JP6181119B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling device.

  Conventionally, an engine cooling device provided with a water pump and an electromagnetic valve is known (see, for example, Patent Document 1).

  In Patent Document 1, an electric pump that discharges a refrigerant for cooling the engine, a first flow path and a second flow path for circulating cooling water to the engine via a radiator, and without passing through the radiator. A third flow path for circulating cooling water to the engine, a valve provided in the third flow path for switching presence / absence of refrigerant flow in the third flow path, and an electric pump and a controller for controlling the valve. An engine cooling system is disclosed. The valve of this engine cooling system includes a valve body, a valve seat, a biasing member that biases the valve body toward the valve seat, and a solenoid that strengthens the contact between the valve seat and the valve body when energized. Yes. Thereby, when closing the valve of the third flow path, the control unit brings the valve body and the valve seat into contact with each other by energizing the solenoid by the energizing force of the energizing member and the attraction force by the solenoid. It is configured as follows. In addition, when the control unit opens the valve in the closed state of the third flow path, the energizing force of the energizing member is stopped by stopping energization to the solenoid and circulating the refrigerant by the electric pump. The valve body and the valve seat are configured to be separated from each other.

  Here, in the engine cooling system described in Patent Document 1, when the valve of the third flow path that has been opened is closed, the control unit stops the electric pump and stops the refrigerant flow. Thereafter, the solenoid of the valve in the third flow path is energized.

JP 2013-108398 A

  However, in the engine cooling system described in Patent Document 1, the electric pump is stopped to close the refrigerant in order to close the valve of the third flow path for circulating the cooling water to the engine without passing through the radiator. Since it is configured to stop the circulation, there is an inconvenience that the refrigerant is not circulated in the engine cooling system during the period in which the electric pump is stopped. For this reason, since the engine is hardly cooled during the period when the electric pump is stopped, there is a problem that the driving engine becomes high temperature.

  The present invention has been made in order to solve the above-described problems, and one object of the present invention is to close an electromagnetic valve of a cooling water passage for circulating cooling water through an engine without going through a radiator. An object of the present invention is to provide an engine cooling device capable of suppressing the temperature of a driving engine from becoming high when the engine is in a state.

In order to achieve the above object, an engine cooling apparatus according to one aspect of the present invention includes a water pump capable of controlling a flow rate of cooling water for cooling an engine, and a first circulating water to the engine via a radiator. A cooling water flow path, a second cooling water flow path for allowing the cooling water to flow through the engine without going through the radiator, and a second cooling water flow path, including the valve body, and moving the valve body by an electrical suction force Thus, when the solenoid valve for opening and closing and the solenoid valve for the second cooling water flow path are closed, the water pump is driven so as to reduce the flow rate of the cooling water, so that the cooling water whose flow rate is reduced is In such a state that the valve body is moved in the valve closing direction by at least an electric suction force in the circulating state, the electromagnetic valve is closed to perform control for blocking the circulation of the cooling water in the second cooling water channel. Comprising a part, a control unit at least based on the hydraulic resistance of the cooling water to obtain a closed maximum possible rotational speed of the water pump to drive the water pump at a rotational speed below the valve closing possible maximum rotation speed By moving the valve body in the above state, control is performed to close the electromagnetic valve of the second cooling water flow path .

In the engine cooling device according to one aspect of the present invention, as described above, when the electromagnetic valve of the second cooling water flow path not passing through the radiator is closed, the electromagnetic water is circulated in the state where the cooling water having a reduced flow rate is circulated. A control unit is provided that performs control to close the valve and block the flow of the cooling water in the second cooling water flow path. As a result, even if the electromagnetic valve of the second cooling water flow path that does not pass through the radiator is closed by closing the electromagnetic valve in a state in which the cooling water is circulated, the inside of the engine cooling device (via the radiator) Since the cooling water can be circulated through the first cooling water flow path), it is possible to prevent the cooling water from being circulated with respect to the engine. As a result, when closing the solenoid valve of the second cooling water flow path that does not pass through the radiator, the engine can be continuously cooled by the circulating cooling water, so that the temperature of the driving engine is prevented from becoming high. Can do. Further, when the valve body is moved in the valve closing direction, the force for moving the valve body in the valve closing direction against the circulating water is increased by circulating the cooling water whose flow rate is reduced. Therefore, it is possible to suppress the necessity of a large electrical attraction force in the electromagnetic valve. Thereby, it is possible to suppress an increase in electric power necessary for closing the solenoid valve, and it is possible to suppress an increase in size of the solenoid valve in order to generate a large electrical attractive force. The control unit obtains the maximum possible rotation speed of the water pump based on at least the flow resistance of the cooling water, and operates the water pump at a rotation speed equal to or lower than the maximum possible rotation speed. By moving the body, control is performed to close the electromagnetic valve of the second cooling water flow path. As a result, the cooling water is circulated in the engine cooling device (the first cooling water flow path via the radiator) by moving the valve body while driving the water pump at a rotation speed equal to or lower than the maximum possible rotation speed. Thus, the electromagnetic valve of the second cooling water passage that does not pass through the radiator can be reliably closed. In the engine cooling device, the differential pressure between the upstream and downstream pressures of the solenoid valve changes according to the flow resistance of the cooling water, and as a result, the maximum possible rotation speed of the water pump can be closed. Change. Therefore, by obtaining the maximum possible rotation speed of the water pump based on the cooling water flow resistance related to the maximum possible rotation speed of the water pump, it is possible to obtain an accurate maximum possible rotation speed of the water pump. Based on this, the solenoid valve can be closed more reliably.

  In the engine cooling device according to the above aspect, the electromagnetic valve preferably further includes an urging member that urges the valve body in the valve closing direction, and the urging force of the urging member and the electric force are driven while driving the water pump. The valve body is configured to move in the valve closing direction by a suction force. With this configuration, the valve body can be easily moved in the valve closing direction against the circulating cooling water by the amount of the urging force by the urging member. Therefore, the second cooling water flow path that does not pass through the radiator is provided. There is no need to greatly reduce the flow rate of the cooling water in order to close the solenoid valve. Thereby, even if it is in the state where the flow volume of cooling water was reduced, cooling water can fully be circulated in the engine cooling device (the 1st cooling water flow path which goes via a radiator).

