US3789669A - Shirt pocket refrigeration gauge - Google Patents

Abstract

Briefly stated, the present invention contemplates a pocket instrument useful in a refrigerator compressor system. This instrument measures the pressure on the high and low sides or stages of the compressor by using the service valve located on the compressor. Generally speaking, the instrument has an elongated chamber, a reciprocating plunger in the chamber with an indicator with a lower end having a rod connected to said lower end. The rod in turn has a connecting boss at the lower end. In the chamber there is a reciprocating piston with an upper socket for receiving said boss when the boss is pushed by hand into the socket. Spring means urge the piston downwards and connecting means connect the compressor to the said service valve so that when the boss engages the socket, changes in pressure are indicated on the indicator, and when said boss is not so engaged, the highest pressure will be indicated on the indicator.

Description

United States Patent 1 1 1 89,669

Passman Feb. 5, 1974 SHIRT POCKET REFRIGERATION GAUGE Primary Examiner-Richard C. Queisser Assistant Examiner-Daniel M. Yasich [76] lnvemor' lmmokalee Attorney, Agent, or Firm-Alfred E. Wilson [22] Filed. June 5, 1972 ABSTRACT [21] Appl' 259970 Briefly stated, the present invention contemplates a pocket instrument useful in a refrigerator compressor [52] U.S. Cl 73/419, 62/125, 73/396 system, This instrument measures the pressure on the [51] Int. Cl. G011 7/16 high and low sides or stages of the compressor by [58] Field of Search 73/419, 396; 62/125, 292,508; using the service valve located on the compressor. 137/559 Generally speaking, the instrument has an elongated chamber, a reciprocating plunger in the chamber with [56] References Cited an indicator with a lower end having a rod connected UNiTED STATES PATENTS to said lower end. The rod in turn has a connecting 3,424,181 1/1969 Morse 62/292 x at the lower the Chamber there is a 1,126,146 1/1915 Werner 73 419 rocating Piston with an pp Socket for receiving Said 235,791 12/1880 Lyne 73/419 boss when the boss is pushed y hand into thesocket- 1,448,168 3/ 1923 Trusty et a1 73/419 X Spring means urge the piston downwards and connect- 2,049,364 7/1936 Fisher. 62/292 ing means connect the compressor to the said service 1,275,180 8/l918 ElllS 73/419 valve so that when the boss engages the ocket 3,152,473 10/1964 Emerson 73/396 X changes in pressure are indicated on the indicator, and 1,716,399 6/1929 Watters 73/419 X when said boss is not so engaged, the/highest pressure will be indicated on the indicator.

5 Claims, 2 Drawing Figures T SHIRT POCKET REFRIGERATION GAUGE BACKGROUND OF THE INVENTION The present invention relates to a refrigeration compressor auxiliary component, and more particularly to a dynamic pressure sensing arrangement used in connection with refrigerator compressors.

BRIEF REVIEW OF THE PRIOR ART The basic principle involved in refrigerating systems is that of transferring heat from an environment at low temperature to one at a higher temperature, by causing a volatile liquid (the refrigerant) to absorb heat at the low temperature by vaporization and to dissipate this heat at the high temperature by condensation. Vaporization and condensation are respectively induced by maintaining a lower or higher pressure than the saturation pressures of the refrigerant at the lower and higher temperatures.

In a compression refrigeration system a compressor is used, which may have either a positive-displacement mechanism (reciprocating or rotary compressor) or an impeller (centrifugal compressor). Although the thermodynamic cycle is the same for both types of compression, the kinematic considerations, particularly with regard to the refrigerant used, are markedly different. The dense-air machine operates on the Carnot cycle and the vapor-compression machine on the reversed Rankine (steam-engine) cycle.

In the ideal case, a piston at the beginning of the suction stroke touches the cylinder head and the volume is zero. As the piston moves out, vapor is drawn in and the volume increases at constant pressure. The vapor is now compressed adiabatically until the vapor pressure equals the condenser pressure after which it is forced into the condenser and the volume decreases to an amount corresponding to a measure of the compression work.

