CA1217464A

CA1217464A - Weight-monitored air-conditioner charging station

Info

Publication number: CA1217464A
Application number: CA000451269A
Authority: CA
Inventors: Arthur G. Hobbs, Jr.; Robert H. Proctor
Original assignee: Individual
Current assignee: Standard Motor Products Inc
Priority date: 1983-05-23
Filing date: 1984-04-04
Publication date: 1987-02-03
Also published as: US4513578A

Abstract

ABSTRACT OF THE DISCLOSURE
A mobile air-conditioner charging station is disclosed which has a reluctance-type weighing scale on which are mounted reservoirs of both lubricant oil and refrigerant. A computer module reads the weight loss of the combined reservoirs as, first, the oil is charged into the air-conditioner and then, sequentially and automatically, the refrigerant is charged into the air-conditioner. Each charging cycle is completed when the computer module senses, by a plurality of discrete readings of the scale at timed intervals, that a pre-selected magnitude of weight loss has occurred and has been maintained.

Description

7~

~8~2-5~

This invention relates generally to the field of refrigeration systems and, more specifically, to the charging or recharging of sucil systems with refrigerant and lubricant, particularly au-tomotive air-conditioning systems.
With the increased popularity of air-conditioning systems in vehicles, the necessity for c]-arging or re-charging such systems has become a common function of automotive service stations and garages. 'I'o this end, charging stations or service units have been developed over time in an effort to reduce the man-hours required for the charging sequence and to improve the reliability and accuracy of the charging sequence. The objective has been to divorce the procedure from the requirement for skilled experts and permit its use by general automotive mechanics, and to free the serviceman from a routine~
time-consuming task for much more productive effort.
Accordingly, in the early days of the charging art, elaborate manuals were prepared for the re-charging procedure As the art developed, attempts have been made to effect constant-flow metering of the charge in association with timers, as well as visual forms of indicators denoting attainment of a desired condition in the re-charging cycle. This has been accompanied by the development of the aforesaid charging stations in the form of compact, mobile units which contain and dispense lubricant and refrigerant.
The progress of the art over the past 25 years is exemplified in Shoemaker, United Sta~es Patent No.2,~99,170; White, United States Patent No. 3,076,319; Wagner, United States Patent No. 3,785,163, Gemender et al, United States Patent No. 3,813,893; and White, United States Patent No.3,873,289.
Shoemaker supplies a predetermined weight of oil and refrigerant to a reservoir for injection into the refrigeration system after evacuation.

-1- ~

~2~7~
Wagner uses a change oF state, from 11qu1d to saturated vapor, for the refr~gerant to provide v~sual 1nd~cat1On when an opt~mum charge has been attalned. Gemender et al use a thermostat1cal1y controlled valve and a restr1cted rate of refrigerant flow to permit control of the charge.
White, Patent ~o. 3,076,319, automates the chary~ng sequence by ut~l~z~ng pressure-respons~ve elements and a stepper switch. White, Patent No. 3,873,2~9, controls refrigerant flow rate by pressure drop through a restr1cted or~f1ce and uses t~mers for sequenc~ng.
It w~ll be noted that the later patentees have found ser~ous dls-advantages ln the ~ntroduction of a pre-we~ghed quantlty of refrlgerant and oil 1nto the a1r-cond~t1Oner system, as d~sclosed by Shoemaker. Therefore, the later patentees have developed other systems of t7med ln~ectlon or pressure-respons~ve control which do not relate directly to the we~ght of refrlgerant or of o11, despite the fact that we19ht is the most des~rable measure, as ~t ~s substant~ally free of var~atlons resultlng from temperature or pressurc changes and ls cons1stent w~th des1gn crlteria and spec~f1cat10ns.
The present ~nventlon avo1ds the d~sadvantages of the Shoemaker d~sclosure by deal~ng with we~ght d~fferent~als of large reservo~rs rather than deallng ~lth the we19ht of a d~screte charge 1tself. The present ~nvent~on avo~ds the d~sadvantages and 1naccurac~es of the later systems, whlch are not directly related to we1ght of charge, by dlrectly us~ng we~ght as the utl~mate measure of the deslred charge.
The 1nvent~on ~s d1rected toward prov1s10n of an 1mproved automated charg~ng stat~on of h19h accuracy and rel1abll1ty.
This 1s accompl~shed by ut~l~zat~on of dlfferent1al welght sens1ng means to d~spense prec1se quant~tles of refr~gerant and o~1 from storage reservo~rs.

