阅读说明：本技术 发动机冷却装置 (Engine cooling device ) 是由 高木登 加藤和树 山口正晃 高冈俊夫 于 2020-08-27 设计创作，主要内容包括：本发明涉及发动机冷却装置。发动机冷却装置具有：机械水泵；流量控制阀,所述流量控制阀具有阀体,所述阀体的相对旋转位置由电动机改变；以及控制单元,所述控制单元执行电动机的驱动控制,以将阀体的相对旋转位置变为目标相对旋转位置。当发动机转速上升时,控制单元执行保护控制,所述保护控制用于将耐压极限转速等于或高于当前发动机转速的相对旋转位置设定成流量控制阀的阀体的目标运行位置,并且当车载电源的供应电压已经下降时,控制单元执行退避控制,所述退避控制用于将目标相对旋转位置的设定范围减小到指定退避运行范围。(The present invention relates to an engine cooling device. The engine cooling device comprises: a mechanical water pump; a flow control valve having a valve body whose relative rotational position is changed by a motor; and a control unit that performs drive control of the motor to change the relative rotational position of the valve body to the target relative rotational position. When the engine speed increases, the control unit executes protection control for setting a relative rotation position at which the withstand voltage limit rotational speed is equal to or higher than the current engine speed as a target operation position of a valve body of the flow control valve, and when the supply voltage of the vehicle-mounted power supply has decreased, the control unit executes retraction control for decreasing the set range of the target relative rotation position to a specified retraction operation range.)

1. An engine cooling device characterized by comprising:

a circulation circuit for coolant flowing through a water jacket formed inside the engine;

a mechanical water pump that operates in response to rotation of the engine, and that circulates the coolant through the circulation circuit;

a flow control valve for regulating a flow rate of the coolant flowing through the circulation circuit, the flow control valve having a valve body driven by an electric actuator that is operated by being supplied with electric power from an on-vehicle power supply, and the flow control valve allowing a flow passage area of the coolant to be changed in accordance with an operation position of the valve body; and

a control unit that sets an operating position within a specified control range to a target operating position according to an operating condition of the engine, and that executes drive control of the actuator to change the operating position of the valve body to the set target operating position, wherein

In a case where a pressure-resistant limit rotational speed is defined as an engine rotational speed maximum value at which a hydraulic pressure in any region of the circulation circuit is lower than an upper limit of a hydraulic pressure that can be allowed in that region, and a maximum pressure-resistant operating position is defined as an operating position at which the pressure-resistant limit rotational speed is highest among operating positions within the control range, the control unit executes protection control for setting the operating position at which the pressure-resistant limit rotational speed is equal to or higher than a current engine rotational speed as the target operating position, and when a supply voltage of the vehicle-mounted power supply has dropped, the control unit executes retreat control for reducing the control range to a retreat operating range that is set in advance to a range including the operating position of the maximum pressure-resistant operating position.

2. The engine cooling apparatus according to claim 1, characterized by further comprising:

a storage unit in which information about the pressure-resistant limit rotational speed at each operating position of the valve body is stored, wherein

The control unit obtains an operation position of the valve body at which the pressure-resistant limit rotational speed is higher than the current engine rotational speed, based on the information stored in the storage unit, and executes the protection control by setting the obtained operation position to the target operation position.

3. The engine cooling apparatus according to claim 1 or 2, characterized in that:

the control unit determines whether the engine torque needs to be decreased by: the control unit determines that the engine torque needs to be reduced when the current engine speed has remained higher than the pressure resistance limit speed at the current operating position of the valve body for a specified time or longer.

4. The engine cooling apparatus according to any one of claims 1 to 3, characterized in that:

the control unit determines that the supply voltage of the vehicle-mounted power supply has dropped when the supply voltage is equal to or lower than a voltage drop determination value, and sets a higher voltage to the voltage drop determination value when an elapsed time after the engine is started is shorter than a specified time than when the elapsed time is equal to or longer than the specified time.

5. The engine cooling apparatus according to any one of claims 1 to 4, characterized in that:

the control unit also executes the backoff control when the temperature of the coolant is equal to or lower than a specified low coolant temperature determination value.

6. The engine cooling apparatus according to any one of claims 1 to 5, characterized in that:

the control unit also executes the backoff control when the engine speed is equal to or higher than a specified backoff start speed.

7. The engine cooling apparatus according to claim 6, characterized in that:

the engine cooling device is applied to an engine mounted on a vehicle, and

when the power transmission between the engine and the wheels is cut off, the control unit sets a lower rotation speed to the retreat start rotation speed than when the power transmission between the engine and the wheels is not cut off.

8. The engine cooling apparatus according to any one of claims 1 to 7, characterized in that:

the engine cooling device is applied to an engine mounted on a vehicle, and

the control unit also executes the retraction control while the vehicle is coasting.

Technical Field

The present invention relates to an engine cooling device equipped with a mechanical water pump and a flow control valve.

Background

The device described in japanese patent application publication No. 2013-234605 (JP 2013-234605A) is generally referred to as a water-cooled engine cooling device that cools an engine by circulating coolant through a water jacket formed inside the engine. The engine cooling device described in japanese patent application publication No. 2013-234605 (JP 2013-234605A) is provided with: a mechanical water pump that delivers coolant to the water jacket in response to rotation of the engine; and an electronic control valve that closes to restrict the flow of coolant from the water jacket. Further, when the engine has not been warmed up, the warming-up of the engine is accelerated by closing the electronic control valve to leave the coolant in the water jacket.

Incidentally, the discharge pressure of the mechanical water pump rises as the engine speed rises. Therefore, when the engine speed becomes high with the electronic control valve closed, the hydraulic pressure of the water jacket may become too high. As a countermeasure to such a problem, the above-described conventional engine cooling device suppresses the rise in hydraulic pressure of the water jacket by: in the case where the engine speed becomes equal to or higher than a certain speed when the electronic control valve is closed to accelerate the warming-up, the electronic control valve is forcibly opened without waiting for the completion of the warming-up.

Disclosure of Invention

However, when the supply voltage of the vehicle-mounted electric power source decreases, the time required to open the electronic control valve becomes long, and the hydraulic pressure remains high during this time. Therefore, the hydraulic pressure rise may not be sufficiently suppressed.

