Development of a Smoke Sensor for Diesel Engines

This paper describes the development and proof-of-concept testing of an electrically based (i.e., non-optical) smoke sensor for diesel engines. The sensor is intended to provide a means of detecting smoke levels that exceed certain pre-defined limits. Potential applications for the sensor include closed loop control of Exhaust Gas Recirculation (EGR) and the diagnosis of fuel injection faults.

Engine dynamometer tests were carried out using a heavy duty diesel engine equipped with a laboratory EGR system. EGR levels were adjusted to vary exhaust smoke levels at a fixed speed/load test point. Reference smoke measurements were provided by an AVL 415S variable sampling smoke meter.

The experimental results showed a correlation between the sensor signal and the Filter Smoke Number (FSN) at FSN values between approximately 1 and 3. The sensor was able to detect relative changes in smoke levels, but its absolute sensitivity was not consistent. It is proposed that precise control of the temperature of the heated sensor will be required to achieve more stable sensitivity.