In the compressor it is necessary to provide a small clearance at the end (sfi'fi'eambress'ion stroke, and a" valve can conveniently be located above the clearance. Before suction can actually start, the vapor enclosed in this space expands adiabatically. Thus, in this system, the refrigerant, a volatile liquid with the proper physical properties, is changed from the liquid to the vapor phase through heat absorption at a low pressure and then from the vapor to the liquid phase through heat removal at an elevated pressure. The vaporization of the refrigerant takes place in the evaporator, that part of the system which is in contact with the material to be cooled. The pressure in the evaporator must be such that the corresponding boiling temperature of the refrigerant is below the temperature of the medium being cooled. Thus, heat will flow from the surrounding material to the refrigerant and cause vaporization. The vapor so formedis removed by rrieans of a coinpressor in order to maintain the low pressure in the evaporator. Through the addition of mechanical energy by the compressor, the temperature and pressure of the vapor are raised. The high-pressure vapor then passes to the condenser, where, through heat exchange with a cooler medium, such as water or air, its sensible and latent heats are removed with subsequent condensation. The pressure to which the compressor must raise the vapor is governed by the temperature at which the vapor is condensed (depending, in turn, upon the temperature of the cooling medium) and corresponds to the vapor pressure at that temperature. The heat removed in the condenser is the total of the heat picked up in the evaporator, the heat of compression, and any net heat gained by the system from the surroundings.

The hot liquid refrigerant passes from the condenser to the receiver, a storage reservoir, and thence to the expansion valve. The expansion valve controls the flow of refrigerant from the high-pressure side of the system to the low-pressure region. Since the hot liquid after passing through the valve is above the equilibrium temperature corresponding to the pressure in the evaporator, a portion of the liquid flashes (vaporized), thus reducing the remainder of the liquid to the equilibrium temperature. The refrigerant is then ready to pass through the cycle again.

As the refrigerant passes from the evaporator to the compressaifen'aehsr, expansion valve, and back to the evaporator, it undergoes several processes. These processes, in their sequence, constitute a heat cycle. The ideal cycle for refrigeration is the reversed Carnot heat-engine cycle, which consists of adiabatic expansion and compression and isothermal vaporization and condensation. This cycle, however, because it is ideal, cannot be applied to actual machinery, and only serves as a basis of comprison. The vapor compression refrigeration machine operates on the reversed Rankine cycle. Saturated liquid refrigerant enters the expansion valve at point and in passing through the valve the pressure drops and a portion of the liquid is vaporized to cool the refrigerant. This expansion occurs without change in heat content of the fluid. At the entrance to the evaporator, both liquid and vapor exist. As the refrigerant passes through the evaporator, it absorbs heat from the medium being cooled and the remainder of the liquid evaporates at constant temperature. The refrigerant leaves the evaporator as a saturated vapor and entrs the compressor, in which it is compressed at constant entropy to point where it exists as a superheated vapor. The superheated vapor enters the condenser and heat is rejected at constant pressure to the cooling medium. The temperature of the vapor drops to the saturation temperature, corresponding to the pressure in the condenser, and then the vapor condenses, thus returning to the previous condition.

The simple compression system described is usually referred to as a single-stage compression because the vapor is compressed from evaporator pressure to condenser pressure in one step. Such a system has a limited operating range usually set by the compressor design and the refrigerant used. The lower limit for single-stage compression is about 0 p.s.i.g. pressure in the evaporator, providing the compressor design will per mit the compression ratio'necessary to reach the condenser pressure. For applications exceeding the limitations of simple compression systems, multistage compression systems and cascade systems are used.

In themultistage compression system, the refrigerant vapor is compressed from evaporator pressure to condenser pressure in two or more steps.' The different steps of compression may be accomplished by means of individual compressors or a single compressor with several compressing stages. As the compression ratio increases, the discharge temperature and the superheat in the compressed vapor increase exponentially. Thus, when multistage compression is required, the vapor from the last stage discharges at a temperature too high for proper compressor performance. To overcome this, cooling of the vapor between stages is required. lnterstage cooling accomplishes, among other desirable effects, increased refrigerating effect in the evaporator, and reduced compression power.

The basic components of a two-stage cascade system are two indeperigerit circuits, one termed the lowtemperature or low stage and H16 other the hightemperature or high stage. In order to reduce the condenser pressure, and thus the compression ratio, of the low stage, refrigerant from the high stage is used to cool this condenser. The high-stage refrigerant then follows a simple compression cycle and is condensed in a water-cooled high-pressure condenser. It is readily seen that the evaporator of the high stage is the condenser of the low stage, whereas the evaporator of the low stage is producing the desired low-temperature refrigeration. In many cases the refrigerants used in the two stages are not the same, but are selected to give the best operating conditions.

