Information
-
Patent Grant
-
6626645
-
Patent Number
6,626,645
-
Date Filed
Monday, April 1, 200222 years ago
-
Date Issued
Tuesday, September 30, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Freay; Charles G.
- Gray; Michael K.
Agents
- Rader, Fishman & Grauer PLLC
-
CPC
-
US Classifications
Field of Search
US
- 417 2222
- 417 2221
- 251 12902
- 251 12915
-
International Classifications
-
Abstract
A valve element disposed in the valve chamber of a control valve body of a control valve for variable capacity compressors performs opening and closing operations by a plunger. The upper end of the valve element of this control valve body is inserted in the pressure chamber, while the lower end of the valve element is inserted in the plunger chamber of the solenoid excitation part. And the plunger chamber and the pressure chamber communicate with each other through a cancel hole formed in this valve element.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control valve for variable capacity compressors used in air conditioners of vehicles and the like and, more particularly, to a control valve for variable capacity compressors that controls the supply of a coolant gas in the interior of a crankcase from a discharge-pressure region as required.
2. Description of the Prior Art
Conventionally, variable capacity compressors provided with a cylinder, a piston, a wobble plate, etc. have been used, for example, in compressing and delivering a coolant gas of an air conditioner for automobiles. A known variable capacity compressor of this type is provided with a coolant-gas passage that communicates with a discharge-pressure region and a crankcase, and changes the inclination angle of the wobble plate by adjusting the pressure in the interior of the crankcase thereby to change discharge capacity. The pressure adjustment in the interior of the crankshaft is performed by supplying a high-pressure compressed coolant gas from the discharge-pressure region to the crankcase by the opening adjustment of a control valve provided within the coolant-gas passage.
For example, a control valve
100
′ as shown in
FIGS. 10 and 11
is known (Japanese Patent Application Laid-Open Nos. 9-268973 and 9-268974) as a control valve for such a variable capacity compressor as described above. This control valve
100
′ is provided on the side of the rear housing
210
of a variable capacity compressor
200
, and performs the pressure adjustment of a crankcase
231
within a front housing
230
, which is installed in connection with a cylinder block
220
of the variable capacity compressor
200
.
In the interior of the crankcase
231
, a wobble plate
240
is supported by a driving shaft
250
in a manner such that the wobble plate
240
can slide in the axial direction of the driving shaft
250
and tilt. A guide pin
241
of this wobble plate
240
is slidably supported by a support arm
252
of a rotary support
251
. Also, the wobble plate
240
is connected, via a pair of shoes
242
, to a piston
260
, which is slidably disposed within a cylinder bore
221
.
The wobble plate
240
rotates in the directions indicated by an arrow shown in
FIG. 10
according to a difference between the suction pressure Ps in the cylinder bore
221
and the crankcase pressure Pc in the crankcase
231
, and changes the inclination angle of the wobble plate
240
itself. On the basis of the inclination angle of the wobble plate
240
, the stroke width of forward and backward movements of the piston
260
in the cylinder bore
221
is determined. And a blocking element
270
that abuts against the middle portion of the wobble plate
240
moves forward and backward in a housing hole
222
as the wobble plate
240
rotates in the directions indicated by the arrow.
In the interior of the rear housing
210
, suction chambers
211
a
,
211
b
, which constitute a suction-pressure region, and discharge chambers
212
a
,
212
b
, which constitute a discharge-pressure region, are defined and formed. When the piston
260
moves forward and backward on the basis of the rotation of the wobble plate
240
, a coolant gas in the suction chamber
211
a
is sucked into the interior of the cylinder bore
221
from a suction port
213
, is compressed to a prescribed pressure and is then delivered from a discharge port into the discharge chamber
212
a.
Furthermore, a suction passage
215
formed in the center portion of the rear housing
210
communicates with the housing hole
222
and, at the same time, the suction passage
215
communicates also with the suction chamber
211
b
via a through hole
216
. When the wobble plate
240
moves to the side of the blocking element
270
, the blocking element
270
moves to the side of the suction passage
215
and blocks the through hole
216
.
The upper side of the control valve
100
′ communicates with the suction passage
215
via a pressure-detection passage
217
that introduces the suction pressure Ps into the interior of the control valve
100
′. Furthermore, the discharge chamber
212
b
and the crankcase
231
communicate with each other via air supply passages
218
,
219
of the control valve
100
′. The air supply passages
218
,
219
are opened and closed by a valve element
106
′ of the control valve
100
′.
The discharge pressure Pd of the discharge chamber
212
b
is introduced into a valve chamber port
113
′ via the air supply passage
218
. The pressure Pc within the crankcase is introduced into the air supply passage
219
via a valve hole port
114
′. The suction pressure Ps is introduced into a suction pressure introduction port
115
′ via the pressure-detection passage
217
.
When an operation switch
280
of an air conditioner is on, for example, when a temperature detected by a room sensor
281
is not less than a temperature set by a room temperature setting device
282
, a control computer
283
gives instructions to a solenoid
101
′ of the control valve
100
′ and causes the solenoid
101
′ to supply a prescribed current to a driving circuit
284
. And a moving core
102
′ is attracted toward the fixed core
104
′ by the attraction of the solenoid
101
′ and the urging force of a spring
103
′.
With the movement of the moving core
102
′ the valve element
106
′ attached to a solenoid rod
105
′ moves, while resisting the urging force of a forced relief spring
107
′, in a direction in which the opening of a valve hole
108
′ is reduced. With the movement of this valve element
106
′ a pressure-sensitive rod
109
′, which is integral with the valve element
106
′, also rises. As a result of this, a bellows
111
′ is pressed, which is connected to the valve element
106
′ via a pressure-sensitive rod receiving part
110
′ in such a manner that the bellows
111
′ can come close to and away from the valve element
106
′.
The bellows
111
′ is displaced according to variations in the suction pressure Ps introduced into the interior of a pressure-sensitive part
112
′ via the pressure-detection passage
217
, and gives loads to the pressure-sensitive rod
109
′. Accordingly, the opening of the valve hole
108
′ of control valve
100
′ by the valve element
106
′ is determined by a combination of the attraction by the solenoid
101
′, the urging force of the bellows
111
′ and the urging force of the forced relief spring
107
′.
When a difference between a temperature detected by the room sensor
281
and a temperature set by the room temperature setting device is great (when the cooling load is large), an increase in supply current causes the fixed core
104
′ to attract the moving core
102
′, and the opening of the valve hole
108
′ by the valve element
106
′ decreases. As a result, the control valve
100
′ operates in such a manner that the control valve
100
′ holds a lower suction pressure Ps, and under this suction pressure Ps the opening and closing of the valve element
106
′ is performed.
When the valve opening decreases, the volume of the coolant gas that flows from the discharge chamber
212
b
via the air supply passages
218
,
219
into the crankcase
231
decreases and, at the same time, the gas in the crankcase
231
flows out and enters the suction chambers
211
b
,
211
a
, with the result that the pressure Pc in the crankcase drops. And when the cooling load is large, the suction pressure Ps in the cylinder bore
221
increases and a difference is made between the suction pressure Ps and the pressure Pc in the crankcase, resulting in an increased inclination angle of the wobble plate
240
. As a result, the blocking element
270
leaves the side of the suction passage
215
and opens the through hole
216
.
