JPH10266840A - Automobile exhaust flexible tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly practical automobile exhaust flexible tube which absorbs relative displacement between a first exhaust pipe fixed to an engine side and a second pipe fixed to a muffler, and satisfies all required performances such as compactness and lightness, low-cost, high displacement absorptivity, and high durability. SOLUTION: This automobile exhaust flexible tube is equipped with a bellows 3 which is connected with first and second exhaust pipes 1, 2 and absorbs displacement of the two exhaust pipes, an outer cover 5 which covers the periphery of the bellows 3 and has one end which is fixed on one end of the bellows 3, a protector 7 which is connected with the other end of the bellows 3, a coil spring 6 of which a beginning end is fixed to the protector 7 between another end of the outer cover 5 and the protector 7, and an interlock pipe 8 in which many rings arranged along the inner diameter of the bellows 3 are provided and connected with moving margins for tension/expansion, bending, and shearing direction.

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. Belongs to the technical field.

[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 Laid-Open Publication No. 61-187916 The flexible tube described in this publication includes, as shown in FIG. 8, a bellows connected to an exhaust pipe, an outer blade arranged on the outer periphery of the bellows, 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. 9, 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 As shown in FIG. 10, the flexible tube described in this publication is provided 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 As shown in FIG. 11, the flexible tube described in this publication has a bellows connected to an exhaust pipe, and is arranged on the outer periphery of the bellows, and one end is fixed to one end of the bellows. A plurality of first outer covers, 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 the first outer covers and the second outer cover interposed therebetween. This is a configuration including a spring.

[0006]

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. 8, the spring constant of the flexible tube is largely affected by manufacturing variations 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. 9, since the central portion of the bellows is exposed to the outside, the bellows is easily damaged by a stepping stone or the like, and the bellows is inferior in durability.

Further, since the spring member protrudes largely outward, a flexible tube having a large outer diameter is obtained. 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. 10 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) In the flexible tube shown in FIG. 11, the outer circumference of the first and second outer covers disposed on the outer circumference of the bellows is further provided with a projecting portion having a spring diameter plus an alpha. 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.

Further, 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 covers and bellows, which is disadvantageous in terms of durability.

As described above, each of them has advantages and disadvantages, and does not satisfy all the performances required for a flexible tube for an automobile exhaust system such as small size, light weight, low cost, high displacement absorption, and high durability. The emergence of a new flexible tube that replaces the generally employed flexible tube shown in FIG. 8 is being demanded.

An object of the present invention is to provide a vehicle exhaust system having a bellows for absorbing 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. It is an object of the present invention to provide a flexible tube having a high practical value that satisfies all required performances of a flexible tube, such as small size, light weight, low cost, high displacement absorption, and high durability.

[0015]

[Means for Solving the Problems]

(Solution 1) In order to achieve the above object, in the invention according to claim 1, both ends are connected to a first exhaust pipe and a second exhaust pipe, and a bellows that absorbs displacement of both exhaust pipes and a plate material are used. An outer cover having a cylindrical shape covering the outer periphery of the bellows, one end of which is fixed to one end of the bellows; a protector connected to the other end of the bellows; A coil spring interposed between the free end side of the outer cover and the protector, and both ends of the spring are fixedly connected to the outer cover and the protector, respectively, and a number of rings are stretched / compressed and bent along the inner diameter of the bellows. And an interlock pipe having both ends fixed to both ends of the bellows in a state of being integrated into a tubular shape with an allowance for movement in the shearing direction. And wherein the door.

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 to give a displacement in the pipe axis direction, the bellows and the coil spring are compressed or pulled 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.

Furthermore, the coil spring acts on both a compressive load and a tensile load, and the external force applied to the flexible tube is dispersed between the bellows and the coil spring, so that 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 the displacement, the bellows cannot be displaced and the bellows is not allowed to further displace, and the deformation of the bellows is prevented by the displacement limiting action of the interlock tube.

In addition, if there is a stone jump during traveling, the bellows and the coil spring are prevented from being deformed or damaged by the protective action of the outer cover.

