GB2629422A

GB2629422A - Exhaust system including a heating system for raising a temperature of an exhaust gas aftertreatment device

Info

Publication number: GB2629422A
Application number: GB2306285.4A
Authority: GB
Inventors: Dale Martin
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2023-04-28
Filing date: 2023-04-28
Publication date: 2024-10-30
Also published as: GB202306285D0

Abstract

An exhaust system (100, Fig.2) for a vehicle (1, Fig.1), and an associated method (600, Fig. 6) and computer software (408, Fig. 4); The exhaust system (100, Fig. 2) comprises a turbomachine assembly 120 and a component (202, 204, Fig. 2) of a heating system (200, Fig. 2) for raising a temperature of an exhaust gas aftertreatment device (152, Fig. 2); The turbomachine assembly 120 comprises a turbomachine housing 126 with: an inlet section 126A having an exhaust gas inlet port (130, Fig. 2), a turbine volute 126B, and an outlet section 126C extending from the turbine volute 126B and having an exhaust gas discharge port 135; The outlet section 126C of the turbomachine housing 126 further comprises an opening 132, 134 wherein the component (202, 204, Fig. 2) of the heating system (200, Fig. 2) is received in the opening 132, 134. The invention aims to speed up the heating process of an exhaust gas aftertreatment device.

Description

EXHAUST SYSTEM INCLUDING A HEATING SYSTEM FOR RAISING A TEMPERATURE OF AN EXHAUST GAS AFTERTREATMENT DEVICE

TECHNICAL FIELD

The present disclosure relates to an exhaust system including a heating system for raising a temperature of an exhaust gas aftertreatment device. In particular, but not exclusively it relates to an exhaust system for a vehicle, a system, a vehicle, a method, and computer software.

BACKGROUND

Many vehicles equipped with internal combustion engines (engines' herein) also comprise exhaust gas aftertreatment devices, such as three way catalysts (TWCs), to treat exhaust gases from the engines. The exhaust gas aftertreatment device needs to reach an operating temperature (light-off temperature) at which it is effective to clean exhaust gases. The operating temperature may be in the order of hundreds of degrees Celsius.

Therefore, vehicle pollutant emissions are generally highest at the start of a vehicle drive cycle due to the engine running while the temperature of the exhaust gas aftertreatment device is low. To speed up catalyst heating, the engine may be run in a mode that generates higher exhaust gas temperatures, or a heating system can be provided such as a burner system upstream of the exhaust gas aftertreatment device, or an electric heater to heat the exhaust gas aftertreatment device.

The electric heater is activated when the engine is running, to heat exhaust gases flowing through the electric heater. The burner system is a separate module with its own air pump, to inject heated/combusted air towards the exhaust gas aftertreatment device.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided an exhaust system for a vehicle, the exhaust system comprising a turbomachine assembly, and a component of a heating system, wherein the heating system is for raising a temperature of an exhaust gas aftertreatment device, wherein the turbomachine assembly comprises a turbomachine housing, wherein the turbomachine housing comprises: an inlet section having an exhaust gas inlet port; a turbine volute; and an outlet section extending from the turbine volute and having an exhaust gas discharge port; wherein the outlet section of the turbomachine housing further comprises an opening, wherein the component of the heating system is received in the opening.

By integrating the component of the heating system with the turbine housing, an advantage is that air can be heated far upstream of the exhaust gas aftertreatment device, resulting in evenly spatially distributed heating of the surface of the exhaust gas aftertreatment device. Additionally, the component is immediately downstream of the turbine wheel which means that heated gases have additional swirl and turbulence to improve fuel-air mixing.

The opening may extend through a wall of the outlet section of the turbomachine housing at a location upstream of the exhaust gas discharge port. The exhaust system may further comprise a mounting portion, to which the component, is secured, wherein the opening and the mounting portion are arranged to position the component to extend through the opening to expose the component to an interior space of the outlet section.

An advantage of exposing the component of the heating system to the interior space of the outlet section is that air already in the turbomachine housing can support combustion. Therefore, combustion-supporting air can be supplied by rotating a crankshaft of the internal combustion engine without requiring a separate air pump.

