Importance

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Abstract

A hydraulic servovalve is controlled electrically through electromagnetic means. Electrical currents applied to force motors determine the relative position of a single, displaceable control assembly within the valve. Displacive movement of the control assembly changes, in reciprocal proportion, the inlet and outlet flow-metering clearances in each of the chambers of this open-passage type valve. The position of the control assembly determines the inlet and outlet flows within, and, therefore, the net flow through, each chamber. Moreover, since the chambers are each connected (either directly, or through a flow-impeding orifice) to one of the control ports, the position of the control assembly thereby determines the control flow delivered by the valve. Generally, both hydrostatic and hydrodynamic forces within the valve are balanced against corresponding forces, all acting upon the control assembly. However, any internal unbalanced hydrodynamic forces--which arise in proportion to control flow--are compensated by opposing hydrostatic forces, creating a naturally stable servovalve over a wide range of operating conditions.

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First Claim