Nissan Motor Company Limited

Junichi Kawashima

Naoya Tsutsumoto

Toshimasa Koga

Terunori Kondou

Takao Inoue

Makoto Otake

Shouichirou Ueno

Masahiko Nakano

Makoto Ootake

Terunori Kondo

Munehiro Tabata

Yutaka Matayoshi

Toshifumi Nishimura

Makoto Ohtake

Satoshi Takeyama

Kouji Mori

Kodai Yoshizawa

Seiji Niinuma

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 diesel engine () comprises an exhaust passage (), and a DPM filter () provided on the exhaust passage (), which traps diesel particulate matter (DPM) contained in the exhaust gas such that the diesel particulate matter accumulates therein. An engine controller () starts regeneration processing of the DPM filter () by raising the exhaust gas temperature when a regeneration timing of the DPM filter () is reached, sets a target exhaust gas temperature during regeneration processing to ensure that the temperature of the DPM filter () does not exceed an upper temperature limit of the DPM filter (), even when the temperature of the DPM filter () is raised due to the engine () entering an idling condition during the regeneration processing, and controls the exhaust gas temperature to the target exhaust gas temperature.

Diesel engine comprising DPM filter and DPM filter regeneration method

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).

A regeneration control device which regenerates a filter () by increasing an exhaust gas temperature to burn exhaust gas particulates trapped in the filter, is disclosed. The filter () traps particulate matter in exhaust gas from an engine (). The regeneration control device suppresses fuel cost-performance impairment due to filter regeneration. The regeneration control device has a load detection sensor () which detects an engine load and a microcomputer-based controller (). The controller is programmed to perform engine control to adjust the exhaust gas temperature for regeneration of the filter (), when a computed trapped amount is equal to or more than the first reference value (A) and less than the second reference value (B), and the detected load (Vsp) is equal to or more than a reference load (Vo); and perform engine control to adjust the exhaust gas temperature for regeneration of the filter () regardless of the detected load (Vsp), when the computed trapped amount is equal to or more than the second reference value (B).

Filter regeneration in engine exhaust gas purification device

A filter () which traps particulate matter contained in the exhaust gas of a diesel engine () for a vehicle is regenerated by fuel injection control. A controller () calculates a representative value of the operating condition of the diesel engine () during a latest predetermined time period, and determines the traveling condition of the vehicle on the basis of this representative value. When the representative value corresponds to a highway traveling condition, fuel injection control is performed in accordance with a pattern for burning all of the particulate matter trapped in the filter (). Under any other conditions, fuel injection control is performed in accordance with another pattern. Hence optimum filter regeneration can be performed depending on the traveling condition of the vehicle.

Regeneration control of diesel particulate filter

A filter differential pressure, which is the difference between the inlet pressure and the outlet pressure of a DPM filter (), is determined, and switching is performed in accordance with the regeneration condition of the DPM filter () between a first trapped DPM amount calculation process for estimating the trapped DPM amount after complete regeneration, in which all of the DPM trapped in the DPM filter () is burned, and a second trapped DPM amount calculation process for estimating the trapped DPM amount when a part of the DPM trapped in the DPM filter () has been burned away. The trapped DPM amount in the DPM filter () is estimated on the basis of the filter differential pressure using one of the first and second trapped DPM amount calculation processes.

Diesel engine comprising DPM filter and method of estimating amount of DPM trapped in DPM filter

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.

A diesel particulate filter () which traps particulate matter contained in the exhaust gas of a diesel engine () comprises an oxidation catalyst (A) which exhibits a temperature-raising effect during regeneration of the filter (). A controller () calculates the amount of particulate matter trapped in the filter () at the start of regeneration as a first amount, and calculates the amount of particulate matter burned during regeneration of the filter () as a second amount (S, S, S). A deterioration factor d of the oxidation catalyst is calculated from the ratio of the second amount and first amount, and a target temperature for the next regeneration of the filter is determined on the basis of this deterioration factor d. Thus deterioration of the oxidation catalyst (A) is compensated for, and an optimum temperature environment for regenerating the filter () is realized.

An exhaust gas purifying system of a diesel engine comprises a PM filter installed in an exhaust passage line of the engine to collect particulate matter (PM) in the exhaust gas from the engine; a pressure difference sensor for detecting a pressure difference between upstream and downstream portions of the PM filter; a control unit which comprises a collected PM amount estimating section that estimates an amount of collected PM in the PM filter based on the pressure difference; and a reactivation timing judging section that, based on the estimated amount of the collected PM, judges a reactivation time when the reactivation of the PM filter is needed; and a reactivation carrying out system that, upon judgment of the reactivation time, carries out a predetermined operation to increases the temperature of the PM filter thereby to burn the collected PM. The control unit further comprises a dispersion condition judging section that judges a dispersion condition of the collected PM in the PM filter; and a correction section that corrects the estimated amount of the collected PM in accordance with the judged dispersion condition of the collected PM.

Exhaust gas purifying system of internal combustion engine

An engine exhaust gas purification device is disclosed. The purification device has a filter () which traps particulate matter contained in the exhaust gas from an engine; a differential pressure detection sensor () which detects a differential pressure of the filter; a sensor () which detects an engine running state, and a microcomputer (). The microcomputer () is programmed to compute an estimated ash amount ASH_a of the filter based on the detected differential pressure; compute an oil consumption amount OC_total based on the detected engine running state; compute an ash density DENS_ASH from the oil consumption amount OC_total and estimated ash amount ASH_a, and compute an ash amount ASH of the filter based on the oil consumption amount OC_total and ash density DENS_ASH.

Engine exhaust gas purification device

A map which defines a relationship of an exhaust gas pressure Pat the outlet of a filter () to a load Q and rotation speed Ne of an engine () is prepared, and an exhaust gas pressure Pat the inlet to the filter () is determined from a differential pressure &#x394;P between the front and rear of the filter and the outlet pressure Pobtained by referring to the map. The inlet pressure Pdetermined in this manner is used to determine an exhaust gas volumetric flow rate Q, and thus an accurate particulate accumulation SM, which is required to determine the need for regeneration of the filter (), can be calculated.

To regenerate a diesel particulate filter () which traps particulate matter contained in the exhaust gas of a diesel engine (), a controller () raises the temperature of the exhaust gas through fuel injection control of a fuel injector (), and thus burns the particulate matter trapped in the filter (). The controller () cumulatively calculates the time during which the temperature of the filter () exceeds a target temperature as an effective regeneration time. By estimating the amount of particulate matter remaining in the filter () on the basis of the effective regeneration time, the controller () estimates the amount of remaining particulate matter with a high degree of precision and without consuming energy, whereupon regeneration of the filter () through fuel injection control ends.

In regeneration apparatus and method for a particulate filter that collects a particulate in exhaust gas of an internal combustion engine, a timing at which an accumulated particulate is combusted to regenerate the particulate filter is determined and a control is performed for a combustion of the particulate, during the control for the combustion of the particulate, a temperature of the engine exhaust gas is raised to a first target temperature set at a temperature equal to or higher than a criterion temperature which provides a criterion of whether the particulate is combusted to regenerate the particulate filter when the engine falls in a first driving region, and the engine exhaust gas temperature is raised to a second target temperature set at a temperature lower than the criterion temperature when the engine falls in a second driving region different from the first driving region.

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Yokosuka, Japan

Junichi Kawashima