| 摘要 |
PURPOSE:To avoid the over-correction of a flow rate due to an integrating action by delivering an adverse hysteresis signal when a control deviation signal exceeds a range of deviation corresponding to a blind sector area and using the adverse hysteresis signal to control the application of a control signal to an operating terminal. CONSTITUTION:A control deviation signal B is sent to an adverse hysteresis signal producing part 19 as well as to a blind sector area forming part 143. The signals of low levels are delivered as long as the signal B is kept within a range of deviation corresponding to a blind sector area and then set at high levels when the signal B exceeds said range of deviation and is set at >=H1 to show the adverse hysteresis characteristics. This signal of a high level serves as an ON control signal of an adverse hysteresis adding circuit 16. As a result, a flow rate control valve is controlled. Then the flow rate is controlled by a control signal D produced at a PI control arithmetic part 15. Thus the level of the signal B is lowered gradually. When the signal B is set at <=H2, an adverse hysteresis signal F is delivered. Thus the circuit 16 is turned off. |