The refrigeration-system compressor is a gas pump that transfers the refrigerant vapor from the lowpressure region to the high-pressure region through the expenditure of mechanical energy. The compressor must have sufficient capacity to remove from the evaporator all the vapor formed in producing the desired refrigeration effect and to compress that vapor sufficiently to permit subsequent condensation when heat is removed. There are three general classes of compressors used in refrigeration practice: reciprocating, rotary, and centrifugal.

The reciprocating compressor is a piston-type pump and take simany variations in form. It may have one or more p istons set in various arrangements and may be driven by either a hermetically sealed electric motor or an externally connected prime mover. There are other variations in types of valves, valve arrangement, cylinder cooling methods, and capacity controls. Reciprocating compressors operate at 250-l,750 rpm. and at maximum piston speeds of 750 feet per minute. The choice of type of compressor is based upon requirements for adaptability to variable load conditions, economy of floor space, power requirements, working life, and safety.

In a rotary compressor, the rotor, carrying several vanes or blades, is mounted eccentrically within the water-cooled cylinder. In operation centrifugal forces hold the blades tightly against the cylinder wall, forming a number of cavities which first increase and then decrease in size as they pass from the suction port to the discharge port. The lowpressure vapor is drawn into a cavity as it increases in size and then is compressed as the cavity decreases. The rotary compressor, like the reciprocating compressor, is of the positive displacement type. Because it is a high-volume machine, it has smaller dimensions than a comparable reciprocating compressor. In addition, the rotary machine is free of pulsations and vibrations, does not require valves, and can be directly connected to a motor. The rotary compressor is used chiefly in multistage compression where the pressure differential does not exceed 30 p.s.i. and the maximum discharge pressure is 20 p.s.i.g.

The centrifugal compressor is a high-speed machine wit h on eeor r r 1 ore impellers keyed to a driven shaft and enclosed in a suitable housing. The impellers, which resemble the closed impellers of a centrifugal pump,

rotate at 2,800-9,000 r.p.m., depending upon their diameters. The number, diameter, and speed of the impellers are based upon the compression ratio and the density of the refrigerant vapor. When more than one stage, or impeller, is required thehigh-velocityvapor is conducted through adiffuserbr volute, where its ve locity is reduced with corresponding increase in pressure, and thence through a channel and guide vanes to the next impeller. The centrifugal compressor is not a positive displacement machine but, instead, develops a fairly constant head with a wide variation in quantity of vapor handled. It has a number of advantages, including low weight-capacity ratio, minimum oil contamination, and absence of vibration and pulsations. It is ideally adaptable to variable load applications.

In servicing the compressors hereinbefore described, a pressure guage is needed on the high and low cycles of the compressor. However, presently available pressure gauges deal mostly with a static situation and not with a changing situation. Typical of such gauges are those found in the A. L. Bradley U. S. Pat. No. 1,402,139, the A. Watters U. S. Pat. No. 1,716,399, the J. Wahl U. S. Pat. No. 1,866,140, The .l.C. Crowley U. S. Pat. No. 1,923,776, the J. C. Crowley U. S. Pat. No. 1.930,039 and the S. T. Williams U. S. Pat. No. 2,049,532. In all of these patents there is an elongated casing usually, and a window, a calibrated indicator inside the casing, a sensing means connected to the indicator which will sense pressure, and a return spring. These gauges work fine as bicycle and automobile tire gauges, but have little practical use as refrigerator gages.

SUMMARY OF THE INVENTION Briefly stated, the present invention contemplates a pocket instrument useful in a refrigerator compressor system. This instrument measures the pressure on the high and low sides or stages of the compressor by using the service valve located on the compressor. Generally speaking, the instrument has an elongated chamber, a reciprocating plunger in the chamber with an indicator with a lower end having a rod connected to said lower end. The rod in turn has a connecting boss at the lower end. In the chamber there is a reciprocating piston with an upper socket for receiving said boss when the boss is pushed by hand into the socket. Spring means urge the piston downwards and connecting means connect the compressor to the said service valve so that when the boss engages the socket, changes in pressure are indicated on the indicator, and when said boss is not so engaged, the highest pressure will be indicated on the indicator.

