US2053290A - Refrigerating apparatus - Google Patents

Description

P 1936- D; KAUIFMANY 2,053,290

REFRIGERATING APPARATUS Filed Feb. 9, 1955 INVENTOR.

2M? h; a f M I ATTORNEYS Patented Sept. I 8, 1936 PATENT OFFICE REFRIGERATIN G APPARATUS Daniel I Kaufman, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation oi Delaware Application February 3 Claims.

This invention relates to refrigerating apparatus and more particularly to means for preventing high starting loads upon the refrigerant compressor.

When refrigerating systems are shut down the refrigerant pressure within the low pressure portion of the system becomes much higher than during normal operation because of the rise in temperature of the evaporating means and the environment of the evaporating means. This imposes a much greater loadthan even the normal starting load and the normal starting load is of course considerably greater than the normal running load. 'lhus, it will be realized that upon to starting a refrigerating system. which has been shut down for a considerable period of time, a very heavy load is placed upon the compressor and its driving motor. Attempts have been made to place throttling valves in the suction line oi I no refrigerating systems in order to tahe care oi this particular situation. However, unless such valves are made exceedingly large they throttle the gas during the entire running period or the compressoil and so cause the emclency of the system to so be reduced considerably. Also, the use of large valves requires a very large bellows for operating the valve since large valves usually require a rather large amount of force in order to move them to open position.

it is an object of my invention to provide a refrigerating system with a valve means for reducing the load on the compressor during the starting of the refrigerating system after a shut down which valve means requires only a small to actuating means and which will not appreciably throttle the flow of refrigerant during the normal running period of the compressor.

it is a further object of my invention to provide a refrigerating system with a compound valve in the suction line thereof having a comparatively small bellows responsive to the pressure in the inlet of the compressor for opening the valve when the pressure has been reduced Sit to a predetermined amount to prevent overload- 5 ing the compressor.

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

in the'drawing:

The figure-is a diagrammatic view of a refrigerating system including an enled section of my improved valve means.

5 Referring to the drawing, there is shown a 9, 1935, Serial No. 5,189

compressor 29 for compressing the refrigerant and for forwarding the compressed refrigerant to a condenser Hwhere the compressed refrigerant is liquefied and collected in the receiver 26. From the receiver 2 3 the liquid refrigerant is forwarded through a common supply conduit 26 and branch supply conduits 28, 3t and it to the air conditioning units M, as and W. Each of these air conditioners is provided with an expansion valve it which controls thesupply of liquid refrigerant to an evaporating means 42. The valve to is controlled by a thermostat as located in heat exchange relation with the outlet of the evaporator 32. From the air conditioning units the evaporated reirigerant is conducted by the individual supply conduits dt, it, and Eli to the common supply conduit is which connects to my improved throttle control valve til for controlling the flow of evaporated refrigerant through the return conduit til to the inlet of the compressor it. The compressor to is driven by an electric motor 6% under the control of a snap acting switch means it provided with a bellows responsive to the pressure within the return conduit 56. Each oi the air conditioning units are provided with a motor driven fan preferably oi the centrifugal type des ignated by the reference character t2 which draws in air from the room and circulates the air over the evaporator d2. Although the invention is shown as applied to a multiple air conditioning system, it should be understood that this invention is applicable also to single and multiple refrigerating systems for other'purposes.

Normally the pressure within the refrigerant evaporator, the return conduit and the inlet of the compressor is kept between predetermined limits. However, when the system is shut down for any reason whatever, especially in warm weather, the refrigerant pressure rises in these evaporators and in the return conduit and inlet of the compressor. The hotter the day and the hotter the environment temperature of. the evaporators and compressor, the higher the pressure is in the evaporators and the return conduit. It will thus be seen should the system be required to start on a very hot day after a shut down, there will be a tremendous load imposed upon the compressor which may be several times greater than the'normal load.

Prior to my invention, so far as I am aware, no one has been able to successfully provide a valve for throttling the suction line under such conditions which does not, have the disadvantage of either throttling the now of refrigerant during the running period orthe disadvantage of high pressure conditions but which permits the free flow of refrigerant under normal conditions.

