| 摘要 |
<p>1,035,367. Automatic temperature control. THETA CONTROLS Ltd. July 13,1964 [July 11, 1963], No.27571/63. Heading G3R. In an arrangement for controlling the supply of a heating medium the flow temperature is served by a detector A, formed by a thermistor 3 connected in series with a balancing resistor, comprising a resistor 1 and rheostat 4, which is connected across the primary of a transformer 10. The detector and transformer are fed as shown, at constant current from a transformer 5 through a high resistance 2. An imbalance between the currents through the two portions of the primary of the transform 10 due to a variation in the value of thermistor 3, caused by a flow temperature change, causes an error voltage across the secondary which is amplified by transistors 15, 16 and fed to transistors 34, 36 connected as a class B amplifier. The transistor 34,36 are connected, as shown, to relays 39, 40 so that the relay appropriate to the phase of the error voltage actuates contacts 47a, or 47b to energize a motor, not shown, to adjust the flow of heating medium. The motor also drives the slider of a feedback potentiometer 9, fed at constant current through a resistor 14, to vary the currents in the two portions of the primary of transformer 10 so as to tend to restore the secondary voltage to zero. The desired valve of the controlled temperature is adjusted by a potentiometer 7, fed at a constant current through a resistor 8. A further detector B, responsive to conditions outside the controlled space can be connected, as shown, to modify the effect of detector A. The responses of the detector B and of feedback potentiometer 9 are adjusted by potentiometers 6,13 respectively.</p> |
