DE102017212807A1 - Method and device for regenerating a particle filter of a vehicle - Google Patents

Abstract

A method and a device for the regeneration of a particle filter (6) of a vehicle are proposed, wherein the vehicle has an internal combustion engine (1), an electrical machine (2), a navigation device (11) and a battery (12). The electric machine (2) can be operated as a drive of the vehicle together with the internal combustion engine (1) or alone or as a generator. Based on a route proposed by the navigation device (11), a prediction of driving segments (1,11, III) with low or high vehicle load is made. To assist a regeneration of the particulate filter (6), the electric machine (2) is operated as a drive before a driving segment (I) with low vehicle load until a predetermined low state of charge of the battery (12) is reached and before a driving segment (III) with high Vehicle load, the electric machine (2) is operated as a generator until a predetermined high state of charge of the battery (12) is reached.

Description

State of the art

The invention is based on a method and a device for the regeneration of a particulate filter of a vehicle according to the preamble of the independent claims.

From the EP 2 157 407 B1 a vehicle is already known which has an internal combustion engine with a particle filter and a navigation device. The data of the navigation device are used to calculate a vehicle load based on a travel route of the vehicle. In this case, routes are preferred in which the vehicle load is advantageous for regeneration of the particulate filter.

Advantages of the invention

In contrast, the method according to the invention or the device according to the invention for the regeneration of a particulate filter of a vehicle has the advantage that the regeneration of the particulate filter in the vehicle is optimized. Based on a proposed by the navigation device route is a prediction of driving segments with high or low vehicle load. To support this regeneration of the particulate filter, the electric machine is used as a drive or a generator in order to produce an advantageous load state of the internal combustion engine for regeneration. It can be achieved in different segments driving an optimization of regeneration. To prepare for these measures, a desired state of charge of the battery is produced in each case before reaching the respective driving segments in order to be able to optimize the regeneration during the relevant driving segment. By this forward-looking operation, therefore, an improved regeneration of the particulate filter, in particular with respect to the usable for the regeneration load ranges of the internal combustion engine can be achieved.

Further advantages and improvements result from the measures of the dependent claims. By operating the electric machine as a generator, an additional load of the internal combustion engine and by operating the electric machine as a drive, a reduction of the load of the internal combustion engine can be achieved. It can thus be ensured each optimized for the regeneration load of the internal combustion engine. In front of a driving segment with changing vehicle power while a medium state of charge of the battery is sought in order to allow both operation as a generator and as a drive in this phase. In particular, in areas with low vehicle load, the regeneration is only started when a desired state of charge of the battery is made, so that an increase of the load of the internal combustion engine is made possible. During an ongoing regeneration of the particulate filter, the desired state of charge of the battery is advantageously produced before a change of the driving segment takes place. It can thus be ensured that an ongoing regeneration is not interrupted by a change of the driving segment. Furthermore, it can be ensured by proposing a corresponding route that driving routes that are favorable for a regeneration of the particulate filter are preferred. Also by this measure, the time that is available for regeneration can be optimized.

list of figures

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

• 1 ein Fahrzeug mit einer Brennkraftmaschine 1, einer elektrischen Maschine 2 und mit einem Partikelfilter 6,
• 2 eine Fahrgeschwindigkeit und ein Batterieladezustand jeweils aufgetragen gegen die Zeit und
• 3 verschiedene Schritte des erfindungsgemäßen Verfahrens

Show it:

• 1 a vehicle with an internal combustion engine 1 , an electric machine 2 and with a particle filter 6 .
• 2 a travel speed and a battery state of charge respectively plotted against time and
• 3 various steps of the method according to the invention

Description of the embodiments

In the 1 becomes a drive for a hybrid vehicle consisting of an electric motor 2 and an internal combustion engine 1 shown. Both motors are capable of a drive shaft 4 of the vehicle and thus cause a movement of the vehicle. A control, whether the drive of the drive shaft for each vehicle by the electric motor 2 or by the internal combustion engine 1 is done by a control unit 10 coordinates, which by control pulses a corresponding power output of the internal combustion engine 1 or the electric motor 2 on the drive shaft 4 of the vehicle causes. The control unit controls this 10 via appropriate Ansteuerleitungen the internal combustion engine 1 or the electric motor 2 at. The internal combustion engine 1 has a variety of cylinders 3 on. The combustion exhaust gases of the combustion in the cylinders 3 be over an exhaust pipe 5 through a particle filter 6 and finally after the particulate filter through the exhaust pipe 7 delivered to the environment. Other means of exhaust aftertreatment, such as various catalysts are for reasons of clarity in the 1 not shown.

