G. L. Rexroth Gmbh

Mannesmann Rexroth Corporation

Roland Ewald

Herbert Lembke

Wolfgang Lukasczyk

Andreas Grimm

A control for a hydraulic drive or actuator is provided, wherein the actuator has pressurized operating fluid applied thereto, and wherein the operating fluid is directed through an electrically controlled valve for establishing the amount of operating fluid to be fed to the actuator. An electrical signal for controlling the valve is provided by a computing device. In the computing device, a predetermined desired value for the position (or travel), force, or pressure of the actuator or drive is continuously calculated based, at any given time, at least on one measured or simulated state variable indicative of a condition of the drive or actuator at the time of calculation. The calculated desired value determines the amplitude of the electrical signal directed to an electrical actuating device of the valve. The computing speed of the computing device for determining the respective desired value is faster than the actuating velocity or speed of the valve.

Control for hydraulic drive or actuator

A compensating valve arrangement is connected between a throttling direction control valve or proportioning valve which controls fluid flow from a pressure source to a load. The compensating valve is provided with a pressure reducing valve, check valves and throttling points between the pressure supply and the control piston of the compensating valve to compensate for surges, prevent sudden driving of the load and prevent leakage.

Apparatus for the control of a hydromotor

A pressure control valve construction comprising a valve body having an inlet port adapted for connection to a pressure source, a pair of working ports adapted for connection to respective loads, and a pair of outlet ports connected to a reservoir. A control spool is movably mounted in a bore in the body and includes lands for respectively controlling communication between the inlet port and respective ones of the working ports and between the working ports and the outlet ports. The control spool has opposite ends with blind bores respectively provided therein, and sensing spools are respectively mounted for sliding movement in the blind bores to define spaces between the bottoms of the blind bores and the sensing spools. The spaces communicate with the working port via respective openings in the control spool. In the case of a double acting valve, an actuator is provided at each end for acting on a respective sensing spool whereas for a single acting control valve only one actuator is provided.

Pressure control valve

An apparatus for controlling a single action piston and cylinder having means biasing the piston toward a retracted position within the cylinder and having a non-return valve openable toward the cylinder connecting the cylinder with a fluid pressure source comprises a control valve and a proportional valve. The control valve has an inlet in fluid communication with a supply tank, an outlet in fluid communication with a supply tank, a control port in fluid communication with the fluid pressure source, and a control element movable between open and closed positions for controlling flow of fluid pressure from the inlet to the outlet. The control element is spring biased toward the open position and forced toward the closed position by pressure entering through the control port. The proportional valve regulates the pressure entering through the control port.

Apparatus for controlling a single action operating cylinder, especially

A multi-position flow control valve comprises a control piston movable in a boring in two opposite directions. At each end of the boring a pressure chamber is provided accommodating a pressure spring supported on a spring collar that at its end facing the boring has a conical recess. Each recess accommodates a conical projection of a supporting rod that is slidably guided in a blind end bore provided in the control piston. A spring is arranged in the blind end to urge the supporting rod into engagement with the recess in the spring collar. If a pressure fluid is introduced into one pressure chamber, it displaces the piston and compresses the biasing spring in the other pressure chamber whereby the spring biased supporting rods remain in engagement with the recesses in the spring collars.

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Lohr, Germany

Roland Ewald