U.S. patent application number 11/178482 was filed with the patent office on 2006-01-12 for flow control valve for engine cooling water.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Akira Furukawa, Douji Imai, Shinji Ishida, Yuichiro Miura.
Application Number | 20060005789 11/178482 |
Document ID | / |
Family ID | 35540012 |
Filed Date | 2006-01-12 |
United States Patent
Application |
20060005789 |
Kind Code |
A1 |
Miura; Yuichiro ; et
al. |
January 12, 2006 |
Flow control valve for engine cooling water
Abstract
A flow control valve comprises a first valve for controlling a
radiator flow amount and a second valve for controlling a bypass
flow amount. Pressure adjusting passages are respectively provided
for the first and second valves for communicating spaces formed at
both sides of the respective valves to equalize fluid pressures at
both sides, so that a pressure load in an axial direction to the
respective valves can be eliminated. As a result, a driving force
of an actuator of the flow control valve for directly or indirectly
driving the first and second valves can be reduced.
Inventors: |
Miura; Yuichiro;
(Kariya-city, JP) ; Ishida; Shinji; (Kariya-city,
JP) ; Furukawa; Akira; (Kariya-city, JP) ;
Imai; Douji; (Kariya-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
35540012 |
Appl. No.: |
11/178482 |
Filed: |
July 12, 2005 |
Current U.S.
Class: |
123/41.1 |
Current CPC
Class: |
F01P 2070/08 20130101;
F01P 2007/146 20130101; F01P 7/16 20130101 |
Class at
Publication: |
123/041.1 |
International
Class: |
F01P 7/14 20060101
F01P007/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 2004 |
JP |
2004-205097 |
Claims
1. A flow control valve of engine cooling water for a vehicle
comprising: a valve housing having a first inlet port to be
connected to a radiator, a second inlet port to be connected to a
bypass passage and an outlet port to be connected to a water pump,
the valve housing further having a first valve passage forming a
part of a radiator cooling circuit in which the engine cooling
water is circulated from the an engine to the water pump through
the radiator, the valve housing further having a second valve
passage forming a part of a bypass circuit in which the engine
cooling water is circulated from the engine to the water pump
through the bypass passage bypassing the radiator; an actuator for
generating a driving force in accordance with an operational
condition of the engine; a first valve movably housed in the valve
housing and moved in its axial direction upon operatively receiving
the driving force from the actuator, so that an opening degree of
the first valve passage is controlled; a second valve movably
housed in the valve housing and moved in its axial direction upon
operatively receiving the driving force from the actuator, so that
an opening degree of the second valve passage is controlled; and a
pressure adjusting passage for equalizing fluid pressures at both
axial sides of at least one of the first and the second valves.
2. A flow control valve according to claim 1, wherein the pressure
adjusting passage is formed in the first valve, extending in the
axial direction to communicate spaces respectively formed at the
both axial sides of the first valve with each other.
3. A flow control valve according to claim 1, wherein the pressure
adjusting passage is formed in the second valve, extending in the
axial direction to communicate spaces respectively formed at the
both axial sides of the second valve with each other.
4. A flow control valve according to claim 1, wherein the actuator
has a rotor shaft rotating at an axis which is coaxial with a
center axis of the first valve, and the axial direction of the
second valve is almost perpendicular to the axial direction of the
rotor shaft.
5. A flow control valve according to claim 4, wherein the first
valve has a profile for driving the second valve in its axial
direction, so that a desired bypass flow amount with respect to a
rotational angle of the rotor shaft is obtained, and the second
valve is biased toward the profile by a biasing means.
6. A flow control valve according to claim 1, wherein the valve
housing further comprises: a mixing chamber for mixing the engine
cooling water of a low temperature from the radiator with the
engine cooling water of a high temperature bypassing the radiator;
a radiator side passage for flowing the engine cooling water from
the radiator into the mixing chamber; a bypass side passage for
flowing the engine cooling water from the bypass passage into the
mixing chamber; and a pump side passage for flowing out the engine
cooling water from the mixing chamber to the water pump.
7. A flow control valve according to claim 1, wherein the valve
housing has further a third valve passage forming a part of a
heater circuit in which the engine cooling water is circulated from
the engine to the water pump through a heater.
8. A flow control valve according to claim 7, further comprising: a
third valve movably housed in the valve housing and moved in its
axial direction upon operatively receiving the driving force from
the actuator, so that an opening degree of the third valve passage
is controlled; and another pressure adjusting passage for
equalizing fluid pressures at both axial sides of the valve.
9. A flow control valve according to claim 8, wherein the other
pressure adjusting passage is formed in the third valve, extending
in the axial direction to communicate spaces respectively formed at
the both axial sides of the third valve with each other.
10. A flow control valve according to claim 8, wherein the actuator
has a rotor shaft rotating at an axis which is coaxial with a
center axis of the first valve, and the axial direction of the
third valve is almost perpendicular to the axial direction of the
rotor shaft.
11. A flow control valve according to claim 10, wherein the first
valve has a profile for driving the third valve in its axial
direction, so that a desired heater flow amount with respect to a
rotational angle of the rotor shaft is obtained, and the third
valve is biased toward the profile by a biasing means.
12. A flow control valve according to claim 7, wherein the valve
housing further comprises: a mixing chamber for mixing the low
temperature engine cooling water radiated at the heater, the engine
cooling water of a low temperature from the radiator and the engine
cooling water of a high temperature bypassing the radiator with one
another; a heater side passage for flowing the engine cooling water
from the heater into the mixing chamber; a radiator side passage
for flowing the engine cooling water from the radiator into the
mixing chamber; a bypass side passage for flowing the engine
cooling water from the bypass passage into the mixing chamber; and
a pump side passage for flowing out the engine cooling water from
the mixing chamber to the water pump.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2004-205097 filed on Jul. 12, 2004, the disclosures of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a flow control valve to be
used in an engine cooling system for a water-cooled engine, in
which engine cooling water is circulated to the engine after having
been cooled at a radiator. In particular, the present invention
relates to a flow control valve for optimizing a temperature of the
engine cooling water, by adjusting a flow amount of the engine
cooling water flowing through the radiator and a flow amount of the
engine cooling water bypassing the radiator, depending on an
operational condition of the engine.
BACKGROUND OF THE INVENTION
[0003] An engine cooling system for a water-cooled engine is known
in the art as a system for cooling an engine mounted in a vehicle
having a radiator, in which engine cooling water is circulated into
the engine after having been cooled at the radiator. A thermostat
is provided in such an engine cooling system, so that the engine
cooling water bypasses the radiator by an operation of the
thermostat when the temperature of the cooling water is lower than
a predetermined value and is circulated back to the engine through
a water pump.
