JP2002071071A - Structure for connecting exhaust pipe of automobile and coil spring used for the structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weight structure for a portion connecting an exhaust pipe of an automobile. SOLUTION: The first flange 1a of a first exhaust pipe 1 and the second flange 2a of a second exhaust pipe 2 are jointed by a plurality of joining members C, and the joining members C comprises a composition of which the front end portion 8a of a bolt member 8 disposed by passing through the second flange portion 2a is fixed to the first flange portion 1a, and a compressive coil spring 6 is disposed between the rear end portion 8b of the bolt member 8 and the second flange portion 2a, and the section of the wire rod of the compressive coil spring 6 is provided with a flattening sectional shape of which the dimensional ratio d1/d2 between a longer diameter d1 and a shorter diameter d2 is given 1.1 to 2.6, and more than 50% in an end face is formed to be the same flat face without grinding a seat face on the each end face on the both end portions of the coil spring 6, and the end face of the same flat face is formed as the seat face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection structure using a ball joint of an exhaust pipe of an automobile and a coil spring used for the connection structure.

[0002]

2. Description of the Related Art Conventionally, a ball joint has been used as a vibration isolating joint in an exhaust line of an automobile, thereby absorbing vibration of a vehicle body and making it impossible to connect to an exhaust portion of an engine or a connection portion of an exhaust pipe. It is devised so that no excessive stress is applied, and its concrete structure is described in JP-A-10-17.
As disclosed in Japanese Patent No. 6777 and Utility Model Registration No. 2598461, various types have been proposed and put into practical use.

[0003] Referring to Fig. 5, a representative structure thereof will be described. In Fig. 5, an exhaust pipe includes a first exhaust pipe 1 called an exhaust manifold for guiding exhaust gas from an automobile engine, and the exhaust pipe. An exhaust pipe (second exhaust pipe) 2 for releasing gas into the atmosphere is provided. The two exhaust pipes 1 and 2 are flexibly connected by a ball joint mechanism B. That is, the first exhaust pipe 1 of the second exhaust pipe 2
A ball portion 3 having a spherical outer shape is formed at a connection portion with the first exhaust pipe 1, and a flare portion 5 having an inner curved surface 4 adapted to the ball portion 3 is formed at the other first exhaust pipe 1. ,
The first exhaust pipe 1 and the second exhaust pipe 2 are formed with a first flange portion 1a and a second flange portion 2a having opposing flat surfaces, respectively, and between the two flange portions 1a, 2a,
It is connected and fixed by a plurality of connecting members C.

The connecting member C is connected to the second flange 2
and a bolt member 8 fixed to the nut 7 by screwing a tip 8a to the nut 7 and disposed through the opening 1b of the first flange 1a.
And the first exhaust pipe 1 is disposed between the rear end 8b of the bolt member 8 and the first flange 1a, and presses the first exhaust pipe 1 toward the second exhaust pipe 2 via the first flange 1a. When a bending force acts between the first exhaust pipe 1 and the second exhaust pipe 2 due to the vibration of the vehicle body, the ball joint mechanism B makes the first exhaust pipe 1 The second exhaust pipe 2 is allowed to bend, and the coil spring 20 maintains the close contact between the ball portion 3 and the inner curved surface 4 in the ball joint portion B to prevent leakage of exhaust gas. .

[0005]

In the method having the above structure, the compression coil spring 20 is formed by winding a wire having a circular cross section in a coil shape. Therefore, the diameter of the coil wire is d, and the coil spring is wound. Assuming that the number of times is n, the length of the coil spring is n × d even when the coil spring is compressed until the coil wires come into contact with each other. Therefore, the length of the portion of the bolt member 8 receiving the coil spring 20 must be longer than nxd, and a relatively heavy bolt is used. At the same time, due to the high spring height, the amount of lateral movement when bending stress is applied during use increases,
In addition, there has been a problem that the contact amount between the lines increases and the moment increases.

[0006] On the other hand, due to recent environmental problems, improvement of fuel efficiency of automobiles is the most important issue.
Development of high efficiency engine, improvement of combustion method, reforming of fuel,
It is well known that the development of new driving sources such as fuel cells and the like has been carried out, but at the same time, continuous efforts have been made to improve fuel efficiency by reducing the weight of the vehicle body.

[0007] As measures to reduce the weight of the vehicle body, hard efforts have been made from the reduction of the weight of the vehicle body structure to the reduction of the weight of various parts in gram units. In the system as well, efforts have been made to reduce the thickness of the exhaust pipe and to reduce the diameter of the bolt member 8 in the connecting member C, and the system has been near the limit of weight reduction. A lighter weight is desired.

