US 2095834 A
Description (OCR text may contain errors)
C. A. RODMAN REFRIGERATING APPARATUS Oct. 1'2, 1937.
Filed May 51, 1935 INVENTOR' WMM M,
ATTORNEY .Patented ocr. 12, 1'937 PATENT OFFICE REFRIGERATING APPARATUs Clarence-A. Rodman, Detroit, Mich., assignor to John B. Tanner Claims.
This invention relates to improvements in refrigerating and air conditioning apparatus and employing expansion or element coils in combination with controlled valve mechanism or novel construction and operation. In my Patent No.. 2,047,799, issued July 14, 1936, I have shown and described means for controlling the flow of refrig'erant to the evaporator, causing it to take place intermittently or in impulses and for controlling the volume passing from the condenser sideto the expansion side by means responsive to the requirements of conditions, that is, the load imposed upon the apparatus. y
In the present application as in the former, the general object isto provide a simple, effective mechanism for so controlling the ilow of the refrigerant to the evaporator Aor expansion coil inl such manner as to cause the latter to operate at or near the dew point Without causing precipitation 'of moisture on the surface of. said evapo rator or expansion coil.
In accomplishing this object I provided in the application referred to a valve for causing the flow of refrigerant at timed intervals, and by means ofanother valve or passage for liquid refrigerant provided a thermo-responsive means governing the opening and thus the amount of 'liquid refrigerant allowed'to pass at each interval.- p
More specific therefore is an object of the present invention to interconnect lthe thermo and timing controlled valve operating mechanism so that the former may govern the opening or extent of opening of a valve and the timing device may govern intervals and length of time during which this same valve shall be opened and closed.
In the operation of my system the valve is effective to release the refrigerant to the cooling or expansion coils inimpulses. 'Ihese impulses 40 .create cool sections or zones along the path of the refrigerant in expanding through the evapoy rator, and a Warm zone or section intervenes between the successive impulses due to the absence of expanding refrigerant present at these points within the. evaporator, resulting 'in alternate warm and cool sections moving along the trans? verse reaches of the evaporator, 4"lihe releasing of a limited amount of refrigerant in impulses at the expansion valve causes the refrigerant to be of a relatively high density to effectively expand and travel in the form of relatively isolated v .charges through the entire lengthof the evapo` rator creating a moving cool section or zone as it goes and the succession of impulses or charges Thy thislow pressure condition within Application May 31, 1935, Serial No. 24,381v
evaporator, it immediately begins to expand,
causing heat to be abstracted from the air passing through the evaporator unit. This reduction in temperature of the air causes a condensation of moisture on the ns and tubes of the evaporator but of a decreased amount because of our moderated tube surface temperature as caused byaour intermittent iiow of refrigerant (this amount of moisture deposit-depending on the humidity and temperature of the airrentering the evaporator and the amount or density of refrigerant included in the charge, this latter being controlled by the condition of the refrigerant as it leaves the evaporator, which condition governs the amount of openingof lour valve .element in the expansion valve, as Will presently appear).
As the charge of. refrigerant passes on, this same evaporator section will undergo a warming period caused by the flow of unrefrigerated air and the absence of refrigerant within the evaporator tubes at that instant, this duration of the period being controlled by our timing device, as will presently appear.
Thiswarming period may cause vaporization By the low pressure condition existing withinvthe evaporator unit as caused by the suction pump or fan on the outlet side of the evaporator, the moisture may travel along the fins towards the suction source. The air leaving the evaporator will contain moisture picked up'by evaporation, and that entrained in the air as caused the 'evaporator chamber. i In controlling temperature and humidity of refrigerated air, we have these two governors in theexpansion valve, one controlling the number of charges per unit interval of time and the `other the amount or density of lrefrigerant in each charge, For controlling solely the temperature of the air passing through the evaporator the intermittentiiow ol.' the refrigerant is of no superior value. But in controlling humidity, the pulsations or charge of refrigerant per unit interval of time necessary will vary in a proportion with the difference in percent of the relative humidity differential desired, as between the inlet and outlet conditions of the air passing through the evaporator. In other words, assuming no change in temperature desired in the air to be'refrigerated but a desired humidity increase, or decrease, the pulsations per unit interval of time are increased or decreased in a proportion in conjunction with a` variance in unrefrigerated air velocity through the evaporator, the amount or density of refrigerant for each charge or impulse being controlled by the thermal condition of the refrigerant at the outlet of the evaporator as reflected through the thermal bulb and thermal sylphon bellows, the action of the thermal bellows governing the opening of the valve element CII .within the expansion valve.
