GB2582599A

GB2582599A - An exhaust system for an internal combustion engine and a method

Info

Publication number: GB2582599A
Application number: GB1904226.6A
Authority: GB
Inventors: John Mcallister Matthew; Matthews Tom
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2019-03-27
Filing date: 2019-03-27
Publication date: 2020-09-30
Anticipated expiration: 2039-03-27
Also published as: GB2582599B; GB201904226D0; DE102020106315A1

Abstract

Disclosed is an exhaust system 104 for an internal combustion engine 103, a vehicle 101, a method and non-transitory computer readable medium for carrying out the method. The exhaust system 104 comprises at least one cylinder head 202 defining a first integrated exhaust manifold 208A and a second integrated exhaust manifold 208B. A first aftertreatment component 210 is provided in fluid communication with both the first integrated exhaust manifold 208A and the second integrated exhaust manifold 208B. The exhaust system also comprises a second aftertreatment component 211 configured to enable a flow of exhaust gases from the first integrated exhaust manifold 208A through the second aftertreatment component 211 to the first aftertreatment component 210. The aftertreatment component may be a catalytic convertor. Turbines for a turbocharger system may be located in the exhaust passage. The engine may selectively deactivate a first cylinder group connected to an exhaust manifold during warm up and activate all cylinders once the engine has warmed up.

Description

AN EXHAUST SYSTEM FOR AN INTERNAL COMBUSTION ENGINE AND A METHOD

TECHNICAL FIELD

The present disclosure relates to an exhaust system for an internal combustion engine, a vehicle, a method and a non-transitory computer readable medium. In particular, but not exclusively it relates to an exhaust system for an internal combustion engine, a vehicle, a method and a non-transitory computer readable medium for a road vehicle such as a car.

BACKGROUND

Exhaust systems for internal combustion engines are know to have two catalytic converters arranged in series. A first one of the two catalytic converters is positioned closest to the exhaust manifold of the engine and consequently when the engine is started from cold, the first catalytic converter warms up to its operating temperature (a "light-off" temperature) before the second catalytic converter reaches its operating temperature. Thus, the first catalytic converter provides treatment of exhaust gases while the second catalytic converter continues to warm up. When both catalytic converters are up to their operating temperatures, they are both able to play a part in the treatment of exhaust gases.

A problem with this arrangement is that there is a period of time, before the first catalytic converter is warming up to its operating temperature, in which the exhaust system emits relatively large quantities of noxious gases.

In addition, when the engine and catalytic converters are up to their operating temperatures, the first catalytic converter can become damaged by overheating at high power outputs of the engine. To avoid such overheating, it is known to run the engine with a rich fuel to air mixture so that cooler exhaust gases are produced. However, the disadvantage of this is that by not operating the engine at a stoichiometric air-fuel ratio (referred to as "lambda 1'1), the emission of noxious gases by the exhaust system is increased.

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 an exhaust system for an internal combustion engine, a vehicle, a method and non-transitory computer readable medium as claimed in the appended claims.

According to an aspect of the invention there is provided an exhaust system for an internal combustion engine, the exhaust system comprising: at least one cylinder head defining a first integrated exhaust manifold and a second integrated exhaust manifold; a first aftertreatment component in fluid communication with both the first integrated exhaust manifold and the second integrated exhaust manifold; and a second aftertreatment component configured to enable a flow of gases from the first integrated exhaust manifold through the second aftertreatment component to the first aftertreatment component.

This provides the advantage that the second aftertreatment component is able to warm up rapidly to its operating temperature, because the area of internal surfaces on a passage between the cylinders of an engine and the second aftertreatment component may be made smaller by the use of the first integrated exhaust manifold, instead of an external manifold. In addition, the cylinder head may be provided with a coolant passage to keep the cylinder head relatively cool at times when the engine is producing relatively large quantities of power, and consequently the exhaust gases may be kept relatively cool without varying the fuel to air ratio from a stoichiometric ratio.

According to another aspect of the invention there is provided an exhaust system for an internal combustion engine, the exhaust system comprising: at least one cylinder head defining at least a first integrated exhaust manifold defining a first outlet port and a second outlet port; a first aftertreatment component in fluid communication with both the first outlet port and the second outlet port; and a second aftertreatment component configured to enable a flow of gases from the first outlet port through the second aftertreatment component to the first aftertreatment component. Optionally, the first integrated exhaust manifold defines the first outlet port and the second outlet port.

Optionally, the exhaust system comprises a first turbine housing configured to enable a flow of gases from the first integrated exhaust manifold through the first turbine housing to the first aftertreatment component.

Optionally, the first turbine housing is configured to enable a flow of gases from the first integrated exhaust manifold through the first turbine housing to the second aftertreatment component.

Optionally, the first turbine housing is the housing of a turbocharger, and the turbocharger is a mono-scroll turbocharger or a variable geometry turbocharger. This provides the advantage that the turbocharger causes less cooling of exhaust gases than if it were a twin-scroll turbocharger.

Optionally, the exhaust system comprises a second turbine housing configured to enable a flow of gases from the second integrated exhaust manifold through the second turbine housing to the first aftertreatment component.

Optionally, the cylinder head is configured to form a part of an inline cylinder engine.

Optionally, the second aftertreatment component and the first aftertreatment component are three-way catalytic converters.

Optionally, the first integrated exhaust manifold is configured to enable gases to be exhausted from a first group of cylinders and the second integrated exhaust manifold is configured to enable gases to be exhausted from a second group of cylinders, each of the cylinders of the second group being different to each of the cylinders of the first group.

