JP2007009851A - Engine cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine cooling device capable of increasing fuel economy by reducing the work load of a water pump circulating cooling water. <P>SOLUTION: This engine cooling device comprises a bypass passage 41 allowing the intake port 13b and the discharge port of a water pump to communicate with each other. The bypass passage 41 is connected to the intake port 13b so that the cooling water flows thereinto in the tangential direction of the inner wall 43a of a pipe 43. Accordingly, the cooling water at the intake port 13b causes swirl flow by the cooling water flowing from the bypass passage 41 thereinto. Then, the cooling water is led into the impeller of the water pump while causing swirl flow. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine cooling apparatus that cools an engine with cooling water.

Conventionally, in a water-cooled engine in which cooling water supplied to an engine is circulated through a radiator, a bypass passage is provided that connects a suction port and a discharge port of a water pump that circulates cooling water, and the bypass passage is provided by a control valve. A cooling device that controls the flow rate of circulating coolant has been proposed (see, for example, Patent Document 1). In such a cooling device, the opening and closing of the control valve is controlled based on a signal of a temperature sensor that detects the temperature of the cooling water in the engine, and at least one of the cooling water discharged from the water pump when the control valve is opened. The part is led to the intake port of the water pump through the bypass passage. That is, during cold operation of the engine, the control valve is opened to increase the flow rate of the cooling water flowing through the bypass passage, thereby reducing the flow rate of the cooling water supplied to the engine and quickly The temperature is increased to stabilize combustion. On the other hand, during the warm operation of the engine, the control valve is closed so that the cooling water does not flow through the bypass passage, thereby increasing the flow rate of the cooling water supplied to the engine and the engine cooling effect. Is fully obtained.
JP 2004-301032 A

  By the way, in such a cooling device, the cooling water circulating in the cooling water circulation passage and the cooling water flowing in from the bypass passage are merged at the suction port of the water pump. There is a risk that the pumping loss of the water pump will increase due to disturbance. That is, when turbulent flow occurs at the cooling water merging portion, the speed fluctuation and pressure fluctuation of the cooling water increase, and the fluctuation of the load on the water pump increases. When the load fluctuation of the water pump becomes large, the work amount of the water pump is increased, which causes deterioration of fuel consumption.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine cooling device that can reduce the work of a water pump that circulates cooling water and can improve fuel efficiency. .

  In order to achieve the above object, an invention according to claim 1 is provided with a water pump provided in a cooling water circulation passage for circulating cooling water of an engine through a radiator and rotating the impeller to circulate the cooling water, and the water An engine cooling apparatus comprising a bypass passage communicating with a suction port and a discharge port of a pump and returning at least a part of cooling water discharged from the discharge port to the suction port. The bypass passage extends from the bypass passage. The cooling water flowing into the suction port is connected to the suction port in such a manner that the cooling water sucked into the water pump generates a swirling flow in the same direction as the rotation direction of the impeller.

  According to this configuration, since the swirl flow in the same direction as the rotation direction of the impeller is generated in the cooling water sucked into the water pump, the impeller is rotated in the rotation direction by the swirl force. As a result, the driving force of the water pump, and hence the external load of the engine can be reduced, and the fuel consumption can be improved. In addition, since the cooling water is swirling in the same direction as the impeller rotation direction, the relative speed of both of the cooling water when colliding with the impeller blades becomes small, and the cooling water generated after passing through the impeller The eddy current becomes smaller. As a result, the occurrence of cavitation at the discharge port can be suppressed, and the generation of noise and piping damage due to this can be suitably avoided.

  In addition, as an aspect when connecting the bypass passage and the discharge port in this manner, specifically, as described in claim 2, the bypass passage extends in a direction perpendicular to the direction in which the suction port extends. It is possible to adopt a configuration in which the cooling port is connected to the suction port so that the cooling water flows from the bypass passage toward the suction port toward a position eccentric from the center of the passage section of the suction port.

  According to a third aspect of the present invention, in the engine cooling apparatus according to the second aspect, the bypass passage is connected to the suction port so that cooling water flows in a tangential direction of the inner wall of the suction port. I am doing so.

According to this configuration, the turning force of the cooling water flowing into the water pump through the suction port can be further increased.
According to a fourth aspect of the present invention, in the engine cooling device according to any one of the first to third aspects, the suction port has a circular cross section in a portion where the bypass passage is connected. I have to.