An engine cooling device that solves the above problems is equipped with: a circulation circuit for coolant flowing through a water jacket formed inside the engine; a mechanical water pump that operates in response to rotation of the engine and circulates coolant through the circulation circuit; a flow control valve for regulating a flow rate of the coolant flowing through the circulation circuit, and having a valve body driven by an electric actuator that is operated by being supplied with electric power from an on-vehicle power supply, and that allows a flow passage area of the coolant to be changed according to an operation position of the valve body; and a control unit that sets an operating position within a specified control range to a target operating position according to an operating condition of the engine, and that executes drive control of the actuator to change the operating position of the valve body to the set target operating position. The control unit in the above-described engine cooling device executes the protection control for setting the operation position where the withstand voltage limit rotational speed is equal to or higher than the current engine rotational speed to the target operation position. Further, when the supply voltage of the vehicle-mounted power supply has dropped, the control unit executes a retraction control for reducing the control range to a retraction operation range that is set in advance to an operation position range including the maximum withstand voltage operation position. Incidentally, the pressure-resistant limit rotational speed mentioned herein means a maximum value of the engine rotational speed at which the hydraulic pressure in any region of the circulation circuit is lower than the upper limit of the hydraulic pressure that can be allowed in that region. The maximum pressure-resistant operating position means an operating position at which the pressure-resistant limit rotation speed is highest among the operating positions in the control range.

In the engine cooling device configured as described above, the mechanical water pump that operates in response to rotation of the engine circulates the coolant through the circulation circuit. Therefore, when the engine speed increases, the hydraulic pressure of the circulation circuit increases. Then, when the hydraulic pressure in any region of the circulation circuit has been kept higher than the pressure-resistant limit in that region, i.e., higher than the upper limit of the hydraulic pressure that can be allowed in that region, as a result, component members of the circulation circuit cannot withstand the hydraulic pressure, causing leakage of the coolant, or the like.

On the other hand, when the operating position of the valve body of the flow control valve is changed to change the flow of the coolant flowing through the circulation circuit, the hydraulic pressure in each region of the circulation circuit is changed. Therefore, when the operation position of the flow control valve is changed to prevent the hydraulic pressure from being higher than the pressure-resistant limit in any region of the circulation circuit even when the engine speed rises, it is possible to protect the component members of the circulation circuit from the hydraulic pressure. Incidentally, the maximum value of the engine speed (i.e., the pressure-resistant limit rotational speed), at which the hydraulic pressure in any region of the circulation circuit is lower than the upper limit of the hydraulic pressure that can be allowed in that region, differs depending on the operating position of the valve body. Therefore, it is possible to protect the component members of the circulation circuit from the hydraulic pressure by driving the valve body to the operation position where the withstand voltage limit rotational speed is equal to or higher than the current engine rotational speed. Therefore, when the engine speed rises, the control unit of the above-described engine cooling device protects the component members of the circulation circuit from the hydraulic pressure by executing the protection control for setting the operation position where the withstand voltage limit rotational speed is equal to or higher than the current engine speed to the target operation position.

Incidentally, in the above-described engine cooling device, the operating position of the valve body is changed by an electric actuator that is operated by being supplied with electric power from an in-vehicle power supply. Therefore, when the supply voltage of the vehicle-mounted power supply decreases, the speed at which the operating position of the valve body is changed by the actuator decreases. Thus, when the supply voltage has dropped, the time required to change the operating position of the valve body in the protection control becomes long, and it may become impossible to sufficiently suppress the rise in the hydraulic pressure of the circulation circuit.

As a countermeasure against such a problem, in the case of the above-described engine cooling device, when the supply voltage of the vehicle-mounted power supply has dropped, the retreat control for reducing the control range to the retreat operation range set in advance as the operation position range including the maximum withstand voltage operation position is executed. Then, the operating position of the valve body is thus changed to an operating position within the retreat operating range, that is, within a range not too far from the maximum pressure-resistant operating position. Therefore, even when the amount of change in the operating position of the valve body has stopped increasing after reaching a certain amount and the speed of change in the operating position of the valve body has decreased in response to a drop in the supply voltage of the vehicle-mounted power supply in the protection control in the case where the protection control is performed in response to a rise in the engine speed thereafter, the time required to change the operating position of the valve body in the protection control is unlikely to become long. Thus, in the case of the above-described engine cooling device, when the engine speed increases, the time required to suppress the increase in the hydraulic pressure of the circulation circuit is unlikely to become long, even when the supply voltage of the vehicle-mounted electric power source has decreased.

Incidentally, also in the above-described protection control, unless the appropriate operation position where the pressure resistance limit rotational speed is equal to or higher than the current engine rotational speed is set to the target rotational position, the rise in the hydraulic pressure cannot be sufficiently suppressed. As a countermeasure to such a problem, the above-described engine cooling device may be provided with a storage unit in which information on the pressure-resistant limit rotational speed at each operating position of the valve body is stored, and based on the information stored in the storage unit, the control unit may execute the protection control by obtaining an operating position of the valve body at which the pressure-resistant limit rotational speed is higher than the current engine rotational speed and by setting the obtained operating position to the target operating position. In this case, information on the pressure-resistant limit rotational speed at each operating position of the valve body is stored in the storage unit in advance. Therefore, based on this information, the operating position at which the withstand voltage limit rotational speed is equal to or higher than the current engine rotational speed can be appropriately set to the target rotational position.

In the case where the rise in the hydraulic pressure of the circulation circuit cannot be sufficiently suppressed even when the above-described protection control is executed, it is conceivable to achieve protection of the component members of the circulation circuit by reducing the engine torque to reduce the engine speed. This additional reduction in engine torque may be determined by: when the current engine speed has remained higher than the pressure-resistant limit speed at the current operating position of the valve body for the specified time or longer, the control unit of the above-described engine cooling device is caused to make a determination as to the necessity of reducing the engine torque by determining that the engine torque needs to be reduced.

Immediately after the engine is started, the supply voltage of the vehicle-mounted power supply may temporarily drop due to the power consumption at the start of the engine. This drop in the supply voltage of the vehicle-mounted power supply immediately after the engine start is stopped in a short time. Therefore, it is not usually necessary to perform the back-off control at this time as a measure against the supply voltage drop. In these cases, the control unit of the above-described engine cooling device may determine that the supply voltage of the vehicle-mounted power supply has dropped when the supply voltage is equal to or lower than the voltage drop determination value, and when an elapsed time after the engine is started is shorter than a specified time, set a higher voltage to the voltage drop determination value than when the elapsed time is equal to or longer than the specified time.

