US2076332A

US2076332A - Lubrication system

Info

Publication number: US2076332A
Application number: US29133A
Authority: US
Inventors: Robert W Zercher
Original assignee: YORK ICE MACHINERY CORP
Current assignee: YORK ICE MACHINERY Corp
Priority date: 1935-06-29
Filing date: 1935-06-29
Publication date: 1937-04-06
Anticipated expiration: 1954-04-06

Description

April 6, 1937. R. w. ZERCHER LUBRICATION SYSTEM V 2 Sheets-Sheet 1 Zmventor Filed June 29, 1935 R. w. ZERCHER 2,076,332

LUBRIGATION SYSTEM 'Filed June 29, 1935 2 Sheets-Sheet 2 5W @mmm W 2/ W7 mm ala-Nita (Ittgrneg S a s L 11% w an w mn A 6 iv. w n m, Nb wm on a I 2 5 5%. 3 Lu 0 F q. Q i fi L. 1 Q 1 L 1 LV w 6 Patented Apr. 5, 1937 umr o STATES FATE-T err-ice LUBRIGATION svs'rEM Robert W. Zercher, York, Pa., assignor to York Ice Machinery Corporation, York, Pa., a corporation of Delaware Application June 29, 1935, Serial No. 29,133

10 Claims. (01. 230206) This invention relates to lubricating means for refrigeration systems of the type in which a plurality of compressors operate in parallel relation and supply compressed gas to a refrigerating circuit. 1

In systems of this character it is usual to lubricate the compressors by the splash system in which the crank cases of the compressors act as sumps for the lubricating oil and are in communication with the low pressureside of the circuit. Where a plurality of compressors are operated in parallel, it is usual to cut them in or out, in accordance with the load on the refrigerating circuit, the control being either manual or automatic. Consequently, conditions arise where certain of the compressors are idle when others are operating.

Frequently the lubricating oil flows in suspension in the gaseous or liquid refrigerant, and this is particularly true when therefrigerant is one of the recently developed types, such as that mon suction and discharge lines, at such times as the crank case pressures of two compressors'become equal. It has also been found to be'equally important, as hereinafter explained, to prevent oil flow from one crank case to another at all times when the crank case pressures are unequal.

Equalization of the oil level between the crank cases of the various compressors an be obtained by providing equalizing conne tions between oints of proper oil level in the various crank c es. A constantly open connection is, however, not satisfactory, because the crankcase pressures of different compressors may'vary. When, for example, one or more of the machines is idle, crank case pressure tends to build up in themachine or machines which are active and this results in the oil from the crank case of an operating machine being displaced and transferred to the crank case of an idle machine. Obviously, such a condition must be avoided since it may result in acompressor running dry.

Consequently, it isproposed, according to this invention, to provide equalizing connections between the crank cases of the compressors, and to include in each connection a check valve having a moderate opening tendency. This valve will operate to prevent oil from being forced from the crank case of one machine to that of another by pressure differential developed between the crank cases of such machines, but will not prevent the equalizing gravity flow of oil when ad- .jacent machines are inactive or when the pressures are equalized.

The invention will be more fully understood when the following specification is read in conjunction with the drawings in which:--

Figure l is a diagrammaticalyiew of one form of refrigeration system embodying this invention;

Figure 2 is a detail sectional view of a double check valve which may be used in carrying out this invention;

Figure 3 is a view similar to Figure 1, but showing a modified arrangement of oil equalizing connections, also embodying this invention; and

Figure 4 is a sectional view of a check valve suitable for use in the system of Figure 3.

For purposes of illustration the invention has been shown in Figure 1, as embodied in a simple refrigeration system of the direct expansion type, although it is to be understood that it is of gen-" -eral application and may be used in connection with a system of the flooded type or in any system in which a plurality of compressors are connected in parallel with the refrigerating circuit and are capable of independent or conjoint operation.