In employing a suction pump or fan at the outlet of the evaporator in place of a discharge pump at the inlet, the effect of centrifugal force and impacton the dis-entrainment of the moisture in the air as it passes through the-evaporator is considerably decreased, allowing greater humidity control. Also the fins used in the evaporator are preferably of a thinness` not to exceed .007" in order to prevents. thermal equilibrium to occur as between the transverse reaches of the evaporator, and because of this very small cross sectional area they will not act as heat or cold conductors, they will be exceptionally sensitive to a change in temperature occurring in the evaporator tubes to which they are attached. Therefore by the use of such fins, ring like temperature zones are projected out from and to the evaporator tubes respectively, thus making possible this increased control over the humidity of the air to be refrigerated.
By insulating the end zones of the evaporator, an increased efficiency is acquired because of the condensation or cooling of the refrigerant as it passes through these zones,giving an increased expansionability to the refrigerant as it passes into the transverse reaches of the evaporator.
Using this system in conjunction with food preservation, such as in a machine for dispensing comestibles, a low temperature condition must be maintained with, the humidity controlled so that for example, a chocolate ice cream may be preserved for days, in fact indefinitely without any deposits of moisture or absorption of moisture from these comestibles as in any way interferes with their appearance, edibility or saleand such results have been accomplished by my refrigerating and dispensing apparatus as described in my Patent No.'2,009,817, issued July 30, 1935. v
Other objects include so constructing the valve that it may be cheaply manufactured, may be effective in operation vand durable in use.
In the drawing:
Fig. 1 is a diagrammatic view of an air conditioning or refrigerating system.
Fig. 2 is a sectional enlargement of my combined thermo and time controlled valve.
Fig. 3 is a sectional enlargement of a section taken around the valve proper of my thermo and time. controlled expansion palve, indicating the connection of the valve to the "sylphon on the thermal and solenoid sides of my refrigerating valve.
In the drawing there is shown for illustrative purposes a refrigerating system of the compressor-condenseriexpansionl type including a l2 to a receiver I4 in the nature of a suitable tank from which passes the liquid refrigerant through a ,conduit l5 to my time and thermo l controlled expansion valve, designated generally at 20, and thence through a conduit 2|' to the cooling .unit or expansion coils 22 and then through a return conduit 24 to the compressor I0.
A thermo bulb having a suitable thermo responsive fluid therein is indicated at 30 as attached to the return line 24 and as having a tube 3| connecting it to a thermo bellows 32 acting on the expansion valve as will presently appear. At 35, is indicated a suitable timing mechanism, which may be an electric clock or the like and which may close a circuit through a solenoid indicated at 40, also acting on the valve as will be described.
My improved form of expansion valve shown in section, in Fig. 2, comprises generally a hollow housing having at the top a latterly' extending portion providing a passage 45 with which the conduit I5 communicates and from which leads a smaller or reduced passage 46 communicating at its lower point with a valve orifice 48, adapted to be closed, and to have the extent of opening controlled by a pointed or needle type valve member 50. The valve member 50 is mounted upon a movable rigid carrier 52, shown as having upright end portions and an intermediate portion extending across the lower end of the boss formed on the casing and in which the passage 46 terminates in the valve orifice 48. The casing forms a chamber 53 from which conduit 2| leads. Extending each way from the chamber are hollow threaded projections 54 and 55. On the member 54 is preferably a flanged head 56 threaded thereto and having a partition like wall 51 and an outwardly extending flange 58, which is tightly secured to a plate 59,.and on which is tted the flanged cap or housing for the solenoid. The solenoid coil is indicated at 68 and its core or armature 62 is connected by a stem 65 slidable through a sleeve 66, threaded into the wall 51 and by means of a bore in the stem 65 a support is made for the pilot stem of the valve member 50. Around the stem and sleeve 66 and also rigidly secured to the upright portion member 52 and the valve is a bellows 68 commonly referred to as a sylphon. 'I'his prevents leakage of the liquid or gas from the chamber 53. The stem 65 is slidable through sleeve 66. A spring 10 between the end of the sleeve 66 and the end wall of the "sylphon bellows urges the valve to a closed position, preventing the loading up of the evaporator with refrigerant during the off load periods of the evaporator. By action of the armature of the solenoid 60, the spring pressure against the valve is released allowing the condition in the outlet of the evaporator which is reflected through the thermal bulb 36 and thermoy responsive bellows 32 to control the distance of .withdrawal of the valve from its seat, as will intermittent reaches of At is shown a revolving disk carrying adjustablymounted cam-like members 82, indicated as secured by a screw 83 and slot 84 which is one of several arcuate slots in this revolving disk, and by which the position of the cam or a plurality of cams may be arranged to effect desired timing of the closing of the switch. The closing is effected by this cam engaging a raised button or the like as at 86 on the upper contact member so that as the cam moves past, it is closed for a momentary interval, thus closing the circuit to the solenoid, energizing the same and moving the armature 62 outwardly to release the pressure of the spring against the valve member 50, allowing free action of the thermo bellows 32 to con-- trol the amount of opening of the valve. The disk-84 is shown as mounted on a shaft 85 which may be rotated by any suitable time device such as an electric clock mechanism.
