| 摘要 |
1,131,121. Automatic speed control. MARWIN MACHINE TOOLS Ltd. Jan.24, 1967 [Jan.25, 1966], No.3209/66. Heading G3R. A variable stroke hydraulic motor is driven through a servovalve which meters the output of a source of fluid at constant pressure, and a tachometer registers the speed of the motor as an electric signal which is fed back to control the servovalve. The source of fluid is a pressure compensated pump, or a fixed output pump with a large accumulator fed through an unload relief valve. The motor may be of the swash-plate type. As shown, a constant pressure pump 10 supplies a variable stroke hydraulic motor 14 through valve 12, the motor driving a tachometer generator 16 which provides a feedback signal to control the valve to compensate for spindle loading. The feedback circuit comprises an operational amplifier 22 and a booster amplifier 24. The stroke of the motor 14 is controlled by unit 26 in accordance with signals in binary code which are decoded by a unit 30 to provide preset stroke positions, and a reference voltage for the amplifier 22 through generator 32. Speed is restricted by an indicator 34 and logic unit 36. In another embodiment, the amplifier 24 is fed by two pressure transducers indicating the difference in pressure across the servovalve and the motor respectively. |
