Information
-
Patent Grant
-
6702251
-
Patent Number
6,702,251
-
Date Filed
Monday, February 25, 200222 years ago
-
Date Issued
Tuesday, March 9, 200420 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
-
International Classifications
-
Abstract
A control valve for a variable displacement compressor is provided. A retainer cylinder in the control valve includes a first cylindrical member made of non-magnetic material and a second cylindrical member having a bottom portion made of magnetic material. A shim is intervened a bottom surface of a plunger and inner bottom surface of the second cylindrical member. The retainer cylinder has good magnetic permeability between a coil and the plunger, even though the wall of the cylinder thickens to improve the withstanding pressure to internal refrigerant pressure.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a displacement control valve controlling the discharge capacity of variable displacement compressors that are included in the refrigerant circuit of air conditioners.
A typical control valve incorporates a solenoid valve, which is externally controllable.
FIG. 4
shows an example of an electromagnetic actuator portion
101
in the control valve. A retainer cylinder
102
having a bottom portion is disposed in the electromagnetic actuator portion
101
. A stationary core
103
and a movable core (plunger)
104
are disposed in the retainer cylinder
102
. A coil
105
is disposed at outside of the retainer cylinder
102
. Electric current through the coil
105
generates electromagnetic force between stationary core
103
and movable core
104
. The electromagnetic force is applied to the movable core
104
to slide along an inner cylindrical surface of the retainer cylinder
102
. This movement is transmitted to a valve body (not shown in the drawing) through a rod
106
. The displacement of valve body based on the movable core
104
serves to adjust the opening degree of the valve to control a discharge displacement of the compressor.
The discharge displacement is achieved by, for example, changing a pressure in a crank chamber in which a swash plate is disposed. To change the pressure in the crank chamber, the control valve regulates the degree of the opening in a pressurizing passage, which supplies a pressurized refrigerant gas from the discharge chamber to the crank chamber.
Recently, air conditioners utilizing carbon dioxide as a refrigerant gas has become generally used. In such system, the pressure of the refrigerant gas is much higher than that of a conventional CFC (chlorofluorocarbon) gas. Accordingly, in order to control the displacement of the compressor that deal with carbon dioxide, it is necessary to increase the withstanding pressure of the control valve as well as the compressor. For example, a cylindrical wall of the retainer cylinder
102
may be thick to resist the internal pressure.
However, the retainer cylinder
102
is made of non-magnetic material to prevent magnetic flux from leaking out between the stationary core
103
and the movable core
104
. Therefore, if the wall of the retainer cylinder
102
is thickened to resist the high internal pressure sufficiently, it will be harder for the magnetic flux to go through between the coil
105
and the movable core
104
.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a control valve, especially control valve in variable displacement compressor, in which a magnetic flux can easily go through between a coil and movable core even if a wall of the retainer cylinder is thickened in order to increase its withstanding pressure.
Another objective of the present invention is a method of adjusting the tolerance of the movable extent in the control valve, which is caused during its manufacture.
To achieve the foregoing, the present invention provides a control valve for operating fluid flow that goes through the control valve. The control valve includes a retainer cylinder, a stationary core, a movable core, a shim, a coil and a valve body. The retainer cylinder includes a first cylindrical member made of non-magnetic material and a second cylindrical member made of magnetic material, the second cylindrical member having a bottom portion. The stationary core is disposed in the retainer cylinder. The movable core is disposed in the retainer cylinder, and located between the stationary core and the bottom portion of the second cylindrical member. The shim is made of non-magnetic material, and disposed in the retainer cylinder and located between the movable core and the bottom portion of second cylindrical member. The coil is disposed around the retainer cylinder. The valve body is movably linked with the movable core. The valve body is actuated by a movement of the movable core in an elongated direction of the retainer cylinder. The movement of the movable core is based on an electromagnetic force that is generated between the stationary core and the movable core in accordance with an electric current supplied to the coil.
The control valve is appropriate for a variable displacement compressor that adjusts the discharge displacement in accordance with the inclination of a drive plate located in a crank chamber.