[0004] In recent years, two opposing requirements for an engine,
such as a higher engine output and a lower fuel consumption ratio,
have been increased. An engine cooling system, which could meet
such requirements for the engine, is accordingly desired. Namely,
it is necessary to increase a cooling efficiency at the engine by
decreasing the cooling water temperature, and to maintain the
temperature at every portion of the engine at such a temperature
lower than a durability limit temperature with respect to a thermal
load, in order to realize the higher engine output. On the other
hand, it is necessary to increase a combustion efficiency at a
combustion chamber of the engine, by increasing the cooling water
temperature, in order to achieve the lower fuel consumption ratio.
As above, such a engine cooling system is required, which could
control the cooling water temperature in accordance with various
operational conditions of the engine, for example, a high-speed
high-load operation of the engine which is a high-speed running of
the vehicle with the high engine output, a low-speed high-load
operation during the vehicle is running on an up-hilling road, a
low-speed low-load operation or a normal operation which is an
operation for the low fuel consumption ratio, a re-starting
operation of the engine after an engine stop (an engine idling stop
operation) for the purpose of a lower harmful emission and the low
fuel consumption ratio, and so on.
[0005] An engine cooling system for the water-cooled engine has
been proposed in the art, in which a flow control valve is provided
to make it possible to control the cooling water temperature
depending on the various operational conditions of the engine.
According to such a cooling system, a flow control valve is
provided at an interfluent portion of a cooling water circuit and a
bypass circuit, so that a flow amount of the cooling water to the
radiator (hereinafter also called as "the radiator flow amount")
and a flow amount of the cooling water bypassing the radiator
(hereinafter also called as "the bypass flow amount") are precisely
controlled. The flow control valve can control the cooling water
temperature more precisely than the control valve operated by the
thermostat, and thereby the lower fuel consumption ratio is
achieved.
[0006] However, an extremely high fluid pressure is applied by a
water pump to a valve body of the flow control valve provided in
the engine cooling system, when the valve body is operated by an
actuator, independently whether the engine operation is in the
high-load operation or in the normal operation. Accordingly, a
large operating force or driving torque is necessary for a driving
shaft of the actuator to move the valve body. The actuator becomes
larger in its size or higher in cost, when it is necessary to
provide a reduction device (a gear reduction device) between the
driving shaft of the actuator and a moving shaft of the valve body,
for reducing a rotational speed of the driving shaft of the
actuator to a certain reduction ratio.
[0007] In view of the above problem, another flow control valve is
proposed, for example, as disclosed in Japanese Patent Publication
No. 2003-286843 (which corresponds to U.S. Pat. No. 6,837,193 B2),
in which the driving torque required for the actuator is decreased
to achieve a small sized actuator. More specifically, a driving
load applied to the flow control valve is canceled by a pressure
difference between a radiator flow pressure and a bypass flow
pressure, to decrease the driving load for the actuator. In the
above flow control valve, a first valve body and a first valve seat
for controlling the radiator flow amount (of the cooling water
flowing through the engine and the radiator and returning to the
water pump) and a second valve body and a second valve seat for
controlling the bypass flow amount (of the cooling water flowing
through the engine, bypassing the radiator, and returning to the
water pump) are provided, wherein the first valve body and the
second valve body are integrally formed as a single valve body
which is then driven by the actuator.
[0008] In the above flow control valve, however, the radiator flow
pressure and the bypass flow pressure may be largely differed from
each other, during the high-load operation of the engine during
which only the first valve body is opened, or in a case that a
difference between fluid flow resistances appears due to a
difference of passage diameters between a radiator side passage and
a bypass passage. Then it would become difficult to cancel the
driving load applied to the flow control valve the pressure
difference between the radiator flow pressure and the bypass flow
pressure. As a result, the above flow control valve can not
sufficiently achieve the effect for decreasing the driving load to
the actuator.
SUMMARY OF THE INVENTION
[0009] It is, therefore, an object of the present invention to
provide a flow control valve, in which a load to a driving
operation by an actuator is minimized, independently of a closing
or opening state of a radiator flow control valve and a bypass flow
control valve and independently of fluid pressure of the radiator
flow or the bypass flow, by canceling a pressure load to the
radiator flow control valve and/or bypass flow control valve during
the valve (or valves) is moved in its axial direction.
[0010] It is a further object of the present invention to provide a
flow control valve, which is smaller in size and which can
eliminate a reduction device.
[0011] According to a feature of the present invention, a flow
control valve comprises a first and a second valve, which are
respectively and movably housed in a valve housing, and an actuator
for directly or indirectly driving the first and second valves,
wherein the first valve controls a radiator flow amount of engine
cooling water flowing through a radiator and the second valve
controls a bypass flow amount of the engine cooling water bypassing
the radiator. The radiator flow amount and the bypass flow amount
are independently controlled by the actuator depending on an
operational condition of an engine. As a result, a temperature of
the engine cooling water can be controlled at a desired value
corresponding to the respective operational conditions of the
engine.
[0012] According to another feature of the present invention, the
flow control valve further comprises pressure adjusting passages
for the respective first and second valves for communicating with
each other spaces formed at both sides of the respective valves, so
that the fluid pressure at both sides of the respective valves are
equalized. As a result, a pressure load to the first and second
valve is cancelled during the valve (or valves) is moved in its
axial direction.
[0013] According to a further feature of the present invention, the
second valve is arranged that an axial direction of the second
valve is almost perpendicular to an axial direction of the first
valve, so that fluid pressure applied to the second valve does not
adversely influence on an axial movement of the first valve, and
vice versa.
[0014] According to a still further feature of the present
invention, a cam face is formed at an outer surface of the first
valve, and the second valve is arranged that its axial direction is
almost perpendicular to the axial direction of the first valve and
a forward end of the second valve is brought into contact with the
cam face. As a result, the second valve can be moved in its axial
direction in accordance with the axial movement of the first valve,
so that a desired characteristic of the bypass flow amount can be
obtained by suitably designing a shape of the cam face.
[0015] According to a still further feature of the present
invention, the flow control valve can be used as a control valve
for controlling a heater flow amount, in addition to the radiator
flow amount and the bypass flow amount. For the purpose of
controlling the heater flow amount of the engine cooling water (hot
water) for heating air to be blown into a passenger room of a
vehicle, a third valve is movably provided in the flow control
valve.
