Electric supercharging device

An electric supercharging device that supercharges intake air into an internal combustion engine of a vehicle by rotating a compressor, which is not connected to an exhaust turbine, through a drive of an electric motor, the electric supercharging device comprising:

• an accelerator that accelerates a rotation of the electric motor and transmitting the rotation to the compressor;
• wherein the accelerator includes:
• a variable displacement hydraulic pump that is connected to the electric motor, is driven by the electric motor, and includes a displacement volume;
• a variable displacement hydraulic motor that is connected to the compressor, is driven by hydraulic oil supplied from the variable displacement hydraulic pump, and includes a displacement volume;
• and
• a rotation speed controller that determines a ratio of the displacement volume of the variable displacement hydraulic pump to the displacement volume of the variable displacement hydraulic motor higher than 1 by controlling the hydraulic pump and the hydraulic motor and adjusts a rotation speed of the variable displacement hydraulic motor higher than a rotation speed of the electric motor;
• wherein during an acceleration of the vehicle, the rotation speed controller is to control the variable displacement hydraulic pump and the variable displacement hydraulic motor to suppress an increase ratio of the rotation speed of the electric motor within a prescribed range and increase an acceleration ratio of the accelerator so as to increase a rotation speed of the compressor.