US 2968961 A
Description (OCR text may contain errors)
Jan. 24, 1961 R. MGGREGOR 2,968,961
REFRIGERATING APPARATUS Filed Feb.r 13, 1957 5 sheets-sheet 1 Il fl H/S ATTORNEY Jan- 24, 1961 R. MCGREGOR 2,968,961
REFRIGERATING APPARATUS Filed Feb. 13, 1957 5 Sheets-Sheet 2 Y W, MMS' n H/S ATTORNEY Jan. 24, 1961 R. MGGREGOR REFRIGERATING APPARATUS 3 Sheets-Sheet' Filed Feb. 13, 1957 f .n Aw/ .JDNA m m Tw m W.. .w n@ .../1. [WM FM United States Patent REFRIGERATING APPARATUS Ralph McGregor, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Feb. 13, 1957, Ser. No. 640,025
1 Claim. (Cl. 74--60) This invention relates to refrigerating apparatus and more particularly to a sealed motor-compressor unit.
It is an object of this invention to provide a simple and inexpensive motor-compressor unit in which a multiple cylinder axial compressor or pump is directly connected to a motor.
Still another object of this invention is to provide an improved combination and arrangement of parts wherein a lubricant pump is disposed directly between the main bearing and the wobble plate of an axial compressor.
Still another object of this invention is to provide an improved arrangement for modulating the output of the compressor by adjusting the angle of the wobble plate.
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.
In the drawings:
Figure l is a vertical sectional view of a motor-compressor unit constructed in accordance with the invention;
Figure 2 is a fragmentary sectional view taken substantially on line 2-2 of Figure l and showing the relationship of the parts of the wobble plate angle adjusting means at maximum compressor capacity;
Figure 3 is a view similar to Figure 2 but showing the relationship of the parts at less than maximum capacity;
Figure 4 is a view similar to Figures 2 and 3 and is taken on line 4--4 of Figure 5 but showing the relationship of the parts at minimum capacity;
Figure 5 is a fragmentary sectional view showing the angular relationship of the wobble plate to the drive shaft at reduced compressor capacity;
Figure 6 is a sectional view taken substantially on line 6--6 of Figure l;
Figure 7 is a fragmentary sectional view taken substantially on line 7-7 of Figure 4;
Figure 8 is a fragmentary sectional View taken suby stantially on line 8 8 of Figure l;
Figure 9 is a fragmentary sectional view taken substantially on line 9-9 of Figure l() and shows a modified wobble plate construction; and
Figure l0 is a fragmentary sectional View showing the relationship of the parts when the modified construction shown in Figure 9 is operated at zero capacity.
Referring now to the drawings, wherein a preferred embodiment of the invention has been shown, reference numeral 10 designates an outer sheet metal cylindrical casing or housing for the motor-compressor assembly. The motor-compressor assembly comprises a supporting frame and bearing element 12 which is disposed intermediate the ends of the casing 10 and abuts an internal shoulder 14 provided on the casing 10. The element 12 includes a main bearing boss 16 which projects into the central opening of the motor stator 20 and serves to support the main drive shaft 18. The motor stator 20 has its one end arranged to abut the casting 12 and has its ceN other end abutting against a corrugated spring washerlike strip 22 which is held in place by the end cap assembly 24. The motor includes a motor rotor 26 which is keyed to the main drive shaft 18 and serves to operate the drive shaft whenever the motor is energized.
The compressor is of the multiple cylinder axial type which includes a wobble plate assembly comprising a first bearing portion 30 secured to the drive shaft 18 so as to rotate in unison with the drive shaft and forming an offset crank portion on which a second hub like portion 32 is shiftable or rotatable so as to change the angle of the wobble plate socket element 34 in a manner to be explained more fully hereinafter.