The opening may be an injector opening, and the component may be a fuel injector. The exhaust system may further comprise an igniter of the heating system, wherein the turbomachine housing is further configured to receive the igniter of the heating system, and expose the igniter to the interior space of the outlet section to enable the igniter to initiate combustion of fuel injected by the fuel injector. An advantage is that the ignition is initiated very far upstream of the exhaust gas aftertreatment device.

The outlet section of the turbomachine housing may comprise a second opening exposing the igniter of the heating system to the interior space of the outlet section, wherein the second opening is proximal to the injector opening. The exhaust system may comprise an igniter mounting portion to which the igniter is secured, wherein the second opening and the igniter mounting portion are arranged to position the igniter to extend through the second opening and expose the igniter to the interior space of the outlet section.

The second opening for the igniter may be downstream of the injector opening, closer to the exhaust gas discharge port than the injector opening.

The turbomachine housing may be a single cast part including the turbine volute and the outlet section, and optionally the inlet section.

The turbomachine assembly may be a turbocharger assembly.

The exhaust system may further comprise the heating system.

While air is mentioned herein to support combustion of fuel supplied by the heating system, the air may be a more generalised gas, which gas may comprise exhaust gas from the internal combustion engine on which the turbomachine is fitted. At least, it is exhaust gas once the engine has been running for a period of time. There must be unused oxygen and other atmospheric air components in the exhaust gas to support combustion of fuel in the outlet section of the turbomachine when injected by the heating system.

According to another aspect of the invention, there is provided a system comprising the exhaust system, and comprising a control system configured to output a control signal to cause a torque source connected to an internal combustion engine to rotate the internal combustion engine to provide combustion-supporting air for the heating system. In this event, the gas in the turbomachine will indeed be air.

According to a further aspect of the invention, there is provided a system for raising a temperature of an exhaust gas aftertreatment device of an exhaust system of a vehicle, the system comprising: an exhaust assembly defining a path for exhaust gas to travel from an internal combustion engine to the exhaust gas aftertreatment device, wherein the internal combustion engine defines a torque source of the vehicle; means for providing combustion-supporting air into the path of the exhaust assembly; and a heating system comprising a fuel injector, and an igniter for igniting a mixture of fuel injected by the fuel injector and the combustion-supporting air, wherein the fuel injector and the igniter each extend into the path of the exhaust assembly to expose the fuel injector and the igniter to the combustion-supporting air.

An advantage of exposing the component of the heating system to the path of the exhaust assembly is that air already in the path can be ignited. Therefore, combustion-supporting air can be supplied by rotating a crankshaft of the internal combustion engine without requiring a separate air pump.

The means may comprise the internal combustion engine in combination with a torque source operable to rotate the internal combustion engine to pump the combustion-supporting air.

According to a further aspect of the invention, there is provided a system comprising a component of a heating system and a wastegate assembly for an exhaust system of a vehicle, wherein the wastegate assembly comprises a wastegate housing and a wastegate duct, wherein the wastegate assembly comprises an opening to receive a component of the heating system, and wherein the heating system is for raising a temperature of an exhaust gas aftertreatment device of the exhaust system.

An advantage is that air can be heated very far upstream of the exhaust gas aftertreatment device.

According to a further aspect of the invention, there is provided a vehicle comprising the turbomachine assembly or the exhaust system or the system.

According to a further aspect of the invention, there is provided a method of raising a temperature of exhaust gas in a turbomachine assembly for an exhaust system of a vehicle, the method comprising: injecting fuel into an outlet section of a turbomachine housing of the turbomachine assembly; and igniting the fuel in the turbomachine housing upstream of an exhaust gas aftertreatment device.

The method may further comprise causing a torque source connected to an internal combustion engine to rotate the internal combustion engine to provide combustion-supporting air for igniting the fuel.

