GB725599A - Improvements in follow-up mechanism for servomotor control apparatus - Google Patents

Abstract

725,599. Fluid-pressure servomotor-control systems. ELECTROL, Inc. April 15, 1953, No. 10319/53. Class 135. A follow-up mechanism for a control unit comprises a slidable member 20, 35 resiliently urged against the closed outer end of a rotatable and axially movable sleeve member 40 for axial movement therewith, and a member 46 concentric with and rotatable relative to the sleeve member but restrained against axial movement relative to a support 11 for the slidable member the members 40, 46 having co-operating inclined planes whereby on relative rotation of either of the members the sleeve member 40 and the slidable member will be moved axially, and one of the members 40, 46 being movable by a control member and the other by a member controlled by the control member. Fig. 1 shows the application of the invention to the control of a valve unit 10 adapted to control the supply and exhaust of hydraulic fluid to a hydraulic motor or jack actuating an aircraft wing flap or other member to be controlled. An externally threaded sleeve 40 operated for instance manually by a lever 41 screws into a correspondingly threaded rotatable sleeve 46 held against axial movement by a flanged ring 48. The sleeve 46 is rotated by movement of the jack or motor by a lever 49 secured in adjusted position by a screw 50. The slidable member comprises a cam-shaft 20 with an extension 35 held in engagement with a plug 43 in the end of the sleeve 40 by a spring 25. The shaft 20 is held against rotation by fingers 31, 32 on a retaining ring 30 engaging grooves 33, 34 in the cam-shaft. The cam-shaft operates in a bore 27 communicating with a pressure supply port 16 and an exhaust port 17. The ports 16, 17 are adapted to be selectively connected to ports 18, 19 leading to opposite sides of the jack or motor by lift valves 12, 13, 14, 15 opened by the cam surfaces 21, 24, 23, 22 respectively. Downward movement of the shaft 20 opens the inlet valve 12 and the exhaust valve 14, whilst upward movement opens the inlet valve 15 and the exhaust valve 13. Other types of inclined plane or camming elements may be used instead of the screw-threads on the sleeves 40, 46. The cam-shaft may be moved positively by the sleeve 40 in both directions, the spring 25 being omitted if desired. The levers 41, 49 may be replaced by pulleys or gears especially where rotary motors are employed. The camshaft may alternatively operate switches controlling an electric motor.