| 摘要 |
PURPOSE:To monitor the condition of operation of a solenoid valve by a method wherein there are provided a unit for sensing a full-open time for use in measuring a time until the valve is fully opened and a discriminating circuit for comparing the measured full-opened time with a predetermined time and judging if their difference is less than the error. CONSTITUTION:When a valve-open signal for a solenoid valve is applied to an input terminal IN, electric current is flowed to the ground from power supply +V through a transistor TR, solenoid coil L and resistor R1 and a voltage proportional to an electric current flowed in a solenoid coil is generated in the resistor R1. Unit A for sensing a variation of time is composed of an integrating circuit having a resistor R2 and a capacitor C, and a comparator 1 so as to make a substantial uniform wave form. In turn, the unit B for sensing the full- open time is composed of a flip-flop 3 and a counter 4. The flip-flop 3 is set by a starting end of the open-valve signal, reset by the pulse F, so that its output has an output pules width being equal to a full-open time. |