According to a further aspect of the invention, there is provided a control system for raising a temperature of exhaust gas in a turbomachine assembly for an exhaust system of a vehicle, the control system comprising one or more controllers, the control system configured to: receive an input signal indicative of a requirement to raise a temperature of the exhaust gas aftertreatment device; determine the requirement; and output one or more control signals to inject fuel into an outlet section of a turbomachine housing of the turbomachine assembly, and ignite the fuel in the turbomachine housing upstream of exhaust gas aftertreatment device.

The one or more controllers may collectively comprise: at least one electronic processor having an electrical input for receiving the input signal; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to determine the requirement and output the one or more control signals.

According to a further aspect of the invention, there is provided computer software that, when executed, is arranged to perform any one or more of the methods described herein. According to a further aspect of the invention there is provided a non-transitory computer readable medium comprising computer readable instructions that, when executed by one or more electronic processors, causes the one or more electronic processors to carry out any one or more of the methods described herein.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination that falls within the scope of the appended claims. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination that falls within the scope of the appended claims, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 illustrates an example of a vehicle; FIG. 2 illustrates an example of an internal combustion engine and a portion of an exhaust system; FIG. 3 illustrates an example of a turbine housing; FIG. 4 illustrates an example of a control system; FIG. 5 illustrates an example of a non-transitory computer-readable storage medium; and FIG. 6 illustrates an example of a method.

DETAILED DESCRIPTION

FIG. 1 illustrates an example of a vehicle 1 in which embodiments of the invention can be implemented. In some, but not necessarily all examples, the vehicle 1 is a passenger vehicle, also referred to as a passenger car or as an automobile. In other examples, embodiments of the invention can be implemented for other applications, such as commercial vehicles.

FIG. 2 schematically illustrates an internal combustion engine 10 ('engine' herein) and a portion of an exhaust system 100. The exhaust system 100 comprises at least a turbomachine assembly 120, an exhaust gas aftertreatment device 152, and one or more exhaust pipes 160.

The illustrated engine 10 is a reciprocating piston engine having a number of combustion chambers 12. In other examples, the engine 10 is any other appropriate type of internal combustion engine.

If the engine 10 comprises multiple combustion chambers 12, an exhaust manifold 110 is provided as shown in FIG. 2. The exhaust manifold 110 may be an external manifold or an integrated manifold, for example. An integrated manifold is part of the casting of the engine 10. An external manifold is a separate part than the engine 10, connected to an exterior of the engine 10.

The exhaust manifold 110 is connected to a turbomachine assembly 120 of the exhaust system 100, downstream of the exhaust manifold 110. The connection may be direct, as shown, or indirect.

The turbomachine assembly 120 can comprise a turbine wheel 127 and a compressor wheel 122 together defining a turbocharger, wherein the turbine wheel 127 drives the compressor wheel 122 as is understood. This is shown in the Figures. Alternatively, the turbomachine assembly 120 can comprise a turbine wheel 127 and a mechanical connection to a crankshaft of the engine 10 to define a turbocompounder, wherein the turbine wheel 127 transfers energy to the crankshaft as is understood.

The turbomachine assembly 120 of FIG. 2, defining a turbocharger, comprises two turbomachine housings: a turbine housing 126 and a compressor housing 121. The turbine housing 126 comprises a turbine inlet section 126A, a turbine volute 126B, and a turbine outlet section 126C. The compressor housing 121 comprises a compressor inlet section 121A, a compressor volute 121B, and a compressor outlet section 121C.

The turbine housing 126 and compressor housing 121 are mechanically connected to each other by a shaft 125 coupling the turbine wheel 127 to the compressor wheel 122.

FIG. 3 is a detail view of an example turbine housing 126. In the specific example of FIG. 3, the turbine housing 126 is a multi-volute turbine housing such as a dual-volute turbine housing.

However, the turbine housing 126 can alternatively be a single volute turbine housing.

The turbine inlet section 126A comprises one or more elongate hollow tubes 126A1, 126A2 each providing an exhaust gas channel from the exhaust manifold 110 to the corresponding turbine volute(s) 126B. The turbine inlet section 126A is generally referred to as a 'foot' of the turbine housing 126.

