JP3064673B2 - Exhaust manifold cover for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold cover for a vehicle, and more particularly to an exhaust manifold for a vehicle for increasing the lowest natural frequency of the exhaust manifold cover and reducing the sound pressure level of radiated sound due to resonance at a high frequency. About the cover.

[0002]

2. Description of the Related Art Vehicles include an exhaust manifold cover, an exhaust pipe cover, a catalyst case cover, a muffler cover, a worm air cover, a heat shield plate, a sheet metal air cleaner case, and a blow molding formed by a plate-shaped molding member. Boxes, dash panels, floors and the like of automobile bodies are used, and a predetermined surface rigidity is ensured after the molding of the molding member.

One example of the exhaust manifold cover for a vehicle is disclosed in Japanese Utility Model Laid-Open Publication No. Sho 61-65231. The heat shield plate of the exhaust manifold disclosed in this publication is attached to the exhaust manifold of the engine and provided with a heat shield plate for shielding the heat of the exhaust manifold, and the heat shield plate has an outer plate and an inner plate. And a space is provided between the outer plate and the inner plate, and the outer plate is provided with a number of protrusions protruding outward.

Further, there is one disclosed in Japanese Utility Model Laid-Open No. 63-154717. The exhaust manifold heat shield device disclosed in this publication covers an exhaust manifold multi-branch pipe and a downstream end of an exhaust conduit where the multi-branch pipe joins to cover the exhaust manifold, and to completely cover the exhaust manifold. In a heat shield device having a heat shield plate of a split middle type in which a pair of press pieces formed with a convex or concave bead extending over the periphery are joined to each other by a flange, the height of the flange at a portion where no bead is formed And below.

When the exhaust manifold cover for a vehicle is formed, as shown in FIGS. 8 and 9 (a), 9 (b) and 9 (c), a relatively thin sheet metal or a sheet thickness such as blow molding of resin is used. In the molded member 122 having a substantially constant thickness, the molded member 122
In order to reinforce a relatively flat portion, a bead portion 120 having an uneven shape extending in one direction in the longitudinal direction is formed on the surface to improve rigidity after molding.

Further, as shown in FIG.
Some have a grid-shaped bead portion 220 formed thereon.

[0007]

By the way, in a conventional exhaust manifold cover for a vehicle, as shown in FIG.
When the exhaust manifold cover is formed by the forming member 122, as shown in FIG. 9A, the cross-sectional shape of the forming member 122 is in an uneven state, the second moment of area is increased, and the rigidity after the forming is large.

However, in FIG. 9B, the sectional shape of the molded member 122 is quite flat, the second moment of area is not increased, and in FIG. Are substantially flat.

As a result, when the surroundings of the exhaust manifold cover are fixed and vibrated, the lowest natural frequency is determined mainly by the surface bending stiffness, depending on the fixing method. It is inconvenient that it is difficult to expect a reduction in the amount.

Further, when the exhaust manifold cover is formed by the forming member, the resonance area when vibrated at a high frequency has high sensitivity and large radiated sound because the area per flat portion is large. Which is disadvantageous in practical use.

[0011]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a vehicle exhaust manifold covered by an exhaust manifold cover formed by an upper cover and a lower cover in order to eliminate the above-mentioned inconvenience. A plurality of cross-shaped or T-shaped bead portions formed to have a constant thickness and appearing in a substantially semicircular cross section on a plurality of surfaces of the exhaust manifold cover, and an area between the bead portions is provided. Are densely provided independently of each other in order to reduce the size, and are fixed around the exhaust manifold.

[0012]

According to the invention described above, when forming the exhaust manifold cover, the exhaust manifold cover is formed so as to have a substantially constant thickness, and is made to appear on a plurality of surfaces of the exhaust manifold cover in a substantially semicircular cross section. A plurality of cross-shaped or T-shaped bead portions are provided, densely provided independently of each other so as to reduce the area between the bead portions, fixed around the exhaust manifold, to improve the rigidity of the exhaust manifold cover, The minimum natural frequency is increased, and the radiation sound due to resonance at a high frequency is reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 7 show an embodiment of the present invention. In FIG. 2, reference numeral 2 denotes an engine of a vehicle (not shown), and reference numeral 4 denotes an exhaust manifold.

A catalyst 6 is mounted downstream of the exhaust manifold 4, and a muffler 10 is connected to the catalyst 6 via an exhaust center pipe 8.

The exhaust manifold 4 is covered by an exhaust manifold cover 12. The exhaust manifold cover 12 covers the exhaust manifold 4 from the upper side, and covers the exhaust manifold 4 from the lower side. And a lower cover 16.

Reference numeral 18 denotes a thermofuse disposed in a catalyst case (not shown).

When the exhaust manifold cover 12 comprising the upper cover 14 and the lower cover 16 is formed, the exhaust manifold cover 12 is formed so as to have a substantially constant thickness, and has a substantially semicircular cross section on a plurality of surfaces of the exhaust manifold cover 12. A plurality of exposed cross-shaped or T-shaped bead portions 20 are provided, densely provided independently of each other so as to reduce the area between the bead portions 20, and fixed around the exhaust manifold 4.

That is, the upper cover 14 and the lower cover 1
When forming the molding member 6, as shown in FIG.
The cross-shaped or T-shaped bead portion 20 is densely exposed.

FIGS. 3 and 4 (a), (b), (c)
This is an actual example when the bead portion 20 is exposed on the upper cover 14.

As shown in FIG. 3, the upper cover 14
A bead portion 20-1 having a cross shape, a T-shape, or another shape that is difficult to explain appears, and the resonance area between the bead portions 20-1 is small.

5 and 6 (a), (b),
(C) is an example in which the bead portion 20 is exposed on the lower cover 16.

