US2622788A

US2622788A - Refrigeration compressor

Info

Publication number: US2622788A
Application number: US642348A
Authority: US
Inventors: Ramclow Axel
Original assignee: Mills Ind Inc
Current assignee: Mills Industries Inc; Mills Ind Inc
Priority date: 1946-01-19
Filing date: 1946-01-19
Publication date: 1952-12-23
Anticipated expiration: 1969-12-23

Description

Dec. 23, 1952 cLow 2,622,788

REFRIGERATION COMPRESSOR Filed Jan. 19, 1946 2 SHEETS-SHEET l ZLQMIQ J Dec. 23, 1952 A. RAMCLOW REFRIGERATION COMPRESSOR Filed Jan. 19, 1946 2 SHEETS-SHEET 2 l I. 1 E N H I! Patented Dec. 23, 1 952 REFRIGERATION COMPRESSOR Axel Ramclow, Chicago, Ill., assignor to Mills Industries, Incorporated, Chicago, 111., a. corporation of Illinois Application January 19, 1946, Serial No. 642,348

8 Claims.

This invention relates to refrigeration compressors and is especially useful in compressors of the direct-drive type, that is, of the type in which the crank shaft of the compressor is connected directly to, and is in effect a continuation of, the drive shaft of a motor forming a part of a unitary motor-compressor unit, although certain features of the invention are not necessarily limited to this type of compressor.

It is the custom of the refrigeration industry to manufacture compressors in sizes to meet the power output of the standard sizes of electric motors available on the market. It is also the custom of the industry to produce condensing units having compressors of different displacement volume for each size of driving motor. For example, a choice of three different compressor displacements may be provided for a given size of motor and the selection will be determined'by the requirements of the refrigeration application for which the unit is to be used. In one common type of compressor drive, in which the compressor is driven from the motor by mean of V-belts and sheaves, the desired selection of three compressor displacements for each motor size is readily obtained by the selection of sheaves having a pitch diameter ratio which will provide the desired speed ratio between the motor and compressor, it being understood that with this type of drive the compressor is operated at a speed slower than that of the driving motor.

On the other hand, when direct-drive compressors, in which the motor rotor and the compressor have one common shaft, are employed, different compressor displacements have heretofore been possible only through changes of cylinder diameter and piston stroke. Such changes could be made only by changing the fundamental dimensions of the compressor which involved an entirely different model and size of compressor for each compressor displacement. This inflexibility had been a serious disadvantage of direct-drive compressors, although in certain other respects such compressors have definite advantages over the so-called belted type. Among such advantages is that the size of a direct-drive compressor may be much less than that of the relatively slow speed belt-drive compressors employing speed reduction means of the type above described. Compressor size is in inverse ratio to speed and the relatively high speed direct-drive compressors may, therefore, be very small. They may also be close coupled in relation to the motor, and thus very compact, Lighter weight is also another advantageous character: istic.

One-of the objects of the present invention is to provide a direct-drive compressor construction in which the compressor displacement may be changed with substantially the same simplicity as is possible with the relatively slow speed belt drive type of compressor.

A further object of the certain aspects also useful in other, constructions;

Other objects and. advantages of the invention the following description,-

will be apparent from taken in connection with the accompanying drawings, in which:

Fig. l is a cross-'sectional view of a two-cylinder opposd type of refrigeration compressor adapted-- to be driven directly from the shaft of an electric:

motor; and

Fig. 2 is a cross-sectional view of the come taken-at right angles to the plane of Fig. 1 and showing in elevation the motor housing.

As shown, the crankcase ll of the compressor is cast integrally with opposed cylinder blocks l2 and with an arcuate flange is formed with a shoulder the edge of the housing or l3 at one end'which I4 adapted to receive casing I5 of the drive motor, generally indicated by the reference by, means of a cylinder head '22 and cylinder head screws 23 which extend through the head and into tapped holes inthe cylinder block I2.

