Unit monitoring electrically-conductive particles in gas flow, e.g. soot in diesel exhaust, includes measurement system for electrical resistance of deposited particles

摘要

The sensor (S) in the gas flow, captures particles. Its long dielectric (1) spaces terminal electrodes (2) apart. An instrument (3) measures electrical resistance variation arising from the deposits. A processor (4) determines particle flow rate, as a function of variations in electrical resistance measured. A more specific unit is claimed, for evaluating the degree of filter blocking by conductive particles, e.g. soot, based on the same principles. The sensor surface has discontinuities, to augment particle fixation capacity. These include grooves, flat areas or porosity. A computer (4) processes the results, connected to an instrument (3) measuring variations in electrical resistance. A heater (5) is controlled by the computer, to remove accumulated particles by combustion, once the sensor resistance descends below a given threshold. The heater comprises electrical resistances included in the sensor. The computer measures frequency of sensor burn-off. The sensor is implanted at the upstream end of the filter, to track its degree of blockage (by inference). A second is implanted downstream, relative to the flow, to detect possible filter failure. The calculator compares burn-off frequency against a reference value. Filter regeneration is initiated by the computer, as a function of variations of resistance measured by the sensor. The filter is located in the exhaust flow of a heat engine or internal combustion engine. The computer (4) controls filter regeneration in accordance with measured sensor resistance, by modification of engine operational conditions.