| 摘要 |
PURPOSE:To find variation in air pressure, not to mention an abnormal state in its early stage and to prevent an accident caused by abnormal air pressure by using a magnetic detecting means to detect variation in magnetic field corresponding to the displacement of a magnetism generating body and measuring the air pressure of a tire, and measuring and displaying the air pressure during a vehicle run successively all the time. CONSTITUTION:While a vehicle runs, a permanent magnet 18 rotates together with the tire 14, but a magnetic sensor 21 does not rotates. When the permanent magnet 18 moves from the center point of the magnetic sensor 21, an AC output is obtained from the magnetic sensor 21. The AC output obtained from the magnetic sensor 21 and amplified by an amplifying circuit 22 is outputted to a display meter 25, where the tire air pressure is displayed. In this state, if the tire air pressure drops, bellows 15 contract to increase the clearance between the permanent magnet 18 and magnetic sensor 21 gradually. As the clearance l is increased, the output of the magnetic sensor 21 decreases. Consequently, the tire air pressure value on the display meter 25 decreases with the output. |
