Patent ID: 7438046

Claim:
A failure detection apparatus for detecting failures of a variable valve timing and lift control system in an internal combustion engine, said variable valve timing and lift control system adapted to switch opening/closing timing or lift amount of a valve depending on operating conditions, said apparatus comprising: a sensor for sensing a vibration inside a cylinder; means for extracting a component of seating sound of the valve from the output signal of said sensor; means for determining an actual seating time of the valve from said component of seating sound; means for calculating a target seating time of the valve-based on at least one of requested lift amount, requested advance angle, and requested open angle of the valve which are determined depending on operating conditions; means for correcting the actual seating time according to stationary deviation between the actual seating time and the target seating time, said stationary deviation caused by degradation or unevenness of the sensor; and means for comparing the corrected actual seating time with the target seating time to determine a failure of the variable valve timing and lift control system.