When the temperature of the coolant is low, the viscosity of the coolant is high, and the flow resistance of the coolant applied to the valve body when changing the operation position is high. Therefore, even when the temperature of the coolant is low, the speed at which the operating position of the valve body is changed by the actuator is low. Therefore, it is also desirable for the control unit of the engine cooling device described above to execute the backoff control when the temperature of the coolant is equal to or lower than the specified low coolant temperature determination value.

Incidentally, in the case where the protection control can be executed for a short time even when the supply voltage of the in-vehicle power supply has not dropped, it is desirable to enable the change of the operation position of the valve body in the protection control to be completed in a short time by executing the evacuation control. In one of these cases, the engine speed has risen to such an extent that the protection control needs to be executed due to a subsequent slight rise in the engine speed. Therefore, the control unit of the above-described engine cooling device may also execute the backoff control when the engine speed is equal to or higher than the specified backoff-starting speed. Further, in the case where such an engine cooling device is applied to an engine mounted on a vehicle, when power transmission between the engine and wheels is cut off, the control unit may set a lower rotation speed to the retract-start rotation speed than when power transmission between the engine and the wheels is not cut off. When the power transmission between the engine and the wheels is cut off, the rotational load of the engine is low, so the rate of increase in the engine rotational speed tends to be higher than when the above-described power transmission is not cut off. Therefore, when the above-described power transmission is cut off, it is desirable that the back-off control be executed with a lower engine speed than when the above-described power transmission is not cut off.

Further, in an engine mounted on a vehicle, when the engine is dragged along with rotation of wheels, the engine rotation speed may rapidly increase due to downshifting or the like during coasting of the vehicle. Therefore, in the case where the above-described engine cooling device is applied to an engine mounted on a vehicle, it is desirable that the control unit execute the retraction control while the vehicle is coasting.

Drawings

Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and wherein:

FIG. 1 is a view schematically showing the configuration of an engine cooling device according to one embodiment;

FIG. 2 is a perspective view of a flow control valve disposed in the cooling device;

FIG. 3 is an exploded perspective view of the flow control valve;

FIG. 4 is a perspective view of a valve body that is a component member of the flow control valve;

FIG. 5 is a perspective view of a housing as another component of the flow control valve;

fig. 6A is a graph showing a relationship between a relative angle of a valve body of a flow control valve and an opening ratio of a corresponding output port;

fig. 6B is a graph showing the relationship between the relative angle of the valve body and the pressure-resistant limit rotational speed;

fig. 7 is a flowchart showing a part of a processing routine of a flow rate control valve control routine executed by a control unit provided in the engine cooling device according to the embodiment; and is

Fig. 8 is a flowchart showing the remaining part of the processing procedure of the flow control valve control routine.

Detailed Description

An engine cooling device according to one embodiment will be described hereinafter with reference to fig. 1 to 8. The engine cooling device according to the present embodiment is applied to an engine mounted on a vehicle having an automatic transmission. As shown in fig. 1, the engine cooling apparatus according to the present embodiment is equipped with a circulation circuit 21 through which the coolant flowing through a water jacket 111 in a cylinder block 11 of the engine 10 and a water jacket 121 in a cylinder head 12 of the engine 10 circulates. The circulation circuit 21 is provided with a mechanical water pump 22, and the mechanical water pump 22 discharges the coolant toward a water jacket 111 in the cylinder block 11. Further, the circulation circuit 21 is provided with three heat exchangers, namely, a radiator 23, an ATF warmer 24, and a heater core 25 of an air conditioner of a vehicle. The radiator 23 cools the coolant by heat exchange with outside air. The ATF warmer 24 heats or cools Automatic Transmission Fluid (ATF), which is hydraulic oil of an automatic transmission 241 coupled to the engine 10, through heat exchange with the coolant. The heater core 25 warms air blown into the vehicle compartment by air conditioning by heat exchange with the coolant.

Incidentally, the water pump 22 is coupled to a crankshaft 101 of the engine 10 via a circulating transmission mechanism 102. Thus, the water pump 22 operates in response to rotation of the crankshaft 101 of the engine 10, and conveys the coolant toward the water jacket 111.

The circulation circuit 21 is provided with a flow control valve 26, and the coolant that has flowed out from the water jacket 121 in the cylinder head 12 flows into this flow control valve 26. The flow control valve 26 has three ports, i.e., a radiator port P1, a device port P2, and a heater port P3, as output ports through which the coolant that has flowed into the flow control valve 26 flows out. The radiator port P1 is connected to the first coolant passage 271, and the coolant flows through the first coolant passage 271 via the radiator 23. The device port P2 is connected to the second coolant passage 272, and the coolant flows through the second coolant passage 272 via the ATF warmer 24. The heater port P3 is connected to the third coolant passage 273, and the coolant flows through the third coolant passage 273 via the heater core 25. Incidentally, the circulation circuit 21 is provided with a coolant temperature sensor 122, and this coolant temperature sensor 122 detects the temperature of the coolant that flows into the flow control valve 26 after flowing out from the water jacket 121 in the cylinder head 12.

Further, the engine cooling device according to the present embodiment is equipped with a control unit 50, the control unit 50 serving as a control unit of the engine cooling device. The control unit 50 is equipped with: an arithmetic processing circuit 51, the arithmetic processing circuit 51 executing arithmetic processing for controlling the engine cooling device; and a memory 52, and the memory 52 stores a program and data for control. Further, the control unit 50 is equipped with a voltage adjusting circuit 54, and the voltage adjusting circuit 54 adjusts the voltage supplied from the vehicle-mounted power supply 53 by pulse width modulation, and supplies the adjusted voltage to the motor 37 built in the flow rate control valve 26. Incidentally, various pieces of information regarding the operating conditions of the engine 10 and the running conditions of the vehicle are input to the control unit 50. The information block input to the control unit 50 includes the coolant temperature detected by the coolant temperature sensor 122, the engine speed NE, the setting of the shift range of the automatic transmission 241, the operation amount of the accelerator pedal, the supply voltage of the vehicle-mounted power supply 53, and information on how the vehicle compartment is air-conditioned and warmed. Incidentally, the control unit 50 is connected to an engine control unit 55 as an electronic control unit for engine control through an in-vehicle communication line.

