U.S. patent application number 11/402746 was filed with the patent office on 2006-10-12 for control valve for variable capacity compressors.
This patent application is currently assigned to Fujikoki Corporation. Invention is credited to Daisuke Mori, Takanori Nagata.
Application Number | 20060228227 11/402746 |
Document ID | / |
Family ID | 36609037 |
Filed Date | 2006-10-12 |
United States Patent
Application |
20060228227 |
Kind Code |
A1 |
Mori; Daisuke ; et
al. |
October 12, 2006 |
Control valve for variable capacity compressors
Abstract
There is provided a control valve for a variable capacity
compressor, which is applicable to a compressor of large capacity.
This control valve comprises a valve main body (20) equipped with a
valve rod (15) having a valve body (15a), with a valve chamber (21)
having a guide hole (19) in which the valve rod is enabled to slide
and a valve aperture (22) for the valve body, with a cooling medium
inlet port (25) disposed on an upstream side of the valve aperture
for introducing a cooling medium from the compressor, and with a
cooling medium outlet port (26) disposed on a downstream side of
the valve aperture and communicated with a crank chamber; an
electromagnetic actuator (30) for driving the valve rod to move in
the direction of opening or closing the valve aperture; and a
pressure sensitive moving member (40) for driving the valve rod to
move in response to a sucking pressure of the compressor; which is
characterized in that a contracted hole portion is formed at an
upper portion of the guide hole, that a diametrally reduced rod
portion (15b) to be inserted into the contracted hole portion (19b)
is formed at an upper portion of the valve rod, and that the valve
rod is provided with an equalizing hole (51) for introducing a
cooling medium pressure of the cooling medium outlet port into an
equalizing pressure introducing chamber (52).
Inventors: |
Mori; Daisuke; (Tokyo,
JP) ; Nagata; Takanori; (Tokyo, JP) |
Correspondence
Address: |
BAKER & BOTTS
30 ROCKEFELLER PLAZA
44TH FLOOR
NEW YORK
NY
10112
US
|
Assignee: |
Fujikoki Corporation
Tokyo
JP
|
Family ID: |
36609037 |
Appl. No.: |
11/402746 |
Filed: |
April 11, 2006 |
Current U.S.
Class: |
417/222.2 |
Current CPC
Class: |
F04B 2027/1854 20130101;
F04B 27/1804 20130101; F04B 2027/1859 20130101; F04B 2027/1827
20130101 |
Class at
Publication: |
417/222.2 |
International
Class: |
F04B 1/26 20060101
F04B001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2005 |
JP |
2005-114428 |
Claims
1. A control valve for a variable capacity compressor, comprising:
a valve main body including a valve rod having a valve body, the
valve rod having a diametrally reduced rod portion formed at a
first portion thereof and a diametrally enlarged rod portion formed
at a second portion thereof, a valve chamber having a guide hole
for receiving the valve rod and a valve aperture with which the
valve body is capable of being contacted, the guide hole having a
contracted hole portion formed at a first portion thereof and an
enlarged hole portion formed at a second portion thereof, a cooling
medium inlet port disposed on an upstream side of the valve
aperture for introducing a cooling medium of discharge pressure
from the compressor, and a cooling medium outlet port disposed on a
downstream side of the valve aperture and capable of communicating
with a crank chamber of the compressor; an electromagnetic actuator
for moving the valve rod in a direction of opening or closing the
valve aperture; and a pressure sensitive moving member for moving
the valve rod in the direction of opening or closing the valve
aperture in response to a sucking pressure of the compressor;
wherein the diametrally reduced rod portion is adapted to be
slidingly inserted into the contracted hole portion, and the valve
rod includes an equalizing hole for introducing a cooling medium
pressure of the cooling medium outlet port into an equalizing
pressure introducing chamber within the valve main body.
