US1854997A - Refrigeration - Google Patents

Description

April 19, 1932. 'C E, PLQEGER 1,854,997

REFRI GERATION Filed April 2, 1929 INVE R 40 2. Eff/ )2W @f Patented Apr. 19, 1932 UNITED STATES PATENT OFFICE CLYDE EDWARD IPLOEGER, OFF EVANSVILLE, INDIANA, ASSIGNOR T0 SERVEL, INC., OF NEW' "YORK, N. Y., A CORPORATION OF DELAWARE REFBIGERATION Application mea April 2, 192s. serial No. 352,024.

My invention relates to refrigerating apparatus and particularly to refrlgerating apparatus in which oil is circulated.

In refrigerating systems of the compressorcondenser-evaporator cycle' type wherem a refrigerant and an oil are circulated through the cycle, the oil being heavier than the refrigerant or in solution or miscible with the refrigerant, separate passages serve f or the purpose of withdrawing gaseous fluid and liquid fluid from the evaporator, the liquid withdrawn being partly or wholly the oil. A compressor causes a suction force to lbe applied to both the gas passage and the hquid passage. `With fixed passages, as has heretofore been the practice, a variatlon 111 suction force applied by the compressor causes a variation of suction force applied to the liquid passage. While restricting members may be placed in the system and so arranged as to provide proper relative suctions for a given apparatus or for given condition of operation, fixed restrictions are not adaptable to widely varying conditions of operation or to different combinations of apparatus but result in such variations of .suction force on the liquid as to cause disadvantages in operation. To illustrate, assume a refrigerating system of the type known as multiple system having a large number of evaporators connected to a single compressorcondenser unit. Assume another multiple system with only one-third the number of evaporators. The capacities of compressors for use with these different systems will naturally be decidedly different and the suction forces on individual evaporators will vary considerably. Even in-a single system, the suction force will vary in different evaporators depending upon proximity to the compressor, the friction in pipe lines and other conditions. The variations in suction force cause variations in withdrawal of oil or mixed liquid refrigerant and oil from the evaporator and in many cases may result in an improper functioning due to excess pumping of oil. Even with a single cvaporating system the variations may be such that fixed restrictive members 'result in inferior operation.

To overcome these objections, I have devised an arrangement whereby a substantially constant suction force for withdrawing liquid is maintained for different conditions of compressor operation, for different conditions of gas Withdrawal and for different combinations of evaporators with different capacities of compressors. This is accomplished by having an automatically movable member 'acting to vary and determine flow through a gas passage in such manner as to produce'a substantially constant suction force on liquid withdrawn from the compressor.

The nature of my invention will becom apparent from the following description taken in conjunction with the accompanying drawings forming a part hereof and on which:

Fig. 1 shows a refrigerating system includingd my improved oil return control device; an

Fig. 2 shows a part of the apparatus of Fig. 1 on an enlarged scale.

In Fig. 1 is shown a system comprisin a gas compressor 10 driven by means ot a motor 11 receiving electricity from an electric circuit 12. Gaseous refrigerant entering compressor 10 from conduit 13 is compressed to a high pressure and passes through conduit 14; into condenser 15 where it is liquefied by air or water. From the compressor liquid refrigerant flows through conduit 16 and into a fitting 17 attached to an evaporator vessel 18. Fitting 17 has passages through the same for conducting the liquid refrigerant to evaporator tubing 19.` Liquid refrigerant entering tubing 19, which is placed within a refrigerator cabinet 20, expands and becomes gaseous. Gaseous refrigerant with some liquid refrigerant passes into chamber 21 within evaporator vessel 18 through outlet 22 of evaporator coil 19.

Within chamber 21 is a float 23 pivoted at 24 and operating a needle valve 25 within fitting 17 which controls supply of liquid refrigerant from conduit 16 into conduit 19. The oat is buoyed up by liquid in chamber 21 and the level of liquid determines the position of the oat and consequently the position of needle valve 25. Asl the liquid in chamber 21 rises, the float and needle valve 25 restrict flow of liquid refrigerant from conduit 16. into conduit 19.

Oil is contained inthe system and circulates through the system along with the refri erant.

(gaseous refrigerant and oil are withdrawn from the evaporator vessel through conduit 26 which passes through the refrigerating chamber in order to further evaporate refrigerant. compressor and becomes the inlet conduit 13 of the compressor. Conduit 26 is connected to a housing 27 fitted into the wall of the evaporator vessel 18 and situated above the highest level of liquid in the evaporator vessel. Housing 27 is shown in detail in Fig. 2. Housing 27 serves as a means of communication between the gas space of chamber 21 and the liquid space of chamber 21 and suction conduit 26. A suction passage 28 in housing 27 is threaded to receive the end of suction conduit 26. Gaseous refrigerant enters the suction housing through an opening 29. Liquid is drawn into the suction housing from the lower part of chamber 2-1 through a tube 30 which is provided with a strainer 3l at its inlet end. Screwed into. an intermediate passage 39 of the housing is a supporting'member 32 for a fixed spindle 33 having an enlarged hea-d 34 in opening 29. The spindle 33 is arranged longitudinally of the flow of gas through the housing. Movably supported Within the housin is a restricting member 35 in the form o a plate with an outside flange 36. The housing is formed with a recess 37 in which sets a spring 38 lwhich acts against plate 35 serving to force the plate against the tapered part of the enlarged head 34 of the spindle. The restrictive plate 35 has a center hole which is tapered to bear against the head 34. The space between plate 35 and member 32 is indicated by reference character 4() and may be considered as a suction chamber because it is the suction force in this chamber which determines the withdrawal of liquid through conduit 30. By suction as applied by chamber 540 is meant the negative difference of pressure in chamber 40 and in the gas space of evaporator vessel 18.