Incidentally, as shown in
FIGS. 10 and 11
, the above-described conventional control valve
100
′ is constructed in such a manner that the discharge pressure Pd is introduced into the valve chamber port
113
′ of the control valve
100
′ via the air supply passage
218
. This discharge pressure Pd is high and besides the coolant gas that generates the discharge pressure Pd gives off high heat by being compressed by the forward and backward motions of the piston
260
until a prescribed pressure is reached, with the result that the control valve
100
′ itself is heated by this high heat and the accuracy of opening and closing of the valve hole
108
′ by the valve element
106
′ decreases, posing a problem.
Also, because the distance between the point of application of the attraction of solenoid rod
105
′ by the solenoid
101
′ and the point of application of the urging force by the bellows
111
′ is large, there is a fear that during the movement of the solenoid rod
105
′ at the time of valve closing, backlash might occur in the solenoid rod
105
′, thereby hindering an improvement in the accuracy of valve opening and closing.
In order to solve this problem, there is disclosed in Japanese Patent Application Laid-Open No. 11-218078 a technique for bringing the point of application of the attraction of solenoid rod close to the point of application of the urging force of bellows by disposing a bellows below a solenoid rod. With this technique, however, a low suction pressure Ps becomes apt to remain as a coolant pool on the bellows side and, therefore, no special consideration is given to factors responsible for the hindrance to plunger motions, such as sticking by plane contact between the lower end of the control valve proper and the upper end surface of the plunger, or factors responsible for the hindrance to the motions of the plunger and stem by the damper action of a coolant.
Furthermore, the pressure-receiving area that receives the crankcase pressure Pc on the upper side of the moving direction of the valve element
106
′ is adjusted to such a size that the respective pressure-receiving areas of valve hole
108
′ and solenoid rod
105
′ are not affected by pressure. However, because the suction pressure Ps and crankcase pressure Pc are not always held at the same level of pressure, the suction pressure Ps and crankcase pressure Pc are not completely balanced out. In addition, because the pressure in the crankcase shows great pressure variations due to the operation of a compressor, forces acting on the valve element
106
′ also vary when the pressure variations occur, posing a problem of an adverse effect on the opening and closing accuracy of the valve element
106
′.
Also, in the conventional control valve for variable capacity compressors, a pressure-sensitive bellows and means for exciting a solenoid are arranged side by side in the opening and closing direction of a valve element and, therefore, this poses a problem of difficulty in achieving compact design suitable for a part to be installed in a car.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a control valve for variable capacity compressors which improves the accuracy of valve opening and closing by eliminating an adverse effect of a coolant gas pressure acting on the valve element of the control valve, and which, at the same time, permits compact design.
In order to achieve the above-described object, in a first aspect of the present invention there is provided a control valve for variable capacity compressors, which comprises a control valve body, a solenoid excitation part and a pressure-sensitive part. The solenoid excitation part is provided with a solenoid and a plunger moving vertically by the excitation of the solenoid. The control valve body is disposed on the upper side of the solenoid excitation part and has a valve chamber provided with a valve hole on the bottom surface thereof, a pressure chamber disposed above the valve chamber, and a valve element disposed in the valve chamber and performing opening and closing operations by the plunger. The upper end of the valve element of the control valve body is inserted in the pressure chamber and the lower end thereof is inserted in the plunger chamber of the solenoid excitation part. And, the plunger chamber and the pressure chamber communicate with each other through a cancel hole formed in the valve element.
Because in the control valve for variable capacity compressors of the present invention constructed as described above, the coolant gas at the suction pressure Ps in the plunger chamber is introduced into the pressure chamber via the cancel hole, the valve element is subjected to the suction pressure Ps from both sides of the upper and lower portions thereof. In addition, because the upper and lower portions of the valve element have the same sectional area, the valve element is not influenced by the discharge pressure Pd. Therefore, because pressure balance is always maintained in the upper and lower portions of the valve element, the valve opening and closing accuracy can be improved. In addition, because the cancel hole is provided in the valve element, the working of the cancel hole can be easily performed.
Furthermore, in a second aspect of the present invention there is provided a control valve for variable capacity compressors, which comprises a control valve body, a solenoid excitation part and a pressure-sensitive part. The solenoid excitation part is provided with a solenoid, a plunger moving vertically by the excitation of the solenoid and an attraction element on the lower side of the plunger. And the pressure-sensitive part is formed on the inner side of the attraction element. As a result, because the pressure-sensitive part is formed on the inner side of the attraction element, it is possible to ensure compact design of the control valve by reducing the diameter of the solenoid excitation part.
In the control valve for variable capacity compressors according to the present invention, the following preferred embodiments can be adopted.
The attraction element is in the form of a cylinder with a bottom opposed to the plunger. Alternatively, the attraction element comprises a cylindrical portion to be engaged with the inner side of the solenoid excitation part and a cover portion to be press-fitted to the upper end of this cylindrical portion.
The plunger is provided with a coolant vent in the interior thereof in the longitudinal axial direction. Alternatively, the plunger is provided with a slit on the side surface thereof in the longitudinal axial direction.
The solenoid excitation part is provided with a stem having an almost half-moon section for transmitting the motion of the above-described pressure-sensitive part to the plunger.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other objects and features of the present invention will become apparent from the following description of the embodiments taken in connection with the accompanying drawings in which:
FIG. 1
is a longitudinal sectional view of a variable capacity compressor provided with a control valve of the first embodiment of the present invention, wherein the discharge passage of the compressor is in open state;
FIG. 2
is a longitudinal sectional view of the variable capacity compressor shown in
FIG. 1
, wherein the discharge passage is in closed state;
FIG. 3
is an enlarged longitudinal sectional view of a control valve for the variable capacity compressor shown in
FIG. 1
;
FIG. 4
is a longitudinal sectional view of the details of the control valve shown in
FIG. 3
;
FIGS. 5A and 5B
are a perspective view and a longitudinal sectional view, respectively, of a plunger of control valve shown in
FIG. 3
;
FIGS. 6A and 6B
are a perspective view and a longitudinal sectional view, respectively, of a stem of control valve shown in
FIG. 3
;
FIG. 7
is a perspective view of a stem whose structure is different from that of the stem shown in
FIGS. 6A and 6B
;
FIG. 8
is an enlarged longitudinal sectional view of a control valve in the second embodiment of the present invention;
FIG. 9
is an enlarged longitudinal sectional view of a control valve in the third embodiment of the present invention;
FIG. 10
is a longitudinal sectional view of a variable capacity compressor provided with a conventional control valve; and
FIG. 11
is a longitudinal sectional view of the details of the control valve shown in FIG.
10
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First, a variable capacity compressor provided with a control valve
100
in the first embodiment of the present invention will be described below by referring to
FIGS. 1 and 2
.
A rear housing
3
is fixed to one end surface of a cylinder block
2
of a variable capacity compressor
1
via a valve plate
2
a
, and a front housing
4
is fixed to the other end surface thereof. In the cylinder block
2
, a plurality of cylinder bores
6
are disposed around a shaft
5
at equal intervals in a circumferential direction. A piston
7
is slidably housed in each cylinder bore
6
.
