GB2556918A

GB2556918A - Exhaust manifold slip joint

Info

Publication number: GB2556918A
Application number: GB1619989.5A
Authority: GB
Inventors: Edward Smith James
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2016-11-25
Filing date: 2016-11-25
Publication date: 2018-06-13
Anticipated expiration: 2036-11-25
Also published as: GB2556918B; CN207647588U; GB201619989D0

Abstract

An exhaust manifold slip joint 10 for forming a permanent gas-tight seal between portions of an exhaust manifold 100, eg of an i.c. engine, comprises a first pipe portion 12 having a male coupling part 16 insertable into a female coupling part 18 of a second pipe portion 14. An exhaust gas leakage path 22 is provided at the section 24 where the male and female coupling parts overlap. A plurality of ridges 26 are provided on the male or female part at the overlapping section 24 to trap particulate matter thus forming a combustion seal. In a modification, an annular flange (56, fig.3) is provided on the first pipe portion 12 supporting a seal ring (58) which extends over the outlet 52 of the leakage path 22.

Description

(71) Applicant(s):

Perkins Engines Company Limited (Incorporated in the United Kingdom)

Frank Perkins Way, Eastfield, PETERBOROUGH, Cambs, PE1 5FQ, United Kingdom (56) Documents Cited:

WO 2015/073872 A1 US 20080012296 A1

US 6220605 B1 US 20060272321 A1 (58) Field of Search:

INT CL F01N, F16L

Other: EPODOC, Patent Fulltext, WPI (72) Inventor(s):

James Edward Smith (74) Agent and/or Address for Service:

Caterpillar UK Legal Services Division Eastfield, PETERBOROUGH, Cambs, PE1 5FQ, United Kingdom (54) Title of the Invention: Exhaust manifold slip joint Abstract Title: Exhaust manifold slip joint (57) An exhaust manifold slip joint 10 for forming a permanent gas-tight seal between portions of an exhaust manifold 100, eg of an i.e. engine, comprises a first pipe portion 12 having a male coupling part 16 insertable into a female coupling part 18 of a second pipe portion 14. An exhaust gas leakage path 22 is provided at the section 24 where the male and female coupling parts overlap. A plurality of ridges 26 are provided on the male or female part at the overlapping section 24 to trap particulate matter thus forming a combustion seal. In a modification, an annular flange (56, fig.3) is provided on the first pipe portion 12 supporting a seal ring (58) which extends over the outlet 52 of the leakage path 22.

1/3

102

2/3

3/3

EXHAUST MANIFOLD SLIP JOINT

Technical Field

This disclosure relates generally to the field of internal combustion engines, particularly to the exhaust manifolds of the internal combustion engines and more particularly to exhaust manifold interfaces.

Background

In an internal combustion engine, the exhaust manifold may deliver hot gases from the cylinders to the exterior thereof. The engine manifold may expand from start of the engine during operation of the engine. The degree of thermal expansion may be determined by factors such as: material properties; engine cycle; and exhaust gas temperature.

In large engines, the exhaust manifold may comprise several sections that are joined together. Exhaust manifolds may be designed with a gap between mutually joined portions to provide for ease of assembly and compensate for relative thermal expansion. The size of the gap may be configured to enable efficient assembly while providing for relative expansion within certain threshold levels.

In general, engines may be improved by having a larger manifold and connecting flanges for assembly of manifold sections. However, a larger connecting flange may require a greater number of fasteners in order to maintain proper sealing. Different materials used for fasteners compared to the exhaust manifold may result in different rates of expansion and contraction which may cause manifold cracking and fastener fatigue.

Operational capabilities of engines may be improved through improvements in fuel systems and electronics. Engines may be able to operate at different load levels in a relatively short time span. The ability to cycle between high and low load conditions may cause thermal expansions due to the fluctuation in exhaust temperatures. In order to compensate for thermal expansion in exhaust manifolds a bellows may be used in combination with the flange. However, the bellows that are known in the art have a tendency to fatigue and leak over time due to the harsh operating environment.

DE2729772A1 discloses a pipe connection for an internal combustion engine exhaust. The pipe connection has a sleeve covering the adjacent ends of the pipes. Each pipe end is cut back to leave a half-round pipe portion which engages the half-round portion of the other pipe to complete the full round section. The straight edges of each half-round portion are inclined to the pipe axis to form a hook engaging the complementary hook of the other halfround portion.