1 The clearance ofthe sleeve flange 18 within cylinder block l2 may be sufficient to permit ready assembly and conformity of the flange to the cylinder shoulder l 'l, it having been found in practice that a clearance of five-thousandths to six-thousandths of an inch is a desirable cleari ance. The clearance of .the valve plate 2| within the cylinder wall is preferably less than the clearance of the sleeve. flange 18, a clearance of one-thousandths to three-thousandths of 'aninchf having been found satisfactory inpractice. Thus there ispreferably a differential of, say," three-thousandths of .an inch between. the clearance of the sleeve flange and that of the valve plate. The relatively loose fit of the sleeve greatly facilitates manufacture and assembh'. The i8 is held tightly against the shoul invention is theiprofl vision of a lubricating system particularly well adapted to this type of compressor, although from der I! by the valve plate 2| and cylinder head 22. and these parts may be assembled in gas-tight contact by lapping the contacting surfaces or by the use of suitable gaskets therebetween. They are held in permanent compression by means of the cylinder head screws 23.

A discharge valve assembly 24 is provided on the valve plate 2| and, being off-known construction, need not be described in detail. It may be constructed in accordance with United States Patent No. 2,106,775, and provides for discharge of compressed gas through an opening 25 in the valve plate 2| into a chamber 28 in the cylinder head 22 in accordance with conventional practice. The compressed gas is conducted from the chamber 26 through a discharge opening 27 to the condenser (not shown) in'the usual manner.

A piston 28 is positioned within the cylinder sleeve I 9 for reciprocating motion therein and is connected bymeans of a connecting rod 29 with an: eccentric 3| .mounted on a crank shaft 32 extending lengthwise through the gas chamber 33 of the compressor. Anintake valve .34 is positioned on the head of the piston 28 which is o'f (hollow construction, said intake valve serving to admit refrigerant gas from the chamber 33 to a compression chamber 35in the sleeve l9 through openings .36 in the head 31 of the piston upon the .retractingstroke of thepiston, said openings 36 .being closedby the valve 34 upon the compressionstroke of the piston.

The shaft 32 is in effect a continuation of a drive shaft 38 of the motor 1.6 which passes through-an end plate 39 on the crankcase I I and is supported by .a bearing 4| integrally formed on the insideof said end plate 39'. Aremovable' sleevetype bronze journal 42, secured to the shaft 38, 32 provides bearing contact with .said bearing 41. Said journal 42 .is held in place against a shoulder 43 on the shaft 38 by means of a nut 44 positioned on the end of the shaft section-32 and-affording.pressureagainst the two eccentrics 3| which are mounted on said shaft section. Adjacent the inner end of the shaft section 32 is a thrust bearing 45 carried by a crankcase cover 46 which is secured to the crankcase casting by means of screws 41. A steel ball 48 and thrust spring 49 are mounted within a hollow end'portion of the shaft 32, said ball engaging .the thrust bearing 45 and the spring serving to push the shaft 32, 38 toward the motor .to maintain contact of the elements :of a shaft seal provided at the point of entrance of the shaft section 38 into the crankcase. Said seal may be of any suitable or desired construction, as, for example, the construction :shown in Patent No. 2,245,106.

A body'of oil 52 is contained within the lower part of the crankcase H and an oil reservoir 53 is provided between the'bearing 4| and aboss 54 on the wall 39 of thecrankcasecasting .l i through which the-shaft 38.extends-. Acoil spring belt .55 is mounted upon the journal 42 and an idler sheave 56 rotatably mounted on a screw 5'! extending into a boss 58 provided on the .inside of the wall 39 below the level of the oil in the crankcase. Said belt is held in place by means of a groove59 in the journal 42 and a groove 5| in the sheave 56. It is located within a channelshaped baflle 62 and above the inner end of the journal 42 within :said channel shaped baffle, a curved bafile '63 is .provided.

