CA2178647C - Defrost control device and method - Google Patents
Defrost control device and method Download PDFInfo
- Publication number
- CA2178647C CA2178647C CA 2178647 CA2178647A CA2178647C CA 2178647 C CA2178647 C CA 2178647C CA 2178647 CA2178647 CA 2178647 CA 2178647 A CA2178647 A CA 2178647A CA 2178647 C CA2178647 C CA 2178647C
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- refrigerator
- power consumption
- recited
- time
- control
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
- F25D21/002—Defroster control
- F25D21/006—Defroster control with electronic control circuits
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/15—Power, e.g. by voltage or current
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2117—Temperatures of an evaporator
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D2400/00—General features of, or devices for refrigerators, cold rooms, ice-boxes, or for cooling or freezing apparatus not covered by any other subclass
- F25D2400/04—Refrigerators with a horizontal mullion
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D2700/00—Means for sensing or measuring; Sensors therefor
- F25D2700/12—Sensors measuring the inside temperature
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D2700/00—Means for sensing or measuring; Sensors therefor
- F25D2700/12—Sensors measuring the inside temperature
- F25D2700/122—Sensors measuring the inside temperature of freezer compartments
Abstract
A device and method is provided for automatically defrosting a refrigeration system. The present invention includes a microprocessor (102) which initiates a defrost cycle during a time of day which is most efficient for the refrigerator (50) and the utility company. Moreover, the defrost cycle is initiated during a time of day which has the least impact on food stored within the refrigerator (50). The microprocessor (102) is programmed and enabled so as to analyze the power consumption of the refrigerator during a 24-hour period, and from this analysis, the microprocessor (102) is able to determine the time of day and period(s) of time which will be most efficient for the initiation of a defrost cycle.
Description
21 73~47 DEFROST CONTROL DEVICE AND METHOD
BACKGROUND OF THE INVEN~ON
1. Fleld of the In~ention The present invention relates to rec~ nti~l refrige~ti- n systems and more particularly relates to a device and method for ~ u~ l;r~lly calr~ ting and~Ic~ ...;n;..g when a defrost cycle should be ;n;l;~tP~ in a l--f.;g., Al;nl- system.
15 2. DL~ tion oftheRelated Art A refrig~tor typically is provided with a defiu~Ling control system for removing frost which has a^r,um~ t~ on the e~A~ AI~r coils of a refrigeratnrduring a cooling cycle. A typical deLu~Lil~g control system is illll~n~ll~ in FIG.
20 l . and generally in~ ludes a motor driven switch timer (l0) which effectively counts the cl~m~ tive running time of a co,-",lc~sor (12) so as de~ . ,..;"r when the cooling cycle is to be ~~ f~ so as to initiate a deLu~ g cycle. The refrigerator circuit, int~luAing the motor driven switch timer (l0), is activated when a freezer ~.~ atu~ control switch (16) closes, caused generally by the ~5 refrige~ator having a storage c~llly~Llllcnt tf.~ above a presrnbe~ value.
~nen swi~cn (16) opens, the reTrigf~rator is in effe~t 0II. A aefros; nealer (l '~ is provided for thawing the frost arcllmlll~tf~ on the evA~ o~ coils (not shown) along with a defrost tf, .,.;n~lo~ (18) for ~If~t~tinv the t~ w.,~lllf~ of the e~d~dLu 30 coils so as to disable the en~,lE~dLion of the defrost heater (14).
WO 95/16172 2 1 7 8 6 ~ 7 PCT/US94/14154 The defrosting operation is controlled and carried out periotlir~lly by the motor driven switch timer (10) which is typically detArhAhly coupled to the control ci~cuill ~ of the refrigerator at quick-connPct terminals to f~rilit~t~o.
5 re~ emPnt if npr~pccAry. The duty cycle of refrigeration to defrost is fixed by the refri~e~Atnr m~nl~fact ~rer and impl~PmPnteA i~ the motor driven switch timer (10), with ~enP.~lly six hours of cooling to thirty ...;.~ es of dt;~lc,sling. There are no adju~ n~c to compPnc~tP for ~rA,;AI;nnc in the opcldLing env..o....~ t, and as such 10 the same ratio is used in a refrigerator disposed in Alaska as COIllp~C~ to a refri~P~tor used in Florida.
In operation, when the freezer Ir~ AI~ ; control switch (16) closes, the cooling cOIll~l~ ssor (12) is activated, and the c~m~ tive rUMing time of colllpl~r (12) is count~d by the motor driven switch timer (10). After the coll,l.l~sor (12) has been energized for a prescribed period of time, such as, e.g., six hours, the motor driven switch timer (10) ~ Ply dc en~ es the co,llpl~sor (12) and consequently ene.~s the defrost heater (14) through the provision of an internal switch (lOa). The motor driven switch timer (10) ~ thereafter enabies the defrost heater (14) to be enel~i~ed when the derrost ~.,llinator (18) is in a closed position- Typically, the defrost lc.ll,inator (18) will be in a closed position when the le",.~,dtu~e of the evaporator coiis are beiow a prPs~ihed value (e.g., 20F). In particular, the motor driven switch timer (10) ~, enables the defrost heater (14) to be energized only during a defrosting dulv cvcie wnich is.tvDicallv 2 thiily minute per.od which is Dresc ibed bv the motor {inV'.
swiuh timer (10). While the defrost healer (1.) is energized. any frost on tne evd~oldlol coils are grad~ ly thawed by radiant heat from the defrost hea~er (1.).
30 The accumulation of ice and frost on the e~a?oldtor coils restricts the coiis from drawing heat out of the food co",L)a,L",ent since the ice acts as an insulator, thus lowering the efficiencv of the coiis, and consequently, the refrigerator. In 3, WO 95/16172 2 ~ 7 ~ 6 ~ 7 PCT/US94/14154 accordance with the energization of the defrost heater (14), the l~,n~,,.ll"c of the evdpoldlor coils gradually rises. In this time period, (such as, e.g., a half hour) the defrost tPrrnin~t~r (18) detects the te~ )cldL~lre of the evdpcldtor coils. When the ~llpeldLulc of the e~d~ld~u coils reaches a ~ ;he~ value, (such as, e.g., 50F) the defrost ~ Il.inato- moves to an opçn position and the defrost heater (14) is dce.l~ d, ~ll~ the cc"l.~aor (12) is r.n~l-ed to an o~ .,.I;~-n~l state by the motor driven switch timer (10) after the half hour duty cycle of the defrost 10 heater (14) has expired.
In typical refrigerdtor control systems, such as i~ Ct~ted in FIG. 1, the motor driven switch timer (10) only Upe,~d~L;S when the refriE~ tor~s settable freezer l~ r~ "~c control switch (16) is closed (usually when the tc,~ dtulc in the storage colll~~ nt of the ,crliE,_,aLur is above a ples- ~;he~
e.g., 50). As illu~ in FIG. 2, a defrost cycle must always i~ pL and a-lpe.scde a cooling cycle. Further, the cooling cycle may not be l~
(illc~ lless of the position of the defrost ~ll,lir,aLur (18)), until after the defrost duty cycle, as pres~rihed in the motor driven switch (10), has expired. FIG. 2 20 illustrates a refrigerator energy co~sllmption ~raph including a defrost cycle cnncicting of thirty ~ t~s which comprises regions (2) and (3). Only after expiration of the defrost duty cvcle, may the motor driven switch timer (10) initiate a cooling cycle, as indi-~t~ by regions (4),(5) and (6) in FIG. 2, and as ~, seen, during region (3) the refrigerator is effectively off.
The above defrost scsiem is disaavan~a~es i~. tnat tne de,ros. cyc -is oniy iniri~t~ by the interrupuon ana conseauent ~e;ll.inddon OI a cooiing cvci~.
This results in a nigh energy consumption by the refriger~ror along with the 30 ~evr~ tiQn of food stored within the refrigerator. In particular, the reîrigerator concllm~s a large amount of energy since the compressor mus~ not only lower the ~ x,drure of the stor~e c~lllp~.lllent to below a prescribed ~m~-dture. but 2 i 78647 must now ~ition~lly compencAtP for the further rise in co-,-p~,--ent temperaturewhich is attributable to the defrosting cycle. Thus, the further rise in the co...pd~ .ent ~ ' Al~ e along with the longer time period ~uiled by the 5 cc...~,~sor to lower the co...l,~L-..ent tÆ ~.l~JAI~e, gives rise the ~eg~tiorl of food which may be stored within a storage ~--p~ul--,~ nt of the refrigerator.
Furth~llllole~ it has been found that there are a greater number of cooling cycles, and cooling cycles of longer du~ on, l~uin~ during times of 10 high ambient ~ .AI~ s and high door opening activity, (e.g., dinner time during a hot humid day in August) and less cooling cycles during lower Amhj~Pnt 1~lAI~ S and low door opçnin~ activity, (e.g., 3 a.m. in the ..,-~,..in~).
The.~le~ the ~ tin~ defrost scheme utilized by refri~, . A~u~ ~ tends to drive 15 initiAtion of a defrost cycle toward the power utility's peak load period.
~Aditinn~lly, more cooling cycles and cycles of long dl---Ation are lc luilcd during brown outs or i~ ly following a power outage, and lL~ ~ folc, a high probability of a defrost cycle being ir.;l;~t~ exists at those times. Thus, there is no rPlAtio2lchip of initi~tion of the defrost cycle as to the amount of frost on the 20 e~dpold~or coils, since the defrost cycle is not altered based on how much ice is melted, and the initi~tion time of the defrost cycle is unrelated to the needs of the power utility co~ )dny.
A typical eY~mple of the above method is disclosed in U.S. Patent ~; No. 4,528,821 to Tershak et al. wherein the defrost cycle is PYP~utPA while the operation of the cooling cvcle is swilched from the "on" srate to the "ofr" s~ate o-auring a period when the ~ell~p~ .dLLIre within tne refrigerator is al tne upper ena or its range at which foods deteriorate.
A still further type of defrost control is rlic~locp~d in U.S. Patent No 4,251,988 to Allard et al. This defrost control is .cÇ~ d to as an "adaptive"
defrost control since it establishes the time between succe~nin defrosting cvcles as 3;
wo 95/16172 2 1 7 ~ ~ ~ 7 PCr/Uss4/l4l54 a function of the length of time that the defrost heater was cnc~ ed during the first defrosting cycle. Another type of adaptive defrost control is r~icrlose~ in U.S.
Patent No. 4,481,785 to Tershak et al. This adaptive defrost control varies the 5 length of an interval between defrosting cycles in accol~lance with the number and ;on of C~ llC,~ door opçnin~c~ th~ tion of a previous d~,rlu~L~ng cycle as c~ cd by the ~ t of the e~,dpc~ldLor coils prior to a defrost cycle and the length of time the co,l.p~r has been en~.~,i~d. However, the d~l~ h-~
10 of the nu"lbel and dll~tion of refriger~tc r door openings does not result in an entirely accurate ~ l;nn of the amount of frost which has formed on the e~ or coils due to the moisture introduced into the refrigerator while the refrigerator door is open. Ac~ç~ingly, this results in a less-than-optimal defrost 1 ~ interval.