[0016] According to the further feature of the present invention,
another cam face is likewise formed at the outer surface of the
first valve, and the third valve is arranged that its axial
direction is almost perpendicular to the axial direction of the
first valve and a forward end of the third valve is brought into
contact with the cam face. As a result, the third valve can be
moved in its axial direction in accordance with the axial movement
of the first valve, so that a desired characteristic of the heater
flow amount can be obtained by suitably designing a shape of the
cam face.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description made with reference to the accompanying
drawings. In the drawings:
[0018] FIG. 1A is a schematic view showing an engine cooling system
for a water-cooled engine according to the present invention;
[0019] FIG. 1B is a graph showing characteristics of a radiator
flow amount and a bypass flow amount with respect to a rotational
angle of an actuator;
[0020] FIG. 2 is a vertical cross sectional view of a flow control
valve, according to a first embodiment of the present invention,
showing a starting condition of the valve operation;
[0021] FIGS. 3A and 3B are also vertical cross sectional views of
the flow control valve, respectively showing a valve condition
during a normal operation and a valve condition during a high-load
operation;
[0022] FIGS. 4A to 4C are cross sectional views, respectively taken
along lines IVA-IVA, IVB-IVB, and IVC-IVC in FIG. 2;
[0023] FIGS. 5A and 5B are horizontal cross sectional views
respectively showing a main portion of a flow control valve
according to a second embodiment;
[0024] FIGS. 5C and 5D are vertical cross sectional views
respectively showing further modifications of the flow control
valve according to the second embodiment;
[0025] FIG. 6 is a vertical cross sectional view of a flow control
valve according to a third embodiment of the present invention;
[0026] FIG. 7 is a vertical cross sectional view of a flow control
valve according to a fourth embodiment of the present
invention;
[0027] FIGS. 8A and 8B are respectively a vertical and a horizontal
cross sectional views of a flow control valve according to a fifth
embodiment and its modification of the present invention;
[0028] FIG. 9A is a schematic view showing an engine cooling system
for a water-cooled engine according to the fifth embodiment;
and
[0029] FIG. 9B is a graph showing characteristics of a radiator
flow amount, a bypass flow amount and a heater flow amount with
respect to a rotational angle of an actuator of the fifth
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0030] FIGS. 1A to 4C show a first embodiment of the present
invention, wherein FIG. 1A shows a schematic view showing an engine
cooling system for a water-cooled engine, and FIG. 1B is a graph
showing characteristics of a radiator flow amount and a bypass flow
amount with respect to a rotational angle of an actuator.
[0031] A flow control system according to the present invention
comprises an engine cooling system for a water-cooled engine 1
having a cooling water circuit, a flow control valve 2 provided in
the cooling water circuit, an electronic control unit (not shown
and called hereinafter as ECU) for electronically controlling an
opening degree of the flow control valve 2 depending on operational
conditions of the engine 1. The flow control valve 2 comprises, as
shown in FIG. 2, an actuator 3 to be electronically operated by the
ECU, a valve housing 4 which also forms a part of an interfluent
portion of the water cooling circuit, a valve body 5 (also referred
to as a first spool valve) for controlling a flow amount of the
engine cooling water flowing through a radiator 9, and a valve body
6 (also referred to as a second spool valve) for controlling a flow
amount of the engine cooling water flowing through a bypass circuit
11 (also referred to as a bypass passage).
[0032] The ECU comprises a microcomputer having a well known
structure and components, which are CPU for signal processing and
calculation, memory devices, such as ROM and RAM, for storing
programs and data, an input circuit, an output circuit, a power
supply circuit, and so on. Sensor signals from various sensors are
inputted into the microcomputer after those signals are processed
by A/D converters. Connected to the microcomputer are a crank angle
sensor, an acceleration sensor, an intake air flow sensor (an
airflow meter, etc.), an intake air temperature sensor, an intake
air pressure sensor, a throttle opening sensor, a cooling water
temperature sensor on an engine side, a cooling water temperature
sensor on a radiator side, a cooling water temperature sensor on a
bypass circuit side, a cooling water temperature sensor on a water
pump side, and so on. A starter motor drive circuit is connected to
the ECU, for controlling a driving current to a starter motor for
starting up an engine operation.
[0033] When an ignition key is inserted into a key cylinder of a
vehicle and turned to a position of "ST", a starter switch (not
shown) is turned on (ST:ON) and a starter relay (not shown)
provided in the starter motor drive circuit is turned on. The
engine 1 is cranked up to start its operation. When the ignition
key is turned back to a position of "IG" and thereby an ignition
switch (not shown) is turned on (IG:ON) after the engine 1 has
started its operation, the ECU starts its electronic controls to
various actuators, such as the flow control valve 2, in accordance
with the control programs stored in the memory device. The ECU
stops its electronic control when the ignition switch is turned off
(IG:OFF).
[0034] The engine cooling system comprises the cooling water
circuit in which the engine cooling water is circulated to cool the
engine 1. The cooling water circuit comprises a radiator cooling
circuit in which the cooling water is circulated from and back to a
water pump 8 through the engine 1, the radiator 9 and the flow
control valve 2. The cooling water circuit further has the bypass
circuit in which the cooling water is circulated from and back to
the water pump 8 through the engine 1, the bypass passage 11 and
the flow control valve 2. As the engine cooling water, an
antifreeze liquid having ethylene glycol as a main component, or a
long life coolant containing the antifreeze liquid, antirust and
the like, is used.
[0035] The water pump 8 is arranged adjacent to an output shaft
(e.g. a crankshaft) of the engine 1 and integrally provided to an
inlet port of the engine 1. The water pump 8 is one of engine
accessories driven to rotate by the engine 1 via a transmitting
device, such as a belt, and to circulate the cooling water. The
water pump 8 can be formed by a pump driven by an electric motor.
The engine 1 is mounted in an engine room of the vehicle, and it is
the water-cooled engine having a water jacket 12 formed in a
cylinder head and a cylinder block of the engine 1, so that the
cooling water flows through the engine 1 (through the water
jacket). The every portion of the engine 1 is thereby cooled to
effectively operate the engine 1.
[0036] The radiator 9 is arranged in the engine room and at such a
position at which the radiator 9 effectively receives wind during
the vehicle running. The radiator 9 comprises an upper tank, a
lower tank and a core portion between the upper and lower tanks,
wherein the core portion has multiple tubes through which the
cooling water flows. In the radiator 9, a heat exchange is
performed between the cooling water flowing through the tubes and
cooling air passing through between outer surfaces of the multiple
tubes, wherein the cooling air is the wind flowing through the
radiator during the vehicle running and the wind blown by a cooling
fan (not shown). The radiator 9 is, therefore, a heat exchanger for
cooling down the cooling water, the water temperature of which is
increased as a result of absorbing waste heat of the engine 1
during the cooling water passes through the water jacket 12 of the
engine 1.
[0037] The radiator cooling circuit comprises passage portions 13
to 16, and the passage portions are liquid-tightly connected to the
radiator 9. A downstream side of the passage portion 15 is
liquid-tightly connected to an upstream side of the flow control
valve 2. The bypass passage 11 is provided, so that the cooling
water flowing out of the engine 1 bypasses the radiator 9, wherein
the bypass passage 11 branches off from a connecting portion of the
passage portions 13 and 14 and is liquid-tightly connected to the
upstream side of the flow control valve 2.