Optionally, the exhaust system comprises a duct configured to enable a flow of gases from the second integrated exhaust manifold through the duct and through the first aftertreatment component without passing through the second aftertreatment component and any other catalytic converter. This provides the advantage that, while the second aftertreatment component may be caused to warm up more rapidly by deactivating the cylinders connected to the second integrated exhaust manifold, the exhaust system only requires two aftertreatment components, i.e. the second aftertreatment component, primarily provided for use during a warm up period, and the first aftertreatment component that is arranged to receive exhaust gases from all cylinders after the warm up period.

Optionally, the first group of cylinders comprises a first number of cylinders; the second group of cylinders comprises a second number of cylinders; and the first number is greater than or equal to the second number.

Optionally, the first number is four and the second number is two.

Optionally, the first group of cylinders comprises a first number of cylinders; the second group of cylinders comprises a second number of cylinders; and the first number is equal to the second number.

Optionally, the exhaust system comprises a third aftertreatment component configured to enable a flow of gases from the second integrated exhaust manifold through the third aftertreatment component to the first aftertreatment component. This provides the advantage that all cylinders may be used during a warm-up period immediately following starting of the engine. The second and third aftertreatment components may be arranged to warm up relatively rapidly and then convert noxious gases to less harmful ones, while the first aftertreatment component warms up to its operating temperature.

According to another aspect of the invention there is provided a vehicle comprising: an exhaust system according to any one of the previous paragraphs.

A vehicle comprising: an exhaust system according to any one of the previous paragraphs; an internal combustion engine comprising a first group of cylinders configured to exhaust gases through the first integrated exhaust manifold, and a second group of cylinders configured to exhaust gases through the second integrated exhaust manifold; and a control means configured to cause fuel injection and ignition in the first group of cylinders during a warm-up period and deactivate the second group of cylinders during the warm-up period. This provides the advantage that during the warm-up period after starting the engine, the first group of cylinders connected to the first integrated exhaust manifold are made to generate more power than they would do if all cylinders were operational. Consequently, heat is transported to the second aftertreatment component at a higher rate than it would be if all cylinders were operational, and so the second aftertreatment component is caused to warm up more rapidly.

Optionally, the internal combustion engine comprises an active intake valve actuation system configured to enable intake valves of the second group of cylinders to remain closed during the warm-up period. This provides the advantage that during operation of the engine, air may be prevented from being pumped through the second group of cylinders and so oxidation of the first aftertreatment component may be avoided.

According to a further aspect of the invention there is provided a method of operating an internal combustion engine comprising the exhaust system of any one of the previous paragraphs, the method comprising: causing fuel injection and ignition in the first group of cylinders during a warm-up period; and deactivating the second group of cylinders during the warm-up period. This provides the advantage that the second aftertreatment component is caused to warm up more rapidly than it would do if all cylinders were operational.

Optionally, said deactivating the second group of cylinders comprises causing intake valves of the second group of cylinders to remain closed. This provides the advantage that air is prevented from being pumped through the second group of cylinders and oxidation of the first aftertreatment component is avoided.

According to a further aspect of the invention there is provided a method of operating an internal combustion engine comprising a first group of cylinders and a second group of cylinders, the method comprising: deactivating the second group of cylinders during a warm-up period while causing fuel injection and ignition in the first group of cylinders so that gases exhausted from the first group of cylinders pass through a second aftertreatment component to a first aftertreatment component; and after the warm-up period, causing fuel injection and ignition in all of the cylinders of the engine so that gases exhausted from all of the cylinders pass through the first aftertreatment component. This provides the advantage that the second aftertreatment component is caused to warm up more rapidly than it would do if all cylinders were operational.

According to yet another aspect of the invention there is provided non-transitory computer readable medium comprising computer readable instructions that, when executed by a processor, cause performance of a method according to any one of the previous paragraphs.

According to yet a further aspect of the invention there is provided an exhaust system for an internal combustion engine comprising a first group of cylinders and a second group of cylinders, the exhaust system comprising: a first exhaust manifold to enable gases to be exhausted from the first group of cylinders; a second exhaust manifold to enable gases to be exhausted from the second group of cylinders; a first aftertreatment component in fluid communication with the first exhaust manifold and the second exhaust manifold; a second aftertreatment component configured to enable a flow of fluid from the first exhaust manifold through the second aftertreatment component to the first aftertreatment component; and a duct configured to enable a flow of fluid from the second exhaust manifold through the duct and through the first aftertreatment component without passing through the second aftertreatment component and without passing through any other aftertreatment component. This provides the advantage that, while the second aftertreatment component may be caused to warm up more rapidly by deactivating the cylinders connected to the second exhaust manifold, the exhaust system only requires two aftertreatment components, i.e. the second aftertreatment component, primarily for use during a warm up period, and the first aftertreatment component that is arranged to receive exhaust gases from all cylinders after the warm up period.

The exhaust system may be for a road vehicle such as a car.

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 is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, 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 shows a schematic plan view of a vehicle embodying the present invention; Fig. 2 shows a schematic diagram of a plan view of an engine and a front portion of an exhaust system embodying the present invention; Fig. 3 shows a schematic diagram of a plan view of an engine and a front portion of an alternative exhaust system embodying the present invention; Fig. 4 shows a schematic diagram of one of the cylinders of the engine of Fig. 3 and mechanisms by which an intake valve and an exhaust valve of the cylinder are actuated; Fig. 5 shows a flowchart illustrating a method of operating an internal combustion engine, which embodies the present invention; Fig. 6 shows a flowchart illustrating a method of operating an internal combustion engine that provides a specific example of the method of Fig. 5; Fig. 7 shows a schematic diagram of plan view of another alternative engine and a front portion of an exhaust system embodying the present invention; and Fig. 8 shows a schematic diagram of a plan view of yet another alternative engine and a front portion of an exhaust system embodying the present invention.