A cast cylinder block 36 is provided as shown in which a plurality of cylinder bores 38 are provided. Piston means 40 operate within the bores and are adapted to be driven by the wobble plate assembly by means of the usual connecting rods 42. For purposes of illustration there has been shown a compressor in which there are ve cylinders, whereas the number of cylinders may be varied without departing from the spirit of the invention. A valve plate assembly 44 is held against the end of the cylinder block 36 by means of the cylinder head assembly 46. The cylinder head assembly includes a suc tion or inlet chamber 48 and a discharge chamber 5t). As shown in Figure l each compression chamber cornmunicates with the suction chamber 4S through a port such as the port 52 shown in Figure l. A reed valve plate 54 controls the ow of refrigerant through the suction port in accordance with standard practice. For a more detailed description of the valve plate reference is hereby made to copending application S.N. 430,768, filed May 19, 1954, now Patent No. 2,825,499. The compressed refrigerant leaves each compression chamber through a discharge port such as the port 56 shown in Figure l. There is provided a reed valve 58 at each discharge port in accordance with standard practice. A needle-type bearing assembly 60 is provided as shown for supporting the end of the main drive shaft in the cylinder block 36. In accordance with conventional practice, the cylinder block 36 includes the usual integrally formed shoe guides 62 which cooperate with a shoe 64 projecting from one side of the wobble plate element 34 so as to prevent rotation of the wobble plate element 34 without preventing angular movement of the wobble plate relative to the drive shaft. The construction of the compression cylinders, the pistons, and the inlet and outlet ports is conventional and needs no further description.
In many types of refrigerating systems it is desirable to provide means for modulating the output of the compressor without changing the speed of operation of the driving motor or other power source. The output of an axial type compressor can very effectively be varied by changing the angle of the wobble plate so as to vary the head clearance. In the particular wobble plate assembly shown, the head clearance can be varied by shifting the Wedge shaped element 32 relative to the element 30 in a manner to be explained hereinafter. Figure 2 shows the relative location of the parts when the compressor is operating at maximum capacity at which time no clearance is provided between the pistons 40 and the cylinder head at the end of the compression strokes.
Figure 5 shows the angular relationship which exists after the element 32 has been rotated relative to the element 30 so as to reduce the angle of tilt of the wobble plate socket element 34. It will be noted that the central aperture in the element 32 is arranged at an angle relative to its outer periphery on which the wobble plate element 34 is mounted whereby relative rotation between the elements 30 and 32 causes a change in the angle between the wobble plate 34 and the central axis of the drive shaft 18. With the angular relationship shown in Figure 5 the pistons will not move to the end of the compression chamber at any time, with the result that the capacity of the compressor will be materially reduced. The amount of `reduction in capacity will be determined by the amount of relative rotation between `the parts 30 and 32. Figure 10 shows an arrangement in which the elements 30 and 32 'have been shifted throughout a 180 angle so that the wobble plate socket element 34 is, in effect, perpendicular to the axis of the drive shaft 18, with the result that the compressor will have zero capacity due to the fact that the elements 30 and 32 canl operate at high speed without causing the element 34 to wobble.
The elements 30 and 32 are held in spaced relationship by means of a pair of ring like elements 70 and 71 which are secured to the element 30 and which cooperate with the elements 30 and 32 to form therebetween oil chamber means into which oil under pressuremay be supplied by means of an oil pump to be described hereinafter.
The element 30 has secured thereto (see Figures 2, 3 and 4) a pair of blocks 72 which divide the oil chamber means into a pair of semicircular chambers and the element 32 has secured thereto a pair of similar blocks 74 which become in effect piston elements operating within the semicircular oil chambers. Oil under pressure is adapted to be supplied to each of the semicircular'oil chambers through a pair of ports 76 so as to force the blocks 72 and 74 to move from the relative position in which they are shown in Figure 4 to a position such as that shown in Figures 3 or 2. v By controlling the amount of oil under pressure supplied through the passages 76 into the space between adjacent blocks 72 and 74 it is possible to vary the amount of relative rotation between the elements 30 and 32 so as to thereby vary the effective angle of the wobble plate 34 relative to the axis of rotation of the main drive shaft 18.
