WO2017216105A1

WO2017216105A1 - Vehicle exhaust system

Info

Publication number: WO2017216105A1
Application number: PCT/EP2017/064288
Authority: WO
Inventors: Dean PETLEY; Simon Fletcher; Stephen MITCHLEY; Jacob PILLINGER
Original assignee: Jaguar Land Rover Limited
Priority date: 2016-06-15
Filing date: 2017-06-12
Publication date: 2017-12-21
Also published as: DE112017003009T5; GB201709295D0; GB2553200B; GB2552060A; GB2553200A; GB201707611D0; GB2552060B; GB201610407D0

Abstract

A vehicle exhaust system for a vehicle, the vehicle exhaust system comprising a first assembly and a second assembly, the first and second assemblies together defining a channel for exhaust gases flowing through the vehicle exhaust system. The vehicle exhaust system further comprises a first flexible joint intermediate the first assembly and second assembly, the first flexible joint comprising a resiliently-biased sealing means having a first sealing surface and a second surface. The first assembly is physically separated from the second assembly by a gap, the sealing means being positioned within said gap such that the first sealing surface is in contact with the first assembly and the second sealing surface is in contact with the second assembly. The sealing means is configured to prevent the escape of the exhaust gases from the vehicle exhaust system. In use, the first assembly is fixable in position in the vehicle at at least one part of the first assembly that is remote from the first flexible joint and the second assembly is fixable in position in the vehicle at least one part of the second assembly that is remote from the first flexible joint. In this way, the at least one part of the first assembly and the at least one part of the second assembly can be substantially fixed in position relative to one another.

Description

VEHICLE EXHAUST SYSTEM

TECHNICAL FIELD The present disclosure relates to a vehicle exhaust system, and particularly, to a flexible joint for a vehicle exhaust system. Aspects of the invention relate to a vehicle exhaust system, to a vehicle comprising a vehicle exhaust system and to a method of preventing the escape of exhaust gases from a vehicle exhaust system. BACKGROUND

Vehicle exhaust systems are configured to control the flow and treatment of exhaust gases that are expelled from a vehicle engine, before the exhaust gases are released into the atmosphere. Vehicle exhaust systems typically comprise an exhaust manifold that is configured to collect exhaust gases from the engine and directs the gases into downstream components of the exhaust system. In particular, the exhaust manifold may be connected to a turbocharger assembly, which, in turn, is connected to a hot end of the exhaust system. Exhaust gases pass through the hot end of the exhaust system, before passing through a cold end of the exhaust system, and the gases are then expelled through an exhaust outlet. The hot end of the exhaust system typically comprises aftertreatment devices, such as a catalytic converter and associated piping.

Typically, the turbocharger assembly and the hot end of the exhaust system are connected by way of a v-band clamp, which is positioned so as to join a flange of the turbocharger assembly to a flange of an adjoining downstream pipe. The two flanges abut one another, and the v-band clamp is arranged in a c-shape around the outside of the flanges such that the flanges are sandwiched between two arms of the clamp. In this way, the v-band clamp draws the turbocharger assembly and the pipe together, compressing the two flanges against one another to prevent the escape of exhaust gases between the turbocharger assembly and the pipe.

In recent years, it has become an objective of vehicle manufacturers to reduce the weight of vehicle components, in order to reduce the use of raw materials and to improve fuel efficiency for environmental and economic benefit. Among others, it is an industry goal to apply lightweighting technologies to components of vehicle exhaust systems.

One way in which the weight of exhaust system components may readily be reduced is by down-gauging the materials used to manufacture the components, such that the walls of the finished components are thinner. While reducing the material gauge of the components of a vehicle exhaust system can lead to significant weight savings, this can also reduce the structural rigidity of the components. In the event that the material gauge of the turbocharger assembly and the adjoining downstream pipe is reduced, for example, the lower structural rigidity of the components may mean that the turbocharger assembly and the pipe are more susceptible to deformation while the vehicle is in use. In particular, stresses created by thermal variations in the components of the exhaust system and the surrounding assemblies may lead to undesirable bending or distortion of the turbocharger and the pipe.

There remains a need to provide a vehicle exhaust system having an improved connection between a turbocharger assembly and a downstream pipe. The present invention has been devised to mitigate or overcome at least some of the above- mentioned problems.

SUMMARY OF THE INVENTION

According to an aspect of the present invention there is provided a vehicle exhaust system for a vehicle, the vehicle exhaust system comprising a first assembly and a second assembly, the first and second assemblies together defining a channel for exhaust gases flowing through the vehicle exhaust system. The vehicle exhaust system further comprises a first flexible joint intermediate the first assembly and second assembly, the first flexible joint comprising a resiliently-biased sealing means having a first sealing surface and a second sealing surface. The first assembly is physically separated from the second assembly by a gap extending between the first assembly and the second assembly in an axial direction, the sealing means being positioned within said gap such that the first sealing surface is in contact with the first assembly, the second sealing surface is in contact with the second assembly and relative movement between the first and second assemblies in an axial direction is permitted, the sealing means being configured to prevent the escape of exhaust gases from the vehicle exhaust system. In use, the first assembly is fixable in position to at least one part of the vehicle at at least one part of the assembly that is remote from the first flexible joint and the second assembly is fixable in position to at least a part of the vehicle at at least one part of the assembly that is remote from the first flexible joint such that the at least one part of the first assembly and the at least one part of the second assembly are substantially fixed in position.