DETAILED DESCRIPTION

A vehicle 101, an exhaust system 104 and a method in accordance with embodiments of the present invention are described herein with reference to the accompanying Figs. 1 to 7.

With reference to Fig. 1, in which the vehicle 101 is shown in a schematic plan view, the vehicle 101 is a road vehicle in the form of a car having four road wheels 102. The vehicle 101 comprises an internal combustion engine 103 (referred to below as the engine 103), which provides torque for driving at least two of the road wheels 102, and an exhaust system 104 configured to receive exhaust gases from the engine 103. The exhaust system 104 is configured to provide aftertreatment to the exhaust gases and release the treated exhaust gases to the atmosphere.

An intake manifold 105 provides air to the engine 103 for the purposes of combustion. The intake manifold is provided with: a temperature sensor 106 for measuring the temperature of air provided through the intake manifold; and a pressure sensor 107 for measuring air pressure within the intake manifold 105 to enable rate of mass of air flowing into the engine 103 to be determined. Further sensors, such as an engine temperature sensor 108 and a crankshaft position sensor 109, may be included within the engine 103 to enabling monitoring and control of the operation of the engine 103 and/or the exhaust system 104.

A plan view of the engine 103 and a front portion of the exhaust system 104 is shown in a schematic diagram in Fig. 2. The engine 103 comprises a plurality of cylinders 201 (in the present embodiment 6 cylinders 201A, 201 B, 201 C, 201 D, 201E and 201 F). A cylinder head 202 covers one end of the cylinders 201 and for each cylinder 201 the cylinder head 202 includes at least one intake port 203, at least one exhaust port 204, a sparkplug 205 and a fuel injector 206. (It may be noted that the intake port 203, exhaust port 204, sparkplug 205 and fuel injector 206 have only been labelled for the first cylinder 201A, but all six cylinders 201 comprise these features.) The engine 103 includes a valve train 207 comprising a plurality of intake valves (not shown in Fig. 2), so that each intake port 203 is provided with an intake valve that is moveable to open or close its corresponding intake port 203 during operation of the engine 103. The exhaust ports 204 are similarly provided with exhaust valves (not shown in Fig. 2) for opening and closing the exhaust ports 204.

The valve train 207 may comprise a conventional arrangement in which the intake valves are operatively connected to a crankshaft (not shown) of the engine 104 by a mechanical and/or hydraulic system, so that the valves are arranged to be opened and closed at times that are set by the rotational position of the crankshaft. Alternatively, the valve train 207 may comprise a variable valve lift arrangement that enables the timing of the opening and closing of the intake valves and/or the height of lift of the intake valves to be adjusted by an electronic control system.

The cylinder head 202 defines two integrated exhaust manifolds 208A and 208B, referred to below as the first IEM 208A and the second IEM 208B, or the IEMs 208A and 208B. The first IEM 208A connects the exhaust ports 204 of three cylinders 201A, 210B and 201C to a first outlet port 209A and the second IEM 208B connects the exhaust ports 204 of the other three cylinders 201 D, 201E and 201 F to a second outlet port 209B. The cylinder head 202 also defines a coolant passage 220, which forms a part of an engine cooling system, in which a liquid coolant is arranged to flow. During operation of the engine 103, exhaust gases flowing through the IEMs 208A and 208B provide heat to the cylinder head 202, but the liquid coolant in the coolant passage 220 transports heat away from the cylinder head 202 to prevent its overheating.

The outlet ports 209A and 209B of the IEMs 208A and 208B are connected directly to the remainder of the exhaust system 104, which includes a first aftertreatment component 210. The exhaust system 104 is configured such that both the first IEM 208A and the second IEM 208B are in fluid communication with the first aftertreatment component 210.

The exhaust system 104 also comprises a second aftertreatment component 211 that is arranged to enable exhaust gases flowing from the first outlet port 209A of the first IEM 208A through the second aftertreatment component 211 to the first aftertreatment component 210.

Similarly, the exhaust system 104 comprises a third aftertreatment component 212 arranged to enable exhaust gases flowing from the second outlet port 209B of the second IEM 208B through the third aftertreatment component 212 to the first aftertreatment component 210.

In the present embodiment, an exhaust pipe manifold 213 is configured to receive exhaust gases from both the second aftertreatment component 211 and the third aftertreatment component 212 and provide the exhaust gases to a single inlet port 214 of the first aftertreatment component 210. However, in alternative embodiments the first aftertreatment component 210 comprises two inlet ports, each one being connected to a respective one of the second and third aftertreatment components 211 and 212 by a pipe.

In the present embodiment, the exhaust system 104 comprises a first turbine housing 215 configured to enable a flow of gases from the first IEM 208A through the first turbine housing 215 to the second aftertreatment component 211 and through the second aftertreatment component 211 to the first aftertreatment component 210. Similarly, a second turbine housing 216 is configured to enable a flow of gases from the second IEM 208B through the second turbine housing 216 to the third aftertreatment component 212 and through the third aftertreatment component 212 to the first aftertreatment component 210. In some alternative embodiments, that do not include a turbocharger, the second aftertreatment component 211 is connected directly to the first outlet port 209A of the first IEM 208A and similarly the third aftertreatment component 212 is connected directly to the second outlet port 209B of the second IEM 208B Each of the three aftertreatment components 210, 211 and 212 is a catalytic converter, and in the present embodiment, each of the catalytic converters comprises a three-way catalytic converter. The first aftertreatment component 210 has a larger capacity than either of the second aftertreatment component 211 or the third aftertreatment component 212, and the first aftertreatment component 210 may therefore be regarded as the main catalytic converter.