[0038] A structure of the flow control valve 2 according to the
embodiment is explained with reference to FIGS. 2 to 4C. FIG. 2
shows a valve position of the flow control valve at a start of the
operation, whereas FIGS. 3A and 3B respectively show the valve
positions during the normal operation and at the high-load
operation. The flow control valve 2 precisely controls a radiator
flow amount of the cooling water flowing in the radiator cooling
circuit (13, 14, 9, 15, 2 and 16) as well as a bypass flow amount
of the cooling water flowing in the bypass circuit 11, depending on
the various operational conditions of the engine. The flow control
valve 2 can control the cooling water temperature more precisely
than the control valve operated by the thermostat, and thereby the
lower fuel consumption ratio is achieved.
[0039] The actuator 3 is a driving force generating portion for
generating a driving force depending on the engine operation, and
comprises a stepping motor for moving the first and second spool
valves 5 and 6 in their respective axial directions (in a valve
opening or closing direction). A rotor shaft 21 of the actuator 3
is rotationally supported by the valve housing 4. One end of the
rotor shaft 21 protrudes into the inside of the valve housing 4,
and an oil seal (a shaft seal) is provided between the rotor shaft
21 and the valve housing 4. A male screw portion 23 is formed on an
outer periphery of the rotor shaft 21, which is engaged with a
female screw portion 57 (FIG. 4C) formed on an inner periphery of
the first spool valve 5 movable in its axial direction (in a
vertical direction in FIG. 2). A cut-out portion 24 vertically
extending (in the axial direction) is formed at the male screw
portion 23, as shown in FIG. 4C. Instead of the stepping motor, a
brushless motor, a DC motor with brushes, an alternating current
motor of a three-phase induction motor can be used for the actuator
3. Further, a solenoid actuator for linearly driving the shaft can
be used as the driving force generating portion.
[0040] The valve housing 4 is made by an aluminum die-casting
process, and is arranged at the interfluent portion at which the
passage portions 15 and 16 of the radiator cooling circuit and the
bypass passage 11 are jointly connected. A cooling water passage is
formed in the valve housing 4. The valve housing 4 has a first
cylindrical wall portion 40a for movingly (reciprocally) supporting
the first spool valve 5, a circular pipe joint portion 40b
horizontally extending in the leftward direction in FIG. 2 (FIGS.
3A and 3B) from an outer surface of the first cylindrical wall
portion 40a, a second cylindrical wall portion 40c horizontally
extending in the rightward direction in FIG. 2 (FIGS. 3A and 3B)
from the outer surface of the first cylindrical wall portion 40a
and movingly (reciprocally) supporting the second spool valve 6,
and a circular pipe joint portion 40d vertically extending in the
upward direction in FIG. 2 (FIGS. 3A and 3B) from an outer surface
of the second cylindrical wall portion 40c. The circular pipe joint
portions 40b and 40d are respectively connected to the passage
portion 16 and the bypass passage 11.
[0041] The valve housing 4 further has a circular pipe joint
portion 40e at a lower end of the first cylindrical wall portion
40a, and a cylindrical valve case 25 is fixed to the circular pipe
joint portion 40e by screws or any other fixing means. An O-ring is
provided between the pipe joint portion 40e and the valve case 25
to prevent leakage of the cooling water. The pipe joint portion 40e
is connected to the radiator 9 through the passage portion 15. A
mixing chamber 27 is formed in the inside of the first cylindrical
wall portion 40a, at which the low temperature cooling water cooled
down at the radiator 9 and the high temperature cooling water
having bypassed the radiator 9 flow into and are mixed
together.
[0042] A space 31 defined by an upper end surface of the first wall
portion 40a of the valve housing 4 and an upper end surface of the
first spool valve 5 is a first volume variable space, the inner
volume of which is varied in accordance with the movement of the
first spool valve 5 in its axial direction. A space 32 defined by a
right-hand end surface of the second cylindrical wall portion 40c
and a right-hand end surface of the second spool valve 6 is a
second volume variable space, the inner volume of which is varied
in accordance with the movement of the second spool valve 6 in its
axial direction. An inner diameter of the pipe joint portion 40e is
made larger than an inner diameter of the first cylindrical wall
portion 40a. A radiator side passage 34 (a first inlet port) is
formed in the inside of the pipe joint portion 40e, so that the
cooling water from the radiator 9 flows into the mixing chamber
27.
[0043] A bypass side passage 35 (a second inlet port) is formed in
the inside of the pipe joint portion 40d, so that the cooling water
from the bypass circuit 11 flows into the mixing chamber 27. A pump
side passage 37 (an outlet port) is formed in the inside of the
pipe joint portion 40b, so that the cooling water flows out from
the mixing chamber 27 to the water pump 8 through the water pump
passage portion 16. The first wall portion (the mixing chamber 27)
of the valve housing 4 is respectively connected to the three ports
(34, 35 and 37) in a form of a T-shape in the vertical cross
section of the valve housing.
[0044] The first cylindrical wall portion 40a of the valve housing
4 has a first cylindrical partitioning portion 40f for operatively
separating the mixing chamber 27 from the radiator side passage 34.
A cylindrical inner surface of the first partitioning portion 50a
forms a first sliding surface (a first valve seat), on which a
first seal portion (5a) of the first spool valve 5 reciprocally
moves in a sliding manner.
[0045] The second cylindrical wall portion 40c of the valve housing
4 likewise has a second cylindrical partitioning portion 40g for
operatively separating the mixing chamber 27 from the bypass side
passage 35. A cylindrical inner surface of the second partitioning
portion 40g forms a second sliding surface (a second valve seat),
on which a second seal portion (6a) of the second spool valve 6
reciprocally moves in a sliding manner.
[0046] Multiple first guide portions 4a are integrally formed in
the valve housing 4 at a lower end side of the first cylindrical
partitioning portion 40f, for guiding the first seal portion (5a)
when the first spool valve 5 is downwardly moved. Multiple second
guide portions 4b are likewise integrally formed in the valve
housing 4 at a left-hand side of the second cylindrical
partitioning portion 40g, for guiding a protruded small-diameter
portion 60a of the second seal portion (6a) when the second spool
valve 6 is moved in a left-and right-ward direction.
[0047] An inside space 41 formed at a lower side of the first
cylindrical wall portion 40a forms a first valve passage 41, which
is surrounded by the first guide portions 4a, the outer surface of
the first spool valve 5 and the inner surface of the circular pipe
joint portion 40e. The first valve passage 41 is communicated with
the mixing chamber 27; the radiator side passage 34 is communicated
with the mixing chamber 27 through the first valve passage 41 when
the first spool valve 5 is downwardly moved and opened, as shown in
FIG. 3B.
