US1793019A

US1793019A - Expansion valve for refrigerating systems

Info

Publication number: US1793019A
Application number: US307630A
Authority: US
Inventors: Albert F Sawyer
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-09-22
Filing date: 1928-09-22
Publication date: 1931-02-17
Anticipated expiration: 1948-02-17

Description

1931- A. F. S AWYER' EXPANSION VALVE FOR REFRIGERATING SYSTEMS Filed Sept. 22. 192B Patented Feb. 17, 1931 UNITED STATES.

PATENT OFFICE ALBERT F. SAWYER, OF HAVERI- IILL, MASSACHUSETTS, ASSIGNOR TO IRVING L. .KEITH, F I-IAVERHILL, MASSACHUSETTS EXPANSION VALVEFOR REFRIGERATING SYSTEMS Application fi1ed Septemher 22, 1928. Serial No. 307,630.

This invention relates to expansion valves of the type of which are employed in closed circuit expander, compressor, condenser refrigerating systems, to control the supply of refrigerant to the expansion coil or chamher, and more ymrticularly, .to a'pressure controlled type of valve which opens when the pressure, in the expansion chamber, .or the back pressure is reduced to a predetermined point and closes again when the back pressure-is raised to another predetermined point.

In devices of this type it is customary to V operate theneedle valve, which directly controls the passage through which thewrefrigerant passes to the expansion chamber,by vmeans of a diaphragm which is open to the low pressure of the system at its inner side and is subject to atmospheric pressure at its outer side, this action, usually being supple- ZOinentedby a spring, the action of which is usually partly neutralized by a spring of lighter weight located within the casmg, and

the arrangement being such that when the pressure in the expansion chamber is reduced to such an extent that the combined action of this pressure and of the light weight spring is over balanced by the atmospheric pressure and the action of the heavier spring, the needle valve will be opened to permit. the .dischargeof refrigerant from the hlgh pressure side to the low pressure side of the system.

.In practice the means for causing the needle valve to be opened sometimes fail to act, so that a dangerously high pressure 1s likelyto be built up in such case. .Thls failvure ofthe needle valve to open is frequently due to an accumulation of frost, or ice on the diaphragm, so that it becomesinflexible, or on coils of the outer spring for actuating the diaphragm, so that it is prevented fromacting to force the latter inward, and this 1s likely to occur eventhough the diaphragm andspring are encased to preventaccess of air thereto, the movement of the diaphragm tending to cause air to be drawn 1n to and out of the chamber in which it is encased.

The object of my invention is to provide a simpleand compact form of valve device of the type above referred to, in which the arfor engagement with the inner side of the rangement is such that, when the supply side of the systemis raised to a predetermined polnt above the normal high pressure,but is still well below a pressure which would be system and a port 3, adapted to be connected to the high pressure side thereof. A needle jvalve 4: is provided in the casing and arranged to seat in the port 3 against the pressure of the high pressure side. The stem 5 of said valve is provided with a central 10ngitudinal bore or chamber 6, which extends from the opposite end thereof for approx- ?5 imately half its length, and a circular flange 7 is formed integrally with said stem and has an annular rib 8 on its inner side. A flexible diaphragm 9 is clampedto the open end of the casing by means of a cap 10 and screws 11. A coiled spring 12 is arranged within the cap 10 in engagement at its inner end with the outer side of the diaphragm and an adjusting screw13 is threaded in the cap and in engagement with the outer end of said spring. -An actuating stem 14 is disposed in aXial'alignm-ent with the valve'stem 5 and is telescopically arranged in the chamher 6 thereof, with its outer end in position diaphragm 9. A spring 15 is interposed'between the inner end of the stem 14 and the bottom of chamber 6. A pair of levers 17 are extended in opposite relation thru apertures 18 in the side of the chamber 6 of the valve stem and the inner ends thereof are disposed 1n an annular groove formed in stem 14, the outer ends thereof being arranged to engage the rib 8 0n flange 7, and

the middle portions thereof being fulcrumed on an annular rib 19 on the casing l.

lVith the above described construction, when the pressure against the inner side of the diaphragm 9 is sutlicient to overcome the combined action of atmospheric pressure and of spring 12 on its outer side, the spring 15 will act to hold the valve 4 closed, as shown. in Fig. 1. This position of the parts may be considered as the normal position. When the pressure within the casing is reduced to a iiredetermined point, so that the inward pressure over balances the ouward pressure on the diaphragm, it will be sprung inward, forcing the stem 14 inward and causing lovers 1? to be swung so as to be forced against the flange 7 and open the valve d against the action of spring 15, this action ted by the fluid pressure which is being built up against the valve in the high pressure sine of the system, or in port 3. This condition will continue until the circulating ounip stops and, the pressure in the valve casing rises sulliciently to ovcrl'ialance the inward pressure on the diaphragm and i rmit the spring 15 to close the valve.

