Dirty work

Particulate sensors that allow automatic cleaning of filters in diesel exhaust emission control systems have been developed in an EU-backed research project — the IMITEC initiative.

Diesel vehicles are increasingly becoming a major force in Europe’s automotive market, representing more than 50 per cent of the car fleet in several EU countries. They are more efficient than equivalent petrol versions but produce higher emissions of particulates, mainly carbon and nitrogen oxides.

To control this, diesel vehicles can be fitted with a particulate filter. As the filter becomes clogged by the particulate it collects, it needs to be cleaned by oxidation of the accumulated soot to remain functioning — a process known as regeneration. To do this, the exhaust temperature must be raised.

However, diesel engines are very efficient so the normal exhaust temperature is too low to oxidise soot. Without a sensor it can be hard to judge when a filter needs to regenerate, as more or less particulates can be produced depending on driving conditions.