DE102011112343B4 - Method and device for regenerating a filter of a vehicle - Google Patents

Abstract

Method for regenerating a filter (4) of a vehicle (10), the vehicle (10) comprising an energy store (5), a generator (6) and an internal combustion engine (7), wherein an energy content of the energy store (5) depends on a imminent regeneration is reduced, with the energy content of the energy store (5) being increased during the regeneration by the internal combustion engine (7) charging the energy store (5) via the generator (6), the energy content of the energy store (5) before the regeneration being below a predetermined percentage of a maximum energy content of the energy store (5) is reduced, and wherein the predetermined percentage is lower, the higher a detected temperature outside the vehicle (10).

Description

The present invention relates to a method and a device for regenerating a filter of a vehicle, in particular a diesel particle filter.

The U.S. 2007/0 204 594 A1 describes an emission control system for a hybrid vehicle with an internal combustion engine and an electric motor. When a deposit in a diesel particulate filter exceeds a limit, the power of the electric motor is increased to reduce an amount of charge before regeneration. The power of the internal combustion engine is then increased, as a result of which the temperature of the diesel particulate filter reaches the temperature required for regeneration and the amount of charge is increased.

The DE 10 2008 039 350 A1 discloses regeneration of an exhaust gas aftertreatment device in a hybrid electric vehicle with a diesel internal combustion engine. The state of charge of a battery, with which a generator/motor is electrically connected, is lowered to a low value when regeneration is required.

The DE 43 21 767 A1 describes a method in which the load on a diesel engine is increased when a limit value is exceeded, with the ignition temperature of the particles in the particle filter being reached.

The DE 10 2008 037 649 A1 discloses a method in which an intake air heater increases an engine load via an alternator of the engine, thereby achieving increased exhaust gas temperatures for DPF regeneration.

The EP 1 205 647 A1 describes a regeneration of a particulate filter, with filter residues being burned off by increasing the temperature. In order to increase the engine load and thus the production of waste heat, suitable electrical consumers are switched on.

A regeneration of a diesel particulate filter (DPF) is in the lower load range of the diesel engine, especially when idling, the more difficult to carry out, the lower the load requirement on the diesel engine. As described above, additional electrical consumers are therefore switched on according to the prior art, for example, in order to increase the load requirement on the engine. However, this procedure has the disadvantage that the total consumption of the vehicle increases due to the consumers that are also switched on.

The object of the present invention is therefore to regenerate a filter of a vehicle, the overall consumption of the vehicle increasing at least less than is the case with the prior art.

According to the invention, this object is achieved by a method for regenerating a filter according to claim 1, by a device for regenerating a filter according to claim 6 and by a vehicle according to claim 8. The dependent claims define preferred and advantageous embodiments of the present invention.

Within the scope of the present invention, a method for regenerating a filter (in particular a diesel particle filter) of a vehicle is provided. The vehicle includes an energy store, a generator and an internal combustion engine, in particular for driving the vehicle. Depending on an imminent regeneration of the filter, an energy content of the energy store is reduced in a targeted manner. During regeneration, on the other hand, the energy content of the energy store is increased by the internal combustion engine (especially a diesel engine) charging the energy store via the generator.

By specifically reducing the energy content of the energy store before regeneration, the energy content or state of charge of the energy store is correspondingly low shortly before the start of regeneration, so that a braking load on the generator is comparatively high during regeneration, so that the engine has more to do in its entire operating range is loaded and thus the critical low-load range can be almost completely avoided.

Targeted discharging is understood to mean the opposite of random discharging, in which case random discharging could take place, for example, by the driver accidentally switching on additional electrical consumers before regeneration. Targeted discharging, on the other hand, is understood as meaning discharging of the battery, which in any case takes place before regeneration, in that specific measures for discharging the battery are initiated in a targeted or automatic manner.

The generator can be an alternator or an electric motor operated as a generator to drive the vehicle.

Advantageously, the energy content of the energy store is reduced in time before the regeneration, in that an energy flow from the generator to the energy store is at least reduced before the regeneration.

While according to the state of the art only an additional, but actually unnecessary consumer is put into operation, with the present invention the vehicle is operated more economically in the run-up to the regeneration (ie before the regeneration) with regard to fuel (e.g. diesel) consumption, by, for example, reducing the drive power for the generator to be generated by the internal combustion engine or eliminating it completely. The braking power then to be applied by the generator (e.g. the alternator) during regeneration is therefore not wasted senselessly, but is used to charge the previously emptied energy store.

Before the regeneration, the energy content of the energy store is lowered below a predetermined percentage of a maximum possible energy content of the energy store by reducing the power supplied by the generator accordingly or by not supplying any power from the generator.

