WOBBLE PLATE COMPRESSOR

Abstract: A compressor (1) has a rotation preventing mechanism (60) for preventing a wobble plate (14) from rotating relatively to a housing (2,3,4,5). The mechanism (60) comprises a guide plate (62) rigidly or pivotably mounted in the housing (2,3,4,5) adjacent to the circumferential edge of the nutating wobble plate (14). Also, the same circumferential edge has a hole (142) in which a cylindrical block (61) is rotatably mounted but prevented from sliding out of the wobble plate (14). The cylindrical block (61) has a transverse groove (611) that slidably receives a free edge of the guide plate (62).

Description: The present invention relates to a wobble plate compressor with a variable displacement mechanism and a rotation-preventing mechanism. A wobble plate 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 art. Changing the inclined angle of the wobble plate changes the stroke of the pistons and therefore changes the displacement volume of the cylinders. In such a compressor, it is necessary to prevent rotation of the wobble plate when the rotational movement of the cam rotor converts into nutational movement of the wobble plate. A rotation-preventing mechanism for the wobble plate is disclosed in JP-81-77578. The rotation-preventing mechanism, which is shown in Fig. 1 of the accompanying drawings, includes a guide bar 100 extending within a crank chamber in a compressor housing. The guide bar 100 is disposed parallel to a drive shaft and passes the circumferential edge of the wobble plate. A hollow bearing 101, which is provided with a spherically-curved surface, is slidably disposed on the guide bar 100. A pair of half-cylindrical shoe members 102, which are slidably disposed within a hole formed on the outer circumference of the wobble plate, are slidably disposed around the hollow bearing 101. When assembling the above rotation-preventing mechanism, it is necessary to assemble the parts in the compressor housing so that the hollow bearing 101 is retained between the shoe members 102 which are slidably disposed within the hole and the hollow bearing 101 is also slidably disposed on the guide bar 100. However, when the parts are assembled, because the shoe members 102 may easily slip out of the hole, the assembly is very difficult and it therefore takes a long time to assemble the rotation-preventing mechanism. It is an object of this invention to provide a wobble plate compressor with a variable displacement mechanism which has a rotation-preventing mechanism that can be assembled easily and in a short time, is of simple construction and is of high durability. Our EP-A-0207613 discloses a wobble plate compressor with a variable displacement mechanism, the compressor comprising a compressor housing provided with a crank chamber and a cylinder block in which a plurality of cylinders are formed; a drive shaft rotatably supported in the housing; a rotor fixed on the drive shaft and connected to a variably inclined plate; a wobble plate adjacent to the inclined plate and arranged to convert rotary motion of the inclined plate into nutating motion thereof; a plurality of pistons coupled with the wobble plate and reciprocably fitted within a respective one of the cylinders; and a rotation-preventing mechanism for preventing the wobble plate from rotating, the rotation-preventing mechanism comprising a guide plate attached to the housing within the crank chamber and a cylindrical block rotatably mounted in a hole formed at the outer circumference of the wobble plate, the cylindrical block being provided with a groove at one end slidably positioned over a free edge of the guide plate; and, according to the invention, such a compressor is characterised by means for retaining the cylindrical block in the hole such that the surface at the inner end of the groove is maintained out of contact with the edge of the guide plate. The invention will now be described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is an exploded perspective view of parts of a conventional rotation-preventing mechanism for a variable displacement compressor; Fig. 2 is a cross-sectional view of a wobble plate compressor with a variable displacement mechanism in accordance with one embodiment of the invention; Fig. 3 is an exploded perspective view of parts of a rotation-preventing mechanism shown in Fig. 2; Fig. 4 (a) is a perspective view of a part shown in Fig. 3; Fig. 4 (b) is a plan of the rotation-preventing mechanism shown in Fig. 2; Fig. 4 (c) is an end view of the rotation-preventing mechanism shown in Fig. 2; Fig. 5 (a) is a perspective view of parts used in a rotation-preventing mechanism in accordance with another embodiment of the invention; Fig. 5 (b) is a plan of the rotation-preventing mechanism incorporating the parts shown in Fig. 5 (a); Fig. 5 (c) is an end view of the