Thus, a common disadvantage with prior defrost systems is that thev do not initiate a defrost cycle during an optimal time period according to the energy effi~iency of the refrigerator, the peak dem~nrl loading needs of power utility co~ nir~ and the de~tiQn of food caused by a defrosting cycle being 7 initi~t~d during a warm ambient l~,.,p~ldL-lre period.
F~ ,lllore, the above mPntionçd adaptive defrost controls are unable to be readily adapted for retrofit into eyicting rerrigerator control svslems.
Rather, the control cil~uitl~/ of refrige.d~ols must be de~i,ned and configured for ~, the impl~",er.LdLion of such adaptive defrost controls.
~ ccordinvi~!. the-e e~is;s a need tC ?rovide a de.;.os; svste--. -..,a; ~
conserve energy and preven~ the degradation OI IOOd DV initi~ring a deîros~ cvcie during an optimal time period which is most energy efficient after the compietion 30 of a cooling cycle.
WO 95/16172 2 1 7 8 6 ~ 7 PCTtUS94/14154 It is an object of the present invention to initiate a defrosting cycle in a refrigerator during an off-peak demand period of utility co...l~AniPs which is most energy effi~ ipnt for the refrigerator while also preventing the degradation of 5 food stored within the rPfrigerAtor.
Further, there exists a need t~rovide a defrost control system that is configured to be readily ^~ te~ into ~l~icting refrigcidtola while being simple and inl l~r~C;~e to ~ nu~Arl~c.
SUMIVIARY OF T~IE INVENT~ON
GenP.rAlly, in a refr ~er~tion system, a co~ aul provides for cooling the food co~ a~ nt in conjullclion with e~,a~uld~or coils which draw heat out of the food collll~LIllent to assist the collllll~sor in the cooling function.
During cooling, frost and ice tend to arcum~ te on the e~dpold~or coils which dec,e~ses the effiri~nry of the refrigerator. It is desirable to defrost the ~rcum-~l-AtP~ frost and ice only as often as is nece~A, y to IllA;lllAIn an efficient 20 coo~ing system. This objective dictates that a balance be struck between the CG-~ g conci~p~tionc of system operation with frosted e~d~ldtol coils, the energy conc~)me~ in removing a frost load from the evaDorator coils and the acceptable level of ~ d~ul~; fluctuation within the refri_erated food 25 compartments as a result OI a defrosting operation.
T c ac_ompiish tne ODie'lS desc ibed abo-~e. Ihe ?resen. inventior provides a novel derrost controi device whicn is tiimP~cioned and configured so as to be ~et~rh-Ahly env~gP~d with the refTigeration colllponents of a commerciallv30 avaiiable refrigerator. Typically, a commercially available refrigerator comprises at least one enclosed co,llp~llllent for storinv ilems, such as food. Means for cooiing the at least one enclosed coll~p~u.lllent. such as a coll-u-essor and wo 95/16172 2 1 7 3 ~ 4 7 PCT/US94/14154 evaporator, are also typically provided. Additionally means are provided for heating the e~dpoldtol, (i.e., a defrost heater) so as to remove ~rrum~ t~ frostfrom the e~d~vldtol.
5 The novel control device is configured so as to initiate a defrost cycle, wllcr~y the initi~ticm of the defrost cycle is respcnsive to the daily power conC~mrtion of the refri~-Ptnr. In particular, the control device of the presentinvention inrludes a miclu~,l~sol which is ~l~plu~ .llll~ with a Illz~ t;r~l 10 scheme so as to deh~ ine the time of day without the usage of clock by analyzing the energy CQn~ ~ Iplion of the refrigeT~tor during a 24 hour period.
By rle~ g tne d~lu~ tP time of day, the mi.,lu~,locessor is enabled to initiate a defrost cycle during the off-peak energy power corlc Ill~lion time of the local utility co~ any. This is advantageous since the off-peak energy power c~ncllmption time typically cQinri~S with the time period collc~l,ùnding to the period of least usage of the refrigePtor (the upening and closing of doors).Further, this time period coincides with a relatively low ambient ~llpcld~ e which the refrigerator will be CA~Os~ to during a 24 hour period. Thus, the 2C initiation of a defrosting cycle during this time period conserves energy while also having the sm~ st impact on food stored within the refrigerator. The miclû~luces~or can ~nncip~te the initiation ûf the next cooling cyciing startin~ a defrost cycle just prior to the preAir~t~d start thus, a cooling cycle will never be 7~ imerrupted. Furthermore. the miclùp~ùcessor constantlv monitors the opeldLing,~.e~uorlc~ of tne de~ os~ hearo- so as to ensuro that a de~ros; cvcie is oni~ .iate~
when i~ is needed and oniy durin~ a time perioci wnicn is most efficien~ for ~herefrigerator and the local utility co-~-pany.
BRIEF DESCRIPI'TON OF THE DRAWINGS
Further features of the present invention will become more readily S apparent from the following det~ d description of the invention taken in conjunction with the acco,l,y~lying drawings, in which:
FIG. 1 is a ~imrlifi~d srh~om~tic circuit illl)str~tin~ a refrige,r~tor circuit ~ltili7in~ a prior art defrost time which is used to defrost the refri~P~tr)r;
FIG. 2 is a graph illustrating the energy co~cumption of a refri~P~tor having a circuit using the prior art defrost timer of FIG. 1;
FIG. 3 is a ,u~ l;ve view of a refri~or~tor in partial cut-away t;~g c~ one,l~ of the refrigerator with which the present invention is used;
FIG. 4 is a Sc`hp I~I;C circuit ~ m ;11115l1~ Cr a defrost control system according to the present invention; and FIGS. 5-12 are flow charts eYpl~inin~ the operation of the micro~l~cessor of FIG. 4.
7 DETAILED DESCRIPrION OF T~; PRE~RRED EMBODIMENT
Referring now to FIG. 3, there is iliustrated a refrigerator 50 within which the present invention is inttonded to be used with. Generally, such a 7~ refrigerator 50 includes a fresn food col",ualL",ent door 52 and a frozen food ccj~llL)dlLI~le.~l. acor 5- whic;~ are Divotabiv connecle~ IO a boav poruoll. 56 whic.-deImes. l~sue,-Liveiy. a fresil fooG co,l, dl-ll,ent 58 anci a f-rozen rood co""pdl"llen 60.
The lc~ue~;Live food co,l,l)dl.",ents 58, 60 are refrigerated by passing refri~erated air therein which is cooled by a cooling dUUdldL~lS which comprises an evdpcjldLur 62, a co"lvressol 6. and a condenser 66. The cooling duU~dtLIS aiso W095/16172 9 21 78~A7 PcTluS94/14154 inrl~ld~P5 a CQn~PncPr fan, an evaporator fan and a heater or arcllmulAtor (not shown), as is conventionAl.
The evd~oldLor 62 is periodically de~losLed by a defrost heater 68 5 which is to be o~ld~cd by the control of the present invention. The defrost heater 68 may be configured as of the or~ hy resL~ive type or may be configured as any other type of heating e1~ .l nt configured to acco~ lish such a task.
A ~ IA~ sensing device generally in the configuration of a 10 defrost t~ h~lol 70 (such as, i.e., a thermostat) is ~icros~l in heat-tlansfer rPlqtinnchir with the e~Al~-..A~or 62. More crerifirAlly, the defrost lclll~rLato- 70 is mountP~ directly on the evd~,d~l 62 as to detect the te~i~ Au~c thereof.
Ad~itionAlly~ at least one te~lllh,lAIll~c control switch (not shown) is utilized in at least one food ~Ill~A~ h~ent 58, 60 so as to detect the ~r-~.l~- A~ e of one or both of the ~ re food COIll~ lc~ 58, 60.
Tun~ing now to FIG. 4, there is illuct~AtP~ a ~hP-..AI;r, circuit tiiAgT7m of the control system 100 according to the present invention, which is con~ clcd to replace the prior art elc. Llo,..~rhAnirAl time (1) as shown in the20 circuit of FIG. 1. The control system 100 is preferably nicpoS~pli within the body portion 56 or outside of the body portion 56 of the refrigestor 50. As describedin more detail below, the control 100 is confivured to ~et~rh~hly engage with the above-mentinnPd co.ll~n~ nts of an existing refrigestor 50 (FIG. 3), such as that 2, shown in FIG. 4 and srhPn-~tir~lly depicted as block 101.
m general. the control 100 comprises a microprocessol 10; to~om.o-with circuitry for conlroiling the Co~ S50~ 6~ and the defrost hea~e- 68 OI the re~igestor 50. The mi~lup~..cessor is provided with a clock input 103 conn_urea 30 to connP~t to a clock source, such as an oscill~tor, as is convçnbnn~k The various co-,.yonent~ of the control 100 illllctrat~d in FIG. 4 receive DC volt-dge from a rectifier 103 which is directly courlçd, via line 104, to an AC voltage source. In particular, the AC voltage source may origin~te from 5 the power circuitry of the refri~e~tor S0 or from any other source, such as a convention~l wall outlet. A filter ayi)d dLus 106 is courl~ to the l~iLc~ 103 soas to reduce the ripple of the terminal voltage from the rectifier 103, and ~ ltlitirn~lly, to smooth out any voltage surges being c~rr~~ ~ from a 1 0 colnplessù~/defrost relay 108 being coupled in parallel rel~tionchir to the filter 106. The c~lllyl~/defrost relay 108 cQmprictos a dry switch 134 and a relay coil 136, the ci~nifir~nre of which will be ~ rihe~d in greater detail below.
A solid state relay control 110 couples to the filter ~ ..c 106 and to the colllyl~sorldefrost relay 108. The solid state relay control 110 is configured to either ene-y.2e or dc e.~ e the cc,lllyle~ ,or/defrost relay 108 upon a CGlll~ signal which is Ejen~ ~t~d from the out~put tennin~l 120 of the mic~u~loce~sor 102 which is coupled, via line 112, to the solid state relay control 110.
The miciu~luccssor 102 is powered by line 114 which is coupled to the so}id state relay control 110. A æner diode DC regulated power supply 116 isprovided in line 114 so as to regulate the voltage between the solid state relaycontrol 110 and the input supply voltage terminal 118 of the micr~r~cessor 102.
An input terrninal 122 of the miclo~lucessol 102 is coupled, via line 126. to a f~ter and peak detector 124. The filter and peak detector 124, via line 128, is coupl~ to a toroid transformer 130. As will be d~srrine~ in grea~er de~ail below, the filter and peak del~lol~ 124 provides the mi- luylùcessor 102 with the 30 infolll,a~ion which in turn is utilized by the miclûplvcessor so as to formulate when a defrosting cycle is to be initi~tPd in the rerrigerator 50.
3~
-WOgS/16172 2 17864 7 PcT~us94/l4l54 The toroid tran~l.ner 130, via line 132, is in el~rtr~
communi~tinn with an AC switched line voltage supply of the refriger~tor 50.
Sperific~lly, the AC switched line voltage supply, via line 132, provides an 5 ene.~iLi-lg current when the ~ .c control switch of the refriger~tor 50 is in a closed poCitinn. Typically, the ~ .pr~ e control switch is in a closed pociti~nn when a ,~h~e food cc,l,.palhllcnt 58, 60 of the refrigprator 50 has a te~ e which is greater than a pre~rihed value (such as, e.g., 30F).