(Solution means 2) In the invention according to claim 2,
A bellows having both ends connected to the first exhaust pipe and the second exhaust pipe for absorbing displacement of the two exhaust pipes, an outer cover formed in a tubular shape to cover an outer periphery of the bellows with a plate material,
A first protector and a second protector respectively connected to both ends of the bellows, and one end of the outer cover and a first protector inside the outer cover, and both ends of the spring are respectively connected to the outer cover and the first protector. A first coil spring fixedly connected, and a second coil spring interposed between the other end of the outer cover and a second protector inside the second coil spring, and both ends of the spring fixedly connected to the outer cover and the second protector, respectively. A number of rings are provided along the inner diameter portion of the bellows with predetermined movement allowances in the tension / compression direction, the bending direction, and the shearing direction, and are connected in a tubular shape so that both ends are joined at both ends of the bellows. And an interlock pipe fixed to the section.

Therefore, in addition to the effect of the invention described in the first aspect, the outer cover is completely elastically supported by the first and second coil springs when the outer cover is held at both ends, and stress acts on the outer cover in the deformation range of the coil spring. This is more advantageous in terms of durability.

(Solution Means 3) In the invention according to claim 3,
3. The flexible tube for an automobile exhaust system according to claim 1, wherein the coil spring or the first coil spring and the second coil spring are cylindrical coil springs having a constant winding diameter and arranged in parallel to a tube axis. I do.

(Solution means 4) In the invention according to claim 4,
3. The flexible tube for an automobile exhaust system according to claim 1, wherein a winding diameter of one end of the coil spring or the first coil spring and the second coil spring substantially coincides with an outer diameter of the protector, and a winding diameter of the other end. Is a conical coil spring substantially matching the inner diameter of the outer cover.

(Solution means 5) In the invention according to claim 5,
5. The flexible tube for an automobile exhaust system according to claim 1, wherein the ring forming the interlock pipe has a hook having a substantially J-shaped cross section at one edge and the one at the other edge. Has a hook opposite to the hook on the edge of
In addition, both hooks have gaps that can be displaced in the tension / compression direction, the bending direction, and the shearing direction of the rings with the hooks of the adjacent rings locked.

When the interlock tube is displaced in the tension / compression direction, bending direction, or shearing direction due to the displacement of the bellows, the interlock tube is smoothly displaced within the gap in the hook portion which is locked together, and the hook portion is moved in the gap. When they abut each other, the interlock tube cannot be further displaced in that direction, protecting the bellows and preventing deformation until the acting force is removed.

[0028]

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 second, third, and fifth 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,
5 is the outer cover, 6 'is the first coil spring, and 6 "is the second coil spring.
A coil spring, 7 'is a first protector, 7 "is a second protector, and 8 is an interlock tube.

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

The bellows 3 is made of a material having a thickness of 0.1 mm.
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 cover 5 is formed by a plate material into a tubular shape that covers the outer periphery of the bellows 3 over substantially the entire length thereof, and the first cover 51 and the second cover 52, which are vertically divided at the center, are welded. It is configured integrally. By bending the ends of the first cover 51 and the second cover 52 inward by deep drawing, the first cover-side spring fixing portion 5a 'and the second cover-side spring fixing portion 5a "are formed. .

The first protector 7 'and the second protector 7 "are connected (spot-welded) to both ends of the bellows 3, respectively. Both protectors 7' and 7"
A first protector-side spring fixing portion 7a 'and a second protector-side spring fixing portion 7a "facing the inner surface of the outer cover 5 are formed.

The first coil spring 6 'and the second coil spring 6 "are cylindrical coil springs having a constant winding diameter and arranged parallel to the tube axis. The first coil spring 6' is a first cover side spring fixing portion 5a '. And the first protector-side spring fixing portion 7a ', the outer end of the spring is fixedly connected to the first cover-side spring fixing portion 5a' by welding, and the inner end of the spring is connected to the first protector side. The second coil spring 6 "is provided in a state of being supported and fixed to the spring fixing portion 7a 'by welding, and the second cover-side spring fixing portion 5a" and the second protector are similar to the first coil spring 6'. It is supported and fixed between the side spring fixing portion 7a ″. Note that the first and second coil springs 6 ', 6 "are also fixed at the respective fixed portions 5a', 5a", 7 ".
For a ′, 7a ″, not only welding but also other fixing means such as caulking can be widely used.

