Nissan Motor Company Limited

Makoto Ootake

Naoya Tsutsumoto

Junichi Kawashima

Toshimasa Koga

Shouichirou Ueno

Masahiko Nakano

Terunori Kondou

Terunori Kondo

Terunori Kondoh

An engine controller () controls regeneration of a diesel particulate filter () deployed along an exhaust passage () of a vehicle diesel engine (). Regeneration terminates in response to a terminating request based on running conditions of the diesel engine (). When the regeneration elapsed time at the time of termination is shorter than a reference duration, the engine controller () adds a time corresponding to a deviation of the regeneration elapsed time from the reference duration to the reference duration for the next regeneration of the DPF (), thereby completely removing particulate matter accumulated in and around an inlet () of the filter ().

Regeneration of diesel particulate filter

A particulate matter deposit amount in a diesel particulate filter () provided in an exhaust passage () of a diesel engine () for a vehicle is estimated on the basis of a pressure loss in the filter (), which is detected by a differential pressure sensor (). When the temperature of the differential pressure sensor () is not within a predetermined temperature range, estimation of the particulate matter deposit amount based on the pressure loss is restricted, and instead, the particulate matter deposit amount is estimated by accumulating a particulate matter deposit amount per unit time. In so doing, increases in the estimation error outside of the predetermined temperature range are prevented. Moreover, by applying these estimation methods selectively in accordance with the vehicle speed, the precision with which the particulate matter deposit amount is estimated outside of the predetermined temperature range is improved.

Estimation of particulate matter deposit amount in diesel particulate filter

A particulate matter deposit amount accumulated in a diesel particulate filter () is calculated as a first particulate matter deposit amount from a pressure loss of the filter () (S). The particulate matter deposit amount accumulated in the filter () is calculated as a second particulate matter deposit amount from another parameter (S). It is determined whether or not there is front end blockage of the filter () based on a comparison between the first particulate matter deposit amount and second particulate matter deposit amount (S, S). When there is a front end blockage of the filter (), the regeneration device is controlled to perform regeneration of the filter () for a longer period than the normal regeneration period of the filter () (S).

Removal of front end blockage of a diesel particulate filter

A particulate filter () which traps particulate matter in the exhaust gas of a diesel engine (), regenerates when a controller () performs an exhaust gas increase operation which includes decreasing the opening of an intake throttle (). The controller (), during regeneration of the filter (), determines whether or not the required load of the diesel engine () is increasing from an accelerator pedal depression sensor () or a fuel injection amount (S), and prevents output decrease of the diesel engine () by interrupting the exhaust gas temperature increase operation when the required load is increasing (S).

This invention relates to estimation of a particulate matter deposit amount in a diesel particulate filter () provided in an exhaust passage () of a vehicle diesel engine (). When the vehicle speed exceeds a predetermined vehicle speed, a differential pressure method, in which the particulate matter deposit amount is estimated based on the differential pressure upstream and downstream of the filter (), is applied, and when the vehicle speed does not exceed the predetermined vehicle speed, an accumulation method, in which the particulate matter deposit amount is estimated by accumulating an increment determined from the load and rotation speed of the diesel engine (), is applied. When switching from the differential pressure method to the accumulation method, the particulate matter deposit amount determined in the differential pressure method is used as an initial value of the accumulation, and thus the particulate matter deposit amount can be determined accurately.

An oxidation promoting catalyst () which converts nitrogen monoxide in exhaust gas to nitrogen dioxide, and a diesel particulate filter () which traps soot in the exhaust gas, are installed in an exhaust gas passage of a diesel engine (). A control unit () determines whether or not it is necessary to regenerate the filter based on the exhaust gas pressure detected by an exhaust gas pressure sensor (), and when it is necessary to regenerate the filter, it increases the nitrogen monoxide in the exhaust gas by performing an advance correction of the fuel injection timing of a fuel injector () so as to promote generation of nitrogen dioxide by the oxidation promoting catalyst. The nitrogen dioxide decreases the combustion temperature of the soot trapped by the diesel particulate filter (), and efficiently regenerates the filter.

Regeneration of diesel particulate filter for diesel engine

A particulate filter ( ) is provided in an exhaust passage ( ) of a diesel engine ( ) in order to trap particulate matter in exhaust gas. A controller ( ) determines a basic fuel injection amount in response to an accelerator pedal depression amount (S ), determines a maximum fuel injection amount in response to an intake air amount of the engine ( ) (S ), and sets the smaller of the basic fuel injection amount and the maximum fuel injection amount as the target injection amount (S -S ). When the deposited amount of particulate matter on the particulate matter filter ( ) has exceeded a predetermined amount, reductions in output torque are prevented by increasing the maximum injection amount (S ).

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Yokohama, Japan

Makoto Ootake