SUMMARY OF THE INVENTION In view of the above situation, it is a primary object of the present invention to provide a novel exhaust pipe connection structure that is further reduced in weight, and to further reduce the cost of the exhaust pipe connection structure. Is the second object.

[0009]

SUMMARY OF THE INVENTION The present invention has been made on the basis of this point of view, and in particular, by improving the structure of a coil spring which has not been taken into consideration by conventional measures for reducing the weight of an exhaust pipe, has been proposed. While significantly reducing the weight of the connection structure,
The present invention also achieves cost reduction, and the feature is that the wire rod cross-sectional shape of the compression coil spring used for the exhaust pipe connection structure is such that the dimensional ratio of the major axis to the minor axis is 1.
1 to 2.6, preferably 1.3 to 2.0, and in addition, each end face at both ends of the coil spring is not subjected to a bearing surface polishing process. The point is that 50% or more of the end faces are formed to be coplanar, and the end face of the coplanar plane is used as a seating surface. By making the cross section of the wire rod into a flat cross-sectional shape, the length of the coil spring in the fully compressed state is not shortened. In addition to this, the seating surface of the coil spring is formed by utilizing the flatness of the cross section of the wire rod of the coil spring, thereby reducing the manufacturing cost of the coil spring by omitting the step of polishing the seating surface.

[0010] The coil spring is formed by forming a wire having a flat cross section having parallel flat portions facing each other by cold rolling or cold drawing a wire having a circular cross section into a coil shape. And high quality, which is the most preferable form.

Further, the cross-sectional shape of the wire rod of the coil spring includes a parallel flat portion facing in a long diameter direction and left and right circular arc portions continuous with the flat portion, and the width of the flat portion in the long diameter direction and the long diameter are defined. Is preferably 0.5 to 0.9, more preferably 0.5 to 0.8.

In addition, at least 50% of one surface of the flat portion at both ends of the coil spring is formed to be coplanar, and the seat surface of the coil spring is formed by the coplanar portion, so that the seat surface is polished. The same effect as the one obtained is obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a main part showing an exhaust pipe connection structure for an automobile according to the present invention. In FIG. 1, the exhaust pipe includes a first exhaust pipe 1 and a second exhaust pipe 2. The exhaust pipes 1 and 2 are flexibly connected to each other by a ball joint mechanism B. One of the connecting portions between the second exhaust pipe 2 and the first exhaust pipe 1 is formed with a ball portion 3 having a spherical outer shape, and the other is provided with a flare having an inner curved surface 4 adapted to the ball portion 3. The first exhaust pipe 1 and the second exhaust pipe 2 have a first flange portion 1a and a second flange portion 2 having opposing flat surfaces, respectively.
a is formed and the two flanges 1a and 2a are connected and fixed by a plurality of connecting members C as in the conventional case.

The connecting member C is connected to the second flange 2
and a bolt member 8 fixed to the nut 7 by screwing a tip 8a to the nut 7 and disposed through the opening 1b of the first flange 1a.
Is disposed between the rear end portion 8b of the bolt member 8 and the first flange portion 1a, and presses the first exhaust pipe 1 toward the second exhaust pipe 2 via the first flange portion 1a. When a bending force acts between the first exhaust pipe 1 and the second exhaust pipe 2 due to the vibration of the vehicle body, the first exhaust pipe 1 and the second exhaust pipe 1 It is configured to allow bending of the exhaust pipe 2 and maintain the close contact between the ball portion 3 and the inner curved surface 4 of the ball joint portion B by the coil spring 6 to prevent leakage of exhaust gas. .

In the exhaust pipe connection structure having the above-described structure, the compression coil spring 6 used in the present invention has an opposing parallel flat portion 6c as shown in FIG.
It has a significant feature in that it has a flat cross-sectional shape composed of the left and right circular arc portions 6d that are continuous with it. That is, by making the coil wire cross-sectional shape a flat shape, it becomes possible to reduce the spring height in the close contact state of the coil spring as compared with a conventional coil spring using a wire having a circular cross-section. When using a coil spring having the same spring constant as the above, the length (height) of the coil spring itself can be reduced, and the length of the bolt member 8 used integrally with the coil spring can be also reduced. Thus, the weight of the connecting member C including the coil spring 6 and the bolt member 8 can be significantly reduced.