The distal end of the turbine inlet section 126A comprises one or more exhaust gas inlet ports 130. The distal end of the turbine inlet section 126A can further comprise a flange structure 129A, 129B to align the or each exhaust gas inlet port 130 with a corresponding outlet of the exhaust manifold 110. The flange structure 129A, 129B may define a flange connector.

A turbine volute 126B is a spiral-shaped form, also referred to as a scroll-shaped form. The exhaust gas channel extends through the turbine volute 126B. A turbine volute 126B is configured as a funnel to decrease the cross-sectional area of the exhaust gas channel in a downstream direction. The turbine volute 126B is arranged around the turbine wheel 127 and is arranged to direct exhaust gas through the turbine wheel 127.

If the turbine housing 126 is a multi-volute turbine housing, multiple turbine volutes 126B1, 126B2 may be provided. Each turbine volute 126B1, 126B2 is for a corresponding one of the exhaust gas channels. The turbine volutes 126B1, 126B2 merge meaning that their respective exhaust gas channels merge.

The turbine outlet section 126C of the turbine housing 126 extends from the turbine volute 126B and has an exhaust gas discharge port 139. The turbine outlet section 126C comprises a hollow tube 136 providing an exhaust gas path from the turbine wheel 127 to the exhaust gas discharge port 139 of the turbine housing 126. The turbine outlet section 126C (hollow tube 136) can be annular in cross-section shape. The annual shape may be circular. A central axis of the turbine outlet section 126C (hollow tube 136) can be substantially coaxial with an axis of rotation of the turbine wheel 127.

At least part of the turbine outlet section 126C has a minimum length of at least six centimetres, for example approximately eight centimetres. The minimum length is defined as the axial distance by which the turbine outlet section 126C protrudes from the nearest edge of the turbine volute 126B. The minimum length provides space to accommodate the component(s) 202, 204 of the later-described heating system 200.

An Inner diameter and/or outer diameter of the turbine outlet section 126C may increase with downstream distance along the turbine outlet section 126C. A distal end of the turbine outlet section 126C can comprise a lip 135 as well as the exhaust gas discharge port 139. The lip 135 may extend radially outwardly. The lip 135 may extend radially outwardly from the central axis of the turbine outlet section 126C. The lip 135 may be shaped to enable a securing device, such as an external hose clamp, to secure the turbine outlet section 126C to another part of the exhaust system 100.

The turbine housing 126 may be a single part defining the turbine inlet section 126A, turbine volute 126B, and turbine outlet section 126C. The turbine inlet section 126A, turbine volute 126B, and turbine outlet section 126C, may be integral portions of a single part. They may be formed together. The turbine housing 126 may be a single cast part or a single forged part. In some examples, the compressor housing 121 is a separate part than the turbine housing 126, and formed separately. The turbine housing 126 may be formed from metal.

The turbine outlet section 126C can further comprise a wastegate actuator opening 138, to receive a component of a wastegate actuator (not shown).

Returning to FIG. 2, the turbine outlet section 126C is connected to another part of the exhaust system 100. The turbine outlet section 126C is releasably connected to the other part. The other part is secured to the turbine outlet section 126C via a releasable connector such as a hose clamp, spring clip, or flange connector.

In FIG. 2, the turbine outlet section 1260 is connected to a canning 150 via an adapter 140 (e.g., a widening funnel, that can be referred to as an exhaust inlet cone). Alternatively, the turbine outlet section 126C can be connected directly to the canning 150 if no adapter is required. The canning 150 is then connected to a downstream exhaust pipe 160 as shown.

FIG. 2 also illustrates oxygen sensors 302, 306, and a temperature sensor 304, secured to the canning 150 and/or downstream of the canning 150.

The canning 150 houses an exhaust gas aftertreatment device 152, which can comprise a catalytic converter such as a three-way catalytic converter, and/or can comprise a soot filter.

The exhaust gas aftertreatment device 152 needs to reach a light-off temperature at which it is effective to clean exhaust gases. The light-off temperature may be in the order of hundreds of degrees Celsius.