Said coil spring belt 55 is under such tension as .to' separate the coils slightly and said coils are ad'apted'to open up somewhat more as they pass 'isters with an oil hole 72 in one cylinder sleeves on the around the bottom of the sheave 56 and the top of the grooved journal 42. Capillary attraction causes lubricating oil to enter the interior of the spring and to be held between the coils as the belt travels upwardly from the body of oil 52. As it passes around the top of the journal 42, centrifugal force acting on the oil exceeds the capillary attraction and the adhesion tending to retain the oil within the coils, and this, coupled with the opening up of the coils, causes the oil to leave the belt and to be thrown against the curved bathe-63 which deflects it into the reservoir 53. The latter is thus kept filled with oil and the exposed parts of the seal 5| are submerged "within'the body of oil in this reservoir. The journal 42 has a helical oil groove 64 in the periphery thereof which communicates with a radialpil hole extending through the journal from an annular groove 66 formed on the exterior thereof. The shaft 38 has an annular groove 61 adapted to receive oil passing through the hole '65, and said shaft 38 is provided with an oil hole 68 opening into an o-ilpassage 69 drilled longitudinally in the shaft 38, 32. Said passage extends to the hollow portion of the shaft section 32 in which the spring 49 and ball 43 are located. An oil hole ll extends from thejpassage 69 radially through the shaft section 32 and regof the eccentrics 3'! from which the oil passes into a semicircular groove 13 in the large end of the connecting rod 29 which is nearest the motor. An oil hole 14 in the shaft section 32 registering with an .oil hole "#5 in the other eccentric supplies oil to a semicircular groove l5 in the other connecting rod.

From 'said semicircular grooves in the large ends 'of 'the connecting rods an oil passage 1! leads to an oil groove if! in the wrist pin 19 by which the connecting rod is connected to the piston 28.

The connecting rods 29 are assembled on the eccentrics 3! in such manner that the direction of rotation will force oil in the connecting rod oil grooves 13 and 76 through the passages 11 to the pistonpin oil grooves 78. Theadhesion of the oil to the eccentrics during the rotation of the" latter builds up in the

oil grooves

13 and 16 an accumulated pressure which forces the oil through the passages 17 to the wristpin grooves 18.

The refrigerant vapor to'be compressed enters the crank case through a conventional valve 8| and an opening 82, and, as previously indicated, is drawn into the compression chamber 35 in the suction stroke of the pistons. After compression it passes through the discharge valve 24 and outlet opening 21.

In order to provide a different compressor .dis placement when required for a particular use of the compressor, the cylinder sleeves i9 may be readily removed and replaced with sleeves .having a bore of different diameter. The construction above described makes it possible to make this substitution easily while at the same time providing the gas-tight relationship of the parts which is essential in compressor construction.

For the purpose of determining the extent of the effective stroke of the piston, openings 83 may, if desired, be provided in the walls of the cylinder sleeves is, the location of these openings or slots obviously determining the length of the effective stroke. Thus the compressor displacement may be varied by substitution of sleeves having the openings 83 differently located I lengthwise thereof as well as by the substitution of sleeves of different bore diameter.

The operation of the compressor does not differ substantially from that of other known constructions, with'the exception of the lubrication system which has heretofore been described, but the new construction has many advantages from the standpointof manufacturing and servicing which previous constructions do not have.

' The use of the replaceable cylinder sleeves H which may have various bores and be fitted with corresponding pistons, permits the use of a single model of cylinder block casting to produce compressors having various displacements. This is a great advantage in direct-drive compressors wherein the displacement cannot be changed by changing the compressor speed as can be done with belt-driven compressors. The use of the present invention thus makes it unnecessary to have a greater number of cylinder block models for direct-drive compressors than would be necessary in a comparable line of belt-driven compressors. I

In the conventional refrigeration compressor, in which the cylinder is cast integrally with the crankcase and is machined to provide the surfaces necessary to cooperate with the piston (without the use of a separate cylinder-sleeve), the machining of the cylinder bore is a very dimcult and exacting job. The accuracy of the cylinder bore dimension must be held within tolerance limits of a few ten-thousandths of an inch in relation to the piston, and if any error is made in the machining of either of the cylinders in the casting, the entire casting must be discarded or the eiiciency of the compressor will be impaired. It is much quicker and. less critical to machine a cylinder sleeve and cylinder block separately than it is to machine the two units combined in one casting and, furthermore, the cylinder block does not have to be machined nearly so accurately to properly receive the sleeve as if the piston were to work directly in a cylindervbore formed in the casting. With the construction of my invention only a relatively short portion of the cylinder block need be machined and the short machined surfaces which are contacted by the cylinder sleeve may have a relatively generous dimensional tolerance as compared with the tolerance between the piston and the surface against which it operates.

