U.S. patent application number 12/575615 was filed with the patent office on 2010-04-15 for displacement control valve for variable displacement compressor.
This patent application is currently assigned to DOOWON TECHNICAL COLLEGE. Invention is credited to Ki-jung An, Young-il Chang, Hak-soo Kim, Geon-ho Lee, Yong-ju Lee.
Application Number | 20100092311 12/575615 |
Document ID | / |
Family ID | 42099004 |
Filed Date | 2010-04-15 |
United States Patent
Application |
20100092311 |
Kind Code |
A1 |
Kim; Hak-soo ; et
al. |
April 15, 2010 |
DISPLACEMENT CONTROL VALVE FOR VARIABLE DISPLACEMENT COMPRESSOR
Abstract
The present invention provides a displacement control valve for
a variable displacement compressor, the displacement control valve
including a valve housing, in which a discharge chamber passage and
a crank chamber passage are provided, and a valve body for opening
and closing the valve, characterized in that a motor rotates the
valve body to open and close the valve. Therefore, the present
invention can reduce the overall length of the displacement control
valve to reduce the size of the compressor, thereby achieving a
compact structure of the compressor.
Inventors: |
Kim; Hak-soo; (Daejeon-shi,
KR) ; Chang; Young-il; (Ansan-shi, KR) ; Lee;
Yong-ju; (Suwon-si, KR) ; An; Ki-jung; (Seoul,
KR) ; Lee; Geon-ho; (Seongnam-si, KR) |
Correspondence
Address: |
HAMRE, SCHUMANN, MUELLER & LARSON, P.C.
P.O. BOX 2902
MINNEAPOLIS
MN
55402-0902
US
|
Assignee: |
DOOWON TECHNICAL COLLEGE
Anseing-shi
KR
DOOWON ELECTRONIC CO., LTD
Asan-shi
KR
|
Family ID: |
42099004 |
Appl. No.: |
12/575615 |
Filed: |
October 8, 2009 |
Current U.S.
Class: |
417/212 |
Current CPC
Class: |
F04B 27/1804 20130101;
F04B 39/10 20130101; F04B 2027/1827 20130101; F04B 39/08
20130101 |
Class at
Publication: |
417/212 |
International
Class: |
F04B 49/12 20060101
F04B049/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 9, 2008 |
KR |
10-2008-0099255 |
Claims
1. A displacement control valve for a variable displacement
compressor, the displacement control valve comprising a valve
housing, in which a discharge chamber passage and a crank chamber
passage are provided, and a valve body for opening and closing the
valve, characterized in that a motor rotates the valve body to open
and close the valve.
2. The displacement control valve of claim 1, wherein the motor is
a stepping motor and the opening degree of the valve is controlled
by an input signal.
3. The displacement control valve of claim 2, wherein a first
discharge chamber passage and the crank chamber passage of the
valve housing are connected to each other and a valve groove for
controlling the opening degree between the first discharge chamber
passage and the crank chamber passage is formed in the valve
body.
4. The displacement control valve of claim 3, wherein the first
discharge chamber passage is formed to penetrate the center of the
valve housing.
5. The displacement control valve of claim 3, wherein the first
discharge chamber passage is formed to penetrate a portion of an
upper part of the valve housing.
6. The displacement control valve of claim 3, wherein the valve
groove is formed to penetrate the valve body in the longitudinal
direction.
7. The displacement control valve of claim 1, wherein the motor is
an induction motor in which the rotational torque is determined by
an input current and the displacement control valve further
comprises a balance means for applying a force to the valve body in
an opening direction of the valve.
8. The displacement control valve of claim 7, wherein a first
discharge chamber passage of the valve housing and the crank
chamber passage are connected to each other and a valve groove for
controlling the opening degree between the first discharge chamber
passage and the crank chamber passage is formed in the valve
body.
9. The displacement control valve of claim 8, wherein the first
discharge chamber passage is formed to penetrate the center of the
valve housing.