The oil which is used for adjusting the compressor capacity is supplied by means of a conventional gear type oil pump which includes the usual pumping gears 80 and 82 which operate within a pumping chamber 84 which is provided in one side of the main bearing 16 as shown in Figure l. The pumping gears 80 and 82V are held in place within the chamber 84 by means of a plate member 86 which forms the end thrust bearing surface for the member 30 as Well as forming one wall of the pumping chamber 84. The oil enters the pumping chamber through suitable oil feed aperture means-90 provided in the frame element 12 and which leads from the lower part of the motor compressor housingfto the pumping chamber 84 best shown in dotted lines in Figure l. Oil under pressure is supplied from theV gear pump to the oil feed passages 88 formed in the shaft 18 and is also supplied to a passage 92 which communicates with the oil passages 76. The oil pump has more than enough capacity to supply oil under pressure to the oil feed passages 88, 92 and 76 and the surplus oil is adapted to flow through passage means 94 which lead to a control valve 96. The outlet of the valve 96 returns the oil t0 the bottom of the casing through the line 98. When the valve 96 is fully open, the oil pressure supplied to the semicircular oil chambers formed between the elements 30 and 32 is not enough to hold the wobble plate adjusting means in the position in which they are shown in Figure 2. By closing or partially closingthe valve 96 it is possible to build up the oil pressure to the point where it will move the elements'72 and 76 from the position in which they are shown in Figure 4 to some such position as that shown in Figures 2 or 3. Drain or .pressure relief holes 77 are provided at the one end of each semicircular chamber for the purpose of relieving the pressure at the one end of the piston like elements 74. Whereas Figures 2, 3 and 4 show arrangements in which there are two blocks 72 andv two blocks 74 it is within the purview of this invention to substitute only one block for each pair of blocks as shown in Figure 9. The single blocks have beenrdesignated by the reference numerals 72a and 74a. Except for the difference in construction of the blocks 72 and 74 the rest of the structure of the motor-compressor unit is the same in both instances.
In the arrangements shown herein, the application of oil pressure to the pistons in the semicircular oil chambers serves to decrease the output of the compressor and conversely a decrease in oil pressure serves to increase the compressor output as the parts tend to return to the position of maximum output of their own accord when the oil pressure in the semicircular chamber is decreased by opening the valve 96. It is, however, within the purview of this invention to so arrange the parts that it is possible to use oil pressure to shift the parts so as to increase the output of the, compressor and then let a decrease in oil pressuredecrvease the output. Y
The compressor is especially well suited for use in refrigerating systems and when used in such a system the relatively cold suction gas is introduced into the casing 10 through an inlet 100 so as to cool the motor and deposit any entrained oil into the lower portion of the casing 10 and is then withdrawn from the main casing 10 through an outlet 102. The inlet 104 serves to admit the refrigerant to be compressed into the cylinder head 46. The compressed gas leaves through the outlet 106.
While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claim which follows.
What is claimed is as follows: i
In combination, a drive shaft having an offset crank portion thereon, an end thrust bearing adjacent said offset crank portion and abutted thereby, driving means mounted on said crank portion, said driving means comprising a wobble plate and a wedge-shaped element rotatably supported on the offset part of said crank portion, rings disposed one within the other in spaced apartV concentric lrelationship and secured to said crank portion for rotation therewith about the axis of said offset part thereof, said wedge-shaped element engaging an edge of each of the rings and forming therewith and with said crank portion a chamber between said rings, piston means within said chamber one secured to said offset crank portion and the other secured to said wedge-shaped element, said piston means-being adapted to beV moved relative to one another forrshifting said wedge-shaped element about said offset part of said crank portion to change the angle of disposition of said wobble plate with respect to said drive shaft, an oil pump at the side of said thrust bearing opposite the side thereof abutted by said offset crank portion and operated by said shaft, and said bearing and said offset crank portion each being provided withra passage communicating with the outlet of said pump and with said chamber to cause said relative movement of said piston means in response to oil pressure developed by the pump.
References Cited in the file of this patent Y UNITED STATES PATENTS Dean Sept. '17, 1895 Great Britain ..-,July '13, 1936