Method of controlling electric oil pump in hybrid vehicle

Abstract

A method of controlling an electric oil pump in a hybrid vehicle controls, at an ultra-low temperature, the electric oil pump so that the number of revolutions thereof is not unnecessarily increased, so as to prevent unnecessary power consumption of the battery, thereby contributing to an increase in fuel efficiency, to prevent unnecessary noise, thereby improving the market quality of the vehicle, and to improve the endurance of the electric oil pump.

What is claimed is: 
     
         1 . A method of controlling an electric oil pump in a hydraulic vehicle, comprising:
 measuring an oil temperature of a transmission;   determining whether or not the oil temperature of the transmission is an ultra-low temperature that does not exceed a predetermined reference temperature;   controlling the electric oil pump in an open loop up to a target number of revolutions when it is determined that the oil temperature of the transmission is the ultra-low temperature; and   controlling the electric oil pump in a closed loop in order to follow the target number of revolutions after the controlling the electric oil pump in the open loop is ended.   
     
     
         2 . The method of  claim 1 , wherein the predetermined reference temperature is in a range of −10° C. or less, in consideration of an effect that a change in a viscosity of oil in the transmission takes on a formation of oil pressure in response to an operation of the electric oil pump. 
     
     
         3 . The method of  claim 1 , further comprising:
 when the oil temperature of the transmission is not the ultra-low temperature,   controlling the electric oil pump up to a reference number of revolutions in an open loop; and   performing the controlling the electric oil pump in a closed loop after the controlling the electric oil pump up to a reference number of revolutions in an open loop.   
     
     
         4 . The method of  claim 3 , wherein the reference number of revolutions at the controlling the electric oil pump up to a reference number of revolutions in an open loop is set in consideration of a responsibility of the electric oil pump based on a room temperature state, such that the reference number of revolutions is greater than a target number of revolutions at the controlling the electric oil pump in an open loop up to a target number of revolutions. 
     
     
         5 . The method of any one of  claim 1 , wherein
 the controlling the electric oil pump in an open loop is performed in duty control mode, in which only a duty value is provided to a motor of the electric oil pump, and   the controlling the electric oil pump in a closed loop is performed in proportional integration control mode, in which the target number of revolutions is followed by feeding back a number of revolutions of the electric oil pump.   
     
     
         6 . The method of any one of  claim 2 , wherein
 the controlling the electric oil pump in an open loop is performed in duty control mode, in which only a duty value is provided to a motor of the electric oil pump, and   the controlling the electric oil pump in a closed loop is performed in proportional integration control mode, in which the target number of revolutions is followed by feeding back a number of revolutions of the electric oil pump.   
     
     
         7 . The method of any one of  claim 3 , wherein
 the controlling the electric oil pump in an open loop is performed in duty control mode, in which only a duty value is provided to a motor of the electric oil pump, and   the controlling the electric oil pump in a closed loop is performed in proportional integration control mode, in which the target number of revolutions is followed by feeding back a number of revolutions of the electric oil pump.   
     
     
         8 . The method of any one of  claim 4 , wherein
 the controlling the electric oil pump in an open loop is performed in duty control mode, in which only a duty value is provided to a motor of the electric oil pump, and   the controlling the electric oil pump in a closed loop is performed in proportional integration control mode, in which the target number of revolutions is followed by feeding back a number of revolutions of the electric oil pump.