DE102017201597A1 - EXHAUST TREATMENT SYSTEM IN WHICH A RESPONSE IS INJECTED INTO A TURBOCHARGER BYPASS CHANNEL - Google Patents

Abstract

There is provided an exhaust treatment system for a vehicle. The exhaust system includes: an exhaust passage, a turbocharger turbine provided at the exhaust passage, a turbocharger bypass passage including first and second ends, the first end upstream of the turbocharger turbine being in fluid communication with the exhaust passage and the second end downstream of the process the turbocharger is in fluid communication with the exhaust passage, an exhaust aftertreatment device provided downstream of the turbocharger bypass passage, and an injector provided at the turbocharger bypass passage and configured to introduce a reactant into the turbocharger bypass passage ,

Description

The present disclosure relates to an exhaust system for a motor vehicle and is particularly, but not exclusively, concerned with an exhaust system designed to enhance the effectiveness of one or more exhaust treatment devices provided in the system.

Vehicles, such as automobiles, are typically equipped with exhaust aftertreatment devices that are designed to reduce the amount of environmentally harmful substances that are present in gases emitted from the vehicle. The exhaust aftertreatment devices often include a catalyst that is heated to an ignition temperature by the exhaust gases before it starts to efficiently remove pollutants from the exhaust gas.

With the efficiency of modern engines, exhaust gases are expelled from the engine at reduced temperatures. Therefore, the amount of time required for exhaust aftertreatment devices to reach the desired operating temperature increases.

Under the legislation of the Euro 6 emission standard, emissions in all real-world driving cycles must comply with the legally regulated emission limits and thus emissions must be controlled at both higher and lower temperatures.

Therefore, an exhaust aftertreatment device that can operate efficiently in a range of elevated temperatures is desirable.

According to another aspect of the present disclosure, there is provided an exhaust system for a vehicle, comprising: an exhaust passage, a turbocharger turbine provided on the exhaust passage, a turbocharger bypass passage including first and second ends, the first end upstream of the engine Turbocharger turbine is in fluid communication with the exhaust passage and the second end downstream of the turbocharger in fluid communication with the exhaust passage, an exhaust aftertreatment device, which is provided downstream of the turbocharger bypass passage, an injector, which is provided and designed for the turbocharger bypass passage to introduce a reactant comprising hydrogen into the turbocharger bypass passage, and a hydrogen source configured to provide the hydrogen to the injector.

The turbocharger bypass passage and / or the injector may be configured such that the reactant first mixes with the exhaust gases in the turbocharger bypass passage.

The exhaust aftertreatment device may include a catalyst configured to catalyze a reaction between the exhaust gases and the reactant. The catalyst may comprise a zeolite catalyst. Additionally or alternatively, the catalyst may comprise a platinum group metal catalyst, a selective catalytic reduction catalyst, and / or a diesel oxidation catalyst.

The injector may be configured to introduce the reactant to the exhaust aftertreatment device during a regeneration event. Additionally or alternatively, the injector may be configured to introduce the reactant to the aftertreatment device during a DeNOx and / or DeSOx event.

The hydrogen source may include a hydrogen generator configured to generate hydrogen when required by the exhaust system. The hydrogen generator may be required to generate the amount of hydrogen to be injected by the injector. Additionally or alternatively, the hydrogen generator may be configured to generate hydrogen for storage in a reservoir of the hydrogen source. The hydrogen generator can only be used to generate hydrogen if insufficient hydrogen is available in the container.

The exhaust system may further include a bypass valve. The bypass valve may be configured to control the flow of exhaust gases through the turbocharger bypass passage. Additionally or alternatively, the bypass valve may be configured to control the pressure of the exhaust gases in the turbocharger bypass passage.

The exhaust aftertreatment device may include a selective catalytic reduction device. Additionally or alternatively, the exhaust aftertreatment device may include a lean NOx trap.

