JP2001221043A - Exhaust system structure of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce indoor noise in simple constitution without using an extra part. SOLUTION: An exhaust manifold 1, a catalyst converter 2, a catalyst converter 3, a sub-muffler 4, a main muffler 5 and a tail pipe 6 are arranged in this order along a direction in which exhaust gas flows, each of them is connected to each other by first - fourth exhaust pipes 11-14 and are supported on a car body by support members (first and second support members 21, 22) previously provided at a plural number of positions. It is possible to lower a vibrational level of the first support member 21 as a phase of vibration of an exhaust system structure is slipped in comparison with the same before flattening as a cross-section of a bent part 11b of the first exhaust pipe 11 is flattened so that vibrational level of this support member 21 is reduced though the support member 21 is provided at a position to influence upon indoor noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust system structure for a vehicle.

[0002]

2. Description of the Related Art As shown in FIG. 4, an exhaust system of a vehicle is provided with an exhaust manifold 5 along a flow direction of exhaust gas.
1. The catalytic converter 52, the sub-muffler 54, the main muffler 55, and the tail pipe 56 are arranged in this order, are connected by exhaust pipes 61 to 63, and are supported by support members 71 and 72 at a plurality of predetermined positions. It has a structure supported by the vehicle body. In the exhaust system of this vehicle, an exhaust manifold 51 and a catalytic converter 52
A flexible pipe 65 for absorbing vibration is attached to the exhaust pipe 61 between the two. If flexible pipe 6
If there is no 5, the support members 71 and 72 may resonate due to vibrations caused by engine rolling, pitching or the like or vibrations when traveling on rough roads, causing unpleasant in-vehicle sounds. By providing the support members 71 and 7
2 is suppressed, and the sound in the vehicle is reduced.

[0003]

However, in the configuration shown in FIG. 4, it is necessary to secure a space for mounting the flexible pipe 65, so that there is a problem that it cannot be employed if such a space cannot be secured. . Also, because the flexible pipe 65 is used,
There is also a problem that the cost increases accordingly.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an exhaust system structure for a vehicle which can reduce in-vehicle noise with a simple structure without using separate parts. I do.

[0005]

Means for Solving the Problems and Effects of the Invention In order to solve the above problems, the present invention provides an exhaust system for a vehicle in which an exhaust pipe constituting an exhaust system is supported on a vehicle body by a support member at a predetermined position. It is a structure, so that the vibration level of the support member at the position that affects the interior sound is reduced,
A cross section of the exhaust pipe is flattened.

In the exhaust system structure for a vehicle according to the present invention, the cross section of the exhaust pipe is flattened, so that the phase of the vibration of the exhaust system structure is shifted as compared with before the flattening of the exhaust system structure, and the exhaust pipe structure is mounted at a position that affects the sound inside the vehicle. The vibration level of the support member provided can be reduced, and as a result, the sound in the vehicle can be reduced.

As described above, according to the vehicle exhaust system structure of the present invention, the vehicle interior noise is reduced by a simple structure in which the cross section of the exhaust pipe is flattened without using a flexible pipe as a separate component as in the prior art. Is achieved. In the exhaust system structure for a vehicle according to the present invention, the cross section of the exhaust pipe may be flattened so that the vibration level corresponding to the predetermined engine speed among the support members at the position that affects the interior sound is reduced. preferable. That is, the support member at the position that affects the in-vehicle sound has a plurality of peaks when looking at the vibration level with respect to the engine speed, but it is necessary to reduce the vibration level corresponding to the engine speed that greatly affects the in-vehicle sound. However, this is preferable for effectively reducing the sound inside the vehicle. It should be noted that the engine speed, which greatly affects the sound inside the vehicle, may differ depending on the type of vehicle.

[0008] In the vehicle exhaust system structure of the present invention, it is preferable that the cross section of the exhaust pipe between the exhaust manifold and the catalytic converter be flattened. In this case, since the exhaust pipe between the exhaust manifold and the catalytic converter is close to the engine, the phase of the vibration due to rolling, pitching, etc. of the engine can be effectively shifted.