10. The displacement control valve of claim 8, wherein the first
discharge chamber passage is formed to penetrate a portion of an
upper part of the valve housing.
11. The displacement control valve of claim 8, wherein the valve
groove is formed to penetrate the valve body in the longitudinal
direction.
12. The displacement control valve of claim 7, wherein the balance
means comprises: a movable groove formed in the valve housing; a
movable projection formed in the valve body and inserted into the
movable groove; and a spring inserted between the movable groove
and the movable projection.
13. The displacement control valve of claim 7, wherein the balance
means comprises: a second discharge chamber passage formed in the
valve housing; a suction chamber passage formed in the valve
housing; and first and second pressure grooves formed in the valve
body to correspond to the second discharge chamber passage and the
suction chamber passage, respectively.
14. The displacement control valve of claim 13, wherein an
off-spring is inserted between the second discharge chamber passage
and the first pressure groove.
15. The displacement control valve of claim 13, wherein an
off-spring is interposed between a centering groove formed in the
valve housing and the valve body.
16. The displacement control valve of claim 1, wherein a spring is
inserted between the bottom of the valve housing and the bottom of
the valve body.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 2008-0099255, filed on Oct. 9, 2008,
the disclosure of which is incorporated herein by reference in its
entirety.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a displacement control
valve for a variable displacement compressor and, more
particularly, to a displacement control valve for a variable
displacement compressor, which can reduce its overall length to
reduce the size of the compressor, thereby achieving a compact
structure of the compressor.
[0004] 2. Discussion of Related Art
[0005] Since a compressor used in a refrigeration cycle of a
vehicular air-conditioning system is directly coupled to an engine
by a belt, the speed of the compressor cannot be controlled
independently.
[0006] Therefore, a variable displacement compressor capable of
changing the discharge volume of refrigerant to achieve an adequate
cooling performance without restriction by the engine speed has
been widely used recently.
[0007] Various types of variable displacement compressors such as
the so-called swash plate type, rotary type, and scroll type
compressors are used.
[0008] In the swash plate type compressor, a swash plate provided
in a crank chamber such that the inclination angle of the plate is
varied is rotated by the rotational movement of a rotating shaft,
and a piston is reciprocated by the rotational movement of the
swash plate. In this case, the refrigerant in a suction chamber is
sucked into a cylinder by the reciprocating movement of the piston,
compressed and discharged into a discharge chamber. At this time,
the inclination angle of the swash plate is changed by a difference
between the pressure in the crank chamber and the pressure in the
cylinder, and thus the discharge volume of refrigerant is
controlled.
[0009] Especially, an electronic solenoid type displacement control
valve, which is actuated by an electric current, is adopted to
control the pressure of the crank chamber such that the inclination
angle of the swash plate is controlled, thereby controlling the
discharge volume.
[0010] In this case, the displacement control valve is operated in
such a manner that detection signals such as the rotational speed
of the engine, the temperatures inside and outside the vehicle, and
the temperature of an evaporator are calculated by a controller
incorporating a CPU or the like and a control signal based on the
calculated results is applied to an electromagnetic coil of the
displacement control valve as an operating current.
[0011] A typical example of the displacement control valve for the
variable displacement compressor is disclosed in U.S. Pat. No.
6,443,708 (hereinafter referred to as a "prior art"), and the
schematic configuration thereof will be described with reference to
FIG. 1 below.
[0012] As shown in the figure, the displacement control valve 20
for the variable displacement compressor in accordance with the
prior art comprises a valve housing 40, a valve body 30, and an
electromagnetic solenoid such that the valve body 30 is
reciprocated as the electromagnetic solenoid is actuated by an
electric current to open and close a discharge chamber passage 6
formed in the valve housing 40.
[0013] In the valve housing 40, a suction chamber passage 8
receiving the pressure of a suction chamber, a crank chamber
passage 5 receiving the pressure of a crank chamber, and the
discharge chamber passage 6 receiving the pressure of a discharge
chamber of the compressor are provided. The discharge chamber
passage 6 and the crank chamber passage 5 are connected to each
other.
