Exhaust system, internal combustion engine and vehicle

Abstract

An exhaust system (50) for an internal combustion engine (40) is disclosed. The exhaust system (50) comprises a turbine device (1) for a turbocharging device (30). The turbine device (1) comprises a turbine housing (51) and a turbine unit (19) arranged to rotate in the turbine housing (51). The exhaust system (50) further comprises a bypass passage (11) having an inlet opening (12, 12 ', 14, 16) arranged upstream of a turbine outlet (29) of the turbine unit (19) and an outlet opening (22, 22') arranged downstream of the turbine outlet (29). The exhaust system (50) further comprises a NOx sensor (9) arranged to sense the NOx content of the exhaust gas flowing through the bypass passage (11). The disclosure also relates to an internal combustion engine (40) and a vehicle (2).

Description

Technical Field

[0001] The present disclosure relates to an exhaust system for an internal combustion engine, wherein the exhaust system comprises a turbine device for a turbocharger device. The present disclosure also relates to an internal combustion engine comprising the exhaust system and a vehicle comprising the internal combustion engine. Background Art

[0002] Turbochargers are used on internal combustion engines to improve the performance and / or fuel efficiency of the engine. One type of turbocharger is a turbocharger. A turbocharger includes a turbine unit and a compressor, wherein the turbine unit is driven by exhaust gases in the exhaust system of the engine to provide power to the compressor. The compressor forces air to the air intake of the engine, which allows more fuel to be added and therefore the power output of the engine to be higher. A turbocharger is an effective means of supercharging an engine because it uses the energy of the exhaust gases of the engine to compress the intake air of the engine.

[0003] Another type of turbocharger is a turbo compounder. A turbo compounder also includes a turbine unit driven by the exhaust gases of the engine. However, instead of powering the compressor, the energy recovered from the exhaust gases is sent to the output shaft of the engine or used for another purpose, such as powering a generator. The electricity generated can be used in an electric machine to generate motor power for the vehicle, or can be used to power one or more other subsystems of the vehicle. A turbo compounder is an effective means of increasing overall fuel efficiency because it is able to convert part of the energy of the exhaust gases into useful energy.

[0004] Since the turbine unit of the turbocharger is configured to extract energy from the exhaust gases of the engine, in most cases the temperature and pressure of the exhaust gases are higher upstream of the turbine unit than downstream of the turbine unit.

[0005] Environmental concerns and emission standards for motor vehicles have led to the development of combustion engine components that use exhaust additives such as reductants for diesel and / or ethanol exhaust gases. The reductant may include an aqueous solution of urea and may be used as a consumable in a selective catalytic reduction (SCR) catalyst to reduce nitrogen oxide NOx concentrations in exhaust emissions from an internal combustion engine.

[0006] Nitrogen oxides NOx are formed by the reaction between oxygen O2 and nitrogen N at high temperatures and pressures in the cylinders of the engine. In other words, when the operation of the engine is optimized for fuel efficiency, large amounts of nitrogen oxides NOx may be formed. The term NOx refers to several forms of nitrogen oxides, including nitrogen monoxide NO and nitrogen dioxide NO2.

[0007] A selective catalytic reduction device is a means of converting nitrogen oxides NOx into diatomic nitrogen N2 and water H2O with the aid of a catalyst using a reducing agent added to the exhaust gas flow adsorbed on a catalyst substrate of the SCR catalyst. The reducing agent may include a gaseous reducing agent, typically anhydrous ammonia, aqueous ammonia or urea. Some exhaust systems have been developed that include two or more SCR catalysts arranged in series.

[0008] In an internal combustion engine comprising a turbocharger and one or more SCR catalysts, the SCR catalyst(s) are usually arranged downstream of the turbine unit of the turbocharger. In this way, the SCR catalyst(s) have a lower impact on the exhaust gas flow from the exhaust valve of the combustion engine to the turbine unit.

[0009] The use of exhaust additives is associated with several problems and design difficulties. One problem is the need for effective mixing in order to achieve a uniform distribution of the exhaust additive across the surface area of ​​the catalyst substrate. The limited space available for mixing may result in inadequate mixing of the exhaust additive and the exhaust gas upstream of the catalyst substrate. Inadequate mixing between the exhaust additive and the exhaust gas reduces the reduction efficiency at the catalyst substrate and may result in the formation of deposits of the exhaust additive inside the exhaust system.

[0010] Modern engines typically include various sensors arranged to sense properties of the exhaust gases of the engine, such as one or more NOx sensors, one or more oxygen sensors, and one or more temperature sensors. A nitrogen oxide sensor, also known as a NOx sensor, is a device that can be used to detect nitrogen oxides in the exhaust gas flow from an internal combustion engine.

[0011] The NOx sensor can be arranged downstream of the SCR catalyst to measure the NOx content in the exhaust gas downstream of the SCR catalyst. In this way, the NOx conversion rate of the SCR catalyst can be monitored. In addition, the NOx sensor can be arranged upstream of the first SCR catalyst of the exhaust system. In this way, the NOx generation of the internal combustion engine can be monitored.

[0012] Placing various types of sensors in the exhaust system of an internal combustion engine is a problem. For example, sensors such as NOx sensors are sensitive components that may be damaged if subjected to excessive temperatures and pressures. In addition, some types of sensors (such as NOx sensors) cannot provide reliable data at excessive pressures and / or temperatures.

[0013] Furthermore, injecting exhaust additives into the exhaust gas stream may interfere with the measurements obtained by the sensor, and the sensor may provide erroneous data if mounted close to the exhaust additive injection point in the exhaust system. As an example, a NOx sensor may register ammonia from the exhaust additive as NOx. Furthermore, as described above, the space available inside the exhaust system is limited, and it may be difficult to position the exhaust additive dosing unit to obtain adequate mixing between the exhaust additive and the exhaust gas before the mixture reaches the catalytic substrate. Summary of the invention

[0014] It is an object of the present invention to overcome or at least alleviate at least some of the above mentioned problems and disadvantages.

[0015] According to a first aspect of the invention, the object is achieved by an exhaust system for an internal combustion engine, wherein the exhaust system comprises a turbine device for a turbocharger. The turbine device comprises a turbine housing and a turbine unit arranged to rotate in the turbine housing. The exhaust system further comprises a bypass channel having an inlet opening arranged upstream of a turbine outlet of the turbine unit and an outlet opening arranged downstream of the turbine outlet. The exhaust system further comprises a NOx sensor configured to sense the NOx content of exhaust gas flowing through the bypass channel.

