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US 4,959,581 AGranted
Servo valve having a piezoelectric element as a control motor
AssigneeMannesmann Rexroth GmbH
InventorJorg Dantlgraber
Life of this patent
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Abstract
A control motor for a servo valve is provided. The control motor comprises a control element which can carry out a pivotal movement due to an electric input signal supplied to said motor. The movement of the control element causes a corresponding change of hydraulic resistances and, as a consequence, changes in hydraulic output signals of an hydraulic amplifier actuated by said motor.
Claims28
An electrohydraulic pressure transducer apparatus comprising:
- a control element comprising a piezoelectric element,
- electrically actuated means for causing a movement of said control element for carrying out a control function so as to change a hydraulic output signal in accordance with an electric input signal, wherein
- the control function is provided for by a front face of said control element, the moment of resistance of the control element is small in the direction of movement of the control element, but large in the direction in which the force created by the pressure of the hydraulic output signal acts, the front face of the control element has a recess defined therein which is connected with a source of pressure medium, and said recess is connected with stationary recesses which are connected with control ports in the housing or cover of the apparatus.
A control apparatus in cooperation with a hydraulic amplifier, said apparatus comprising:
- a housing having a pump port, a tank port and at least two control ports,
- a frame,
- a control element fixedly mounted in said frame in such a manner that the application of a small electrical input signal to said control element will cause a proportional movement of said control element in a direction of movement,
- wherein said control element forms one or a plurality of control surfaces,
- means for creating a control function together with the control surface(s) of the control element so as to generate hydraulic output signals at said control ports which correspond to said movement of the control element, and
- wherein one control surface is provided at the control element in substance parallel to the direction of movement such that the control function cannot create a force component in or opposite to the direction of movement inasmuch as the force components act substantially perpendicular to the direction of movement;
- wherein only one control surface is provided at the control element and only one control surface is provided at a component which is stationary with respect to the housing, said stationary component being located adjacent to said first control surface;
- wherein the control element fixedly mounted to said frame can be adjusted with respect to its 0- or initial position, wherein the adjustment of the 0- position of the control element being effected by means of a screw using the resilient regions of the frame to transfer an adjustment force onto the control element.
5 more elements
An electrohydraulic pressure transducer apparatus comprising:
- a control element,
- electrically actuated means for causing a movement of said control element for carrying out a control function so as to change a hydraulic output signal in accordance with an electric input signal, wherein the control function is provided for by a front face of said control element, the moment of resistance of the control element is small in the direction of movement of the control element, but large in the direction in which the force created by the pressure of the hydraulic output signal acts, and a housing or cover of the apparatus has at least one recess defined therein substantially in facing relation to said front face of said control element, said at least one recess being connected to at least one of a source of pressure medium, tank, and a control port.
Dependencies are inferred from the claim text.