The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of the prior art system.

Brief Summary of the Invention

In a first aspect, the present disclosure describes an exhaust manifold slip joint comprising a first pipe portion including a male coupling part; a second pipe portion including a female coupling part wherein the male coupling part is insertable into the female coupling part so as to form an exhaust channel and wherein the female coupling part overlaps the male coupling part at an overlapping section; a leakage path fluidly connected to the exhaust channel wherein the leakage path is configured to provide for leakage of exhaust gas and wherein the leakage path is formed between the male coupling part and the female coupling part; and a plurality of ridges interposed between the male coupling part and the female coupling part at the overlapping region.

In a second aspect, the present disclosure describes a method for sealing an exhaust manifold slip joint. The method comprises the steps of providing a leakage path between a male coupling part of a first manifold section and a female coupling part of a second manifold section, wherein the leakage path is configured in use to provide for a flow of a portion of exhaust gas passing through the exhaust manifold slip joint into an inlet of the leakage path and along the leakage path, and wherein at least one of the male coupling and female coupling sections is configured to provide a series of ridges and valleys along the leakage path through which ridges and valleys the portion of exhaust gas passes as it travels along the leakage path; and using particulates in the portion of exhaust gas flowing through the leakage path to accumulate in the valleys and seal the exhaust manifold slip joint.

Brief Description of the Drawings

The foregoing and other features and advantages of the present disclosure will be more fully understood from the following description of various embodiments, when read together with the accompanying drawings, in which:

Fig. 1 is a isometric view of two sections of an exhaust manifold according to the present disclosure;

Fig. 2 is a partial sectional view of a first embodiment of the exhaust manifold slip joint according to the present disclosure; and

Fig. 3 is a partial sectional view of a second embodiment of the exhaust manifold slip joint according to the present disclosure.

Detailed Description

This disclosure generally relates to an exhaust manifold slip joint for an exhaust manifold. Fig. 1 illustrates an exhaust manifold 100 having a first manifold section 102 and a second manifold section 104. The exhaust manifold 100 may have an exhaust manifold slip joint 10 for connection of the first and second manifold sections 102, 104.

The exhaust manifold slip joint 10 may have a first pipe portion 12 and a second pipe portion 14. The first pipe portion 12 may include a male coupling part 16. The second pipe portion 14 may include a female coupling part 18. In an embodiment, the first pipe portion 12 may include the female coupling part 18 and the second pipe portion 14 may include a male coupling part 16.

Figs. 2 and 3 respectively illustrate a first and a second embodiment of the exhaust manifold slip joint 10. The male coupling part 16 may be inserted into the female coupling part 18. A leakage path 22 may be formed between the male coupling part 16 and the female coupling part 18. A plurality of ridges 26 may be interposed between the male coupling part 16 and the female coupling part 18.

The first pipe portion 12 may be carried on the first manifold section 102 and the second pipe portion 14 may be carried on the second manifold section 104. The first and second pipe portions 12, 14 may form any part of the exhaust manifold 100. First and second pipe portions 12, 14 may have a substantially tubular configuration. With reference to figs. 2 and 3, first pipe portion 12 may have a first hollow bore 34 that forms a first portion of an exhaust channel 20. Second pipe portion 14 may have a second hollow bore 36 that forms a second portion of the exhaust channel 20. In an embodiment, first and second pipe portions 12, 14 may each be substantially linear.

The female coupling part 18 may not form part of the second hollow bore 36. The female coupling part 18 may encompass a coupling bore 44 that is contiguous with the second hollow bore 36. Internal surface 46 of the female coupling part 18 may define the coupling bore 44. Coupling bore 44 may have a diameter that is greater than the diameter of the second hollow bore 36.

With reference to fig. 1, The male coupling part 16 may be insertable into the female coupling part 18. In an embodiment, the axial length of the male coupling part 16 may be substantially equal to the axial length of the female coupling part 18.The male coupling part 16 may be insertable into the female coupling part 18 so as to form the exhaust channel 20. Male coupling part 16 may be accommodated in the coupling bore 44. The respective first and second hollow bores 34, 36 of the first and second pipe portions 12, 14 may be connected to form the exhaust channel 20. The first and second pipe portions 12, 14 may be fluidly connected through the coupling of the male and female coupling parts 16, 18. In an embodiment, the exhaust channel 20 may be substantially linear and may have a longitudinal axis A.