2. A control valve for a variable capacity compressor, which
comprises: a valve main body including a valve rod having a valve
body, the valve rod having a diametrally reduced rod portion formed
at a first portion thereof and a diametrally enlarged rod portion
formed at a second portion thereof, a valve chamber having a guide
hole for receiving the valve rod and a valve aperture with which
the valve body is capable of being contacted, the guide hole having
a contracted hole portion formed at a first portion thereof and an
enlarged hole portion formed at a second portion thereof a cooling
medium inlet port disposed on an upstream side of the valve
aperture for introducing a cooling medium of discharge pressure
from the compressor, and a cooling medium outlet port disposed on a
downstream side of the valve aperture and capable of communicating
with a crank chamber of the compressor; an electromagnetic actuator
including a coil, a cylindrical stator disposed on the inner
peripheral side of the coil, a sucking member secured to the
stator, and a plunger capable of cooperating with the coil and
moving the valve rod in a direction of opening or closing the valve
aperture; a pressure sensitive chamber which is formed on the inner
peripheral side of the stator and over the sucking member and to
which an inlet pressure is introduced therein from the compressor;
a pressure sensitive driving member disposed in the
pressure-sensitive chamber; and an operating rod interposed between
a pressure sensitive driving member and the plunger; wherein the
valve body is designed to be moved in the valve-closing direction
as the plunger is moved in a first direction and the valve body is
designed to be moved in the valve-opening direction as the
operating rod is pushed in a direction opposite the first direction
by the actuation of the pressure sensitive driving member; wherein
the diametrally reduced rod portion is adapted to be slidingly
inserted into the contracted hole portion, and the valve rod
includes an equalizing hole for introducing a cooling medium
pressure of the cooling medium outlet port into an equalizing
pressure introducing chamber within the valve main body.
3. The control valve of claim 1 wherein the equalizing pressure
introducing chamber comprises an area between the contracted hole
portion and the enlarged rod portion.
4. The control valve of claim 2 wherein the equalizing pressure
introducing chamber comprises an area between the contracted hole
portion and the enlarged rod portion.
5. The control valve of claim 1, wherein the valve rod includes an
annular groove on an outer circumferential portion thereof designed
to slidingly contact the enlarged hole portion of guide hole.
6. The control valve of claim 2, wherein the valve rod includes an
annular groove on an outer circumferential portion thereof designed
to slidingly contact the enlarged hole portion of guide hole.
7. The control valve of claim 3, wherein the valve rod includes an
annular groove on an outer circumferential portion thereof designed
to slidingly contact the enlarged hole portion of guide hole
8. The control valve of claim 4, wherein the valve rod includes an
annular groove on an outer circumferential portion thereof designed
to slidingly contact the enlarged hole portion of guide hole.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a control valve for a
variable capacity compressor to be employed in an air conditioner
for vehicle. In particular, the present invention relates to a
control valve for a variable capacity compressor, which is
applicable to a compressor of large capacity while making it
possible to share the components employed in the conventional
control valves.
BACKGROUND INFORMATION
[0002] A control valve for a variable capacity compressor to be
employed in an air conditioner for vehicle is generally constructed
as follows. Namely, a cooling medium exhibiting a discharge
pressure "Pd" is permitted to enter into the crank chamber of
compressor from the discharge chamber of compressor so as to adjust
the pressure "Pc" inside the crank chamber. In this case, the flow
rate of cooling medium exhibiting a discharge pressure "Pd" to the
crank chamber is restricted in such a manner that the quantity of
supply (throttling volume) of cooling medium to the crank chamber
can be controlled depending on the sucking pressure "Ps" of
compressor. For this purpose, various proposals where an
electromagnetic actuator (solenoid) is employed have been suggested
or put into practice as seen from JP Patent Laid-open Publication
(Kokai) No. 2002-303262 (2002).
[0003] FIG. 3 illustrates one example of such a conventional
control valve for a variable capacity compressor. The control valve
5 shown herein comprises a valve rod 15' having a valve body 15a; a
valve main body 20' provided with a valve chamber 21 having a valve
seat (valve aperture) 22 with which the valve body 15a is enabled
to retroactively contact, with a plurality of filter
(25A)--attached cooling medium--inlet ports 25 for receiving a
cooling medium of discharge pressure "Pd" from the compressor,
these inlet ports 25 being disposed around the outer
circumferential wall of the valve chamber 21 (i.e. an upstream side
of the valve seat 22), and with a cooling medium outlet port 26
which is disposed on a downstream side of the valve seat 22 and
communicated with a crank chamber of the compressor; an
electromagnetic actuator 30.
