Piston type compressor

Pumps – With muffler acting on pump fluid

Reexamination Certificate

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Details

C092S071000, C417S269000

Reexamination Certificate

active

06293768

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a piston type compressor that is used for a car air conditioner, for example, and compresses a refrigerant gas by the reciprocating motion of pistons.
2. Description of the Related Art
A double-headed piston-type compressor shown in
FIGS. 6 and 7
of the accompanying drawings is known as a compressor of this kind.
A pair of cylinder blocks
101
and
102
are mutually joined and fixed at their opposed end portions as shown in
FIG. 6. A
front housing
103
is joined and fixed to the end portion of the cylinder block
101
on the front side (on the left side in the drawing). A rear housing
104
is joined and fixed to the end portion of the cylinder block
102
on the rear side (on the right side in the drawing). A drive shaft
105
is rotatably supported in such a fashion as to extend from the cylinder blocks
101
and
102
to the front housing
103
. A plurality of cylinder bores
106
are formed round the axis L of the drive shaft
105
in each cylinder block
101
,
102
. A double-headed-type piston
107
is accommodated in each cylinder bore
106
and is connected to the drive shaft
105
through a swash plate
108
.
A suction chamber
109
is defined on the outer peripheral side of each of the housings
103
and
104
as shown in
FIG. 7. A
discharge chamber
110
is defined on the inner peripheral side of the suction chamber
109
in each of the housings
103
and
104
. Though
FIG. 7
shows the rear housing (
104
) side, the construction is substantially similar on the front housing (
103
) side, too.
Turning back again to
FIG. 6
, a valve/port-forming member
111
is clamped between each of the cylinder blocks
101
,
102
and each of the housings
103
,
104
. The valve/port-forming member
111
has a suction port
112
and a suction valve
113
that are interposed between each cylinder bore
106
and the suction chamber
109
, and a discharge port
114
and a discharge valve
115
that are interposed between each cylinder bore
106
and a discharge chamber
110
, respectively. A plurality of discharge valves
115
are so formed as to extend in a radial direction (in the direction of the corresponding discharge port
114
) from the outer edge portion of a disc-like substrate
116
(see FIG.
7
).
The rotational motion of the drive shaft
105
is converted to the reciprocating motion of the piston
107
through the swash plate
108
. In consequence, a series of compression cycles of suction of the refrigerant gas of the suction chamber
109
into the cylinder bores
106
through the suction port
112
and the suction valve
113
, compression of the refrigerant gas that is sucked, and discharge of the compressed refrigerant gas to the discharge chamber
110
through the discharge port
114
and the discharge valve
115
are repeatedly carried out. The refrigerant gas discharged to the discharge chamber
110
is exhausted to an external refrigerating circuit.
Inside each housing
103
,
104
, the retaining portion
117
comprises a ring-like wall body, as shown in
FIG. 7
, and is formed in such a fashion as to extend into the discharge chamber
110
. The retaining portion
117
retains a ring-like area in the center portion of the valve/port-forming member
111
by its distal end surface
117
a
(FIG.
6
). The valve/port-forming member
111
comprises a laminate of a plurality of sheet materials, and its outer peripheral side is clamped directly by the cylinder block
101
,
102
and the housing
103
,
104
. If this retaining portion
117
is not disposed, the center portion of the valve/port-forming member
111
, that corresponds to a large space (discharge chamber
110
) in a direction orthogonal to the axis L of the drive shaft
105
, cannot be directly clamped by the cylinder block
101
,
102
and the housing
103
,
104
. In consequence, each sheet-like member is likely to float up on the center side. Particularly because the substrate
116
, that functions as the base portion for allowing the discharge valve
115
to undergo deformation as a reed valve, cannot be retained under a suitable condition inside the valve/port-forming body
111
, deformation of the discharge valve
115
does not occur in a stable way.
The piston type compressor having the construction described above is not free from the problem of vibration and noise that occur in the piping arrangement of the external refrigerating circuit due to pressure pulsation of the discharge refrigerant gas. A muffler chamber
118
is formed in an outer profile portion of the cylinder block
101
,
102
to solve this problem. The discharge refrigerant gases from the front and rear side discharge chambers
110
join each other in the muffler chamber
118
. The muffler chamber
118
exhibits its muffler function to damp the pressure pulsation and then discharges the gas to the external refrigerating circuit. To improve the effect of damping the pressure pulsation of the discharge refrigerant gas, the capacity of the muffler chamber
118
must be increased, resulting in an increase in the size of the compressor.
Considering specifically the retaining portion
117
of the rear housing
104
, a space
119
exists inside the retaining portion
117
. To reduce an increase in the weight of the compressor, this space
119
is formed as the retaining portion
117
and is shaped in the ring-like form to correspond to only the outer peripheral portion of the substrate
116
. In other words, as the necessity for providing the retaining portion
117
is not very high, the space
119
is formed on the rear housing
104
and the space
119
is a dead space that uselessly occupies the inside of the retaining portion
117
.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a piston type compressor that can reduce pressure pulsations in a discharge refrigerant gas without increasing its size by utilizing an internal space of a retaining portion of a rear housing as a muffler chamber.
To accomplish the object described above, the present invention provides a piston type compressor that includes a cylinder block; a front housing joined and fixed to an end portion of the cylinder block on the front side; a rear housing joined and fixed to an end portion of the cylinder block on the rear side; a drive shaft rotatably disposed as to extend from the cylinder block to the front housing; a plurality of cylinder bores formed round the drive shaft in the cylinder block; a piston accommodated in each cylinder bore and caused to reciprocate by the revolution of the drive shaft; a suction chamber defined inside, and on the peripheral side of, the rear housing; a valve/port-forming member equipped with a suction port and a suction valve that are clamped between the cylinder block and the rear housing and are disposed between each cylinder bore and the suction chamber, and with a discharge port and a discharge valve that are disposed between each cylinder bore and a discharge chamber; and a retaining portion so formed in the rear housing as to extend into the discharge chamber, and retaining the valve/port-forming member by its distal end face and by the cylinder block; wherein a center muffler chamber is defined inside the retaining portion and a discharge gas from the discharge chamber flows to an external circuit through the center muffler chamber.
In this construction, the piston is caused to reciprocate when the drive shaft rotates, and a series of compression cycles of suction of the gas of the suction chamber into the cylinder bore through the suction port and the suction valve, compression of the suction gas, and discharge of the compressed gas to the discharge chamber through the discharge port and the discharge valve are conducted.
The gas discharged from each discharge port to the discharge chamber flows through the center muffler chamber. The muffler operation of this center muffler chamber reduces the pressure pulsations, and the gas is discharged to the external circuit. The center muffler chamber is defined by effec

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