Electromagnetic generator for use in tyre pressure warning sensor - includes magnetic circuit carrying wire coils in which current is induced when circuit is intermittently broken by flexing of tyre

摘要

The electromagnetic generator includes a U-shaped piece of magnetic iron (124) on which two multi-turn coils (125) are wound. These two coils are connected by a wire (125a), and have output connections (129,b). The magnetic circuit is completed by a bar (123) lying across the open ends of the U-shaped iron core. A piece of elastic material (126) lies over both the U-shaped core and the bar (123) and is attached to a plastic base. (127) The plastics base is attached to the inside surface of a tyre so that as the wheel supporting the tyre rotates, the plastics base (127) flexes and the magnetic circuit is intermittently broken. The intermittent variation in the flux through the coils induces a current which may be used to power a small transmitter sending a signal indicating the pressure within the tyre.