[0004] This electromagnetic actuator 30 is equipped with a coil 32
having a connector 31 for electroexcitation, with a cylindrical
stator 33 disposed on the inner peripheral side of the coil 32,
with a sucking member 34 having U-shaped cross-section and
press-inserted into a lower inner peripheral end portion of the
stator 33, with a flange (35a)--attached pipe 35 which is coupled,
through an upper edge portion thereof and by means of TIG welding,
to a lower outer circumferential end portion (step portion) of the
stator 33, with a plunger 37 slidingly disposed so as to enable it
to move up and down inside the guide pipe 35 and placed below the
sucking member 34, and with a cylindrical housing 60 with an
opening in its bottom and disposed to cover the outer periphery of
the coil 32.
[0005] Additionally, a hexagon socket head adjusting screw 65 is
screwed on an upper portion of the stator 33. A pressure sensitive
chamber 45 into which the sucking pressure "Ps" of compressor is to
be introduced is formed between the adjusting screw 65 attached to
the inner peripheral wall of stator 33 and the sucking member 34.
In this pressure sensitive chamber 45, there is disposed, as a
pressure sensitive driving member, a bellows main body 40
consisting of a bellows 41, a downwardly projected upper stopper
42, a reverse U-shaped lower stopper 43 and a compression coil
spring 44. Further, a compression coil spring 46 for urging the
bellows main body 40 to contract (in the direction to contract it
toward the adjusting screw 65) is interposed between the bellows
main body 40 and the sucking member 34. Further, a step-attached
operating rod 14 piercing through the sucking member 34 is
interposed between the reverse U-shaped lower stopper 43 of bellows
main body 40 and a U-shaped portion 37c of plunger 37.
Additionally, a valve-opening spring 47 made of a compression coil
spring for urging the valve rod 15' downward (in the direction to
open the valve) by way of the plunger 37 is interposed between the
sucking member 34 and the U-shaped portion 37b of plunger 37.
[0006] On the other hand, a convex stopper 28 for regulating the
lowermost descending position of the plunger 37 is projected upward
from an upper central portion of the valve main body 20'. A guide
hole 19 in which the valve rod 15 is slidingly inserted is formed
at a central portion of valve main body 20' over the valve chamber,
this guide hole 19 being formed so as to pierce also through the
convex stopper 28. A suction pressure cooling medium-introducing
chamber 23 for enabling a cooling medium of suction pressure of the
compressor to be introduced therein is formed between the plunger
37 and an upper outer periphery of the valve main body 20' (an
outer peripheral wall of the convex stopper 28). A plurality of
suction pressure cooling medium-introducing ports 27 are formed in
the outer wall of the suction pressure-introducing chamber 23. A
cooling medium of sucking pressure "Ps" that has been introduced
into the suction pressure cooling medium-introducing chamber 23
from the cooling medium-introducing ports 27 is designed to be
introduced into the pressure sensitive chamber 45 via longitudinal
grooves 37a formed on the outer peripheral wall of plunger 37, via
a through-hole 37d formed at a central axis of plunger 37 and via a
through-hole 39 formed in the sucking member 34.
[0007] A valve-closing spring 48 made of a conical compression
spring for urging the valve rod 15' upward is disposed at a lower
portion (a cooling medium outlet port 26) of the valve main body
20'. By the effect of urging force of this valve-closing spring 48,
an upper end portion of the valve rod 15' is always brought into
press-contact with the through-hole 37d portion of plunger 37.
[0008] A lower flange portion 35a of the pipe 35 is mounted,
through an O-ring 57, on an upper end of the valve main body 20'. A
flange (56a)--attached short cylindrical pipe holder 56 is
interposed between the flange portion 35a and the coil 32. These
flange portions 35a and 56a are both fixed to each other by means
of the upper outer peripheral chamfering portion 29 of the valve
main body 20'. An open bottom portion 61 of the housing 60 is
press-inserted in an upper end portion of the pipe holder 56. An
upper end portion 62 of the housing 60 is calked to the flange
portion 31c of the connector 31. An O-ring 66 is interposed between
the housing 60 and the connector 31. At a lower central portion of
the connector 31, there is formed a recessed portion 31a in which a
projected portion 31b to be engaged with the hexagonal hole of the
adjusting screw 65 is formed. An upper portion of the stator 33 as
well as an upper portion of the adjusting screw 65 is inserted into
this recessed portion 31a.