[0016] Thereby, reliable data for obtaining the NOx content of the exhaust gas flowing through the bypass channel is provided, while avoiding conditions of NOx sensor damage caused by excessive temperature and / or pressure. Since the bypass channel comprises an inlet opening arranged upstream of the turbine outlet and an outlet opening arranged downstream of the turbine outlet, a continuous exhaust gas flow can be obtained through the bypass channel during operation of the exhaust system.

[0017] Furthermore, the NOx content of the exhaust gas flowing through the bypass channel is representative of the NOx content of the exhaust gas flowing through the turbine outlet, because the bypass channel is configured to receive the exhaust gas from an inlet opening arranged upstream of the turbine outlet. In this way, reliable data for obtaining the NOx content of the exhaust gas flowing through the turbine unit of the turbine arrangement is provided, while avoiding conditions of damage to the NOx sensor caused by excessively high temperatures and / or pressures.

[0018] Furthermore, since the bypass passage comprises an inlet opening arranged upstream of the turbine outlet and an outlet opening arranged downstream of the turbine outlet, conditions are provided for injecting exhaust additives into the exhaust gas at a position close to the turbine unit of the turbine arrangement without interfering with the measurement values ​​obtained by the NOx sensor. This is because the bypass passage is configured to receive the exhaust gas from the inlet opening arranged upstream of the turbine outlet of the turbine unit.

[0019] Therefore, due to these features, an exhaust system is provided which has the conditions for providing reliable data on the NOx content of the exhaust gases flowing through the turbine unit of the turbine device, is robust at the same time, and has the conditions for adding exhaust additives to the exhaust gases at a position close to the turbine unit in order to obtain a high degree of mixing between the exhaust additive and the exhaust gases without interfering with the measurements obtained by the NOx sensor.

[0020] Hence, there is provided an exhaust system that overcomes or at least mitigates at least some of the above problems and disadvantages. Hence, the above objects are achieved.

[0021] As understood from the above, the bypass channel is fluidly connected to the exhaust system at a position upstream of the turbine outlet of the turbine unit, and is fluidly connected to the exhaust system at a position downstream of the turbine outlet via the second opening. The bypass channel is called a "bypass" channel because the bypass channel bypasses at least the turbine outlet of the turbine unit. Because the pressure in the exhaust system is higher upstream of the turbine outlet than downstream of the turbine outlet under almost all operating conditions, a continuous exhaust gas flow through the bypass channel from the inlet opening toward the outlet opening can be ensured. This is because the turbine of the turbine device is configured to extract energy from the exhaust gas flow passing therethrough.

[0022] Optionally, the inlet opening of the bypass channel is arranged on the turbine housing. Thereby, it can be ensured that the exhaust gases from different cylinders of the combustion engine mix before flowing into the bypass channel via the inlet opening. In this way, conditions are provided for obtaining even more reliable data on the NOx content of the exhaust gases of the turbine unit flowing through the turbine arrangement. In addition, a space-saving solution is provided, which only requires a short bypass channel layout. In addition, since the temperature and pressure of the exhaust gases in the turbine housing are lower than those in the more upstream parts of the exhaust system, damage to the NOx sensor caused by excessive temperatures and / or pressures can be further avoided.

[0023] Optionally, the turbine housing comprises a turbine inlet, and wherein the inlet opening of the bypass channel is arranged on the turbine inlet of the turbine housing. Thereby, it can be ensured that the exhaust gases from different cylinders of the combustion engine are mixed before flowing into the bypass channel via the inlet opening. In this way, conditions are provided for obtaining even more reliable data on the NOx content of the exhaust gases of the turbine unit flowing through the turbine arrangement. In addition, a space-saving solution is provided, which only requires a short bypass channel layout. In addition, since the temperature and pressure of the exhaust gases in the turbine inlet of the turbine housing are lower than those in the exhaust gases in the more upstream part of the exhaust system, damage to the NOx sensor caused by excessive temperature and / or pressure can be further avoided.

[0024] Optionally, the turbine inlet comprises a turbine inlet vortex, and wherein the inlet opening of the bypass channel is arranged on the turbine inlet vortex. Thereby, it can be ensured that the exhaust gases from different cylinders of the combustion engine are mixed before flowing into the bypass channel via the inlet opening. In this way, conditions are provided for obtaining even more reliable data on the NOx content of the exhaust gases of the turbine unit flowing through the turbine device. In addition, a space-saving solution is provided, which only requires a short bypass channel layout. In addition, since the temperature and pressure of the exhaust gases in the turbine inlet vortex are lower than those in the more upstream part of the exhaust system, damage to the NOx sensor caused by excessive temperature and / or pressure can be further avoided.

[0025] Optionally, the turbine inlet includes two turbine inlet vortices, and the bypass channel includes two inlet openings, each arranged on one of the two turbine inlet vortices. Since the turbine inlet includes two turbine inlet vortices, the efficiency of the turbine device can be improved by utilizing the pulsating exhaust gas flow obtained from all cylinders of the combustion engine in a more efficient manner. In addition, since the bypass channel includes two inlet openings, each arranged on one of the two turbine inlet vortices, it is possible to ensure that the exhaust gases from different cylinders of the combustion engine are mixed before reaching the NOx sensor. In this way, conditions are provided for obtaining even more reliable data of the NOx content of the exhaust gas of the turbine unit flowing through the turbine device. In addition, a space-saving solution is provided, which only requires a short bypass channel layout. In addition, since the temperature and pressure of the exhaust gas in the turbine inlet vortex are lower than the exhaust gas in the more upstream part of the exhaust system, damage to the NOx sensor caused by excessive temperature and / or pressure can be further avoided.

[0026] Optionally, the turbine housing comprises a turbine shroud enclosing at least a part of the turbine unit, and wherein the inlet opening of the bypass channel is arranged on the turbine shroud. Thereby, it can be ensured that the exhaust gases from different cylinders of the combustion engine are mixed before flowing into the bypass channel via the inlet opening. In this way, conditions are provided for obtaining even more reliable data on the NOx content of the exhaust gases of the turbine unit flowing through the turbine arrangement. In addition, a space-saving solution is provided, which only requires a short bypass channel layout. In addition, due to the lower temperature and pressure of the exhaust gases in the turbine shroud compared to the exhaust gases in the more upstream parts of the exhaust system, damage to the NOx sensor caused by excessively high temperatures and / or pressures can be further avoided.

