WOBBLE PLATE TYPE COMPRESSOR WITH VARIABLE DISPLACEMENT MECHANISM

Abstract: A wobble plate type compressor (1) with a variable displacement mechanism includes a compressor housing (3) which is proveded with a crank chamber (32) and a cylinder block (31) in which a plurality of cylinders (33) are formed. A front end plate (2) is fixed on one end surface of the compressor housing (3). A cylinder head (5) which is provided with a suction chamber (52) and a discharge chamber (53) is fixed on the other end surface thereof. A drive shaft (7) is rotatably supported in the housing (3) and one end of the drive shaft (7) is rotatably supported in a central bore (35) in the cylinder block (31). A rotor (9) is fixed on the drive shaft (7) and is variably connected to an inclined plate (11) through a hinge mechanism. A wobble plate (13) is adjacent to the inclined plate (11) and converts rotary motion of the inclined plate (11) into nutating motion thereof. A plurality of pistons (19) are coupled with the wobble plate (13) through a plurality of connecting rods (18) each of which is reciprocably fitted within a respective one of the cylinders (33) and of which the stroke volume is changed in accordance with variation of the angle of the inclined plate (11). A control valve (60) controls the communication between the crank chamber (32) and the suction chamber (52) through a conduit. The control valve is disposed in the central bore (35). Therefore, the compressor can be easily assembled since the outer shape of the compressor housing is formed cylindrical.

Description: The present invention relates to a wobble plate type compressor with a variable displacement mechanism and more particularly, to a position of a control mechanism for a variable displacement mechanism. A wobble plate type compressor which reciprocates pistons by converting the rotational movement of a cam rotor into nutational movement of a wobble plate is well known in the prior art as shown in disclosed Japanese Patent Application Publication No. 58-158,382. Changing the inclined angle of the wobble plate changes the stroke of the pistons and therefore changes the displacement volume of the cylinders. Referring to Fig. 1 the construction of a conventional wobble plate type compressor is shown. Wobble plate type compressor 1 includes front end plate 2, cylinder casing 3 having cylinder block 31, valve plate 4, and cylinder head 5. Front end plate 2 is fixed on one end of cylinder casing 3 by securing bolts (not shown). Axial hole 21, which is formed through the center of front and plate 2 receives drive shaft 7. Radial bearing 8 is disposed in axial hole 21 to rotatably support drive shaft 7. Annular sleeve portion 22 projects from front end plate 2 and surrounds drive shaft 7, defining a seal cavity. Cylinder casing 3 is provided with cylinder block 31 and crank chamber 32. Cylinder block 31 has a plurality of equiangularly spaced cylinders 33 formed therein. Cam rotor 9 is fixed on drive shaft 7 by pin 103. Thrust needle bearing 10 is disposed between the inner wall surface of front end plate 2 and the adjacent axial end surface of cam rotor 9. First arm portion 91 of cam rotor 9 extends in the direction of cylinder block 31. Elongated hole 92 is formed through third arm portion. Inclined plate 11, which is provided with flange portion 111, fourth arm portion 112 and cylindrical portion 113, is disposed around drive shaft 7. Fourth arm portion 112 is formed on the outer surface of flange portion 111 of inclined plate 11 and faces third arm portion 91 of cam rotor 9. A hole (not shown) which is formed in fourth arm portion 112, is aligned with elongated hole 92. Guide pin 12, which is fixedly disposed through the hole, is slidable movable within elongated hole 92. Ring-shaped wobble plate 13 is mounted on the outer surface of cylindrical portion 113 of inclined plate 11 through radial bearing 14 and is prevented from axial movement by flange portion 111 and snap ring 15 which is disposed on cylindrical portion 113. Wobble plate 13 is also prevented from rotating by guide plate 25 which extends within crank chamber 32. Thrust needle bearing 16 is disposed in a gap between flange portion 111 and wobble plate 13. The other end of drive shaft is rotatably supported through bearing 17 in the central bore 34 of cylinder block 31. One end of piston rod 18 is rotatably connected to receiving surface 131 of wobble plate 13. The other end of piston