Abstract: A self-opened type valve is opened by motor torque of an electric motor. Therefore, a diaphragm is not necessary for opening the valve, and downsizing of a valve drive apparatus for opening the valve is possible. Since the valve is assembled to the motor shaft of the electric air pump via a motion-direction conversion mechanism, an opening action of the valve can start in a short time after a rotational action of the impeller of the electric air pump starts, so that control responsiveness is improved. At a rotation stop of the impeller of the electric air pump, the valve can be maintained in a fully closed condition by an urging force of the coil spring, thereby preventing exhaust gases or condensed water from entering into an inside of the electric air pump.

Abstract: In an air supply pump, having an electric motor and a blower driven by the electric motor, the blower has an impeller having multiple blades for compressing and pumping out the air. A value (F) obtained by a formula (F=N×S) is made to be higher than the audible frequency band to the human beings, wherein “N” means number of blades of the impeller, and “S” means a number of rotation of the impeller for each second at a normal rotational speed. (“×” is a symbol for a mathematical multiplication.) The frequency (F=N×S) of fan noises at a primary peak appears at higher frequencies out of the audible frequency band, so that the noises audible to the human beings can be reduced.

Abstract: A pump unit (14) has an air pump and a valve device, wherein the valve device has a pressure chamber and a pressure control device, so that the air from the air pump is introduced into the pressure chamber and the pressure in the pressure chamber is controlled by the pressure control device. The pump unit has an outlet port, an opening of which is controlled by a valve body driven by a diaphragm, so that the amount of the air to be supplied through the outlet port is controlled by the pressure of the pressure chamber.