During operation of the engine 103, heat from the exhaust gases raises the temperature of the aftertreatment components 210, 211 and 212 and when they reach their operating temperature, i.e. a "light-off" temperature, they will efficiently convert nitrogen oxides, carbon monoxide, unburnt hydrocarbons and oxygen to nitrogen, carbon dioxide and water. When the engine 103 is first started from cold, the aftertreatment components 210, 211 and 212 do not function as required, but the present arrangement enables the aftertreatment components 210, 211 and 212 to warm up while keeping down the quantity of untreated exhaust gases that are released to atmosphere.

Due to their smaller capacity, the second and third aftertreatment components 211 and 212 are able to be located next to the turbine housings 215 and 216 and close to the outlet ports 209A and 209B of the IEMS 208A and 209B. This compact arrangement results in relatively little heat being lost by the exhaust gases as they travel between the cylinders 201 of the engine 103 and the second and third aftertreatment components 211 and 212. Furthermore, the use of IEM5 208A and 208B also causes less heat loss by the exhaust gases when compared to a similar arrangement that employs cast iron external exhaust manifolds. This is because, although the IEM5 208A and 208B are cooled by coolant flowing through coolant passage 220, the surface area of the cold inner surfaces of the IEMS 208A and 208B is relatively small in comparison to the surface area of the inner surfaces of a system employing an external manifold. In such a system, the exhaust gases not only have to travel through the external manifold before reaching the aftertreatment components but also have to pass through channels in the cylinder head, all of which is initially cold.

The relatively low heat loss by the exhaust gases during an initial warm-up period of the engine 103 assists the second and third aftertreatment components 211 and 212 to warm up rapidly and so the time taken to reach their light-off temperatures is relatively small. Having reached their operating temperature, the second and third aftertreatment components 211 and 212 are capable of converting exhaust gases as required, while the first aftertreatment component 210 continues to warm up to its operating temperature.

In the present embodiment, the specifications of the second and third aftertreatment components 211 and 212 are chosen to provide a required level of efficiency over a period in which the first aftertreatment component 210 is able to warm up from cold to its operating temperature. In order to provide sufficient functionality while the first aftertreatment component 210 warms up, the loading of precious metals within the second and third aftertreatment components 211 and 212 may be relatively high compared to the first aftertreatment component 210 to facilitate light-off. When the first aftertreatment component 210 is at its operating temperature, the process of converting the exhaust gases is then performed by all three of the aftertreatment components 210, 211 and 212.

The first turbine housing 215 is the housing of a first turbocharger 217. In the present embodiment the first turbocharger 217 is a variable geometry turbocharger but in alternative embodiments the first turbocharger 217 is a mono-scroll turbocharger. Similarly, the second turbine housing 216 is the housing of a second turbocharger 218, which is a variable geometry turbocharger but in alternative embodiments is a mono-scroll turbocharger. The use of variable geometry turbocharges enables the gas leakage through the turbine to be minimised by closing its vanes, and therefore heat transfer to the catalyst face of the aftertreatment component 211 is increased. In embodiments in which mono-scroll turbochargers are used, this provides an advantage over a twin-scroll turbocharger, in that a mono-scroll presents a smaller surface area to the exhaust gases as they flow through, and so they cause less heat to be lost from the exhaust gases. The choice of a variable geometry turbocharger, or a mono-scroll turbocharger, therefore assists the process of rapidly heating up the aftertreatment components 210, 211 and 212 from a cold start.

At times when the engine 103 is generating a relatively high power, for example when the vehicle 101 is travelling at high speed, the exhaust gases carry heat from the cylinders 201 of the engine 103 at a relatively high rate. However, it is not necessary to enrich the fuel-air mixture to reduce exhaust temperatures in such conditions, and a stoichiometric fuel-air mixture may be maintained, because sufficient heat may be extracted from the exhaust gases by the coolant cooled IEMs 208A and 208B. In some embodiments, the turbine housings 215 and 216 are also cooled to provide them with further protection.

In some embodiments, the first aftertreatment component 210 may be provided with electric heating coils 219 adjacent to its inlet port 214, through which an electric current may be passed while the first aftertreatment component 210 is warming up, in order to reduce the time it takes to reach its operating temperature.

In the embodiment of Fig. 2, the engine 103 is an inline (or straight) engine but in alternative embodiments, the engine may be a V engine or a flat engine, in which the engine has two cylinder heads, each defining one of the IEMs 208A and 208B.

In an alternative embodiment, which is shown in Fig. 8, the engine 103 has a single cylinder head that defines a single IEM 208A having two outlet ports 209A and 209B; the second aftertreatment component 215 is arranged to receive exhaust gases from the first outlet port 209A and the third aftertreatment component 216 is arranged to receive exhaust gases from the second outlet port 209B. Otherwise the embodiment of Fig. 8 is like that of Fig. 2, and its features have been provided with the same reference signs in Fig. 8 as those described above with reference to Fig. 2.

A plan view of an alternative engine 103A and a front portion of an exhaust system 104A for the vehicle 101 is shown in a schematic diagram in Fig. 3. The engine 103A may be similarly configured to the engine 103 of Fig. 2, and the features of the engine 103A have been provided with the same reference signs as those of the engine 103. Thus, the engine 103A has a plurality or cylinders 201, each having at least one intake port 203, at least one exhaust port 204, a sparkplug 205 and a fuel injector 206.