~ L7~6~

According to the ~nvention there is prov~ded, ~n a f~rst embod~ment, ~n an a~r-conditioner charging station, the combinat~on of:
a powered vacuum pump for evacuat~on of the alr-cond~tioner, a reservo~r of o~l under pressure, a reservolr of refr~gerant under pressure, valve means for selectively connecting sa~d pump and each of sa~d reservo~rs to the a~r conditioner to be charged, we~gh~ng means, common to both sa~d reservoirs, for sensing the comblned we~ght thereof, an electronlc micro-processor sequencing un~t operat~vely associated wlth sald valve means and sa~d we~gh~ng means, including ad~ustable we~ght d~fferential input sett~ngs, and actuat~ng means for in~t~ating operation of said sequencing unit to sequent~ally charge a pre-selected we~ght of oil from said oil reservo~r and then a pre-selected weight of refrigerant from said refr~gerant reservoir into the a1r-cond1tioner.
In a further embodiment there ~s prov~ded, ~n an air-condit70ner charging station, the comb~natlon of a reservo~r of refr~gerant under pressure, a condult means and electr~cally operated valve means for selectively connecting the reservoirs to the a1r-cond~t~oner to be serv~ced, welgh~ng means for sensing the we~ght and for producing an ouput s~gnal proportional to the we~ght of the reservo~r9 electronic sequenc~ng means operat~vely assoclated w1th the valve means and the we~ghing means for rece~v~ng the output signal ~or monltoring weight loss ~rom the reservo~r as refr~gerant is d~scharged therefrom and for generating s~gnals for controlling the valve means, ad~ustable weight d~fferential input means operatively connected to the sequenc~ng means for lntroduc~ng into the sequenc~ng means selected values representative of pre-selected weight of refrlgerant to be discharged from the reservoir, and means for ln1t~ating 7~6~
operatlon of the sequencing means to receive and mon1tor the weighing means output signal and to provide signals to the control valve means for charg1ng a pre-selected weight of refrlgerant from the refrlgerant reservoir tnto the alr-conditioner.
In a further embodiment of the 1nvention an a~r-conditioner charglng stat1on is provided.
Other ob~ects and advantages of the invention will appear more fully ~n the course of the following descr~pt10n.
In drawings which illustrate embodiments of the lnvention:
Figure l is a front elevation of a charg~ng station embody~ng the features of the inventlon, port~ons thereof being broken away to show the interior storage areas;
F~gure 2 is fragmentary rear elevatton of the upper portlon of the sharglng statlon, with the access panel broken away to show the dlspos1tion of certain valves and other components; and F~gure 3 is a side elevation of a welgh1ng scale util1zed ~n the invention, portions thereof being broken away to show greater deta~l.
-~ . _ . .

- 3a -~2~

Referring to Figures 1 and 2 of the drawing, there is shown a charging station 10 which includes a storage cabinet 11, mounted for mobility on casters 12, and surmounted by a control pallel 13.
The cabinet 11 is provided with optional storage drawers 14 and with hinged doors 15 and 16 which provide access to the interior o-f the cabinet, when opened. In Figure 1, portions of these doors have been broken away to show a motorized vacuum pump unit 17 mounted interiorly of the cabinet on one side of the base thereof. On the other side of the base of the cabinet interior there is mounted a weighing scale 18 having a pla~form 19 on which is secured a pressurized refrigerant canister or reservoir 20 by means of a suitable detachable ~racket assembly 21. Also mounted on the platform 19 and secured thereto by a suitable detachable bracket assembly 22 is a pressurized oil cylinder or reservoir 23. Each of the canisters is provided with its own conventional shut-off valve (not shown) which, when opened, permits the refrigerant reservoir to communicate through hose 24 with a solenoid valve 25 and permits the oil reservoir to communicate through hose 26 with a solenoid valve 27. A hose 28 provides communication from the vacuum pump to a solenoid valve 29.
- As best seen in Figure 2, the valve 25 communicates with a charging port 30 through conduit 31 and communicates with a low pressure gauge 32 through conduit branch 33.
The valve 27 i.s provided with a conduit 34 by means of which the pressurized oil can be directed to the charging pori 30, by joinder with the refrigerant conduit 31.
The evacuation valve 29 also communicates with port 30 through a conduit 36, by joinder with the refrigerant conduit 31.

