US2975613A - Refrigerating apparatus with aspirator in a by-pass - Google Patents

Description

March 21, 1961 J. H. HEIDORN 2,975,613

REFRIGERATING APPARATUS WITH ASPIRATOR m A BY-PASS Filed Jan. 23, 1959 fiI IWh/ 20 42 38 \46 62 60 64 V as 1 49 V JNVENTOR. John H. He/dorn His A Ito/hey United States Patent C APPARATUS 'wrrn ASPIRATOR IN A BY-PASS 3 Claims. (Cl. 62-192) REFRIGERATING This invention pertains to refrigerating apparatus and especially to means for returning excessive amounts of lubricants collecting in the evaporator to the compressor.

All conventional mechanical compressors require lubrication. In a refrigerating system, the lubricant is carried through the system. Under low heat loads, the lubricant tends to accumulate in the evaporator thereby starving the compressor of lubricant. This condition is aggravated where low-pressure-drop parallel-pass evaporators are used. This condition is further aggravated when there is loss of refrigerant charge in the system. It is not practical to hermetically seal automotive air conditioning systems; such systems are subjected to road shocks and vibration stresses. Consequently, such systems are susceptible to leakage and occasionally such systems do leak.

Also in automotive air conditioning systems, it is customary to by-pass the condenser and evaporator with part of the refrigerant in order to avoid stopping and restarting the compressor. When this by-passing takes place, there is a tendency for the compressor to heat up. During the time the by-passing takes place, the heat load upon the evaporator is low, and the lubricant tends to accumulate in the evaporator causing the compressor to be starved of lubricant. This condition is aggravated when there is leakage of refrigerant from the system.

It is an object of this invention to provide an arrangement for returning to the compressor lubricant collected in the evaporator during the by-passing of the condenser and evaporator.

It is another object of this invention to provide added cooling of the compressor during-the by-passing of the condenser and evaporator.

It is a further object of this invention to draw a mixture of lubricantand refrigerant collecting in other parts of'the' r'ef-rigeratingflsystem intothe suction inlet of the compressor 'tonreturnflthe. lubricant, tothe compressor and to cool the compressor during the by-passing of the condenser and the evaporator.

These and other objects are attained in the form shown in the drawing in which an aspirator is placed in the bypass line by-passing the condenser and evaporator to draw a mixture of refrigerant and lubricant from the bottom of the evaporator into the bypass line so that this mixture is returned to the compressor during the bypass period for restoringthe lubricant to the compressor and for cooling the compressor.

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 embodiment of the present invention is clearly shown.

In the drawing:

Figure l is a diagrammatic view of a refrigerating system embodying one form of my invention; and

Figure 2 is an enlarged sectional view of the aspirator shown in Figure 1.

Referring now to the drawings, there is shown an automobile engine 20, normally used for driving the auto- 2,975,613 Patented Mar. 21, 1961 ice mobile, in which the air conditioning system is located. The automobile engine is provided with an additional pulley 22 which through a belt 24 drives the compressor pulley 26 connected through a magnetic clutch 28 with the automotive type compressor 36'. When the switch 32 is closed, current flows from the ground 34 through the battery 36, the conductor 38, the switch 32, the fuse 4%, the conductor 42 and the magnetic clutch 28 back to the ground 34. This causes the engagement of the clutch 28 to cause compressor 30 to be driven by the automobile engine 20. The compressor 30 withdraws evaporated refrigerant from the parallel-pass type of evaporator 44 through the suction conduit 46. The compressor 3t) compresses the evaporated refrigerant and delivers the evaporated refrigerant to the discharge conduit 48 which discharges into the condenser 50. The dis: charge conduit 48 may be provided with a muflier 49. The outlet of the condenser 50 discharges into a receiver 52 from which the refrigerant is conducted through the supply conductor 54 to a thermostatic expansion valve 56 having a thermostat control bulb 58 mounted upon the suction line adjacent the outlet of the evaporator44.

It is considered objectionable to frequently start and stop the compressor 30 since the addition and Withdrawal of the compressor load upon the engine 30 is quite noticeable under driving conditions. Automobile refrigerating systems are normally provided with a high refrigerating capacity, such as one and one-half tons for example, .so'

as to quickly cool a car which has become hot after being parked in the sun. Consequently, it is necessary to reduce the amount of refrigeration provided afterthe car has become sufiiciently cool for comfort. To do this without stopping the compressor 30, there is provided a by-pass conduit 60 connecting the discharge conduit 48 with the suction conduit 46. T 0 control the flow of refrigerant through this suction conduit 60 under low load conditions, there is provided a valve 62 in the bypass conduit 60 which opens when the suction pressure in the suction conduit 46 falls below a certain pressure. This valve is preferably made adjustable so that it may open at pressures varying from 30 to 50 pounds per square inch pressure on the suction side. A valve of this type is designated by the references 24 and 25 in the Waterfield Patent 2,363,273, issued November 21, 1944.