In the engine cooling device according to the above one aspect , preferably, the engine cooling device further includes a thermostat that is provided in the first cooling water flow path, and whose opening degree changes based on the temperature of the cooling water, and the control unit is based on the opening degree of the thermostat. The cooling water flow resistance is estimated. Here, in the engine cooling device, the flow rate of the cooling water in the first cooling water flow path changes based on the opening of the thermostat, and as a result, the flow resistance of the cooling water changes. Therefore, by estimating the flow resistance of the cooling water based on the opening of the thermostat, a more accurate maximum water pump closing speed that can be closed based on the flow resistance of the cooling water estimated appropriately. Can be acquired. Further, when the thermostat is in the open state, the cooling water flows through the first cooling water flow path and the cooling water flows through the engine even when the flow of the cooling water in the second cooling water flow path is interrupted. In addition, the coolant having a high temperature can be effectively cooled by circulating the coolant through the radiator of the first coolant channel. Further, when the thermostat is in the closed state, it is not preferable to cool the engine being driven by the cooling water having a low temperature, such as when the engine is warming up. Therefore, the cooling water is supplied to the radiator of the first cooling water passage. By not circulating the engine, it is possible to suppress the cooling water from being cooled in the radiator and to suppress the engine from being excessively cooled.

  In the engine cooling apparatus according to the above aspect, the water pump is preferably an electric water pump including a sensorless motor. Here, in the sensorless motor, the initial position of the rotor of the sensorless motor becomes unclear when the water pump (sensorless motor) is stopped because the sensor is not provided. For this reason, in the sensorless motor, once the sensorless motor is stopped, it is necessary to detect the initial position of the rotor in order to drive the sensorless motor correctly. As a result, when driving a sensorless motor in a stopped state, it is necessary to start driving to detect the initial position of the rotor, and as a result, extra time for starting driving is required. Therefore, the period during which the coolant is not distributed to the engine is further prolonged. On the other hand, in the present invention, as described above, when the solenoid valve is closed in the engine cooling device, the water pump is driven to reduce the flow rate of the cooling water, so that the water pump includes the sensorless motor. Even in the case of a water pump of the type, no extra time such as the time for starting drive occurs. Thereby, the configuration of the present invention is particularly suitable when the water pump includes a sensorless motor.

  In the engine cooling device according to the above aspect, preferably, the control unit is configured to perform control to increase the flow rate of the cooling water by the water pump after the closing of the electromagnetic valve of the second cooling water flow path. Yes. If comprised in this way, cooling of the engine etc. by cooling water, heat recovery from cooling water, etc. can be performed effectively by increasing the flow volume of cooling water after completion of valve closing of an electromagnetic valve.

  In addition, in the engine cooling device of this application, the following other structures are also conceivable.

(Additional item 1)
That is, the engine cooling device further includes a first heat exchanger that is disposed in the second cooling water flow path and in which heat is exchanged between the cooling water.

(Appendix 2)
Further, in the configuration further including the first heat exchanger, the cooling water is provided in parallel with the second cooling water flow path and is disposed in the third cooling water flow path through which the cooling water flows, and the third cooling water flow path. A second heat exchanger to be replaced.

(Additional Item 3)
Further, in the configuration in which the valve body is moved in a state where the water pump is driven at a rotation speed equal to or less than the maximum valve-closing speed, the control unit is configured to control a cooling water maximum discharge pressure in the water pump and the cooling water. The water pump is configured to obtain the maximum possible rotation speed of the water pump based on the water flow resistance.

(Appendix 4)
Further, in the configuration in which the flow rate of the cooling water is increased after completion of the closing of the electromagnetic valve of the second cooling water flow path, the control unit determines the period until the closing of the electromagnetic valve according to the cooling water flow resistance. It sets so that it may control to increase the flow volume of cooling water with a water pump after progress of the period until the valve closing completion of the set solenoid valve.

(Appendix 5)
Moreover, in the structure which estimates the cooling water flow resistance based on the opening degree of the thermostat in the first cooling water flow path, the thermostat is arranged on the upstream side of the engine, and is arranged on the downstream side of the engine. A temperature detection unit that detects a downstream temperature of the cooling water on the downstream side of the engine, and the control unit is configured to detect the upstream side of the engine based on the downstream temperature detected by the temperature detection unit and the cooling loss in the engine. The upstream temperature of the cooling water on the side is estimated, and the opening degree of the thermostat is estimated based on the upstream temperature.

  ADVANTAGE OF THE INVENTION According to this invention, when making the solenoid valve of the cooling water flow path which distribute | circulates cooling water to an engine without going through a radiator into a valve closing state, it can suppress that the engine in drive becomes high temperature.

It is the schematic diagram which showed the engine cooling device and engine by one Embodiment of this invention. It is the figure which showed the opening degree characteristic map by one Embodiment of this invention. It is the figure which showed the water flow resistance map by one Embodiment of this invention. It is sectional drawing which showed the structure of FSV of the engine cooling device by one Embodiment of this invention. It is the figure which showed the timing chart at the time of FSV valve closing by one Embodiment of this invention. It is the figure which showed the timing chart at the time of FSV valve closing by a prior art example. It is the flowchart which showed the valve closing control flow of FSV of the engine cooling device by one Embodiment of this invention. It is the figure which showed the cooling loss map by one Embodiment of this invention. It is the figure which showed the rotation speed map by one Embodiment of this invention. It is the figure which showed the valve closing time map by one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Configuration of engine cooling device>
First, with reference to FIGS. 1-4, the structure of the engine cooling device 100 by one Embodiment of this invention is demonstrated.

  An engine cooling device 100 according to an embodiment of the present invention is mounted on a vehicle (not shown), supplies cooling water to an engine 101 mounted on the vehicle, cools the engine 101, and warms it with heat from the engine 101 or the like. The cooling water is cooled by the radiator 2 and the heat is recovered from the heated cooling water by using the heater core 3 or the like. The cooling water means a liquid such as water for cooling the engine 101.

  As shown in FIG. 1, the engine cooling device 100 includes an electric water pump (electric W / P) 1, a radiator 2, a heater core 3, an oil cooler 4, a thermostat 5, and a flow shutting valve (FSV) 6. And. The engine cooling device 100 is configured to be controlled by an engine control unit (ECU) 7 that controls the rotational speed of the engine 101 and the like. The electric W / P1 is an example of the “water pump” in the claims, and the FSV 6 is an example of the “solenoid valve” in the claims. The ECU 7 is an example of a “control unit” in the claims.

  Further, the engine cooling device 100 is configured such that cooling water circulates and circulates through the cooling water circulation passage 8. The cooling water circulation channel 8 includes cooling water channels 8a, 8b, and 8c. The cooling water channels 8a and 8b are examples of the “first cooling water channel” and the “second cooling water channel” in the claims, respectively.

