US2596640A - Refrigerator compressor - Google Patents

Description

Mans, 1952 fF, BERRY 2, 5%,640

REFRIGERATOR COMPRESSOR Filed Aug. 21, 1946 5 Sheets-Sheet l FIG. I.

0 I INVENTOR.

. EPA N/IEERRY O BY naw

ATTOZZIYEY May 13, T952 F. BERRY- REFRIGERATOR COMPRESSOR s SheetsSheec 2 Filed Aug; 21, 1946 INVENTOR. F/PA AMBER/Rx ATTORNEY May 13, 1952 BERRY 2,596,640

REFRIGERATOR COMPRESSOR Filed Aug. 21, 1946 5 Sheets-Sheet 3 IN V EN TOR. FEM NKBEEF? Y AQLM% ATTORNEY May 13, 1952 F. BERRY 2,596,640

REFRIGERATOR COMPRESSOR Filed Aug. 21, 1946 5 Sheets-Sheet 4 llllll //A 33- ii IN V EN TOR. FA/VKBEHHY ATTORNEY May 13, 1952 BERRY 2,596,640

REFRIGERATOR COMPRESSOR Filed Aug. 21, 1946 5 Sheets-Sheet 5 IN VEN TOR. FPAN/fBEl-T'HY AT OZBNEY Kc invention.

Patented May 13, 1952 UNITED STATES PATENT OFFICE mrmotazrf tursssson Frank- Berry, Giirinth, Miss afss'ig nor, by mesne assignments. to Oliver Iron andStel; Gunner-a tion, Pittsburgh, -Pa., a corporation of Bennsxh V ia 1 Claim.

The "invention relates "to "rotary fluid compressors such as air orfreon compressors for use in refrigeration systems and the like. It has special application to multistage rotary compressors of the rotary abutment type.

A rotary fluid compressor if operated in reverse is a fluid motor. Consequently; it the motor which drives the compressor is turned off or disconnected, the compressed fluid will drive the compressor in reverse as aprime mover. or motor, dissipating the eonipressed fluid. At least this normally will be the case in the absence of check or unloader valves to'prevent'the fluid from flowing through the unit in reverse. Therefore, it is quite customary 'to provide spring orgravity operated check and'unloader valves at the low pressure fluid intake or at the high pressure outlet, or both, so that when the motor which drives the compressor is cut off, reverse flow of the compressed fluid is prevented.

I have discovered, however, that by a special construction and interrelation of the fluid passageway between stages and of the fluid outlet, eontrolled by ther-otary abutment, apressure balance can be achieved which will eifectively lock the compressor against operation in reverse as a motor. I have discovered, further, that'thls specialcons'truction and arrangement ma es it possible to dispense entirely with the use of check and unloadervalves without sacrificing the functions formerly served by such valves. Consequently I have been able to eliminate a number-or 'parts whileretainlngthe same operational characteristics with respect to looking against reverse flow. The elimination "of these "parts leads to a simpler construction which can "be manufactured "at lower cost and which is easier to maintain.

'Thus a primary object of my invention has been to eliminate the use of check; and unloader valves in multi-stage fluid compressors while retaining the principal advantages of such valves.

In the drawings:

'1 is a cemmiverneai cross sectional'vlew of a pref'e'rred form of mum-stage refrigerator "pressor constructed in accordance withmy 2 is a side elevatidnarview of the same compressor with its encasing hermetic shell shown in cross section.

Fig. 3 is an end elevational view of the same compressor. taken as indicated at 3-4 in Fig. 1.

Fig. 4 is a vertical cross sectional view taken on-the line 4-4 of F 1.

Fig. 5 is a detail section taken on the line 5-5 of Fig. 4.

Fig. 6. is a detail section taken through the centerline of the rotary abutment shaft as indicated at 6- 6 in Fig. 3.

Fig. 'l is a detail view of the rotary abutment member.

Figs. 8, 9., 10 and 11 are detail cross sectional views taken respectively on thelines 8-8, 9-9. I0. |:0 and H -H of Fig. I. Fig. 8. shows the abutment drive. and gear pump assembly, Fig. 9 the first stage cylinder, Fig. lojthe porting between first and second stage cylinders, and Fig. 1 1 the second stage cylinder.

