Abstract: A device for maintaining a desired inflation pressure within a tire mounted on a wheel of a vehicle which includes a microcompressor having a flexible compression chamber and a magnetic element not on the wheel. As the compressor passes the magnet each wheel revolution, a small amount of atmospheric air is pumped into the tire, if needed. The magnet and the compressor need no other contact with the vehicle or the wheel and require no energy source on the wheel. An alternative embodiment uses an electrical coil on the wheel to pass the magnet inducing a voltage that drives a compressor on the wheel. As the coil passes the electromagnet it provides a split transformer that transfers electrical power to the wheel and permits two-way pulse data communication between the wheel and the vehicle.

Abstract: A battery-powered tire pressure monitor and inflation system which is mounted entirely on or within a vehicle wheel, preferably on the inner surface of a wheel cover. The entire system rotates concurrently with the vehicle wheel, thereby eliminating the need for any interconnection between non-rotating and rotating components of the vehicle. The preferred system also incorporates a centrifugal intake valve apparatus, which remains closed until the vehicle wheel exceeds a minimum rotational rate. The centrifugal intake valve closure apparatus thereby prevents fluids or particles from being drawn into the compressor.

Abstract: A device for automatically maintaining desired air pressure within a vehicle tire utilizes deformation of the rotating tire where it contacts the road surface to operate an air compressor. The air compressor is formed in the wheel and connected to the tire, the compressor responsive to deformation of the tire causing compressed air to pass into the tire. The compressor is preferably of a reciprocating piston type having a cylinder adapted to receive a sliding piston, the piston preferably slidably received within a plunger in contact with the inside of the tire. A spring is preferably disposed between the plunger and the piston to limit the motion of the piston to a fixed displacement less than the deformation of the tire, such that the tire inflation system is operable for a wide range of deformations of the tire.