EP1827893A1

EP1827893A1 - Method for controlling the regeneration of an electrostatic particle filter

Info

Publication number: EP1827893A1
Application number: EP05824400A
Authority: EP
Inventors: Alexandra Dubray-Demol; Philippe Le Quang Bieng; Pierrick Morel; Pierre Darcy
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 2004-12-13
Filing date: 2005-12-07
Publication date: 2007-09-05
Also published as: JP2008523300A; FR2879242A1; WO2006064148A1; US20090266050A1; WO2006064148A8

Abstract

The invention relates to a method for controlling the regeneration of a particle filter (6) by electrically heating the same. According to said method, the regeneration is triggered by a calculator (3) according to the loading level (A) and the temperature (T) of the particle filter (6). The inventive method is characterised in that the calculator (3) simultaneously uses parameters relating to the operation of the vehicle in such a way as to take into account the fuel consumption driven by the electrical heating of the filter (6).

Description

METHOD FOR CONTROLLING THE REGENERATION OF AN ELECTROSTATIC PARTICLE FILTER

The invention relates to a method for controlling the regeneration of an electrostatic particle filter fitted to the exhaust line of the internal combustion engine of a motor vehicle.

The regeneration is applied by electric heating of the particulate filter. It is triggered according to functional parameters of the motor vehicle that are sent to a calculator.

Among the known systems for removing soot particles emitted by internal combustion engines and in particular diesel engines, mention may be made of particulate filters inserted into the exhaust lines of the engines. These particulate filters are adapted to trap the soot particles contained in the exhaust gas.

Controlled regeneration devices make it possible to periodically burn the particles trapped in the particulate filters and avoid clogging them. It is desirable that the regeneration of a particulate filter does not penalize the performance and has the least impact on the cost of consumption of the engine.

Indeed, the soot particles burn at temperatures of the order of 500 to 600 ° C. However, such thermal levels are only rarely achieved by the exhaust gas of a motor vehicle diesel engine, for example in the city, the temperature of the exhaust gases varies between 150 ° and 250 ° C. Hence the need to have appropriate means to directly heat the soot without passing through the gas. Various regeneration systems have been proposed, in particular, electric resistance heating systems, to bring the temperature of the exhaust gas to a value sufficient to cause the combustion of particles in the particulate filter.

The activation of such regeneration aid systems is controlled by a control computer which determines, as a function of a certain number of parameters, the time of the regeneration. However, the electrical power demanded by electrical auxiliaries, such as electrical resistance, is directly supplied by the motor via the alternator. Regeneration of the particulate filter can therefore result in overconsumption of fuel or, if the alternator can not provide the instantaneous power, a discharge of the battery.

The object of the present invention is to limit the fuel consumption due to an electric heating system used for the regeneration of a particulate filter.

For this purpose, the invention proposes that the regeneration control computer receives parameters making it possible to determine the fuel consumption related to the production of electricity for the heating means necessary for the regeneration. According to other characteristics of the invention, the parameters coming from the vehicle are, for example, the position of the pedals, the speed of the vehicle, the gear engaged.

Other features and advantages of the invention will appear on reading the description of exemplary embodiments with reference to the appended figures.

FIG. 1 represents a schematic view of an internal combustion engine equipped with a particulate filter, implementing the method according to the invention.

FIG. 2 represents a flowchart of the method according to the invention. Identical or similar elements are designated by the same reference numerals.

Figure 1 illustrates in a non-limiting way the implementation of the proposed regeneration principle. An internal combustion engine 1 is intended to equip a vehicle such as an automobile. This is, for example, a diesel engine turbocharged four-cylinder in-line and direct injection of fuel. The engine 1 is equipped with an exhaust line 5 provided with a device for filtering soot particles. The engine 1 is supplied with air by an intake circuit 2.