The engine 103A has a cylinder head 202 that comprises two IEMs 208A and 208B, each of which are arranged to receive exhaust gases from a different group of the cylinders 201. In the present embodiment, the engine 103 has a single bank of six cylinders 201A, 201 B, 201C, 201 D, 201E and 201 F and a first group of three of the cylinders 201 A, 201 B and 201 C exhaust gases through the first IEM 208A while a second group of cylinders 201 D, 201E and 201 F exhaust gases through the second IEM 208B. The cylinder head 202 also defines a coolant passage 220, positioned next to the IEMS 208A and 208B, and which forms a part of an engine cooling system, in which a liquid coolant is arranged to flow.

The engine 103A includes a valve train 207A comprising a plurality of intake valves (not shown in Fig. 3), so that each intake port 203 is provided with an intake valve that is moveable to open and close its corresponding intake port 203 during operation of the engine 103A. The exhaust ports 204 are similarly provided with exhaust valves (not shown in Fig. 3) for opening and closing the exhaust ports 204. The valve train 207A comprises an active intake valve actuation system configured to enable the intake valves of the second group of cylinders 201 D, 201E and 201F to remain closed during operation of the engine 103A while the intake valves of the first group of cylinders 201A, 201B and 201C are operated normally. The valve train 207A may comprise a continuous variable valve lift system that enables the height of lift of the intake valves to be adjusted to various heights, or it may be a simpler variable valve lift system that enables only discrete variation of valve lift, including no valve lift at all.

The vehicle 101 also comprises a control means, in the form of an engine control unit (ECU) 301, that is configured to control operation of the engine 103A. The ECU 301 has input/output means 302 to enable it to communicate with other components of the vehicle 101. The input/output means 302 may comprise a transceiver for providing communication to and from the ECU 301 over a data bus of the vehicle 101.

For example, the ECU is configured to provide output signals to control: fuel injection by the injectors 206; air intake into the cylinders 201, by opening of the intake valves; and ignition by the sparkplugs 205 to cause combustion within the cylinders 201. The ECU 301 is also configured to receive signals from a sensor (109 shown in Fig.1) of the engine 104A that are indicative of the position of the crankshaft of the engine 103A to enable timing of the fuel injection, air intake and ignition to correspond with determined positions of the pistons of the cylinders 201.

Each of the IEM5 208A and 208B has an outlet port 209A and 209B connected to the remainder of the exhaust system 104A, which includes a first aftertreatment component 210, and the exhaust system 104A is configured such that both the first IEM 208A and the second IEM 208B are in fluid communication with the first aftertreatment component 210.

The exhaust system 104A also comprises a second aftertreatment component 211 that is arranged to enable exhaust gases flowing from the first outlet port 209A of the first IEM 208A through the second aftertreatment component 211 to the first aftertreatment component 210. In some alternative embodiments, the exhaust system 104A also comprises a third aftertreatment component (like aftertreatment component 212 of Fig. 2) arranged to enable exhaust gases flowing from the second outlet port 209B of the second IEM 208B through the third aftertreatment component 212 to the first aftertreatment component 210. However, in the embodiment of Fig. 3, the exhaust system 104A does not include such a third aftertreatment component, i.e. the exhaust system 104A is configured so that exhaust gases exiting the second IEM 208B through outlet port 209B do not pass through any other aftertreatment component before entering the first aftertreatment component 210.

In the present embodiment, the exhaust system 104A includes a first turbine housing 215 that is positioned to receive exhaust gases from the first IEM 208A and a second turbine housing 216 that is positioned to receive exhaust gases from the second IEM 208B. The second aftertreatment component 211 is positioned to receive exhaust gases from the first turbine housing 215. An exhaust pipe manifold 213 is configured to receive exhaust gases from both the second aftertreatment component 211 and the second turbine housing 216 and provide the exhaust gases to a single inlet port 214 of the first aftertreatment component 210. The exhaust pipe manifold 213 therefore provides a duct 306 to enable a flow of exhaust gases from the second IEM 208B through the duct 306 and through the first aftertreatment component 210 without passing through any other aftertreatment component. In alternative embodiments, the first aftertreatment component 210 has two inlet ports; a first inlet port connected by a first pipe to the second aftertreatment component 211 and a second inlet port connected by a second pipe to the second turbine housing 216. The second pipe therefore provides a duct 306 to enable a flow of exhaust gases from the second IEM 208B through the duct 306 and through the first aftertreatment component 210 without passing through any other aftertreatment component.

During normal operation of the engine 103A and the exhaust system 104A, when the aftertreatment components 210 and 211 are both up to their operational temperatures, the ECU 301 controls the engine 103A to cause all six cylinders 201 to be operational, and the exhaust gases are treated by the two aftertreatment components 210 and 211. However, when the engine 103A is first started from cold, the ECU 301 is configured to: provide the necessary output signals to cause fuel injection, air intake and ignition in the first group of cylinders 201 A, 201B and 201C; and prevent combustion in the second group of cylinders 201D, 201E and 201 F, by preventing fuel injection, air intake and ignition in those cylinders. Consequently, the three cylinders 201A, 201B and 201C are caused to produce twice the power that they would do if all six cylinders 201 were operational, and so the second aftertreatment component 211 receives exhaust gases at twice the rate, for a given amount of torque produced by the engine 103A, than it would do if all six cylinders 201 were operational. As a result, increased enthalpy is provided to the aftertreatment component 211, which is heated up to its operational temperature (i.e. its light-off temperature) more rapidly than it would be if all six cylinders 201 were operational, and therefore efficient catalytic conversion of the exhaust gases by the second aftertreatment component 211 occurs sooner.