As shown in FIG. 3, the shape of the flat cross-section wire used in the present invention has a major axis d1 and a minor axis d2.
It is important to set the ratio (d1 / d2) to a range of 1.1 to 2.6. If this ratio is smaller than 1.1, a significant difference from the conventional wire having a circular cross section is not recognized. Tap, 2.6
If it exceeds, it becomes close to a plate-like body, the spring constant becomes small, and the length (height) of the coil spring may rather increase, so it is necessary to set it within the above range. still,
It is the most preferable mode to set the value of the ratio in a range of 1.3 to 2.0.

As a method of flattening the wire, a method of cold rolling a normal wire having a circular cross section through a pair of upper and lower rolling rollers or a method of cold drawing is preferable. By performing this cold rolling or cold drawing, the hardness of the wire is increased, and the strength, fatigue characteristics, and set resistance are improved.As a result, the wire itself can be used as a thinner wire than before. Also, the effect of reducing the weight of the coil spring is expected.

By performing the cold rolling or the cold drawing described above, opposed parallel flat portions 6c are formed in the longitudinal direction of the wire.
The dimensional ratio (d3 / d1) of the width d3 to the major axis d1 is
It is preferable to set in the range of 0.4 to 0.9. If this value is smaller than 0.4, it is difficult to obtain sufficient flatness and the effect of cold working. The degree of flatness becomes too large and becomes closer to a plate-like body, which may make it difficult to obtain an appropriate spring constant. In particular, 0.5-0.8
The degree is a preferred range.

FIG. 3 shows a coil spring 6 formed by winding a wire having a flat cross section as shown in FIG. 2 into a coil shape.
FIG. In the same figure, the winding portions 6a, 6b at both ends of the coil spring 6 are different from the winding portions at the central portion, so that the end windings are formed so as to be flush with the end planes S1, S2, respectively. The portions 6a and 6b are wound so as to have a winding portion in the same plane. As a result, a part of the flat portion 6c of the wire in the winding portions 6a and 6b at both ends is present on the same plane as the end surface planes S1 and S2. 6c is used as a seat surface of the coil spring in the present invention.

This eliminates the necessity of polishing the seating surface of the coil spring, which is required when a conventional wire having a circular cross section is used, thereby simplifying the coil spring manufacturing process and reducing the manufacturing cost. become.

It is desirable that the ratio of the wire rods at the end portions 6a and 6b existing on the same planes S1 and S2 of the flat portion 6c is at least 50% or more. As a result, at least 50% of the coil spring comes into surface contact with the mating member on the end face of the coil spring, so that the coil spring 6 is stably set at the predetermined position.

[0022]

Next, an embodiment of the present invention will be described. S
US316N cross-section circular wire (diameter = 3.2 mm) is cold-rolled to obtain a long diameter (d1) = 3.52 mm and a short diameter (d).
2) = 2.55 mm, ratio of major axis to minor axis (d1 / d2)
A flat wire having a flat cross-sectional shape of 1.38, the flat part width (d3) = 1.8 mm, and the ratio of the flat part width to the major axis (d3 / d1) = 0.51 was manufactured as a test wire for a coil spring. did.
Outer diameter = 24 mm, total number of turns =
4.5 (Effective number of turns = 3, number of turns on both ends = 0.75)
Winding), free height = 30.5 mm, close contact height = 14.5 m
m, a coil spring having a spring constant of 29.4 N / mm (3 kgf / mm) was manufactured. Using this coil spring, FIG.
As shown in (1), the exhaust pipes of the automobile were connected at two places (at a position of 180 °), bending stresses were applied to the ball joint in four directions, and the moments acting on the bolt members were measured. For comparison, with the same spring constant molded in the same manner using a wire having a circular cross section before the cold rolling,
Total number of turns = 7.5 (effective number of turns = 5.5, number of end turns =
1.0) and the same test was performed using a coil spring having a free height of 42.0 mm. The result is shown in FIG.

