ELECTROHYDRAULIC VALVE CALIBRATION SYSTEM AND METHOD

摘要

A valve calibration system and method is disclosed for an electrohydraulic valve having upstream and downstream sides. A valve current controls the valve orifice size connecting the upstream and downstream sides. The calibration method includes opening the valve, stalling the system to prevent volume changes, and closing the valve with substantially equalized upstream and downstream pressures; then increasing upstream pressure, and finding a calibration current that provides a calibration orifice size through the valve by monitoring downstream pressure. Finding a calibration current can include stepping through valve control currents, sensing downstream pressures, and calculating step orifice sizes until the calculated step orifice size is greater than or equal to the calibration orifice size. Finding a calibration current can include performing a coarse calibration followed by a finer calibration. An offset can be calculated for a valve characteristic relating valve control current to valve orifice size.

主权项

1. A calibration method for an electrohydraulic valve in an electrohydraulic system driven by a pump, the electrohydraulic valve having an upstream side between the pump and the electrohydraulic valve and a downstream side on the opposite side of the electrohydraulic valve from the pump, a valve control current controlling an orifice size through the electrohydraulic valve connecting the upstream side with the downstream side, the calibration method comprising:
opening the electrohydraulic valve; stalling the electrohydraulic system to prevent volume changes in the electrohydraulic system during calibration; closing the electrohydraulic valve with the upstream and downstream sides of the electrohydraulic valve substantially equalized at an equalization pressure; increasing pressure on the upstream side of the electrohydraulic valve to an increased pressure using the pump, the increased pressure being greater than the equalization pressure on the downstream side of the valve; and finding a calibration valve control current that provides a calibration orifice size through the electrohydraulic valve by monitoring pressure on the downstream side of the electrohydraulic valve.