US2364783A - Oil return arrangement - Google Patents

Description

Dec. 12, 1944. M. B. GODDARD ETAL OIL RETURN ARRANGEMENT Filed Oct. 31, 1940 MERRILL B. GODDARD INVENTOR5 AND RICHARD C. OELER Patented Dec. 12, 1944 UNITED STATES PATENT OFFICE.

on. RETURN ARRANGEMENT Merrill B. Goddard and Richard C. Oeler, Chlcago, Ill., assignors of one-half to Carrier Corporation, Syracuse, N. Y., and one-half to The Liquid Carbonic Corporation, Chicago, Ill.

Application-October 31, 1940, Serial No. 363,712

Claims. (Cl. 62-115) This invention relates to refrigeration systems and more particularly to an oil return arrange-v ment employed in connection with flooded systems wherein the oil mixes with the refrigerant. The general object of the invention is 'to pro vide for the return of oil to a compressor from ie low side of a flooded refrigeration system wherein the efliciency of the system will be subciated with the cooler or evaporator, but such prior practices have not always been satisfactory, especially under varying load conditions, and in' some cases, the 'expedients employed required the use of needle valves, solenoid valves and the like, all of which are eliminated by applicants in their solution of the problem.

A feature of the invention resides in the provision of a simple accumulator structure operatively associated with a cooler .for effectively feeding oil back to the compressor, the amount of oil fed to the suction line of the compressor being proportional to the suction velocity or speed of the machine. Thus, under heavy loads, when the compressor operates at higher velocity, more oil will be led back than'under low load conditions when the compressor speeds are lower. In effect, *the amount of oil returned always meets the-requirements of operation despite varying load conditions.

A further feature of the invention resides in the provision of an 'oil return arrangement wherein the return of oil to a compressor automatically terminates when the compressor becomes inoperative, thus eliminating the dangers of rupture as might occur from a continuation of bleeding back of liquid to a compressor, especially of the reciprocating type.

Further features making for eflcientoperation, simplicity and economy in construction,

and substantial freedom from service troubles,

will be apparent from the following description of one form of the invention to be read in connection with the accompanying drawing, drawn to diflerent scales, in which:

Fig. 1 illustrates a flooded system incorporating an accumulator in which applicants oil return arrangement is employed, and Fig. 2 is a. sectional view diagrammatically illustrating that portion of the accumulator in which the oil return structure is provided, and

Fig; 3 is a fragmentary plan view illustrating certain features of the accumulator structure.

Referring to the drawing, similar designations referring tosimilar parts, numeral 4' generally designates a refrigeration system of the flooded type utilized, for example, for the cooling of water. A compressor-condenser assembly is diagrammatically lllustrated and includes compres sor base 5 on which is mounted motor 6 for driving compressor I, which is shown to be of the reciprocating, although it may be of any other, type. Although, one cylinder is diagram-,

matically shown, it will be understood that the machine may be a muiti-cylinder structure, the construction of which is well-known in the art, and the details of which are eliminated, since ,they form no part of the invention. Condenser the invention. The-liquid refrigerant plus such oil as is lost past the piston rings or is otherwise in the system, passes under high pressure from receiver 9 to heat exchanger l0, then through injector ll into cooler l2. From the cooler, the evaporated refrigerant plus liquid refrigerant plus such oil as is carried over enters accumulator l3 and the evaporated refrigerant (including a portion or such oil) is then returned to the compressor through heat exchanger Ill, back pressure regulator valve II, and suction line IE, to complete the cycle. The cooler or evaporator l2 serves a cold storage tank It from which water may be fed through cold water discharge line I] for any desired 'purpose, the cold water tank being equipped with a level control l8, and overflow pipe I! to provide a practical cold water supply system.

Considering the accumulator arrangement IS, a mixture of liquid and gaseous refrigerant in practice enters accumulator l3 from: the evaporator through line 20. This mixture also contains a portion of oil which has been carried over intothe system. The purpose of the accumulator is to cause a separation of the liquid from the gaseous refrigerant so that the liquid may bereturned to promote further refrigerating effect and the gas returned to the com- 66 pressor.