[0027] Optionally, the turbine device comprises a turbine outlet duct configured to receive exhaust gases from a turbine outlet at a first side of the turbine unit, wherein the turbine housing comprises a compartment at a second side of the turbine unit opposite to the first side, and wherein the inlet opening of the bypass channel is fluidly connected to the compartment. Thus, it can be ensured that the exhaust gases from different cylinders of the combustion engine are mixed before flowing into the bypass channel via the inlet opening. In this way, conditions are provided for obtaining even more reliable data on the NOx content of the exhaust gases of the turbine unit flowing through the turbine device. In addition, a space-saving solution is provided, which only requires a short bypass channel layout. In addition, since the temperature and pressure of the compartment at the second side of the turbine are lower than the exhaust gases in the more upstream part of the exhaust system, damage to the NOx sensor caused by excessive temperature and / or pressure can be further avoided.

[0028] Optionally, the inlet opening of the bypass channel is arranged in a delimiting wall of the compartment.Thereby, the inlet opening can be provided in a simple and cost-effective manner.

[0029] Optionally, the bypass channel comprises a flow restriction portion having a smaller effective cross-sectional area than other portions of the bypass channel, and wherein the flow restriction portion is arranged in the bypass channel at a position upstream of the NOx sensor. Thereby, damage to the NOx sensor caused by excessive temperature and / or pressure is further avoided in an effective manner. Furthermore, it can be ensured that the NOx sensor can provide reliable data over the entire operating range of the internal combustion engine including the exhaust system.

[0030] Optionally, the turbine housing comprises a turbine outlet duct configured to receive exhaust gas from the turbine outlet, and wherein the turbine arrangement comprises an exhaust additive dosing unit arranged to supply exhaust additive inside the turbine outlet duct. Since the turbine arrangement comprises a NOx sensor arranged to sense the NOx content of the exhaust gas flowing through the bypass channel, conditions are provided for arranging the exhaust additive dosing unit to supply exhaust additive at a position close to the turbine unit of the turbine arrangement without interfering with the measurement values ​​obtained by the NOx sensor. In this way, a high degree of mixing between the exhaust additive and the exhaust gas upstream of the SCR catalyst can be ensured without interfering with the measurement values ​​obtained by the NOx sensor.

[0031] Optionally, the turbine arrangement comprises a distribution device arranged on the turbine unit, and wherein the exhaust gas additive dosing unit is arranged to supply the exhaust gas additive to the distribution device. Thus, conditions are provided for a high degree of mixing between the exhaust gas additive and the exhaust gas upstream of the SCR catalyst, while at the same time having conditions for obtaining reliable data from the NOx sensor.

[0032] Optionally, the outlet opening of the bypass channel is arranged on the turbine housing. Thus, a space-saving solution is provided, which only requires a short bypass channel layout.

[0033] Optionally, the turbine housing comprises a wastegate chamber which is configured to receive exhaust gases from a wastegate valve, and wherein the outlet opening is arranged in a delimiting wall of the wastegate chamber. Thus, a space-saving solution is provided which utilizes an existing chamber for accommodating the outlet opening. Furthermore, conditions are provided for the arrangement of a short bypass channel.

[0034] Optionally, the exhaust system includes an exhaust throttle valve, which can be controlled to a closed state in which the exhaust throttle valve at least partially blocks exhaust gas from flowing through the exhaust throttle valve, and wherein the outlet opening of the bypass channel is arranged downstream of the exhaust throttle valve. Since the exhaust system includes the exhaust throttle valve, effective engine braking of the combustion engine including the exhaust system can be performed. In addition, since the outlet opening of the bypass channel is arranged downstream of the exhaust throttle valve, when the exhaust throttle valve is controlled to a closed state, the NOx sensor is protected from being damaged by excessive pressure.

[0035] According to a second aspect of the invention, the object is achieved by an internal combustion engine comprising an exhaust system according to some embodiments of the present disclosure. Since the internal combustion engine comprises an exhaust system according to some embodiments, an internal combustion engine is provided that overcomes or at least mitigates some of the above-mentioned problems and disadvantages. Therefore, the above-mentioned object is achieved.

[0036] According to a third aspect of the invention, the object is achieved by a vehicle comprising an internal combustion engine according to some embodiments of the present disclosure. Since the vehicle comprises an internal combustion engine according to some embodiments, a vehicle is provided that overcomes or at least mitigates some of the above-mentioned problems and disadvantages. Therefore, the above-mentioned object is achieved.

[0037] Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Various aspects of the present invention, including its particular features and advantages, will be readily understood from the exemplary embodiments discussed in the following detailed description and accompanying drawings, in which:

[0039] Figure 1 Schematically shows a carrier according to some embodiments of the present disclosure,

[0040] Figure 2 Schematically shows Figure 1 The internal combustion engine of the vehicle shown in FIG.

[0041] Figure 3 Shows Figure 2 A cross section of a turbine device of an exhaust system of an internal combustion engine is shown in

[0042] Figure 4 shows a cross section of a turbine arrangement according to some further embodiments,

[0043] Figure 5 shows a cross section of a turbine arrangement according to some further embodiments, and

[0044] Figure 6 Exhaust systems according to some further embodiments are shown. DETAILED DESCRIPTION

[0045] Aspects of the present invention will now be described more fully. Like reference numerals refer to like elements throughout. For the sake of brevity and / or clarity, well-known functions or constructions need not be described in detail.

[0046] Figure 1 A vehicle 2 according to some embodiments of the present disclosure is schematically shown. According to the illustrated embodiment, the vehicle 2 is a truck, i.e. a heavy vehicle. However, according to other embodiments, as mentioned herein, the vehicle 2 may be another type of manned or unmanned vehicle for land-based or water-based propulsion, such as a truck, a bus, a construction vehicle, a tractor, a car, a ship, a boat, etc.

[0047] The vehicle 2 comprises an internal combustion engine 40. According to the embodiment shown, the internal combustion engine 40 is configured to provide motoring power to the vehicle 2 via wheels 41 of the vehicle 2.

[0048] Figure 2 Schematically shows Figure 1 40 of the vehicle 2 shown in FIG. For the sake of brevity and clarity, the internal combustion engine 40 is referred to as the "combustion engine 40" or simply "engine 40" in some places herein. Figure 1 and Figure 2 .