The male coupling part 16 and the female coupling part 18 are both substantially tubular in shape. The diameter of the male coupling part 16 is equal to rest of the first pipe portion 12. The diameter of the female coupling part 18 is greater than rest of the second pipe portion 14. The internal diameter of the female coupling part 18 may be greater than rest of the second pipe portion 14. The female coupling part 18 may be radially spaced further from the longitudinal axis A relative to the rest of the second pipe portion 14. The diameter of the female coupling part 18 may be greater than rest of the male coupling part 16. The internal diameter of the female coupling part 18 may be greater than rest of the first pipe portion 12.

The second pipe portion 14 may have an annular shoulder 38 connecting the female coupling part 18 to the rest of the second pipe portion 14. Shoulder 38 may extend radially away from the second hollow bore 36. Shoulder 38 may define the start of the second hollow bore 36.

With reference to figs. 2 and 3, male coupling part 16 may have a first terminal end 28. First terminal end 28 may be configured as an annular ring defining a first opening 32. First opening 32 may lead to the first hollow bore 34 of the first pipe portion 12. First opening 32 may have a diameter substantially equal to the internal diameter of the male coupling part 16. First opening 32 may have a diameter substantially equal to the internal diameter of the first hollow bore 34. First opening 32 may have a diameter substantially equal to the internal diameter of the second hollow bore 36. First terminal end 28 may have face the shoulder 38. In an embodiment, the width of the shoulder 38 may be substantially equal to the width of the first terminal end 28.

With reference to fig. 1, female coupling part 18 may have a second terminal end 40. Second terminal end 40 may be configured as an annular ring defining a second opening 42. Second opening 42 leads to the coupling bore 44 of the second pipe portion 14. Second opening 42 may have a diameter substantially equal to the internal diameter of the female coupling part 18. The internal diameter of the second opening 42 may be configured to receive the male coupling part 16. The internal diameter of the second opening 42 may be greater than the external diameter of the male coupling part 16.

With reference to figs. 2 and 3, internal surface 46 of the female coupling part 18 may extend from the shoulder 38 to the second opening 42. Coupling bore 44 may extend from the shoulder 38 to the second opening 42.

The female coupling part 18 may overlap the male coupling part 16 at an overlapping section 24. The female coupling part 18 may be concentric to the male coupling part 16. Internal surface 46 of the female coupling part 18 may be concentric to an external surface 30 of the male coupling part 16. The overlapping section 24 may have an annular configuration. Overlapping section 24 may be concentric relative to the exhaust channel 20.

The overlapping section 24 may be defined by the respective structures of the female coupling part 18 and the male coupling part 16. The overlapping section 24 may be defined by the internal surface 46 of the female coupling part 18 and the external surface 30 of the male coupling part 16. The axial length of the overlapping section 24 may be determined by the respective axial lengths of the internal surface 46 of the female coupling part 18 and the external surface 30 of the male coupling part 16.

The internal surface 46 of the female coupling part 18 may be radially spaced from an external surface 30 of the male coupling part 16. Internal surface 46 of the female coupling part 18 may uniformly spaced from the external surface 30 of the male coupling part 16. Internal surface 46 of the female coupling part 18 may extend over the external surface 30 of the male coupling part 16. Internal surface 46 of the female coupling part 18 may be coaxial with the external surface 30 of the male coupling part 16 relative to the longitudinal axis A.

The exhaust manifold slip joint 10 may comprise the leakage path 22. Leakage path 22 may be a void in the exhaust manifold 100. Leakage path 22 may be a void extending through the exhaust manifold slip joint 10. The leakage path 22 may be fluidly connected to the exhaust channel 20. Leakage path 22 may be configured to provide for leakage of exhaust gas. Exhaust gas flowing through the exhaust channel 20 may flow into the leakage path 22 to the exterior of the exhaust manifold 100. The flow path of the exhaust gas are depicted by arrows in figs. 2 and 3.

Leakage path 22 may comprise the overlapping section 24. Exhaust gas leaking through the leakage path 22 may pass through the overlapping section 24. Leakage path 22 may extend from the respective internal surfaces to the respective external surfaces of the first and second pipe portions 12, 14. Leakage path 22 may have an annular configuration around the exhaust channel 20. The leakage path 22 may be concentric relative to the exhaust channel 20.

