Variable displacement compressor

Details Variable displacement compressor Variable displacement compressor

1999-07-21

2001-04-17

Thorpe, Timothy S. (Department: 3746)

Pumps

Condition responsive control of drive transmission or pump...

Adjustable cam or linkage

Reexamination Certificate

active

06217293

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a variable displacement compressor for vehicle air-conditioning system. More specifically, the present invention relates to a variable displacement compressor having a drive plate for reciprocating pistons, the inclination angle of which is varied.
FIGS. 3 and 4
show a conventional variable displacement compressor. A drive shaft
102
is rotatably supported in a housing
101
. The housing
101
includes cylinder bores
101
a,
a crank chamber
103
, a suction chamber
104
, and a discharge chamber
105
. A piston
106
is accommodated in each cylinder bore
101
a
to reciprocate. A rotor
107
is fixed to the drive shaft
102
in the crank chamber
103
. A drive plate, or a swash plate
108
, is accommodated in the crank chamber
103
. The drive shaft
102
penetrates the swash plate
108
. A hinge mechanism
109
is located between the rotor
107
and the swash plate
108
. The hinge mechanism
109
rotates the swash plate
108
together with the drive shaft
102
and the rotor
107
and permits the swash plate
108
to incline with respect to the drive shaft
102
. The pistons
106
are coupled to the swash plate
108
.
The drive shaft
102
is connected to an external drive source, or an engine
110
, of the vehicle without a clutch mechanism such as an electromagnetic clutch. The drive shaft
102
is constantly driven while the engine
110
is running. The swash plate converts the rotation of the drive shaft
102
into reciprocation of each piston
106
. Each piston
106
draws refrigerant gas from the suction chamber
104
to the corresponding cylinder bore
101
a
and compresses the gas. Then, the refrigerant gas is discharged from the cylinder bore
101
a
to the discharge chamber
105
.
A pressurizing passage
111
connects the crank chamber
103
to the discharge chamber
105
. A bleeding passage
112
connects the crank chamber
103
to the suction chamber
104
. A displacement control valve
113
is located in the pressurizing passage
111
. The control valve
113
is an electromagnetic valve and moves a valve body
113
b by exciting and de-exciting a solenoid
113
a.
This opens and closes the pressurizing passage
111
. When the solenoid
113
a
is excited, the control valve
113
closes the pressurizing passage
111
. When the solenoid
113
a
is de-excited, the control valve
113
opens the pressurizing passage
111
.
As shown in
FIG. 3
, when the pressurizing passage
111
is closed, the refrigerant gas does not flow from the discharge chamber
105
to the crank chamber
103
. Accordingly, the pressure in the crank chamber
103
decreases and the inclination angle of the swash plate
108
increases. This increases the piston stroke and displacement of the compressor. As shown in
FIG. 4
, when the pressuring passage
111
is opened, the refrigerant gas flows from the discharge chamber
105
to the crank chamber
103
. Accordingly, pressure in the crank chamber
103
increases and the inclination angle of the swash plate
108
decreases. This decreases the piston stroke and displacement of the compressor.
A suction passage
114
is formed in the housing
101
and connects an external refrigerant circuit to the suction chamber
104
. A shutter
115
engages the rear end of the drive shaft
102
and slides along the axis of the drive shaft
102
. The shutter
115
moves with the swash plate
108
and selectively opens and closes the suction passage
114
. As shown in
FIG. 3
, when the swash plate
108
is positioned at its maximum inclination angle by the excitation of solenoid
113
a,
the shutter
115
opens the suction passage
114
. Accordingly, the refrigerant gas flows from the external refrigerant circuit to the suction chamber
104
. As shown in
FIG. 4
, when the swash plate
108
is positioned at its minimum inclination angle by the demagnetization of the solenoid
113
a, the shutter
115
closes the suction
114
. Accordingly, refrigerant gas does not flow from the external refrigerant circuit to the suction chamber
104
. This stops the circulation of refrigerant gas between the external refrigerant circuit and the compressor.
The control valve
113
includes an electromagnetic valve and suddenly opens the pressurizing passage
111
when the solenoid
113
a
is demagnetized. Accordingly, high-pressure refrigerant gas of the discharge chamber
105
suddenly flows into the crank chamber. This suddenly increases pressure in the crank chamber
103
and reduces the inclination angle of the swash plate
108
. This increases friction on the engaging parts of the hinge mechanism
109
, the swash plate
108
and the drive shaft
102
, which produces vibration and noise.
SUMMARY OF THE INVENTION
An objective of the present invention is to control the sudden change of pressure in the crank chamber and slows the change of inclination angle of the drive plate in a variable displacement compressor.
To achieve the above objective, the present invention provides a variable displacement compressor that varies the displacement in accordance with the inclination angle of a drive plate located in a crank chamber. The compressor is structured as follows. A piston is connected to the drive plate and is reciprocated by movement of the drive plate. An adjusting mechanism for adjusting the pressure in the crank chamber includes a control passage connected to the crank chamber for permitting passage of a fluid and a control valve located in the control passage for selectively opening and closing the control passage. The inclination of the drive plate is varied in accordance with pressure in the crank chamber and the piston stroke varies in accordance with the drive plate inclination to vary the displacement. A fixed restrictor is located in the control passage, to limit the flow rate of the fluid in the control passage.
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.


REFERENCES:
patent: 4867648 (1989-09-01), Murayama
patent: 5242274 (1993-09-01), Inoue
patent: 5318410 (1994-06-01), Kawamura et al.
patent: 5865604 (1999-02-01), Kawaguchi et al.
patent: 5971716 (1999-10-01), Ota et al.
patent: 5975859 (1999-11-01), Kawaguchi et al.
patent: 6010312 (2000-01-01), Suitou et al.
patent: 7-253080 (1995-10-01), None
German Search Report dated Oct. 23, 2000 (and translation thereof).

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