According to another aspect of the present disclosure, there is provided a method of operating a vehicle, the vehicle comprising: an engine, an exhaust passage, a turbocharger turbine provided on the exhaust passage, a turbocharger bypass passage including first and second ends; wherein the first end upstream of the turbocharger turbine is in fluid communication with the exhaust passage and the second end of the turbocharger is in fluid communication with the exhaust passage, an exhaust aftertreatment device provided downstream of the turbocharger bypass passage, the exhaust treatment device including a catalyst, an injector provided on the turbocharger bypass passage, and a hydrogen source configured to provide hydrogen to the injector, the method comprising: introducing a reagent comprising hydrogen from the hydrogen source into the turbocharger bypass passage using the injector.

The method may further include operating the engine under rich combustion conditions. The reactant may be introduced while the engine is operating under rich combustion conditions.

Additionally or alternatively, the method may further include operating the engine to increase the temperature of the exhaust gases. The reactant may be introduced while the engine is operating to increase the temperature of the exhaust gases.

In other words, the reactant may be introduced while the engine is running under hot and / or rich combustion conditions.

The vehicle may further include a bypass valve configured to control the flow of exhaust gases through the turbocharger bypass passage. The method may further include operating the by-pass valve to alter a flow rate of exhaust gases through the bypass passage during introduction of the reactant. For example, the flow rate of bypass exhaust gases may be increased or decreased while injecting the reactant.

Additionally or alternatively, the method may include operating the bypass valve to change a pressure of the exhaust gases in the bypass passage during the introduction of the reactant. For example, the pressure of the bypass exhaust gas may be increased or decreased while the reactant is being injected.

The bypass valve may be controlled to minimize reactions between the reactant and the exhaust gases upstream of the catalyst.

The reactant may comprise any substance designed to react with the exhaust gases in the presence of the catalyst. For example, the reactant may include unburned hydrocarbons, a reformer gas, and / or ammonia gas.

In accordance with another aspect of the present disclosure, a vehicle is provided that includes the exhaust system according to any preceding aspect of the disclosure.

To avoid unnecessary duplication and repetition of text in the specification, certain features are described only in terms of one or more aspects or only one or more embodiments of the invention. It is to be understood, however, that features described with respect to any aspect or embodiment of the invention, where technically possible, will also be used with any other aspect or any other embodiment of the invention within the scope of the claims can.

For a better understanding of the present invention and to more clearly illustrate how this may be carried into effect, reference will now be made, by way of example, to the accompanying drawings. Show it:

1 a schematic view of an engine and an exhaust system according to embodiments of the present disclosure and

2 A method of operating a vehicle according to embodiments of the present disclosure.

In terms of 1 includes a vehicle 1 an engine 2 , a turbocharger 3 , an air intake 4 , an exhaust gas recirculation (EGR) system 6 and an exhaust system 8th , As in 1 shown includes the engine 2 a turbocharged diesel engine, however, it is also contemplated that the present invention could be applied to another type of vehicle engine, such as a gasoline engine. Additionally or alternatively, the engine may be a naturally aspirated engine or may comprise a compressor and / or be equipped with another form of reinforced feed. The vehicle may include an additional engine, such as an electric motor and the engine 2 can be part of a hybrid drive system.

In 1 occurs over the inlet 4 Air and is through a turbocharger compressor 3a compressed before going to an intake manifold 2a the motor is guided. Process upstream of the intake manifold 2a can a throttle 5 be provided to control the flow of air to the intake manifold. The air gets over the intake manifold 2a in the engine 2 sucked. The intake air is in the engine 2 mixed with fuel and the mixture is burned to provide power for propulsion of the vehicle and for supplementary systems, such as electrical systems, in the vehicle are provided. The burning of the fuel and the intake air produces exhaust gases containing water vapor, carbon dioxide (CO ₂ ), carbon monoxide (CO), nitrogen oxides (NO _X ), sulfur oxides (SO _X ), particulate matter (PM) and other substances that are over an exhaust manifold 2 B be ejected.