The leakage path 22 may comprises an inlet 48 for permitting entry of exhaust gas from the exhaust channel 20. Inlet 48 may permit fluid communication between the exhaust channel 20 and the leakage path 22. Inlet 48 may permit entry of exhaust gas into the leakage path 22 from the exhaust channel 20. Inlet 48 may be formed between the male coupling part 16 and the female coupling part 18. Inlet 48 may have an annular configuration around the exhaust channel 20.

Inlet 48 may be formed between the internal surface of the second hollow bore 36 and the first terminal end 28. Inlet 48 may be defined by the face of the first terminal end 28 on a first side and by the edge of the shoulder 38 and the internal surface of the second hollow bore 36, on a second side, and. In an embodiment, the first side may be defined by the edge of the first opening 32.

In embodiment, the leakage path 22 may further comprises an inlet section 50 leading from the inlet 48 to the overlapping section 24. The inlet section 50 may be formed between the shoulder 38 and the first terminal end 28. Inlet section 50 may extend radially away from the inlet 48. In a further embodiment, the inlet section 50 may be substantially perpendicular to the overlapping section 24. Exhaust gas may flow from the inlet 48 through the inlet section 50 to the overlapping section 24.

The leakage path 22 may comprises an outlet 52 for permitting exit of exhaust gas from the leakage path 22. Outlet 52 may permit fluid communication between the leakage path 22 and the exterior of the exhaust manifold 100. Outlet 52 may permit exit of exhaust gas from the leakage path 22 to the exterior of the exhaust manifold 100. Outlet 52 may be formed between the male coupling part 16 and the female coupling part 18. Outlet 52 may have an annular configuration around the exhaust channel 20. Outlet 52 may be coaxial to the inlet 48 relative to the longitudinal axis A.

With reference to fig. 2, in the first embodiment, the outlet 52 may be disposed at an end of the overlapping section 24. Outlet 52 may be disposed at the end of the overlapping section 24 that is opposite the end connected to the inlet section 50.

With reference to fig. 3, in a second embodiment, the first pipe portion 12 may further comprises an annular flange 56 spaced from the overlapping section 24. The annular flange 56 may be disposed on the male coupling part 16. Annular flange 56 may be formed on the external surface of the first pipe portion 12. Annular flange 56 may be concentric with the exhaust channel 20. Second terminal end 40 may have face the annular 56. In an embodiment, the width of the annular flange 56 may be substantially equal to the width of the second terminal end 40.

The outlet 52 may be formed between the annular flange 56 and the female coupling part 18. The outlet 52 may be formed between a free end 60 of the annular flange 56 and the second terminal end 40.

Outlet 52 may be defined by a side of the free end 60 of the annular flange 56 on a first side and by the face of the second terminal end 40, on a second side, and. In an embodiment, the first side may be defined by the edge of the free end 60 of the annular flange 56 and the second side may be defined by the outer perimeter of the second terminal end 40.

In embodiment, the leakage path 22 may further comprises an outlet section 54 leading from the outlet 52 to the overlapping section 24. The outlet section 54 may be formed between the side of the annular flange 56 and the second terminal end 26. Outlet section 54 may extend radially towards the outlet 52. In a further embodiment, the outlet section 54 may be substantially perpendicular to the overlapping section 24. .

In an embodiment, a seal ring 58 may extend over the outlet 52. Seal ring 58 may extend from the annular flange 56 to the female coupling part 18. Seal ring 58 may be connected to the free end 60 of the annular flange 56 at an end. Seal ring 58 may be connected to the external surface of the female coupling part 18. Seal ring 58 may be concentric with the outlet 52.

With reference to figs. 2 and 3, the distance between the male coupling part 16 and the female coupling part 18 may increase along the leakage path 22 from the inlet 48 to the outlet 52. The distance between the male coupling part 16 and the female coupling part 18 may increase relative to the flow path of the exhaust gas. The increasing clearance or width of the leakage path 22 between the male coupling part 16 and the female coupling part 18 along the leakage path may effect a reduction in the velocity of exhaust gas flow as the exhaust gas flows from the inlet 48 to the outlet 52.

The distance between the respective surfaces defining the inlet section 50 may increase from the inlet 48 to the overlapping section 24. The distance between the shoulder 38 and the first terminal end 28 may increase from the inlet 48 to the overlapping section 24.