A crankcase
8
is formed in the front housing
4
. A wobble plate
10
is disposed in the crankcase
8
. On a sliding surface
10
a
of the wobble plate
10
, a shoe
50
, that supports one spherical end
11
a
of a connecting rod
11
such that the spherical end
11
a
can slide relative to the shoe
50
, is held by a retainer
53
. The retainer
53
is mounted to a boss
10
b
of the wobble plate
10
via a radial bearing
55
such that the retainer
53
can rotate relative to the wobble plate
10
. The radial bearing
55
is locked to the boss
10
b
by means of a stopper
54
fixed by a screw
45
. The other end
11
b
of the connecting rod
11
is fixed to the piston
7
.
The shoe
50
is composed of a shoe body
51
which supports the leading end surface of one end
11
a
of the connecting rod
11
such that the one end
11
a
can roll relative to the shoe
50
, and a washer
52
which supports the trailing end surface
11
a
of the connecting rod
11
such that the trailing end surface
11
a
can roll relative to the washer
52
.
A discharge chamber
12
and a suction chamber
13
are formed in the rear housing
3
. The suction chamber
13
is arranged so as to surround the discharge chamber
12
. A suction port (not shown) that communicates with an evaporator (not shown) is provided in the rear housing
3
.
FIG. 1
shows a discharge passage
39
in an open state and
FIG. 2
shows the discharge passage
39
in a closed state. Midway in the discharge passage
39
that provides communication between the discharge chamber
12
and a discharge port
1
a
, there is provided a spool valve (a discharge control valve)
31
. The discharge passage
39
is composed of a passage
39
a
formed in the rear housing and a passage
39
b
formed in the valve plate
2
a
. The passage
39
b
communicates with the discharge port
1
a
formed in the cylinder block
2
.
A spring (an urging member)
32
is disposed within the cylindrical spool valve
31
having a bottom. One end of this spring
32
abuts against a stopper
56
fixed to the rear housing
3
by means of a cap
59
. The other end of the spring
32
abuts against the bottom surface of the spool valve
31
. The inner space
33
of the spool valve
31
communicates with the crankcase
8
via a passage
34
.
On one side (the upper side) of the spool valve
31
, the urging force of the spring
32
and the pressure of the crankcase
8
act in a direction in which the urging force and pressure close the spool valve
31
(in a direction in which the urging force and pressure reduce the opening of the valve
31
). On the other hand, when the spool valve
31
is open as shown in
FIG. 1
, the discharge port
1
a
and the discharge chamber
12
communicate with each other via the discharge passage
39
and, therefore, on the other side (the lower side) of the spool valve
31
the pressure of the discharge port
1
a
and the pressure of the discharge chamber
12
act in a direction in which both pressures open the spool valve
31
(in a direction in which both pressures increase the opening of the valve
31
). However, when a pressure difference between the crankcase
8
and the discharge port
1
a
becomes not more than a prescribed value, the spool valves
31
moves in a closing direction and blocks the discharge passage
39
. As a result, on the lower side of the spool valve
31
, the pressure of the discharge port
1
a
ceases to act and only the pressure of the discharge chamber
12
acts in a direction in which the pressure opens the valve
31
.
The discharge chamber
12
and the crankcase
8
communicate with each other via a second passage
57
. Midway in this second passage
57
, a control valve
100
of this embodiment, which will be described in detail later, is disposed at a position lower than the center position of the compressor
1
. In the case of a large thermal load, this second passage
57
is blocked because a valve element
132
is placed on a valve seat due to the energization of the solenoid
131
A of the control valve
100
. On the other hand, in the case of a small thermal load, the second passage
57
communicates because the valve element
132
leaves a valve seat
125
a
due to the stop of the energization of the solenoid
131
A. The operation of the control valve
100
is controlled by a computer (not shown).
The suction chamber
13
and the crankcase
8
communicate with each other via a first passage
58
. This first passage
58
is composed of an orifice (a second orifice)
58
a
formed in the valve plate
2
a
, a passage
58
b
formed in the cylinder block
2
, and a hole
58
c
formed in a ring (an annular part)
9
fixed to the shaft
5
. The suction chamber
13
and the crankcase
8
communicate with each other via a third passage
60
.
This third passage
60
is composed of a passage
60
a
formed in the front housing
4
, a front-side bearing-housing space
60
b
, a passage
60
c
formed in the shaft
5
, a rear-side bearing-housing space
60
d
formed in the cylinder block
2
, the passage
58
b
of cylinder block
2
, and an orifice
58
a
of valve plate
2
a.
Therefore, the passage
58
b
of cylinder block
2
and the orifice
58
a
of valve plate
2
a
constitute part of the first passage
58
and, at the same time, constitute also part of the third passage
60
.
A female thread
61
is formed on the inner peripheral surface of the rear-side end of the passage
60
c
formed in the shaft
5
. A screw
62
is screwed into this female thread
61
. An orifice (a first orifice)
62
a
is formed in this screw
62
, and the passage area of this orifice
62
a
is smaller than the passage area of the second orifice
58
a
in the valve plate
2
a
that constitutes part of the first passage
58
. Therefore, only in a case where the boss
10
b
of wobble plate
10
almost blocks the hole
58
c
of ring
9
and the passage area of the first passage
58
has decreased greatly, the coolant in the crankcase
8
is introduced into the suction chamber
13
via the third passage
60
.
In the valve plate
2
a
, there are provided a plurality of discharge ports
16
, which provide communication between a compression chamber
82
and the discharge chamber
12
, and a plurality of suction ports
15
, which provide communication between the compression chamber
82
and the suction chamber
13
, respectively, at equal intervals in the circumferential direction. The discharge port
16
is opened and closed by a discharge valve
17
. The discharge port
17
, along with a valve-holding member
18
, is fixed to the side end surface of the rear housing of valve plate
2
a
by means of a bolt
19
and a nut
20
. On the other hand, the suction port
15
is opened and closed by a suction valve
21
. This suction valve
21
is disposed between the valve plate
2
a
and the cylinder block
2
.
The rear-side end of the shaft
5
is rotatably supported by a radial bearing (a rear-side bearing)
24
housed in the rear-side bearing-housing space
60
d
of cylinder block
2
and a thrust bearing (a rear-side bearing)
25
. On the other hand, the front-side end of the shaft
5
is rotatably supported by a radial bearing (a front-side bearing)
26
housed in the front-side bearing-housing space
60
b
of front housing
4
. A shaft seal
46
, in addition to the radial bearing
26
, is housed in the front-side bearing-housing space
60
b.
A female thread
1
b
is formed in the middle of the cylinder block
2
. An adjusting nut
83
engages on this female thread
1
b
. A preload is given to the shaft
5
via the thrust bearing by tightening this adjusting nut
83
. Furthermore, a pulley (not shown) is fixed to the front-side end of the shaft
5
.
A thrust flange
40
that transmits the rotation of the shaft
5
to the wobble plate
10
is fixed to the shaft
5
. This thrust flange
40
is supported by the inner wall surface of the front housing via a thrust bearing
33
a
. The thrust flange
40
and the wobble plate
10
are connected to each other via a hinge mechanism
41
. The wobble plate
10
is mounted on the shaft
5
so that the wobble plate
10
can slide on the shaft
5
and can, at the same time, incline with respect to a virtual surface at right angles to the shaft
5
.
