Piston-type compressor

Details Piston-type compressor Piston-type compressor

2000-04-19

2002-01-15

Koczo, Michael (Department: 3746)

Pumps

Condition responsive control of drive transmission or pump...

Adjustable cam or linkage

C417S269000, C092S071000

Reexamination Certificate

active

06338613

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a piston-type compressor used, for example, in vehicle air-conditioners.
FIGS. 9 and 10
show a typical variable displacement compressor. A compressor housing
101
includes a crank chamber
102
and a rotatably supported drive shaft
103
. A lug plate
104
is fixed to the drive shaft
103
in the crank chamber
102
. A swash plate
105
is coupled to the lug plate
104
through a hinge mechanism
106
. The lug plate
104
and the hinge mechanism
106
cause the swash plate
105
to rotate integrally with the drive shaft
103
and to incline relative to the drive shaft
103
.
Six cylinder bores
107
are formed in the housing
101
and are arranged about the axis L of the drive shaft
103
at equal intervals. A piston
108
is accommodated in each cylinder bore
107
and is coupled to the swash plate
105
through shoes
109
. When an external drive source, such as a vehicle engine, rotates the drive shaft
103
, the swash plate is rotated by the lug plate
104
and the hinge mechanism
106
. Rotation of the swash plate
105
is converted into reciprocation of the pistons
108
through the shoes
109
. The reciprocation of the pistons
108
repeats a cycle of drawing refrigerant gas to the cylinder bores
107
, compressing the refrigerant gas, and discharging the refrigerant gas from the cylinder bores
107
.
A thrust bearing
110
is located between the housing
101
and the lug plate
104
. The thrust bearing
110
receives a compression load, which is applied to the lug plate
104
through the pistons
108
, the shoes
109
, the swash plate
105
, and the hinge mechanism
106
.
A displacement control valve
111
, which is an electromagnetic valve, varies the pressure in the crank chamber
102
and the compressor displacement in accordance with external signals, which are determined by the cooling load and the On/Off state-of the air-conditioning switch.
When each piston
108
moves from the bottom dead center to the top dead center, that is, in the compression stroke, refrigerant gas is compressed. When each piston
108
moves from the top dead center to the bottom dead center, that is, in the suction stroke, refrigerant gas is drawn to the corresponding cylinder bore
107
.
As shown in
FIG. 10
, the swash plate
105
includes a location D
1
corresponding to the top dead center position of the pistons
108
and a location D
2
corresponding to the bottom dead center position of the pistons
108
. The pistons
108
are in the compression stroke when coupled to the part from the top dead center location D
1
to the bottom dead center location D
2
in the rotation direction of the swash plate
105
(or drive shaft
103
). That is, the pistons
108
that are coupled to the right side of the swash plate
105
from the imaginary plane H in
FIG. 10
are in the compression stroke. The pistons
108
are in the suction stroke when coupled to the part from the bottom dead center location D
2
to the top dead center location D
1
in the rotation direction of the drive shaft
103
. That is, the pistons
108
that are coupled to the left side of the swash plate
105
from the imaginary plane H in
FIG. 10
are in the suction stroke. The imaginary plane H includes the top dead center location D
1
, the bottom dead center location D
2
, and the axis L.
Therefore, a pressing force directed toward the lug plate
104
is applied from the pistons
108
to the compression stroke side of the swash plate
105
. On the other hand, a tractive force directed toward the cylinder bores
107
is applied from the pistons
108
to the suction stroke side of the swash plate
105
. The tractive force is caused by the negative pressure in the cylinder bores
107
.
Therefore, the force applied to one side of the swash plate
105
relative to the plane H is opposite to that applied to the other side. Accordingly, an inclination moment is applied to the piston-driving parts, which include the swash plate
105
, the hinge mechanism
106
, and the lug plate
104
. This may incline the piston-driving parts relative to the housing
101
and may form a space between the lug plate
104
and the thrust bearing
110
and between the thrust bearing
110
and the housing
101
. As a result, the rotation of the lug plate
104
may become unstable from chattering of the thrust bearing
110
, and the lug plate
104
drives the thrust bearing
110
against the housing
101
. This causes noise and vibration.
The illustrated compressor has a variable displacement. When the displacement is decreased, the control valve
111
increases the pressure in the crank chamber
102
. As the pressure in the crank chamber
102
increases, the difference between the pressure in the crank chamber
102
applied to the front of the pistons
108
coupled to the compression stroke side and that in the cylinder bores
107
applied to the rear of the same pistons
108
decreases. At this time, the difference between the pressure in the crank chamber
102
applied to the front of the pistons
108
coupled to the suction stroke side and that in the cylinder bores
107
applied to the rear of the same pistons
108
increases. This increases the inclination moment applied to the piston-driving parts
104
-
106
and causes the previously mentioned problems.
There is a case in which the control valve
111
, which is an electromagnetic valve controlled by the external signals, increases the pressure in the crank chamber
102
even if the cooling load is great. In other words, there is a case in which the displacement is decreased when the discharge pressure is high. In this case, the pressure in the crank chamber
102
increases to a very high level against the high pressure in the cylinder bores
107
, which further increases the inclination moment applied to the piston-driving parts
104
-
106
.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a piston-type compressor that reduces noise and vibration caused by the inclination of the piston-driving parts relative to the compressor housing.
To achieve the above objective, the present invention provides a piston-type compressor structured as follows. A housing includes a crank chamber and cylinder bores. Pistons are located in the corresponding cylinder bores. A drive shaft is supported by the housing and passes through the crank chamber. A piston-driving part is supported by the drive shaft in the crank chamber to rotate integrally with the drive shaft. The pistons are coupled to the piston-driving part. Gas in the cylinder bores is compressed when rotation of the drive shaft is converted into reciprocation of the pistons through the piston-driving part. A thrust bearing is located between the housing and the piston-driving part and receives a thrust load applied to the piston-driving part. The thrust bearing includes front and rear races and rolling elements located between the races. The front race is located between the rear race and the housing and the rear race is located between the front race and the piston-driving part. A front seat is formed on the housing for supporting the front race. A rear seat is formed on the piston-driving part for supporting the rear race. The diameters of the front and rear seats are different, which causes elastic deformation of the races when a thrust load is applied to the thrust bearing.
Other aspects and advantages of the present 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: 3393022 (1968-07-01), Alven et al.
patent: 4428718 (1984-01-01), Skinner
patent: 5094590 (1992-03-01), Carella et al.
patent: 5233913 (1993-08-01), Muirhead
patent: 5433137 (1995-07-01), Ikeda et al.
patent: 5762476 (1998-06-01), Ota et al.
patent: 0 814 263 (1997-12-01), None
patent: 04-148082 (1992-05-01), None
patent: 07-301177 (1995-11-01), None
patent: 10-047242 (1998-02-01), None
Communication from the European Patent Office regarding Europea

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