VARIABLE DISPLACEMENT COMPRESSOR

Abstract

A variable displacement compressor including a rotary shaft, a swash plate, and a rotary support is disclosed. An inclination angle of the swash plate is changed so that the displacement of the compressor is controlled. The rotary support has a first balance weight and an arm. The swash plate has a second balance weight and a support bracket. At least one of the first balance weight, the second balance weight, the arm, and the support bracket has a slope on a leading side in the rotation direction of the rotary shaft. The slope has a leading end. The slope is shaped to descend in the direction of the rotation axis toward the leading end.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2007-062027 filed on Mar. 12, 2007 and Japanese Patent Application No. 2008-059227 filed on Mar. 10, 2008, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a variable displacement compressor, in which the pressure in a control pressure chamber accommodating a swash plate is adjusted to control the inclination angle of the swash plate so that the displacement is controlled.

BACKGROUND OF THE INVENTION

Such a variable displacement compressor is disclosed in Japanese Laid-Open Patent Publication No. 2005-23849. A swash plate is tiltably accommodated in a crank chamber (control pressure chamber). The control pressure chamber is supplied with refrigerant of a discharge chamber (discharge pressure zone), and the refrigerant in the crank chamber is discharged to a suction pressure zone, so that the pressure in the crank chamber is adjusted. When the pressure in the crank chamber increases, the inclination angle of the swash plate decreases. This decreases the displacement. When the pressure in the crank chamber decreases, the inclination angle of the swash plate increases. This increases the displacement.

To lubricate parts in the crank chamber that need lubrication (for example, sliding portions of the swash plate and shoes), lubricant is provided in the crank chamber. Lubricant stored in a bottom portion of the crank chamber is sheared (agitated) by a thrust flange (rotary support), which rotates integrally with the rotary shaft, and the swash plate, which splashes the lubricant. The splashed lubricant lubricates the parts that need lubrication in the crank chamber.

The swash plate is linked to the thrust flange by means of a link mechanism, which rotates integrally with the thrust flange. To improve the balance of rotation of the thrust flange and the swash plate, a counterweight (balance weight) that corresponds to the link mechanism is provided to the thrust flange or the swash plate. The thrust flange and the swash plate shear lubricant stored in the bottom portion of the crank chamber. However, if a great rotational resistance is generated when the counterweight and the link mechanism shear the lubricant, the temperature of the lubricant is excessively raised. This can degrade the lubrication performance of the lubricant. Also, the greater the rotational resistance, the greater the power loss becomes.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to suppress rotational resistance generated as lubricant in a control pressure chamber is sheared by rotation of a rotary support or a swash plate in a variable displacement compressor.

To achieve the foregoing objective and in accordance with a first aspect of the present invention, a variable displacement compressor having a swash plate tiltably accommodated in a control pressure chamber is provided. Refrigerant is supplied from a discharge pressure zone to the control pressure chamber, and is discharged therefrom to a suction pressure zone, so that the pressure in the control pressure chamber is adjusted to change an inclination angle of the swash plate, so that the displacement is controlled. The compressor includes a rotary shaft having a rotation axis, a rotary support that rotates integrally with the rotary shaft, a link mechanism, a first balance weight, and a second balance weight. The link mechanism links the swash plate to the rotary support such that the inclination angle of the swash plate is changeable. The link mechanism includes a first appendage attached to the rotary support and a second appendage attached to the swash plate. The first balance weight is provided on the rotary support and corresponds to the link mechanism. The second balance weight is provided on the swash plate and corresponds to the link mechanism. At least one of the first balance weight, the second balance weight, the first appendage, and the second appendage has a slope on a leading side in the rotation direction of the rotary shaft. The slope has a leading end in the rotation direction and is shaped to descend in the direction of the rotation axis toward the leading end.

