Patent ID: 7963185
Filing Date: 2011-06-21
Classification: F15B,F16K,H02K,Y10T

Abstract:
1. A stepper motor driven actuator comprising: a stepper motor; a cam operatively connected to the stepper motor, the cam rotating position in response to stepping of the stepper motor, the cam positioned within a valve body having an inlet port, a rod port, a head port and at least one drain port; a control piston positioned within the valve body and having a nozzle positioned on a first side of the cam in close proximity to a surface of the cam and movable between a null position and flow positions, the nozzle having a flow path leading from a first end of the control piston, the control piston further including a means for applying a force on a second end of the control piston, the control piston moving as a result of a pressure imbalance at the ends of the control piston occurring in response to a change in position of the cam; and an actuator having a piston integral to a rack that is operably coupled to the cam, the piston having a first side and a second side, the first side being in fluid communication with the head port and the second side being in fluid communication with the rod port, the cam moving in response to the rack moving.