US2587246A - Hermetic refrigeration compressor - Google Patents

Description

Feb. 26, 1952 A J. roUBoRG 2,587,246

HERMETIC REFRIGERATION COMPRESSOR Filed Nov. 28, 1949 3 Shees-Sheel l FQJ. 22 f ffg nl x x v Bnnentor B @aa/#1% ZW Citt meg Feb. 26, 1952 1 TOUBQRG 2,587,246

HERMETIC RFRIGERATION COMPRESSOR Filed Nov. 28, 1949 3 Sheets-Sheet 2 JQDS j'uborg Feb. 26, 1952 J. TOUBORG 2,587,246

HERMETIC REFRIGERATION COMPRESSOR Filed Nov. 28, 1949 3 Sheets-Sheet 5 Jens Toubaf BB M W omeg Patented Feb. 26,

A 2,587,246 HERMETIC REFRIGERATION COMPRESSOR Jens Touborg, Tecumseh, Mich., assignor to Tresco, Inc., a corporation of Michigan Application November 28, 1949, Serial No. 129,738

7 Claims. (Cl. 2304-58) This invention relates to compressors of the which is also described in my prior and copending application, Serial No. 51,348, led September 27, 1948, and to that extent this application may be deemed a continuation in part.

One of the problems presented in connection with small or fractional horsepower compressors, to be used in conventional refrigerating systems, is the elimination of noise. Another problem is to assure adequate supplies of lubricant to the working parts, such as the motor shaft. It has heretofore been proposed to include a small auxiliary pump in the compressor assembly to deliver oil to the working parts, but it has been found, under many conditions of operation, that a pump having adequate capacity also generated a relatively loud noise, and thus detracted from one of the desired attributes of the compressor. Another problem encountered in the provision of a lubricant pump is that many proposals require a substantial number of additional parts, complicated porting and conduit arrangements and the like, and thus unduly increase the cost.

According to the present invention, a lubricant pump of high capacity, and which has been found to be substantially noiseless in operation, is built into the compressor assembly, and is so devised as to require substantially no additional parts, and a minimum of machining operations. In a preferred embodiment of the invention, the pumping effect is obtained by inclining a reciprocating piston-in-cylinder compressor with respect to the axis of the drive shaft, and utilizing the resulting relative linear motion between the crank pin and piston yoke to force oil into a duct drilled in the drive shaft. Additionally, the crank pin is also inclined to the axis of the drive shaft, to impart an arcuate oscillatory motion to the piston about its longitudinal axis. as well as a linear reciprocating motion. The compounded motion of the piston provides a wiping action within the cylinder, which laps or polishes out score marks that might otherwise be formed by adventitious dirt particles. Such motion moreover maintains the piston in motion in at least one direction at all times, and thus further eliminates or reduces a noise factor which is an incident to, or inherent in, reciprocating pistons whose linear motion is truly or approximately harmonic.

The principles of the invention, and the ad' vantages to be derived therefrom, will be made apparent from the following description of a typical embodiment, illustrated in the accompanying drawings, wherein:

Fig. 1 is a vertical section through a hermetic compressor incorporating the invention;

Fig. 2 is a bottom plan;

Figs. 3 to 6 inclusive are enlarged fragmentary -horizontal sections through the cylinder and piston assembly of the compressor, showing the relative positions of the parts at -ninety degree intervals during a complete revolution of the drive shaft;

Figs. '7 and `a are enlarged fragmentary vertical sections through the cylinder and piston assembly, showing the positions corresponding to those shown in Figs. 3 and 6, respectively;

Fig. 9 is an exploded view, partly in section and partly in elevation, of the drive shaft, crosshead. and piston and yoke of the compressor;

Fig. 10 is an additionally enlarged bottom plan of the crosshead; and,

Fig. l1 is a top plan of the piston and yoke assembly.

Referring primarily to Figs. 1 and 2, the compressor (in common with that'disclosed in my above identified prior application) comprises a two-part casing or shell including flanged sections 2| and 22, which are relatively shallow with respect to their diameters, and which are welded together after assembly to provide a hermetically sealed compressor. Within the casing are an electric motor 23, main casting 24, and a refrigerant pump or compressor 25, all of which. are connected together and are resiliently mounted in spaced relation to the casing walls. The casting 24 is generally annular in form', and it is provided at diametrically opposed points with outstanding lugs 26, each of which is transversely bored to receive mounting means, as will presently be described. The casting 24 is centrally formed with anupstandlng bearing boss 21, which is axially bored to receive a vertically disposed main drive shaft 28, whose ends project both above and below the boss.