Subsequently, the configuration of the flow control valve 26 will be described with reference to fig. 2 to 6B. As shown in fig. 2, the flow control valve 26 is equipped with a housing 31, and the housing 31 forms a skeleton of the flow control valve 26. The first, second and third connector members 32, 33, 34 are attached to the housing 31. The first connector member 32 is provided with a heat sink port P1. The second connector member 33 is provided with a device port P2. The third connector member 34 is provided with a heater port P3. Further, in the case where the connector members 32 to 34 are attached to the housing 31, the output ports P1 to P3 are arranged at different positions.

As shown in fig. 3, the flow control valve 26 is equipped with a valve body 35, and the valve body 35 is accommodated in the housing 31. A coolant passage is formed in the valve body 35. Further, a shaft 36 extending in the axial direction Z of the housing 31 is coupled to the valve body 35. Further, the valve body 35 rotates about the shaft 36 as indicated by the arrow in fig. 3. When the relative angle ANG of the valve body 35 with respect to the housing 31 is changed by the rotation of the valve body 35, the degree to which the coolant passage formed in the valve body 35 overlaps with the output ports P1 to P3 is changed, and the flow passage areas of the coolant at the output ports P1 to P3 are changed. That is, the flow of the coolant in the circulation circuit 21 can be controlled by changing the rotational phase of the valve body 35 with respect to the housing 31.

The motor 37 is accommodated in the housing 31 of the flow control valve 26. Furthermore, a transmission 38 is provided in the housing 31. The transmission mechanism 38 has a plurality of gears 39 that mesh with each other, and the transmission mechanism 38 transmits the output of the motor 37 to the shaft 36 of the valve body 35 via the gears 39.

The cover 40 is attached to the housing 31 in such a manner that the cover 40 covers the portion of the housing 31 that houses the motor 37 and the transmission mechanism 38. A rotation angle sensor 123 that detects the rotation angle of the motor 37 is mounted in the cover 40. Incidentally, information on the rotation angle of the motor 37 detected by the rotation angle sensor 123 is also input to the control unit 50.

As shown in fig. 4, the valve body 35 takes a shape obtained by, for example, superimposing two barrels on each other in the axial direction Z of the housing 31. Two holes 351 and 352 (i.e., a first hole 351 and a second hole 352) aligned in the axial direction Z are formed through the side wall of the valve body 35. The holes 351 and 352 constitute portions of the coolant passage provided in the valve body 35. The first hole 351 is located at the upper side in the drawing, and when the valve body 35 is within a certain angular range with respect to the housing 31, the first hole 351 communicates with the radiator port P1. When the first bore 351 communicates with the radiator port P1, the coolant that has flowed into the flow control valve 26 flows out from the radiator port P1. Further, when the valve body 35 is in another angular range with respect to the housing 31, the second hole 352 communicates with at least one of the device port P2 and the heater port P3. When the second hole 352 communicates with the device port P2, the coolant that has flowed into the flow control valve 26 flows out from the device port P2. Further, when the second hole 352 communicates with the heater port P3, the coolant that has flowed into the flow control valve 26 flows out from the heater port P3.

In the case where the upper wall 353 of the valve body 35 is defined as the upper wall of the valve body 35 in the drawing, the shaft 36 is connected to the upper wall 353. Further, the upper wall 353 is provided with an annular groove 355 extending in such a manner as to surround the root of the shaft 36 so as to have a part of the shaft 36 as the engaging portion 354.

Fig. 5 shows a perspective structure of the housing 31 viewed in the direction of insertion into the valve body 35. When the flow control valve 26 is assembled, the valve body 35 is inserted into the housing 31 via the accommodation opening 311. The portion of the housing 31 facing the upper wall 353 of the valve body 35 is provided with a stop 312 received in the recess 355. Therefore, when the valve body 35 is accommodated in the housing 31, the engagement portion 354 of the valve body 35 abuts against the stopper 312, thereby holding the valve body 35 against rotation relative to the housing 31. That is, the range in which the engaging portion 354 does not abut on the stopper 312 is a range in which the valve body 35 is allowed to rotate relative to the housing 31.

The coolant flows into the housing 31 of the flow control valve 26 via the receiving opening 311. That is, the receiving opening 311 serves as an input port of the flow control valve 26. Then, the coolant that has flowed into the housing 31 flows through the coolant passage provided in the valve body 35, and is guided to the output ports P1 to P3.

Fig. 6A is a graph showing the relationship between the relative angle ANG of the valve body 35 with respect to the housing 31 and the opening ratios of the output ports P1 to P3. Incidentally, in the present embodiment, the relative angle ANG is used as a state quantity indicating the operation position of the valve body 35 in the flow control valve 26. Each opening ratio represents a ratio of the flow passage area corresponding to one output port, assuming that the opening ratio is 100% when the output port is fully opened.

In the flow control valve 26, it is assumed that the relative angle ANG is "0 °" when all the output ports P1 to P3 are closed, and the valve body 35 is rotatable in the positive and negative directions with respect to the housing 31 until the stopper 312 of the housing 31 and the engagement portion 354 of the valve body 35 abut against each other. The sizes and positions of the holes 351 and 352 of the valve body 35 are set such that the opening degrees of the output ports P1 to P3 change with a change in the relative angle ANG as shown in fig. 6A. In the present embodiment, when the valve body 35 is rotated in the forward direction with respect to the housing 31, the relative angle ANG increases. On the other hand, when the valve body 35 is rotated in the negative direction with respect to the housing 31, the relative angle ANG decreases.

In the flow control valve 26, when the valve body 35 is relatively rotated in the forward direction from the position where the relative angle ANG is "0 °, the heater port P3 first starts to open, and the opening degree of the heater port P3 gradually increases with an increase in the relative angle ANG. Then, when the relative angle ANG is further increased after the heater port P3 is fully opened, the device port P2 is opened. The opening degree of the device port P2 increases with an increase in the relative angle ANG. Then, after the device port P2 is fully opened, the radiator port P1 starts to be opened. The opening degree of the radiator port P1 also increases with the increase in the relative angle ANG. In the case where the relative angle is "+ β °" when the engagement portion 354 and the stopper 312 abut against each other, the radiator port P1 is fully opened before the valve body 35 reaches the position where the relative angle ANG is "+ β °". Then, even when the relative angle ANG increases, the output ports P1 to P3 remain fully opened until the valve body 35 reaches a position where the relative angle ANG is "+ β °".