In accordance with a second aspect of the present invention, a variable displacement compressor having a swash plate tiltably accommodated in a control pressure chamber is provided. Refrigerant is supplied from a discharge pressure zone to the control pressure chamber, and is discharged therefrom to a suction pressure zone, so that the pressure in the control pressure chamber is adjusted to change an inclination angle of the swash plate, so that the displacement is controlled. The compressor includes a rotary shaft having a rotation axis, a rotary support that rotates integrally with the rotary shaft, a link mechanism, a first balance weight, and a second balance weight. The link mechanism links the swash plate to the rotary support such that the inclination angle of the swash plate is changeable. The link mechanism includes a first appendage attached to the rotary support and a second appendage attached to the swash plate. The first balance weight is provided on the rotary support and corresponds to the link mechanism. The second balance weight is provided on the swash plate and corresponds to the link mechanism. At least one of the first balance weight, the second balance weight, the first appendage, and the second appendage has a step on a leading side in the rotation direction of the rotary shaft, and the step is covered with a cover so as to suppress rotational resistance generated as the lubricant in the control pressure chamber is sheared by rotation of the rotary support or the swash plate.

In accordance with a third aspect of the present invention, a variable displacement compressor having a swash plate tiltably accommodated in a control pressure chamber is provided. Refrigerant is supplied from a discharge pressure zone to the control pressure chamber, and is discharged therefrom to a suction pressure zone, so that the pressure in the control pressure chamber is adjusted to change an inclination angle of the swash plate, so that the displacement is controlled. The compressor includes a rotary shaft having a rotation axis, a rotary support that rotates integrally with the rotary shaft, a link mechanism, a first balance weight, and a second balance weight. The link mechanism links the swash plate to the rotary support such that the inclination angle of the swash plate is changeable. The link mechanism includes a first appendage attached to the rotary support and a second appendage attached to the swash plate. When at least one of the rotary support and the swash plate is defined as a body of revolution, the body of revolution having on a surface of a part of the body of revolution except a portion on which the appendage is formed, a plane of rotation that is formed all around the rotation axis. A recess is formed in the plane of rotation, and wherein the recess is located on the same side as the appendage with respect to the axis.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1A is a cress-sectional side view showing a whole variable displacement compressor according to a first embodiment of the present invention;

FIG. 1B is a perspective view illustrating the rotary support of FIG. 1A;

FIG. 2A is a cross-sectional view taken along line 2A-2A of FIG. 1A;

FIG. 2B is a cross-sectional view taken along line 2B-2B of FIG. 2A;

FIG. 2C is a cross-sectional view taken along line 2C-2C of FIG. 2A;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1A;

FIGS. 4A and 4B are perspective views each illustrating a rotary support according to a second embodiment of the present invention;

FIG. 5A is a partial cross-sectional side view illustrating a variable displacement compressor according to a third embodiment of the present invention;

FIG. 5B is a cross-sectional view taken along line 5B-5B of FIG. 5A;

FIG. 6A is a perspective view illustrating the rotary support of FIG. 5B;

FIGS. 6B and 6C are perspective views each showing the cover of FIG. 6A;

FIG. 7A is a side cross-sectional view showing a rotary support of a variable displacement compressor according to a fourth embodiment of the present invention;

FIG. 7B is a perspective view illustrating the ring of FIG. 7A;

FIG. 7C is a perspective view illustrating the rotary support of FIG. 7A;

FIG. 8 is a partial cross-sectional side view illustrating a variable displacement compressor according to a fifth embodiment of the present invention;

FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 8;

FIG. 10A is a front view illustrating a swash plate according to another embodiment of the present invention; and

FIG. 10B is a rear view illustrating a swash plate according to another embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

A first embodiment of the present invention will now be described with reference to FIGS. 1A to 3.