The separate cylinder sleeves can be machined in automatic screw machines with every operation complete except the final finish of the bore which can bedone quicker and more accurately in individual cylinder sleeves than it could be in a complicated cylinder block.

For the above and other reasons, a great deal of time and expense is saved in the manufacture of compressors constructed in accordance with the present invention and less skill is required than in the manufacture of conventional compressors.

Another advantage of the present invention lies in the elimination of cylinder wall distortion which is sometimes caused in conventional compressor construction by radial thrust of cylinder head screws when they are tightened into the cylinder block. These screws are ordinarily located in a circle around the cylinder bore in the casting and the thrust is at times sufficient to cause deflection of the cylinder wall toward the center of the cylinder. This deflection may be of sumcient amplitude to exceed the amount by which the piston is smaller than the cylinder bore and it may cause sticking of the piston for tion, the diameter of the valve plate is greater than the diameter of the annular flange on the sleeve and therefore the radial thrust would be on the valve plate and not on the sleeve, Furthermore, any distortion permitted by the valve plate would be taken up by the internal shoulder in the cylinder block, the internal diameter of which exceeds the outside diameter of the cylinder sleeve by an amount greater than any likely deflection of the shoulder.

A further advantage of the present construction is that the assembly of the mechanism is much simpler and a more compact unit can be obtained than with prior construction. This is by reason of the fact that a sub-assembly of the piston, connecting rod, eccentric and certain other parts may be made within the crankcase before the cylinder sleeve is inserted, which could not be done if integral cylinders were employed since the assembly referred to would be too long'to lit-between the inner ends of opposed cylinders. There are also other assembly advantages which will be apparent to those familiar with the manufacture of apparatus of this character.

It will also be apparent that with the present construction the cylinder sleeves (and pistons, if necessary) may be readily and quickly replaced by a serviceman in the field or in a local shop.

The lubricating mechanism hereinabove described is particularly useful in a direct-drive type of compressor for the purpose of lubricating the motor shaft and seal elements, as well as providing effective piston pin lubrication, and, as has been pointed out, the cylinder sleeve construction of the present invention has especial advantages in such compressors since the displacement volume thereof cannot be changed by merely changing the compressor speed as in the case of beltdriven compressors.

The foregoing detailed description has been given for clearness of understanding only, and nounnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

I claim:

V l. A refrigeration compressor comprising a crankcase having a cylinder block formed therein, the latter having an internal annular shoulder formed therein, a separate cylinder sleeve positi'o'ned'entirely within said cylinder block and extending into the crankcase, said sleeve having an external annular flange engaging said shoulder, a valve plate of greater diameter than said flange engaging said flange and having its periphery in contact with the interior of the cylinder block, a cylinder head contacting said plate, cylinder head screws holding said parts in assembled relation against said shoulder under compression, a piston reciprocably mountedin said cylinder sleeve, and means for actuating said position. Y 2. A refrigeration compressor comprising a crankcase having opposed cylinder blocks formed therein, the latter each having an internal annular shoulder formed therein, a separate cylinder sleeve positioned entirely within said cylinder sleeve positioned entirely within said cylinder block and. extending into the crankcase, said sleeve having an external annular flange engaging said shoulder, a valve plate of greater diameter than said flange engaging saidfiange and having its peripheryincontact with the interior of the cylinder block, a cylinder head contacting said plate, cylinder head screws holding said parts inassembled relationiagainst said shoulder under compression, a piston reciprocably mounted in said cylinder sleeve, and means for actuating said piston.

3. A refrigeration compressor comprising a crankcase having a cylinder block formed therein, 'the latter having an internal annular shoulder formed therein, a separate cylinder sleeve positioned entirely within said cylinder block and extending into the crankcase, said sleeve .havingan external annular flangeengaging said shoulder, a valve plate of greater diameter than said flange engaging said flange and havingits periphery in contact with the interior of the cylinder block, a cylinder head contacting said plate, cylinder head screws holding said parts .inassembled relation against said shoulder under compression, a piston reciprocably mounted in said cylinder sleeve, and means for actuating said piston, said means including a compressor shaft and a motor directly connected with said sha'ftfcr driving the same.