The hinge mechanism
41
is composed of a bracket
10
e
provided on a front surface
10
c
of wobble plate
10
, a linear guide groove
10
f
provided in this bracket
10
e
, and a rod
43
screw-threaded onto a wobble plate-side side surface
40
a
of the thrust flange
40
. The longitudinal axis of the guide groove
10
f
is inclined to the front surface
10
c
of wobble plate
10
at a prescribed angle. A spherical portion
43
a
of the rod
43
is slidably fitted into the guide groove
10
f.
Next, the control valve
100
for variable capacity compressors in this embodiment will be explained in detail by referring to
FIGS. 3 and 4
.
FIG. 3
is a longitudinal sectional view of a control valve
100
built in a variable capacity compressor
1
and
FIG. 4
is a longitudinal sectional view of the details of the control valve shown in FIG.
3
.
The control valve
100
is disposed in the spaces
84
,
85
of the rear housing
3
of the variable capacity compressor
1
shown in
FIGS. 1 and 2
with an airtight state maintained via O-rings
121
a
,
121
b
,
131
b.
As shown in
FIG. 4
, the control valve
100
is composed of a control valve body
120
, a solenoid excitation part
130
, and a pressure-sensitive part
145
. The solenoid excitation part
130
is disposed in the middle, the control valve body
120
is disposed on the upper side of the solenoid excitation part
130
, and the pressure-sensitive part
145
is disposed on the lower side of the solenoid excitation part
130
.
The solenoid excitation part
130
is provided with a solenoid housing
131
along the periphery thereof. In the interior of this solenoid housing
131
, a solenoid
131
A, a plunger
133
that moves vertically by the excitation of the solenoid
131
A, an attraction element
141
, and a stem
138
are disposed. A plunger chamber
130
a
that houses the plunger
133
communicates with a suction coolant port
129
provided in the control valve body
120
.
The pressure-sensitive part
145
is arranged on the lower side of the solenoid housing
131
. In a pressure-sensitive chamber
145
a
formed in this pressure-sensitive part
145
, a bellows
146
and a spring
159
that operate the plunger
133
via the stem
138
, etc are disposed.
The control valve body
120
is provided with a valve chamber
123
. In this valve chamber
123
, a valve element
132
that performs opening and closing operations by the plunger
133
is disposed. A coolant gas at a high discharge pressure Pd flows into this valve chamber
123
via a passage
81
and a discharge coolant port
126
. On the bottom surface of the valve chamber
123
, a valve hole
125
that communicates with a crankcase coolant port
128
is formed. The space in the upper part of the valve chamber
123
is blocked by a stopper
124
. In the center part of this stopper
124
, a pressure chamber
151
opposite to the valve hole
125
is formed. This pressure chamber
151
is a bottomed pit having the same sectional area with the valve hole
125
. This pressure chamber
151
, which is a bottomed pit, functions also as a spring-housing chamber
151
a
and, on the bottom thereof, a valve-closing spring
127
for urging the valve element
132
toward the bottom of the valve chamber
123
is disposed.
The valve element
132
is composed of an upper portion
132
a
, an enlarged valve element portion
132
b
, a small-diameter portion
132
c
, and a lower portion
132
d
. The valve element
132
takes on the shape of a bar as a whole and the upper portion
132
a
and lower portion
132
d
thereof have a sectional area equal to that of the valve hole
125
. The upper portion
132
a
is fitted onto and supported by the stopper
124
having the pressure chamber
151
. The enlarged valve element portion
132
b
is arranged in the valve chamber
123
. Within the valve hole
125
, the small-diameter portion
132
c
is opposed to a crankcase coolant port
128
that communicates with the crankcase (crankcase pressure Pc). The lower portion
132
d
is fitted onto and supported by the interior of the control valve body
120
, and the lower end thereof is inserted into the plunger chamber
130
a
, into which a coolant gas at the suction pressure Ps is introduced, and is in contact with the plunger
133
. For this reason, when the plunger
133
moves up and down, the valve element
132
moves up and down, where by a gap between the enlarged valve element portion
132
b
of valve element
132
and a valve seat
125
a
formed in the upper surface of the valve hole
125
is adjusted.
And the suction pressure Ps at a low temperature that flows into the plunger chamber
130
a
is introduced into the pressure-sensitive part
145
, which will be described later, and at the same time this suction pressure Ps is also introduced into a suction-pressure introduction space
85
between the rear housing
3
and a solenoid housing
131
(FIG.
3
). This suction-pressure introduction space
85
is sealed by an O-ring
131
b
provided on a projection
131
a
formed on the side of the solenoid housing
131
, whereby the cooling of the whole side of the solenoid housing
131
is accomplished by a low-temperature coolant gas from the suction chamber
13
.
In the interior of the solenoid housing
131
, which is caulked and connected to the control valve body
120
, the plunger
133
that contact-fixes the valve element
132
as shown in
FIG. 4
is disposed. This plunger
133
is slidably housed in a pipe
136
attached to an end of the control valve body
120
via an O-ring
134
a.
A stem
138
is fixed to the plunger
133
, with the upper portion
138
A thereof being inserted in a housing hole
137
formed at the lower end of the plunger
133
. On the other hand, the lower portion
138
B of the stem
138
, which passes through an upper-end-housing hole
142
of the attraction element
141
and protrudes from the side of a lower-end-housing hole
143
, can slide with respect to the attraction element
141
. Between the plunger
133
and the upper-end-housing hole
142
of the attraction element
141
, there is provided a valve-opening spring
144
that urges in a direction in which the valve-opening spring
144
detaches the plunger
133
from the side of the attraction element
141
.
Also, the stem
138
is arranged in such a manner that the lower portion
138
B thereof can come into contact with or leave a first stopper
147
within the bellows
146
disposed in a pressure-sensitive chamber
145
a
. Within the bellows
146
, a second stopper
148
, in addition to this first stopper
147
, is provided. Between a flange
149
of the first stopper
147
and the lower-end-housing hole
143
of the attraction element
141
, there is provided a spring
150
that urges in a direction in which the spring
150
detaches the first stopper
147
from the side of the attraction element
141
.
When the suction pressure Ps in the pressure-sensitive chamber
145
a
increases, the bellows
146
contracts and the first stopper
147
comes into contact with the second stopper
148
. At this point of time, the contracting action (displacement) of the bellows
146
is controlled. The maximum amount of displacement of this bellows
146
is set so that it becomes smaller than the maximum amount of fit between the lower portion
138
B of stem
138
and the first stopper
147
of bellows
146
.
Incidentally, a cord
158
capable of feeding a solenoid current that is controlled by a control computer (not shown) is connected to the solenoid
131
A (FIG.
3
).
Also, the stopper
124
that blocks the valve chamber
123
is provided with a transverse hole
153
that communicates with the pressure chamber
151
, as shown in FIG.
4
. This transverse hole
153
provides communication between a gap
139
formed by the stopper
124
and control valve body
120
and the pressure chamber
151
. On the other hand, a cancel hole
155
that provides communication between the gap
139
and the plunger chamber
130
a
into which a coolant gas at the suction pressure Ps flows is formed in the control valve body
120
.
The structure of the plunger
133
will be described below by referring to
FIG. 5A
(a perspective view) and
FIG. 5B
(a longitudinal sectional view).
