Exact position feedback of double-acting power piston in hydraulic cylinders

摘要

An apparatus for the exact position feedback of a double- acting power piston in a hydraulic power cylinder subjected to extreme environmental conditions, especially high temperatures, comprising a double-acting detecting (measuring), or follower cylinder, having a volume corresponding to that of said power cylinder and including a detecting piston the position of which is sensed by an electrical detector, wherein a pair of working spaces of power and detecting cylinders are in fluid communication with each other via a connecting pipe, while the respective other working spaces are adapted to be connected to a (pressursized) fluid pump or a reservoir through a control valve. Pressure limiting switches are each positioned in said connecting pipe as well as in the fluid line extending between the power cylinder and the control valve, and both the power piston and detecting piston each include a valve- controlled acknowledgement passage by which fluid communication can be established between the two working spaces of the power and detecting cylinders.