摘要 |
An exhaust gas purification system has a first accumulation quantity estimation device that estimates an accumulation quantity of exhaust particulate matters collected by a diesel particulate filter (DPF) based on a flowing state of exhaust gas and a second accumulation quantity estimation device that estimates the accumulation quantity based on an operating state of an engine. The first estimation device is employed only when a flow rate of the exhaust gas is equal to or greater than a predetermined value and the engine is in a steady operating state. Otherwise, the second estimation device is employed. The exhaust gas flow rate is increased if the estimation by the second estimation device continues for a long time. Thus, an opportunity to perform the accumulation quantity estimation with the first estimation device is increased, and accumulation accuracy is improved.
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