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Variable displacement compressor

Variable displacement compressor description/claims

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.

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.

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.

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.

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;

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