US2954681A - Refrigeration system - Google Patents

Description

Oct. 4, 1960 A. A. M CORMACK 2,954,681

REFRIGERATION SYSTEM Filed Jan. 29, 1958 INVENTOR. flux i. MZ'amvncx.

Unite States Patent '2,9s4,iss1

REFRIGERATION SYSTEM Alex A. McCormack, Cleveland, Tillie, assignor to Penn Controls, Inc.', Goshen, Ind.

Filed Jan. 29, 1958, Ser. No. 711,857 4 Claims. (or. 6 2-496) 1 This invention relates generally to mechanical refrigeration systems and in particular to a means for maintaining proper compressor head pressure at sub-normal ambient temperatures.

In the operation of mechanical refrigeration or "air conditioning systems in low ambient temperatures, it has been found that the compressor head pressure may fall to undesirably low values. The difliculty is brought about by the fact that with the "compressor head pressure abnormally low, a condensing pressure in the receiver may result which is so low as to prevent proper operation of the expansion valve or other means for creating a pressure drop at the 'ehtr'ance to the evaporator. Fur- 'ther, with an abnormally low compressor head pressure, there will be a drop in suction pressure, which will cause the evaporator to operate below its intended temperature causing freeze-ups or causing the low pressure cut-out -to operate prematurely.

I The present invention utilizes a bel1ows-actuated shutoff valve to modulate the flow of liquid out of thecondenser into the receiver. The bellows-actuator for the valve is arranged so that the valve is moved toward closed position with decreases in ambient temperature. A bypass relief valve, installed between the vapor line from the compressor and the liquid line to the receiver, opens upon a fixed rise in pressure differential caused by the closing or restricting of the bellows-actuated shut-01f valve. Thus the compressor head pressure is automatically raised to a desired level in low ambient temperatures. In normal ambient temperatures, the by-pass valve is fully closed and full and efficient use of the condenser results.

An object of the present invention, therefore, is to provide an arrangement whereby a mechanical refrigeration system may be controlled during low ambient temperatures so as to maintain proper compressor head pressure.

A further object of the present invention is to provide an ambient temperature correcting valve means which can be applied to an existing mechanical refrigeration system by an experienced refrigeration service man.

A further object of the present invention is to provide an arrangement of the type referred to above which, in normal ambient temperatures, makes full and efiicient use of the condenser and by-passes the condenser only at relatively low ambient temperatures.

These and other objects will become apparent as the description proceeds with reference to the accompanying drawing in which the drawing is a schematic illustration of a mechanical refrigeration system incorporating the valve means and auxiliary connections of the present invention.

Referring to the drawing, reference numeral 10 indicates a conventional compressor having a high pressure discharge line 11 connected to a conventional remote condenser 12. The condenser is connected by means of a liquid line 13 to a conventional receiver 14. A line 16 connects the receiver to a conventional evaporator er. 4-, was

Patented Q 17. An expansion valve, indicated at 18, controls the admission of refrigerant into the evaporator and the expanded refrigerant is drawn from the evaporator and through the suction line 19 by the compressor. It will be understood that what hasso far been described is a conventional mechanical refrigeration system in which refrigerant is delivered at head pressures of the order of pounds per square inch gauge to the condenser 12. At the condenser, heat is removed from the refrigerant, causing it to lique fy and to subsequently be collected in the receiver from whence it is metered into the evaporator.

In the operation of conventional refrigeration systems, as the condenser ambient temperature falls, the capacity of the condenser is increased, reducing the condensing pressure below the pressure necessary for proper operation of the expansion valve at the evaporator. The valve means of the present invention, now to be described, provides for automatically maintaining proper compressor head pressure.

The valve means and accompanying by-pass connection of the present invention includes the valve casing 21 having an inlet. opening 22 and an outlet opening 23. Within the casing the inlet opening and outlet opening are separated by means of a valved aperture 24. A valve closure disc 26 cooperates with the aperture and has a stem 27 extending centrally through a flexible bellows 28 of conventional type. The bellows 28 is filled with a suitable temperature responsive fluid, and the stem 27 is rigidly secured to the movable end plate of the bellows, so that upon a decrease in the ambient temperature at the bellows, thestem 27 will be moved inwardly causing the valve disc 26 to throttle the How of refrigerant from the condenser.

The upper end of the housing 21 is formed so as to provide a cylindrical boss 29, the interior of which communicates with the by-pass line 31 by means of the opening 32. The by-pass line 31 is connected by a suitable fitting (not shown) to the vapor line 11. A valve closure-33 controls the by-pass passage and is urged into seated position upon the circular boss 29 by means of a compression spring 34. It will be understood that the spring 34 may be suitably sized or adjusted so that the valve closure 33 will be moved from its seat upon the existence of a predetermined pressure differential between the vapor line 11 and the liquid line 13.