For a period of time after starting, the engine 103A continues to be operated using only the first group of cylinders 201 A, 201 B and 201 C while the first aftertreatment component 210 is warmed up to its operational temperature. It may be noted that during this warm-up period, the intake ports 203 of the second group of cylinders 201 D, 201E and 201 F are kept closed and therefore air is prevented from passing through those cylinders to the first aftertreatment component 210. Therefore, the first aftertreatment component 210 is protected from oxidation and cooling that would otherwise occur. After that warm-up period, when the first aftertreatment component 210 is up to its operational temperature, the ECU 301 causes combustion to begin in the second group of cylinders 201 D, 201E and 201 F as well as the first group of cylinders 201A, 201 B and 201 C, and the engine 103A is then operated normally.

To determine when the warm-up period is completed, the temperature of the first aftertreatment component 210 may be determined from a computer model within the ECU 301 based on the temperature of the air received by the engine 104A, the flow rate of air into the engine 104A and the rate of fuel combusted by the engine 104A.

In an alternative embodiment to that of Fig. 3, the exhaust system 1048 comprises two exhaust manifolds that are external to the cylinder head 202. The cylinder head 202 comprises a plurality of passageways having an exhaust port 204 at one end and an outlet port at its other end, so that each passageway provides fluid communication between just one of the cylinders 201 and one of the outlet ports. One of the exhaust manifolds is configured to receive exhaust gases from the first group of cylinders 201A, 201B and 201C and provide them to the first turbocharger 217, and the other one of the exhaust manifolds is configured to receive exhaust gases from the second group of cylinders 201D, 201E and 201F and provide them to the second turbocharger 218.

Details of the valve train 207A are illustrated in Fig. 4, which shows one of the cylinders 201 F of the engine 103A containing a piston 401. Fig. 4 also shows the mechanisms by which an intake valve 402 and an exhaust valve 403 of the cylinder 201 F are actuated. It should be understood that although only one cylinder 201 F with one intake valve 402 is illustrated in Fig. 4, intake valves 402 of the other cylinders 201 may be actuated in a similar manner. The arrangement of Fig. 4 may also be employed in the embodiment of Fig. 2.

In the embodiment of Fig. 4, the valve train 207A comprises a hydraulic system of a known type which is arranged to actuate only the intake valves 402 of the engine 103A. The exhaust valves 403 are actuated by direct mechanical interaction with a cam 404 on a camshaft 405, but in an alternative embodiment, the exhaust valves 403 may be actuated by a variable valve lift (VVL) system in a similar manner to the intake valves 402. In such an alternative embodiment, the exhaust valves 403 of the cylinders 201 D, 201E and 201 F may be kept shut during the warm-up period, as well as, or instead of the corresponding intake valves.

The valve train 207A comprises a cam follower 406, which is arranged to be actuated by a cam 407 located on a camshaft 408 of the engine 103A. When actuated, the cam follower 406 actuates a piston 409 in a master cylinder 410 of the hydraulic system. The master cylinder 410 is hydraulically connectable via a solenoid valve 411 to a reservoir means 412 and a slave cylinder 413, which contains a piston 414. In the present embodiment, the solenoid valve 411 is biased so that connection is normally provided between the master cylinder 410 and the slave cylinder 413, while the reservoir means 412 is isolated from the master cylinder 410, and when the solenoid valve 411 is actuated, in response to a signal from the ECU 301, the master cylinder 410 is connected to the reservoir means 412 and isolated from the slave cylinder 413.

The piston 414 of the slave cylinder 413 is arranged to actuate the intake valve 402. When the intake valve 402 is actuated, as illustrated in Fig. 4, the intake valve 402 is displaced from the intake port 203 of the cylinder 201 F to allow air to be drawn into the cylinder.

During normal operation of the engine 103A, the solenoid valve 411 provides connection between the master cylinder 410 and the slave cylinder 413, at least for a part of the period in which the cam 407 actuates the piston 409 of the master cylinder 410, during the intake stroke of the piston 401. Consequently, the piston 414 of the slave cylinder 413 is hydraulically actuated and pushes the intake valve 402 to an open position, as shown in Fig. 4. As the cam 407 is further rotated, it releases its pressure applied to the piston 409, allowing hydraulic fluid to return to the master cylinder 410 and allowing the intake valve 402 to return to a closed position in which it closes the intake port 203.

However, in response to a signal from the ECU 301, the solenoid valve 411 may be moved to connect the master cylinder 410 to the reservoir means 412 during the whole of the intake stroke of the piston 401, so that actuation of the piston 409 in the master cylinder 410 cannot cause actuation of the piston 414 in the slave cylinder 413. Consequently, the intake valve 402 remains in the closed position, so that no air is able to enter the cylinder 201 F through the intake port 415 during the whole of the intake stroke.

As illustrated in Fig. 4, a fuel injector 206 is positioned to provide an injection of fuel directly into the cylinder 201 F, and the spark plug 205, is provided to ignite fuel and air mixtures present within the cylinder 201 F. In alternative embodiments, the valve train 207A may comprise another type of variable valve lift system capable of enabling the intake valves 402 to remain closed during operation of the engine 103A. For example, such a system may comprise an electrical system in which solenoids or electric motors are arranged to actuate the intake valves 402 of the engine 103A directly.

As illustrated in Fig. 3, the ECU 301 may comprise at least one electronic processor 303 and at least one electronic memory device 304 which stores instructions 305. The at least one electronic processor 303 is configured to access the instructions 305 stored in the at least one electronic memory device 304 and execute the instructions 305 so that it becomes operable to perform the functions of ECU 301 as described above and as described below with reference to Fig. 5 and 6. It should be noted that although the above description describes the control means 301 as an electronic control unit, it will be appreciated that the functions provided by the ECU 301 may be distributed over several different controllers or control units.