  An engine 101, an electric W / P1, a radiator 2, and a thermostat 5 are disposed in the cooling water flow path 8a. The electric W / P 1 is disposed upstream of the engine 101, the radiator 2 is disposed downstream of the engine 101, and the thermostat 5 is disposed downstream of the radiator 2. That is, the cooling water flow path 8 a is configured to circulate cooling water to the engine 101 via the radiator 2. In addition, the “upstream side” and “downstream side” in the present embodiment mean the upstream side and the downstream side in the flow direction of the cooling water (double chain line in FIG. 1), respectively.

  The cooling water flow paths 8b and 8c branch off at the branch point 9a on the downstream side of the engine 101 in the cooling water flow path 8a and on the upstream side of the radiator 2, and on the downstream side of the thermostat 5 in the cooling water flow path 8a, and Both merge at the junction 9b on the upstream side of the electric W / P1. That is, the cooling water channel 8b and the cooling water channel 8c are provided in parallel.

  The heater core 3 and the FSV 6 are disposed in the cooling water flow path 8b. In other words, the cooling water flow path 8b is a cooling water flow path provided with the FSV 6, and can join the cooling water flow path 8a at the junction 9b without passing through the radiator 2 to cause the engine 101 to circulate the cooling water. It is configured as possible. The heater core 3 is arranged on the branch point 9a side, and the FSV 6 is arranged on the junction point 9b side.

  An oil cooler 4 is disposed in the cooling water passage 8c. That is, the cooling water flow path 8c is configured to be able to circulate cooling water through the engine 101 by joining the cooling water flow path 8a at the junction 9b without passing through the radiator 2.

  The electric W / P1 is an electric type, and is configured such that the flow rate of the cooling water discharged is controlled based on the control of the ECU 7. Further, the electric W / P1 is configured to suck the cooling water from the opposite side of the engine 101 in the cooling water flow path 8a and to discharge the cooling water toward the engine 101 side. The electric W / P1 is a centrifugal pump excellent in discharge efficiency.

  The electric W / P1 that is a centrifugal pump includes a brushless / sensorless motor 1a for rotating an impeller (not shown). As a result, the electric W / P1 can be driven independently of the engine 101. The “brushless motor” is a motor that is driven by controlling the switching of the current direction by electrical control without using the brush that contacts and slides or the commutator that switches the direction of the current. Thus, by using the brushless / sensorless motor 1a, unlike the case of using a motor having a brush, there is no brush wear, so that the electric W / P1 can be extended in life. The brushless / sensorless motor 1a is not provided with a sensor (such as a Hall element) for detecting the position of the rotor (permanent magnet). For this reason, the brushless / sensorless motor 1a is configured to detect the initial position of the rotor based on a change in electromotive force generated by the rotation of the rotor. The brushless / sensorless motor 1a is an example of the “sensorless motor” in the claims.

  Further, the electric W / P1 is configured to be able to transmit the rotational speed (the rotational speed of the impeller) of the brushless / sensorless motor 1a to the ECU 7 as pump rotational speed information.

  The radiator 2 is configured such that heat exchange is performed between the cooling water flowing through the radiator 2 and the traveling wind (air). Thereby, the cooling water which distribute | circulates the radiator 2 is cooled.

  The heater core 3 is configured to be blown by a fan (not shown) based on a signal from the ECU 6 when a heating operation is performed in a vehicle (not shown). As a result, heat is exchanged between the cooling water flowing through the heater core 3 (cooling water flow path 8b) and the wind (air), the cooling water is cooled, and warm air is supplied into the vehicle. Is heated.

  In the oil cooler 4, heat exchange is performed between cooling water flowing through the oil cooler 4 (cooling water flow path 8c) and oil used for lubrication of a sliding portion (not shown) of the engine 101, and the like. The cooling water is warmed and the oil is cooled.

  The thermostat 5 is configured such that the opening degree changes based on the temperature of the cooling water. Accordingly, the thermostat 5 has a function of switching whether or not the cooling water is circulated through the radiator 2 of the cooling water flow path 8a and a function of adjusting a flow rate of the cooling water when the cooling water is circulated through the radiator 2. ing.

  Specifically, as shown in FIG. 2, the thermostat 5 is completely closed (opened) when the temperature of the cooling water flowing through the thermostat 5 is lower than the first temperature (= about 80 ° C.). Therefore, the cooling water is not allowed to flow through the radiator 2 of the cooling water flow path 8a. At this time, the cooling water flows (circulates) from the branch point 9a through the cooling water flow path 8b (in the case of the FSV valve opening state) and the cooling water flow path 8c, and returns to the electric W / P1 again from the junction point 9b. In the radiator 2, the cooling water is not cooled. In addition, when the temperature of the cooling water is equal to or higher than the first temperature, the thermostat 5 adjusts the flow rate of the cooling water flowing through the thermostat 5 based on the opening degree that changes according to the temperature of the cooling water. It is configured. At this time, the cooling water whose flow rate is adjusted according to the opening degree flows through the radiator 2 of the cooling water passage 8a, and a part of the cooling water is cooled in the radiator 2, and the remaining cooling water is supplied to the cooling water passage. 8b (when in the FSV valve open state) and the cooling water flow path 8c are circulated (circulated) so as to return to the electric W / P1 again from the junction 9b. Further, the thermostat 5 is configured to be completely opened (the opening degree is 100%) when the temperature of the cooling water is equal to or higher than the second temperature. At this time, the cooling water flows (circulates) through the cooling water flow path 8a, the cooling water flow path 8b (in the case of the FSV valve opening state) and the cooling water flow path 8c to return to the electric W / P1 again. Is cooled in the radiator 2.

  As a result, in the engine cooling device 100, the flow path of the cooling water and the flow rate of each flow path change according to the valve opening state of the thermostat 5, so the engine cooling device 100 ( The resistance (water resistance) of the cooling water flowing through the cooling water circulation channel 8) is changed. In addition, as shown in FIG. 3, when the opening degree of the thermostat 5 is small, a water flow resistance becomes large with respect to the flow rate of the cooling water, and when the opening degree of the thermostat 5 is large, the flow rate of the cooling water is increased. On the other hand, resistance to water flow is reduced. Further, the water flow resistance varies depending on the structure of the engine cooling device 100 such as the diameter of the cooling water circulation flow path 8, and is thus obtained for each engine cooling device 100 having a different structure.