By combustion in the cylinders 3 The exhaust gas contains fine particles, which are commonly referred to as soot. However, these are not just carbon but also other substances contained in fuels, such as sulfur. Through the passage through the particle filter 6 These particles are filtered out of the exhaust, so that in the opening into the environment exhaust pipe 7 only a few or no particles are contained. Due to this continuous filtering process, the particle filter saves 6 the particles. From time to time, for example every 500 to 1000 km of driving distance of the vehicle, it is necessary that in the particulate filter 6 stored particles through an oxidation process to completely burn, so the loading of the particulate filter 6 to reduce again with particles. For this purpose, a regeneration phase is provided. In this regeneration phase, the temperature in the particulate filter 6 kept at a sufficient level, since the combustion of the particulate filter 6 stored particles requires an initial temperature, for example, of 580 degrees. By a residual amount of oxygen in the exhaust gas, which is the particle filter 6 via the exhaust gas supply 5 is fed, then a burning of the particles is caused when the temperature in the particulate filter 6 is sufficiently high.

Furthermore, the vehicle still has a battery 12 and a navigation device 11 on. The battery 12 is with the electric machine 2 connected and provides either electrical energy to operate the electric machine 2 as a drive or but gets from the electric machine 2 electrical energy, which is then stored in the battery when the electric machine 2 operated as a generator. Furthermore, the state of charge of the battery, which is also referred to as SOC (State of Charge) is monitored by a corresponding device, such as a control unit. This function can be used, for example, by the control unit 10 for controlling the internal combustion engine 1 or the electric machine 2 to be taken over. Alternatively, a separate battery control device may be provided.

Furthermore, a navigation device 11 provided, in which a driver of the vehicle can enter a destination request. Based on the destination of the driver and in the navigation device 11 contained road data, a route and in particular the expected power requirement to the vehicle by the driver can be predicted. Alternatively, the navigation device can also determine a route prediction on the basis of learned values of the driver behavior. For example, the driver always drives to work at the same time or to do sports every Thursday, or when he drives onto the motorway after two kilometers, he typically drives 30 kilometers before leaving the motorway. According to the invention, this route prediction is now provided by navigation devices 11 for optimized operation of the vehicle, in particular for regeneration of the particulate filter 6 to use. To explain this optimized method for the regeneration of the particulate filter is on the 2 directed.

In the 2 is a speed V of the vehicle and a percentage state of charge of the battery, which is also referred to as SOC hereinafter, each also plotted against a time.

On the basis of the speed of the vehicle V can be plotted against the time different driving segments recognize, which are marked as I, II and III. A first driving segment I is characterized by predominantly low driving speeds V in the period between t0 and t3 characterized. This segment I thus is a segment of a typical city traffic, in which only low speeds occur. This is followed by a segment II, in which also speeds well beyond 50 Km / h can occur. This segment II thus corresponds to an operation on a highway, in which it comes to frequently changing vehicle loads of the vehicle. In this segment II (highway) phases with a high vehicle load follow phases with a low vehicle load and the loads of the vehicle alternate more frequently in the period between t3 and t5 , This concludes from the time t5 a Segment III, which is characterized by very high speeds in the vicinity of and well above 100 Km / h. This segment III is thus a highway operation in which typically very high vehicle loads occur.

Furthermore, in the upper diagram there is still a time range between the period t1 and t6 shown in which a regeneration of the particulate filter 6 is operated. As is clear from the temporal overlap, a regeneration can take place both in city operation of the driving segment I, and in the country road operation of the driving segment II and, of course, in the highway operation of the driving segment III. In the lower part of the 2 the state of charge of the battery between a maximum state of charge max and a minimum state of charge min is shown. The maximum charge state is determined by the capacity of the battery. When the battery 12 no more charge can take, so is the maximum state of charge of the battery 12 reached. The minimum state of charge is not characterized by a completely empty battery, but by the fact that in the state min still reliable start of the vehicle, ie a Start of the internal combustion engine 1 can be ensured. This situation state min does not correspond to a complete discharge of the battery, but a remaining reliable starting possibility of the vehicle. Furthermore, the battery may still have limitations in the allowable charge and discharge in terms of the durability of the battery, since, for example, overcharging leads to a reduced durability. The average state of charge, which is referred to as mid, is then simply located between the maximum value and the minimum value, wherein this average state of charge does not necessarily have to represent the exact middle between the state max and min.

