JP2000356138A - Exhaust pipe heat shield cover mounting structure - Google Patents

Abstract

(57) [Summary] [Description] A metal heat shield cover 20 covering an exhaust pipe 12 through a predetermined gap D2 and an exhaust pipe 1 through a bolt 22 are provided.
A mounting portion 24 fixed to the second boss portion 18 is provided. Around the mounting portion 24, a cutout portion 26 extending in the circumferential direction is formed leaving a weak portion 28. The attachment part 24 and the fragile part 28 are formed integrally with the cover main body 20A of the heat shield cover 20,
Further, the cover body 20A is elastically supported by the fragile portion 28. [Effect] At the time of press molding of the heat shield cover 20, the notch 2
By punching 6, the mounting portion 24 and the fragile portion 28 can be formed at the same time, and its manufacture becomes extremely easy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for a heat shield cover of an exhaust pipe used for an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, exhaust pipes used in automobiles and the like have a high temperature of 900 ° C. or more due to exhaust heat. It is designed to protect peripheral devices from the effects. However, since such a heat shield cover is formed of a thin metal plate or the like having high heat resistance, there is a problem that a film vibration is caused by an engine vibration or the like propagating from an exhaust pipe and a radiation sound (noise) is generated. is there.

As a countermeasure against this, Japanese Patent Laid-Open Publication No. 63-60008
In the method described in the above publication, the heat shield cover is formed by stacking two metal plates having different thicknesses on each other, connecting the two metal plates at a plurality of locations, and bringing the two metal plates into frictional contact with each other. , To attenuate vibration.

[0004]

However, in the structure disclosed in Japanese Patent Application Laid-Open No. 63-60008, the heat shield cover has a two-piece structure, which is complicated, and the mounting part of the heat shield cover is attached to the exhaust pipe. Since the structure is rigidly connected with the bolts, the vibration of the exhaust pipe is directly propagated to the heat shield cover, and the radiated sound is also generated from the heat shield cover.

Therefore, in Japanese Patent Laid-Open No. Hei 5-296037, as shown in FIG. 4, a part of the inner inner panel of the two metal plates forming the heat shield cover is moved inward.
A metal spring plate is formed by bending the spring plate into a letter shape, and this spring plate is fixed to the exhaust pipe via bolts. In this case, the heat shield cover is elastically supported by the exhaust pipe by the spring plate part as the mounting portion, and vibration transmitted from the exhaust pipe to the heat shield cover can be reduced.

However, Japanese Patent Application Laid-Open No. Hei 5-29603 describes
In the structure of Japanese Patent Publication No. 7, since the mounting portion is located inside the heat shield cover, that is, between the heat shield cover and the exhaust pipe, a hole for a jig for attaching a bolt to the heat shield cover is separately provided. The inner panel must be formed by press working or the like, and then bent inward into a U-shape to form a spring plate portion.
Reduction of manufacturing cost is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a simple structure that effectively suppresses transmission of vibration from an exhaust pipe to a heat shield cover, while further simplifying and manufacturing. It is an object of the present invention to provide a novel heat shield cover mounting structure for an exhaust pipe which can reduce costs.

[0008]

According to a first aspect of the present invention, a metal heat shield cover for covering an exhaust pipe through a predetermined gap has a mounting portion fixed to a boss portion of the exhaust pipe via bolts. Around the mounting portion, a notch extending in the circumferential direction is formed leaving a fragile portion, and the fragile portion and the mounting portion are formed integrally with the cover main body of the heat shield cover, and The cover body is elastically supported.

With the above configuration, the cover body becomes a mass, the fragile portion becomes a spring, and the heat shield cover is elastically attached to the exhaust pipe. By the fragile portion, vibration transmitted from the exhaust pipe to the heat shield cover is suppressed, and generation of noise due to the vibration of the heat shield cover can be effectively prevented.

At the time of manufacturing, for example, by punching out the notch when the heat shield cover is formed by press working, the mounting portion and the fragile portion can be formed at the same time, and the manufacturing is extremely easy.

According to a second aspect of the present invention, a washer is interposed between the mounting portion and the head of the bolt, and the washer is formed to be at least larger than the notch so as to cover the notch. It is characterized by having.

According to this configuration, the transmission of the radiant heat of the exhaust pipe to the outside of the heat shield cover through the cutout portion by the washer can be effectively suppressed. That is, it is possible to suppress a decrease in the heat shielding performance of the heat shielding cover due to the provision of the notch.

