Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2002-10-30
2004-09-07
Yu, Justine R. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C417S222100, C417S269000, C092S071000
Reexamination Certificate
active
06786704
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a compressor for a fluid such as a refrigerant compressor used in a refrigeration cycle of an air-conditioning system mounted in a vehicle.
2. Description of the Related Art
There are two leading types of conventional drive plate (or swash plate) type piston compressors. One type takes out reciprocating motion directly to a piston by bringing two semispherical shoes attached to the end of the piston into direct frictional contact with the front and rear surfaces of a drive plate attached to a shaft in a tilted state and engaging in rotary motion and rocking motion. The problem with a compressor of this type is that at the time of high speed rotation of the compressor, the relative sliding speed between the drive plate and the shoes becomes large, so under operating conditions where the supply of lubrication oil becomes insufficient, the lubrication state between the drive plate and shoes becomes poor and seizing or other trouble easily occurs. Further, since the drive plate and the shoes engage in frictional contact, there is also the problem of a large mechanical loss compared with rolling contact.
The other type changes the large frictional sliding contact between the drive plate and shoes to rolling contact to reduce the mechanical loss etc. One example is described in Japanese Unexamined Patent Publication (Kokai) No. 2001-123945.
In this type, one end of each piston has attached to it shoes able to freely tilt with respect to an axis of the piston. Further, a thrust needle bearing is interposed between the shoes and the drive plate so that the sliding contact parts become rolling contact parts. These constituent elements enable a compression operation pushing the piston into the cylinder bore to compress the fluid, but do not enable a suction operation of pulling the piston out from the cylinder bore to suck the fluid. The reason is that the thrust needle bearing can support a compressive load in the axial direction, but cannot transmit or support a tensile load.
Therefore, the compressor described in the above-mentioned Japanese Unexamined Patent Publication (Kokai) No. 2001-123945 is configured to enable a suction operation by providing a rocking member engaging with and holding the shoes attached to the end of a piston with a suitable clearance and a slider slidably engaging with the shaft in the axial direction, by connecting the rocking member and slider by a roller bearing, and by biasing the slider toward the drive plate by a coil spring. The compressor of this example is a fixed capacity type, but even if making the tilt angle of the drive plate variable to try to remodel the compressor to a variable capacity type, with this configuration, it is impossible to change the tilt angle of the rocking member engaged with and holding the shoes, so this compressor cannot be made a variable capacity type.
Further, in this example, in the same way as the structure in general use in a conventional compressor of this type, the shaft passes through the center of the drive plate and the rocking member (shoe holding plate) driven by this through a bearing and extends to the inside of the cylinder block, so a bearing is provided inside the cylinder block to support the front end of the shaft. In this case, while there is nothing which has to be driven by the shaft other than the drive plate, since the shaft passes through the rocking member etc. and extends to the cylinder block at the rear, there is the problem that the compressor as a whole becomes larger than necessary.
Further examples of the conventional compressor are shown in Japanese Unexamined Patent Publication (Kokai) No. 7-19164 and Japanese Unexamined Patent Publication (Kokai) No. 2001-234857. One structure is illustrated in FIG.
38
. These compressors fall under the category of drive plate type (or swash plate type) piston type variable capacity compressors. The housing forming the shell is comprised of three parts—front housing
1
, a cylinder block
2
, and a rear housing
3
—joined by means such as not shown through bolts. Pistons
7
are inserted into the plurality of cylinder bores
21
formed in the center cylinder block
2
and are forced to engage in reciprocating motion by a common drive plate (swash plate)
5
through shoes
8
. The drive plate
5
is driven to rotate by a long shaft
4
passing through its center and extending to the center of the cylinder block
2
. The front end of the shaft
4
is axially supported by a bearing
64
provided in the cylinder block
2
.
In the operating state, due to the rocking motion of the drive plate
5
rotating together with the shaft
4
, the pistons
7
engage in reciprocating motion in their cylinder bores
21
to expand and compress working chambers
21
a
and thereby cause a fluid such as a refrigerant to pass through a suction valve
13
and be sucked into the working chambers
21
a
from a suction chamber
31
formed at the center of the rear housing
3
so as to be compressed, then pass through a discharge valve
11
and be discharged into a large volume discharge chamber
32
formed at the outer periphery of the rear housing
3
. This compressor enables the tilt angle of the drive plate
5
to be smoothly changed, so enables the discharge capacity to be continuously changed.
In a compressor of the type causing pistons to engage in reciprocating motion to compress a fluid, both the suction operation from the suction chamber
31
to the working chambers
21
a
and the discharge operation of the fluid compressed in the working chambers
21
a
to the discharge chamber
32
are performed intermittently, so pressure fluctuations (pulsation) of the fluid occur in the suction chamber
21
and the discharge chamber
32
. Due to this, sometimes vibration or a groaning-like noise occurs, so to suppress pressure fluctuations in the suction chamber
31
and discharge chamber
32
and smooth the flow of fluid into the compressor and the flow of fluid out of it, the conventional compressor has been designed to make the capacity of the suction chamber or discharge chamber as large as possible. Therefore, by common sense, enlargement of the drive plate type compressor as a whole by the amount of increase of capacity of the suction chamber and discharge chamber as a measure for preventing vibration and noise is an unavoidable problem.
Still another example of a conventional compressor is described in Japanese Unexamined Patent Publication (Kokai) No. 2000-18172. The structure of this compressor as a whole is shown in
FIG. 44
, which part of it, that is, the part of the capacity control valve, is shown in FIG.
45
. This compressor falls under the category of a drive plate type variable capacity compressor. The housing forming the shell is comprised of three parts—a front housing
1
, a cylinder block
2
, and a rear housing
3
—joined by through bolts
40
. Pistons
7
are inserted into a plurality of cylinder bores
21
formed in the center cylinder block
2
and are forced to engage in reciprocating motion by a common drive plate
5
through shoes
8
. The drive plate
8
is driven to rotate by a long shaft passing through its center and extending to the center of the cylinder block
2
. The front end of the shaft
4
is axially supported by a bearing
64
provided in the cylinder block
2
.
In the operating state, due to the rocking motion of the drive plate
5
rotating together with the shaft
4
, the plurality of pistons
7
engage in reciprocating motion in their cylinder bores
21
to expand and compress working chambers
21
a
and thereby cause a fluid such as a refrigerant to pass through a suction valve and be sucked into the working chambers formed at the top faces of the pistons in the cylinder bores
21
from a suction chamber
31
formed at the outer periphery of the rear housing
3
so as to be compressed, then pass through a discharge valve and be discharged into a discharge chamber
32
formed at the center of the rear housing
3
. This compressor enables the tilt an
Inoue Masafumi
Inoue Takashi
Kamiya Hirokazu
Kamiya Shigeru
Matsuda Mikio
Denso Corporation
Posz & Bethards, PLC
Solak Timothy P.
Yu Justine R.
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