The EGR system 6 includes a return channel 6a and a recirculation valve 6b , which is designed for an exhaust gas flow in the return channel 6a to control. As in 1 shown includes the EGR system 6 a high pressure EGR system that is designed to recirculate exhaust gases before the gases pass through a turbocharger turbine 3b be extended. However, it is also envisaged that the EGR system 6 may include a low pressure EGR system in which exhaust gases after expansion by the turbocharger turbine 3b be returned. The vehicle may include a combination of low pressure and high pressure EGR system. Alternatively, the vehicle may not include an EGR system. The EGR system 6 allows some of the exhaust gases back to the engine inlet 2 respectively. Exchanging a portion of the oxygen-rich air with combustion exhaust gases reduces the ratio of contents of each cylinder available for combustion. This leads to a lower heat release and a lower maximum cylinder temperature and thereby reduces the formation of NO _x .

The exhaust system 8th includes upstream of an exhaust outlet 14 an exhaust duct 9 , a turbocharger turbine 3b , a lean NO _x trap (LNT) 10a and / or a selective catalytic reduction device (SCR device) 10b ,

Exhaust gases that do not have the EGR system 6 be recycled, enter a high pressure section 9a the exhaust duct 9 one. The turbocharger turbine 3b is so on the exhaust duct 9 provided that exhaust gases flowing through the exhaust passage, z. As the main flow of exhaust gases through the turbocharger turbine 3b be extended to a low pressure section 9b the exhaust duct 9 to reach. The turbocharger turbine 3b is provided on the same shaft as the turbocharger compressor 3a and configured to drive the compressor to compress the intake air and a boosted supply to the engine 2 provide.

The exhaust system 8th further includes a turbocharger bypass passage 12 , The turbocharger bypass channel is at a first end 12a in fluid communication with the high pressure section 9a the exhaust duct, z. B. at a position of the exhaust passage 9 upstream of the turbocharger turbine 3b , The turbocharger bypass channel 12 is at a second end 12b in fluid communication with the low pressure section 9b the exhaust duct, z. B. at a position of the exhaust passage 9 process down the turbocharger turbine 3b , The turbocharger bypass channel allows some of the exhaust gases on the turbocharger turbine 3b passing out.

It can be a turbocharger bypass valve 11 be provided to control the amount ratio of the exhaust gases flowing through the turbocharger turbine and / or the turbocharger bypass passage. Controlling the exhaust gases in this way makes it possible to control the level of boost pressure provided by the turbocharger. As in 1 shown, the turbocharger bypass valve 11 at the exhaust duct 9 provided and configured to the exhaust gas flow through the turbocharger turbine 3b to control, for. B. such that more or less exhaust gases flow through the turbocharger bypass channel. Additionally or alternatively, the turbocharger bypass valve 11 at the turbocharger bypass channel 12 provided and configured to control the exhaust flow through the turbocharger bypass passage 12 directly to control. The turbocharger bypass valve 11 may be on or off to the first end 12a be provided of the bypass channel. Additionally or alternatively, the turbocharger bypass valve 11 on or to the second end 12b be provided of the bypass channel. And again in addition or alternatively, the bypass valve 11 anywhere between the first and second ends 12a . 12b be provided. For example, the turbocharger bypass valve 11 process up and / or process downstream of the injector 22 be provided as described below.

When the diverted exhaust gases bypass the channel 12 leave, z. B. process down the second end 12b , the diverted exhaust gases can with the main flow of exhaust gases in the low-pressure section 9b Mix. Alternatively, the exhaust gases mix downstream of the second end due to the relative flow characteristics, such as pressure, velocities, and / or flow regimes of the main exhaust stream and the redirected exhaust stream 12b possibly not before reaching the LNT 10a and / or the SCR device 10b , In any case, both the main flow of exhaust gases and the diverted exhaust gases through the LNT 10a and the SCR device 10b be guided.

