Hydraulic system with mechanism for relieving pressure trapped in an actuator

摘要

Pressure trapped in an inactive hydraulic actuator can result in the actuator moving in a direction which is opposite to that desired upon subsequent activation. The present method detects a trapped pressure condition and takes remedial action before activating the hydraulic actuator for motion. The pressure differentials across valves that control the fluid flow to and from the hydraulic actuator are used to detect a trapped pressure condition. In response to that detection, a selected valve is initially opened in a manner that releases the trapped pressure while producing motion in the desired direction. After the trapped pressure condition has been resolved, one or more other valves are operated to produce the desired motion of the hydraulic actuator.