The heating system 200 shown in FIG. 2 is operable to raise the temperature quickly in a cold start situation, to minimise cumulative pollutant emissions.

The heating system 200 described herein defines an improved heating system 200 relative to standalone burner systems (not illustrated). A standalone burner system comprises a fresh air pump, an injector 202 for injecting fuel, an igniter 204, and a housing comprising a burner combustion chamber. The burner combustion chamber is outside the main exhaust gas path, and is connected to the main exhaust gas path via a pipe to a junction upstream of the exhaust gas aftertreatment device 152. Typically, the junction is at an oblique angle to direct hot gas from the burner towards the exhaust gas aftertreatment device 152. Challenges with standalone burner systems include minimising impact on overall vehicle weight, dealing with packaging constraints, and minimising the path length from the junction to the exhaust gas aftertreatment device 152 without risking uneven heating and overtemperature damage to exhaust gas aftertreatment device 152. Since the minimum path length for the burner is quite a long distance, the exhaust gas aftertreatment device 152 may need to be sited further downstream from the engine 10 than would be optimal, which means that the average engine exhaust gas temperature through the exhaust gas aftertreatment device 152 would be generally lower.

The heating system 200 described herein addresses the above problems. Instead of providing a separate housing with a separate burner combustion chamber, the fuel injector 202 and igniter 204 (e.g., spark plug/glow plug) of the heating system 200 are connected to existing exhaust system components and are connected as far upstream as possible. Further, the air pump can be omitted and instead fresh air can be generated by rotating the engine 10 using a torque source 14 such as an electric machine, before the engine 10 is predicted to / allowed to switch on. The electric machine can comprise a pinion starter, a starter-generator, or an electric drive unit, for example.

As shown in FIG. 3, the turbine outlet section 126C of the turbine housing 126 of the turbomachine assembly 120 is provided with an injector opening 132 in which the fuel injector 202 is received. By integrating the fuel injector 202 with the turbine housing 126, the fuel injector 202 can inject fuel into the exhaust as far upstream of the exhaust gas aftertreatment device 152 as possible. Additionally, the injection location is immediately downstream of the turbine wheel 127 which means that the incoming air has additional swirl and turbulence to improve fuel-air mixing.

In order to initiate combustion of the injected fuel as far upstream as possible, the turbine outlet section 126C is further provided with an igniter opening 134 in which the igniter 204 is received. In other examples, the igniter 204 is mounted to the exhaust system 100 downstream of the turbine housing 126.

The injector opening 132 and igniter opening 134 are through-holes extending through a wall 137 of the turbine outlet section 126C (hollow tube 136). The fuel injector 202 may protrude through the injector opening 132 into the interior space of the turbine outlet section 126C to be exposed to the airstream. The igniter 204 may protrude through the igniter opening 134 into the interior space of the turbine outlet section 126C to be exposed to the airstream and fuel spray from the fuel injector 202, to enable the igniter 204 to initiate combustion of the air-fuel mixture before the mixture has even reached the exhaust gas discharge port 139 of the turbine housing 126.

The injector opening 132 and igniter opening 134 are positioned so that the igniter 204 is aligned with a spray pattern of the fuel injector 202. The igniter opening 134 may be at approximately a same azimuthal position as the injector opening 132. The igniter opening 134 is downstream of the injector opening 132.

Regarding the azimuthal positions of the openings on the turbine outlet section 126C, FIG. 3 shows the injector opening 132 facing away from the turbine inlet section 126A so that the fuel injector 202 is located to the far side of the engine 10. The benefit is ease of access and enabling the fuel line (not shown) to be routed around the engine 10. The injector opening 132 may be at least partially upward facing, to ensure that any residual fuel drains downwardly. The igniter opening 134 may also face away from the turbine inlet section 126A and/or may be at least partially upward facing.

The fuel injector 202 may be angled to direct its spray pattern in a radially inward and downstream direction. The angle of the fuel injector 202 may also be tangential relative to the central axis of the turbine outlet section 126C, to initiate swirl in the spray pattern.

