Vehicle IC engine exhaust gas emissions cleaning system

摘要

The catalyst (21) has an adsorbing filter (22) downstream to adsorb emission components during cold start and before the catalyst temperature reaches the operating level. Once this is reached a flap valve (23) closes off the outlet to the filter and the exhaust gasses bypass the filter. At the same time a recirculating duct passes some part of the exhaust gas flow through the filter to flush out adsorbed products and pass them back to the inlet manifold. The effectiveness of both the catalyst and the filter are monitored by measuring the rate of temperature changes in the gas flows through them at various times. The rate of temperature change in the filter during operation and during flushing is compared with reference values to determine if the filter needs replacing. The exhaust gas quality is measured downstream of the catalyst, as well as the quality of the recirculated gasses, as well as the time required to flush the filter. All these parameters provide a simple check of the effectiveness of the filter and the catalyst.