| 摘要 |
A two-stage flow-control electrohydraulic servovalve has a pilot-stage (14) and a second-stage valve spool (6) mounted for sliding movement relative to a body (1). The pilot-stage (14) is arranged to provide an output pressure, which is used to selectively displace the second-stage spool (6) relative to the body, to establish flow through the second-stage. The second-stage spool has a plurality of lobes, which are overlapped with respect to passageways communicating with the control ports (3,4). A spool position feedback servoloop is closed about the second-stage valve spool and the pilot-stage. The improvement provides a compensation circuit (21) for modifying the command signal (ec) so as to compensate for the "dead zone" in the normal second-stage flow-to-displacement characteristics, such that the second-stage output flow will be substantially proportional to the command signal.
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