| 摘要 |
A pneumatic sensor switch for giving a warning signal if a pneumatic vehicle tire has too low pressure has a gas-filled chamber (11), separated from the inflation space in the tire by a flexible diaphragm (8) cooperating electrically with a metal part (16) in the chamber to form an electric switch open at safe pressures in the tire and closed at dangerous lower pressures. There is an electric circuit with battery (4) and transmitter (5) to transmit warning signals to the outside if said switch is closed. There may be a second chamber (13) with electric switch contact means, filled with gas at a lower pressure and also separated from the inflation space in the tire by a flexible diaphragm (10) so that said contact means are open at atmospheric pressure therein and closed by the diaphragm at higher pressures. The electric switch means of both chambers (11, 13) are connected in series so that a warning signal is only given at pressures in the dangerous range, when both switches are closed, and not at atmospheric and at safe operating pressures in the tire. There may be a roll switch in one of the chambers to interrupt the electric circuit when the device is stationary. The diaphragm (8) may have mechanical contact means or operate such means through compression of the gas in the closed chamber (11). There may be more than one such sensor, operating at mutually different tire pressures. The gas filled chambers make the device take up the same temperature as the inflation space in the tire, so that the device adapts itself adequately to differing temperatures in the tire.
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