The injector opening 132 and igniter opening 134 are upstream of the exhaust gas discharge port 139 and downstream of the turbine wheel 127. They are shown upstream of the lip 135. The injector opening 132 and igniter opening 134 are holes rather than slots, and are therefore separated from/unconnected to the exhaust gas discharge port 139.

The fuel injector 202 may be mounted to the turbine housing 126. The igniter 204 may be mounted to the turbine housing 126. FIG. 3 further illustrates a mounting arrangement 131 providing injector mounting portion 131A and an igniter mounting portion 131B. The injector mounting portion 131A and igniter mounting portion 131 B can be separate mounting bosses, or can be portions of a same mounting boss as shown by the mounting arrangement 131 in FIG. 3. FIG. 3 shows the mounting arrangement 131 being a single mounting boss having a number of openings 132, 133, 134 including the injector opening 132 and igniter opening 134.

The turbine outlet section 126C of the turbine housing 126 comprises the injector mounting portion 131A and the igniter mounting portion 131B. The injector mounting portion 131A and igniter mounting portion 131B may have a flatter surface than that of the turbine outlet section 126C, for ease of mating. The injector mounting portion 131A and igniter mounting portion 131B may each be substantially flat.

The fuel injector 202 and igniter 204 may be mountable to the mounting arrangement 131 of the turbine outlet section 126C via fixings (e.g., bolts) to engage with the illustrated holes 133 in the mounting arrangement 131.

The fuel injector 202 and igniter 204 may be supported by a carrier structure (not shown) having a mating surface to mate with the mounting arrangement 131 in the form of the single mounting boss. The mating may be via a gasket (not shown). The carrier structure may have fixing points (e.g., holes) alignable with the holes 133 shown in the mounting arrangement 131. Alternatively, the fuel injector 202 and igniter 204 may be individually securable to (and releasable from) separate injector and igniter mounting portions. A shared carrier structure provides stiffness and ensures a durable connection to the mounting arrangement 131.

In another implementation than that illustrated in the Figures, the fuel injector 202 and optionally the igniter 204 may be mounted upstream of the turbine assembly. The fuel injector 202 and optionally the igniter 204 may be mounted to the exhaust manifold 110. The implementation illustrated in the Figures is however advantageous for being not too far upstream, such that thermal energy is not lost to the turbine assembly.

In a still further implementation, the fuel injector 202 and optionally the igniter 204 may be connected to a wastegate assembly (not shown), wherein the wastegate assembly comprises a wastegate housing and a wastegate duct. The wastegate assembly comprises an opening to receive the fuel injector 202 and optionally a further opening to receive the igniter 204.

FIG. 4 illustrates an example control system 400 configured to control the heating system 200.

The control system 400 of FIG. 4 comprises a controller 401. In other examples, the control system 400 may comprise a plurality of controllers on-board and/or off-board the vehicle 1.

The controller 401 of FIG. 4 includes at least one processor 404; and at least one memory device 406 electrically coupled to the electronic processor 404 and having instructions (e.g. a computer program 408) stored therein, the at least one memory device 406 and the instructions configured to, with the at least one processor 404, cause any one or more of the methods described herein to be performed. The controller 401 may have an interface 402 comprising an electrical input/output I/O 410, 412, or an electrical input 410, or an electrical output 412, for receiving information and interacting with external components. The electrical input 410 receives information from one or more sensors 414 such as any sensor indicative of an engine ignition state or vehicle power mode, and/or any sensor indicative of a current capability (e.g., temperature) of the exhaust gas aftertreatment device 152. The electrical output 412 is for transmitting control signals to control systems such as the engine 10, the fuel injector 202, and the igniter 204.

FIG. 5 illustrates a non-transitory computer-readable storage medium 500 comprising the instructions 408 (computer software).

FIG. 6 is a flowchart illustrating a method 600. The method 600 is a computer-implemented 25 method. The method 600 may be executed by the control system 400.

Block 602 comprises outputting a control signal to cause an air pumping means to provide combustion-supporting air for the heating system 200.

