JPH1122456A - Interlock pipe and flexible tube for automobile exhaust system using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible tube high in a practical value to satisfy all of demanded performances such as smallness, lightness, high displacement absorptivity and high durability by using an interlock pipe the tension compression directional characteristic of which is made proper by using the same molding die. SOLUTION: This flexible tube is constituted by forming bellows connected to a first and a second exhaust pipes and to absorb displacement of both of the exhaust pipes, an outer cylinder to cover the bellows, a coil spring coaxially arranged with the outer cylinder and interposed between an end part of the outer cylinder and a support collar and flat parts 14, 15 with bent parts 12, 13 arranged on their head end sides on an S shaped cross-section so that they are arranged on both sides by holding a central reversing part 16 in between. Additionally, an interlock pipe 8 having a contracted side regulating stopper 17 projected to rear sides of adjacent bent part outer bottoms 12b, 13b near to the central reversing part 16 of the flat parts 14, 15 and engaged with the bent parts 12, 13 is furnished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible tube for an automobile exhaust system having a bellows for absorbing a relative displacement between a first exhaust pipe attached to an engine side of an exhaust system for a vehicle and a second exhaust pipe attached to a muffler side. And the technical field of the interlock pipe used for it.

[0002]

2. Description of the Related Art Conventionally, as flexible tubes for automobile exhaust systems, for example, the following ones are known.

(1) Japanese Utility Model Application Laid-Open Publication No. Sho 61-187916 As shown in FIG. 9, a flexible tube described in this publication includes a bellows connected to an exhaust pipe, an outer blade arranged on the outer periphery of the bellows, and This configuration is provided with protectors provided at both ends of the outer blade for spot welding the outer blade and the bellows.

(2) Japanese Unexamined Utility Model Publication No. 2-144418 As shown in FIG. 10, a flexible tube described in this publication includes a bellows connected to an exhaust pipe, and spring branch pipes respectively arranged on outer circumferences of both ends of the bellows. And a spring material provided between the two spring branches.

(3) Japanese Unexamined Utility Model Publication No. 4-6523 The flexible tube described in this publication is, as shown in FIG. 11, arranged with a bellows connected to an exhaust pipe and an outer periphery of the bellows, and one end is fixed to the bellows. And a compression spring interposed between a clamp member fixed to the other end of the outer blade and a cylindrical body fixed to the bellows. (4) JP-A-6-117243 The flexible tube described in this publication has a bellows connected to an exhaust pipe and a bellows connected to the outer periphery of the bellows as shown in FIG. 12 and one end fixed to one end of the bellows. First
An outer cover, a second outer cover having one end fixed to the other end of the bellows and the other end disposed on the outer periphery of the bellows and the first outer cover, and a plurality of springs interposed between the first outer cover and the second outer cover. It is a configuration provided. (5) Japanese Unexamined Utility Model Publication No. 3-47421 As shown in FIG. 13, the flexible tube described in this publication is provided with a cylindrical shell over the entire outer periphery of the bellows via a wire mesh, and bends the support collar and the shell. The wire mesh is arranged also in the maze structure formed by the parts.

Further, as a conventional interlock pipe used for a flexible tube for an automobile exhaust system, for example, the following one is known.

(6) Japanese Unexamined Utility Model Publication No. Sho 60-34518 As shown in FIG. 14, the flexible tube for an exhaust pipe described in this publication has a tube material formed in a substantially S-shaped cross section and is located outside the flexible tube. The end portion and the end portion located inside have a folded portion so that the other end portions are engaged with each other and are spirally wound in the fitted state, and the end portions are connected to other ends. This is a configuration in which arc-shaped ridges projecting toward the projection are formed.

(7) Japanese Unexamined Utility Model Publication No. 60-67485 In the flexible pipe described in this publication, as shown in FIG. 15, the band-shaped plate member 6 is bent in an S-shape in the width direction thereof, and spirally wound. In this configuration, the S-shaped inner bent portion and the outer bent portion are engaged with each other, and the engaging pieces at the tips of the bent portions are formed so as to have a wavy cross section.

[0009]

However, in the above-mentioned conventional flexible tube for an automobile exhaust system,
Each has the problems listed below.

(1) In the flexible tube shown in FIG. 9, the spring constant of the flexible tube is greatly affected by the manufacturing variation of the outer blade, and the vibration displacement absorption characteristics vary. Further, an outer blade made by knitting a stainless steel wire is expensive. Therefore, the bellows having a large number of peaks used to secure the vibration displacement absorption characteristics increases the size, and the outer blade used to protect the bellows increases the cost.

(2) In the flexible tube shown in FIG. 10, since the central portion of the bellows is exposed to the outside, the bellows is easily damaged by stepping stones or the like, and the bellows is inferior in durability. Also, since the spring material protrudes greatly outward,
It becomes a flexible tube with a large outer diameter. If mud or the like adheres to the spring material that protrudes outward in a largely exposed state during running, the spring characteristics change, and the desired displacement absorption cannot be obtained.

(3) Since the flexible tube shown in FIG. 11 basically uses an outer blade made by knitting a stainless steel wire, it has the above-mentioned problem (1). In addition, the compression spring increases the absorbency against the tensile displacement, but cannot improve the absorbency against the compressive displacement.

(4) The flexible tube shown in FIG. 12 has a spring diameter plus an alpha-extending portion formed on the outer circumference of both the first and second outer covers disposed on the outer circumference of the bellows. The flexible tube has a large size, which is easily restricted by the installation location, and adversely affects the minimum ground clearance and road surface interference of the vehicle.