The LNT 10a typically contains a zeolite catalyst that allows the adsorption of NO _x compounds (especially NO and NO ₂ ) from the exhaust gases. Zeolite is able to adsorb a limited amount of NO _x and as the trap fills, the NO _x adsorption rate is reduced. Once the trap is full, NO _x can no longer be adsorbed and the zeolite must be purified to allow more NO _x to be adsorbed.

To the LNT 10a To clean, the engine may be operated under rich combustion conditions, which may lead to generating an increased concentration of reducing substances in the exhaust gases, such as unburned hydrocarbons (HC). The engine may also be controlled to increase the temperature of the exhaust gases. The increased concentration of reducing substances and the high temperature may cause the trapped NO _x to be converted into nitrogen and water that may be expelled from the vehicle.

While in use, the LNT 10a also capture SO _x from the exhaust gases. The trapped SO _x can also be stored in the zeolite catalyst. The storage of the SO _x may reduce the ability of the catalyst to store NO _x . Thus, when the amount of SO _x stored in the zeolite increases, the frequency of purification of the LNT may be necessary 10a to increase. In order to reduce the amount of SO _x stored in the zeolite, it may be desirable to perform a desulfurization (DeSO _x ) operation. The DeSO _x process may also include operating the engine under rich combustion conditions with elevated exhaust gas temperature, but it may be necessary to use the LNT 10a to heat to higher temperatures than during a purge event to remove the stored SO _x .

The LNT 10a may further comprise an oxidation catalyst. The LNT may include, for example, a platinum group metal catalyst, such as a platinum, palladium, osmium, iridium, ruthenium, or rhodium catalyst. The LNT can thereby be designed to capture nitrogen oxides and catalyze the oxidation of other substances in the exhaust gases. During operation of the vehicle 1 For example, the oxidation catalyst itself can be oxidized. When the LNT is purified as described above, the increased concentration of reducing substances in the exhaust gases can lead to the reduction of the oxidation catalyst. This may allow the catalyst to continue catalyzing the oxidation reaction of substances in the exhaust gases.

The SCR device 10b in the 1 The illustrated exhaust system includes a catalyst configured to catalyze a reduction reaction to reduce the concentration of environmentally harmful substances, such as NO _x , in the exhaust gas. Upstream of the SCR device, typically a reductant is injected, for example by an SCR dosing system (not shown), which reacts with the exhaust gases in the presence of the SCR catalyst. For example, NOx _can be reduced by the reducing agent to nitrogen gas and water vapor. In a typical SCR device, ammonia is used as the reducing agent. The dose of the reducing agent can be controlled to determine the efficacy, _x is removed with the NO in the exhaust gases.

In other arrangements (not shown), the exhaust system 8th include a passive NO _x adsorber (PNA), which may be known as LNT Lite. The PNA may be configured to capture NO _x from the exhaust gases at or below a first temperature and exhaust NO _x into the exhaust gases at or above a second temperature. The PNA may also be designed to oxidize hydrocarbons, carbon monoxide and / or other substances in the exhaust gases with the aid of a catalyst.

In a further arrangement (not shown), the exhaust system 8th a diesel particulate filter (DPF) comprising a filter structure designed to trap particulate matter and soot from the exhaust gases. The filter structure may be a disposable filter. Alternatively, the DPF may be configured to regenerate the filter by degrading and releasing the captured particulate matter. The particulate filter may include a catalyst configured to enhance the removal of entrained particulate matter from the filter during regeneration.

Additionally or alternatively, the exhaust system 8th a diesel oxidation catalyst (DOC) (not shown). The DOC typically comprises a substrate coated with a catalyst such as a platinum group metal catalyst designed to catalyze an oxidation reaction of substances in the exhaust gases such as CO, HC and PM.