The upper end of the shaft 28 receives a bored and counterbored quill 3| provided with a sleeve 32 whose lower end is supported on the upper end of the boss 21 through the medium of a thrust washer 33. The sleeve is suitably connected to the upper end of the shaft 28, as. for example, by means of a press iit. A motor rotor 34 is also press fitted into the q uill 3|. The motor stator 35 is mounted on a. shoulder 36 'through the aperture 45.

anemie formed onine periphery or the casting u. and ,it

is secured in position by any suitable means, such as bolts, not shown. The motor lead wires 31 extend to terminals 38 which pass through the wall of the casing section 22, and into a relay box,39, welded to the casing, wherein the indicated electrical connections may be made.

The casting 24 and the parts connected thereto are internally mounted in the casing by a resilient suspension cooperating with the casting lugs 26. The casing sections are each provided with spaced padportionsM, 42, located substantially radially equidistant from the longitudinal axis of the cylindrical dimension of the casing, and in an axial plane parallel thereto. Opposed pads may therefore bebrought into alignment when the casing sections are superimposed. As

described in detail in my aforesaid copending application, each pad is provided 'with an abutment or socket 43 which is welded thereto, to receive the ends of transversely extending spring supporting and retaining rods 44, which pass through tapped apertures 45 in the lugs 26. Each rod is surrounded by a coiled spring 4 6 which also passes The springs 46 are both helical and cylindrical, and they are-screwed/into the apertures 45 to project on each side thereof the proper distance to center or locate the compressor assembly within the casing. While the springs contact the lugs, they do not contact the rods 44 except at the ends thereof,.where they are bent into a generally hairpin convolution togrip the' rod on opposite sides, and around a small key 41 formed on either end thereof. These keys prevent rota.- tion of the springs and rods relative to each other after the assembly has been made and adjusted. -The casing section 22 is also provided with depending brackets 48, disposed above the lugs 26, to whichvare connected one yend of. tension springs 49, whose opposite ends engage openings formed in ears 5I of the lugs 26. The springs 4S absorb some of the weight of the assembly, andin conjunction with the springs 46, permit the resilient mounting of the parts in such fashion that forced vibrations, and resulting noise, is

minimized. l

The refrigerant pump unit 25 comprises acylinder block having'a cylinder, 56 bored therein, the head end of which is covered by a valve plate 51 and-cylinder head 58. Inasmuch as the details of the valves form no part ofthe present invention, and suitable structure is more fully described in my prior application, a further description of these parts appears unnecessary. The cylinder block 55 is secured to the under side of the casting 24 by bolts 59.- A piston 6I is reciprocably mounted in the cylinder 56 by means of an offset or crank portion 62 formed on the lower end of the main shaft 28, and below aV crank' arm 63 which carries a counterweight 64. The crank 62 rotatably ts into a diametrical bore 65 of a cylindrical crosshead 66, which is Vcarried for ltransverse reciprocatory movement in turning refrigerant vapors into the cylinder 56 v 4 The returning vapors line 1I at the top of the casing, flow around .the motor to absorb-some of its heat. and enter the cylinder head 68 through a suction tube 12 which extendsupwardly in the casing and above the oil level therein. The discharged vapors pass through a discharge line 1I which yis advantageously coiled in the oil bath at the bottom of the casing, and which terminates in an outlet line 14 passing through the casing wall. The compressor is adapted to be included in the usual compressor condenser expander refrigeration system. which needs no description here.

Considering further'the cylinder and piston and 'drive assembly. it will be seen, in Fig. 1 and' some -of the enlarged views, that the cylinder block $5 and the cylinder bore 58, are inclined at a slight angle to the horizontal plane. Similarly, while the motor and bearing portions of the main shaft 28 are disposed in a vertical plane, the crank portion 62 is inclined to the vertical plane. The piston 6I is, of course, also necessarily inclined to the horizontal plane, and it follows that it is not at right angles to the vertical. These inclinations depart from customary practice, and lead to the improvements with which the present invention is primarily concerned. It may here -be noted that while this angularity may be varied within reasonably wide limits, the drawings have here been laid out for deviations from the horizontal and vertical reference lines or planes for a fairly small angle, between two and three degrees. This is sufllcient for a compressor subject to the intended service of the illustrated unit.