[0049] In addition to the internal combustion engine 40, the vehicle 2 may also include one or more electric propulsion motors for providing maneuvering power to the vehicle 2. Thus, the vehicle 2 as referred to herein may include a so-called hybrid electric powertrain, which includes one or more electric propulsion motors in addition to the combustion engine 40 for providing maneuvering power to the vehicle 2.

[0050] According to the embodiment herein, the internal combustion engine 40 is a four-stroke internal combustion engine. In addition, according to the illustrated embodiment, the internal combustion engine 40 is a diesel engine, i.e. a compression ignition engine. Therefore, the internal combustion engine 40 can be a compression ignition engine configured to rely on a fuel (such as biodiesel, biomass to liquid (BTL) diesel or gas to liquid (GTL) diesel) of diesel or similar diesel to operate. The fuel (such as biodiesel) of similar diesel can be obtained from renewable resources such as the vegetable oil mainly comprising fatty acid methyl ester (FAME). The fuel of similar diesel can be produced by many types of oil (such as rapeseed oil (rapeseed methyl ester, RME) and soybean oil (soybean methyl ester, SME)).

[0051] According to further embodiments, the internal combustion engine 40 as referred to herein may be an Otto engine with a spark ignition device, wherein the Otto engine may be configured to run on gasoline, alcohol, similar volatile fuels, or a combination thereof. Alcohols (such as ethanol) may come from renewable biomass. According to some embodiments, the internal combustion engine 40 as referred to herein may be arranged to provide power to another device, system or unit other than a vehicle (e.g., a generator, a ship, a boat, etc.).

[0052] The combustion engine 40 comprises an exhaust system 50. The exhaust system 50 is configured to conduct exhaust gases from an exhaust valve of the combustion engine 40 to the surrounding environment. The exhaust system 50 comprises a turbocharger device 30, which comprises a turbine device 1. As further explained herein, the turbine device 1 of the turbocharger device 30 comprises a turbine unit, which is configured to be driven by the exhaust gases of the internal combustion engine 40.

[0053] According to the embodiment shown, the turbocharger device 30 is a turbocharger, i.e. a supercharging device configured to compress air arriving at an air inlet 42 of a combustion engine 40. Thus, according to these embodiments, a turbine unit of the turbocharger device 30 is connected to a compressor. According to further embodiments, the turbocharger device 30 as referred to herein may be a turbocharger compound device, wherein the turbine unit is connected to an output shaft of the combustion engine 40 or to another shaft or another device configured to generate useful energy by rotation of the turbine unit.

[0054] According to the illustrated embodiment, the combustion engine 40 comprises an air filter unit 43 and a charge air cooler 44. The compressor of the turbocharger 30 is configured to force air from the air filter unit 43 to the air inlet 42 of the combustion engine 40. The charge air cooler 44 is arranged between the compressor of the turbocharger 30 and the air inlet 42 of the combustion engine 40. The charge air cooler 44 is configured to cool the compressed air before the air is conducted to the air inlet 42. In this way, the power output and fuel efficiency of the combustion engine 40 can be improved.

[0055] Furthermore, according to the illustrated embodiment, the exhaust system 50 includes a selective catalytic reduction SCR catalyst 45 arranged downstream of the turbine unit of the turbine device 1. Furthermore, the exhaust system 50 includes an exhaust duct 47, which fluidically connects the selective catalytic reduction SCR catalyst 45 to the turbine device 1 of the turbocharger device 30. According to further embodiments, the exhaust system 50 may include another catalytic converter in addition to the selective catalytic reduction SCR catalyst 45.

[0056] Figure 3 Shows Figure 2 4 is a cross section of a turbine device 1 of an exhaust system 50 of a combustion engine 40 shown in FIG. The turbine device 1 comprises a turbine housing 51 and a turbine unit 19 arranged to rotate in the turbine housing 51. The turbine device 1 may also be referred to as a turbine assembly for a turbocharger. The turbine unit 19 is configured to be driven by an internal combustion engine (such as Figure 2 The turbine device 1 may form part of a turbocharger device in the form of a turbocharger or a turbocharger compound device. As will be understood from the above, Figure 2 The turbocharger 30 shown in FIG. 1 may include a turbocharger according to Figure 3 The turbine device 1 of the embodiment shown in FIG. Therefore, unless otherwise indicated below, reference is made to Figure 2 and Figure 3 .

[0057] The turbine unit 19 is configured to rotate about an axis of rotation Ra during operation of a turbocharger device 30 including the turbine device 1. Figure 3 , the cross section is taken in a plane including the rotation axis Ra of the turbine unit 19. The turbine unit 19 includes a turbine 19' and a shaft 19'" connected to the turbine 19'. As mentioned herein, the turbine 19' may also be referred to as a turbine impeller. According to the illustrated embodiment, the turbine 19' and the shaft 19' are formed from one piece of continuous material. According to further embodiments, the turbine 19' and the shaft 19' may be separate parts, wherein the turbine 19' is connected to the shaft 19'.

[0058] In the embodiment in which the turbine device 1 forms part of a turbocharger device 30 in the form of a turbocharger, the shaft 19 ″ of the turbine unit 19 is connected to a compressor, such as reference Figure 2 In the embodiment in which the turbine device 1 forms part of a turbocharger device 30 in the form of a turbocharger compound device, the shaft 19 ″ of the turbine unit 19 can be connected to the output shaft of the combustion engine 40 or to another shaft or another device configured to generate useful energy by rotation of the turbine unit 19.

[0059] The turbine housing 51 includes a turbine inlet scroll 52, 52'. The turbine inlet scroll 52, 52' may also be referred to as a turbine volute. The turbine inlet scroll 52, 52' may be fluidly connected to a plurality of exhaust valves of the combustion engine via an exhaust manifold, such as an exhaust manifold. Figure 2 4. In more detail, according to the embodiment shown, the turbine housing 51 comprises two turbine inlet scrolls 52, 52'. Therefore, the turbine device 1 may also be referred to as a twin-scroll turbine device.