The plunger
133
comprises a head
133
A and a barrel
133
B. The head
133
A faces the lower end of the control valve body
120
. On the other hand, the barrel
133
B slides within the pipe
136
. Incidentally, the upper portion
138
A of the stem
138
passes through the lower end
133
C of the barrel
133
B.
The head
133
A of the plunger
133
has an almost cylindrical shape with a smaller diameter than the barrel
133
B and is in contact with the lower end of the control valve body
120
. Furthermore, as shown in
FIG. 5A
, this head
133
A has an upper end surface
133
Aa that is in contact with the lower portion
132
d
of the valve element
132
. At the center of this upper end surface
133
Aa, a first coolant vent
133
d
that extends in the longitudinal (z axis) direction of the plunger
133
is formed. Furthermore, on the side surface of the head
133
A, as shown in
FIG. 5B
, there is provided a second coolant vent
133
c
that extends while intersecting the longitudinal (z axis) direction of the plunger
133
. These first and second coolant vents
133
d
,
133
c
communicate with each other in the head
133
A of the plunger
133
. The first coolant vent
133
d
has a radius about half the radius of the second coolant vent
133
c.
The barrel
133
B of the plunger
133
has an almost cylindrical shape and, on the outer surface thereof, a slit
133
a
that extends parallel to the longitudinal (z axis) direction of the plunger
133
is formed. A coolant at the suction pressure Ps is introduced by this slit
133
a
into the pressure-sensitive part
145
. On the other hand, in the interior of the barrel
133
B of plunger
133
, as shown in
FIG. 5B
, there is provided a third coolant vend
133
b
that extends in the longitudinal (z axis) direction of the plunger
133
. This third coolant vent
133
b
and the second coolant vent
133
c
communicate with each other in the head
133
A of the plunger
133
. The third coolant vent
133
b
and second coolant vent
133
c
have the same inside diameter. Therefore, the diameter of the first coolant vent
133
d
is smaller than the diameter of the second and third coolant vents
133
c
,
133
b.
The lower end
133
C of the barrel
133
B of plunger
133
has a shape tapering toward a lower end surface
133
C
a
of the plunger
133
, and, in the interior thereof, a housing hole
137
that receives the upper portion
138
A of the stem
138
is formed. This housing hole
137
communicates with the third coolant vent
133
b
. Therefore, between the upper end surface
133
Aa and lower end surface
133
Ca of plunger
133
, there is provided communication by the first coolant vent
133
d
and the third coolant vent
133
b.
An example of structure of the stem
138
will be described below by referring to
FIG. 6A
(a perspective view) and
FIG. 6B
(a longitudinal sectional view).
The stem
138
is composed of an upper portion
138
A, which is passed through the housing hole
137
of the plunger
133
, and a lower portion
138
B. The upper portion
138
A has an almost cylindrical shape and a hollow part formed therein in the longitudinal (z axis) direction of the stem
138
functions as a coolant vent
138
b
. On the other hand, the lower portion
138
B has an almost cylindrical shape with a smaller diameter than the upper portion
138
A, and a hollow part formed therein in the longitudinal (z axis) direction of the stem
138
functions as a coolant vent
138
c.
Also, on the outer surface of the stem
138
(including the upper portion
138
A and lower portion
138
B), a slit
138
a
that extends parallel to the longitudinal (z axis) direction of the stem
138
is formed. Because the stem
138
is provided with this slit
138
a
, it is possible to prevent the sticking of the outer peripheral surface of the stem
138
to the inner peripheral surface of the housing hole
137
for receiving the plunger
133
and the sticking of the outer peripheral surface of the stem
138
to the inner peripheral surface of the attraction element
141
.
Next, another example of stem structure will be described below by referring to
FIG. 7
(a perspective view).
A stem
140
is composed of a head
140
A and a barrel
140
B. On the side surfaces of the head
140
A and barrel
140
B, respectively, there are formed flat portions
140
a
,
140
b
. That is, the section of the head
140
A and barrel
140
B has an almost half-moon shape. Because the stem
140
(including the head
140
A and the barrel
140
B) is provided, on the outer surface thereof, with flat portions
140
a
,
140
b
as described above, a gap is generated each between the outer peripheral surface of the stem
140
and the inner peripheral surface of the housing hole
137
for receiving the plunger
133
and between the outer peripheral surface of the stem
140
and the inner peripheral surface of the attraction element
141
, whereby it is possible to prevent the sticking of the outer peripheral surface of the stem
138
to the inner peripheral surface of the housing hole
137
for receiving the plunger
133
and the sticking of the outer peripheral surface of the stem
138
to the inner peripheral surface of the attraction element
141
.
As described above, because the stem
138
is provided with the slit
138
a
(or because the stem
140
is provided with the flat portions
140
a
,
140
b
), it is possible to prevent the sticking of the stem
138
(or
140
) to the plunger
133
and attraction element
141
. Furthermore, in a case where the plunger
133
is located in a place lower than the center position of the compressor
1
, even when a coolant gas having a low suction pressure Ps is introduced to the side of the bellows
146
below the plunger
133
and a coolant pool is formed on the lower side of the plunger
133
, it is possible to prevent phenomena such as delays in the operation of the plunger and stem, because it becomes easy for the coolant that has collected to move.
Next, the operation of the variable capacity compressor
1
in which the control valve
100
of this embodiment is built will be described below.
The rotary power of a car-mounted engine is transmitted to the shaft
5
from a pulley (not shown) via a belt (not shown). The rotary power of the shaft
5
is transmitted to the wobble plate
10
via the thrust flange
40
and hinge mechanism
41
thereby to rotate the wobble plate
10
.
By the rotation of the wobble plate
10
, the shoe
50
performs relative rotation on the sliding surface
10
a
of the wobble plate
10
. As a result, the piston
7
performs linear reciprocating motions and changes the volume of the compression chamber
82
in the cylinder bore
6
. According to this volume change of the compression chamber
82
the suction, compression and discharge processes of a coolant gas are sequentially performed and the coolant gas of a volume corresponding to the inclination angle of the wobble plate
10
is delivered.
First, in the case of a large thermal load, the flow of the coolant gas from the discharge chamber
12
to the crankcase
8
is blocked and, therefore, the pressure of crankcase
8
drops and a force generated on the rear surface of the piston
7
during the compression process decreases. For this reason, the sum total of forces generated on the rear surface of the piston
7
drops below the sum total of forces generated on the front surface (top surface) of the piston
7
. As a result, the inclination angle of the wobble plate
10
increases.
When the pressure of discharge chamber
12
rises and the pressure difference between the discharge chamber
12
and the crankcase
8
becomes not less than a specified value, with the result that the pressure of the coolant gas in the discharge chamber
12
acting on the lower side of the spool valve
31
exceeds the sum total of the pressure of the coolant gas in the crankcase
8
acting on the upper side of the spool valve
31
and the urging force of the spring
32
, then the spool valve
31
moves in an opening direction and the discharge passage
39
opens (FIG.
1
), as a result of which the coolant gas in the discharge chamber
12
flows out of the discharge port
1
a
into a capacitor
88
.