As shown in FIG. 1A, a front housing member 12 is coupled to the front end of a cylinder 11. A rear housing member 13 is coupled to the rear end of the cylinder 11. The cylinder 11, the front housing member 12, and the rear housing member 13 form a whole housing of a variable displacement compressor 10. The front housing member 12 and the cylinder 11 define a control pressure chamber 121, and rotatably support a rotary shaft 14. The rotary shaft 14 projects from the control pressure chamber 121 to the outside, and receives power from an external power source (for example, a vehicle engine).

A rotary support 17 is fixed to the rotary shaft 14, and a swash plate 18 is supported on the rotary shaft 14. The swash plate 18 is permitted to slide in a direction of a rotation axis 141 of the rotary shaft 14 and to incline with respect to the rotary shaft 14.

As shown in FIG. 2A, an arm 19 is integrally formed with the rotary support 17 on a surface 171 opposed to the swash plate 18. A pair of guide holes 191, 192 are formed in the arm 19.

As shown in FIG. 3, a pair of support brackets 20 and a balance weight 34 are integrally formed with the swash plate 18 on a surface 181 opposed to the rotary support 17. A guide pin 21 is fixed to each support bracket 20. Each of the guide holes 191, 192 slidably receives the corresponding one of the guide pins 21. The engagement of the guide holes 191, 192 with the guide pins 21 allows the swash plate 18 to move along the rotation axis 141 of the rotary shaft 14 while being inclined, and to rotate integrally with the rotary shaft 14. The swash plate 18 is inclined by sliding the guide pins 21 with respect to the guide holes 191, 192, and sliding the swash plate 18 with respect to the rotary shaft 14.

The arm 19, the guide holes 191, 192, the support brackets 20, and the guide pins 21 form a link mechanism 22. The link mechanism 22 links the swash plate 18 to the rotary support 17, which rotates integrally with the rotary shaft 14, in such a manner that the inclination angle of the swash plate 18 is changeable. The arm 19 is an appendage attached to the rotary support 17 included in the link mechanism 22. The support brackets 20 and the guide pins 21 are appendages attached to the swash plate 18 included in the link mechanism 22.

When a radial center portion of the swash plate 10 moves toward the rotary support 17, the inclination of the swash plate 18 increases. The maximum inclination angle of the swash plate 18 is defined by the contact between the rotary support 17 and the swash plate 18. When in a position indicated by solid lines in FIG. 1A, the swash plate 18 is at the maximum inclination position. When in a position indicated by chain lines, the swash plate 18 is at the minimum inclination position.

As shown in FIG. 1A, cylinder bores 111 are formed in and extend through the cylinder 11. A piston 23 is retained in each cylinder bore 111. The rotation of the swash plate 18 is converted to reciprocation of the pistons 23 by means of shoes 24. Thus, each piston 23 reciprocates in the corresponding cylinder bore 111.

A suction chamber 131 and a discharge chamber 132 are defined in the rear housing member 13. As each piston 23 moves from the top dead center to the bottom dead center (from the right side to the left side in FIG. 1A), refrigerant in the suction chamber 131, which is a suction pressure zone, is drawn into the associated cylinder bore 111 through a suction port 15 while flexing a suction valve flap 151. When each piston 23 moves from the bottom dead center to the top dead center (from the left side to the right side in FIG. 1A), gaseous refrigerant in the corresponding cylinder bore 111 is discharged to the discharge chamber 132 through a discharge port 16 while flexing a discharge valve flap 161.

Refrigerant that is discharged to the discharge chamber 132, which is a discharge pressure zone, flows out to an external refrigerant circuit (not shown) located outside of the compressor 10. After being discharged to the external refrigerant circuit, the refrigerant is returned to the suction chamber 131.

