US Patent 7926530 Device for generating tire air pressure

A tire-air-pressure-generating apparatus includes an air pump, a pressure control valve, and an adjustment device, which are disposed coaxially in a shaft portion of an axle hub. The air pump includes a pump chamber located in the interior of the axle hub. The pressure control valve and the adjustment device are assembled into a cylinder head, which is assembled airtightly and removably to the axle hub. The cylinder head includes a suction-discharge path, discharge paths, pressure lead paths, and a suction path.