JP2002257248A - Flow control valve and cooling device for internal combustion engine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increases in leakage of cooling water at a starting initial time of an internal combustion engine and leakage by changes due to aging and quicken temperature rising of the cooling water when starting the internal combustion engine. SOLUTION: This flow control valve 1 is provided with a valve housing 10 provided with first, second and third fluid passages 14a, 14b and 14c for introducing a coolant and a fourth fluid passage 12a for leading out the coolant, a rotatable valve element 20 for switching flow rate of coolant introduced from the fluid passages 14a, 14b and 14c and a driving device 30 for the valve element 20. A speed reducer 40 and a return spring 50 are interposed between the valve element 20 and the driving device 30. In a non-operating state of the driving device 30, the two fluid passages of the three fluid passages 14a, 14b and 14c for introduction are made to be communicated with the fluid passage 12a for leading out the coolant by the return spring 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control valve and a cooling device for an internal combustion engine using the same, and more particularly, to a flow rate of a cooling medium for adjusting a cooling water temperature of an internal combustion engine used in an automobile or the like. It relates to a structure according to the flow rate adjustment of the control flow control valve.

[0002]

As a cooling device for an automobile internal combustion engine, water-cooling unit is known to use the radiator. In this type of cooling device, a thermostat is used to control the temperature of the cooling water. When the cooling water as a cooling medium is lower than a predetermined temperature, the cooling water is bypassed by activating the thermostat. The cooling medium circulation circuit is configured to flow through the passage and return the cooling water to the internal combustion engine without passing through the radiator.

In this conventional cooling device, as a means for sensing the temperature of the cooling medium and adjusting the flow rate of the cooling medium, a thermostat comprising a flow control valve using a temperature-sensitive member such as paraffin which expands and contracts due to a temperature change is used. Since it is used, an inexpensive flow control device can be provided, but the temperature response and the reproducibility of the valve opening are low due to the characteristics of the temperature-sensitive member. Moreover,
Cooling water temperature thermostat appreciable, since limited to a thermostat vicinity of the passage through which cooling water passes, it is difficult to maintain the temperature accurately coolant constant.

[0004] In addition, since the thermostat biases the spring in the direction of closing the valve due to its structure, when the valve fails, the passage through which the cooling water passes through the radiator is closed regardless of the operation state of the internal combustion engine.

Furthermore the temperature of the cooling water from the relationship that is controlled to a set temperature of the thermostat is kept substantially at a constant temperature in winter and summer. Therefore, it is scolded or flame to optimally controlled in accordance with the operating state of the temperature of the cooling water outside air temperature and an internal combustion engine. For example, if the temperature of the cooling water is set higher to improve the heater performance and fuel efficiency in winter, the temperature of the cooling water tends to increase in summer when the outside air temperature is high, and the cooling effect of the internal combustion engine decreases. And the temperature of the lubricating oil rises.

[0006] In recent years, as a demand for an internal combustion engine,
Contradictory demands for high output and low fuel consumption are increasing, and a cooling device that satisfies such a demand for an internal combustion engine is also desired. That is, in order to achieve high output, it is necessary to lower the temperature of the cooling water cooled by the radiator, to increase the cooling efficiency of the internal combustion engine, and to maintain the temperature of each member of the internal combustion engine at or below the endurable temperature limit against a thermal load. . Further, in order to achieve low fuel consumption, it is necessary to increase the cooling water temperature to improve the combustion efficiency of the combustion chamber of the internal combustion engine. That is, the internal combustion engine, such as high-speed driving or sudden traveling uphill which is a high output running state, or the load low running a fuel-efficient driving,
For example, there is a demand for a cooling device that can control the temperature of the cooling water according to the state of the internal combustion engine such as idling during a traffic jam.