Also, since a plurality of springs are arranged in the circumferential direction of the bellows, adverse effects due to variations in spring characteristics, that is, a difference occurs in the spring constant in the bending direction in the left and right or up and down directions, resulting in uneven vibration absorbing force. Also, it is conceivable that a force in the bellows bending direction is applied when a tensile compression load is applied. Since the spring constant of the spring alone is designed to be relatively weak, the spring is shaken by the vibration of the exhaust system, so that interference noise with other parts is easily generated. Depending on the direction in which the bending or shearing force acts, there is a difference in the stress applied to both outer cylinders and the bellows, which is disadvantageous in terms of durability.

(5) In the flexible tube shown in FIG. 13, since the wire mesh is elastically deformed simultaneously with the deformation of the bellows, the spring constant of the flexible tube is the sum of the spring constant of the bellows and the spring constant of the wire mesh. , As the displacement increases. In particular, if the wire mesh enters the valley of the bellows due to partial deformation or the like, the spring constant increases with respect to the compression, so that the product may vary. In addition, there is a disadvantage that the weight increases due to the wire mesh, and that the bellows is hardly released to the outside.

Further, the conventional exhaust pipe flexible tube and flexible pipe have the following problems.

(6) The flexible tube for an exhaust pipe shown in FIG. 14 has a ridge, which prevents sharp edges of both ends from biting into a counterpart end to maintain flexibility. In addition, the flexible tube shown in FIG. 15 has an engaging piece having a wavy cross section, which also prevents an increase in surface contact force due to the removal of the distortion of the bent portion to achieve the desired elasticity and flexibility. In each case, the regulation of the direction of tension and compression is made by the pitch P shown in the figure. Since the pitch P is limited by the type used at the time of manufacturing, it is difficult to change the amount of restriction in the tension and compression directions in this state. Further, in the case of manufacturing products having different regulation amounts in the tension and compression directions, it is necessary to prepare dies suitable for the regulation amounts, which is uneconomical.

As described above, an interlock pipe is provided, which has advantages and disadvantages for each of them, and has a regulated amount in the direction of tension and compression adjusted to match the flexible tube for an automobile exhaust system, and is economically manufactured. The small size, light weight, low cost, high displacement absorption, and high durability required for the flexible tubes for automobile exhaust systems are not all satisfied, and the flexible tubes shown in FIG. There is a need for a new flexible tube that replaces the above.

An object of the present invention is to provide a vehicle exhaust system having a bellows for absorbing a relative displacement between a first exhaust pipe attached to an engine side of a vehicle exhaust system and a second exhaust pipe attached to a muffler side. Practical value that uses interlock pipes that are adjusted so that the amount of regulation in the tensile and compression directions matches the flexible tube, and that satisfies all the required performances of small size, light weight, low cost, high displacement absorption, and high durability It is to provide a flexible tube with high performance.

[0020]

[Means for Solving the Problems]

(Solution 1) In order to achieve the above object, in the invention according to claim 1, a continuous bent portion is provided on both edges of the band-shaped member so that the cross section in the width direction forms an S shape, and the band-shaped member is spirally wound. In an interlock tube formed in a cylindrical shape by slidably engaging adjacent bent portions in a spiral state, the S-shaped cross section is such that a flat portion in which the bent portion is disposed at the distal end is inverted at the center. A contraction-side regulating stopper formed to be disposed on both sides of the flat portion and protruding toward the center inversion portion of the flat portion and projecting rearward from the outer bottom of the adjacent bent portion engaged with the bent portion. It is characterized by.

For this reason, the interlock pipe has a pitch P
In the movement allowance is restricted by the bending portion tip and the bending portion inner bottom in the engaging portion, and the bending portion outer bottom and the compression side regulating stopper protruding to the rear side, when the interlock tube follows the load acting direction, After the interlock tube is displaced by a predetermined amount (movement allowance), the tip of the bent portion in the engaging portion and the inner bottom of the bent portion abut in the pulling direction operation, and the outer bottom of the bent portion and the compression side in the compression direction action. Since the restricting stopper abuts and cannot be displaced, it has displacement characteristics in the tension and compression directions according to the set position of the contraction side restricting stopper.

(Solution means 2) In the invention according to claim 2,
The flat part according to claim 1, further comprising an extension-side restricting stopper protruding forward of a front end of an adjacent bent part engaged with the bent part.

For this reason, the interlock pipe has a pitch P
In the inside, the movement margin is regulated by the bending part tip and the extension side restriction stopper protruding forward, and the bending part outer bottom and the compression side restriction stopper protruding rearward, so that the interlock pipe follows the load application direction. Then, after the interlock pipe is displaced by a predetermined amount (movement allowance), the tip of the bent portion comes into contact with the extension-side restricting stopper in the action of the pulling direction, and the outer bottom of the bent portion and the contraction side in the action of the compression direction. Since the restricting stopper abuts and cannot be displaced, it has displacement characteristics in the tension and compression directions according to the set positions of the contracting side restricting stopper and the extension side restricting stopper.

(Solution Means 3) In the invention according to claim 3,
Both ends are connected to the first exhaust pipe and the second exhaust pipe, a bellows for absorbing displacement of both exhaust pipes, an outer cylinder formed in a cylindrical shape that covers the outer periphery of the bellows with a plate material, A protector extending from the other end and having a tip fitted and fixed to the other end of the bellows, a support collar fitted and fixed to one end of the bellows, and one end arranged coaxially with the outer cylinder. A cylindrical coil spring fixed to the free end side of the outer cylinder and the other end locked to the support collar;
An interlock pipe according to claim 1 or an interlock pipe according to claim 2, which is disposed inside the bellows and has both ends of the pipe connected and fixed to both ends of the bellows.