Also, the present invention provides a method of adjusting the amount of movable extent of a movable core in a control valve for operating fluid flow that goes through the control valve including a step of adjusting a thickness of the shim so that the amount of movable extent of the movable core in the retainer cylinder is adjusted.
Regarding the description of the invention, the term of “bottom” refers to a relative location with respect to the other structural elements described below, and is illustrated, by way of example, in FIG.
2
. Therefore, if the control valve of the invention is installed in practical use “upside down” with respect to the orientation depicted in
FIGS. 1-3
, the term “bottom” should mean the reverse as
BRIEF DESCRIPTION OF THE DRAWINGS
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawing in which:
FIG. 1
is a cross-sectional view of a variable displacement type of swash plate compressor according to one embodiment of the present invention;
FIG. 2
is a cross-sectional view of a control valve;
FIG. 3
is an enlarged partial cross-sectional view of the control valve of
FIG. 2
; and
FIG. 4
is an enlarged partial cross sectional view of a prior art control valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A control valve for a variable displacement compressor according to an embodiment of the present invention will now be described.
As shown in
FIG. 1
, a housing
11
of a variable displacement type swash plate compressor (hereinafter, compressor) defines a crank chamber
12
by an inner wall of the housing
11
. A drive shaft
13
is rotatably supported in the housing
11
. The drive shaft
13
is connected to an engine E as a power source of a vehicle, so that the engine E rotatably drives the drive shaft
13
.
In the crank chamber
12
, a lug plate
14
is fixed to the drive shaft
13
in order to rotate integrally with drive shaft
13
. A swash plate
15
, which serves as a cam plate, is disposed in the crank chamber
12
. The swash plate
15
is supported by the drive shaft
13
, to be slidable along and inclinable with respect to the axis of drive shaft
13
. A hinge mechanism
16
is intervened between the lug plate
14
and the swash plate
15
. Accordingly, the hinge mechanism
16
enables the swash plate
15
to rotate integrally with drive shaft
13
and to vary its inclination with respect to the axis of the drive shaft
13
.
Cylinder bores
11
a
are formed in the housing
11
(in
FIG. 1
, only one cylinder bore is shown). A single-headed piston
17
is accommodated in the each cylinder bore
11
a
. Each piston
17
is coupled to the periphery of the swash plate
15
through shoes
18
. Rotation of the drive shaft
13
is converted into reciprocation of the pistons
17
through the lug plate
14
, the hinge mechanism
16
, the swash plate
15
and the shoes
18
.
At a rear side of the cylinder bores
11
a
(right side of FIG.
1
), compression chambers
20
are defined by pistons
17
and valve-port assembly
19
that is disposed in the housing
11
. Suction ports
23
, suction valves
24
, discharge ports
25
and discharge valves
26
are formed in the valve-port assembly
19
. At the rear side in the housing
11
, a suction chamber
21
, which is a suction pressure zone, and a discharge chamber
22
, which is a discharge pressure zone, are individually formed.
The movement of each piston
17
from the top dead center to the bottom dead center draws refrigerant gas to the corresponding compression chamber
20
through the corresponding suction port
23
and suction valve
24
in the valve-port assembly
19
. The movement of each piston
17
from the bottom dead center to the top dead center compresses refrigerant gas in the corresponding compression chamber
20
to a predetermined pressure and discharges the refrigerant gas to the discharge chamber
22
through the discharge port
25
and discharge valve
26
.
The variable displacement mechanism will now be described.
As shown in
FIG. 1
, a bleed passage
27
and a pressurizing passage
28
are respectively disposed in the housing
11
. The bleed passage
27
continuously connects the crank chamber
12
to the suction chamber
21
. The pressurizing passage
28
connects the discharge chamber
22
to the crank chamber
12
. A control valve CV is located in the pressurizing passage in the housing
11
.