As shown in FIGS. 1 and 2, the interlock tube 8 has a number of rings 81, 82, which have an outer diameter substantially equal to the inner diameter of the bellows (3) and are formed in the same shape.
83, 84 ... are connected on the same axis.
The connecting portion is described, for example, around the ring 82. One edge is provided with a hook portion 82a bent into a substantially J-shaped cross section, and the other edge is provided with the hook portion 82a of the one edge.
A hook 82b bent in a direction opposite to the direction a is provided.
The hooks 82a on the one side, which are opposite sides, are inserted with hooks 81b opposite to the adjacent ring 81, and the hooks 82b on the other side, opposite sides, hook the hooks of the adjacent ring 83. The part 83a is inserted. When the bellows 3 absorbs the displacement of the exhaust pipes 1 and 2, the connecting portion is provided with a clearance (movement allowance) that allows only the displacement of the bellows 3 within an allowable range of the tensile / compression stress, the bending stress, and the shear stress. In the tension / compression direction, the rings are arranged uniformly on the same axis in the tube axis direction, that is, between the tip 82a 'of the hook portion 82a and the inner bottom portion 81b "of the hook portion 81b. , A clearance a is provided between the tip 81b 'of the hook 81b and the inner bottom 82a "of the hook 82a. In addition, the shear direction is set in the internal space of the hook 82b,
Clearances b and b are provided between the thicknesses in the direction orthogonal to the pipe axis of the pipe, and the bending directions are the clearances b and b and the hooks 82a and 8 from the bottom of the hook 82a.
It is provided with a length c up to the center of the reversal portion from 2b. The clearances a, b, and c are adjusted according to the specifications of the bellows 3. And this 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, D
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 Operation 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 first coil spring 6 'and the second coil spring 6 are set. Let K2 be the spring constant of
Since the bellows 3 and both coil springs 6 'and 6 "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 6 'and 6 ", and the flexible tube spring constant K are clear, the remaining 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 6 'and 6 "which is easy to manage and has a high degree of freedom of selection is set to a large value. By selecting from among them, a desired flexible tube spring constant K can be obtained.

Thus, the spring constant K1 of the bellows 3 is changed not by changing the spring constant K1 of the bellows 3 but by changing the spring constant K2 of the coil springs 6 'and 6 ". It can also be set to a constant value.

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 6 'and 6 "
It can be supplemented by K2, and the size and weight of the flexible tube can be reduced.

[Displacement Absorbing Action] 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 the engine or the vehicle body will be described.

When a compressive load is applied among the displacement loads, the bellows 3 is compressed and the first and second coil springs 6 ',
6 "is extended in the pulling direction and the two 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 is shortened by ΔL, and the coil spring installation span L2 is respectively reduced. When the bellows 3 is compressed, the edges of the rings 81, 82, 83,... Of the interlock tube 8 come into contact with each other, so that the bellows 3 is further extended. Displacement will be prevented.

When a tensile load is applied among the displacement loads, the bellows 3 is pulled and the first and second coil springs 6 'and 6 "are shortened in the compression direction, and the two exhaust pipes 1 and 2 are tensilely displaced. 4, when a tensile load is applied, the bellows installation span L1 becomes longer by ΔL and the coil spring installation spans L2 become shorter by ΔL / 2, respectively. 8 are also pulled, and in the connection portion between the rings, taking one connection portion as an example, the tips 81b 'and 82a' of the hook portions are respectively connected to the inner bottom portion 82.
a ", 81b", the bellows 3 is displaced within the range of the total of the clearance a in the tube axis direction set within the allowable stress of the bellows 3.

That is, the first and second coil springs 6 ′ and 6 ″ exhibiting the same spring characteristics both in expansion and contraction of the bellows 3 and in tension and compression, and the tension and compression are vibrated repeatedly in the tube axis direction. The displacement is neatly absorbed within the range of the allowable stress of the bellows 3.

The first exhaust pipe 1 and the second exhaust pipe 2 include:
When an external force acts to give a displacement in a bending direction or a shearing direction other than the pipe axis direction, and the bellows 3 receives the bending displacement, the interlock pipe 8 also receives the bending displacement, and the hook portions 82b and 83a Respectively rotate only in the mutual space, the bellows 3 is displaced within the range defined by the clearance b in the direction perpendicular to the tube axis and the clearance c in the tube axis direction. Further, when the bellows 3 is subjected to shear displacement, the interlock pipe 8 is also subjected to shear displacement, and the hook portions 82b and 83a are displaced in the direction perpendicular to the pipe axis only in the mutual space at the connection portion. 3 is displaced within the range of the clearance b. That is, also in this case, the bellows 3 having a high degree of freedom of deformation and the two coil springs 6 ′ and 6 ″ are bent or sheared by following the direction in which the load acts, so that the bellows 3 is allowed to bend and shear. It is neatly absorbed within the range of stress.