Referring to Figure 1 the reference characters CI, C2 and C3 designate three compressors connected inparallel relation on their high sides to. a common pressure line 8 leading 'to a condenser 9. The system includes a line H running from the condenser 9 to a liquid receiver 12; a line l3 and an expansion valve I4 connecting the out flow of receiver I2 to the inlet of evaporator l5, and a return or suction line l6 connecting the evaporator with the low sides of the compressors Cl, C2 and C3 in parallel.

The three compressors shown will normally, 45

although not necessarily, be arranged'to be cut in serially according to the load on the refrigerating circuit, and to be cut out serially in reverse order. For example, under light load conditions the compressor. CI may operate alone.

On falling loads machine C3 will cut out first, then machine C2 and finally machine Cl.

Each of the compressors Cl, C2 and C3 has a crank case H which acts as a sump for lubricating oil. Connected between the crank cases ll of the compressors Cl and C2, at or below the normal oil level'therein, is an equalizing connection or line l8 containing a two-way check valve 20. A similar equalizing connection l9 containing a two-way check valve 21| is placed between the compressors C2 and C3. If only two machines are used,- a single equalizing connection will be chamber 22 partially closed at each end by a sleeve 23 threaded into the body 20 and having slots 24 for the reception of a wrench or screw driver. The inner end of each of the sleeves 23 has a countersunk seat for sealing cooperation with a ball check 26 which, under conditions of equal pressure at both ends of the chamber 22, gravitates to substantially the mid point of this chamber, as shown in Figure 2. When a pressure differential exists between the ends of the chamber 22, the ball 26 is forced into contact with the seat 25 of one or the other of the sleeves 23 thereby closing the equalizing connection against flow of lubricant. In moving to sealing engagement with either seat the ball is raised slightly against the attraction ofgravity. Consequently, the ball check may operate in either direction to prevent flow of lubricant between the crank cases of machines having unequal pressures. When, however, the crank pressures of two connected machines become substantially equal, the ball 26 will fall away from both of the seats 25. The oil flow will then be insufflcient to lift the ball to sealing position, leaving substantially unrestricted connection between the two ends of the chamber 22 and permitting equalizing flow of oil from one crank case to the other. It is unnecessary to provide an equalizing connection between the crank cases of compressors Cl and C3, because of the order in which the compressors are put into and out of action. Hence no such connection is shown. Obviously the use of this additional connection is within the scope of the invention.

The operation of the two-way check in the complete system shown may be stated briefly as follows:

When the compressor Cl alone is operating, its crank case pressure will predominate over that of the two idle machines. Consequently, the ball 26 will move against the left hand seat 25 of valve 20 and prevent flow of oil from the crank case of machine CI'to that of machine C2. If machine C2 then starts up, pressure between the crank cases of machines CI andC2 will be substantially equalized and the check 20 will open, while the check 2| between machines C2 and C3 will close. If machine C3 is likewise operating, both checks 20 and 2| will open, and the pressure will besubstantially equalized among the three crank cases. When machine C3 shuts. down, the check 2| between that machine and C2 will close to prevent oil from being discharged from the crank case of C2 to that of C3, and a similar operation of check 20 will occur when machine C2 shuts down. When all of the machines shut down both checks will open and the oil level will equalize among the three machines. While the invention has been described in connection with a system including a plurality of compressors connected in parallel and adapted for serial operation, the preferred arrangement is such that the compressors may operate in any order, and consequently flow of oil from one compressor to another is prevented whenever a pressure differential exists between any two machines. Figure 3 of the drawings illustrates a system of this character having the same evaporator, receiver and condenser arrangements as those shown in Figure 1.

Referring to Figure 3, thereference characters 31, 38 and 39 designate three compressors having pressure connections 5, 6 and 'I, respectively to the pressure side 8 of the refrigerating circuit. Similarly the

suction connections

21, 28 and 29 of these machines are made to the suction side l6 of the refrigerating circuit. n In this arrangement, the compressors 31, 38 and 39 may operate in any order, as for example, when the system is subject to manual control. Under such circumstances the operator would employ a number of machines commensurate with the refrigerating load, and would cut machines in or out, in accordance with variations in this load. A failure of one of the machines might result in a complete change in the order of operation, consequently, it is desirable to have the oil equalization independent of the order in which the compressors are put into or taken out of operation.

