Abstract: In controlling a fuel injection quantity by spilling a part of fuel fed from a high pressure chamber of a fuel injection pump using a high pressure electromagnetic valve which is on-off controlled by a driving circuit in accordance with engine operating conditions, switch means is provided between the high pressure electromagnetic valve and a power source, an output signal from the driving circuit is monitored, and the switch means is opened when the output signal from the driving circuit continues more than a predetermined period.

Abstract: A combustion process sensor for detecting combustion processes occurring in a combustion chamber of an engine has a generally tubular mounting casing to be screwed into a threaded hole in the combustion chamber wall and a quartz-glass rod axially extending in the mounting casing and held in position therein. The casing includes two axially aligned generally tubular members rigidly secured together at their own ends. The quartz-glass rod has a first portion remote from a sensing end thereof adapted to be exposed to combustion flame in the combustion chamber, and a second portion between the first portion and the sensing end. The first portion is secured to one of the two tubular members of the casing, while the second portion is supported from the casing only by a vibration damping material disposed in engagement with the outer peripheral surface of the quartz-glass rod and the inner peripheral surface of the casing.

Abstract: An internal combustion engine has an exhaust system and an oxygen sensor fitted to the exhaust system including a sensor element and an electrically powered heater for heating the sensor element. A method for controlling the electrical power supplied to the heater properly and quickly heats up the sensor element after engine starting from the cold condition. At the time of starting up the engine it is determined whether or not the temperature of the engine is less than a certain value. If so, the heater is provided with electrical power to the maximum practicable amount, for a certain time interval after the engine is started up. Thereby, during engine heating up operation, the temperature of the sensor element is brought up to its minimum proper operating temperature as quickly as practicable, and accordingly it is ensured that engine performance and the quality of exhaust gas emissions at the time of such engine warming up operation are good. A system is also described for implementing this method.

Abstract: An internal combustion engine has an exhaust system and an oxygen sensor fitted to the exhaust system including a sensor element and an electrically powered heater for heating it. The power supplied to the heater is controlled by determining a target value for it according to operational parameters of the engine, and by controlling the mean power in a time interval as follows: the voltage applied to the heater and the current flowing through it are detected, an intermittent voltage is supplied to the heater, and the duty ratio of the intermittent voltage is controlled so that the product of the heater voltage and the heater current is substantially equal to the target power, with the detection of the voltage supplied to the heater synchronized with the energization of the heater. A system is also described for implementing this method.