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US 10,344,885 B2Granted
Hydraulic servovalves
AssigneeMoog Controls, Inc.
InventorsIan Brooks, Christopher Pagett, Paul Guerrier
Life of this patent
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Abstract
A servovalve has a pilot stage having a piezoelectric element actuating a pilot stage spool valve, which pilot stage spool valve comprises an output control fluid line to a main stage.
Claims19
A hydraulic servovalve comprising:
- a pilot stage comprising an electric actuator arranged to actuate a pilot stage spool valve along a pilot spool axis, which pilot stage spool valve comprises:
- an output control fluid line;
- a bushing having a plurality of flow passages and an opening extending along the pilot spool axis;
- a spool body received and axially movable within the opening of the bushing to control flow in and out of the flow passages in the bushing, wherein axially directed motion of the spool body is unrestricted by the bushing;
- in which the spool body is connected to the electric actuator by a shaft extending parallel to or coaxial with the pilot spool axis and the spool body is arranged to be moved relative to the bushing, along the pilot spool axis, by the electric actuator;
- and
- in which the shaft is connected to the electric actuator via a spool adaptor such that a position of the spool body within the bushing can be calibrated by rotating the shaft within the adaptor;
- a main stage comprising a proportional main stage fluid spool valve arranged to influence the flow of a working fluid;
- in which the output control fluid line of the pilot stage spool valve is arranged to drive the main stage fluid valve to continuously vary the flow of the working fluid.
6 more elements
A hydraulic servovalve comprising:
- a pilot stage comprising an electric actuator arranged to actuate a pilot stage spool valve along a pilot spool axis, which pilot stage spool valve comprises an output control fluid line;
- a main stage comprising a proportional main stage fluid spool valve arranged to influence the flow of a working fluid;
- in which the output control fluid line of the pilot stage spool valve is arranged to drive the main stage fluid spool valve to continuously vary the flow of the working fluid,
- wherein the electric actuator comprises a piezoelectric element, the piezoelectric element being transferrable between a first position in which the piezoelectric element is undeformed, a second position in which the piezoelectric element is deformed relative to the first position in a first direction, and a third position in which the piezoelectric element is deformed relative to the first position in a second direction opposite to the first direction, and
- wherein the pilot stage comprises a clamping ring urged into contact with the piezoelectric element by a resilient element, the clamping ring comprising a plurality of slots for locking the piezoelectric element in a rotational sense.
2 more elements
Dependencies are inferred from the claim text.