[0007] In view of the above circumstances, the present applicant,
A cooling device for an internal combustion engine using a flow control valve capable of controlling the temperature of a cooling water according to the operating state of the internal combustion engine has already been proposed. This cooling device controls the cooling water of the internal combustion engine so as to reduce the bypass passage area at the time of starting by using a flow control valve arranged with the axis of the inner peripheral wall of the valve housing and the axis of the valve element eccentrically arranged, Normally engine control unit (ECU)
The cooling water temperature is controlled in accordance with a predetermined operating state.

However, if this eccentric flow control valve is used, the valve cannot be completely closed due to eccentricity at the valve position where the radiator side passage is to be fully closed, and a leakage flow from the radiator side passage is generated. This leakage flow rate is of a degree that does not cause a problem after the internal combustion engine is completely warmed up, but causes a delay in temperature rise when it is desired to increase the cooling water temperature during the warming up. In order to prevent this leakage, stopping the eccentric valve and putting rubber packing in the radiator side passage is effective in preventing initial leakage, but increases leakage due to wear of the packing during operation. For this reason, it is difficult to prevent leakage in consideration of aging.

Further, the cooling device is provided with a heat exchanger (heater) used for heating a vehicle living space in the middle of a cooling water circuit.
In this case, the flow control valve is controlled to reduce the bypass passage area in order to accelerate the temperature rise of the cooling water at the time of starting the internal combustion engine, but the cooling water passage to the heat exchanger is always provided on the internal combustion engine side. and communicates, to further accelerate the temperature rise of the cooling water at the start there is a need to close the coolant circuit.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to prevent the leakage at the initial stage of the internal combustion engine and the increase in the leakage with the lapse of time, and to reduce the area of the bypass passage. An object of the present invention is to provide a flow control valve having a structure for closing a cooling water circuit to a heat exchanger (heater) at the same time as the reduction, and a cooling device for an internal combustion engine using the valve.

[0011]

SUMMARY OF THE INVENTION The present invention provides a flow control valve and a cooling device for an internal combustion engine according to the present invention as means for solving the above-mentioned problems.
Flow control valve according to claim 1, the first to introduce the cooling medium, and the second and third fluid passages, and a valve housing with a fourth fluid passage for deriving the cooling medium, these fluids The valve body includes a rotatable valve body for switching the flow rate of the cooling medium introduced from the passage, and a driving device for the valve body. A speed reduction device and a return spring are interposed between the valve body and the driving device. And two of the three introduction fluid passages are communicated with the fourth fluid passage by a return spring when the driving device is not operated. Therefore, when the drive device is not operated, the fluid passage is normally opened,
A so-called normally open flow control valve can be provided.
For example, if one of the two fluid passages that communicates with the fourth fluid passage when the drive device is not operated is a fluid passage that introduces a cooling medium cooled by heat radiation or the like, when the flow control valve fails, A circulation circuit for the cooling medium that returns the cooling medium cooled through the fourth fluid passage that is the outlet passage of the flow control valve to the heat load device, for example, the internal combustion engine, can be secured, and the heat load device can be maintained in a safe state. .

[0012] flow control valve according to claim 2 is obtained by defining a speed reducer interposed between the valve body and the driving device and the two-step planetary gears. As described above, the drive source is provided between the valve body to which the biasing force of the return spring is applied and the drive device, by providing the speed reducer for increasing the drive torque of the drive device, in order to resist the biasing force of the return spring. It is possible to make the flow control valve normally open without increasing the size of the driving device.

According to a third aspect of the present invention, there is provided a flow control valve, wherein two openings are formed on a disk-shaped seal plate having three independent openings communicating with the first to third fluid passages. The opening of the first to third fluid passages is made variable by rotating the disc-shaped valve of the valve body. That is, in the overlapping degree of the opening of the aperture and the valve seal plate, and the opening area of the fluid passage in the variable. Flow control valve according to claim 4, which was pressed against constantly valve sealing plate by a spring, thereby, leakage of the cooling medium from between the seal plate and the valve can be prevented. Also, even if the seal plate is worn due to an increase in the number of times of operation, the valve leakage does not increase because the pressing force of the spring acts.