The discharge chamber 132 is connected to the control pressure chamber 121 by a supply passage 25. The control pressure chamber 121 is connected td the scion chamber 131 by a release passage 26. Refrigerant in the control pressure chamber 121 flows to the suction chamber 131 through the 35 release passage 26. An electromagnetic displacement control valve 27 is installed in the rear housing member 13. The electromagnetic displacement control valve 27 regulates the flow passage area of the supply passage 25. When the opening degree of the electromagnetic displacement control valve 27 is increased, the flow passage area of the supply passage 25 is increased. This increases the amount of refrigerant supplied from the discharge chamber 132 to the suction chamber 131, thereby increasing the pressure in the control pressure chamber 121. Accordingly, the inclination angle of the swash plate 18 is reduced. When the opening degree of the electromagnetic displacement control valve 27 is decreased, the flow passage area of the supply passage 25 is decreased. This reduces the amount of refrigerant supplied from the discharge chamber 132 to the suction chamber 131, thereby lowering the pressure in the control pressure chamber 121. Accordingly, the inclination angle of the swash plate 18 is increased.

As shown in FIG. 1B, the balance weight 28 is integrally formed on the opposed surface 171 of the rotary support 17. To improve the rotation balance of the rotary support 17, the balance weight 28 is located in an opposite side of the arm 19 with respect to the rotation axis 141. The balance weight 28 is formed as a projection having a shape of a circular arc about the rotation axis 141. Each of an outer peripheral surface 282 and an inner peripheral surface 283 of the balance weight 28 is a part of an imaginary circumferential surface about the rotation axis 141. The outer peripheral surface 282 and the inner peripheral surface 283 are planes of rotation created by rotation trajectories when lines parallel to the rotation axis 141 are rotated about the rotation axis 141. No step is formed in the outer peripheral surface 282 or the inner peripheral surface 283 along the circumferential direction.

An outer peripheral surface 174 of the rotary support 17 is a circumferential surface about the rotation axis 141. The radius of the outer peripheral surface 174 is substantially equal to the radius of the cuter peripheral surface 282. The outer peripheral surface 174 is a plane of rotation created by rotation trajectory when a line parallel to the rotation axis 141 is rotated about the rotation axis 141. No step is formed in the outer peripheral surface 174 along the circumferential direction.

The rotary support 17 rotates about the rotation axis 141 in a rotation direction indicated by arrow R. A step of the balance weight 28 on a leading side in the rotation direction R of the rotary support 17 forms a slope 281. The leading side has a leading end. As shown in FIG. 2B, the slope 281 is shaped to descend in the direction of the rotation axis 141 toward the opposed surface 171 in the rotation direction R. In other words, the slope 281 is shaped to descend in the direction of the rotation axis 141 toward the leading end.

As shown in FIG. 2A, the arm 19 is substantially shaped like a circular arc projection about the rotation axis 141. An outer peripheral surface 194 of the arm 19 is a part of an imaginary circumferential surface about the rotation axis 141. The outer peripheral surface 194 is a plane of rotation created by rotation trajectory when a line parallel to the rotation axis 141 is rotated about the rotation axis 141. No step is formed in the outer peripheral surface 194 along the circumferential direction.

As shown in FIG. 2C, a step of the arm 19 on a leading side in the rotation direction R of the rotary support 17 forms a slope 193. The leading side has a leading end. The slope 193 is shaped to descend in the direction of the rotation axis 141 toward the opposed surface 171 in the rotation direction R. In other words, the slope 193 is shaped to descend in the direction of the rotation axis 141 toward the leading end.

As shown in FIG. 3, lubricant Y is stored in the control pressure chamber 121. When the rotary support 17 and the swash plate 18 rotate, the lubricant Y stored in a bottom portion of the control pressure chamber 121 is sheared and splashed so that the lubricant Y lubricates parts in the control pressure chamber 121 that need lubrication.

The first embodiment provides the following advantages.

(1) When the rotary support 17 rotates, the slopes 193, 281 pushes through the lubricant Y stored in the bottom portion of the control pressure chamber 121. Therefore, the rotational resistance generated when the lubricant Y in the control pressure chamber 121 is sheared as the rotary support 17 rotates is suppressed. As a result, the temperature increase of the lubricant Y and the power loss are suppressed.

