基本信息
摘要：1,209,458. Sensing liquid levels and temperature electrically. ALL-O-MATIC MFG. CORP. Nov.8, 1967 [Nov. 16, 966], No.50881/67. Heading G1N. A liquid level and/or temperature sensing system e.g. for the cooling water of an automobile engine, comprises a semi-conductor sensor 2 Fig. 1, of doped silicon, germanium or gallium arsenide, either N or P type, the resistance of which decreases as temperature increases above a characteristic temperature value and the resistance of which increases as temperature increases at temperatures below the characteristic value. The semi-conductor sensor 2 is connected in series with a warning lamp to the battery voltage, the lamp filament acting additionally as a current limiter. The sensor may firstly be used to monitor the liquid temperature. For safe working temperatures of the engine the current through the sensor 2 will be insufficient to light the lamp. As the temperature rises above the characteristic value e.g. 250‹ F., the sensor resistance decreases and the current will increase causing the lamp to light increasingly brightly. Secondly the sensor monitors the liquid level. If the level falls below the sensor there will be no heat transfer to the liquid and the sensor temperature will increase rapidly due to the I
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