Turbomachine housing with heating system inlet and valve

Abstract

A turbomachine housing 200 comprises a heating system inlet 212 configured to merge a heated gas output path 224 from a heating system (170, Fig. 1B) with an exhaust gas flow path 226 from an internal

Description

TECHNICAL FIELD The present disclosure relates to a turbomachine housing with a heating system inlet and valve. Aspects of the invention relate to a turbomachine housing, a system, a vehicle, a method and computer software. BACKGROUND It is known to provide exhaust gas aftertreatment devices for vehicles to reduce substances emitted by the vehicle. Some exhaust gas aftertreatment devices require heating to above ambient temperatures in order to be efficient. However, other components of a vehicle may not be rated to withstand significant heating. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a turbomachine housing, a system, a vehicle, a method and computer software as claimed in the appended claims. According to an aspect of the present invention there is provided a turbomachine housing for a vehicle. According to an aspect of the present invention there is provided a turbomachine housing for a vehicle, the turbomachine housing comprising: a heating system inlet configured to merge a heated gas output path from a heating system with an exhaust gas flow path from an internal combustion engine; and a valve configured to allow a flow of gas from the heated gas output path to the exhaust gas flow path and to inhibit a flow of gas from the exhaust gas flow path to the heated gas output path. Advantageously, the valve prevents backflow of hot gases (in particular exhaust gases) towards the heating system. Said hot gases could cause damage to the heating system. Optionally, the turbomachine housing comprises the heating system inlet such that the valve is configured to allow a flow of gas from the heating system into the turbomachine housing and to inhibit a flow of gas from the turbomachine housing towards the heating system. Optionally, the valve is provided at the heating system inlet, to an interior side of the turbomachine housing. Advantageously, providing the valve at the heating system inlet to an interior side of the turbomachine housing uses the existing turbomachine housing as a support for the valve. This saves cost, weight and complexity when compared to providing the valve to an exterior side of the turbomachine housing. Optionally, the turbomachine housing further comprises a waste gate valve, separate to the valve. Optionally, the heating system inlet further comprises a mounting portion to which a heating system output pipe is secured, the heating system output pipe configured to transfer heated gas output from the heating system to the heating system inlet, and the valve is provided upstream of the heating system inlet, within the heating system output pipe or to an end of the heating system output pipe proximal to the heating system. Optionally, the valve is movable to an open position when heated gas is received from the heating system, and movable to a closed position when no heated gas is received from the heating system. This advantageously allows flow of the gas from the heating system when the heating system is running. Optionally, the turbomachine housing further comprises an actuator configured to move the valve between the open position and the closed position. According to a further aspect of the invention, there is provided a system comprising the turbomachine housing described above, and a control system for preventing backflow of exhaust gases, the control system comprising one or more controllers, the control system configured to: receive an input signal associated with a commencement of operation of a heating system; and output an opening signal to open the valve. Optionally, the control system is further configured to: receive an input signal associated with ceasing of operation of the heating system; and output a closing signal to close the valve. The control system may be system further configured to: output the closing signal to close the valve when the temperature of an exhaust gas after treatment device supplied with exhaust gas and / or heated gas from the turbomachine housing reaches a threshold. The control system may be further configured to: receive an input signal indicative of a pressure of exhaust gas in the exhaust gas flow path; receive an input signal indicative of a pressure of heated gas in the heated gas output path; and output the closing signal to close the valve when the pressure of exhaust gas in the exhaust gas flow path and the pressure of heated gas in the heated gas output path are determined to be such that exhaust gas would flow into the heated gas output path if the valve was not closed. According to a further aspect of the invention, there is provided a vehicle comprising the turbomachine housing described above or the system described above. According to a further aspect of the invention, there is provided a method of preventing backflow of exhaust gases, the method comprising: receiving an input signal indicative of a commencement of operation of a heating system; and causing a valve to move from a closed position to an open position to enable a heated gas output from the heating system to be joined with an exhaust gas flow path from an internal combustion engine. Optionally, the method further comprises: receiving an input indicative of a ceasing of operation of the heating system; and causing the valve to move from the open position to the closed position. Put another way, a method of preventing backflow of exhaust gases comprises: receiving an input indicative of a ceasing of operation of a heating system; and causing a valve to move from an open position to a closed position to prevent exhaust gas in an exhaust gas flow path from an internal combustion engine from entering a heated gas output of the heating system. The method may further comprise: receiving an input signal indicative of a commencement of operation of the heating system; and causing the valve to move from the closed position to the open position to enable the heated gas output from the heating system to be joined with an exhaust gas flow path from an internal combustion engine. The input indicative of a ceasing of operation of a heating system may be responsive to a detection of: a pressure of exhaust gas in the exhaust gas flow path rising beyond a threshold value at which exhaust gas will enter the heated gas output; and / or a temperature of an exhaust gas after treatment device supplied by the exhaust gas flow path and heated gas flow path exceeds a threshold value. According to a further aspect of the invention, there is provided computer software that, when executed, is arranged to perform a method described above. 