| 摘要 |
PURPOSE:To obtain excellent temperature control characteristics for cooling and heating by providing limitters respectively so that the control signals by proportional integrating actions do not exceed the maximum opening corresponding values of heating and cooling sides of an air mix door. CONSTITUTION:The temperature Tr in a car room measured by a sensor 7 is compared with a preset temperature Ts by an arithmetic unit 8, and a control signal Vb by a proportional integrating action is output to control the opening theta of an air mix door 3. The range of this control signal Vb is set at a range from a point A' corresponding to the full heating under the opening theta to a point A'' larger than a point A corresponding to the full cooling, and some deviation is given to the marginal operation range of the door 3 on the cooling side. Accordingly, since the integration term is small during cooling, even if the control signal tends to move toward the heating side in accordance with the proportional term it is kept at the full cooling position between A and A'', and the car room can be fully cooled. During heating, the capability of a heater core 4 is sufficiently high, therefore the ratio of the integration term is large and a sufficient control is available without providing a deviation. |
