US2755025A

US2755025A - Refrigeration expansion valve apparatus

Info

Publication number: US2755025A
Application number: US283011A
Authority: US
Inventors: Chalmers B Boles
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1952-04-18
Filing date: 1952-04-18
Publication date: 1956-07-17
Anticipated expiration: 1973-07-17

Description

July 17, 1956 c. B. BoLEs REFRIGERATION EXPANSIN VALVE APPARATUS Filed April 18, 1952 INVENTOR.

Chalmers B. Boles BY/ZH/Lamwv WZ@ United States Patent O REFRIGERATION EXPANSION VALVE APPARATUS Chalmers B. Boles, Dayton, Ohio, assigner to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application April 18, 1952, Serial No. 283,011

8 Claims. (Cl. 236-92) This invention relates to refrigerating apparatus and more particularly to expansion valves with a limiting device for preventing excessive loads.

Recently there has been introduced on the market thermostatic expansion valves with pressure limiting devices which collapse to assist the closing of the valve when a predetermined pressure is attained in the valve outlet.

lt is an object of my invention to provide a thermostatic expansion valve with a limiting device which expands instead of collapses to directly close the valve.

lt is another object of my invention to provide a thermostatie expansion valve with a small unitary readily replaceable limiting device located a chamber of the Valve which is readily opened.

These objects are attained by providing a thermostatic expansion valve in which the valve element is carried directly by a sealed capsule located in the valve outlet chamber. During normal operation of the Valve the valve element is carried in retracted position and the capsule is bodily moved by the usual combined temperature and pressure responsive element of the valve as if no limiting device were included. This results in a normal refrigerant ow from the condenser to the evaporator. When the temperature and pressure is reached in the valve outlet chamber at which it is desired to limit the flow through the valve, the sealed capsule expands to move the Valve element into or towards engagement with its seat to close or limit the ilow through the valve.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Figure l is a vertical sectional view through an expansion valve embodying one form of my invention;

Figure 2 is an enlarged sectional view of the pressure limiting capsule and fragments of adjacent parts; and

Figure 3 is a fragmentary enlarged section of the thermostatic chamber and diaphragm.

Referring now to the drawings and more particularly to Figure l there is shown a valve body having an inlet 22 provided with a are connection for connection with a refrigerant condenser. The valve body 2t) is also provided with an outlet 24 provided with a flare connection for connection with a refrigerant evaporator. The inlet 22 connects with an inlet passage provided with a conical straining screen 26 which leads to a vertical passage provided along the axis of the valve body 20. This vertical passage connects directly with a valve seat insert 27 which is threaded into the lower end of the vertical passage and is provided with a valve seat at the outlet of the passage. The passage discharges directly into a valve chamber 28 within the valve body 20. This valve chamber 28 has a side outlet connecting with the are connection 24 which in turn connects to the refrigerant evaporator.

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At the top of the valve body 20 there is provided a diaphragm 30. The outer rim of the diaphragm 30 is held in place by the downwardly turned flange of a cap member 32 secured in place by a bent over upwardly facing flange 34 provided at the top of the valve body 20. The top of this cap member 32 is connected by a capillary tube 36 with a thermostat bulb 38. The cap 32, the capillary tube 36 and the bulb 38 may be charged with a thermostatic liquid or a volatile liquid or vapor, but preferably the bulb 38 is provided with a charge of activated charcoal and it together with the capillary tube 36 and the cap member 32 are provided with a charge of a permanent gas such as carbon dioxide which is adsorbed and evolved from the activated charcoal in the bulb 38 according to the temperature of the bulb 38. According to present refrigeration practices it is customary to clamp the bulb 33 in thermal exchange relationship with the outlet portion or suction conduit of the refrigerant evaporator. When the evaporator outlet temperature is high as prevails when the system is shutdown for a considerable length of time the diaphragm 30 will be depressed by the pressure of the gas or vapor in the cap 32. This would cause an ordinary expansion valve to be held wide open to provide an abnormally high pressure in the evaporator to impose an abnormally heavy load upon the compressor.