rod 18 is rotatably connected to piston 19 which is slidably fitted within cylinder 33. Suction ports 41 and discharge ports 42 are formed through valve plate 4. A suction reed valve (not shown) is disposed on valve plate 4. A discharge reed valve (not shown) is disposed on valve plate 4 opposite the suction reed valve. Cylinder head 5 is connected to cylinder casing 3 through gaskets (not shown) and valve plate 4. Partition wall 51 extends axially from the inner surface of cylinder head 5 and divides the interior of cylinder head 5 into suction chamber 52 and discharge chamber 53. Suction chamber 52 is connected to the external fluid circuit through fluid inlet port 54 formed in cylinder head 5. Discharge chamber 53 is connected to the external fluid circuit through fluid outlet port 55 formed in cylinder head 5. Crank chamber 32 of cylinder casing 3 and suction chamber 52 of cylinder head 5 are communicated one another through bypass hole 311 to control the pressure in crank chamber 32 thereby controlling the angle of inclined plate 11 and wobble plate 13. Bypass hole 311, which is formed with cylinder block 31, includes conduit 311a and hollow portion 311b and communicates crank chamber 32 of cylinder casing 3 with suction chamber 52 of cylinder head 5 to introduce the fluid gas in crank chamber 32 to suction chamber 52 responsive to operation of control valve 20. Control valve 20 includes bellows 20a and needle valve 20b. One end of bellows 20a, which is vacuumed, is mounted on a projection which is formed on the inner wall surface of hollow portion 311b and needle valve 20b is fixed on the other end thereof. If the pressure in crank chamber 32 becomes higher than the operating pressure point of bellows 20a, bellows 20a contracts. Thereby needle valve 20b opens hole 43 which is formed through control valve 4. Accordingly, the high pressure gas in crank chamber 32 flows into suction chamber 52, and the pressure of the gas in crank chamber 32 is reduced. Therefore, the angle of inclined plate 11 and wobble plate 13 is increased. Thereby the capacity of the compressor is changed into a large capacity. Contrarily, if the communication between chamber 32 and suction chamber 52 is prevented by closing operation of control valve 20, gas pressure in crank chamber 32 gradually increases, and high gas pressure acts on the rear surface of pistons 19 thereby reducing the angle of inclined plate 11. Thus, the capacity of the compressor is changed into a small capacity. In the above construction of a wobble plate type compressor with a variable displacement mechanism, it is necessary to newly form hollow portion 311 in cylinder block 31 to dispose control valve 20. Furthermore, since hollow portion 311b is formed outside of the circumference of a plurality of cylinders 33, the outer surface of cylinder casing 3 projects in the radial direction as shown in Fig. 2. Alternatively, if hollow portion 311b is formed on the circumference of cylinders 33 to prevent cylinder casing 3 from projectiong, respective cylinder 33 can not be disposed with a regular interval thereby causing to produce pulsation of the gas pressure. Furthermore, if control valve 20 is disposed within a cylinder head, the volume of a suction chamber and a discharge chamber is reduced thereby also increasing pulsation of the gas pressure. It is an object of this invention to provide a wobble plate type compressor with a variable displacement mechanism which can be easily assembled. It is another object of this invention to provide a wobble plate type compressor with a variable displacement mechanism of which the compressor housing can be formed in the shape of a cylinder. A wobble plate type compressor with a variable displacement mechanism according to the present invention includes a compressor housing which is provided with a crank chamber and a cylinder block in which a plurality of cylinders are formed. A front end plate is fixed on one end surface of the compressor housing. A cylinder head which is provided with a suction chamber and a discharge chamber is fixed on the other end surface thereof. A drive shaft is rotatably supported in the housing and one end of the drive shaft is rotatably supported in a central bore in the cylinder block. A rotor is fixed on the drive shaft and is variably connected to an inclined plate through a hinge mechanism. A wobble plate is adjacent the inclined plate and convert rotary motion of the inclined plate