US3033009A

US3033009A - Multiple compressor system for refrigeration installation

Info

Publication number: US3033009A
Application number: US1300A
Authority: US
Inventors: Richard K Berger; Andrew J Nicholas; Linwood A Pickle; Augustus J Van Newenhoven
Original assignee: Worthington Corp
Current assignee: Worthington Corp
Priority date: 1960-01-08
Filing date: 1960-01-08
Publication date: 1962-05-08
Anticipated expiration: 1979-05-08

Description

y 1962 R. K. BERGER ETAL 3,033,009

- MULTIPLE COMPRESSOR SYSTEM FOR REFRIGERATION INSTALLATION Filed Jan. 8, 1960 2 SheetsSheet 1 RICHARD K. BERGER ANDREW I NICHOLAS LINWOOD A. PICKLE HENRI SOUMERAI AUGUSTUS J. VAN NEWENHOVEN INVENTORS AME/ Y 1962 R. K. BERGER ETAL 3,033,009

I MULTIPLE COMPRESSOR SYSTEM FOR REFRIGERATION INSTALLATION Filed Jan. 8, 1960 2 Sheets-Sheet 2 FIG. 2

RICHARD K. BERGER ANDREW J'. NICHOLAS LINWOOD A.PICKLE HENRI SOUMERAI AUGUSTUS J. VAN N EWEN HOVEN INVENTORS ilnited States aware Filed Jan. 8, 1960, Ser. No. 1,300 5 Claims. (Cl. 62-469) This invention relates to refrigeration installations and more particularly to multiple compressor systems used to circulate the refrigerant in such installations.

The application of multiple compressors as the circulating means in a refrigeration system as is shown in U.S. Patent 2,076,332 has certain advantages, both from the standpoint of manufacture and operational effectiveness, over single units having the capabilities of the multiple units.

For example, shutting down a unit in the multiple system is a more efiicient way of regulating the capacity of the system than can be accomplished with unloaders on a single unit.

Furthermore, individual units can be added into the refrigeration installation along with the normal growth or expansion of the plant including the installation.

But inherent defects in the construction of the components of the system and their adaptation to multiple compressor operation have created serious operational difiiculties which have limited the application of these systems in refrigeration installations.

One such difliculty is presented in prior art duplex systems. For example, during operation with one unit the pressure in the crankcase of the operating compressor is usually greater than that in the suction compartment. As a consequence oil that collects in the suction compartment due to reasons well known in the art, will not return to the crankcase where it is needed in proper quantity as lubricant.

Another operational limitation is presented in systems using more than two compressors, wherein one or more may be idle, as follows: the system pressure drop during foregoing operation may prevent the equalization of oil levels in the crankcases of the individual units. As a consequence one or more of the running units may become oil starved.

Various methods have been developed for multiple compressor systems to relieve the arresting influence that the higher gas pressure in the crankcase compartment has on lubricant collected in the motor compartment.

One such system is disclosed in U.S. Patent 2,869,775 and provides a compressor including check valves which prevent the buildup of abnormal pressures in the crankcase compartment, as above described, which arrests lubricant return thereto.

An analysis of the foregoing patent indicates that the problem relative lubricant return from suction to crankcase compartment is solved but that in providing means for destroying the system pressure to maintain substantially equal levels of lubricant in all of the crankcase compartments other difiiculties are presented and particularly in installations including more than two compressors. In order to provide a system of three or more units wherein the system pressure does not interfere with the equalization of oil levels in the crankcases, it is necessary, according to the teachings of the foregoing patent, to maintain definite relationships between the conduits interconnecting the suction, discharge and crankcase compartments and between check valves mounted in the partitions of the individual compressors. Said another way atent ace the system contemplated by Patent 2,869,775 solves the problem relative oil return from the suction to crankcase compartment in an individual unit but in attempt ing to provide for equalization of oil levels in all units of the system, presents technical requirements which increase the overall cost thereof.

In addition to insure proper operation the system contemplated in the above patent must be operated in ac cordance with predetermined operational instructions which at times may be difiicult to meet.

The present invention solves both the problem of oil return from suction compartment to crankcase compartment and equalization of oil level in all crankcases in such manner so as not to require complex technical considerations in the design or operation of the overall system.

Accordingly, it is an object of this invention to provide a multiple compressor system for a refrigeration installation which overcomes the problems mentioned hereinabove.

It is a further object of this invention to provide a less costly multiple compressor system by providing standardized components which are manufactured in accordance with assembly line techniques.

It is another object of this invention to provide a multiple compressor system which can be adapted to any refrigeration installation with minimum design consideration and at lowest possible cost.

With the foregoing objectives in view, and others as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing the multiple compressor system contemplated herein, and the features of the invention will be specifically pointed out in the claims.

In the drawings:

FIGURE 1 is a longitudinal view in part section showing the details of the compressor used in the system.

FIGURE 2 is a schematic view showing a multiple compressor system.

Referring to the drawings FIGURE 1 shows a compressor generally designated 1, adapted for use in the multiple compressor system and embodying the novel components which provide for the return of lubricant from the suction to crankcase compartment and in addition maintain substantially equal lubricant levels in all crankcase compartments when applied in a multiple type system as hereinafter described.

