EP2115280A1

EP2115280A1 - Method for operating a motor vehicle with an exhaust-gas heating apparatus

Info

Publication number: EP2115280A1
Application number: EP08701538A
Authority: EP
Inventors: Jörg-Roman KONIECZNY; Rolf BRÜCK; Jan Hodgson
Original assignee: Emitec Gesellschaft fuer Emissionstechnologie mbH
Current assignee: Vitesco Technologies Lohmar Verwaltungs GmbH
Priority date: 2007-02-06
Filing date: 2008-01-17
Publication date: 2009-11-11
Also published as: US20100037609A1; JP2010518301A; WO2008095752A1

Abstract

The present invention relates to a method for operating a motor vehicle (1) which has, as components, a drive means (2), an exhaust-gas system (3) for exhaust gases (6) of the drive means (2) with at least one heating apparatus (4) and at least one energy converter (11). The method comprises at least the following steps: (a) detection of a possibility for energy recovery, (b) activation of the at least one energy converter (11), (c) feeding of the energy which is recovered by the at least one energy converter (11) to the heating apparatus (4), (d) operating of the heating apparatus (4) for heating the exhaust gas (6) with the recovered energy, and (e) detection of an end of the possibility for energy recovery, after which the energy converter (11) is deactivated and the provision of the recovered energy is ended.

Description

Method for operating a motor vehicle with an exhaust gas heating device

The present invention relates to a method for operating a motor vehicle, which has as components a drive means, an exhaust system for exhaust gases of the drive means with at least one heating device and at least one energy converter. The invention finds particular application in the automotive industry.

It is to be regarded as known to bring the exhaust gas generated by an engine of a motor vehicle into contact with a heating device in order to influence the temperature of the exhaust gas. In addition, it is also to be regarded as known that such heaters are used, for example, just after a cold or restart of an engine or an exhaust system, the exhaust gases or the exhaust gas cleaning components, which are optionally provided with a catalytically active coating, quickly to the reaction temperature to bring, in particular to a temperature at which an interaction of the catalyst with the pollutants of the exhaust gas takes place.

As heaters in particular those have already been proposed which are heated as a result of ohmic resistance heating. The electrical conductor through which current flows at desired times is heated on account of its resistance and can thus heat the catalytically active material and / or the contacted exhaust gas positioned thereon. The designs of such heaters are varied, in particular wire-grid constructions, honeycomb bodies, plate constructions and similar apparatuses have already been described. With regard to the operation of such heaters is also to be regarded as known that they were activated before or with engine start or possibly shortly after engine start to improve the cold start behavior for a limited period of time, taking into account in particular that an electrical overload of the battery of the vehicle is avoided. In addition, it is also known to use such heating devices in combination with particle filters, in order to enable thermal regeneration of the trapped particles in case of need (eg a threatening blockage of the particle filter). For this purpose, it is known to activate the heating device when a predetermined operating period has elapsed and / or the particle load in the filter has reached a predetermined size.

However, the known purposes and / or deployment strategies only partially led to the desired results. In particular, it had to be stated that the use of the heating device sometimes results in an undesirably high energy requirement and that the activation cycles sometimes took very large periods of time.

On this basis, it is an object of the present invention, at least partially solve the problems described with reference to the prior art. In particular, a method is to be specified which enables an energy-saving and effective use of such heaters in exhaust systems of mobile internal combustion engines.

These objects are achieved by a method according to the features of claim 1. Further advantageous embodiments and fields of application of the invention are specified in the dependent formulated claims. It should be noted that the features listed individually in the claims can be combined with each other in any technologically meaningful way, and show further embodiments of the invention. The inventions In the following, training will be further specified in connection with the description and the figures, so that particularly preferred embodiment variants are also specified here.

The inventive method for operating a motor vehicle having as components a drive means, an exhaust system for exhaust gases of the drive means with at least one heater and at least one energy converter comprising at least the following steps: (a) detecting a possibility for energy recovery, (b) activating the at least one energy converter,

(c) supplying the energy recovered by the at least one energy converter to the heating device,

(d) operating the heater to heat the exhaust gas with the recovered energy, and (e) detecting an end of the opportunity for energy recovery, after which the energy converter is deactivated and the provision of the recovered energy is terminated

The method according to the invention therefore relates in particular to the regulation of a heating device in contact with the exhaust gas of an automobile engine so that a desired target parameter of the exhaust gas system or a component therein is reliably achieved.