As shown in the drawings, the oil equalizingconnection comprises a main line 3| between the crank cases ll of the machines 31 and 39, and a branch line 33 interposed between the line 3| and the crank case ll of compressor 38. The oil equalizing connection has interposed between it, and each of the crank cases ll of the three compressors, a check valve 32 preferably constructed' and arranged as shown in Fig. 4. All of these valves are similar, hence a description of one of them will suiiice. This check valve is generally similar in form to that shown in Figure 2, except that in this case the arrangement is such that the ball need seat in one direction only. The valve comprises a valve body 32 threaded at 4| into the wall of a crank case I! and threaded at its opposite ends into a nipple 42 adapted to form a pressure tight seal with the line 3|. The body of the valve 32 is preferably formed on the outside for the reception of a wrench. It contains a chamber 34 similar to the chamber 22 of double check valve 20 previously described.- The end of chamber 32, adjacent the crank case I1, is closed by a threaded sleeve 35 havin wrench slots 24, and preferably formed at its end, adjacent the ball check 36, with a flat face, since this ball check need have a sealing connection at one, end only of chamber 34. The outer end of chamber 34 contains a'second threaded sleeve 23 having slots 24 and being otherwise similar to the sleeves 23 described in connection with the double check valve previously described.

Consequently, when pressure is substantially equalized between the inside of one of the crank casesl'l and the line 3|, the ball 36 gravitates to the position shown in Fig. 4. Whenever a. pressure diiferential is formed, however, so that the pressure within the crank. case I! predominates over that in line 3 I, the ball 36 will be lifted slightly and into contact with'the seat 25 on sleeve 23, thus sealing the crank case I'll against escape of oil therefrom. As soon as pressure between the crank case and the line 3! is equalized,

the ball 36 will gravitate again to the position shown in Fig. 4 so as to permit free equalizing flow of oil from one crank case to another through the line 3| or the-line 3! and branch line 33, as the case may be. It will be obvious that because of this arrangement of a ball check associated with each of the compressors 31, 38 and 39, there can be no flow of oil from one crank case to another, when a pressure diiferential exists between any two machines. Rise in pressure within any one of the three crank cases will cause the associated check valve 32 to close, thus cutting off the flow of oil through the equalizing connection.

It will be understood that the system shown in Figure 3 produces results similar to those of the apparatus of Figure 1, except that it is entirely independent of the order in which the compressors start or stop, and a one-way check. valve is sufilcient, since a check valve'is associated with each of the compressors. Consequently, the em- '25 bodiment of the invention shown in Figure 3 ofiers a flexibility of operation which is not possible with the system shown in Figure 1.

The invention described is of particular utility in systems where there is a marked tendency for 30 the lubricating oil to flow in suspension in the .40 ating in parallel. Consequently, no limitations other than those directly expressed in the claims are implied.

What is claimed is: 1. In a lubrication system, a circuit for a vola- 45 tile liquid medium; a plurality of compressors connected in parallel in said circuit and arranged to operate, one or more at a time, in accordance with the load on said circuit, eachoi said com pressors having an oil sump subject to the suc- 0 tion pressure of the circuit; a lubricating conduit connecting the sumps of said compressors; and means in said conduit for preventing flow of lubricant from one sump to another when a material pressure differential exists between them, 55 but permitting equalizing flow between said sumps when their pressures are substantially equal.

2. In a lubrication system, a circuit for a volatile liquid medium; at least two compressors having individual suction connections and individual 60 discharge connections with said circuit, and each having an oil reservoir subject to the suction pressure of the circuit; a lubricant level equalizing conduit connecting the reservoir of each compressor to the reservoir of the adjacent com- 5 pressor; and'means in each of said conduits for permitting lubricant equalizing fiow between adjacent inactive compressors but preventing flow between an active and an inactive compressor.