(2) The slopes 193, 281 are easily formed as a simple structure for suppressing rotational resistance generated when the lubricant Y in the control pressure chamber 121 is sheared.

(3) Each of the outer peripheral surface 282 and the inner peripheral surface 283 of the balance weight 28 is a part of the imaginary circumferential surface about the rotation axis 141. Thus, both the shearing resistance between the lubricant Y in the control pressure chamber 121 and the outer peripheral surface 282 and the shearing resistance between the lubricant Y and the inner peripheral surface 283 are significantly small. Therefore, the structure of the outer peripheral surface 282 and the inner peripheral surface 283 of the balance weight 28 according to the present embodiment contributes to the suppression of the rotational resistance generated when the lubricant Y in the control pressure chamber 121 is sheared.

(4) The outer peripheral surface 194 of the arm 19 is a part of the imaginary circumferential surface about the rotation axis 141. Thus, the shearing resistance between the lubricant Y in the control pressure chamber 121 and the outer peripheral surface 194 is significantly small. Therefore, the structure of the outer peripheral surface 194 of the arm 19 contributes to the suppression of the rotational resistance generated when the lubricant Y in the control pressure chamber 121 is sheared.

(5) The outer peripheral surface 174 of the rotary support 17 is a circumferential surface about the rotation axis 141. Thus, the shearing resistance between the lubricant Y in the control pressure chamber 121 and the outer peripheral surface 174 is significantly small. Therefore, the structure of the outer peripheral surface 174 of the rotary support 17 contributes to the suppression of the rotational resistance generated when the lubricant Y in the control pressure chamber 121 is sheared.

A second embodiment will now be described with reference to FIG. 4. Same reference numerals are used for those components which are the same as the corresponding components of the first embodiment.

As shown in FIG. 4A, an outer peripheral surface 174 of a rotary support 17 is a circumferential surface about a rotation axis 141. An arc 19 is formed on an opposite surface 171 of the rotary support 17. As shown in FIG. 4B, a surface of the rotary support 17 that is opposite to the surface on which an arm 19 is formed (the opposed surface 171 shown in FIG. 4A) is referred to as a back surface 172. The back surface 172 is perpendicular to the rotation axis 141. The back surface 172 is a surface of a part of the rotary support 17 except a portion on which the arm 19, which is an appendage of the rotary support 17, is formed. The back surface 172 is also a plane created by rotation trajectory when a Line perpendicular to the rotation axis 141 is rotated about the rotation axis 141. That is, the back surface 172 is a plane of rotation formed all around the rotation axis 141.

Recesses 173 are formed in the back surface 172. The recesses 173 are located on the same side as the arm 19 with respect to the rotation axis 141. A portion opposite to the arm 19 with respect to the rotation axis 141 is solid. This structure offers a disk-shaped outer peripheral shape that has no step intersecting the circumferential direction, and a function of a balance weight. This improves the rotation balance of the rotary support 17.

If no recesses 173 are provided in the back surface 172, no step is provided in any given circumferential section spaced from the rotation axis 141 by a constant distance. The recesses 173 create steps on the back surface 172, which is a 25 plane of rotation. However, since the recesses 173 are formed by recessing the back surface 172, the rotational resistance at the recesses 173 generated when lubricant is sheared by the rotary support 17 is smaller than the rotational resistance generated at a projection formed on a plane of rotation. The recesses 173 in she flat back surface 172 are easily formed. The recesses 173 formed in the back surface 172, which is a plane of rotation, has a simple structure as a rotational resistance suppressing portion that suppresses rotational resistance related to lubricant.

The second embodiment has the same advantage as the advantage (5) of the first embodiment.

A third embodiment will now be described with reference to FIGS. 5A to 6C. Same reference numerals are used for those components which are the same as the corresponding components of the first embodiment.