According to a fifth aspect of the present invention, in the flow control valve, the valve housing includes an upper housing and a lower housing, and a peripheral portion of the seal plate is sandwiched between the two housings and fixed in a liquid-tight manner. This prevents leakage of the cooling medium from the section. In the flow control valve according to the sixth aspect, the material of the seal plate is specified to be a material having a low friction coefficient, and an increase in driving torque due to sliding with the valve can be suppressed.

According to a seventh aspect of the present invention, there is provided a cooling device for an internal combustion engine.
Since the above-mentioned flow control valve is provided in the cooling water circuit of the water-cooled internal combustion engine, the cooling water temperature can be controlled according to the operating state. In addition, when the flow control valve or the control system controlling the same fails, the radiator and the fluid passage returning the cooling water from the radiator to the internal combustion engine and the fluid passage returning the cooling water from the heat exchanger to the internal combustion engine are communicated. A cooling water circulation circuit that returns the cooling water cooled by the heat radiation by the heat exchanger to the internal combustion engine can be secured. Therefore, since the use of the flow control valve normally open, capable of maintaining the internal combustion engine in a safe state even in the case of failure. In the cooling device according to claim 8, when the fluid passage returning from the radiator to the internal combustion engine is fully closed to reduce the opening area of the fluid passage returning from the bypass passage to the internal combustion engine, the cooling device returns from the heat exchanger to the internal combustion engine at the same time. reducing the opening area of the fluid passage, it is those that can be controlled to close, thereby, it is possible to accelerate the Atsushi Nobori of the cooling water at the time of starting the internal combustion engine further.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A flow control valve according to the present invention and an embodiment in which a cooling device for an internal combustion engine using the same is applied to a cooling device for an internal combustion engine for a vehicle will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a flow control valve according to an embodiment of the present invention. As shown in FIG. 1, the flow control valve 1 is configured to include a valve housing 10, a valve body 20, a driving device 30, a reduction gear 40, a return spring 50, and the like.

The valve housing 10 includes an upper housing 12
And the lower housing 14. The upper housing 12 includes a valve body 20 rotatably supported, a fourth fluid passage 12a for leading a cooling medium, and the like.
The lower housing 14 includes first, second, and third fluid passages 14a, 14b, and 14c for introducing a cooling medium. As will be described later, these fluid passages include, for example, the first fluid passage 14a in the radiator 200, the second fluid passage 14b in the bypass passage 300, and the third fluid passage 1
4c is the fourth fluid passage 1 in the heat exchanger (heater) 900.
2a is connected to the internal combustion engine 100 as a heat load device. The lower housing 14 is provided with a mounting surface 14d for supporting a shaft 21 and a seal plate 26 of the valve body 20 described later.

The valve body 20 is composed of the shaft 21, the valve 22 and the spring 23 and the like. Valve 22
Has a disc-shaped, is the first, second fluid passage 14a, the opening 22a for the radiator 200 and the bypass passage 300 is 14b and the third fluid passage 14c as shown in FIG. 3 an opening 22b for the heat exchanger 900 is drilled, the hole 2 to interpolate transmural the shaft 21 at the center
2c is formed. The shaft 21 and the valve 22, but in the vertical direction is movable without constraints to each other and restrained to each other in the rotational direction. Therefore, shaft 21
And the valve 22 rotate integrally. Valve body 2
0, the spring 23 for preventing leakage valve for biasing the valve 22 always downward.

In order to form a valve structure together with the valve body 20, a sealing plate 26 is provided on the mounting surface 1 of the lower housing 14.
4d, and its peripheral portion is sandwiched between the upper housing 12 and the lower housing 14, and is sealed and fixed in a liquid-tight state. The seal plate 26 has a disk shape, and as shown in FIG.
a for the radiator 200 which is a
The opening 26b for the bypass passage 300, which is the fluid passage 14b, and the heat exchanger 90, which is the third fluid passage 14c,
An opening 26c for the valve body 20 is formed independently of each other, and a hole 26d through which the shaft 21 of the valve body 20 is inserted is formed at the center.