While FIGURE 1 shows a unit of the hermetic type, it will be understood by those familiar with this art that the concepts outlined herein may be applied to compressors having an independent prime mover and that reference to hermetic units hereinafter is solely for purposes of illustration.

The hermetic compressor shown in FIGURE 1 and forming the basic element of the multiple system resembles the unit described in United States application for Letters Patent Serial No. 742,111, now U.S. Patent 2,956,730, filed June 16, 1958 by Clark B. Hamilton and Linwood A. Pickle and said compressor basically comprises a casing 2 including a partition 3 which divides same into crankcase compartment 4 and a suction compartment 5.

A crankshaft 6 supportably mounted in

bearings

7 and 8 disposed respectively in the end of the casing 2 and in the partition 3 is provided with a jackshaft 9 which may be connected to a motor 11 as shown to provide a hermetic type unit or extend out of an end bell not shown for connection to a separate prime mover (not shown) as is well known in the art.

.lar to the centerline of the crankshaft.

A piston 12 is drivably connected to the crankshaft 6 by connecting rod 13. The piston is slidably disposed in a cylinder 14 formed transversely of the casing 2 and the partition 3 along an imaginary radial line perpendicu- It will be understood that while only one cylinder is shown that the present invention is equally applicable to multi-cylinder compressor units.

The cylinder is provided with the usual head 15 including the usual suction and discharge valve means 16 and 17 which communicate respectively with the suction chamber 18 and discharge outlet chamber 19. As is customary fluid from the low side of the refrigeration installation is passed to the suction chamber through opening 20 and to the high side of the installation from the discharge chamber 21.

Lubrication System .ervoir generally designated 31 formed in the lower portion of the crankcase. This lubricant is pumped from the reservoir by means of any suitable type of pump generally designated 32 which takes its suction through the suction inlet 33 and suction line 34 having a filter 35 about the opening thereof and disposed in the lower portion of the reservoir. The pump is provided with a discharge outlet 36 which communicates through a com- 'mon duct or passage 37 with the respective

transverse passages

38 and 39 which feed the

bearings

7 and 8 respectively. Other transverse passages 3? throw fluid onto the connecting means for the connecting rod 13 and other moving parts of the unit.

Compressors of the above described type are well known in the art and have been incorporated in multiple systems with the provision of a check valve to permit lubricant collected in the suction compartment to return to the crankcase compartment to bring the quantity of lubricant therein to normal level as is indicated at 50 in FIGURE 1.

As was mentioned hereinabove, blowby of refrigerant tends to raise and maintain the pressure in the crankcase compartment 4 above that in the suction compartment 5 to arrest lubricant return to the crankcase. This condition is further amplified ina multiple system, including the foregoing compressor, because the system pressure drop arrests equalization of lubricant levels in the crankcases. As a consequence it is necessary to provide some positive means for returning the lubricant from the suction compartment 5 and for destroying the effects of the system pressure drop which tends to arrest equalization of lubricant levels in the crankcase compartments.

The system pressure drop is destroyed with the provision of an orifice 51 in the partition 3 and conduit means 52 interconnecting the crankcase compartments so that the bottom of the conduit 52 opens into the crankcase at the normal lubricant level as shown at 53 and by providing an area ratio of at least 125 to 1 between the conduit and orifice.

With the foregoing provision the crankcases are at a pressure level between the higher suction pressure of the idle compressors and the lower suction pressure of the running units and accordingly lubricant tends to flow to equal levels in all crankcases.

While the above features, namely the coacting orifice and conduit, relieve the system from the problems caused by the system pressure drop it is pointed out that there results a higher pressure in the crankcase than in the suction compartment of the running unit. This is not a serious operational drawback bacause provision as above described will permit. equalization of. lubricant in... all

crankcases to prevent any one unit from becoming starved of same. However in practice it is desirable to provide means for returning lubricant from the low pressure suction compartment to the high pressure crankcase compartment of the running units.

This is accomplished by means of an ejector generally designated 60 which is described in greater detail in above Patent No. 2,956,730 and shown as including a suction inlet 61 connected to the partition 3 so that the inlet is disposed at a predetermined point in the partition for maintaining the level of collected oil in the motor compartment at the desired level as is shown at 62. The suction chamber communicates with the discharge outlet 63 which is disposed as shown in FIGURE 1 to discharge motive fluid onto the moving parts of the crankcase and piston assembly. The motive fluid is delivered to the ejector by means of a feed line 64 connected by any suitable connecting means 65 to the pump 32 at one end and at the other end by any suitable connecting means to the discharge portion of the ejector 61. Thus, means are provided to deliver motive fluid through the ejector in a manner well known in the art.

The apparatus described above thusly permits the adaptation of the compressor 1, which in itself. is an advance as it solves the oil return problem present in individual installations, into a multiple system Without the necessity of incorporating complex design changes.

