A warning device associated with a rotatable body comprising means on the rotatable body for creating a magnetic field, a receiving coil on a relatively stationary member arranged such that upon rotation of the rotatable body interaction with the magnetic field causes electrical pulses to be generated in the receiving coil and an electronic switching circuit operated by the pulses such that a warning is given upon occurrence of a predetermined condition, such as pressure of a vehicle wheel deviating outside a predetermined limit.
A vehicle tire pressure warning system includes a rotating assembly and a non-rotating assembly. The non-rotating assembly includes a magnet and a pick-up coil. The rotating assembly includes a series circuit comprising a coil, a magnetically operated switch and a pressure actuated switch which is closed when the tire pressure is adequate. The magnetic switch is closed periodically by the magnet and current is induced in the coil. When the magnetic switch re-opens the coil is coupled to the pick-up coil and the flux collapse in the coil causes a signal to be induced in the pick-up coil. The absence of such a signal indicates that the tire pressure is too low and is detected by a counter system for each wheel which counts the number of pulses from all the wheels between pulses from the associated wheel.
In a device for the transmission and evaluation of measurement signals for the tire pressure of tubless tires mounted rims in single and twin wheels of motor vehicles which comprises a pressure sensor (6) arranged in the rim wall, which pressure sensor (6) is electrically connected with a signal transmitter coil (8) arranged at the rim (3), as well as a signal pick-up coil (20) of a high-frequency resonant circuit signal evaluating arrangement connected with the motor vehicle in the area of the axle so as to be stationary, it is provided for the purpose of enabling signal detection also when stationary and for problem-free application to twin tires, that a first repeater coil (15), which is electrically connected with a second repeater coil (17), is arranged in the area of the signal transmitter coil (8) at the hub (12) carrying the rim (3), which hub (12) is connected with the latter so as to be fixed with respect to rotation relative to it, wherein the second repeater coil (17) is constructed as a toroidal coil whose coil axis (18) coincides with the hub axis (11), wherein the stationary signal pick-up coil (20) is arranged in the magnetic field area of the second repeater coil (17).
This invention is concerned with a tire pressure drop alarming apparatus for signaling an abnormal pressure drop of a pneumatic tire by transforming the pressure drop into an electric signal. The apparatus comprises a resonating circuit including a resonance coil and a resonance condenser and includes a retaining body made of metal. The retaining body includes a bottom plate portion interposed between and separating the resonance coil from a vertical portion of a rim flange in such a way that the vertical portion of the rim flange can prevent effects imparting characteristics of the resonance coil, and a side plate portion integrally connected with the base plate portion to be interposed connected with the base plate portion to be interposed between and separating the resonance coil from the parallel portion of the rim flange in such a way that a parallel portion of the rim flange can prevent effects imparting characteristics of the resonance coil, the retaining body being attached to the rim flange with the base plate portion and the side plate portion not deformed.
A vehicle-mountable electrical power generating mechanism and signal transmitter, combined to constitute a self-powered generating system mountable such as on a wheel to monitor and provide an indication of certain operating characteristics of the wheel, such as the pressure of the tire mounted thereon.
A system for monitoring tire pressure preferably at each and every tire to provide an indication of low, unsafe pressure to the operator of the vehicle. The system can be used in pleasure vehicles or commercial trucks and basically comprises a sensor unit mounted to the tire rim including an actuating switch and coupling coil, and a detector unit physically unattached to the sensor unit and also including a coupling coil and associated detecting and indicating circuitry. The sensor unit rotates with the tire and rim while the detector unit, which is preferably mounted to the brake shoe, is stationary enabling inductive coupling between sensor and detector units once each revolution of the wheel of the vehicle. The sensor unit is secured to the inner surface of the rim and is compressable to operate the actuating switch. The detector unit may be powered directly from the vehicle storage battery or may tie into an existing diagnosis system of the vehicle.