[0009] In the control valve 5 constructed as described above, when
the solenoid portion consisting of the coil 32, the stator 33 and
the sucking member 34 is electroexcited, the plunger 37 is drawn
toward the sucking member 34, forcing the valve rod 15' to move
upward (in the valve-closing direction) by the urging force of the
valve-closing spring 48. On the other hand, the cooling medium of
suction pressure "Ps" that has been introduced into the suction
pressure cooling medium-introducing ports 27 from the compressor is
introduced from the suction pressure cooling medium-introducing
chamber 23 into the pressure sensitive chamber 45 via longitudinal
grooves 37a formed on the outer peripheral wall of plunger 37 and
via a through-hole 39 formed in the sucking member 34. As a result,
the bellows main body 40 (the interior thereof is kept in vacuum)
is caused to displace, i.e. contract or expand depending on the
pressure (the suction pressure "Ps") inside the pressure sensitive
chamber 45 (when the suction pressure "Ps" is high, the bellows
main body 40 is contracted, and when the suction pressure "Ps" is
low, the bellows main body 40 is expanded). Then, this displacement
is transmitted, via the operating rod 14 and the plunger 37, to the
valve rod 15', thereby making it possible to adjust the magnitude
of opening of valve (the effective cross-sectional area of
passageway between the valve seat 22 and the valve body 15a).
Namely, the magnitude of opening of valve will be determined
depending on the sucking force of the plunger 37 to be effected by
the solenoid portion consisting of the coil 32, the stator 33 and
the sucking member 34, on the urging force of the bellows main body
40, and on the urging force of the valve-opening spring 47 and the
valve-closing spring 48. Further, depending on this magnitude of
opening of valve, the quantity (magnitude of restriction) of
cooling medium of discharge pressure "Pd" that has been introduced
from the discharge pressure cooling medium inlet port 25 into the
valve chamber 21 and that will be delivered toward the outlet port
26, i.e. toward the crank chamber can be adjusted, thus making it
possible to control the pressure (cooling medium feeding pressure)
"Pc" inside the crank chamber.
[0010] The present inventors have attempted to develop a control
valve which is applicable to a compressor of large capacity while
making it possible to share, in order to reduce the manufacturing
cost, the components employed in the conventional control valves
such as the aforementioned control valve 5 for a variable capacity
compressor. However, there are following problems to be overcome in
order to make the control valve applicable to a compressor of large
capacity.
[0011] Namely, in order to make the control valve applicable to a
compressor of large capacity, it is necessary to enlarge the valve
aperture 22 so as to increase the flow rate of cooling medium to be
fed to the crank chamber of compressor from the cooling medium
outlet port 26. However, if the valve aperture 22 is enlarged, the
cooling medium outlet port 26 side pressure (cooling medium feeding
pressure "Pc" directed toward the crank chamber) acting on the
valve rod 15' (valve body 15a) would be increased. In the case of
the conventional control valve 5, a difference in pressure (Pc-Ps)
between the cooling medium feeding pressure "Pc" and the suction
pressure "Ps" (acting on a top surface of the valve rod 15') is so
small that this difference is almost negligible in controlling the
flow rate. However, when the flow rate of cooling medium is
increased by enlarging the valve aperture 22 in order to make the
valve applicable to a compressor of large capacity, the influence
originating from this difference in pressure between the cooling
medium feeding pressure "Pc" and the suction pressure "Ps" is
increased, so that if the electromagnetic actuator 30 and the
pressure sensitive driving member 40, each being the same in
specifications, are employed (shared), the valve rod 15' (valve
body 15a) is pushed upward (valve closing direction) due to this
difference in pressure, thus giving bad influences on the control
of cooling medium flow rate.
[0012] Further, in the case of control valve 5 described above,
since the pressure of cooling medium to be introduced into the
valve chamber 21 from the discharge pressure cooling medium inlet
port 25 (discharge pressure "Pd") is higher than the pressure of
cooling medium in the suction pressure cooling medium-introducing
chamber 23 (suction pressure "Ps"), part of the cooling medium that
has been introduced into the valve chamber 21 is enabled to leak
into the suction pressure cooling medium-introducing chamber 23
through a slide-contacting interface between the valve rod 15' and
the guide hole 19. As the quantity of this leakage due to this
difference (Pd>Ps) is increased, the control of cooling medium
would be badly affected. Therefore, it is desirable to minimize the
quantity of this leakage due to this difference (Pd>Ps) as much
as possible.
BRIEF SUMMARY OF THE INVENTION
[0013] The present invention has been made in view of the
circumstances mentioned above and, therefore, an object of the
present invention to provide a control valve for a variable
capacity compressor, which is applicable to a compressor of large
capacity while making it possible to share the components employed
in other kinds of control valve.