Therefore, when the first exhaust pipe and the second exhaust pipe are displaced in the pipe axis direction and an external force acts on the flexible tube, the compressive load and the tensile load act on both the bellows and the coil spring.

For this reason, even if the thickness of the bellows is reduced and the spring constant of the bellows is set low, the total spring constant of the flexible tube can be compensated by the coil spring, and the size and weight of the flexible tube can be reduced. .

When an external force is applied to the first exhaust pipe and the second exhaust pipe so as to give a displacement in the pipe axis direction, the bellows and the coil spring are compressed or stretched to follow the direction in which the load acts, thereby absorbing the displacement. Is done. Since the coil spring is a single spring concentric with the bellows and has no difference in spring constant depending on the direction of bending deformation or shearing deformation, an external force which applies displacement in the bending direction or shear direction to the first exhaust pipe and the second exhaust pipe. Is applied, the bellows and the coil spring, which have a high degree of freedom of deformation, are absorbed by bending and shearing deformations uniformly following the direction of the load regardless of the direction of the external force. In other words, the displacement absorption effect using both the bellows and the coil spring is achieved, and there is no difference in the spring constant depending on the direction of bending deformation or shearing deformation. Is done.

Further, since the coil spring acts on both the compressive load and the tensile load, and the external force applied to the flexible tube is dispersed between the bellows and the coil spring, the load on the bellows is reduced.

When the bellows and the coil spring follow the acting direction of the load, the interlock tube also follows the displacement of the bellows, and the interlock tube moves by a predetermined amount (movement allowance).
After being displaced only, the end of the bent portion of the engaging portion and the inner bottom of the bent portion of the engaging portion come into contact with each other during the operation in the pulling direction, or the tip of the bent portion and the stopper on the extension side come into contact with each other. The bellows comes into contact with the side regulating stopper and cannot be displaced, so that the bellows is not allowed to be further displaced. Thus, the deformation of the bellows is prevented by the displacement limiting action of the interlock pipe.

In addition, if there is a stone splash during traveling, the bellows and the coil spring are prevented from being deformed or damaged by the protection effect of the outer cylinder.

(Solution 4) In the invention according to claim 4,
Both ends are connected to the first exhaust pipe and the second exhaust pipe, a bellows for absorbing displacement of both exhaust pipes, an outer cylinder formed in a cylindrical shape to cover an outer periphery of the bellows by a plate material, and both ends of the bellows A support collar fitted and fixed to each part, and a cylindrical coil spring disposed coaxially on both sides of the outer cylinder, one end of which is fixed to the end of the outer cylinder and the other end of which is locked to the support collar. And an interlock pipe according to claim 1 or both of which are disposed inside the bellows and both ends of the pipe are connected and fixed to both ends of the bellows.

Therefore, in addition to the effect of the third aspect of the present invention, the outer cylinder is completely elastically supported by the first and second coil springs when the outer cylinder is held at both ends, and stress is applied to the outer cylinder within the deformation range of the coil spring. Does not act, which is more advantageous in durability.

(Solution means 5) In the invention according to claim 5,
5. The flexible tube for an automobile exhaust system according to claim 3, wherein the two coil springs are formed such that the inner diameter of the small diameter portion is substantially equal to the outer diameter of the support collar, and the outer diameter of the large diameter portion is equal to the inner diameter of the outer cylinder. It is characterized in that it is a conical coil spring formed substantially identically.

The conical coil spring mounted between the outer cylinder and the support collar is stable because the small-diameter part is fitted to the support collar and the large-diameter part is fitted to the outer cylinder. Work is also easy.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) First, the configuration will be described.

The first embodiment corresponds to the first and fourth aspects of the present invention.

FIG. 1 is a half sectional view showing a flexible tube for an automobile exhaust system according to the first embodiment.

In FIG. 1, A1 is a flexible tube, 1 is a first exhaust pipe, 2 is a second exhaust pipe, 3 is a bellows,
4 is an outer cylinder, 6a is a first support collar, 6b is a second support collar, 7a is a first coil spring, 7b is a second coil spring, and 8 is an interlock tube.

The bellows 3 are connected to the first exhaust pipe 1 and the second exhaust pipe 2 at both ends, and are provided to absorb displacement of the exhaust pipes 1 and 2.

As a material of the bellows 3, a thickness of 0.
Using a thin multi-layered product in which two stainless steel thin plates with a thickness of 2 mm (conventionally 0.3 mm in thickness) are stacked, the number of peaks is greatly reduced (21 to 28 peaks → 8 to 9 peaks), and an equivalent spring is used. I have a constant.

The outer cylinder 4 is formed by a plate material into a cylindrical shape that covers the outer circumference of the bellows 3 over substantially the entire length thereof, and has a first cover 4a and a second cover 4b that are vertically divided into two parts at the center.
And are integrated by welding. The first cover 4a and the second cover 4b are bent inward by deep drawing, so that the first cover-side spring fixing portion 40 is bent.
a and the second cover-side spring fixing portion 40b.

The first support collar 6a and the second support collar 6b are connected (spot-welded) to both ends of the bellows 3, respectively.
a and 6b have a first support collar spring fixing portion 60a and a second support collar spring fixing portion 6 facing the inner surface of the outer cylinder 4.
0b is formed.

