US2394409A - Compressor - Google Patents

Description

Feb. 5, 1946. w c. sTEENsTRUPf' COMPRES SOR Filed June 20, 1944 2 Sheets-Sheet 1 Attorney.'

2 Sheets-Sheet 2 COMPRESSOR C. STEENSTRUP Filed June 20, v1944 Feb, 5, 1946.

la I V12. 3. \\lm m mw t @s ,mm t .P h C y 4is Attorney.

Patented Feb. 5, '1946 COMPRESSOR Christian Steenstrup, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application June 20, 1944, Serial No. 541,145

8 Claims.

My invention relates to compressors for refrigerating machines and the like and particularly to reciprocating compressors.

In the production of compressors on a large scale, it is desirable to eliminate as far as Dossible the rejection of parts due to even very slight inaccuracies in alignment. In other words, it is desirable that fairly wide tolerances be permissible at least for certain elements of the apparatus. For example, when a reciprocating compressor is driven by a crank it is dimcult to machine accurately large numbers of parts so that they are interchangeable and still make possible the exact alignment of the crank with respect to the cylinder. Inaccuracies in alignment of' the crank and the cylinder will result in binding and eventually loose ts due to wear and as a result noise is produced by the operation of the compressor. In the assembly of a reciprocating compressor such as employed in refrigerating machines, it is necessary to provide proper alignment of the crank shaft and piston and also to provide proper spacing and clearances for the crank shaft itself. In the construction of re frigerant compressors, particularly those for the hermetically sealed machines, it is desirable to eliminate or minimize all noises produced by the normal operation of the compressor and proper alignment of the parts is essential. Accordingly, it is an object of my invention to provide a compressor for refrigerating machines and the like including an improved arrangement for minimizing noise produced duringthe normal operation of the compressor.

It is another object of my invention to provide a compressor for refrigerating machines and the like including improved arrangements for insuring alignment of the moving parts of the compressor.

It is another object of my invention toprovide an improved Wrist pin and piston assembly for reciprocating compressors or the like.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed 'out with particularity in the claims annexed to and forming a part of this specication.

For a better understanding of my invention, reference may be had to the accompanying drawings in which Fig. 1 is a longitudinal side elevation partly in section of a hermetically sealed refrigerant compressor embodying my invention; Fig. 2 is an end view of the compressor shown in Fig. 1 with the casing cut away and with portions of the compressor shown in section; Fig. 3 is an enlarged sectional view of the wrist pin and piston shown in Fig. 1; Fig. 4 is an end view of Fig. 3 with one-half the piston removed; Fig. 5 is an enlarged view of the shaft alignment device shown in Fig. 1; Fig. 6 is an enlarged view of the lubricant pressure regulator illustrated in Fig. 2; and Fig. '7 is a sectional view on the line 1-1 of Fig. 1 showing the construction of the lubricant pump.

Briefly, the compressor illustrated in the accompanying drawings comprises a hermetically sealed casing within which is arrangeda recipro-4 cating compressor driven by an electric motor, the compressor and the stator of the motor being supported directly on the casing. A separate 1ubricant pump is provided for supplying a sunlcient quantity of lubricant to all moving parts of the mechanism under control of a suitable pressure regulator. A crank shaft for driving the compressor is provided 4with shoulders engaging the thrust bearings and a clearance between the pairs of shoulders may be adjusted by a cam ar'- rangement at the end of the shaft which may be locked in position to maintain the proper clearances throughout the l-'fe of the compressor. In order to insure correct alignment of the piston and crank or connecting rod bearing, the wrist pin and connecting rod are secured together by a device which permits sufficient adjustment of the alignment between the connecting rod andthe piston to compensate for any slight variations of alignment between the cylinder and the connecting rod bearing. The aligning device includes a spring pressed wedge which maintains the wrist pin always in contact with the connecting rod on the side of the wrist pin toward the crank shaft thereby minimizing noise which might otherwise be produced due to clearance between the wrist pin and connecting rod.