It will be understood that the first assembly and second assembly may be fixed to at least a part of the vehicle that is the same part of the vehicle or a different part of the vehicle as the other of the first assembly and/or second assembly.

An arrangement in which a flexible joint is positioned between a first and second assembly of a vehicle exhaust system allows for some relative movement between the two assemblies. The flexible joint thus permits some thermal expansion of components of the first and second assemblies, without the creation of undesirable stresses. In addition, such an arrangement advantageously reduces the transmission of vibrations between the first and second assemblies. Allowing the first and second assemblies to be fixable in position in a vehicle at respective parts of the first and second assemblies that are remote from the first flexible joint advantageously allows for these parts of the first and second assemblies to be accurately located relative to one another, such that a gap of appropriate dimensions exists between the first and second assemblies for accommodating the seal. In an example, he first assembly is configured such that the assembly is only fixed in position to at least one part of the vehicle at the at least one part of the assembly. This permits the first and second assemblies to move relative to one another in the region of the first flexible joint, such that any thermal expansions and/or vibrations in the components of the first assembly are not directly transmitted to the second assembly, and vice versa.

The second assembly may alternatively, or additionally, to the first assembly be configured such that the second assembly fixed in position to a part of the vehicle at at least one part of the second assembly that is remote from the first flexible joint. The sealing means may contact only the first assembly and the second assembly in the vehicle. In this way, the sealing means may be held in position only by virtue of the relative location of the parts of the first and second assemblies. Advantageously, this means that additional means for constraining the sealing means or for fixing the sealing means in position are not required, and the sealing means is free to deform and to absorb relative movements between the first and second assemblies at the first flexible joint. Advantageously, the sealing means may contact only a single component of each of the first and second assemblies only. Such an arrangement allows for ease of assembly of the first flexible joint.

Optionally, the first assembly is a turbocharger assembly. The second assembly may comprise an inlet to a hot end of the vehicle exhaust system, the pipe being positioned downstream of the first assembly in the direction of exhaust gas flow. Thermal variations and vibrations can be most apparent at an upstream end of the vehicle exhaust system, since this is where exhaust gases are at their highest temperature in the exhaust system. Positioning a first flexible joint adjacent to a turbocharger assembly and/or an inlet to a hot end of the vehicle exhaust system advantageously allows for such thermal variations and vibrations to be accommodated. The second assembly may be a catalytic converter assembly of the vehicle exhaust system.

In one embodiment, said gap may extend between the first assembly and the second assembly in an axial direction along the direction of exhaust gas flow. Such an arrangement permits relative movement between the first and second assemblies in an axial direction. The axial direction is defined as being a direction parallel to the longitudinal axis of the channel in the region of the sealing means. The entirety of the sealing means may be positioned within said gap. Such an arrangement allows for ease of assembly of the first flexible joint.

Advantageously, the sealing means may be a spring-biased sealing means. In an embodiment, the vehicle exhaust system comprises a second gap between the first assembly and the second assembly. The second gap may extend in an axial direction along the direction of exhaust gas flow and the second gap may be positioned radially outwards of the sealing means. The extension of the first and second assemblies radially outwards of the sealing means allows for the sealing means to be better protected in the vehicle exhaust system.

The first assembly and the second assembly may be arranged with axial overlap along the direction of exhaust gas flow. In an embodiment, an extension portion of the first assembly is arranged with axial overlap with an extension portion of the second assembly.

Optionally, the sealing means and the first assembly are arranged with axial overlap along the direction of exhaust gas flow. In this case, the sealing means may be positioned radially outwards of the extension portion of the first assembly with which the sealing means has axial overlap.

In an embodiment, the sealing means and the second assembly are arranged with axial overlap along the direction of exhaust gas flow. In this case, the sealing means may be positioned radially inwards of the extension portion of the second assembly, with which the sealing means has an axial overlap. The sealing means may be positioned between the extension portion of the first assembly and the extension portion of the second assembly. The sealing means may be a seal. In an embodiment, the seal may have a bellows configuration. For example, the seal may have a bellows configuration in radial cross- section. Advantageously, a seal having a bellows configuration is able to deform from an original shape under pressure, and to recover the original shape on release of that pressure.

In the event that the seal has a bellows configuration, the seal may have a radial cross-section comprising two or more opposed c-shaped portions connected to one another. In this case, the orientation of the c-shaped portions may alternate so that adjacent c-shaped portions are facing in opposed directions. Advantageously, the c-shaped portions at the first sealing surface and at the second sealing surface may be oriented such that the first and second sealing surfaces are compressed against the first assembly and the second assembly, respectively, by the exhaust gases flowing through the vehicle exhaust system, in use. In this case, the c- shaped portions may be oriented such that the exhaust gases flow into the c-shaped portions at the first sealing surface and at the second sealing surface. This assists in increasing the effectiveness of the seal between the first sealing surface and the first assembly, and between the second sealing surface and the second assembly.

The entirety of the first assembly may be physically separated from the entirety of the second assembly in a region defining the channel. The first assembly may be in contact with the second assembly elsewhere (i.e. other than in the channel region). Alternatively, the first assembly and the second assembly may be physically separated in their entirety.

Optionally, the sealing means forms a closed ring surrounding the channel. The sealing means may be in a state of compression. Advantageously, the first sealing surface of the sealing means thus applies pressure to the first assembly, and the second sealing surface of the sealing means applies pressure to the second assembly.

In one embodiment, the vehicle exhaust system further comprises a second flexible joint. The second flexible joint may be positioned intermediate the second assembly and a third assembly of the vehicle exhaust system, the third assembly being downstream of the second assembly in the direction of exhaust gas flow.