According to the configuration, the flow resistance when the cooling water swirls and flows through the suction port can be reduced, and the swirling force of the cooling water can be further increased.
The invention described in claim 5 further includes a control valve for controlling the flow rate of the cooling water flowing through the bypass passage.

  According to this configuration, the amount of cooling water supplied to the engine can be adjusted by controlling the flow rate of the cooling water flowing through the bypass passage by the control valve. For this reason, for example, during cold operation of the engine, the amount of cooling water supplied to the engine is reduced to shorten the warm-up time, and the work of the water pump is reduced. Will be able to.

  According to a sixth aspect of the present invention, in the engine cooling apparatus according to the fifth aspect, the engine is mounted on a vehicle as a drive source thereof, and the radiator is in contact with a traveling wind generated when the vehicle is traveling. The vehicle further includes travel speed detecting means for detecting the travel speed of the vehicle, and control means for opening the control valve when the detected travel speed of the vehicle is equal to or higher than a predetermined speed.

  When the vehicle is traveling at high speeds, the running wind becomes stronger and the radiator's heat dissipation efficiency can be expected to increase, so the cooling function of the engine with cooling water should be maintained even if the amount of cooling water supplied to the engine is reduced. Can do. According to this configuration, the control valve is controlled to open when it is detected that the vehicle traveling speed is equal to or higher than the predetermined speed. The flow rate of the cooling water flowing through the passage can be increased, and the amount of the cooling water supplied to the engine can be relatively reduced. If the circulation amount of the cooling water is reduced, the work amount of the water pump is reduced and the external load of the engine can be reduced, so that the fuel efficiency can be improved.

Hereinafter, with reference to FIGS. 1-6, embodiment of the cooling device of the engine for vehicles concerning this invention is described.
FIG. 1 shows a cooling device 1 for a water-cooled engine 11 mounted on a vehicle. The cooling device 1 is provided with a radiator 12 that comes into contact with traveling wind generated as the vehicle travels. The engine 11 is connected to a first cooling water circulation passage (cooling water circulation passage) 21 that circulates the cooling water supplied to the engine 11 via the radiator 12. The engine 11 is connected to a second cooling water circulation passage 31 that circulates the cooling water supplied to the engine 11 without passing through the radiator 12.

  The first cooling water circulation passage 21 is constituted by cooling water passages 22 to 26, and a water pump 13 and a thermostat valve 14 are provided in the middle thereof. The cooling water inlet 11 a of the engine 11 and the discharge port 13 a of the water pump 13 are connected by a first passage 22. The water pump 13 is driven by a crankshaft (not shown) of the engine 11 to generate a circulating flow of cooling water. The suction port 13 b of the water pump 13 and the thermostat valve 14 are connected by a second passage 23, and the thermostat valve 14 and the cooling water outlet 12 a of the radiator 12 are connected by a third passage 24. The cooling water inlet 12 b of the radiator 12 and the cooling water outlet 11 b of the engine 11 are connected by the fourth passage 25 and the fifth passage 26. The first cooling water circulation passage 21 is connected as described above, and the cooling water is circulated through the first cooling water circulation passage 21 by the water pump 13.

  Further, the cooling device 1 is provided with a bypass passage 41 that communicates the suction port 13b of the water pump 13 and the discharge port 13a. The bypass passage 41 is provided with an electromagnetic valve (control valve) 42 that controls the flow rate of the cooling water flowing through the bypass passage 41. The electromagnetic valve 42 is a switching valve that is selectively switched between an open state and a closed state, and is driven by an actuator such as a stepping motor or a solenoid. In the valve open state, at least a part of the cooling water discharged from the discharge port 13a of the water pump 13 is circulated through the bypass passage 41 and returned to the suction port 13b of the water pump 13. In the valve closed state, the water is discharged from the water pump 13. The cooling water is prevented from flowing through the bypass passage 41. That is, the electromagnetic valve 42 can change the amount of cooling water supplied to the engine 11 by controlling the flow rate of the cooling water flowing through the bypass passage 41.

  The second cooling water circulation passage 31 is constituted by the cooling water passages 22, 23, 32, and 26, and the water pump 13 and the thermostat valve 14 are provided in the middle thereof. The sixth passage 32 connects the thermostat valve 14 to the radiator 12 side of the fifth passage 26, and the cooling water is circulated through the second cooling water circulation passage 31 by the water pump 13.