[0020] FIG. 4 shows a state of repeating the valve 22 in the state shown in seal plate 26 and 3 in the state shown in FIG. 2, in this state is a second fluid passage 14b and communicates with the internal combustion engine 100 with only the bypass passage 300 is narrowed. Other fluid passage 14
a and 14c are in a closed state. Depending on the rotation of the valve 22, so that the fluid passages 14a, 14b, the opening area of 14c changes. The valve 22 is a spring 2
3 prevents the cooling medium from leaking from between the valve 22 and the seal plate 26 because it is always pressed against the seal plate 26. Seal plate 26,
Because of sliding with the valve 22, it is constantly exposed to wear. In order to suppress an increase in the driving torque of the valve 22, a low coefficient of friction, for example, polytetrafluoroethylene (Teflon,
Trademark) system of the material is desirable.

As shown in FIG. 1, the drive unit 30 is connected to the valve body 2 via a speed reducer 40 disposed below the drive unit 30.
0 is rotatably driven, and includes a drive motor such as a stepping motor. Drive motor may be a rotary solenoid or a DC motor or the like in addition to the step motor. Hereinafter, a step motor applied to the embodiment of the present invention will be described. The driving device 30 has its shaft 3
1, a step motor 32 is provided, and has a connector 33 for supplying a current to the step motor 32 and inputting a drive signal for controlling rotation to a predetermined rotation angle.
The connector 33 has a fixed terminal 33 a that is electrically connected to the electromagnetic drive unit of the step motor 32. Step motor 32 is received various signals sent from the radiator side temperature sensor 421, detecting means such as a bypass passage side sensor 422 400 discussed in the cooling system of an internal combustion engine will be described later, it outputs a drive signal according to the operating conditions The control circuit controls the rotational position of the valve body 20 by inputting an electric signal via the terminal 33a.

The speed reducer 40 has a two-stage planetary gear as shown in FIG. 1, and includes a sun gear 41 integrally formed at the tip of a shaft 31 of the drive device 30 and a holding portion of the speed reducer 40. A ring gear 42, which is formed to form gear teeth on the inner peripheral surface, and a planet gear 4 which is engaged with the sun gear 41 and the ring gear 42 and is disposed between the two gears 41, 42.
3, is supported on the planet gear 43, and an output shaft 44 which engages the shaft 21 of the valve body 20. The reduction gear 40 is disposed between the drive device 30 and the valve body 20,
The drive torque generated by the drive device 30 is increased to
Since it is transmitted to 0, the valve body 20 to which a return spring 50 described later is urged can be freely rotated. further,
The adoption of the two-stage planetary gear structure (reduction structure by each of the gears 41, 42, 43) allows the reduction ratio to be set large, and also allows the reduction in size of the reduction gear 40, that is, the reduction in size of the flow control valve 1. It is.

[0023] The return spring 50, wound portion 50a
And both end portions 50b are disposed between the drive device 30 and the valve body 20 as shown in FIG. 1 and urged against the reduction gear 40 and the valve body 20 disposed immediately below the drive device 30. I have. One of the ends 50b is engaged with an output shaft 44 supported by the planet gear 43 of the reduction gear 40, and the other is engaged with the upper valve housing 12. For this reason, when the driving device 30 does not operate, the valve body 20 is rotated by the urging force of the return spring 50, and the first and third fluid passages 14a and 14c are connected to the fourth fluid passage 12a as described later. it can be communicated with.

Next, the operation of the flow control valve 1 of the present invention will be described. FIG. 5 is a schematic diagram illustrating the opening characteristics of the flow control valve of the present embodiment. The vertical axis represents the passage opening, and the horizontal axis represents the rotation angle of the valve 22 or the number of stepping motor drive pulse signals. The flow control valve 1 of the present invention includes, for example, a first fluid passage 14a that is a fluid passage on the radiator side, a second fluid passage 14b that is a fluid passage on the bypass passage side, and a fluid on the heat exchanger (heater) side. Third fluid passage 14 which is a passage
Each flow rate ratio of the cooling medium to further introduced c is variably controllable. The rotation of the valve body 20 is controlled by a drive device 30 including a motor 32 that is electrically operated.