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. 1A illustrates a perspective view illustrating an example of a vehicle; FIG. 1B schematically illustrates an example of vehicle engine components; FIGs 2A and 2B illustrate front and side views respectively of an example turbomachine housing; FIGs 3A, 3B, 3C and 3D illustrate schematic cut-away views of an example turbomachine housing; FIG. 4 illustrates a schematic view illustrating an example of a control system; FIG. 5 illustrates a schematic view illustrating an example of a storage medium; FIG. 6 illustrates a schematic view illustrating an example of a system; and FIG. 7 illustrates a flowchart illustrating an example of a method of preventing backflow of exhaust gases. DETAILED DESCRIPTION A vehicle 1 in accordance with an embodiment of the present invention is described herein with reference to the accompanying FIG. 1A. 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. 1B schematically illustrates an internal combustion engine 10 (‘engine’ or ‘ICE’ herein), an electric machine 14 (electric motor or motor / generator), an electrical energy storage means 16 such as a battery, a control system 400, and a portion of an exhaust system 100. The invention is not limited to the specific layout shown. 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. The exhaust system 100 in FIG. 1B comprises an exhaust manifold 110, a turbomachine assembly 120, a burner 170, a canning 150 (housing) comprising an exhaust gas aftertreatment device 152, and one or more exhaust pipes 140, 160. The canning 150 houses the exhaust gas aftertreatment device 152, which can comprise a catalytic converter such as a three-way catalytic converter. The exhaust gas aftertreatment device 152 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. The exhaust system 100 further comprises a heating system, in the form of a burner 170, for heating the exhaust gas aftertreatment device 152. A burner is a heating device, separate to the engine 10, that serves to provide hot air at least to the exhaust gas aftertreatment device 152 in order to raise the temperature of the exhaust gas aftertreatment device 152 towards the light-off temperature. The effectiveness of the burner 170 requires a flow of air through the heating system and exhaust gas aftertreatment device 152. The air should also be fresh and unburnt, to provide oxygen for combustion. The burner 170 comprises an injector, an igniter, and a housing comprising a burner combustion chamber. The fuel injector may inject fuel such as petrol or diesel. The igniter may be, for example, a spark plug or an electrode. The vehicle 1 may comprise a fresh air pump (not shown) upstream of the burner 170, to provide unburnt air to the burner combustion chamber. The burner combustion chamber is outside an exhaust gas 4 flow path 226, and is connected to the exhaust gas flow path 226 via a burner outlet pipe to a junction upstream of the exhaust gas aftertreatment device 152, as shown in FIGS. 2A-3C. Examples of the present invention, as shown in FIGs 2A, 2B, 3A,3B, 3C and 3D, provide a turbomachine housing for a vehicle 1, in the form of a turbocharger housing 200. The illustrated turbocharger housing 200 is a turbine housing. In other implementations, the housing 200 is for a different type of turbomachine such as a turbocompounder. FIGs 2A and 2B illustrate an example of a turbocharger housing 200 comprising a heating system inlet 212. The turbocharger housing 200 may comprise an outlet section 208 having an exhaust gas discharge port 210. In examples, the turbocharger housing 200 is configured to output the exhaust gases received from the engine 10 to the exhaust gas aftertreatment device 152 via the exhaust gas discharge port 210. Additionally or alternatively, the outlet section 208 may comprise the heating system inlet 212. The turbocharger housing 200 can comprise a turbine wheel and a compressor wheel which together define a turbocharger, wherein the turbine wheel drives the compressor wheel. The outlet section 208 can further comprise a waste gate actuator opening 216, to receive a component of a waste gate actuator 218 for actuating a waste gate valve 222 (FIG. 3A). The illustrated turbocharger housing 200 comprises an inlet section 202 having an exhaust gas inlet port 204. In examples, the exhaust gas inlet port 204 is configured to receive exhaust gas from the internal combustion engine. In examples, the turbocharger housing 200 further comprises a turbine volute 206 fluidly connected to the inlet section 202. In such examples, the outlet section 208 is fluidly connected to, and extends from, the turbine volute 206. The turbine volute 206 has a spiral-shaped form, also referred to as a scroll-shaped form. The turbine volute 206 is configured as a funnel to decrease the cross-sectional area of the exhaust gas channel in a downstream direction. The turbine volute 206 is arranged around the turbine wheel and is arranged to direct exhaust gas through the turbine wheel. If the turbocharger housing 200 is a multi-volute turbocharger housing as