The control valve CV adjusts the degree of the valve opening in order to control the flow of the high-pressured refrigerant gas through the pressurizing passage
28
from the discharge chamber
22
to the crank chamber
12
. The bleed passage
27
releases the refrigerant gas from the crank chamber
12
to the suction chamber
21
. Therefore, the pressure in the crank chamber
12
is controlled by the balance of the rate of inflow and the rate of outflow of refrigerant gas in crank chamber
12
. The pressure in the crank chamber
12
is applied to the front side of the piston, and the pressure in the compression chambers
20
is applied to piston heads, respectively. Accordingly, the variation of the pressure balance varies the inclination of the swash plate
15
. This varies the stroke of the pistons
17
and the displacement as well.
For example, when the pressure in the crank chamber
12
decreases, the inclination of the swash plate
15
increases in order to increase the displacement of the compressor. Contrary, when the pressure in the crank chamber
12
increases, the inclination of the swash plate
15
decreases in order to decrease the displacement of the compressor.
A refrigerant circuit will be now described.
As shown in
FIG. 1
, the refrigerant circuit for the air conditioner of the vehicle comprises the compressor and an external refrigerant circuit
30
. The external refrigerant circuit
30
includes a condenser
31
, an expansion valve
32
, and an evaporator
33
. Carbon dioxide is provided as refrigerant gas in the refrigerant circuit
30
.
A first pressure detection point P
1
is located in the discharge chamber
22
. A second pressure detection point P
2
is located in a refrigerant passage, which is predetermined distance downstream (the evaporator
31
side) from the first pressure detection point P
1
. As shown in
FIG. 2
, the first pressure detection point P
1
is connected to the control valve CV through a first pressure introduction passage
35
. The second pressure detection point P
2
is connected to the control valve CV through a second pressure introduction passage
36
.
The valve opening control and pressure detecting structure in the control valve will be now described.
As shown in
FIG. 2
, a valve housing
41
of the control valve CV defines a valve chamber
42
, a communication passage
43
and a pressure sensing chamber
44
. In the valve chamber
42
and the communication passage
43
, a rod
45
is disposed for reciprocation in the axial direction (the vertical direction in FIG.
2
). The communication passage
43
is isolated from the pressure sensing chamber
44
by the upper end portion of the rod
45
that blocks the upper communication passage
43
. The valve chamber
42
is connected to the discharge chamber
22
through the upstream pressurizing passage
28
. The communication passage
43
is connected to the crank chamber
12
through the downstream pressurizing passage
28
. The valve chamber
42
and the communication passage
43
comprise a part of the pressurizing passage
28
as well.
A valve body portion
46
, which is formed in the middle of rod
45
, is disposed in the valve chamber
42
. A step, which is located at a border between the valve chamber
42
and the communication passage
43
, is formed as a valve seat
47
. The communication passage
43
functions as a valve hole. Accordingly, the rod
45
is lifted up from the position as shown in
FIG. 2
(bottom position) to a top position of which the valve body portion
46
is seated on the valve seat
47
, then the communication passage
43
is shut down. Namely, the valve body portion
46
functions as a valve body to adjust the degree of the valve opening in the pressurizing passage
28
.
A pressure sensing member
48
including a bellows is accommodated in the pressure sensing chamber
44
. The top end of the pressure sensing member
48
is fixed on the valve housing
41
. The bottom end of the pressure sensing member
48
is fitted on the top end of the rod
45
. In the pressure sensing chamber
44
, the pressure sensing member
48
divides into two separate chambers. One is a first pressure chamber
49
that is the inside of the pressure sensing member
48
, and another is a second pressure chamber
50
that is the outside of the pressure sensing member
48
pressure PdH at the pressure detection point P
1
is conducted into the first pressure chamber
49
through the first pressure introduction passage
35
. A pressure PdL at the pressure detection point P
2
is conducted into the second pressure chamber
50
through the second introduction passage
36
.
An electromagnetic actuator portion
51
in the control valve will now described.
As shown in
FIG. 3
, the electromagnetic actuator portion
51
is located at the bottom of the valve housing
41
. In the electromagnetic actuator portion
51
, a retainer cylinder
52
having a bottom portion is disposed at the center portion of the valve housing
41
. A center post
53
, which serves as a stationary core, is made of magnetic material (such as alloy with an iron base), and fitted on the opening top of the retainer cylinder
52
. A plunger chamber
54
is defined in the retainer cylinder
52
by fitting the center post
53
on the retainer cylinder
52
. The center post
53
, therefore, serves as a separator of the valve chamber
42
and the plunger chamber
54
, as well.