Referring now to Figs. 1 and 2, I have provided a hermetically sealed motor driven refrigerant compressor unit I including a cylindrical shell 2 having `end plates 3 and 4 welded or otherwise suitably bonded thereto to form an enclosing casing. The shell 2 is constructed preferably of steel and constitutes the frame in which is supported a laminated magnetic core structure 5 of an alternating current driving motor B. The laminations -5 are held in place between annular rings 1 and 8 which are welded or otherwise suitably secured to the shell 2. The motor is provided with stator windings 9 which are energized through leads I0 passing through sealed fittings Il to the exterior of the casing. yA compressor Iz is arranged within the easing and comprises a compressor block I3 which is rigidly secured to the ring 8 by suitable bolts or screws I4. The compressor block I3 is provided with a cylinder I'5 in which is located a piston I8. The piston is driven by a crank shaft I1 mounted ina bearing I8 in the block I3, motor 8 being provided with a. squirrel cage rotor I3 mounted on thev shaft I1., The shaft I1 is provided with annular shoulders 20 and 2l near the end of the shaft remotel from the motor I9 and is mounted in the bearing block 22 which is slidably arranged in a circular opening 23 in the compressor block I3. The shoulders 2l) and 2| are mounted in running engagement with annular thrust bearings 24 and 25, respectively, formed on the compressor block I3 and bearing block 22, respectively, and are retained in position'by a. dished bridging member or disk 28 incooperation with a movable camming member r adjusting plate 21. The compressor is provided with intake and exhaust valves (not shown) which are located within a cylinder head 28. Refrigerant gas which is admitted to the compressor through a pair of intakes V29-ilows through an intake muiller 30 andthence into the compressor head through a conduit 3|. The gas compressed within the cylinder I in cooperation with the piston is discharged through a connection 32 into an exhaust muiiler 33 and ows from the exhaust muillery andy out of the casing through a conduit 34 to the remaining components of the refrigerating system (not shown). Refrigerant returning from the refrigerating system is admitted to the casing through a suction"a5 line or return conduit 35.

In order to lubricate the compressor, a-body of oil or lubricating fluid is maintained in the casing I to a level indicated at 38, the bottom of the casing forming a lubricant sump. Lubricant is withdrawn from the sump through a velocity reducing intake baille 31 and an intake passage 38 in the block I3 by operation of a pump 38 the details of which are shown -in` Fig. '1. The intake baille 31 prevents the admission to the pump of gaseous or liquid refrigerant 'and also cil particles of foreign matter which may collect in the bottom of the casing. 'Ihis intake baille -construction is the invention of Carl H. Steenstrup and is described and claimed inapplication, Serial No; 541143, led concurrently 50 42 about the shaft adjacent the 'thrust bearing 0 24 and flows through a passage 43 in the crank shaft to an annular groove 44 in the bearing block 22. From the groove 44, the oil flows through a passage 45 to an'oil pressure regulator 45 of the spring pressed piston type. Oil discharged from the regulator 48 then ows to an annular groove 41 about'the walls of thecylinder I5 for lubricating the piston I8. It is thus apparent that oil is supplied to all moving parts of the compressor assembly.

The motor compressor unit may be supported in any suitable manner .ont the structure with which it is to be employed and has beenillustrated as resiliently suspended on springs 48 and 48 at either end thereof.

During the assembly of the motor compressor unit the shaft I1 is first inserted inthe bearing I8, the opening 23 in the block I3 providing room for the passage of the shoulders 28 and 2l longi- 5 tudinally into position.. The block 22 is then placed over the right-hand end of the shaft I1 and is moved into engagement with the thrust Y bearing 25, it'being noted that the end of the shaft projects slightly beyond the block 22. The

dished disk 28 is then placed in position bridging the end of the shaft I1 and engaging the block 22. The block and 'disk are preferably made approximately of the same diameter as the opening 23 so thatthey are guided by the walls of the opening in their axial movement. The camming plate 21 isthen adjusted to press the bearing block 22 against the shoulder 2l and also to press the shoulder against the thrust bearing 24. The camming plate 21 isconstructed so that 20 the correct clearances between the thrust bearings tion Serial N0. 596,497 led May 29, 1945,` and assigned to the same assignee.

