| 摘要 |
<p>PURPOSE:To enhance reliability in the decision of failure of solenoid by comparing a control signal and a detection signal at the timing of sampling signal having period sufficiently shorter than the pulse period of driving signal and making a decision that a solenoid has falied if a state where comparison results do not match each other sustains longer than a predetermined interval. CONSTITUTION:A CPU 11 outputs an ON/OFF control signal C depending on the operating conditions and subjects a solenoid 6 to duty driving according to a driving signal A through a drive circuit 13. On the other hand, the driving signal A is fed back through a detecting circuit 14 and the voltage at one end of the solenoid 6 is inputted as a detection signal D. A timer in the CPU 11 generates a sampling signal and ON/OFF states of the control signal C and the detection signal D are compared for every period of the sampling signal. A decision is then made whether the mismatch interval sustains longer than a set interval. The set interval corresponds to the minimum pulse width of the control signal C.</p> |