A flowchart illustrating a method 500 of operating an internal combustion engine 103A performable by the ECU 301 and embodying the present invention is shown in Fig. 5. The method 500 is for use in operating an internal combustion engine 103A in which a first group of cylinders 201A, 201B and 201C exhaust gases through a first aftertreatment component 210 via a second aftertreatment component 211, and a second group of cylinders 201 D, 201 E and 201F exhaust gases via the first aftertreatment component 210, but not the second aftertreatment component 211. At block 501 of the method 500, the second group of cylinders 201 are deactivated during a warm-up period, fuel is caused to be injected in the first group of cylinders and a fuel and air mixture in the first group of cylinders is caused to be ignited, so that gases exhausted from the first group of cylinders pass through the second aftertreatment component 211 to the first aftertreatment component 210. As mentioned above, because all of the work done by the engine 103A is performed by the first group of cylinders 201A, 201B and 201C and the exhaust gases pass through the second aftertreatment component 211, this enables the second aftertreatment component 211 to warm up relatively quickly. Therefore, after a short initial part of the warm-up period of the first aftertreatment component 210, the second aftertreatment component 211 is able to efficiently convert exhaust gases while the first aftertreatment component 210 continues to warm up.

At block 502, after the warm-up period, fuel is caused to be injected and ignition of a fuel and air mixture is caused to be ignited in all of the cylinders of the engine 103A, so that the gases exhausted from all of the cylinders 201 pass through the first aftertreatment component 210.

Thus, at block 502, the engine 103A is operated normally.

A flowchart illustrating a method 600 that provides a specific example of the method 500 is shown in Fig. 6. At block 601 of the method 600, fuel is caused to be injected into, and ignition of a fuel and air mixture is caused to be ignited in, a first group of cylinders of an engine 103A, so that gases exhausted from those cylinders pass through a first aftertreatment component 210 via a second aftertreatment component 211. While the first group of cylinders are operated in this way, a second group of cylinders are maintained in an inactive state by keeping closed their intake valves and/or their exhaust valves and by preventing injection of fuel into them.

At block 602 it is determined whether or not the first aftertreatment component 210 has reached its operating temperature (i.e. "light-off" temperature). This process may comprise estimating the temperature within the first aftertreatment component 210 by running a computer model which depends on values received from one or more sensors positioned on the engine 103A and/or the exhaust system 104A.

If it is determined at block 602 that the light-off temperature has not been reached, then the process at block 601 is repeated, otherwise the process at block 603 is performed. At block 603, fuel is caused to be injected and ignition of a fuel and air mixture is caused to be ignited in all of the cylinders 201 of the engine 103A, so that the gases exhausted from all of the cylinders 201 pass through the first aftertreatment component 210.

A plan view of another alternative engine 103B and a front portion of an exhaust system 104B for the vehicle 101 is shown in a schematic diagram in Fig. 7. The engine 103B and exhaust system 104B has many features in common with the engine 103A and exhaust system 104A, and those features have been provided with the same reference signs. Thus, the engine 103B has 6 cylinders 201, each of which has at least one intake port 203, at least one exhaust port 204, at least one sparkplug 205 and a fuel injector 206.

The cylinder head 202A defines two IEMs 208C and 208D, which differ from those of the engine 103A in that the first IEM 208C connects the exhaust ports 204 of four cylinders 201A, 201 B, 201E and 201 F to its outlet port 209C, while the second IEM connects the exhaust ports of just two cylinders 201C and 201 D to its outlet port 209D. The outlet ports 209C and 209D of the IEMs 208C and 208D are connected to the remainder of the exhaust system 104B, which is similarly configured to the corresponding portion of exhaust system 104A. Thus, the exhaust system 104B is configured so that: the outlet ports 209C and 209D are in fluid communication with a first aftertreatment component 210; a first turbine housing 215, a second aftertreatment component 211 and an exhaust pipe manifold 213 provide fluid communication between the first outlet port 209C and the first aftertreatment component 210; and a second turbine housing 217 and the exhaust pipe manifold 213 provide fluid communication between the second outlet port 209D and the first aftertreatment component 210.

The engine 103B also has an associated ECU 301A which operates in a similar manner to ECU 301, in that during a warm-up period when the engine 103B is first started from cold, it causes only a first group of cylinders 201 to be activated, while cylinders 201 of a second group are kept deactivated. However, in this embodiment, the first group of cylinders, comprising cylinders 201A, 201B, 201E and 201F, contains a larger number, i.e. 4, than the second group of cylinders, which comprises only 2 cylinders 201C and 201 D. For purposes of this disclosure, it is to be understood that the control means or ECU described herein can comprise a single control unit or computational device having one or more electronic processors, or may comprise several control units or computational devices. A vehicle and/or a system thereof may comprise a single control unit or electronic controller or alternatively different functions of the control means/ECU may be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controller(s) or control unit(s) to implement the control techniques described herein (including the described method(s)). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software to be executed by one or more electronic processor(s). For example, a first controller may be implemented in software run on one or more electronic processors, and one or more other controllers may also be implemented in software run on one or more electronic processors, optionally the same one or more processors as the first controller. It will be appreciated, however, that other arrangements are also useful, and therefore, the present disclosure is not intended to be limited to any particular arrangement. In any event, the set of instructions described above may be embedded in a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, 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 and EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