[0014] Moreover, the valve body 30 is reciprocated by the
electromagnetic solenoid actuated by an electric current and passes
through the crank chamber passage 5 during the reciprocating
movement to open and close the discharge chamber passage 6. A
spring 28 is provided at the bottom of the valve body 30 such that
the valve body 30 descends during normal times when there is no
external force to maintain the opened state of the discharge
chamber passage 6.
[0015] The electromagnetic solenoid comprises a movable rod 24
connected to the valve body 30 and an electromagnetic coil 21
arranged on the circumference of the movable rod 24. A movable iron
core 23 is provided at an end of the movable rod 24.
[0016] However, according to the prior art having the
above-described structure, since the valve body 30 is configured to
linearly reciprocate from the crank chamber passage 5, in which
crank chamber pressure Pc acts, to the discharge chamber passage 6,
in which discharge chamber pressure Pd acts, so as to open and
close the crank chamber passage 5, the overall length of the
displacement control valve 20 is increased, and thus the size of
the compressor in which the displacement control valve 20 is
installed is increased.
[0017] Moreover, there are problems that the manufacturing
efficiency is degraded due to its complicated structure and
configuration and the number of manufacturing processes is
increased.
SUMMARY OF THE INVENTION
[0018] The prevent invention has been made in an effort to solve
the above-described problems associated with the prior art, and an
object of the present invention is to provide a displacement
control valve for a variable displacement compressor, which can
reduce its overall length to reduce the size of the compressor,
thereby achieving a compact structure of the compressor.
[0019] Another object of the present invention is to provide a
displacement control valve for a variable displacement compressor,
which can simplify its structure to improve the manufacturing
efficiency thereof.
[0020] Still another object of the present invention is to provide
a displacement control valve for a variable displacement
compressor, which can control the discharge volume using a balance
of forces between a balance means and a motor.
[0021] According to an aspect of the present invention for
achieving the above objects, there is provided a displacement
control valve for a variable displacement compressor, the
displacement control valve including a valve housing, in which a
discharge chamber passage and a crank chamber passage are provided,
and a valve body for opening and closing the valve, characterized
in that a motor rotates the valve body to open and close the
valve.
[0022] Preferably, the motor may be a stepping motor and the
opening degree of the valve may be controlled by an input
signal.
[0023] Preferably, a first discharge chamber passage of the valve
housing and the crank chamber passage may be connected to each
other, and a valve groove for controlling the opening degree
between the first discharge chamber passage and the crank chamber
passage may be formed in the valve body.
[0024] Preferably, the first discharge chamber passage may be
formed to penetrate the center of the valve housing.
[0025] Preferably, the first discharge chamber passage may be
formed to penetrate a portion of an upper part of the valve
housing.
[0026] Preferably, the valve groove may be formed to penetrate the
valve body in the longitudinal direction.
[0027] Preferably, the motor may be an induction motor in which the
rotational torque is determined by an input current, and the
displacement control valve may further include a balance means for
applying a force to the valve body in an opening direction of the
valve.
[0028] Preferably, the balance means may include: a movable groove
formed in the valve housing; a movable projection formed in the
valve body and inserted into the movable groove; and a spring
inserted between the movable groove and the movable projection.
[0029] Preferably, the balance means may include: a second
discharge chamber passage formed in the valve housing; a suction
chamber passage formed in the valve housing; and first and second
pressure grooves formed in the valve body to correspond to the
second discharge chamber passage and the suction chamber passage,
respectively.
[0030] Preferably, an off-spring may be inserted between the second
discharge chamber passage and the first pressure groove.
[0031] Preferably, an off-spring may be interposed between a
centering groove formed in the valve housing and the valve
body.