10 Conversely, when a ,~ /e food c~lllydlhllent 58, 60 of the refri~Pra~or 50 has a ~ c which is less than the above ,..~ ;nnf~i y~c~, ;he~d value, the lC...~,atu.e control switch moves to an open ~5;l;on SO as to prevent an ene.~ iLillg current to flow from the AC switched line voltage supply to the line 132 of the control system 100.
As rnPnti~n~P~ above, the colllp,~ssor/defrost relay 108 compriCPs a dry switch 134 and a relay coil 136. The line 133-is coupled to the dry switch 134. The drv switch 134 is configl-red to be ~ctu~hle by a co.,l",and signal from the miclul"~r 102, via the relay coil 136. The dry switch 134 is ~ hl~
20 between an activated position and a de-activated position. When the dry switch 134 is de-activated, it effectively couples the AC switched line voltage supply by line 135 to the col~ly~essor 64 of the refrigerator 50. Conversely, when the dryswitch 134 is activated, it effectively couples the AC switched line voltage supply 2~ by line 137 to the defrost heater 68 of the refrigerator 50. It is particularly noted that the dry switch 134 mav onlv be switched from the de-activated position tO the activated position when the colllylesior 64 is not energized (generally when a ~--~y~;-dlu'e controi switch is riicposed in an open position, as mentioned above).
The toroid transforrner 130 is configured to sense the flow of ~ne,~ g current, via lines 132 and 133, from the AC switched line voltage supply of the refrigerator 50 to the dry switch 134 of the CO"Iy.~ ~sol/defrost relay 2i 78~47 108. Thus, when the tc,l,~,dture control switch of the refrigerator 50 is disposed in a closed pOcitiO~l~ the toroid transformer 130 effectively detects the flow of energizing current from the AC switched line voltage supply, via line 132, to 5 either the COIllpl'~,SSOr 64 or the defrost heater 68, ~nr~ing upon the position of the dry switch 134. The toroid transformer 130 couples this sensed crle~ ng current flow, via line 128, to the filter and peak dc~;lor 124.
The filter and peak det~tor 124, via line 126, is coupled to an input 1 0 terminal of the mi~;luplvcessol 102. As will be lic~ ccpd in much greater detail below, the micluplocessor ~,vcesses this received infol",~Lion from the filter and peak ~et~t~r 124, and subsequently formulates when it is most effi~ nt to initiate a def~ g cycle in the rPfri~P~tor 50.
When the micl~lvcessor 102 de~,lllines that a defrost cycle should be initi~t~ an "ON" signal is sent from the output terminal 120 of the miclol,lucessor 102 to the solid state relay control 110. The solid state relay control 110 relays the "ON" signal to the relay coil 136 of the cc ",~ ssor/defrost relay 108 which erl~l"~- s the dry switch 134 to be "activated"; thereby en~hting 20 the AC switched line voltage supply to be coupied to the defrost heater 68 of the refrigerator 50.
In contrast when the mic,op,ucessor 102 determines that the defrost cycle is to be terrnin~ted, an "OFF" signal is sent from the output terminal 120 of 2~ the mic~up,uc~ssor 102 to the solid state relay control 110. The solid state relay control 110 relavs the "OFr" signal to the relav coil 136 of the co,l~p,cssoridefros;
reiay 108 which efIecn~t~s the dry switch to be "de-activated", thereby enabiin~the AC switched line voltage supply to be coupled to the co,llp,L~sor 64 OI the 30 refrigerator 50.
Referring now to FIGS. 5-12, there is illlctr~tPd a flow chart of the proglA~ ufilized the ~lu~lA~..ming of the micloyrocessor for implçmPnting the control of the instant invention.
The microprocessor program starts immPI1iAtPly after the comrlP*r~n of power on reset timing circuit (not shown~
The ~AI Alll. ~ . ~ of APC (Actual Recorded Hourly Power Concump*on), TTDC (Time to Defrost Control), defrost mode, various recorded 10 times, Tdefrost-A~tll-Al, defrost *ime and others not d~Psrrihed, are ini*-Ali7PA (1).
During the first days (e.g. five days) of operation while the yluyOSc~ device isde~- -...;n;nE~ ope~ti~n-Al time of day for the refri~--rAtor, it will operate as a conven*rn~l defrost timer. The defrost period will be fL~ced at an 8 hour co~ly~Dr run time or, if an AltPrn-ASP configuration is j",~ "I .trd, ju",p~
po~i*~nP~ within the micropç~cessor circuity will be read by the micluy~cessor for various common time periods such as 6, 8, 12, and 16 hours. Referring to FIG. 5, a clock in the ~ luylucessol is initially set for zero (step 500) and will start collntinC when a tick occurs after every 5 sP~Qn~l~ of the system clock event.
20 If a tic~ is detectPd, the control system 100 will measure the toroid current sensor 130 and determine if the current in the defroster or co",ylessor has ch-An,,eA state (steps 512 and 514). If no chan .e in the measured current is de2~oc2t-d, the svstem repeats steps 512 and 514 until a current change is deterted. Once a current ~, change is detect~d, the frost mode fla, is read to determine if the change detected occurred in the defros; heate- or the co~Julcssor (ste?s 516 anc 51~). If tr.~
defrost mode fla~ was set the defrost process of FIG. 6 is yc~ful~l~e~ (sle? 5~0).
The defrost process, illustrated in FIG. 6, is imple~ented such that 30 the control system records the defrost time, as referenced to the clock ticks (step 610) and re~ds the toroid current sensor 130 to de~l",il e if current is sensed (step 620). If current is sensed, the time recorded was a defrost start and the defros;
WO 95/16172 ~i 1 7 8 6 4 7 PCT/US94/14154 process returns to the main loop (step 620 of FIG. 6 and step 520 of FIG. 5). Ifno current is sensed by the toroid current sensor 130, the time recorded was a defrost ~c~ ;nsl;on requiring the defrost mode flag to be cleared (step 630) and the 5 dry switch 134 of the common relay contact 108 is s~viLche~ to activate the eu~ lessol (step 640) so that the next time ~he refrigerator t~ G control supplies power to the Commorl relay contact 108 the u~ ,l~r will actuate.
Once the relay 108 is switched, the defrost process returns to the main loop at step 1 0 520 of FIG. 5.
Rf turnin~ to step 518 of FIG. 5, if the defrost mode flag is not set (step 518), the cc~ pl~sOr process is pe.rorll-cd (steps 518 and 522). The COlllpl~SSOr process is ill~ .4tf~ in FIG. 7 and compricf s the steps of lecor-ling the time, (step 710) as being lefel..nced to the clock ticks. The current sensor, (step 720) is read to de~....inc if current is sensed. If current is sensed, time is ,ecol~cd as a colllpl~sor start (step 720) and the co-,-p~:,or process returns to the eommc-n loop of FIG. 5 (steps 518 and 522). If no current is sensed, the time recorded is of comp.~s:,or power cons~lmption being termin~tf~d ~step 730). The 20 APC memory array cont~inC a 24 hour record oî averaged power concumrtion.
The APC is updated with smoothing (step 740) by adding a perccr ~ge of the latest co~ lc~aor power concumption to the comple~nf~nt~rv pe,.;cn~ge K1 of the averaged power conc~mrtion for the r~s~Li-/e time period. The TTDC counter is 25 declc,nf.-ted (740) by an amount equal to the stop time minus the start time (colllplcs~or on duration!. The TrDC counter is se~ to 8 hours. as wouid be _ convention~l time.. during the convenrion~l derrost program operation. O~ner times may be sPlf rted if the alternate jumper configuration (not shown) is used. If 30 the TTDC has expired, (step 750) the relay is switched to the defrosl position (step 760) and a defrost will be initi~tf~d the next time the ~e",pcldLu-e control supplies power to the relay common terminal. If the TTDC has nol expired~ the pro~r~n wo 95/16172 ~ ~ 78 6 ~q 7 Pcr/Uss4ll4l54 will not allow initiAtion of defrost at this time and ~ rogram returns to the common loop (steps 518 and 522).
Retllrnin, to FIG. 5, if the clock has not ticked (step 512), the 5 I)luglA~l, deLe.,~ es if a Continuous Next Step Time of Day (524) is required.Turning to FIG. 8, the Present Hour ComrlPt~ Flag is tested to 5~ ,....n~ if allrAlr~ tinnC for the present hour are comrl~ (step 810). If not, another single el~ment of the 24 el~ t typical hourly power concumption is :~ubh~c~ed from an 1 0 rl~ ....~n~ of the 24 c~ actual Pl' -"'P~ power concumrti~n array (step 820), the result squared and added to a running sum for the ~ e time ~k ,.. nt This function (step 820) is the c~lrul~tion of at least mean squares fit, also l~f~lcd to as a correlation, of a mAth~m~tirAl ~ 5~..tAtion of the typical hourly power S conC--mrtion eYp~c~ of a typical refrigerator in a typical family rec~ nce to that of the refri~tor cor lA;nin~ the device lO0 of the present invention.
As there are 24 by 24, or 576 c-Alrul-A*onc~ only one c~lr~ tion is ~iull~lecl per pass through the loop. If all 576 cAlculAtinnc are not complete (step 830) the ~lu~ l retums. If all are complete the l)logl~ll oAlr--~At~s the time of 20 day by adding the hme offset determined (step 820) to the cloclc (step 840). The present hour complete flag is set (step 850) and the plu~ ll retums (step 526).
Referring to FIG. 8, if the Present Hour Complete Fiav is set. there will be no more cAlcu1Ations until a new hour occurs (step 860). At the start of a ~5 new hour the indexes for the 576 c~lCUlAtionS are initiAli7tod (step 870). the Presen~
Hour Compieto Fiac is cie~red (sl? 880~ and tho prov;am returns to tne common loop (step 526).
R~ rninv to FIG. 5, as the amount of C0111~1~5501 power 30 concumption data increases, the e~l;r..AIrs of time of day will become closer to actual. When the error corrections to time of day become small (step 526), and the refrigerator is not in defrost mode (step 528) and there is sufficient time (ste~
WO 9S/16172 ~ 1 7 8 6 4 7 PCT/US94/14154 530) until the middle of the off peak period, about 3 AM, the prograrn is allowed to calibrate the defrost operation to determine the therrnal overhead, as illustrated in FIG. 9.
Referring to FIG. 9, the calibration process r~u~ s two defrosts closely spaced. The process is ~ ;~d by a CALLOOP count (step 902). The first defrost is set to occur at 1 AM (step 906). While waiting for the defrost to occur, the clock ticks (step 910), sensor change (step 912) time of day calc~ ~in 1 0 (step 914), defrost (steps 916 and 920), cGI~pl~ ssor (step 918) are uti~ized similarly to those in conventio~l opPr~tion mode (steps 512, 514, 518, 520 and 522). However, when the 1 AM defrost has comrletçd (steps 922 and 924), CALI OOP is dccl~ -..r n~ to allow setup of the 5 AM defrost (step 908). Since only 4 hours of ul~u---ably little refrigeration activity exist between 1 and 5 AM, little frost should occur on the ev~roT~tin~ coils and the ev~r7~tinn tf ~
should be predictable. thus, the --lsuled defrost time at 5 AM will be almost co...~letely the thermal overhead of the defrost process (step 926) without ice. The ideal defrost time for the particular refrigerator is e,l;.~ ed to be the thermal ~ overhead times a factor (step 928) ~reater than 1. The next defrost is sched~led to occur at 2 AM (step 930) and the ~lu~r~,l enters the process of FIG. 11.