[0048] As in the similar manner to the above first valve passage
41, an inside space 42 formed at a left-hand side of the second
cylindrical wall portion 40c forms a second valve passage 42, which
is surrounded by multiple second guide portions 4b, the outer
surface of the second spool valve 6 and the inner surface of the
second wall portion 40c. The second valve passage 42 is
communicated with the mixing chamber 27; the bypass side passage 35
is communicated with the mixing chamber 27 through the second valve
passage 42 when the second spool valve 6 is moved in the rightward
direction and opened, as shown in FIG. 3A.
[0049] The first spool valve 5 is urged by a return spring 44 in a
valve opening direction (a downward direction in FIG. 2), to
prevent overheat of the engine at a system failure. The first spool
valve 5 is prevented from rotating by a stopper pin 51 fixed to the
valve housing 4, so that the first spool valve 5 can be
reciprocally moved in the axial direction (in the upward and
downward direction) when the rotor shaft 21 is rotated by the
actuator 3. When the first spool valve 5 is upwardly or downwardly
moved upon receiving the driving force from the rotor shaft 21, an
opening degree of the first valve passage 41 is varied to control
the radiator flow amount. As above, the first spool valve 5
functions as a control valve for the radiator flow amount.
[0050] The first spool valve 5 comprises a pair of rand portions 5a
and 5b (each of which has a disc portion, an outer periphery and a
sealing portion), a cylindrical portion 5c connecting the rand
portions 5a and 5b with each other, and a side wall portion 5d
which is formed into an arc-shape and between the outer peripheries
of the two rand portions 5a and 5b. The side wall portion 5d is
formed so that it faces to the second spool valve 6. A pair of ring
seal grooves is formed at the outer peripheries of the rand
portions 5a and 5b, into which ring seals 47a and 47b are inserted.
The ring seal 47b is liquid-tightly in contact with the inner
surface of the first cylindrical wall portion 40a, for separating
the first volume variable space 31 from the mixing chamber 27.
[0051] The other ring seal 47a is likewise liquid-tightly in
contact with the inner surface of the first partitioning portion
40f, for operatively separating the radiator side passage 34 (the
first valve passage 41) from the mixing chamber 27. Accordingly, a
desired radiator flow amount, as shown in FIG. 1B, with respect to
the rotational angle of the actuator 3 can be obtained, when the
dimension of the pair of the rand portions 5a and 5b as well as the
first sliding surface (the longitudinal dimension thereof) are
suitably selected.
[0052] The cylindrical portion 5c of the first spool valve 5 has
the female screw portion 57 which is formed at its inner periphery
and engaged with the male screw portion 23 of the rotor shaft 21. A
space 5e is formed between the two rand portions 5a and 5b at the
outer periphery of the cylindrical portion 5c, wherein the space 5e
forms wholly or partly the mixing chamber 27. As above, the first
spool valve 5 is moved upwardly or downwardly in response to the
rotation of the rotor shaft 21, wherein the male screw portion 23
and the female screw portion 57 form a driving direction changing
device. A thick wall portion is provided at the side wall portion
5d of the first spool valve 5, wherein an insertion hole is formed
so that one end of the stopper pin 51 is inserted. A profile 52 is
formed at an outer surface of the thick wall portion (5d), so that
the second spool valve 6 is moved in conjunction with the first
spool valve 5. The profile 52 comprises a concave and a convex
portion, which are so formed to obtain the desired bypass flow
amount, as shown in FIG. 1B, with respect to the rotational angle
of the actuator 3.
[0053] The profile 52 is formed as a cam face for driving the
second spool valve 6 in its axial direction (i.e. in a direction
perpendicular to an axial direction of the first spool valve 5).
The cam face (52) comprises a first and a second flat surface
portions 52a and 52d (concave portions) extending in parallel to
the axial direction of the first spool valve 5, a first and a
second inclined surface portions 52b and 52c protruding outwardly
from the first and second flat surface portions 52a and 52d and
each having an inclined angle with respect to the axial direction
of the first spool valve 5. The first and second inclined surface
portions 52b and 52c form a convex portion, and the inclined angle
of the first inclined surface portion 52b (with which a ball 55 of
the second spool valve 6 is in contact, when the first spool valve
5 is positioned at its starting position, as shown in FIG. 2) is
made larger than that of the inclined surface portion 52c (with
which the ball 55 is brought into contact, when the first spool
valve 5 is moved downwardly to its normal operation or high load
operation position, as shown in FIGS. 3A and 3B).
[0054] A first pressure adjusting passage 61 is formed between the
inner surface (the female screw portion 57) of the cylindrical
portion 5c of the first spool valve 5 and the cut-out portion 24 of
the rotor shaft 21, as shown in FIG. 4C, for communicating with
each other the spaces formed at outer sides of the pair of the rand
portions 5a and 5b. More specifically, the first pressure adjusting
passage 61 communicates the first volume variable space 31 with the
radiator side passage 34 (i.e. the first valve passage 41) for
equalizing the fluid pressures in the both spaces.
[0055] The second spool valve 6 is biased by a set spring 45 toward
the first spool valve 5, so that the second spool valve 6 is
brought into contact with the profile 52 of the first spool valve 5
via the ball 55. The second spool valve 6 is moved in its axial
direction (in a direction perpendicular to the axial direction of
the first spool valve) in accordance with the movement of the first
spool valve 5. When the first spool valve 5 is downwardly moved,
from the position of FIG. 2 to the position of FIG. 3A, the second
spool valve 6 is moved in its right-hand direction to change the
opening degree of the second valve passage 42, so that the bypass
flow amount is controlled. The second spool valve 6 operates as a
bypass flow control valve, as above.
[0056] The second spool valve 6 comprises a pair of rand portions
(i.e. the second seal portions) 6a and 6b which are supported by
the second sliding surface in the sliding manner, and a cylindrical
portion 6c connecting the rand portions 6a and 6b with each other.
The rand portion 6b of the second spool valve 6 liquid-tightly
separates the second volume variable space 32 from the bypass side
passage 35. The second volume variable space 32 is liquid-tightly
closed by a plug member 58.
[0057] The other rand portion 6a of the second spool valve 6
operatively and liquid-tightly separates the bypass side passage 35
from the second valve passage 42 (and thereby the mixing chamber
27). The protruded small-diameter portion 60a is formed at the
other rand portion 6a, protruding outwardly (in a leftward
direction) from the rand portion 6a and in the axial direction of
the second spool valve 6. A recess portion 64 is formed at a
forward end of the protruded small-diameter portion 60a, for
holding the ball 55.
[0058] Accordingly, a desired bypass flow amount, as shown in FIG.
1B, with respect to the rotational angle of the actuator 3 can be
obtained, when the dimensions of the pair of the rand portions 6a
and 6b, the second sliding surface (the longitudinal dimension
thereof), and the profile 52 are suitably selected.