According to the invention it is now provided, due to the prediction of driving segments, to set a control of the state of charge of the battery or a start of the regeneration. First, let's consider the period between t0 and t1 during which the vehicle is in driving condition 1 , ie a driving condition with relatively low load requirements is operated on the vehicle. To be in this driving condition 1 a regeneration of the particulate filter 6 To favor, therefore, is initially in the phase between t0 - t1 planned a discharge of the battery to the minimum state of charge. This is the electrical machine 2 operated as a drive, whereby the battery is discharged. At the time t1 is detected that now the desired minimum state of charge of the battery is reached, and then it is at this time t1 the regeneration of the vehicle started. Due to the highly discharged state of the battery can then in this time window, the electric machine 2 operated as a generator, so as an additional load of the internal combustion engine 1 to effect. By this additional load of the internal combustion engine 1 is by the internal combustion engine 1 an increased heat flow from the cylinders 3 through the exhaust pipe 5 to the particle filter 6 hin causes. By this measure, a stronger heating of the particulate filter 6 and an improved regeneration of the particulate filter 6 supported or, in particular, only possible in phases with very low load. Since a minimal state of charge min of the battery is assumed here, this operation of the electric machine 2 as a generator also in the operating phase 1 be maintained very reliable with low vehicle load. However, this condition ends at the time t2 , because of the data of the navigation system 11 the imminent operation of the vehicle in a driving segment 2 with changing vehicle load is known. It is therefore in the phase between t2 and t3 again causes some discharge of the battery t12 at the time t3 at which the traveling segment II starts, a desired average state of charge mid of the battery 12 to reach. This discharging the battery 12 but is only done so if anyway in this period t2 to t3 the regeneration of the particulate filter 6 can be maintained. The regeneration has a higher priority than the achievement of a desired state of charge of the battery 12 , Since the loads of the internal combustion engine vary even in phase I here short periods of time may be possible in which not regenerated simultaneously and the battery is discharged. In such a case it is then preferable to maintain regeneration. At the time t3 then begins the operating phase 2 with changing vehicle load, in which then the electric machine 2 alternately used once as a generator and once as a drive.

Accordingly, in these phases, electrical energy is introduced into the battery 12 stored or from the battery 12 taken. Both measures serve the load of the internal combustion engine 1 to maintain in a desired middle range, for regeneration of the particulate filter 6 is advantageous. This average load range is characterized in that a reliable regeneration of the particulate filter 6 by a sufficient amount of heat from the internal combustion engine 1 in the particle filter 6 is introduced to ensure. In addition to the regeneration but too high load peaks should be avoided because such high peak loads are detrimental to other constraints that must be met by the exhaust system of the vehicle. In particular, at very high load peaks, increased nitrogen oxide values may occur in the exhaust gas, which must be compensated for by other appropriate measures. Since in the phase of the regeneration of the particulate filter this regeneration operation is to be optimized, however, such further boundary conditions are disadvantageous due to increased nitrogen oxide values and may possibly lead to the regeneration having to be stopped or not optimally proceeding, since other measures have to be taken to reduce the nitrogen oxide levels. In phases of high load of the vehicle, it is therefore advantageous to have a sufficient amount of electrical energy in the battery to possibly the internal combustion engine 1 to relieve and thus keep them in a range in which easily a regeneration of the particulate filter 6 is possible and at the same time only small other measures must be taken to reduce the nitrogen oxide levels.

After the time t5 there is a driving segment III, which is characterized by a high vehicle load. To prepare this driving segment III with a high vehicle load is therefore in the time window between t4 and t5 a high state of charge of the battery 12 at the time t5 prepared. This is done in the time window between t4 and t5 again a generatoric operation, the electric machine 2 at the time t5 a desired maximum state of charge of the battery 12 manufacture. This optimal state of charge of the battery 12 is then used in the driving segment III to the internal combustion engine 1 to relieve in which the electric machine 2 provides a part of the load required on the drive shaft. It can therefore be in the time window between t5 and t6 the regeneration of the particulate filter 6 completed successfully, ie a majority of the particle filter 6 contained particles are burned and the particle filter 6 now has its original storage capacity for particles again. At the time t6 At the end of the regeneration, the battery has a state of charge that is well below the mean value mid. In the time after the time t6 therefore becomes the electric machine 2 again operated as a generator mode to restore a medium state of charge of the battery 12 manufacture. Starting from this average state of charge can then again a load or discharge of the internal combustion engine 1 through the electric machine 2 take place, this loading and unloading by the electric machine 2 no longer the optimization of a regeneration operation but the optimization of other operating parameters of the internal combustion engine 1 serves.