Referring to FIG. 10, an alternate impiemrnt~tinn is implemrntrd DV
reading jumpers (step 1002) which directs the ~rog~dlJ- to read predetermined 25 values of ideal defrost time (step 1004). The l-lL)C is set to 2 AM (1006) the two caiibralion derros~s are no~ re~uired and the provrarn enlers the process of FIC-.
li.
Ref~rinv to FIG. 11, the clock tick (step 1102) sensor chanve (slep 30 1104), defrost mode (step 1106), process defrost (step 1110) and process co,l.ul~:ssor (step 1116) are all similar to those previously described. The TIDC is r~lrul~trd (step 1114) at the end of eacn defrost (step 1112). Referrinv to FIG.
wo gS/16172 Zl 7~6 4 7 PCT/US94114154 12, the different of the actual defrost time and ideal is an error value (step 1202).
If the error value ED is very large (step 1204), then p,e~l.llably a lot of ice was on the evdpold~ol coils and three defrosts (step 1212) are lc~luh~d per day.
Simil~rly, if the error is large (step 1206), two defrosts (step 1214) are required;
the error is small (step 1208) one defrost is lequired (step 1216); the error is less - than small (step 1210), defrost is every other day.
While the inven*on has been particularly shown and dpcrrihe~d with 10 lt;f~,e,lce to the ~er~ d embo~ nlc~ it will be understood by those sl~lled in the art that various m~lifir~*rnc in form and detail may be made therein withoutdeparting from the scope and spirit of the invention. Ac~or~ingly, mo~ifir~tionssuch as those s~-~gectP~ above, but not limited thereto, are to be comil1P~ed within the scope of the invention.
BACKGROUND OF THE INVEN~ON
1. Fleld of the In~ention The present invention relates to rec~ nti~l refrige~ti- n systems and more particularly relates to a device and method for ~ u~ l;r~lly calr~ ting and~Ic~ ...;n;..g when a defrost cycle should be ;n;l;~tP~ in a l--f.;g., Al;nl- system.
15 2. DL~ tion oftheRelated Art A refrig~tor typically is provided with a defiu~Ling control system for removing frost which has a^r,um~ t~ on the e~A~ AI~r coils of a refrigeratnrduring a cooling cycle. A typical deLu~Lil~g control system is illll~n~ll~ in FIG.
20 l . and generally in~ ludes a motor driven switch timer (l0) which effectively counts the cl~m~ tive running time of a co,-",lc~sor (12) so as de~ . ,..;"r when the cooling cycle is to be ~~ f~ so as to initiate a deLu~ g cycle. The refrigerator circuit, int~luAing the motor driven switch timer (l0), is activated when a freezer ~.~ atu~ control switch (16) closes, caused generally by the ~5 refrige~ator having a storage c~llly~Llllcnt tf.~ above a presrnbe~ value.
~nen swi~cn (16) opens, the reTrigf~rator is in effe~t 0II. A aefros; nealer (l '~ is provided for thawing the frost arcllmlll~tf~ on the evA~ o~ coils (not shown) along with a defrost tf, .,.;n~lo~ (18) for ~If~t~tinv the t~ w.,~lllf~ of the e~d~dLu 30 coils so as to disable the en~,lE~dLion of the defrost heater (14).
WO 95/16172 2 1 7 8 6 ~ 7 PCT/US94/14154 The defrosting operation is controlled and carried out periotlir~lly by the motor driven switch timer (10) which is typically detArhAhly coupled to the control ci~cuill ~ of the refrigerator at quick-connPct terminals to f~rilit~t~o.
5 re~ emPnt if npr~pccAry. The duty cycle of refrigeration to defrost is fixed by the refri~e~Atnr m~nl~fact ~rer and impl~PmPnteA i~ the motor driven switch timer (10), with ~enP.~lly six hours of cooling to thirty ...;.~ es of dt;~lc,sling. There are no adju~ n~c to compPnc~tP for ~rA,;AI;nnc in the opcldLing env..o....~ t, and as such 10 the same ratio is used in a refrigerator disposed in Alaska as COIllp~C~ to a refri~P~tor used in Florida.
In operation, when the freezer Ir~ AI~ ; control switch (16) closes, the cooling cOIll~l~ ssor (12) is activated, and the c~m~ tive rUMing time of colllpl~r (12) is count~d by the motor driven switch timer (10). After the coll,l.l~sor (12) has been energized for a prescribed period of time, such as, e.g., six hours, the motor driven switch timer (10) ~ Ply dc en~ es the co,llpl~sor (12) and consequently ene.~s the defrost heater (14) through the provision of an internal switch (lOa). The motor driven switch timer (10) ~ thereafter enabies the defrost heater (14) to be enel~i~ed when the derrost ~.,llinator (18) is in a closed position- Typically, the defrost lc.ll,inator (18) will be in a closed position when the le",.~,dtu~e of the evaporator coiis are beiow a prPs~ihed value (e.g., 20F). In particular, the motor driven switch timer (10) ~, enables the defrost heater (14) to be energized only during a defrosting dulv cvcie wnich is.tvDicallv 2 thiily minute per.od which is Dresc ibed bv the motor {inV'.
swiuh timer (10). While the defrost healer (1.) is energized. any frost on tne evd~oldlol coils are grad~ ly thawed by radiant heat from the defrost hea~er (1.).
30 The accumulation of ice and frost on the e~a?oldtor coils restricts the coiis from drawing heat out of the food co",L)a,L",ent since the ice acts as an insulator, thus lowering the efficiencv of the coiis, and consequently, the refrigerator. In 3, WO 95/16172 2 ~ 7 ~ 6 ~ 7 PCT/US94/14154 accordance with the energization of the defrost heater (14), the l~,n~,,.ll"c of the evdpoldlor coils gradually rises. In this time period, (such as, e.g., a half hour) the defrost tPrrnin~t~r (18) detects the te~ )cldL~lre of the evdpcldtor coils. When the ~llpeldLulc of the e~d~ld~u coils reaches a ~ ;he~ value, (such as, e.g., 50F) the defrost ~ Il.inato- moves to an opçn position and the defrost heater (14) is dce.l~ d, ~ll~ the cc"l.~aor (12) is r.n~l-ed to an o~ .,.I;~-n~l state by the motor driven switch timer (10) after the half hour duty cycle of the defrost 10 heater (14) has expired.
In typical refrigerdtor control systems, such as i~ Ct~ted in FIG. 1, the motor driven switch timer (10) only Upe,~d~L;S when the refriE~ tor~s settable freezer l~ r~ "~c control switch (16) is closed (usually when the tc,~ dtulc in the storage colll~~ nt of the ,crliE,_,aLur is above a ples- ~;he~
e.g., 50). As illu~ in FIG. 2, a defrost cycle must always i~ pL and a-lpe.scde a cooling cycle. Further, the cooling cycle may not be l~
(illc~ lless of the position of the defrost ~ll,lir,aLur (18)), until after the defrost duty cycle, as pres~rihed in the motor driven switch (10), has expired. FIG. 2 20 illustrates a refrigerator energy co~sllmption ~raph including a defrost cycle cnncicting of thirty ~ t~s which comprises regions (2) and (3). Only after expiration of the defrost duty cvcle, may the motor driven switch timer (10) initiate a cooling cycle, as indi-~t~ by regions (4),(5) and (6) in FIG. 2, and as ~, seen, during region (3) the refrigerator is effectively off.
The above defrost scsiem is disaavan~a~es i~. tnat tne de,ros. cyc -is oniy iniri~t~ by the interrupuon ana conseauent ~e;ll.inddon OI a cooiing cvci~.
This results in a nigh energy consumption by the refriger~ror along with the 30 ~evr~ tiQn of food stored within the refrigerator. In particular, the reîrigerator concllm~s a large amount of energy since the compressor mus~ not only lower the ~ x,drure of the stor~e c~lllp~.lllent to below a prescribed ~m~-dture. but 2 i 78647 must now ~ition~lly compencAtP for the further rise in co-,-p~,--ent temperaturewhich is attributable to the defrosting cycle. Thus, the further rise in the co...pd~ .ent ~ ' Al~ e along with the longer time period ~uiled by the 5 cc...~,~sor to lower the co...l,~L-..ent tÆ ~.l~JAI~e, gives rise the ~eg~tiorl of food which may be stored within a storage ~--p~ul--,~ nt of the refrigerator.
Furth~llllole~ it has been found that there are a greater number of cooling cycles, and cooling cycles of longer du~ on, l~uin~ during times of 10 high ambient ~ .AI~ s and high door opening activity, (e.g., dinner time during a hot humid day in August) and less cooling cycles during lower Amhj~Pnt 1~lAI~ S and low door opçnin~ activity, (e.g., 3 a.m. in the ..,-~,..in~).
The.~le~ the ~ tin~ defrost scheme utilized by refri~, . A~u~ ~ tends to drive 15 initiAtion of a defrost cycle toward the power utility's peak load period.
~Aditinn~lly, more cooling cycles and cycles of long dl---Ation are lc luilcd during brown outs or i~ ly following a power outage, and lL~ ~ folc, a high probability of a defrost cycle being ir.;l;~t~ exists at those times. Thus, there is no rPlAtio2lchip of initi~tion of the defrost cycle as to the amount of frost on the 20 e~dpold~or coils, since the defrost cycle is not altered based on how much ice is melted, and the initi~tion time of the defrost cycle is unrelated to the needs of the power utility co~ )dny.
A typical eY~mple of the above method is disclosed in U.S. Patent ~; No. 4,528,821 to Tershak et al. wherein the defrost cycle is PYP~utPA while the operation of the cooling cvcle is swilched from the "on" srate to the "ofr" s~ate o-auring a period when the ~ell~p~ .dLLIre within tne refrigerator is al tne upper ena or its range at which foods deteriorate.
A still further type of defrost control is rlic~locp~d in U.S. Patent No 4,251,988 to Allard et al. This defrost control is .cÇ~ d to as an "adaptive"
defrost control since it establishes the time between succe~nin defrosting cvcles as 3;
wo 95/16172 2 1 7 ~ ~ ~ 7 PCr/Uss4/l4l54 a function of the length of time that the defrost heater was cnc~ ed during the first defrosting cycle. Another type of adaptive defrost control is r~icrlose~ in U.S.
Patent No. 4,481,785 to Tershak et al. This adaptive defrost control varies the 5 length of an interval between defrosting cycles in accol~lance with the number and ;on of C~ llC,~ door opçnin~c~ th~ tion of a previous d~,rlu~L~ng cycle as c~ cd by the ~ t of the e~,dpc~ldLor coils prior to a defrost cycle and the length of time the co,l.p~r has been en~.~,i~d. However, the d~l~ h-~
10 of the nu"lbel and dll~tion of refriger~tc r door openings does not result in an entirely accurate ~ l;nn of the amount of frost which has formed on the e~ or coils due to the moisture introduced into the refrigerator while the refrigerator door is open. Ac~ç~ingly, this results in a less-than-optimal defrost 1 ~ interval.
