Predicting solenoid valve spool displacement through current analysis

A method of identifying solenoid valve transition events by analyzing the current through the solenoid coil is proposed. Solenoid valves experience lags and transition times which are non-trivial in the context of control methods that require precise valve timing. The proposed methodology allows a user to positively identify the beginning and end of valve transition events through identifying slope changes in the solenoid coil current traces. This methodology was shown to identify the timing of valve transition events with less than 7% error when compared to measuring the position of the valve spool with a laser displacement sensor. The proposed methodology is based upon measuring the current through the solenoid coil and requires no modification to the valve or valve housing to achieve these results.