In the example where the air pumping means is the engine 10, block 602 comprises outputting the control signal to cause a torque source 14 (e.g., electric machine) connected to the engine 10 to rotate (the crankshaft of) the engine 10 to provide combustion-supporting air for the heating system 200, while the engine 10 is not running. By rotating the crankshaft of the engine 10 while the engine 10 is not running, combustion-supporting air is pumped through the turbine housing 126. Since the engine 10 is not running (injecting and igniting fuel), the air remains combustion-supporting as it enters the exhaust system 100. However, the engine may be started and running and the exhaust gas may remain sufficiently combustion-supporting. This may particularly be the case if the engine is run in a lean mode on starting, which is also possible to more quickly increase the temperature of the exhaust gas and subsequently of the exhaust gas aftertreatment device.

In another example, a dedicated air pump is used and is arranged to supply the combustion-supporting air to the turbine housing 126 or upstream of the turbine housing 126 without passing through the engine 10.

The torque source 14 can be any suitable electric machine operable to rotate the engine 10. Alternatively, the torque source 14 can be the vehicle wheels (not shown) of the vehicle 1, because the vehicle wheels can rotate the engine 10 if the vehicle 1 is moving over ground while the engine 10 is connected to the vehicle wheels. This may be the case where an electric motor drives the wheels directly in a hydrid electric vehicle.

The control signal may be output in response to an input signal indicative of a requirement to raise the temperature of the exhaust gas aftertreatment device 152. For example, the input signal may be indicative of a requirement to run the engine 10. The input signal may be generated based on information from one or more of the above-described sensors.

Block 604 comprises injecting fuel into the turbine outlet section 126C of the turbine housing 126. This comprises outputting a control signal to the fuel injector 202 to inject the fuel into the turbine outlet section 126C, to cause the fuel to mix with the combustion-supporting air.

Block 606 comprises igniting the fuel in the turbine housing 126. This comprises outputting a control signal to the igniter 204 to cause ignition of the mixture of injected fuel and combustion-supporting air.

An effect of the above is that the exhaust gas aftertreatment device 152 is heated rapidly to its operating temperature, without the compromises associated with standalone burner system.

It is to be understood that the or each controller 401 can comprise a control unit or computational device having one or more electronic processors (e.g., a microprocessor, a microcontroller, an application specific integrated circuit (ASIC), etc.), and may comprise a single control unit or computational device, or alternatively different functions of the or each controller 401 may be embodied in, or hosted in, different control units or computational devices. As used herein, the term "controller," "control unit," or "computational device" will be understood to include a single controller, control unit, or computational device, and a plurality of controllers, control units, or computational devices collectively operating to provide the required control functionality. A set of instructions could be provided which, when executed, cause the controller 401 to implement the control techniques described herein (including some or all of the functionality required for the method 600 described herein). The set of instructions could be embedded in said one or more electronic processors of the controller 401; or alternatively, the set of instructions could be provided as software to be executed in the controller 401. A first controller or control unit may be implemented in software run on one or more processors. One or more other controllers or control units may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller or control unit. Other arrangements are also useful.

In the example illustrated in Figure 4, the or each controller 401 comprises at least one electronic processor 404 having one or more electrical input(s) 410 for receiving one or more input signals, and one or more electrical output(s) 412 for outputting one or more output signals the inject fuel into the turbine outlet section 126C of the turbine housing 126 and ignite the fuel in the turbine housing 126. The or each controller 401 further comprises at least one memory device 406 electrically coupled to the at least one electronic processor 404 and having instructions 408 stored therein. The at least one electronic processor 404 is configured to access the at least one memory device 406 and execute the instructions 408 thereon so as to output the control signals in dependence on satisfaction of a condition for operating the heating system 200.

The, or each, electronic processor 404 may comprise any suitable electronic processor (e.g., a microprocessor, a microcontroller, an ASIC, etc.) that is configured to execute electronic instructions. The, or each, electronic memory device 406 may comprise any suitable memory device and may store a variety of data, information, threshold value(s), lookup tables or other data structures, and/or instructions therein or thereon. In an embodiment, the memory device 406 has information and instructions for software, firmware, programs, algorithms, scripts, applications, etc. stored therein or thereon that may govern all or part of the methodology described herein. The processor, or each, electronic processor 404 may access the memory device 406 and execute and/or use that or those instructions and information to carry out or perform some or all of the functionality and methodology describe herein.

