Nissan Motor Company Limited

Shouichirou Ueno

Naoya Tsutsumoto

Toshimasa Koga

Junichi Kawashima

Terunori Kondou

Makoto Otake

Takao Inoue

Masahiko Nakano

Makoto Ootake

Terunori Kondo

Jun-ichi Kawashima

Terunori Kondoh

A controller () controls regeneration of an exhaust gas filter () which traps particulate matter contained in exhaust gas to prevent the particulate matter from being discharged into the atmosphere. When regeneration of the exhaust gas filter () is underway and the engine () is decelerating, the controller () determines whether or not a catalyst () is active (S) and whether the engine () is decelerating gently or rapidly (S). When the engine () is decelerating gently, the controller () performs a post-injection following a main fuel injection (S), and when the engine () is decelerating rapidly, the controller () performs the main fuel injection but stops the post-injection (S). In so doing, the temperature of the filter does not rise excessively, and the filter can be prevented from melting.

Regeneration control of exhaust gas filter

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 regeneration control device which regenerates a filter () which traps particulate matter in the exhaust gas of an engine () is disclosed. The regeneration control device includes a first temperature sensor (), which detects one of an upstream temperature and a downstream temperature upstream and downstream of the filter () as a first temperature (Tin, Tout); a second temperature sensor (), which detects the other temperature as a second temperature (Tin, Tout); and a microcomputer. The microcomputer programmed to compute an estimated value (Tbede) for the second temperature based on the first temperature detected by the first temperature sensor (), compute an estimated bed temperature (Tbed) of the filter based on the second temperature detected by a second temperature sensor () and the estimated value (Tbede) for the second temperature, and perform engine control for increasing the temperature of the exhaust gas based on the estimated bed temperature (Tbed).

Filter regeneration control

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.

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.

A diesel particulate filter () traps particulate matter contained in the exhaust gas of a diesel engine () for a vehicle. The filter () is regenerated by raising the exhaust gas temperature so that the trapped particulate matter burns. A controller () calculates a particulate matter combustion amount PMr during regeneration, and in accordance with increases in the combustion amount PMr, raises the oxygen concentration of the exhaust gas by operating an intake throttle () and/or a variable nozzle () of a turbocharger (). As a result, the filter () is held at an optimum temperature for regeneration regardless of the residual particulate matter amount, and hence the time required for regeneration can be shortened without damaging the heat resistance performance of the filter ().

This invention relates to regeneration of a filter () which traps particulate matter contained in the exhaust gas of a diesel engine () for a vehicle. A programmable controller () performs filter regeneration appropriately in accordance with the running pattern of the vehicle by calculating a first parameter indicating the frequency with which the diesel engine () performs an idling operation over a predetermined time period up to the present (S), calculating a second parameter indicating the temperature environment of the filter () over a predetermined time period up to the present (S), and determining whether or not the filter () can be regenerated completely on the basis of the first parameter and second parameter (S).

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Yokohama, Japan

Shouichirou Ueno