[Operation of Ensuring Bellows Durability] As will be described later, the durability of the bellows 3 is ensured by the sharing of the load, the prevention of stretching, and the 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 6 ', 6 ".
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 pipe 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 6 'and 6 "are compressed, when an excessive tensile load is applied, the close contact between the adjacent wires of the first and second coil springs 6' and 6" serves as a displacement restricting stopper, and a double deformation prevention measure is provided. Becomes

Since the flexible tube A1 is disposed at the bottom of the vehicle so as to be exposed, when a stone or the like is hit 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, deformation or damage of the bellows 3 is prevented by the protective action of the outer cover 5 covering the entire outer periphery of the bellows 3. In addition, since the outer cover 5 is also arranged to cover the outer circumferences of the first and second coil springs 6 'and 6 ", the deformation and damage of the first and second coil springs 6' and 6" to a stepping stone or the like are also prevented. .

Next, the effects will be described.

(1) A bellows 3 having both ends connected to the first exhaust pipe 1 and the second exhaust pipe 2 for absorbing the displacement of the exhaust pipes 1 and 2, and a cylinder covering the outer periphery of the bellows 3 with a plate material. Of the outer cover 5, the first protector 7 ′ and the second protector 7 ″ respectively connected to both ends of the bellows 3, and the one end side of the outer cover 5 and the first protector 7 ′ inside thereof. A first coil spring 6 'interposed therebetween and having a spring start end fixedly connected to a first protector 7'; a second coil spring 6 'at the other end of the outer cover 5;
A second coil spring 6 ″ interposed between the protector 7 ″ and having a spring start end fixedly connected to the second protector 7 ″;
A state in which a large number of rings are provided with clearances (predetermined movement allowances) a, b, and c in the tension / compression direction, the bending direction, and the shearing direction along the inner diameter portion of the bellows 3, and are integrally connected in a cylindrical shape. And an interlock tube 8 having both ends fixed to both ends of the bellows 3, so that the practical value that satisfies all the required performances of small size, light weight, low cost, high displacement absorption and high durability. The flexible tube A1 with high height can be provided.

(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 set within the allowable stress range of the bellows 3. After being displaced by an amount, ie, a clearance a in the tension / compression direction and a clearance b, c in the bending and shearing directions, the bellows 3 cannot be displaced.
No further displacement is allowed, and the deformation of the bellows 3 is always prevented by the displacement limiting action of the interlock tube 8, so that the durability is further improved.

By providing the interlock tube 8 inside the bellows 3, the bellows 3 having a reduced number of peaks and the coil springs 6 'and 6 "enabling the bellows 3 can be protected, and the noise prevention effect can be obtained. In addition, the bellows is more effective in preventing the temperature rise of the bellows than the conventional inner blade.

(3) Since the first coil spring 6 ′ and the second coil spring 6 ″ are cylindrical coil springs having a constant winding diameter and arranged in parallel to the tube axis, an off-the-shelf spring manufactured and sold as a single coil spring is used. be able to.

(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.
Has a pair of first and second coil springs 6 ′ and 6 ″ to support the outer cover 5 in a doubly supported manner, while omitting one of the coil springs and supporting the outer cover 5 in a cantilevered manner with a single coil spring 6. This is different from the first embodiment.

With the omission of the one coil spring, the end of the outer cover 5 that is not supported by the coil spring 6 is connected to the large-diameter portion of the cylindrical protector 10 having the small-diameter portion 10a fixed to one end of the bellows 3. It is mounted inside 10b 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 Therefore, as in the first embodiment, the spring constant of the bellows 3 is
If two of K1, the spring constant K2 of the coil spring 6, 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 6, 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 (3) of the first embodiment.

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

In the flexible tube A3 according to the third embodiment, the first coil spring 6 'and the second coil spring 6 "have a winding diameter at one end (inside) substantially equal to the outer diameter of the protector, and the other end (outside). Embodiment 1 in that a conical coil spring whose winding diameter substantially matches the inner diameter of the outer cover is used.
And different.