The first coil spring 7a and the second coil spring 7b are cylindrical coil springs having a constant winding diameter and arranged in parallel with the tube axis. The first coil spring 7a includes a first cover side spring fixing portion 40a and a first support. Color spring fixing part 60a
The outer end of the spring is fixedly connected to the first cover side spring fixing portion 40a by welding, and the inner end of the spring is indirectly supported and fixed to the first support collar spring fixing portion 60a. The second coil spring 7b is interposed between the second cover side spring fixing portion 40b and the second support collar spring fixing portion 60b, and the outer end of the spring is fixed to the second cover. The inner side end portion of the spring is indirectly supported and fixed to the second support collar spring fixing portion 60b by welding to the side spring fixing portion 40b. Note that the first and second support collar spring fixing portions 60 for supporting and fixing the above are provided.
The first and second bent portions 61a and 61b are formed at the ends a and 60b by slightly bending the ends in the axial direction.

As shown in FIGS. 1 and 2, the interlock pipe 8 is provided with continuous bent portions 12 and 13 on both edges of a band-shaped member 11 so that the cross section in the width direction forms an S-shape, and has a spiral shape. The bellows 3 is formed in a tubular shape having an outer diameter substantially equal to the inner diameter of the bellows 3 by slidably engaging the adjacent bent portions 13 and 12 in the spiral state. In addition, the S-shaped cross section has flat portions 14, 1 on which the bent portions 12, 13 are disposed on the tip side.
5 are formed so as to be disposed on both sides of the center reversing portion 16.

The flat portions 14 and 15 are formed by depressing one surface of the flat portion toward the center reversing portion 16 and extruding the flat portion toward the inner surface, so that the outside of the adjacent bent portion engaged with the bent portions 12 and 13 is formed. A contraction side regulating stopper 17 protruding from the rear inner surface side of the bottom 12b is provided. The contraction side regulating stopper 17 is arranged at least once a week for one flat portion.

The forming of the contraction side regulating stopper 17 is performed in a step different from the S-shaped forming step of the belt-shaped member. For this reason, even when manufacturing interlock tubes having different characteristics, the same mold is used for the S-shaped forming of the belt-shaped member, and only the extruded position is changed when forming the stopper.

In the engagement portion, the bellows 3 has the exhaust pipe 1,
2 is provided with a clearance (movement allowance) that allows only the displacement of the bellows 3 within the allowable range of the tensile / compressive stress, the bending stress, and the shear stress. , The inner bottom 13a of the bent portion 13 and the tip 12c of the bent portion 12
The compression direction is regulated by the clearance b between the adjacent bent portion outer bottom 12b and the contraction side regulating stopper 17 projecting rearward in the pitch P in the compression direction.

The pitch P and the clearances a and b are adjusted according to the specifications of the bellows 3. The both ends of the interlock tube 8 are connected (spot welding) to the inside of both ends of the bellows 3 respectively.

FIG. 3 is a perspective view showing an automobile exhaust system to which the flexible tube according to the first embodiment is applied.

In FIG. 3, A1 is a flexible tube, B is an exhaust pipe, C is a catalytic converter,
Is a sub-muffler, E is a main muffler, and the flexible tube A1 is provided in the middle of an exhaust pipe B connecting an engine (not shown) and the catalytic converter C, and absorbs a displacement due to an input from the engine or the vehicle body.

Next, the operation will be described.

[Setting Action of Spring Constant] In setting the spring constant of the flexible tube A1, as shown in FIG. 4, the spring constant of the bellows 3 is set to K1, and the spring constant of the first coil spring 7a and the second coil spring 7b is set. If the spring constant is K2,
Since the bellows 3 and both coil springs 7a and 7b are arranged in parallel, the flexible tube spring constant K is represented by the following equation.

K = K1 + (K2 / 2) As described above, if two of the spring constant K1 of the bellows 3, the spring constant K2 of both coil springs 7a and 7b, and the flexible tube spring constant K are clear, the remaining one is obtained. One spring constant is determined.

Therefore, the flexible tube spring constant K
When the spring constant K1 of the bellows 3 is set to a constant value, the spring constant K2 of the coil springs 7a and 7b which is easy to manage and has a high degree of freedom of selection is set from among a large number of values. Upon selection and determination, a desired flexible tube spring constant K is obtained.

As described above, the spring constant K1 of the bellows 3 is not changed by changing the spring constant K1 of the bellows 3 but by changing the spring constant K2 of the coil springs 7a and 7b. Can also be set to

As a result, as in the bellows 3 of the first embodiment, a two-layer product having a smaller thickness and a smaller number of peaks is used as the bellows material, and the spring constant K1 of the bellows 3 is set to a low constant value. The spring constant of both coil springs 7a and 7b
It can be supplemented by K2, and the size and weight of the flexible tube can be reduced.

[Displacement Absorbing Action] A description will be given of the displacement absorbing action when a load that gives a displacement to the first exhaust pipe 1 and the second exhaust pipe 2 is input from an engine or a vehicle body.

When a compression load is applied among the displacement loads, the bellows 3 is compressed and the first and second coil springs 7a,
7b is extended in the pulling direction, and both exhaust pipes 1 and 2 are compressed and displaced. That is, as shown in FIG. 4, when a compressive load is applied, the bellows installation span L1 becomes shorter by ΔL, and the coil spring installation span L2 becomes longer by ΔL / 2. When the bellows 3 is compressed, the outer bottoms 12b and 13b of the interlocking tube 8 and the contraction side regulating stoppers 17 and 17 are in contact with each other. Further displacement of the bellows 3 will be prevented.