[0060] Each of the two turbine inlet vortices 52, 52' may be fluidly connected to the exhaust valves of a plurality of cylinders of the combustion engine 40 via a separate exhaust manifold. In other words, the first inlet vortex 52 of the two turbine inlet vortices 52, 52' may be fluidly connected to the exhaust valves of a first group of cylinders of the combustion engine 40 via a first exhaust manifold, wherein the second inlet vortex 52' of the two turbine inlet vortices 52, 52' is fluidly connected to the exhaust valves of a second group of cylinders of the combustion engine 40 via a second exhaust manifold, and wherein the second group of cylinders is different from the first group of cylinders. In this way, the pulsating exhaust gas flow obtained from all cylinders of the combustion engine 40 may be utilized in a more efficient manner to improve the efficiency of the turbine device 1.

[0061] As defined herein, the turbine housing 51 includes a turbine inlet 24, which includes two turbine inlet scrolls 52, 52' and a portion 24' of the turbine housing 51 upstream of the two turbine inlet scrolls 52, 52'. However, as mentioned herein, the turbine inlet 24 may also include one turbine inlet scroll and a portion 24' of the turbine housing 51 upstream of the turbine inlet scroll. The portion 24' of the turbine housing 51 upstream of the two turbine inlet scrolls 52, 52' is Figure 2 Instructions. Figure 2 As indicated in , the turbine housing 51 is connected to the exhaust manifold 46 of the combustion engine 40 via the portion 24 ′ of the turbine housing 51 . The exhaust manifold 46 fluidly connects the turbine housing 51 to a plurality of cylinders of the combustion engine 40 .

[0062] The turbine housing 51 further comprises a turbine shroud 53 and a turbine outlet duct 3. The turbine shroud 53 encloses at least a portion of the turbine 19' of the turbine unit 19. The turbine outlet duct 3 is arranged downstream of the turbine 19' of the turbine unit 19 and is configured to receive exhaust gas from the turbine 19' of the turbine unit 19. In more detail, the turbine unit 19 comprises a turbine outlet 29 facing the turbine outlet duct 3, wherein the turbine outlet duct 3 is configured to receive exhaust gas from the turbine outlet 29. As defined herein, the turbine outlet 29 is positioned at the interface between the turbine shroud 53 and the turbine outlet duct 3.

[0063] Furthermore, the turbine outlet duct 3 comprises a first end portion 15 and a second end portion 17, wherein the first end portion 15 is arranged at the interface between the turbine shroud 53 and the turbine outlet duct 3. According to the illustrated embodiment, the turbine outlet duct 3 has a frustoconical inner surface formed by its wall 5. According to further embodiments, the inner surface of the turbine outlet duct 3 may have another shape different from a frustoconical shape. The effective cross-sectional area of ​​the turbine outlet duct 3 measured in a plane perpendicular to the central axis Ca of the turbine outlet duct 3 increases along the intended flow direction d1 through the turbine outlet duct 3. The intended flow direction d1 through the turbine outlet duct 3 coincides with a direction pointing from the first end portion 15 of the turbine outlet duct 3 to the second end portion 17 of the turbine outlet duct 3.

[0064] Thus, according to the illustrated embodiment, the turbine outlet duct 3 acts as a diffuser, which reduces the flow velocity and increases the static pressure inside the turbine outlet duct 3 along the intended flow direction d1. Therefore, the turbine outlet duct 3 as referred to herein may also be referred to as diffuser duct, diffuser or the like.

[0065] During operation of the turbine arrangement 1, exhaust gases flow from the cylinders of the combustion engine 40 through the exhaust manifold 46, via the portion 24' of the turbine housing into the turbine housing 51, and via two turbine inlet scrolls 52, 52' into the turbine 19' of the turbine unit 19, through the turbine shroud 53, and via the turbine outlet 29 into the turbine outlet duct 3. As mentioned, the exhaust system 50 comprises an exhaust duct 47 connected to the turbine outlet duct 3. The exhaust duct 47 is Figure 2 and Figure 3 As will be appreciated from the above, the flow of exhaust gases through the turbine 19' causes the turbine unit 19 to rotate about the axis of rotation Ra.

[0066] According to the embodiment shown, the turbine outlet duct 3 forms part of the turbine housing 51, but may also be a separate part attached to the turbine housing 51. However, since according to the embodiment shown, the turbine outlet duct 3 forms part of the turbine housing 51, the turbine outlet duct 3 as mentioned herein may also be referred to as the turbine housing or part of the turbine housing downstream of the turbine outlet 29 of the turbine unit 19 of the turbine device 1.

[0067] Furthermore, as understood from the above, the turbine shroud 53 and the turbine outlet duct 3 may be collectively referred to as the exhaust gas conducting section 31 of the turbine device 1. According to the illustrated embodiment, the turbine shroud 53 and the turbine outlet duct 3 are formed from one continuous piece of material. According to further embodiments, the turbine shroud 53 and the turbine outlet duct 3 may each be formed from separate pieces of material and may be assembled to each other to form the exhaust gas conducting section 31.

[0068] According to the embodiment herein, the exhaust system 50 comprises a bypass passage 11 having an inlet opening 12, 12' arranged upstream of a turbine outlet 29 of a turbine unit 19 and an outlet opening 22 arranged downstream of the turbine outlet 29. Furthermore, the exhaust system 50 comprises a NOx sensor 9 arranged to sense the NOx content of the exhaust gas flowing through the bypass passage 11.

[0069] Thus, conditions are provided for obtaining reliable data on the NOx content of the exhaust gases flowing through the turbine unit 19 of the turbine device 1, while avoiding damage to the NOx sensor 9 caused by excessive temperatures and / or pressures. Furthermore, as further explained herein, due to these features, conditions are provided for injecting the exhaust additive 20 into the exhaust gases inside the exhaust system 50 at a location close to the turbine unit 19' of the turbine device 1 without interfering with the measurements obtained by the NOx sensor 9.

[0070] According to further embodiments, in addition to the NOx sensor 9, the exhaust system 50 may further include another sensor configured to sense another property of the gas flowing through the bypass passage 11 other than the NOx content, such as a temperature sensor configured to sense the temperature of the gas flowing through the bypass passage 11 or an oxygen sensor configured to sense the oxygen content of the gas flowing through the bypass passage 11.

[0071] The turbine arrangement 1 according to the illustrated embodiment comprises an exhaust additive dosing unit 6 which is arranged to supply exhaust additive 20 inside the turbine outlet duct 3. In these embodiments, the exhaust additive dosing unit 6 is arranged to supply exhaust additive 20 closer to the first end portion 15 than to the second end portion 17.

