Servo pneumático e servo

摘要

A pneumatic servo comprises a motor (10) having a shaft for rotation in response to an electrical signal. A cam (14) is connected to the shaft for rotation therewith. The cam (14) has an outer profiled periphery and opposite sides. A pneumatic nozzle (16) having an opening for directing a flow of gas towards one side of the cam (14) near the periphery, obscures the flow by different amounts as the cam (14) rotates to create a back pressure in the nozzle (16) thereby providing a pneumatic signal. A curved projection (30) engages an opposite side of the cam (14), the projection being aligned with the nozzle (16) opening and reducing oscillation excursions of the servo at gas pressures in the nozzle (16) above 12 psig (83 kPa-gage).