[0032] Preferably, a spring may be inserted between the bottom of
the valve housing and the bottom of the valve body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The above and other objects, features and advantages of the
present invention will become more apparent to those of ordinary
skill in the art by describing in detail exemplary embodiments
thereof with reference to the accompanying drawings, in which:
[0034] FIG. 1 is a longitudinal cross-sectional view showing the
structure of a displacement control valve in accordance with a
prior art;
[0035] FIG. 2 is a longitudinal cross-sectional view showing the
structure of a variable displacement compressor in accordance with
the present invention;
[0036] FIG. 3A is a longitudinal cross-sectional view showing the
structure of a displacement control valve in accordance with a
first embodiment of the present invention;
[0037] FIG. 3B is a longitudinal cross-sectional view showing a
closed state of FIG. 3A;
[0038] FIG. 4 is a plan view of FIG. 3A;
[0039] FIG. 5 is a plan view showing the structure of a
displacement control valve in accordance with a second embodiment
of the present invention;
[0040] FIG. 6 is a plan view showing the structure of a
displacement control valve in accordance with a third embodiment of
the present invention;
[0041] FIG. 7A is a longitudinal cross-sectional view taken along
line I-I of FIG. 6; and
[0042] FIG. 7B is a longitudinal cross-sectional view taken along
line II-II of FIG. 6.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0043] Hereinafter, exemplary embodiments of the present invention
will be described in detail below with reference to the
accompanying drawings such that those skilled in the art to which
the present invention pertains can easily practice the present
invention.
[0044] First, the structure of a swash plate type variable
displacement compressor including a displacement control valve in
accordance with the present invention will be schematically
described with respect to FIGS. 2 to 4.
[0045] FIG. 2 is a longitudinal cross-sectional view showing the
structure of a swash plate type variable displacement compressor in
accordance with the present invention, FIG. 3A is a longitudinal
cross-sectional view showing the structure of a displacement
control valve in accordance with a first embodiment of the present
invention, FIG. 3B is a longitudinal cross-sectional view showing a
closed state of FIG. 3A, and FIG. 4 is a plan view of FIG. 3A.
[0046] As shown in the figures, a swash plate type variable
displacement compressor C comprises a cylinder block 110 having a
plurality of cylinder bores 112 arranged in parallel in a
longitudinal direction on its periphery, a front housing 116
air-tightly connected to the front of the cylinder block 110, and a
rear housing 118 air-tightly connected to the rear of the cylinder
block 110 with a valve plate 120 interposed therebetween.
[0047] A crank chamber 186 is provided in the front housing 116.
One end of a drive shaft 144 is rotatably supported around the
center of the front housing 116, and the other end of the drive
shaft 144 passes through the crank chamber 186 and is supported by
a bearing provided in the cylinder block 110.
[0048] Moreover, a lug plate 154 and a swash plate 150 are provided
around the circumference of the drive shaft 144 in the crank
chamber 186.
[0049] A pair of support arms 162 for transmitting power, each
having a guide hole 164 formed to penetrate its center, are formed
to protrude from one side of the lug plate 154 and a ball 166 is
formed on one side of the swash plate 150 such that the ball 166 of
the swash plate 150 is slidably moved in the guide hole 164 of the
lug plate 154 by the rotation of the lug plate 154 to change the
inclination angle of the swash plate 150.
[0050] Moreover, a plurality of pistons 114 are slidably inserted
into the outer circumferential surface of the swash plate 150 with
a shoe 176 interposed therebetween.
[0051] Therefore, the pistons 114 inserted into the outer
circumferential surface of the swash plate 150 with the shoe 176
interposed therebetween are reciprocated in each of the cylinder
bores 112 of the cylinder block 110 by the rotation of the inclined
swash plate 150.
[0052] A suction chamber 122 and a discharge chamber 124 are formed
in the rear housing 118, and a suction port 132 and a discharge
port 136 are formed in the valve plate 120, interposed between the
rear housing 118 and the cylinder block 110, in a position
corresponding to each of the cylinder bores 112.