As shown in FIG. 5A, an arm 19A is integrally formed with a rotary support 17A on an opposed surface 171. A guide hole 195 is formed in the arm 19A. A pair of support brackets 29 are attached to an opposed surface 181 of a swash plate 18. As shown in FIG. 5B, a guide pin 30 extends between and is supported by the support brackets 29. The guide pin 30 is fitted in the guide hole 195. The arm 19A, the guide hole 195, the support brackets 29, and the guide pin 30 form a link mechanism 22A. The link mechanism 22A links the swash plate 18 to the rotary support 17A, which rotates integrally with the rotary shaft 14, in such a manner that the inclination angle of the swash plate 18 is changeable. The arm 19A is an appendage attached to the rotary support 17A included in the link mechanism 22A. The support brackets 29 and the guide pin 30 are appendages attached to the swash plate 18 included in the link mechanism 22A.

As shown in FIG. 6A, a balance weight 28A is formed on the rotary support 17A. The balance weight 28A is formed as a circular arc about the rotation axis 141. The radius of an outer peripheral surface 282 of the balance weight 28A is greater than the radius of the cuter peripheral surface 175 of the rotary support 17A. A rotational resistance suppressing cover 31 made of synthetic resin is attached to the outer periphery of the rotary support 17A on the same side as the arm 19A with respect to the rotation axis 141. The rotational resistance suppressing cover 31 is attached to the rotary support 17A, for example, by adhesive.

As shown in FIGS. 6B and 6C, the rotational resistance suppressing cover 31 is substantially formed as a circular arc. An outer peripheral surface 311 of the rotational resistance suppressing cover 31 is a part of an imaginary circumferential surface having the same radius as the outer peripheral surface 282 of the balance weight 28A. The outer peripheral surface 311 and the cuter peripheral surface 282 are planes of rotation created by rotation trajectories when lines parallel to the rotation axis 141 are rotated about the rotation axis 141. The outer peripheral surface 311 of the rotational resistance suppressing cover 31 attached to the rotary support 17A smoothly continuous to the outer peripheral surface 282 of the balance weight 28A. That is, the outer peripheral surface 282 of the balance weight 28A and the outer peripheral surface 311 of the rotational resistance suppressing cover 31 each form a plane of rotation that is formed all around the rotation axis 141. No step is formed in the outer peripheral surface 311 or the outer peripheral surface 282 along the circumferential direction.

A front surface 312 of the rotational resistance suppressing cover 31 is flat and attached to the rotary support 17A. Also, the front surface 312 is flush with a flat front surface 286 of the balance weight 28A.

The rotational resistance suppressing cover 31 covers the step between the outer peripheral surface 282 of the balance weight 28A and outer peripheral surface 175 of the rotary support 17A, and the step between the front surface 286 of the balance weight 28A and the opposed surface 171 of the rotary support 17A. That is, the rotational resistance suppressing cover 31 covers an end face 284, which is a step of the balance weight 28A, and an end face 285, which is a step of an leading end portion of the balance weight 28A in the rotation direction R. Thus, the rotational resistance generated as lubricant is sheared by the rotary support 17A is suppressed.

A fourth embodiment will now be described with reference to FIGS. 7A to 7C. Same reference numerals are used for those components which are the same as the corresponding components of the third embodiment.

As shown in FIG. 7C, an outer peripheral surface 174 of a rotary support 17B is a circumferential surface about the rotation axis 141. The radius of an outer peripheral surface 282 of a balance weight 28B is equal to the radius of the cuter peripheral surface 174 of the rotary support 17B.

As shown in FIG. 7A, a metal ring 32 shown in FIG. 7B is press fitted to the outer peripheral surface 174 of the rotary support 17B and the outer peripheral surface 282 of the balance weight 28B. The ring 32, which is a rotational resistance suppressing cover, covers the outer peripheral surface 174 of the rotary support 17B and the outer peripheral surface 282 of the balance weight 28B, and end faces (steps) 287, 288 of the balance weight 28B are located inside the ring 32. An outer peripheral surface 321 of the ring 32 is a circumferential surface about the rotation axis 141. The outer peripheral surface 321 is a plane of rotation created by rotation trajectory when a line parallel to the rotation axis 141 is rotated about the rotation axis 141. No step is formed in the outer peripheral surface 321 along the circumferential direction.

