WO2020208129A1

WO2020208129A1 - A pipe arrangement, an exhaust system and a vehicle

Info

Publication number: WO2020208129A1
Application number: PCT/EP2020/060127
Authority: WO
Inventors: Martin DALE; Jonathan Pierce
Original assignee: Jaguar Land Rover Limited
Priority date: 2019-04-10
Filing date: 2020-04-09
Publication date: 2020-10-15
Also published as: GB201905058D0; GB2583462B; GB2583462A

Abstract

Aspects of the present invention relate to a pipe arrangement (107) for an exhaust system (104) for a vehicle (101), an exhaust system (104) and a vehicle (101). The pipe arrangement (107), comprises a pipe means (201) defining a duct (202) having an inlet end (203) and an outlet end (204), the pipe means (201) being configured to receive exhaust gases at the inlet end (203) and guide the exhaust gases to the outlet end (204); a wall (213), wherein the wall (213) and the pipe means (201) define a space (214) between the pipe means (201) and the wall(213); a first aperture (229) to provide fluid communication between the duct (202) and the space (214); and a second aperture (216) for providing fluid communication between the space (214) and a pressure sensor (111) configured to provide a measure of pressure of gases within the space (214).

Description

A PIPE ARRANGEMENT, AN EXHAUST SYSTEM AND A VEHICLE

TECHNICAL FIELD

The present disclosure relates to a pipe arrangement, an exhaust system and a vehicle. In particular, but not exclusively it relates to a pipe arrangement and an exhaust system for a road vehicle such as a car and to a road vehicle such as a car.

BACKGROUND

It is known to include a particulate filter in an exhaust system of an internal combustion engine. During use the particulate filter becomes blocked by contaminants it has trapped, but it may be unblocked by a regeneration process. In order to determine when regeneration is required it is known to provide a pressure sensor upstream and downstream of a particulate filter, and determine the pressure difference. Alternatively, an exhaust system may just have the upstream pressure sensor, and the need for regeneration may be determined based on signals provided by that sensor. The pressure sensors are typically located within the flow of exhaust gases. The transient and often turbulent flow of gases past the sensors affect the accuracy of the sensor readings and dictate the position of the sensors along the exhaust system, which can result in packaging problems. In addition, the fluctuating measurements caused by turbulent flow can result in regeneration being performed sooner than is necessary and so have an adverse effect on fuel economy.

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a pipe arrangement, an exhaust system and a vehicle as claimed in the appended claims.

According to an aspect of the invention there is provided a pipe arrangement for an exhaust system for a vehicle, comprising: a pipe means defining a duct having an inlet end and an outlet end, the pipe means being configured to receive exhaust gases at the inlet end and guide the exhaust gases to the outlet end; a wall, wherein the wall and the pipe means define a space between the pipe means and the wall; a first aperture to provide fluid communication between the duct and the space; and a second aperture for providing fluid communication between the space and a pressure sensor configured to provide a measure of pressure of gases within the space.

This provides the advantage that gas pressures within the space fluctuate less and so a pressure sensor arranged to provide a measure of pressure within the space is able to provide a more stable measurement indicative of pressure in the pipe means.

Optionally, the pipe means defines the first aperture; and the wall defines the second aperture. Optionally, the pipe means comprises at least two pipes. This provides the advantages that movement may be allowed between the two pipes during thermal expansion and contraction, and the first aperture may be provided as a space between the two pipes.

Optionally, the wall is located outside of the pipe means and provides a support structure configured to support the pipe means in its position. This provides the advantage that the pipe means, which is subjected to the largest changes in temperature, due to flows of exhaust gases, does not have to be self-supporting.

Optionally, the wall extends around the outside of substantially the whole length of the pipe means with the space being between substantially the whole length of the pipe means and the wall. This provides the advantage that the wall is generally at a lower temperature than the pipe means, which guides the exhaust gases.

Optionally, the pipe means comprises a first pipe extending from the inlet end to the first aperture and a second pipe extending from the first aperture to the outlet end; the first aperture being an annular aperture formed between the first pipe and the second pipe. This provides the advantage that movement may be allowed between the two pipes at the first aperture during thermal expansion and contraction.

