PIPE CONNECTION

Abstract: The invention relates to a connection between a first pipe piece (1) and a second pipe piece (8), wherein the cross section of both pipe pieces is substantially equal, wherein the connection allows at least a mutual angular displacement of the axis of both pipe pieces in a plane extending through both axes, wherein the first pipe piece comprises at least two passages (3, 2) and the second pipe piece comprises at least two passages, and in any mutual position of the pipe pieces the separating walls (10) between the passages in the first pipe piece at least practically make contact with the separating walls between the passages in the second pipe piece, wherein both pipe pieces have a round cross section and wherein the boundary surface between the pipe pieces extends substantially as a sphere with the point of rotation of the pipe pieces as centre. According to a first preferred embodiment the second pipe is provided with a number of passages larger than two. The advantages of the present invention are also achieved in this situation, i.e a separation between both passages in the first pipe piece.

Description: PIPE CONNECTION The present invention relates to a connection between a first pipe piece and a second pipe piece, wherein the cross-section of both pipes is substantially equal and wherein the connection allows at least a mutual angular displacement of the axis of both pipe pieces in a plane extending through both axes. Such connections are generally known in the form of pieces of flexible pipe. A desired degree of flexibility is obtained by arranging a short piece of flexible pipe between the first pipe piece and the second pipe piece. Such a connection functions excellently in situations where both pipe pieces are only single- passage, i.e. in situations where both pipe pieces are only adapted to guide a single gas flow. There are however situations where both pipe pieces are divided into at least two passages. Both pairs of passages are separated by a partition wall . When a flexible pipe piece is arranged between the two pipe pieces, the two partition walls will not generally connect onto each other, so that the passages will be mutually connected and a short-circuit will occur. US-A-4 188 784 provides such a connection for this purpose wherein the first pipe comprises at least two passages, the second pipe comprises at least two passages, in that in any mutual position of the pipes the separating walls between the passages in the first pipe at least practically make contact with the separating walls between the passages in the second pipe. The object of the present invention is to provide such a connection wherein the partitioning between the two passages is maintained up to a position beyond the second pipe piece, this at as many different mutual angular positions of the pipe pieces as possible. This objective is achieved in that both pipe pieces have a round cross -section and in that the separating wall between the pipe pieces extends substantially as a sphere with the point of rotation of the pipe pieces as centre. According to a first preferred embodiment the second pipe is provided with a number of passages larger than two . The advantages of the present invention are also achieved in this situation, i.e a separation between both passages in the first pipe piece. The danger of short-circuit of the gas flow is moreover further reduced when the number of passages in the second pipe piece is so large that the cross-section of the passages is at least two orders of magnitude smaller than the cross-section of the second pipe piece. According to another preferred embodiment both pipes have a round cross -section and the separating wall between the pipes extends substantially as a sphere with the point of rotation of the pipes as centre. Although the present invention has a wide field of application, the advantages of the present invention become particularly apparent in the use as components of the exhaust system of a motor vehicle. In view of the fact that parts of the exhaust are mounted rigidly on the engine and that other parts of the exhaust are mounted with a certain degree of elasticity on the bodywork of a motor vehicle, it will be apparent that diverse components of an exhaust system are subjected to mutual movements. The exhaust systems are usually constructed such that such mutual movements result in a mutual angular displacement between diverse components of an exhaust system. It is pointed out here that angular displacements are generally very small, being in the order of magnitude of a few degrees, wherein according to the prior art suitable couplings are otherwise known for mutual coupling of the pipe pieces which enable mutual rotation of these pipe pieces. The present invention finds more particular application when the first pipe forms a connection between an engine of a motor vehicle and a catalytic converter, and wherein the second pipe is formed by a converter housing. A catalytic converter is in any case already provided with a large number of parallel channels which are particularly attractive to serve as partitioned passages in the present invention. A further advantage is manifested in the fact that a catalytic converter is a relatively heavy component of an exhaust system, wherein it is attractive in respect of temperature management to place this component the shortest possible distance from the engine block. So as to subject the catalytic converter as little as possible to the vibrations from the engine block it is particularly attractive to arrange such a connection according to the invention in the exhaust system and, because of the large number of channels in a catalytic converter, this connection can preferably be used in the proximity of the catalytic converter. The advantages of the invention are particularly manifest in this embodiment, since it is important that the exhaust gas flows coming from the diverse cylinders remain separated as far as possible so as to prevent mutual influencing of the cylinders. Other attractive preferred embodiments are stated in the remaining sub-claims. The present invention will be elucidated hereinbelow with reference to the annexed