Incidentally, when the inclination angle of the wobble plate
10
changes from a minimum to a maximum, the boss
10
b
of the wobble plate
10
leaves the hole
58
c
of the ring
9
and the first passage
58
is fully opened, with the result that the coolant gas in the crankcase
8
flows into the suction chamber via the first passage
58
. For this reason, the pressure of the crankcase
8
drops. Furthermore, when the passage area of the first passage
58
becomes a maximum, the coolant gas scarcely flows from the third passage
60
into the suction chamber
13
.
When in this manner the thermal load increases and the solenoid
131
A of the control valve
100
is excited, the plunger
133
is attracted toward the attraction element
141
and the valve element
132
with which the plunger
133
is in contact moves in a direction in which the valve element
132
closes the valve opening, whereby the flow of the coolant gas into the crankcase
8
is blocked.
On the other hand, the low-temperature coolant gas is introduced into the pressure-sensitive part
145
from the side of the passage
80
that communicates with the suction chamber
13
via the suction coolant port
129
of the control valve body
120
and the plunger chamber
130
a
. As a result, the bellows
146
of the pressure-sensitive part
145
displaces on the basis of the coolant gas pressure that is the suction pressure Ps of the suction chamber
13
. The displacement of this bellows
146
is transmitted to the valve element
132
via the stem
138
and plunger
133
. That is, the opening of the valve hole
125
by the valve element
132
is determined by the attractive force of the solenoid
131
A, the urging force of the bellows
146
and the urging force of the valve-closing spring
127
and of the valve-opening spring
144
.
And when the pressure in the pressure-sensitive chamber
145
a
(the suction pressure Ps) increases, the bellows
146
contracts and the movement of the valve element
132
responds to this displacement of the bellows
146
(the direction of displacement of the valve element
132
corresponds to the direction of attraction of the plunger
133
by the solenoid
131
A), whereby the opening of the valve hole
125
is reduced. As a result, the volume of the high-pressure coolant gas introduced from the discharge chamber
12
into the valve chamber
123
decreases (the crankcase pressure Pc drops) and the inclination angle of the wobble plate
10
increases (FIG.
1
).
Also, when the pressure in the pressure-sensitive chamber
145
a
drops, the bellows
146
is expanded by the restoring force of the spring
159
and the bellows
146
itself and the valve element
132
moves in a direction in which the valve element
132
increases the opening of the valve hole
125
. As a result, the volume of the high-pressure coolant gas introduced into the valve chamber
123
increases (the crankcase pressure Pc increases) and the inclination angle of the wobble plate
10
in the state shown in
FIG. 1
decreases.
In contrast to this, when the thermal load is small, the high-pressure coolant gas flows from the discharge chamber
12
into the crankcase
8
, thereby raising the pressure of the crankcase
8
. As a result, a force generated on the rear surface of the piston
7
during the compression process increases and the sum total of forces generated on the rear surface of the piston
7
exceeds the sum total of forces generated on the front surface of the piston
7
, thereby reducing the inclination angle of the wobble plate
10
.
When the pressure difference between the discharge chamber
12
and the crankcase
8
becomes not more than a specified value and the sum total of the pressure of the crankcase
8
acting on the upper side of the spool valve
31
and the urging force of the spring
32
exceeds the pressure of the coolant gas in the discharge chamber
12
acting on the lower side of the spool valve
31
, then the spool valve
31
moves in a closing direction and blocks the discharge passage
39
(FIG.
2
), thereby blocking the outflow of the coolant gas from the discharge port
1
a
into the capacitor
88
.
Incidentally, when the inclination angle of the wobble plate
10
becomes a minimum from a maximum, the boss
10
b
of the wobble plate
10
almost blocks the hole
58
c
of the ring
9
and substantially reduces the passage sectional area of the first passage
58
. However, because the coolant gas in the crankcase
8
flows out toward the suction chamber
13
via the third passage
60
, an excessive pressure increase in the crankcase
8
is suppressed and it becomes possible for the coolant gas in the compressor
1
to circulate. That is, the coolant gas flows through the suction chamber
13
, compression chamber
82
, discharge chamber
12
, second passage
57
, crankcase
8
and third passage
60
, and returns to the suction chamber
13
again.
In this embodiment, the structure is such that the pressure of crankcase
8
is caused to act on one side of the spool valve
31
that functions as the discharge control valve, while the pressure of discharge chamber
12
is caused to act on the other side, and the spring
32
having a relatively small spring force is used to urge the spool valve
31
in a direction in which the spring
32
closes the spool valve
31
. Therefore, when the thermal load decreases and the pressure of discharge chamber
12
drops gradually, the stroke of the piston
7
becomes a minimum (an extra-small load) and the spool valve
31
maintains an open state until the wobble plate
10
reduces the passage area of the first passage
58
.
When in this manner the thermal load decreases and the solenoid
131
A is demagnetized, the attractive force to the plunger
133
disappears, with the result that the plunger
133
moves in a direction in which the plunger
133
leaves the attraction element
141
due to the urging force of the valve-opening spring
144
and the valve element
132
moves in a direction in which the valve element
132
opens the valve hole
125
of the control valve body
120
, whereby the inflow of the coolant gas into the crankcase
8
is promoted.
When the pressure in the pressure-sensitive part
145
rises, the bellows
146
contracts and the opening of the valve element
132
decreases. However, because the lower portion
138
B of the stem
138
can come close to and away from the first stopper
147
of the bellows
146
, the displacement of the bellows
146
will not have an effect on the valve element
132
.
As described above, the control valve of this embodiment
100
is constituted by the solenoid excitation part
130
, which is provided, at the middle thereof, with the plunger
133
moving vertically by the excitation of the solenoid
131
A, the pressure-sensitive part
145
, in which the bellows
146
operating synchronously with the plunger
133
via the stem
138
, etc. is disposed on the lower side of the solenoid excitation part
130
, and the control valve body
120
that has the valve chamber
123
in which the valve element
132
operating synchronously with the plunger
133
, etc., are disposed on the upper side of the solenoid housing
131
. Therefore, because the pressure-sensitive chamber
145
a
and the solenoid
131
A are disposed in close vicinity to each other, the point of application by the attraction of the solenoid
131
A and the point of application by the bellows
146
approach each other, with the result that when the valve element
132
and stem
138
move simultaneously in a closing direction, the occurrence of backlash between them is minimized as far as possible.
Now, TABLE 1 shows measured values obtained in an experiment on the load of sticking between the upper end surface
133
Aa of the head
133
A of the plunger
133
and the lower end of the control valve body
120
.
TABLE 1
|
|
No.
Tensile load
Dead weight
Sticking load
|
|
|
1
9.5
205
13.9
191.1
|
2
6.0
40
12.8
27.2
|
3
4.0
14
12.6
1.4
|
4
9.5
145
13.6
131.4
|
5
4.0
11.7
11.7
0.0
|
|
In TABLE 1, No. 1 to No. 3 denote a plunger provided with no coolant vent. Nos. 4 and 5 denote a plunger provided with the first coolant vent
133
d
(refer to
FIG. 5B
) and the second coolant vent
133
c
or the third coolant vent
133
b
that communicates with the first coolant vent
133
d.