Optionally, the first pipe and the second pipe have overlapping end portions and the annular aperture extends around the outside of one of the end portions and around the inside of the other one of the end portions.

Optionally, the pipe arrangement comprises a porous element extending between an inner surface of the wall and an outer surface of one of the first pipe and the second pipe; and the porous element is positioned along the pipe arrangement between the pressure sensor and the aperture. This provides the advantage that the porous element impedes gas flow and further reduce fluctuations in gas pressure detected by the pressure sensor.

Optionally, the porous element comprises a porous ring which extends around the outside surface of said one of the first pipe and the second pipe. This provides the advantage that the porous ring may be used to support the first pipe or second pipe in position within the wall as well as reducing fluctuation in gas pressure detected by the pressure sensor.

Optionally, the pipe arrangement comprises a porous element configured to impede flow of gases between the duct and the second aperture. This provides the advantage that fluctuations in gas pressure detected by the pressure sensor are reduced.

Optionally, the porous element extends across the first aperture.

Optionally, the pipe arrangement comprises a sensor pipe having a first end attached to the wall and a second end external to the wall, the sensor pipe being configured to provide fluid communication between the space and a sensor operatively connected to the second end. This provides the advantage that a pressure sensor may be conveniently positioned, separated from the wall. Optionally, the pipe means has a middle portion extending between an inlet portion adjacent to the inlet end and an outlet portion adjacent to the outlet end; the outlet portion widens from the middle portion to the outlet end; and the sensor pipe intercepts a part of a wall of the wall that faces the outlet portion. This provides the advantage that a pressure sensor may be positioned at or near where it would be on existing systems in which the sensor is positioned just upstream of the particulate filter.

According to another aspect of the invention there is provided an exhaust system for a vehicle comprising the pipe arrangement according to any one of the previous paragraphs, wherein the exhaust system comprises a pressure sensor configured to provide a measure of pressure of gases within the space.

Optionally, the exhaust system comprises a pressure sensor configured to provide a measure of pressure of gases within the space, the sensor pipe providing fluid communication between the space and the pressure sensor.

According to another aspect of the invention there is provided an exhaust system for a vehicle comprising the pipe arrangement according to any one of the previous paragraphs and a particulate filter positioned at the outlet end of the duct.

Optionally, the exhaust system comprises a pressure sensor configured to provide a measure of pressure of gases within the space.

Optionally, the sensor pipe provides fluid communication between the space and the pressure sensor.

According to a further aspect of the invention there is provided a vehicle comprising the pipe arrangement or the exhaust system according to any one of the previous paragraphs.

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 vehicle embodying the present invention;

Fig. 2 shows a pipe arrangement embodying the present invention, in cross-section and positioned between a catalytic converter and a particulate filter; Fig. 3 shows an alternative pipe arrangement embodying the present invention;

Fig. 4 shows another alternative pipe arrangement embodying the present invention;

Fig. 5 shows a further alternative pipe arrangement embodying the present invention;

Fig. 6 shows an exploded view of the pipe arrangement of Fig. 2;

Fig. 7 shows a further alternative pipe arrangement embodying the present invention;

Fig. 8 shows a further alternative pipe arrangement embodying the present invention; and

Fig. 9 shows an end view of the pipe arrangement of Fig. 8.

DETAILED DESCRIPTION

A vehicle 101, an exhaust system 104 and a pipe arrangement 107 in accordance with embodiments of the present invention is described herein with reference to the accompanying Figures 1 to 9.

With reference to Fig. 1 , 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) configured to generate torque to drive at least two of the road wheels 102. The vehicle 101 also comprise an exhaust system 104 configured to receive exhaust gases produced by the engine 103.

The exhaust system 104 includes and exhaust manifold 105 and a catalytic converter 106 downstream of the exhaust manifold 105. A pipe arrangement 107 provides fluid communication from the catalytic converter 106 to a particulate filter 108, and downstream of the particulate filter 108, the exhaust system 104 may comprise other components such as a muffler 109 before it ends in a tailpipe 110.

In the present example, the engine 103 is a petrol (or gasoline) engine, and the particulate filter 108 is a gasoline particulate filter (GPF). Flowever, in alternative vehicles embodying the present invention, the engine 103 is a diesel engine and the particulate filter 108 is a diesel particulate filter (DPF).