When the drive unit is not operated, that is, when an electric signal is not input to the motor 32, the valve 22 which is the valve body 20 is moved by the return spring 50 which urges the reduction gear 40 and the valve body 20. The first fluid passage 14a and the third fluid passage 14c shown in FIG. 5 are returned to the rotational position communicating with the fourth fluid passage 12a.

A motor 32 is used for the operation of the driving device, and an electric signal for controlling the motor is a valve body 20.
A drive signal corresponding to the rotational position at which is rotated is output from, for example, a control device constituting a cooling device of the internal combustion engine using the flow control valve 1 described later. The drive device 30 controlled by this drive signal increases the drive torque by the speed reduction device 40 against the urging force of the return spring 50 urged by the valve body 20, and moves the valve body 20 to a predetermined rotational position. It is driven. Thus, the valve 22 is the valve body 20 is held rotated in the rotational position of a target.

By rotating the valve 22, which is the valve element 20, by the driving device 30, the first fluid passage 14a is reduced in its opening area from the fully opened state as shown in FIG. 14b is to increase the opening area from the fully closed state, and the third fluid passage 14c is
The rotation of the valve body 20 is controlled so as to maintain the fully open state.
The second fluid passage 14b is midway fully opened, the state is maintained.

As the rotation of the valve 22 advances, the first fluid passage 14a is fully closed, and the second and third fluid passages 14a are closed.
b and 14c are fully opened. This state is a dotted line in FIG. 5, the bypass-side fully open radiator side fully closed position, in shown. While further advances the rotation of the valve 22 in this state, the opening area of the third fluid passage 14c begins to reduce. After a short delay, the opening area of the second fluid passage 14b also starts to decrease. In this case, the first fluid passage 14a is maintained in a fully closed state.
When the rotation of the valve 22 further proceeds, the third fluid passage 14c
Are fully closed, the first fluid passage 14a is maintained in the fully closed state, and the opening area of the second fluid passage 14b is being reduced. This state is indicated by the dotted line, the bypass throttle, and the heater passage fully closed position in FIG. Thus, the flow rate of the cooling medium flowing through the first to third fluid passages 14a, 14b, 14c is changed by the rotation of the valve 22, which is the valve body 20.

Next, an embodiment in which the cooling device for an internal combustion engine using the flow control valve 1 of the present invention is applied to a cooling device for an internal combustion engine for a vehicle will be described with reference to FIG. FIG.
As shown in FIG. 1, a cooling device for a vehicle internal combustion engine includes a water-cooled internal combustion engine 100, a radiator 200, a bypass passage 300 that returns cooling water as a cooling medium to the internal combustion engine without passing through the radiator 200, Valve 1 and internal combustion engine 1
00, and a flow control valve 1 according to the operating state detected by the detecting means 400.
And a heat exchanger 900 used for heating a vehicle living space and the like.

The water-cooled internal combustion engine 100, more is the cylinder block 101 and cylinder head 102, these internal passages of the cooling water, provided with a so-called water jacket, the cylinder block 101 and cylinder head 102 around the combustion chamber 103 overheating to prevent the, it is cooled by circulating cooling water cooled by the radiator 200 and the heat exchanger 900 to be described later. The internal combustion engine 100
Is provided with a water pump 600 shown in FIG. 6 so as to circulate cooling water.

[0031] The radiator 200, radiator main body 20
1, a reservoir tank 202, and a cooling fan 203. The radiator main body 201 generally includes a plurality of tubes having cooling fins (not shown), an upper tank and a lower tank connecting the tubes, and sends cooling water to the cooling fins by sending air generated by running a cooling fan or a vehicle. Dissipate heat and cool. Incidentally, the reservoir tank 202 is for absorbing a change in the cooling water volume caused by temperature changes.