With the change of the coil spring, the outer cover 5
Is a first cover side spring fixing portion 5 formed at both ends of the outer cover 5 using an integral cylindrical material that is not divided into two.
a 'and the second cover side spring fixing portion 5a "are fixed by spot welding to the bent portions 53' and 53" whose ends are bent slightly inward and the inner peripheral surface side of the outer cover 5 and are bent. The first and second protector-side spring fixing portions 7a 'and 54 "are formed with fixing members 54' and 54" for pressing and fixing the large-diameter ends of the coil springs 6 'and 6 "to the portions 53' and 53". The fixing portion 7a "is formed by bending the end portions slightly outwardly, and fixed to the outer peripheral surface of the protector 7 by spot welding.
1 ', 71 "and fixing members 72', 72" for fixing the small-diameter end portions of the coil springs 6 ', 6 ".

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 of (1) and (2) of the first embodiment and (4) of the second embodiment.

(5) The first coil spring 6 ′ and the second coil spring 6 ″ are conical coil springs in which the winding diameter at the start end is substantially equal to the outer diameter of the protector and the winding diameter at the end is substantially equal to the inner diameter of the outer cover. Also, deep drawing becomes easy, and the manufacturing cost of the flexible tube A3 can be reduced.

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

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

The flexible tube A4 of the fourth embodiment is different from the flexible tube A3 of the third embodiment.
Has a pair of first and second coil springs 6 ′ and 6 ″ to support the outer cover 5 in a doubly supported manner, while omitting one of the coil springs and supporting the outer cover 5 in a cantilevered manner with a single coil spring 6. This is different from the third embodiment.

With the omission of the one coil spring, the end of the outer cover 5 that is not supported by the coil spring 6 is connected to the large-diameter portion of the cylindrical protector 10 having the small-diameter portion 10a fixed to one end of the bellows 3. It is mounted inside 10b 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 is omitted.

Next, the effects will be described.

In the second embodiment, the following effects are added to the effects of (1) and (2) of the first embodiment and (5) of the third embodiment.

(6) The same effect as in (4) above, that is, the omission of one of the coil springs reduces the number of parts and the cost of parts.

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

[0089]

According to a first aspect of the present invention, there is provided a flexible tube for an automobile exhaust system, wherein both ends are connected to a first exhaust pipe and a second exhaust pipe, and a bellows for absorbing displacement of both exhaust pipes, and a plate material. And an outer cover having one end fixed to one end of the bellows, a protector connected to the other end of the bellows, and a coaxial shaft with the outer cover. A coil spring interposed between the free end side of the outer cover and the protector, and both ends of the spring are fixedly connected to the outer cover and the protector, respectively, and a number of rings extend along the inner diameter of the bellows in the tension and compression directions. An interlock having both ends fixed to both ends of the bellows in a state where a predetermined movement allowance in the bending direction and the shearing direction is given and the tube is connected and integrated. Due to a configuration that includes a tube, a,
It is possible to standardize a coil spring to be applied, and it is possible to provide a flexible tube having a high practical value that satisfies all required performances of small size, light weight, low cost, high displacement absorption, and high durability.

According to the second 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 that absorbs displacement of the two exhaust pipes. A cylindrical outer cover, a first protector and a second protector respectively connected to both ends of the bellows, and interposed between one end of the outer cover and a first protector inside the outer cover; Parts which are fixedly connected to the outer cover and the first protector, respectively.
A second coil spring interposed between the coil spring, the other end of the outer cover and the second protector inside the outer cover, and both ends of the spring fixedly connected to the outer cover and the second protector, respectively; A number of rings are provided with predetermined movement allowances in the tension / compression direction, the bending direction, and the shearing direction along the length of the bellows, and both ends are fixed to both ends of the bellows in a state of being integrally connected in a cylindrical shape. With the configuration including the lock tube, the durability of the outer cover can be improved in addition to the above effects.

In the invention according to claim 3, claim 1
3. The flexible tube for an automobile exhaust system according to claim 2, wherein the coil spring or the first coil spring and the second coil spring are connected to each other.
Since the coil spring is a cylindrical coil spring having a constant winding diameter and arranged in parallel to the tube axis, in addition to the above-described effects, an off-the-shelf spring manufactured and sold as a single coil spring can be used.