During operation of the engine 103, particles present in the exhaust gases collect in the particulate filter 108, causing a resistance to flow resulting in an increase in the gas pressure within the pipe arrangement 107. A pressure sensor 111 is provided on the pipe arrangement 107. The pressure sensor 111 is arranged to measure gas pressure within the pipe arrangement 107 and provide a signal indicative of the gas pressure to a control system 112. The control system 112 monitors the signal received from the pressure sensor 111 and causes regeneration of the particulate filter 108 when the signal from the pressure sensor 111 indicates that regeneration is required. For example, the control system 112 may cause the operation of the engine 103 to be temporarily adjusted to provide conditions in the particulate filter 108 that are necessary for its regeneration.

The pipe arrangement 107 is shown in cross-section in Fig. 2 positioned between the catalytic converter 106 and the particulate filter 108.The pipe arrangement 107 comprises a pipe means 201 defining a duct 202 having an inlet end 203 and an outlet end 204. The inlet end 203 of the pipe means 201 is arranged to receive exhaust gases from the catalytic converter 106. The pipe means 201 is configured to guide the received exhaust gases to its outlet end 204 where they are delivered to the particulate filter 108. The particulate filter 108 may be of a known type that allows gases to pass through but traps particulate material on it surfaces where it may be periodically converted to carbon dioxide during regeneration.

In the present embodiment the pipe means comprises a first pipe 205 and a second pipe 206. The first pipe 205 has a relatively large opening at a first end 207 that provides the inlet end 203 of the pipe means 201 and a relatively small opening at an opposite second end 208. An end portion 209 of the first pipe 205 at its second end 208 overlaps an end portion 210 at a first end 211 of the second pipe 206. The first end 211 of the second pipe 206 has a relatively small opening compared to the opening at its second end 212 where it meets the particulate filter 108. The second end 208 of the first pipe 205 is dimensioned to fit within the opening formed by the first end 211 of the second pipe 206 so that gases flowing from the second end 208 of the first pipe 205 generally flow into and along the second pipe 206.

The pipe arrangement 107 also comprises a wall 213 located outside of the pipe means 201. The wall 213 and the pipe means 201 define a space 214 between the pipe means 201 and the wall 213. In the present embodiment, the wall 213 is in the form of an outer pipe 215 defining a bore along which the pipe means 201 extends. Consequently, the wall 213 extends around the outside of substantially the whole length of the pipe means 201 with the space 214 existing between substantially the whole length of the pipe means 201 and the wall 213.

The pipe means 201 defines a first aperture 229 to provide fluid communication between the duct 202 formed by the pipe means 201 and the space 214 between the pipe means 201 and the wall 213. In the present embodiment, the first aperture 229 is an annular aperture formed between the first pipe 205 and the second pipe 206 where the end portion 209 of the first pipe 205 overlaps with the end portion 210 of the second pipe 206.

The wall 213 defines a second aperture 216 to provide fluid communication between the space 214 and the pressure sensor 111. In the embodiment of Fig. 2, the second aperture 216 is formed in the wall of the outer pipe 215 and a sensor pipe 217 has a first end 226 attached to the outer pipe 215 at the second aperture 216, so that gases are able to flow from the space 214 and through the sensor pipe 215. The pressure sensor 111 is operatively connected to a second end 227 of the sensor pipe 217 that is external to the outer pipe 215, so that the sensor pipe 217 provides fluid communication between the space 214 and the pressure sensor 111. Consequently, the pressure sensor 111 is able to provide a measure of pressure of gases within the space 214.

The pressure sensor 111 may be connected to the sensor pipe 217 by a flexible hose 218, as illustrated in Fig. 2 or it may be fixed directly to the sensor pipe 217.

During use of the pipe arrangement 107, the outer pipe 215 has a first end 219 that is joined to an upstream component of the exhaust system 104, such as the catalytic converter 106 and a second end 220 joined to the particulate filter 108. The first end 219 and the second end 220 are sealed to the components to which they are joined and the outer pipe 215 is configured to be air tight (when the pressure sensor 111 is in place) so that all exhaust gases received by the pipe arrangement 107 are delivered to the particulate filter 108. For example, the outer pipe 215 may be formed of a metal that is welded to the outer metal walls of the catalytic converter 106 and the particulate filter 108.