As will be readily understood by those conversant with the Scotch yoke linkage, rotatlon of the drive shaft 28 about its own axis causes anorbital movement of the 'crank pin 62, which, in the usualor conventional casedescribes or sweeps out a right cylinder whose axis coincides with the axis of the drive shaft. The crank pin 62 rotatably rits in the bore 65 of the crosshead 66,' and the crosshead is guided in the bore of the transverse yoke 61. During one revolution of the drive shaft. the crosshead will therefore move lengthwise of the yoke with a linear reciprocatory motion, and the crosshead, yoke, and piston will also have a linear reciprocatory motion with respect to the longitudinal axis of the cylinder 56. The successive positions assumed by these parts are shown in Figs. 3 to A6, wherein Fig. 3 represents the end of the suction stroke and the beginning of the compression stroke. Counterclockwise rotation as viewed in these figures, will be assumed throughout the balance of the description. The piston 6| is then beginning to move to the left, and the crosshead 66 ismoving in an upward direction.

In the ensuing ninety degrees of rotation, the displacement of the crank pin 62 has moved the crosshead 66 upwardly to the limit of its travel A in this direction, and has also moved the piston 6I about half way in its stroke into the cylinder 56. Thisis shown in Fig. 4. In Fig. 5, the end of the compression stroke has been reached, and the displacement of the crankpin has caused the crosshead to recede from the upper end of itsl lenter through a suction the upper portion ofthe yoke, and the length of the pin 62 is such as to terminate adjacent the innermost chord taken through the arcs of intersection of the bore 65 and the periphery of the crosshead 66.

` As noted, the piston 6| and crank pin 62 are inclined to the normal axes, and therefore the arcuate motion of the crank pin is not such as to describe a cylinder, but rather a cone or frustum of a cone. That is to say, the inclination of the crank pin 62 causes its lower extremity to sweep through a circle of larger diameter than that traced by its upper end. As the crank pin 62 is fitted uniformly in the cylindrical bore 65 of the crosshead 66, it will be apparent that the crosshead will have a rocking or pendulum like motion about the vertical axis as it moves from-one end of the yoke to the other. Similarly, the inclination and motion of the crank pin will cause the yoke 61, and the connected piston 6|, to have a rocking motion about the vertical axis. In Figs. 3 to 6, wherein the vertical axis is normal to the plane of the paper, the rocking motion of the piston 6| is the same as an arcuate oscillatory motion of the piston about the axis of the cylinder 56, and it is herein illustratedby black dots on the piston surface, which show the displace.- ment on either side of the center line. If thes'e successive dot positions were connected, they would outline a relatively long oval or ellipse.

The effect of the combined linear and arcuate movements of the crosshead in the yoke, and the piston in the cylinder, is to change the alignment 82, 83,formed in the casting 24 (see also Fig. 1).

'for delivery to the exposed portion of the piston 6|.' The excess Oil falls by gravity to the oil bath contained in the bottom or crankcase portion of the casing; j

Theiower and Vcrank pin portions of the shaft 28 are longitudinally drilled to provide a duct between longitudinal lines of contact between the pairs of arcuate surfaces, thus producinga wiping or lapping action which otherwise would not be obtained. This motion is beneficial, as it serves to effect a better distribution of the oil films between the surfaces, and it increases the resistance to the introduction of small dirt particles which would cause scoring.

otherwise, the linear and arcuate motions are` out of phase, and, in this particular case, by approximately 180. Inasmuch as the end of the displacement or stroke of a body having har monic motion is accompanied by a reversal of direction of motion, the body, at the instant of reversal, has a zero velocity, while maximum velocity occurs as it passes through its centralpoint of reference. Thus, when the piston 6| reaches the end of its linear movement or stroke, its arcuate velocity is at its maximum, and thel piston is therefore always in motion. It has heretofore been observed that the reversal of stroke of a conventional piston-in-cylinder compressor has been accompanied by a slight hiss or noise, which was considered to be inherent and irreducible. It has now been discovered that by imparting the described compound and continuous motion to the piston, this source of noise is eliminated.

