Direct drive type servo valve

摘要

A direct drive type servo motor in which a spool is driven directly by a force motor, the force of the force motor being balanced by the reactional force generated by a resilient member to stabilize the position of the spool to control the flow of working fluid. The resilient member is constituted by a metallic cylindrical member having holes formed in the outer peripheral surface thereof. The holes are arranged such that, when the force is applied to the cylindrical member in the axial direction, the cylindrical member produces an axial reactional force. In consequence, the generation of force component which would act to press the spool against the sleeve is avoided to reduce the friction between the spool and the sleeve to permit a smooth movement of the spool, while allowing the resilient member to have a high spring constant to improve the response characteristic of the servo valve.