Hitachi, Ltd.

Toru Takahasi

Sadayasu Ueno

Seiko Suzuki

Toru Sugawara

Masahiro Takasaka

Tomoji Inui

An oxygen sensor for monitoring the oxygen concentration in exhaust gases of an engine of a motor vehicle including a sensor element supported by a base in a position remote from the flow of exhaust gases to be tested whereby solid particles in the exhaust gases are prevented from being deposited on the sensor element and the sensor element is imprevious to influences exerted by the temperature and flow velocity of the flow of exhaust gases. The oxygen sensor is capable of stably monitoring the oxygen concentration in exhaust gases of an engine of a motor vehicle with a high degree of performance over a prolonged period of time.

Oxygen sensor

A temperature responsive apparatus includes a thermocouple producing a thermoelectric e.m.f. depending on the temperature difference between a temperature to be detected and a circumferential temperature and a first winding supplied with current from the thermocouple to generate a first magnetic field. A second winding is connected to a voltage source to generate a second magnetic field in the opposite direction to that generated by the first winding and a reed switch is positioned in the total magnetic field generated by the first and the second windings so as to respond to the intensity of the total magnetic field to make and break its contacts. A diode is also connected to the voltage source, and the second winding is always excited in accordance with the voltage drop across the diode to maintain said second magnetic field.

Temperature responsive apparatus employing a thermocouple

A high-temperature detecting apparatus most suitably used with a system for protecting a catalytic apparatus provided for purifying exhaust gas of an automobile is disclosed. A reed relay coil is connected between the cold junctions of a thermocouple in such a manner that the reed relay is driven directly by an electromotive force generated in the thermocouple due to heat in the exhaust gas. The thermocouple and the reed relay are integrally arranged by means of a metal cover. This arrangement reduces the connection resistance between the thermocouple and the coil, thereby making it possible to directly drive the reed relay by the output of the thermocouple.

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Mito, Japan

Toru Takahasi