  The thermostat valve 14 is a valve that switches the flow path of the cooling water according to the temperature of the cooling water. When the temperature of the cooling water flowing through the thermostat valve 14 is higher than the predetermined temperature Ta, the sixth passage 32 side is closed. The 2nd channel | path 23 and the 3rd channel | path 24 are connected. When the temperature of the cooling water is equal to or lower than the predetermined temperature Ta, the third passage 24 side is closed and the second passage 23 and the sixth passage 32 are communicated. Therefore, when the temperature of the cooling water flowing through the thermostat valve 14 is higher than the predetermined temperature Ta, the cooling water circulates through the first cooling water circulation passage 21, and the cooling water radiated by the radiator 12 is supplied to the engine 11. On the other hand, when the temperature of the cooling water flowing through the thermostat valve 14 is equal to or lower than the predetermined temperature Ta, the cooling water circulates through the second cooling water circulation passage 31 and the cooling water that is not radiated by the radiator 12 is supplied to the engine 11. For this reason, during cold operation such as when the engine is started, the cooling water that does not release heat from the radiator 12 circulates through the second cooling water circulation passage 31, so that the temperature of the cooling water can be quickly raised. Thus, the warm-up time can be shortened and early combustion stabilization can be achieved.

  Here, the configuration around the water pump 13 will be described with reference to FIGS. FIG. 2 is a perspective view of the impeller 61 of the water pump 13. The impeller 61 includes a plurality of blades 62, and sends out the cooling water flowing in from the direction perpendicular to the rotation plane of the impeller 61 to the surroundings to function as a pump. 3 is a configuration diagram of the water pump 13 and the bypass passage 41, and FIG. 4 is a cross-sectional view taken along the line AA of FIG. The suction port 13 b of the water pump 13 is configured by a pipe 43 having a circular cross section extending in a direction perpendicular to the rotation plane of the impeller 61. When the electromagnetic valve 42 is opened, the cooling water flows through the bypass passage 41, and the cooling water flowing from the bypass passage 41 and the cooling water flowing from the second passage 23 merge at the suction port 13b of the water pump 13. . At the junction of the suction port 13b, the bypass passage 41 extends in a direction perpendicular to the direction in which the pipe 43 of the suction port 13b extends and is connected to the suction port 13b of the water pump 13. As shown in FIG. 4, the bypass passage 41 is connected to the suction port 13 b so that the cooling water flows toward the tangential direction of the inner wall 43 a of the pipe 43. For this reason, the cooling water flowing in from the bypass passage 41 causes a swirling flow of the cooling water in the suction port 13b. Then, the cooling water is guided to the impeller 61 while generating a swirling flow.

  FIG. 5 is a cross-sectional view taken along line BB in FIG. 3 and shows a state where the impeller 61 pumps the cooling water. Since the impeller 61 is set so as to rotate in the same direction as the turning direction of the cooling water, the relative speed at which the cooling water collides with the blades 62 of the impeller 61 becomes small. That is, if the angular velocity of the impeller 61 is ωp and the angular velocity of the cooling water is ωw, the relative angular velocity ωr at which the cooling water collides with the blades 62 of the impeller 61 is a difference between the angular velocity ωp and the angular velocity ωw. For this reason, the load of cooling water with respect to the impeller 61 of the water pump 13 is reduced, and the work amount of the water pump 13 can be reduced. Further, since the cooling water generates a constant swirling flow in the suction port 13b, the load fluctuation of the cooling water with respect to the impeller 61 is reduced, and the work amount of the water pump 13 can be reduced. When the work amount of the water pump 13 is reduced, the load on the engine 11 that drives the water pump 13 is reduced, so that the fuel consumption can be improved. Further, since the relative speed at which the cooling water collides with the blades 62 of the impeller 61 is reduced, the vortex 63 generated after passing through the blades 62 can be reduced, and the occurrence of cavitation in the cooling water at the discharge port 13a is suppressed. be able to.

  The cooling device 1 is provided with various sensors for detecting the state of each part. A vehicle speed sensor 52 as a travel speed detecting means detects the travel speed of the vehicle. The water temperature sensor 53 is provided in the fifth passage 26 and detects the temperature of the cooling water flowing through the cooling water outlet portion 11 b of the engine 11. The accelerator sensor 54 detects the amount of depression of the accelerator pedal by the driver. The ECU (electronic control unit) 51 controls the cooling device 1 based on the detection signals of the sensors 52 to 54.