[0072] In more detail, according to the illustrated embodiment, the turbine device 1 comprises an exhaust additive dosing device 10, which comprises an exhaust additive dosing unit 6. The exhaust additive dosing device 10 comprises an exhaust additive storage unit 34 configured to contain an exhaust additive 20, such as an aqueous urea solution, and a pump 32 configured to pump the exhaust additive 20 from the exhaust additive storage unit 34 to the exhaust additive dosing unit 6.

[0073] The exhaust additive dosing unit 6 is formed as a supply pipe protruding into the turbine outlet duct 3. The exhaust additive dosing unit 6 comprises an opening 8 for supplying the exhaust additive 20 to the exhaust gas flow inside the turbine outlet duct 3. According to the illustrated embodiment, the exhaust additive dosing unit 6 is arranged such that the center axis Ca of the turbine outlet duct 3 extends through the opening 8 of the exhaust additive dosing unit 6.

[0074] Furthermore, the exhaust gas additive dosing device 10 may include some further components 36 between the pump 32 and the exhaust gas additive dosing unit 6. Figure 3 In the drawings, such additional components 36 are indicated by reference numeral 36 and may include additional piping, dosing valves, etc.

[0075] The exhaust additive dosing device 10 according to the illustrated embodiment is an airless exhaust additive dosing device 10, meaning that the exhaust additive 20 is supplied to the exhaust gas without using pressurized air, as is required with some other types of exhaust additive dosing devices. However, according to further embodiments, the exhaust additive dosing device 10 of the turbine device 1 may utilize pressurized air for supplying the exhaust additive to the exhaust gas flow inside the turbine outlet duct 3.

[0076] According to the illustrated embodiment, the turbine device 1 comprises a distribution device 23 arranged on the turbine unit 19, and wherein the exhaust gas additive dosing unit 6 is arranged to supply the exhaust gas additive 20 onto the distribution device 23. The distribution device 23 is arranged at the center of the turbine unit 19, which means that the rotation axis Ra of the turbine unit 19 extends through the distribution device 23.

[0077] As from Figure 3 It is clearly shown that, according to the embodiment shown, the axis of rotation Ra of the turbine unit 19 coincides with the central axis Ca of the turbine outlet duct 3. According to the embodiment shown, the distribution device 23 forms part of the turbine 19' of the turbine unit 19, i.e. the distribution device 23 and the turbine 19' are formed from one piece of continuous material. According to further embodiments, the distribution device 23 may be a separate part attached to the turbine unit 19, for example by welding and / or by one or more fastening elements.

[0078] According to the illustrated embodiment, the dispensing device 23 is cup-shaped, and the exhaust additive dosing unit 6 protrudes into the open face of the cup-shaped dispensing device 23, so that the opening 8 of the exhaust additive dosing unit 6 is located inside the cup-shaped dispensing device 23. Since the dispensing device 23 rotates together with the turbine unit 19 at a high rotation speed, an effective dispensing and atomization of the exhaust additive 20 is provided. In addition, the cup shape of the dispensing device 23 prevents backflow from the edge of the cup-shaped dispensing device 23 and reduces the risk of inadvertent deposition of the exhaust additive 20 on the surface of the turbine 19'.

[0079] According to further embodiments, the dispensing device 23 may have another shape. As an example, according to some embodiments, the dispensing device 23 may include a receiving surface forming a patterned facial surface. This patterned surface may be used to control and optimize the distribution of the exhaust additive in the exhaust flow. As an alternative or in addition, the exhaust additive dispensing device 23 may include a radial wall, wherein the receiving surface of the exhaust additive dispensing device 23 is the inner face of the radial wall, wherein the exhaust additive dispensing device 23 includes a dispensing surface of an orifice formed in the radial wall, and wherein the orifice extends between the inner face of the radial wall and the outer surface of the radial wall.

[0080] Furthermore, according to further embodiments, the exhaust additive dosing unit 6 may be configured to supply the exhaust additive to the exhaust gas flow inside the turbine outlet duct 3 in another way than supplying it onto the distribution device 23. Figure 3 In the embodiment shown in FIG. 1 , the exhaust additive dosing unit 6 is arranged to supply the exhaust additive 20 to the exhaust gas flow inside the turbine outlet duct 3 at a position located adjacent to the first end portion 15 of the turbine outlet duct 3. In this way, it can be ensured that the exhaust additive 20 and the exhaust gas are mixed to a large extent before the mixture reaches the selective catalytic reduction SCR catalyst 45 of the combustion engine 40.

[0081] according to Figure 3 In the embodiment shown in FIG. 1 , the inlet openings 12 and 12 ′ of the bypass channel 11 are arranged on the turbine housing 51 , that is, arranged on the turbine inlet 24 of the turbine housing 51 . That is, in more detail, according to Figure 3 In the embodiment shown in the figure, the inlet openings 12, 12' of the bypass passage 11 are arranged on the turbine inlet scrolls 52, 52'. As mentioned, according to the embodiment shown, the turbine inlet 24 includes two turbine inlet scrolls 52, 52', and according to the embodiment shown, the bypass passage 11 includes two inlet openings 12, 12', each of which is arranged on one of the two turbine inlet scrolls 52, 52'.

[0082] The bypass channel 11 comprises a junction 11 ', which fluidically connects the two inlet openings 12, 12'. Obviously, according to the embodiment shown, the bypass channel 11 comprises a respective bypass path between the junction 11 ' and the respective inlet opening 12, 12'. The junction 11 ' is arranged upstream of the NOx sensor 9 as seen along the intended flow direction through the bypass channel 11. The intended flow direction through the bypass channel 11 extends from the inlet opening / openings 12, 12' towards the outlet opening 22 of the bypass channel 11.

[0083] According to the illustrated embodiment, the outlet opening 22 of the bypass channel 11 is arranged on the turbine housing 51. In more detail, according to the illustrated embodiment, the turbine housing 51 includes a wastegate chamber 7. The wastegate chamber 7 is configured to receive exhaust gas from a wastegate valve of a turbocharger device 30 including the turbine device 1. Figure 3 As can be seen in FIG. 1 , according to the illustrated embodiment, the outlet opening 22 is provided in the delimiting wall 7 ′ of the wastegate chamber 7 . However, according to further embodiments, the outlet opening 22 may be arranged at a different part of the exhaust system 50 downstream of the turbine outlet 29 of the turbine unit 19 .