In addition to known diesel or petrol engines, the drive means can also be any other comparable drive which ultimately produces an exhaust gas loaded with pollutant or an exhaust gas which is to be subjected to a temperature treatment. These include hybrid powertrains or propellants based on alternative energy sources that emit exhaust gases. The "exhaust system" is regularly formed with one strand (or several strands), in particular in the manner of a tubular conduit leading to a preferred flow direction, exhaust system is now provided at least one heating device, which spans at least partially over the inner cross section of the exhaust system in particular. In this case, the heating device preferably forms passages, channels or the like, through which the exhaust gas flows, wherein a large contact surface is realized. The heater may have additional functions in addition to its heating function, such as catalytic conversion, storage, or diversion of exhaust components.

According to step (a), first a possibility for energy recovery is detected. This happens, for example, in which at least one driving and / or operating state of the motor vehicle (preferably continuously) is monitored by means of a control device. In the case of predetermined states in which it is possible to recover energy, a corresponding signal is then generated, which indicates that there is the possibility of energy recovery. In the context of the invention can hereby optionally current, d. H. current conditions are used to determine the possibility of energy recovery. However, it is also possible to use future, expected, conditions in the recording of possibilities for energy recovery. This can be done for example by means of a GP S navigation device. If it is detected, for example, that a vehicle is located on a longer slope and the direction of travel also points in the direction of the descent, then it is to be expected that the vehicle will predominantly be in the braking or idling state in the near future and thus have an energy efficiency. recovery will be possible. In addition to such a very advantageous driving condition, which represents an excellent way to recover energy, but also in many other states or situations energy recoveries can be made. These are, for example, braking processes from high speeds or shorter slopes.

- A - In the subsequent step (b) of the method, at least one energy converter is then activated. If, as a result of step (a), a signal indicating the possibility of energy recovery is output, step (b) activates the energy converter as a result of the signal. The energy converter then preferably recovers kinetic energy which is stored or generated in the vehicle and converts it into another form of energy (preferably electricity) - recuperation. In addition to the conversion of kinetic energy, it is also conceivable to convert potential energy of the motor vehicle. This could be done, for example, by height changes within the framework of the suspension kinematics, where suspension travel can be used for energy recovery.

As an energy converter, for example, power generators come into consideration. These can convert the rotational movements of the wheels (in particular the braking energy) or the drive elements of the vehicle into electrical current. Alternatively, in hybrid vehicles but also their electric motors, which serve in a drive state for driving the vehicle, can be used in overrun operation as generators for generating electrical power. Other forms of energy converters may be compressors that convert rotational movements, for example of the drive elements, into pressure potentials of compressed-air reservoirs which will later be used directly or indirectly.

In step (c), the energy recovered by the at least one energy converter is then supplied to the heating device. This is done in the simplest case via conduit means, such as in the form of electrical lines, when the recovered energy is in the form of electrical currents. Nevertheless, step (c) can also be designed in several stages, wherein, for example, first an energy store is supplied with the recovered energy and, at a later time, the heating device is supplied as needed. The charging of the energy storage can also be done simultaneously or parallel to the supply of the recovered energy to the heater. The method according to the invention further provides, in step (d), to operate the heating device for heating the exhaust gas with the recovered energy. The heating device can act directly or indirectly on the exhaust gas to be heated. In a direct-acting heater, for example, heating coils are provided, which are arranged directly in the exhaust gas flow and are flowed around there by the exhaust gas. If, for example, they are caused to glow by electric current, the energy provided is emitted by the heating device to the exhaust gas flowing around it, which heats it up. The thus heated exhaust gas can then reach the required temperatures for complete exhaust gas purification faster. When operating an immediate heating device, this can act, for example, on the honeycomb body or other components of the exhaust system. This means the exhaust system or its components are heated by the heating device and in turn heat the exhaust gas flowing through the exhaust system. This results in the direct mode of action of the heater.