Optionally, the second flexible joint is positioned intermediate the catalytic converter assembly and a selective catalytic reduction assembly of the vehicle exhaust system.

According to another aspect of the invention, there is provided a method of preventing the escape of exhaust gases from a vehicle exhaust system, the method comprising the steps of arranging a first assembly and a second assembly such that the first assembly and second assembly together define a channel for the exhaust gases flowing through the vehicle exhaust system, and arranging a first flexible joint intermediate the first assembly and second assembly, the first flexible joint comprising a resiliently-biased sealing means having a first sealing surface and a second sealing surface. The method further comprises the steps of positioning the sealing means within a gap that physically separates the first assembly and the second assembly, such that the first sealing surface is in contact with the first assembly and the second sealing surface is in contact with the second assembly, and fixing the first assembly in position in the vehicle at at least one part of the first assembly that is remote from the first flexible joint and fixing the second assembly in position in the vehicle at at least one part of the second assembly that is remote from the first flexible joint, such that the at least one part of the first assembly and the at least one part of the second assembly are substantially fixed in position relative to one another. According to another aspect of the invention, there is provided a vehicle comprising a vehicle exhaust system in accordance with a previous aspect of the invention.

According to a further aspect of the invention, there is provided a vehicle exhaust system comprising an exhaust system component and a pipe, the exhaust system component and the pipe together defining a channel for exhaust gases flowing through the vehicle exhaust system. The vehicle exhaust system further comprises a resiliently-biased sealing means, having a first sealing surface and a second sealing surface, wherein the exhaust system component is physically separated from the pipe by a gap. The sealing means is positioned within said gap such that the first sealing surface is in contact with the exhaust system component about an outlet in the exhaust system component and the second sealing surface is in contact with the pipe, the sealing means being configured to prevent the escape of the exhaust gases from the vehicle exhaust system. The sealing means and the pipe are arranged with axial overlap along the direction of exhaust gas flow, the sealing means being positioned radially inwards of an extension portion of the pipe with which the sealing means has axial overlap.

The exhaust system component may be a turbocharger assembly. Alternatively, the exhaust system component may be an exhaust manifold. The following paragraphs explain the benefits of the present technique principally in terms of a turbocharger assembly, but it should be understood that the same principles and advantages apply to an exhaust manifold, or other exhaust system components. An arrangement in which a sealing means is positioned between a turbocharger assembly and a pipe allows for some relative movement between the two parts. The sealing means thus permits some thermal expansion of the turbocharger assembly and the pipe, without the creation of undesirable stresses in the components. In addition, such an arrangement advantageously reduces the transmission of vibrations between the turbocharger assembly and the pipe.

In one embodiment, said gap may extend between the turbocharger assembly and the pipe in an axial direction along the direction of exhaust gas flow. Such an arrangement permits relative movement between the turbocharger assembly and the pipe in an axial direction. The axial direction is defined as being a direction parallel to the longitudinal axis of the channel in the region of the sealing means. The entirety of the sealing means may be positioned within said gap.

Advantageously, the sealing means may be a spring-biased sealing means.

The pipe may be an inlet to a hot end of the vehicle exhaust system, the pipe being positioned downstream of the turbocharger assembly. Optionally, the pipe forms part of a catalytic converter assembly of the vehicle exhaust system. In an embodiment, the vehicle exhaust system comprises at least one additional gap between the turbocharger assembly and the pipe. The at least one additional gap may be between an extension portion of the turbocharger assembly and an inner contact portion of the pipe. This allows for exhaust gases to contact an inner surface of the sealing means.

The turbocharger assembly and the pipe may be arranged with axial overlap along the direction of exhaust gas flow. In an embodiment, the extension portion of the turbocharger assembly is arranged with axial overlap with an extension portion of the pipe. Optionally, the sealing means and the turbocharger assembly are arranged with axial overlap along the direction of exhaust gas flow. In this case, the sealing means may be positioned radially outwards of the extension portion of the turbocharger assembly, with which the sealing means has axial overlap.

In an embodiment, the sealing means and the pipe are arranged with axial overlap along the direction of exhaust gas flow. In this case, the sealing means may be positioned radially inwards of the extension portion of the pipe, with which the sealing means has an axial overlap. The sealing means may be positioned between the extension portion of the turbocharger assembly and the extension portion of the pipe.

The sealing means may be a seal. In an embodiment, the seal may have a bellows configuration. For example, the seal may have a bellows configuration in radial cross- section. Advantageously, a seal having a bellows configuration is able to deform from an original shape under pressure, and to recover the original shape on release of that pressure.

In the event that the seal has a bellows configuration, the seal may have a radial cross-section comprising two or more opposed c-shaped portions connected to one another. In this case, the orientation of the c-shaped portions may alternate so that adjacent c-shaped portions are facing in opposed directions.

Advantageously, the c-shaped portions at the first sealing surface and at the second sealing surface may be oriented such that the first and second sealing surfaces are compressed against the turbocharger assembly and the pipe, respectively, by the exhaust gases, in use. This assists in increasing the effectiveness of the seal between the first sealing surface and the turbocharger assembly, and between the second sealing surface and the pipe.

The entirety of the turbocharger assembly may be physically separated from the entirety of the pipe in a region defining the channel. The turbocharger assembly may be in contact with the pipe elsewhere (i.e. other than in the channel region). Alternatively, the turbocharger assembly and the pipe may be physically separated in their entirety.