' operation, only gaseous to a compressor,

' free from possible clogging due to With applicant's accumulator structure, the liquid will settle to the bottom of accumulator l3 and will return through liquid leg 2| to in-.

jector II for recirculation to cooler 12. The gaseous refrigerant is sucked from the accumulator through return line 22- which is actually part of suction line [5.

To prevent excessive liquid refrigerant from being sucked into line 22 at the entrance point 23, a baflle 24 is positioned about-line 22 at the entrance end thereof. A flange or lip 25 is provided at the periphery of baflie 24 to form a cup or shallow receptacle. Access from the cup to line 22 is through an orifice 26.

In practice, a rush of liquid and gaseous refrigerant, containing a small amount of oil, enters theaccumulator through line 20. Such liquid as is routed between the cup and the inner wall 21 of the accumulator drops to the bottom thereof for return to the injector through leg 2|. Gaseous refrigerant above the liquid level in the accumulator is sucked into line 22 for return to the machine.

It may here be noted that if gaseous refrigerant were alone taken into the suction line 22, with the oil remaining behind in the low side of the I I it must be fed in small quantities and substantially free of liquid refrigerant. Also, such'return of liquid would result in possible damage to the compressor and hence, soon necessitate stopping operations.

To avoid the possibility of such undesirable the accumulator is so designed that refrigerant plus a desired metered quantity of oil is allowed to pass to the compressor. The baffle arrangement within accumulator l3 catches'oil and refrigerant to form a small source of supply to the compressor. In effect, only that small amount of liquid refrigerant, containing oil, which passes through orifice 26, is sucked into line 22. When this reaches heat exchanger l0 and comes in indirect contact with the hot liquid flowing therethrough from the high side of the machine, the refrigerant will in effect be boiled out and will reach the compressor, after leaving the heat exchanger, in gaseous superheated condition. The oil, in liquid form, carried over into the compressor, with the seous refrigerant, is free of liquid refrigerant, "and in a form to be accepted by the compressor for return to the crankcase.

Thus, applicants have provided a safe method of feeding a small amount of liquid containing oil but have assured the gasification of the liquid refrigerant in its course to the compressor so that the oil free of liquid reaches the compressor with the refrigerant fed to the compressor in gaseous form. The cup construction provides an adequate reservoir for continuous flow of liquid containing oil through a fixed orifice. 'I'he projecting lips 28 oneach side of orifice 26 form a pocket wi hin which liquid'is collected for continuous flow through the orifice while the system is in operation. 'The lips prevent sweeping away of liquid from the orifice. Interruption in the continuity of flow through the orifice is thus avoided. Screen 29 serves to keep the orifice particles carthe result would be an increasing con-' hence, more liquid will be fed back under heavierload conditions than when the compressor speed is lower under lower load conditions. Thus, the

, rate of return increases and decreases responsive to increases and decreases of load conditions andv assures a check on contamination in the system regardless of variations in load.

When the compressor shuts down, it will be impossible for the liquid to be returned to the The bleeding back automatically place the small amount of isdownwardly from 26 into the bottom of compressor. ceases since the only accumulated liquid can go the cup through the orifice the accumulator. This of feeding liquid back to the compressor which might cause blowing of a cylinder head or other damage.-

It may be noted that no valves are employed to throttle the fiow of liquid to the suction line, as

is customary in some prior arrangements; nor do applicants require a solenoid valve or similar arrangement, often employed in such systems for stopping flow of liquid when the compressor stops.

It is apparent that applicants system of oil return is applicable toall types of flooded systems and hence, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim: I l.'In a flooded refrigeration system, a compressor, a condenser, and an evaporator, operatively associated having oil to entrained therein to the accumulator I from the evaporator, a heat exchanger, means for withdrawing liquid refrigerant from the accumulator for return to the evaporator, means subjected to variations in suction pressure for withdrawing from the accumulator a varying quantity of refrigerant and oil and admitting the same to the heat exchanger, said refrigerant being gasifled in the heat exchanger, and means for returning the gaseous refrigerant and oil entrained therewith to the compressor from the heat exchanger.

