Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2001-06-21
2003-01-28
Walberg, Teresa (Department: 3742)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
Reexamination Certificate
active
06511297
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a compressor, and, more particularly, to a compressor in which moving components are lubricated with a lubricating oil contained in a refrigerant.
2. Description of the Related Art
A variable capacity compressor (hereinafter, referred simply to as a compressor) for use in an automotive air conditioner is known and a typical variable capacity compressor is shown in
FIG. 7
, for example. That is a housing
101
has a crank chamber
102
formed therein, and a drive shaft
103
is rotatably disposed therein. A lip seal
104
is interposed between the drive shaft
103
and the housing
101
so as to seal off a gap therebetween.
The drive shaft
103
is operatively coupled to an automotive engine Eg as an external drive source via an electromagnetic friction clutch
105
as a power transmission mechanism. The friction clutch
105
comprises a rotor
106
operatively coupled to the automotive engine Eg, an armature
17
fixed to the drive shaft
103
so as to rotate together with the drive shaft
103
and a coil
108
. When excited, the coil
108
attracts the armature
107
toward the rotor
106
to fasten the two components together, whereby power can be transmitted between the automotive engine Eg and the drive shaft
103
(the friction clutch
105
is switched on). When the coil
108
is demagnetized in this state, the armature
107
moves away from the rotor
106
, whereby power transmission between the automotive engine Eg and the drive shaft
103
is cut off (the friction clutch is switched off).
A rotation support member
109
is fixed to the drive shaft
103
in the crank chamber
102
, and a swash plate
110
is coupled to the rotation support unit
109
via a hinge mechanism
111
. The swash plate
110
can rotate together with the drive shaft
103
and the inclination angle thereof can be varied relative to the axis L of the drive shaft
103
because it is coupled to the rotation support unit
109
via the hinge mechanism
111
. A minimum inclination angle regulating portion
112
is provided on the drive shaft
103
and regulates the minimum inclination angle of the swash plate
110
by abutting thereagainst.
The cylinder bore
113
, a suction chamber
114
and a discharge chamber
115
are formed in the housing
101
. A piston
116
is reciprocally accommodated in the cylinder bore
113
and is coupled to the swash plate
110
.
The rotating motion of the drive shaft
103
is converted into reciprocating motion of the piston
116
via the rotation support unit
109
, the hinge mechanism
111
and the swash plate
110
, whereby a compression cycle is repeated which is made up of suction step of sucking the refrigerant gas from the suction chamber
114
into the cylinder bore
113
via a suction port
117
a
and a suction valve
117
b
of a valve/port forming unit
117
provided in the housing
102
, a compression step of compressing the sucked refrigerant gas and discharge step of discharging the compressed refrigerant gas to the discharge chamber
115
via a discharge port
117
c
and a discharge valve
117
d
of the valve/port forming unit
117
.
The suction chamber
114
and the discharge chamber
115
are connected to each other via an external refrigerant circuit, not shown. Refrigerant discharged from the discharge chamber
115
is introduced into the external refrigerant circuit. Heat exchange is carried out in this external refrigerant circuit using the refrigerant. Refrigerant discharged from the external refrigerant circuit is introduced into the suction chamber
114
and is then sucked into the cylinder bore
113
for re-compression.
A gas bleed passage
119
communicates with the crank chamber
102
and the suction chamber
114
. A gas supply passage
120
communicates with the discharge chamber
115
and the crank chamber
102
. A control valve
121
is disposed in the gas supply passage
120
for regulating the opening degree of the gas supply passage
120
.
The control valve
121
is constructed to be driven by an electric current outputted by a drive circuit, not shown, based on a signal from a control computer, not shown, so as to regulate the opening degree of the gas supply passage
120
. In the state in which it is not activated by the drive circuit, the control valve
121
operates so as to open the gas supply passage
120
, whereas in the state in which it is activated, the control valve
121
operates so as to regulate the opening degree of the gas supply passage
120
.
The balance between the amount of the high pressure gas introduced into the crank chamber
102
via the gas supply passage
120
and the amount of the gas flowing out from the crank chamber
102
via the gas bleed passage
119
is controlled by regulating the opening degree of the control valve
121
to thereby determine a crank pressure Pc. A difference between the crank pressure Pc and the internal pressure in the cylinder bore
113
on the opposite side of the piston is varied in response to a variation in the crank pressure Pc and, as a result of a variation in the inclination angle of the swash plate
110
, the stroke or the discharge capacity of the piston is regulated.
If, for example, the friction clutch
105
is switched off in response to switching off an air conditioner switch, not shown, from the state in which the compressor is running at the maximum discharge capacity thereof or that the automotive engine Eg is halted, whereby the operation of the compressor is also stopped, activation of the control valve
121
is also stopped (the input current value is zero), and it follows that the gas supply passage
120
is fully opened in a sudden fashion. Consequently, the supply volume of high pressure refrigerant gas from the discharge chamber
115
to the crank chamber
102
is increased suddenly, and since the gas bleed passage
119
cannot bleed the suddenly increased volume of refrigerant gas, the pressure inside the crank chamber
102
is increased excessively. In addition, the pressure inside the cylinder bore
113
is reduced because the pressure tends to become uniform to a lower pressure in the suction chamber
114
due to the stopping of the operation of the compressor. As a result, the difference in pressure between the cylinder bore
113
and the crank chamber
102
is increased excessively.
Due to this, the stash plate
110
inclination angle is set to the minimum inclination angle (shown by chain double-dashed lines in
FIG. 7
) and it is pressed against the minimum inclination angle regulating portion
112
with an excessively large force and strongly pulls the rotation support unit
109
rearward (rightward as viewed in the figure) via the hinge mechanism
111
. As a result, the drive shaft
103
is subjected to a strong moving force acting rearward along the axis L thereof and is forced to slide against the biasing force of a drive shaft biasing spring
118
. Due to this, the following problems may be caused.
(a) When the drive shaft
103
slides in the axial L direction, there is a possibility that the sliding position of the lip seal
104
will deviate from a predetermined position called a contact line. There are many cases where foreign matter such as sludge adheres to portions deviating from the contact line on the outer circumferential surface of the drive shaft
103
. Due to this, sludge bites into the lip seal
104
and the drive shaft
103
and this reduces the shaft seal performance, whereby a defect such as gas leakage occurs.
(b) When the friction clutch is switched off, in other words, power transmission between the automotive engine Eg and the drive shaft
103
is cut off and, if the drive shaft
103
slides rearward in the axial L direction, the armature
107
fixed to the drive shaft
103
moves toward the rotor
106
. A clearance between the rotor
106
and the armature
107
is very small (for example, 0.5 mm) in the state in which the friction clutch
105
is switched off. Consequently, the rearward sliding of the drive shaft
113
along the axial L dire
Adaniya Taku
Kimura Kazuya
Matsubara Ryo
Ota Masaki
Suitou Ken
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Patel Vihod D
Woodcock & Washburn LLP
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