When a tensile load acts on the displacement load, the bellows 3 is pulled and the first and second coil springs 7 are pulled.
A and 7b are shortened in the compression direction, and the two exhaust pipes 1 and 2 are tensilely displaced. That is, as shown in FIG. 4, when a tensile load is applied, the bellows mounting span L1 becomes longer by ΔL,
Each of the coil spring attachment spans L2 is shortened by ΔL / 2. When the bellows 3 is pulled, the interlock tube 8 is also pulled, and the bent portions of the interlock tube 8 are engaged with each other, and the bent ends 12c, 13c and the inner bottoms 12a, 13a are in contact with each other. As a result, further displacement of the bellows 3 is prevented.

That is, the first and second coil springs 7a and 7b exhibiting the same spring characteristics in both expansion and contraction of the bellows 3 and in tension and in compression, the displacement in which the tension and the compression are vibrated repeatedly in the tube axis direction. It will be absorbed neatly within the allowable stress range of the bellows 3.

Further, the first exhaust pipe 1 and the second exhaust pipe 2 include:
When the bellows 3 receives a displacement in the bending or shear direction, the interlock pipe 8 also receives a displacement in the bending or shear direction. It will be displaced within the range due to the shear direction clearance of the part. That is, also in this case, the bellows 3 having a high degree of freedom of deformation, the two coil springs 7a, 7b, and the interlock tube undergo bending deformation or shear deformation following the direction of the load, so that the bending displacement or shear displacement is reduced. Within the allowable stress range.

[Operation of Ensuring Bellows Durability] As described later, the durability of the bellows 3 is ensured by sharing the load, preventing extension and protection from stepping stones and the like.

The external force applied to the flexible tube A1 includes the force applied to the bellows 3 and the two coil springs 7a, 7b.
And the load applied to the bellows 3 is reduced.

Since the bellows 3 is always limited to a displacement within the range of the allowable stress by the displacement limiting action of the interlock tube 8, the bellows 3 is prevented from being deformed, and the durability is further improved. In addition, the first and second
Since the coil springs 7a and 7b are compressed, when an excessive tensile load is applied, the close contact between the adjacent strands of the first and second coil springs 7a and 7b serves as a displacement restricting stopper, which is a double deformation prevention measure.

Since the flexible tube A1 is exposed at the bottom of the vehicle, if a stone or the like is jumped by a tire while the vehicle is running, the flying stone or the like may collide with the flexible tube A1. In the case where a stepping stone or the like is present, the bellows 3 is prevented from being deformed or damaged by the protective action of the outer cylinder 4 covering the entire outer periphery of the bellows 3. still,
Since the outer cylinder 4 is arranged so as to cover the outer circumferences of the first and second coil springs 7a and 7b, deformation and damage of the first and second coil springs 7a and 7b against a stepping stone or the like are also prevented.

Next, the effects will be described.

(1) In the first embodiment, the first exhaust pipe 1
And a second exhaust pipe 2, both ends of which are connected to each other, and a bellows 3 for absorbing displacement of the exhaust pipes 1 and 2, an outer cylinder 4 formed in a cylindrical shape to cover an outer periphery of the bellows 3 with a plate material, A support collar 6a and a support collar 6b fitted and fixed to both ends of the bellows 3, respectively, are coaxially arranged on both sides of the outer cylinder 4, one end is fixed to the end of the outer cylinder 4, and the other end is the other end. Cylindrical coil springs 7a and 7b locked to the support collars 6a and 6b, and continuous bent portions 12 and 13 provided on both edges of the band-shaped member 11 so as to form an S-shaped cross section in the width direction, and spirally. In the spiral state, the adjacent bent portions 13 and 12 are slidably engaged with each other in a spiral state to form a tubular shape, and the S-shaped cross section arranges the bent portions 12 and 13 on the distal end side. Flat part 14 15 is formed so as to place on both sides of the central inverted portion 16, said a central inverted portion 16 toward the side bent portion of the flat portion 14, 15 12, 1
3 has a contraction side regulating stopper 17 protruding rearward of the outer bottoms 12b and 13b of the adjacent bent portions, and is disposed inside the bellows 3 and both ends of the pipe are connected and fixed to both ends of the bellows 3. Since the configuration includes the interlock tube 8, it is possible to provide a flexible tube A1 having a high practical value that satisfies all the required performances of small size, light weight, low cost, high displacement absorption, and high durability.

(2) When the bellows 3 is displaced by an external force, the interlock tube 8 also follows the displacement of the bellows 3, and the interlock tube 8 is moved by an amount set within the allowable stress range of the bellows 3. In other words, after the clearance a in the tension direction, the clearance b in the compression direction, and the clearance in the bending and shearing directions are displaced, the displacement becomes impossible and the bellows 3 is not allowed to further displace. Since the deformation of the bellows 3 is prevented by the displacement limiting action, the durability is further improved. By providing the interlock pipe 8 inside the bellows 3, the bellows 3 having a reduced number of peaks and the coil springs 7a and 7b that enable the bellows 3 are protected, and have an effect of preventing abnormal noise. The bellows temperature rise prevention effect is superior to that of the inner blade.

(3) The amount of displacement of the interlock tube 8 in the tension and compression directions can be set to various values depending on the depth of the bent portions 12 and 13 depending on the position of the stopper formed on the flat portions 14 and 15. Even if the S-shaped forming of the band-shaped member 11 is performed by the same mold, interlock tubes having various characteristics can be easily and economically obtained.