rotation-preventing mechanism shown in Fig. 5 (a); Fig. 6 (a) is a perspective view of a part used in a rotation-preventing mechanism in accordance with a further embodiment of the invention; Fig. 6 (b) is a plan of the rotation-preventing mechanism incorporating the part shown in Fig. 6 (a); Fig. 6 (c) is an end view of the rotation-preventing mechanism shown in Fig. 6 (a); Fig. 7 (a) is a plan of a rotation-preventing mechanism in accordance with a further embodiment of the invention; Fig. 7 (b) is a cross-sectional view taken on the line A-A of Fig. 7 (a); Fig. 8 (a) is a perspective view of a part used in a rotation-preventing mechanism in accordance with a further embodiment of the invention; Fig. 8 (b) is a plan of the rotation-preventing mechanism incorporating the part shown in Fig. 8 (a); Fig. 8 (c) is an end view of the rotation-preventing mechanism shown in Fig. 8 (a); Fig. 9 (a) is a perspective view of a part used in a rotation-preventing mechanism in accordance with a further embodiment of the invention; Fig. 9 (b) is a plan of the rotation-preventing mechanism incorporating the part shown in Fig. 9 (a); Fig. 9 (c) is an end view of the rotation-preventing mechanism shown in Fig. 9(a); Fig. 10 (a) is a plan of a modification of the rotation-preventing mechanism shown in Fig. 9 (b); Fig. 10 (b) is an end view of the modification shown in Fig. 10 (a); Fig. 11 (a) is a perspective view of a part used in a rotation-preventing mechanism in accordance with a further embodiment of the invention; Fig. 11 (b) is a plan of the rotation-preventing mechanism incorporating the part shown in Fig. 11 (a); Fig. 11 (c) is an end view of the rotation-preventing mechanism shown in Fig. 11 (a); Fig. 12 is a cross-sectional view of a wobble plate compressor with a variable displacement mechanism in accordance with a further embodiment of the invention; and, Fig. 13 is an exploded perspective view of a rotation-preventing mechanism shown in Fig. 12. Referring to Fig. 2, a wobble plate compressor 1 includes a front end plate 2, a cylinder casing 3 having a cylinder block 31, a valve plate 4, and a cylinder head 5. The front end plate 2 is fixed on one end of the cylinder casing 3 by securing bolts (not shown). An axial hole 21, which is formed through the centre of the front end plate 2, receives a drive shaft 6. A radial bearing 7 is disposed in the axial hole 21 to support rotatably the drive shaft 6. An annular sleeve portion 22 projects from the front end plate 2 and surrounds the drive shaft 6, defining a seal cavity (not shown). The cylinder casing 3 is provided with the cylinder block 31 and a crank chamber 32. The cylinder block 31 has a plurality of equiangularly spaced cylinders 33 formed therein. A cam rotor 10 is fixed on the drive shaft 6 by a pin 103. A thrust needle bearing 11 is disposed between the inner wall surface of the front end plate 2 and the adjacent axial end surface of the cam rotor 10. An arm portion 104 of the cam rotor 10 extends in the direction of the cylinder block 31. An elongate hole 105 is formed in the arm portion 104. An inclinded plate 12, provided with a flange portion 121, a second arm portion 122 and a cylindrical portion 123, is disposed around the drive shaft 6. The second arm portion 122 is formed on the outer surface of the flange portion 121 of the inclined plate 12 and faces the arm portion 104 of the cam rotor 10. A hole (not shown) in the arm portion 122 is aligned with the elongate hole 105. A pin 13, inserted through the hole, is slidably movable within the elongate hole 105. An annular wobble plate 14 is mounted on the outer surface of the cylindrical portion 123 of the inclined plate 12 through a radial bearing 15 and is prevented from moving axially by the flange portion 121 and a snap ring 16 disposed on the cylindrical portion 123. A thrust needle bearing 17 is disposed in a gap between the flange portion 121 and the wobble plate 14. The other end of the drive shaft 6 is rotatably supported through a radial bearing 18 in a central bore of the cylinder block 31. One end of a piston rod 19 is pivotally located in a socket 141 of the wobble plate 14. The other end of the piston rod 19 is pivotally connected to a piston 20 which is slidably fitted in one of the cylinders 33. Suction ports 41 and discharge ports 42 are formed through the valve plate 4. A suction reed valve (not shown) is disposed on the valve plate 4. A discharge reed valve (not shown) is disposed on the valve plate 4 opposite the suction reed valve. The cylinder head 5 is connected to the cylinder casing 3 through gaskets (not shown) and the valve plate 4. A partition wall 51 extends axially from the inner surface of the cylinder head 5 and divides the interior of the cylinder head 5 into a suction chamber 52 and discharge chamber 53. The suction chamber 52 is connected to an