| 摘要 |
1,154,947. Fluid-pressure servomotor systems. TEXACO DEVELOPMENT CORP. June 16, 1967 [June 30, 1966], No.27839/67. Heading G3P. A system for controlling flow, pressure, temperature &c. comprises a measuring unit 14 which transmits a signal proportional to the measured variable to a bias relay 17 where the signal level is reduced and transmitted via amplifier 21 to a comparator 31. The latter compares the signal with a set point signal from control unit 27 and provides an output signal only when the input is less than the set point signal. This output signal is transmitted to the control unit via a restriction 37, booster relay 41 and manual-automatic station 47. To provide bumpless transfer between manual and automatic modes, the output line communicates with line 39 through restriction 55. When the input to comparator 31 is greater than the set point, the signal in line 39 leaks away through restrictor 37. A capacitor 43 determines the RC time constant governing the build-up and decay of the signal in line 39. The system can be pneumatic, hydraulic or electrical. A typical bias relay or booster relay Fig. 2 (not shown) has a diaphragm (61) responsive on one side to signal pressure in line 15 and to the tension of spring (91) and on the other side to the output signal pressure in chamber (80). The latter is less than the pressure in line 15 by an amount dependent on the tension in spring (91). Valve (89) on diaphragm (61) controls the supply to chamber (80), the latter communicating with outlet chamber (79) which is supplied and exhausted respectively by valves (82, 86) on stem (83) controlled by double diaphragm (65, 67). The amplifier Fig. 3 (not shown) has a disc positioned by input signal bellows (101) to control the leak-off from nozzle (98). Bellows (103) provides a feedback signal to the disc. The comparator Fig. 4 (not shown) has a stack of four inter-connected diaphragms with a supplyexhaust valve (158) located between the two inner diaphragms to connect outlet (163) to supply (164) or exhaust (35a) according to whether the set point signal in chamber (143) exceeds or is less than the input in chamber (131). |