eneath the diaphragm 30, there is a metal diaphragm pad 46 which rests upon three pins each designated by the reference character 42. These pins 42 extend into the chamber 23 and their lower ends engage the upwardly facing recessed surface of a valve supporting means 44 located within the chamber 28. The valve supporting means 44 is provided with a flexible diaphragm 46. The outer portion of this diaphragm 46 is held by an upwardly facing ange 48 of an insert 50 provided in the bottom of the valve supporting member 44. The flange 48 holds the outer portion of the diaphragm 46 in contact with a. shoulder in a diaphragm chamber within the central portion of the valve supporting means 44. The diaphragm 46 and the member 50 are sealed to the valve supporting means 44 by a downwardly extending rim 52 upon the valve supporting means 44 which is rolled inwardly to accomplish the sealing. This sealing may be made doubly sure by the use of solder.

Mounted upon the upper face of the diaphragm 46 is a anged valve element 54 which protrudes through a centrally located aperture in the top of the diaphragm chamber in the valve supporting means 44. The uppermost portion of the valve element 54 is provided with a ball 56 which engages the valve seat insert 27 to close the inlet passage in the valve body 20. Under normal conditions, the valve element S4 and the ball 56 will be held in retracted position within the valve supporting means 44 with the central portion of the diaphragm 46 resting upon a centrally located stop pad 58 upon the bottom of the diaphragm chamber. According to my invention the chamber formed beneath the diaphragm 46 is sealed. It is subject to the pressure of the refrigerant in the valve chamber 28 which has access to the upper surface of the diaphragm 46 through the opening in the top of the valve supporting means through which projects the top of the valve element 54. This pressure tends to keep the valve element retracted within the valve supporting means 44 with the diaphragm 46 in engagement with the stop pad 58.

To provide my valve with a pressure limiting feature, the chamber beneath the diaphragm 46 is charged with a temperature responsive expansible medium having a steeper pressure-temperature curve than the refrigerant controlled by the valve. Preferably this chamber is charged with the vapor of a volatile liquid having a steeper pressure-temperature curve than the refrigerant being used. This chamber is charged through a charging tube 59 and is then sealed when the proper amount of charge is applied. if desircd'the chamber beneath the diaphragm 46 canbe charged with an absorbentV such as activated charcoal and a permanent' gas such as carbon dioxide. If the pressure of the selectedV volatile liquid placed in the chamber beneath the diaphragm 46 is appreciably higher than the pressure of the refrigerant which passes through the chamber 28 at which it is desired to limit thetlow through the valve, there is provided a spring 60 having its upper outer portion bearing against the valve supporting means and having its lower inner portion bearing against the topY of the flange on the valve element 54. This spring 60` may be of any suitable shape but preferably is in the form of a dished ring which may have inwardly extending fingers resting upon the top ofthe flange of the valve element 54. With such anarr'angement,4 when the pressure and temperature is reached in the outlet chamber 28 at which the limiting action is desired, the pressure beneath the diaphragm will be great enough to move the valve member toward or into engagement with the valve seat insert 27.

As specic examples of the invention, it will be assumed that in two different applications it is desired to reduce the flow through the valve to a minimum when the refrigerant within the chamber 28 rises to temperatures of F. and 38 F. These limiting temperatures would be suitable for frozen food systems and beveragecooling systems respectively. Diiluorodichloromethane (F-12) and methyl chloride (CHaCl) have been selected as examples of refrigerants which are suitable for use in the refrigerating system. The following refrigerants are selected as examples of the vapors which may be used in the diaphragm chamber of the valve supporting means 44 since in the range of useful operating temperatures in which the valve operates they have steeper pressure-temperature curves than F-12 and methyl chloride:

Monochlorodiiluoromethane (F-22), ammonia, perfluoropropane (CsFa) (F-218) and pentauoromonochloroethane (CzClFs) (F-l 15).

The following table indicates the pressures of these refrigerants and vapors at 10 F. and 38 F. as well as the differences `in the pressures between each of these vapors and each of the refrigerants:

Table of refrigerant pressures and differences In each case the pressure is higher than the pressures of the F-12 and methyl chloride. This difference in pressures must be counteracted and substantially exactly equaled by the spring force of the diaphragm 46 and the spring 60. For a frozen food installation requiring a valve with a limiting action effective at about 10 F., with F-12 as the refrigerant if the effective area of the diaphragm 46 is about .11 sq. in. then a spring force of about 2 pounds would be required with F-22, while spring forces of one pound would be required for ammonia; 1.35 pounds would be required for F-218 and 1.4 pounds would be required for F-115. This spring force would be the force of the spring 60 and the diaphragm 46 in a position near the uppermost position.

