DE602004013026T2 - Method for controlling the regeneration of a particulate filter - Google Patents

Abstract

A process for controlling regeneration of a particulate filter of an internal combustion engine comprising determining the efficiency of a catalytic device provided in the exhaust upstream of the particulate filter and adjusting at least one operating parameter of the engine in order to increase the exhaust gas temperature upstream of the catalytic device to compensate for a reduction in efficiency of the catalytic device due to ageing.

Description

The The present invention relates to a method of controlling the regeneration of a particulate filter of an internal combustion engine a vehicle, in particular to compensate for the aging of a catalytic arrangement in the exhaust system of the internal combustion engine upstream of the Particle filter is provided.

diesel engines are common due to the requirements of emissions legislation in the exhaust system of which equipped with particle filters. Such filters are usually in the exhaust system downstream a catalytic arrangement such as an oxidation catalyst and other exhaust components such as a turbocharger.

Around To avoid blocking of the particulate filter by accumulated soot, which leads to a increase the exhaust back pressure and ultimately damage the filter leads require Particulate filter periodic regeneration. During the regeneration will raises the temperature of the filter, so that the accumulated Soot burned off which ensures that both acceptable backpressure levels as well as avoiding overloading be ensured of the filter.

This Method of periodic regeneration requires that the temperature of the particulate filter is significantly increased. The temperature of the particulate filter must be compared to a normal exhaust temperature of 150 ° C on increased to about 600 ° C, to burn off the soot. at A known regeneration process will make extra fuel late in the process Injected injection cycle, so that unburned fuel in a catalytic arrangement in the exhaust upstream of the Particulate filter burns to the required elevated temperature to reach the particle filter. It is known, a closed Feedback control system to use, with the temperature at the outlet of the catalytic Arrangement monitored and the amount of injected extra fuel is controlled to the required temperature increase to reach.

As the catalytic arrangement ages, its conversion efficiency decreases for a given inlet temperature, and this eventually reaches a point where increasing the excess fuel does not provide the required temperature increase. It is then necessary to increase the temperature of the exhaust gases from the engine (and consequently to further increase the temperature of the catalytic device). In order to avoid this failure to achieve the required regeneration temperature when the catalytic device has aged, it is currently necessary to calibrate the exhaust gas temperature of the engine to a level higher than that required when the catalytic device is new ( by adjusting the basic calibration setting of the main fuel injection), thereby reducing the efficiency of the regeneration process and increasing the likelihood of failure of the component (for example, contamination of the lubrication system with fuel or excessive temperature of the turbocharger). EP 1291513 and FR 2812688 disclose known regeneration strategies for particulate filters.

The overcomes the present invention this problem by providing a progressive compensation For this Aging process of the catalytic arrangement, wherein the regeneration efficiency maximizes will, while the potential effect of the regeneration conditions on the Engine and exhaust components over the life of the engine Vehicle is reduced.

According to the present Invention is a method for controlling the regeneration of a Particle filter provided an internal combustion engine, the Determining the Efficiency of a Catalytic Array, which in the Exhaust upstream of the particulate filter, and adjusting at least an operating parameter of the engine to the exhaust gas temperature upstream of the to increase catalytic arrangement, to a reduction in the efficiency of the catalytic arrangement due from aging.

The Average method can only be based on those values which correspond to those operating points where the target temperature can be achieved with fully functioning catalytic activity.

measurements Engine load and engine speed can be measured together with the exhaust gas temperature be recorded and the recorded values are filtered, so those recorded temperatures with engine load / engine speed conditions are known to be unable to to reach the temperature target, in determining the average Exhaust gas temperature can not be used (or alternatively in the calculation the temperature differential with a lower temperature target considered become). The adjustment of specific engine load / engine speed conditions to the sensor output requires the implementation of a delay filter, around thermal inertia and to consider a signal delay, about system transport delays to take into account.

Should be a more sophisticated balancing counter As a result, the above technique of engine load / engine speed temperature adjustment may be used to construct a rolling average of the temperature differential on a specific engine load / engine speed basis that produces a temperature matrix that could be used to adjust the engine operating parameter to refine a load / speed basis.

Preferably include the operating parameters of the engine that are adapted Main fuel injection and throttle position. However, it is provided that other engine operating parameters also or alternatively can be adjusted.

The Adjustment of the operating parameter (s) of the engine is preferred proportional to the difference between the specific mean Exhaust gas temperature and the target temperature. This can be on a specific Base of engine load / engine speed to be made when a corresponding temperature matrix is available.