With this arrangement, during low load conditions, the pressure in the suction line 46 will fall sufficiently to cause the valve 62 to open to by-pass a considerable portion of the refrigerant discharged by the compressor 30. Under such conditions, the amount of evaporation of the refrigerant within the evaporator 44 will be greatly reduced. This will increase the amount of lubricant accumulating in the evaporator and cause a lesser amount of lubricant to be carried by the evaporated refrigerant through the suction conduit 46 to the compressor 30. This lubricant tends to mix with the refrigerant in the bottom of the evaporator and collect and remain in the bottom of the evaporator during periods of low heat loads. This condition is aggravated when the refrigerant escapes from the system. The by-passing of the refrigerant reduces the cooling effect of the refrigerant circulating through the compressor 30 and causes the compressor to become hot clue to the heat generated by the compression of the refrigerant. The reduced supply of lubricant caused by the collection of the lubricant in the evaporator 44 aggravates this heating and creates the danger that the compressor may not be properly lubricated under such circumstances when good lubrication is most needed.

According to my invention, I provide an aspirating device 64 in the form of a venturi section in the bypass conduit 66) in series with the valve 62. This venturi sec tion includes a central neck portion 66 having an interinch length on the inlet side and a tapered section 70 of 1%; inch on the outlet side. The central neck portion 66 is provided with a suction entrance 72 to which is connected a conduit means 74 extending to and connecting with the bottom of the evaporator 44.

According to my invention, whenever the valve 62 opens, the flow of refrigerant through the by-pass conduit 6t and particularly the venturi 64 will draw the mixture of refrigerant and lubricant from the bottom of the evaporator 44 into the stream of by-passing refrigerant which will carry it back through the suction inlet of the compressor 30 into the interior of the compressor. This will return the lubricant to the lubricant reservoir of the compessor 30. The lubricant will be cool since it has been drawn from the evaporator 44. In addition, any refrigerant mixed with the oil will evaporate and supply additional cooling to the compressor. Thus, by this sim ple device, the lubricant is returned from the evaporator 44 during the by-passing of the refrigerant and serves to restore the lubricant to the compressor 34) and to assist in'its cooling.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

l. Refrigerating apparatus including an operative refrigerant circuit comprising a compressing means having an inlet and an outlet a condensing means having an inlet and an outlet, an evaporating means having an inlet and an outlet, a first conduit means including a flow control device connecting the outlet of said condensing means and the inlet of the evaporating means, a second conduit means connecting the outlet of said compressing means and the inlet of said condensing means, a third conduit means connecting the outlet of the evaporating means and the inlet of the compressing means, a by-pass conduit means connecting said second and third conduit means, said bypass conduit means including an aspirator means provided with a suction entrance, said evaporating means having a portion where lubricant is apt to collect, a fifth conduit means extending from said suction entrance to said portion of said evaporating means, means for stopping flow through said by-pass conduit means to cause normal refrigeration to be produced by' said refrig'erant circuit and for opening said by-pass conduit means for stopping refrigeration in said refrigerant circuit and drawing lubricant from said evaporating means through said fifth conduit means.

2. Refrigerating apparatus including an operative refrigerant circuit comprising a compressing means having an inlet and an outlet, a condensing means having an inlet and an outlet, an evaporating means having an inlet and an outlet, a first conduit means including a flow control device connecting the outlet of said condensing means and the inlet of the evaporating means, a second conduit means connecting the outlet of said compressing means and the inlet of said condensing means, a third conduit means connecting the outlet of the evaporating means and the inlet of the compressing means, a bypass conduit means connecting said second and third conduit means, said by-pass conduit means including an aspirator means provided with a suction entrance, said evaporating means having a portion where lubricant is apt to collect, and a fifth conduit means extending from said suction entrance to said portion of said evaporating means, and a valve in said by-pass conduit means for closing said by-pass conduit means and stopping the bypassing of said condensing and evaporating means to pro duce normal refrigeration and for opening said by-pass conduit means to by-pass the condensing and evaporating means to prevent normal refrigeration and providing the withdrawal of lubricant from said evaporating means through said fifth conduit means.

3. Refrigerating apparatus including an operative refrigerant circuit comprising a compressing means having an inlet and an outlet, a condensing means having an inlet and an outlet, an evaporating means having an inlet and an outlet, a first conduit means including a flow control device connecting the outlet of said condensing means and the inlet of the evaporating means, a second conduit means connecting the outlet of said compressing means and the inlet of said condensing means, a third conduit means connecting the outlet of the evaporating means and the inlet of the compressing means, a bypass conduit means connecting said second andthird conduit means, said by-pass conduit means including a venturi portion having a neck portion provided with a suction entrance, said evaporating means having a portion where lubricant is apt to collect, a fifth conduit means extending from said suction entrance to said portion of said evaporating means, means for stopping flow through said by-pass conduit means to cause normal refrigeration to be produced by said refrigerant circuit and for opening said by-pass conduit means for stopping refrigeration in said refrigerant circuit and drawing lubricant from said evaporating means through said fifth conduit means.

References Cited in the file of this patent UNITED STATES PATENTS

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