Thus, a common disadvantage with prior defrost systems is that thev do not initiate a defrost cycle during an optimal time period according to the energy effi~iency of the refrigerator, the peak dem~nrl loading needs of power utility co~ nir~ and the de~tiQn of food caused by a defrosting cycle being 7 initi~t~d during a warm ambient l~,.,p~ldL-lre period.
F~ ,lllore, the above mPntionçd adaptive defrost controls are unable to be readily adapted for retrofit into eyicting rerrigerator control svslems.
Rather, the control cil~uitl~/ of refrige.d~ols must be de~i,ned and configured for ~, the impl~",er.LdLion of such adaptive defrost controls.
~ ccordinvi~!. the-e e~is;s a need tC ?rovide a de.;.os; svste--. -..,a; ~
conserve energy and preven~ the degradation OI IOOd DV initi~ring a deîros~ cvcie during an optimal time period which is most energy efficient after the compietion 30 of a cooling cycle.
WO 95/16172 2 1 7 8 6 ~ 7 PCTtUS94/14154 It is an object of the present invention to initiate a defrosting cycle in a refrigerator during an off-peak demand period of utility co...l~AniPs which is most energy effi~ ipnt for the refrigerator while also preventing the degradation of 5 food stored within the rPfrigerAtor.
Further, there exists a need t~rovide a defrost control system that is configured to be readily ^~ te~ into ~l~icting refrigcidtola while being simple and inl l~r~C;~e to ~ nu~Arl~c.
SUMIVIARY OF T~IE INVENT~ON
GenP.rAlly, in a refr ~er~tion system, a co~ aul provides for cooling the food co~ a~ nt in conjullclion with e~,a~uld~or coils which draw heat out of the food collll~LIllent to assist the collllll~sor in the cooling function.
During cooling, frost and ice tend to arcum~ te on the e~dpold~or coils which dec,e~ses the effiri~nry of the refrigerator. It is desirable to defrost the ~rcum-~l-AtP~ frost and ice only as often as is nece~A, y to IllA;lllAIn an efficient 20 coo~ing system. This objective dictates that a balance be struck between the CG-~ g conci~p~tionc of system operation with frosted e~d~ldtol coils, the energy conc~)me~ in removing a frost load from the evaDorator coils and the acceptable level of ~ d~ul~; fluctuation within the refri_erated food 25 compartments as a result OI a defrosting operation.
T c ac_ompiish tne ODie'lS desc ibed abo-~e. Ihe ?resen. inventior provides a novel derrost controi device whicn is tiimP~cioned and configured so as to be ~et~rh-Ahly env~gP~d with the refTigeration colllponents of a commerciallv30 avaiiable refrigerator. Typically, a commercially available refrigerator comprises at least one enclosed co,llp~llllent for storinv ilems, such as food. Means for cooiing the at least one enclosed coll~p~u.lllent. such as a coll-u-essor and wo 95/16172 2 1 7 3 ~ 4 7 PCT/US94/14154 evaporator, are also typically provided. Additionally means are provided for heating the e~dpoldtol, (i.e., a defrost heater) so as to remove ~rrum~ t~ frostfrom the e~d~vldtol.
5 The novel control device is configured so as to initiate a defrost cycle, wllcr~y the initi~ticm of the defrost cycle is respcnsive to the daily power conC~mrtion of the refri~-Ptnr. In particular, the control device of the presentinvention inrludes a miclu~,l~sol which is ~l~plu~ .llll~ with a Illz~ t;r~l 10 scheme so as to deh~ ine the time of day without the usage of clock by analyzing the energy CQn~ ~ Iplion of the refrigeT~tor during a 24 hour period.
By rle~ g tne d~lu~ tP time of day, the mi.,lu~,locessor is enabled to initiate a defrost cycle during the off-peak energy power corlc Ill~lion time of the local utility co~ any. This is advantageous since the off-peak energy power c~ncllmption time typically cQinri~S with the time period collc~l,ùnding to the period of least usage of the refrigePtor (the upening and closing of doors).Further, this time period coincides with a relatively low ambient ~llpcld~ e which the refrigerator will be CA~Os~ to during a 24 hour period. Thus, the 2C initiation of a defrosting cycle during this time period conserves energy while also having the sm~ st impact on food stored within the refrigerator. The miclû~luces~or can ~nncip~te the initiation ûf the next cooling cyciing startin~ a defrost cycle just prior to the preAir~t~d start thus, a cooling cycle will never be 7~ imerrupted. Furthermore. the miclùp~ùcessor constantlv monitors the opeldLing,~.e~uorlc~ of tne de~ os~ hearo- so as to ensuro that a de~ros; cvcie is oni~ .iate~
when i~ is needed and oniy durin~ a time perioci wnicn is most efficien~ for ~herefrigerator and the local utility co-~-pany.
BRIEF DESCRIPI'TON OF THE DRAWINGS
Further features of the present invention will become more readily S apparent from the following det~ d description of the invention taken in conjunction with the acco,l,y~lying drawings, in which:
FIG. 1 is a ~imrlifi~d srh~om~tic circuit illl)str~tin~ a refrige,r~tor circuit ~ltili7in~ a prior art defrost time which is used to defrost the refri~P~tr)r;
FIG. 2 is a graph illustrating the energy co~cumption of a refri~P~tor having a circuit using the prior art defrost timer of FIG. 1;
FIG. 3 is a ,u~ l;ve view of a refri~or~tor in partial cut-away t;~g c~ one,l~ of the refrigerator with which the present invention is used;
FIG. 4 is a Sc`hp I~I;C circuit ~ m ;11115l1~ Cr a defrost control system according to the present invention; and FIGS. 5-12 are flow charts eYpl~inin~ the operation of the micro~l~cessor of FIG. 4.
7 DETAILED DESCRIPrION OF T~; PRE~RRED EMBODIMENT
Referring now to FIG. 3, there is iliustrated a refrigerator 50 within which the present invention is inttonded to be used with. Generally, such a 7~ refrigerator 50 includes a fresn food col",ualL",ent door 52 and a frozen food ccj~llL)dlLI~le.~l. acor 5- whic;~ are Divotabiv connecle~ IO a boav poruoll. 56 whic.-deImes. l~sue,-Liveiy. a fresil fooG co,l, dl-ll,ent 58 anci a f-rozen rood co""pdl"llen 60.
The lc~ue~;Live food co,l,l)dl.",ents 58, 60 are refrigerated by passing refri~erated air therein which is cooled by a cooling dUUdldL~lS which comprises an evdpcjldLur 62, a co"lvressol 6. and a condenser 66. The cooling duU~dtLIS aiso W095/16172 9 21 78~A7 PcTluS94/14154 inrl~ld~P5 a CQn~PncPr fan, an evaporator fan and a heater or arcllmulAtor (not shown), as is conventionAl.
The evd~oldLor 62 is periodically de~losLed by a defrost heater 68 5 which is to be o~ld~cd by the control of the present invention. The defrost heater 68 may be configured as of the or~ hy resL~ive type or may be configured as any other type of heating e1~ .l nt configured to acco~ lish such a task.
A ~ IA~ sensing device generally in the configuration of a 10 defrost t~ h~lol 70 (such as, i.e., a thermostat) is ~icros~l in heat-tlansfer rPlqtinnchir with the e~Al~-..A~or 62. More crerifirAlly, the defrost lclll~rLato- 70 is mountP~ directly on the evd~,d~l 62 as to detect the te~i~ Au~c thereof.
Ad~itionAlly~ at least one te~lllh,lAIll~c control switch (not shown) is utilized in at least one food ~Ill~A~ h~ent 58, 60 so as to detect the ~r-~.l~- A~ e of one or both of the ~ re food COIll~ lc~ 58, 60.
Tun~ing now to FIG. 4, there is illuct~AtP~ a ~hP-..AI;r, circuit tiiAgT7m of the control system 100 according to the present invention, which is con~ clcd to replace the prior art elc. Llo,..~rhAnirAl time (1) as shown in the20 circuit of FIG. 1. The control system 100 is preferably nicpoS~pli within the body portion 56 or outside of the body portion 56 of the refrigestor 50. As describedin more detail below, the control 100 is confivured to ~et~rh~hly engage with the above-mentinnPd co.ll~n~ nts of an existing refrigestor 50 (FIG. 3), such as that 2, shown in FIG. 4 and srhPn-~tir~lly depicted as block 101.
m general. the control 100 comprises a microprocessol 10; to~om.o-with circuitry for conlroiling the Co~ S50~ 6~ and the defrost hea~e- 68 OI the re~igestor 50. The mi~lup~..cessor is provided with a clock input 103 conn_urea 30 to connP~t to a clock source, such as an oscill~tor, as is convçnbnn~k The various co-,.yonent~ of the control 100 illllctrat~d in FIG. 4 receive DC volt-dge from a rectifier 103 which is directly courlçd, via line 104, to an AC voltage source. In particular, the AC voltage source may origin~te from 5 the power circuitry of the refri~e~tor S0 or from any other source, such as a convention~l wall outlet. A filter ayi)d dLus 106 is courl~ to the l~iLc~ 103 soas to reduce the ripple of the terminal voltage from the rectifier 103, and ~ ltlitirn~lly, to smooth out any voltage surges being c~rr~~ ~ from a 1 0 colnplessù~/defrost relay 108 being coupled in parallel rel~tionchir to the filter 106. The c~lllyl~/defrost relay 108 cQmprictos a dry switch 134 and a relay coil 136, the ci~nifir~nre of which will be ~ rihe~d in greater detail below.
A solid state relay control 110 couples to the filter ~ ..c 106 and to the colllyl~sorldefrost relay 108. The solid state relay control 110 is configured to either ene-y.2e or dc e.~ e the cc,lllyle~ ,or/defrost relay 108 upon a CGlll~ signal which is Ejen~ ~t~d from the out~put tennin~l 120 of the mic~u~loce~sor 102 which is coupled, via line 112, to the solid state relay control 110.
The miciu~luccssor 102 is powered by line 114 which is coupled to the so}id state relay control 110. A æner diode DC regulated power supply 116 isprovided in line 114 so as to regulate the voltage between the solid state relaycontrol 110 and the input supply voltage terminal 118 of the micr~r~cessor 102.
An input terrninal 122 of the miclo~lucessol 102 is coupled, via line 126. to a f~ter and peak detector 124. The filter and peak detector 124, via line 128, is coupl~ to a toroid transformer 130. As will be d~srrine~ in grea~er de~ail below, the filter and peak del~lol~ 124 provides the mi- luylùcessor 102 with the 30 infolll,a~ion which in turn is utilized by the miclûplvcessor so as to formulate when a defrosting cycle is to be initi~tPd in the rerrigerator 50.
3~
-WOgS/16172 2 17864 7 PcT~us94/l4l54 The toroid tran~l.ner 130, via line 132, is in el~rtr~
communi~tinn with an AC switched line voltage supply of the refriger~tor 50.