And additionally or alternatively, the exhaust system may include a combined aftertreatment device, such as a combination of a selective catalytic reduction device and a diesel particulate filter (SCR / DPF), which combines the functions of the devices described above. If desired, another exhaust aftertreatment device may be included. The exhaust aftertreatment devices may be provided in the exhaust system in any order.

Once the exhaust gases through the LNT 10a and the SCR 10b they can pass through the outlet 14 be ejected from the vehicle. Process upstream of the outlet 14 can be an exhaust emission sensor 16 , such as a NO _x sensor, may be provided to determine emissions generated by the vehicle. The emission sensor 16 recorded emission levels along with a reading from an engine emission sensor 18 used to determine the efficiency with which the LNT 10a and the SCR 10b work to remove pollutants from the exhaust gases. The particular efficiency can be used to determine the amount of reducing agent that the SCR device 10b should be added, and / or when the LNT 10a should be cleaned.

The vehicle 1 further includes a source of hydrogen 20 , The hydrogen source 20 may comprise a container designed to store hydrogen and which may be replenished as needed, e.g. B. when it is empty. Additionally or alternatively, the hydrogen source 20 a hydrogen generator designed to generate hydrogen by electrolysis, reformation or other suitable process. Hydrogen may be generated during operation of the vehicle when required for use by systems of the vehicle. The hydrogen generator may be configured to generate the amount of hydrogen needed to operate the vehicle. Alternatively, excess hydrogen, e.g. As hydrogen, which is not immediately required, generated and stored in the container. The hydrogen generator may not be operated to produce hydrogen if sufficient hydrogen is available in the vessel. Additionally or alternatively, hydrogen may be generated, even if not needed immediately, and may be stored in the tank for use when needed.

As in 1 shown, includes the exhaust system 8th also an injector 22 , The injector 22 is at the turbocharger bypass channel 12 provided and designed to introduce hydrogen into the bypass channel, z. B. directly into the bypass channel 12 , The injector can z. B. via a hydrogen channel 24 such in fluid communication with the hydrogen source 20 stand that hydrogen selectively from the hydrogen source 20 in the turbocharger bypass channel 12 can be introduced. The injector may be controllable to selectively change the pressure at which hydrogen is introduced into the bypass channel.

Providing the injector 22 at the turbocharger bypass channel 12 can for the engine packaging and the leadership of the hydrogen channel 24 from the hydrogen source 20 be beneficial. Additionally or alternatively, the provision of the injector 22 at the turbocharger bypass channel 12 for the performance of the exhaust system 8th be advantageous, as will be described below.

Hydrogen gas entering the turbocharger bypass channel 12 can be introduced in the exhaust fumes to the LNT 10a and / or the SCR device 10b to reach. Wassersoff, the SCR device 10b can serve as a reductant and can be used in the presence of the SCR catalyst or other catalyst used in the SCR device 10b is provided with substances in the exhaust gas, such as NO _x , react. The reaction between the hydrogen and the exhaust gases may occur at a lower temperature than the reaction between ammonia and the exhaust gases, and thus may use hydrogen as the reducing agent in the SCR device 10b the temperature range over which the SCR device is able to operate can be increased. Additionally or alternatively, hydrogen may be present in the SCR device 10b react with oxygen to the temperature of the exhaust gases and / or the SCR device 10b to increase. Thus, the SCR device may reach a temperature at which ammonia is at an earlier point, e.g. B. time, can be used effectively as a reducing agent in the drive cycle.

Hydrogen may be prior to introducing ammonia into the SCR in the turbocharger bypass channel 12 be introduced, for. B. at all temperatures. Alternatively, hydrogen and ammonia may be added at different times in a drive cycle and / or together, e.g. B, in combination. The relative amounts of hydrogen and ammonia introduced may vary according to vehicle operating conditions.

Under some conditions, such as when the exhaust and / or the SCR device 10b At a low temperature, it may be desirable to use only hydrogen in the turbocharger bypass channel 12 introduce. This may allow the SCR device to start operating using the hydrogen as the reducing agent to lower the levels of environmentally harmful substances such as NO _x at the low temperature. The hydrogen may also react with oxygen in the exhaust gases to raise the temperature of the SCR device.

