SELF COMPENSATION FOR DUTY CYCLE CONTROL

摘要

A valve control assembly (10) controls the flow rate of a liquid through a solenoid valve (11) by repeatedly opening the valve (11) for a predetermined time. The control assembly (10) includes a timer (30) for providing a pulsed signal having a pulse width proportional to flow rate to energize and deenergize the operating coil (24) to open and close a valve sealing element (20). A nominal delay time is provided between the start time of the pulse and actual movement of the valve element (12). With each pulsed signal, the actual movement time of the valve element (12) is compared to the nominal delay time providing a deviation time. The deviation time is added to the original pulse width to obtain an adjusted pulse width, which when supplied to the operating coil (24), will effectively maintain the valve element (12) consistently open for the predetermined time.