US 3813893 A
Apparatus, in the form of a kit, for charging refrigeration systems utilizing a refrigeration system suction line wherein a thermostatically operated valve sensing suction line temperature controls the introduction of refrigerant into the refrigeration system. A restrictor is interposed between the thermostatic valve and the refrigeration system suction line controlling the rate of flow of the refrigerant supplied to a rate permitting the refrigerant supplied to the thermostatic valve to be in a liquefied state, and at a rate which prevents overcharging of the system. A manually operated shutoff valve, and pressure gauge, interposed between the refrigerant supply and the thermostatic valve permits determination of the condition of the system being charged. Insulative means mount the thermostatic valve temperature sensing bulb to the suction line to permit accurate suction line temperature sensing.
Description (OCR text may contain errors)
titted States Patent [191 Gemender et al.
[ REFRIGERATION SYSTEM CHARGING KIT  Inventors: John F. Gemender; Eric H.
Schwenker, both of Jackson, Mich.
 Assignee: Addison Products Company,
221 Filed: Oct. 30, 1972 211 Appl. No.: 301,893
2,547,070 4/1951 Hughey 62/224 2,512,090 6/1950 Cooper 62/292 3,208,232 9/1965 -Madis0n 62/292 3,303,663 2/1967 Miller 62/292 i 'MLLE-KW K-Meye ,Ber in, Attorney, Agent, or Firm-Beaman & Beaman;
[ June 4, 1974 [5 7 ABSTRACT Apparatus, in the form of a kit, for charging refrigeration systems utilizing a refrigeration system suction line wherein a thermostatically operated valve sensing suction line temperature controls the introduction of refrigerant into the refrigeration system. A restrictor is interposed between the thermostatic valve and the refrigeration system suction line controlling the rate of flow of the refrigerant supplied to a rate permitting the refrigerant supplied to the thermostatic valve to be in a liquefied state, and at a rate which prevents overcharging of the system. A manually operated shutoff valve, and pressure gauge, interposed between the refrigerant supply and the thermostatic valve permits determination of the condition of the system being charged. lnsulative means mount the thermostatic valve temperature sensing bulb to the suction line to permit accurate suction line temperature sensing.
6 Claims, 9 Drawing Figures PATENTEDJUN 41914 I 3.813893 COMPRESSOR AND CONDENSING UN T 1 REFRIGERATION SYSTEM CHARGING KIT BACKGROUND OF THE INVENTION The invention pertains to the field of refrigerant charging systems for refrigeration apparatus, and particularly pertains to charging systems which are controlled by sensing refrigeration system suction line superheat.
The amount of refrigerant within a refrigeration system employing a compressor, condenser, evaporator and capillary tube is important if optimum operating characteristics are to be achieved. In small refrigeration systems, such as used in refrigerators, window air conditioning units, ice makers, and other types of appliances wherein the refrigeration circuit is completely assembled at the location of manufacture, precision metering apparatus is available for accurately charging the system. However, with larger refrigeration systems, such as utilized for air conditioning, the refrigeration system is frequently installed component by component, and the refrigeration circuit is charged with refrigerant at the location of installation. This type of installation is widely used in domestic central air conditioning systems wherein an evaporator is located in the dwellings heating ductwork, usually on the furnace, and the condenser is exteriorly located.
In domestic-air conditioning systems, and in other types of systems requiring refrigeration apparatus assembled in situ, it is common to utilize precharged evaporators, condensers and conduits having fracturable seals which establish communication upon asembly of the conduits to the other components. However, as each installation will vary to the peculiarities of the site, size and length of the conduit, and sizes of compressors, condensers and evaporators, it is sometimes necessary to adjust the refrigerant charge in the circuit in order to produce optimum operating characteristics. Also, over a time period, it is not uncommon for refrigerant to be lost due to leakage, requiring recharging of the system.
Another circumstance that requires charging of a refrigeration system in the field arises when one of the major components, such as a compressor, requires replacement.
When domestic central air conditioning systems, and other large refrigeration systems, must be charged in the field, the most common means for determining the amount of refrigerant introduced into the system is to weigh the refrigerant supply cylinder before and after charging. Many service people do not have accurate scales, and bathroom scales and other inaccurate weighing devices, are often used for this purpose, re sulting in inaccurately charged refrigeration systems which do not funciton efficiently, and could contribute to component failure, such as the compressor. Further, in the case of a major component replacement, such as a condensing unit, many times the optimum weight of charge is not known.