3. In a lubrication system, a circuit for a vola- 70 tile liquid medium; at least two compressors con nected in said circuit in parallel relation to one another and adapted for simultaneous or individual operation; a lubricant sump in each of said compressors subject to the suction pressure of 75 the circuit; a lubricant'conduit connecting the ting free equalizing flow between the sumps of the 5 compressors when their pressures are equal.

4. In a lubrication system, a circuit for a volatile liquid medium; a plurality of compressors having individual suction connections and individual discharge connections with said circuit; a 10.

lubricant sump associated with each of said compressors and subject to the suction pressure of the circuit; a lubricant level equalizing conduit between each sump and another; and a two-way check valve in said conduit, said valve being ar- 15 ranged to prevent lubricant flow from the sump of an active to that of an idle compressor and permitting equalizing flow between the sumps of idle compressors.

5. The combination of a closed circuitfor a 20 volatile liquid medium; at least two compressors connected in parallel in saidcircuit and capable of independent and conjoint operation, said compressors being of the type in which lubrication is effected from a charge or oil carried in the crank case, and the crank case is subject to the suction pressure in the system; a normally open oil level equalizing connection between the crank cases of such compressors; and means effective when a compressor is idle to close the equalizing connection between its crank case and the crank case of an active compressor.

6. The combination of a closed circuit for a volatile liquid medium; at least two compressors connected in parallel in said circuit and capable .of independent and conjoint operation, said compressors being of the type in which lubrication is efiected from a charge of oil carried in the crank case, and the crank case is subject to the suction pressure in the system; a normally open oil level l0 equalizing connection between the crank cases of such compressors; and means responsive to pressure differential between the crank cases of the compressors, for at times closing said equalizing connection to prevent flow of oil from one crank case to another.

v 7. In a lubrication system, a circuit for a volatile'liquid medium; .a plurality of compressors connected in parallel relation to one another to supply high pressure gas to saidcircuit, and to receive low pressure gas from, said circuit; an oil collecting reservoir in the low side of each of said compressors; an oil level equalizing conduit connecting all of said reservoirs together; and a two- Way check valve interposed in said conduit be- 5 tween the reservoir of each compressor and that of an adjacent compressor, said valves being gravity operated to permit equalizing flow of oil from one compressor to another when the reservoir pressures are equal, but responsive to a pressure differential between adjacent compressors to prevent flow 01' oil from one compressor to another. 7

8. In a'lubrication system, a circuit for a volatile liquid medium; a pluralityofcompressors having their crank cases formed to act as lubricant reservoirs subject to the suction pressure of the circuit and also subject to variable pressure depending upon whether they are active or idle;

means forconnecting saidcompressors to said circuit in parallel relation to one another; a lubricant level equalizing conduit connecting all of said reservoirs together; and a check valve interposed in said conduit between each compressor and another, said valve being biased by gravity to open position when two adjacent compressors are idle, and closed by the pressure difierential existing when one of two adjacent compressors is idle and the other is active.

9. In a lubrication system, a circuit for a volatile liquid medium; a plurality of compressors connected in parallel with said circuit, and having oil reservoirs subject to the suction pressure of the circuit; means for permitting equalizing flow of lubricant from the oil reservoinof one compressor to that of another when the pressures in these reservoirs are substantially equal; and means responsive to pressure differential between said reservoirs for preventing flow of lubricant from one reservoir to another.

10. The combination of a circuit in which a volatile liquid medium is converted between the liquid and vapor phases by changes of pressure and temperature, such circuit including a plurality of compressors connected in parallel therein, and capable of individual and conjointxoperation, said compressors having oil sumps subject to the suction pressure, from which sumps the compressors are lubricated and the circuit being so arranged that lubricant if entrained with the volatile medium will be returned to at least one of said sumps; oil level equalizing connections between the sumps of respective compressors; and check valve means interposed in said equalizing connections; said check valve means having an opening bias sufficient to maintain them open against differences in hydrostatic pressure occasioned by differences of oil level, but insuflicient to maintain them open against difierentials of suction pressure between different compressors, one of which is operating and the other of which is inactive.

' ROBERT W. ZERCHER.