~2~L7~

A h~gh pressure port 35 ~s provlded for connect~ng a hose to the high pressure side of the refr~geratlon system be~ng serv~ced. A h~gh pressure conduit 37 leads from th~s port 35 to the inter~or of the storage cab~net ll.
A condu~t branch 37a connects the h~gh pressure condu~t 37 to a h~gh pressure gauge 38. Operat~onally, the high pressure condu~t 37 is used for "dump~ng"
the fluid contents of the a~r-cond1t~oner be~ng serv~ced pr~or to evacuat~on, through a valve 55a, as well as for monitor~ng system pressure vla gauge 38 dur~ng charging.
Operat~onally another low pressure conduit 39, branch~ng from the refr~gerant condu~t 31, can be prov1ded for communication w~th an accessory port 40 for non-automated low pressure d~scharge? such as pressur~z~ng the o~l cylinder or d~scharging a small can~ster.
An electron~c computer module 41 wh~ch ~ncorporates a m~croprocessor sequenc~ng un~t ~s operat~vely connected to the var~ous components prev~ously descr~bed, rece~vlng s~gndls from scale 18 and manual controls, and send1ng slgnals to control valves; the sequenc~ng un~t also serves to energ~ze a d~g~tal we~ght d~fferent~al d~splay 42 on the control panel 13.
An electron~c s~gnal in the form of a buzzer or beeper array 43 ts also mounted on the ~nter~or of the control panel and operatlvely connected to the module 41.
A removable access cover 44 ~s secured to the back of the control panel. In F~gure 2 large port~ons of the panel 44 have been broken away to show the above-descr~bed component locations.
As best shown ~n F1gure 3 of the draw~ng, the ~e~gh~ng scale lB ~s of the type wh~ch produces an output s~gnal proport~onal to we~ght; preferably, ~t ~s of the electr~cal reluctance type wh~ch ut~l~zes a current-carry~ng co~l 45 and a movably-mounted metal armature 46 pro~ect~ng ~nto the center of the co~l. The armature 46 ~s secured by an ad~ustable support bracket assembly 47 to a U-shaped scale beam 48 to whtch the platform 19 1s f~xedly secured by a _ 5 _ ~L2 ~7~
po~t ~9.
The beam 48 is yieldably mounted by a parallelogram arrangement of leaf spr~ngs 50. Two horizontally-spaced parallel leaf sprlngs 50 extend hor~zontally from the upper port~on of the beam to securement w~th the upper portion of an L-shaped base 51. Another pa~r of spaced parallel leaf spr~ngs 50 extend hor~zontally from the lower port~on of the beam, parallel to the upper spr~ngs 5~, to the lower port~on of the base 51. The base 51 also serves as an anchor for a coll support member 52 to wh~ch the coil 45 ~s fixedly secured.
The res~l~ent parallelogram mount~ng of the beam 48 perm~ts substant~ally linear movement of the beam ~n response to changes in load on the platform l9. The movement of the beam ~s directly transm~tted to the armature or transducer ~6 and the electromagnetlc changes effected by ~ts interact~on w~th the co~l 45 are transmltted to and sensed by the computer module 41. An ad3ustable stop 53 ~s mounted on the beam 48 for abutment w~th the base 51, so as to l~m~t movement of the beam to ~ts operat~ng range and prevent excess~ve d~stort~on or deformat~on of the ~ovable beam assembly.
The operat~on of the charg~ng stat~on ~s as follo~s, us~ng the m1croprocessor sequenc~ng un~t of electron~c computer module 41 and the manual controls are ~llustrated ~n F~gure l. Bas~cally, the re-charg~ng procedure cons~sts of empty~ng and evacuat~ng the a~r-cond~t~on~ng or refr~gerat~ng apparatus, as necessary, then charg~ng lubr~cat~ng o~l ~nto the apparatus, and then charg~ng refr~gerant ~nto the apparatus. The deta~led hook-ups and quant~t~es for accompl~sh~ng the forego~ng are well-known in the art and therefore requ~re no ~urther explanat~on.
As best seen in F~gure 1, the control panel 13 carries an "on-off"
power sw~tch 54 wh1ch ls man~pulated to energ~ze the charg~ng stat~on's electr7cal and electron~c components from a convent~onal power source. There ~s also a bleed valve control knob 55 whlch ls turned to open valve 55a 79L~i~

