| 摘要 |
<p>547,241. Automatic control systems for heating or cooking apparatus. BRITISH THOMSONHOUSTON CO., Ltd. March 27, 1941, No. 4113. Convention date, March 30, 1940. [Class 38 (iv)] Temperature.-A thermostat 19 controlling a valve 13 to vary the supply of a temperature changing medium to a temperature-controlled space has an auxiliary heating coil the current in which varies with the setting of the valve to reduce heating in the control, and further reduction of heating is obtained by arranging that the auxiliary heating is abruptly changed when the thermostat completes an actuating circuit. As shown the series connected shading coils 23, 24 of a motor 15 are supplied from a transformer 27, the mains field 22 of the motor being connected to supply mains. The junction of the coils 23, 24 is connected to the junction of a resistance 41 and a potentiometer resistance 39 which are also in series across the transformer 27. The thermostat 19 is also connected to the said junction and the heating winding 36 is connected across a portion of the potentiometer which is adjusted by the motor simultaneously with the valve. Fixed thermostat contacts 20, 21 are arranged selectively to short-circuit through limit switches not only the shading coils 23 or 24 according as temperature is low or high but at the same time to eliminate or double the potential applied to the heating' winding as a result of the connections described. A resistance may be connected between the potentiometer and the common junction referred to. Two opposed shaded pole motors may be similarly arranged for control. The invention is applicable to heating, cooking and air conditioning systems.</p> |