shown, multiple turbine volutes may be provided. Each turbine volute is for a corresponding one of multiple exhaust gas channels. The turbine volutes merge, meaning that their respective exhaust gas channels merge around and through the turbine and into the outlet section 208. Some exhaust gas aftertreatment devices require heating to above ambient temperature in order to be efficient. For example, a catalytic converter has low efficiency until it reaches a light-off temperature. When the catalytic 5 converter reaches the light-off temperature, its efficiency rapidly increases. The light-off temperature may be approximately 250C - 300C. To minimise emissions produced by a vehicle, it is desirable to raise a temperature of the catalytic converter to the light-off temperature before an engine 10 of the vehicle enters a full running state in which significant exhaust gases requiring after-treatment are produced, or soon after the engine 10 enters the running state. This enables more efficient treatment of exhaust gas produced by the engine 10. The catalytic converter 152 is therefore heated using the burner 170. The turbocharger housing 200 is configured to receive a heated gas output from the burner 170 and to output at least that gas towards the catalytic converter. In examples, the heated gas output from the burner 170 is received by the heating system inlet 212. The burner 170 is omitted in FIGS. 2A-3D. The turbocharger housing 200 therefore receives at least two gas output paths: a heated gas output path 224 from the burner 170 and an exhaust gas flow path 226 from the engine 10. The heating system inlet 212 is configured to merge the two gas paths. The burner 170 may begin operation before the engine 10 is cranked, which allows for the temperature of the catalytic converter to be raised to or towards the light-off temperature before the engine 10 enters a running state. A fresh air pump upstream of the burner 170 may provide positive air flow from the burner 170 towards the catalytic converter. ‘Positive’ refers to a direction away from the engine 10 and towards a tailpipe of the vehicle in which the engine is fitted. Therefore, when the burner 170 is running before the engine 10 is cranked and / or enters the running state there is a positive airflow in the heated gas output path 224 from the burner 170 towards the turbocharger housing 200, and heated gas output from the burner 170 is therefore delivered to the turbocharger housing 200. When the engine 10 is cranked and / or enters the running state, a positive air flow is produced in the exhaust gas flow path 226 from the engine 10 to the turbocharger housing 200. In some situations, the pressure in the exhaust gas flow path 226 may be higher than the pressure in the heated gas output path 224. For example, the burner 170 may not be running while the engine 10 is running. Therefore, if the heated gas output path 224 is open and permits two-way flow, the flow direction in the heated gas output path 224 would be reversed such that exhaust gases would be moved from the turbocharger housing 200 towards the burner 170. Upstream from the turbocharger housing 200, the burner 170 receives fresh air from an air filter (not shown) of the vehicle 1. In examples, the burner 170 is rated to operate at high temperatures (e.g., temperatures above 200C or temperatures above 800C) but the air filter and other upstream components are not. The heated gas output by the burner 170 and / or the exhaust gases received from the engine 10 may be higher than a maximum operating temperature of the air filter. Thus, if the flow direction in the heated gas output path 224 is reversed, the upstream components may be damaged. Further, a reversal in flow direction of the heated gas output path 224 provides a path for exhaust gas to escape to the atmosphere (which is against emissions regulations) or to enter back into the air intake system (which may affect engine operation). Further, the difference between the positive air flow in the exhaust gas flow path 226 and the positive air flow in the heated gas output path 224 (even while the burner 170 is operating) may be sufficiently large that the heated gas output path 224 is reversed and the pressure of the heated gas output path 224 is increased. This may cause damage to the burner 170, the external air filter, and other upstream components. Therefore, embodiments of the turbocharger housing 200 may be configured to inhibit a flow of gas from the exhaust gas flow path 226 to the heated gas output path 224. FIGs 3A, 3B, 3C and 3D illustrate examples of a turbocharger housing 200 comprising a heating system inlet 212 and a valve 214. In the example of FIG. 3A, the valve 214 is a pivotable poppet valve. In the example of FIGs 3C and 3D, the valve 214 is a linear poppet valve. In further examples, the valve 214 may be any other suitable type of valve, for example a check valve or a butterfly valve. The valve 214 is configured to allow a flow of gas from the heated gas output path 224 to the exhaust gas flow path 226 and to inhibit a flow of gas from the exhaust gas flow path 226 to the heated gas output path 224. In other words, if the pressure gradient across the valve 214 is in a back flow direction, gas is prevented from flowing back into the burner 170 and the other upstream components. In examples, the valve comprises a return spring. The return spring acts as a failsafe by biasing the valve towards the closed position even if the actuator fails. In this case, the actuator serves to open the valve. In examples, the heating system inlet 212 and valve 214 are provided such that valve 214 is configured to allow a flow of gas from the heating system into the turbocharger housing 200 and to inhibit a flow of gas from the turbocharger housing 200 towards the heating system. The valve may be provided and / or seated to an interior (hot) side or exterior (cold) side of the turbine housing. In examples, the valve 214 is