In this case, this predetermined percentage is set as a function of an outside temperature outside the vehicle, in that this percentage is set the lower the higher the detected outside temperature is. In the same way, the predetermined percentage can be set higher, the lower the recorded outside temperature is.

Since starting the internal combustion engine requires more energy, the colder the internal combustion engine is, it is advantageous not to lower the energy content of the energy store as low before regeneration at correspondingly low ambient temperatures as at correspondingly higher ambient temperatures.

According to the invention, it is also possible to partially or completely suppress recuperation before regeneration, in order not to increase the energy content of the energy storage device, but rather to reduce it in a targeted manner.

In vehicles with an electric motor to drive the vehicle, the kinetic energy of the vehicle can be converted into electrical energy by means of recuperation when the vehicle is braked, which increases the energy content of the energy store. By partially or completely suppressing recuperation prior to regeneration, the energy content of the energy store can be reduced according to the invention, in order to allow the braking power to be applied by the generator to charge the energy store to increase accordingly during regeneration. In these vehicles with an electric motor, it is possible, for example, to specifically discharge the energy store before a planned regeneration by using the electric motor to drive the vehicle.

A device for regenerating a filter of a vehicle is also provided within the scope of the present invention. In this case, too, the vehicle comprises an energy store, a generator and an internal combustion engine, while the device comprises control means. These control means specifically reduce the energy content of the energy store depending on an upcoming regeneration. During the regeneration, the control means ensure that the energy content of the energy store is charged via the generator, which is driven by the internal combustion engine.

The advantages of the device according to the invention essentially correspond to the advantages of the method according to the invention, which have been explained in detail above, so that they are not repeated here.

Within the scope of the present invention, a vehicle is also provided which includes a device according to the invention.

For example, in vehicles with a start-stop system (i.e. the combustion engine is switched off when the vehicle is stationary and automatically restarted when the accelerator pedal is pressed), intelligent battery management is used, which monitors the charge level of the battery and and switching off the alternator is able to recover part of the speed energy when coasting (recuperation). For this purpose, the charging voltage of the alternator is increased, particularly when the vehicle is overrun. The present invention now provides for an extension of this field of application of battery management. By specifically switching off the alternator prior to regeneration, the battery is first run empty and then recharged during regeneration when the alternator is switched on again.

The present invention is particularly suitable for vehicles with a diesel engine. It is irrelevant whether it is a vehicle with an electric motor or a vehicle without an electric motor, in which the energy store or the battery is charged via an alternator driven by the engine. However, vehicles with an electric motor (e.g. electric vehicles or hybrid vehicles) offer more options for reducing the energy content of the energy store before regeneration, for example by using the electric motor to drive the vehicle more intensively before regeneration.

It should be noted that the present invention is not limited to vehicles with a diesel engine, since it is also conceivable for use in vehicles with a gasoline engine, for example, if more stringent environmental regulations require the elimination of other particles produced by the gasoline engine. In addition, the present invention can also be used in ships, airplanes and rail-bound or track-guided vehicles, provided they have a corresponding filter.

In the following, the present invention is described in detail on the basis of preferred embodiments according to the invention with reference to the figures.

1 shows the course of the voltage of an energy store and the course of the load on an internal combustion engine by a generator before and during regeneration in a method according to the invention.

In 2 a vehicle according to the invention is shown with a device according to the invention.

In 1 a battery voltage curve 12, a generator power curve 14 and a curve 15 of a regeneration flag are shown over time t. In a first time interval 1, a vehicle with a diesel particle filter is driven normally, ie an alternator in the vehicle and the diesel particle filter are working normally and regeneration is not yet necessary. At the end of the first time interval 1 or at the beginning of the second time interval 2, a corresponding sensor detects that the diesel particle filter will soon have to be regenerated in order to burn off the corresponding particles within the filter, so that the filter can continue to function after the regeneration of the exhaust gas filtering can carry out in full. The vehicle's alternator is therefore switched off, so that the vehicle's battery is no longer charged, but instead is deliberately run empty at the beginning of the second time interval 2, in that the battery continues to have the corresponding electrical consumers (e.g. radio, air conditioning, engine control ) provided. It should be explicitly pointed out that the battery does not supply any additional consumers in this run-up to regeneration (ie in the second time interval 2), which are only connected for the purpose of rapidly reducing the energy content of the battery. Instead, the battery continues to supply the electrical consumers that are switched on anyway. In other words, the battery can only be run empty in a targeted manner by switching off the vehicle's alternator.

By switching off the alternator, the power 14 required by the alternator (generator) in the diesel engine falls in comparison to a normal generator output 13, as it was at the beginning of the second time interval 2 in 1 is shown. On the right scale 1 shows the power required by the alternator in watts. In addition, switching off the alternator also reduces the energy content of the battery, which also causes the battery voltage 12 to drop, as shown in 1 is shown in comparison to the conventional battery voltage curve 11. The left scale in applies to the battery voltage curves 11, 12 1 , on which the voltage is shown in V.