If the temperature of the SCR device is high, it may not be advantageous to introduce hydrogen. For example, the rate of reaction between the hydrogen and the oxygen present in the exhaust gas is increased and the hydrogen can less effectively reduce _NOx or other pollutants present in the exhaust gases. Thus, at high temperatures, it may be desirable to use ammonia as the reducing agent.

At intermediate temperatures, it may be desirable to introduce both hydrogen and ammonia. By introducing both hydrogen and ammonia, the effectiveness of the SCR device can be increased (compared with the single use of hydrogen or ammonia) and the temperature of the SCR may continue to increase due to the reaction between the hydrogen and oxygen.

As stated above, the LNT adsorbs 10a during normal operation of NO _x from the exhaust gases and may also include an oxidation reaction of other substances in the exhaust gases, such as CO or HC, catalyze. Thus, during normal operation, it is the LNT 10a may not be advantageous to introduce hydrogen into the device. If the LNT 10a however, as described above, the introduction of hydrogen may be desirable. For example, hydrogen introduced during purification may react with the trapped NO _x , which may reduce the time required for the purge event, e.g. For example, the time during which the engine must be operated under rich combustion conditions. In addition, the hydrogen can reduce the temperature at which the adsorbed NO _x can be converted to nitrogen and water.

As stated above, it may also be necessary to carry out the DeSO _x process to remove SO _x that has been stored in the zeolite catalyst. The introduction of hydrogen during DeSO _x can improve the efficiency of the DeSO _x process. Hydrogen can diffuse deeper and / or faster into the zeolite catalyst, which can lead to an increased rate of SO _x removal. Additionally or alternatively, upon introduction of hydrogen, it may be possible to carry out the DeSO _x operation at lower temperatures and operating the engine under less lean conditions.

If the LNT 10a As described above, includes an oxidation catalyst, the introduction of hydrogen during the purification of the LNT 10a or during a DeSO _x event, increase the rate at which the oxidation catalyst is reduced, e.g. B. regenerated in order to be able to catalyze future oxidation reactions.

When hydrogen is provided for the purposes described above, the hydrogen may be upstream of the exhaust aftertreatment device 10a . 10b , eg in the exhaust duct 9 into which exhaust gases are injected. This is allowed to mix the hydrogen with the main flow of the exhaust gases, before this in the exhaust aftertreatment device, for. For example, the LNT 10a and / or the SCR device 10b , enter. The mixing of the hydrogen with the exhaust gases may be advantageous as it may increase the likelihood that hydrogen will be available to operate alongside the catalyst in the exhaust aftertreatment device (US Pat. 10a . 10b ) to react with the exhaust gases, z. B. to reduce NO _x or other pollutants in the exhaust gases. However, the mixing of the hydrogen and the exhaust gases upstream of the exhaust aftertreatment device may result in the oxidation of the hydrogen before the exhaust gases reach the catalyst. Thus, it may be desirable to control the mixing of the injected hydrogen with the main exhaust gases.

When hydrogen enters the turbocharger bypass channel 12 is injected as it is in 1 initially, the hydrogen may react with a controlled portion of the exhaust gases in the turbocharger bypass channel 12 mix before entering the main flow of exhaust gases in the exhaust duct 9 entry. Mixing the hydrogen with a limited portion of the exhaust gases is advantageous because it prevents excessive dilution of the hydrogen and / or oxidation of the hydrogen by the exhaust gases.

The turbocharger bypass valve 11 can be adjusted to control the flow rate of exhaust gases that accumulate in the turbocharger bypass channel 12 mix with the hydrogen. Adjusting the Turbocharger Bypass Valve 11 will also control the pressure of the exhaust gases in the turbocharger bypass channel 12 and / or in the low pressure section 9b of the exhaust duct.

