GB2248899A

GB2248899A - Flexible joint for motor vehicle exhaust system

Info

Publication number: GB2248899A
Application number: GB9022851A
Authority: GB
Inventors: Patrick John Toudic; Keith Ransom
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1990-10-19
Filing date: 1990-10-19
Publication date: 1992-04-22
Anticipated expiration: 2010-10-19
Also published as: GB9022851D0; GB2248899B

Abstract

A flexible joint for a motor vehicle exhaust system is described which comprises two sections of pipe 10, 12 for connection to an exhaust system, a part-spherical seat 20 on one section, a collar 18 on the other section, and a compressible seal 16 having a part-spherical outer surface disposed between the collar 18 and the seat 20. A gimbal ring 22 connects the two pipe sections 10, 12 to one another in a position in which the seal is compressed between the seat 20 and the collar 18 to effect a seal between the two pipe sections. The gimbal ring 22 is connected by a respective pair of aligned pivot pins 24, 26 to each of the pipe sections 10, 12 and the axes defined by the respective pairs of pivot pins 24, 26 intersect one another at a point coincident with the centre of the part-spherical sealing surfaces. <IMAGE>

Description

FLEXIBLE JOINT FOR MOTOR VEHICLE EXHAUST SYSTEM Field of the invention The present invention relates to a flexible joint for a motor vehicle exhaust system.

DescriPtion of the prior art There has been proposed a joint for flexibly joining two parts of a vehicle exhaust system in which a seal formed of a compressible copper clad mesh is clamped between a collar on one of the parts and a part-spherical seat on the other part. It is necessary to apply a force between the two parts to maintain the seal in compression and this has been done by means of springs acting on clamping rings of the joint.

Such a design has certain disadvantages in that the movement of the parts relative to one another is controlled only by the springs which act to maintain the seal compressed. The springs are usually arranged around two bolts passing through the clamping rings and the joint nay pivot about a line passing through the two bolts. However, this arrangement does not allow pivoting about an axis perpendicular to the plane of the bolts. Thus, though the seal should inherently be capable of two degrees of freedom, the means for maintaining the seal compressed restrict the pivotal movement to one degree of freedom.

The design of the springs also presents problems in that if the springs are too weak, an effective seal is not achieved and if the springs are too strong then the seal will wear and tend to squeak in operation. This problem is aggravated by the fact that the spring force must be maintained within a narrow permissible band over a very wide temperature range.

of cfthe invention The invention seeks to provide a flexible joint which is suitable for use in a motor vehicle exhaust system and which has two degrees of pivotal freedom.

A further aim of the invention is to provide a flexible joint in which means other that the part-spherical seal are provided for connecting the inlet and outlet pipes of the joint to one another so that the pipes may only pivot relative to one another about a point coincident with the centre of the seal.

Summary of the invention According to the present invention, there is provided a flexible joint for a motor vehicle exhaust system, comprising two sections of pipe for connection to the exhaust system, a part-spherical seat on one section, a collar on the other section, a compressible seal having a part-spherical outer surface and disposed between the collar and the seat, and a gimbal ring connecting the two pipe sections to one another in a position in which the seal is compressed between the seat and the collar to effect a seal between the two pipe sections, the gimbal ring being connected by a respective pair of aligned pivot pins to each of the pipe sections and the axes defined by the respective pairs of pivot pins intersecting one another at a point coincident-with the centre of the partspherical seat.

The arrangement of the gimbal ring and the two pipes forms a universal joint which can pivot freely about a point coinciding with the centre of the sealing surface.

Therefore in all position of the pipes, the same force is applied to compress the seal. In this way, noise from the sealing surface can be suppressed and any tendency for the seal to be unseated can be eliminated.

Brief descrintion or the drawi The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of a flexible joint of the invention, and Figure 2 is a section through the joint when assembled taken along the discontinuous section line designated I-I in Figure 1.

Detailed description of the invention In the drawings, a flexible joint is shown for connecting a first section of exhaust pipe 10 to a second section of exhaust pipe 12. The second section of pipe 12 has welded onto it a short flanged tube 14, the weld being designated 30 in Figure 2. A collar 18 on the tube 14 forms a flat sealing surface and the section 10 has a flared end 20 which defines a spherical sealing surface. A part spherical sealing ring 16 is sandwiched between the two sealing surfaces and is maintained slightly compressed in use to effect a good seal between the two pipe sections 10 and 12 even when the sections pivot relative to one another.

The joint further comprises a gimbal ring 22 of large diameter that the flanged tube 14 which is mounted with clearance between the tube 14 and the flared end 20 of the section of the exhaust pipe 10. The gimbal ring 22 has four holes 36, 38 of which the holes 36 are in line with two holes 34 in the pipe section 10 and receive a first pair of pivot pins 26 and the second pair of holes 38 are in line with holes 32 in the flanged tube 14 and receive a pair of pivot pins 24.

To asz amble the flexible joint, the flats s ebe 14 is welded to the pipe section 12 with part of the pipe section 12 projecting beyond the collar 18. The gimbal ring 22 is slipped over the flanged tube 14 and the pivot pins 24 are inserted into the holes 38 in the gimbal ring 22 and the holes 32 in the flanged tube 14. The pivot pins are a tight fit in the holes 38 but a loose fit in the holes 32 so that gimbal ring 22 can pivot about the axis of the pins 24 relative to the flanged tube 14.

The sealing ring 16 is next fitted over the end of the pipe section 12 projecting beyond the collar 18 and rests against the collar 18. The sealing ring 16 is made of a steel mesh with an external copper cladding which can establish a gas tight seal with the flared end 20 of the first pipe section 10. Being made of a wire mesh, the ring is compressible under pressure and its own resilience maintains the contact pressure on the sealing surfaces.

In the next step, the flanged tube 14 with the gimbal ring 22 secured to it and the sealing ring 16 slipped onto it, is introduced into the flared end 20 of the pipe section 12 and, using a suitable jig, pressure is applied to compress the sealing ring 16. When the ring 16 is compressed, the holes 34 in the flared end 20 line up with the second pair of holes 36 in the gimbal ring and the second pair of pivot pins 26 can now be fitted into the aligned holes. The pins 26 are a tight fit in the holes 36 but not in the holes 34 so that the gimbal ring 22 can pivot relative to the flared end of the pipe section 10 about the axis of the pivot pins 26.

The axes of the pins 26 lie in the same plane as and at right angles to the axes of the pine 24 and their intersection coincides with the part spherical sealing surface between the sealing ring 16 and the flared end 20 of the pipe section 10. As a result of the gimbal mounting, the two pipe sections can therefore swivel in all directions relative to one another and because the pivoting centre, as defined by the intersection of the axes of the pins 24 and 26, lies at the centre of curvature of the part-spherical sealing surfaces, such pivoting movements will not affect the sealing pressure.

In this way, noise from the sealing surface is suppressed and any tendency for the seal to be unseated is eliminated.

Claims

CLAIM8

1. A flexible joint for a motor vehicle exhaust system, comprising two sections of pipe for connection to an exhaust system, a part-spherical seat on one section, a collar on the other section, a compressible seal having a part-spherical outer surface and disposed between the collar and the seat, and a gimbal ring connecting the two pipe sections to one another in a position in which the seal is compressed between the seat and the collar to effect a seal between the two pipe sections, the gimbal ring being connected by a respective pair of aligned pivot pins to each of the pipe sections and the axes defined by the respective pairs of pivot pins intersecting one another at a point coincident with the centre of the partspherical seat.

2. A flexible joint for a motor vehicle exhaust system constructed, arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.