A plate
55
is attached at a bottom-opening end in the valve housing
41
. The plate
55
is formed in a ring-shape and is made of magnetic material. The inner circumference of the plate
55
is bent upward to form a cylindrical portion
55
a
. The plate
55
with the cylindrical portion
55
a
is fitted on the periphery of the retainer cylinder
52
so that the plate
55
block up an annular opening that exists between the bottom portion of the retainer cylinder
52
and the bottom of the valve housing
41
.
A plunger
56
, which serves as a movable core, is formed in a cylindrical shape and is made of magnetic material. The plunger
56
is accommodated in the plunger chamber
54
so that the plunger may move in the axial direction of the retainer cylinder
52
. The movement of the plunger
56
is slidably guided by the inner surface of the retainer cylinder
52
. A guide hole
57
is bored through the center of the center post
53
. The bottom portion of the rod
45
is disposed in the guide hole
57
so that the rod
45
may move in the axial direction of the rod
45
. The bottom end of the rod
45
contacts the top surface of the plunger
56
in the plunger chamber
54
.
A projection portion
53
a
is annularly projected on the periphery of the bottom end of the center post
53
around the center axis of the valve housing
41
. The projection portion
53
a
is downwardly tapered away to the plunger
56
. A peripheral edge portion
56
b
is chamfered off from the edge of the plunger
56
, in order to avoid the projection portion
53
a
and be faced along the inclined surface of the projection portion
53
a
. According to the structure, an electromagnetic attraction (See the following details), which is generated between the center post
53
and the plunger
56
, has a linear characteristic with respect to the distance therebetween.
A spring
60
is accommodated between the bottom portion of the retainer cylinder
52
and the plunger
56
in the plunger chamber
54
. The spring
60
urges the plunger toward the rod
45
. The rod
45
is also urged by elastic character of the pressure sensing member
48
(hereinafter, a bellows spring
48
) toward the plunger
56
. Accordingly, the plunger
56
and the rod
45
are always moved up and down together. The urging elastic force of the bellows spring
48
is set to be greater than that of the spring
60
.
The valve chamber
42
and the plunger chamber
54
are connected to each other through a space between the guide hole
57
and the rod
45
. Therefore, the discharge pressure of the refrigerant gas is supplied into both the valve chamber
42
and the plunger chamber
54
. It is generally known that a characteristic to control the valve is improved by supplying the same gas pressure into both the valve chamber
42
and the plunger chamber
54
.
The retainer cylinder
52
includes a first cylindrical member
58
, which is formed in a hollow shape and is made of non-magnetic material (such as non-magnetic stainless material), and a second cylindrical member
59
having a bottom portion, which is made of magnetic material. The entire second cylindrical member
59
including the side cylindrical portion as well as the bottom portion is made of non-magnetic material, in order to be easy to manufacture it.
The first cylindrical member
58
is disposed for surrounding the center post
53
and the plunger
56
. The bottom-opening end of the first cylindrical member
58
is thinner than the other part (a large diameter portion
58
a
) and the bottom-opening end comprises a small diameter portion
58
b
. The second cylindrical member
59
is fitted with the outer surface of the small diameter portion
58
b
of the first cylindrical member
58
. The outer cylindrical surface of the second cylindrical member
59
has almost the same diameter as the large diameter portion
58
a
of the first cylindrical member
58
.
A shim
65
is located between a bottom surface
56
a
of the plunger
56
and an inner bottom surface
59
a
of the second cylindrical member
59
in the plunger chamber
54
. The shim
65
is formed in a ring plate shape and is made of non-magnetic material. During the assembly of the control valve CV, a number of shims
65
having various thickness are provided so that the particular shim may be selected to correct an unevenness of the control valve CV. In the other words, providing the various thickness of the shims
65
is for adjusting the tolerance of movable extent of the plunger
56
, even if the tolerance of each part or assembling each part in the control valve CV is added to increase the unevenness. The thickness of the shim
65
is greater than the thickness of the small diameter portion
58
b
of the first cylindrical member
58
.