The wall 213 of the pipe arrangement 107 is formed of a relatively thick gauge of metal compared to the pipe means 201, and it provides a support structure configured to support the pipe means 201 in its position. To provide support to the pipe means 201 , the outer pipe 215 is fixed to the first end 207 of the first pipe 205 and to the second end 212 of the second pipe 206, for example by welding.

The second end 208 of the first pipe 205 is supported in position within the wall 213 by a first spacer ring 221 that extends around the outside of the first pipe 205 near to its second end 208. The first spacer ring 221 has an inner surface positioned against an outer surface of the first pipe 205 and an outer surface positioned against an inner surface of the wall 213 and thereby holds the first pipe 205 in position within the wall 213.

Similarly, the first end 211 of the second pipe 206 is supported in position within the wall 213 by a second spacer ring 222 that extends around the outside of the second pipe 206 near to its first end 211. The second spacer ring 222 has an inner surface positioned against an outer surface of the second pipe 206 and an outer surface positioned against the inner surface of the wall 213 and thereby holds the second pipe 206 in position within the wall 213.

The second spacer ring 222 comprises a porous element that is configured to be porous to gases, so that gas pressure within the space 214, where the pressure sensor 111 is arranged to measure gas pressure, is indicative of the gas pressure at the first aperture 229. Consequently, the pressure sensor 111 is able to provide a measure of the pressure of gases at the first aperture 229. For example, the second spacer ring 222 may be formed of a woven or knitted metal wire material that is formed into a ring shape, similar to existing rings known for use within components of exhaust systems. The first spacer ring 221 may be formed of a similar material to the second spacer ring 222.

An inlet portion 223 of the pipe means 201 has a cross-section that reduces in area between the inlet end 203 of the pipe means 201 and a middle portion 224 of the pipe means 201 , and an outlet portion 225 of the pipe means 201 has a cross section that increases in area between the middle portion 224 and the outlet end 204 of the pipe means 201. The middle portion 224 has a cross-section that does not change, or only changes to a relatively small degree, over its length. Consequently, during operation of the engine 103, exhaust gases flowing along the duct 202 from the middle portion 224 into the outlet portion 225 flow in a non-linear manner with a portion of the exhaust gases circulating in the outlet portion 225 back towards the middle portion 224 and recirculating. As the rate of flow of gases through the duct 202 varies, the manner in which the gases recirculate within the outlet portion 225 also varies. Consequently, if the pressure sensor 111 were arranged to measure pressure at a position within the outlet portion 225 of the pipe means 201 , the measured pressure would vary with time, in dependence upon the recirculation of gases that was present at the position of the measurement.

Flowever, the pressure sensor 111 is arranged to measure pressure at a position where gas pressure is relatively stable. Firstly, it may be noted that the first aperture 229 is within the middle portion 224 of the pipe means 201 at a position where gas flows are relatively linear compared to those in the outlet portion 225. Also, because the second pipe 206 overlaps the first pipe 205, with the first pipe 205 on the inside of the second pipe 206, the gas flows are generally not directed into the first aperture 229. Consequently, gas pressures on the space 214 side of the first aperture 229 are not unduly affected by unstable gas pressures produced by recirculating gases. In addition, the porous element provided in the form of the ring spacer 222 impedes flow of gases between the duct 202 and the second aperture 216, and so any brief fluctuations in gas pressure that are present on the first aperture 229 side of the ring spacer 222 tend to cause smaller fluctuations in gas pressure on the second aperture 216 side of the ring spacer 222.

Because the gas pressure signals provided by the pressure sensor 111 to the controller 112 are relatively stable, the condition of the particulate filter 108 may be determined by the controller 112 with a high degree of confidence in a relatively short period of time compared to the period of time that would be required if the pressure sensor 111 were positioned to measure pressures within the outlet portion 225. This allows the times at which regeneration of the particulate filter 108 to be more accurately determined and consequently regeneration may be performed less often, thereby saving fuel.

