Electric oil pump

Abstract

An electric oil pump including an electric motor, a first pump element that is driven to suck and discharge oil by output torque of the electric motor, a second pump element that is driven to suck and discharge the oil by the output torque of the electric motor, and a torque transmission switching member disposed on a torque transmission path extending between the electric motor and the second pump element. The torque transmission switching member is actuated to allow torque transmission between the electric motor and the second pump element when viscosity of the oil is not higher than a predetermined value, and interrupt the torque transmission between the electric motor and the second pump element when viscosity of the oil is higher than the predetermined value.

1 . An electric oil pump comprising:
 an electric motor;   a first pump element that is driven to suck and discharge oil by output torque of the electric motor;   a second pump element that is driven to suck and discharge the oil by the output torque of the electric motor; and   a torque transmission switching member disposed on a torque transmission path that extends between the electric motor and the second pump element, the torque transmission switching member being actuated to allow torque transmission between the electric motor and the second pump element when viscosity of the oil is not higher than a predetermined value, and interrupt the torque transmission between the electric motor and the second pump element when viscosity of the oil is higher than the predetermined value.   
     
     
         2 . The electric oil pump as claimed in  claim 1 , wherein the first pump element and the second pump element have oil suction ports and oil discharge ports, respectively, the oil suction ports of the first pump element and the second pump element and the oil discharge ports of the first pump element and the second pump element being respectively arranged in parallel with each other with respect to an oil circulation path. 
     
     
         3 . The electric oil pump as claimed in  claim 1 , wherein the torque transmission switching member is a torque sensitive clutch that is engaged when torque applied between the first pump element and the second pump element is not higher than a set torque, and is disengaged when the torque applied between the first pump element and the second pump element is higher than the set torque. 
     
     
         4 . The electric oil pump as claimed in  claim 1 , further comprising a first shaft through which the first pump element is driven, the first pump element and the second pump element being arranged in series with respect to the first shaft. 
     
     
         5 . The electric oil pump as claimed in  claim 1 , further comprising a first shaft through which the first pump element is driven, the first pump element and the second pump element being arranged in parallel with each other with respect to the first shaft. 
     
     
         6 . The electric oil pump as claimed in  claim 1 , wherein the first pump element and the second pump element have a suction port in common. 
     
     
         7 . The electric oil pump as claimed in  claim 1 , further comprising a second shaft connected with the second pump element, the torque transmission switching member being disposed between the first shaft and the second shaft. 
     
     
         8 . The electric oil pump as claimed in  claim 5 , wherein the first pump element and the second pump element have a suction port in common. 
     
     
         9 . The electric oil pump as claimed in  claim 5 , further comprising a second shaft connected with the second pump element, a third shaft that is parallel with the first shaft and connected with the first pump element, and a pair of power transmission gears through which the third shaft is connected to the first shaft.