iassuming however, that the outer spring ihould become ineffective for any reason, as by having its coils become frozen together, or by having the diaphragm so stiffened by ice as to become inflexible, it will be apparent that when the pressure within the casing is reduced, the diaphragm will not be forced inward and in consequence, the valve 4 will not be lifted from its seat thereby. The tens on of spring 15 is however such that when the pressure in port 3 rises to a substantial extent above that atwhich the valve would normally be opened by the inward force on the diaphragm, this pressure, acting against he valve l, will overcome the action of pring 15 and cause valve l to be unseated, .0 that the refrigerant will pass from the ii gh pressure to the low pressure side of the system, the pressure in the high pressure side thus being prevented from rising above a predetermined point. The danger of having excessive or unsafe pressures built up in system from failure of the diaphragm to be moved inward is thus avoided. The construction also is advantageous over a construction in which the pressure in the high ressure side tends to hold the valve against its seat, which arrangement has been commonly employed, as the higher the point to which the pressure rises the more diffcult it becomes to unseat the valve. On the contrary with the above described construction, the higher the point to which this pressure rises the more easily the valve is opened, so that in case the valve should tend to stick or become frozen to its seat, the pressure against he valve will ordinarily act to open it, when it otherwise would not be opened automatically. In warm weather there is also conside able tendency for the pressure in the high pressure side of the system to run substantially higher than in cool Wcaher, and this increased pressure tends to cause the valve 1 to be opened earlier and close later with the above described construction, than would be the case if the pressure tended to hold the valve to its seat, and thus tended to restrict circulation when maximum circulation was desirable.

The above described construction is very compact, and may be housed in an ordinary cylindrical casing of practically the same form as the construction which has usually been employed for this purpose.

t is also simple and but slightly more expensive to manufacture than such prior construction.

I claim:

1. An expansion valve comprising a casing having an inlet port and an outlet port respectively adapted for connection to the high pressure side and to the low pressure side of a closed circuit refrigeration system, a valve stem reciprocally movable within the casing and having a valve at one end, to be n'ioved against the pressure supplied to said inlet port to close the same, a spring adapted and arranged to engage said stem and hold said valve closed against the normal fluid pressure supplied to said inlet port and to yield to permit the valve to be opened by an abnormal pressure supplied thereto, a pressure controlled device on said casing arranged to be moved outwardly to an inoperative position by the pressure within the casing when raised to a predetermined point and to be moved inwardly from said position when said pressure is reduced below said point, and engaging means between said device and said stem arranged to move said stem to open said inlet port when said device is moved inwardly.

2. An expansion valve comprising a casing" having an inlet port and an outlet port respectively adapted for connection to the high pressure side and to the low pressure side of a closed circuit refrigeration s stem, a valve having a. stem disposed within the casing and longitudinally movable in one direction to close said inlet port against the pressure of the fluid supplied thereto and oppositely movable by said pressure to an open position, a spring arranged to engage said stem and to hold said valve in closed position against a normal pressure supplied to said inlet port and to yield to permit the valve to be forced open by an abnormal pressure supplied thereto, a pressure controlled diaphragm closing one side of the casing and outwardly movable by the pressure within the casing, and normally actuated to move inwardly when the pressure is reduced to a predetermined point, and a lever fulcrumed Within the casing at its middle portion and arranged to be engaged at one end by said diaphragm and at its opposite with said projection, to move said valve stem end with said stem, to move the stem to open to open its valve on inward movement of the the valve when the diaphragm is moved indiaphragm.

wardly.

In testimony whereof, I have signed my 3. An expansion valve comprising a casing name to this specification.

having an inlet port and an outlet port respectively adapted for connection to the high pressure side and to the low pressure side of a closed circuit refrigeration system, a valve stem disposed within the casing and having a valve at one end, said stem being longitudinally movable in one direction to close said inlet port against the pressure of the fluid supplied thereto and oppositely movable by said pressure to an open position, a spring arranged to engage said stem and to hold said valve in closed position against a normal pressure in said inlet port and to yield to permit the valve to be forced open by an abnormal pressure therein, a pressure controlled diaphragm arranged to close one side of the easing and to be moved outwardly by the pressure within the casing, means for movingsaid diaphragm inwardly when the pressure within the casing is reduced'to a predetermined point, an actuating stem disposed within the casing in ali nment with said valve stem and arranged tobe moved by said diaphragm to wards said valve when the diaphragm is moved inwardly, and a lever arm arranged to be engaged at one end by said actuating stem and to engage said valve stem at its opposite end to move the valve stem in a direction to open the valve.

4:. An expansion valve comprising a casing having an'inlet port and an outlet port respectively adapted for connection to the high pres sure side and to the low pressure side of a closed circuit refrigeration system, a valve stem disposed within the casing and havin a valve at one end, said stem being longitu inally movable in one direction to close said inlet port against the pressure of the fluid supplied thereto and oppositely movable by said pressure to an open position, a spring arranged to engage said stem and to hold said valve in closed position against a normal pressure in said inlet portand to yield to permit the valve to be forced open by an abnormal pressure therein, a pressure controlled diaphragm arranged to close one side of the casing and to be moved outwardly by the pressure within the casing, means for moving said diaphragm inwardly when the pressure I within the casing is reduced to a predetermined point, an actuating stem aligned'with said valve stem and telescopically arranged at its inner end with the opposite portion of the valve stem from its valve with its outer end arranged for arrangement with the inner said actuating stem and at its opposite end ALBERT F. SAWYER.