It may be that the relationship between the temperature difference and the engine operating parameter adjustment is not necessarily linear is. For example, a temperature difference of 200 ° C in a additional Main fuel injection delay resulting from 8 °, while a temperature difference of 100 ° C in an additional main fuel injection delay of 3 ° result can.

The Extent of Motor operating parameter adjustment for each operating parameter of the to varying engine is preferably to a maximum adaptation value (eg 8 ° delay for main fuel injection) limited. The adaptation of a motor operating parameter can be over two or several successive regeneration cycles stepwise introduced become.

The Reduction in temperature difference (or other degree of catalyst efficiency) adjusting an engine operating parameter should not allow around the above mentioned Adjusting the engine operating parameter to reverse and thereby in to result in a reversal of aging compensation. This can preferably achieved by merely reversing the Parameter adaptation possible will if the polarity the temperature difference (or another measure of catalyst efficiency) is seen as the other way around.

The priority and scheduling the timing of adjustment of each engine operating parameter, which is to be adjusted, can by means of a temperature compensation algorithm preferably as a function of the degree of temperature difference between the determined average exhaust gas temperature over a regeneration cycle and the target temperature are determined beforehand.

A embodiment The present invention will now be described with reference to the accompanying drawings Drawings in which:

1 FIG. 3 is a schematic representation of a regeneration process according to a first embodiment of the present invention; FIG.

2 a schematic view of the catalyst power monitoring arrangement of the regeneration process 1 is; and

3 a schematic view of the engine parameter modifier arrangement of the regeneration process 1 is.

The position within the overall regeneration control structure of an engine parameter change algorithm used to effectuate actual compensation for the loss of temperature increase due to catalytic aging is described in U.S. Pat 1 shown. In the 1 shown basic regeneration strategy arrangement 1 is conventional in the prior art, whereas the catalyst power monitoring arrangement 2 and the motor parameter modifier arrangement 3 represent additional arrangements that perform the method of the present invention. The catalyst power monitoring arrangement 2 determines the efficiency of the catalytic arrangement, and the motor parameter modifier arrangement 3 determines the necessary changes to the engine parameters used to realize the progressive balance in the catalytic device aging.

The outputs of the engine parameter modifier arrangement 3 include the engine parameter modifications required to compensate for the aging of the catalytic assembly, and such outputs are combined with the basic engine parameter modifications provided by the known regeneration strategy arrangement 1 be determined to provide an output signal for controlling the amount of injected fuel, wherein the main fuel injection and the throttle position are required to achieve the necessary exhaust gas temperature for the regeneration of the particulate filter.

The order 2 will be more detailed in 2 shown. The preferred inputs to the arrangement 2 are engine load 1 , Engine speed 2 and catalyst outlet temperature 3 ,

The catalyst power monitoring arrangement 2 monitors these inputs over a complete regeneration cycle and compares the average catalytic array (DOC) outlet temperature with a predetermined target temperature to provide an output of the temperature difference between the measured DOC outlet temperature and the target temperature as a measure of DOC efficiency. This measure is recorded over a variety of selected intervals throughout the regeneration cycle.

2 shows the use of a target temperature constraint table to select load and speed dependent criteria for selecting recorded measurements to be used in the average calculation to limit the average to the recorded measurements at which the target temperature can actually be achieved. The load and speed inputs to this table are filtered and decelerated to match the load and speed values to the corresponding measured temperature.

One additional Measurement selection criterion based on the differential first Order of the temperature difference is used to determine the influence of To reduce temperature transients.

The basic regeneration strategy arrangement 1 represents the catalytic power monitoring arrangement 2 provide an active flag for full regeneration so that sampling and averaging only occur during the regeneration process of the particulate filter. The catalyst power monitoring arrangement 2 also provides filtered engine load and engine speed readings for use by the engine parameter modifier arrangement 3 ready.

The engine parameter modifier arrangement 3 will be more detailed in 3 shown. The average temperature difference and filtered engine load and engine speed values from the catalyst power monitor assembly 2 become the motor parameter modifier arrangement 3 fed. This arrangement 3 provides a calibration or control parameter modification signal used to control at least one operating parameter of the engine, such as main fuel injection, to increase the DOC inlet temperature (ie, exhaust gas temperature of the engine) by the required amount by the determined loss of oxidation catalyst efficiency to ensure that the oxidation catalyst outlet temperature reaches the target temperature required for regeneration of the particulate filter during the next and subsequent regeneration cycles.