provided to an interior of the turbocharger housing 200 such that flow of exhaust gases beyond a boundary of the turbocharger housing 200 is prevented. In other examples, the valve 214 is provided to an exterior of the turbocharger housing 200 such that flow of exhaust gases beyond the turbocharger housing 200 is prevented. In such examples, the valve 214 may be bolted-on to the exterior of the turbocharger housing 200. In FIGS. 3A-3D, the heating system comprises a mounting portion 232 to which a heating system output pipe 220 is secured. FIGs 3A and 3B illustrate an example turbomachine housing 200 to which a heating system output pipe 220 is secured. The heating system output pipe 220 is configured to transfer the heated gas output from the burner 170 to the heating system inlet 212. In such examples, the valve 214 is provided upstream of the heating system inlet 212, within the burner outlet pipe, such that flow of exhaust gases beyond the boundary of the turbocharger housing 200 is allowed, but flow of exhaust gases beyond a valved section of the burner outlet pipe is prevented. In examples, the valve 214 has an open position and a closed position. In the open position, flow of gas through the valve 214 (in either direction) is allowed. In the closed position, flow of gas through the valve 214 (in either direction) is limited. In examples, the valve 214 is movable to the open position when heated gas is received from the burner 170, that is, when the burner 170 is operating. The valve 214 may be movable to the open position when the burner 170 is turned on. Alternatively, the valve 214 may be movable to the open position when the receiving of heated gas from the burner 170 is detected. Additionally or alternatively, the valve 214 may be movable to the open position when the engine 10 has not been cranked and / or is not in the running state, and / or when the receiving of exhaust gases from the engine 10 is not detected. In examples, the valve 214 is movable to the closed position when no heated gas is received from the burner 170, that is, when the burner 170 is not operating. The valve 214 may be movable to the closed position when the burner 170 is turned off and / or stops operating. Alternatively, the valve 214 may be movable to the closed position when the receiving of heated gas from the burner 170 is not detected. Additionally or alternatively, the valve 214 may be movable to the closed position when the engine 10 has been cranked and / or is in the running state, and / or when the receiving of exhaust gases from the engine 10 is detected. In embodiments, a failsafe feature is provided such that the valve may be moved to the closed position if one or more of engine revolutions per minute (RPM) or turbine pressure exceeds a predetermined threshold. The threshold may be selected such that the burner is protected from engine exhaust gases should the pressure of the exhaust gas flow 226 exceed the pressure of heated gas flow 224 and commence backflow of exhaust gases towards the burner 170. As shown in FIG. 3C, the turbocharger housing 200 may further comprise an actuator 228 configured to move the valve 214 between the open position and the closed position, via any appropriate mechanism. The actuator may be an electromagnetic actuator or an electromechanical actuator or a pneumatic actuator. In some examples where the actuator is an electromagnetic actuator, the actuator comprises a magnet actuated by an electrical current, and a mechanical spring that biases the valve to the closed position. In some examples where the actuator is an electromechanical actuator, the actuator comprises an electric motor driving a set of gears and / or rod linkages. Any of the abovementioned types of actuator may be used regardless of whether the valve 214 is a pivotable poppet valve, a linear poppet valve, or some other type of valve. FIGS. 3A-3B show an example where the valve 214 is an internal, pivotable poppet valve inside the outlet section of the turbocharger assembly 200. FIG. 3B shows part of a mechanism connecting the actuator to the valve 214. A linkage arm 215 is shown, connected at one end directly or indirectly to the actuator, and at the illustrated opposite end to a pivot 234 of a stem of the valve 214. The pivot is formed in the turbocharger housing 200. The linkage arm 215 is eccentrically connected to the pivot of the valve 214. Therefore, motion of the linkage arm 215 pivots the valve 214 into and out of a valve seat formed in the turbocharger housing 200. FIGS. 3C-3D show an example where the valve 214 is a linear poppet valve, having a valve head inside the outlet section 208 of the turbocharger assembly 200, and a valve stem extending out of the turbocharger assembly 200. The valve stem may extend out of an opening in the heating system output pipe 220 towards the actuator. The valve stem may be coupled to the actuator via any appropriate mechanism, such as a rocker arm and / or a cam. FIGS. 3C-3D further illustrate a return spring 230 configured to bias the valve towards the closed position. In such examples, the output pipe may be a casted component comprising a valve stem seal and a valve stem seat. The turbocharger housing 200 may also comprise a waste gate valve 222, provided and controlled separately to the valve 214. With reference to FIG. 4, there is illustrated a control system 400 for a vehicle 1. The control system 400 comprises one or more controllers 401. The control system 400 is configured to receive burner operation data from a burner system control module and determine a required position of the valve 214. The control system 400 may then output a control signal to control the position of the valve 214. The valve is moved to the open position when the burner is activated and is moved to the closed position when the burner is deactivated. The control system 400 may be further configured to receive temperature data from temperature sensors at the burner