Mannesmann Rexroth Corporation

Alfred Feuser

Jorg Dantlgraber

Joachim Neumann

Helmut Kunkel

Walter Voxbrunner

Rudolf Schaffer

A proportional valve has an output proportional to an electrical input signal. In a preferred embodiment, the valve is actuated by a proportional solenoid having a coil which is controlled by a control signal in proportion to voltage or current. The proportional solenoid is controlled by a relatively high current such as a rectified mains voltage. A control circuit ensures that the coil of the proportional solenoid is not overloaded. Particularly, it ensures that a maximum current value is not exceeded. In this way, the mains supply required in prior art devices may be eliminated.

Control of a proportional valve using mains voltage

For path control of a plurality of drives, i.e. for driving a plurality of drives in different axes in geometrical path dependence, to obtain high accuracy it is necessary for the lag error of the drives to remain constant. According to the invention for this purpose a circuit arrangement is proposed in a cascade structure in which from the speed of each individual path drive and the control deviation determined from the actual value and desired value of the position a difference signal is formed which is integrated and added to the output signal of a P controller.

Circuit arrangement for a hydraulic drive in a position control circuit

A hydraulic driving device includes a working cylinder for moving a machine component, and an electro-hydraulic servo system. The servo system includes a servo-valve, a position-error control, a circuit for emulating speed and acceleration of the working cylinder, and a regulator for weighting the ascertained position error according to the emulated speed and acceleration, and generating a setting signal for the servo valve.

Hydraulic driving device

A machine tool comprising an axially reciprocating tool is driven by a hydraulic jack or lifting cylinder which is controlled by a servovalve. The amplitude and velocity of the lifting cylinder is set at a control circuit to which the position and acceleration of the lifting cylinder are applied as input variables. The electrohydraulic control has a high damping and high gain. As a result the velocity change of the lifting cylinder when the tool enters the workpiece is negligibly small.

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Lohr-Rodenbach, Germany

Alfred Feuser