[0053] Refrigerant of the suction chamber 122 is sucked into the
cylinder bores 112 by the reciprocating movement of the pistons
114, compressed and discharged into the discharge chamber 124. At
this time, the inclination angle of the swash plate 150 is changed
by a difference between the pressure in the crank chamber 186 and
the pressure in the cylinder bore 112, and thus the discharge
volume of refrigerant is controlled.
[0054] In detail, the variable displacement compressor in
accordance with the present invention employs a displacement
control valve 200 to be opened and closed by an electric current
such that the pressure of the crank chamber 186 is controlled and
the inclination angle of the swash plate 150 is adjusted, thus
controlling the discharge volume.
[0055] A displacement control valve in accordance with a first
embodiment of the present invention will now be described with
reference to FIGS. 3A, 3B, and 4.
[0056] As shown in the figures, the displacement control valve 200
in accordance with the first embodiment of the present invention
comprises a valve housing 210 having a pair of upper and lower
housings, a valve body 220 rotatably mounted in the valve housing
210, and a motor 230 axially connected to the valve body 220 to
transmit a drive force.
[0057] A crank chamber passage 211 in which pressure Pc of the
crank chamber 186 acts and a first discharge chamber passage 212 in
which pressure Pd of the discharge chamber 124 acts are provided in
the valve housing 210. The crank chamber passage 211 and the first
discharge chamber passage 212 are connected to each other by the
rotation of the valve body 220.
[0058] Moreover, the first discharge chamber passage 212 is formed
at the top of the valve housing 210, and the crank chamber passage
211 is formed perpendicularly to the side of the valve housing
210.
[0059] Meanwhile, the first discharge chamber passage 212 may be
formed to penetrate the center of the valve housing 210 as shown in
(a) of FIG. 4 or may be formed to penetrate a portion of the upper
of the valve housing 210 as shown in (b) of FIG. 4.
[0060] The valve body 220 is closely adhered to the top of the
valve housing 210 and includes a valve groove 221 formed on one
side of the valve body 220 to control the opening degree between
the first discharge chamber passage 212 and the crank chamber
passage 211.
[0061] The valve groove 221 may be formed to penetrate the valve
body 220 in the longitudinal direction or may be configured in the
form of a groove from which a portion is removed as shown in the
figures. Moreover, it is sufficient that the valve groove 221 has a
structure which can connect the crank chamber passage 211 to the
discharge chamber passage 212, and there is no necessity to limit
the shape of the valve groove 221.
[0062] Therefore, as an electric current is applied to the motor
230 comprising a stator 231 and a rotor 232, the valve body 220 is
rotated such that the first discharge chamber passage 212 formed in
the valve housing 210 is opened and closed by the valve groove
221.
[0063] Meanwhile, the motor 230 comprises a stepping motor which is
rotated by a predetermined angle in response to a pulse signal and,
since this stepping motor is well known in the art, its detailed
description will be omitted.
[0064] Moreover, it is preferable that a spring (not shown) is
provided at the bottom of the valve body 220 such that the top of
the valve body 220 is closely adhered to the inside of the valve
housing 210, thus preventing the discharge pressure from
leaking.
[0065] Next, the operation of the displacement control valve in
accordance with the first embodiment of the present invention will
be described with reference to the drawings.
[0066] First, in the initial state, the power supply to the
displacement control valve 200 is cut off and, in this state, the
valve groove 221 of the valve body 220 connects the first discharge
chamber passage 212 and the crank chamber passage 211 and maintains
the opened state (refer to FIG. 3A).
[0067] Here, the motor 230 is a stepping motor and the valve groove
221 is located in a position that connects the first discharge
chamber passage 212 and the crank chamber passage 211 during power
supply cut-off.
[0068] Therefore, since the discharge pressure Pd passes through
the first discharge chamber passage 212 and the crank chamber
passage 211 and acts on the crank chamber 186, the pressure of the
crank chamber 186 is increased and the inclination angle of the
swash plate 150 is rapidly reduced, thereby reducing the discharge
volume of refrigerant.
