| 摘要 |
<p>A valve cap adapted to be screwed onto the tire valve of a pneumatic tire generates a wireless transmissible pressure drop indication signal. The valve cap comprises a valve cap housing comprising a pressure chamber and a reference chamber. The non-blockable pressure chamber is in communication with the tire pressure to be controlled. The reference chamber is pressurized with a desired pressure whenever the valve cap is screwed onto the tire valve. A signal generating means including transmitter means, power supply means and switching means is provided within said valve cap housing. The switching means comprises a conductor section fixedly arranged within the pressure chamber a short distance from a rest position of a deflectable diaphragm. Any tire pressure drop will deflect the diaphragm into the pressure chamber and will complete an electrical circuit whereupon a transmitter circuitry is supplied with voltage/current, and the transmitter means generates a pressure drop indicating signal of limited duration.</p> |