external fluid circuit through a fluid inlet port 54 formed in the cylinder head 5. The discharge chamber 53 is connected to the external fluid circuit through a fluid outlet port 55 formed in the cylinder head 5. The crank chamber 32 of the cylinder casing 3 and the suction chamber 52 of the cylinder head 5 are connected to one another through a conduit 311 so as to control the angle of the inclined plate 12 and the wobble plate 14. The conduit 311, which is formed within the cylinder block 31, connects the crank chamber 32 of the cylinder casing 3 and the suction chamber 52 of the cylinder head 5 through a hollow portion 312 which is formed within the cylinder block 31 and a hole 43 which is formed through the valve plate 4. Gas in the crank chamber 32 is able to pass to the suction chamber 52 under the control of a control valve 25 which opens and closes the hole 43 in response to the gas pressure within the crank chamber 32. The angle of the inclined plate 12 and the wobble plate 14 is varied by the pressure of the gas in the crank chamber 32. If there is no communication between the crank chamber 32 and the suction chamber 52, because the control valve 25 has closed the hole 43, then the gas pressure in the crank chamber 32 gradually increases, and high gas pressure acts on the rear surfaces of the pistons 20, thereby reducing the angle of the inclined plate 12. Thus, the capacity of the compressor is changed into a small capacity. On the other hand, if the crank chamber 32 and the suction chamber 52 can communicate with each other via the control valve 25, the gas pressure in the crank chamber 32 will decrease, thereby increasing the angle of the inclined plate 12 and the wobble plate 14. Thus, the capacity of the compressor is changed to a large capacity. A rotation-preventing mechanism 60 for converting the rotational-movement of the inclined plate 12 into nutational movement of the wobble plate 14 is disposed within the crank chamber 32. Referring to Figs. 3, 4 (a), (b) and (c), the construction of the rotation-preventing mechanism 60 is shown. The rotation-preventing mechanism 60 comprises a cylindrical block 61 which is provided with a transverse groove 611 and a guide plate 62 which is formed with an arc 621 on one edge. The cylindrical block 61 is disposed in a hole 142, which is formed in an axially projecting portion 146 on the wobble plate 14, and is held in the hole 142, whilst being rotatable therein, by bending over extended portions 143 of the wobble plate 14. The guide plate 62 extends within the crank chamber 32 parallel to the drive shaft 6. One end of the guide plate 62 is fixedly disposed in a hole 313 which is formed on the inner wall surface of the cylinder block 31 and the other end of the guide plate 62 is fixedly disposed in a hole 23 which is formed on the inner wall surface of the front end plate 2. When assembling the compressor, and more particularly, when assembling the rotation-preventing mechanism, one end of the guide plate 62 is first inserted into the hole 313 of the cylinder block 31. The cylindrical block 61, which is disposed in the hole 142 of the wobble plate 14, is positioned with its groove 611 around the arced edge of the guide plate 62. Once the wobble plate 14 retaining the cylindrical block 61 and the inclined plate 12 are disposed in the compressor housing 3, the other parts are assembled in the compressor housing 3. Finally, the opening of the compressor housing 3 is closed by the front end plate 2 so that the other end of the guide plate 62 is fixedly inserted into the hole 23 in the front end plate 2. Thus, there is no problem of the cylindrical block 61 falling out of the hole 142 during assembly of the compressor. Referring to Figs. 5 (a), (b) and (c), the construction of a rotation-preventing mechanism in accordance with another embodiment of this invention is shown. Most of the compressor is the same as in the previous embodiment and a detailed explanation of the common components is omitted for the sake of clarity. A hole 612 is formed transversely through the cylindrical block 61 adjacent the end remote from the groove 611. A pin 613 is disposed through the hole 612 so as to project out of the ends of the hole. A two-part groove 144 is formed on the inner wall surface of the hole 142 around the circumference thereof to permit the pin 613 to slide therein. Opposed openings 142a and 142b are formed in the inner wall surface of the hole 142. When the cylindrical block 61 is assembled in the hole 142, the cylindrical block 61 is first inserted into the hole 142 so that the ends of the hole 612 are aligned with the openings 142a and 142b. Then, the pin 613 is inserted into the hole 612 and the cylindrical block 61 is rotated so that projecting portions 613a and 613b of the pin 613 engage the groove 144. In this way, the cylindrical