The inner circumference of the shim
65
is intervened between the inner bottom surface
59
a
and spring
60
so that the shim
65
serves as a spring seat as well. According to such structure, the spring
60
urges the shim
65
toward the inner bottom surface
59
a
. The shim
65
is, therefore, stably located in the plunger chamber
54
without fixing the shim
65
on the bottom surface of the plunger
56
or on the inner bottom surface
59
a
of the second cylindrical member
59
. Further, regarding the present invention, the shim
65
may be fixed on the bottom surface of the plunger
56
or on the inner bottom surface
59
a
of the second cylindrical member
59
.
A coil
61
is wound or disposed around the retainer cylinder
52
along a length thereof that surrounds portions of the center post
53
and the plunger
56
. The coil
61
receives a electric current from a drive circuit
71
based on a signal from a control device
70
(such as computer) that receives external signals from an external sensing means
72
, such as an On/Off signal of air-conditioner switch, an actual temperature in the passenger compartment, target temperature set by a adjuster, etc.
According to the electric current from the control device
70
, magnetic flux is generated around the coil
61
. The magnetic flux goes from the coil
61
through the plate
55
or the second cylindrical member
59
to the small diameter portion
58
b
of the first cylindrical member
58
and the plunger
56
, and further, it goes through the plunger
56
to the center post
53
. The electromagnetic force (electromagnetic attraction), which is corresponds to the amount of electric current flowing to the coil
61
, is generated between the plunger
56
and the center post
53
. This force is transmitted from the plunger to the rod
45
. The electric current is controlled by an adjustment of the voltage to the coil
61
. For the adjustment of the voltage, a PWM (pulse-width modulation) control is applied to the drive circuit
71
.
An operating characteristic of the control valve CV will be now described. Regarding the illustrated control valve CV, the position of the rod
45
decides the valve opening degree of the valve body portion
46
as follows;
First, as shown in
FIG. 2
, the position of the rod
45
is determined by the downward force of the bellows spring
48
when no electric current is supplied to the coil
61
(duty of PWM=0%). Accordingly, the rod
45
is located at a bottom position in order to fully open the valve body portion
46
in the communication passage
43
. The pressure in the crank chamber
12
is therefore to be a maximum under the condition. A differential pressure between the crank chamber
12
and the compression chamber
20
through the piston
17
is, therefore, a maximum under this condition. Consequently, the inclination angle of the swash plate
15
is at the maximum and the displacement of the compressor will be the minimum.
Next, when the current with a minimum duty (>0%) in the variable duty range is supplied to the coil
61
, the electromagnetic force is generated and added upward to the urging force of the spring
60
. When the added upward force exceeds the downward force of the bellows spring
48
, the rod
45
moves upward. In this situation, the upward force, which comprises the electromagnetic force added to the urging force of the spring
60
, is opposed by the downward force, which comprises the force resulting from the differential pressure ΔPd (=PdH-PdL) added to the downward force of the bellows spring
48
. The valve body portion
46
with the rod
45
is positioned at the location where the forces applied to the rod
45
are equilibrated.
For example, if the amount of the refrigerant gas flow decreases based on a decrease of the engine E speed, the downward force of the differential pressure ΔPd decreases. Due to this change, the forces applied to the rod
45
lose their equilibrium. Accordingly, the rod
45
with the valve body portion
46
is lifted up to reduce the opening in the communication passage
43
so that the pressure in the crank chamber
12
decreases. The inclination angle of the swash plate
15
is increased to increase the displacement of the compressor. Consequently, the amount of the refrigerant gas flow in the refrigerant circuit
30
increases based on the larger displacement of the compressor, and the differential pressure ΔPd increases.