[0059] A space 6e is formed between the two rand portions 6a and 6b
and at the outer periphery of the cylindrical portion 6c, wherein
the space 6e forms wholly or partly the bypass side passage 35. A
second pressure adjusting passage 62 is formed in the cylindrical
portion 6c, as shown in FIGS. 2 and 4A, for communicating with each
other the spaces formed at outer sides of the pair of the rand
portions 6a and 6b. More specifically, the second pressure
adjusting passage 62 communicates the second volume variable space
32 with the mixing chamber 27 through the second valve passage 42
for equalizing the fluid pressures in the both spaces. According to
the present embodiment, the protruded small-diameter portion 60a is
formed at the rand portion 6a and the recess portion 64 is formed
at its forward end, and therefore the second pressure adjusting
passage 62 is formed into an L-shaped passage, as shown in FIG.
2.
[0060] An operation of the above engine cooling system is explained
with reference to FIGS. 1 to 4.
[0061] The actuator 3 of the flow control valve 2 is controlled by
the ECU to change the opening degrees of the first and second spool
valves 5 and 6 depending on the operational condition of the water
cooled engine 1, as shown in FIG. 1B. The first spool valve 5 is
moved in its axial direction (in the valve opening or closing
direction) upon directly receiving the driving force from the rotor
shaft 21, wherein the rotational movement of the rotor shaft 21 is
converted into the linear movement by the screw portion 23, so that
the opening degree of the first valve passage 41 is increased or
decreased. As a result, the radiator flow amount of the engine
cooling water flowing in the radiator cooling circuit can be
controlled in accordance with the engine operational condition.
[0062] The second spool valve 6 is moved in its axial direction (in
the valve opening or closing direction) upon indirectly receiving
the driving force from the rotor shaft 21 through the first spool
valve 5 and the ball 55 being in contact with the profile 52 formed
in the first spool valve 5, so that the opening degree of the
second valve passage 42 is likewise increased or decreased. As a
result, the bypass flow amount of the engine cooling water flowing
in the bypass circuit can be controlled in accordance with the
engine operational condition. As above, the radiator flow amount as
well as the bypass flow amount can be precisely controlled in
accordance with the engine operational condition, so that the
temperature of the engine cooling water flowing through the water
jacket 12 can be controlled at such a temperature which is most
suitable for the respective engine operation conditions.
[0063] The first and second spool valves 5 and 6 are controlled in
the following manner, in accordance with the engine operational
conditions. At a starting period of the engine 1, the actuator 3 is
operated to move the first and second spool valves 5 and 6 to the
positions shown in FIG. 2. In this position, the rand portion 5b of
the first spool valve 5 is in the sliding contact with the inner
surface of the valve housing 4, whereas the other rand portion 5a
is in the sliding contact with first sliding surface (i.e. the
first valve seat 40f). Accordingly, the first valve passage 41 is
separated from the mixing chamber 27 and the pump side passage
37.
[0064] As in the same manner to the first spool valve 5, the rand
portion 6b of the second spool valve 6 is in the sliding contact
with the inner surface of the valve housing 4 (the second sliding
surface at the right-hand side), whereas the other rand portion 6a
is in the sliding contact with the second sliding surface (the
second valve seat 40g). Accordingly, the bypass side passage 35 is
separated from the second valve passage 42 and the mixing chamber
27.
[0065] As above, the first and second spool valves 5 and 6 are
closed during the period for the engine starting operation, as
shown in FIG. 1B, so that the radiator flow amount of the engine
cooling water circulating in the radiator cooling circuit as well
as the bypass flow amount of the engine cooling water circulating
in the bypass circuit are both zero.
[0066] When the engine is operated in its normal operation but the
temperature of the engine cooling water detected by the temperature
sensor on the engine side is below a predetermined value, for
example 60 to 78.degree. C., the first spool valve 5 is downwardly
moved from its starting position of FIG. 2, to a position shown in
FIG. 3A. In this valve position, the rand portion 5a of the first
spool valve 5 is still in the sliding contact with the first valve
seat 40f, so that the separation between the first valve passage 41
and the mixing chamber 27 (and the pump side passage 37) is
maintained.
[0067] On the other hand, the ball 55 of the second spool valve 6
is lifted up (moved in the right-hand direction) by the convex
portion of the profile 52 formed in the thick wall portion of the
first spool valve 5, as shown in FIG. 3A, and thereby the rand
portion 6a of the second spool valve 6 is separated from the second
sliding surface (the second valve seat 40g). The bypass side
passage 35 is communicated from the second valve passage 42 and the
mixing chamber 27.
[0068] As a result, since the first spool valve 5 is kept closed
whereas the second spool valve 6 is opened, the radiator flow
amount of the engine cooling water circulating in the radiator
cooling circuit is still zero, whereas the bypass flow amount of
the engine cooling water circulating in the bypass circuit is
controlled to become such an amount corresponding to the opening
degree of the second spool valve 6 (i.e. the amount of the movement
of the second spool valve 6).
[0069] When the second spool valve 6 is opened as above, the engine
cooling water pumped out from the water pump 8 circulates through
the water jacket 12 of the engine 1, the passage portion 13, the
bypass passage 11, the bypass side passage 35 of the flow control
valve 2, the second valve passage 42, the mixing chamber 27, the
pump side passage 37 and the passage portion 16. During this
operation, the temperature of the engine cooling water is gradually
increased, due to the engine cooling water flowing through the
water jacket 12 of the engine 1, to reach the predetermined
value.
[0070] When the temperature of the engine cooling water detected by
the temperature sensor on the engine side becomes higher than the
predetermined value, for example 60 to 78.degree. C., during the
normal operation of the engine, the first spool valve 5 is further
downwardly moved from its first normal position of FIG. 3A, toward
a position shown in FIG. 3B. In this valve position (before
reaching the position of FIG. 3B), the rand portion 5a of the first
spool valve 5 is separated from the first valve seat 40f, so that
the first valve passage 41 is brought into communication with the
mixing chamber 27 and the pump side passage 37.
[0071] The contact between the ball 55 and the profile 52 of the
first spool valve 5 is changed from the contact with the first
inclined surface 52b to the contact with the second inclined
surface 52c, and the second spool valve 6 is gradually moved in the
leftward direction (in the valve closing direction) by the biasing
force of the set spring 45 in proportion to the downward movement
of the first spool valve 5.
[0072] As above, the first spool valve 5 starts its opening
operation whereas the second spool valve 6 is moved to its closing
position, when the temperature of the engine cooling water detected
by the temperature sensor on the engine side becomes higher than
the predetermined value, for example 60 to 78.degree. C., during
the normal operation of the engine. Accordingly, as shown in FIG.
1B, the radiator flow amount of the engine cooling water
circulating in the radiator cooling circuit is controlled to be
such an amount corresponding to a stroke of the downward movement
(i.e. the opening degree) of the first spool valve 5, whereas the
bypass flow amount of the engine cooling water circulating in the
bypass circuit is controlled to be such an amount corresponding to
a stroke of the leftward movement (i.e. the opening degree) of the
second spool valve 6.