  Next, control of the cooling device 1 will be described. FIG. 6 shows a flowchart of a solenoid valve control routine by the cooling device 1. In this solenoid valve control routine, the ECU 51 as control means controls the opening and closing of the solenoid valve 42 based on detection signals from the vehicle speed sensor 52, the water temperature sensor 53, and the accelerator sensor 54. The ECU 51 repeats the electromagnetic valve control routine at every predetermined timing. When the solenoid valve control routine is started, the ECU 51 determines whether or not the accelerator depression amount is smaller than the predetermined depression amount α (step S110). When the accelerator depressing amount is equal to or greater than the predetermined depressing amount α, it is determined that a heavy load is applied to the engine 11. It is necessary to increase the cooling effect of the engine 11 by increasing it. For this reason, when the accelerator depression amount is equal to or larger than the predetermined depression amount α, the process proceeds to step S140, and the solenoid valve 42 is closed so that the coolant does not flow through the bypass passage 41. The flow rate of the cooling water supplied to 11 is increased.

  When the accelerator depression amount is smaller than the predetermined depression amount α, it is determined whether or not the vehicle traveling speed V is smaller than the predetermined speed Va (step S120). When the traveling speed V of the vehicle is equal to or higher than the predetermined speed Va, the traveling wind becomes strong, and an increase in the heat dissipation efficiency of the radiator 12 can be expected. Therefore, the temperature of the cooling water supplied to the engine 11 decreases, and the circulation amount of the cooling water Can be reduced. When the circulation amount of the cooling water is reduced, the work amount of the water pump 13 is reduced, and the load on the engine 11 that drives the water pump 13 is reduced. Therefore, the fuel consumption can be improved. For this reason, when the traveling speed V of the vehicle is equal to or higher than the predetermined speed Va, the process proceeds to step S150, the flow rate of the cooling water flowing through the bypass passage 41 is increased with the electromagnetic valve 42 opened, and supplied to the engine 11. Reduce the flow rate of cooling water.

  When the running speed V of the vehicle is lower than the predetermined speed Va, it is determined whether or not the temperature T of the cooling water flowing through the cooling water outlet 11b of the engine 11 is higher than the predetermined temperature Tb (step S130). When the temperature T of the cooling water is equal to or lower than the predetermined temperature Tb, the engine 11 is in cold operation, so that it is supplied to the engine 11 in order to quickly increase the temperature of the engine 11 and shorten the warm-up time. It is desirable to reduce the flow rate of the cooling water that is generated. For this reason, when the temperature T of the cooling water is equal to or lower than the predetermined temperature Tb, the process proceeds to step S150 to increase the flow rate of the cooling water flowing through the bypass passage 41 with the electromagnetic valve 42 opened and supplied to the engine 11. Reduce the flow rate of cooling water.

  When the temperature T of the cooling water is higher than the predetermined temperature Tb, the engine 11 is in a warm operation, so the process proceeds to step S140, and the flow rate of the cooling water supplied to the engine 11 is increased by closing the electromagnetic valve 42. Let In step S140, processing is performed so that the electromagnetic valve 42 is maintained in the closed state or the electromagnetic valve 42 is switched from the opened state to the closed state. Further, in step S150, processing is performed so that the electromagnetic valve 42 is maintained in the open state or the electromagnetic valve 42 is switched from the closed state to the open state. And this solenoid valve control routine is complete | finished.

  As described above, the flow rate of the cooling water supplied to the engine 11 can be controlled by controlling the electromagnetic valve 42 based on the vehicle operating state such as the traveling speed V of the vehicle. Thereby, it can suppress making the water pump 13 do excessive work, and can suppress the deterioration of a fuel consumption. Further, during the cold operation, the temperature of the cooling water can be quickly raised by the control of the electromagnetic valve 42 and the thermostat valve 14, so that the warm-up time can be shortened and early combustion stabilization can be achieved.