Contrary, if the amount of the refrigerant gas flow increases based on an increase of the engine E speed, the downward force resulting from the differential pressure ΔPd increases. Due to the change, the forces applied to the rod
45
lose their equilibrium. Accordingly, the rod
45
with the valve body portion
46
is lowered to enlarge the opening in the communication passage
43
so that the pressure in the crank chamber
12
increases. The inclination angle of the swash plate
15
is decreased to decrease the displacement of the compressor. Consequently, the amount of refrigerant gas flow in the refrigerant circuit
30
decreases based on the smaller displacement of the compressor, and the differential pressure ΔPd decreases.
Further to above, when the current duty to the coil
61
increases in order to increase the magnitude of the upward electromagnetic force, the forces applied to the rod
45
lose their equilibrium. Accordingly, the rod
45
with the valve body portion
46
is lifted up to reduce the opening in the communication passage
43
so that the displacement of the compressor increases. Consequently, the amount of refrigerant gas flow increases based on the larger displacement of the compressor, and the differential pressure ΔPd increases.
Contrary, when the current duty to the coil
61
decreases in order to decrease the magnitude of the upward electromagnetic force, the forces applied to the rod
45
lose their equilibrium. Accordingly, the rod
45
with the valve body portion
46
is lowered to enlarge the opening in the communication passage
43
so that the displacement of the compressor decreases. Consequently, the amount of refrigerant gas flow decreases based on the smaller displacement of the compressor, and the differential pressure ΔPd decreases.
In other words, the control valve CV has the structure that the rod
45
is automatically positioned based on the actual differential pressure ΔPd in order to maintain the differential pressure ΔPd at the control target (target differential pressure) that is determined by the electric current duty into the coil
61
. The target differential pressure is externally variable by adjusting the current duty to the coil
61
.
By the way, in the illustrated embodiment, the language of “bottom” describes the relative location with respect to the other structural elements the illustrated in FIG.
2
. If the control valve or the compressor is installed in practical use upside down, the term “bottom” should mean the reverse as “top”. The other words such as the “top”, “up”, “upward”, “down” and “downward” should mean the reverse as well.
The illustrated embodiment has the following advantage.
(1) The retainer cylinder
52
includes the first cylindrical member
58
made of non-magnetic material and a second cylindrical member
59
having a bottom portion that is made of magnetic material. Accordingly, the magnetic permeability between the coil
61
and the plunger
56
is improved, even though the retainer cylinder
52
may be thickened to improve its withstanding pressure to the internal refrigerant gases such as the carbon dioxide.
(2) The shim
65
, which is formed from non-magnetic material, is intervened between the bottom surface
56
a
of the plunger
56
and inner bottom surface
59
a
of the second cylindrical member
59
. Therefore, the non-magnetic gap, which is formed by non-magnetic material of the shim
65
, is secured between the magnetic material of the second cylindrical member
59
and the plunger
56
, even though the plunger
56
is located at the lowest position. It enables to suppress the downward electromagnetic attraction between the bottom surface
56
a
of the plunger
56
and the inner bottom surface
59
a
of the second cylindrical member
59
. Because the shim
65
is non-magnetic, there is a little downward electromagnetic attraction that would offset the upward electromagnetic force acting on the plunger
56
and the rod
45
from the coil
61
. Furthermore, the upward electromagnetic force is conventionally controlled by the chamfered peripheral edge portion
56
b
of the plunger
56
in order to obtain the linear characteristic of the upward electromagnetic force to the distance between the center post
53
and the plunger
56
. However, the downward electromagnetic attraction between the bottom surface
56
a
and the inner bottom surface
59
a
is extremely strong where the bottom surface
56
a
approaches the inner bottom surface
59
a
, on condition that there is no gap between them. According to the illustrated embodiment, the shim
65
secures the non-magnetic gap to suppress the downward electromagnetic attraction between the bottom surface
56
a
of the plunger
56
and the inner bottom surface
59
a
of the second cylindrical member
59
. The external controllability of the control valve CV is, therefore, improved so that the control of the displacement of the compressor may be more accurate.