[0073] When the first spool valve 5 is opened as above, the engine
cooling water pumped out from the water pump 8 circulates through
the water jacket 12 of the engine 1, the passage portion 13, the
radiator passage portion 14, the radiator 9, the radiator passage
portion 15, the radiator side passage 34 of the flow control valve
2, the first valve passage 41, the mixing chamber 27, the pump side
passage 37 and the passage portion 16. On the other hand, since the
second spool valve 6 is still in its opened state, the engine
cooling water pumped out from the water pump 8 circulates through
the water jacket 12 of the engine 1, the passage portion 13, the
bypass passage 11, the bypass side passage 35 of the flow control
valve 2, the second valve passage 42, the mixing chamber 27, the
pump side passage 37 and the passage portion 16. Due to the above
operation, the temperature of the engine cooling water flowing
through the water jacket 12 of the engine 1 is maintained at the
predetermined value.
[0074] When the engine 1 is operated with high load, the first
spool valve 5 is further downwardly moved from its second normal
position, to the position shown in FIG. 3B. In this valve position
(FIG. 3B), the rand portion 5a of the first spool valve 5 is
further separated from the first valve seat 40f, so that the
opening degree of the first valve passage 41 is made larger than
that during the normal operation, whereas the ball 55 is brought
into contact with the flat surface portion 52d of the profile 52 of
the first spool valve 5 and the rand portion 6a of the second spool
valve 6 is thereby brought into the sliding contact with the second
sliding surface (40g) to close the second valve passage 42. The
bypass side passage 35 is thereby separated from the second valve
passage 42 and the mixing chamber 27. As a result, since the first
spool valve 5 is kept opened whereas the second spool valve 6 is
closed, as shown in FIG. 1B, the radiator flow amount of the engine
cooling water circulating in the radiator cooling circuit is
continuously controlled to be the amount corresponding to the
stroke of the downward movement (i.e. the opening degree) of the
first spool valve 5, whereas the bypass flow amount of the engine
cooling water circulating in the bypass circuit becomes zero.
[0075] Since the first spool valve 5 is kept opened as above, the
engine cooling water pumped out from the water pump 8 circulates
through the water jacket 12 of the engine 1, the passage portion
13, the radiator passage portion 14, the radiator 9, the radiator
passage portion 15, the radiator side passage 34 of the flow
control valve 2, the first valve passage 41, the mixing chamber 27,
the pump side passage 37 and the passage portion 16. In this
operation, since a larger amount of the engine cooling water
flowing through the water jacket 12 of the engine 1 is cooled down
at the radiator, the temperature of the engine cooling water can be
maintained at the predetermined value. As indicated in FIG. 1B, it
is not always necessary to completely close the second valve
passage 42. Instead, the opening degree of the second valve passage
42 can be reduced to a smaller amount than that during the normal
operation.
[0076] According to the first embodiment, as described above, since
the first volume variable space 31 is communicated with the space
formed at the opposite side of the first spool valve 5 (i.e. the
first valve passage 41 and the radiator side passage 34) through
the first pressure adjusting passage 61, the fluid pressures at
both of the longitudinal sides of the first spool valve 5 is
equalized (P1=P2). As a result, the pressure load for the movement
of the first spool valve 5 in its axial direction (in the
upward-downward direction in FIG. 2) can be cancelled.
[0077] As in the same manner to the first spool valve 5, since the
second volume variable space 32 is communicated with the space
formed at the opposite side of the second spool valve 6 (i.e. the
second valve passage 42 and the mixing chamber 27) through the
second pressure adjusting passage 62, the fluid pressures at both
of the longitudinal sides of the second spool valve 6 is equalized
(P3=P4). As a result, the pressure load for the movement of the
second spool valve 6 in its axial direction (in the
leftward-rightward direction in FIG. 2) can be cancelled.
[0078] As above, the driving load for the actuator 3 of the flow
control valve 2 can be minimized, independently of the valve
opening or valve closing positions of the first and second spool
valves 5 and 6, and further independently of fluid pressure in the
radiator cooling circuit (more specifically, the fluid pressure in
the radiator side passage 34) or the fluid pressure in the bypass
circuit (more specifically, the fluid pressure in the bypass side
passage 35). The flow control valve 2 can be therefore made in a
smaller size, and made in a lower cost since a reduction device for
reducing a rotational speed of the actuator by a predetermined
reduction ratio can be eliminated. Since the flow amount
characteristics shown in FIG. 1B can be freely changed by changing
the shape of the profile 52, the main components of the flow
control valve 2 can be commonly used for various types of the flow
control valves, independently of different requirements for the
different cooling systems or different vehicle models. And
therefore, the development cost can be also reduced.
Second Embodiment
[0079] A second embodiment will be explained with reference to
FIGS. 5A to 5D, wherein the second embodiment differs from the
first embodiment in that the first pressure adjusting passage 61 is
modified, instead of providing the cut-out portion 24 at the rotor
shaft 21.
[0080] FIG. 5A shows a cross sectional view of the cylindrical
portion 5c of the first spool valve 5. A part of the cylindrical
portion 5c is extended in a radial direction to form the first
pressure adjusting passage 61.
[0081] FIG. 5B also shows a cross sectional view of the cylindrical
portion 5c of the first spool valve 5. Three parts of the
cylindrical portion 5c are extended in radial directions to form
multiple pressure adjusting passages 61.
[0082] FIG. 5C shows a vertical cross sectional view of the flow
control valve 2, wherein the first pressure adjusting passage 61 is
formed in the side wall portion 5d of the first spool valve 5.
[0083] FIG. 5D also shows a vertical cross sectional view of the
flow control valve 2, wherein a connecting pipe portion 69 is
provided between the rand portions 5a and 5b and the first pressure
adjusting passage 61 is formed in the connecting pipe portion
69.
[0084] In the above modifications, the first pressure adjusting
passage 61 is formed in the first spool valve 5. However, although
not shown in the drawings, the first pressure adjusting passage can
be formed in the valve housing 4.
[0085] According to the above second embodiment, the cross
sectional area of the first pressure adjusting passage 61 can be
freely designed, more specifically the cross sectional area can be
made larger than that of the first embodiment, so that the pressure
equalization between the first volume variable space 31 and the
first valve passage 41 (i.e. radiator side passage 34) can be more
smoothly performed.
Third Embodiment
[0086] A third embodiment will be explained with reference to FIG.
6.
[0087] The forward end 70 of the protruded small-diameter portion
of the second spool valve 6 is formed into a semispherical shape,
so that the ball 55 of the first embodiment can be eliminated.
According to the third embodiment, the number of parts as well as
number of assembling processes for the flow control valve can be
reduced to realize a cost down.
Fourth Embodiment
[0088] A fourth embodiment will be explained with reference to FIG.
7.