With any of these examples, as long as the temperature within the valve chamber is an adequate amount below 10 F., there will be no limiting action because below about 10 F. the pressure of the refrigerant upon the diaphragm 46 plus the spring force of the spring 60 and the diaphragm 46 is always greater than the pressure of the vapor within the diaphragm chamber in the valve supporting means 44 so that the diaphragm 46 will be pushed down against the pad 58. This must be true since if the balanced condition is about 10 F. and the vapor has a steeper pressure-temperature curve than the refrigerant, the refrigerant and allied spring forces will be greater than the force of the vapor below 10 F. and less than the force of the vapor above 10 F. It follows from this that above 10 F., the vapor pressure within the diaphragm chamber in the valve supporting means 44 always will be greater than the opposing refrigerant pressure and the allied spring forces so that the diaphragm 46 will be forced upwardly to move the ball 56 toward or into engagement with the valve seat in thc insert 27.

As another example, assume for a beverage cooler installation it is desired to set the valve so that its maximum limiting action would be reached at 38 F. The pressures of these different vapors at 38 F. are indicated in the table as wel] as the difference in pressure between these particular vapors and F-12 at 38 F. Again we assume that the diaphragm 46 has an effective area of .ll sq. in. A downward spring force of the diaphragm 46 and the spring 60 would be required. For F-22 this force would be 3.4 pounds, for ammonia 2.3 pounds, for F-Zl 8 2.25 pounds and F-1l5 2.4 pounds. It appears that for these latter three one particular spring arrangement would be satisfactory and this could be set at about 2.3 pounds.

Instead of F-12 as the refrigerant in the system, methyl chloride could be used as shown in the table. Methyl chloride at 10 F. would have a pressure of 8.9 pounds and at 38 F. it would have a pressure of about 27 pounds. The difference in pressure between any one of the refrigerants in the capsule would be greater as illustrated by the ditferenec in pressure noted in the table. The spring force required at 10 F. would be 2.66 pounds for F42, 1.65 pounds for ammonia, 1.94 pounds for F-218 and 2.06 pounds for F-1l5. With methyl chloride at 38 F., a spring force of 4.33 pounds would be required for F-22, 3.17 pounds with ammonia, 3.18 pounds with F-218 and 3.35 pounds with F-115.

For other selected limiting temperatures different spring forces could be provided. These spring support assemblies could be made in sets for different refrigerants and different limiting temperatures and pressures. They would be interchangeable in the chamber 28. They could be readily removed and inserted from the chamber 28 by removing the threaded cap member 62 which is threaded into the open end portion of the chamber 28. This cap member 62 has a threaded adjusting screw 64 therein which engages a spring retainer 64 provided at the lower end of the valve closing spring 66. The upper end of this valve closing spring 66 rests against the bottom of the member 50 and holds the spring support assembly 44 in engagement with the three pins 42.

The chamber 28 may be connected by a passage 68 with the chamber beneath the diaphragm 30 which contains the pad 40. Otherwise the passages through which the pins 42 extend may be relied upon for this purpose. The chamber beneath the diaphragm 30 may also be connected to the outlet of the evaporator if desired. The screw 64 may be turned to adjust the tension ofthe spring 66 so as to adjust the pressure and temperature at which the valve normally opens. The lower end of the screw 64 is enclosed by a cap nut 70 to complete the sealing of the chamber 28.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. An expansion valve for controlling the flow of a refrigerant includinga valve body having an inlet and an outlet, a valve means for controlling the ow of refrigerant from'said inlet to said outlet, a flexible diaphragrnmeans' associated with said valve body and having'operative connecting means for moving said valve means to open position, means fordeflecting said diaphragm means to operate said valve means, said valve means including a second bodily movable sealed diaphragmfmeans and a valve member carried by and operated by said sealed diaphragm means, said sealed diaphragm means and said valve member constituting principal parts of and being bodily'movable with the valve means and said flexible diaphragm means, adjusting means associated with said Valve body, spring means extending between said adjusting means and said valve means, and a temperature responsive expansible medium within said sealed diaphragm means having a greater rise vin pressure for a corresponding rise in temperature than the refrigerant controlled by the valve, said valve member having a connection to said diaphragm means for movement toward valve closing position upon expansion of the second diaphragm means within the same range of operating temperatures.