Further, even in the event that the fragile portion is damaged due to metal fatigue or the like and the cover body of the heat shield cover is separated from the mounting portion, the peripheral edge of the notch is in contact with and supported by the washer. As a result, the cover body can be prevented from falling off.

According to a third aspect of the present invention, the fragile portion is inclined from the mounting portion toward the exhaust pipe so as to provide a first gap between the cover body and the washer.

That is, in order to provide the first gap, a step is provided between the mounting portion and the cover body. In this case, even if the heat shield cover vibrates, there is no possibility that the cover main body and the washer come into contact with each other, and there is no possibility that so-called chatter noise is generated. The first gap is set to a minimum within a range where the washer does not come into contact with the cover body due to vibration, and is set to, for example, several mm to several cm.

According to a fourth aspect of the present invention, in order to reduce the number of components, the bolt is a flanged bolt integrally formed with a washer.

According to a fifth aspect of the present invention, the boss portion of the exhaust pipe projects toward the heat shield cover so as to provide a second gap between the cover main body and the exhaust pipe. .

In this case, even if the heat shield cover vibrates, there is no possibility that noise and breakage may occur due to contact with the exhaust pipe. Note that this second
Is set to a minimum as long as the exhaust pipe and the heat shield cover do not come into contact with each other due to vibration, and for example, is set to several mm to several cm.

In the heat shield cover, it is the central portion of the heat shield cover where the vibration amplitude is large and sound generation is concerned. Therefore, in the invention of claim 6, in order to suppress the vibration transmitted to the cover main body via the fragile portion, the fragile portion is arranged around the mounting portion on the side opposite to the central portion of the heat shield cover.

In the case where the heat shield cover has an inner panel and an outer panel which are joined to each other, preferably, the notch is formed in the inner panel to form a mounting portion and a fragile portion. While the parts are provided integrally, mounting holes are formed in the outer panel according to the outer shape of the cutout parts.

Thus, the vibration is transmitted to the outer panel serving as the sound generating surface via the inner panel. For this reason, while the vibration input to the inner panel is transmitted to the outer panel, the vibration energy is appropriately attenuated as friction energy between the two. Therefore, compared with the case where the outer panel is directly attached to the exhaust pipe, the vibration of the heat shield cover is more effectively suppressed, and the generation of noise can be reduced.

Also, since the outer panel is provided with a mounting hole corresponding to the outer shape of the cutout portion, the fragile portion is formed as desired while using a relatively rigid heat shield cover formed by joining two metal plates. It can have low rigidity. As a result, the frequency at which vibration can be prevented is reduced, and the generation of vibration and noise of the heat shield cover can be effectively suppressed.

[0023]

As described above, according to the present invention, the cover body serves as a mass and the fragile portion serves as a spring, and the heat shield cover is elastically attached to the exhaust pipe. By the fragile portion, vibration transmitted from the exhaust pipe to the heat shield cover is suppressed, and generation of noise due to the vibration of the heat shield cover can be effectively prevented.

For example, by punching out the notch when the heat shield cover is press-formed, the mounting portion and the fragile portion can be easily formed at the same time, and its manufacture is extremely easy, and the manufacturing cost is kept low. be able to.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a heat shield cover mounting structure for an exhaust pipe according to a first embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 4, the exhaust manifold 10
Has four exhaust pipes 12 connected to the exhaust ports of the cylinders of the engine, a joint flange 14 for the engine body, and a joint flange 16 for the exhaust pipe on the downstream side.
The exhaust pipe 12 is provided with a plurality of bosses 18 for attaching the heat shield cover 20 (FIGS. 1 to 3).

As shown in FIGS. 1 to 3, the heat shield cover 20 is formed by press-molding a single metal plate having excellent heat resistance.
The exhaust manifold 10 including the exhaust pipe 12 is covered with a predetermined gap D2 so as to protect the ignition system, the fuel system, and various accessories from thermal effects of zero.

The heat shield cover 20 is provided with mounting portions 24 in which mounting holes 24 a for bolts 22 are formed, and the mounting portions 24 are fastened and fixed to the boss portions 18 of the exhaust pipe 12 by the bolts 22. It has become so.

