Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2001-01-10
2003-04-15
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C417S269000, C092S071000
Reexamination Certificate
active
06547533
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a piston type compressor used in, for example, a vehicle air conditioner and a compressor assembly method.
A conventional variable displacement swash plate type compressor shown in
FIG. 7
includes an electromagnetic clutch
101
between a drive shaft
104
and a vehicle engine Eg, which is an external driving source. The electromagnetic clutch
101
includes a rotor
101
b
connected to the engine Eg and an armature
101
a
integrally, rotatably secured to the drive shaft
104
. When the electromagnetic clutch
101
is turned on, the armature
101
a
is pulled toward the rotor
101
b
and engages the rotor
101
b
, which engages the clutch
101
. Accordingly, the power of the engine Eg is transmitted to the drive shaft
104
. When the electromagnetic clutch
101
is turned off, the armature
101
a
is moved away from the rotor
101
b
, which disengages the clutch
101
. Accordingly, the drive shaft
104
is disconnected from the engine Eg.
A rotor
105
is fixed to the drive shaft
104
in a crank chamber
107
. A thrust bearing
111
is located between the rotor
105
and a housing
110
. A swash plate
103
is connected, through a hinge mechanism
106
, to the rotor
105
. The swash plate
103
is supported on the drive shaft
104
and inclines with respect to the axis L. The swash plate
103
is driven integrally with the drive shaft
104
through the hinge mechanism
106
. A restriction ring
109
is provided on the drive shaft
104
. When the swash plate
103
contacts the restriction ring
109
, the swash plate
103
is defined at the minimum inclination angle position.
A cylinder bore
108
is formed in the housing
110
. A piston
102
is accommodated in the cylinder bore
108
and is connected to the swash plate
103
.
The inclination angle of the swash plate
103
is changed by changing the difference between the pressure in the crank chamber
107
and the pressure in the cylinder bore
108
through the piston
102
. Thus, when the inclination angle is changed, the stroke of the piston
102
is changed so that the discharge displacement is changed.
When the inner pressure of the crank chamber
107
is increased and the difference between the increased pressure in the crank chamber
107
and the pressure in the cylinder bore
108
becomes large, the inclination angle of the swash plate
103
decreases and the discharge displacement of the compressor becomes small. A broken line in
FIG. 7
shows the swash plate
103
at the minimum inclination angle position, where it contacts the restriction ring
109
. On the other hand, when the inner pressure of the crank chamber
107
is decreased and the difference between the decreased pressure in the crank chamber
107
and the pressure in the cylinder bore
108
becomes small, the inclination angle of the swash plate
103
increases and the discharge displacement of the compressor becomes large. As a result, the swash plate
103
is moved to the maximum inclination angle position.
When refrigerant gas is being compressed, and in particular, when the swash plate
103
is at the maximum inclination angle position, a strong compression load force is transmitted through the piston
102
, the swash plate
103
, the hinge mechanism
106
, the rotor
105
and the drive shaft
104
to the inner wall surface of the housing
110
.
When the electromagnetic clutch
101
is turned off, or when the engine Eg is stopped, the pressure in the crank chamber
107
is increased and the swash plate
103
is moved to the minimum inclination angle position. As a result, the compressor is stopped in a state where the inclination angle of the swash plate
103
is minimum, in other words, in a state where the discharge displacement is minimum. Therefore, the compressor is always started from the minimum discharge displacement, where the load torque is minimum. This reduces the shock generated when the compressor is started. In addition, when a vehicle is abruptly accelerated, the load on the engine Eg is reduced. Thus, the pressure in the crank chamber abruptly increases so that the discharge displacement of the compressor becomes minimum.
However, when the pressure in the crank chamber
107
is abruptly increased, the inclination angle of the swash plate
103
is rapidly reduced. Accordingly, the swash plate
103
(as shown by the broken line in
FIG. 7
) moves to the minimum inclination angle position and strongly presses against the restriction ring
109
. Further, the swash plate
103
pulls the rotor
105
rearward (in the right direction of
FIG. 7
) through the hinge mechanism
106
. As a result, the drive shaft
104
is moved axially rearward against the force of a support spring
113
.
When the drive shaft
104
is moved in the rear direction when the compressor is stopped by disengagement of the electromagnetic clutch
101
, the armature
101
a
, which is secured to the drive shaft
104
, is moved toward the rotor
101
b
. This may eliminate the clearance between the armature
101
a
and the rotor
101
b
, and the armature
101
a
may contact the rotor
101
b
, which is rotating. As a result, noise or vibration occurs, or, in spite of the deactivation of the clutch
101
, the power of the engine Eg may be transmitted to the drive shaft
104
.
When the drive shaft
104
is moved rearward, the piston
102
, which is connected to the drive shaft
104
through the rotor
105
, the hinge mechanism
106
, and the swash plate
103
are also moved rearward. Thus, the top dead center position of the piston
102
is moved toward a valve plate
112
. Accordingly, the piston, which reciprocates in the cylinder bore
108
, may repeatedly collide with the valve plate
112
. As a result, vibration or noise occurs.
To prevent the movement of the drive shaft
104
in the rearward direction, increasing the force applied by the supporting spring
113
has been considered. However, when the force of the supporting spring
113
is increased, the life of the thrust bearing
111
between the housing
110
and the rotor
105
is reduced, and the power loss of the engine Eg is increased.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a piston type compressor that requires no spring for urging a drive shaft, and an assembly method for the same.
To attain the above-mentioned object, the present invention provides a piston type compressor. The compressor includes a housing and a crank chamber formed in the housing. A drive shaft is rotatably supported by the housing in the crank chamber. The drive shaft has an end surface. A cylinder bore is formed in the housing. A piston is located in the cylinder bore. The piston reciprocates between a top dead position and a bottom dead position. A valve plate is located at an opposite side of the piston from the crank chamber. A swash plate is connected with the piston to change the rotation of the drive shaft to reciprocation of the piston. The swash plate integrally rotates with the drive shaft. A front restriction and a rear restriction are located in the housing and for restricting a movement in the axial direction of the drive shaft. The front restriction restricts the axial movement of the drive shaft in a forward direction. The rear restriction restricts axial movement of the drive shaft in a rear direction. A first clearance is formed between the end surface of the drive shaft and the rear restriction when the movement of the drive shaft is restricted by the front restriction. A second clearance is formed between the piston and the valve plate when the movement of the drive shaft is restricted by the front restriction and when the piston is in the top dead center position. The first clearance is smaller than the second clearance.
The present invention also provides an another piston type compressor. The compressor includes a housing and a crank chamber formed in the housing. A drive shaft is rotatably supported by the housing in the crank chamber. The drive shaft has an end surface. A cylinder bore is formed in the housing. A piston
Kayukawa Hiroaki
Kimura Kazuya
Ota Masaki
Suitou Ken
Umemura Satoshi
Freay Charles G.
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan , LLP
Solak Timothy P.
LandOfFree
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