Eigs. 12 and 13 showthe first'an'd second stage "cylinders, respectively, with the parts in a stopped position such as, will initiate reverse operation of the unit as a motor.

Figs. 14 and 15 show the. firstfand second stage cylinders, respectively, with the parts in a pressure balanced position, locked against further reverse operation.

The multi-stage, refrigerator compressor illustrated in the drawings comprises an electric motor l6. directsconnectejd to a compressor ll, the unit beingmounted in a, two-part rmetitally sealed shell 1.8, 19 "carried bysuitable mountin bracke 0. 2i.

Th e m r ssor 1. comp is s i s enera arran ement-spaced casing-members 1. 2:3 a d :2 formin the si e wa o an iu arc lincler chamher n djacen abutment *chemhers. s ace casin membe s 2 an iherebetwe 92min the oute eripheral. 5 .3; of th c der ham ersnd 41 91 the at bars, a piston rotor comprisinga strait-Z1 and si t r 28 a d 129 fixed theretqes 'br seys a d 1-. and Mar a utmesis 3,? and i @Ki t a ha t a y eans o 191 1 i i t ro ar a u ment baring news 3. a 35 to clear the pistonsas they pass the abutments. The abutment recesses 34, 3.5 may ext d pariin o th shaf 35. c ea sh in igs 9 6 1d .1,-

easing me ber L22. 3 1 .4 r v e, a m n sh t "suns 3 1 21. Ah end plate 42 adjacent thecasing ber 22 is fo'rmed'withbragiliets 43 supper rig an annular housing member 44 to receive the mounting ring 45 which carries "the stator 46 bf the motor. The stator 46 may have a press 22 and partly in the end plate 42.

The end plate 42 and the five casing members 22, 23, 24, 25 and 26 are secured together as by means of bolts 41 and machine screws 48 passing through aligned apertures therein, the latter having threaded engagement with the end plate 42. I prefer to employ, also, hollow tubes or dowel pins 49 to secure accurate alignment of the parts during assembly.

End plate 42 is formed with an extension 66 to support the armature of motor 16.

The righthand end of the motor-compressor shaft 21 (as viewed in Fig. 1) is of reduced diameter as at 52, and to it is keyed as at 53 (Fig. 8) a gear 54 meshing with a gear 55 keyed at 56 to the end of the abutment shaft 36. By this means the rotary abutment is driven at the same speed as the pistons but in the opposite direction. Thus as viewed in Figs. 9 and 11, the pistons 28 and 26 rotate in a clockwise direction and the abutments 62 and 33 in a counterclockwise direction.

The gears 54, 55 are enclosed by a cover plate or housing 51 secured to the casing member 24 as by means of screws 58 passing through flange 59 of the housing 51. The gears 54, 55 fit the housing in the manner shown in Fig. 8 to provide a gear pump lubricating the compressor as will be described further on. A tube 66 provides communication between the interior of the gear housing 51 and a point below the surface of the oil 6! contained in the hermetic shell l8, [9. The lubricating oil which is drawn in through tube 63 is forced by the gear pump 54, 56 through channelways 62, 63 of the pump housing (Fig. 3) to the ends of the rotor and abutment shafts 2! and 36. From the end of the rotor shaft 21 the oil is forced through a central bore 64 and thence through transverse bores 65, 66 and 6?. Transverse bores 65 and 66 lead to circumferential grooves lubricating the bearings in the casing members 23 and 24. Transverse bore 67 leads to an annular chamber 68 formed partly in the casing member From chamber 68 the oil is carried by the spiral groove 69 to an annular recess at the end of extension 50 for lubrication of the thrust bearing of the armature 5|. Excess oil passes out through the opening H leading from the recess 16. Also there is an overflow tube 12 leading directly from the gear pump casing and which discharges over the top of the compressor, this overflow discharge preventing excess pressure from being built up by the gear pump, while assuring a steady flow of the lubricant.