drawings, in which: figure 1 shows a partly broken away perspective view of a first embodiment of the device according to the present invention; figure 2 is a schematic perspective view of an engine, wherein a connection according to the present invention is placed between the engine and the catalytic converter; figure 3 shows a cross-sectional view of a catalytic converter which is provided on both sides with a connection according to the present invention; figure 4 shows a cross-sectional view of a variant of the embodiment depicted in figure 3 ; and figure 5 shows a cross-sectional view of another variant of the embodiment depicted in figure 3. Figure 1 shows a first pipe 1 formed by two passages 2,3 separated by a separating wall 4. In the drawn embodiment the first pipe 1 comprises an outer pipe 5 in which are placed two inner pipes 6 respectively 7 so that separating wall 4 is formed by two inner pipes 6,7. A similar situation applies for a second pipe 8. This comprises a first passage 9 and a second passage not shown in the drawing. Both passages are separated by a partition wall 10, while the whole assembly of the second pipe is formed by an outer pipe 11 and two inner pipes 12, wherein the second is not shown in the drawing. Both pipe pieces connect to each other. The end of outer pipe 5 is thus widened to form a cup 13 and the corresponding end of outer pipe 11 is provided with a collar 14. Placed between the end of pipe 11 and collar 14 is an annular junction 15 which on its outside has substantially the shape of a segment of a sphere. Both pipe pieces 1,8 are fixed to each other by a coupling not shown in the drawing which allows a rotation movement between both pipe pieces but which holds both pipe pieces in mutual contact . In order to ensure that the gas flows flowing in passages 2 and 3 are permanently separated, separating walls 4 respectively 10 extend to within close proximity of each other. In order to enable the rotation movement of the pipe pieces one of the two separating walls is herein provided with a concave end wall while the other is provided with a convex end wall. It will be apparent that in this embodiment a separation is maintained between both gas flows only when the rotation is limited only to rotation on a single axis . If it is desired for the tubes to mutually rotate on more than one axis, another embodiment, which will be elucidated with reference to the other figures, is more attractive. Figure 2 shows an application of such an embodiment . Figure 2 shows an engine block 16 provided with an exhaust manifold 17 which runs out into a pipe piece 18. A catalytic converter 19 is further shown, wherein converter 19 and pipe piece 18 are joined by a connection 20. Converter 19 is once again connected on its outlet side to a further pipe piece 21 which leads to the further components of the exhaust system. Here also a connection 22 is arranged between converter 19 and pipe piece 21. As can be seen in figure 3, pipe piece 18 is provided with a separating wall 23 whereby pipe piece 18 comprises two different passages 24 respectively 25. So as to prevent short-circuit between the gas flows occurring in both passages 24 respectively 25, it is important that the gas flows are only combined with each other after a certain distance. Earlier combining would result in a kind of short-circuit of both flows, whereby mutual influencing would occur which would have a negative effect on the efficiency of the engine. In modern automobiles it is important that the catalytic converter be placed as close as possible to the engine, on the one hand to bring converter 19 as quickly as possible to the desired operating temperature and on the other to maintain this temperature. This will result in the most effective possible use of the catalytic converter. In view of the foregoing, it is important that the gas flows coming from the pairs of cylinders are separated at least up to the catalytic converter. Use is made for this purpose of the fact that a catalytic converter is provided with a large number of parallel channels of small cross-section. This measure is taken in order to make the active surface area of the catalytic converter as large as possible. The present invention makes surprising use of this property by causing the structure forming the separating walls of the catalytic converter to extend to a point at least a short distance from separating wall 23. The separation between passages 24 and 25 is herein maintained into the catalytic converter. Because connection 20 further allows an angular displacement of the axes of pipe piece 18 and catalytic converter 19 and the converter structure extends as a sphere, this separation is maintained, also in the case of small angular displacements. Separating wall 23 will of course not always connect directly onto the separating walls of the catalytic converter, since these latter often have a triangular or hexagonal structure. Given the small cross- section of the channels, the effect thereof is negligible . In view of the fact that the exhaust gas flow coming from the engine has to be distributed over the diverse channels of the catalytic converter, this latter must have a larger passage than the exhaust pipe. 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Ω CO H- 1 ^ O PJ LQ φ CO μ- J3 ø tr CQ ua ø <! ø rr Ω PJ PJ PJ rr ø rr φ • ø ti μ- O Φ ø h- 1 rt φ rt rt PJ tr ti rt h- 1 μ- ø μ- Φ CO φ ti Φ ti tr μ- μ- tr CQ P. Ω O ti H PJ o Φ CQ μ- φ ø PJ PJ Φ Hi 0 H rt rt co CQ ø H M tr tr H> tr PJ rt tr "< Φ Φ • φ φ ii cross-section of the catalytic converter is hereby obtained. Further in this embodiment the boundary surface between the catalytic converter and the first pipe piece takes a convex form and the second boundary surface is concave. All converter channels thus have the same length. It will be apparent that diverse changes can be made to the embodiment shown here without departing from the inventive concept: it is thus possible to make use of more complicated separating wall structures in the pipe pieces instead of a single separating wall. Application is moreover not limited to a catalytic converter; it is possible to apply structures designed specially for this purpose.