2. An expansion valve for controlling the flow of a refrigerant including a valve body having an inlet and an outlet, a valve means for controlling the flow of refrigerant from said inlet to said outlet, a flexible diaphragm means associated with said valve body and having operative connecting means for moving said valve means to open position, means for dellecting said diaphragm means to operate said valve means, said valve means including a second bodily movable sealed diaphragm means and a valve member carried by and operated by said sealed diaphragm means, said sealed diaphragm means and said valve'member constituting principal parts of and being bodily movable with the valve means and said flexible diaphragm means, adjusting means associated with said valve body, spring means extending between said adjusting means and said valve means, and a temperature responsive expansible medium within said sealed diaphragm means having a greater rise in pressure for a corresponding rise in temperature than the refrigerant controlled by the valve within the same range of operating temperatures, said valve means also including spring means for biasing said second diaphragm means, said valve member having a connection to said diaphragm means for movement toward valve closing position upon expansion of the second diaphragm means.

3. An expansion valve for controlling the ow of a refrigerant including a valve body having an inlet and an outlet, a valve means for controlling the flow of refrigerant from said inlet to said outlet, a flexible diaphragm means associated with said valve body and having operative connecting means for moving said valve means to open position, means for deflecting said diaphragm means to Operate said valve means, said valve means including a second bodily movable sealed diaphragm means and a valve member carried by and operated by said sealed diaphragm means, said sealed diaphragm means and said valve member constituting principal parts of and being bodily movable with the valve means and said flexible diaphragm means, adjusting means associated with said valve body, spring means extending between said adjusting means and said valve means, and a temperature responsive expansible medium within said sealed diaphragm means having a greater rise in pressure for a corresponding rise in temperature than the refrigerant controlled by the valve within the same range of operating temperatures, said valve means also including a stop arrangement for limiting the movement of the valve member, said valve member having a connection to said diaphragm means for movement toward valve closing position upon expansion of the second diaphragm means.

4. A thermostatic expansion valve for controlling the ow of a refrigerant including a valve body having an inlet and an outlet and a chamber connected to the outlet, said body having a valve seat located between said chamber and said inlet, a thermostatic operating means located on one side of said valve seat, a valvev supporting'means located in said chamber on the opposite side of the valve seat from said thermostatic operating means,v a sealed diaphragm means located upon said supporting means, a valve member positively mounted on the face of said sealed diaphragm means nearest said valve seat for movement toward the valve seat upon expansion of the sealed diaphragm means, a movement transmitting means extending from said thermostatic means to said valve supporting means, said sealed diaphragm means being charged with a volatile liquid having a greater rise in pressure for a corresponding rise in temperature than the refrigerant within the same range of operating temperatures, said valve member having a connection to said diaphragm means for movement toward valve closing position upon expansion of the second diaphragm means for expanding said diaphragm means above a predetermined refrigerant temperature to reduce the amount of valve opening.

5. A thermostatic expansion valve for controlling the flow of a refrigerant including a valve body having an inlet and an outlet and a chamber connected to the outlet, said body having a valve seat located between said chamber and said inlet, a thermostatic operating means located on one side of said valve seat, a valve supporting means located in said chamber on the opposite side of the valve seat from said thermostatic operating means, a sealed diaphragm means located upon said supporting means, a valve member positively mounted on the face of said sealed diaphragm means nearest said valve seat for movement toward the valve seat upon expansion of the sealed diaphragm means, a movement transmitting means extending from said thermostatic means to said valve supporting means, said sealed diaphragm means being vcharged with a volatile liquid having a greater rise in pressure for a corresponding rise in temperature than the refrigerant within the same range of operating temperatures for expanding said diaphragm means above a predetermined refrigerant temperature to reduce the amount of valve opening, and adjustable spring means bearing upon said supporting means for opposing said thermostatic operating means.