to discharge or "dump" the fluid contents of the air-conditioner through the high pressure conduit 37 before evacuation. A discharge catch tray (not shown) is provided under the cabinet base, equipped with steel wool to entrap the oil carried with the discharging refrigerant.
A vacuum timer 56, calibrated in minutes, serves to hold open the solenoid valve 29 for a selected time interval. The vacuum pump 17 will operate during the selected time interval, nominally ten minutes for the usual size of passenger vehicle air-conditioner, and then evacuation should be complete, as evidenced by a reading of 30 inches Hg on the low pressure gauge 32. ~uring evacuation, no other functions of the charging station will be performed, even though charging quantities have been pre-set for the oil and refrigerant charges. An indicator 57 remains lighted until the timed evacuation is completed.
The charging settings can be selected either during evacuation or upon completion o-f evacuation, as desired. First, a setting knob 5~, which is calibrated in pounds, is set to the selected weight of refrigerant to be charged.
As this control knob is manipulated, the changing settings are visible in the digital display 42, in pounds and ounces avoirdupois, accurate to 0.2 ounces, so that an extremely precise setting to a decimal fraction of an ounce can be established. ~hen the desired setting is achieved, a set button 59 is momentarily depressed to feed this setting to the computer memory, which acknowledges receipt by initiating an audible "beep". As will appear more fully hereinafter, the button 59 also serves as a sequence interrupter during the charging cycles. The operation of the set button 59 clears the refrigerant setting from the digital display 42.
Thereafter, another setting knob 60, calibrated in fluid ounces, 7~6~L
is set to the deslred volume of oil to be charged, whlch ~s s~milarly d~splayed ~n ounces on the dig~tal dlsplay 42. When the desired o~l sett~ng ~s achieved, a "Start" sw~tch or button 63 on the control panel ~s momentarlly depressed to ~eed th~s sett7ng to the computer memory. Rece~pt of the otl sett~ng ~s acknowledged by an audible "beep".
If ~t ~s des~red to charge the a1r-cond~tloner only w~th refr~gerant, but not with o~l, a zero sett~ng ls used for the o~l. S~m~larly, ~f ~t were des~red to charge only o~19 but not refrigerant, a zero sett~ng would be used for the refr~gerant.
If the refr~gerant and o~l charge setting have been made dur~ng the t~med evacuat~on ~nterval, then upon complet~on of evacuat~on, the s~gnal l~ght 57 goes out, a "beep" s~gna7 ~s heard, an o~l charge signal 61 ~s actuated, the soleno~d valve 27 opens, and o~l under pressure ~s automat~cally charged into the a~r-cond~t~oner. Dur~ng th~s o~l charg~ng cycle, the d~g~tal d~splay 42 w~ll cont~nually be chang-~ng to reflect the rema~n~ng quant~ty of charge yet to be madei ~.e., the d~g~tal d~splay approaches a zero read~ng as the computer mon~tors the we~ght loss ~nd~cated by we~gh~ng scale 18.
It is to be noted that ~t has become a standard pract~ce ~n the art to use flu7d ounces as the quant~tat~ve measure of the oil charge. In order to conform to th1s pract~ce, the o~l charge ~s set and d~splayed ~n flu~d ounce measure. However, as the scale 18 senses only we~ght, the computer module 7s programmed to convert the o~l charge sett~ng to ounces of we~ght and mon~tors the charge ~n a we1ght-equ~valent to the flu~d ounce sett~ng.
When a zero read~ng ~s atta~ned on the d~splay ~2, ~nd~cat~ng that the des~red we~ght-equ~valent charge of o11 has been d~spensed, the soleno7d -valve 2~ closes. Howeverl the computer module cont~nues to mon~tor the scale 18 at short ~ntervals9 e.g. l l/3 seconds, several t~mes, say f~ve t~mes, to 7~6~

