Abstract: Alarm system for monitoring pressurized vehicular tires for their gas mass, basically comprising a wheel unit for at least some of the tires of the vehicle, and a common receiver. Each wheel unit has an antenna made of a flexible material in the form of an open annulus, suitable to be snapped into and held by its resilience against the inner periphery of the respective tire, a continuous wire loop being embedded in the annulus for transmitting signals but optionally also for receiving power. At symmetrical location about the inside of the antenna, an electro-magnentic power generator module, a gas-mass monitoring sensor module, and a signal transmitter are mounted, electrically interconnected, for giving a preferably two-bit signal indication to the common receiver. The latter may have signal decoding and alarm circuitry to display at least two different conditions, namely a warning and an alarm condition.

Abstract: An electromagnetic power generator for installation in the interior of a vehicular tire, working on the principle of deriving energy from the fact that a portion of the tire becomes flattened once every revolution, causing a change in the length of the corresponding chord. A small closed magnetic circuit is alternately opened and closed by this movement, by means of a flexible strap coupled between the tire interior and the magnetic circuit. The circuit is reclosed by magnetic attraction.

Abstract: A vehicle tire gas mass sensor having a sealed cylinder containing a non-toxic and inert gas. The cylinder is sealed at one end with a diaphragm and contains a sealable plug at an opposite end for admitting the inert gas. Sealing is permanent after the introduction of gas. The diaphragm moves freely in response to pressure differential between the inside predetermined pressure of the inert gas and pressure existing in the environment in which sensor is installed. The sensor is defined by a first, second and third contacts which are responsive to diaphragm movement caused by pressure differentials in the cylinder. In turn opening and closing of the contacts actuates alarms for indicating such pressure differential. Equilibrium conditions as between the interior and environment of the sensor are reflected by the movement of diaphragm to compensate for temperature variation occurring at these locations.