In general, it should be noted that the continuation of the regeneration in all operating states has a higher priority than the setting of a desired state of charge of the battery 12 , If, for example, in the period t2 to t3 or in the period t4 to t5 due to the charging or discharging of the battery, the regeneration would have to be interrupted, the desired charging cycle is not maintained but the regeneration is continued. The desired charging cycle is then continued when the operating parameters of the internal combustion engine again a regeneration and at the same time the desired charge or discharge of the battery 12 enable.

Regarding the 2 became the segment II with changing vehicle load at the time t3 a middle charge state mid produced. This has been achieved in the phase t2 to t3 the electric machine was operated as a drive. If at the time t2 but the state of charge SOC of the battery 12 is below the mean state of charge mid, so would be in phase t2 to t3 the electric machine 2 operated as a generator to achieve this state of charge.

In the 3 The individual steps of the method according to the invention will now be described with reference to a flow chart. In a first process step 301 First, the query is whether a regeneration of the particulate filter is activated or not. If at the time of the query of the step 301 already done this particle filter, so follow the step 301 the steps 306 . 307 and 309 , If at the time of the query of the step 301 no regeneration of the particulate filter 6 takes place, then follow the process steps 302 . 303 . 304 and 305 , When diagnostics is activated, the process step 306 first queried, whether due to the data of the navigation device 11 soon a change of the driving segment is predicted. If no such change of a drive segment is predicted, then follow the step 306 again the starting step 301 , If a change of the driving segment is predicted, then follow the step 306 the step 307 , Essential for the decision of the step 306 is that switching to the step 307 sufficiently before the change of the driving segment is done so that there is still a sufficient time to bring the battery in a corresponding desired state of charge. For this purpose, either a fixed predetermined time can be used, which is usually sufficient to a sufficient state of charge of the battery 12 bring about. Alternatively, however, calculations can also be made that determine the current state of charge and the desired state of charge of the battery for the corresponding travel segment 12 consider. Depending on the difference of the current state of charge and the desired state of charge when changing the driving segment can then be the decision to switch to the step 307 be postponed accordingly. In step 307 is then for the upcoming or predicted change of the driving segment a corresponding desired state of charge of the battery 12 defined and by a corresponding control of the electric machine 2 either as a generator or as drive of the drive shaft 4 , the desired desired state of charge of the battery 12 brought about. In step 309 Then there is a query whether the desired nominal state of charge of the battery 12 already reached or not. If the nominal state of charge has not yet been reached, follow the step 309 the step 307 , When the desired set state of charge is reached, follow the step 309 the step 306 in which it is again waited, whether another change of the driving segment is imminent.

When in step 301 has been determined that no regeneration of the particulate filter is currently granted, the step follows 302 , In step 302 It is checked if there is a demand to regenerate the particulate filter in the near future. If this is not the case, ie if there is no request for the regeneration of the particulate filter, then the step follows 302 again the step 301 , When in step 302 it is determined that there is a regeneration request for the particulate filter, the step follows 302 the step 303 , In step 303 the current driving profile is analyzed as to whether one of the three driving segments I, II or III is currently present and based on the current data of the Navigation system still lasts for a certain time or whether a change of the driving segment is predictable. On the step 303 then follows the step 304 in which as a result of the investigation of the step 303 a corresponding desired state of charge of the battery 12 is given. If due to the data of the navigation device 11 is provided for a longer period of time nor a driving segment I with a low load, so will correspond to a minimum state of charge of the battery 12 provided, as in the 2 in the time segment t0 to t1 is shown. In step 305 is then checked whether the target state of charge is reached. If the nominal state of charge is not reached, follow the step 305 again the step 304 , When the target state of charge is reached, then in step 305 the regeneration triggered, provided all other conditions for a regeneration of the particulate filter 6 are fulfilled. It then takes on the step 305 again the step 301 ,

The process steps of 3 describe only as a corresponding nominal state of charge of the battery 12 as a function of the current driving segment or of a predicted change of the driving segment. 3 contains no information as to how then the desired state of charge is used during the corresponding driving segment to the regeneration of the particulate filter 6 to support.