Suitable sensors, and in particular a flowmeter 8, equip the intake circuit 2 to supply a control computer 3 with parameters relating, for example, to the pressure supplying the engine 1. The injection of the fuel into the cylinders is ensured by electromagnetic injectors, not shown, opening into the combustion chambers and controlled by the control computer 3 from a pressurized fuel circuit 4 of the common rail high pressure type. At the outlet of the engine 1, the exhaust gas discharged in line 5 passes through a particulate filter 6.

Different sensors 7, such as pressure and temperature sensors, placed upstream and downstream of the particle filter 6, provide the control computer 3 with corresponding parameters. It is also planned to equip the exhaust line with an oxidation catalytic converter 10 treating HC unburned hydrocarbon emissions and carbon monoxide CO. Part of the exhaust gas is recycled to the intake by means of a recycling circuit 11 comprising a valve 12 whose opening is controlled by the control computer 3. The turbocharger comprises, in a conventional manner, a turbine 13 and a compressor 14. - AT -

The control computer 3 comprises, in a limiting manner, a microprocessor or CPU, at least one random access memory, at least one read-only memory, at least one digital analog converter and at least one input / output interface. The microprocessor of the control computer 3 comprises electronic circuits and appropriate software, intended in particular for the different actuators controlled.

The computer 3 controls the fuel pressure in the common rail 4 and the opening of the injectors from the parameters delivered by the various sensors, and in particular the intake air mass, the engine speed and the formulas and stored calibrations to achieve the desired levels of consumption and performance. The opening of the injectors is more particularly defined by the instant of injection start and the duration of opening of the injectors, duration which corresponds for a given supply pressure to a quantity of fuel injected and therefore to a richness of the mixture filling the combustion chambers.

The computer 3 is also adapted to ensure the control of the operation of the exhaust system, and in particular of the particulate filter 6. The triggering of the regeneration of the particle filter 6 is controlled by the computer 3 which further determines its continuation or its interruption.

As indicated above, the regeneration phase essentially consists in directly increasing the temperature of the soot so as to burn the trapped particles. The increase in temperature is initiated, for example, by electric heating means such as metal cords.

According to the invention, the computer 3 takes into account various parameters, concerning the particulate filter 6, itself, and the vehicle for triggering the regeneration, for example, engine coolant temperatures, gases upstream and downstream of the particulate filter 6, the vehicle speed, the mass of soot accumulated in the particulate filter 6 and the distance traveled since the last regeneration. According to the invention, the computer 3 also receives other parameters relating to the fuel consumption due to the production of electricity to operate the heating system. These last parameters can include the position of the pedals Pf, Pacc, the speed V of the vehicle, the gear ratio H, the speed N of the engine, the torque M of the motor.

In this way, a compromise can be found to achieve regeneration while avoiding overconsumption of fuel or discharge of the battery.

FIG. 2 illustrates a flowchart of the method for controlling the regeneration of a proposed particulate filter.

In step 10, the computer notes various parameters such as the level of loading of the particle filter A, the speed V of the vehicle, the position of the acceleration pedal Pacc, the torque of the motor M, the engine speed N , the engaged ratio H, the temperature T of the particulate filter.

In step 1 1, after the computer 3 has noted as a parameter the loading level of the particulate filter A, a first test is performed on the level of the loading of the filter 6.

If the loading level A is less than a predetermined threshold, called S1, S1 is greater than a threshold from which the regeneration is not necessary, called Smini, the next step is step 17, there is no regeneration.

If the level of loading A is greater than S1, the next step is step 12. In step 12, a second test is performed on the position of the brake pedal Pf. If the position of the brake pedal Pf is activated, noted Pf = 1, the next step 14 is the regeneration. The regeneration is activated thanks to the electrical energy recovered by the regenerative braking. The regenerative braking takes place when the vehicle mode is rolling with braking: the alternator recovers the kinetic energy of the vehicle in electrical form to supply the heating means.