[0014] With a view to achieving the aforementioned objects, there
is provided, according to one aspect of the present invention, a
control valve for a variable capacity compressor, which
fundamentally comprises a valve main body equipped with a valve rod
having a valve body, with a valve chamber having a guide hole in
which the valve rod is enabled to slidingly insert and a valve
aperture with which the valve body can be retractivebly contacted,
with a cooling medium inlet port disposed on an upstream side of
the valve aperture for introducing a cooling medium of discharge
pressure from the compressor, and with a cooling medium outlet port
disposed on a downstream side of the valve aperture and
communicated with a crank chamber of the compressor; an
electromagnetic actuator for driving the valve rod to move in the
direction of opening or closing the valve aperture; and a pressure
sensitive moving member for driving the valve rod to move in the
direction of opening or closing the valve aperture in response to a
sucking pressure of the compressor.
[0015] Further, control valve is characterized in that a contracted
hole portion is formed at an upper portion of the guide hole, that
a diametrally reduced rod portion which can be slidingly inserted
into the contracted hole portion is formed at an upper portion of
the valve rod, and that the valve rod is provided with an
equalizing hole for introducing a cooling medium pressure of the
cooling medium outlet port into an equalizing pressure introducing
chamber which is interposed between an enlarged hole portion
located below the contracted hole portion of the guide hole and a
diametrally enlarged rod portion located below the diametrally
reduced rod portion of the valve rod.
[0016] In a more preferable embodiment, the control valve for a
variable capacity compressor comprises a valve main body equipped
with a valve rod having a valve body, with a valve chamber having a
guide hole in which the valve rod is enabled to slidingly insert
and a valve aperture with which the valve body can be retractivebly
contacted, with a cooling medium inlet port disposed on an upstream
side of the valve aperture for introducing a cooling medium of
discharge pressure from the compressor, and with a cooling medium
outlet port disposed on a downstream side of the valve aperture and
communicated with a crank chamber of the compressor; an
electromagnetic actuator constituted by a coil, a cylindrical
stator disposed on the inner peripheral side of the coil, a sucking
member secured to the stator, and a plunger disposed below the
sucking member and enabled to slide up and down; a pressure
sensitive chamber which is formed on the inner peripheral side of
the stator and over the sucking member and to which an inlet
pressure is introduced therein from the compressor; a pressure
sensitive driving member disposed in the pressure-sensitive
chamber; and an operating rod interposed between a pressure
sensitive driving member and the plunger; wherein the valve body is
designed to be moved in the valve-closing direction as the plunger
is moved close to the sucking member and in the valve-opening
direction as the operating rod is pushed downward by the actuation
of the pressure sensitive driving member; the control valve being
further characterized in that a contracted hole portion is formed
at an upper portion of the guide hole, that a diametrally reduced
rod portion which can be slidingly inserted into the contracted
hole portion is formed at an upper portion of the valve rod, and
that the valve rod is provided with an equalizing hole for
introducing a cooling medium pressure of the cooling medium outlet
port into an equalizing pressure introducing chamber which is
interposed between an enlarged hole portion located below the
contracted hole portion of the guide hole and a diametrally
enlarged rod portion located below the diametrally reduced rod
portion of the valve rod.
[0017] In a further preferable embodiment, the valve rod is
provided with an annular groove on an outer circumferential portion
thereof which is designed to be slidingly contacted with the
enlarged hole portion of guide hole.
[0018] In the control valve for a variable capacity compressor
according to the present invention, the pressure of the cooling
medium outlet port side acting on the valve body of valve rod (the
pressure "Pc" to be fed to the crank chamber) is transmitted, via
equalizing hole formed in the valve rod, into the equalizing
pressure introducing chamber, enabling the pressure "Pc" to act so
as to push the valve rod downward, i.e. to minimize (cancel) the
pressure difference between the cooling medium feeding pressure
"Pc" and the suction pressure "Ps". As a result, even if the valve
aperture is enlarged to increase the flow rate of cooling medium in
order to make the control valve applicable to a compressor of large
capacity, it is possible to prevent the valve rod (valve body) from
being pushed upward that might has been caused by the effect of
pressure difference between the cooling medium feeding pressure
"Pc" and the suction pressure "Ps", thus overcoming the problems
involved in the control of valve. As a result, it is now possible
to provide a control valve which is applicable to a compressor of
large capacity while making it possible to share the components
employed in other kinds of control valve.