[0084] Furthermore, according to the illustrated embodiment, the bypass channel 11 includes a flow restriction portion 57. The flow restriction portion 57 has a smaller effective cross-sectional area than other portions of the bypass channel 11. The flow restriction portion 57 is arranged at a position upstream of the NOx sensor 9 in the bypass channel 11 as seen with respect to the expected flow direction through the bypass channel 11. Due to the flow restriction portion 57, damage to the NOx sensor 9 caused by excessively high temperatures and / or pressures is further avoided in an effective manner. Furthermore, it can be ensured that the NOx sensor 9 can provide reliable data over the entire operating range of the internal combustion engine 40 including the exhaust system 50.

[0085] Figure 4 A cross section of a turbine device 1 according to some further embodiments is shown. Figure 2 The exhaust system 50 of the internal combustion engine 40 shown in FIG. 4 may include a Figure 4 The turbine device 1 of the embodiment shown in FIG. Therefore, unless otherwise indicated below, reference is made to Figure 2 and Figure 4 . Figure 4 The turbine device 1 shown in FIG. 1 comprises a Figure 3 The invention also has the same features, functions and advantages as the turbine device 1 shown in FIG. 1 , with some exceptions explained below.

[0086] Also in Figure 4 In the embodiment shown in FIG. 1 , the inlet opening 14 of the bypass channel 11 is arranged on the turbine inlet 24 of the turbine housing 51 . Figure 4In the embodiment shown in FIG. 5 , the inlet opening 14 of the bypass channel 11 is arranged on a turbine shroud 53. As mentioned, the turbine shroud 53 encloses at least a portion of the turbine 19' of the turbine unit 19.

[0087] Since the inlet opening 14 of the bypass channel 11 is arranged on the turbine shroud 53, it can be ensured that the exhaust gases from different cylinders of the combustion engine 40 are mixed before flowing into the bypass channel 11 via the inlet opening 14. In this way, conditions are provided for obtaining even more reliable data of the NOx content of the exhaust gases flowing through the turbine unit 19 of the turbine device 1. In addition, a space-saving solution is provided, which only requires a short bypass channel 11 layout. In addition, since the temperature and pressure of the exhaust gases in the turbine shroud 53 are lower than those in the more upstream parts of the exhaust system 50, damage to the NOx sensor 9 caused by excessively high temperatures and / or pressures can be further avoided.

[0088] Figure 5 A cross section of a turbine device 1 according to some further embodiments is shown. Figure 2 The exhaust system 50 of the internal combustion engine 40 shown in FIG. 4 may include a Figure 5 The turbine device 1 of the embodiment shown in FIG. Therefore, unless otherwise indicated below, reference is made to Figure 2 and Figure 5 . Figure 5 The turbine device 1 shown in FIG. 1 comprises a Figure 3 The invention also has the same features, functions and advantages as the turbine device 1 shown in FIG. 1 , with some exceptions explained below.

[0089] like Figure 5 As indicated in FIG. 1 , the turbine outlet duct 3 is configured to receive exhaust gas from the turbine outlet 29 at a first side S1 of the turbine 19' of the turbine unit 19. Furthermore, the turbine housing 51 comprises a compartment 55 at a second side S2 of the turbine 19' of the turbine unit 19. The second side S2 of the turbine 19' of the turbine unit 19 is opposite to the first side S1 of the turbine 19' of the turbine unit 19. Figure 5 In the embodiment shown in , the inlet opening 16 of the bypass channel 11 is fluidly connected to the compartment 55 at the second side S2 of the turbine 19 ′ of the turbine unit 19 .

[0090] In more detail, according to Figure 5 In the embodiment shown in the figure, the inlet opening 16 of the bypass channel 11 is arranged in a delimiting wall 55' of a compartment 55. According to the embodiment shown, the delimiting wall 55' of the compartment 55 is a wall of the turbine housing 51. The compartment 55 is delimited by the delimiting wall 55', the rear side of the turbine 19' of the turbine unit 19, the shaft 19" of the turbine unit 19 and a sealing assembly 59. The sealing assembly 59 may include one or more seals, heat shields, etc.

[0091] Since the inlet opening 16 of the bypass channel 11 is fluidly connected to the compartment 55 at the second side S2 of the turbine 19' of the turbine unit 19, it can be ensured that the exhaust gases from different cylinders of the combustion engine 40 are mixed before flowing into the bypass channel 11 via the inlet opening 16. In this way, conditions are provided for obtaining even more reliable data of the NOx content of the exhaust gases flowing through the turbine unit 19 of the turbine device 1. In addition, a space-saving solution is provided, which only requires a short bypass channel 11 layout. In addition, since the temperature and pressure of the compartment 55 at the second side S2 of the turbine 19' are lower than the exhaust gases in the more upstream part of the exhaust system 50, damage to the NOx sensor 9 caused by excessively high temperatures and / or pressures can be further avoided.

[0092] exist Figure 4 and Figure 5 In the embodiment shown in , the outlet opening 22 of the bypass channel 11 is provided in the delimiting wall 7 ′ of the wastegate chamber 7 . However, also in these embodiments, the outlet opening 22 may be arranged at a different part of the exhaust system 50 downstream of the turbine outlet 29 of the turbine unit 19 .

[0093] Figure 6 An exhaust system 50 is shown according to some further embodiments. Figure 6 The exhaust system 50 shown in FIG. 5 may include the same Figure 2-Figure 5 The exhaust system 50 described above has the same features, functions and advantages as described above, with some exceptions explained below. Figure 6 Also shown is the internal combustion engine 40 including an exhaust system 50 . Figure 1 The carrier 2 shown in FIG. 1 may include a Figure 6 The internal combustion engine 40 of the embodiment shown in FIG.

[0094] according to Figure 6 , the exhaust system 50 includes an exhaust throttle valve 57. The exhaust throttle valve 57 can be controlled to a closed state in which the exhaust throttle valve 57 at least partially blocks the exhaust gas from flowing through the exhaust throttle valve 57. Therefore, the closed state as mentioned herein may also be referred to as an "at least partially closed state", or simply as a "state in which the exhaust throttle valve 57 at least partially blocks the exhaust gas from flowing through the exhaust throttle valve 57". Due to the exhaust throttle valve 57, the combustion engine 40 can be braked in an effective manner by providing an opposing force on the piston of the combustion engine 40 during its exhaust stroke.