  The FSV 6 is a valve member that is opened and closed by an electric suction force, and has a function of blocking the flow of the cooling water in the cooling water flow path 8b by closing the valve. As shown in FIG. 4, the FSV 6 includes a cylindrical housing 61, and a valve body 62, a valve seat 63, a biasing member 64, and a solenoid 65 disposed in the housing 61. The housing 61 extends in a direction substantially orthogonal to the inflow path 61a into which the cooling water flows from the heater core 3 side and the direction (Z direction) in which the inflow path 61a extends, and the outflow from which the cooling water flows out to the electric W / P1 side. It has a passage 61b and a valve body accommodating portion 61c that connects the inflow passage 61a and the outflow passage 61b. A valve body 62 and a biasing member 64 are housed in the valve body housing portion 61c.

  The solenoid 65 is composed of an annular member, and includes a body 65a made of a magnetic material, a bobbin 65b disposed inside the body 65a, and a winding 65c wound around the bobbin 65b to generate a magnetic field by energization. It has. Further, the solenoid 65 has a housing in which the inside of the solenoid 65 forms an inflow passage 61 a and the surface of the solenoid 65 on the valve body accommodating portion 61 c side (Z1 side) is a valve seat 63 that contacts the valve body 62. 61.

  The valve body 62 is formed in a columnar shape having an inverted T-shaped cross section, and is configured to be movable in the Z direction. The valve body 62 is formed of a magnetic material such as iron. Thus, when the solenoid 65 is excited by energizing the winding 65c of the solenoid 65, the valve body 62 and the solenoid 65 are moved in the valve closing direction (Z2 direction) toward the valve seat 63. An electric attractive force is generated between the two. Further, the urging member 64 is constituted by a coil spring, and is disposed in the valve body accommodating portion 61c in a state in which the valve body 62 is urged in the valve closing direction.

  As a result, the valve element 62 moves in the valve closing direction (Z2 direction) by the urging force by the urging member 64 and the electric suction force by the energized solenoid 65, and comes into contact with the valve seat 63. The FSV 6 is configured to be in a closed state. Further, the force applied to the valve body 62 from the Z2 side based on the pressure of the cooling water in the inflow passage 61a and the pressure of the cooling water in the outflow passage 61b and the valve body housing portion 61c in a state where the solenoid 65 is de-energized. When the pressure force exceeds the urging force, the valve element 62 is moved in the valve opening direction (Z1 direction), and the FSV 6 is switched from the valve closing state to the valve opening state.

  Here, the urging force of the urging member 64 and the attracting force by the solenoid 65 are both small. In addition, the area of the valve element 62 to which pressure from the Z2 side is applied in the valve open state (area of the region surrounded by the double chain line in the valve open state diagram of FIG. 4) S1 is the pressure from the Z2 side in the valve closed state. Is larger than the area of the valve body 62 (area of a region surrounded by a double chain line in the valve closed state in FIG. 4) S2. As a result, when the FSV 6 is in a normal driving state in which the electric W / P1 is driven at a rotational speed that discharges cooling water having a large flow rate such as about 2000 rpm in the valve open state, the urging force of the urging member 64 The pressure by the cooling water cannot be resisted only by the suction force by the solenoid 65. Therefore, in the FSV 6, when the cooling water is circulated at a normal flow rate in the valve open state, it is difficult to switch from the valve open state to the valve closed state.

  Therefore, in the engine cooling device 100 of the present embodiment, the ECU 7 drives the electric W / P 1 at a low speed, for example, at a low rotation speed of about 700 rpm or less when the FSV 6 of the cooling water passage 8b is switched from the open state to the closed state. Thus, the solenoid 65 is energized while the flow rate of the cooling water discharged from the electric W / P1 is decreased from the normal flow rate. As a result, in the engine cooling device 100, the valve element 62 is moved in the valve closing direction by the urging force of the urging member 64 and the electric suction force while driving the electric W / P1, and the FSV 6 of the cooling water flow path 8b is moved. Is closed, and as a result, the flow of the cooling water in the cooling water flow path 8b is blocked. On the other hand, even during the valve closing operation of the FSV 6 and after completion of the valve closing, the cooling water flows through the cooling water flow path 8a and the cooling water flow path 8c when the thermostat 5 is opened, other than the cooling water flow path 8b. Thereby, it is possible to distribute the cooling water to the engine 101. Details of the valve closing control of the FSV 6 of the ECU 7 will be described later.

  Further, when the FSV 6 is closed and the flow of the cooling water to the heater core 3 is blocked, the cooling water heated by the engine 101 is blocked from flowing through the heater core 3 (cooling water flow path 8b) and The cooling of the oil in the oil cooler 4 is performed by increasing the flow rate of the cooling water flowing through the oil cooler 4 (cooling water flow path 8c) by blocking the flow of the cooling water in the heater core 3 There are cases where efficiency is improved. Whether the FSV 6 is closed and the flow of the cooling water to the heater core 3 is cut off is determined by the ECU 7.

  As shown in FIG. 1, the engine cooling device 100 is provided with a water temperature sensor 7a that detects a downstream temperature (outlet water temperature To) of the cooling water on the downstream side of the engine 101 in the cooling water flow path 8a. The water temperature sensor 7a is configured to transmit information related to the outlet water temperature To (exit water temperature information) to the ECU 7.

<Comparison between this embodiment and conventional example by timing chart when FSV is closed>
Next, referring to FIG. 1 and FIGS. 4 to 6, a comparison between a timing chart when the FSV 6 is closed in one embodiment of the present invention and a timing chart when the FSV is closed in the conventional example will be described. .

(Timing chart when the FSV is closed in this embodiment)
First, a timing chart when the FSV 6 is closed in the present embodiment shown in FIG. 5 will be described.

  In the present embodiment, when the flow of the cooling water to the heater core 3 (see FIG. 1) of the cooling water flow path 8b is shut off from the state where the electric W / P1 is in the normal driving state, the ECU 7 first closes the FSV 6 in this embodiment. The maximum rotation speed of the electric W / P1 that can be valved (the maximum rotation speed that can be closed) is calculated. Then, the ECU 7 performs drive control of the electric W / P1 so as to drive at a low speed at the calculated maximum valve-closing possible rotation speed. As a result, although the electric W / P1 is in a low drive state, circulation of the cooling water in the engine cooling device 100 (the cooling water flow path 8a via the radiator 2 (when the thermostat 5 is opened) and the cooling water flow path 8c) ( Circulation) continues. Further, the ECU 7 energizes the FSV 6 substantially at the same time as instructing to drive the electric W / P 1 low. Thereby, an electrical suction force in the valve closing direction (see FIG. 4) is applied to the valve body 62. Here, since the electric W / P1 is driven at the maximum valveable rotation speed, even if the cooling water is circulated in the FSV 6, the suction force by the solenoid 65 rather than the force based on the pressure of the cooling water. And the total force of the urging force by the urging member 64 is increased. As a result, the FSV 6 is closed.