Depending on the form of use and the vehicle, the recovered energy can replace or supplement other energy sources in whole or in part. For example, while hitherto conventional heating devices are operated with electric currents which are provided by generators and vehicle batteries, they often lead to high loads on the electrical systems. Moreover, the use of 12 or 24 volt systems also results in a significant limitation with regard to the maximum possible power output of such systems. Based on this state of the art can now be replaced by the recovered energy completely or partially by means of the present invention, either derived from the usual energy sources heating energy. This leads to a particularly strong relief of the electrical systems. If a particularly high heating power is desired in other cases of application, for example, if required exhaust treatment as complete as possible, the recovered energy can also be used in addition to the previous heating energy sources for heating the exhaust gas, which significantly higher heating capacities than previously possible. In addition, it is now ensured that in driving situations that basically lead to cooling of the exhaust system, because no sufficient amount of hot exhaust gas is generated, directly takes place a heating of the "cooler" exhaust gases and thus the activity or effectiveness of the exhaust gas purification components of the exhaust system is maintained (especially for diesel engines).

Finally, in step (e) of the invention, the end of the opportunity for energy recovery is detected, after which the energy converter is deactivated and the provision of the recovered energy is terminated. This ensures that a vehicle is not braked in a state or otherwise removed energy, if this energy is primarily needed for other purposes. For example, an acceleration process may be mentioned in which the available power or amount of energy should be used as completely as possible for the acceleration of the vehicle. In such a driving state, it would not be desirable and sometimes even relevant to safety if the available drive power would be partially converted in the context of energy recovery. In step (e), the energy recovery is thus terminated and the vehicle is, as it were, placed in a waiting state in which it remains until a renewed possibility for energy recovery ensues.

It is very particularly preferred according to the present invention if the method described above is carried out at least at a partial load of the drive means or below a minimum exhaust gas temperature. A possible limit for a partial load range is 80%. That means that only if the drive means of the motor vehicle are operated with a load of 80% or less, an energy recovery is to be performed. Other load limits may be defined at, for example, 60% or 30%, thereby ensuring that no energy recovery is performed when the engine or drive means is operated at a power exceeding those partial load limits. In principle, the load limits can also be linked to an average and / or actual exhaust gas temperature, so that heating is already commensurate even at lower temperatures despite high partial load ranges (eg 80%). Conversely, at high exhaust gas temperatures, a heating can be omitted, even if the partial load is very small and, for example, less than 30%. This temperature used to control the heating then represents a predetermined exhaust gas minimum temperature (eg 400 ⁰ C, or 300 ⁰ C or even 200 ⁰ C), in the still sufficient effectiveness and exhaust aftertreatment is ensured by the exhaust gas purification device.

It is also particularly advantageous if steps (a) to (e) are carried out by a control device connected to the components. In this case, a control device is understood to be a device which is capable of detecting various parameter signals and / or measured values of a vehicle, analyzes these according to predetermined conditions, situations, states and / or laws and outputs corresponding control commands. Such a control device can be physically implemented on a device or in the vehicle distributed to a plurality of so-called control devices. In particular, it should also be noted that control programs are executed on such control devices in which the method steps are stored in program-technical form.

Control devices can be found in almost all modern vehicles and, by appropriate adaptation of control programs in a simple form, also for carrying out the method according to the present invention prepared and used. Such control devices are particularly powerful and can monitor and take into account a large number of parameters in real time in the decision making process. In particular, reference should also be made to a connection of control devices with navigation devices, which is advantageously possible in the context of the present invention.

According to another advantageous embodiment of the present invention, it is provided for the control device to continuously monitor at least one energy absorption capability or one energy emission capability of at least one energy store or one consumer. It can be provided that the energy-emitting capability and / or the energy-absorbing capacity of the energy store and / or consumer is monitored by a control device. Such consumers are, for example, the abovementioned heating device or else other energy consumers, such as control devices, electric drives of hybrid vehicles or electric vehicles, or even energy storage devices, such as, for example, accumulators or capacitors.