(3) The first cylindrical member
58
is disposed for directly surrounding the plunger
56
, and the second cylindrical member
59
is disposed for surrounding the small diameter portion
58
b
of the first cylindrical member
58
. During the operation, the plunger
56
is guided to slide on the inner cylindrical wall of the first cylindrical member
58
that is made of non-magnetic material. Generally, magnetic material tends not to slide well on other magnetic materials. Therefore, the illustrated embodiment has the advantage of the slidablity of the plunger
56
on the inner wall of the first cylindrical member
58
. Further to above, the inner cylindrical wall of the first cylindrical member
58
covers the full extent of the plunger's range of movement in order to slidably guide the plunger
56
. Accordingly, the sliding resistance between the plunger
56
and the retainer cylinder
52
is decreased. This structure suppresses the hysteresis characteristics, which appears in the degree of the control valve opening in accordance with the current duty rate into the coil
61
.
(4) Regarding the first cylindrical member
58
made of non-magnetic material, the portion in the vicinity of the plunger
56
(small diameter portion
58
b
) is thinned. Therefore, the magnetic permeability between the coil
61
and plunger
56
is improved so that even a small coil
61
may generate sufficient electromagnetic force to actuate the plunger
56
. This serves to miniaturize the electromagnetic actuator portion
51
as well as the control valve CV.
(5) The second cylindrical member
59
is fixed to the outer surface of the small diameter portion
58
b
of the first cylindrical member
58
. The second cylindrical member
59
serves to reinforce the small diameter portion
58
b
. The retainer cylinder
52
, therefore, maintains the strengths even though the wall of the first cylindrical member
58
is thinned. According to this structure, the withstanding pressure is improved so that the hi-pressured carbon dioxide may be applied as the refrigerant gas. As well, it is easier to introduce the hi-pressured discharge gas into the plunger chamber
54
.
(6) The non-magnetic shim
65
serves as the adjustment member for adjusting the tolerance of the movable extent of the plunger
56
. Accordingly, the illustrated method corrects the unevenness of the movable extent of the plunger
56
in connection with an unevenness of the valve opening control.
The present invention can further be embodied, for example, in;
a control valve that is not disposed in the pressurizing passage
28
, but in the bleed passage
27
to control the pressure in the crank chamber
12
. This type is generally called a bleeding control valve.
the other type of electromagnetic control valves, such as the valve is operated by only electromagnetic power without any pressure sensing mechanism (pressure sensing member
48
).
a control valve for controlling a wobble type compressor.
Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.
Claims
- 1. A control valve for operating fluid flow that goes through the control valve, the control valve comprising;a retainer cylinder including a first cylindrical member made of non-magnetic material and a second cylindrical member made of magnetic material, the second cylindrical member having a bottom portion; a stationary core disposed in the retainer cylinder; a movable core disposed in the retainer cylinder, wherein the movable core is located between the stationary core and the bottom portion of the second cylindrical member; a shim made of non-magnetic material, the shim is disposed in the retainer cylinder and located between the movable core and the bottom portion of the second cylindrical member, a coil disposed around the retainer cylinder; and a valve body movably linked with the movable core, wherein the valve body adjusts a degree of a valve opening based on a movement of the movable core in the retainer cylinder, and wherein the movement of the movable core is based on an electromagnetic force that is generated between the stationary core and the movable core in accordance with an electric current supplied to the coil.
- 2. The control valve according to claim 1, wherein an inner wall of the first cylindrical member surrounds the movable core so that the inner wall contacts to a surface of the movable core.
- 3. The control valve according to claim 2, wherein the first cylindrical member having a small diameter portion, and the second cylindrical member is fitted with an outer surface of the small diameter portion.
- 4. The control valve according to claim 1, further comprising a spring urges the movable core to the bottom portion of the second cylindrical member, wherein the valve body is positioned at where the electromagnetic force and an urging force of the spring are equilibrated.