With reference to fig. 2, the distance between the respective surfaces of the overlapping section 24 may increase from the inlet section 50 to the outlet 52 in the first embodiment. The distance between the internal surface 46 of the female coupling part 18 and the external surface 30 of the male coupling part 16 may increase from the inlet section 50 to the outlet 52 in the first embodiment.

With reference to fig. 3, the distance between the respective surfaces of the overlapping section 24 may increase from the inlet section 50 to the outlet section 54 in the second embodiment. The distance between the internal surface 46 of the female coupling part 18 and the external surface 30 of the male coupling part 16 may increase from the inlet section 50 to the outlet section 54 in the second embodiment.

With reference to fig. 3, the distance between the respective surfaces defining the outlet section 54 may increase from the overlapping section 24 to the outlet 52. The distance between the annular flange 56 and the second terminal end 40 may increase from the overlapping section 24 to the outlet 52.

In an embodiment, the cross-sectional area of the leakage path 22 may be greater at the outlet 52 than at the inlet 48. The cross-sectional area of the leakage path 22 may increase from the outlet 52 to the inlet 48.

With reference to figs, 1 to 3, the exhaust manifold slip joint 10 may comprise a plurality of ridges 26 interposed between the male coupling part 16 and the female coupling part 18 at the overlapping region 24. The plurality of ridges 26 promote soot particles or particulate matter from the exhaust gas to become trapped in between the male coupling part 16 and the female coupling part 18.

Plurality of ridges 26 may be distributed in series along the overlapping section 24. Plurality of ridges 26 may extend between the internal surface 46 of the female coupling part 18 and the external surface 30 of the male coupling part 16. Each ridge 26 may be an annular ring and may be concentric with the exhaust channel 20.

Each ridge 26 may have a suitable cross-sectional shape. In an embodiment, the crosssectional shape of the ridge 26 may be semi-circular, chordal, elliptical, trapezoidal, triangular or rectangular. Each ridge 26 may have a base and a tip. Each ridge 26 may be tapered from the base to the tip. In an embodiment, the tip may be narrower than the base.

In an embodiment, the ridges 26 may be disposed on the external surface 30 of the male coupling part 16. The base of each ridge 26 may be disposed on the external surface 30. The tip of each ridge 26 may engage the internal surface 46 of the female coupling part 18 at insertion of the male coupling part 16 into the female coupling part 18.

In an alternative embodiment, the ridges 26 may be disposed on internal surface 46 of the female coupling part 18. The base of each ridge 26 may be disposed on the internal surface 46. The tip of each ridge 26 may engage the external surface 30 of the male coupling part 16 at insertion of the male coupling part 16 into the female coupling part 18.

The height of the ridges 26 may increase along the overlapping section 24 from the inlet 48 to the outlet 52. The height of the ridges 26 may increase along the overlapping section 24 relative to the flow path of the exhaust gas. With reference to fig. 2, the height of the ridges 26 may increase along the overlapping section 24 from the inlet section 50 to the outlet 52 in the first embodiment. With reference to fig. 3, the height of the ridges 26 may increase along the overlapping section 24 from the inlet section 50 to the outlet section 54 in the second embodiment. The increasing height of the ridges 26 may assist in the assembly of the male coupling part 16 to the female coupling part 18. The clearance between male coupling part 16 and the female coupling part 18 may be relatively small, Accordingly, as the male coupling part 16 and the female coupling part 18 are drawn together, engagement of each successive ridge 26 of increasing height may assist in centralizing the respective parts together. Increasing height of the ridges 26 may also facilitate insertion of the successive ridge 26.

Increasing height of the ridges 26 may assist in maintaining an effective gas seal as the male coupling part 16 and the female coupling part 18 become heated and slide against each other during operation. The largest and final ridge 26 may be relatively close to internal surface 46, accordingly the preceding ridges 26 may retain the accumulated particulate matter that assist in providing a combustion seal.

The exhaust manifold slip joint 10 may comprise a plurality of valleys 62 interspersed between the ridges 26. The preceding ridges 26 may also assist in progressively reducing the gas pressure in each valley 62 thereby improving the gas seal.