[0019] Further, part of the cooling medium that has been introduced
into the valve chamber from the discharge pressure cooling medium
inlet port is enabled to enter into the equalizing pressure
introducing chamber through a slide-contacting interface between
the valve rod and the guide hole. In other words, since the leakage
of cooling medium (from the discharge pressure "Pd" to the suction
pressure "Ps") in the conventional control valve can be
substantially prevented and hence the discharge pressure "Pd" is
allowed to pass toward the feeding pressure "Pc", there is no
possibility that the pressure control can be badly affected. As a
result, it is possible to enhance the accuracy of pressure
control.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a longitudinal sectional view illustrating one
embodiment of the control valve for a variable capacity compressor
according to the present invention;
[0021] FIG. 2 is an enlarged longitudinal sectional view
illustrating a main portion of the control valve shown in FIG. 1;
and
[0022] FIG. 3 is a longitudinal sectional view illustrating one
example of the control valve for a variable capacity compressor
according to the prior art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] Next, a specific embodiment of the control valve for a
variable capacity compressor according to the present invention
will be explained in detail with reference to the drawings.
[0024] FIG. 1 shows a longitudinal sectional view illustrating one
embodiment of the control valve for a variable capacity compressor
according to the present invention.
[0025] The control valve 1 for a variable capacity compressor shown
in FIG. 1 is designed such that it is applicable to a compressor of
large capacity while making it possible to share the components
such as the electromagnetic actuator 30, the pressure sensitive
moving member (bellows main body) 40, etc. of the conventional
control valve 5 for a variable capacity compressor which is shown
in FIG. 3. In the following description, the parts or components
which correspond to those of the conventional control valve 5 for a
variable capacity compressor which is shown in FIG. 3 will be
identified by the same reference numbers and the features which
differ from those of the conventional control valve 5 will be
mainly explained.
[0026] The control valve 1 shown in FIG. 1 comprises a valve main
body 20 which is equipped with a valve rod 15 having a valve body
15a which is cross- or T-shaped in cross-section (to be explained
hereinafter in more detail), with a valve chamber 21 provided with
a valve seat (valve aperture) 22 with which the valve body 15a can
be retractivebly contacted, with a plurality of cooling medium
inlet ports 25 for introducing a cooling medium of discharge
pressure "Pd" from the compressor into the outer peripheral portion
of the valve chamber 21 (on the upstream side of the valve seat
22), and with a cooling medium outlet port 26 disposed below
(downstream side of) the valve seat 22 and communicated with the
crank chamber of compressor; and an electromagnetic actuator
30.
[0027] The electromagnetic actuator 30 is equipped with an
electromagnetic coil 32 having a connector 31 for
electroexcitation, a step-attached cylindrical stator 33 disposed
on the inner peripheral side of the electromagnetic coil 32, a
sucking member 34 having U-shaped cross-section and press-inserted
into a lower inner peripheral end portion of the stator 33, a
plunger 37 slidingly disposed to move up and down in a guide pipe
35 and located below the sucking member 34, the cylindrical guide
pipe 35 for guiding the plunger 37, which is fixedly coupled,
through a brazing which is applied to an upper inner peripheral end
35a, to a lower outer peripheral end portion of the stator 33, a
step-attached cylindrical housing 60 disposed covering the outer
peripheral portion of the coil 32, and a short cylindrical holder
50 interposed between an upper end portion of the valve main body
20 and the coil 32.
[0028] A lower end portion of the pipe 35 is fitted inside the
holder 50 and fixedly coupled thereto by means of brazing. A lower
diametrally contracted portion 61 of the housing 60 is externally
inserted over an outer peripheral portion of holder 50. An upper
end portion 62 of the housing 60 is calked to nearly an upper end
portion of the coil 32. At a lower end portion of the holder 50,
there is integrally formed a thin wall flanged cylindrical portion
50a which is externally fitted on an upper outer peripheral wall of
the valve main body 20. The holder 50 is fixed to the valve main
body 20 through the peel-calking work of the cylindrical portion
50a.