Optionally, the sealing means forms a closed ring. The sealing means may be in a state of compression. Advantageously, the first sealing surface of the seal thus applies pressure to the turbocharger assembly, and the second sealing surface of the seal applies pressure to the pipe.

According to another aspect of the invention, there is provided a method of preventing the escape of exhaust gases from a vehicle exhaust system, the method comprising the step of arranging a turbocharger assembly and a pipe such that the turbocharger assembly and the pipe together define a channel for the exhaust gases flowing through the vehicle exhaust system. A resiliently-biased sealing means is positioned within a gap that physically separates the turbocharger assembly and the pipe, the sealing means having a first sealing surface and a second sealing surface. The sealing means is positioned such that the first sealing surface is in contact with the turbocharger assembly and the second sealing surface is in contact with the pipe.

According to another aspect of the invention, there is provided a vehicle comprising a vehicle exhaust system in accordance with a further previous aspect of the invention.

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:

Figure 1 is a schematic plan view of a vehicle having a vehicle exhaust system of an embodiment of the invention;

Figure 2 is a perspective view of the vehicle exhaust system of Figure 1 ;

Figure 3 is a perspective view of a sealing means of the vehicle exhaust system of Figure 1 ;

Figure 4a is a side view of a turbocharger assembly of the vehicle exhaust system of Figure 1 ; Figure 4b is a side view of the sealing means of Figure 3, in an 'in use' position with respect to the turbocharger assembly of Figure 4a;

Figure 5 is a perspective view of a pipe of the vehicle exhaust system of Figure 1 ; Figure 6 is a schematic section view of the sealing means of Figure 3, in an 'in use' position with respect to the turbocharger assembly of Figure 4a and the pipe of Figure 5; and

Figure 7 is a side view of the sealing means of Figure 3, in an 'in use' position with respect to the turbocharger assembly of Figure 4a and the pipe of Figure 5.

DETAILED DESCRIPTION

Figure 1 is a schematic view of a vehicle 10, comprising an engine 12 that is connected to a vehicle exhaust system 14. Referring to both Figure 1 and Figure 2, as is conventional, the vehicle exhaust system 14 comprises an exhaust gas manifold 16 that is fluidly connected to a first assembly in the form of a turbocharger assembly 18. The turbocharger assembly 18 is itself connected to a pipe 20, or inlet of a hot end 22 of the exhaust system 14, which transitions into a cold end 24 of the vehicle exhaust system 14. The hot end 22 of the vehicle exhaust system 14 comprises a second assembly in the form of a catalytic converter assembly 26 and a third assembly in the form of a chamber 30 for selective catalytic reduction (SCR), or SCR assembly. The cold end 24 of the vehicle exhaust system 14 comprises two mufflers or silencers 32 and a number of connecting pipes, including two tail pipes 34. In the present invention, the turbocharger assembly 18 and the catalytic converter assembly 26 are arranged so as to define a channel 35 (shown in Figure 6) for exhaust gases flowing through the vehicle exhaust system 14. When the vehicle 10 is in use, exhaust gases are produced in the engine 12. These exhaust gases are expelled from the engine 12 and are collected in the exhaust gas manifold 16, before passing through the downstream components of the vehicle exhaust system 14 and being released through the tail pipes 34 into the atmosphere. The vehicle exhaust system 14 is configured so as to guard against the release of exhaust gases before the exhaust gases have passed through the entirety of the vehicle exhaust system 14, to ensure that the exhaust gases are treated prior to their discharge into the atmosphere.

For this purpose, the vehicle exhaust system 14 comprises a number of sealing means that are configured to guard against the release of exhaust gases between adjoining components of the vehicle exhaust system 14. In particular, referring to Figures 1 to 3, the vehicle exhaust system 14 comprises a resiliently-biased seal 36, that is positioned between the turbocharger assembly 18 and the catalytic converter assembly 26 of the vehicle exhaust system 14, to form a first flexible joint 37 intermediate the turbocharger assembly 18 and the catalytic converter assembly 26 and to guard against the escape of exhaust gases therebetween. A second flexible joint 38 is positioned intermediate the catalytic converter assembly 26 and the chamber 30 for SCR.

As is shown most clearly in Figure 3, the seal 36 is in the form of an annular ring, having a bellows configuration in radial cross-section, such that the seal 36 is spring- biased. The cross-section of the seal comprises two or more opposed c-shaped portions 39 connected to one another, such that the orientation of the c-shaped portions 39 alternates. Typically, the seal 36 comprises five opposed c-shaped portions 39 in a 'multiple bellows' configuration, although the skilled person would appreciate that the number of opposed c-shaped portions 39 could be less than or greater than five, depending on the desired dimensions and properties of the seal 36. Referring to Figure 6, the seal 36 comprises an inner surface 40, an outer surface 42, a first sealing surface 44 and a second sealing surface 46. In use, the inner surface 40 of the seal 36 is exposed to exhaust gases passing through the vehicle exhaust system 14, and the outer surface 42 of the seal 36 is exposed to the external environment.

The seal 36 is typically manufactured using a nickel alloy, such as Inconel^®, and may be subjected to a heat treatment process to increase the ability of the seal 36 to recover its shape after deformation. Alternatively, the seal 36 may be manufactured from Waspaloy^® or any other suitable nickel alloy, or from stainless steel. The seal 36 is capable of cyclic use, and can be used at high temperatures. A coating, such as silver, may also be applied to the seal 36 to improve the sealing performance of the seal 36. Additional sealing structures may be applied at the inner and/or outer surfaces 40, 42 of the seal 36, or at one or both of the first or second sealing surfaces 44, 46, should the required specification of the first flexible joint 37 necessitate it.