[0069] Then, when detection signals such as the rotational speed of
an engine, the temperatures inside and outside a vehicle, and the
downstream temperature and pressure of an evaporator are applied to
a motor control unit (MCU), the MCU calculates a thermal load based
on the detection signals and, if the calculated thermal load
exceeds a predetermined value, a current signal for increasing the
discharge volume of refrigerant is applied to a power source.
[0070] Accordingly, an increased current flows through the motor
230 to rotate the motor 230 and, at the same time, the valve body
220 connected to the motor 230 is also rotated, thereby closing the
first discharge chamber passage 212 or the crank chamber passage
211.
[0071] As a result, the pressure in the crank chamber 186 is
reduced and the inclination angle of the swash plate 150 is
increased, thus rapidly increasing the discharge volume and
pressure of the compressor.
[0072] Meanwhile, although the above description refers to the
first discharge chamber passage 212 which is completely opened or
closed, the discharge volume and pressure of the compressor can be
readily adjusted since the opening degree between the first
discharge chamber passage 212 and the crank chamber passage 211 is
determined by the current value input to the stepping motor
230.
[0073] Next, displacement control valves in accordance with second
and third embodiments of the present invention will be described,
in which the same elements as those of the first embodiment are
designated by the same reference numerals, and their detailed
description will be omitted.
[0074] FIG. 5 is a plan view showing the structure of a
displacement control valve in accordance with a second embodiment
of the present invention, FIG. 6 is a plan view showing the
structure of a displacement control valve in accordance with a
third embodiment of the present invention, FIG. 7A is a
longitudinal cross-sectional view taken along line I-I of FIG. 6,
and FIG. 7B is a longitudinal cross-sectional view taken along line
II-II of FIG. 6.
[0075] First, each of the displacement control valves 200' and
200'' in accordance with the second and third embodiments of the
present invention is configured in the same manner as the
displacement control valve 200 of the first embodiment. That is,
each of the displacement control valves 200' and 200'' comprises a
valve housing 210 in which a first discharge chamber passage 212
and a crank chamber passage 211 are connected to each other, a
valve body 220 including a valve groove 221 configured to rotatably
open and close the first discharge chamber passage 212, and a motor
230 for transmitting drive power to the valve body 220.
[0076] However, a typical induction motor is used as the motor 230
in the second and third embodiment of the present invention, and
the valve groove 221 rotatably opens and closes the first discharge
chamber passage 212 by the rotation of the motor 230.
[0077] Meanwhile, since the motor 230 is an induction motor which
is rotated when an electric current is applied thereto in a manner
different from the stepping motor which is rotated by a
predetermined angle in response to a pulse signal, it is necessary
to regulate the rotation range.
[0078] Therefore, a balance means 240 for applying a rotational
force proportional to the rotational force of the motor 230 in the
opposite direction is further provided.
[0079] FIG. 5 shows the displacement control valve 200' in
accordance with the second embodiment, in which the balance means
240 comprises a movable groove 241 formed in the valve housing 210,
a movable projection 242 formed in the valve body 220 and inserted
into the movable groove 241, and a spring 243 inserted between the
movable groove 241 and the movable projection 242.
[0080] Meanwhile, although the balance means 240 is formed at the
top of the valve housing 210 in FIG. 5, the present invention is
not limited thereto, and the balance means 240 may be formed at the
bottom of the valve housing 210.
[0081] Therefore, when no electric current is applied to the motor
230, the first discharge chamber passage 212 and the crank chamber
passage 211 are opened by the valve groove 221 due to the elastic
force of the spring 243. When an electric current is applied to the
motor 230, the motor 230 is rotated and, at the same time, the
valve body 220 is rotated, thereby closing the first discharge
chamber passage 212 or the crank chamber passage 211.
