Patent ID: 7673452

Claim:
A motor-driven supercharger comprising: (a) an electric motor disposed to accelerate and assist rotation of a compressor impeller, wherein the electric motor is disposed within a center housing and wherein the center housing is arranged between a turbine housing and a compressor housing; (b) an electric motor side cooling fluid flow path arranged to flow cooling fluid so as to cool the electric motor; (c) a turbine side cooling fluid flow path arranged to flow cooling fluid coming from the electric motor side cooling fluid flow path and to circulate cooling fluid so as to cool a portion of a turbine impeller side of the center housing, wherein a turbine impeller is disposed on the turbine impeller side of the center housing; and (d) a cooling fluid flow rate adjusting device for adjusting a flow rate of cooling fluid, wherein the cooling fluid flow rate adjusting device comprises i. a flow rate adjuster arranged to supply cooling fluid via the electric motor side cooling fluid flow path, and arranged on a cooling fluid supply line that supplies cooling fluid to the center housing, wherein the flow rate adjuster is operable to switch a first flow rate and a second flow rate; and ii. a controller disposed to control the flow rate adjuster, wherein the controller receives a signal of a temperature of cooling fluid from a first temperature meter and a signal of a temperature of the electric motor from an electric motor temperature meter, wherein the controller operates to control the flow rate adjuster to set the flow rate of cooling fluid to the first flow rate for cooling the electric motor in a first temperature state when a temperature difference obtained by subtracting the temperature of cooling fluid from the temperature of the electric motor is equal to, or more than, a predetermined temperature that is equal to or greater than zero, and the controller operates to control the flow rate adjuster to set the flow rate of cooling fluid to the second flow rate that is smaller that the first flow rate and that is used for suppressing a heating operation of the electric motor in a second temperature state when the temperature difference is lower than the predetermined temperature that is equal to or greater than zero, wherein the flow rate adjuster has an opening and closing valve and a fixed orifice that are provided in parallel on the cooling fluid supply line, and the controller controls the opening and closing valve on the basis of the temperature of the electric motor and the temperature of cooling fluid, wherein the flow rate of cooling fluid comes to the first flow rate in a first valve state in which the opening and closing valve is open, and the flow rate of cooling fluid comes to the second flow rate in a second valve state in which the opening and closing valve is closed.