The details of construction of the cammina device 21 and the associated parts will be ap. parent from Figs. 1, 2 and 5. The iplate is seao cured to the block I3 by suitable cap screws 58 and 5I the platebeing arranged to pivot on the screw 50 and being provided with a slot 52 affording lateral adjustment of the plate with respect to the shaft I1. As clearly shown in Fig. 5, the plate 21 is provided with a sloping camming surface,53 which engages the outermost portion or apex of the disk 28. y

By loosening the screws 58 and 5I. and pivoting the plate in a clockwise direction about the 40 screw 50, the camming surface53 may be made to force the disk 28 toward the left to press the block 22 into engagement with the shaft shoulder 2l. After the shaft is in position, the piston I8 together with a connecting rod 54 and wrist pin' 451s is inserted in the cylinder ,so that; the tep half f of the crank bearing formed in the connecting rod enga/ges the crank indicated at 55. The lower lhalf of the connecting rod bearing indicated at 51 is then secured in place by suitable screws 58. The compressor block is then placed ina suitable nxture and the crank I1 turned until the piston I8 is in its outermost position so that the crank is on dead-center. The camming plate 21 is then turned in a counterclock-wise direction and the 55 screws 50 and 5I tightened in a position such that f the shaft islocked against rotation, thecamming plate forcing the shoulders and thrust bearings into tight engagement. The blockl is then released from the xture and placed in a xture on which is located the rotor I9 having a counterweight 59 located so that when the shaft andi rotor are pressed together in the xture, the counterweight is located in its proper 'position with respect to the crank 55. Thereafter the plate 21 05 is released' and the compressor placed in ,another 'xture provided with means for gauging the longitudinal movement of the shaft I1. The plate 21 is then adjusted until the movement of thev 7o 7- zo and ai.

It is readily apparent that the arrangement :lust described for adjusting the shaft to its required position provides a simple and eective way for adjusting large numbers of parts in production. It has been found, however, that very slight variations of alignment between the cylinder and the crank shaft and between the piston and the wrist pin, which inaccuracies may be of the order of a very few thousandths of an inch or even less than a thousandth of an inch in some cases, produce vibration, noise and undue wear. The presence of these inaccuracies makes it necessary to align each compressor individually and greatly reduces the speed of production. -It is extremely diiiicult to machine the compressor block so that the shaft bearing and cylinder will be in alignment within the narrow clearances perv missible.

In order to ing accurate alignment, I have provided a connecting rod and piston assembly which insures correct alignment to compensate for any inaccuracies within predetermined permissible tolerances and which effectively minimizes noise and vibration of the mechanism.

As shown in Figs. 1, 3 and 4, the piston Yand connecting rod assembly includes the connecting rod 54 which has a circular opening 60 in its upper end and the piston IB which is provided with a cylindrical wrist pin bearing 6i and a wrist pin 55 which is journalled in the bearing 8| and passes through the opening 60 in the connecting rod. The piston is constructed of two halves i6a and l6b which are duplicate parts and are formed with upwardly extending recesses 62 having crescent-shaped shoulders 63 adjacent the upper side of the bearing 6| which serve as guides or bearings for the upper end of the connecting rod 54. The two halves l6a and Ib are secured together, preferably by brazlng, to form a unitary piston. The wrist pin 55 is hollow and has a cylindrical opening 64 therein which is open at one end and closed at the other end, except for a small opening 65. 'Ihe wrist pin is llocked in position in the opening 60 by a locking pin or key 66 which extends laterally from the interior of the wrist pin and is provided with a cone-shaped head 61 which ts the conically reamed lower end of a drill hole or recess 68 in the connecting rod at the top of the opening 60. 'I'he pin 66 is pressed upwardly into engagement with the connecting rod 54 by a wedge 65 slidably mounted in the inner passage 64 of the wrist pin and pressed toward the pin 66 by a spring 10 held under compression between the wedge 69 and the end of the wrist pin about the opening 65. The spring 10 is selected so that it will urge the pin 66 upwardly and press the wrist pin against the bottom of the opening 60 with sufficient force to maintain contact between the wrist pin 55 and the connecting rod 54 throughout the operation of the compressor. I'he opening 60 is not cylindrical but is relieved as indicated by the'clearance around the opening at 1 i. In the drawings, the clearance 1I has been exaggerated as it is necessary to provide only a few thousandths of an inch for the required purpose. Because of the clearance 1I, the wrist pin 55 may rock slightly laterally in the opening 60 and may pivot about the cone 61 at the upper end of the pin 66. This rocking movement makes it possible to vary slightly the angle between the connecting rod 54 and the piston I6. This slight variation in position is employed to oil'set inaccuracies in the alignment of the piston and bearing 6I and also in the alignment of the cylinder bbviate these dimeuiues in obtain- I6 and the crank 66. This change in alignment takes place automatically when the wrist pinis assembled in the compressor. The only movement which is necessary during the operation of the compressor may be a slight movement axially of the bearings and this is permitted since the connecting rod bearing may move axially of the crank B6 the few thousandths of an inch neces- Sary.