(4) Since the first coil spring 7a and the second coil spring 7b are cylindrical coil springs having a constant winding diameter and arranged parallel to the tube axis, the coil spring can be standardized, and the coil spring is manufactured and sold as a single coil spring. Off-the-shelf springs can be used.

(Embodiment 2) First, the configuration will be described.

FIG. 5 shows a flexible tube A for an automobile exhaust system according to a second embodiment corresponding to the first and third aspects of the present invention.
FIG.

The flexible tube A2 of the second embodiment is different from the flexible tube A1 of the first embodiment.
Is that the outer cylinder 4 is supported by a pair of first and second coil springs 7a and 7b, while one of the coil springs is omitted and the outer cylinder 4 is supported by a single coil spring 7 in a cantilever manner. This is different from the first embodiment.

With the omission of the one coil spring, the end of the outer cylinder 4 that is not supported by the coil spring 7 has a large diameter of the cylindrical protector 5 having a small diameter 5 a fixed to one end of the bellows 3. It is mounted in the part 5b and connected and fixed by spot welding.

The other configuration is the same as that of the first embodiment, and the description is omitted.

Next, in setting the spring constant, the flexible tube spring constant K is expressed by the following equation.

K = K1 + K2 Accordingly, the spring constant of the bellows 3 is the same as in the first embodiment.
If two of K1, the spring constant K2 of the coil spring 7, and the flexible tube spring constant K are clear, the remaining one spring constant is determined.

As a result, as in the first embodiment, a two-layer product having a smaller thickness and a smaller number of peaks than the conventional one is used as the bellows material, and the spring constant K1 of the bellows 3 is set to a low constant value. This can be compensated by the spring constant K2 of the coil spring 7, and the size, weight, and cost of the flexible tube can be reduced.

Next, the effects will be described.

In the second embodiment, the following effects are added to the effects (1) to (4) of the first embodiment.

(5) By omitting one of the coil springs, the number of parts can be reduced, and the cost of parts can be reduced.

(Embodiment 3) First, the configuration will be described.

FIG. 6 is a half sectional view showing a flexible tube A3 for an automobile exhaust system according to a third embodiment corresponding to the first, fourth and fifth aspects of the present invention.

In the flexible tube A3 according to the third embodiment, the first coil spring 7a and the second coil spring 7b have a winding diameter at one end (inside) substantially equal to the outer diameter of the protector, and a winding at the other end (outside). Embodiment 2 is different from Embodiment 1 in that a conical coil spring whose diameter substantially matches the inner diameter of the outer cylinder is used.

In accordance with this change in the coil spring, the outer cylinder 4 is made of an integral cylindrical material that is not divided into two parts, and the first cover side spring fixing portions 40a formed at both ends of the outer cylinder 4 in the first embodiment. And a portion corresponding to the second cover-side spring fixing portion 40b has first and second ends slightly bent inward.
The second bent portions 41a and 41b are provided, and are fixed to the inner peripheral surface side of the outer cylinder 4 by spot welding. The large-diameter ends of the coil springs 7a and 7b are attached to the first and second bent portions 41a and 41b. Fixing members 42a and 42b for pressing and fixing are provided. In addition, in the portions corresponding to the first support collar spring fixing portion 60a and the second support collar spring fixing portion 60b, bent portions 62a, which are formed by slightly bending the ends of the first and second support collars 6a, 6b outward. 62b, and first and second fixing members 63a, 63b fixed to the outer peripheral surfaces of the support collars 6a, 6b by spot welding and fixing the small-diameter side ends of the coil springs 7a, 7b to the bent portions 62a, 62b, respectively. Is provided.

The other configuration is the same as that of the first embodiment, and the operation is the same as that of the first embodiment.

Next, the effects will be described.

In the third embodiment, the following effects are added to the effects (1) to (3) of the first embodiment.

(6) A conical coil spring in which the first coil spring 7a and the second coil spring 7b are fitted to the outer diameter of the support collar at the small-diameter end and to the inner diameter of the outer cylinder at the large-diameter end. As a result, a stable mounting structure can be achieved with a simple structure.
Manufacture of the outer tube is facilitated, and the manufacturing cost of the flexible tube A3 can be reduced.

(Embodiment 4) First, the configuration will be described.

FIG. 7 is a half sectional view showing a flexible tube A4 for an automobile exhaust system according to a fourth embodiment corresponding to the first, third and fifth aspects of the present invention.

The flexible tube A4 according to the fourth embodiment is different from the flexible tube A3 according to the third embodiment.
Is that the outer cylinder 4 is supported by a pair of first and second coil springs 7a and 7b, while one of the coil springs is omitted and the outer cylinder 4 is supported by a single coil spring 7 in a cantilever manner. This is different from the third embodiment.

With the elimination of the one coil spring, the end of the outer cylinder 4 that is not supported by the coil spring 7 has a large diameter of the different diameter cylindrical protector 5 in which the small diameter portion 5a is fixed to one end of the bellows 3. It is mounted in the part 5b and connected and fixed by spot welding.

The other configuration is the same as that of the third embodiment, and the operation is also substantially the same as that of the third embodiment, so that the description will be omitted.

Next, the effects will be described.

In the fourth embodiment, the following effects are added to the effects of (1) to (3) of the first embodiment and (6) of the third embodiment.

(7) The same effect as in the above (5), that is, the omission of one of the coil springs reduces the number of parts and the cost of parts.

(Embodiment 5) First, the configuration will be described.

FIG. 8 is a sectional view showing a part of an interlock pipe 8a according to a fifth embodiment corresponding to the second aspect of the present invention.