[0082] At this time, the spring 243 applies a rotational force
F.sub.1 to the valve body 220 in a direction that opens the first
discharge chamber passage 212 and the motor 230 applies a
rotational force F.sub.2 corresponding to the rotational force
F.sub.1 of the spring 243 based on the amount of current applied to
the motor 230, thereby controlling the rotation of the valve body
220. As a result, it is possible to change the discharge volume and
pressure of the compressor by controlling the opening degree
between the first discharge chamber passage 212 and the crank
chamber passage 211.
[0083] Meanwhile, FIGS. 6 and 7 show the displacement control valve
200'' in accordance with the third embodiment, in which a balance
means 240 comprises a second discharge chamber passage 241 formed
in the valve housing 210, a suction chamber passage 242 formed in
the valve housing 210, and first and second pressure grooves 243
and 244 formed in the valve body 220 to correspond to the second
discharge chamber passage 241 and the suction chamber passage 242,
respectively.
[0084] Here, discharge pressure Pd by the second discharge chamber
passage 241 is applied to the first pressure groove 243 to rotate
the valve body 220 in a direction that opens the first discharge
chamber passage 212, and suction pressure Ps by the suction chamber
passage 242 is applied to the second pressure groove 244 to rotate
the valve body 220 in a direction that closes the first discharge
chamber passage 212.
[0085] As a result, the discharge pressure Pd is higher than the
suction pressure Ps, and thus the rotational force F.sub.1 is
applied to rotate the valve body 220 in a direction that opens the
first discharge chamber passage 212.
[0086] On the contrary, the motor 230 applies the rotational force
F.sub.2 proportional to the amount of current applied to the motor
230 to rotate the valve body 220 in a direction that closes the
first discharge chamber passage 212.
[0087] Moreover, an off-spring 245 is inserted between the second
discharge chamber passage 241 and the first pressure groove
243.
[0088] The installation position of the off-spring 245 is not
limited to the space between the second discharge chamber passage
241 and the first pressure groove 243 and may be interposed between
a centering groove 213 formed in the valve housing 210 and the
valve body 220.
[0089] Therefore, when no electric current is applied to the motor
230, the first discharge chamber passage 212 is opened by the valve
groove 221 due to the elastic force of the spring 243. When an
electric current is applied to the motor 230, the motor 230 is
rotated and, at the same time, the valve body 220 is rotated,
thereby closing the first discharge chamber passage 212 or the
crank chamber passage 211.
[0090] At this time, the discharge pressure Pd and the suction
pressure Ps act on the first and second pressure grooves 243 and
244, respectively, to apply the rotational force F.sub.1 for
rotating the valve body 220 in a direction that opens the first
discharge chamber passage 212 and the motor 230 applies the
rotational force F.sub.2 corresponding to the rotational force
F.sub.1 based on the amount of current applied to the motor 230,
thereby controlling the opening degree of the valve. Therefore, it
is possible to change the discharge volume and pressure of the
compressor.
[0091] As a result, the opening degree of the valve is determined
by the balance between the rotational force F.sub.1, obtained by
subtracting the suction pressure Ps value from the discharge
pressure Pd value, and the rotational force F.sub.2 of the motor
230, which is determined in proportion to the amount of current
applied to the motor 230.
[0092] As described above, according to the displacement control
valve for the variable displacement compressor of the present
invention, it is possible to reduce the overall length of the
displacement control valve to reduce the size of the compressor,
thereby achieving a compact structure of the compressor.
[0093] Moreover, it is possible to simplify the structure of the
displacement control valve, thereby improving the manufacturing
efficiency thereof.
[0094] Furthermore, it is possible to control the discharge volume
using a balance of forces between the balance means and the
motor.
[0095] It will be apparent to those skilled in the art that various
modifications can be made to the above-described exemplary
embodiments of the present invention without departing from the
spirit or scope of the invention. Thus, it is intended that the
present invention covers all such modifications provided they come
within the scope of the appended claims and their equivalents.
* * * * *