Engine cooling system for vehicle

Abstract

In order to reduce driving power of an engine cooling system in which a cooling fan for cooling a radiator and a water pump are driven by a motor, according to the invention, a pump motor of the water pump 5 which circulates liquid coolant is used as a drive source of the cooling fan. An electromagnetic clutch is provided between the pump motor and the cooling fan, and when the liquid coolant exiting from an engine is at a predetermined temperature or higher, the electromagnetic clutch is brought into a connected state, whereas when the liquid coolant is at a temperature lower than the predetermined temperature, the electromagnetic clutch is brought into a disconnected state. When the liquid coolant is at a temperature lower than the predetermined temperature, and the vehicle speed is at a predetermined speed or higher, the electromagnetic clutch is brought into a connected state, and a rotational force of the cooling fan receiving driving wind is transmitted to the pump motor to reduce its load.

1 . An engine cooling system for a vehicle, comprising:
 a water pump for circulating liquid coolant of an engine which is a propulsion source of the vehicle;   a pump motor which drives the water pump;   a temperature detecting means for detecting the temperature of the liquid coolant;   a radiator which cools the liquid coolant circulated by the water pump;   a cooling fan which cools the radiator;   a clutch which connects and disconnects the cooling fan to and from the pump motor;   an assist ability detecting means which detects whether or riot the cooling fan has assist ability of giving a rotational force to the pump motor when the cooling fan is rotated by receiving external wind dynamic pressure; and   a control means which controls the clutch, wherein   the control means causes the clutch to perform a connecting operation to connect the pump motor and the cooling fan when a detected temperature of the temperature detecting means is equal to or higher than a predetermined temperature, and when the detected temperature of the temperature detecting means is lower than the predetermined temperature and the assist ability detecting means detects presence of the assist ability, and the control means causes the clutch to perform a disconnecting operation to disconnect the pump motor from the cooling fan when the detected temperature of the temperature detecting means is lower than the predetermined temperature and the assist ability detecting means detects absence of the assist ability.   
   
   
       2 . The engine cooling system for a vehicle according to  claim 1 , wherein the assist ability detecting means comprises:
 a vehicle speed sensor which detects the speed of the vehicle; and   a judging means which judges that the assist ability is present when a detected speed of the vehicle speed sensor is equal to or higher than a predetermined speed, and judges that the assist ability is absent when the detected speed of the vehicle speed sensor is lower than the predetermined speed.   
   
   
       3 . The engine cooling system for a vehicle according to  claim 1 , wherein the assist ability detecting means comprises:
 a motor rotational speed detecting means which detects the rotational speed of the pump motor;   a vehicle speed sensor which detects the speed of the vehicle; and   a judging means which calculates to convert a detected speed of the vehicle speed sensor into a rotational speed of the cooling fan, and judges that the assist ability is present when the calculated rotational speed is beyond the rotational speed of the pump motor detected by the motor rotational speed detecting means, and judges that the assist ability is absent when the rotational speed of the cooling fan is equal to or less than the rotational speed of the pump motor.   
   
   
       4 . The engine cooling system for a vehicle according to  claim 1  wherein the assist ability detecting means comprises:
 a fan rotational speed detecting means which detects the rotational speed of the cooling fan;   a motor rotational speed detecting means which detects the rotational speed of the pump motor;   a vehicle speed sensor which detects the speed of the vehicle; and   a judging means which judges that the assist ability is present when the rotational speed of the cooling fan detected by the fan rotational speed detecting means is beyond the rotational speed of the pump motor detected by the motor rotational speed detecting means, and judges that the assist ability is absent when the vehicle speed sensor detects a speed that is equal to or less than a predetermined speed.   
   
   
       5 . An engine cooling system for a vehicle, comprising:
 a water pump for circulating liquid coolant of an engine which is a propulsion source of the vehicle;   a pump motor which drives the water pump;   a temperature detecting means for detecting the temperature of the liquid coolant;   a radiator which cools the liquid coolant; circulated by the water pump;   a cooling fan which cools the radiator;   a clutch which connects and disconnects the cooling fan to and from the pump motor;   a control means which causes the clutch to perform a connecting operation to connect the pump motor and the cooling fan when a detected temperature of the temperature detecting means is equal to or higher than a predetermined temperatures and causes the clutch to perform a disconnecting operation to disconnect the pump motor from the cooling fan when the detected temperature of the temperature detecting means is lower than the predetermined temperature; and   a one-way clutch which is provided between the pump motor and the cooling fan, connects the cooling fan to the pump motor when the cooling fan receives external wind dynamic pressure and tends to rotate faster than the pump motor, and cuts the connection of the cooling fan and a rotor shaft of the pump motor when a rotational speed of the cooling fan which rotates by receiving the external air pressure is lower than the rotational speed of the pump motor.   
   
   
       6 . The engine cooling system for a vehicle according to  claim 1 , wherein the rotational speed of the pump motor is controlled to be changed in accordance with the detected temperature of the temperature detecting means. 
   
   
       7 . The engine cooling system for a vehicle according to  claim 5 , wherein the rotational speed of the pump motor is controlled to be changed in accordance with the detected temperature of the temperature detecting means. 
   
   
       8 . The engine cooling system for a vehicle according to  claim 1 , wherein the rotational speed of the pump motor is controlled to be changed in accordance with the difference in temperature of the liquid coolant on an inlet port side and an outlet port side of the engine. 
   
   
       9 . The engine cooling system for a vehicle according to  claim 5 , wherein the rotational speed of the pump motor is controlled to be changed in accordance with the difference in temperature of the liquid coolant on an inlet port side and an outlet port side of the engine. 
   
   
       10 . The engine cooling system for a vehicle according to  claim 1 , wherein transmission of rotation from the pump motor to the water pump is performed by a magnetic coupling. 
   
   
       11 . The engine cooling system for a vehicle according to  claim 5 , wherein transmission of rotation from the pump motor to the water pump is performed by a magnetic coupling. 
   
   
       12 . The engine cooling system for a vehicle according to  claim 1 , wherein the pump motor is configured to be actuated behind a starting Lime of the engine. 
   
   
       13 . The engine cooling system for a vehicle according to  claim 5 , wherein the pump motor is configured to be actuated behind a starting time of the engine. 
   
   
       14 . The engine cooling system for a vehicle according to  claim 1 , wherein a further cooling fan for cooling the radiator or a body to be cooled other than the radiator is provided separately from the cooling fan, and a further motor which drives the further cooling fan is constituted of a motor generator which functions as a generator when receiving a rotational force from the further fan and the further cooling fan does not need to be driven. 
   
   
       15 . The engine cooling system for a vehicle according to  claim 5 , wherein a further cooling fan for cooling the radiator or a body to be cooled other than the radiator is provided separately from the cooling fan, and a further motor which drives the further cooling fan is constituted of a motor generator which functions as a generator when receiving a rotational force from the further fan and the further cooling fan does not need to be driven.