The interlock tube 8a according to the fifth embodiment
In the first embodiment, the flat part 14 provided with the contraction-side regulating stopper 17 is provided, while the interlock tube 8 of the first embodiment causes the distal end of the bent part of the engaging part to abut on the inner bottom of the bent part when the interlock pipe 8 acts in the pulling direction. When the interlocking tube 8a is displaced in the pulling direction, the extension-side regulating stopper 18 is provided at 15 and protrudes forward of the distal end of the adjacent bent portion 13, 12 engaged with the bent portion 12, 13.
Embodiment 2 is different from Embodiment 1 in that elongation in the pulling direction is regulated by abutting the bent end portions 12c and 13c and the extension-side regulating stopper 18.

The extension-side restricting stopper 18 is also formed in a step different from the S-shaped forming of the belt-shaped member, and the displacement amount of the interlock tube 8a is determined by the pitch P from the extending-side restricting stopper 18 to the contraction-side restricting stopper 17. Is determined, the characteristics can be freely changed by changing the pitch P.

The remaining structure is the same as that of the interlock tube 8 of the first embodiment, and the state in which the tube is mounted on the flexible tube is the same as that of the first to fourth embodiments. I do.

Next, the effects will be described.

In the fifth embodiment, the following effect is added to the effect of (2) of the first embodiment.

(8) The same effect as (3) of the first embodiment, that is, the amount of displacement of the interlock tube 8a is
Since it is possible to regulate only the formation positions of the contraction side restriction stopper 17 and the extension side restriction stopper 18 to 4 and 15, even if the S-shaped molding of the belt-shaped member is performed by the same mold, the interlock pipe having various characteristics can be formed. Obtainable.

(Other Embodiments) In the embodiment, an example of the outer tube and the flexible tube having the first exhaust pipe having a circular cross section has been described. However, the same operation and effect can be obtained with an elliptical flexible tube. Can be

The number of the compression-side restriction stoppers 17 or the extension-side restriction stoppers 18 arranged in one spiral can be arbitrarily set.

[0109]

According to the flexible tube for an automobile exhaust system according to the first aspect of the present invention, a continuous bent portion is provided on both edges of the band-shaped member so as to form an S-shaped cross section in the width direction, and the tube is spirally wound. In an interlock tube formed in a tubular shape by slidably engaging adjacent bent portions in the spiral state, the S-shaped cross section has a flat portion in which the bent portion is disposed on the distal end side. A contraction-side restricting stopper formed so as to be disposed on both sides of the center reversing portion and protruding toward the center reversing portion of the flat portion and projecting rearward from the outer bottom of the adjacent bent portion engaged with the bent portion. Therefore, even if the S-shaped forming of the band-shaped member is performed with the same mold at the time of manufacturing the interlock pipe, it is only necessary to provide a small stopper at a predetermined position of the flat portion with respect to the depth of the bent portion. It is possible to obtain an interlock pipe characteristics. In the invention according to claim 2, claim 1
The flat portion described above is provided with an extension-side restricting stopper protruding forward of the tip of an adjacent bent portion engaged with the bent portion, so that the S-shaped forming of the belt-shaped member is the same when the interlock tube is manufactured. Even with the above-mentioned mold, interlock pipes having various characteristics can be obtained only by providing a pair of small stoppers at predetermined positions of the flat portion regardless of the depth of the bent portion.

According to the third aspect of the present invention, both ends of the bellows are connected to the first exhaust pipe and the second exhaust pipe, and the outer circumference of the bellows is covered with a plate material for absorbing displacement of both exhaust pipes and a plate material. A cylindrical outer cylinder, a protector extending from the other end of the outer cylinder and having a distal end fitted and fixed to the other end of the bellows, and a support fitted and fixed to one end of the bellows A collar, a cylindrical coil spring arranged coaxially with the outer cylinder and having one end fixed to the free end of the outer cylinder and the other end locked to the support collar; and a tube arranged inside the bellows. The interlock pipe according to claim 1 or the interlock pipe according to claim 2 having both ends connected and fixed to both ends of the bellows, so that a coil spring to be applied can be standardized,
An off-the-shelf spring manufactured and sold as a single coil spring can be used, and the bellows is always limited to a displacement within the allowable stress range by the displacement limiting action of the interlock pipe, so that the durability of the bellows is reduced. Further, it is possible to provide a flexible tube having a high practical value that satisfies all the required performances of small size, light weight, low cost, high displacement absorption, and high durability.

According to the fourth aspect of the present invention, both ends of the bellows are connected to the first exhaust pipe and the second exhaust pipe, and the outer circumference of the bellows is covered with a plate material for absorbing displacement of both exhaust pipes and a plate material. An outer cylinder formed in a tubular shape, a support collar fitted and fixed to both ends of the bellows, and coaxially arranged on both sides of the outer cylinder, one end of each being fixed to an end of the outer cylinder, and the like. 3. The interlock tube according to claim 1, wherein a cylindrical coil spring whose end side is locked to the support collar, and both ends of the tube are arranged inside the bellows and both ends of the tube are connected and fixed to both ends of the bellows. In addition to the above-described effects, an effect of providing a flexible tube with a reduced number of parts and a high practical value can be obtained.

According to the fifth aspect of the present invention, there is provided the third aspect.
5. The flexible tube for an automobile exhaust system according to claim 4, wherein the cylindrical coil spring is formed such that an inner diameter of the small diameter portion is substantially equal to an outer diameter of the support collar, and an outer diameter of the large diameter portion is substantially equal to an inner diameter of the outer cylinder. Since the conical coil springs are formed in the same manner, in addition to the effects described in the third or fourth aspect, there is no need to form a spring fixing portion by deep drawing, and the manufacturing cost of the flexible tube can be reduced. Is obtained.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a flexible tube for an automobile exhaust system according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a range indicated by P in FIG. 1;

FIG. 3 is a perspective view showing an automobile exhaust system to which the flexible tube according to the first embodiment of the present invention is applied.