The width of the ridges 26 may increase along the overlapping section 24 from the inlet 48 to the outlet 52. The width of the ridges 26 may increase along the overlapping section 24 relative to the flow path of the exhaust gas. With reference to fig. 2, the width of the ridges 26 may increase along the overlapping section 24 from the inlet section 50 to the outlet 52 in the first embodiment. With reference to fig. 3, the width of the ridges 26 may increase along the overlapping section 24 from the inlet section 50 to the outlet section 54 in the second embodiment.

With reference to figs, 1 to 3, valleys 26 may be defined by the distance between respective bases of the adjacent ridges 26. Soot particles or particulate matter from the exhaust gas may become trapped in the valleys 62 between the adjacent ridges 26. In an embodiment, the width ofthe valleys 62 may decrease along the overlapping section from the inlet 48 to the outlet 52. The width of the valleys 62 may decrease along the overlapping section 24 relative to the flow path of the exhaust gas. With reference to fig. 2, the width of the valleys 62 may decrease along the overlapping section 24 from the inlet section 50 to the outlet 52 in the first embodiment. With reference to fig. 3, the width of the valleys 62 may decrease along the overlapping section 24 from the inlet section 50 to the outlet section 54 in the second embodiment

The exhaust manifold slip joint 10 may be comprised in the exhaust manifold 100 as illustrated in figs 1 to 3. The exhaust manifold 100 may be comprised in an internal combustion engine (not shown).

A method for sealing an exhaust manifold slip joint 10 may comprise the steps of providing a leakage path 22 between a male coupling part 16 of a first pipe portion 12 of an first manifold section 102 and a female coupling part 18 of a second manifold section 104, wherein the leakage path 22 is configured in use to provide for a flow of a portion of exhaust gas passing through the exhaust manifold slip joint 10 into an inlet 48 of the leakage path 22 and along the leakage path 22, and wherein at least one of the male coupling and female coupling sections 16, 18 is configured to provide a series of ridges 26 and valleys 62 along the leakage path 22 through which ridges 26 and valleys 62 the portion of exhaust gas passes as it travels along the leakage path 22; and using particulates in the portion of exhaust gas flowing through the leakage path 22 to accumulate in the valleys 62 and seal the exhaust manifold slip joint 10.

The method may further comprise the step of reducing the clearance between the ridges 26 and the internal surface 46 by relative thermal expansion between the male coupling part 16 and the female coupling part 18 so as to reduce or eliminate the leakage path 22 to prevent gas leakage from the exhaust manifold 100.

The skilled person would appreciate that foregoing embodiments may be modified or combined to obtain the exhaust manifold slip 10 of the present disclosure.

Industrial Applicability

This disclosure describes an exhaust manifold slip joint 10 for an exhaust manifold 100. The exhaust manifold slip joint 10 enables efficient assembly of the first and second pipe portions 12, 14 of the exhaust manifold 100. The plurality of ridges 26 interposed between the first and second pipe portions 12, 14 encourage soot particles from the exhaust gas to become trapped in the voids between the first and second pipe portions 12, 14. The build-up of soot particles may assist in forming a permanent gas-tight seal between the first and second pipe portions 12, 14.

The clearance between the first and second pipe portion 12, 14 may increase along the leakage path may result in the velocity of any exhaust gas leakage to decrease towards the outlet 52. The reduction in velocity may further assist in the deposit of the soot particles in the exhaust gas.

At assembly, the exhaust manifold 100 is cold and the clearance, in particular the width of the leakage path 22, between the first and second pipe portions 12, 14 provides for ease of assembly. The ease of assembly may be assisted further by the increasing height of of the ridges 26 along the overlapping section 24. As the engine warms up during operation, the clearance may be reduced. The reduction of clearance may assist in forming a gas tight seal when the exhaust manifold 100 becomes hot during engine operation. During hot/cold thermal cycling of the exhaust manifold 100, the ridges 26 will move relative to the complementary abutting surface of the first or second pipe portion 12, 14. During this relative movement, the ridges 26 may be encouraged to wear against the complementary abutting surface of the first or second pipe portion 12, 14. The tips of the ridges 26 may be worn according to the size and shape of the recess. A ridge 26 having a wider tip may have more wear resistance. The amount of wear may be configured by adjusting the width of the tips of the ridges 26 thereby permitting optimization effectiveness of the gas seal. The gas tight seal may be maintained by accumulated soot particles around the periphery of the ridges 26.

Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein.

Where technical features mentioned in any claim are followed by reference signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, neither the reference signs nor their absence have any limiting effect on the technical features as described above or on the scope of any claim elements.

One skilled in the art will realise the disclosure may be embodied in other specific forms without departing from the disclosure or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the disclosure described herein. Scope of the invention is thus indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.

Claims

1. An exhaust manifold slip joint (10) comprising:

a first pipe portion (12) including a male coupling part (16);

a second pipe portion (14) including a female coupling part (18) wherein the male coupling part (16) is insertable into the female coupling part (18) so as to form an exhaust channel (20) and wherein the female coupling part (18) overlaps the male coupling part (18) at an overlapping section (24);

a leakage path (22) fluidly connected to the exhaust channel (20) wherein the leakage path (22) is configured to provide for leakage of exhaust gas and wherein the leakage path (22) is formed between the male coupling part (16) and the female coupling part (18); and a plurality of ridges (26) interposed between the male coupling part (16) and the female coupling part (18) at the overlapping region (24).

2. The exhaust manifold slip joint (10) of claim 1 wherein the leakage path (22) comprises an inlet (48) for permitting entry of exhaust gas from the exhaust channel (20) and an outlet (52) for permitting exit of exhaust gas out of the leakage path (22).

3. The exhaust manifold slip joint (10) of claim 2 wherein the first pipe portion (12) comprises an annular flange (56) spaced from the overlapping section (24) and the outlet (52) is formed between the annular flange (56) and the female coupling part (18).

4. The exhaust manifold slip joint (10) of claims 2 or 3 wherein the leakage path (22) comprises an outlet section (54) leading from the outlet (52) to the overlapping section (24) and the outlet section (54) is substantially perpendicular to the overlapping section (24).

5. The exhaust manifold slip joint (10) of claims 2, 3 or 4 wherein the leakage path (22) comprises an inlet section (50) leading from the inlet (48) to the overlapping section (24) wherein the inlet section (50) is substantially perpendicular to the overlapping section (24).

6. The exhaust manifold slip joint (10) of claims 3, 4 or 5 wherein a seal ring (58) extends over the outlet (52) from the annular flange (56) to the female coupling part (18).

7. The exhaust manifold slip joint (10) of any one of claims 2 to 6 wherein the distance between the male coupling part (16) and the female coupling part (18) increases along the leakage path from the inlet to the outlet.

8. The exhaust manifold slip joint (10) of any one of claims 2 to 7 wherein the height of the ridges (26) increases along the overlapping section (24) from the inlet (48) to the outlet (52).

9. The exhaust manifold slip joint (10) of any one of claims 2 to 8 wherein the width of the ridges (26) increases along the overlapping section (24) from the inlet (48) to the outlet (52).

10. The exhaust manifold slip joint (10) of any one of preceding claims further comprising a plurality of valleys (62) interspersed between the ridges (26) wherein the width of the valleys (62) decreases along the overlapping section (24) from the inlet (48) to the outlet (52).

11. The exhaust manifold slip joint (10) of any one of preceding claims wherein the leakage path (22) is concentric relative to the exhaust channel (20).

12. The exhaust manifold slip joint (10) of any one of preceding claims wherein the overlapping section (24) is concentric relative to the exhaust channel (20).

13. An exhaust manifold (100) comprising the exhaust manifold slip joint (10) of any one of the preceding claims.

14. An internal combustion engine comprising the exhaust manifold (100) of claim 13.

15. A method for sealing an exhaust manifold slip joint (10), comprising the steps of:

providing a leakage path (22) between a male coupling part (16) of a first manifold section (102) and a female coupling part (18) of a second manifold section (104), wherein 5 the leakage path (22) is configured in use to provide for a flow of a portion of exhaust gas passing through the exhaust manifold slip joint (10) into an inlet (48) of the leakage path (22) and along the leakage path (22), and wherein at least one of the male coupling and female coupling sections (16, 18) is configured to provide a series of ridges (26) and valleys (62) along the leakage path (22) through which ridges (26) and valleys (62) the

10 portion of exhaust gas passes as it travels along the leakage path (22); and using particulates in the portion of exhaust gas flowing through the leakage path (22) to accumulate in the valleys (62) and seal the exhaust manifold slip joint (10).

Intellectual

Property

Office

Application No: GB1619989.5