On the other hand, in the flow control valve 26, when the valve body 35 is relatively rotated in the negative direction from the position where the relative angle ANG is "0 °", the heater port P3 is not opened. In this case, the device port P2 starts to open first, and the opening degree of the device port P2 gradually increases as the relative angle ANG decreases. Then, the relative angle ANG is further reduced after the device port P2 is fully opened, and the radiator port P1 is opened. The opening degree of the radiator port P1 increases as the relative angle ANG decreases. In the case where the relative angle is "- α °" when the engaging portion 354 and the stopper 312 abut against each other, the radiator port P1 is fully opened before the valve body 35 reaches the position of the relative angle "- α °. Then, even when the relative angle ANG is decreased, the radiator port P1 and the device port P2 remain fully opened until the valve body 35 reaches a position at a relative angle of "- α °.

Incidentally, in the engine cooling device configured as described above, the coolant is circulated through the circulation circuit 21 by the mechanical water pump 22, which mechanical water pump 22 operates in response to the rotation of the engine 10. In this engine cooling device, the discharge pressure of the coolant in the water pump 22 increases as the engine speed NE increases. On the other hand, in the above-described engine cooling device, the flow of the coolant flowing through the circulation circuit 21 is changed by the flow control valve 26. In this engine cooling device, the hydraulic pressure at the corresponding position of the circulation circuit 21 is determined by the engine speed NE and the relative angle ANG of the valve body 35 of the flow control valve 26.

Incidentally, there is an upper limit of the allowable hydraulic pressure for each component member of the circulation circuit 21. When the hydraulic pressure is kept higher than the upper limit, leakage of the coolant may be caused. In the following description, the upper limit of the allowable hydraulic pressure of each component member of the circulation circuit 21 will be referred to as the pressure-resistant limit thereof. Further, the maximum value of the engine speed NE at which the hydraulic pressure in any region of the circulation circuit 21 is lower than the upper limit of the hydraulic pressure that can be allowed in that region will be referred to as a pressure-resistant limit speed.

In the present embodiment, in designing the engine cooling device, the value of the pressure-resistant limit rotation speed per one relative angle ANG of the valve body 35 of the flow control valve 26 is obtained through experiments, simulations, and the like. Further, a map M indicating a pressure-resistant limit rotation speed value of each relative angle ANG of the valve body 35 is stored in the memory 52 of the control unit 50. In the engine cooling device according to the present embodiment, the memory 52 corresponds to a storage unit in which information on the pressure-resistant limit rotational speed for each operating position of the valve body 35 is stored.

Fig. 6B shows the relationship between the relative angle ANG of the valve body 35 and the pressure-resistant limit rotation speed in the engine cooling device according to the present embodiment. When the valve body 35 is located at the position where the relative angle ANG is "0 °, the opening rates of the output ports P1 to P3 are all" 0% ", and the flow of the coolant is blocked by the flow control valve 26. In the following description, a portion of the circulation circuit 21 downstream of the water pump 22 and upstream of the flow control valve 26 will be referred to as a pump/valve gap portion. When the engine speed NE rises and therefore the discharge pressure of the water pump 22 also rises with the flow of the coolant blocked by the flow control valve 26, the hydraulic pressure at the pump/valve gap portion reaches the pressure-resistant limit. At this time, the pressure-resistant limit rotational speed is the engine rotational speed NE at which the hydraulic pressure at the pump/valve gap portion reaches the pressure-resistant limit.

When the valve body 35 is relatively rotated in the forward direction from the position where the relative angle ANG is "0 °, the output ports P1 to P3 are sequentially opened, and the coolant is delivered from the output ports P1 to P3. Then, as a result, the hydraulic pressure at the pump/valve gap portion is reduced. Therefore, when the valve body 35 is relatively rotated in the forward direction from the position where the relative angle ANG is "0 °", the pressure resistance limit rotation speed gradually increases.

On the other hand, when the flow rate of the coolant sent from the radiator port P1 to the first coolant passage 271 increases, the pressure loss of the coolant flowing through the radiator 23 increases, and the hydraulic pressure in the portion of the circulation circuit 21 that is upstream of the radiator 23 in the first coolant passage 271 increases. In the following description, a portion of the circulation circuit 21 that is upstream of the radiator 23 in the first coolant passage 271 will be referred to as a valve/radiator gap portion.

When the valve body 35 is relatively rotated to a position where the relative angle ANG is "γ °", the engine speed NE at which the hydraulic pressure at the pump/valve gap portion reaches the pressure-proof limit becomes equal to the engine speed NE at which the hydraulic pressure at the valve/radiator gap portion reaches the pressure-proof limit. When the valve body 35 is further relatively rotated in the forward direction from the position where the relative angle ANG is "γ °", the engine speed NE at which the hydraulic pressure at the pump/radiator gap portion reaches the pressure-proof limit becomes lower than the engine speed NE at which the hydraulic pressure at the pump/valve gap portion reaches the pressure-proof limit. Therefore, in the range where the relative angle ANG is larger than "γ °", the pressure-resistant limit rotation speed is the engine rotation speed NE at which the hydraulic pressure at the valve/radiator gap portion reaches the pressure-resistant limit. Incidentally, when the valve body 35 is relatively rotated in the forward direction from the position where the relative angle ANG is "γ °", the flow rate of the coolant in the first coolant passage 271 also increases as the opening ratio of the radiator port P1 increases. Therefore, the engine speed NE at which the hydraulic pressure at the valve/radiator gap portion reaches the pressure-proof limit falls. As a result, when the valve body 35 is relatively rotated in the forward direction from the position where the relative angle ANG is "0 °, the pressure resistance limit rotational speed stops rising and starts falling at the position where the relative angle ANG is" γ °.

For the same reason, when the valve body 35 is also relatively rotated in the negative direction from the position where the relative angle ANG is "0 °", the pressure resistance limit rotational speed rises until the valve body 35 reaches the position where the relative angle ANG is "- δ °", and thereafter, the pressure resistance limit rotational speed starts to fall. In this way, the pressure-resistant limit rotational speed is locally maximum at each of the relative rotational position of the valve body 35 at the relative angle ANG of "γ °" and the relative rotational position of the valve body 35 at the relative angle ANG of "- δ °. Incidentally, the three output ports P1 to P3 are all open at the relative rotational position of the valve body 35 at the relative angle ANG of "γ °. In contrast, at the relative rotational position of the valve body 35 at the relative angle ANG of "- δ °, of the three output ports P1 to P3, only the radiator port P1 and the device port P2 are open. Therefore, in the range of the relative rotation of the valve body 35 from the position where the relative angle ANG is "- α °" to the position where the relative angle ANG is "β °", when the valve body 35 has been relatively rotated to the position where the relative angle ANG is "γ °", the pressure-resistant limit rotation speed is maximized. In the following description, the relative rotational position of the valve body 35 at the relative angle ANG of "γ °" will be referred to as a maximum pressure-resistant relative rotational position.