- 5. A control valve in a variable displacement compressor that adjust a discharge displacement in accordance with the inclination angle of a swash plate disposed in a crank chamber, wherein the inclination angle of the swash plate varies according to the differential pressure between a pressure in the crank chamber and the pressure in a cylinder bore, wherein the compressor includes a adjusting device for adjusting the differential pressure, wherein the adjusting device includes the control valve and a gas passage for conducting refrigerant gas, and wherein the control valve regulates the amount of the refrigerant gas flow in the gas passage, the control valve comprising:a retainer cylinder including a first cylindrical member made of non-magnetic material and a second cylindrical member made of magnetic material, the second cylindrical member having a bottom portion; a stationary core disposed in the retainer cylinder; a movable core disposed in the retainer cylinder, wherein the movable core is located between the stationary core and the bottom portion of the second cylindrical member; a shim made of non-magnetic material, the shim is disposed in the retainer cylinder and located between the movable core and the bottom portion of the second cylindrical member, a coil disposed around the retainer cylinder; and a valve body movably linked with the movable core, wherein the valve body adjusts a degree of a valve opening based on a movement of the movable core in the retainer cylinder, and wherein the movement of the movable core is based on an electromagnetic force that is generated between the stationary core and the movable core in accordance with an electric current supplied to the coil.
- 6. The control valve according to claim 5, wherein an inner wall of the first cylindrical member surrounds the movable core so that the inner wall contacts to a surface of the movable core.
- 7. The control valve according to claim 6, wherein the first cylindrical member having a small diameter portion, and the second cylindrical member is fitted with an outer surface of the small diameter portion.
- 8. The control valve according to claim 5, wherein the variable displacement compressor comprises a part of refrigerant circuit of an air conditioner, further including a pressure detection part in the refrigerant circuit, and a pressure sensing mechanism sensing a detected pressure of the pressure detection part, wherein the pressure sensing mechanism operates the valve body for controlling the variable displacement to reduce or cancel a fluctuation of the detected pressure.
- 9. The control valve according to claim 8, wherein the air conditioner further comprising a control device for controlling the electric current to the coil to adjust a target pressure in accordance to set a position of the valve body.
- 10. The control valve according to claim 9 further comprising a spring urges the movable core, wherein the valve body is positioned based on the electromagnetic force, the operation of the pressure sensing mechanism and the spring.
- 11. The control valve according to claim 9, wherein the pressure detection part provides two separate detection points in the refrigerant circuit, the pressure sensing mechanism operates based on a differential pressure between the two detection points, and the target pressure as a reference point of the valve body is variable by varying the electric current to the coil.
- 12. The control valve according to claim 11, where the two separate points of the pressure detection part are provided in a discharge pressure region of the refrigerant circuit.
- 13. The control valve according to claim 5, wherein the refrigerant gas is carbon dioxide.
- 14. A method of adjusting the amount of movable extent of a movable core in a control valve operating fluid flow that goes through the control valve, the control valve having,a retainer cylinder including a first cylindrical member made of non-magnetic material and a second cylindrical member made of magnetic material, the second cylindrical member having a bottom portion, a stationary core disposed in the retainer cylinder, a movable core disposed in the retainer cylinder, wherein the movable core is located between the stationary core and the bottom portion of the second cylindrical member, a shim made of non-magnetic material, the shim is disposed in the retainer cylinder and located between the movable core and the bottom portion of the second cylindrical member, a coil disposed around the retainer cylinder, and a valve body movably linked with the movable core, wherein the valve body adjusts a degree of a valve opening based on a movement of the movable core in the retainer cylinder, wherein the movement of the movable core is based on an electromagnetic force in accordance with an electric current supplied to the coil, the method comprising: adjusting a thickness of the shim so that the amount of movable extent of the movable core in the retainer cylinder is adjusted.
- 15. The method according to claim 14, further comprising providing plural shims having various thickness, and selecting a particular shim having a particular thickness in the plural shims to correct manufacturing tolerance of the movable extent of the movable core.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2001-054455 |
Feb 2001 |
JP |
|
US Referenced Citations (5)
Number |
Name |
Date |
Kind |
4681143 |
Sato et al. |
Jul 1987 |
A |
4779762 |
Klein et al. |
Oct 1988 |
A |
4875832 |
Suzuki et al. |
Oct 1989 |
A |
5115783 |
Nakamura et al. |
May 1992 |
A |
5794860 |
Neumann |
Aug 1998 |
A |
Foreign Referenced Citations (1)
Number |
Date |
Country |
2000-028024 |
Jan 2000 |
JP |