vThe connecting bracket member 52 has its leit upright portion rigid with the end of a I bellows lor sylphon element 90 and it is also connected by a pin or spindle 92, slidable through a wall member 53 Within the housing surrounding the sylphon elementl 32, shown as threaded to thev extension 55 of the valve housing. Suitable gas and liquid tight connections indicated at are provided to further insure against a leakage.
As thethermo liquid of the bulb 30 and bellows 32l is aiected'by the temperature of the tube or passage 24, the connecting stem 92 is moved, thus positioning the bridgingl element 52 and the valve 50, according to the condition of the system. That is, if the cooling system requires no refrigerant the contracted condition of the bellows 32 will keep the valve 50 seated upon the energizing of the coil 60 of the solenoid 40.
'If however, an intermediate condition requiring some refrigerant exists, the bellows and its connections with the valve, will permit slight opening in varying l degrees and distances, of opening of the valve from its seat in the orifice 48. vAssuming that the system requires the maximum supply of the refrigerant the expansion of thefthermo bellows will fully open the valve, as for example, to the position in Fig. 3, allowing free passage of the refrigerant iiuid from the passage 48 to themchamber` 58 and thence to the cooling Vcoils 22 as described.
I have found, as described in my Patent No. 2,047,799, that thetiming may be effected, with relation to the passage of the intermittent volume or the charges of refrigerant to the coils fromV the expansion chamber 53 of the expansion valve, with such relationship to portions of the .cooling elements as may beinsulated from other portions, that the warm spots will be outside of the stream or body of air to be cooled, and the expansion of the volumes of gases pass'- ing in series of separate charges through the coil will occur principally in the intervening or air being refrigerated.
To illustrate this it maybe assumed that-the \l,ines |00 represent partitions or walls of a passage for refrigerated airbetween which the A air passes upwardly as indicated by the arrows the coil exposed to the increase in eiliciency as a result of this arrangement and timing of the intermittent volumes sucessively released to the expansion coils.
summarizing the operation it will be seen that the refrigerant is Vliquefied bythe use of the compressor I0 and condenser coils I2 and is stored in the receiver I4 and 4from which it passes to the expansion valve orifice 48 in liquid form. Here it is released at predetermined time intervals, the quantity released being de .termined bythe state of expansion of the fluid of the thermo expansion device, including the sylphon bellows 32, connected with the valve as described. Thus the desired amount of refrigerant is released into the chamber 53 from which it passes to the coil 22; The rapidity of its passage'and the beginning of its expansion at the predetermined time intervals having reliationship to the cooling reaches l |03 of the evaporator coil, eiects expansion in these air passages subjected to the relatively higher temperature with the results above described.
It will be seen that the intervals of time may y be varied by the amount of contact of .the moving element 82-and the button 86 on the spring switch or contact elements.
The method of release of the intermittent and relatively isolated charges is more fully described and claimed in my prior application above referred to, but has been here summarized for convenience, and further as illustrative of the valve control mechanism comprising the subject matter of this application.