A number of automatic recharging systems have been developed for refrigeration apparatus, and reference is made to US. Pat. Nos. 2,055,780 and 2,893,217. The expense of incorporating, as a permanent component of the refrigeration system, refrigerant supply means is excessive, and thus devices such as shown in these patents are not economically feasible for most installations.
Other efforts have been made to develop refrigeration charging systems which are superior to those presently available wherein the refrigerant is weighed, and reference is made to US. Pat. Nos. 3,303,663 and 3,400,552. These patents utilize compressor suction line temperature, or refrigerant pressure, to determine the amount of refrigerant within the system, and charging apparatus constructed in accord with these patents is capable of properly replenishing a refrigeration circuit. However, the apparatus illustrated in US. Pat. No. 3,400,552 is very expensive, and thus is not economically practical for most refrigeration servicemen. The more economically producible apparatus shown in US. Pat. No. 3,303,663 would be within the economic means of a greater number of service personnel, but the systems disclosed in thispatent have the disadvantage of possibly permitting overcharging of the system, and in such event, requiring the bleeding of the system resulting in a wasting of refrigerant. Furthermore, the apparatus shown in US. Pat. No. 3,303,663, when recharging at full capacity, will permit the refrigerant within the supply to become gaseous, significantly increasing the recharging time required, than if the refrigerant could be maintained in the liquid state. The servicemen often must heat maintain sufficient gas pressure in the refrigerant supply container to insure a flow of gaseous refrigerant from said container to the refrigeration or air conditioning system. The attendant handling and trouble involved substantially increases the time and cost of recharging.
SUMMARY OF THE INVENTION It is an object of the invention to provide a refrigeration charging system in the form of a kit which is economical to manufacture as to be readily available to all service personnel. Additionally, it is an object of the invention to provide a refrigeration charging kit which will accurately charge a refrigeration system with refrigerant without requiring the use of scales, yet will automatically permit the required amount of refrigerant to be charged for producing efficient operating characteristics.
The use of the charging kit in accord with the invention is easily within the skill of the average servicemen, and as the introduction of the refrigerant into the refrigeration circuit is automatic, and as the refrigerant is fed from the refrigerant supply in the liquid state, the time required for proper charging is substantially reduced as compared with previous charging systems and apparatus, and yet the likelihood of overcharging the refrigerant system is substantially eliminated.
In the practice of the invention a thermostatic valve is employed to control the flow of refrigerant from a pressurized refrigerant supply to the refrigeration system suction line. The thermostatic valve is controlled by a temperature sensing bulb attached to the suction line by insulated means wherein the temperature of the suction line can be accurately sensed independent of the ambient temperature conditions. The thermostatic valve includes an outlet communicating with a port defined in the suction line, and a restrictor in the form of an orifice is located between the suction line and valve outlet limiting the rate of charging, regardless of the amount of flow which might be capable of passing through the thermostatically controlled valve, when opened. The restrictor prevents overcharging of the system by limiting the flow of refrigerant into the refrig' eration circuit to a rate which permits timely sensing of the suction line superheat.
A manually operated flow control valve is located intermediate the refrigerant supply and the thermostatic valve, and a pressure gauge is located between the manually operated valve and the thermostatic valve. The completion of the charging process is determined by the proper interaction between opening and closing of the manually operated valve and the pressure gauge readings.
The bulb of the thermostatic valve is preferably attached to the refrigeration system suction line by a twopiece insulated housing utilizing resilient foam material of a high thermal insulation value. Thus, the housing permits the bulb to be quickly attached to the suction line in a mechanical manner which insulates the bulb from the ambient air temperature sufficiently to permit accurate regulation of the thermostatic valve by the bulb.
BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects and advantages of the invention will be appreciated from the following de scription and drawings wherein:
FIG. I is a plan view of a charging kit in accord with the invention,
FIG. 2 is a schematic view of the circuit connections made with the kit apparatus,
FIG. 3 is a schematic view of a complete refrigeration circuit illustrating the charging apparatus of the invention as connected thereto,
FIG. 4 is an elevational view of a thermostatic valve as utilized in the practice of the invention, the restrictor fitting being attached to the outlet thereof,
FIG. 5 is an elevational sectional view of the restrictor fitting used with the thermostatic valve of FIG. 4,
FIGS. 6 and 7 are inside views of the two portions of the bulb mounting housing,
FIG. 8 is an elevational, sectional view of the bulb mounting housing prior to assembly of the housing portions, the bulb, and suction line not being illustrated, and
FIG. 9 is an elevational, sectional view of the fully as sembled housing, bulb and suction line as taken along Section IXIX of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT The basic components of a refrigeration system, and the basic components of the charging kit, are best appreciated from FIG. 3. The charging kit of the invention is most advantageously used with capillary tube type refrigeration systems which include a compressor 10, a condenser 12, a capillary tube 14, interposed between the condenser and the evaporator 16, and a suction line 18 connects the evaporator with the compressor.