The invention as well as other objects and advantages thereof will become more apparent from the following detailed description when taken together with the accompanying drawing, in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal vertical view, partly in section of the gauge contemplated herein; and

FIG. 2 is an enlarged cross-sectional view of a portion of the gauge shown in FIG. 1.

Shown in the drawing is a portion of a compressor 8,

valve head 11 will move off its seat permitting gas in the compressor to escape. Shown above the valve is a gauge 12 with a pocket clip 12a and with an elongated housing chamber 13 in which there is a plunger between the piston 22 and a spring stop 25 just below the indicator. To prevent an air cushion in the gauge there is a vent 26. Also, to absorb any shock in the system there is a snubber orifice 27 in the piston. Piston 14. At the top of the plunger 14 is an indicator 15, one 5 holds a piston rod 28 which terminates in a valve deside of which can be of one color, e.g., green and calipression 29. The valve depression 29 is surrounded by brated for the particular refrigerant, e.g., Freon F22 in a concave rubber seal 30 and the gauge also includes a pressure-temperature scale which the other side can a lower knurled service nut to attach to the compressor be colored white and calibrated for another refrigerant, service valve 10. e.g., Freon FlZQAlso, prepared scales may be inserted 10 It will be observed therefore that according to the in lieu of fixed scales for the particular refrigerants inventive concept, pocket gauge 12 is connected to one listed in Table I and Table ll. of the service valves employed on the high and low 'g sides of refrigeration compressors and the plunger 14 registers the pressure developed by the compressor. common Others Others 15 The plunger has a rod 16 having an enlarged end boss Ammonia Carbon tetrachloride Dimethyl ether. 18 adapted to fit into amd be Seclfred in a 50cket 20 Carbon dioxide Dichloroethylene..... Ethyl bromide. when pushed by hand so that the piston 22 is clamped Dichlorodifluoro- Ethane Ethyl ether. to the rod 1 w it is clamped and Connected up to methane (Freonl2). 1.2-Dichloro-l.l,2.2- Ethylamine Hexane. the refrigerator cycle the plston 22 W1 use the y tetrafluoroethane 20 inder 21 and carry with it the spring 23 and plunger 14. 1 The plunger 14 slides through the washer 17 which is Dtchloromonofluoro- Ethylene Methane.

methane (Freon-21). anchored in the cylinder 21, compressmg the spring 23 metnylenlel Cl'lLOfide Fthlyl chloride gentalze. proportionately to pressure in the system when th ct y c ori e so utane ropy ene. Monochlorodifluoro- Methylamine Trichloromethane. pressure m the System drops the PE 23 fo rces the methane (Freon-22). 25 rod16 and the piston 22 downwardly 1n thecyhnder 21 Sulfur dioxide Methyl formate Mgnochloratlrr so that the plunger records the pressure existing in the gggf f system, and it will thus indicate changes in the pres- Trichloromonofluoro' Propane Tetrafluoromethane sure.

l (Freonm' When the rod 16 is disconnected from the socket 20 l.l.2-Tnch1oro-l.2.2- Water 22- 2.--. .w. -2. 2

u-ifl th and p1ston 22 the operation wtlTbe as prevlously de- (Freon-113). scribed as pressure increases. When the pressure drops TABLE 11.-CHARAcrtafisfics oFiiiiioiililfiis' At 5F. evaporator temp. and 86F. condenser temp.

Weight circulated Displace- Heat of Refrigper ton of ment per ton Pressure. p.s.i.a. vaporizacrating refrigof refrigtion at 5F. effect eration, eration. Cycle Refrigerant A1 5F At 86F b.t.u./lb. b.t.u./lb. |b.lmin. cu. ft./min. hp./ton

Ammonia .1 34.27 169.2 565.0 474.5 0.422 3.44 0.15.91 Carbon dioxide... 331.95 1043.0 117.6 55.50 3.528 0.943 1.843 Freon-ll 2.93 18.28 84.0 67.54 2.961 36.33 (1.935 Freon-l2 26.51 107.90 69.5 51.07 3.916 5.82 0.997 Freon-21.. 42.02 174.5 109.34 89.41 2.237 20.43 0.926 Freon-22..... 43.02 174.5 93.59 69.28 2.886 3.687 1.054 Freon-1 l3 0.98 7.86 70.62 53.67 3.672 100.75 1.002 Freon-114......... 6.77 36.69 61.98 43.58 4.589 19.37 Methyl chloride 21.15 94.70 180.71 150.3 1.345 v6.09 0.963 Methylene chloride.... 4.9 85.3 162.1 134.1 1.492 74.45 0.965 Sulfur dioxide 11.81 66.45 169.4 141.4 1.414 9.08 0.995

Ideal cycle 0.822.