The structure in which the end faces 287, 288 of the balance weight 28B are located inside the ring 32 generates 35 less rotational resistance due to shearing of lubricant by the rotary support 17B compared to a structure in which the end faces 287, 288 of the balance weight 28B are located outside of the ring 32.

The fourth embodiment has the same advantage as the advantage (5) of the first embodiment.

A fifth embodiment will now be described with reference to FIGS. 8 and 9. Same reference numerals are used for those components which are the same as the corresponding components of the first embodiment.

As shown in FIG. 8, a base plate 33 is fixed to the opposed surface 181 of the swash plate 18. As shown in FIG. 9, a balance weight 34A and a pair of support brackets are formed integrally on a surface of the base plate 33 that is opposed to the rotary support 17. The balance weight 34A is formed as a circular. A synthetic resin cover 35 is fixed to the opposed surface 331 of the base plate 33.

As shown in FIG. 8, a recess 36 is formed on a contact surface 332 of the base plate 33 that contacts the opposed surface 181 of the swash plate 18. The recess 36 faces the support brackets 20. A recess 37, which faces the recess 36, is formed in the opposed surface 181 of the swash plate 18. The recesses 36, 37 reduce the size (weight) of the balance weight 34A.

The cover 35, which is a rotational resistance suppressing cover, covers most of the opposed surface 331 of the base plate 33, and an outer peripheral surface 351 of the cover 35 is a circumferential surface about the rotation axis 141. The height of the cover 35 is substantially equal to the height of the balance weight 34A, and most of the balance weight 34A and many portions of the support brackets 20 are located inside the cover 35. Rotational resistance in this structure due to shearing of lubricant is less than that in a structure without the cover 35.

It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms.

As shown in FIG. 10A, each support bracket 20 of the swash plate 18 may form a slope 203 similarly to the slope 193 provided on the arm 19 of the rotary support 17 shown in FIG. 2. Also, a slope 341 may be provided on the balance weight 34 of the swash plate 18 as shown in FIG. 10A similarly to the slope 281 provided on the balance weight 28 of the rotary support 17 shown in FIG. 2.

As shown in FIG. 10B, recesses 183 may be provided on the back surface 182 of the swash plate 18 similarly to the recesses 173 provided on the back surface 172 of the rotary support 17 shown in FIG. 4B.

In the third embodiment, the rotary support 17A may be placed in the mold for molding the rotational resistance suppressing cover 31, so that the rotational resistance suppressing cover 31 is formed through insert molding. In this case, the rotary support 17A is fixed to the rotational resistance suppressing cover 31 at the same time as the molding of the rotary support 17A, which facilitates the manufacture.

In the third embodiment, the rotational resistance suppressing cover 31 may be integrally formed with the rotary support 17A as a single member. Specifically, the rotational resistance suppressing cover 31, the arm 19A as the appendage, and the balance weight 28A are integrally formed with the rotary support 17A. Such configuration allows the strength of the arm 19A to be easily increased and facilitates the manufacture of the rotary support 17A.

The rotational resistance suppressing cover 31 may have any structure as long as it covers steps, thereby reducing the steps.

The outer peripheral surface 174 of the rotary support 17 may be a conical plane of rotation or a plane of rotation created by rotation trajectory when a curve is rotated about the rotation axis 141.

The outer peripheral surface 321 of the ring 32 may be a conical plane of rotation or a plane of rotation created by rotation trajectory when a curve is rotated about the rotation axis 141.

