Controlling system for cooling fan

Abstract

A controlling system for a cooling fan according to the present invention includes a fluid-pressure motor for driving the cooling fan; a fluid-pressure pump functioning as a driving source for the fluid-pressure motor; and a controller. The controller determines a target motor speed value by selecting a higher one of required motor speed values respectively corresponding to multiple kinds of fluids to be cooled and controls the fluid-pressure motor so that the motor speed thereof reaches the target motor speed value, each of the required motor speed values being determined from a temperature value of the corresponding fluid detected by a corresponding one of temperature sensors on the basis of a characteristic preliminarily determined by a temperature-versus-motor-speed relationship for the corresponding fluids the characteristic being set for each kind of fluid.

1 . A controlling system for a cooling fan, comprising: 
 a fluid-pressure motor for driving the cooling fan;    a fluid-pressure pump functioning as a fluid-pressure source for the fluid-pressure motor;    temperature sensors for detecting temperature values of multiple kinds of fluids to be cooled; and    motor-speed controlling means for controlling a rotational speed of the fluid-pressure motor,    wherein the motor-speed controlling means determines a target motor speed value by selecting a higher one of required motor speed values respectively corresponding to the fluids and controls the fluid-pressure motor so that the motor speed thereof reaches the target motor speed value, each of the required motor speed values being determined from the temperature value of the corresponding fluid detected by the corresponding temperature sensor on the basis of a characteristic preliminarily determined by a temperature-versus-motor-speed relationship for the corresponding fluid, said characteristic being set for each kind of fluid.    
   
   
       2 . The controlling system for the cooling fan according to  claim 1 , wherein said multiple kinds of fluids to be cooled includes a coolant for cooling an engine and a working fluid used for driving a fluid-pressure actuator.  
   
   
       3 . The controlling system for the cooling fan according to  claim 2 , further comprising an engine cooling device for cooling the engine, wherein the engine cooling device includes a cooling pump that discharges the coolant and a cooling circuit provided with a coolant cooler for cooling the coolant, and wherein the coolant cools the engine by circulating around the cooling circuit.  
   
   
       4 . The controlling system for the cooling fan according to  claim 3 , wherein the temperature sensors include a coolant temperature sensor for detecting a coolant temperature value in the coolant cooler, and a working-fluid temperature sensor for detecting a temperature value of the working fluid, and 
 wherein the motor-speed controlling means determines the target motor speed value by selecting a higher one of motor speed values determined on the basis of characteristics preliminarily determined by a coolant-temperature-versus-motor-speed relationship and by a working-fluid-temperature-versus-motor-speed relationship, the motor-speed controlling means controlling the fluid-pressure motor so that the motor speed thereof reaches the target motor speed value.    
   
   
       5 . The controlling system for the cooling fan according to  claim 4 , wherein the coolant cooler comprises a radiator, wherein the engine cooling device further includes a thermostat disposed at an intermediate position in the cooling circuit and a circulation path, wherein the cooling circuit cools the engine by allowing the coolant discharged from the cooling pump to circulate through the engine and the radiator, wherein when the coolant is in a low temperature state, the coolant output from the engine is carried back to the engine by the circulation path without passing through the radiator, and wherein the coolant temperature sensor detects a coolant temperature value in an area other than the circulation path.  
   
   
       6 . The controlling system for the cooling fan according to  claim 1 , wherein the fluid-pressure pump comprises a variable-displacement fluid-pressure pump, and 
 wherein the motor-speed controlling means includes a pump regulator for regulating a capacity of the fluid-pressure pump, and a controller that outputs a pump-capacity command signal to the pump regulator on the basis of the temperature value of the corresponding fluid detected by the corresponding temperature sensor and on the basis of said characteristic preliminarily determined by the temperature-versus-motor-speed relationship.    
   
   
       7 . The controlling system for the cooling fan according to  claim 1 , further comprising an air temperature sensor for detecting an outside air temperature, 
 wherein the motor-speed controlling means reduces the motor speed when the outside air temperature is lower than a predetermined temperature value.