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 the Figs. 5 and 6 may represent steps in a method and/or sections of code in the computer program 305. 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 endeavoring 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 an internal combustion engine, the exhaust system comprising: at least one cylinder head defining a first integrated exhaust manifold and a second integrated exhaust manifold; a first aftertreatment component in fluid communication with both the first integrated exhaust manifold and the second integrated exhaust manifold; and a second aftertreatment component configured to enable a flow of gases from the first integrated exhaust manifold through the second aftertreatment component to the first aftertreatment component.
2. An exhaust system according to claim 1, wherein the exhaust system comprises a first turbine housing configured to enable a flow of gases from the first integrated exhaust manifold through the first turbine housing to the first aftertreatment component.
3. An exhaust system according to claim 2, wherein the first turbine housing is configured to enable a flow of gases from the first integrated exhaust manifold through the first turbine housing to the second aftertreatment component.
4. An exhaust system according to claim 2 or claim 3, wherein the first turbine housing is the housing of a turbocharger, and the turbocharger is a mono-scroll turbocharger or a variable geometry turbocharger.
5. An exhaust system according to any one of claims 2 to 4, wherein the exhaust system comprises a second turbine housing configured to enable a flow of gases from the second integrated exhaust manifold through the second turbine housing to the first aftertreatment component.
6. An exhaust system according to any one of claims 1 to 5, wherein the cylinder head is configured to form a part of an inline cylinder engine.
7. An exhaust system according to any one of claims 1 to 6, wherein the second aftertreatment component and the first aftertreatment component are three-way catalytic converters.
8. An exhaust system according to any one of claims 1 to 7, wherein the first integrated exhaust manifold and the second integrated exhaust manifold are defined within a single cylinder head.
9. An exhaust system according to any one of claims 1 to 8, wherein the first integrated exhaust manifold is configured to enable gases to be exhausted from a first group of cylinders and the second integrated exhaust manifold is configured to enable gases to be exhausted from a second group of cylinders, each of the cylinders of the second group being different to each of the cylinders of the first group.
10. An exhaust system according to claim 9, wherein the exhaust system comprises a duct configured to enable a flow of gases from the second integrated exhaust manifold through the duct and through the first aftertreatment component without passing through the second aftertreatment component and any other catalytic converter.
11. An exhaust system according to claim 9 or claim 10, wherein the first group of cylinders comprises a first number of cylinders; the second group of cylinders comprises a second number of cylinders; and the first number is greater than or equal to the second number.
12. An exhaust system according to claim 11, wherein the first number is four and the second number is two.
13. An exhaust system according to claim 9 or claim 10, wherein the first group of cylinders comprises a first number of cylinders; the second group of cylinders comprises a second number of cylinders; and the first number is equal to the second number.
14. An exhaust system according to any one of claims 1 to 13, wherein the exhaust system comprises a third aftertreatment component configured to enable a flow of gases from the second integrated exhaust manifold through the third aftertreatment component to the first aftertreatment component.
15. A vehicle comprising: an exhaust system according to any one of claims 1 to 14.
16. A vehicle comprising: an exhaust system according to any one of claims 1 to 14; an internal combustion engine comprising a first group of cylinders configured to exhaust gases through the first integrated exhaust manifold, and a second group of cylinders configured to exhaust gases through the second integrated exhaust manifold; and a control means configured to cause fuel injection and ignition in the first group of cylinders during a warm-up period and deactivate the second group of cylinders during the warm-up period.
17. A vehicle according to claim 16, wherein the internal combustion engine comprises an active intake valve actuation system configured to enable intake valves of the second group of cylinders to remain closed during the warm-up period.
18. A method of operating an internal combustion engine comprising the exhaust system of any one of claims 9 to 13, the method comprising: causing fuel injection and ignition in the first group of cylinders during a warm-up period; and deactivating the second group of cylinders during the warm-up period.
19. A method according to claim 18, wherein said deactivating the second group of cylinders comprises causing intake valves of the second group of cylinders to remain closed. 20
20. A method of operating an internal combustion engine comprising a first group of cylinders and a second group of cylinders, the method comprising: deactivating the second group of cylinders during a warm-up period while causing fuel injection and ignition in the first group of cylinders so that gases exhausted from the first group of cylinders pass through a second aftertreatment component to a first aftertreatment component; and after the warm-up period, causing fuel injection and ignition in all of the cylinders of the engine so that gases exhausted from all of the cylinders pass through the first aftertreatment component.
21. A method according to claim 20, wherein said deactivating the second group of cylinders comprises causing intake valves of the second group of cylinders to remain closed.
22. A non-transitory computer readable medium comprising computer readable instructions that, when executed by a processor, cause performance of a method according to any one of claims 19 to 20.
23. An exhaust system for an internal combustion engine, the exhaust system comprising: at least one cylinder head defining at least a first integrated exhaust manifold defining a first outlet port and a second outlet port; a first aftertreatment component in fluid communication with both the first outlet port and the second outlet port; and a second aftertreatment component configured to enable a flow of gases from the first outlet port through the second aftertreatment component to the first aftertreatment component.
24. An exhaust system according to claim 23, wherein the first integrated exhaust manifold defines the first outlet port and the second outlet port.
25. An exhaust system for an internal combustion engine comprising a first group of cylinders and a second group of cylinders, the exhaust system comprising: a first exhaust manifold to enable gases to be exhausted from the first group of cylinders; a second exhaust manifold to enable gases to be exhausted from the second group of cylinders; a first aftertreatment component in fluid communication with the first exhaust manifold and the second exhaust manifold; a second aftertreatment component configured to enable a flow of fluid from the first exhaust manifold through the second aftertreatment component to the first aftertreatment component; and a duct configured to enable a flow of fluid from the second exhaust manifold through the duct and through the first aftertreatment component without passing through the second aftertreatment component and without passing through any other aftertreatment component.