PURPOSE: To perform fault diagnosis objectively and highly accurately by detecting vibration when an exhaust valve comes into contact with a valve seat, detecting a crank angle when the exhaust valve comes into contact, analyzing the vibrating frequency at this time, comparing the frequency with the analyzed value of the vibration frequency obtained at the normal time beforehand, and judging the presence or absence of the fault of the exhaust valve.
CONSTITUTION: Vibration when an exhaust valve 104 comes into contact with an exhaust valve seat 105 is picked up by a vibration sensor at good timing, and the frequency is analyzed. The rate of the high frequency spectrum occupied in the entire spectrums is computed. Whether the valve is normal or abnormal is judged based on the magnitude of the value. Since the high frequency vibration tends to attenuate quickly, a powerful magnet 111 is mounted in the sensor 110 so that the searching point for the vibration source can be freely changed. A rotary-angle detecting sensor 119 is used for detecting the seating timing of the exhaust valve 104. The movement of a pin 118 which is provided at a flywheel 108 and the like is detected, and a crank angle is computed. In this way, the fault diagnosis of the exhaust valve 104 can be performed objectively and highly accurately.
TAKAISHI TAKEO
GOTO KEIZO
KOGA MIKIO
KUWAGAE SHIYOUICHI
| JPS639833A | 1988-01-16 | |||
| JPS646540B2 | 1989-02-03 |