| 摘要 |
Tyre pressure indicator for indicating the pressure in a tyre, mounted on a vehicle wheel, irrespective of whether the wheel is stationary or rotating, having a passive resonator which is composed of a first coil, a capacitor which is attached in the tyre and a second coil which is attached in the wheel rim coaxially with respect to the wheel, said components being connected one behind the other, and having a pressure-sensitive element which is attached in the tyre and in the case of pressure changes acts on a ferrite rod in order to displace the latter and thus change the inductance of the first coil. An oscillator is connected to the vehicle frame and has a third coil which is magnetically coupled to the second coil and is set to the same frequency as the passive resonator when the tyre pressure has the expected value. In this state, the passive resonator absorbs energy from the third coil and thus damps the oscillator. In the case of a change in the tyre pressure, thanks to the magnetic coupling the oscillator supplies an output signal which is then amplified and rectified and permits an indication of the pressure. <IMAGE>
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