In this experiment, plungers
133
with different diameters of upper end surface
133
Aa of head
133
A were used. After attaching the upper end surface
133
Aa of plunger
133
to an oil-applied flat plate at an atmosphere temperature of 20° C., an actual force (tensile force) necessary for detaching the plunger
133
was measured and by subtracting the dead weight of the plunger
133
from this tensile load, the sticking load of the plunger
133
(unit: gram) was found. The result is shown in TABLE 1. This sticking load is equivalent to the resistance value during the detaching of the plunger
133
from the flat plate.
From TABLE 1, it is apparent that the sticking load can be reduced to about {fraction (1/130)} by reducing the diameter φ of the upper end surface
133
Aa of the plunger to about ½ (refer to Nos. 1 and 3).
In particular, in the case of the plunger No. 5, the sticking load becomes almost zero and it is apparent that the plunger
133
of this structure ensures positive valve-closing operation, etc. because during the closing of the valve element
132
, the coolant does not collect any more between the upper end surface
133
Aa of the plunger and the lower portion
132
d
of the valve element
132
.
From the above-described results, it is apparent that by reducing the diameter of the head
133
A of plunger
133
in comparison with the diameter of the barrel
133
B, the contact area between the upper end surface
133
Aa of the head
133
A of plunger
133
and the lower end of the control valve body
120
(refer to
FIG. 4
) is reduced, whereby the sticking of the plunger
133
to the control valve body
120
is suppressed, making it possible to operate the valve element
132
smoothly.
Also, by installing, as shown in
FIG. 5B
, the third coolant vent
133
b
and first coolant vent
133
d
that extend in the longitudinal direction of the plunger
133
, the coolant gas is prevented from collecting between the upper end surface
133
Aa of the plunger and the lower portion
132
d
of the valve element
132
even during the closing of the valve element
132
. In addition, by installing the second coolant vent
133
c
that radially extends in the plunger
133
, the movement of the coolant gas in the plunger chamber
130
a
is made smooth.
Therefore, by forming, in the plunger
133
, the first and third coolant vents
133
d
and
133
b
that extend in the longitudinal direction thereof and the second coolant vent
133
c
that extends in the radial direction intersecting these two coolant vents and, at the same time, by making the diameter of the third coolant vent
133
b
and the diameter of the second coolant vent
133
c
equal to each other thereby to provide communication therebetween, whereby it is ensured that even during the closing of the valve element
132
, the cooling gas does not collect between the upper end surface
133
Aa of the plunger and the lower portion
132
d
of the valve element
132
and, at the same time, the coolant gas that has collected below the plunger
133
can be easily moved to the upper portion of the plunger chamber
130
a
. For this reason, delays in the operation of the plunger
133
and the like do not occur any
Now, TABLE 2 shows measured values obtained in an experiment on the damper effect of oil and the viscous sliding resistance between the inner peripheral surface of the pipe
136
and the outer peripheral surface of the plunger
133
.
TABLE 2
|
|
No.
Dead weight
Sliding resistance
|
|
|
Tensile load
|
1
506
14.0
492.0
|
2
250
13.8
236.2
|
3
20
11.7
8.3
|
Compressive load
|
1
107
14.0
121.0
|
2
104
13.8
117.8
|
3
0
11.7
11.7
|
|
In TABLE 2, No. 1 denotes a plunger
133
in which one slit
133
a
extending parallel to the longitudinal direction of the plunger is formed on the side surface of the barrel
133
B thereof, No. 2 denotes a plunger
133
in which two above-described slits
133
a
are formed on the side surface of the barrel
133
B thereof, and No. 3 denotes a plunger
133
which is provided with the first, second and third coolant vents
133
d
,
133
c
and
133
b
and in which one slit
133
a
is formed on the side surface of the barrel
133
B thereof.
In this experiment, after inserting the plunger
133
into a pipe containing oil at an atmosphere temperature of 20° C., a tensile load or compressive load necessary for vertically moving the plunger
133
was measured and by subtracting the dead weight of the plunger from the measured value or adding the dead weight of the plunger to the measured value, a force necessary for moving the plunger
133
(sliding resistance, unit: gram) was found. The result is shown in TABLE 2.
The tensile load (a force necessary for pulling up the plunger
133
in a direction in which the valve element
132
opens) of the of No. 2 plunger
133
is reduced to about ½ of the tensile load of the No. 1 plunger. It can be understood that this is because the No. 2 plunger
133
has more slits than the No. 1 plunger
133
.
The tensile load of the No. 3 plunger
133
is reduced to about {fraction (1/60)} of that of the No.1 plunger
133
, and the compressive load (a force necessary for pushing down the plunger
133
in a direction in which the valve element
132
closes) of the No. 3 plunger is reduced to about {fraction (1/10)} of that of the No. 1 plunger
133
.
Therefore, by forming the slit
133
a
on the side surface of the barrel
133
B of plunger
133
, it is possible to destroy the full-circumference pressure balance between the inner peripheral surface of the pipe
136
and the outer peripheral surface of the plunger
133
, whereby the sticking of the plunger
133
can be prevented and the valve element can be smoothly moved.
Furthermore, by forming the coolant vents
133
b
,
133
c
,
133
d
in the interior of the plunger
133
, it is possible to easily move the coolant gas that has collected to the upper portion of the plunger chamber
130
a
, whereby delays in the operation of the plunger
133
and the like can be prevented.
Also, by forming, in the interior of the stem
138
, the coolant vents
138
b
,
138
c
that extend in the longitudinal direction thereof, it becomes easy to move the cooling gas that has collected below the stem
138
to the upper portion of the plunger chamber
130
a
via the second and third coolant vents
133
c
,
133
d
of the plunger
133
, whereby delays in the operation of the stem
138
and the like can be prevented.
Furthermore, by forming the slit
138
a
on the side surface of the stem
138
(
FIG. 5A
) or by making the section of the stem
140
half-mooned and not circular (
FIG. 7
) thereby to prevent the sticking of the outer peripheral surface of the stem
138
,
140
to the inner peripheral surfaces of the plunger
133
and attraction element
141
, whereby the motion of the plunger
133
and valve element
132
can be made smooth.
Next, a control valve
100
in the second embodiment of the present invention will be described below by referring to FIG.
8
.
Because the control valve
100
for variable capacity compressors of this embodiment has features mainly in the structure of a cancel hole and a pressure-sensitive part, these points will be described below in detail.
A valve element
132
of the control valve
100
is composed of an upper portion
132
a
, an enlarged valve element portion
132
b
, a small-diameter portion
132
c
, and a lower portion
132
d
. The upper portion
132
a
is housed in a pressure chamber
151
. The enlarged valve element portion
132
b
is arranged in a valve chamber
123
. The small-diameter portion
132
c
is present in a valve hole
125
and is opposed to a crankcase coolant port
128
. The lower portion
132
d
is fitted into the interior of a control valve body
120
and the lower end thereof is inserted into a plunger chamber
130
a
, into which a cooling gas at the suction pressure Ps is introduced, and is in contact with a plunger
133
.
Furthermore, the valve element
132
is, at the center thereof, provided with a cancel hole
132
e
in the longitudinal axial direction. The pressure chamber
151
and the plunger chamber
130
a
communicate with each other via this cancel hole
132
e.