According to the fourth aspect of the present invention, there is provided the first aspect.
3. The flexible tube for an automobile exhaust system according to claim 2, wherein the coil spring or the first coil spring and the second coil spring are connected to each other.
The coil spring is a conical coil spring in which the winding diameter at one end is substantially equal to the outer diameter of the protector and the winding diameter at the other end is substantially equal to the inner diameter of the outer cover. And the manufacturing cost of the flexible tube can be kept low.

In the fifth aspect of the present invention, the first aspect
5. The flexible tube for an automobile exhaust system according to claim 4, wherein the ring forming the interlock pipe has a hook portion having a substantially J-shaped cross section at one edge and the one edge at the other edge. 6. The hooks have hooks opposite to the hooks, and both hooks have gaps that can be displaced in the tension / compression direction, bending direction, and shearing direction of the rings with the hooks of the adjacent rings locked. In addition to the above effects,
Since the bellows is always limited to a displacement within the range of the allowable stress by the displacement limiting action of the interlock pipe, the durability of the bellows can be further improved.

[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 a half sectional view showing a flexible tube for a vehicle exhaust system according to Conventional Example 1.

9 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. 10 is a half sectional view showing a flexible tube for an automobile exhaust system of a third conventional example.

FIG. 11 is a half sectional view showing a flexible tube for an automobile exhaust system according to Conventional Example 4.

[Explanation of symbols]

 A1 to A4 Flexible tube 1 First exhaust pipe 2 Second exhaust pipe 3 Bellows 5 Outer cover 6, 6 ', 6 "coil spring 7', 7" protector 8 Interlock pipe

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16L 27/12 F16L 27/12 B

Claims (5)

[Claims] 1. 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); The outer cover (5) is formed in a tubular shape to cover the outer circumference of the bellows (3), and has one end fixed to one end of the bellows (3); and a protector connected to the other end of the bellows (3). (7), a free end portion of the outer cover (5), which is disposed on the same axis as the outer cover (5), and a protector (7).
A coil spring (6) interposed between the outer cover (5) and the protector (7), and a plurality of rings (8) along the inner diameter of the bellows (3).
) Are fixed to both ends of the bellows (3) in a state where they are given a predetermined movement allowance in the pulling / compressing direction, the bending direction and the shearing direction and are integrally connected in a cylindrical shape. A flexible tube for an automobile exhaust system, comprising: an interlock pipe (8) provided. 2. 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); And an outer cover (5) formed in a cylindrical shape to cover the outer periphery of the bellows (3), and a first protector (7 ′) and a second protector (7 ″) respectively connected to both ends of the bellows (3). The spring is interposed between one end of the outer cover (5) and the first protector (7 ') inside the outer cover (5), and both ends of the spring are fixedly connected to the outer cover (5) and the first protector (7'), respectively. The first coil spring (6 ') is interposed between the other end of the outer cover (5) and the second protector (7 ") inside the first coil spring (6'). 2nd coil spring (6 ") fixedly connected to 2 protector (7") If the along the inner diameter of the bellows (3) a number of rings (8
) Are fixed to both ends of the bellows (3) in a state where they are given a predetermined movement allowance in the pulling / compressing direction, the bending direction and the shearing direction and are integrally connected in a cylindrical shape. A flexible tube for an automobile exhaust system, comprising: an interlock pipe (8) provided. 3. The flexible tube for an automobile exhaust system according to claim 1, wherein a winding diameter of the coil spring (6) or the first coil spring (6 ′) and the second coil spring (6 ″) is constant. A flexible tube for an automobile exhaust system, characterized in that it is a cylindrical coil spring arranged parallel to the tube axis. 4. The flexible tube for an automobile exhaust system according to claim 1, wherein the coil spring (6) or the first coil spring (6 ′) and the second coil spring (6 ″) are wound on the starting end side. A flexible tube for an automobile exhaust system, wherein the flexible tube is a conical coil spring having a diameter substantially equal to the outer diameter of the protector, and a winding diameter on the end side is larger than that on the start side. 5. The flexible tube for an automobile exhaust system according to claim 1, wherein the ring (8) forming the interlock tube (8).
2, 83..) Has a hook portion (8
2a, 83a...) And the other edge has hooks (82b, 83b...) Opposite to the hooks of the one edge, and both hooks engage hooks of the adjacent ring. A flexible tube for an automobile exhaust system, which has gaps (a, b, c) that can be displaced in a tension / compression direction, a bending direction, and a shearing direction of the rings in a stopped state.