In operation, as `the compressor produces ""a suction on conduit 26, a suctionforce is created in chamber 40. This suction force, due to the present invention, is maintained substantially constant for the reason that plate 35 automatically adjusts its position within the. housing to maintain this substantially constant suction force. A pressure force determined by difference of pressure between the gas space of evaporator vessel 18 and pressure in chamber 40 acts on one side of plate 35 while the spring 38 acts on the other side. When a heavy suction is applied to conduit 26, the pressure differential Conduit 26 is continued to the v moves plate 35 against the force of this spring to increase the gas opening between the edge of the hole in plate 35and spindle 33. This admits more gas to chamber 40 and consequently increases the gas pressure therein and lowers the pressure differential. This action takes place to an extent whereby the opening between the plate and the spin dle is such as to maintain a substantially constant pressure in chamber 40.v

It will be seen that with this arrangement a large compressor or a small compressor with'large or small capacities respectively can be attached to the suction line and the pressure in lchamber 40 will remain substantially constant. This means that at all times there will be a constant withdrawal of liquid. The liquid passing through conduit 30 is made up of a proportion of oil depending upon the relative specific weights and solubility of refrigerant and the oil used. The pressure varies from constant only as respects the differences in pressure resulting from expansion and compression of spring 38. Spring 38 is a light spring and its variation is very small.

I have conducted tests on this device and where, with a fixed orifice in place of plate 35, a small capacity compressor ave a suction force in chamber 40 measure by a half inch water lift in chamber 40 and a large capacity compressor gave a suction force in Ichamber 40 measured by a ten inch water lift, with the present invention the same two compressors gave a difference of suction force measured by only a quarter of an inch height of water. With this small variation, a proper oil return is assured for all conditions of operation and the same device may be used for determining suction force for all types and combinations of apparatus.

Obviously variationsmay'be made in the design and construction and arrangement of parts. If' the housing 27 is turned 90 with the enlarged head of the spindle downward it would be possible to use a plate 35 of a weight which would permit omission of spring 38. Insuch case, a strictly constant pressure would be theoretically obtainable in chamber 40. Instead of having a spring act against plate 35, it is possible to have a weight on a bell-crank actagainst the same. What I claim is: I i 1. Refrigerating apparatus comprising an evaporator, means to withdraw gas from the evaporator, means to withdraw liquid from the evaporator and means acted on'by pressure in said evaporator on one side -and a spring on the other side for maintaining a constant rate of liquid withdrawal while permitting variable rates of gas withdrawal.

2. Refrigerating apparatus of the compressor, condenser, evaporator cycle type comprising an evaporator vessel, a suction conduit, means providing a passage for with- CFI drawing gas from said vessel to the suction conduit and providing a passage for withdrawing liquid from said vessel to the suction conduit and means for varying the effective area of the gas passage to maintain a substantially constant suction force on the liquid withdrawn.

8. Refrigerating apparatus of the compressor, condenser, evaporator cycle type comprising an evaporator vessel, a suction conduit, means providing a passage for withdrawing gas from said vessel to the suction conduit and providing a passage for withdrawing liquid from said vessel to the suction conduit and means for automatically var-ying the effect-ive area of the gas passagel to maintain a substantially constant suction :torce for the withdrawal of liquid.

4. Refrigerating apparatus of the compressor, condenser, evaporator cycle type comprising an evaporator vessel for containing liquid and gas, a suction housing connected by a gas passage to said vessel and by a liquid passage to said vessel, a suction conduit connecting said suction housing with the compressor whereby a suction force can be applied to said suction housing, a flow restricting member movable upon variation of suction force to alter the area of the gas passage and resilient means tending to hold the restricting member in a position of diminished area of gas flow.

-5. Refrigerating apparatus of the compressor, condenser, evaporator cycle type comprising an evaporator vessel for containing liquid and gas, a suction housing connected by a gas passage to said vessel and by a liquid passage to said vessel, a suction conduit connecting said suction housing with the compressor whereby la suction force can be applied to said suction housing, a flow restricting member movable upon variation o suction force to alter the area of the gas passage and a spring tending to hold the restricting member in a position oi diminished area of gas flow. y

6. Refrigerating apparatus of the compressor, condenser, evaporator cycle type comprising an evaporator vessel for containing liquid and gas, a suctionI housing connected by a gas passage to said vessel and by a liquid passage to said vessel, a suction conduit connecting said =suction housing with the compressor whereby a suction force can be applied to said suction housing, a flow restricting member movable upon variation of suction force to alter the area of the gas passage, a fixed spindle having an enlarged head for limiting movement of the movable member and resilient means tending to force the movable member against said head.

7. Refrigerating apparatus of the come.

ing liquid and gas, a suction housing connected by a gas passage to said vessel and by a liquid passage to said vessel, a suction conduit connecting said suction housing with the compressor whereby a suction force can be applied to said suction housing, a flow restricting member movable upon variation of suction force to alter the area of the gas passage and means acting against said movable member operating to maintain a iiXed suction force in the housing.

8. In a refrigerating system of the compressor-condenser-expander type including an evaporator and a suction line, means for withdrawing gas from said evaporator, means for withdrawing liquid from said evaporator, and means for maintaining a constant pressure differential between the evaporator and the suction line for withdrawing liquid from the evaporator at a predetermined constant rate.

In testimony whereof I have affixed my signature.

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