At the end of the second time interval 2 or at the beginning of the third time interval 3, the regeneration of the diesel particulate filter begins, which is the case, for example, in 1 this can be recognized by the fact that the value of a regeneration flag is switched from 0 to 1. In addition, at this point in time (beginning of the third time interval 3), the alternator is put back into operation. Due to the low state of charge of the battery, the braking load 14 of the alternator is very high at this point in time, so that the diesel engine of the vehicle experiences a corresponding additional load from charging the battery over its entire operating range, so that the critical low-load range of the diesel engine during regeneration ( can be almost completely avoided during the time interval 3). It should be noted that regeneration is more effective the less it takes place in the low-load range. Greater effectiveness during regeneration means that less additional fuel has to be burned and that the regeneration time can also be significantly reduced. The additional braking load due to the charging of the battery can be seen from the jump in the generator power profile 14 at the beginning of the third time interval 3. In addition, the battery voltage 12 also increases accordingly at the beginning of the third time interval 3 due to charging, as is shown in 1 is shown.

After the third time interval 3 (after regeneration of the diesel particulate filter), the vehicle returns to the "normal driving" operating state (fourth time interval 4), in which the alternator is operated normally again and which corresponds to the first time interval 1. It can be seen that the battery voltage 12 again corresponds to the conventional battery voltage curve 11 and that the generator power 14 also falls back to the level of the conventional generator power curve 13 .

In 2 a vehicle 10 according to the invention is shown which, in addition to a device 20 according to the invention, comprises a diesel engine 7 with a diesel particle filter 4 , a battery 5 and an electric motor 6 . The device 20 according to the invention in turn comprises a controller 8.

If controller 8 detects that regeneration of diesel particle filter 4 is necessary, controller 8 ensures that electric motor 6 is no longer operated as a generator in order to charge battery 5 . In this operating state “pre-regeneration” there is also no recuperation, so that the battery 5 is discharged due to its supply to the electrical consumers inside the vehicle, but is no longer charged via the electric motor 6 operated as a generator. Then there is a regeneration of the diesel particle filter 4, as previously with 1 is described, except that in the in 2 In the illustrated embodiment, there is no alternator, but the electric motor 6 operated as a generator charges the battery 5 and thus ensures a corresponding additional load on the diesel engine 7 .

The point in time at which the regeneration begins is determined in particular as a function of the state of charge of the battery 5 and as a function of the degree of contamination of the diesel particle filter 4 .

Claims (8)

Method for regenerating a filter (4) of a vehicle (10), wherein the vehicle (10) comprises an energy store (5), a generator (6) and an internal combustion engine (7), wherein an energy content of the energy store (5) is reduced depending on an upcoming regeneration, wherein during the regeneration the energy content of the energy store (5) is increased by the internal combustion engine (7) charging the energy store (5) via the generator (6), the energy content of the energy store (5) falling below a predetermined percentage of a maximum before regeneration Energy content of the energy store (5) is reduced, and wherein the higher a sensed temperature outside the vehicle (10), the lower the predetermined percentage. procedure after claim 1 , characterized in that the internal combustion engine is a diesel engine (7) and the filter is a diesel particle filter (4). procedure after claim 1 or 2 , characterized in that the generator is an alternator or an electric motor (6) operated as a generator for driving the vehicle (10). Method according to one of the preceding claims, characterized in that the energy content of the energy store (5) is reduced before regeneration by reducing an energy flow from the generator (6) to the energy store (5) before regeneration. Method according to one of the preceding claims, characterized in that the energy content of the energy store (5) is reduced by suppressing recuperation prior to regeneration. Device for regenerating a filter (4) of a vehicle (10), wherein the vehicle (10) comprises an energy store (5), a generator (6) and an internal combustion engine (7). the device (20) comprising control means (8), wherein the control means (8) are designed to reduce the energy content of the energy store (5) depending on an upcoming regeneration, wherein the control means (8) are designed to increase the energy content of the energy store (5) during the regeneration by the control means (8) controlling the generator (6) and the internal combustion engine (7) in order to charge the energy store (5) by means of the internal combustion engine (7) to charge via the generator (6), wherein the device is designed to reduce the energy content of the energy store (5) before the regeneration below a predetermined percentage of a maximum energy content of the energy store (5), and wherein the higher a sensed temperature outside the vehicle (10), the lower the predetermined percentage. device after claim 6 , characterized in that the device (20) for carrying out the method according to any one of Claims 1 - 5 is designed. Vehicle with a device (20). claim 6 or 7

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