This valve comprises a valve body Ill having a valve opening I2 provided with a valve seat 14. The valve opening connects to the inlet IQ of the valve on one side and to the outlet of. the valve 18 on the other side. Beneath the valve seat there is provided a large valve member having an annular rubber-like gasket member 82 of some suitable rubber-like material such as a form of chloroprene which is commonly known under the trade name "duprene. This rubberlike annular member has an inner flange which is fastened to the valve member 80 by a flanged member 84 threaded intothe top of the valve and whose flanges grip the inner flange of the an- .nular rubber-like member 82. The valve member 80 is guided within a boss 88 extending upwardly from the removable bottom portion 88 of the valve body which is fastened tothe middle portion of the valve body by cap screws ID. The valve member 80 is urged against the valve seat 14 by a compression type of coil spring I2 which is seated within an annular groove surrounding the valve guide 88. Within the valve member II is a smaller pilot or primary valve 84. This valve is guided by a pin 96 extending from the lower portion of this pilot valve into an aperture formed in the bottom valve member 80. The pilot or primary valve is resiliently urged in an upward direction by a rather weak coil spring I'L The upper portion .of this pilot valve is provided with a rubber-like gasket member 98 preferably of a. form of chloroprene commonly known under the trade name of "duprene. This rubber-like memher is fastened to the body of the pilot or primary valve by a screw III. This pilot or primary valve cooperates with a seat i formed on the threaded member 84.

In order to open these two valves there is provided a flexible metal bellows I08 in the upper portion of the valve body which has its upper fixed end connected to a flange member I" having its flange portion held between the bonnet I I0 and the main portion of. the valve body. The lower movable portion of the metal bellows is connected to a plate 2 fastened to the valve stein ill by a nut II! which holds the plate H2 tightly against a hexagonal shoulder on the valve stem. The upper end of this valve stem slides within the hollow lower end of anadjusting screw I20. Threaded upon the adjusting screw I20 is a spring retainer III which holds the upper end of a compression coil spring I24 while the lower end of the spring is held by the plate I II.

when thepressure in the crankcase or inlet of a. compressor is relatively high the bellows I is partially collapsed and the valve stem remains in its upper position. when the compressor starts, for example, after a shut down, both the large secondary valve 80 and the pilot or primary valve II are closed. At this time the pressure of the refrigerant in the evaporators as well as in the compressor acts upon the two valves and holds them tightly closed with the help of the springs 92 and 81. operation the pressure within the return line 58 and the inlet of. the compressor is gradually lowered. This reduces the pressure upon the closed end of the metal bellows I08 and permits the spring i 24 to movethe valve stem H4 downwardly. When the pressure within the crank case has been reduced a sumcient amount, the lower end of the valve stem ill comes into contact withthe screw I02 on the top of the pilot or primary valve 04 and begins to move the pilot valve downwardly. This permits the evaporated refrigerant to flow through the valve at a relatively slow rate and prevents a sudden load from being imposed upon the compressor. By this means the pressure upon the suction side is made rather constant and pressure on the two sides of the valve gradually approach equalization. As the pressure is still further reduced the bottom portion I 26 of the pilot valve ll comes into contact with the,

bottom portion I28 of the valve 80 and moves the secondary valve 89 to open position. As the pressure is further reduced, the valve 80 is moved to its fully open position and the evaporated rethe evaporator-s through the valve member 54 to the compressor and the system is therefore permitted to operate at maximum efliciency.

Thus in my valve the bellows and its spring are merely required'flrst to open the small pilot or primary valve which is backed by a rather weak spring. The pressure of the refrigerant in the evaporators exerts considerable pressure upon the valves tending to hold them closed and lightervalve springs may therefore be used. After the pressure has been reduced by the compressor the bellows acquires suflicient power to open the largevalve. This enables this valve to have sufficient sensitivity to properly throttle the refrigerant during the starting period of the compressor and also provide suflicient power both in theinitial stages of opening and in the flnal stages of opening. Thus by the use of this compound valve structure in the suction line the ob- As the compressor begins i'rige'rant is then permitted to freely move from iections to this form of control have been overcome.

.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, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus including an evaporating means, a compressor, and a condenser connected in operative circuit relation. said evaporating means being connected to said compressor and condenser, a compound valve comprising. a small pilot valve and a large main valve for controlling the flow of fluid between the evaporating means and the compressor, and

pressure responsive means for flrst opening the small pilot valve to reduce the pressure differential upon the main valve and than opening the large main valve. l

controlling the flow of fluid between the evapcrating means and the compressor, and pressure responsive means responsive to pressure at the aosaaoo 3- inlet of the compressor for iirst opening the small prising a small pilot valve and a large main valve pilot valve and then opening the large main valve. for controlling the flow oi fluid thrpugh said op- 3. Refrigerating apparatus including an evaperative circuit, and pressure responsive means orating means. a compressor, and a condenser for first opening the small pilot valve to reduce 5 connected in operative circuit relation, said the pressure diilerential upon the main valve and 5.

evaporating means being connected to said comthen opening thelarge main valve. pressor and condenser, a compound valve com DANIEL L. KAUFMAN.

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