Controlling the relative pressure of the hydrogen, the diverted exhaust gases, and / or the main exhaust stream allows the distribution of hydrogen in the exhaust gases at the LNT 10a and / or the SCR 10b to control. In addition, exhaust gases can pass through the turbocharger bypass channel 12 flow, be less turbulent than the main exhaust stream. The less turbulent nature of the bypass stream can limit the spread of hydrogen in the mainstream gases. The rate of distribution and / or mixing of the hydrogen may also be influenced by the relative flow characteristics, e.g. B. pressure, velocity and / or flow regime of the two exhaust streams, z. As the diverted exhaust gases and hydrogen and the main exhaust stream. Limiting the rate of distribution of hydrogen can reduce the rate of hydrogen oxidation and its effectiveness in improving the performance of the LNT 10a and / or the SCR device 10b increase as described above.

Based on 2 now becomes a procedure 200 for operating a vehicle. As described above, the vehicle may be the engine 2 , the exhaust duct 9 , the turbocharger turbine 3b , the turbocharger bypass channel 12 , the LNT 10a and / or the SCR device 10b and the injector 22 , the turbocharger bypass channel 12 is included, as in 1 shown. The procedure 200 includes a first step 202 in which a reagent, e.g. As hydrogen, using the injector 22 in the turbocharger bypass channel 12 is injected.

The procedure 200 can take a second step 204 in which the engine is operated under hot and / or rich combustion conditions. As described above, such engine operating conditions may be required to control the LNT 10a and / or the SCR device 10b It may therefore be advantageous to introduce hydrogen while the engine is operating under hot and / or rich combustion conditions.

The procedure 200 can take a fourth step 204 include in which the turbocharger bypass valve 11 is operated to the flow of diverted exhaust gases in the bypass channel 12 to control. As described above, controlling the bypass flow in this manner may affect the flow rate and / or the pressure of the exhaust gases in the bypass passage, which may affect the mixing and / or distribution of the injected hydrogen with the exhaust gases. The turbocharger bypass valve 11 can thereby be controlled to minimize reactions between the hydrogen and the exhaust gases upstream of the catalyst, which increases the effectiveness of the hydrogen in improving the performance of the LNT 10a and / or the SCR device 10b can maximize.

When the turbocharger bypass valve 11 is operated, for. B. in the fourth step 204 to the flow rate and / or the pressure of the exhaust gases in the turbocharger bypass channel 12 It is also possible to control the flow of exhaust gases through the turbocharger turbine 3b to be influenced. Additionally or alternatively, the process of injecting hydrogen into the bypass passage may itself control the flow of exhaust gases in the bypass passage 12 affect and thus the flow through the turbocharger turbine 3b , A change in the flow of exhaust gases through the turbocharger turbine 3b affects the power passing through the turbocharger 3b for the turbocharger compressor 3a what is provided for the engine 2 provided level of increased introduction, e.g. B. height of the boost pressure influenced. The turbocharger bypass, blades and / or turbocharger turbine nozzle 3b can be adjusted to compensate for changes in flow rate. Additionally or alternatively, the throttle 5 be adjusted to compensate for the change in the amount of boost pressure, z. To allow the engine to continue operating to provide the same performance as before. And again in addition or alternatively, the return valve 6b be adjusted to adjust the amount of exhaust gas recirculation and to compensate for the change in the boost pressure level.

Although the above description has been made with reference to the introduction of hydrogen into the exhaust gases, it is equally contemplated that using the injector 22 Any other reactant can be introduced, for example, HC, reformer gas, ammonia or a combination of different gases in the turbocharger bypass channel 12 be introduced.