The at least one memory device 406 may comprise a computer-readable storage medium (e.g. a non-transitory or non-transient storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational devices, including, without limitation: a magnetic storage medium (e.g. floppy diskette); optical storage medium (e.g. CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g. EPROM ad EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

Example controllers 401 have been described comprising at least one electronic processor 404 configured to execute electronic instructions stored within at least one memory device 406, which when executed causes the electronic processor(s) 404 to carry out the method as hereinbefore described. However, it will be appreciated that embodiments of the present invention can be realised in any suitable form of hardware, software or a combination of hardware and software. For example, it is contemplated that the present invention is not limited to being implemented by way of programmable processing devices, and that at least some of, and in some embodiments all of, the functionality and or method steps of the present invention may equally be implemented by way of non-programmable hardware, such as by way of non-programmable ASIC, Boolean logic circuitry, etc. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

The blocks illustrated in FIG. 6 may represent steps in a method and/or sections of code in the computer program 408. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS1. An exhaust system for a vehicle, the exhaust system comprising a turbomachine assembly, and a component of a heating system, wherein the heating system is for raising a temperature of an exhaust gas aftertreatment device, wherein the turbomachine assembly comprises a turbomachine housing, wherein the turbomachine housing comprises: an inlet section having an exhaust gas inlet port; a turbine volute; and an outlet section extending from the turbine volute and having an exhaust gas discharge port; wherein the outlet section of the turbomachine housing further comprises an opening, wherein the component of the heating system is received in the opening.
2. The exhaust system of claim 1, wherein the opening extends through a wall of the outlet section of the turbomachine housing at a location upstream of the exhaust gas discharge port.
3. The exhaust system of claim 1 or 2, further comprising a mounting portion to which the component is secured, wherein the opening and the mounting portion are arranged to position the component to extend through the opening to expose the component to an interior space of the outlet section.
4. The exhaust system of claim 1, 2 or 3, wherein the opening is an injector opening, and wherein the component is a fuel injector.
5. The exhaust system of claim 4, further comprising an igniter of the heating system, wherein the turbomachine housing is further configured to receive the igniter of the heating system, and expose the igniter to the interior space of the outlet section to enable the igniter to initiate combustion of fuel injected by the fuel injector.
6. The exhaust system of claim 5, wherein the outlet section of the turbomachine housing comprises a second opening exposing the igniter of the heating system to the interior space of the outlet section, wherein the second opening is proximal to the injector opening.
7. The exhaust system of claim 6, comprising an igniter mounting portion to which the igniter is secured, wherein the second opening and the igniter mounting portion are arranged to position the igniter to extend through the second opening and expose the igniter to the interior space of the outlet section.
8. The exhaust system of claim 6 or 7, wherein the second opening for the igniter is downstream of the injector opening, closer to the exhaust gas discharge port than the injector opening.
9. The exhaust system of any preceding claim, wherein the turbomachine housing is a single cast part including the turbine volute and the outlet section, and optionally the inlet section.
10. The exhaust system of any preceding claim, wherein the turbomachine assembly is a turbocharger assembly.
11. The exhaust system of any preceding claim, further comprising the heating system.
12. A system comprising the exhaust system of any one of the preceding claims, and comprising a control system configured to output a control signal to cause a torque source connected to an internal combustion engine to rotate the internal combustion engine to provide combustion-supporting air for the heating system.
13. A vehicle comprising the exhaust system of any one of claims 1 to 11 or the system of claim 12.
14. A method of raising a temperature of gas in a turbomachine assembly for an exhaust system of a vehicle, the method comprising: injecting fuel into an outlet section of a turbomachine housing of the turbomachine assembly; and igniting the fuel in the turbomachine housing upstream of an exhaust gas aftertreatment device.
15. Computer software that, when executed, is arranged to perform a method according to claim 14.