Subsequently, the control of the flow control valve 26 of the engine cooling device according to the present embodiment will be described. Fig. 7 and 8 are flowcharts of a flow control valve control routine executed by the control unit 50 when controlling the flow control valve 26. During operation of the engine 10, the control unit 50 repeatedly executes the processing of the routine for a given control cycle.

When the processing of the present routine is started, first, a required relative rotational position is calculated in step S100. Specifically, the relative angle ANG of the valve body 35 at which the opening ratios of the output ports P1 to P3 satisfy the requirements for warming and cooling of the engine 10 and ATF and the requirement for warming of the vehicle cabin by the air conditioner is calculated as the value of the required relative rotational position. Incidentally, the relative rotational position of the valve body 35 set to the required relative rotational position ranges from a position where the relative angle ANG is "- α °" to a position where the relative angle ANG is "β °".

Subsequently, in steps S110 to S170, it is determined whether conditions (i) to (v) shown below are satisfied. The condition (i) is that the shift range (P) for parking or the neutral shift range (N) is set as the shift range of the automatic transmission 241 and the engine rotation speed NE is equal to or higher than the specified retract-start rotation speed N1 (yes in S110). Incidentally, as shown in fig. 6B, the engine speed NE lower than the minimum value of the withstand voltage limit rotational speed is set to the value of the evacuation start rotational speed N1.

The condition (ii) is that the shift range for running, i.e., the shift range for forward running (D) or the shift range for backward running (R), is set as the shift range of the automatic transmission 241, and the engine rotation speed NE is equal to or higher than the specified retract-start rotation speed N2 (yes in S120). Incidentally, the engine speed NE higher than the retract-start speed N1 in the condition (i) is set to the value of the retract-start speed N2 in the condition (ii).

Condition (iii) is that the vehicle is coasting (yes in S130). In the present embodiment, it is determined that the vehicle is coasting when the operation amount of the accelerator pedal has been kept equal to "0" and the engine speed NE has been kept equal to or higher than the specific speed for the specified time or longer.

The condition (iv) is that the elapsed time after start, which is the elapsed time after the start of the engine 10, is shorter than the specified time T0 (no in S140), and the supply voltage of the vehicle-mounted power supply 53 is lower than the voltage drop determination value V1 (yes in S150).

The condition (V) is that the elapsed time after the startup is equal to or longer than the specified time T0 (yes in S140), and the supply voltage of the vehicle-mounted power supply 53 is equal to or lower than the voltage drop determination value V2 (yes in S160). Incidentally, a voltage higher than the voltage drop determination value V1 is set to the voltage drop determination value V2.

Condition (vi) is that the temperature of the coolant is lower than the specified low-temperature determination value (yes in S170). When none of the conditions (i) to (vi) is satisfied, the value of the required relative-rotation position is directly set to the value of the target relative-rotation position in step S180, and then the process proceeds to step S210. As described above, the relative rotational position of the valve body 35 set to the required relative rotational position ranges from the position where the relative angle ANG is "- α °" to the position where the relative angle ANG is "β °". Therefore, the relative rotational position of the valve body 35 set to the target relative rotational position at this time also ranges from the position where the relative angle ANG is "- α °" to the position where the relative angle ANG is "β °".

In contrast, in the case where at least one of the conditions (i) to (vi) is also satisfied, when the value of the required relative-rotation position is equal to or greater than "S °" (no in S190), the value of the required relative-rotation position is directly set to the value of the target relative-rotation position in step S180, and then the process proceeds to step S210. On the other hand, when at least one of the conditions (i) to (vi) is satisfied and the value of the required relative-rotation position is smaller than "S °" (yes in S190), the "S °" is set to the value of the target relative-rotation position in step S200, and then the process proceeds to step S210. When at least one of the conditions (i) to (vi) is satisfied in this way, the relative rotational position of the valve body 35 set to the target relative rotational position ranges from the position where the relative angle ANG is "s °" to the position where the relative angle ANG is "β °".

In the case where at least one of the conditions (i) to (vi) is satisfied in this way, the value of the relative-rotation position on the forward side with respect to the position where the relative angle ANG is "s °" is set to the value of the target relative-rotation position. As shown in fig. 6B, "epsilon °" is a relative angle ANG at the end on the negative side of the retreat operation range, which is set in advance to the relative rotation range of the valve body 35, including the relative rotation position of the valve body 35 at which the relative angle ANG as the maximum pressure-resistant relative rotation position is "γ °". Thus, when at least one of the conditions (i) to (vi) is satisfied, the relative angle ANG in the backoff operation range is set to the value of the target relative rotational position.

It should be noted herein that the control range of the valve body 35 is defined as a range of the relative rotation position of the valve body 35 set to the target relative rotation position. In the case where none of the conditions (i) to (vi) is satisfied, the control range of the valve body 35 is from the position where the relative angle ANG is "- α °" to the position where the relative angle ANG is "β °". In contrast, when at least one of the conditions (i) to (vi) is satisfied, the control range is narrowed to a retreat operation range, which includes the maximum pressure-resistant relative rotation position, set in advance as the relative rotation position range of the valve body 35.

When the process proceeds to step S210 after the target relative-rotation position is set in step S180 or step S200 as described above, in step S210, the value of the pressure-resistant limit rotation speed NL at the relative angle ANG set to the value of the target relative-rotation position is calculated based on the map M stored in the memory 52. Further, subsequently in step S220, it is determined whether the calculated pressure resistance limit rotation speed NL is lower than the current engine rotation speed NE. Then, if the pressure resistance limit rotation speed NL at the target relative-rotation position is equal to or higher than the current engine rotation speed NE (no), the process directly proceeds to step S240. In contrast, if the pressure resistance limit rotation speed NL at the target relative-rotation position is lower than the current engine rotation speed NE (yes), the pressure resistance limit rotation speed is equal to or higher than the current engine rotation speed NE in step S230, and the relative angle ANG in the retreat operation range is obtained based on the map M. Then, after the obtained relative angle ANG is further reset to the value of the target relative-rotation position in step S230, the process proceeds to step S240.