Sperific~lly, the AC switched line voltage supply, via line 132, provides an 5 ene.~iLi-lg current when the ~ .c control switch of the refriger~tor 50 is in a closed poCitinn. Typically, the ~ .pr~ e control switch is in a closed pociti~nn when a ,~h~e food cc,l,.palhllcnt 58, 60 of the refrigprator 50 has a te~ e which is greater than a pre~rihed value (such as, e.g., 30F).
10 Conversely, when a ,~ /e food c~lllydlhllent 58, 60 of the refri~Pra~or 50 has a ~ c which is less than the above ,..~ ;nnf~i y~c~, ;he~d value, the lC...~,atu.e control switch moves to an open ~5;l;on SO as to prevent an ene.~ iLillg current to flow from the AC switched line voltage supply to the line 132 of the control system 100.
As rnPnti~n~P~ above, the colllp,~ssor/defrost relay 108 compriCPs a dry switch 134 and a relay coil 136. The line 133-is coupled to the dry switch 134. The drv switch 134 is configl-red to be ~ctu~hle by a co.,l",and signal from the miclul"~r 102, via the relay coil 136. The dry switch 134 is ~ hl~
20 between an activated position and a de-activated position. When the dry switch 134 is de-activated, it effectively couples the AC switched line voltage supply by line 135 to the col~ly~essor 64 of the refrigerator 50. Conversely, when the dryswitch 134 is activated, it effectively couples the AC switched line voltage supply 2~ by line 137 to the defrost heater 68 of the refrigerator 50. It is particularly noted that the dry switch 134 mav onlv be switched from the de-activated position tO the activated position when the colllylesior 64 is not energized (generally when a ~--~y~;-dlu'e controi switch is riicposed in an open position, as mentioned above).
The toroid transforrner 130 is configured to sense the flow of ~ne,~ g current, via lines 132 and 133, from the AC switched line voltage supply of the refrigerator 50 to the dry switch 134 of the CO"Iy.~ ~sol/defrost relay 2i 78~47 108. Thus, when the tc,l,~,dture control switch of the refrigerator 50 is disposed in a closed pOcitiO~l~ the toroid transformer 130 effectively detects the flow of energizing current from the AC switched line voltage supply, via line 132, to 5 either the COIllpl'~,SSOr 64 or the defrost heater 68, ~nr~ing upon the position of the dry switch 134. The toroid transformer 130 couples this sensed crle~ ng current flow, via line 128, to the filter and peak dc~;lor 124.
The filter and peak det~tor 124, via line 126, is coupled to an input 1 0 terminal of the mi~;luplvcessol 102. As will be lic~ ccpd in much greater detail below, the micluplocessor ~,vcesses this received infol",~Lion from the filter and peak ~et~t~r 124, and subsequently formulates when it is most effi~ nt to initiate a def~ g cycle in the rPfri~P~tor 50.
When the micl~lvcessor 102 de~,lllines that a defrost cycle should be initi~t~ an "ON" signal is sent from the output terminal 120 of the miclol,lucessor 102 to the solid state relay control 110. The solid state relay control 110 relays the "ON" signal to the relay coil 136 of the cc ",~ ssor/defrost relay 108 which erl~l"~- s the dry switch 134 to be "activated"; thereby en~hting 20 the AC switched line voltage supply to be coupied to the defrost heater 68 of the refrigerator 50.
In contrast when the mic,op,ucessor 102 determines that the defrost cycle is to be terrnin~ted, an "OFF" signal is sent from the output terminal 120 of 2~ the mic~up,uc~ssor 102 to the solid state relay control 110. The solid state relay control 110 relavs the "OFr" signal to the relav coil 136 of the co,l~p,cssoridefros;
reiay 108 which efIecn~t~s the dry switch to be "de-activated", thereby enabiin~the AC switched line voltage supply to be coupled to the co,llp,L~sor 64 OI the 30 refrigerator 50.
Referring now to FIGS. 5-12, there is illlctr~tPd a flow chart of the proglA~ ufilized the ~lu~lA~..ming of the micloyrocessor for implçmPnting the control of the instant invention.
The microprocessor program starts immPI1iAtPly after the comrlP*r~n of power on reset timing circuit (not shown~
The ~AI Alll. ~ . ~ of APC (Actual Recorded Hourly Power Concump*on), TTDC (Time to Defrost Control), defrost mode, various recorded 10 times, Tdefrost-A~tll-Al, defrost *ime and others not d~Psrrihed, are ini*-Ali7PA (1).
During the first days (e.g. five days) of operation while the yluyOSc~ device isde~- -...;n;nE~ ope~ti~n-Al time of day for the refri~--rAtor, it will operate as a conven*rn~l defrost timer. The defrost period will be fL~ced at an 8 hour co~ly~Dr run time or, if an AltPrn-ASP configuration is j",~ "I .trd, ju",p~
po~i*~nP~ within the micropç~cessor circuity will be read by the micluy~cessor for various common time periods such as 6, 8, 12, and 16 hours. Referring to FIG. 5, a clock in the ~ luylucessol is initially set for zero (step 500) and will start collntinC when a tick occurs after every 5 sP~Qn~l~ of the system clock event.
20 If a tic~ is detectPd, the control system 100 will measure the toroid current sensor 130 and determine if the current in the defroster or co",ylessor has ch-An,,eA state (steps 512 and 514). If no chan .e in the measured current is de2~oc2t-d, the svstem repeats steps 512 and 514 until a current change is deterted. Once a current ~, change is detect~d, the frost mode fla, is read to determine if the change detected occurred in the defros; heate- or the co~Julcssor (ste?s 516 anc 51~). If tr.~
defrost mode fla~ was set the defrost process of FIG. 6 is yc~ful~l~e~ (sle? 5~0).
The defrost process, illustrated in FIG. 6, is imple~ented such that 30 the control system records the defrost time, as referenced to the clock ticks (step 610) and re~ds the toroid current sensor 130 to de~l",il e if current is sensed (step 620). If current is sensed, the time recorded was a defrost start and the defros;
WO 95/16172 ~i 1 7 8 6 4 7 PCT/US94/14154 process returns to the main loop (step 620 of FIG. 6 and step 520 of FIG. 5). Ifno current is sensed by the toroid current sensor 130, the time recorded was a defrost ~c~ ;nsl;on requiring the defrost mode flag to be cleared (step 630) and the 5 dry switch 134 of the common relay contact 108 is s~viLche~ to activate the eu~ lessol (step 640) so that the next time ~he refrigerator t~ G control supplies power to the Commorl relay contact 108 the u~ ,l~r will actuate.
Once the relay 108 is switched, the defrost process returns to the main loop at step 1 0 520 of FIG. 5.
Rf turnin~ to step 518 of FIG. 5, if the defrost mode flag is not set (step 518), the cc~ pl~sOr process is pe.rorll-cd (steps 518 and 522). The COlllpl~SSOr process is ill~ .4tf~ in FIG. 7 and compricf s the steps of lecor-ling the time, (step 710) as being lefel..nced to the clock ticks. The current sensor, (step 720) is read to de~....inc if current is sensed. If current is sensed, time is ,ecol~cd as a colllpl~sor start (step 720) and the co-,-p~:,or process returns to the eommc-n loop of FIG. 5 (steps 518 and 522). If no current is sensed, the time recorded is of comp.~s:,or power cons~lmption being termin~tf~d ~step 730). The 20 APC memory array cont~inC a 24 hour record oî averaged power concumrtion.
The APC is updated with smoothing (step 740) by adding a perccr ~ge of the latest co~ lc~aor power concumption to the comple~nf~nt~rv pe,.;cn~ge K1 of the averaged power conc~mrtion for the r~s~Li-/e time period. The TTDC counter is 25 declc,nf.-ted (740) by an amount equal to the stop time minus the start time (colllplcs~or on duration!. The TrDC counter is se~ to 8 hours. as wouid be _ convention~l time.. during the convenrion~l derrost program operation. O~ner times may be sPlf rted if the alternate jumper configuration (not shown) is used. If 30 the TTDC has expired, (step 750) the relay is switched to the defrosl position (step 760) and a defrost will be initi~tf~d the next time the ~e",pcldLu-e control supplies power to the relay common terminal. If the TTDC has nol expired~ the pro~r~n wo 95/16172 ~ ~ 78 6 ~q 7 Pcr/Uss4ll4l54 will not allow initiAtion of defrost at this time and ~ rogram returns to the common loop (steps 518 and 522).
Retllrnin, to FIG. 5, if the clock has not ticked (step 512), the 5 I)luglA~l, deLe.,~ es if a Continuous Next Step Time of Day (524) is required.Turning to FIG. 8, the Present Hour ComrlPt~ Flag is tested to 5~ ,....n~ if allrAlr~ tinnC for the present hour are comrl~ (step 810). If not, another single el~ment of the 24 el~ t typical hourly power concumption is :~ubh~c~ed from an 1 0 rl~ ....~n~ of the 24 c~ actual Pl' -"'P~ power concumrti~n array (step 820), the result squared and added to a running sum for the ~ e time ~k ,.. nt This function (step 820) is the c~lrul~tion of at least mean squares fit, also l~f~lcd to as a correlation, of a mAth~m~tirAl ~ 5~..tAtion of the typical hourly power S conC--mrtion eYp~c~ of a typical refrigerator in a typical family rec~ nce to that of the refri~tor cor lA;nin~ the device lO0 of the present invention.
As there are 24 by 24, or 576 c-Alrul-A*onc~ only one c~lr~ tion is ~iull~lecl per pass through the loop. If all 576 cAlculAtinnc are not complete (step 830) the ~lu~ l retums. If all are complete the l)logl~ll oAlr--~At~s the time of 20 day by adding the hme offset determined (step 820) to the cloclc (step 840). The present hour complete flag is set (step 850) and the plu~ ll retums (step 526).
Referring to FIG. 8, if the Present Hour Complete Fiav is set. there will be no more cAlcu1Ations until a new hour occurs (step 860). At the start of a ~5 new hour the indexes for the 576 c~lCUlAtionS are initiAli7tod (step 870). the Presen~
Hour Compieto Fiac is cie~red (sl? 880~ and tho prov;am returns to tne common loop (step 526).
R~ rninv to FIG. 5, as the amount of C0111~1~5501 power 30 concumption data increases, the e~l;r..AIrs of time of day will become closer to actual. When the error corrections to time of day become small (step 526), and the refrigerator is not in defrost mode (step 528) and there is sufficient time (ste~
WO 9S/16172 ~ 1 7 8 6 4 7 PCT/US94/14154 530) until the middle of the off peak period, about 3 AM, the prograrn is allowed to calibrate the defrost operation to determine the therrnal overhead, as illustrated in FIG. 9.
