| 摘要 |
PURPOSE:To precisely detect puncture, by deciding the puncture when a ratio of a continuation time of a signal greater than a fundamental level of a tire load signal to a signal greater than a tire inner pressure abnormal level is different from a predetermined reference value. CONSTITUTION:A load signal from a load detector 1 such as a load cell and a pressure sensitive switch for detecting a load to a left or right pneumatic tire is input to first and second trigger circuits 2 and 3. The load signal is divided into a signal greater than a tire load detection level L1 and a signal greater than a tire inner pressure abnormal level L2. Continuation times of both the signals are measured by timers 4 and 5. The measured continuation times t1 and t2 input to an operating section 6 to operate a ratio between the measured times t1 and t2. Then, the ratio (t2/t1) is compared with a predetermined reference value S by a comparator 7. When (t2/t1)<S, a tire inner pressure abnormality signal is input from the comparator 7 to an indicating section 8 to indicate puncture of the tire. |