The bypass passage 300 is connected to the radiator 200
The cooling water is returned to the internal combustion engine 100 without passing through the internal combustion engine 100 and the radiator 20 as shown in FIG.
It is provided in the middle of a cooling water circuit circulating between zero. Further, as shown in FIG. 6, the cooling device for the internal combustion engine according to the present embodiment includes a heat exchanger (heater) 9 in the middle of the cooling water circuit.
00 is provided. If this heat exchanger 900 is used for heating a vehicle living space or the like, heating can be performed using cooling water that is heated by the generation of a heat load on the internal combustion engine 100, and fuel saving can be achieved. Further, as shown in FIG. 6, a throttle valve 800 disposed in the middle of the cooling water circuit, if the inner wall inside so that the cooling water is circulated, the throttle valve 8
00 icing can be prevented.

The internal combustion engine 10 from the flow and the heat exchanger 900 of the cooling water returning to the internal combustion engine 100 from the bypass passage 300
The flow of the cooling water returning to 0 merges with the flow of the cooling water returning from the radiator 300 to the internal combustion engine 100, and the flow control valve 1 of the present invention is disposed at this junction. Structure and operation of the flow control valve 1 is as described above.

The detecting means 400 is a detecting means for detecting the operating state of the internal combustion engine 100, and is a load detecting means 4 for detecting the output of the vehicular internal combustion engine, that is, the load state of the internal combustion engine.
10 and a cooling water detecting means 420 for detecting a combustion efficiency and a cooling effect attributable to an operation state from a cooling water temperature of the internal combustion engine. The load detecting means 410 includes a throttle position sensor 411, an intake / intake air amount sensor (not shown),
It is composed of an internal combustion engine or a vehicle speed sensor, an O ₂ sensor, a starter switch, and the like. For example, the presence or absence of acceleration of the vehicle by a throttle position sensor 411, or
High load, in a detection signal for detecting operating conditions such as whether the low load or is output. As shown in FIG. 6, the cooling water temperature detecting means 420 includes sensors 421 and 4 for detecting a radiator side cooling water temperature, a bypass passage side cooling water temperature, and a water pump cooling water temperature flowing into the water pump 600, respectively.
22, 423 are provided.

The control device (ECU) 500 is a read-only memory (ROM) using a microcomputer and storing programs necessary for various kinds of software processing for controlling the cooling water temperature of the cooling device of the internal combustion engine. central processing unit for execution (CPU), composed mainly of a writable memory (RAM) for temporarily storing variables required for the program.

The control device 500 includes the detecting means 40
The detection signal output from 0 is input, and the detection means 400 sends a drive signal to the drive device 30 provided in the flow control valve 1 according to the operation state. In response to this drive signal, the drive device 30 rotates the valve body 20 of the flow control valve 1 to control the rotation position to a target rotation position. Thus, the first fluid passage 14a corresponding to the radiator 200 of the flow control valve 1 and the second fluid passage 14a corresponding to the bypass passage 300
The cooling water introduced by the fluid passage 14b of the internal combustion engine 100 and the third fluid passage 14c corresponding to the heat exchanger 900 is changed to a flow ratio of each flow, and the internal combustion engine 100 through the fourth fluid passage 12a. to be returned.

Therefore, as shown in FIG. 5, when the internal combustion engine 100 is started, the valve body 20 is rotated to correspond to the first fluid passage 14a corresponding to the radiator 200 and the heat exchanger (heater) 900. The third fluid passage 14c to be closed is fully closed, and the opening area of the second fluid passage 14b corresponding to the bypass passage 300 is set to a turning position in a state where the opening area is narrowed, so that the cooling water is circulated, so heating of the cooling water can be further hasten.

[Brief description of the drawings]

1 is a longitudinal sectional view of the flow control valve of the embodiment of the present invention.

2 is a plan view of a seal plate used in the flow control valve of the present invention.

FIG. 3 is a plan view of a valve used for the flow control valve of the present invention.

