Expansible chamber devices – Relatively movable working members – Interconnected with common rotatable shaft
Reexamination Certificate
2001-02-01
2002-05-14
Ryznic, John E. (Department: 3745)
Expansible chamber devices
Relatively movable working members
Interconnected with common rotatable shaft
C092S172000
Reexamination Certificate
active
06386090
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a compressor for use in an air conditioner for vehicle, especially, a piston type compressor in which the rotation of the piston is prevented.
Conventionally, it is common that a rotation preventing member and the piston are formed integrally. For example, devices in FIG.
7
and FIG.
8
(
a
) are disclosed in Japanese Unexamined Patent Publication No. 11-201037.
A drive shaft
101
is rotatably supported by a housing
102
. A swash plate
13
as a cam plate is coupled with the drive shaft
101
to rotate integrally. A cylinder bore
102
a
is defined in the housing
102
. A head portion
104
a
of a single-headed piston
104
is inserted into the cylinder bore
102
a
. A neck portion
104
b
of the piston
104
is arranged outside of the cylinder bore
102
a
. A pair of shoe seats or semi-spherical recesses
104
c
is inwardly recessed to define pockets in the neck portion
104
b
of the piston
104
. A pair of shoes
105
is arranged in the neck portion
104
b
of the piston
104
, and received by the shoe seats
104
c
. The peripheral portions of the swash plate
103
are slidably sandwiched between the shoes
105
. The rotational movement of the swash plate
103
accompanying with the rotation of the drive shaft
101
is converted to the reciprocating movement of the piston
104
through the shoes
105
. Then the compression cycle is performed such that a refrigerant gas is sucked into the cylinder bore
102
a
, compressed and discharged out.
A piston
104
is provided with a rotation preventing portion
106
. The piston
104
and the rotation preventing portion
106
are formed integrally. The rotation preventing portions
106
are formed on the neck portion
104
b
of the piston
104
so as to protrude ahead and behind in the rotational direction of the swash plate
103
, respectively. The rotation preventing portions
106
are formed such that the curvature of contacting surfaces
106
a
confronting a contacting portion
102
b
of the housing
102
is smaller than that of the head portion
104
a
. An axis of an arc of the rotation preventing portion
106
is different from that of an arc of the head portion
104
a
. The housing
102
and the piston
104
are made of aluminium or an aluminium alloy for reducing its weight. A coating layer is formed on the head portion
104
a
and the contacting surface
106
a
for preventing seizure between the housing
102
and the piston
104
and for improving wearproof of the piston
104
. The contacting portion
102
b
prevents the rotation of the piston, cooperating with the rotation preventing portion
106
.
The connecting structure between the piston
104
and the swash plate
103
through the shoes
105
allows the rotation around the axis S of the piston
104
. If the piston
104
rotates significantly, the neck portion interferes with the rotating swash plate
103
and there is a possibility of causing vibration and noise. However, as shown in FIG.
8
(
a
) as two dotted chain line, the amount of rotation of the piston
104
could be reduced by that one end of the rotation preventing portion
106
contacts with the contacting portion
102
b
. Therefore, the piston
104
does not interfere with the swash plate
103
.
On the other hand, another type of compressor, in which the rotation preventing member and the piston are arranged separately, is disclosed in Japanese Unexamined Patent Publication No. 9-105377.
As shown in FIG.
8
(
b
) and
FIG. 9
, a protruding portion
111
is formed on the end portion of the piston
110
. The intermediate portion of an arched leaf spring
112
is fastened to the protruding portion
111
with a screw
113
. As shown in FIG.
8
(
b
), the leaf spring
112
is assembled such that both end portions
112
a
are pressed to the inner wall surface
114
a
of the cylinder block (housing)
114
, slidably in the moving direction of the piston
110
, respectively.
Generally, a piston is produced by performing machining process, coating process to form a coating layer to cover the surface, and polishing process etc. to the material formed by molding or forging. As the piston
104
disclosed in Japanese Unexamined Patent publication No. 11-201037, it becomes troublesome to machine the piston or form a coating layer on the piston by roll coating, for the rotation preventing portion
106
and the piston
104
are formed integrally and the axis of the arc of the rotation preventing portion
106
deviates from that of the arc of the contacting surface
106
a.
On the other hand, a compressor disclosed in Japanese Unexamined Patent Publication No. 9-105377 has the following problems.
(1) The rotation prevention of the piston
110
is performed by the leaf spring
112
which is continually press-contacted to the inner wall surface
114
a
of the housing
114
, and an unbalanced load is continually affected to a piston
110
from the leaf spring
112
. Therefore, the inner wall surface
114
a
of the housing
114
to which the leaf spring
112
is press-contacted, is easily worn, and then the piston
110
is easily worn partially. To control the amount of rotation of the piston
110
under a required quantity, it needs to strengthen the spring force of the leaf spring
112
. However, that makes the above problem remarkable.
(2) The protruding portion
111
is formed on the end portion of the piston
110
and the leaf spring
112
is fastened to it with the screw
113
. Such a structure axially lengthen the piston
110
and increases the size of the compressor. Furthermore, it needs to machine the screw
113
and a tapped hole
115
, and increases the manufacturing process.
SUMMARY OF THE INVENTION
The present invention was achieved by recognizing the above problems in the prior art. The purpose is to propose a compressor in which the rotation of the piston is prevented without affecting a big unbalanced load to the piston and the manufacture for the piston is simplified.
A piston type compressor comprises a housing having a cylinder bore therein, a drive shaft rotatably supported in the housing, a cam plate coupled on the drive shaft to rotate integrally therewith, a piston being operatively connected to the cam plate through a pair of shoes, the piston including a head portion and a neck portion, the head portion of the piston being inserted into the cylinder bore, and the cam plate converting rotation of the drive shaft to reciprocating movement of the piston through the pair of shoes. In the above compressor, the present invention has the following features. A rotation preventing member is formed separately from the piston and mounted on the piston. A contacting portion is formed in the housing. The rotation preventing member prevents rotation around the axis of the piston, by contacting with the contacting portion when the piston rotates by a certain angle.
According to the present invention, it is easy to machine the piston and to form a coating layer on the piston by roll coating etc., for the rotation preventing member is formed separately from the piston. During the running of the compressor, a moment around the axis of the piston acts to the piston, accompanied with the rotation of the swash plate, and the piston tends to rotate around the axis. However, when the piston rotates by a certain angle from the base portion, the rotation is prevented, for the rotation preventing member contacts the contacting portion. Therefore, the piston slides without receiving an unbalanced load, different from the structure that a leaf spring is used as the rotation preventing member.
Furthermore, the present invention has a following feature. The rotation preventing member is received in the piston. A stopper for preventing the relative movement of the rotation preventing member in the axial direction of the piston is arranged between the rotation preventing member and the piston. Accordingly, even after long use, the rotation preventing member is not separated from the piston by slipping in the axial direction of it.
Furthermore, the present invention has a f
Iwamori Hidekazu
Kato Takayuki
Ohno Tomomi
Yokota Masahiro
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan , LLP
Ryznic John E.
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