| 摘要 |
<p>1,087,639. Automatic temperature control systems. SATCHWELL CONTROLS Ltd. Dec. 3, 1965 [Dec. 3, 1964], No. 49247/64. Heading G3R. A temperature control system providing both proportional and integral action comprises a thermistor 35 Fig. 3 detecting temperature in A. C. bridge network 10 in series with feedback bridge network 12 having temperature sensitive elements 39, 40 acted on by a heater 74 or 75 when the forward or reverse winding 70, 71 of a servomotor 72 controlling the heating fluid is energized by a 3 position relay 65-68. The bridge outputs are applied to an amplifier including transistors 50, 51 connected to a discriminating circuit comprising a transistor 55 which provides a voltage across resistors 59, 60 of polarity dependent on the signal phase, which voltage is added to a fixed bias across resistors 62, 63 and applied to a transistor 64 controlling the relay coil 65. In an alternative arrangement Fig.7 (not shown) the heaters 74, 75 are controlled by transistors so as not to be dependent on motor current. The resistor heater assemblies 39, 74 or 40, 75 comprise an insulated brass rod 26 (Fig. 2) with a heater 24 overwound with and insulated from a temperature sensitive element 22. The assembly is enclosed in a vacuum flask 30 which is sealed by a foam plastic stopper 31. The arrangement is stated to give integral action times of 50 minutes or more.</p> |