Referring to Figures 4a and 4b, the turbocharger assembly 18 comprises an outer contact portion 48 and an extension portion 50. The extension portion 50 takes the form of an annular ring and extends from the outer contact portion 48 in an axial direction, so as to define an outlet 52 for exhaust gases from the turbocharger assembly 18. In an example, the outer contact portion 48 and the extension portion 50 may be manufactured by means of a casting process. Alternatively, the outer contact portion 48 and the extension portion 50 may be manufactured by way of machining. As can be seen in Figure 4b, which shows the seal 36 in situ, the diameter of the seal 36 is greater than the diameter of the extension portion 50 so that the extension portion 50 can be received within the seal 36, i.e. allowing the seal 36 to be located around the extension portion 50. In use, the seal 36 is thus positioned radially outwards of the extension portion 50 of the turbocharger assembly 18.

As shown in Figure 5, in the present invention the inlet 20 of the hot end 22 of the vehicle exhaust system 14 forms part of the catalytic converter assembly 26 of the vehicle exhaust system 14. The inlet 20 comprises a main body 53, an inner contact portion 54 in the form of an annulus, and an extension portion 56. The extension portion 56 of the inlet 20 extends from the inner contact portion 54 in an axial direction, forming a lip. The diameter of the seal 36 (shown in Figure 6) is smaller than the diameter of the extension portion 56 of the inlet 20, such that the seal 36 can be received within and hence positioned radially inwards of the extension portion 56 of the inlet 20.

Referring to Figures 6 and 7 the turbocharger assembly 18 and the catalytic converter assembly 26 are arranged with a gap or space 58 therebetween so that they are physically separated. Typically, the turbocharger assembly 18 and the inlet 20 of the catalytic converter assembly 26 are arranged such that the gap 58 extends axially between the outer contact portion 48 of the turbocharger assembly 18 and the inner contact portion 54 of the inlet 20 of the catalytic converter assembly 26, along the direction of exhaust gas flow. The seal 36 is positioned in the gap 58, such that the first sealing surface 44 of the seal 36 is in contact with the outer contact portion 48 of the turbocharger assembly 18 and the second sealing surface 46 of the seal 36 is in contact with the inner contact portion 54 of the inlet 20. In this way, the seal 36 bridges the gap 58 between the turbocharger assembly 18 and the catalytic converter assembly 26, but importantly the turbocharger assembly 18 and the catalytic converter assembly 26 do not make contact.

The seal 36 is positioned in the gap 58 between the extension portion 50 of the turbocharger assembly 18 and the extension portion 56 of the inlet 20 of the catalytic converter assembly 26. By virtue of the extension portion 50 of the turbocharger assembly 18 and the extension portion 56 of the inlet 20, the turbocharger assembly 18, the inlet 20 and the seal 36 are arranged with axial overlap along the direction of exhaust gas flow. In particular: a portion of the seal 36 has axial overlap with the extension portion 50 of the turbocharger assembly 18; a portion of the seal 36 has axial overlap with the extension portion 56 of the inlet 20; and, at least a portion of the extension portion 56 of the inlet 20 has axial overlap with at least a portion of the extension portion 50 of the turbocharger assembly 18. In other words, the extension portion 56 lies radially outward of the seal 36 and the extension portion 50 lies radially inward of the seal 36. In the depicted embodiment, a second gap 60 is defined between the extension portion 56 of the inlet 20 and a facing portion of the outer contact portion 48 of the turbocharger assembly 18, such that the second gap 60 extends in an axial direction along the direction of exhaust gas flow. The second gap 60 is positioned radially outwards of the sealing means 36. In addition, a third gap 62 is defined between the extension portion 50 of the turbocharger assembly 18 and a transition region between the main body 53 and the inner contact portion 54 of the inlet 20, such that the third gap 62 also extends in an axial direction along the direction of exhaust gas flow. The third gap 62 defines an inlet to the gap 58 between the turbocharger assembly 18 and the inlet 20 and permits exhaust gases to be diverted from the channel 35 to pass between the turbocharger assembly 18 and the inlet 20 of the catalytic converter assembly 26. This creates a region of high pressure exhaust gases at the inner surface 40 of the seal 36, such that a pressure gradient exists across the seal 36.

Typically, the c-shaped portions 39 of the seal 36 are oriented such that pressure applied to the inner surface 40 of the seal 36 by the exhaust gases compresses the first and second sealing surfaces 44, 46 against the turbocharger assembly 18 and the inlet 20 of the catalytic converter assembly 26, respectively. Specifically, the c-shaped portions 39 are oriented such that the exhaust gases flow outwardly into the c-shaped portion 39 at the first sealing surface 44 and into the c-shaped portion 39 at the second sealing surface 46, such that pressure is applied by the exhaust gases to cause the first and second sealing surfaces 44, 46 to be compressed against the respective assembly 18, 26. Such an arrangement improves the effectiveness of the seal 36 as a mechanism for preventing the escape of exhaust gases between the turbocharger assembly 18 and the catalytic converter assembly 26.