[0095] exist Figure 6 , a bypass passage 11 of an exhaust system 50 is schematically indicated. The bypass passage 11 may include an inlet opening having a shape similar to that of reference Figure 3-Figure 5The position of the inlet opening(s) 12, 12', 14, 16 in any of the explained embodiments corresponds to the position. Figure 6 As can be seen in FIG. 1 , in these embodiments, the outlet opening 22' of the bypass passage 11 is arranged downstream of the exhaust throttle valve 57. Thus, when the exhaust throttle valve 57 is controlled to a closed state, the NOx sensor 9 is protected from being damaged by excessive pressure.

[0096] As used herein, the term "adjacent to" may encompass referent objects being within 1-2 centimeters of each other.

[0097] As used herein, the terms upstream and downstream refer to the relative position of an object relative to the intended flow direction of a fluid in the referenced system. As an example, the feature that a first object is arranged upstream of a second object in a system means that the first object is arranged before the second object as seen in the intended flow direction of the fluid through the system. As another example, the feature that a first object is arranged downstream of a second object in a system means that the first object is arranged after the second object as seen in the intended flow direction of the fluid through the system.

[0098] Thus, the feature that the bypass passage 11 comprises inlet openings 12, 12', 14, 16 arranged upstream of the turbine outlet 29 of the turbine unit 19 means that the inlet openings 12, 12', 14, 16 are arranged in the exhaust system 50 at a position upstream of the turbine outlet 29 of the turbine unit 19 as seen with respect to the intended flow direction of the exhaust gases through the exhaust system 50. Likewise, the feature that the bypass passage 11 comprises outlet openings 22, 22' arranged downstream of the turbine outlet 29 means that the outlet openings 22, 22' are arranged downstream of the turbine outlet 29 as seen with respect to the intended flow direction of the exhaust gases through the exhaust system 50.

[0099] It should be understood that the above is an illustration of various exemplary embodiments, and the present invention is limited only by the appended independent claims. Those skilled in the art will recognize that the exemplary embodiments may be modified without departing from the scope of the present invention as defined by the appended independent claims, and that different features of the exemplary embodiments may be combined to produce embodiments other than those described herein.

[0100] As used herein, the terms “comprising” and “comprises” are open ended and include one or more stated features, elements, steps, components or functions, but do not preclude the presence or addition of one or more other features, elements, steps, components, functions or groups thereof.

Claims

1. An exhaust system (50) for an internal combustion engine (40), The exhaust system (50) comprises a turbine device (1) for a turbocharger (30), The turbine device (1) comprises a turbine housing (51) and a turbine unit (19) arranged to rotate in the turbine housing (51). and wherein the exhaust system (50) comprises a bypass channel (11) having an inlet opening (12, 12', 14, 16) arranged upstream of a turbine outlet (29) of the turbine unit (19) and an outlet opening (22, 22') arranged downstream of the turbine outlet (29), And wherein the exhaust system (50) includes a NOx sensor (9) configured to sense the NOx content of the exhaust gas flowing through the bypass passage (11).

2. The exhaust system (50) according to claim 1, wherein the inlet opening (12, 12', 14, 16) of the bypass channel (11) is arranged on the turbine housing (51).

3. An exhaust system (50) according to claim 1 or 2, wherein the turbine housing (51) comprises a turbine inlet (24), and wherein the inlet opening (12, 12') of the bypass channel (11) is arranged at the turbine inlet (24) of the turbine housing (51).

4. The exhaust system (50) according to claim 3, wherein the turbine inlet (24) comprises a turbine inlet scroll (52, 52'), and wherein the inlet opening (12, 12') of the bypass channel (11) is arranged on the turbine inlet scroll (52, 52').

5. An exhaust system (50) according to claim 3, wherein the turbine inlet (24) includes two turbine inlet vortices (52, 52'), and wherein the bypass passage (11) includes two inlet openings (12, 12') each arranged on one of the two turbine inlet vortices (52, 52').

6. An exhaust system (50) according to claim 1 or 2, wherein the turbine housing (51) comprises a turbine shroud (53) enclosing at least a part of the turbine unit (19), and wherein the inlet opening (14) of the bypass channel (11) is arranged on the turbine shroud (53).

7. An exhaust system (50) according to claim 1 or 2, wherein the turbine device (1) comprises a turbine outlet duct (3), which is configured to receive exhaust gas from the turbine outlet (29) at a first side (S1) of the turbine unit (19), wherein the turbine housing (51) comprises a compartment (55) at a second side (S2) of the turbine unit (19) opposite to the first side (S1), and wherein the inlet opening (16) of the bypass channel (11) is fluidically connected to the compartment (55).

8. An exhaust system (50) according to any one of the preceding claims, wherein the bypass passage (11) includes a flow restriction portion (57), the flow restriction portion having a smaller effective cross-sectional area than other portions of the bypass passage (11), and wherein the flow restriction portion (57) is arranged in the bypass passage (11) at a position upstream of the NOx sensor (9).

9. An exhaust system (50) according to any one of the preceding claims, wherein the turbine housing (51) comprises a turbine outlet duct (3), which is configured to receive exhaust gases from the turbine outlet (29), and wherein the turbine device (1) comprises an exhaust additive dosing unit (6), which is arranged to supply exhaust additive (20) inside the turbine outlet duct (3).

10. The exhaust system (50) according to claim 9, wherein the turbine device (1) comprises a distribution device (23) arranged on the turbine unit (19), and wherein the exhaust gas additive dosing unit (6) is arranged to supply the exhaust gas additive (20) to the distribution device (23).

11. The exhaust system (50) according to any one of the preceding claims, wherein the outlet opening (22) of the bypass channel (11) is arranged on the turbine housing (51).

12. An exhaust system (50) according to any one of the preceding claims, wherein the turbine housing (51) comprises a wastegate chamber (7) configured to receive exhaust gases from a wastegate valve, and wherein the outlet opening (22) is arranged in a delimiting wall (7') of the wastegate chamber (7).

13. An exhaust system (50) according to any one of the preceding claims, wherein the exhaust system (50) comprises an exhaust throttle valve (57), which can be controlled to a closed state, in which the exhaust throttle valve (57) at least partially prevents exhaust gas from flowing through the exhaust throttle valve (57), and wherein the outlet opening (22') of the bypass channel (11) is arranged downstream of the exhaust throttle valve (57).

14. An internal combustion engine (40) comprising an exhaust system (50) according to any one of the preceding claims.

15. A vehicle (2) comprising an internal combustion engine (40) according to claim 14.

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