into nutating motion thereof. A plurality of pistons are coupled with the wobble plate through a plurality of connecting rods each of which is reciprocably fitted within a respective one of the cylinders and of which the stroke volume is changed in accordance with variation of the angle of the inclined plate. A control valve controls the communication between the crank chamber and the suction chamber through a conduit. The control valve is disposed in the central bore. Further objects, features and other aspects of the invention will be understood from the following description of the preferred embodiments of the invention referring to the attached drawings. Fig. 1 is a cross-sectional view of a conventional wobble plate type compressor with a variable displacement mechanism. Fig. 2 is a cross-sectional view taken along the line A-A shown in Fig. 1. Fig. 3 is a cross-sectional view of another conventional wobble plate type compressor with a variable displacement mechanism. Fig. 4 is a cross-sectional view of a wobble plate type compressor with a variable displacement mechanism in accordance with one embodiment of this invention. Fig. 5 is a cross-sectional view taken along the line B-B shown in Fig. 4. Fig. 6 is a wobble plae type compressor with a variable displacement mechanism in accordance with another embodiment of this invention. Referring to Figs. 4 and 5, the construction of a wobble plate type compressor with a variable displacement mechanism is shown. The same numerals are accorded on the same construction as that shown in Figs. 1 and 2. The description of that construction is omitted to symplify the specification of this invention. Cylinder bore 35 is formed in cylinder block 31 to be defined to first cylinder chamber 351 and second cylinder chamber 352. Those chambers 351 and 352 are communicated through hole 353 each other. One end of drive shaft 7 is rotatably supported with radial bearing 8 which is disposed in axial hole 21 and the other end thereof is also rotatably supported with radial bearing 17 which is disposed in first cylinder chamber 351. Control valve mechanism 60 is fixedly disposed in second cylinder chamber 352 of cylinder bore 35. Control valve mechanism 60 includes cylinder casing 61, bellows 62 and needle valve 63. Hole 61a is formed through the axial end of cylinder casing 3. Partition wall 61b radially extends from the inner surface of cylinder casing 61 and defines the interior of cylinder casing 61 into first casing chamber 610 and second casing chamber 611. Hole 61c is formed through partition wall 61b to communicate first casing chamber 610 with second casing chamber 611. Hole 61d is formed through the cylindrical wall surfaces of cylinder casing 3 to communicate second casing chamber 611 with the exterior of cylinder casing 3. The exterior of cylinder casing 3, which is second cylinder chamber 352, is communicated with suction chamber 52 through conduit 311 and hole 43. Bellows 62 is fixed on a projection, which is formed on one inner wall surface of first casing chamber 610, at one end thereof. Needle valve 63 is fixed on the other end of bellows 62 at the position corresponding to hole 61c. Refrigerant gas flows into cylinder bore 35 through gaps among a plurality of balls of radial bearing 17 as shown by a dotted line. If the pressures of the gas, which flows into first casing chamber 610 through hold 61a, is higher than an operating point of bellows 62, bellows 62 contracts, thereby moving needle valve 63 toward left. Accordingly, the opening of hole 61c is opened, and the gas flows into second casing chamber 611 through hole 61c. The gas in second casing chamber 611 flows out to the exterior of cylinder casing 61 and flows into suction chamber 52 through conduit 311 and hole 43. Therefore, since the pressure of the gas in crank chamber 32 is reduced thereby the angle of inclined plate 11 is increased. Contrarily, if the pressure of the gas in first casing chamber 610 is below the operating point of bellows 62, bellows 62 expands, thereby moving needle valve 63 toward right. Accordingly, the opening of hole 61b is closed by needle valve 63, and thus the gas in crank chamber 32 is prevented from flowing into suction chamber 52. Therefore, the pressure of the gas in crank chamber 32 gradually increases. Referring to Fig. 6, the construction of a wobble plate type compressor with a variable displacement mechanism in accordance with another embodiment of