As heretofore noted, the inclination of the piston with respect to the horizontal axis is also are required. Considering particularly Fig. '9,

Athe drive'sha-ft 28 is forrred on its periphery above the crank arm 63 with a spiral groove 8|,

. utilized to provide a simple and effective lubricant pump, in which no additional moving parts 84 .which communicates with the groove 8| through a radial port 85. 'The crank pin 62 is formed with a radial slot 86 which intersects the duct 84, and the lower' end of the duct, below the slot 86, isv stopped oi with a plug 81 after the shaft has been machined. 'The crosshead 66 is formed with a transverse or vertical groove 88, which maybe machined in the wall ofthe bore 65 from one end thereof al sufficient distance to overlap the radial slot 86 when the parts are assemble'd, YThe crosshead. .66 is also formed with an angularly inclined, transversely disposed or tangential slot"89,- disposed on the external surface and extending upwardly from the bottom of the bore 65, and in spaced relation to the groove 88. `An oil groove 90 is also formed circumferentially of the crosshead 66, to supply lubricant to the bearing surface against the yoke 61.

Ihe .yoke 61 is formed with a port 9|, positioned above the lower trace of the yoke, and which is. in open communication with a flattened suction orriser tub'e 92, welded to the bottom of the yoke, the lower end of which is adapted `to dipinto the oil bath. Both the tangential slot 89 and theoil groove 90 are adapted to pass over the port 9| when the compressor is operated.

It will now be apparent that, as the piston 6| reciprocates, its yoke end moves downwardly with respect to the crank pin 62 on the suction stroke, and'upwardly on the compression stroke, due to the inclination of the piston with respect to the horizontal. Inasmuch as the lower end ofthe crankpin 62 `is adjacent the junction of the bore 65 with the wall of the crosshead 66, there is a small well or reservoir 93 constituting, in effect, a cylinder or pump chamber in which the crank pin reciprocates as a piston. Referring again to Figs. `3 -to` 8, it will be seen that, as the piston 6| reaches the end of its compression stroke Fig. 5-) the angularslot 89 in the crosshead 66 is about to register with the port 9| in the yoke 61, and thus place the slot 89 in fluid communication with the oil bath. As the shaft 28 continues 'to rotate, this communication becomes fully established, as shown in Fig. 6, and the reservoir 93 also is in fluid communication with Vthe oil bath, since the slot 89 extends downwardly thereto, as is clearly shown in Fig. 8. The crosshead is moving downwardly over the crank pin 62, to increase the volume of the reservoir 93, and the suction effect causes oil to flow into the reservoii` as long as the fluid passageway is open.

During this same time, the trailing edge of the radial slot 86 in the crank pin 62 has moved past the longitudinal duct 88 in the crosshead, thus closing off this passage, and preventing flow of oil therethrough. -As the crosshead 66 moves back to its central position the port 9| progressively closes, and is cut oi by the body of the crosshead as the end of the suction stroke is reached, as shown in Fig. 3. As the compression stroke begins, the leading edge of therradial slot 86 opens the duct 88, and the pressure Icreated by the upward motion of the crosshead 68' with respect to the crank pin 62 forces the oil into the radial slot 86, and thence into' the longitudinal duct 84. The lubricant is then distributed asheretofore described.

It has heretofore been stated that the actual' inclination of the piston to the horizontal, and the crank pin to the vertical, may be a small angle of only two or three degrees. Preferably, both piston and crank pin are inclined, and they are inclined equally with respect to their reference axes.

invention. For example, further consideration of the Figures will show that, with equal angularities, the axes of the crank pin and the piston are However, this condition need not be fulfilled within the broader principles of the at right angles to each other when the crank pin 4 has revolved 180 from the position shown in` be vertical. references to vertical and horizontal planes and axes are made for convenience of description, and not to -limit the invention to compressors mounted in one specific manner.

It will thus be seen that a positive displace-I ment oil pump has been formed from the basic elements of the driving connection itself, that is. .the drive shaft, crosshead, and yoke, and in which no additional moving parts are required. In my prior application, a system of porting through the driving elements is also disclosed, but

with added parts to provide a pump cylinder and.

piston. As with the lubricant pump of myprior invention, the present pump is so organized as to have its suction and pressure strokes coincide substantially with the suction and compression strokes of the refrigerant compressor.