6. A thermostatic expansion valve for controlling the flow of a refrigerant including a valve body having an inlet and an outlet and a chamber connected to the outlet, said body having a valve seat located between said chamber and said inlet, a valve supporting means located in said chamber adjacent said valve seat, a diaphragm located upon the side of the valve seat opposite said valve supporting means, said valve body having a shallow chamber adjacent said diaphragm, a cap member enclosing said diaphragm, said cap member and said diaphragm being sealed to said valve body around said shallow chamber, a thermostat bulb connected to said cap member, push pins extending from said shallow chamber through the valve body to said valve supporting means for moving the valve supporting means in accordance with the movement of the diaphragm, said valve supporting means being provided with a shallow chamber facing said valve seat, a second diaphragm covering said shallow chamber and having its edge portions sealed to said supporting means, a valve member positively supported upon the face of said second diaphragm nearest the valve seat for engagement with said valve seat, said shallow chamber in said supporting means being charged with a volatile liquid having a greater rise in pressure for a corresponding rise in temperature than the refrigerant within the same range of operating temperatures for expanding said second diaphragm toward said valve seat above a predetermined refrigerant temperature to reduce the opening of the valve.

7. A thermostatic expansion valve for controlling the ow of a refrigerant including a valve body having an inlet and an outlet and a chamber connected to the outlet, said body having a valve seat located between said chamber and said inlet, a valve supporting means located in said chamber adjacent said valve seat, a diaphragm located upon the side of the valve seat opposite said valve supporting means, saidk valve body havinga shallow chamber adjacent said diaphragm, a cap member enclosing said diaphragm, saidcapl member and said diaphragm being sealed to said valve body around said shallow chamber, a thermostat bulb connected to said cap member, push pins extending from said shallow chamber through the valve bodyito said valve supporting means for moving the valve supporting means in accordance with the movement of the diaphragm, said valve supporting means being provided with a shallow chamber facing said valve seat, a second diaphragm covering said shallow chamber and having its edge portions sealed to said supporting means, a valve member positively supported upon the face of said second diaphragm nearest the valve seat for engagement with said valve seat, said shallow chamber in said supporting means'being charged with a volatile liquid having a greaterv rise in pressure for a corresponding rise in temperature than the refrigerant within the same range of operating temperatures for expanding said second diaphragm toward said valve seat above a predetermined refrigerant temperature to reduce the opening of the valve, said supporting means being provided with a stop arrangement cooperating with said valve member to limit the movement of said valve member.

8; A thermostatic expansion valve for controlling the ow of a refrigerant including a valve body having an inlet and an outlet and a chamber connected to the outlet, said body having a valve seat located between said cham ber and said inlet, a valve supporting means located in said chamber adjacent said valve seat, a diaphragm located upon the side of the valve seat opposite said valve supporting means, said valve body having a shallow chamber adjacent said diaphragm, a cap, member enclosing said diaphragm, said cap member and said diaphragm being sealed to said valve body around said shallow cham' ber, a thermostat bulb connected to said cap member, push pins extending from said shallow chamber through the valve body to said valve supporting means for moving the valve supporting means in accordance withthe movement of the diaphragm, said valve supporting means being provided with a shallow chamber facing said valve seat, a second diaphragm covering said shallow chamber and having its edge portions sealed to said supporting means, a valve member positively supported upon the face of said second diaphragm nearest the valve seat for engagement with said valve seat, said shallow chamber in said supporting means being charged with a volatile liquid having a greater rise in pressure for a corresponding rise in temperature than the refrigerant within the same range of operating temperatures, `said valve member having a connection to said diaphragm means for movement toward valve closing position upon `expansion of second diaphragm means for expanding said second diaphragm toward said valve seat above a predetermined refrigerant temperature to reduce the opening of the valve, said supporting means being provided with spring means for biasing said second diaphragm.

References Cited in the file of this patent UNITED STATES PATENTS 2,505,933 Aughey et al May 2, 1950 2,506,413 Dube May 2, 1950 2,511,565 Carter June 13. 1950