block 61 is retained in the hole 142 so as to be rotatable but not axially movable. Referring to Figs. 6 (a), (b) and (c), the construction of a rotation-preventing mechanism in accordance with a further embodiment of the invention is shown. An annular groove 614 is formed adjacent the end remote from the groove 611 and around the outer circumference of the cylindrical block 61. After the cylindrical block 61 has been inserted in the hole 142, a pair of pins (not shown) are inserted into respective radial holes 615, extending through the wobble plate 14 from the interior of the hole 142, until they project into the groove 614. Thus, the pins prevent the cylindrical block 61 from moving axially. Referring to Figs. 7 (a) and (b), a modification of the rotation-preventing mechanism shown in Figs. 6 (a)-(c) is shown. The cylindrical block 61, which is provided with the annular groove 614 around the outer circumference thereof, is inserted into the hole 142. A lower end portion 171a of the thrust race 171 of the thrust bearing 17 adjacent to the wobble plate 14 is bent toward the cylinder block 31 and extends into the annular groove 614 through the opening 142b formed in the hole 142. Accordingly, the cylindrical block 61 is prevented from moving axially by the lower end portion 171a. Referring to Figs. 8 (a),(b) and (c), the construction of a rotation-preventing mechanism in accordance with a further embodiment of this invention is shown. The cylindrical block 61 is provided with a pair of planar surfaces 616 and 617 at opposite ends of the transverse groove 611. Flange portions 142c are formed around the open end of the hole 142 except at the openings 142a and 142b and extend radially inwards of the hole 142. The dimensions a of at least one of the openings 142a and 142b is greater than the thickness of the cylindrical block 61 between its planar surfaces 616 and 617. During assembly, the cylindrical block 61 is inserted into the hole 142 through one of the openings 142a and 142b, with each planar surface 616 and 617 facing a flange portion 142c. Then, the cylindrical block 61 is rotated until the planar surfaces 616 and 617 are perpendicular to the guide plate 62 and the block is located behind the flange portions 142c. Thus, the cylindrical block 61 is prevented from moving axially by the flange portions 142c. Referring to Figs. 9 (a), (b) and (c), the construction of a rotation-preventing mechanism in accordance with a further embodiment of this invention is shown. The cylindrical block 61 is provided with a pin 618 at the end remote from the groove 611. When the cylindrical block 61 is inserted into the hole 142, the free end of the pin 618 projects out of the wobble plate 14 through a hole 145 which is formed in the projecting portion 146. The cylindrical block 61 is retained in the hole 142 by flattening the free end of the pin 618. Referring to Figs. 10 (a) and (b), a modification of the construction shown in Figs. 9 (a)-(c) is shown. The cylindrical block 61 is retained in the hole 142 by a snap ring 70 instead of by flattening the free end of the pin 618. Referring to Figs. 11 (a), (b) and (c), the construction of a rotation-preventing mechanism in accordance with a further embodiment of this invention is shown. The cylindrical block 61 is provided with a hole 619 which is formed between the bottom of the transverse groove 611 and the end of the block remote from the groove 611. A pin 80, which is provided with an end flange portion 801, is inserted into the hole 619 and the hole 145. The cylindrical block 61 is retained in hole 142 by flattening the projecting end of the pin 80. Referring to Figs. 12 and 13, the construction of a rotation-preventing mechanism in accordance with a further embodiment of this invention is shown. The cylindrical block 61 is rotatably mounted in the hole 142. A circular disc 37, which is provided with an elongate slot 371 at one end thereof, is rotatably mounted in a hole 24 formed in the inner wall of the front end plate 2. A circular disc 38, which is provided with an elongate slot 381 at one end thereof, is rotatably mounted in a hole 314 formed in the inner wall of the cylinder block 31. The guide plate 62 extends within the crank chamber 32; one end of the guide plate 62 is located in the elongate slot 371 formed in the circular disc 37 and the other end of the guide plate 62 is located in the elongate slot 381 formed in the circular disc 38. Thus, even if the plane of the guide plate 62 is not aligned with the centres of the wobble plate 14 and the cylindrical block 61, the guide plate 62 rotates until this is so and thus the cylindrical block 61 is prevented from eccentrically contacting the sides of the guide plate 62. Therefore, the cylindrical block 61 does not wear unevenly, thereby improving the durability of the rotation-preventing mechanism.