  After completing the valve closing of the FSV 6, the ECU 7 performs drive control of the electric W / P1 so that it is normally driven. Thereby, the rotation speed of the electric W / P1 is increased, and the flow rate of the discharged cooling water is increased.

(Timing chart when the FSV is closed in the conventional example)
Next, a timing chart when the FSV is closed in the conventional example shown in FIG. 6 will be described. As a conventional example, there is shown a case where the driving of the electric W / P is stopped when the FSV is closed while having the same configuration as the engine cooling device 100 of the above embodiment.

  When it is desired to block the flow of the cooling water to the heater core from the state where the electric W / P is in the normal driving state, in the conventional example, the driving of the electric W / P is stopped by the ECU. Thereafter, the ECU energizes the FSV after the fluctuation of the front-rear differential pressure of the FSV has settled and the front-rear differential pressure almost disappears. As a result, the FSV is closed. In addition, the ECU performs drive control of the electric W / P so that the FSV is driven again almost simultaneously with the energization of the FSV. At this time, since the electric W / P includes a brushless / sensorless motor, the start driving of the electric W / P until the electric W / P is normally driven after the ECU issues an instruction to drive the electric W / P. A period of time is required.

(Comparison between this embodiment and conventional example)
As a result, when the FSV is closed, in the conventional engine cooling apparatus, the cooling water in the engine cooling apparatus is used in the electric W / P stop period and the start drive period necessary for closing the FSV. Circulation is stopped. As a result, the period during which the engine is not cooled is lengthened, and as a result, the engine that is being driven is not sufficiently cooled, resulting in a high temperature of the engine. On the other hand, in the engine cooling device 100 of the present embodiment, the electric W / P1 continues to be driven low even during the valve closing control of the FSV 6, so that the coolant flow in the engine cooling device 100 (when the thermostat 5 is opened) The cooling water is circulated in the path 8a and the cooling water flow path 8c), and the cooling water is circulated to the driving engine 101. Further, unlike the engine cooling device of the conventional example, a period for starting the electric W / P1 does not occur. Thereby, it is possible to effectively suppress the occurrence of inconvenience due to the engine 101 not being sufficiently cooled.

(FSV valve closing control)
Next, the valve closing control flow of the FSV 6 in one embodiment of the present invention will be described with reference to FIGS. This control flow is performed by the ECU 7 (see FIG. 1).

  First, as shown in FIG. 7, in step S1, it is determined whether or not it is necessary to close the FSV 6 of the cooling water flow path 8b, and the control in step S1 is repeated until it is determined that it is necessary. If it is determined that the FSV 6 needs to be closed, in step S2, the downstream side temperature (outlet) of the cooling water on the downstream side (outlet) of the engine 101 based on the outlet water temperature information transmitted from the water temperature sensor 7a. Water temperature To) is acquired. In step S3, the current engine speed and engine torque of the engine 101 are acquired based on the engine speed information and torque information transmitted from the engine 101, and the pump speed information transmitted from the electric W / P1. Based on the above, the current rotation speed (pump rotation speed) of the electric W / P1 is acquired.

  In step S4, the upstream temperature (inlet water temperature Ti) of the cooling water on the upstream side (inlet) of the engine 101 is estimated based on the acquired outlet water temperature To, engine speed, and engine torque.

  Specifically, first, the ECU 7 obtains a cooling loss from the acquired engine speed and engine torque based on the cooling loss map shown in FIG. 8 stored in advance in a storage unit (not shown) of the ECU 7. This cooling loss map shows the cooling loss with respect to the engine torque for each engine speed. For example, the ECU 7 determines that the cooling loss is about 25 kW from the cooling loss map when the engine speed is about 2000 rpm and the engine torque is about 150 N · m.

  The engine inlet / outlet water temperature difference ΔT = (outlet water temperature To−inlet water temperature Ti) = (cooling loss / (cooling water flow rate × cooling water specific heat × cooling water density)) The engine inlet / outlet water temperature difference ΔT and the inlet water temperature Ti are estimated from the loss and the outlet water temperature To. In Equation (1), the “cooling water flow rate” is the cooling water flow rate discharged from the electric W / P 1 and is acquired by the ECU 7 based on the pump rotation speed. Further, in the formula (1), “specific heat of cooling water” and “density of cooling water” may be approximated to be 1 each simply, or may be obtained by performing measurement or the like in advance. .

  Next, in step S5, the opening degree of the thermostat 5 is estimated based on the inlet water temperature Ti. Specifically, the inlet water temperature Ti is substantially equal to the temperature of the cooling water in the thermostat 5 disposed in the vicinity of the engine 101 on the upstream side of the engine 101. Therefore, the ECU 7 estimates the opening degree of the thermostat 5 from the inlet water temperature Ti using the opening degree characteristic map shown in FIG. 2 stored in advance in the storage unit of the ECU 7. In this opening degree characteristic map, the opening degree of the thermostat 5 with respect to the inlet water temperature Ti is shown. For example, when the inlet water temperature Ti is about 80 ° C., the opening degree of the thermostat 5 is estimated to be 0% from the opening degree characteristic map.

  Next, in step S6, the flow resistance of the cooling water with respect to the flow rate of the cooling water discharged from the electric W / P1 is estimated based on the opening degree of the thermostat 5. Specifically, the ECU 7 estimates the flow resistance of the cooling water corresponding to the estimated opening of the thermostat 5 using the flow resistance map shown in FIG. 3 stored in the storage unit of the ECU 7. In this water flow resistance map, the water flow resistance of the cooling water with respect to the flow rate of the electric W / P1 for each opening degree of the thermostat 5 is shown. As the opening degree of the thermostat 5 becomes smaller, the cooling water flow rate is reduced. The flow resistance of the cooling water to the flow rate increases.

  In step S7, the maximum rotation speed (maximum rotation speed that can be closed) of the electric W / P1 that can close the FSV 6 is acquired based on the flow resistance of the cooling water. Specifically, the storage unit of the ECU 7 stores the maximum discharge pressure (maximum discharge pressure that can be closed) of the electric W / P1 that can close the FSV 6 obtained in advance and the rotation speed map shown in FIG. Has been. In this rotation speed map, the discharge pressure of the electric W / P1 with respect to the flow rate of the cooling water of the electric W / P1 for each rotation speed of the electric W / P1 is shown.

