Nissan Motor Company Limited

Shigeo Isitani

Masaaki Uchida

Kohki Sone

A temperature control system is disclosed wherein a heater of a gas sensor and a plurality of reference resistors cooperate to form a bridge circuit. The temperature control system comprises a comparator means for monitoring a balancing voltage of the bridge circuit and generating a control signal indicative of the balancing voltage and an electric power amplifier means responsive to the control signal for varying a voltage applied to the bridge circuit in such a manner to reduce the balancing voltage. The gas sensor has mounted therein at least one of the plurality of reference resistors, which reference resistor having a resistance resulting from multiplying the resistance of the heater with a constant.

Temperature control system

A device for detecting concentrations of oxygen in gases by using an oxygen sensor element having a substrate provided with a heater and a concentration cell part in the form of a laminate including a solid electrolyte layer supported on the substrate. The device has a power supply circuit to apply a controlled voltage to the heater to keep it at a constant temperature by controlling its resistance to a constant value, and a current supply circuit which forces a controlled DC current to flow through the solid electrolyte layer in the sensor element to thereby maintain a reference oxygen partial pressure in the sensor element. The current supply circuit is electrically associated with the power supply circuit so as to vary the intensity of the current in inverse proportion to the voltage applied to the heater for the purpose of maintaining the reference oxygen partial presure constant even when the temperature of the concentration cell part of the sensor element varies depending on the temperature of the gas subject to measurement.

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Yokosuka, Japan

Shigeo Isitani