3. In a compression refrigeration system containing a refrigerant anda supply ofoil, an accumulator, means for feeding a portion of said refrigerant with a portion of said oil entrained therein to the accumulator, means for withdrawing refrigerant with entrained oil from the ac cumulator consisting of aline having an inlet below the liquid level in the accumulator, a second line leading from within the accumulator, said second line having an inlet above the liquid level in the accumulator, means for admitting a measured quantity of refrigerant with entrained oil from the accumulator into said second line. the

eliminates any possibility together, an accumulator, means for admitting refrigerant having oil entrained aaomsa the second line and means for removing the resultant gas and oil entrained therewith from said gasifying means for further use in the system.

4. In a system of the character described, a compressor, a condenser and an evaporator operatively associated to carry on a refrigeration cycle, an accumulator, means for admitting refrigerant having oil entrained therein to the accumulator from the evaporator,'an injector for feeding liquid body of liquid below the receptacle, means responsive to suction pressure in said line for feeding a measured quantity of the liquid from said receptacle into said line.

7. In a system of the character described, an accumulator, means for feeding refrigerant with entrained oil into the accumulator, a suction line refrigerant supplied from the condenser to the evaporator, means for feeding liquid refrigerant from the accumulator to said injector, a collecting device within the accumulator, a measuring device through which liquid from said collecting device may be withdrawn, a suction line leading from a point above the liquid level in the accumulator and connecting said measuring device to the suction intake of the compressor, liquid refrigerant and oil entrained therewith being fed from said measuring device into said line responsive to suction pressure exerted on the line by said compressor, a

5. In a system of the character described, a compressor, a condenser, an evaporator, a heat interchanger, means for feeding refrigerant from the condenser to the interchanger, a line connecting the interchanger and evaporator for feeding refrigerant to the latter, an accumulator, means for feeding refrigerant with entrained oil leading from within the accumulator to a compressor, a cup-shaped receptacle within the accumulator, said line passing through the receptacle, an orifice connecting the receptacle to said line, gaseous refrigerant being fed into said line from the accumulator, liquid refrigerant with entrained oil being fed into said line through the orifice. I

8. In an accumulator arrangement according to claim 7, said cup forming a reservoir surrounding said line, and a plurality of lips within said cup forming a pocket about said oriflce to prevent liquid adjacent said orifice from being swept away.

9. In combination for use in a flooded system of the character described, a casing, a first line for supplying refrigerant from a point of evaporation to said casing, a second line leading from the casing, a third line leading from the casing, a

to the accumulator from the evaporator, means for returning a portion of said refrigerant with entrained oil from the accumulator to the line connecting the interchanger and evaporator, means for feeding anotherportion of refrigerant with entrained oil from a point above the liquid level in the accumulator to the interchanger responsive to suction pressure and means for admitting said last portion of refrigerant, converted into gaseous form, and. oil entrained therewith, from the interchanger into the compressor.

6. In a system of the character described, an evaporator, a compressor, an accumulator, means for supplying refrigerant having oil entrained therein from the evaporator to the accumulator through an inlet to the accumulator, a receptacle in the form of a cup positioned within and spaced from the walls of the accumulator, a suction line connected to the receptacle and leading to the compressor said receptacle being so related to the inlet of the accumulator and to the walls of the accumulator that some of the refrigerant and entrained oil discharged into the accumulator formsashallow pool of liquid in the receptacle and some of the refrigerant and entrained oil forms a receptacle positioned about the third line proximate the point of entrance of the refrigerant into the .casing from the first line, means for withdrawing liquid from the casing through the second line, means for withdrawing refrigerant in gaseous condition from the casing through the third line and'means for feeding a measured quantity of liquid refrigerant containing oil from the receptacle intothe third line.

10. In a system of the character described including a compressor, a condenser, an evaporator, an accumulator, a heat interchanger, means for feeding liquid refrigerant from the condenser to the interchanger, and then to the evaporator, means for admitting refrigerant from the evaporator to the accumulator, means for draining refrigerant from the accumulator to the evaporator, some of the refrigerant admitted to the accumulator being collected within the bottom of the accumulator, means for returning gaseous refrigerant from a point above the liquid level in the accumulator to the interchanger, means, for admitting from the accumulator a quantity of liquid refrigerant with entrained oil into the gaseous refrigerant fed to the interchanger, and a suction line for returning gaseous refrigerant plus oil from the interchanger to the compressor.

MERRIIL B. GODDARD. RICHARD c. earn

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