It may be noted that, during use, the pipe means 201 becomes much hotter than the outer pipe 215. However, although the spacer rings 221 and 222 maintain the first and second pipes 205 and 206 in position within the outer pipe 215, they enable a degree of movement along the length of the outer pipe 215 to accommodate thermal expansion of the first and second pipes 205 and 206.

Also, although the middle portion 224 is illustrated in Fig. 2 as being straight, in reality the middle portion 224 may be curved, at least partly to enable the exhaust system 104 to be located within available space within the vehicle 101.

The position of the pressure sensor 111 in the example of Fig. 2 is arranged to be closer to the outlet end 204 of the pipe means 201 than it is to the inlet end 203. Also, the sensor pipe 217 intercepts the outer pipe 215 at a position on the wall of the outer pipe 215 that faces the outlet portion 225 of the pipe means 201. This arrangement enables the pipe arrangement 107 to be located in a vehicle 101 where there is space near to the particulate filter 108 to accommodate the pressure sensor 111. However, because the pressure sensor 111 is arranged to measure pressure in the space between the pipe means 201 and the wall 213, the pressure sensor 111 may be positioned in many different positions in other embodiments, as suggested by the Figs. 3 to 5.

Alternative pipe arrangements 107 embodying the present invention are shown in Figs. 3, 4, 5 and 7. The pipe arrangement 107 of Figs. 3, 4, 5 and 7 are similar to that of Fig. 2 and the features that they have in common with the pipe arrangement of Fig. 2 have been provided with the same reference signs. Thus, the pipe arrangement 107 of Figs. 3, 4, 5 and 7 comprises a pipe means 201 defining a duct having an inlet end 203 and an outlet end 204, and the pipe means 201 is configured to receive exhaust gases at the inlet end 203 and guide the exhaust gases to the outlet end 204. A wall 213 comprising an outer pipe 215 is located outside of the pipe means 201, and a space 214 is provided between the pipe means 201 and the wall 213. The pipe means 201 defines a first aperture 229 to provide fluid communication between the duct 202 and the space 214, and the wall 213 defines a second aperture 216 for providing fluid communication between the space and a pressure sensor configured to provide a measure of pressure of gases within the space 214.

In Figs. 3 and 4 the pipe means 201 comprises a first pipe 205 and a second pipe 206, which are arranged with overlapping end portions 209 and 210 in a similar manner to those of Fig. 2, and the first pipe 205 and the second pipe 206 are supported within the wall 213 in a similar way as described above for the pipe means 201 of Fig. 2. Flowever, the pipe arrangement 107 of Fig. 3 differs from that of Fig. 2 in that the second aperture 216 formed in the wall 213 is positioned in the wall of the outer pipe 215 that faces the first pipe 205, and a porous element in the form of the first spacer ring 221 is positioned between the first aperture 229 and the second aperture 216. It may be noted that the position of the first aperture 229 along the pipe means 201 is similar to that of Fig. 2 and therefore the pressures detected by a pressure sensor 111 when connected to the sensor pipe 217 are similar to those detected by the sensor 111 in Fig. 2, even though the position of the pressure sensor 111 is substantially changed.

The pipe arrangement 107 of Fig. 4 differs from that of Figs. 2 and 3 in that the second aperture 215 in the wall 213 is positioned along its length between the first spacer ring 221 and the second spacer ring 222. Therefore, the pipe arrangement 107 of Fig. 4 does not rely on either of the spacer rings 221 and 222 being porous. A porous element 401 , such as a wire mesh is provided across the first aperture 229 as shown in Fig. 4 to impede flow between the duct 202 and the space 214 and so reduce fluctuations in gas pressure within the space 214. Flowever, in an alternative embodiment, similar to that of Fig. 4, the pipe arrangement 107 does not include the porous element 401.

The pipe arrangement 107 of Fig. 5 differs from that of Fig. 2 in that the pipe means 201 comprises a single pipe 501 defining several first apertures 229 in the middle portion 224 of the pipe 501. The outlet portion 225 of the pipe 501 is welded to the wall 213 but to allow for thermal expansion of the pipe 501 , the inlet portion 223 is held in position in the wall by a spacer ring 502. A porous element in the form of a spacer ring 222 supports the middle portion 224 of the pipe 501 in its position within the wall 213. The spacer ring 222, like that of Fig. 2 is positioned along the pipe means 201 between the first apertures 229 and the position of the second aperture 216.