[0029] Additionally, a hexagon socket head adjusting screw 65 is
screwed on an upper portion of the stator 33. A pressure sensitive
chamber 45 into which the sucking pressure "Ps" of compressor is to
be introduced is formed between the adjusting screw 65 attached to
the inner peripheral wall of stator 33 and the sucking member 34.
In this pressure sensitive chamber 45, there are disposed, as a
pressure sensitive driving member, a bellows main body 40
consisting of a bellows 41, a downwardly projected upper stopper
42, a reverse U-shaped lower stopper 43 and a compression coil
spring 44. Further, a compression coil spring 46 for urging the
bellows main body 40 to contract (in the direction to contract it
toward the adjusting screw 65) is interposed between the bellows
main body 40 and the sucking member 34. Further, a step-attached
operating rod 14 piercing through the sucking member 34 is
interposed between the reverse U-shaped lower stopper 43 and a
U-shaped portion 37c of plunger 37. Additionally, a valve-opening
spring 47 made of a compression coil spring for urging the valve
rod 15 downward (in the direction to open the valve) by way of the
plunger 37 is interposed between the sucking member 34 and the
U-shaped portion 37b of plunger 37.
[0030] On the other hand, a convex stopper 28 for regulating the
lowermost descending position of the plunger 37 is projected from
an upper central portion of the valve main body 20. A guide hole 19
(to be described in detail hereinafter) in which the valve rod 15
is slidingly inserted is formed at a central portion of the valve
main body 20 which is located over the valve chamber and also at a
central portion of the convex stopper 28. A suction pressure
cooling medium-introducing chamber 23 into which the cooling medium
of suction pressure "Ps" of compressor is formed between the
plunger 37 and an upper outer periphery of the valve main body 20
(an outer peripheral wall of the convex stopper 28). A plurality of
suction pressure cooling medium-introducing ports 27 are formed in
the outer wall of the suction pressure cooling medium-introducing
chamber 23. A cooling medium of sucking pressure "Ps" that has been
introduced into the suction pressure cooling medium-introducing
chamber 23 from the cooling medium-introducing ports 27 is designed
to be introduced into the pressure sensitive chamber 45 via
longitudinal grooves 37a formed on the outer peripheral wall of
plunger 37, via a through-hole 37d formed at a central axis of
plunger 37 and via a through-hole 39 formed in the sucking member
34. At the same time, this sucking pressure "Ps" is enabled to act
on a top surface of the valve rod 15.
[0031] A valve-closing spring 48 made of a conical compression
spring for urging the valve rod 15 upward to press an upper end
portion of valve rod 15 against the through hole 37d portion of
plunger 37 is disposed in the cooling medium outlet port 26
disposed at a lowermost portion of the valve main body 20.
[0032] In the control valve 1 of this embodiment, the diameters of
the valve aperture 22, the valve rod 15 and the guide hole 10 are
all made larger than those of the control valve 5 shown in FIG. 3
described above so as to make the control valve 20 applicable to a
compressor of large capacity. Further, as clearly seen from FIG. 1
and FIG. 2 (partially enlarged), a contracted hole portion 19b is
formed at an upper portion of the guide hole 19, and a diametrally
reduced rod portion 15b which can be slidingly inserted into the
contracted hole portion 19b is formed at an upper portion of the
valve rod 15. The valve rod 15 is provided with an equalizing hole
51 for introducing a cooling medium pressure "Pc" of the cooling
medium outlet port 26 into an equalizing pressure introducing
chamber 52 which is interposed between an enlarged hole portion 19A
located below the contracted hole portion 19b of the guide hole 19
and a diametrally enlarged rod portion 15A located below the
diametrally reduced rod portion 15b of the valve rod 15. This
equalizing hole 51 extends, piercing through the axis of the valve
rod 15, from a lower end of the valve rod 15 up to an upper portion
of the valve rod 15 which is located near the diametrally reduced
rod portion 15b. A plurality of lateral holes opening to the
equalizing pressure introducing chamber 52 are formed at an upper
portion of the valve rod 15. On an outer circumferential portion of
the enlarged hole portion 19A of valve rod 15 (a lower end portion
of the valve rod 15), which is adapted to be slidingly contacted
with the guide hole 19, there are formed three annular grooves
15c.