The charging kit includes a refrigerant supply cylinder 20, a manually operated shutoff valve 22, a pressure gauge 24 communicating with the conduit 25 between the valve 22 and the thermostatically controlled internally equalized valve 26. The thermostatic valve 26 is opened and closed in response to temperature sensed by a temperature sensing bulb 28 connected to the valve by a tube 30, as is well known. The outlet 32 of the thermostatic valve 26 is connected to the compressor suction line 18 by a conduit 34 and a conventional port or tee 36 mounted in the suction line, usually adjacent the compressor.
The refrigerant supply consists of a pressurized cylinder 20 of refrigerant, such as Freon, normally in a liquid form. The valve 22 is controlled by a handle 38, FIG. I, and the pressure gauge 24 may be of any conventional type having an operative reading range between the pressures normally utilized in refrigeration circuits.
Various type of thermostatic valves 26 can be used in the practice of the invention, and in the commercial embodiment a model FV-L valve manufactured by Sporlan Valve Company of St. Louis, M0., is utilized. The valve has a l5 F. superheat setting.
As the charging kit in accord with the invention is in tended as a standard item of equipment for refrigeration servicemen, the kit is preferably housed in a suitcase type case 40, FIG. 1, which may be readily transported. The kit housing includes a cover 42 and a bottom section 44 having a recess 46 in which are carried the rubber hose conduits 56 and 58 and the bulb attaching housing 48, as well as other service tools, such as wrenches and the like.
Approximately one half of section 44 is enclosed by a panel 50, and the pressure gauge 24 is mounted upon the enclosure panel, as are the threaded hose connections 52 and 54, and valve 26 is below the panel. The manually operative valve handle 38 also extends through the panel 50 for ready access by the operator. The panel 50 includes a recessed channel 51 disposed about its edge in which the bulb tube .30 is located, and the bulb 28 is retained in a clip 53 within the recess 46. The refrigerant supply cylinder 20 is carried separately from the kit case.
The mode of installation of the apparatus of the kit is illustrated in FIG. 2. One of the rubber, hoses 56 is employed to connect the Freon supply cylinder 20 to the fitting 52 which communicates with valve 22, while the other rubber hose 58 is utilized to connect the fitting 54, which communicates with the outlet of valve 26, to the compressor suction line port fitting 36. The bulb 28 is attached to the underside of the suction line 18, and maintained in position by the insulated housing 48 as described below.
The bulb mounting housing 48 consists of a pair of portions 60 and 62 formed of sheet material, such as metal, or synthetic plastic, which are of general transverse U-shaped cross sections as will be appreciated from FIGS. 8 and 9. The portion 60 includes lateral edges 64, and open ends 66, FIG. 6, while the portion 62 includes lateral edges 68, and open ends 70. The lateral edges 64 are flanged inwardly, while the lateral edges 68 are flanged outwardly. Internally, both portions 60 and 62 receive a thermal insulating material 72, such as synthetic foam, and the foam portions are recessed at 74 and 76 to help provide clearance for the suction line and temperature sensing bulb.
Once the bulb 28 is placed adjacent the underside of the suction line 18, the sidewalls 78 of the portion 62 are manually deformed inwardly so that the flanges 68 may be inserted between the flanges 64. Upon release of the sidewalls 78 the resilient nature of the sheet material of the portion 62, and the resistance to compression of the foam insulating material 72 therein, forces the sidewalls outwardly, and the flanged edges 68 into an overlapping and interlocking relationship with the flanged edges 64, FIG. 9. Thus, the housing 48 may be quickly employed to mechanically attach the bulb 28 to the suction line 18, and at the same time insulate the bulb from the ambient air temperature. The bulb is attached to the underside of the suction line in order to sense the temperature of any liquid that may be carried within the suction line.
Once the charging kit is connected to the refrigeration circuit, as shown in FIG. 2, the valve 22 is opened, and the refrigeration compressor is started, as is the evaporator air moving device, not shown. The temperature of the suction line 18 will be such as to open the thermostatic valve 26, and permit refrigerant to flow from the cylinder 20, through the valve 26, hose 58 and into the suction line through the port 36.
When the proper amount of refrigerant has been introduced into the refrigeration circuit the temperature of the suction line 18, as sensed by the bulb 28, will cause the thermostatic valve 26 to close, due to the predetermined operating conditions of the thermostatic valve, and the operator may then check to determine if the refrigeration system is actually fully charged.