As shown in FIG. 5, similarly to the above-described upper cover 14, a bead portion 20-2 having a cross shape, a T-shape, or any other shape that is difficult to describe appears on the lower cover 16. The resonance area between the portions 20-2 is small.

When the bead portion 20 is exposed, if the bead portion 20 is exposed to a relatively flat portion or a surface portion of the upper cover 14 or the lower cover 16, the effect of improving the rigidity is further enhanced.

In the vibration generated when the exhaust manifold cover 12 is fixed around the exhaust manifold 4, the lowest natural frequency is determined mainly by the surface bending stiffness, although it depends on the fixing method. .

Next, the operation will be described.

When the engine 2 mounted on a vehicle (not shown) is driven, a radiated sound is generated in the exhaust manifold 4 due to resonance at a high frequency, and the radiated sound collides with the upper cover 14 and the lower cover 16.

At this time, the radiated sound having directivity is finely dispersed by the bead portions 20 formed in the upper cover 14 and the lower cover 16, and the sound pressure level of the radiated sound is reduced.

As a result, the bead portion 20 can be made to appear in a substantially semicircular cross section, the second moment of area can be increased, the surface bending rigidity can be increased, and the exhaust manifold cover 12 can be connected to the exhaust manifold 4. The lowest natural frequency can be raised in the frequency generated at the time of vibration when fixed around.

Further, since the lowest natural frequency can be increased, the sound pressure level of the radiated sound emitted to the outside of the exhaust manifold cover 12 can be reduced, and the quietness can be improved. It is advantageous.

Further, the bead portions 20 are made to appear densely on the exhaust manifold cover 12 so that each bead portion 2 is exposed.
The resonance area at a high frequency between zero can be narrowed, and there is no fear of vibration, and the usability can be improved.

Further, the exhaust manifold cover 12
By making the wall thickness substantially constant, material costs can be reduced, costs can be reduced, and there is an economical advantage as compared with a conventional exhaust manifold cover.

It should be noted that the present invention is not limited to the above-described embodiment, and various application modifications are possible.

For example, in the embodiment of the present invention, the bead portion is exposed on the exhaust manifold cover. However, the exhaust pipe cover, the catalyst case cover, the muffler cover, the worm air cover, the heat shield plate, and the sheet metal The bead portion can also be made to appear on members such as an air cleaner case, a blow-molded box, a dash panel and a floor of a vehicle body, and the surface rigidity of a component having a substantially constant thickness can be improved.

In the embodiment of the present invention, the cross-sectional shape of the bead portion may be substantially semicircular, the cross-sectional shape may be a semi-elliptical shape other than the substantially semicircular shape, or another shape. is there.

[0036]

As described above in detail, according to the present invention, the exhaust manifold cover of the vehicle exhaust manifold covered by the exhaust manifold cover formed by the upper cover and the lower cover has a substantially constant thickness. While forming, a plurality of cross-shaped or T-shaped bead portions that appear in a substantially semicircular cross section on a plurality of surfaces of the exhaust manifold cover are provided independently of each other to reduce the area between the bead portions. Since it is densely provided and fixed around the exhaust manifold, the bead part can appear in a substantially semicircular cross section, the second moment of area increases, the surface bending rigidity can be increased, and the exhaust manifold cover can be The lowest natural frequency can be increased in the frequency generated at the time of vibration when fixed around the exhaust manifold. Further, since the lowest natural frequency can be increased, the sound pressure level of the radiated sound emitted to the outside of the exhaust manifold cover can be reduced, and the quietness can be improved, which is practically advantageous. Furthermore, if the exhaust manifold cover has a structure in which the beads are made to appear densely, the resonance area at a high frequency between the beads can be narrowed, and there is no possibility of vibration, and the usability is improved. I can do it. Furthermore, by making the thickness of the exhaust manifold cover substantially constant, material costs can be reduced and costs can be reduced as compared with the conventional exhaust manifold cover, which is economically advantageous.

[Brief description of the drawings]

FIG. 1 is a schematic view of a bead portion formed on a plate-like member according to an embodiment of the present invention.

FIG. 2 is an assembly diagram of a vehicle exhaust manifold cover.

FIG. 3 is a front view of an upper cover.

FIG. 4A is a left side view of the upper cover. (B)
It is a right view of an upper cover. (C) It is a top view of an upper cover.

FIG. 5 is a front view of a lower cover.

FIG. 6A is a bottom view of the lower cover. (B) It is a top view of a lower cover. FIG. 4C is a right side view of the lower cover.

FIG. 7 is an enlarged explanatory view of a main part of a bead portion.

FIG. 8 is a front view of a molded member showing the prior art of the present invention.

9A is a cross-sectional view taken along line AA of FIG.
(B) It is sectional drawing by the BB line of FIG. (C) FIG.
It is sectional drawing by CC line of FIG.

FIG. 10 is an enlarged view of a main part of a molded member showing another prior art of the present invention.

[Explanation of symbols]

 2 Engine 4 Exhaust manifold 6 Catalyst 8 Exhaust center pipe 10 Muffler 12 Exhaust manifold cover 14 Upper cover 16 Lower cover 20, 20-1, 20-2 Bead portion 22 Molded member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01N 7/14 F01N 7/10 F02B 77/11

Claims (1)

(57) [Claims] 1. An exhaust manifold for a vehicle covered by an exhaust manifold cover formed by an upper cover and a lower cover, wherein the exhaust manifold cover is formed to have a substantially constant thickness, and a plurality of exhaust manifold covers of the exhaust manifold cover are provided. providing a plurality of cross-like or T-shaped bead portions to appear in a substantially semicircular shape in a surface, provided the area between the bead portion densely independently of one another in order to small, the exhaust <br / > Vehicle exhaust manifold cover, which is fixed around the air manifold.