| 摘要 |
PURPOSE:To ensure the detection of the decrease of air in a tire and to simplify a structure, by sealing a liquid, which reflects radio waves, in a flat bag body comprising a material, which does not reflect the radio waves, and utilizing the movement of the liquid caused by the change in the air pressure in the tire. CONSTITUTION:An air bag 12 and a container 13 are provided in an outer frame 11 having many holes. A liquid 14, which reflects radio waves, is sealed in the container and communicated to a flat bag body 15 located outside of the outer frame 11. When the air pressure in the tire is decreased to the value lower than a specified pressure, the air pressure in the air bag 12 is not changed, but only the outside pressure is decreased. Therefore, the air pressure in the air bag 12 becomes relatively higher than the outside pressure. The pressure is applied to the outside of the container 13. Then the container 13 is contracted, and the internally sealed liquid 14 is pushed into the bag body 15, which is communicated to the container. Since the liquid 14 has property of reflecting the radio waves, the liquid 14 receives the radio waves from a radio wave transmitter 5 and reflects it. The radio wave is received by a radio wave receiver 6 and processed in a data processing device 7. The result is displayed on a display device 8. |