The turbocharger assembly 18 is rigidly bolted to the engine 12 of the vehicle 10, and the catalytic converter assembly 26 is similarly rigidly fixed in position in the vehicle 10. In particular, a part of the turbocharger assembly 18 that is remote from, or at least slightly separated from, the first flexible joint 37 is fixed in position in the vehicle 10, and a part of the catalytic converter assembly 26 that is remote from, or at least slightly separated from, the first flexible joint 37 is also fixed in position in the vehicle 10. In this way, these remote parts of the turbocharger assembly 18 and catalytic converter assembly 26 are substantially fixed in position relative to one another. The accuracy with which the remote parts of the turbocharger and catalytic converter assemblies 18, 26 are positioned relative to one another allows for the seal 36 to be held in position by the turbocharger assembly 18 and catalytic converter assembly 26 only and, in particular, by a single component of each of the turbocharger assembly 18 and catalytic converter assembly 26 only. In other words, no additional constraining means is required to hold the seal 36 in position between the assemblies 18, 26.

This enables some relative movement between the turbocharger and catalytic converter assemblies 18, 26 at the first flexible joint 37, to account for thermal expansion of the turbocharger assembly 18 and catalytic converter assembly 26 without risk of distortion of the components of the assemblies 18, 26 or the creation of undesirable stresses in the vehicle exhaust system 14. If anything, expansion of the components and the resultant reduction in the size of the gap 58 between the outer contact portion 48 of the turbocharger assembly 18 and the inner contact portion 54 of the catalytic converter assembly 26 increases the sealing strength of the seal 36, by increasing the force applied by the first and second sealing surfaces 44, 46 to the outer contact portion 48 and inner contact portion 54, respectively. In addition, the seal 36 has a damping effect, reducing the transmission of vibrations between the turbocharger assembly 18 and the catalytic converter assembly 26.

The bellows configuration of the seal 36 also allows the seal 36 to be particularly effective at deforming under compressive loads, such that the seal 36 can accommodate relative movement between the turbocharger assembly 18 and the catalytic converter assembly 26 without compromising the integrity of the seal 36.

The turbocharger assembly 18 and catalytic converter assembly 26 are typically physically separated in their entirely, such that the only connection between the turbocharger assembly 18 and the catalytic converter assembly 26 is by way of the seal 36 at the first flexible joint 37. Since the seal 36 at the first flexible joint 37 is positioned between the turbocharger assembly 18 and the catalytic converter assembly 26, the seal 36 does not constrain the turbocharger assembly 18 and the catalytic converter assembly 26 to a fixed position relative to one another. The ability of the seal 36 to change shape without being permanently deformed allows for some variation in the dimensions of the components of the turbocharger assembly 18 and the catalytic converter assembly 26, such that the seal 36 may accommodate tolerance stacks resulting from the manufacture and assembly of components of the vehicle exhaust system 14.

The second flexible joint 38 similarly allows for relative movement between the catalytic converter assembly 26 and the chamber 30 for SCR, to account for thermal expansion of the catalytic converter assembly 26 and the chamber 30 and for damping the transmission of vibrations therebetween. The second flexible joint 38 takes the form of a flexible pipe 58 (shown in Figures 1 and 2), but it would be appreciated by the skilled person that the second flexible joint 38 may take any alternative form, and may comprise a second seal (not shown). In this case, a part of the catalytic converter assembly 26 remote from the second flexible joint 38 and a part of the chamber 30 for SCR remote from the second flexible joint 38 may each be substantially fixed in position in the vehicle 10 such that the second seal is held in position by the relative positioning of the catalytic converter assembly 26 and chamber 30 only, in the same way as previously described in relation to the first flexible joint 37. Provision of both the first flexible joint 37 and second flexible joint 38 allows for components of the vehicle exhaust system 14 to be thermally decoupled from one another. For example, the first flexible joint 37 decouples the turbocharger assembly 18 from the catalytic converter assembly 26, such that thermal expansion in the turbocharger assembly 18 does not have a direct effect on the catalytic converter assembly 26. The seal 36 at the first flexible joint 37 allows for some thermal expansion of the turbocharger assembly 18 and catalytic converter assembly 26 without risk of distortion of the components of the assemblies 18, 26 or the creation of undesirable stresses in the vehicle exhaust system 14. If anything, expansion of the components and the resultant reduction in the size of the gap 58 between the outer contact portion 48 of the turbocharger assembly 18 and the inner contact portion 54 of the catalytic converter assembly 26 increases the sealing strength of the seal 36, by increasing the force applied by the first and second sealing surfaces 44, 46 to the outer contact portion 48 and inner contact portion 54, respectively. In addition, the seal 36 has a damping effect, reducing the transmission of vibrations between the turbocharger assembly 18 and the catalytic converter assembly 26. Such an arrangement allows the vehicle exhaust system 14 to cope with large vibrations and thermal variations without causing stress or deformation of the components thereof. Many modifications may be made to the above examples without departing from the scope of the present invention as defined in the accompanying claims.

For example, the skilled person would appreciate that the seal 36 may be positioned between any two adjacent components, where the adjacent components define a gap therebetween, such that the first flexible joint 37 may be positioned at any point in the vehicle exhaust system 14. In addition, it would be appreciated by the skilled person that the seal 36 may be positioned in a gap between the turbocharger assembly 18 and any adjacent downstream inlet, and that the invention is not intended to be restricted to an inlet 20 of a catalytic converter assembly 26.