Such a check is easily accomplished by watching the gauge 24 when the valve 22 is fully closed. if the gauge pressure should drop, charging is not complete, and the valve 22 is reopened and charging continues. if the gauge pressure does not drop when the valve 22 is closed, charging is completed, and the hose 58 is removed from the port 36, and the bulb 28 is removed from the suction line 18 by deforming the sidewalls 78 and disassemblying the housing portions 60 and 62.
The thermostatic valve 26 opens on demand for refrigerant, and closes when the refrigeration system is completely charged. While the thermostatic valve may, to a slight extent, throttle the flow of refrigerant through the valve, the flow of refrigerant through the valve, particularly during the initial stages of charging, is great enough to cause the liquefied refrigerant, within the cylinder to become gaseous, and in such a gaseous state the duration of charging the refrigeration circuit becomes excessively long. Usually, under such circumstances as occurring with known charging apparatus where the refrigerant has become gaseous, the serviceman will insert the cylinder in hot water to increase the temperature of the cylinder thereby increasing the gas pressure of the refrigerant supply.
Additionally, the flow of refrigerant through the refrigeration circuit is not at such a rate as to produce instantaneous temperature changes in the suction line proportional to the amount of refrigerant within the refrigeration circuit due to the volume of the refrigerant and restrictions in the circuit. Thus, if refrigerant is introduced into the refrigeration circuit too fast, it is possible to overcharge the system due to the lag inher-' valve 26 and the suction line 18 to control the maxi-,
mum flow rate of refrigerant that may be introduced into the suction line, regardless of the degree that the valve 26 may be open during charging. This restriction takes the form of an orifice defined in the restriction fitting 82 threadedly mounted upon the valve outlet 32, FIG. 4. The hose 58 communicates with the fitting 82, as the fitting is connected to connection 54. It has been discovered that an orifice of 0.043 inches prevents an excessive charging rate of the refrigeration circuit. Of course, an equivalent restriction could be achieved by lengthening the orifice and increasing the orifice diameter slightly, shortening the length of the orifice and reducing its diameter or using a capillary tube or similar restriction.
The use of the restricting orifice 80, while limiting the rate at which the refrigerant may enter the refrigeration circuit, actually decreases the time required for charging in that the liquefied state of the refrigerant supply is maintained during charging, and bleeding of the circuit, clue to overcharging is prevented.
The charging kit of the invention is particularly useful with capillary type refrigeration circuits where an internal refrigerant reservoir is not present. The charging system permits mismatched refrigerant circuit components such as evaporators, capillary tubes and condensers to be properly charged and the inaccuracies of charging that were previously very common may be eliminated by the system of the invention.
Of course, it will be appreciated that the bulb 28 may be attached to the suction line 18 by means other than the housing 48, for instance, the bulb may be taped to the suction line, and an insulating material wound about the bulb and suction line. The housing 48 provides a very quick'and effective means for attaching the bulb to the suction line, and the housing may be reused innumerable times without damage thereto.
Also, it will be appreciated that the restriction orifice 80 could be built into the valve 26, or otherwise incorporated into the hose and circuit between valve 26 and the suction line.
it will therefore be understood that the aforementioned advantages and objects are achieved by the invention, and various changes may be apparent to those skilled in the art which lie within the scope of the invention.
1. A charging system in combination with a refrigeration apparatushaving an evaporator, a condenser, and a compressor having a refrigerant suction line and a suction line port comprising, a thermostatic valve having an inlet, an outlet, and atemperature sensing bulb controlling said valve, a first passage for connecting said valve inlet with a refrigerant supply, a second passage connecting said outlet to the refrigerant suction line port, means attaching said bulb to the refrigerant suction line for sensing the temperature thereof, and a refrigerant flow restrictor means located within said second passage restricting the flow of refrigerant from said valve to said suction line to a rate preventing overcharging and permitting withdrawal of refrigerant from said supply while in a liquid state.
2. In a charging system as in claim 1, a manually operated shutoff valve located within said first passage controlling refrigerant flow to said thermostatic valve.
3. In a charging system as in claim 2, a pressure gauge communicating with said first passage intermediate said shutoff valve and said thermostatic valve.
inlet connectable to the supply of liquefied refrigerant, an outlet for communicating with the suction line port, and a suction line temperature sensing bulb controlling said valve for communicating with the suction line, and a refrigerant flow restrictor means mounted on said valve outlet restricting the flow of refrigerant from said valve to said suction line port to a rate preventing overcharging and permitting withdrawal of refrigerant from said supply while in a liquid state.