In FIG. 4, (a) to (d) show the displacement angle (deg) of the joint portion when stress is applied to the ball joint portion in different phases and the moment (N ·) acting on the bolt member. m) is a graph showing the same using the coil spring according to the present invention (open circles in the figure) and the one using the conventional circular cross-section coil spring (black circles in the figure) in the same drawing. In the direction 1 of FIG. 4A, the winding start position of the coil spring is arranged at the position shown at 12 o'clock when viewed from the side where the displacement stress is applied, and in the direction 2 of FIG. 4 (c), the winding start position of the coil spring is set to the 6 o'clock position as viewed from the side where the displacement stress is applied. In the direction 4 in FIG. 4D, the winding start position of the coil spring is arranged at the position shown at 9 o'clock when viewed from the side where the displacement stress is applied. As is clear from these figures, in any direction, the one using the coil spring of the present invention shows a lower moment for the same displacement angle. This is because, in the case of using the coil spring of the present invention, the free height of the coil spring is set lower because the contact height of the coil spring can be reduced as compared with the conventional product, and therefore, the bolt member which is a mating component And the set height of the exhaust pipe connection member is also reduced, so that the amount of lateral movement of the coil spring for the same displacement angle is reduced, and the moment (oscillation torque) for the displacement angle is reduced. This indicates that the vibration isolation performance of the part has been improved.

[0024]

As described above, according to the present invention, by setting the cross-sectional shape of the coil spring wire to a predetermined flat cross-sectional shape, the contact height can be set lower than that of a conventional coil spring using a circular cross-sectional wire. In particular, by setting the ratio between the long diameter and the short shape within the predetermined range of the present invention, it is possible to set the contact height as low as about 60% at the maximum, and accordingly, the free height of the coil spring is correspondingly reduced. Since it can be set and the length of the bolt member as the counterpart member can be shortened, the weight of the exhaust pipe connecting member can be significantly reduced. In particular, according to the optimum design, the total weight of the bolt member and the coil spring can be reduced to about 50% as compared with the conventional method. It is expected to contribute to improvement.

In addition, since the free height of the coil spring is reduced, the set height of the exhaust pipe connecting member is also reduced. As a result, the amount of lateral movement of the coil spring for the same displacement angle is reduced, and the amount of contact between the coils is also reduced. Since it is reduced, the moment for the same displacement angle is also smaller than that of the conventional product, and the improvement of the vibration isolation performance of the joint is achieved.

Further, as a result of the contact height of the coil spring being greatly reduced, the degree of freedom in selecting the material dimensions is increased as compared with the conventional product. As a result, a compact and smart coil spring can be designed, and the exhaust pipe connection portion can be designed. The on-board performance of the vehicle is improved.

If the flat wire for the coil spring is formed of a cold rolled or cold drawn wire of a circular wire, the hardness of the wire is increased by cold working. As a result of the improved settling resistance, it is possible to make the wire thinner, which is expected to further contribute to the measurement of automobile parts.

Further, if the bearing surface is formed by utilizing the flatness of the wire, the grinding process of the bearing surface at the end of the coil spring, which has been conventionally required, becomes unnecessary, and the manufacturing process of the coil spring is omitted. In addition to the cost reduction and cost reduction, the generation of polishing debris is eliminated, which contributes to the reduction of the amount of waste generated in the manufacturing process.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an example of an exhaust pipe connection structure according to the present invention.

FIG. 2 is a sectional view of a coil of the coil spring of FIG. 1;

FIG. 3 is a sectional view of a coil spring used in the exhaust pipe connection structure of FIG. 1;

FIG. 4 is a graph comparing characteristics of the coil spring of the present invention and a conventional coil spring.

FIG. 5 is a sectional view of a main part showing an example of a conventional exhaust pipe connection structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st exhaust pipe 1a Flange part of 1st exhaust pipe 2 2nd exhaust pipe 2a Flange part of 2nd exhaust pipe 6 Cross-section flat coil spring 6a, 6b End part of coil spring 6c Flat part 6d Arc part 7 Nut 8 Bolt member 8a Bolt Tip 8b Bolt rear end B Ball joint mechanism C Connecting member d1 Long diameter of flat cross section d2 Short diameter of flat cross section d3 Flat section width of flat cross section S1, S2 Flat surface of coil spring end

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Yanagihara 14th Suncall Co., Ltd. Umezu Nishiuracho, Ukyo-ku, Kyoto-shi (72) Inventor Hanshitaishi Sueyoshi 1st Toyota Town, Toyota-shi, Aichi Prefecture Toyota Motor F term in reference (reference) 3G004 AA01 DA11 EA03 GA01 3H104 JA03 JB02 JC04 JC08 JD03 LA07 LA15 LA18 LF01 MA08 3J059 AD05 AE04 AE05 BA08 BC02

Claims (11)