outlet and catalyst inlet and determine if heat flow is as expected. Based on this, it may be determined whether the valve is in the correct position. Further, the control system 400 may be configured to receive turbomachine outlet pressure data and engine RPM data and determine if the turbomachine outlet pressure is greater than the maximum expected pressure provided by the burner pump. Based on this, the control system 400 may then output a control signal to move the valve 214 to the closed position. The control system 400 is configured to receive an on / off command from an engine control module. The control system 400 may then output a control signal to control valve position and burner system fuelling strategy. The control system 400 as illustrated in FIG. 4 comprises one controller 401, although it will be appreciated that this is merely illustrative. The controller 401 comprises processing means 404 and memory means 406. The processing means 404 may be one or more electronic processing devices 404 which operably execute computer-readable instructions. The memory means 406 may be one or more memory devices 406. The memory means 406 is electrically coupled to the processing means 404. The memory means 406 is configured to store instructions, and the processing means 404 is configured to access the memory means 406 and execute the instructions stored thereon. The controller 401 comprises an input means 410 and an output means 412. The input means 410 may comprise an electrical input 410 of the controller 401. The output means 412 may comprise an electrical output 412 of the controller 401. The input 410 is arranged to receive a valve position signal from an engine control module. The valve position signal is an electrical signal which is indicative of a required position of the vlave (on / open or off / closed). The output 412 is arranged to output a valve 214 control signal for controlling opening and / or closing of the valve 214. FIG. 5 illustrates a non-transitory computer-readable storage medium 500 comprising the instructions (computer software). FIG. 6 illustrates a system 600 comprising the turbomachine housing 200 described above and a control system 400. FIG. 7 illustrates a method 700 according to an embodiment of the invention. The method 700 is a method of preventing backflow to the burner 170 of exhaust gases within a vehicle 1, such as the vehicle 1 illustrated in FIG. 1. The method 700 may be performed by the control system illustrated in FIG. 4. In particular, the memory 406 may comprise computer-readable instructions 408 which, when executed by the processor 404, perform the method 700. Method 700 is a method of preventing backflow of exhaust gases. Method 700 comprises: at block 702, receiving an input signal indicative of a commencement of operation of the heating system (e.g., burner 170); and at block 704, causing the valve 214 to move from the closed position to the open position to enable the heated gas output from the heating system to be joined with the exhaust gas flow path 226 from the engine 10. The input signal may be received from a controller or from one or more sensors. In a reactive implementation, the input signal is generated based on information from any appropriate sensor configured to detect a current or requested ignition state of the engine. In a predictive implementation, the input signal is generated based on information from any appropriate sensor associated with a high likelihood of future engine running, such as 10 a driver’s door sensor, a driver’s seatbelt sensor, a driver’s seat weight sensor, etc, enabling the burner 170 to be used prior to engine start. Similarly, in the case of a hybrid vehicle having an electric motor powered by a battery, the input signal may be derived from a requirement for engine running to maintain or increase charge in the battery. The valve 214 may be opened when the burner 170 is activated. Block 704 may further comprise activating the burner 170. Causing the valve 214 to move from the closed position to the open position can comprise outputting an opening signal to the actuator to open the valve 214. Method 700 may further comprise: at block 706, receiving an input indicative of a ceasing of operation of the heating system; and at block 708, causing the valve 214 to move from the open position to the closed position. The input signal may be received from a controller or from one or more sensors. The input signal may be generated based on a determination that light-off temperature has been reached. In some examples, the input signal may be based on the same information as described above, to turn the burner 170 off based on received exhaust gas temperature data and oxygen sensor data. Causing the valve 214 to move from the open position to the closed position can comprise outputting a closing signal to the actuator to close the valve 214. 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 ofthe 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 ofthe functionality required for the method(s) described herein). The set of instructions 408 could be embedded in said one or more electronic processors 404 ofthe controller 401; or alternatively, the set of instructions 408 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. 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 408. The, or each, electronic memory device 406 may comprise any suitable memory device and may store a variety of 11 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 orthose instructions and information to carry out or perform some or all of the functionality and methodology described 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. Examples of the form include, 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. 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. For The blocks illustrated in FIG 7 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. 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.