The present pump is quite noiseless in operation, and, while the displacements are numerically small, they are sucient to supply adequate quantities of oil to the bearings and other working parts. In fact, the present pump delivers enough oil that a portion of it may be sprayed against the casing walls to aid in cooling, being thrown off centrifugally from the exposed upper end of the groove 8|, while the remaining portion drips through the rotor gap to lubricate the piston. The provision of the depending suction or riser tube 92 on the yoke 61 makes it unnecessary to submerge the yoke and cylinder block in the lubricant.

While the invention has been described with respect to a single embodiment thereof, it will be apparent to those skilled in the art that numerous modifications and alterations may be made without departure from its principles. It is therefore intended that the invention should be accorded a scope commensurate with that expressed inthe following claims.

I claim:

n 1. A compressor having a crankcase portion and a cylinder block formed with a cylinder bore, a piston reciprocably mounted in the cylinder bore and provided with a transversely disposed yoke at the crankcase end thereof, a crosshead slidably mounted in the yoke and formed with In this case.

When a larger, inclination of the piston is desired, and noise is. not so much of a factor, the crank pin axis mayl` It will, of course, be understood that4 a diametrical bore, a drive shaft having a crank pin portion rotatably mounted in the crosshead bore. a bearing for rotatably mounting the drive shaft for rotation about its own axis, said cylinder bore and piston being angularly inclined with respect to the axis of the drive shaft,.said yoke being positioned with its axisl at right angles to the axis of the piston, whereby upon rotation of the drive shaft the crank pin and crosshead bore have linear movement relative to each other. an oil duct extending longitudinally of the crank pin to the drive shaft bearing, an oil bath in the crank case portion, and ports formed in the crosshead adapted to be alternately opened and closed in timed relation to the linear movement of lthe crosshead to alternately subject oil in the oil duct to pressure and to replenish oil discharged from the duct fr om the oil bath.

2. A compressor having a reciprocable piston mounted in a fixed cylinder, said compressor having a crank case portion adapted to contain a bath ofl oil, a. drive shaft formed with a crank pin inclined to the axis of the drive shaft, a bearing for supporting the drive shaft for rotation about its own axis, a crosshead having a'diametrical bore in which the crank pin is rotatably mounted, a yoke surrounding the crosshead and connected to the piston with the axes of the piston and yoke at right angles to each other, said yoke having an imperforate wall beneath the bore of the crank pin, said piston having its axis inclined to the axis of the drive shaft, whereby upon rotation of the drive shaft the piston will reciprocate linearly in the cylinder and will also oscillate about its own axis and said crosshead will reciprocate linearly in the yoke, oscillate about its own axis, and reciprocate linearly of the crank pin to change the volume of the space between the end lof the crank pin and said imperforate wall of the yoke, porting means formed in the crosshead and adapted, when said space is increasing in volume, to place said space in communication with the oil bath, an oil duct extending longitudinally of the crank pin to said bearing, and additional porting means between the pin and duct to place said duct in communication with said space when it, is decreasing in volume.

3. In a compressor having a supporting casting and a drive shaft rotatably mounted in a bearing in the cast-ing for rotation about its own axis, a cylinder block formed with a cylinder bore connected to the casting, a reciprocable piston in the cylinder bore, said piston and bore having a common axis inclined to the axis/ of the drive shaft, a yoke connected to the crank case end of the piston, the axis of the yoke being disposed at right angles to the axis of the piston and transversely of the shaft axis, a cross head formed with a diametrical bore slidably mounted in the yoke, a crank pin on the drive shaft rotatably mounted in the crosshead bore, the end of the crank pin terminating short of the end of the bore to form a reservoir between the end of said crank pin, the wall of the bore, and the wall of the yoke, a lubricant duct having one end adapted to be placed in commiuiication with the reservoir extending longitudinally of the crank pin to the drive shaft bearing, valve means in the crank pin and crosshead for establishing said communication during one phase of rotation and for interrupting'said communication during a successive phase, additional valve means in the crosshead and yoke for interrupting and establishing communication between said reservoir 9 and the exterior of the yoke alternately to the operation of said rst named valve means, and means exterior of lthe yoke to supply oil to said reservoir when said reservoir is in communication with the exterior of the yoke through said additional valve means.