A multiple compressor system including the above compressor is shown in FIGURE 2 and can be readily assembled by interconnecting the suction chambers 5 through conduit means 55 with the low side of therefrigeration installation .as will be readily understood by those skilled in this art. 'In similar fashion the discharge compartments 21 are interconnected by conduit means 56 with the high side of the installation.

Conduit 52 of a predetermined dimension relative the orifice 51 interconnects the crankcases to provide means for passing lubricant from crankcase to crankcase to provide equalization of level therein regardless of the sequence of operation of compressors.

Thusly with the above provisions applicant describes a multiple compressor system which eliminates the objections of prior type units and it will be evident to those skilled in the art that many changes may be made without departing from the scope of the appended claims.

What is claimed is:

1. A multiple compressor system for use in a refrigeration installation and including a plurality of compressors, each compressor comprising a casing including a partition therein dividing said easing into a suction compartment and a crankcase compartment, a discharge compartment in the casing, a lubrication system for said compressor and disposed in said casing, a suction conduit interconnecting each of the suction compartments and said conduit connected to the low side of the refrigeration installation, a discharge conduit interconnecting each of the discharge compartments and said discharge con duit connected to the high side of said refrigeration installation, an opening in the partition of each compressor to permit fluid to pass there through to maintain substantially equal pressures in both the suction and crankcase compartments, ejector means including a suction inlet and a discharge outlet disposed in the partition, the suction inlet of the ejector means communicating with the suction compartment, the discharge outlet of said ejector means being disposed in the crankcase compartment, means interconnecting the ejector with the lubrication system of said compressor whereby upon operation of the compressor said ejector will pass fluid from the suction compartment to the crankcase compart ment, and a conduit interconnecting the crankcase compartments of each of said compressors.

2. A multiple compressor system for use in a refrigeration installation and including a plurality of compressors, each compressor comprising a casing including a partition therein dividing said easing into a suction compartment and a crankcase compartment, a discharge compartment in the casing, a lubricating system including a pump means for the compressor and disposed in the casing, a suction conduit interconnecting each of the suction compartments and said suction conduit connected to the low side of the refrigeration installation, a discharge conduit interconnecting each of the discharge compartments and said discharge compartment connected to the high side of said installation, an orifice of a predetermined size in the partition of each of said compressors to permit fluid to pass therethrough to maintain substantially equal pressures in the suction and crankcase compartments, ejector means including a discharge outlet and a suction inlet disposed in said partition, said suction inlet communicating with the suction compartment, said discharge outlet communicating with the crankcase compartment, means connecting the discharge outlet of the ejector to the pump of the lubrication system whereby during operation of the pump means said ejector passes fluid from the suction compartment to the crankcase compartment, and a conduit of predetermined dimension interconnecting the crankcase compartment of each of said compressors.

3. A multiple compressor system for use in a refrigeration installation and including at least three compressors, each compressor comprising a casing including a partition therein dividing said easing into a suction compartment and a crankcase compartment, a discharge compartment in the casing, a lubrication system including a pump means for the compressor and disposed in the casing, a suction conduit interconnecting each of the suction compartments and said suction conduit connected to the low side of the refrigeration system, a discharge conduit interconnecting each of the discharge compartments and said discharge conduit connected to the high side of said refrigeration installation, an orifice of a predetermined dimension in the partition of each corn-pressor to permit fluid to pass therethrough to maintain substantially equal pressures in both suction and crankcase compartments, and ejector means including a suction inlet and a discharge outlet disposed in said partition, said suction inlet disposed in said partition at a predetermined point and in communication with the suction compartment for maintaining a desired level of lubricant in said suction compartment, and said discharge outlet disposed in the crankcase compartment at a predetermined point, means connecting the discharge outlet of the ejector to the pump means of the lubrication system whereby during operation of the pump means said ejector will pass fluid from the suction compartment to the crankcase compartment and direct said fluid adjacent the point of connection between the crankshaft and the connecting rod, and a conduit interconnecting the crankcase compartment of each of said compressors.

4. The system claimed in claim 3 wherein the bottom of the conduit interconnecting the crankcases is connected to the crankcases at the normal lubricant level.

5. The system claimed in claim 4 wherein the ratio of areas between the means in the casing providing communication between the suction and crankcase compartments and the conduit connecting the crankcases is at least to 1.

References Cited in the file of this patent UNITED STATES PATENTS 1,948,572 Floyd Feb. 27, 1934 1,954,498 Smith Apr. 10, 1934 2,048,025 Phillip July 21, 1936 2,076,332 Zercher Apr. 6, 1937 2,128,388 Williams Aug. 30, 1938 2,145,354 Hull Jan. 31, 1939 2,150,487 Brown Mar. 14, 1939 2,191,326 Smith, et al. Feb. 20, 1940 2,274,774 Chambers Mar. 3, 1942 2,738,652 Phillip Mar. 20, 1956 2,869,775 Neubauer Jan. 20, 1959 2,956,730 Hamilton et a1. Oct. 18, 1960 OTHER REFERENCES Trane Refrigeration Manual, Trane Company, La Crosse, Wis. Copyright 1946 (pages 17-18).