this invention is shown. The interior of cylinder casing 61 is defined by partition wall 61g to first casing chamber 610 and second casing chamber 611. Bellows 62 is fixed on a projection, which is formed on the inner wall surface of first casing chamber 610 at the side of discharge chamber 53, at one end thereof. Needle valve 63 is fixed on the other end surface of bellows 62 and controls the opening and closing of hole 61e of first casing chamber 610. Hole 61f is formed through the cylindrical surface of cylinder casing 3 to communicate first casing chamber 610 with the exterior of cylinder casing 3, which is second cylinder chamber 352. The interior of first casing chamber 610 is communicated with suction chamber 52 through conduit 311 and hole 43. If the pressure of the gas in suction chamber 52 is higher than the operating point of bellows 62, bellows 62 contracts thereby moving needle valve 63 toward right. Accordingly, the opening of hole 61e is opened, and the gas in crank chamber 32 flows into suction chamber 52. Contrarily, if the pressure of the gas in suction chamber 52 is below the operating point of bellows 62, the opening of hole 61e is closed by needle valve 63. Thereby the gas in crank chamber 32 is prevented from flowing into first casing chamber 610. The interior of bellows 62 is vaccumed so that the operation of bellows 62 is not influenced by the temperature of the gas. The communication between first cylinder chamber 351 and a portion of second cylinder 352, which is defined by the outer surface of cylinder casing 3 , is prevented by seal element 64. The present invention has been described in detail in connection with the preferred embodiments, but these are examples only, and the invention is not restricted thereto. It will be easily understood by those skilled in the art that other variations and modifications can be easily made within the scope of this invention.

Claims: 1. In a wobble plate type compressor (1) with a variable displacement mechanism, said compressor (1) including a compressor housing (3) provided with a crank chamber (32) and a cylinder block (31) in which a plurality of cylinders (33) are formed, a front end plate (2) fixed on one end surface of said compressor housing (3), a cylinder head (5) provided with a suction chamber (52) and a discharge chamber (53) fixed on the other end surface thereof, a drive shaft (7) rotatably supported in said housing and one end of said drive shaft (7) rotatably supported in a central bore (35) in said cylinder block (31), a rotor (9) fixed on said drive shaft (7) and variably connected to an inclined plate (11) through a hinge mechanism, a wobble plate (13) adjacent to said inclined plate (11) and converting a rotary motion of said inclined plate (11) into a nutating motion thereof, a plurality of pistons (19) coupled with said wobble plate (13) through a plurality of connecting rods (18) each of which is reciprocably fitted within a respective one of said cylinders (33) and of which the stroke volume is changed in accordance with a variation of the angle of said inclined plate (11), and a control valve (60) controlling the communication between said crank chamber (32) and said suction chamber (52) through a conduit; said control valve (60) is disposed in said central bore (35). 2. The wobble plate type compressor (1) with a variable dis­ placement mechanism of claim 1 wherein said control valve (60) comprises a cylinder casing (61), a bellows (62) which is fixedly disposed on one inner end surface of said cylinder casing (61) at one end surface thereof, and a needle valve (63) which is fixed on the other end surface of said bellows (62). 3. The wobble plate type compressor (1) with a variable displacement mechanism of claim 2 wherein said bellows (62) operates in accordance with the gas pressure in said crank chamber (32) so that said needle valve (63 controls the communication between said crank chamber (32) and said suction chamber (52). 4. The wobble plate type compressor (1) with a variable displacement mechanism of claim 2 wherein said bellows (62) operates in accordance with the gas pressure in said suction chamber (52) so that said needle valve (63) controls the communication between said crank chamber (32) and said suction chamber (52).

Inventors: HIGUCHI, TERUO, KIKUCHI, SEI, TAKAI, KAZUHIKO, TERAUCHI, KIYOSHI
Applicants: SANDEN CORPORATION
Application year: 1988
Main classification: F04B1
IPC codes: F04B27