The present invention relates to a variable displacement inclined plate type compressor, and specifically, to improvement of the structure of the engaging portion between the inclined plate and the shoe.
As a variable displacement compressor provided in a refrigeration cycle, etc., an inclined plate type compressor, for example, a variable displacement inclined plate type compressor added with a clutchless function is known. This variable displacement inclined plate type compressor is formed, for example, as depicted in
In the above-described variable displacement inclined plate type compressor, because the inclination angle of inclined plate 3 becomes almost zero degree when the displacement is minimum and the stroke of piston 8 also becomes almost zero, the inertial resistance and the sliding resistance of the piston approaches zero as much as possible. On the contrary, shoe 7 always slides relatively to inclined plate 3, and it is known that the power consumption due to the viscosity resistance of lubricating oil.
In order to improve the lubricating performance on the sliding surface of the inclined plate, a structure is known wherein a plurality of grooves extending in the radial direction of the inclined plate are provided on the inclined plate, in particular, on the sliding surface with the shoe (Patent document 1). In this structure, however, a gap between the shoe and the inclined plate may discontinuously vary by the grooves extending in the radial direction of the inclined plate, and at worst, the shoe may float relative to the inclined plate. As the result, the operation of the piston may become unstable, and the property and reliability of the compressor may be reduced.
Patent document 1: JP-A-8-159024
Accordingly, an object of the present invention is to provide a variable displacement inclined plate type compressor which can reduce its power consumption particularly at the time of minimum displacement operation without damaging reliability.
To achieve the above-described object, a variable displacement inclined plate type compressor according to the present invention comprises a spindle, an inclined plate provided to be inclinable relative to the spindle and rotating together with the spindle, a pair of shoes arranged to hold the inclined plate therebetween, and a piston coupled with the inclined plate through the pair of shoes, wherein a quantity of stroke of the piston is determined depending on an inclination angle of the inclined plate, and the compressor is characterized in that the compressor has a groove in a sliding surface of the inclined plate with which a planar part of the shoe comes into contact, and the groove is formed such that a contact area of the shoe and the sliding surface of the inclined plate when the inclination angle of the inclined plate is minimum becomes smaller than a contact area of the shoe and the sliding surface of the inclined plate when the inclination angle of the inclined plate is maximum.
The above-described groove may comprise a plurality of annular grooves whose centers are set at a center of the inclined plate. Although the plurality of annular grooves can be formed as grooves having widths different from each other, from the viewpoint of facilitating the processing, it is preferable to form grooves having a same width. Particularly in such a case where grooves having a same width are formed, it is preferred that the plurality of annular grooves are formed so that a width between grooves in a radially outer part of the inclined plate becomes larger than a width between grooves in a radially inner part of the inclined plate.
The widths between grooves may be increased stepwise in a radially outward direction of the inclined plate, or the widths between grooves may be increased continuously (that is, in order) in the radially outward direction of the inclined plate.
Further, it is possible to form the above-described plurality of annular grooves over substantially the entire region of the sliding surface of the inclined plate with the shoe, and as shown in the embodiment described later, it is also possible to form the above-described plurality of annular grooves only in a region positioned at a side of the center of the inclined plate.
Such a variable displacement inclined plate type compressor according to the present invention is suitable particularly as a compressor used in a refrigeration cycle of an air conditioning system for vehicles, which requires durability, etc.
In the variable displacement inclined plate type compressor according to the present invention, since the contact area between the planar part of the shoe and the inclined plate becomes large at the time of maximum displacement and the contact area between the planar part of the shoe and the inclined plate becomes small at the time of minimum displacement, the power consumption at the time of minimum displacement can be reduced without increasing the contact pressure between the shoe and the inclined plate applied at the time of maximum displacement. Further, by forming the grooves as the annular grooves, because the gap between the shoe and the inclined plate can be maintained to be always constant without causing such a problem as aforementioned as to Patent document 1, the shoe is not floated, and the property and reliability of the compressor may be ensured.
Hereinafter, desirable embodiments of the present invention will be explained referring to figures.
The basic structure of a variable displacement inclined plate type compressor is the same as that which has been depicted in
Further, in this embodiment, the widths of the plurality of grooves 22 are identical to each other (the sectional shapes of the grooves are identical to each other), thereby facilitating the processing. In order to achieve the structure wherein the contact area of shoe 7 and sliding surface 3a of inclined plate 3 when the inclination angle of inclined plate 3 is minimum becomes smaller than the contact area of shoe 7 and sliding surface 3a of inclined plate 3 when the inclination angle of inclined plate 3 is maximum, the widths between respective grooves 22 are changed. Namely, the plurality of annular grooves 22 are formed so that a width between grooves W2 in the radially outer part of inclined plate 3 becomes larger than a width between grooves W1 in the radially inner part of inclined plate 3. In this embodiment, the widths between grooves are increased stepwise in a radially outward direction of inclined plate 3. Therefore, as depicted in
It is not always necessary to form the forming region for the plurality of grooves 22 over the entire area of sliding surface 3a of inclined plate 3 with shoe 7. The loci due to the relative movement of shoe to inclined plate 3 become, for example, as shown in
As is understood from
Further, because these first region 23 and second region are formed by annular grooves 22, when shoe 7 slides relative to inclined plate 3 along the locus shown in
The structure of the compressor according to the present invention can be applied to any variable displacement inclined plate type compressor, and in particular, it is suitable for a variable displacement inclined plate type compressor used in a refrigeration cycle of an air conditioning system for vehicles.
Number | Date | Country | Kind |
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2006014741 | Jan 2006 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2007/050203 | 1/11/2007 | WO | 00 | 7/22/2008 |