[Claims] An exhaust pipe connection structure for an automobile, wherein a first exhaust pipe (1) and a second exhaust pipe (2) are bendably connected by a ball joint mechanism (3), wherein the first exhaust pipe is provided. The first flange portion (1a) formed at the connection portion of the pipe (1) and the second flange portion (2a) formed at the connection portion of the second exhaust pipe (2) are connected to a plurality of connecting members (C ), And the connecting member (C) is configured such that a tip portion (8a) of a bolt member (8) disposed through the second flange portion (2a) is connected to the first flange portion (1a). The bolt member (8) is fixed at the rear end (8
b) and the second flange portion (2a), a compression coil spring (6) is arranged, and the wire section of the compression coil spring (6) has a major axis (d1) and a minor axis ( d2) is 1.1 to 1.1.
It has a flat cross-sectional shape of 2.6, and at least 50% or more of the end faces of both ends (6a, 6b) of the compression coil spring (6) are not subjected to the polishing of the seating surface. An exhaust pipe connection structure for an automobile, wherein the exhaust pipe connection structure is formed so as to be on the same plane (S1, S2), and the end face of the same plane (S1, S2) is used as a seating surface. 2. A dimensional ratio (d1 / d2) of a major axis (d1) and a minor axis (d2) of a wire section of the compression coil spring (6).
2. The exhaust pipe connection structure for an automobile according to claim 1, wherein the number is 1.3 to 2.0. 3. The compression coil spring (6) is formed by coiling a flat cross-section wire having opposed flat portions (6c) obtained by performing cold rolling or cold drawing on a wire having a circular cross section. The exhaust pipe connection structure for an automobile according to claim 1, wherein the exhaust pipe connection structure is obtained by molding. 4. A cross-sectional shape of a wire rod of the compression coil spring (6) includes a parallel flat portion (6c) facing in the major axis direction and left and right circular arc portions (6d) continuous with the flat portion (6d). 6c) the width (d3) in the major axis direction and the major axis (d
The exhaust pipe connection structure for an automobile according to any one of claims 1 to 3, wherein a dimensional ratio (d3 / d1) to 1) is 0.4 to 0.9. 5. The dimensional ratio (d3 / d1) of the width (d3) of the flat portion (6c) to the major axis (d1) is 0.5 to 5.
5. The exhaust pipe connection structure for an automobile according to claim 4, wherein the value is 0.8. 6. Both ends (6) of said compression coil spring (6).
a, 6b) of 50 to 50 on one surface of the flat portion (6c).
The exhaust pipe connection structure for an automobile according to claim 4 or 5, wherein 80% is formed so as to be on the same plane (S1, S2), and the seating surface of the coil spring is formed by the same plane portion. 7. A coil spring (6) used for an exhaust pipe connection structure of an automobile, wherein a cross-sectional shape of a wire forming the coil spring has a long diameter (d).
The dimensional ratio (d1 / d2) between 1) and the minor axis (d2) is 1.
A coil spring for an exhaust pipe connection structure of an automobile, wherein the coil spring has a diameter of 1 to 2.6. 8. A coil spring (6) used for an exhaust pipe connection structure of an automobile, wherein a cross-sectional shape of a wire forming the coil spring has a long diameter (d).
The dimensional ratio (d1 / d2) between 1) and the minor axis (d2) is 1.
1 to 2.6, and has a flat cross-sectional shape in the major axis direction including a parallel flat surface portion (6c) opposed thereto and left and right circular arc portions (6d) continuous with the flat surface portion (6d). The width (d3) of the portion (6c) in the major axis direction and the major axis (d
A dimensional ratio (d3 / d1) to (1) of 0.4 to 0.9, wherein the coil spring for an exhaust pipe connection structure of an automobile is characterized by being 0.4 to 0.9. 9. A major axis (d1) and a minor axis (d1) of a cross section of the wire rod.
2) is 1.3 to 2.0, and the width (d3) of the flat portion (6c) and the major axis (d)
9. The coil spring for an exhaust pipe connection structure of an automobile according to claim 8, wherein the dimensional ratio (d3 / d1) to 1) is 0.5 to 0.8. 10. An end (6) of the coil spring (6).
9. The wire rod in (a, 6b) is formed so that at least 50% of one surface of the flat portion (6c) is located on the same end surface (S1, S2), and the same flat portion is used as a seat surface.
Or a coil spring for an exhaust pipe connection structure of an automobile according to 9 11. The wire of the coil spring according to claim 7, wherein the wire having a circular cross section is formed into the flat cross-sectional shape by cold rolling or cold drawing. Coil spring for exhaust pipe connection structure of automobile