When the process proceeds to step S240, the value of the relative angle ANG at the relative rotational position at which the valve body 35 is currently located is acquired in step S240. Incidentally, in the following description, the relative angle ANG at the relative rotation position at which the valve body 35 is currently located will be referred to as a current relative angle. Incidentally, the current relative angle is obtained from the detection result of the rotation angle of the motor 37 by the rotation angle sensor 123.

Subsequently in step S250, the withstand voltage limit rotation speed NN at the current relative angle is calculated based on the map M stored in the memory 52. Then, subsequently in step S260, it is determined whether the current engine rotation speed NE is higher than the pressure resistance limit rotation speed NN at the calculated current relative angle. If the pressure resistance limit rotation speed NN is higher than the current engine rotation speed NE (yes), an operation of incrementing the value of the counter COUNT is performed in step S270, and then the process proceeds to step S290. On the other hand, if the withstand voltage limit rotation speed NN is equal to or lower than the current engine rotation speed NE (no in S260), an operation of clearing the value of the counter COUNT to "0" is performed in step S280, and then the processing of the present routine is terminated. The value of the counter COUNT thus operated represents the duration for which the pressure resistance limit rotation speed NN has remained higher than the current engine rotation speed NE.

When the process proceeds to step S290, it is determined in step S290 whether the value of the counter COUNT is equal to or greater than a specified allowable time determination value. If the value of the counter COUNT at this time is smaller than the allowable time determination value (no), the processing of the present routine regarding the current loop is immediately terminated. On the other hand, if the value of the counter COUNT at this time is equal to or greater than the allowable time determination value (yes), a request for lowering the engine torque is output to the engine control unit 55, and then the processing of the present routine with respect to the current cycle is terminated. Incidentally, the engine control unit 55 reduces the torque of the engine 10 in accordance with the input of the request for reducing the engine torque.

Incidentally, the control unit 50 executes power supply control of the electric motor 13 to relatively rotate the valve body 35 toward the target relative-rotation position set in the present routine. That is, when the current relative rotation position of the valve body 35 is located in the negative direction of the target rotation position, the control unit 50 supplies power to the motor 37 so that the rotation direction of the motor 37 coincides with the direction of the relative rotation of the valve body 35 in the positive direction. Further, when the current relative rotation position of the valve body 35 is located in the positive direction of the target rotation position, the control unit 50 supplies power to the motor 37 so that the rotation direction of the motor 37 coincides with the direction of the relative rotation of the valve body 35 in the negative direction. Then, when the current relative-rotation position of the valve body 35 coincides with the target relative-rotation position, the control unit 50 stops supplying power to the motor 37.

The operation and effect of the present embodiment will be described. In the engine cooling device according to the present embodiment equipped with the mechanical water pump 22 as described above, the value of the required relative-rotation position is set in accordance with the warming-and-cooling requirements of the engine 10 and ATF and the requirement of air-conditioning warming, and is normally set directly to the value of the target relative-rotation position. Then, the power supply control of the motor 37 is performed to bring the relative rotational position of the valve body 35 to the set target relative rotational position.

On the other hand, in the engine cooling device according to the present embodiment that employs the mechanical water pump 22 that operates in response to the rotation of the engine 10, the discharge pressure of the coolant in the water pump 22 rises as the engine speed NE rises. Further, when the valve body 35 of the flow control valve 26 is located at a specific relative rotational position at this time, the hydraulic pressure of the circulation circuit 21 may become higher than the pressure-resistant limit.

In contrast, when the engine speed NE rises, the engine cooling device according to the present embodiment executes the protection control for suppressing the hydraulic pressure of the circulation circuit 21 from rising above the pressure-resistant limit by resetting the relative rotational position at which the pressure-resistant limit rotational speed is equal to or higher than the current engine speed NE to the value of the target relative rotational position.

Further, in the present embodiment, when at least one of the conditions (i) to (vi) is satisfied, the retraction control for resetting the relative rotational position within the retraction operation range of the relative rotational position range of the valve body 35, which is set in advance to include the maximum pressure-resistant relative angle, to the target relative rotational position is performed. Thus, the relative rotational position of the valve body 35 becomes a relative rotational position within the retreat operation range, that is, a range not too far from the maximum withstand voltage relative rotational position.

Incidentally, even in the case where the above-described evacuation control and protection control are executed, when the engine rotation speed NE is kept higher than the withstand voltage limit rotation speed, the request for reduction of the engine torque is output to the engine control unit 55, and the engine rotation speed NE is suppressed from rising due to a reduction of the engine torque corresponding to the request.

The engine cooling device according to the present embodiment described above can exert the following effects. (1) In the present embodiment, the above-described backoff control is executed when the supply voltage of the in-vehicle power supply 53 has dropped. When the supply voltage of the vehicle-mounted power supply 53 decreases, the speed at which the relative rotational position of the valve body 35 is changed by the motor 37 decreases, and the time required to change the relative rotational position of the valve body 35 in the protection control becomes long. In this regard, when the above-described retraction control is executed before the protection control is executed, the amount of change in the relative rotational position of the valve body 35 does not increase beyond a certain value in the case where the protection control is executed in response to a rise in the engine rotational speed NE thereafter. Therefore, even when the supply voltage of the in-vehicle power supply 53 decreases to cause a decrease in the speed of changing the relative rotational position of the valve body 35, the time required to change the relative rotational position of the valve body 35 in the protection control is unlikely to become long. Thus, even in the case where the supply voltage of the vehicle-mounted power supply 53 has decreased, when the engine speed NE increases, the time required to suppress the increase in the hydraulic pressure of the circulation circuit 21 is unlikely to become long.

(2) Information on the pressure-resistant limit rotation speed at each relative rotational position of the valve body 35 is stored in advance in the memory 52. In the protection control, the relative rotational position of the valve body 35 at which the withstand voltage limit rotational speed obtained based on this information is higher than the current engine rotational speed NE is set as the target relative rotational position. Therefore, in the protection control, an appropriate target relative-rotation position at which the withstand voltage limit rotation speed is equal to or higher than the engine rotation speed NE can be set.