During the assembly of the wrist pin and the piston, the upper end of the connecting rod is first placed in the recess 62 with the opening 60 in alignment with the bearing 6I. The spring 10 and the wedge 69 are placed in the opening 64 in the wrist pin and the spring is compressed so that the pin 66 may be inserted from outside the pin until a head 12 on the pin 66 lies below the front edge of the-wedge 69 and retains the'.A

spring in its compressed position when the original pressure is released. The wrist pin is then inserted in the bearing 6| passing through the opening 60 until the pin 66 is in alignment with the conical opening 68. VThe spring 10 is then compressed and the pin 66 pressed upwardly until the head 12 is abovel the sloping portion of the wedge and is forced into position by the spring 10. The opening 6U makes it possible to tap the wedge 69 outwardly against the head 1-2 to be sure the head and the sloping portion of the wedge are in proper engagement. It will readily be understood that the reverse operation may be effected in order to take the assembly apart, the

the stream of oil is suddenly started or stopped,

head 12 on the pin 66 serving as a shoulder making it possible to draw the pin 66 into the hollow interior of the wrist pin after the wedge 69 has been pressed back against the spring 10. K

The simple wrist pin and piston assembly described above not only provides alignment to' offset inaccuracies in production machining operations but also maintains the wrist pin and connecting rod inA engagement at one point throughout the operation of the compressor regardless 'of changes in load and thereby minimizes noise. The locking or keying arrangement including the pin 66 thus serves not only to lock thewrist pin to the connecting rod and prevent rotation of the wrist pin in the opening 6D but also provides for the necessary initial alignment of the parts and maintains the required pressure at all times between the wrist pin and the connecting rod.

To obtain satisfactory operation of the compressor and to minimize noise it is desirable that the lubricating system operate to provide oil or other iluid lubricant at the desired uniform pressure and the regulator 46 is provided for this purpose. The details of the regulator are more clearly shown in Fig. 6, the piston 46 being mounted in a cylinder 13 and pressed toward the left by a spring 14. The cylinder 13 includes an intake port 15 which isthe upper end of the passage 45 and an exhaust port 16. During the operation of the-refrigerating machine the piston 46 moves back and forth across the exhaust port 16 and, if the cutoff is sharp, so that the flow of noise results. In order to minimize the noise due to sharp cutoi there is provided a bypass between the intake 15 and the exhaust port 16 which comprises an annular groove 11 arranged about the end of the piston 46 and communicating with the end of the cylinder 13 adjacent the intake port through a groove 18 formed in one side and across the top of the piston. The spring 14 is mounted between the piston and a stationary 'disk 19 securely pressed into an opening 80 at the outer end of the cylinder 13 and the piston l46 may rotate within the cylinder 13; however,

since the groove TI extends entirely about the piston, the Abypass is maintained between the inlet and exhaust ports of the cylinder 13 regardless of the position of the piston. Since there is always a ow of lubricant through the bypass during the operation of the mechanism, sharp cutoff is prevented and noise is minimized. A

I damping action for the piston 46 is obtained by 1 providing a small restricted opening .8| in the disk 'IiiA providing communication between the cylinder 13- and the casing about the cylinder block i3. Oil or a mixture of oil and gas will fill the cylinder 13 back of the piston 46 and the restricted opening 8| will limit the rate of passage of the iluid from the cylinder to the outside and thereby-damp sudden movements of the piston 46. This further eiects a reduction of noise. This regulator construction is described and' claimed in my copending application Serial No. 596,498, led May 29, 1945, and assigned to the same assignee.