In addition, the skilled person would understand that the third gap 62 is not restricted to a position between the extension portion 50 of the turbocharger assembly 18 and the inner contact portion 54 of the catalytic converter assembly 26. The third gap 62 may be in any suitable position so as to allow for exhaust gases to flow towards and impinge upon the inner surface 40 of the seal 36. Further, the second gap 60 and the third gap 62 may extend in a direction that is transverse to the axial direction, for example, if the extension portion 56 of the inlet 20 of the catalytic converter assembly 26 is offset from the outer contact portion 48 of the turbocharger assembly 18, or if the extension portion 50 of the turbocharger assembly 18 is offset from the inner contact portion 54 of the catalytic converter assembly 26.

It would be appreciated by the skilled person that the sealing means can take one of a number of forms. For example, the sealing means may be a seal having a radial cross- section in the form of a u-shape, or in the form of a circle. Alternatively, the sealing means may be in the form of a compressible sealant. The bellows configuration shown in the accompanying figures is therefore just one example.

Claims

1 . A vehicle exhaust system for a vehicle, the vehicle exhaust system comprising: a first assembly and a second assembly, the first and second assemblies together defining a channel for exhaust gases flowing through the vehicle exhaust system; and

a first flexible joint intermediate the first assembly and second assembly, the first flexible joint comprising a resiliently-biased sealing means having a first sealing surface and a second sealing surface,

the first assembly being physically separated from the second assembly by a gap extending between the first assembly and the second assembly in an axial direction, the sealing means being positioned within said gap such that the first sealing surface is in contact with the first assembly, the second sealing surface is in contact with the second assembly and relative movement between the first and second assemblies in an axial direction is permitted, the sealing means being configured to prevent the escape of the exhaust gases from the vehicle exhaust system,

wherein, in use, the first assembly is fixable in position to at least one part of the vehicle at at least one part of the assembly that is remote from the first flexible joint and the second assembly is fixable in position to at least a part of the vehicle at at least one part of the assembly that is remote from the first flexible joint such that the at least one part of the first assembly and the at least one part of the second assembly are substantially fixed in position.

2. The vehicle exhaust system of Claim 1 , wherein the first assembly is configured such that the assembly is only fixed in position to at least one part of the vehicle at the at least one part of the assembly.

3. The vehicle exhaust system of Claim 1 or Claim 2, wherein the second assembly is fixed in position to a part of the vehicle at at least one part of the second assembly that is remote from the first flexible joint.

4. The vehicle exhaust system of any preceding claim, wherein the sealing means contacts only the first assembly and the second assembly in the vehicle.

5. The vehicle exhaust system of Claim 4, wherein the sealing means contacts only a single component of each of the first and second assemblies.

6. The vehicle exhaust system of any preceding claim, wherein the first assembly is a turbocharger assembly.

7. The vehicle exhaust system of any preceding claim, wherein the second assembly comprises an inlet to a hot end of the vehicle exhaust system, the inlet being positioned downstream of the first assembly in the direction of exhaust gas flow.

8. The vehicle exhaust system of any preceding claim, wherein the second assembly is a catalytic converter assembly of the vehicle exhaust system.

9. The vehicle exhaust system of any preceding claim, wherein said gap extends between the first assembly and the second assembly in an axial direction along the direction of exhaust gas flow.

10. The vehicle exhaust system of any preceding claim, wherein the entirety of the sealing means is positioned within said gap.

1 1 . The vehicle exhaust system of any preceding claim, wherein the sealing means is a spring-biased sealing means.

12. The vehicle exhaust system of any preceding claim, further comprising a second gap between the first assembly and the second assembly.

13. The vehicle exhaust system of Claim 12, wherein the second gap extends in an axial direction along the direction of exhaust gas flow and the second gap is positioned radially outwards of the sealing means.

14. The vehicle exhaust system of any preceding claim, wherein the first assembly and the second assembly are arranged with axial overlap along the direction of exhaust gas flow.

15. The vehicle exhaust system of any preceding claim, wherein the sealing means and the first assembly are arranged with axial overlap along the direction of exhaust gas flow.

16. The vehicle exhaust system of Claim 15, wherein the sealing means is positioned radially outwards of an extension portion of the first assembly with which the sealing means has axial overlap.

17. The vehicle exhaust system of any preceding claim, wherein the sealing means and the second assembly are arranged with axial overlap along the direction of exhaust gas flow.

18. The vehicle exhaust system of Claim 17, wherein the sealing means is positioned radially inwards of an extension portion of the second assembly with which the sealing means has axial overlap.

19. The vehicle exhaust system of any preceding claim, wherein the sealing means is a seal having a bellows configuration.

20. The vehicle exhaust system of Claim 19, wherein the seal has a radial cross- section comprising two or more opposed c-shaped portions connected to one another.

21 . The vehicle exhaust system of Claim 20, wherein the c-shaped portions at the first sealing surface and at the second sealing surface are oriented such that the first and second sealing surfaces are compressed against the first assembly and the second assembly, respectively, by the exhaust gases flowing through the vehicle exhaust system, in use.

22. The vehicle exhaust system of Claim 21 , wherein the c-shaped portions are oriented such that the exhaust gases flow into the c-shaped portions at the first sealing surface and at the second sealing surface.

23. The vehicle exhaust system of any preceding claim, wherein the entirety of the first assembly is physically separated from the entirety of the second assembly in a region defining the channel.

24. The vehicle exhaust system of any preceding claim, wherein the sealing means forms a closed ring surrounding the channel.

25. The vehicle exhaust system of any preceding claim, wherein the sealing means is in a state of compression.

26. The vehicle exhaust system of any preceding claim, further comprising a second flexible joint.

27. The vehicle exhaust system of Claim 26, wherein the second flexible joint is positioned intermediate the second assembly and a third assembly of the vehicle exhaust system, the third assembly being downstream of the second assembly in the direction of exhaust gas flow.