4. A refrigeration compressor comprising a crankcase having a cylinder block formed therein, the latter having an internal annular shoulder formed therein, a separate cylinder sleeve positioned entirely Within said cylinder block and extending into the crankcase, said sleeve having an. external annular flange engaging said shoulder, the clearance between said sleeve and the walls of the cylinder block being sufflciently great to permit ready manual assembly of the sleeve in the block, a valve plate of greater diameter than said flange engaging said flange and having its periphery in contact with the interior of the cylinder block, a cylinder head contacting said plate, cylinder head screws holding said parts in assembled relation against said shoulder under compression, a piston reciprocably mounted in said cylinder sleeve, and means for actuating said piston.

5. A refrigeration compressor comprising a crankcase having a cylinder block formed therein, the latter having an internal annular shoulder formed therein, a separate cylinder sleeve positioned entirely within said cylinder block and extending into the crankcase, saidsleeve having an external annular flange engaging said shoulder, a valve plate .engaging said flange and having its periphery in contact with the interior of the cylinder block, the clearance between the .sleeve and the walls of the cylinder block being substantially greater than that between the valve plate-and the Walls of said cylinder block acylinder head contacting said plate, cylinder head screws holding said parts .in assembled relation against said shoulder under compression, a piston reciprocably mounted in said cylinder sleeve, and means for actuating said piston.

:6. A refrigeration compressor comprising a crankcase having a cylinder block formed therein, the latter having an internal annular shoulder formed therein, a separate cylinder sleevepositioned entirely within said cylinder block and extending .into the crankcase, said sleeve having anexternal annular flange engaging said shoulder, a valve plate of greater diameter than said flange engaging said flange and having its periphcry in contact with the interior of the cylinder block, a cylinder head contacting said plate, cylinder head screws holding said parts in assembled relation against said shoulder under compression, a piston reciprocably mounted in said cylinder sleeve, and means for'actuating said piston, said cylinder sleeve being slotted intermediate its ends to determine the length of the effective stroke of said piston.

7. In a compressor of the class described, the combination of a-cylinder block, a cylinder sleeve, a circular valve plate, a cylinder head and cylinder head screws, said cylinder block having an internal'annular shoulder and said cylinder sleeve having an externalannular flange nesting in said cylinder block in contact with said internal anular cylinder block shoulder, said circular valve plate'being of greater diameter thansaidflange and being positioned within said cylinder block in contact with the external annular flange of said cylinder sleeve, said cylinder head being in pressure-exerting relationship with said valve plate, and said cylinder head screws being secured into said cylinder block under tension holding said cylinder head in place, said valve plate and said external flange of said cylinder sleeve being in fixed series relationship against said internal annular shoulder of said cylinder block and being disposed inside said block in close-fitting relationship with the wall thereof.

8. In a compressor of the class described, the combination of a cylinderblock, a cylinder sleeve, a circular valve plate, a cylinderhead and cylinder head screws, said cylinder block having an internal annular shoulder and said cylinder sleeve having an external annular flange nesting in said cylinder block in contact with said internal annular cylinder block shoulder, said. circular valve plate being positioned within said cylinder block in contact with the external annular flange of said cylinder sleeve, said cylinder head being in pressure-exerting relationship with said valve plate, and said cylinder head screws being secured into said cylinder block under tensionholding said cylidner head in place, said valve plate and said external flange of said cylinder sleeve being in fixed-series relationship against said internal annular shoulder of said cylinder block and being disposed inside said block in close-fitting .relationship with the wall thereof, said circular valve plate being of greater diameter than the maximum diameter of said sleeve.

AXEL .RAMCLQW.

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

UNITED STATES PATENTS Number Name Date 221,223 Epping -1 Nov. 4,1879 1,295,529 Lawhead Feb. 25,1919 1,583,535 Dubrovin May 4, 1926 1,643,645 Strand Sept. 27, 1927 1,763,395 Frederick June 10, 1930 1,915,165 Ramclau June'20, 1933 1,955,958 Greenwald Apr. 24, 1934 2,106,775 Trask Feb. '1, 1938 2,245,106 Karlberg June 10, 1941 2,406,229 Leinweber Aug. 20,1946 2,436,854 Corey Mar. 2, 1948