[0089] A blade portion 71 is formed at the rand portion 5a of the
first spool valve 5, for rectifying the fluid flow in the radiator
side passage 34 and the first valve passage 41 to reduce fluid
resistance for the engine cooling water flowing from the radiator 9
into the flow control valve 2. As a result, the flow amount can be
increased at the full open state of the first spool valve 5, to
maximally bring out the cooling effect of the radiator 9.
Fifth Embodiment
[0090] A fifth embodiment will be explained with reference to FIGS.
8A to 9B, wherein FIG. 8A is a vertical cross sectional view of the
flow control valve, FIG. 8B is a cross sectional view of a modified
flow control valve, FIG. 9A is a schematic view showing an engine
cooling system, and FIG. 9B is a graph showing characteristics of a
radiator flow amount, a bypass flow amount and a heater flow amount
with respect to a rotational angle of an actuator. The same
reference numerals to the first embodiment are those parts which
are identical or similar to the first embodiment.
[0091] The engine cooling system shown in FIG. 9A comprises three
different flow circuits; a radiator cooling circuit in which the
engine cooling water flows from the water pump 8 through the engine
1, the radiator 9, the flow control valve 2 and back to the water
pump 8; a bypass circuit in which the engine cooling water flows
from the water pump 8 through the engine 1, the bypass passage 11,
the flow control valve 2 and back to the water pump 8; and a heater
circuit in which the engine cooling water (hot water) flows from
the water pump 8 through the engine 1, a hot water type heater 10
for an air conditioning system, the flow control valve 2 and back
to the water pump 8.
[0092] The hot water type heater 10 is provided in an air duct of a
vehicle air conditioning device for air-conditioning a passenger
room of a vehicle. The heater 10 comprises a heater core having a
pair of tanks and multiple tubes connected between the tanks, so
that the engine cooling water (the hot water) flows from one of the
tanks to the other tank through the tubes. When air passes by the
heater 10, heat is exchanged between the hot water flowing through
the tubes and the air flowing around outer surfaces of the tubes,
so that the air cooled down by an evaporator (not shown) is
re-heated by the heater 10. At the same time, the engine cooling
water (hot water) heated by the waste heat of the engine 1 can be
cooled down by the heater 10. The heater 10 is connected to the
engine 1 through a heater passage 17 and to the flow control valve
through another heater passage 18, which is liquid-tightly
connected to the flow control valve 2.
[0093] The flow control valve 2 comprises a third spool valve 7, in
addition to the first and second spool valves 5 and 6 which are
basically identical to those shown in FIG. 2. The third spool valve
7 is also similar in its structure to the second spool valve 6 and
is biased by a set spring 46 toward the first spool valve 5, so
that the third spool valve 7 is brought into contact with a profile
53 of the first spool valve 5 via a ball 56. The third spool valve
7 is moved in its axial direction (in a direction perpendicular to
the axial direction of the first spool valve) in accordance with
the movement of the first spool valve 5. When the first spool valve
5 is downwardly moved, the third spool valve 7 is moved in its
right-hand direction to change an opening degree of a third valve
passage 43, so that the heater flow amount is controlled. The third
spool valve 7 operates as a heater flow control valve, as above.
When the third spool valve 7 is opened, a heater side passage 36 is
communicated with the third valve passage 43, the mixing chamber 27
and the pump side passage 37.
[0094] The third spool valve 7 comprises a pair of rand portions
(i.e. third seal portions) 7a and 7b which are supported by a third
sliding surface in the sliding manner, and a cylindrical portion 7c
connecting the rand portions 7a and 7b with each other. The rand
portion 7b of the third spool valve 7 liquid-tightly separates a
third volume variable space 33 from the heater side passage 36. The
third volume variable space 33 is liquid-tightly closed by a plug
member 59. A guide portion 4c is integrally formed in the valve
housing 4, for guiding the third spool valve 7.
[0095] The other rand portion 7a of the third spool valve 7
operatively and liquid-tightly separates the heater side passage 36
from the third valve passage 43 (and thereby the mixing chamber
27). The protruded small-diameter portion 70a is formed at the
other rand portion 7a, protruding outwardly (in a leftward
direction) from the rand portion 7a and in the axial direction of
the third spool valve 7. A recess portion 65 is formed at a forward
end of the protruded small-diameter portion 70a, for holding the
ball 56.
[0096] Accordingly, a desired heater flow amount, as shown in FIG.
9B, with respect to the rotational angle of the actuator 3 can be
obtained, when the dimensions of the pair of the rand portions 7a
and 7b, the third sliding surface (the longitudinal dimension
thereof), and the profile 53 are suitably selected.
[0097] A space 7e is formed between the two rand portions 7a and 7b
and at the outer periphery of the cylindrical portion 7c, wherein
the space 7e forms wholly or partly the heater side passage 36. A
third pressure adjusting passage 63 is formed in the cylindrical
portion 7c, as shown in FIGS. 8A and 8B, for communicating with
each other the spaces formed at outer sides of the pair of the rand
portions 7a and 7b. More specifically, the third pressure adjusting
passage 63 communicates the third volume variable space 33 with the
mixing chamber 27 through the third valve passage 43 for equalizing
the fluid pressures in the both spaces. According to the present
embodiment, the protruded small-diameter portion 70a is formed at
the rand portion 7a and the recess portion 65 is formed at its
forward end, and therefore the third pressure adjusting passage 63
is formed into an L-shaped passage, as shown in FIG. 8A. The third
spool valve 7 is formed in the valve housing 4 in the same vertical
line to the second spool valve 6, as shown in FIG. 8A. However, it
can be formed in the same horizontal line to the second spool valve
6, as shown in FIG. 8B, wherein the third spool valve 7 is
displaced from the second spool valve 6 by a certain angle. As
above, in the case that a further spool valve is formed in the flow
control valve, the further spool valve can be formed in the similar
manner to the third spool valve 7.
[0098] According to the above fifth embodiment, the heater flow
amount can be controlled in addition to the radiator flow amount
and the bypass flow amount, without largely increasing the driving
load to the actuator 3. The flow control valve 2 can be therefore
made in a small size, compared with a case in which a heater valve
for controlling the heater flow amount is independently
provided.
[0099] Furthermore, since the heater flow amount can be controlled
independently from the control for the radiator flow or the bypass
flow, the heater passages 17 and 18 can be communicated by the flow
control valve 2 before the radiator cooling circuit and the bypass
circuit are opened, when the temperature of the heater 10 is to be
rapidly and preferentially increased, as shown in FIG. 9B, during a
period of a heater preferential operation. Accordingly, the waste
heat from the engine can be intensively supplied to the heater 10
for quickly warming the passenger room of the vehicle.
[0100] Furthermore, the multiple spool valves 6 and 7 can be
arranged in the valve housing 4 in any manner as desired, it
becomes possible to design the flow control valve realizing the
best arrangement to the cooling system.
* * * * *