A substantially C-shaped notch 26 extending in the circumferential direction is formed around each mounting portion 24 except for a weak portion 28 having a predetermined circumferential length. That is, the mounting portion 2
4 and the fragile portion 28, the notch 26 and the fragile portion 28
Are formed integrally with the cover main body 20A of the heat shield cover 20 except for the above, and the fragile portion 28 elastically supports the cover main body 20A. That is, the cover body 20A serves as a mass, the fragile portion 28 serves as a spring, and the heat shield cover 20 is elastically attached to the exhaust pipe 12. As a result, the vibration transmitted from the exhaust pipe 12 to the heat shield cover 20 is reduced, and the generation of noise due to the vibration of the heat shield cover 20 can be effectively reduced.

In manufacturing, for example, when the heat shield cover 20 is formed by press working, the notch 26 is punched out, so that the mounting portion 24 and the fragile portion 28 are simultaneously formed integrally with the heat shield cover 20. Therefore, the manufacturing is extremely easy, and the manufacturing cost can be reduced.

The mounting portion 24 and the head 22 of the bolt 22
A washer 30 is interposed between a and a. The washer 30 is formed to be at least larger than the notch 26 so as to cover the notch 26. For this reason, transmission of the radiant heat of the exhaust pipe 12 to the outside via the notch 26 is suppressed. That is, it is possible to suppress a decrease in the heat shielding performance of the heat shielding cover 20 due to the provision of the cutout portion 26.

Moreover, even if the fragile portion 28 is damaged by metal fatigue or the like and the cover body 20A is separated from the mounting portion 24, the peripheral edge of the notch 26 in the cover body 20A contacts the washer 30. , And the cover body 20A can be reliably prevented from falling off.

Here, the cover body 20A and the washer 30
The fragile portion 28 is inclined from the mounting portion 24 toward the exhaust pipe 12 so as to provide a predetermined gap (first gap) D1 between the first and second gaps. That is, in order to provide the gap D1, the mounting portion 2
A step is provided between the cover 4 and the cover body 20A. The gap D1 is formed between the washer 30 and the cover body 20 by vibration.
A is set to a minimum as long as it does not contact A, for example, several meters
m to several cm. As a result, the cover body 20A
There is no danger of contact with the washer 30 even if it vibrates, and there is no danger of so-called chattering noise.

In this embodiment, the bolt 22 and the washer 30 are separate parts. However, in order to further reduce the number of parts, a bolt with a flange in which the bolt and the washer are integrated is used. Can also.

The boss portion 18 of the exhaust pipe 12 has a mounting hole 18a for a bolt 22 and a predetermined gap (second gap) D2 between the cover body 20A and the exhaust pipe 12. As shown in the figure, the exhaust pipe 12 has a cylindrical shape that protrudes (raises) from the surface of the exhaust pipe 12 toward the heat shield cover 20. This gap D2 is set to a minimum within a range where the exhaust pipe 12 and the cover main body 20A do not come into contact with each other due to vibration,
For example, it is set to several mm to several cm. As a result, even if the heat shield cover 20 vibrates, there is no possibility that the heat shield cover 20 will come into contact with the exhaust pipe 12 to cause noise and breakage. In this embodiment, the gaps D1, D
2 are set to substantially the same value, and the heat shield cover 20 is
It is arranged at a substantially intermediate position between 2 and washer 30.

In this embodiment, the boss 18 is formed integrally with the exhaust pipe 12 by casting. However, the boss 18 is formed separately from the exhaust pipe 12 and is fixed to the exhaust pipe 12 later. Is also good.

As shown in FIG. 3, the central portion C of the heat shield cover 20 where the vibration amplitude is particularly large and there is concern about sound generation. Therefore, in the present embodiment, in order to further suppress the vibration transmitted to the cover main body 20A via the fragile portion 28, each fragile portion 28 is opposed to the central portion C of the heat shield cover 20 around the mounting portion 24. Side, that is, on the side opposite to the central portion C.

According to the present embodiment as described above, the vibration transmitted to the cover body 20A is effectively suppressed by the fragile portion 28, and more specifically, the resonance frequency is as low as about several tens Hz, and the film resonance is reduced. The frequency range of several hundreds of Hz where the noise is remarkable can be reliably prevented, and the heat shielding cover 20 can be used.
Generation of noise due to the vibration of the vehicle can be reliably prevented. When the notch 26 is punched out when the heat shield cover 20 is press-formed, the mounting portion 24 and the fragile portion 28 can be formed integrally with the heat shield cover 20 at the same time. Therefore, the manufacturing cost can be reduced.