3 shows two actuator blocks 8th . 9 for adjusting a selected engine operating parameter for which the primary input is the average temperature differential (thereby defining a measure of catalytic efficiency). It is this primary input that essentially defines the output of the actuator blocks, which is the amount of actuator adjustment adjustment. The actuator adjustment adjustment would only be reversed if the temperature difference reversed the polarity.

The Output can also be used as a function of engine load and engine speed be determined.

Temperature difference threshold tables 10 . 11 for each engine operating parameter actuator 8th . 9 provide an output associated with the available temperature increase for a given associated engine operating adjustment as a function of load and speed and required temperature increase, and allow scheduling of timing, prioritization, or sequencing of more than one actuator to be achieved. In this embodiment, the selection of which engine operating parameter to adjust will be based on a comparison between the average temperature difference and the contents of the lookup tables 10 . 11 met.

Each engine operating parameter actuator 8th . 9 belongs to a determination unit 12 . 13 , which uses engine speed and load inputs to define the absolute limit of available engine operating adjustment (as a function of load and speed) and the maximum amount of adjustment that may change with each update event.

Claims (12)

A method for controlling the regeneration of a particulate filter of an internal combustion engine, comprising determining the efficiency of a catalytic arrangement provided in the exhaust upstream of the particulate filter and adjusting at least one operating parameter of the engine to increase the exhaust temperature upstream of the catalytic arrangement reducing catalyst efficiency due to aging, wherein catalytic efficiency is improved by determining the exhaust gas temperature downstream of the catalytic arrangement and comparing the exhaust gas temperature with a target temperature, a measure of the temperature increase due to decreased catalytic efficiency is lost, it is determined, wherein the at least one operating parameter of the engine is adjusted to the error between the actual exhausts temperature downstream of the catalytic arrangement and a target temperature, characterized in that the step of determining the exhaust gas temperature downstream of the catalytic arrangement records the exhaust gas temperature at intervals over a complete regeneration cycle and determining the average exhaust gas temperature as an average of the measured temperature over a Variety of selected intervals throughout the entire regeneration cycle by filtering the recorded temperature values used to determine the average exhaust gas temperature and using only those recorded values where the first order differential is the temperature difference between the recorded value and the target temperature falls below a predetermined value or is zero to minimize the transients, the step of adjusting at least one of em operating parameters of the engine over one or more subsequent regeneration cycles occurs. Method according to claim 1, wherein the efficiency of the catalytic arrangement through integration the difference between the exhaust gas temperature and the target temperature over a or multiple regeneration cycles can be determined. Method according to claim 1 or claim 2, wherein the average method only applies to those Values corresponding to those operating points where the Target temperature achieved with fully functioning catalytic activity can be. Method according to one of the preceding claims, taking measurements of engine load and engine speed along with the exhaust gas temperature recorded, and where the recorded Values are filtered so that those recorded temperatures, those with engine load / engine speed conditions are known to be unable to to reach the temperature target, in determining the average Exhaust gas temperature can not be used. Method according to one the claims 1 to 3, taking measurements of engine load and engine speed together recorded with the exhaust gas temperature, and where the recorded values be filtered so that those recorded temperatures, those with engine load / engine speed conditions are known to be unable to to reach the temperature target when calculating the temperature differential be considered with a lower temperature target. Method according to claim 4 or claim 5, wherein a delay filter is used to filter the measurements of engine load and speed to thermal inertia consider. Method according to one the claims 4 to 6, wherein in the measurement of the engine speed and load a signal delay is used to account for system transport delays. Method according to one of the preceding claims, with the operating parameters of the engine being adapted to the Time selection of the main fuel injection and the throttle position include. Method according to one of the preceding claims, the adjustment of the operating parameter (s) of the motor being proportional to the difference between the determined average exhaust gas temperature and the target temperature. Method according to one of the preceding claims, the extent of the Engine operating parameter adjustment for each operating parameter of the engine, which is to be varied, is limited to a maximum adaptation value. Method according to one of the preceding claims, wherein adjusting an engine operating parameter over two or several successive regeneration cycles stepwise introduced becomes. Method according to one of the preceding claims, being the priority and scheduling the timing of adjustment of each engine operating parameter, to be adjusted by means of a temperature compensation algorithm preferably as a function of the degree of temperature difference between the determined average exhaust gas temperature over a Regeneration cycle and the target temperature previously determined can be.