Claims: CLAIMS 1. Connection between a first pipe piece and a second pipe piece, wherein the cross-section of both pipe pieces is substantially equal, wherein the connection allows at least a mutual angular displacement of the axis of both pipe pieces in a plane extending through both axes, wherein the first pipe piece comprises at least two passages, the second pipe piece comprises at least two passages, and in any mutual position of the pipe pieces the separating walls between the passages in the first pipe piece at least practically make contact with the separating walls between the passages in the second pipe piece, characterized in that both pipe pieces have a round cross-section and that the boundary surface between the pipe pieces extends substantially as a sphere with the point of rotation of the pipe pieces as centre. 2. Connection as claimed in claim 1, characterized in that the second pipe piece is provided with a number of passages larger than two. 3. Connection as claimed in claim 2, characterized in that the number of passages in the second pipe piece is so large that the cross-section of the passages is at least two orders of magnitude smaller than the cross-section of the second pipe piece. 4. Connection as claimed in any of the foregoing claims, characterized in that the boundary surface towards the second pipe piece is concave. 5. Connection as claimed in any of the foregoing claims, characterized in that the diameter of the first pipe piece is smaller than that of the second pipe piece and that the first pipe piece connecting onto the boundary surface comprises a conical part. 6. Connection as claimed in claim 5, characterized in that the cross-section of the passages in the conical part is proportional to the cross-section of the conical part . 7. Connection as claimed in any of the foregoing claims, characterized in that both pipe pieces form part of an exhaust system of a motor vehicle. 8. Connection as claimed in claim 7, characterized in that the first pipe piece forms a connection between an engine of a motor vehicle and a catalytic converter, and that the second pipe piece is formed by a converter housing. 9. Connection as claimed in any of the foregoing claims, characterized in that the outer walls of the pipe pieces are coupled in mutually elastic manner . 10. Connection as claimed in claim 9, characterized in that the outer walls of the pipe pieces are each provided with a bent edge, which edges are coupled in mutually elastic manner. 11. Connection as claimed in any of the foregoing claims, characterized in that the first pipe piece comprises a passage located concentrically of the outer wall . 12. Connection as claimed in any of the foregoing claims, characterized in that at least one of the pipe pieces is provided with a sleeve arranged concentrically round the relevant pipe piece. 13. Connection as claimed in claim 12, characterized in that an insulating layer is arranged between the sleeve and the relevant pipe piece. 14. Connection as claimed in any of the foregoing claims, characterized in that at least one of the two pipe pieces is connected to the connection by means of a cone . 15. Connection as claimed in claim 8, characterized in that the catalytic converter is connected to the exhaust pipe on the outlet side of a connection as claimed in claim 1. 16. Connection as claimed in claim 15, characterized in that the boundary surfaces are convex on one side of the catalytic converter and concave on the other side of the converter.

Inventors: GROBBENHAAR HERMANUS GERHARDUS, GROBBENHAAR, HERMANUS, GERHARDUS
Applicants: GRAND PRIX SILENCERS BV, GROBBENHAAR HERMANUS GERHARDUS, GRAND PRIX SILENCERS B.V., GROBBENHAAR, HERMANUS, GERHARDUS
Application year: 1998
Main classification: F16L27
IPC codes: F01N3, F01N7, F16L27