(3) Determining whether engine torque needs to be reduced by: when the current engine speed NE has remained higher than the pressure-resistant limit speed at the current relative rotational position of the valve body 35 for the specified time or more, it is determined that the engine torque needs to be reduced. Therefore, when the rise of the hydraulic pressure cannot be sufficiently suppressed by the protection control, the rise of the hydraulic pressure can be suppressed by making a request for reducing the engine torque and suppressing the rise of the engine rotation speed NE.

(4) Immediately after the start of the engine, the supply voltage of the vehicle-mounted power supply 53 may temporarily drop due to the power consumption at the start of the engine. Such a supply voltage drop of the vehicle-mounted power supply 53 immediately after the engine start is stopped in a short time, so it is not generally necessary to execute the backoff control in this case as a countermeasure against the supply voltage drop. In contrast, according to the present embodiment, when the elapsed time after the engine start is shorter than the specified time T0, a higher voltage is set to the voltage drop determination value than in the case where the elapsed time is equal to or longer than the specified time T0, so that it is less likely that the backoff control is unnecessarily executed.

(5) When the coolant temperature is low, the viscosity of the coolant is high, and the flow resistance of the coolant applied to the valve body 35 when changing the relative rotational position of the valve body 35 is also high. Therefore, even when the temperature of the coolant is low, the speed at which the relative rotational position of the valve body 35 is changed by the motor 37 is low. In contrast, according to the present embodiment, the backoff control is executed even when the coolant temperature is equal to or lower than the specified low coolant temperature determination value. Therefore, even in the case where the speed at which the relative rotational position of the valve body 35 is changed by the electric motor 37 has decreased due to a low coolant temperature, when the engine speed NE increases, it is unlikely that the increase in the hydraulic pressure of the circulation circuit 21 cannot be sufficiently suppressed.

(6) The backoff control is executed even when the engine speed NE is high to a certain degree and the protection control may need to be executed in a short time. Therefore, when the engine speed NE increases, the increase in the hydraulic pressure of the circulation circuit 21 can be suppressed quickly.

(7) When the shift range for parking or the shift range for neutral is set, the power transmission between the engine 10 and the wheels is cut off by the automatic transmission 241, and the portion of the power transmission system of the vehicle on the wheel side with respect to the automatic transmission 241 is disconnected from the engine 10, so the rotational load of the engine 10 is reduced. Therefore, when the shift range for parking or the shift range for neutral is set, the speed at which the engine rotation speed NE increases tends to be higher than when the shift range for running is set without the power transmission being cut off. In contrast, according to the present embodiment, when the shift range of the automatic transmission 241 is set to the shift range for parking or the shift range for neutral, the retract control is executed at a lower engine speed NE than when the shift range of the automatic transmission 241 is set to the shift range for traveling. Therefore, even in the case where the power transmission between the engine 10 and the wheels is cut off by the automatic transmission 241 and the speed at which the engine rotation speed NE rises tends to be high, when the engine rotation speed NE rises, it is easy to suppress the rise in the hydraulic pressure of the circulation circuit.

(8) In the engine 10 mounted on the vehicle, while the vehicle is coasting with the engine 10 being dragged along with the rotation of the wheels, the engine speed may rapidly increase through a downshift or the like. In contrast, according to the present embodiment, the retraction control is executed even while the vehicle is coasting. Therefore, even when the engine speed NE rapidly rises while the vehicle is coasting, it is easy to suppress the rise in the hydraulic pressure of the circulation circuit 21.

Incidentally, according to the present embodiment, the operation position of the valve body 35 in the flow control valve 26 is represented by the rotational position of the valve body 35 with respect to the housing 31. In the present embodiment, the target relative rotation position corresponds to the target running position, and the maximum pressure-resistant relative rotation position corresponds to the maximum pressure-resistant running position.

The present embodiment may be performed after being modified as follows. The present embodiment and the following modifications may be performed in combination with each other within a range where technical contradictions do not occur. In the above-described embodiment, information on the pressure resistance limit rotation speed at each relative rotation position of the valve body 35 is stored in the recording device 42 as the map M, and the target relative rotation position in the protection control is calculated based on the stored information. However, the target relative-rotation position in the protection control may be calculated according to another method without storing the above-described information. For example, the target relative-rotation position in the protection control may be fixed to the maximum withstand-voltage operating position or the like.

In the above-described embodiment, when the current engine rotation speed NE has remained higher than the pressure-resistant limit rotation speed at the current relative rotation position of the valve body 35 for the specified time or more, it is determined that the engine torque needs to be reduced, and a request for reducing the engine torque is output to the engine control unit 55. The determination as to the necessity of reducing the engine torque and the output for the request for reduction may be omitted.

In the above-described embodiment, when the gear range of the automatic transmission 241 is set to the gear range for parking or the gear range for neutral to cut off the power transmission between the engine 10 and the wheels, the limp-home control is executed by the lower engine speed NE than when the gear range for running is set without the power transmission being cut off. In a vehicle employing a manual transmission, when a clutch provided between an engine and the manual transmission is disengaged or when the manual transmission is in a neutral state, power transmission between the engine and wheels is cut off. Therefore, in the vehicle employing the manual transmission, when at least one of the condition (vii) that the clutch is disconnected and the condition (viii) that the manual transmission is in the neutral state is satisfied, the retract control can be performed by the lower engine speed NE than when neither of the conditions (vii) and (viii) is satisfied.

In the above-described embodiment, when the power transmission between the engine and the wheels is cut off, the limp-home control is executed with the lower engine speed NE than when the power transmission between the engine and the wheels is not cut off. However, the back-off control may be executed when the engine speed NE becomes equal to or higher than a certain speed, regardless of whether the power transmission is cut off.

In the above-described embodiment, the low voltage determination value is changed in accordance with the elapsed time after the engine is started. However, the fixed value may be set to the low voltage determination value regardless of the elapsed time after the engine start.

When at least one of the conditions (i) to (vi) is satisfied, backoff control is performed. However, one or more of conditions (i), (ii), (iii), and (vi) may be omitted.

The number of output ports of the flow control valve 26 and the number of coolant passages in the circulation circuit to the output ports can be changed as appropriate. The flow control valve 26 employed in the above-described embodiment has the valve body 35 that rotates relative to the housing 31, and the flow passage area of the coolant at the output port is changed in accordance with the relative rotational position of the valve body 35. However, a flow control valve having a valve body that performs an operation other than relative rotation (such as reciprocating linear motion) may be employed.

A flow rate control valve that employs an electric actuator other than the motor 37, for example, an electromagnetic solenoid as an actuator for driving the valve body 35, may be employed.