confirm that the scale 18 is stable and that the zero reading is, in fact, true.
If a false zero reading has been momentarily attained as a result of sca]e 18 being disturbed by movemen-t of the charging s-tation or by someone or something bumping into it, then the zero reading will not be confirmed and solenoid valve 27 will open again to conti.nue the oil charge until a true zero reading, indicating completion of the charge, is attained, and valve 27 closes.
After completion of the oil charge, an automatic short timed pulse of chase refrigerant is directed through hose 24$ conduit 31, and out port 30 to clear the lines of retained or residual oil, so that the full charge of oil is dispensed into the air-conditioner. Signal light 61 is extinguished, and a "beep" sound is heard signalling completion of the oil charge cycle and automatic starting of the refrigerant charge cycle.
At the initiation of the refrigerant charge cycle, the digital display 42 is cleared and the previously set selected ~Yeight of refrigerant charge is displayed. A visual signal 62 lights up and solenoid valve 25 opens to charge pressurized refrigerant into the air-conditioner.
In the same manner explained above, the computer module monitors the weight loss on scale 18, continuously indicates on the display 42 the remaining weight of refrigerant yet to be dispensed, confirms the zero reading by repeated discrete monitoring of scale 18 at short time intervals, re-opens valve 25 to continue dispensing if a false zero reading was indicated by scale 18~ and finally closes valve 25, de-energizes signal light 62, and sounds an audible "beep" signal that the operation has been completed.
It will be noted that the charging cycles for the oil and refrigerant are completely automatic and are initiated by completion of the evacuation cycle, so that all three phases of the operation are automatic once ~%~

the quant~ty sett~ngs have been made and the evacuat~on cycle started.
There may be c~rcumstances when it ~s considered desirable to complete the evacuation cycle and v~sually mon~tor the read~ngs on the low pressure gauge 32, w~thout automatically ~n~t~ating the subsequent charg~ng cycles. If such ~s desired, then the operator s~mply postpones enter~ng the oil and refrigerant quantlty sett~ngs unt~l after evacuation has been satisfactorily completed. The charg~ng cycles are then ~n~t~ated by momentary depresslon of the "Start" button 63 on the control panel, and the automat~c operation commences.
There may also be c~rcumstances when ~t ~s considered desirable to om~t the evacuat10n cycle. In such cases the operator proceeds directly to mak~ng the refr~gerant and o11 quant~ty sett~ngs. The charg~ng cycles are then ~nit~ated by momentary depresslon of the "5tart" button 63, and automat~c operat~on commences.
~ hether the charg~ng cycles are automat~cally ~n~tiated upon complet~on of the evacuat~on cycle, or d~rectly ~n~t~ated ~ndependently of e~acuat~on by pressing button ~3, the computer module 41 ~s programmed to start read~ng or mon~toring the load on scale 18 at the start of the o~l charg~ng cycle, not sooner. Thus, any lnaccuracy or changes ~n the scale read~ngs wh~ch may occur due to metal fat~gue or temperature dr~ft ~n the scale 18 over a per~od of t~me, or even ~n the relat~vely short t~me span of the eYacuat7on phase, are ~gnored and el~m~nated. Thereby, the measure of charge, as determ~ned by the targeted we~ght loss or load d~fferent~dl on scale 18, can be atta~ned w~th extreme accuracy.
The computer module 41 not only cont~nuously monltors the we~ght loss on scale 18 dur~ng each of the charg~ng cycles, ~t also mon~tors the rate - ln -~%17~ii4 of weight loss so that any interruption or excessive slowdown in the transfer of the charge to the air-conditioner causes an audible "beep" alarm signal to be sounded. Such restriction or interruption of flow to the air-conditioner is ordinarily the result of an inadequate supply of pressurized oil or refrigerant in the charging reservoirs 20 or 23 or may result from the existence of an inadequate pressure differential between the charging system and the air-conditioner.
When this distinctive alarm is sounded, the operator can visually observe which charging cycle, whether oil or refrigerant, is affected by noting which signal light 61 or 62 is lit. The operator can then place the entire charging system in "Hold" status, by momentarily depressing switch button 59 --which will cause closing of the solenoid valve 25 or 27, as the case may be.
The operator can then check the pertinent reservoir 20 or 23 and replace it, if necessary, with a full canister. It will be apparent that this replacement will establish an entirely new and different load or weight on scale 18. But, inasmuch as the charging system herein described monitors loss of weight on scale 18 rather than weight directly, when the charging cycle is removed from "Hold" and restarted by momentary depression of button switch 63~ the computer module 41 continues its monitoring at exactly the same point in the cycle where it was placed on "Hold". Thus, the computer module will concern itself only with the remaining weight differential required to complete the charge, despite the intervening change in load on scale 18; no re-setting of the quantity of charge is required. Similarly, any adjustments required to be made to the air-conditioner to correct the inadequate pressure differential problem will not require re-setting of the charge quantities to re-start the charging cycles from the point of interruption.