Referring to FIG. 9, the calibration process r~u~ s two defrosts closely spaced. The process is ~ ;~d by a CALLOOP count (step 902). The first defrost is set to occur at 1 AM (step 906). While waiting for the defrost to occur, the clock ticks (step 910), sensor change (step 912) time of day calc~ ~in 1 0 (step 914), defrost (steps 916 and 920), cGI~pl~ ssor (step 918) are uti~ized similarly to those in conventio~l opPr~tion mode (steps 512, 514, 518, 520 and 522). However, when the 1 AM defrost has comrletçd (steps 922 and 924), CALI OOP is dccl~ -..r n~ to allow setup of the 5 AM defrost (step 908). Since only 4 hours of ul~u---ably little refrigeration activity exist between 1 and 5 AM, little frost should occur on the ev~roT~tin~ coils and the ev~r7~tinn tf ~
should be predictable. thus, the --lsuled defrost time at 5 AM will be almost co...~letely the thermal overhead of the defrost process (step 926) without ice. The ideal defrost time for the particular refrigerator is e,l;.~ ed to be the thermal ~ overhead times a factor (step 928) ~reater than 1. The next defrost is sched~led to occur at 2 AM (step 930) and the ~lu~r~,l enters the process of FIG. 11.
Referring to FIG. 10, an alternate impiemrnt~tinn is implemrntrd DV
reading jumpers (step 1002) which directs the ~rog~dlJ- to read predetermined 25 values of ideal defrost time (step 1004). The l-lL)C is set to 2 AM (1006) the two caiibralion derros~s are no~ re~uired and the provrarn enlers the process of FIC-.
li.
Ref~rinv to FIG. 11, the clock tick (step 1102) sensor chanve (slep 30 1104), defrost mode (step 1106), process defrost (step 1110) and process co,l.ul~:ssor (step 1116) are all similar to those previously described. The TIDC is r~lrul~trd (step 1114) at the end of eacn defrost (step 1112). Referrinv to FIG.
wo gS/16172 Zl 7~6 4 7 PCT/US94114154 12, the different of the actual defrost time and ideal is an error value (step 1202).
If the error value ED is very large (step 1204), then p,e~l.llably a lot of ice was on the evdpold~ol coils and three defrosts (step 1212) are lc~luh~d per day.
Simil~rly, if the error is large (step 1206), two defrosts (step 1214) are required;
the error is small (step 1208) one defrost is lequired (step 1216); the error is less - than small (step 1210), defrost is every other day.
While the inven*on has been particularly shown and dpcrrihe~d with 10 lt;f~,e,lce to the ~er~ d embo~ nlc~ it will be understood by those sl~lled in the art that various m~lifir~*rnc in form and detail may be made therein withoutdeparting from the scope and spirit of the invention. Ac~or~ingly, mo~ifir~tionssuch as those s~-~gectP~ above, but not limited thereto, are to be comil1P~ed within the scope of the invention.
Claims (61)
1. A refrigerator, comprising:
(a) at least one enclosed compartment for storing items to be cooled;
(b) means for cooling said at least one enclosed compartment positioned exterior to said compartment;
(c) means for heating said cooling means; and (d) control means for determining a rate of power consumption of said refrigerator within a predetermined period of time, said control means being configured to energize said heating means upon determination of said rate of power consumption by said control means.
(a) at least one enclosed compartment for storing items to be cooled;
(b) means for cooling said at least one enclosed compartment positioned exterior to said compartment;
(c) means for heating said cooling means; and (d) control means for determining a rate of power consumption of said refrigerator within a predetermined period of time, said control means being configured to energize said heating means upon determination of said rate of power consumption by said control means.
2. A refrigerator as recited in claim 1, wherein said control means comprises a microprocessor, said microprocessor being programmed so as to determine said rate of power consumption of said refrigerator within a 24 hour period of time.
3. A refrigerator as recited in claim 2, wherein said microprocessor is programmed to determine the frequency of defrost cycles with respect to the duration of energization of said heating means during preceding defrosting cycles.
4. A refrigerator as recited in claim 1, wherein said cooling means comprises at least an evaporator having a refrigerant flowing therethrough for dissipating heat from said at least one enclosed compartment.
5. A refrigerator as recited in claim 4, wherein said heating means is positioned adjacent said evaporator to melt frost accumulating upon said evaporator during cooling.
6. A refrigerator as recited in claim 5, wherein said heating means includes a sensor for detecting the temperature of said evaporator.
7. A control for a refrigerator having cooling means including an evaporator for cooling said refrigerator and a heating means for removing frost accumulating upon said evaporator after a cooling cycle, comprising:
(a) determining means for determining at least one optimum defrost time during an interval of lowest power consumption of said refrigerator in a 24 hour period;
(b) detecting means for detecting a period of time required to remove accumulated frost from said evaporator when said heating apparatus is energized;
and (c) means for energizing said heating apparatus during said at least one optimum defrost time in accordance with said detected period of time established by said detecting means.
(a) determining means for determining at least one optimum defrost time during an interval of lowest power consumption of said refrigerator in a 24 hour period;
(b) detecting means for detecting a period of time required to remove accumulated frost from said evaporator when said heating apparatus is energized;
and (c) means for energizing said heating apparatus during said at least one optimum defrost time in accordance with said detected period of time established by said detecting means.
8. A control for a refrigerator as recited in claim 7, further comprising a microprocessor.
9. A control for a refrigerator as recited in Claim 7, further comprising a housing including electrical contacts for enclosing said determining means, said detecting means and said energizing means, said control being configured to detachably engage with said refrigerator.
10. A control for a refrigerator as recited in claim 8, wherein said determining means includes comparison means and measures the power consumption of a refrigerator during a 24 hour period and compares said 24 hour measurement with a pre-programmed power distribution curve in said microprocessor so as to determine said period of lowest power consumption of said refrigerator.
11. A control for a refrigerator as recited in claim 8, wherein said means for energizing includes a solid state relay control coupled to a compressor/defrost relay, said solid state relay control being coupled to said microprocessor.
12. A control for a refrigerator as recited in claim 11, wherein said compressor/defrost relay includes a dry switch coupled to said cooling means and said heating means of said refrigerator, said dry switch being actuable between said cooling means and said heating means.
13. A control for a refrigerator as recited in claim 12, wherein said dry switch is activated between said cooling means and said heating means in response to an output signal from said microprocessor.
14. A control for a refrigerator as recited in claim 8, further including means for sensing when said accumulated frost is removed from said evaporator and being responsive so as to de-energize said heating apparatus when said accumulated frost is removed from said evaporator.
15. A control for a refrigerator as recited in claim 14, wherein said sensing means is coupled to said detecting means whereby said microprocessor is programmed to determine the frequency of defrost cycles in accordance with the duration of energization said heating apparatus during preceding defrosting cycles.
16. A method for controlling the defrosting of an evaporator coil of a refrigerator by initiating a defrost operation during a lowest power consumption interval of the refrigerator within a 24 hour period, said method comprising the steps of:
(a) measuring power consumption of said refrigerator within a first 24 hour period;
(b) storing measured power consumption of said refrigerator during said first 24 hour period;
(c) determining a period of lowest power consumption of said refrigerator within said first 24 hour period; and (d) initiating at least one defrost operation during said period of lowest power consumption within a subsequent 24 hour period.
(a) measuring power consumption of said refrigerator within a first 24 hour period;
(b) storing measured power consumption of said refrigerator during said first 24 hour period;
(c) determining a period of lowest power consumption of said refrigerator within said first 24 hour period; and (d) initiating at least one defrost operation during said period of lowest power consumption within a subsequent 24 hour period.
17. A method for controlling the defrosting of an evaporator coil of a refrigerator as recited in claim 16, further including the steps of:
(e) determining a desired time period required to raise said evaporator coil to a predetermined temperature without the presence of ice on said evaporator coil;
and (f) determining the time required to complete a defrost cycle of said evaporator coil.
(e) determining a desired time period required to raise said evaporator coil to a predetermined temperature without the presence of ice on said evaporator coil;
and (f) determining the time required to complete a defrost cycle of said evaporator coil.
18. A method for controlling the defrosting of an evaporator coil of a refrigerator as recited in claim 17, further including the steps of:
(g) determining the number of defrost operations required during said period of lowest power consumption; and (h) establishing an interval before a next defrost operation based at least in part on the time needed to complete the previous defrost operation.
(g) determining the number of defrost operations required during said period of lowest power consumption; and (h) establishing an interval before a next defrost operation based at least in part on the time needed to complete the previous defrost operation.
19. A method for controlling the defrosting of an evaporator coil of a refrigerator as recited in claim 18, wherein the step (h) of establishing an interval before a next defrost operation comprises the steps of:
(i) increasing an interval of time between defrost operations if the time required to complete a preceeding defrost operation is within a predetermined time from said desired time period; and (j) decreasing the interval of time between defrost operations if the time required to complete the preceeding defrost operation is greater than a second predetermined time from said desired time period.
(i) increasing an interval of time between defrost operations if the time required to complete a preceeding defrost operation is within a predetermined time from said desired time period; and (j) decreasing the interval of time between defrost operations if the time required to complete the preceeding defrost operation is greater than a second predetermined time from said desired time period.
20. A method for controlling the defrosting of an evaporator coil of a refrigerator as recited in claim 19, further comprising the step of:
(k) averaging a plurality of said stored measured power consumptions of said refrigerator during said first 24 hour period.
(k) averaging a plurality of said stored measured power consumptions of said refrigerator during said first 24 hour period.
21. A circuit for determining periodic power consumption of an electrically operated device, which comprises:
a) measuring means for measuring actual power consumption of said electrically operated device;
b) control means coupled to said measuring means and operative to enable said measuring means in predetermined first intervals of time;
c) storage means coupled to said measuring means and operative to store said measured power consumption in at least one second predetermined interval of time;
and d) calculating means for calculating periodic power consumption through an averaging calculation of said measured power consumption stored in said at least one second predetermined interval of time, wherein said calculating means is coupled to said control means for activating and deactivating an electrical component of said electrically operated device.
a) measuring means for measuring actual power consumption of said electrically operated device;
b) control means coupled to said measuring means and operative to enable said measuring means in predetermined first intervals of time;
c) storage means coupled to said measuring means and operative to store said measured power consumption in at least one second predetermined interval of time;
and d) calculating means for calculating periodic power consumption through an averaging calculation of said measured power consumption stored in said at least one second predetermined interval of time, wherein said calculating means is coupled to said control means for activating and deactivating an electrical component of said electrically operated device.
22. A circuit for determining periodic power consumption as recited in claim 21, wherein said first predetermined interval of time is approximately five seconds and said second predetermined interval of time is approximately twenty-four hours.
23. A circuit for determining periodic power consumption as recited in claim 22, wherein said measuring means includes a toroid transformer associated with an AC switched line voltage supply of said electrically operated device.
24. A circuit for determining periodic power consumption as recited in claim 23, wherein said measuring means further includes a filter and peak detector coupled to said torid transformer.
25. A circuit for determining periodic power consumption as recited in claim 22, further including a microprocessor wherein said microprocessor includes said control means, storage means and determining means.
26. A circuit for determining periodic power consumption as recited in claim 22, further including switching means operative to activate and deactivate an electrically driven component of said electrically operated device upon determination of said periodic power consumption.
27. A circuit for determining periodic power consumption as recited in Claim 21, wherein said control means is configured to generate a clock signal with said calculated periodic power consumption through at least means square fit between said clock signal and said calculated power consumption, said clock signal being derived in part by said calculated periodic power consumption.