In the 4 Details of the regeneration during high load operation in segment III or an operation with relatively high load in segment II are still presented. In a first step 401 Once again, a running regeneration is detected. If the regeneration is currently running, follow the step 401 the step 402 , If no regeneration is currently done, follow the step 401 again the step 401 ie the procedure of 4 will not start. In step 402 Checks whether the NOx emissions are too high or the engine is operated in a critical operating range. If the NOx emissions are not above a threshold or the engine is not operating in a critical range, then follow the step 402 again the step 401 , If the NOx emissions are above a threshold or the engine is operating in a critical range, then follow the step 402 the step 403 , In step 403 it is checked whether by a shift of the load point, the NOx emissions can be brought into an acceptable range without thereby the regeneration of the particulate filter is deteriorated. If not, then follow the step 403 again the step 401 and if so, follow the step 403 the step 404 , The transition from the step 403 on the step 404 is preferably at high engine loads, because then the NOx emissions are very high and due to the associated with a high load heat generation is no danger to interrupt the regeneration of the particulate filter. In step 404 is then checked whether the electrical system allows a corresponding shift of the operating point of the engine. This requires the electric machine 2 to be able to provide a corresponding power to the drive shaft 4 to give off and the battery 12 must be able to provide the appropriate electrical energy. When in step 404 it is determined that the electrical system is not ready then the step follows 401 and if the readiness of the electrical system is established, then follow the step 404 the step 405 , In step 405 Then, by an intervention of the electrical system, the operating point of the internal combustion engine 1 shifted so that a reduction of the NOx release takes place without thereby the regeneration of the particulate filter 6 would be worsened.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• EP 2157407 B1 [0002]

Claims (9)

Method for regenerating a particle filter (6) of a vehicle, the vehicle having an internal combustion engine (1), an electric machine (2), a navigation device (11) and a battery (12), wherein the electric machine (2) drives the vehicle Vehicle is operable together with the internal combustion engine (1) or alone or as a generator, wherein due to a predicted by the navigation device (11) route, a prediction of driving segments (I, II, III) with low or high vehicle load, wherein to assist a regeneration of the particle filter (6) in front of a driving segment (I) with low vehicle load, the electric machine (2) is operated as a drive until a predetermined low state of charge of the battery (12) is reached, and wherein before a driving segment (III) with high vehicle load, the electric machine (2) is operated as a generator until a predetermined high state of charge of the battery (12) is reached. Method according to Claim 1 characterized in that the regeneration of the particulate filter (6) in the low load vehicle segment (I) by operating the electric machine (2) as a generator and the regeneration of the particulate filter in the high load vehicle segment (III) by operating the electric vehicle Machine (2) is supported as a drive. Method according to Claim 1 , characterized in that when a driving segment (II) is predicted with changing vehicle load, the electric machine (2) is operated as a traction drive or as a generator to achieve a predetermined average state of charge of the battery (12). Method according to Claim 3 , characterized in that the regeneration of the particulate filter (6) in the driving segment (II) with changing vehicle load is temporarily supported by operating the electric machine (2) as a generator and temporarily by operating the electric machine (2) as a drive. Method according to one of the preceding claims, characterized in that when the regeneration has not yet started, before the start of the regeneration of the desired state of charge of the battery (12) is produced and that after reaching the desired state of charge of the battery (12) the regeneration is started , Method according to one of the preceding claims, characterized in that during regeneration due to the prediction of a change of the driving segment, a desired state of charge of the battery is made before the change of the driving segment. Method according to one of the preceding claims, characterized in that when entering a destination in the navigation device (11) in a request for regeneration, a route is proposed, which favors a regeneration of the particulate filter. Method according to one of the preceding claims, characterized in that during ongoing regeneration, a check is made whether the emissions of NOx of the internal combustion engine (1) can be reduced by the operation of the electric machine (2) without significantly impairing the regeneration and Furthermore, a check is made whether the state of charge of the battery (12) is sufficiently high, and if the tests are positive, the electric machine (2) is operated as a drive to reduce the NOx emissions. Device for regenerating a particle filter (6) of a vehicle, the vehicle having an internal combustion engine (1), an electric machine (2), a navigation device (11) and a battery (12), wherein the electric machine (2) drives the vehicle Vehicle is operable together with the internal combustion engine (1) or alone or as a generator, wherein due to predicted by the Navigationsgerat (11) route, a prediction of driving segments (I, III) takes place with low or high vehicle load, characterized in that means are provided to assist a regeneration of the particulate filter (6) in front of a driving segment with low vehicle load operate the electric machine as a drive until a predetermined low state of charge of the battery (12) is reached, and that the means before a driving segment with high vehicle load, the electric machine (2 ) operate as a generator until a predetermined high state of charge of the battery is reached.

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