Claims

16 04^51. A turbomachine housing for a vehicle, the turbomachine housing comprising:a heating system inlet configured to merge a heated gas output path from a heating system with an5 exhaust gas flow path from an internal combustion engine; anda valve configured to allow a flow of gas from the heated gas output path to the exhaust gas flow path and to inhibit a flow of gas from the exhaust gas flow path to the heated gas output path.

2. The turbomachine housing of claim 1, wherein the valve is provided at the heating system inlet, to an 10 interior side of the turbomachine housing.

3. The turbomachine housing of claim 1 or 2, further comprising a waste gate valve, separate to the valve.15 4. The turbomachine housing of claim 1, 2 or 3, wherein the heating system inlet further comprises amounting portion to which a heating system output pipe is secured, the heating system output pipe configured to transfer heated gas output from the heating system to the heating system inlet, and whereinthe valve is provided upstream of the heating system inlet, within the heating system output pipe or to an end of the heating system output pipe proximal to a heating system.

5. The turbomachine housing of any preceding claim, further comprising an actuator configured to move the valve between the open position and the closed position.

6. A system comprising the turbomachine housing of any preceding claim, and a control system for25 preventing backflow of exhaust gases, the control system comprising one or more controllers, the control system configured to:receive an input signal associated with a commencement of operation of a heating system; and output an opening signal to open the valve.30 7. The system of claim 6, the control system further configured to:receive an input signal associated with ceasing of operation of the heating system; and output a closing signal to close the valve.

8. The system of claim 7, the control system further configured to:35 output the closing signal to close the valve when the temperature of an exhaust gas after treatmentdevice supplied with exhaust gas and / or heated gas from the turbomachine housing reaches a threshold.

9. The system of claim 7 or 8, the control system further configured to:receive an input signal indicative of a pressure of exhaust gas in the exhaust gas flow path;40 receive an input signal indicative of a pressure of heated gas in the heated gas output path; and16 04^5output the closing signal to close the valve when the pressure of exhaust gas in the exhaust gas flow path and the pressure of heated gas in the heated gas output path are determined to be such that exhaust gas would flow into the heated gas output path if the valve was not closed.5 10. A vehicle comprising the turbomachine housing of any of claims 1 to 5 or the system of any of claims6 to 9.

11. A method of preventing backflow of exhaust gases, the method comprising:in response to receiving an input signal indicative of a commencement of operation of the heating10 system, causing a valve of a turbomachine housing to move from a closed position to an open position to enable a heated gas output from the heating system to be joined with an exhaust gas flow path from an internal combustion engine at a heating system inlet of the turbomachine housing; andin response to receiving an input indicative of a ceasing of operation of a heating system, causing the valve to move from the open position to the closed position to prevent exhaust gas in the exhaust gas flow 15 path from the internal combustion engine from entering the heated gas output of the heating system.

12. The method of claim 11, wherein the input indicative of a ceasing of operation of a heating system is responsive to a detection of:a pressure of exhaust gas in the exhaust gas flow path rising beyond a threshold value at which exhaust gas will enter the heated gas output; and / ora temperature of an exhaust gas after treatment device supplied by the exhaust gas flow path and heated gas flow path exceeds a threshold value.

13. Computer software that, when executed, is arranged to perform a method according to any of claims25 11 to 12.

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