In particular, particularly powerful capacitors are known which serve in vehicles for temporary storage of large amounts of energy. Quite preferred is the use of double-layer capacitors, also called electrochemical double-layer capacitors (English: electrochemical double layer capacitor - EDLC) or supercapacitors called. Double-layer capacitors consist of two electrodes, which are wetted with an electrolyte. When a voltage is applied which is smaller than the decomposition voltage of the electrolyte, ions of opposite polarity collect at both electrodes. They form a zone of immobile charge carriers whose layer thickness is only a few molecule layers. Such double-layer capacitors have very high specific power density (watts / kg) compared to accumulators, which is determined by the internal resistance. Such high power densities favor applications for buffering consumers who require or give away a high current for a short time (In the automotive sector cited here, a corresponding electromotive brake can be used in electric, hybrid and gyro powered vehicles because they have sufficiently large drive motors and energy stores). These capacitors, in contrast to previously known accumulators electric energy very quickly and in large quantities caching. They are thus particularly suitable for short-term and rapid intermediate storage of the recovered energy.

In this respect, it is advantageous to monitor the energy storage capability and energy delivery capability of such energy stores in order to temporarily store the recovered energy provided by the energy converter there. It should be noted that in the case of intermediate storage, the recovered energy in a buffer of step (e) of the method of the invention may provide a time delay between the deactivation of the energy converter and the termination of the provision of the recovered energy. In the remaining time after the deactivation of the energy converter, the provision of the recovered energy can be done by means of the previously filled energy storage, which still emit the cached energy for a certain period of time to the heater. In this way, after an end of the recovery, a reheating with the cached energy can take place. This is particularly useful in idling phases, which, for example, follow directly or with a time delay to phases of energy recovery. An idle phase can, for example, form a waiting time in front of a traffic light system. Moreover, in some cases it may be useful to divide up the recovered energy and forward it to a plurality of consumers or stores. Thus, especially in vehicles with electric drives in the energy recovery a very high power output can occur. That means in a very short time will be a big one Generated amount of energy that needs to be consumed or stored. Such quantities of energy can be monitored and distributed, for example, by a control device. In this case, it makes sense, for example, to consume a part of the energy in a heating device and to store another part in a storage device, wherein both steps can be executed in parallel or in succession as a function of the amount of energy to be absorbed.

As already mentioned above, it is advantageously provided in the context of the present invention to carry out the method according to step (b) by means of at least one electric motor or generator. Such electric motors and / or generators are already used in modern vehicles, for example with hybrid drive or with pure electric drive, and can be used to generate electric currents and thus as energy converters. But even in previously driven exclusively by internal combustion engines vehicles such electric motors or generators can also be arranged as a drive or energy converter in the vehicle.

In addition, in the context of the present method for carrying out step (d), preferably at least one electrically heatable honeycomb body is used as the heating device. Such an electrically heatable honeycomb body may be formed either ceramic or metallic or a combination of both types of materials. Such heatable honeycomb bodies are also already known in the art in a variety of configurations and have also proven themselves beyond. In this case, preference is given to honeycomb bodies which are constructed with at least partially structured sheet metal layers which form electrically insulated, wound winding current paths which extend over the cross section of the honeycomb body.

It is also particularly advantageous if an exhaust gas mass flow is at least partially recycled during step (d). As a result, the relatively cold and aufzuschheizende exhaust gas mass flow can be significantly reduced in mass by this is at least partially slides back into the engine. By reducing the exhaust gas mass flow to be heated, the remaining non-recirculated exhaust gas mass flow can then be heated to a higher temperature or the heating power required for heating can be correspondingly reduced without lowering the temperature. Alternatively, both can be the case. In particular, a reduction of the heating power relieves the electrical system of the vehicle and allows a longer heating time with the recovered energy.

The invention is particularly advantageous for use in a motor vehicle, comprising at least one drive means and an exhaust system with at least one controllable heating device which can be brought into contact with exhaust gas, in which at least the heating device connected to a control device is arranged to carry out the method described herein.

The invention and the technical environment will be explained in more detail with reference to FIGS. It should be noted that the figures show particularly preferred embodiments of the invention, but this is not limited thereto. They show schematically:

1 shows a side view of a motor vehicle for carrying out the method according to the invention;

2 shows a plan view of the vehicle according to Fig. 1;

3 shows a plan view of a second embodiment of a motor vehicle; and 4 shows a plan view of a third embodiment of a motor vehicle.