28. The vehicle exhaust system of Claim 27 when dependent on Claim 8, wherein the second flexible joint is positioned intermediate the catalytic converter assembly and a selective catalytic reduction assembly of the vehicle exhaust system.

29. A method of preventing the escape of exhaust gases from a vehicle exhaust system, the method comprising the steps of:

arranging a first assembly and a second assembly such that the first assembly and second assembly together define a channel for the exhaust gases flowing through the vehicle exhaust system;

arranging a first flexible joint intermediate the first assembly and second assembly, the first flexible joint comprising a resiliently-biased sealing means having a first sealing surface and a second sealing surface;

positioning the sealing means within a gap that physically separates the first assembly and the second assembly, such that the first sealing surface is in contact with the first assembly and the second sealing surface is in contact with the second assembly; and fixing the first assembly in position o at least one part of the vehicle at at least one part of the first assembly that is remote from the first flexible joint and fixing the second assembly in position to at least a part of the vehicle at at least one part of the second assembly that is remote from the first flexible joint, such that the at least one part of the first assembly and the at least one part of the second assembly are substantially fixed in position relative to one another.

30. A vehicle comprising the vehicle exhaust system as claimed in any of Claims 1 to 28.

31 . A vehicle exhaust system comprising:

an exhaust system component and a pipe, the exhaust system component and the pipe together defining a channel for exhaust gases flowing through the vehicle exhaust system; and

a resiliently-biased sealing means, having a first sealing surface and a second sealing surface,

wherein the exhaust system component is physically separated from the pipe by a gap, the sealing means being positioned within said gap such that the first sealing surface is in contact with the exhaust system component about an outlet in the exhaust system component and the second sealing surface is in contact with the pipe, the sealing means being configured to prevent the escape of the exhaust gases from the vehicle exhaust system; and

wherein the sealing means and the pipe are arranged with axial overlap along the direction of exhaust gas flow, the sealing means being positioned radially inwards of an extension portion of the pipe with which the sealing means has axial overlap.

32. A vehicle exhaust system according to claim 31 , wherein the exhaust system component is a turbocharger assembly.

33. A vehicle exhaust system according to claim 31 , wherein the exhaust system component is an exhaust manifold.

34. The vehicle exhaust system as claimed in any of Claims 31 to 33, wherein said gap extends between the exhaust system component and the pipe in an axial direction along the direction of exhaust gas flow.

35. The vehicle exhaust system as claimed in any of Claims 31 to 34, wherein the entirety of the sealing means is positioned within said gap.

36. The vehicle exhaust system as claimed in any of Claims 31 to 35, wherein the sealing means is a spring-biased sealing means.

37. The vehicle exhaust system as claimed in any of Claims 31 to 36, wherein the pipe is an inlet to a hot end of the vehicle exhaust system, the pipe being positioned downstream of the exhaust system component.

38. The vehicle exhaust system of Claim 37, wherein the pipe forms part of a catalytic converter assembly of the vehicle exhaust system.

39. The vehicle exhaust system as claimed in any of Claims 31 to 38, further comprising at least one additional gap between the exhaust system component and the pipe.

40. The vehicle exhaust system as claimed in any of Claims 31 to 39, wherein the exhaust system component and the pipe are arranged with axial overlap along the direction of exhaust gas flow.

41 . The vehicle exhaust system as claimed in any of Claims 31 to 40, wherein the sealing means and the exhaust system component are arranged with axial overlap along the direction of exhaust gas flow.

42. The vehicle exhaust system of Claim 41 , wherein the sealing means is positioned radially outwards of an extension portion of the exhaust system component with which the sealing means has axial overlap.

43. The vehicle exhaust system as claimed in any of Claims 31 to 42, wherein the sealing means is a seal having a bellows configuration.

44. The vehicle exhaust system of Claim 43, wherein the seal has a radial cross- section comprising two or more opposed c-shaped portions connected to one another.

45. The vehicle exhaust system of Claim 44, wherein the c-shaped portions at the first sealing surface and at the second sealing surface are oriented such that the first and second sealing surfaces are compressed against the exhaust system component and the pipe, respectively, by the exhaust gases flowing through the vehicle exhaust system, in use.

46. The vehicle exhaust system as claimed in any of Claims 31 to 45, wherein the entirety of the exhaust system component is physically separated from the entirety of the pipe in a region defining the channel.

47. The vehicle exhaust system as claimed in any of Claims 31 to 46, wherein the sealing means forms a closed ring surrounding the channel.

48. The vehicle exhaust system as claimed in any of Claims 31 to 47, wherein the sealing means is in a state of compression.

49. A method of preventing the escape of exhaust gases from a vehicle exhaust system, the method comprising the steps of:

arranging an exhaust system component and a pipe such that the exhaust system component and the pipe together define a channel for the exhaust gases flowing through the vehicle exhaust system; and

positioning a resiliently-biased sealing means, having a first sealing surface and a second sealing surface, within a gap that physically separates the exhaust system component and the pipe, such that the first sealing surface is in contact with the exhaust system component and the second sealing surface is in contact with the pipe, wherein the sealing means and the pipe are arranged with axial overlap along the direction of exhaust gas flow, the sealing means being positioned radially inwards of an extension portion of the pipe with which the sealing means has axial overlap..

50. A vehicle comprising the vehicle exhaust system as claimed in any of Claims 31 to 48.