The rapidity of the revolving of the disk 80 may be varied and for a given rotation any suitable number of actuating cam members 82 may be placed on the carrier 85, as desired. It is to be understood thatthe specific construction and particular details described may be varid'without departing from the spirit of my invention. They are given as illustrative and embody a construction found successful in operation and accomplishing the objects above described. However, it is not intended to linut the scope of the invention, except as defined by the appended claims.
, Having thus described my invention, vwhat I claiml is:
1'. Air conditioning apparatus comprising a condenser for the refrigeranhan evaporator comprising a plurality of connected spans of tubing and strips of metal extending from one of said spans to another forming continuous iins, an expansion valve between said condenser and said evaporator, temperature responsive means associated with said evaporator and means for actuating said valve at timed intervals, the effective valve opening being controlled by said temperature responsive means.
2. Air conditioning apparatus comprising a condenser for the refrigerant, an evaporator comprlsing aplurality of connected spans of tubing and means for conducting moisture from oner of said spans to another, an expansion valveV means.
3. The combination with an air conditioning apparatus comprising a container for the refrigerant, an evaporator, an expansion valve between the container and evaporator, means for operating said valve at intervals to open it where..
by the refrigerant is delivered to said evapora.- tor in impulses, means to vary the frequencies and length of said intervals, and means responsive to the thermal condition of the evaporator for 'governing the amount of opening of said valve.
4. In an air conditioning. apparatus, the combination of a container for refrigerant, an evaporator, an expansion valve between said container and evaporator, means for operating said valve at regular timed intervals whereby the refrigerant is delivered to said evaporator in separated charges, means for varying the frequency ofy said intervals or valve opening, and means responsive to the thermo condition of the evaporator for varying the extent of opening of said valve.
5. In an air conditioning apparatus, the combination with a condenser and an evaporator, of an expansion valve between the condenser and evaporator, a temperature responsive means associated with said evaporator for controlling the extent of opening of the valve and means for actuating the valve to open it at predetermined time intervals.
6. In an air conditioning apparatus, the combination of a container for refrigerant with a condenseig'an evaporator therefor, of an expansion valve between said condenser and said evaporator, means for opening said valve at prede-l termined timed intervals, andmeans connected with said valve including a thermo-responsive element associated with the evaporator for governing the amount of opening of said valve.
7. A system for conditioning air, comprising the provision of a condensing and expansion means for a refrigerant, and an expansion valve between said means, and the provision for insulating separated portions of the expansion means and exposing the intermittent portions'to the air to be conditioned, the provision of. means for intermittently opening said valve at predetermined time intervals to release charges of the refrigerant to the expansion means, and the provision of thermo responsive means connected with the valve and associated with the expansion means for governing the amount ofvalve opening, and wherebysaid charges pass throughthe system in suitable stagesof expansion in the portions of the expansion means `*exposed to the air to be conditioned. i
8. An expansion valve for use-"between the pressure and the expansion sides of a refrigerating system, means for operating the saine n for varying amounts of opening and at predetermined time intervals comprising a casing having i passage for .the refrigerant, a valve element for closing said passage, an electro magnetic device for opening the valve, a circuit governing the same, a time mechanism for intermittently closing said circuit and a thermo responsive means associatedk with the low pressure side of the system connected with the lvalve to control the amount of vvalve opening upon actuation of the electro magnetic means.
9. A valve mechanism for controlling the passage of refrigerant from the pressure side to the expansion side of a coolingsystem, comprising.
a casing having a passage for a refrigerant, a valve element, resilient'means tending to seat said element to close the passage, a solenoid mounted on the casing and having an armature connected with the valve to open the same, a normally open circuit for the solenoid, contacts, and a clock actuated means for intermittently closing the contacts for causing the valve to open, a member cormected with the valve, and thermoresponsive movable elements connected to said valve and associated with the expansion side of the system to govern the extent of opening of the valve.
10. In a refrigerating system of the compression-expansion type including a means for compressing said refrigerant, an evaporator, an expansion valve between said compression means and said evaporator, said expansion valve comprising a casing having passage for the refrigerant, a valve element for closing said passage, electro-magnetic means for opening the valve at timed intervals, and a thermo-responsive means associated with said evaporator controlling the amount of valve opening when actuated by said electro-magnetic means.
CLARENCE A. RODMAN.