In Fig. 1, a motor vehicle 1 for carrying out the method according to the invention is shown. The motor vehicle 1 consists of various components, which include, among other things, a drive means 2, an exhaust system 3 and a heater 4. The drive means 2 is embodied as an internal combustion engine 5, which produces an exhaust gas 6 and conveys it through the exhaust system 3 to a catalytic converter 7, from where it is passed through a rear part of the exhaust system 3 to a vehicle rear 8, where it exits to the outside , In addition to the heating device 4, the catalytic converter 7 also comprises a (at least one further) honeycomb body 9, which may be metallic or ceramic and may be provided with various catalytically active, adsorbing or further coatings. The hitherto incompletely "cleaned" exhaust gas 6 is treated at corresponding temperatures in the honeycomb body 9. To achieve the temperatures favorable or required for the conversion, the heating device 4 is arranged upstream of the honeycomb body 9.

At the wheels 10 each energy converter 11 are arranged, which are connected via conduit means 12 to the heater 4. Furthermore, the energy converters 11 are connected via control lines 13 to a control device 14.

2, the motor vehicle 1 of FIG. 1 is shown in a plan view. There, in turn, the control device 14 can be seen, which is connected via control lines 13 to each of the four energy converters 11 and in addition to the internal combustion engine 5. The control lines 13 serve either to send control commands or to query measured values and parameters. The term control line is thus also to be understood in the sense of a signal transmission line. In addition, it can be clearly seen in FIG. 2 that an energy converter 11 is arranged on each of the wheels 10. The recovered in each of the energy converters 11 ne electrical energy is introduced via the conduit 12 directly into the heater 4. In the embodiment shown, the execution of the method according to the invention by the controller 14 first detects the presence of the possibility of energy recovery and then outputs 13 signals to the energy converter 11 via the control lines to activate them. After activation of the energy converter 11, the kinetic energy of the rotating wheels is recovered by this and forwarded via the conduit means 12 in the form of an electric current to the heater 4, where they initiated according to the arrows shown and converted to heat the exhaust gas 6 to heat becomes. The energy converter 11 are formed in the illustrated embodiment as a follower generators that are continuously coupled to the wheels 10. You can, for example, be designed so that they rotate in the inactivated state almost without resistance with the wheels and not slow them down. Only at the time of their activation, a small excitation current can be applied to the generators, whereby they are activated as generators and begin with the generation of electrical energy. In another embodiment, it is quite possible to run the generators continuously, and only in the case of activation to make the line contact to the heater 4 and thus close a consumer circuit.

Thus, for example, a simple control either by the connection of the consumer in the form of the heater 4 or by applying an excitation current to the generators done.

FIG. 3 now shows a plan view of a motor vehicle 1, in which the drive means 2 is again designed as an internal combustion engine 5. In addition, an electric motor 16 is arranged on a front axle 15 of the motor vehicle 1 as an energy converter 11. The structure of the catalyst 7 corresponds to that of the previously described in connection with Figures 1 and 2 catalyst 7. Bei In this embodiment, the control device is in turn connected via a control line 13 to the internal combustion engine 5 and can thus acquire measured values and parameters from it. In addition, the control device 14 is connected via line means 12 both to the electric motor 16 and to the heating device 14. If a possibility for energy recovery is detected by the control device 14, it activates the electric motor 16 as an energy converter 11, so that it provides energy via the line 12 in the form of an electric current, which is forwarded by the control device 14 to the heater 4 and there is used to heat the exhaust gas flowing through the exhaust system 3 6. The vehicle shown here corresponds essentially to a so-called hybrid vehicle, in which the drive energy is first generated in an internal combustion engine and partly transmitted directly from the latter to the wheels 10. In other driving conditions, the energy generated by the internal combustion engine 5 is temporarily stored and then transmitted via the electric motor 16 to the wheels 10. In such a hybrid vehicle, the present invention can also be advantageously applied as previously shown.

