Leakage detecting device for evaporating fuel processing apparatus

A leakage detecting device for an evaporating fuel processing apparatus, to detect leakage of evaporating fuel in a ventilation apparatus that includes a fuel tank and a filter for absorbing fuel evaporating in the fuel tank, the leakage detecting device comprising:

• an electric pump that includes a motor portion and a pump portion for generating at least one of pressurizing force and de-pressurizing force, wherein the electric pump produces a pressure difference between an inside of the ventilation apparatus and an outside of the ventilation apparatus in accordance with said at least one of pressurizing force and de-pressurizing force to detect a leakage condition of the ventilation apparatus;
• a rotation speed controller that controls rotation speed of the motor portion;
• a pressure detector that is connected between the electric pump and the fuel tank for detecting pressure in the ventilation apparatus and said pressure difference;
• and
• a reference detector that detects a reference pressure difference which is produced using the electric pump to generate said at least one of pressurizing force and de-pressurizing force through a reference orifice,
• wherein the rotation speed controller detects rotation speed of the motor and corrects the rotation speed of the motor so that the reference pressure difference coincides with a predetermined pressure difference, and
• the leakage detecting device further comprising:
• a rotation speed storage that stores the rotation speed of the motor portion, which is corrected by the rotation speed controller, as a detecting rotation speed,
• wherein the rotation speed of the motor portion is controlled at the detecting rotation speed when the leakage condition of the ventilation apparatus is detected.

A method of detecting leakage of evaporating fuel in a ventilation apparatus that includes a fuel tank and a filter for absorbing fuel evaporating in the fuel tank, the method comprising:

• generating at least one of pressurizing force and de-pressurizing force with an electric pump that includes a motor portion and a pump portion, wherein the electric pump produces a pressure difference between an inside of the ventilation apparatus and an outside of the ventilation apparatus in accordance with said at least one of pressurizing force and de-pressurizing force to detect a leakage condition of the ventilation apparatus;
• detecting pressure in the ventilation apparatus using a pressure sensor connected between the electric pump and the fuel tank;
• detecting said pressure difference in accordance with said pressure in the ventilation apparatus;
• detecting a reference pressure difference which is produced using the electric pump to generate said at least one of pressurizing force and de-pressurizing force through a reference orifice;
• detecting rotation speed of the motor and controlling the rotation speed of the motor portion such that the reference pressure difference coincides with a predetermined pressure difference;
• and
• storing the rotation speed of the motor portion as a detecting rotation speed,
• wherein the rotation speed of the motor portion is controlled at the detecting rotation speed when the leakage condition of the ventilation apparatus is detected.