| 摘要 |
1,170,616. Automatic control. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. Feb.27, 1967 [Feb.28, 1966], No.9142/67. Heading G3R. The ratio of two variables is controlled in dependence on a third by applying a voltage corresponding to the latter to charge a reservoir condenser which is differentially charged from an auxiliary condenser which is, in turn, charged through switching means operated at a frequency dependent on one of the two variables and from a voltage source dependent on the other of the two variables, the resultant reservoir condenser voltage controlling the ratio of the two variables. As described, the rates of flow of petrol and butane supplied to a mixing conduit are measured by turbine type meters which respectively operate switches 45, 46, Fig. 2, at corresponding frequencies so that condensers 40, 41 are correspondingly charged and then discharged in opposition into an integrating amplifier 50 associated with a reservoir feedback condenser 51. The output of amplifier 50, which represents deviation of the flow ratio from a predetermined value, restores the flow ratio to the predetermined value by controlling a valve (not shown) in the butane supply conduit. To maintain a desired volatility of the mixture an electrical signal 21 dependent on its vapour pressure is compared at 20 with a signal 22 representing desired vapour pressure so that any difference is applied through an integrating amplifier 23 and variable resistor 27 to the input of amplifier 50 to vary the flow ratio. The volatility control may be disengaged by closing a manually operated switch 25, and a switch 26, which is opened by a delayed relay 28, ensures smooth engagement of the volatility control when starting up. A meter 29 indicates the flow ratio when the output of amplifier 23 is zero. The Specification refers to control in dependence on viscosity or temperature instead of vapour pressure, to the replacement of one of the switched condensers with a reference source of current, and to the control of a plurality of mixture components. |