Oil passages are provided in the abutment shaft 36'similar to those described in connection with the rotor shaft 27.

The casing member 24 is bored and tapped to receive the end of an intake conduit 13 (see Figs. 3 and 6) communicating with a transverse passage 14 in casing member 26 (Figs. 6 and 9) leading to the first stage cylinder at its junction with the abutment chamber.

An intermediate fluid passageway 16. 16 between the two cylinders is arranged to pass partially compressed fluid from one cylinder to the other during a selected portion of the rotation of the shaft and pistons. Portion E5 of the intermediate passageway leads from abutment recess 34 of the first stage cylinder diagonally through the shaft 36 to the outer periphery thereof where, during a selected portion of rotation of the shaft 36, it communicates with portion 16 of the intermediate passageway formed in the casing member 23. The interval during which such commupassageway formed in the casing member 22.

The interval during which such communication obtains will be understood from consideration of Figs. 4 and 13. The opening and closing of the intermediate fluid passageway I5, 16 and fluid outlet passageway H, 18 is controlled by the rotary abutment, the intermediate fluid passageway, fluid outlet passageway and abutment mem-- bers being constructed and arranged so that when the compressor is stoppedwith thefluid outlet passageway open (Fig. 13), subjecting the compressor to being driven in reverse as a motor by the high pressure fluid in the shell l6, l9, the fluid outlet passageway 17, 18 will close and pressures on both sides of the piston 29 of the second stage cylinder (in this embodiment the final compression cylinder) will be equalized before the intermediate fluid passageway 15, 76 opens, whereby the compressor is locked against further operation in reverse.

The operation of the compressor may be summarized as follows:

Motor l6, through its rotor 5| fixed to the shaft 2?, drives the pistons 28 and 29 in a clockwise direction as viewed in Figs. 9 to 15 inclusive, and through gears 54, 55, drives the rotary abutments 32, 33 in a counterclockwise direction. When the parts are in the position shown in Figs. 9, 10 and 11, the compression stroke of the first stage (Fig. 9) is partially completed and that of the second stage (Fig. 11) is about to begin. Low pressure fluid is drawn into the unit through the conduit 13 and passage 74 Where it enters the first stage cylinder behind the piston 28. The fluid ahead of this piston is compressed until such time as the abutment 62 has reached a position where this abutment no longer seals off the cylinder from the abutment chamber as by uncovering the relief passageway 79. The compressed fluid ahead of the piston 28 then flows through passageway 15 which at this time is in communication with passageway 16. Also at this time the piston .29 of the second stage cylinder is in sealing engagement with the abutment 33 and the compressed fluid'from the first cylinder flowsbetween the piston 29 and the abutment. This piston, as it rotates. further compresses the fluid ahead of it (i. e. the fluid from the preceding cycle) against the rotary abutment 33 until such time as the latter uncovers the relief passageway 66 in casing member 25 permitting the fully compressed fluid to flow into the abutment recess 35 and through passageway 11 which will then be in communication with passageway 16 in casing member 22 as illustrated in Fig. 13, permitting the compressed fluid to flow through mufiler 8| and out through opening 82 into the shell l8, [9 which is maintained at the discharge pressure, or approximately so. A suitable outlet for the compressed fluid is provided in the shell at 63 to which a fluid conduit may be connected as desired. The construction of muflier 8| formed in casing member 22 is plainly illustrated in Fig. 4 and consists of a series of chambers joined by relatively narrow connecting passages. The locking action which prevents the compressor from being driven in reverse as a motor by the high pressure fluid in the'shell l8, [9 without the use of auxiliary check valves or unloading valves will now be described in more detail with particular reference to Figs. 12 to 15 inclusive. Figs. 12 and 13 show the first and second stage cylinders with the parts in such a position as upon stopping would initiate reverse operation of the unit as a motor. Figs. 14 and 15 show the first and second stage cylinders with the parts in, or approaching, a pressure balanced position, locked against further reverse operation. With the parts stopped as shown in Fig. 13, direct communication is afforded between the interior of the shell l8, l9 and the second stage cylinder via the opening 82 in the casing, mufiier 8| and outlet passages 18 and 71. The compressed fluid thus flowing back into the second stage cylinder will produce rotation of the piston 29 in a reverse direction (counterclockwise as viewed in Fig. 13) As it rotates, the fluid at the other side of the piston 29 will be compressed against abutment 33. During this backward rotation of piston 29 there is no communication between portions 75 and 16 of the passageway between stages as will be understood from a comparison of Figs. 12 and 14. Consequently a certain amount of fluid is trapped between the first and second stages during reverse rotation from the position shown in Figs. 12 and 13 to the position shown in Figs. 14 and 15. Moreover, with the parts in the position shown in Fig. 15, communication has been closed between that part H of the fluid outlet which is in the abutment shaft and that part 18 which is in the casing member 22. Thus no more high pressure fluid can flow back into the second stage cylinder. At this moment the fluid trapped between the stages will have been compressed somewhat so that any further reverse movement of the piston 29 will be only such slight amount as will balance the pressures on both sides of this piston. In other words, at this point there is high pressure fluid locked on both sides of the piston 29 and the piston simply moves a sufficient amount to equalize these two pressures, and comes to a stop. This pressure balanced condition is due to the fact that communication between the abutment shaft and the casing in the fluid outlet is closed upon reverse rotation of the abutment shaft and a pressure balance obtained before communication between the casing and abutment shaft in the fluid passageway between stages is opened.