The first pipe 205 of the pipe arrangement 107 of Fig. 7 is similar to that of Fig. 2 and is supported within the wall 213 in a similar manner to that of Fig. 2, and therefore it is able to expand and contract as first pipe 205 is heated and cooled during use. Flowever, the pipe arrangement 107 of Fig. 7 differs from that of Fig. 2 in the manner in which the second pipe 206 is supported within the wall 213 and the position of the first aperture 229. A shaped portion 701 of the second pipe 206 widens out to the first end 211 , where it is welded 702 to the inside surface of the outer pipe 215. The second end 212 of the second pipe 206 is unattached to the outer pipe 215 to leave a first aperture 229 between the second end 212 of the second pipe 206 and the outer pipe 215, so that pressure within the space 214 between the outer surface of the second pipe 206 and the inner surface of the outer pipe 213 has a pressure that is dependent on the pressure within the second pipe 206 at its second end 212. i.e. in this embodiment, the first aperture 229 is defined by the outlet end 204 of the pipe means 201 and the wall 213. The wall 213 of Fig. 7 comprises a second aperture 216 to enable fluid communication between the space 214 and a pressure sensor (not present in Fig. 7), which may be positioned at a second end 227 of a sensor pipe 217 that is connected to the outer pipe 215 at the second aperture 216. It may be noted that, in the embodiment of Fig. 7, there is no porous element between the first aperture 229 and the second aperture 216. Flowever, in alternative embodiments to that of Fig. 7, such as porous element may be provided, for example, in the form of a porous spacer ring that supports the second pipe 206 adjacent to its second end 212 within the wall 213.

A further alternative pipe arrangement 107 embodying the present invention is shown in a cross-sectional side view in Fig. 8 and an end view in Fig. 9. The position of the plane 901 of the cross-section of Fig. 8 is shown in Fig. 9. The pipe arrangement 107 comprises a single pipe 801 configured to make a sealing connection with a particulate filter 108 at an outlet end 802 and another component of an exhaust system, such as a catalytic converter 108, at an inlet end 803.

The pipe arrangement 107 also comprises an open-sided box 804 that has edges 805 surrounding its open side that are attached to the inner surface 808 of the pipe 801 , so that the space 214 within the box 804 is enclosed by the sides of the box 804 and the pipe 801. The outside surfaces 806 of the box 804 are exposed to the space within the pipe 801 , and therefore the pipe 801 in combination with the box 804 provide a pipe means 201 that defines a duct 202 between the inlet end 803 and the outlet end 802. One or more first apertures 229 are provided in a side 807 of the box 804 to provide fluid communication between the duct 202 and the space 214 within the box 804. A second aperture 216 is provided in a wall 213 that forms a part of the pipe 801 , so that the second aperture 216 is able to provide fluid communication between the space 214 and a pressure sensor (not shown).

A sensor pipe 217 has a first end 226 fixed to the pipe 801 at the position of the second aperture 216 so that the sensor pipe 217 is able to provide fluid communication between the space 214 and a second end 227 of the sensor pipe 217 where a pressure sensor may be fitted.

In the embodiment of Figs. 8 and 9, the box 804 extends only partially around the inner surface 808 of the pipe 801 , but in alternative embodiments, it has a circular shape that extends completely around the inner surface 808 of the pipe 801.

In alternative embodiments to that of Figs. 8 and 9, the configuration of the pipe arrangement is substantially the same as the pipe arrangement of Figs. 8 and 9. Flowever, the box 804 is formed as a part of the pipe 801 (i.e. formed from the same piece of material as the remainder of the pipe 801) and the wall 213 is formed of a separate piece of material that is attached to the pipe 801 to cover the open side of the box 804. In one such embodiment, the wall 213 and the sensor pipe 217 are formed as a single part that is welded to the pipe 801 over the open side of the box 804.