From the foregoing it is readily apparent that I have provided simple and eiective arrangements for minimizing dimculties due to the unavoidable inaccuracies in machining of the parts of a compressor during quantity production and that these arrangements facilitate the interchanging of parts without the sacrifice of accu- Y rate alignment.

block provided with a cylinder and a, crank for reciprocating a piston in the cylinder, a piston and connecting rod .assembly comprising a piston havinga wrist pin bearing therein, a connecting rod having a crank bearing at one end and an opening at its other' end, a hollow wrist pin arranged in said opening and journaled -in said wrist pin bearing, and means mounted in said wrist pin for locking said pin against rotation in said opening and for maintaining said pin in contactwith the side of said opening adjacent said crank bearing throughout the operation of said piston whereby the forces acting between said rod and said piston are transmitted between said wrist pin and said adjacent side of said opening, said means aiording limited angular movement of said wrist 'pin with respect to said crank bearing to offset misaligmnent of the compressor cylinder with respect to the crank.

4. A piston and connecting rod assembly for compressors and the like comprising a piston having a wrist pin bearing therein, a connecting rod having a crank bearing at one end and an opening at its other end, a hollow wrist pin arranged in said opening and engaging said wrist pin bearing, and means arranged in said wrist vpin and including a member extending from said wrist pin and engaging said connecting rod on the trated and I intend by the appended claims to l cover all modiilcations within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

tact area between said member and said con,

necting rod to permit alignment of the piston with respect to said crank bearing.

5. A piston and connecting rod'assembly for compressors and the like comprising a piston having a wrist pin bearing therein, a connecting rod having a crank bearing at one'end and an opening at its other end, a hollow wrist pin arranged in said opening and engaging said wrist ing, and means arranged in said wrist pin and 5 including a member extending from said wrist pin and engaging said connecting rod on the side of said opening remote from said crank bearing for urging said wrist pin against the opposite side of said opening and for affording limited angular `movement of the longitudinal axis of said wrist pin with respect to said crank bearing, said member cooperating with said connecting rod to prevent rotation of said wrist pin in said opening.

2. A piston and connecting rod assembly for compressors and the like comprising a. piston having a wrist pin bearing therein, a connecting rod having a crank' bearing at one end and an opening at its other end, a hollow wrist pin arranged in said opening and engaging said wrist pin bearing, and means mounted' in said wrist pin for locking said pin against rotation in said opening, and for maintaining said pin in contact with the side of said opening adjacent said crank bearing throughout the operation of said piston whereby the forces acting between said rod and said piston are transmitted between said wrist pin and said rod through said adjacent side voi said opening.

. pin bearing, and means including a spring-pressed having a wristpin bearing therein, a connecting f rod having a' crank bearing at one end and an opening at its other end, a hollow wrist pin arranged in said opening and engaging said wrist Vpin bearing, a longitudinally slidabley wedge mounted in said wrist pin, a key slidably mounted in said wrist pin and extending laterally thereof into engagement with said connecting rod, and a spring arranged within said wrist pin for urging said wedge against said key to hold said key in engagement with said connecting rod for locking said assembly together.

'7. A piston and connecting rod assembly for ,compressors and the like comprising a piston having a -wrist pin bearing therein, a connecting*v 3. Ina compressor or the like having a cylinder' 75 arranged to nt the conical recess in said connecting rod, and a spring-pressed wedge arranged in said longitudinal recess for pressing said key into engagement with said connecting rod to lock said assembly together.

8. A piston and connecting rod assembly for compressors and the like comprising a piston having a wrist pin bearing therein, a connecting rod having a crank bearing at one end and an opening at its vother end, a hollow wrist pin arranged in said opening and engaging said wrist l0 o pin bearing, and means including a springpressed wedge movable longitudinally in said wrist pin and a key extending laterally from said pin and urged outwardly by said wedge for'locking said wrist pin against rotation in said opening, the end of said key within said wrist pin being provided with a shoulderwhereby the key may be engaged and drawn into said pin upon retraction of said wedge to permit removal of said4 wrist pin from said assembly.

CHRISTIAN sTEENsTRUP.

Images