Claims: 1. A wobble plate compressor (1) with a variable displacement mechanism, the compressor (1) comprising a compressor housing (2, 3, 4, 5) provided with a crank chamber (32) and a cylinder block (31) in which a plurality of cylinders (33) are formed; a drive shaft (6) rotatably supported in the housing (2, 3, 4, 5); a rotor (10) fixed on the drive shaft (6) and connected to a variably inclined plate (12); a wobble plate (14) adjacent to the inclined plate (12) and arranged to convert rotary motion of the inclined plate (12) into nutating motion thereof; a plurality of pistons (20) coupled with the wobble plate (14) and reciprocably fitted within a respective one of the cylinders (33); and a rotation-preventing mechanism (60) for preventing the wobble plate (14) from rotating, the rotation-preventing mechanism (60) comprising a guide plate (62) attached to the housing (2, 3, 4, 5) within the crank chamber (32) and a cylindrical block (61) rotatably mounted in a hole (142) formed at the outer circumference of the wobble plate (14), but prevented from slidiny axially out of the wobble plate (14) the cylindrical block (61) being provided with a groove (611) at one end slidably positioned over a free edge of the guide plate (62) characterised by means for retaining the cylindrical block (61) in the hole (42) such that the surface at the inner end of the groove is maintained out of contact with the edge of the guide plate (62). 2. A wobble plate compressor (1) according to claim 1, whrein the cylindrical block (61) is retained in the hole (142) by bent over extended portions (143) at the open end of the hole (142). 3. A wobble plate compressor (1) according to claim 1, wherein the cylindrical block (61) is provided with a transverse hole (612), the hole (142) is provided with grooving (144) around its circumference and a pin (613) is located in the transverse hole (612) so as to project into the grooving (144) and prevent the cylindrical block (61) from sliding axially out of the wobble plate (14). 4. A wobble plate compressor (1) according to claim 1, whrein the cylindrical block (61) is provided with an annular groove (614) around its outer circumference, the wobble plate (14) is provided with a second hole (615) communicating with the hole (142) and a pin is located in the second hole (615) so as to project into the groove (614) and prevent the cylindrical block (61) from sliding axially out of the wobble plate (14). 5. A wobble plate compressor (1) according to claim 1, wherein the cylindrical block (61) is provided with an annular groove (614) around its outer circumference, and a thrust race (171) of a thrust bearing (17) supporting the wobble plate (14) on the inclined plate (12) is provided with a portion (171a) extending into the groove (614) so as to prevent the cylindrical block (61) from sliding axially out of the wobble plate (14). 6. A wobble plate compressor (1) according to claim 1, wherein the cylindrical block (61) is provided with a pair of planar surfaces (161, 617) at the opposite ends of the transverse groove (611) and the wobble plate (14) is provided with a pair of openings (142a, 142b) into the side of the hole (142) and the width (a) of at least one of the openings (142a, 142b) is greater than the thickness of the cylindrical block (61). 7. A wobble plate compressor (1) according to claim 1, wherein the cylindrical block (61) is provided with a projection (618) at the end remote from the groove (611) and the wobble plate (14) is provided with a third hole (145) communicating with the bottom of the hole (142) and in which the projection (618) is located with its free end projecting out of the third hole (145) and flattened to prevent the cylindrical block (61) from sliding axially out of the wobble plate (14). 8. A wobble plate compressor (1) according to claim 7, wherein axial sliding of the cylindrical block (61) out of the wobble plate (14) is prevented by a snap ring (70) on the free end of the projection (618) instead of by flattening of the free end. 9. A wobble plate compressor (1) according to claim 1 wherein the cylindrical block (61) is provided with a fourth axial hole (619) at the bottom of the transverse groove (611), the wobble plate (14) is provided with a fifth hole (145) communicating with the bottom of the hole (142), and a pin (80) passes through the fourth (619) and fifth (145) holes so as to prevent the cylindrical block (61) from sliding axially out of the wobble plate (14). 10. A wobble plate compressor (1) according to any of the preceding claims, wherein the rotation preventing mechanism (60) further comprises a pair of circular discs (37, 38) each of which is rotatably mounted in a respective hole (24, 314) formed in the inner wall of a front end plate (2) of the compressor housing (2, 3, 4, 5) and in the cylinder block (31) and the guide plate (62) has its ends located in the discs (37, 38) for rotation therewith. 11. A wobble plate compressor according to claim 10, wherein each circular disc (37, 38) is provided with an elongate slot (371, 381) for receiving the respective end of the guide plate (62).

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