The construction of the pipe arrangement 107 of Fig. 2 is illustrated in the exploded view of Fig. 6. The first pipe 205 is formed of a length of tube 601 and a conical element 602. The conical element 602 has a relatively wide, open end 603 that provides the inlet end 203 of the pipe means 201 and a narrower open end 604 dimensioned to enable it to be connected to the tube 601. The narrower open end 604 of the conical element 602 is welded to the tube 601 to form the first pipe 205. The second pipe 206 is formed in a similar manner to the first pipe 205.

The wall 213 comprises two half shells 605 and 606 formed of metal that are welded together to form the wall 213. After locating the spacer ring 221 on the first pipe 205 and the second spacer ring 222 on the second pipe 206, the first pipe 205 and the second pipe 206 are located within the wall 213 and welded to the wall 213 at the first end 207 of the first pipe 205 and the second end 212 of the second pipe 206, to form the pipe arrangement 107.

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.

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

1. A pipe arrangement for an exhaust system for a vehicle, comprising:

a pipe means defining a duct having an inlet end and an outlet end, the pipe means being configured to receive exhaust gases at the inlet end and guide the exhaust gases to the outlet end;

a wall, wherein the wall and the pipe means define a space between the pipe means and the wall;

a first aperture to provide fluid communication between the duct and the space; and

a second aperture for providing fluid communication between the space and a pressure sensor configured to provide a measure of pressure of gases within the space.

2. A pipe arrangement according to claim 1 , wherein: the pipe means defines the first aperture; and the wall defines the second aperture and/or wherein the pipe means comprises at least two pipes.

3. A pipe arrangement according to any one of claims 1 to 2, wherein the wall is located outside of the pipe means and provides a support structure configured to support the pipe means in its position.

4. A pipe arrangement according to any one of claims 1 to 3, wherein the wall extends around the outside of substantially the whole length of the pipe means with the space being between substantially the whole length of the pipe means and the wall.

5. A pipe arrangement according to any one of claims 1 to 4, wherein: the pipe means comprises a first pipe extending from the inlet end to the first aperture and a second pipe extending from the first aperture to the outlet end; the first aperture being an annular aperture formed between the first pipe and the second pipe and optionally wherein the first pipe and the second pipe have overlapping end portions and the annular aperture extends around the outside of one of the end portions and around the inside of the other one of the end portions.

6. A pipe arrangement according to claim 5, wherein: the pipe arrangement comprises a porous element extending between an inner surface of the wall and an outer surface of one of the first pipe and the second pipe; and the porous element is positioned along the pipe arrangement between the pressure sensor and the aperture and optionally wherein the porous element comprises a porous ring which extends around the outside surface of said one of the first pipe and the second pipe.

7. A pipe arrangement according to any one of claims 1 to 5, wherein the pipe arrangement comprises a porous element configured to impede flow of gases between the duct and the second aperture and optionally wherein the porous element extends across the first aperture.

8. A pipe arrangement according to any one of claims 1 to 7, wherein the pipe arrangement comprises a sensor pipe having a first end attached to the wall and a second end external to the wall, the sensor pipe being configured to provide fluid communication between the space and a sensor operatively connected to the second end and optionally wherein: the pipe means has a middle portion extending between an inlet portion adjacent to the inlet end and an outlet portion adjacent to the outlet end; the outlet portion widens from the middle portion to the outlet end; and the sensor pipe intercepts a part of a wall of the wall that faces the outlet portion.

9. An exhaust system for a vehicle comprising the pipe arrangement according to any one of claims 1 to 8, wherein the exhaust system comprises a pressure sensor configured to provide a measure of pressure of gases within the space and optionally the sensor pipe providing fluid communication between the space and the pressure sensor.

10. An exhaust system for a vehicle comprising the pipe arrangement according to any one of claims 1 to 8 and a particulate filter positioned at the outlet end of the duct.

11. An exhaust system according to claim 10, wherein the exhaust system comprises a pressure sensor configured to provide a measure of pressure of gases within the space.

12. An exhaust system according to claim 11, comprising the pipe arrangement according to claim 8, wherein the sensor pipe provides fluid communication between the space and the pressure sensor.

13. A vehicle comprising the pipe arrangement of any one of claims 1 to 8 or the exhaust system of any one of claims 9 to 12.