Abstract: The degree of deterioration of lubricating oil used in an internal combustion engine is detected by measuring the lubricating oil dielectric constant with a pair of spaced sensor capacitor electrodes in the lubricating oil. The sensor capacitor is connected to a fixed capacitor to form a voltage divider connected across a constant frequency AC voltage source so that a developed voltage across the sensor capacitor corresponds to the lubricating oil dielectric constant. The frequency of the AC voltage is set at a value ranging from 50 KHz to 500 KHz.

Abstract: In a Diesel engine with a Bosch-type fuel pump or the like having a control lever which determines the fuel injection quantity, idling speed is controlled by a movable stopper which abuts the control lever to place a lower limit on fuel injection quantity during idling. A control unit derives a target idling speed value according to engine temperature, electrical load, etc. and controls the pneumatic actuator of the stopper in accordance with the difference between actual engine speed during idling and the target idling speed. When the engine is not idling, the pneumatic actuator may be controlled to act as a dashpot, damping the return of the control lever to its idling position. Electromagnetically controlled valves respond to the control unit by providing atmospheric pressure or negative pressure to the pneumatic actuator. An auxiliary valve is provided for bypassing a defective atmospheric pressure supplying valve.

Abstract: A temperature measuring device according to the present invention includes a temperature sensor which is arranged in the vicinity of reference contacts to detect the variations in temperature of the reference contacts, and a processing circuit which outputs a signal corresponding to the temperature at the measuring point by compensating the temperature at the reference contacts based on the output signal from a thermocouple and the output signal from the temperature sensor. The reference contacts and the temperature sensor connected to the processing circuit by transmission lead wires, respectively.