28. A switching circuit for an electrically operated appliance, wherein said switching circuit is responsive to periodic power consumption of said electrically operated appliance, said switching circuit comprises:
a) measuring means for measuring power consumption of said electrically operated appliance in predetermined first intervals of time;
b) storage means coupled to said measuring means and operative to store said measured actual power consumption in a plurality of second predetermined intervals of time;
c) calculating means for calculating said periodic power consumption by an averaging calculation of said measured power consumption stored in said plurality of second predetermined intervals of time; and d) control means coupled to said calculating means and to an electrically driven component of said electrically operated appliance, said control means being adapted to activate and deactivate said electrically driven component upon determination of said periodic power consumption of said electrically operated appliance.
a) measuring means for measuring power consumption of said electrically operated appliance in predetermined first intervals of time;
b) storage means coupled to said measuring means and operative to store said measured actual power consumption in a plurality of second predetermined intervals of time;
c) calculating means for calculating said periodic power consumption by an averaging calculation of said measured power consumption stored in said plurality of second predetermined intervals of time; and d) control means coupled to said calculating means and to an electrically driven component of said electrically operated appliance, said control means being adapted to activate and deactivate said electrically driven component upon determination of said periodic power consumption of said electrically operated appliance.
29. A switching circuit as recited in claim 28, wherein said control means is configured to generate a clock signal, said clock signal being derived in part by said calculated periodic power consumption.
30. A switching circuit as recited in claim 29, wherein said control means is further configured to generate said clock signal with said calculated periodic power consumption through at least means square fit between said clock signal and said calculated power consumption.
31. A switching circuit as recited in claim 29, wherein said control means is operative to activate and deactivate said electrically driven component in a prescribed time period defined by said clock signal.
32. A switching circuit as recited in claim 31, wherein said control means includes:
i) a microprocessor;
ii) a solid state relay control circuit coupled to and actuated by said microprocessor; and iii) a relay switching circuit coupled to said solid state relay control circuit, said relay switching circuit further being coupled to said electrically driven component and a power supply, wherein said relay switching circuit is operative to couple said electrically driven component to said power supply upon actuation of said solid state relay control circuit.
i) a microprocessor;
ii) a solid state relay control circuit coupled to and actuated by said microprocessor; and iii) a relay switching circuit coupled to said solid state relay control circuit, said relay switching circuit further being coupled to said electrically driven component and a power supply, wherein said relay switching circuit is operative to couple said electrically driven component to said power supply upon actuation of said solid state relay control circuit.
33. A switching circuit as recited in claim 32, wherein said measuring means includes a toroid transformer associated with an AC switched line voltage supply of said electrically operated appliance.
34. A switching circuit as recited in claim 33, wherein said measuring means further includes a filter and peak detector coupled to said torid transformer.
35. A switching circuit as recited in claim 34, wherein said storage means and said calculating means are provided in said microprocessor.
36. A switching circuit as recited in claim 35, wherein said first predetermined interval of time is approximately one second and said second predetermined interval of time is approximately twenty-four hours.
37. A method of activating an electrically driven component of an electric appliance in response to measured periodic power consumption of said appliance, which comprises the steps of:
a) measuring power consumption of said appliance in predetermined first intervals of time;
b) storing said measured power consumption in a plurality of second predetermined intervals of time;
c) calculating said periodic power consumption by averaging said measured power consumption stored in said plurality of second predetermined intervals of time;
d) activating said electrically driven component upon determination of said periodic power consumption of said appliance.
a) measuring power consumption of said appliance in predetermined first intervals of time;
b) storing said measured power consumption in a plurality of second predetermined intervals of time;
c) calculating said periodic power consumption by averaging said measured power consumption stored in said plurality of second predetermined intervals of time;
d) activating said electrically driven component upon determination of said periodic power consumption of said appliance.
38. A method of activating an electrically driven component of an electric appliance as recited in claim 37, further including the step of:
e) generating a clock signal being derived in part by said calculated periodic power consumption.
e) generating a clock signal being derived in part by said calculated periodic power consumption.
39. A method of activating an electrically driven component of an electric appliance as recited in claim 38, wherein the activating step (d) activates said electrically driven component in a prescribed time period defined by said clock signal.
40. A method of activating an electrically driven component of an electric appliance as recited in Claim 38, wherein activating step (d) generates said clock signal with said calculated periodic power consumption through at least mean square fit between said clock signals and said calculated power consumption.
41. A circuit for determining periodic power consumption of an electrically operated device, which comprises:
a) measuring means for measuring actual power consumption of said electrically operated device;
b) control means coupled to said measuring means and operative to enable said measuring means in predetermined first intervals of time;
c) storage means coupled to said measuring means and operative to store said measured power consumption in at least one second predetermined interval of time; and d) calculating means for calculating periodic power consumption through an averaging calculation of said measured power consumption stored in said at least one second predetermined interval of time.
a) measuring means for measuring actual power consumption of said electrically operated device;
b) control means coupled to said measuring means and operative to enable said measuring means in predetermined first intervals of time;
c) storage means coupled to said measuring means and operative to store said measured power consumption in at least one second predetermined interval of time; and d) calculating means for calculating periodic power consumption through an averaging calculation of said measured power consumption stored in said at least one second predetermined interval of time.
42. A circuit for determining periodic power consumption as recited in claim 41, wherein said first predetermined interval of time is approximately five seconds and said second predetermined interval of time is approximately twenty-four hours.
43. A circuit for determining periodic power consumption as recited in claim 42, wherein said measuring means includes a toroid transformer associated with an AC switched line voltage supply of said electrically operated device.
44. A circuit for determining periodic power consumption as recited in claim 43, wherein said measuring means further includes a filter and peak detector coupled to said toroid transformer.
45. A circuit for determining periodic power consumption as recited in claim 42, further including a microprocessor wherein said microprocessor includes said control means, storage means and determining means.
46. A circuit for determining periodic power consumption as recited in claim 42, further including switching means operative to activate and deactivate an electrically driven component of said electrically operated device upon determination of said periodic power consumption.
47. A refrigerator, comprising:
(a) at least one enclosed compartment for storing items to be cooled (b) means for cooling said at least one enclosed compartment positioned exterior to said compartment (c) means for heating said cooling means; and (d) control means for determining a rate of power consumption of said refrigerator, said control means including means for automatically energizing said heating means upon determination of said rate of power consumption by said control means.
(a) at least one enclosed compartment for storing items to be cooled (b) means for cooling said at least one enclosed compartment positioned exterior to said compartment (c) means for heating said cooling means; and (d) control means for determining a rate of power consumption of said refrigerator, said control means including means for automatically energizing said heating means upon determination of said rate of power consumption by said control means.
48. A refrigerator as recited in claim 47, wherein said control means comprises a microprocessor, said microprocessor being programmed so as to formulate a 24 hour model of an estimated rate of power consumption of said refrigerator.
49. A refrigerator as recited in claim 48, wherein said microprocessor is programmed to determine the frequency of defrost cycles with respect to the duration of energization of said heating means during preceding defrosting cycles.
50. A refrigerator as recited in claim 47, wherein said cooling means comprises at least an evaporator having a refrigerant flowing therethrough for dissipating heat from said at least one enclosed compartment.
51. A refrigerator as recited in claim 50, wherein said heating means is positioned adjacent said evaporator to melt frost accumulating upon said evaporator during cooling.
52. A refrigerator as recited in claim 51, wherein said heating means includes a sensor for detecting the accumulation of frost upon said evaporator.
53. A control for a refrigerator having cooling means including an evaporator for cooling said refrigerator and a heating means for removing frost accumulating upon said evaporator after a cooling cycle, comprising:
(a) determining means for determining an optimum defrost time of said refrigerator in a 24 hour period;
(b) detecting means for detecting a period of time required to remove accumulated frost from said evaporator when said heating apparatus is energized;
and (c) means for energizing said heating apparatus during said interval of lowest power consumption in accordance with said detected period of time established by said detecting means.
(a) determining means for determining an optimum defrost time of said refrigerator in a 24 hour period;
(b) detecting means for detecting a period of time required to remove accumulated frost from said evaporator when said heating apparatus is energized;
and (c) means for energizing said heating apparatus during said interval of lowest power consumption in accordance with said detected period of time established by said detecting means.
54. A control for a refrigerator as recited in claim 53, further comprising a microprocessor.
55. A control for a refrigerator as recited in claim 53, further comprising a housing including electrical contacts for enclosing said determining means, said detecting means and said energizing means, said control being configured to detachably engage with said refrigerator.
56. A control for a refrigerator as recited in claim 54, wherein said determining means includes comparison means and measures the power consumption of a refrigerator during a 24 hour period and compares said 24 hour measurement with pre-programmed power distribution curve in said microprocessor so as to determine said period of lowest power consumption of said refrigerator.
57. A control for a refrigerator as recited in claim 54, wherein said means for engaging includes a solid state relay control coupled to a compressor/defrost relay, said solid state relay control being coupled to said microprocessor.
58. A control for a refrigerator as recited in claim 57, wherein said compressor/defrost relay includes a dry switch coupled to said cooling means and said heating means of said refrigerator, said dry switch being actuable between said cooling means and said heating means.
59. A control for a refrigerator as recited in claim 58, wherein said dry switch is activated between said cooling means and said heating means in response to an output signal from said microprocessor.
60. A control for a refrigerator as recited in claim 54, further including means for sensing when said accumulated frost is removed from said evaporator and being responsive so as to de-energize said heating apparatus when said accumulated frost is removed from said evaporator.
61. A control for a refrigerator as recited in claim 60, wherein said sensing means is coupled to said detecting means whereby said microprocessor is programmed to determine the frequency of defrost cycles in accordance with the duration of energization said heating apparatus during preceding defrosting cycles.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/164,333 | 1993-12-09 | ||
| US08/164,333 US5415005A (en) | 1993-12-09 | 1993-12-09 | Defrost control device and method |
| PCT/US1994/014154 WO1995016172A1 (en) | 1993-12-09 | 1994-12-08 | Defrost control device and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2178647A1 CA2178647A1 (en) | 1995-06-15 |
| CA2178647C true CA2178647C (en) | 2000-02-22 |
Family
ID=22594015
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2178647 Expired - Fee Related CA2178647C (en) | 1993-12-09 | 1994-12-08 | Defrost control device and method |
Country Status (4)
| Country | Link |
|---|---|
| US (2) | US5415005A (en) |
| AU (1) | AU1337795A (en) |
| CA (1) | CA2178647C (en) |
| WO (1) | WO1995016172A1 (en) |
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1993
- 1993-12-09 US US08/164,333 patent/US5415005A/en not_active Expired - Lifetime
-
1994
- 1994-12-08 CA CA 2178647 patent/CA2178647C/en not_active Expired - Fee Related
- 1994-12-08 WO PCT/US1994/014154 patent/WO1995016172A1/en active Application Filing
- 1994-12-08 AU AU13377/95A patent/AU1337795A/en not_active Abandoned
-
1995
- 1995-04-03 US US08/415,256 patent/US5515692A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995016172A1 (en) | 1995-06-15 |
| US5515692A (en) | 1996-05-14 |
| CA2178647A1 (en) | 1995-06-15 |
| US5415005A (en) | 1995-05-16 |
| AU1337795A (en) | 1995-06-27 |
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| EEER | Examination request | ||
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