According to the above embodiment, the following effects can be obtained.
(1) In the above embodiment, the bypass passage 41 is connected to the suction port 13b so that the cooling water flows in the tangential direction of the inner wall 43a of the suction port 13b constituted by the pipe 43 having a circular passage cross section. Therefore, a swirling flow is generated at the suction port 13b. Further, the swirling flow is generated in the same direction as the rotation direction of the impeller 61 of the water pump 13. For this reason, since the relative speed at which the cooling water collides with the blades 62 of the impeller 61 is reduced, the load of the cooling water on the impeller 61 of the water pump 13 is reduced, and the work amount of the water pump 13 can be reduced. Further, since the cooling water generates a constant swirling flow in the suction port 13b, the load fluctuation of the cooling water with respect to the impeller 61 is reduced, and the work amount of the water pump 13 can be reduced. When the work amount of the water pump 13 is reduced, the load on the engine 11 that drives the water pump 13 is reduced, so that the fuel consumption can be improved.

  (2) In the above embodiment, the suction port 13b to which the bypass passage 41 is connected is constituted by the pipe 43 whose passage section has a circular shape. For this reason, the flow resistance when the cooling water swirls and flows through the suction port 13b can be reduced, and the swirl force of the cooling water can be further increased.

  (3) In the above embodiment, a swirling flow is generated in the suction port 13b, and the relative speed at which the cooling water collides with the blades 62 of the impeller 61 is reduced. For this reason, the vortex 63 generated after passing through the blades 62 of the impeller 61 can be reduced, and the occurrence of cavitation in the cooling water in the discharge port 13a can be suppressed. Therefore, it is possible to improve the reliability of the cooling device 1 by avoiding the generation of noise due to the occurrence of cavitation and the damage of the cooling water passage and the like.

  (4) In the above embodiment, when the traveling speed V of the vehicle is equal to or higher than the predetermined speed Va, the electromagnetic valve 42 is opened to increase the flow rate of the cooling water flowing through the bypass passage 41 and supplied to the engine 11. The cooling water flow is reduced. When traveling at high speed, the traveling wind becomes stronger, and an increase in the heat dissipation efficiency of the radiator 12 can be expected. Therefore, the cooling performance of the engine 11 can be maintained even if the circulating amount of cooling water is reduced. When the circulation amount of the cooling water is reduced, the work amount of the water pump 13 is reduced, and the load on the engine 11 that drives the water pump 13 is reduced. Therefore, the fuel consumption can be improved.

  (5) In the above embodiment, when the temperature T of the cooling water is equal to or lower than the predetermined temperature Tb, that is, when the engine 11 is in cold operation, the cooling water flowing through the bypass passage 41 with the electromagnetic valve 42 opened. The flow rate of the cooling water supplied to the engine 11 is decreased. For this reason, the temperature of the engine 11 can be quickly raised to shorten the warm-up time, and early combustion stabilization can be achieved. Moreover, the work amount of the water pump 13 can be reduced by reducing the circulation amount of the cooling water, and the fuel consumption can be improved.

  (6) In the above embodiment, when the amount of accelerator depression is greater than or equal to α, the solenoid valve 42 is closed so that the cooling water does not flow through the bypass passage 41, so that the first passage 22 passes through the engine 11. The flow rate of the supplied cooling water is increased. For this reason, the cooling effect of the engine 11 can be enhanced at the time of high engine load when the temperature of the engine 11 rises.

  (7) In the above embodiment, when the electromagnetic valve 42 is opened, the cooling water flowing through the bypass passage 41 is guided to the suction port 13b of the water pump 13, so that the suction port 13b and the discharge port 13a of the water pump 13 are used. The pressure difference of the cooling water at and decreases. For this reason, generation | occurrence | production of the cavitation in cooling water in the suction port 13b can be suppressed, generation | occurrence | production of the noise resulting from this and damage to piping can be avoided, and the reliability of the cooling device 1 can be improved.

  (8) In the above embodiment, when the temperature of the cooling water flowing through the thermostat valve 14 is equal to or lower than the predetermined temperature Ta, the cooling water circulates through the second cooling water circulation passage 31 and the cooling water that does not radiate heat from the radiator 12 is the engine. 11 is supplied. For this reason, during cold operation such as when the engine is started, the cooling water that does not release heat from the radiator 12 circulates through the second cooling water circulation passage 31, so that the temperature of the cooling water can be quickly raised. Thus, the warm-up time can be shortened and early combustion stabilization can be achieved.