4. A combined refrigerant compressor and oil pump comprising a cylinder and a Apiston reciprocably mounted therein, a drive shaft and a bearing for the drive shaft, and a, Scotch yoke connection between the shaft and piston, said yoke comprising a yoke cylinder disposed at right angles to the piston and connected thereto and a cylindrical crosshead slidably mounted in the yoke, a bore in the crosshead, a crank pin on the drive shaft rotatably mounted in the bore. said piston being inclined to the axis of the shaft, a casing for the piston and shaft adapted to contain a bath of oil, ports formed in the yoke and crosshead adapted to be aligned during one phase of movement of the shaft and piston and rocable piston fitted in a fixed cylinder and a drive shaft rotatably mounted in a fixed bearing, a Scotch yoke connection between the shaft and piston comprising a cylindrical yoke connected to the crank end of the piston at right angles to the axis thereof and a cylindrical crosshead reciprocably mounted in the yoke, said crosshead being formed with a diametrical bore and said drive shaft being formed with a crank pin rotatably mounted in said bore, the axis of the piston being inclined to the axis of the drive shaft. saidY yoke being formed with an oil admission port disposed within the outermost trace of the crosshead bore, said crosshead being formed with a tangential slot communicating with the bore and adapted upon reciprocation of the crosshead to periodically register With and be displaced from said port, an oil duct formed in the crank pin and extending to the bearing, a radial slot formed in the crank pin communicating with the duct. and a groove in the bore adapted to register with the radial slot during that phase of motion of the crank pin and crosshead when the tangential slot is displaced from said port.

6. In a refrigerant compressor having av reciprocable piston fitted in a, fixed cylinder and a drive shaft rotatably mounted in a fixed bearing, a Scotch yoke connection between the piston and shaft including a cylindrical yoke connected to the piston at right angles to the axis thereof, a cylindrical crosshead slidably mounted in the yoke and formed with a diametrical bore, a crank pin on the drive shaft rotatably mounted in said bore, said piston being inclined to the axis of the drive shaft and said crank pin also being inclined to the axis of the drive shaft at an angle substantially equal to the inclination of the piston to said shaft, an oil reservoir formed between the end of the crank pin. crosshead bore, and yoke surface, a crank case for the compressor containing a bath of oil, and porting means formed in the crank pin, crosshead, and yoke adapted upon successive phases of rotative movement of the shaft to admit oil from the crank case to the reservoir and to transfer oil from the reservoir to the bearing.

7. A hermetic refrigerant compressor comprising a casing having a supporting casting therein, a motor mounted on the casting, a bearing formed in the casting and a drive shaft rotatably mounted in the bearing, said drive shaft projecting beyond the bearing at each end thereof and being formed with an oil groove, a cylinder block mounted on the casting and formed with a, cylinder bore, a piston reciprocably mounted in the cylinder bore, a cylindrical yoke connected to the crank end of the piston at right angles thereto, said piston and cylinder bore being inclined to the axis of the drive shaft, a crosshead slidably mounted in the yoke and formed with a diametrical bore, a crank pin formed on one end of the drive shaft and extending beyond the bearing and rotatably mounted in the crosshead bore, a. bath of oil in the casing, an oil duct formed in the crank pin and communicating with the oil groove of the drive shaft, ports formed in the yoke and crosshead adapted to register during one phase of movement of the drive shaft to admit oil from the oil bath to the region between the end of the crank pin, crosshead bore, and yoke, other ports formed in the crank pin and crosshead adapted to place said region in communication with said oil duct during a successive phase of movement, said oil groove extending the full length of the drive shaft and to the opposite end thereof beyond said bearing, whereby oil forced into said groove may be transferred from said opposite end of the shaft to the motor and the casing walls to absorb heat therefrom, and a drain duct in said casting adjacent the crank end of the piston and cylinder block to direct at least a portion of the oil to the piston.

JENS TOUBORG.

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

UNITED STATES PATENTS Number Name Date 1,744,791 Nemetz Jan. 28, 1930 1,814,285 Butler July 14, 1931 2,153,773 Patrignani Apr. 11. 1939 '2,239,723 Limpert et al. Apr. 29, 1941

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