7~

For example, it has been determined that the flow interruption alarm should be actuated if the charging rate of oil is more than 30 seconds per ounce or if the charging rate of refrigerant is more than one minute per pound, although other paramaters could be established, as desired, and programmed into computer module 41.
Additional safety features for the charging system relate to excessive discharge pressure and to inadvertent start-up of the vacuum system during operation of a charge cycle. If the vacuum timer 56 is manipulated during a charging cycle, an alarm sounds and the charging cycle is automatically terminated. Similarly, if the discharge pressuro reaches a dangerous level, e.g. 275 psi, as sensed by a high pressure cut-out switch 64, the alarm sounds and the charging cycle is automatically terminated.
In either circumstance, the situation must be investigated and corrected.
Then the whole operative cycle of the charging station must be re-initiated, including the steps of setting the quantities of oil and refrigerant to be charged into the air-conditioner.
It is to be understood that the above-described embodiment of the invention is a preferred example of the same and that various changes and modifications may be made without departing from the scope of the subjoined claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

l. In an air-conditioner charging station, the combination of:
(a) a powered vacuum pump for evacuation of an air-conditioner;
(b) a reservoir of oil under pressure, (c) a reservoir of refrigerant under pressure, (d) a conduit means and electrically operated valve means for selectively connecting said pump and each of said reservoirs to the air-conditioner to be serviced, (e) weighing means, common to both said reservoirs, for sensing the combined weight thereof and for producing an output signal proportional to the combined weights of said reservoirs, (f) electronic sequencing means operatively associated with said valve means and said weighing means for receiving said output signal for monitoring weight loss from said reservoirs as oil or refrigerant is discharged therefrom and for generating signals for controlling said valve means, (g) adjustable weight differential input means operatively connected to said sequencing means for introducing into said sequencing means selected values representative of preselected weight of refrigerant and oil to be discharged from said reservoirs, and (h) means for initiating operation of said sequencing means to receive and monitor said weighing means output signal and to provide signals to said control valve means for sequentially charging a preselected weight of oil from said oil reservoir and then a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner.
2. A combination as defined in claim l, and Further including means responsive to completion of said oil charge for initiating a short timed pulse of refrigerant charge to chase residual oil from said charging station into the air-conditioner.
3. A combination as defined in claim 1, and further including a digital visual display unit for said selected weight differential input means, and wherein said sequencing means senses the weight loss in said reservoirs during said charging cycles and said display unit continuously indicates said weight loss.
4. A combination as defined in claim 3, wherein said sensing of weight loss by said sequencing means is continuous until said preselected weight of charge is indicated as having been dispensed, and including multiple discrete sensing of said weight loss at timed intervals in response to completion of said continuous sensing, whereby to obtain confirmation of stabilized attainment of said pre-selected weight of charge prior to cessation of the charging cycle.
5. A combination as defined in claim 3, wherein said sequencing means senses both the weight loss and the rate of weight loss in said reservoirs, and including signal means actuated in response to a separate predetermined parameter of rate of weight loss for each of said reservoirs.
6. A combination as defined in claim 3, including manually-actuated interrupter means for said microprocessor sequencing means, whereby sequencing can be arrested at any step thereof and restarted from the point of arrest.
7. A combination as defined in claim 1, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.
8. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:
(a) a powered vacuum pump for evacuation of an air-conditioner, (b) a reservoir of oil under pressure, (c) a reservoir of refrigerant under pressure, (d) conduit means and electrically operated valve means for selectively connecting or disconnecting said vacuum pump and each of said reservoirs to the air-conditioner to be serviced, (e) weighing means for sensing the weight of said reservoirs and for substantially continually producing an output signal proportional thereto as weight is decreased during charging, (f) electronic sequencing means including adjustable oil and refrigerant preselected weight differential input means operatively associated with said valve means and said weighing means for receiving said output signal from said weighing means for monitoring weight loss as oil or refrigerant is discharged from a said reservoir into said air-conditioner and for generating signals, including a signal to a said valve means for disconnecting a said reservoir from the air-conditioner upon receiving a signal indicating that the preselected weight of charge has been dispensed, (g) means for initiating operation of said sequencing means for sequentially changing a preselected weight of oil from said oil reservoir and then a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner, (h) said electronic sequencing means including means for sensing weight loss after the generation of said signal for disconnecting said reservoir at multiple discrete timed intervals and for generating a signal to the said valve means for connecting said reservoir to the air-conditioner upon receiving a signal indicating that a false signal of dispensed weight change was received, whereby to obtain confirmation of stabilized attainment of said preselected weight change.
9. An air-conditioner charging station as defined in claim B, wherein said sequencing means senses rate of weight loss in said reservoirs, and including signal means actuated in response to a separate, predetermined parameter of rate of weight loss for each of said reservoirs.
10. An air-conditioner charging station as defined in claim 9, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.
11. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:
(a) a powered vacuum pump for evacuation of an air-conditioner, (b) a reservoir of oil under pressure, (c) a reservoir of refrigerant under pressure, (d) d conduit means and electrically operated valve means for selectively connecting or disconnecting said vacuum pump and each of said reservoirs to the air-conditioner to be charged, (e) weighing means for sensing the weight of said reservoirs and for substantially continually producing an output signal proportional thereto as weight is decreased during servicing, (f) electronic sequencing means operative associated with said valve means and said weighing means for monitoring weight loss and rate of weight loss as oil or refrigerant is discharged from a said reservoir into said air-conditioner, (g) adjustable weight differential input means operatively connected to said sequencing unit, (h) means for initiating operation of said sequencing means for sequentially charging a preselected weight of oil from said oil reservoir and then a preselected weight of refrigerant from said refrigerant reservoir into the air-conditioner, and (i) signal means actuated in response to a separate predetermied parameter of rate of weight loss for each of said reservoirs for indicating an inadequate supply of pressurized oil or refrigerant in the charging reservoirs or the existence of an inadequate pressure differential between the charging system and the air-conditioner.
12. A combination as defined in claim 11, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.
13. In an air-conditioner charging station, the combination of:
(a) a reservoir of refrigerant under pressure, (b) a conduit means and electrically operated valve means for selectively connecting said reservoir to the air-conditioner to be serviced, (c) weighing means for sensing the weight and for producing an output signal proportional to the weight of said reservoir, (d) electronic sequencing means operatively associated with said valve means and said weighing means for receiving said output signal for monitoring weight loss from said reservoir as refrigerant is discharged therefrom and for generating signals for controlling said valve means, (e) adjustable weight differential input means operatively connected to said sequencing means for introducing into said sequencing means selected values representative of pre-selected weight of refrigerant to be discharged from said reservoir, and (f) means for initiating operation of said sequencing means to receive and monitor said weighing means output signal and to provide signals to said control valve means for charging a pre-selected weight of refrigerant from said refrigerant reservoir into the air-conditioner.
14. A combination as defined in claim 13 including a powered vacuum pump for evacuation of an air-conditioner.
15. A combination as defined in claim 13, further including a digital visual display unit for said weight differential input means, and wherein said sequencing means senses the weight loss in said reservoir during said charging cycle and said display unit continuously indicates said weight loss.
