The air pump is installed at the front end of the engine and consists of a centrifugal air filter and a vane pump. The air pump is driven by the crankshaft pulley of the engine through the transmission belt, and supplies a large amount of air with low pressure to the injection system.

The centrifugal air filter is installed on one end of the rotor shaft of the pump and rotates at the same speed as the pump. The role of the centrifugal air filter is to clean the air entering the air pump. The filtration principle of the centrifugal air filter is that when the impeller rotates at a high speed, the dust particles in the air have a larger mass than the air, and are separated from the air flow entering the air pump under the action of centrifugal force.
The vane pump is composed of a pump casing, a rotor, a vane, a vane sealing groove, an air inlet and an air outlet. In order to form cavities of different sizes between the vanes and the inner hole of the pump casing, the rotation centerline of the rotor does not coincide with the centerline of the inner hole of the pump casing. Driven by the pulley, the rotor rotates on an axis that does not coincide with the inner hole of the pump casing. Two blades are arranged at an angle of 180° in the groove of the rotor, and slide in the groove, and there is a sealing groove between the blade and the rotor groove.