Attached to the bottom 6f indicator 15 13 61 115116. Separating the rod and indicator is a washer 17. The outer end of the rod 15 terminates in an enlarged end or boss 18. This boss 18 is fitted to enter an aperture 19 of a socket 20 made of resilient material so that the boss can readily enter the socket and be easily withdrawn therefrom. This portion of the housing 13 takes the form of a cylinder 21 and there is a cup seal piston 22. The cup open end faces downwards and the upper end of the cup seal piston supports socket 20.

Thus, when the boss is pushed into the socket; the movement of rod 16, which may be threaded, will move the piston 22 up and down in cylinder 21. Disposed around rod 16 is a spring 23 which is calibrated by means of a-calibration nut 24. This spring extends the spring 2 3 which seats on the piston 22 will force the piston downwardly in the cylinder 21 leaving the rod 16 and plunger 14 in the elevated position to record the highest pressure attained in the system.

1 claim:

11. In a refrigerator compressor system, an instrument to measure the pressure on the high and low sides or stages of the compressor (8) through service valve means (10) located on the compressor, in combination:

a. an elongated chamber (13);

b. a reciprocating plunger (14) in said chamber with an indicator plunger with a lower end (15) having a rod (16) connected to said lower end of said indicator plunger, said rod having a boss (18) at the lower end;

c. a reciprocating piston (22) in said chamber with an upper socket (20) with an aperture 19) for detachably receiving said boss (18);

d. spring means (23) between the indicator plunger and said piston for urging said piston downwards; and,

e. means (28, 29) for connecting said compressor to said service valve means, whereby when said boss is engaged in said socket, changes in pressure are indicated on said indicator plunger, and whensaid boss is not so engaged, the highest pressure will be indicated by the position of the detachable indicator plunger.

2. An instrument as claimed in claim 1, said spring means (23) includes calibration means (24) coacting with said rod between said lower indicator plunger and said piston.

3. An instrument as claimed in claim 2, said piston being a cup seal piston with the cup facing downwards, said socket being on the upper part of said piston.

4. An instrument as claimed in claim 3, said spring means including a spring stop below said indicator.

5. An instunnent as claimed in claim 3, said piston including a lower piston rod (28), a seal (30) at the end of said lower piston rod and a valve depression (29) for engaging said compressor valve means.

Claims (5)

1. In a refrigerator compressor system, an instrument to measure the pressure on the high and low sides or stages of the compressor (8) through service valve means (10) located on the compressor, in combination: a. an elongated chamber (13); b. a reciprocating plunger (14) in said chamber with an indicator plunger with a lower end (15) having a rod (16) connected to said lower end of said indicator plunger, said rod having a boss (18) at the lower end; c. a reciprocating piston (22) in said chamber with an upper socket (20) with an aperture (19) for detachably receiving said boss (18); d. spring means (23) between the indicator plunger and said piston for urging said piston downwards; and, e. means (28, 29) for connecting said compressor to said service valve means, whereby when said boss is engaged in said socket, changes in pressure are indicated on said indicator plunger, and when said boss is not so engaged, the highest pressure will be indicated by the position of the detachable indicator plunger.

2. An instrument as claimed in claim 1, said spring means (23) includes calibration means (24) coacting with said rod between said lower indicator plunger and said piston.

3. An instrument as claimed in claim 2, said piston being a cup seal piston with the cup facing downwards, said socket being on the upper part of said piston.

4. An instrument as claimed in claim 3, Said spring means including a spring stop below said indicator.

5. An insturment as claimed in claim 3, said piston including a lower piston rod (28), a seal (30) at the end of said lower piston rod and a valve depression (29) for engaging said compressor valve means.

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