In the control valve
100
of the above-described first embodiment, as shown in
FIG. 4
, the communication between the pressure chamber
151
and the plunger chamber
130
a
is provided by the transverse hole
153
formed in the stopper
124
and the cancel hole
155
formed in the control valve body
120
. In contrast to this, in the control valve
100
of the second embodiment, by forming the cancel hole
132
e
in the valve element
132
itself in such a manner that the cancel hole
132
e
passes through the valve element
132
from the upper portion
132
a
thereof to the lower portion
132
d
, communication is provided between the pressure chamber
151
and the plunger chamber
130
a.
Accordingly, the coolant gas at the suction pressure Ps in the plunger chamber
130
a
is introduced into the pressure chamber
151
via the cancel hole
132
e
. Then, the valve element
132
receives the suction pressure Ps from both sides of each of the upper portion
132
a
and lower portion
132
d
thereof. In addition, because the upper portion
132
a
and lower portion
132
d
of the valve element
132
have the same sectional area, the suction pressure Ps received from both sides of the upper portion
132
a
and lower portion
132
d
thereof is balanced and canceled out each other, with the result that the valve element
132
is not virtually affected by the discharge pressure Pd.
Also, in this valve element
132
, its portion near the crankcase coolant port
128
having the crankcase pressure Pc is formed as the small-diameter portion
132
c
and, therefore, when the enlarged valve element portion
132
b
of the valve element
132
is seated on a valve seat
125
a
, an unnecessary force will not act on the valve element
132
even when the valve element
132
is subjected to the pressure Pc in the crankcase because the upward and downward forces acting on the valve element
132
are balanced.
As described above, in the control valve
100
of this embodiment, pressure balance is always maintained above and under the valve element
132
and, therefore, it is possible to improve the valve opening and closing accuracy and besides working is easy compared with a case where the cancel hole is formed in the control valve body
120
, making it possible to further reduce the manufacturing cost. Incidentally, this cancel hole may be formed in the valve element
132
of the control valve
100
of the first embodiment.
Also, an attraction element
141
of the control valve
100
of this embodiment, unlike that of the first embodiment, is in the form of a cylinder the bottom of which faces the plunger
133
, and a bellows
146
is disposed in a pressure-sensitive chamber
145
a
formed in the interior of the cylinder. For this reason, a pressure-sensitive part
145
is formed in the inside of the attraction element
141
and hence scarcely protrude to the outside of a solenoid excitation part
130
. In addition, compact design of the control valve
100
can be ensured by reducing the diameter of the solenoid excitation part
130
. Incidentally, the bellows
146
is adjusted by the position adjustment of the stopper
148
from the outside.
Furthermore, because the plunger
133
and attraction element
141
of the control valve
100
of this embodiment are provided, in the longitudinal axial direction thereof, with coolant-introduction and coolant-vent holes
133
e
and
141
a
, the coolant gas at the suction pressure Ps in the plunger chamber
130
a
is introduced into the pressure-sensitive chamber
145
a.
Next, a control valve
100
in the third embodiment of the present invention will be described below by referring to FIG.
9
.
The control valve
100
of this embodiment has features mainly in the structure of an attraction element and a pressure-sensitive part. An attraction element
141
of the control valve
100
is constituted by a cylindrical portion
141
b
engaged on the inside of a solenoid excitation part
130
, a cover portion
141
c
press-fitted at the upper end of the cylindrical portion
141
b
, and an adjusting screw
157
engaged on the lower side of the cylindrical portion
141
b
. A pressure-sensitive part
145
is provided in the inside of the cylindrical portion
141
b.
The cylindrical portion
141
b
of the attraction element
141
is, from the lower side thereof, engaged to the adjusting screw
157
and, on the other hand, from the upper side thereof, a stopper
148
, a spring
159
, a bellows
146
and a flange
149
of the stopper
148
, and a spring
150
are installed. At the upper end of the cylindrical portion
141
b
, a cover portion
141
c
is press-fitted. And a joint between the cylindrical portion
141
b
and the cover portion
141
c
is TIG welded and a pressure-sensitive chamber
145
a
is formed inside the attraction element
141
. For this reason, compact design can be ensured by the shortening in the longitudinal axial direction of the control valve
100
. Incidentally, the adjusting screw
157
is intended for use in the adjustment of the displacement of the bellows
146
by the adjustment of the position of the stopper
148
from the outside.
A plunger
133
is provided with a coolant vent
133
f
in the interior thereof in the longitudinal direction and is also provided with a slit
133
a
for introducing the coolant at the suction pressure Ps into the pressure-sensitive part
145
in the outer surface thereof in the longitudinal direction. Furthermore, a stem
140
having an almost half-moon section as shown in
FIG. 7
is used. Therefore, the coolant gas at the suction pressure Ps in the plunger chamber
130
a
is introduced into the pressure-sensitive part
145
via the slit
133
a
of plunger
133
and the stem 140.
Furthermore, a control valve body
120
and the solenoid excitation part
130
are, unlike those of the control valve
100
of the second embodiment, connected together via a pipe
136
and a spacer, by performing caulking from the side of the control valve body
120
. Incidentally, a gap between the control valve body
120
and the solenoid excitation part
130
is sealed by means of packing
134
b.
In the control valve for variable capacity compressors according to the present invention, as described above with respect to each of the embodiments, the opening and closing accuracy of the valve hole can be improved by eliminating an adverse effect of the operation of the valve element based on a coolant gas. Also, clutch-less operation of a compressor can be maintained by the improvement of the opening and closing accuracy of the valve hole.
Furthermore, the compact design of the control valve can be ensured by arranging the pressure-sensitive part within the attraction element.
Claims
- 1. A control valve for variable capacity compressors, comprising:a solenoid excitation part having a solenoid and a plunger moving vertically by the excitation of said solenoid; and a control valve body disposed on the upper side of said solenoid excitation part and having a valve chamber provided with a valve hole on the bottom surface thereof, a pressure chamber disposed above said valve chamber, and a valve element disposed within said valve chamber and performing opening and closing operations by said plunger; wherein, the upper end of the valve element of said control valve body is inserted in said pressure chamber, while the lower end of said valve element is inserted in a plunger chamber of said solenoid excitation part, said plunger chamber and said pressure chamber communicate with each other through a cancel hole formed in said valve element.
- 2. A control valve for variable capacity compressors, comprising:a solenoid excitation part having a solenoid and a plunger moving vertically by the excitation of said solenoid; a control valve body; an attraction element provided on the lower side of the plunger of said solenoid excitation part; and a pressure-sensitive element formed on the inner side of said attraction element.
- 3. The control valve for variable capacity compressors according to claim 2, wherein said attraction element is in the form of a cylinder with a bottom opposed to said plunger.
- 4. The control valve for variable capacity compressors according to claim 2, wherein said attraction element comprises a cylindrical portion to be engaged with the inner side of said solenoid excitation part and a cover portion to be press-fitted to the upper end of said cylindrical portion.
- 5. The control valve for variable capacity compressors according to claim 1 or 2, wherein said plunger is provided with a coolant vent extending in the longitudinal axial direction.
- 6. The control valve for variable capacity compressors according to claim 2, wherein said plunger is provided with a slit, on the side surface thereof, extending in the longitudinal axial direction.
- 7. The control valve for variable capacity compressors according to claim 2, wherein said solenoid excitation part is provided with a stem having a substantially half-moon section for transmitting the motion of said pressure-sensitive part to said plunger.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2001-108951 |
Apr 2001 |
JP |
|
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