In this embodiment, only one fragile portion 28 is formed around the mounting portion 24, but a plurality of fragile portions may be formed intermittently.

FIG. 5 is a sectional view showing a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and duplicate description will be omitted as appropriate.

The heat shield cover 32 of this embodiment comprises an inner panel 34 and an outer panel 36 which are individually press-molded.
Are joined together at a plurality of places by spot welding or the like. Here, the inner panel 34 near the exhaust manifold is set to be thinner than the outer panel 36 which is a sound generation surface due to vibration. Specifically, the thickness of the inner panel 34 is set to, for example, several mm, and the thickness of the outer panel 36 is set to several times the thickness of the inner panel 34.

The C-shaped notch 26 is formed in the inner panel 34 to integrally form the mounting portion 24 and the fragile portion 28, while the outer panel 36 is mounted in accordance with the outer shape of the notch 26. The hole 38 is formed by punching.

With the above configuration, the fragile portion 2 formed on the inner panel 34 is provided on the outer panel 36 serving as a sound generating surface.
Vibration is transmitted through 8. For this reason, while the vibration input to the inner panel 34 is transmitted to the outer panel 36, the vibration is appropriately attenuated as the friction energy between the two, and the vibration of the heat shield cover 32 is reduced as compared with the case where the outer panel is directly attached to the exhaust pipe. Thus, the noise can be more effectively reduced, and the generation of noise can be more effectively reduced.

For example, the inner panel 34 is 0.4 m
m, when the outer panel 36 has a plate thickness of about 20 mm, the rigidity of the heat shield cover 32 is relatively high at 0.8 kgf / mm, but in the present embodiment, the outer panel 36 conforms to the outer shape of the notch 26. Since the mounting hole 38 is formed, the fragile portion 28 is formed only by the inner panel 34, and its rigidity can be reduced to a desired value. As a result, the resonance frequency becomes several tens of Hz, and the frequency range of 200 Hz or more where the film resonance becomes remarkable can be reliably prevented from being vibrated, and the radiation sound generated from the heat shield cover 32 can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a heat shield cover mounting structure for an exhaust pipe according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the heat shield cover.

FIG. 3 is a front view of the heat shield cover.

FIG. 4 is a front view of an exhaust manifold.

FIG. 5 is a sectional view showing a heat shield cover mounting structure for an exhaust pipe according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Exhaust pipe 18 ... Boss part 20 ... Heat shield cover 20A ... Cover main body 22 ... Bolt 24 ... Mounting part 26 ... Notch part 28 ... Fragile part 30 ... Washer

Claims (7)

[Claims] A metal heat shield cover for covering an exhaust pipe with a predetermined gap provided with a mounting portion fixed to a boss portion of the exhaust pipe via a bolt, and a peripheral portion is provided around the mounting portion. The notch extending in the direction is formed leaving a fragile portion, and the mounting portion and the fragile portion are formed integrally with the cover body of the heat shield cover, and the cover body is elastically supported by the fragile portion. Features a heat shield cover mounting structure for the exhaust pipe. 2. A washer is interposed between the mounting portion and the head of the bolt, and the washer is formed to be at least larger than the notch so as to cover the notch. The heat shield cover mounting structure for an exhaust pipe according to claim 1. 3. A first space between the cover body and the washer.
The heat shield cover mounting structure for an exhaust pipe according to claim 2, wherein the fragile portion is inclined from the mounting portion toward the exhaust pipe so as to provide a gap. 4. A heat shield cover mounting structure for an exhaust pipe according to claim 2, wherein said bolt is a flanged bolt integrally formed with said washer. 5. The exhaust pipe according to claim 1, wherein a boss portion of the exhaust pipe projects toward the heat shield cover so as to provide a second gap between the cover body and the exhaust pipe. A heat shield cover mounting structure for an exhaust pipe according to any one of the above. 6. The exhaust pipe shield according to claim 1, wherein the fragile portion is disposed in the periphery of the mounting portion and on the side opposite to the center of the heat shield cover. Heat cover mounting structure. 7. The heat shield cover includes an inner panel and an outer panel that are joined to each other. The notch is formed in the inner panel to integrally provide a mounting portion and a fragile portion, while the notch is formed in the outer panel. 7. A heat shield cover mounting structure for an exhaust pipe according to claim 1, wherein a mounting hole is formed in accordance with the outer shape of the exhaust pipe.