| 摘要 |
1,197,745. Fluid-pressure servomotor systems. DRESSER INDUSTRIES Inc. July 12, 1967 [July 18, 1966], No. 32048/67. Heading G3P. An apparatus responding to a change in a variable, such as fluid pressure, temperature, fluid flow, motion or weight, has a device 12 adapted for bi-directional movement from a null position in response to the variable condition, a pneumatically operated sensing device 15 providing a first signal in response to movement of the control device in one direction from the null position and a different signal in response to movement of the control device in a different direction from the null position, a bi-directional drive mechanism 36 actuated by the sensing device, a feedback mechanism 48, 49, 44 and 42 to return the device 12 to the null position, and a readout mechanism 51 actuated by the drive mechanism. The device 12 consists of a vane member connected to a Bourdon tube 13 by a lever arm 14 to regulate the flow between pairs of aligned nozzles 16, 21 and hence the pressure applied to diaphragms 27, 28 which hold valve members 31, 32 closed against spring pressure. When vane movement allows one of the valves to open the drive mechanism is rotated to actuate the mechanism 51 and a pen 54 in contact with a travelling paper strip 55 brought into periodic contact with raised digital wheels 57 on a printing counter 52. At the same time, a lead screw 44 for actuating the pen applies feedback through a spring 42 to the Bourdon tube 13. In the first modification, the mechanism 36 actuates a valve, rheostat or switch assembly through a drive comprising a spring, belt, a pulley and a differential gear which is also connected to a manually set reference counter. A second modification, uses a lever adjustably connected to the vane 12 and the feedback spring, the lever being actuated by a pair of membranes responding to the pressure drop across a flow restrictor. The sensing device 15 may be replaced by pneumatic volume relays 119, 121, Fig. 6 controlled by flow restrictors 117, 118 in the supply line to a single pair of nozzles 112, 113 between which the vane member 124 may be moved longitudinally by the Bourdon tube 13. |