The pressure balanced interlock between stages, by preventing reverse operation of the unit as a fluid motor, makes it possible to eliminate the use of check and unloading valves without sacrificing the functions formerly served by such valves.

It will be understood that my invention is applicable to compressors having a greater number of stages than the one specifically illustrated, for, so long as there are two or more stages it is possible to bring about the pressure balanced interlock against reversal of the unit. The terms and expressions which I have employed are used in a descriptive and not a limiting sense, and I have no intention of excluding such equivalents of the invention described, or of portions thereof, as fall within the purview of the claim.

I claim:

In a rotary fluid compressor, a casing having a plurality of annular compressor cylinders arranged side by side longitudinally along a common axis and rotary abutment chambers arranged longitudinally along a common axis and adjoining said cylinders, a piston in each cylinder fixed to a common shaft and a cooperating rotary abutment for each piston fixed to a common shaft, each abutment having a recess to clear its cooperating piston, an inlet through the casing to the first compression cylinder, an intermediate fluid passageway extending from one abutment recess through the abutment shaft to the casing and thence to the final compression cylinder, an outlet from the casing, and a fluid outlet passageway extending from the abutment recess of the final compression cylinder through the abutment shaft to said outlet, the opening and closing of said intermediate fluid passageway and fluid outlet passageway being controlled by the rotary abutment, and the intermediate fluid passageway, fluid outlet passageway, and abutment memhere being constructed and arranged so that when the compressor is stopped with the fluid outlet passageway open, subjecting the compressor to being driven in reverse as a motor by the high pressure fluid, the fluid outlet passageway will close and pressures on both sides of the piston of the final compression cylinder will be equalized before the intermediate fluid passageway opens, whereby the compressor is locked against further operation in reverse.

FRANK BERRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 720,460 McMillan Feb. 10, 1903 785,408 Cooper Mar. 21, 1905 973,190 Green Oct. 18, 1910 994,311 Green June 6, 1911 1,531,607 Green Mar. 31, 1925 1,989,552 Good Jan. 29, 1935 2,158,933 Good May 16, 1939 2,243,466 Kucher May 27, 1941 2,309,443 Cuthbert Jan. 26, 1943 2,423,507 Lawton July 8, 1947 FOREIGN PATENTS Number Country Date 14,335 France Sept. 18, 1911 18,188 Sweden Sept. 10, 1904 27,868 Switzerland Sept. 25, 1902 38,285 France Feb. 3, 1931 45,197 Switzerland Sept. 19, 1908 407,661 Great Britain June 18, 1932 771,638 France July 30, 1934 779,940 France Jan. 24, 1935

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