In operation, at normal ambient temperatures, the valve disc 26 will be positioned relatively far from the passage 24, permitting unobstructed flow of refrigerant from the condenser to the receiver. Since, during these conditions of operation, the pressure differential between the line 11 and the line 13 will be relatively low, the valve member 33 will remain seated. As the ambient temperature falls, the valve disc 26 will be moved toward the aperture 24, causing a throttling of the flow of refrigerant from the condenser. The restriction caused by the valve disc 26 results in an increase in the pressure differential between the line 11 and the line 13. When this pressure differential is suflicient to move valve closure 33 against the force exerted by spring 34, the valve 33 will be lifted from its seat, permitting refrigerant vapor to by-pass the condenser. Thus the throttling action of the ambient temperature responsive valve 26 prevents the compressor head pressure from falling to an undesirably low value, and the relief valve 33 maintains the proper pressure differential between the vapor line 11 and the liquid line 13 and thus maintains the proper condensing pressure.

From the foregoing it will be evident that the arrangement provided by the present invention automatically maintains the compressor head pressure at the desired level in low ambient temperatures, however, at normal ambients the condenser is used to full capacity and efficiency. It will be understood that the bellows-type actuator 28 could be replaced by other similar types of temperature responsive means, it being required only that the valve disc 26 be moved into throttling position in response to the decrease in ambient temperature.

The invention claimed is:

1. In a mechanical refrigeration system having a compressor, condenser, receiver and evaporator, a fluid line connecting the discharge side of said compressor to said condenser, means for adjustably admitting refrigerant from said receiver into said evaporator, a fluid line joining said evaporator and the suction side of said compressor, ambient temperature responsive valve means, a

fluid line connecting said valve means and said receiver, said valve means arranged to throttle refrigerant flow from said condenser into said valve-receiver line in response to decrease in temperature ambient to said condenser, a condenser by-pass line connecting said compressor-condenser line and said valve means, said valve means including a relief valve controlling flow through said by-pass and arranged to open when the diiferential in pressure between said compressor-condenser line and said valve-receiver line increases to a predetermined value.

2. In a mechanical refrigeration system having a compressor, condenser, and a receiver, a fluid line connecting the discharge side of said compressor to said condenser, ambient temperature responsive valve means, a fluid line connecting said valve means and said receiver, said valve means arranged to throttle refrigerant flow from said condenser into said valve-receiver line in response to decrease in temperature ambient to said condenser, a condenser by-pass line connecting said com pressor-condenser line and said valve means, said valve means including a relief valve controlling flow through said by-pass and arranged to allow such flow when the differential in pressure between said compressor-condenser line and said valve-receiver line increases to a predetermined value.

3. In a mechanical refrigeration system having a compressor, condenser, receiver and evaporator, a fluid line connecting the discharge of said compressor to said con denser, means for adjustably admitting refrigerant from said receiver into said evaporator, a fluid line joining said evaporator and the suction side of said compressor, valve means adapted to throttle refrigerant flow from said condenser, a fluid line connecting said valve means and said receiver, a fluid filled bellows adapted to operate said valve means in response to variations in temperature ambient to said condenser, a condenser by-pass line connecting said compressor-condenser line and said valve means, said valve means including a relief valve controlling flow through said by-pass and arranged to allow flow through said by-pass when the differential in pressure between said compressor-condenser line and said valve-receiver line increases to a predetermined value.

4. In a mechanical refrigeration system having a compressor, condenser, receiver and evaporator, a fluid line connecting the discharge of said compressor to said condenser, means for adjustably admitting refrigerant from said receiver into said evaporator, a fluid line joining said evaporator and the suction side of said compressor, ambient temperature responsive valve means, a fluid line connecting said valve means and said receiver, said valve means controlling flow from said condenser into said valve-receiver line and arranged to throttle refrigerant flow from said condenser in response to decrease in temperature ambient to said condenser, a condenser by-pass line connecting said compressor-condenser line and said valve means, said valve means including a relief valve controlling flow through said by-pass and allowing flow through said by-pass only when the differential pressure between said compressor-condenser line and said valvereceiver line increases to and above a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS 2,564,310 Nussbaum Aug. 14, 1951 2,707,868 Goodman May 10, 1955 2,761,287 Malkofi Sept. 4, 1956 2,869,330 Kramer Jan. 20, 1959 2,874,550 Musson Feb. 24, 1959

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