If the position of the brake pedal is inactive, noted Pf = 0, then the next step is step 13 where a new test is performed on the loading of the particle filter. The loading level A is then compared to a second predetermined threshold, called S2 (significant back pressure which requires regeneration without waiting for the driver to brake). This threshold S2 is greater than S1 and is less than a threshold where the regeneration becomes mandatory, called Smax. If the loading level A is greater than S2, the next step is step 15. This step 15 consists in that the computer 3 selects the values of various parameters having an influence on the fuel consumption, for example the vehicle speed V, the position of the acceleration pedal Pacc, the torque M of the engine, the engine speed N, the gear engaged H, the temperature T of the particulate filter.

To determine if there is a fuel over-consumption, initially, the engine efficiency F is calculated using selected parameters. The values of the various parameters allow the computer 3 to make a comparison between the engine efficiency G which would be obtained with a regeneration and the engine efficiency F obtained without regeneration.

For this purpose, a mapping of the efficiency G of the motor obtained with a regeneration is memorized by the computer 3. For example, for a heat engine, a map of the Efficiency G is represented as a function of the following parameters: the motor torque M and the motor speed N. The values recorded by the computer 3 make it possible to determine the efficiency F of the engine on the stored map. The efficiency F of the engine is compared with the efficiency of the engine obtained with a regeneration G. If the regeneration improves the efficiency of the engine, it is activated, the next step is step 14.

Otherwise the loading level of the particulate filter A is compared with the threshold Smax in step 18. If the loading level A is less than Smax, the regeneration is not performed, it is step 17.

If the loading level A is greater than Smax, the regeneration is then switched on immediately.

Claims

1. A method of controlling the regeneration of a particulate filter (6) by electric heating thereof, wherein the regeneration is triggered by a computer (3) as a function of the loading level (A) and the temperature ( T) of the particulate filter (6) characterized in that the computer (3) simultaneously uses parameters related to the operation of the vehicle so as to take into account the fuel consumption caused by the electric heating of the filter (6).

2. A method of controlling the regeneration of a particulate filter (6) according to claim 1, characterized in that the parameters comprise the position of the brake pedal (Pf).

3. A method of controlling the regeneration of a particulate filter (6) according to one of claims 1 or 2, characterized in that the computer (3) activates the regeneration of the particulate filter (6):

if the loading level (A) is greater than S1, which is a predetermined threshold,

- and if the position of the brake pedal (Pf) is activated, Pf = 1.

4. A method of controlling the regeneration of a particulate filter (6) according to claim 3, characterized in that S1 is greater than Smini, which is the threshold from which regeneration is not necessary.

5. A method of controlling the regeneration of a particulate filter (6) according to one of claims 3 or 4, characterized in that the computer (3) activates the regeneration of the particulate filter (6)

if the loading level (A) is greater than a predetermined threshold, S2, which is greater than S1,

- and if the position (Pf) is not activated, Pf = 0 - And if the efficiency (F) of the engine, calculated using selected parameters, is lower than the efficiency (G) of the engine that would be obtained with a regeneration of the particulate filter.

6. A method of controlling the regeneration of a particulate filter (6) according to claim 5, S2 is less than Smax, which is the threshold where regeneration is mandatory.

7. A method of controlling the regeneration of a particulate filter (6) according to one of claims 5 or 6, characterized in that the parameters comprise the engaged ratio (H).

8. A method of controlling the regeneration of a particulate filter (6) according to one of claims 5 or 6, characterized in that the parameters comprise the position of the accelerator pedal (Pacc).

9. A method of controlling the regeneration of a particulate filter (6) according to one of claims 5 or 6, characterized in that the parameters comprise the speed (V) of the vehicle.

10. A method of controlling the regeneration of a particulate filter (6) according to one of claims 5 or 6, characterized in that the parameters comprise the regime (N) of the engine.

11. A method of controlling the regeneration of a particulate filter (6) according to one of the preceding claims 5 or 6, characterized in that the parameters comprise the torque (M) of the engine.