JP3841390B2 - Flexible pipe for vehicle exhaust pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible pipe structure including an interlock tube constituting an exhaust pipe of an automobile, and more particularly to a flexible pipe structure having a simple structure, low cost and excellent durability.
[0002]
[Prior art]
In an exhaust system of an automobile engine, a flexible pipe including an interlock tube has been widely used in a pipe connecting portion so as to absorb vibrations of the engine and a vehicle during running.
FIG. 3 shows an example of a conventional flexible pipe with an interlock tube.
With only the bellows pipe that can be expanded and contracted in the axial direction, the exhaust gas flowing inside it is disturbed by irregularities inside the bellows pipe, resulting in abnormal noise and noise, the heat insulation is poor and the bellows pipe becomes hot and the strength decreases, The bellows tube was not sufficiently durable against the axial compression / tensile load as well as the problem of causing heat damage to the bellows. A part of the compressive load in the axial direction is carried out, and a blade such as a wire net is usually provided on the outer peripheral part of the bellows to mainly carry a part of the tensile load, thereby improving the durability of the flexible pipe.
However, the conventional interlock tube is a straight shape with a uniform diameter that is configured to be able to expand and contract in the direction of the winding axis in a spiral shape by partially overlapping adjacent hook-shaped portions with a member having a cross-sectional shape formed in a hook shape. The inner pipe 6 is welded and joined to both ends, and the inner pipe is fixed to the bellows pipe connecting part. This not only increases the number of parts and costs, but also connects the interlock tube and the inner pipe. There was a problem that the flow of the exhaust gas was disturbed at the stepped portion, resulting in abnormal noise. Particularly in terms of durability, the cross-sectional shape is formed in a bowl shape, and the clearance between adjacent hook-like portions is substantially the same over the entire length of the interlock tube. Above the displacement, an abrupt compressive load is applied, and vibration and noise are deteriorated by shock input, and the durability of the interlock tube is deteriorated.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a flexible pipe for an exhaust pipe of an automobile which has a simple structure with a small number of parts and is lightweight and low in cost and excellent in vibration durability.
[0004]
[Means for Solving the Problems]
Measure taken by the present invention for solving the above problems is to place a blade having a flexible extensible bellows tube in the axial direction and its outer periphery, the cross-sectional shape on the inner peripheral side of the bellows pipe the barbs formed in a hook shape of a substantially S-shaped, flexible pipe exhaust pipe having an interlock tube with a telescopically configured hooked parts adjacent to each other in the winding axis direction spirally was partially overlapped The diameter of the interlock tube is gradually increased and expanded in the connecting direction, and is fixed to the inner periphery of the connecting portion of the bellows tube, and the diameter of the saddle-like overlapping portion adjacent to each other of the interlock tube connecting portion is By gradually changing the clearance (a) in the direction toward the coupling direction so as to be smaller than the radial clearance (b) of the flange-like overlapping portion of the general portion that has not been expanded, the saddle-like overlapping Wherein the allowed part sliding resistance are to varying removal.
By adopting such a structure, when the interlock tube is displaced in the axial compression direction, the radial clearance of the adjacent saddle-shaped portion gradually changes between the general portion of the interlock tube and the connecting portion at both ends. Therefore, the sliding resistance gradually changes, and the change of the compression load with respect to the displacement amount in the compression direction of the interlock tube becomes gentle as shown in FIG. That is, the impact force on the interlock tube is alleviated, and the durability is improved as well as the vibration and noise are reduced.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows an enlarged view of the vicinity of the interlock tube connecting portion. The flexible pipe 1 is composed of a bellows tube 2, an interlock tube 3 and a blade 4, and the bellows tube is composed of a bellows portion 21 and a bellows connecting portion 22, and the outer periphery of the bellows is connected to a blade connecting portion 42 of the blade 4 made of mesh wire or the like. The bellows connecting portion 22 and the outer ring 5 are attached to protect the outside of the bellows and carry a part of the tensile load.
On the other hand, on the inner peripheral side of the bellows tube, a hook-shaped member 31 having a hook- shaped substantially S-shaped cross - section is spirally wound while being partially overlapped by adjacent hook-shaped overlapping portions 31a . While the diameter of the interlocking tube connecting portion 32 is gradually increased, the radial clearance a of the bowl-shaped overlapping portion 31a is gradually smaller than the radial clearance b of the general portion. In FIG. 2, the clearance is expressed larger than the actual size for the sake of clarity. Further, pipes to be connected (not shown) are inserted inside both ends of the flexible pipe 1, and the interlock tube and the bellows pipe are connected by resistance welding or fusion welding.
When a compressive load in the axial direction is applied to the flexible pipe, the hook-like overlapping portions of the hook- like parts adjacent to the interlock tube slide relative to each other, and a compressive displacement occurs beyond the axial clearance c between the hook-like parts, that is, more than the close contact. A compression load is applied to the interlock tube, but the radial clearance of the overlapping portion of the hooked portion of the interlock tube connecting portion is gradually changing, so the sliding resistance is also gradually changed and the compression load is gradually reduced. Will rise. That is, the impact on the interlock tube with respect to vibration is alleviated and durability is improved.
[0006]
【The invention's effect】
According to the present invention, the diameter of both ends of the interlock tube and the clearance of the adjacent hook-like portion are gradually changed and expanded and directly fixed to the inner periphery of the connecting portion of the bellows pipe, so that the conventional inner pipe can be eliminated. Lightweight and inexpensive. Also, there is no step between the conventional interlock tube and inner pipe, the flow of exhaust gas is smooth, and abnormal noise and increase in exhaust gas internal pressure can be suppressed.
In particular, the impact on the interlock tube against vibration is alleviated and durability is improved, and so-called N, V, and H can be reduced, and the riding comfort of the automobile is improved.
[Brief description of the drawings]
FIG. 1 shows a flexible pipe according to the present invention.
FIG. 2 is an enlarged cross-sectional view of the vicinity of a connecting portion of an interlock tube of a flexible pipe according to the present invention.
FIG. 3 shows a conventional example.
FIG. 4 shows a graph of axial compressive displacement and compressive load in an interlock tube.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Flexible pipe 2 ... Bellows pipe 21 ... Bellows part 22 ... Bellows pipe connection part 3 ... Interlock tube 31 ... Member 32 ... Interlock tube connection part 4 .... Blade 5 ... Outer ring 6 ... Inner pipe a ... Radial clearance b adjacent to the gradually changing part of the interlock tube diameter b ... Interlock tube in general Clearance in the radial direction of the adjacent hook-shaped part of the part c ... Clearance in the axial direction of the adjacent hook-shaped part of the interlock tube

Claims (1)

Place the blade having axially extensible bellows tube and flexibility to the outer peripheral side thereof, a hook-like member formed with cross-sectional shape in a hook shape of a substantially S-shaped in the inner peripheral side of the bellows tube, In flexible pipes for exhaust pipes with interlock tubes that are configured to be able to expand and contract in the direction of the winding axis by overlapping the adjacent saddle-shaped portions in a spiral shape, gradually reduce the diameter of the interlock tubes toward the connecting direction. Non-expanded general part with variable diameter and expansion, fixed to the inner periphery of the connecting part of the bellows tube, and the radial clearance (a) of the hooked overlapping parts adjacent to each other of the interlock tube connecting part be characterized in that the are divided varying the so the sliding resistance of the hook-shaped overlapping portions by causing gradual change toward the connecting direction so as to be smaller than the hook-shaped overlapping portions radial clearance (b) Flexible pipe for an exhaust pipe of the vehicle.

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