  The maximum discharge pressure that can be closed is obtained by measuring the maximum differential pressure across the front and back that can be closed by energization in the FSV 6 and the ratio of the differential pressure across the FSV 6 to the pressure of the cooling water discharged from the electric W / P1. In addition, it is obtained in advance by dividing the maximum differential pressure before and after the valve can be closed by the ratio of the differential pressure before and after. For example, when the maximum front-rear differential pressure that can be closed by energization in the FSV 6 is about 0.2 kPa, and the ratio of the front-rear differential pressure of the FSV 6 to the pressure of the coolant discharged from the electric W / P 1 is 10%. The maximum discharge pressure that can be closed is about 2 kPa (= 0.2 / 0.1).

  Then, the ECU 7 obtains the rotation speed of the electric W / P1 passing through the intersection point O between the maximum valveable discharge pressure and the coolant flow resistance in the rotation speed map as the maximum valveable rotation speed. For example, when the coolant flow resistance (shown by a straight line) and the maximum valveable discharge pressure intersect at the intersection O as shown in FIG. 9 with respect to the flow rate of the coolant discharged from the electric W / P1, the intersection O Is obtained as the maximum number of rotations that can be closed. In addition, as shown in FIG. 9, the maximum number of rotations that can be closed decreases as the flow resistance of the cooling water increases.

  In step S8, the valve closing time of the FSV 6 is acquired based on the flow resistance of the cooling water. Specifically, the ECU 7 sets the flow rate of the cooling water in the cooling water flow path 8b (FSV6) with respect to the flow rate of the cooling water corresponding to the intersection O in FIG. 9 and the flow rate of the cooling water discharged from the electric W / P1 obtained in advance. From this ratio, the flow rate of the cooling water in the FSV 6 when the electric W / P1 is driven at the maximum possible rotation speed is obtained. In addition, it is preferable that the flow volume of the cooling water in FSV6 is about 1 (L / min) or less, and it is more preferable that it is about 0.5 (L / min) or less.

  The ECU 7 then obtains the flow rate of the cooling water in the FSV 6 acquired based on the valve closing time map shown in FIG. 10 stored in advance in a storage unit (not shown) of the ECU 7 and the flow of the cooling water acquired in step S6. The valve closing time of the FSV 6 is acquired from the water resistance. This valve closing time map shows the valve closing time of the FSV 6 with respect to the flow rate of the cooling water in the FSV 6 for each cooling water flow resistance, and the valve closing time becomes longer as the cooling water flow resistance increases. Become.

In step S9, the electric W / P1 is driven and controlled so that the electric W / P1 is driven at the maximum valveable rotation speed obtained. As a result, as shown in FIG. 5, the driving state of the electric W / P1 is switched from the normal driving state to the low driving state, and the flow rate of the cooling water discharged from the electric W / P1 is reduced. In step S10, the solenoid 65 of the FSV 6 is energized. Thereby, even if it is in the state which distribute | circulated cooling water, the force which totaled the electrical attraction force and the urging | biasing force of the urging | biasing member 64 by the flow volume of a cooling water reducing is the pressure of a cooling water. And the valve body 62 is moved in the valve closing direction (see FIG. 4). Thereby, FSV6 of the cooling water flow path 8b will be in a valve closing state. The cooling water whose flow rate has been reduced flows through the cooling water flow path 8a and the cooling water flow path 8c when the thermostat 5 is opened, other than the cooling water flow path 8b. As a result, the cooling water continues to flow through the engine 101.

  Thereafter, in step S11, it is determined whether or not the valve closing time of the FSV 6 acquired in step S8 has elapsed since the solenoid 65 of the FSV 6 is energized, and the control in step S11 is performed until it is determined that the time has elapsed. Is repeated. When it is determined that the valve closing time of the FSV 6 has elapsed, in step S12, the driving state of the electric W / P1 is returned from the low driving state to the normal driving state, and the cooling water discharged from the electric W / P1 The flow rate of is increased. That is, in the engine cooling apparatus 100, the valve closing time of the FSV 6 is set by the ECU 7, and the flow rate of the cooling water in the cooling water circulation passage 8 is increased after the valve closing time has elapsed. Then, the valve closing control flow of the FSV 6 is ended.

  At this time, since the electric W / P1 continues to be driven even during the low drive period of the electric W / P1, the electric W / P1 can be quickly and normally returned from the low driving state without requiring a period for starting driving. Switch to driving state. As a result, even when the engine 101 cannot be sufficiently cooled in the low driving state of the electric W / P1 such that the engine 101 is driven with a high load, the electric W / P1 is quickly in the normal driving state. By switching to, the engine 101 is quickly and sufficiently cooled.

[Effect of this embodiment]
In the present embodiment, the following effects can be obtained.

  In the present embodiment, as described above, when the FSV 6 of the cooling water flow path 8b that does not pass through the radiator 2 is closed, the FSV 6 is closed in a state in which the cooling water whose flow rate has been reduced is circulated. An ECU 7 is provided for performing control for blocking the flow of the cooling water in the path 8b. As a result, even when the FSV 6 in the cooling water flow path 8b that does not pass through the radiator 2 is closed by closing the FSV 6 in a state where the cooling water is circulated, the engine cooling device 100 (via the radiator 2) can be closed. Since the cooling water can be circulated through the cooling water flow path 8a (when the thermostat 5 is opened) and the cooling water flow path 8c), the cooling water is prevented from flowing to the engine 101. be able to. As a result, when the FSV 6 of the cooling water flow path 8b that does not pass through the radiator 2 is closed, the engine 101 can be continuously cooled by the circulating cooling water, so that the temperature of the driving engine 101 is prevented from becoming high. be able to. In addition, when the valve body 62 is moved in the valve closing direction, the force for moving the valve body 62 in the valve closing direction against the circulating cooling water is caused by circulating the cooling water having a reduced flow rate. Since it can suppress that it becomes large, it can suppress that big electrical attraction force is needed in FSV6. Thereby, it is possible to suppress an increase in electric power necessary for closing the valve in the FSV 6, and it is possible to suppress an increase in the size of the FSV 6 in order to generate a large electric attractive force.

  In the present embodiment, the FSV 6 is configured to move the valve element 62 in the valve closing direction by the urging force of the urging member 64 and the electric suction force while driving the electric W / P1. Accordingly, the valve body 62 can be easily moved in the valve closing direction against the circulating cooling water by the amount of the urging force by the urging member 64, so that the FSV 6 of the cooling water flow path 8 b that does not pass through the radiator 2 can be changed. Since the valve is closed, it is possible to suppress the flow rate of the cooling water from being greatly reduced. As a result, even in a state where the flow rate of the cooling water is reduced, the cooling water is supplied to the engine cooling device 100 (the cooling water flow path 8a via the radiator 2 (when the thermostat 5 is opened) and the cooling water flow path 8c). It can be distributed sufficiently.