Claims (23)

Exhaust system for a vehicle, comprising: an exhaust duct, a turbocharger turbine provided at the exhaust passage, a turbocharger bypass passage including first and second ends, wherein the first end upstream of the turbocharger turbine is in fluid communication with the exhaust passage and the second end downstream of the turbocharger is in fluid communication with the exhaust passage; an exhaust aftertreatment device provided downstream of the turbocharger bypass channel, an injector provided and designed for the turbocharger bypass channel introducing a reactant comprising hydrogen into the turbocharger bypass passage and a source of hydrogen configured to provide the hydrogen to the injector. The exhaust system of claim 1, wherein the exhaust aftertreatment device comprises a catalyst configured to catalyze a reaction between the exhaust gases and the reactant. The exhaust system of claim 1 or 2, wherein the injector is configured to introduce the reactant to the exhaust aftertreatment device during a regeneration event. The exhaust system of any one of the preceding claims, wherein the injector is configured to introduce the reactant to the aftertreatment device during a DeNOx or DeSOx event. The exhaust system of any one of the preceding claims, wherein the hydrogen source comprises a hydrogen generator configured to generate hydrogen when required by the exhaust system. The exhaust system of any one of the preceding claims, further comprising a bypass valve configured to control the flow of exhaust gases through the turbocharger bypass passage. The exhaust system of any one of the preceding claims, further comprising a bypass valve configured to control the pressure of the exhaust gases in the turbocharger bypass passage. An exhaust system according to claim 2 or any of claims 3 to 7 when dependent on claim 2, wherein the catalyst comprises a zeolite catalyst. An exhaust system according to claim 2 or any of claims 3 to 8 when dependent on claim 2, wherein the catalyst comprises a platinum group metal catalyst. Exhaust system according to one of the preceding claims, wherein the exhaust aftertreatment device comprises a device for selective catalytic reduction. Exhaust system according to one of the preceding claims, wherein the exhaust aftertreatment device comprises a lean NOx trap. Method for operating a vehicle the vehicle comprising: a motor, an exhaust duct, a turbocharger turbine provided at the exhaust passage, a turbocharger bypass passage including first and second ends, wherein the first end upstream of the turbocharger turbine is in fluid communication with the exhaust passage and the second end downstream of the turbocharger is in fluid communication with the exhaust passage; an exhaust aftertreatment device provided downstream of the turbocharger bypass passage, wherein the exhaust treatment device comprises a catalyst, an injector provided on the turbocharger bypass passage, and a hydrogen source configured to provide hydrogen to the injector, the method comprising: Introducing a reagent comprising hydrogen from the hydrogen source into the turbocharger bypass passage using the injector. The method of claim 12, wherein the method further comprises: Operating the engine under rich combustion conditions, wherein the reactant is introduced while the engine is operating under rich combustion conditions. The method of claim 12 or 13, wherein the method further comprises: Operating the engine to increase the temperature of the exhaust gases wherein the reactant is introduced while the engine is operating to raise the temperature of the exhaust gases. The method of claim 12, wherein the vehicle further comprises a bypass valve configured to control the flow of exhaust gases through the turbocharger bypass passage, the method comprising operating the bypass valve to change a flow rate Flow rate of the exhaust gases through the bypass channel during the introduction of the reactant comprises. The method of claim 12, wherein the vehicle further comprises a bypass valve configured to control the flow of exhaust gases through the turbocharger bypass passage, the method comprising operating the bypass valve to change a bypass valve Pressure of the exhaust gases in the bypass channel during the introduction of the reactant comprises. The method of claim 15 or 16, wherein the bypass valve is controlled to minimize reactions between the reactant and the exhaust gases upstream of the catalyst. The method of any one of claims 12 to 17, wherein the reactant comprises a reformer gas. The method of any one of claims 12 to 18, wherein the reactant comprises unburned hydrocarbons. The method of any one of claims 12 to 19, wherein the reactant comprises ammonia. A vehicle comprising the exhaust system of any one of claims 1 to 11. Exhaust system or vehicle, substantially as described herein with reference to the drawings and as shown in these. A method of operating a vehicle, substantially as described herein and with reference to the drawings.

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