In addition, you may change the said embodiment as follows.
In the above embodiment, in the connecting portion shown in FIG. 4, the bypass passage 41 enters the suction port 13 b so that the cooling water flows in the tangential direction of the inner wall 43 a of the suction port 13 b configured by the circular pipe 43. Although connected, you may connect so that cooling water may flow toward directions other than the tangential direction of the inner wall 43a. FIG. 7 is a cross-sectional view taken along the line AA in FIG. 3 when the cooling water flows from the bypass passage 41 in a direction other than the tangential direction of the inner wall 43a. The bypass passage 71 is connected to the suction port 13b so that the cooling water flows from the circular center O of the passage section of the suction port 13b constituted by the circular pipe 73 toward a position eccentric by a distance D. Even if comprised in this way, a swirl | vortex flow can be produced in the suction port 13b.

  In the above embodiment, the suction port 13b to which the bypass passage 41 is connected is configured by the pipe 43 having a circular cross section, but suction is performed by forming the cross section of the pipe 43 into a shape other than the circular shape. A swirling flow may be generated at the port 13b.

  In the above embodiment, the single bypass passage 41 is configured to be connected to the suction port 13b. However, the bypass passage 41 is divided into a plurality of parts at the connection portion of the bypass passage 41, and the outside of the suction port 13b. They may be connected from different directions. If comprised in this way, a swirling flow can be stably produced in the suction port 13b.

  In the above embodiment, the flow rate of the cooling water flowing through the bypass passage 41 is controlled by opening and closing the electromagnetic valve 42 to the open state or the closed state. For example, the flow rate of the cooling water flowing through the bypass passage 41 may be controlled by adjusting to a half-open state.

  In the above embodiment, the solenoid valve 42 is controlled to open and close based on the detection signals of the water temperature sensor 53 and the accelerator sensor 54. However, the solenoid valve 42 is controlled to open and close without using these detection signals. Also good.

  In the above-described embodiment, the electromagnetic valve 42 is controlled to be opened / closed based on the traveling speed V of the vehicle, but the electromagnetic valve 42 may be controlled to open / close based on other information such as the outside air temperature.

The block diagram of the cooling device of the engine for vehicles in this embodiment. The perspective view of an impeller. The block diagram around a water pump. Sectional drawing which follows the AA line of FIG. Sectional drawing which follows the BB line of FIG. The flowchart which shows the procedure of the process which controls a solenoid valve. Sectional drawing which follows the AA line of FIG. 3 in the other example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 12 ... Radiator, 13 ... Water pump, 13a ... Discharge port, 13b ... Intake port, 14 ... Thermostat valve, 21 ... First cooling water circulation passage, 31 ... Second cooling water circulation passage, 41 ... Bypass passage, 42 ... solenoid valve, 43 ... piping, 51 ... ECU, 52 ... vehicle speed sensor, 61 ... impeller, 62 ... blade.

Claims (6)

A water pump that is provided in a cooling water circulation passage that circulates engine cooling water through a radiator and circulates cooling water by rotating an impeller, and a suction port and a discharge port of the water pump communicate with each other from the discharge port. An engine cooling device comprising a bypass passage for returning at least a part of the discharged cooling water to the suction port;
The bypass passage is connected to the suction port in such a manner that the cooling water flowing into the suction port from the bypass passage generates a swirling flow in the same direction as the rotation direction of the impeller in the cooling water sucked into the water pump. An engine cooling device. The engine cooling device according to claim 1,
The bypass passage extends in a direction perpendicular to the direction in which the suction port extends, and enters the suction port so that cooling water flows into the suction port from the bypass passage toward a position eccentric from the passage cross-sectional center of the suction port. Engine cooling system characterized by being connected. The engine cooling device according to claim 2,
The bypass passage is connected to the suction port so that cooling water flows in a direction tangential to the inner wall of the suction port. The engine cooling device according to any one of claims 1 to 3,
The engine cooling device according to claim 1, wherein the suction port has a circular cross section in a portion where the bypass passage is connected. The engine cooling device according to any one of claims 1 to 4, further comprising a control valve that controls a flow rate of the cooling water flowing through the bypass passage. The engine cooling device according to claim 5,
The engine is mounted on a vehicle as a drive source thereof, and the radiator is in contact with traveling wind generated as the vehicle travels,
Traveling speed detection means for detecting the traveling speed of the vehicle;
The engine cooling device further comprising: a control unit that opens the control valve when the detected traveling speed of the vehicle is equal to or higher than a predetermined speed.

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