  Further, in the present embodiment, the ECU 7 obtains the maximum valveable rotation speed of the electric W / P1 based on at least the flow resistance of the cooling water, and the electric W / P1 at the rotation speed of the maximum valveable rotation speed. The valve body 62 is moved in a state where the valve is driven to perform control to close the FSV 6 of the cooling water flow path 8b. As a result, the valve body 62 is moved in a state where the electric W / P1 is driven at the maximum valve-closing possible rotation speed, so that the inside of the engine cooling device 100 (the cooling water flow path 8a via the radiator 2 (opening of the thermostat 5) is performed. ) And the cooling water flow path 8c), the FSV 6 of the cooling water flow path 8b that does not pass through the radiator 2 can be reliably closed. Further, by obtaining the maximum valveable rotation speed of the electric W / P1 based on the cooling water flow resistance related to the maximum valveable rotation speed of the electric W / P1, it is possible to accurately close the electric W / P1. The FSV 6 can be more reliably closed based on the maximum possible rotation speed.

  In the present embodiment, the ECU 7 is configured to estimate the flow resistance of the cooling water based on the opening degree of the thermostat 5. Thereby, based on the appropriately estimated flow resistance of the cooling water, it is possible to acquire a more accurate maximum possible rotation speed of the electric W / P1. Further, when the thermostat 5 is in the open state, even if the circulation of the cooling water in the cooling water flow path 8 b is interrupted, the cooling water flows through the cooling water flow path 8 a and distributes the cooling water to the engine 101. The cooling water can be effectively cooled by circulating the cooling water through the radiator 2 of the cooling water flow path 8a. Further, when the thermostat 5 is in the closed state, it is not preferable that the engine 101 being driven is cooled with cooling water having a low temperature, such as when the engine is warming up. By not circulating the cooling water, it is possible to suppress the cooling of the cooling water in the radiator 2 and to suppress the engine 101 from being excessively cooled.

  Further, in the present embodiment, even when the electric W / P1 is an electric water pump including the brushless / sensorless motor 1a, when the FSV 6 is closed in the engine cooling device 100, the electric W / P1 is used. By driving P1 so as to decrease the flow rate of the cooling water, no extra time is required as in the period for starting driving. As a result, even if the electric W / P1 includes the brushless / sensorless motor 1a, it is possible to prevent the cooling water from flowing through the engine 101.

  In the present embodiment, the ECU 7 performs control to increase the flow rate of the cooling water by the electric W / P1 after the valve closing of the FSV 6 of the cooling water flow path 8b is completed. Thereby, cooling of the oil etc. of the engine 101 and the oil cooler 4 with a cooling water can be performed effectively.

  In the present embodiment, the heater core 3 that exchanges heat between the cooling water is disposed in the cooling water flow path 8b in which the FSV 6 is disposed. Thereby, when the FSV 6 is in the valve open state, the heater core 3 can heat the inside of the vehicle with the heat recovered from the cooling water, so that the heat of the cooling water can be used efficiently. Further, by closing the FSV 6, it is possible to block the cooling water heated by the engine 101 from flowing through the heater core 3 (cooling water flow path 8 b), so that the cooling efficiency in the vehicle can be improved. it can.

  Moreover, in this embodiment, the oil cooler 4 with which cooling water heat-exchanges is arrange | positioned to the cooling water flow path 8c. Thereby, oil can be cooled using the cooling water circulating through the cooling water circulation passage 8. Further, by closing the FSV 6, the flow of the cooling water in the heater core 3 (cooling water flow path 8 b) is blocked, and the flow rate of the cooling water flowing through the oil cooler 4 (cooling water flow path 8 c) is increased. Therefore, the oil cooling efficiency in the oil cooler 4 can be improved.

  Moreover, in this embodiment, ECU7 acquires the valve-closing maximum rotation speed of electric W / P1 based on the maximum discharge pressure which can be closed in cooling water in electric W / P1, and the water flow resistance of cooling water. Configure as follows. As a result, the maximum possible rotation speed of the electric W / P1 can be reliably acquired.

  In the present embodiment, the ECU 7 sets a period (valve closing time) until the valve closing of the FSV 6 is completed according to the water flow resistance of the cooling water, and after the set valve closing time of the FSV 6 has elapsed, Control is performed to increase the flow rate of the cooling water using W / P1. As a result, it is possible to suppress an increase in the flow rate of the cooling water flowing through the FSV 6 in a state where the FSV 6 is not completely closed, so that the cooling water in the cooling water flow path 8b can be prevented without the FSV 6 being completely closed. It is possible to prevent the circulation of

  Further, in the present embodiment, the ECU 7 controls the upstream side of the engine 101 based on the downstream temperature (outlet water temperature To) of the cooling water on the downstream side of the engine 101 detected by the water temperature sensor 7a and the cooling loss in the engine 101. An upstream side temperature (inlet water temperature Ti) of the cooling water on the side is estimated, and the opening degree of the thermostat 5 arranged on the upstream side of the engine 101 is estimated based on the inlet water temperature Ti. As a result, the opening degree of the thermostat 5 can be estimated using the detection result (exit water temperature To) of the water temperature sensor 7 a that is generally arranged on the downstream side of the engine 101. It is not necessary to arrange a water temperature sensor separately from the sensor 7a. Thereby, the number of parts can be reduced.

[Modification]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of claims for patent, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, when the engine cooling device 100 closes the FSV 6, the maximum possible rotation speed is acquired from various parameters such as the outlet water temperature, and the electric W is obtained with the acquired maximum possible rotation speed. Although an example is shown in which / P1 is driven low, the present invention is not limited to this. In the present invention, the engine cooling device may be configured such that the FSV is closed by at least an electric suction force in a state where the flow rate of the cooling water is reduced. For example, the engine cooling device may be configured to drive the electric W / P at a low speed at a preset low rotation speed when closing the FSV. As a result, there is no need to obtain the maximum possible rotation speed, so the control load on the ECU can be reduced accordingly.

  In the above-described embodiment, an example in which the electric W / P1 is driven at a low value with the maximum valveable rotation speed acquired by the ECU 7 is shown, but the present invention is not limited to this. In the present invention, the ECU may drive the electric W / P at a low speed that is less than the maximum number of rotations that can be closed. At this time, it is preferable to drive the electric W / P at a low speed that is less than the maximum valve-closing speed and close to the maximum valve-closing speed. Thereby, it is possible to more reliably close the FSV while sufficiently securing the flow rate of the cooling water in the low driving state of the electric W / P.