16. A combination as defined in claim 15, wherein said sensing of weight loss by said sequencing means is continuous until said pre-selected weight of charge is indicated as having been dispensed, and including multiple discrete sensing of said weight loss at timed intervals in response to completion of said continuous sensing, whereby to obtain confirmation of stabilized attainment of said pre-selected weight of charge prior to cessation of the charging cycle.
17. A combination as defined in claim 15, wherein said sequencing means senses both the weight loss and the rate of weight loss in said reservoir, and including signal means actuated in response to a separate predetermined parameter of rate of weight loss for said reservoir.
18. A combination as defined in claim 15, including manually-actuated interrupter means for said microprocessor sequencing means, whereby sequencing can be arrested at any step thereof and restarted from the point of arrest.
19. A combination as defined in claim 13, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.
20. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:
(a) a reservoir of refrigerant under pressure, (b) conduit means and electrically operated valve means for selectively connecting or disconnecting said reservoir to the air-conditioner to be serviced, (c) weighing means for sensing the weight of said reservoir and for substantially continually producing an output signal proportional thereto as weight is decreased during changing, (d) electronic sequencing means including adjustable refrigerant pre-selected weight differential input means operatively associatd with said valve means and said weighing means for receiving said output signal from said weighing means for monitoring weight loss as refrigerant is discharged from said reservoir into said air-conditioner and for generating signals, including a signal to a said valve means for disconnecting said reservoir from the air-conditioner upon receiving a signal indicating that the pre-selected weight of charge has been dispensed.
(e) means for initiating operation of said sequencing means for charging a pre-selected weight of refrigerant from said refrigerant reservoir into the air-conditioner, (f) said electronic sequencing means including means for sensing weight loss after the generation of said signal for disconnecting said reservoir at multiple discrete timed intervals and for generating a signal to the said valve means for connecting said reservoir to the air-conditioner upon receiving a signal indicating that a false signal of dispensed weight change was received, whereby to obtain confirmation of stabilized attainment of said pre-selected weight change.
21. An air-conditioner charging station as defined in claim 20 including a powered vacuum pump for evacuation of an air conditioner.
22. An air-conditioner charging station as defined in claim 20, wherein said sequencing means senses rate of weight loss in said reservoir, and including signal means actuated in response to a separate, predetermined parameter of rate of weight loss for said reservoir.
23. An air-conditioner charging station as defined in claim 22, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.
24. An air-conditioner charging station for charging refrigerant into an air-conditioner comprising:
(a) a reservoir of refrigerant under pressure, (b) a conduit means and electrically operated valve means for selectively connecting or disconnecting said reservoir to the air-conditioner to be charged, (c) weighing means for sensing the weight of said reservoir and for substantially continually producing an output signal proportional thereto as weight is decreased during servicing, (d) electronic sequencing means operative associated with said valve means and said weighing means for monitoring weight loss and rate of weight loss as refrigerant is discharged from said reservoir into said air-conditioner, (e) adjustable weight differential input means operatively connected to said sequencing unit, (f) means for initiating operation of said sequencing means for charging a pre-selected weight of refrigerant from said refrigerant reservoir into the air-conditioner, and (g) signal means actuated in response to a separate predetermined parameter of rate of weight loss for said reservoir for indicating an inadequate supply of refrigerant in the charging reservoir or the existence of an inadequate pressure differential between the charging system and the air-conditioner.
25. The air-conditioner charging station of claim 24 including a powered vacuum pump for evacuation of an air-conditioner.
26. A combination as defined in claim 24, and further including a high pressure cut-out switch for sensing discharge pressure, said sequencing means generating signals for terminating charging upon sensing of a high pressure by said high pressure cut-out switch.