[0033] In the control valve 1 constructed as described above, when
the solenoid portion consisting of the coil 32, the stator 33 and
the sucking member 34 is electroexcited, the plunger 37 is drawn
toward the sucking member 34, forcing the valve rod 15 to move
upward (in the valve-closing direction) by the urging force of the
valve-closing spring 48. On the other hand, the cooling medium of
suction pressure "Ps" that has been introduced into the cooling
medium-introducing ports 27 from the compressor is introduced from
the suction pressure cooling medium-introducing chamber 23 into the
pressure sensitive chamber 45 via longitudinal grooves 37a formed
on the outer peripheral wall of plunger 37 and via a through-hole
39 formed in the sucking member 34. The bellows main body 40 (the
interior thereof is kept in vacuum) is caused to displace, i.e.
contract or expand depending on the pressure (the suction pressure
"Ps") inside the pressure sensitive chamber 45 (when the suction
pressure "Ps" is high, the bellows main body 40 is contracted, and
when the suction pressure "Ps" is low, the bellows main body 40 is
expanded). Then, this displacement is transmitted, via the
operating rod 14 and the plunger 37, to the valve rod 15, thereby
making it possible to adjust the magnitude of opening of valve (the
effective cross-sectional area of passageway between the valve
aperture 22 and the valve body 15a). Namely, the magnitude of
opening of valve can be determined depending on the sucking force
of the plunger 37 to be effected by the solenoid portion consisting
of the coil 32, the stator 33 and the sucking member 34, on the
urging force of the bellows main body 40, and on the urging force
of the valve-opening spring 47 and the valve-closing spring 48.
Further, depending on this magnitude of opening of valve, the
quantity (magnitude of restriction) of cooling medium of discharge
pressure "Pd" that has been introduced from the discharge pressure
cooling medium inlet port 25 into the valve chamber 21 and that can
be delivered toward the cooling medium outlet port 26, i.e. toward
the crank chamber can be adjusted, thus making it possible to
control the pressure "Pc" (feeding pressure) inside the crank
chamber.
[0034] In the control valve 1 for a variable capacity compressor
according to this embodiment, the pressure of the cooling medium
outlet port side acting on the valve body 15a of valve rod 15 (the
pressure "Pc" to be fed to the crank chamber) is transmitted, via
the equalizing hole 51 formed in the valve rod 15, into the
equalizing pressure introducing chamber 52, enabling the pressure
"Pc" to act so as to push the valve rod 15 downward, i.e. to
minimize (cancel) the pressure difference between the cooling
medium feeding pressure "Pc" and the suction pressure "Ps". As a
result, even if the valve aperture 22 is enlarged to increase the
flow rate of cooling medium in order to make the control valve
applicable to a compressor of large capacity, it is possible to
prevent the valve rod (valve body) from being pushed upward that
might has been caused by the effect of pressure difference between
the cooling medium feeding pressure "Pc" and the suction pressure
"Ps", thus overcoming the problems involved in the control of
valve. As a result, it is now possible to provide a control valve
which is applicable to a compressor of large capacity while making
it possible to share the components employed in other kinds of
control valve.
[0035] Further, part of the cooling medium that has been introduced
into the valve chamber 21 from the discharge pressure cooling
medium inlet port 25 is enabled to enter into the equalizing
pressure introducing chamber 52 through a slide-contacting
interface between the diametrally enlarged rod portion 15A of valve
rod 15 and the enlarged hole portion 19A of guide hole 19. In other
words, since the leakage of cooling medium (from the discharge
pressure "Pd" to the suction pressure "Ps") in the conventional
control valve can be substantially prevented and hence the
discharge pressure "Pd" is allowed to pass toward the feeding
pressure "Pc", there is no possibility that the pressure control
can be badly affected. As a result, it is possible to enhance the
accuracy of pressure control.
[0036] Further, since the annular grooves 15c are formed on the
valve rod 15, it is possible to minimize the leakage of pressure
from the discharge pressure "Pd" to the feeding pressure "Pc" due
to the labyrinth effects by these annular grooves 15c. At the same
time, due to the provision of annular grooves 15c, it is possible
to entrap fine foreign matters that may be intruded into the
sliding interface between the valve rod 15 and the guide hole 19.
As a result, the clogging of the sliding interface between the
valve rod 15 and the guide hole 19 due to fine foreign matters can
be prohibited, thus obviating the operation failure of valve rod
15, e.g. the trouble of valve rod 15 where the valve rod 15 is
prevented from moving upward, thus leaving it behind even if the
plunger 37 is attracted toward the sucking member 34.
* * * * *