  Moreover, although the example which estimates each of the inlet water temperature Ti, the opening degree of the thermostat 5, and the cooling water flow resistance was shown in the said embodiment, this invention is not limited to this. In this invention, you may comprise so that an inlet water temperature, the opening degree of a thermostat, and the flow resistance of cooling water may each be detected directly using detection parts, such as a sensor. In addition, when directly detecting the cooling water flow resistance, it is not necessary to acquire (estimate) the inlet water temperature and the opening degree of the thermostat. When the opening degree of the thermostat is directly detected, There is no need to obtain (estimate) the water temperature.

  In the above embodiment, the ECU 7 has shown the example in which the valve closing time of the FSV 6 is obtained from the flow resistance of the cooling water and the flow rate of the cooling water in the FSV 6, but the present invention is not limited to this. In the present invention, the ECU may use a preset valve closing time as the valve closing time of the FSV. As a result, there is no need to obtain the valve closing time, and the control load on the ECU can be reduced accordingly.

  Moreover, in the said embodiment, although the example using electric W / P1 was shown as a water pump, this invention is not limited to this. For example, as the water pump, a non-electric water pump that transmits a rotational driving force from an engine crankshaft or the like may be used. In this case, it is possible to control the flow rate of the cooling water discharged from the water pump by configuring the distance between the impeller and the cover in the water pump to be adjustable. It is also possible to control the flow rate of cooling water discharged from the water pump by controlling the rotational driving force transmitted from the crankshaft by using a member capable of controlling the driving force such as a transmission and a clutch. Is possible.

  Moreover, although the electric W / P1 is an electric water pump including the brushless / sensorless motor 1a in the above embodiment, the present invention is not limited to this. In the present invention, instead of the brushless / sensorless motor, the electric W / P may include a brushless motor provided with a sensor for detecting the position of the rotor or a motor having a brush.

  In the above embodiment, the example in which the FSV 6 (solenoid valve) includes the urging member 64 in addition to the solenoid 65 is shown, but the present invention is not limited to this. In the present invention, the solenoid valve only needs to be configured such that the valve element moves in the valve closing direction by at least an electric attractive force. That is, the electromagnetic valve may be configured not to include the biasing member.

  Moreover, in the said embodiment, the thermostat 5 is arrange | positioned in the cooling water flow path 8a (1st cooling water flow path) in which the radiator 2 is arrange | positioned, the heater core 3 is arrange | positioned, and the cooling water flow path 8b (2nd cooling water flow) in which FSV6 is arrange | positioned. Although an example in which the heater core 3 is disposed in the water flow path) and the oil cooler 4 is disposed in the cooling water flow path 8c (third cooling water flow path) has been shown, the present invention is not limited thereto. In the present invention, a heat exchanger other than the radiator may be disposed in the first cooling water flow path. Moreover, it is not necessary to arrange a thermostat in the first cooling water channel. Further, a heat exchanger other than the heater core may be added to the second cooling water flow path, or another heat exchanger may be arranged instead of the heater core, or the heat exchanger itself including the heater core may be arranged. It is not necessary to arrange. Further, a heat exchanger other than the oil cooler may be added to the third cooling water flow path, or another heat exchanger may be arranged instead of the oil cooler, or heat exchange including the oil cooler The container itself may not be arranged. Here, as a heat exchanger other than the heater core and the oil cooler, an EGR (Exhaust Gas Recirculation) cooler, an exhaust heat recovery device, a mission cooler, an inverter cooler, or the like can be used.

  Moreover, although the example which provided the cooling water flow path 8c (3rd cooling water flow path) in which the oil cooler 4 is arrange | positioned was shown in the said embodiment, this invention is not limited to this. In the present invention, the third cooling water channel may not be provided.

  Moreover, in the said embodiment, although the example in which the engine cooling device 100 was mounted in a vehicle was shown, this invention is not limited to this. You may provide the engine cooling device of this invention in the ship etc. to which the engine was attached.

1 Electric water pump (water pump)
1a Brushless sensorless motor (Sensorless motor)
2 Radiator 3 Heater core (first heat exchanger)
4 Oil cooler (second heat exchanger)
5 Thermostat 6 Flow shutting valve (solenoid valve)
7 ECU (control unit)
7a Water temperature sensor (temperature detector)
8a Cooling water channel (first cooling water channel)
8b Cooling water channel (second cooling water channel)
8c Cooling water channel (third cooling water channel)
62 Valve body 64 Energizing member 100 Engine cooling device 101 Engine

Claims (5)

A water pump capable of controlling the flow rate of cooling water for cooling the engine,
A first cooling water flow path for circulating the cooling water to the engine via a radiator;
A second cooling water flow path for circulating the cooling water to the engine without passing through the radiator;
An electromagnetic valve that is provided in the second cooling water flow path, includes a valve body, and opens and closes by moving the valve body by an electric suction force;
When the solenoid valve of the second cooling water flow path is closed, the water pump is driven so as to reduce the flow rate of the cooling water, whereby the cooling water having a reduced flow rate is circulated. A controller that performs control to shut off the flow of the cooling water in the second cooling water flow path by closing the electromagnetic valve by moving the valve body in the valve closing direction by at least an electric suction force; equipped with a,
The control unit obtains the maximum valveable rotation speed of the water pump based on at least the flow resistance of the cooling water, and drives the water pump at a rotation speed equal to or lower than the maximum valveable rotation speed. An engine cooling device configured to perform control to close the electromagnetic valve of the second cooling water flow path by moving the valve body in a state . The solenoid valve further includes a biasing member that biases the valve body in the valve closing direction,
2. The engine cooling device according to claim 1, wherein the valve body is moved in the valve closing direction by an urging force and an electric suction force of the urging member while driving the water pump. 3. A thermostat provided in the first cooling water flow path, the opening of which changes based on the temperature of the cooling water;
The engine cooling device according to claim 1 or 2 , wherein the control unit is configured to estimate a water flow resistance of the cooling water based on an opening degree of the thermostat. The engine cooling apparatus according to any one of claims 1 to 3 , wherein the water pump is an electric water pump including a sensorless motor. The control unit, wherein the rear closing completion of the second coolant passage of the solenoid valve, the is configured to perform a control for increasing the flow rate of the cooling water by the water pump, according to claim 1-4 The engine cooling device according to any one of the preceding claims.

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