4 is a plan view of the superposition of the valve seal plate and the diagram of FIG 3.

5 is a plot showing an opening area characteristic of the flow control valve of the embodiment of the present invention.

6 is a schematic view showing a configuration of a cooling apparatus for an internal combustion engine using a flow control valve of the embodiment of the present invention.

[Explanation of symbols]

 1 ... flow control valve 12a ... fourth fluid passages 14a, 14b, 14c ... first, second, third fluid passage 20 ... valve body 22 ... Valve 26 ... sealing plate 30 ... driving device 40 ... reduction gear 50 ... Return spring 100 ... internal combustion engine 200 ... radiator 300 ... bypass passage 900 ... heat exchanger (heater)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H062 AA07 AA15 BB28 CC02 EE07 FF41 HH04 HH10 3H063 AA05 BB39 DA14 DB36 GG01 GG11 3H067 AA13 CC04 CC38 DD03 DD12 DD32 EA03 EB24 FF11 GG01 GG21

Claims (8)

[The claims] 1. A valve housing including a first fluid passage, a second fluid passage, and a third fluid passage for introducing a cooling medium, and a fourth fluid passage for leading the cooling medium, and the valve. is rotatably supported in the housing, the first,
A flow control valve, comprising: a valve body for switching a flow rate of the cooling medium introduced from second and third fluid passages; and a drive device for driving the valve body to be rotatable, wherein the drive device and the valve A drive unit that increases a drive torque of the drive unit; and a return spring that urges the valve body driven through the speed reducer, the drive unit is not operating. In some cases, two of the three introduction fluid passages are communicated by rotating the valve body by the return spring. 2. The flow control valve according to claim 1, wherein the speed reducer includes a two-stage planetary gear. Wherein the valve body is a shaft, said shaft relative is restrained in the rotational direction without being constrained in the vertical direction, a disk-shaped valve two openings are bored, said valve lower A disc-shaped seal plate fixed within the valve housing and having three independent openings communicating with the first, second and third fluid passages. The flow control valve according to claim 1, wherein the opening of the first, second, and third fluid passages is changed by rotating the valve. 4. The seal plate and the valve are pressed against each other by the spring,
4. The flow control valve according to claim 3, wherein the cooling medium does not leak from the space. Wherein said valve housing consists of an upper housing and a lower housing, the periphery of the sealing plate, characterized in that it is fixedly clamped in a liquid-tight between the upper and lower housings claims The flow control valve according to 3 or 4. 6. The flow control valve according to claim 3, wherein the material of the seal plate is a material having a low friction coefficient. 7. A cooling device for an internal combustion engine using the flow control valve according to claim 1, wherein the cooling water in a cooling water circuit of the water-cooled internal combustion engine is cooled by heat radiation. A heat exchanger (heater) provided in the middle of a cooling water circuit of the internal combustion engine and used for heating a vehicle living space or the like using cooling water from the internal combustion engine; and a heat exchanger (heater) for the internal combustion engine and the radiator. A bypass passage that is disposed between the cooling water and returns to the internal combustion engine without passing through the radiator; and the cooling water that returns to the internal combustion engine from the radiator, the heat exchanger, and the bypass passage, respectively, is joined. A flow control valve disposed in a cooling water circuit for controlling a flow rate of each cooling water returned to the internal combustion engine; a detection unit for detecting an operation state of the internal combustion engine; A control circuit that controls a variable flow rate of the flow control valve based on a signal that is output from the control circuit, based on a drive signal output from the control circuit in accordance with an operation state detected by the detection unit. A cooling device for an internal combustion engine, which controls a temperature. 8. the fluid passage back to the internal combustion engine from the radiator to the fully closed state, from said bypass passage when reducing the opening area of the fluid passage back to the internal combustion engine, to the internal combustion engine from the heat exchanger at the same time Back reduce the opening area of the fluid passage, the cooling system of an internal combustion engine according to claim 7, wherein the controlled is possible to close.