The present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

Claims

1. A variable displacement compressor comprising a swash plate tiltably accommodated in a control pressure chamber, wherein refrigerant is supplied from a discharge pressure zone to the control pressure chamber, and is discharged therefrom to a suction pressure zone, so that the pressure in the control pressure chamber is adjusted to change an inclination angle of the swash plate, so that the displacement is controlled, the compressor comprising: a rotary shaft having a rotation axis;a rotary support that rotates integrally with the rotary shaft;a link mechanism that links the swash platy to the rotary support such that the inclination angle of the swash plate is changeable, wherein the link mechanism includes a first appendage attached to the rotary support and a second appendage attached to the swash plate;a first balance weight that is provided on the rotary support and corresponds to the link mechanism; anda second balance weight that is provided on the swash plate and corresponds to the link mechanism,wherein at least one of the first balance weight, the second balance weight, the first appendage, and the second appendage has a slope on a leading side in the rotation direction of the rotary shaft, the slope having a leading end in the rotation direction, and wherein the slope is shaped to descend in the direction of the rotation axes toward the leading end.

2. A variable displacement compressor comprising a swash plate tiltably accommodated in a control pressure chamber, wherein refrigerant is supplied from a discharge pressure zone to the control pressure chamber, and is discharged therefrom to a suction pressure zone, so that the pressure in the control pressure chamber is adjusted to change an inclination angle of the swash plate, so that the displacement is controlled, the compressor comprising: a rotary shaft having a rotation axis;a rotary support that rotates integrally with the rotary shaft;a link mechanism that links the swash plate to the rotary support such that the inclination angle of the swash plate is changeable, wherein the link mechanism includes a first appendage attached to the rotary support and a second appendage attached to the swash plate;a first balance weight that is provided on the rotary support and corresponds to the link mechanism; anda second balance weight that is provided on the swash plate and corresponds to the link mechanism,wherein at least one of the first balance weight, the second balance weight, the first appendage, and the second appendage has a step on a leading side in the rotation direction of the rotary shaft, and the step is covered with a cover so as to suppress rotational resistance generated as the lubricant in the control pressure chamber is sheared by rotation of the rotary support or the swash plate.

3. The compressor according to claim 2, wherein the rotational resistance suppressing cover as a ring that covers an outer periphery of the rotary support.

4. The compressor according to claim 3, wherein an outer peripheral surface of the ring is a plane of rotation about the rotation axis.

5. The compressor according to claim 2, wherein the rotational resistance suppressing cover is formed of a resin through insert molding.

6. The compressor according to claim 2, wherein the rotational resistance suppression cover covers the outer peripheral surface of the rotary support such that an outer peripheral surfaces of the balance weights and the outer peripheral surface of the cover form a plane of rotation that is formed all around the rotation axis.

7. A variable displacement compressor comprising a swash plate tiltably accommodated in a control pressure chamber, wherein refrigerant is supplied from a discharge pressure zone to the control pressure chamber, and is discharged therefrom to a suction pressure zone, so that the pressure in the control pressure chamber is adjusted to change an inclination angle of the swash plate, so that the displacement is controlled, the compressor comprising: a rotary shaft having a rotation axis;a rotary support that rotates integrally with the rotary shaft; anda link mechanism that links the swash plate to the rotary support such that the inclination angle of the swash plate is changeable, wherein the link mechanism includes a first appendage attached to the rotary support and a second appendage attached to the swash plate,wherein, when at least one of the rotary support and the swash plate is defined as a body of revolution, the body of revolution having, on a surface of a part of the body of revolution except a portion on which the appendage is formed, a plane of rotation that is formed all around the rotation axis, wherein a recess is formed in the plane of rotation, and wherein the recess is located on the same side as the appendage with respect to the axis.

8. The compressor according to claim 7, wherein the rotary support has an opposed surface that is opposed to the swash plate, and the plane of rotation is a back surface that is on an opposite side of the opposed surface.

9. The compressor according to claim 1, wherein the cuter peripheral surface of the rotary support is a plane of rotation about the rotation axis.