FIG. 4 now shows a plan view of a further possible embodiment of a motor vehicle 1 which is suitable for carrying out the method according to the invention. Again, the drive means 2 is again designed as an internal combustion engine 5. Both on the front axle 15 and on a rear axle 17 are each an electric motor 16. Both electric motors 16 are used as an energy converter 11. In contrast to the embodiment shown in FIG. 3, the control device 14 can thus receive electrical energy from two drive shafts 15, 17 in the case of energy recovery. In addition, however, this embodiment also has an energy store 18, which is formed with a plurality of so-called supercapacitors. The control device 14 can thus be particularly well suited to complex driving conditions and vehicle states, in particular states of the electrical system. tems, to be adjusted. Thus, it is possible, for example, to initiate the electrical energy provided by the electric motors 16, which is obtained in the case of energy recovery, either into the heating device 4 or into the energy store 18 for intermediate storage. If the state of the energy recovery is then terminated and no further electrical energy is provided by the energy converters 11, the energy of the buffer 18 stored in the supercapacitors can optionally be used to drive the electric motors 16 or to heat the heating device 4. In a heating of the heater 4, it is then possible to clean particularly efficiently at a, for example, subsequent full-load operation of the internal combustion engine 5 resulting exhaust gases without delay at high temperatures. The exhaust system 3 and in particular the catalytic converter 7 can thus unfold its full effect again by means of the energy stored in the energy store 18 or the energy provided by the energy converter 11 immediately in the event of a renewed attack of exhaust gases and does not first have to be heated, what else additional external Heating energy or a longer period of time with hot exhaust gases would be required in which then only a partial or poor exhaust gas purification is achieved. In this case, as indicated by the two line means 12, the recovered energy is supplied in parallel to the energy storages 18 and the heating device 4.

Incidentally, the present invention is not limited to the illustrated embodiments. In the context of the invention, it is quite possible to design the illustrated arrangements of energy converters, control devices and heating devices within the exhaust system in numerous variants without departing from the spirit of the invention. For example, instead of the one heater, a plurality of heaters may be used. In addition, as already indicated, different numbers of energy converters 11 and energy 18, as well as different types of consumers, are taken into account by the control device 14.

LIST OF REFERENCE NUMBERS

1 motor vehicle

2 drive means

3 exhaust system

4 heating device

5 internal combustion engine

6 exhaust

7 catalyst

8 vehicle rear

9 honeycomb body

10 wheel

11 energy converters

12 conduit means

13 control line

14 control device

15 front axle

16 electric motor

17 rear axle

18 energy storage

Claims

claims

A method for operating a motor vehicle (1) comprising as components a drive means (2), an exhaust system (3) for exhaust gases (6) of the drive means

(2) with at least one heating device (4) and at least one energy converter (11), comprising at least the following steps:

(a) detecting a possibility for energy recovery,

(b) activating the at least one energy converter (11), (c) supplying the energy recovered by the at least one energy converter (11) to the heating device (4),

(d) operating the heating device (4) to heat the exhaust gas (6) with the recovered energy, and

(e) detecting an end of the opportunity for energy recovery, after which the energy converter (11) is deactivated and the provision of the recovered energy is stopped.

2. Method according to the preceding claim, wherein this is carried out at least at a partial load of the drive means (2) or below a Abgasemindest- temperature.

A method according to any one of the preceding claims, wherein steps (a) to (e) are performed by a control means (14) connected to the components.

4. The method according to any one of the preceding claims, wherein by a control device (14) continuously at least one energy absorption capability or an energy-releasing ability of at least one energy storage device (18) or a consumer (4) is monitored.

5. The method according to any one of the preceding claims, wherein step (b) is carried out by means of at least one electric motor (16) or generator.

6. The method according to any one of the preceding claims, wherein at least one electrically heatable honeycomb body (9) is used to perform the step (d) as a heating device (4).

7. The method according to any one of the preceding claims, wherein during the step (d) an exhaust gas mass flow is at least partially recycled.

8. motor vehicle (1) comprising at least one drive means (2) and an exhaust system (3) with at least one controllable and can be brought into contact with exhaust heating device (4), wherein at least the heating device (4) with a control device (14) is connected , which is set up to carry out a method according to one of the preceding claims.