FIG. 4 is an explanatory view of a spring absorbing action of the flexible tube for an automobile exhaust system according to the first embodiment of the present invention.

FIG. 5 is a half sectional view showing a flexible tube for an automobile exhaust system according to a second embodiment of the present invention.

FIG. 6 is a half sectional view showing a flexible tube for an automobile exhaust system according to a third embodiment of the present invention.

FIG. 7 is a half sectional view showing a flexible tube for an automobile exhaust system according to a fourth embodiment of the present invention.

FIG. 8 is an enlarged sectional view showing a part of an interlock tube according to a fifth embodiment of the present invention.

FIG. 9 is a half-sectional view showing a flexible tube for an automobile exhaust system of Conventional Example 1.

10 is a front view (a) and a side view (b) showing a flexible tube for an automobile exhaust system of Conventional Example 2. FIG.

FIG. 11 is a half sectional view showing a flexible tube for an automobile exhaust system according to a third conventional example.

FIG. 12 is a half sectional view showing a flexible tube for an automobile exhaust system of a fourth conventional example.

FIG. 13 is a half sectional view showing a flexible tube for an automobile exhaust system of a fifth conventional example.

FIG. 14 is a cross-sectional view showing a part of an interlock pipe used for a flexible tube for an automobile exhaust system according to Conventional Example 6.

FIG. 15 is a cross-sectional view showing a part of an interlock pipe used in a flexible tube for an automobile exhaust system according to a conventional example 7.

[Explanation of symbols]

 A1 to A4 Flexible tube 1 First exhaust pipe 2 Second exhaust pipe 3 Bellows 4 Outer cylinder 5 Protector 6, 6a, 6b Support collar 7, 7a, 7b Coil spring 8, 8a Interlock pipe 11 Strip-shaped member 12, 13 Bent portion 12a , 13a Inner bottom 12b, 13b Outer bottom 12c, 13c Tip 14, 15 Flat part 16 Center reversing part 17 Retraction-side restriction stopper 18 Extension-side restriction stopper

Claims (5)

[Claims] 1. A bent portion (12), (1) continuous with both edges of a band-shaped member (11) such that a cross section in the width direction forms an S-shape.
3) is provided and wound spirally, and in the spiral state, the adjacent bent portions (13) and (12) are slidably engaged with each other to form a tubular interlock tube. The S-shaped cross section is formed such that the flat portions (14) and (15) on which the bent portions (12) and (13) are disposed on the distal end side are disposed on both sides of the center reversing portion (16). A contraction side restriction that is located on the side of the flat portions (14) and (15) near the center reversing portion (16) and projects rearward of the outer bottom of the adjacent bent portion engaged with the bent portions (12) and (13). An interlock tube having a stopper (17). 2. An extension projecting forward of the front end of the adjacent bent portion (13, 12) engaged with the bent portion (12, 13) in the flat portion (14, 15). 2. The interlock tube according to claim 1, further comprising a side regulating stopper. 3. A bellows (3) having both ends connected to a first exhaust pipe (1) and a second exhaust pipe (2) for absorbing displacement of the exhaust pipes (1) and (2); An outer cylinder (4) formed in a tubular shape to cover the outer periphery of the bellows (3), and a distal end fitted to the other end of the bellows (3) extending from the other end of the outer cylinder (4). A protector (5) fitted and fixed; a support collar (6) fitted and fixed to one end of the bellows (3); and a coaxially arranged one end of the outer cylinder (4). ), A cylindrical coil spring (7) fixed to the free end and the other end locked to the support collar (6), and both ends of the pipe arranged inside the bellows (3) and the bellows (3). 3. The interlock pipe (8) according to claim 1, which is connected and fixed to both ends of the interlock pipe or the interro according to claim 2. Flexible tube for an automobile exhaust system, characterized in that it comprises click pipe (8a), a. 4. A bellows (3) having both ends connected to a first exhaust pipe (1) and a second exhaust pipe (2) for absorbing displacement of the exhaust pipes (1) and (2); An outer cylinder (4) formed in a tubular shape to cover the outer periphery of the bellows (3), a support collar (6a) and a support collar (6b) fitted and fixed to both ends of the bellows (3), respectively. A cylindrical shape which is coaxially arranged on both sides of the outer cylinder (4), one end of which is fixed to the end of the outer cylinder (4), and the other end of which is engaged with the support collars (6a), (6b); 2. The interlock pipe (8) according to claim 1, wherein said coil springs (7a) and (7b) are arranged inside said bellows (3), and both ends of said pipe are connected and fixed to both ends of said bellows (3). An interlock pipe (8a) according to claim 2. Flexible tube for an automobile exhaust system characterized. 5. The flexible tube for an automobile exhaust system according to claim 3, wherein the coil spring (7) or the coil spring (7) has a cylindrical shape.
Instead of a) and (7b), the inner diameter of the small diameter portion is formed to be substantially the same as the outer diameter of the support collar (6) or the support collars (6a) and (6b), and the outer diameter of the large diameter portion is changed to the outer cylinder (4). A flexible tube for an automobile exhaust system, characterized in that it is a conical coil spring formed to have substantially the same inner diameter as that of the above.