In the exhaust system structure for a vehicle according to the present invention, when the vibration level of the support member at the position that affects the sound inside the vehicle is the vibration level in the vertical direction of the vehicle, the cross section of the exhaust pipe is crushed in the vertical direction and becomes flat. In the case where the vibration level of the support member at the position affecting the in-vehicle sound is the vibration level in the vehicle left-right direction, it is preferable that the cross section of the exhaust pipe is crushed in the left-right direction and flattened. That is, when the vibration level of the support member is the vibration level in the vehicle vertical direction, when the cross section of the exhaust pipe is crushed in the vertical direction and flattened, the phase of the vibration is shifted and the vibration level can be effectively reduced. it can. In addition, when the vibration level of the support member is the vibration level in the vehicle left-right direction, when the cross section of the exhaust pipe is crushed in the left-right direction and flattened, the phase of the vibration is shifted and the vibration level can be effectively reduced. it can.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view of an exhaust system of a vehicle according to the present embodiment, and FIG. 2 is a sectional view taken along line AA of FIG. In the exhaust system of the vehicle according to the present embodiment, the exhaust manifold 1, the catalytic converter 2, the catalytic converter 3, the sub-muffler 4, the main muffler 5, and the tail pipe 6 are arranged in this order along the exhaust gas flow direction, and each exhaust gas is exhausted. Connected by pipes (first to fourth exhaust pipes 11 to 14) and supported by a vehicle body (not shown) by support members (first and second support members 21 and 22) provided at a plurality of predetermined positions. Have been.

The exhaust pipe includes a first exhaust pipe 11 connecting the exhaust manifold 1 and the catalytic converter 2, and a second exhaust pipe 1 connecting the catalytic converter 2 and the catalytic converter 3.
2. Third connecting the catalytic converter 3 and the sub-muffler 4
The exhaust pipe 13 includes a fourth exhaust pipe 14 connecting the sub-muffler 4 and the main muffler 5. Of these, the first
The exhaust pipe 11 and the fourth exhaust pipe 14 have flanges 11a and 14a as joints in the middle thereof. Also,
The first exhaust pipe 11 is formed so as to extend in a vehicle vertical direction from a connection portion with the exhaust manifold 1 and then bend (referred to as a bent portion 11b) to extend rearward of the vehicle. As shown in FIG. 2, the cross section of the bent portion 11b is crushed in the vertical direction and flattened.

The first support member 21 supports the third exhaust pipe 13 connecting the catalytic converter 3 and the sub-muffler 4 to the vehicle body, and the second support member 22 supports the main muffler 5 to the vehicle body. It is. By the way, since the exhaust system of this vehicle receives vibrations due to rolling and pitching of the engine or vibrations when traveling on rough roads, the first and second support members 21 and 22 vibrate. In this vehicle, the mounting position of the first support member 21 corresponds to a position that greatly affects the sound inside the vehicle, and the vibration level of the first support member 21 near the engine speed of 4500 rpm most affects the sound inside the vehicle. Here, FIG. 3 is a graph showing the relationship between the engine speed and the vibration level of the first support member 21. The solid line relates to the present embodiment, and the broken line relates to the comparative embodiment. Note that the comparative example is the bent portion 11 of the first exhaust pipe 11.
The configuration is the same as that of the present embodiment except that b is not flattened.

In FIG. 3, focusing on the vibration level at an engine speed of 4500 rpm that most affects the in-vehicle sound, the first exhaust pipe 11 is flattened while the vibration level exceeds 80 dB in the comparative example. In the present embodiment, the vibration level is reduced to 65 dB. As a result, in the present embodiment, the sound in the vehicle is reduced as compared with the comparative example.

Looking at the overall shape of the graph, the graph pattern of the present embodiment is obtained by shifting the graph pattern of the comparative example to a lower engine speed.
The degree of flattening of the first exhaust pipe 11 is determined while observing how the vibration level is reduced. At this time, the graph pattern shifts to a lower side of the engine speed as the flattening becomes larger, but if the flattening is made too large, the graph pattern shifts too much and the vibration level at the engine speed of 4500 rpm increases again. Since there is a possibility that a trouble (a crack or the like) may occur in the exhaust pipe, it is determined appropriately in consideration of these.

As described above, according to the vehicle exhaust system of the present embodiment, the cross section of the bent portion 11b of the first exhaust pipe 11 is flattened, so that the vibration of the entire exhaust system is reduced as compared with before the flattening. It is possible to shift the phase and reduce the vibration level of the first support member 21 attached to a position that affects the interior sound, and as a result, the interior noise can be reduced. Therefore, the first exhaust pipe 11 can be used without using a flexible pipe as a separate component as in the related art.
The effect of realizing the reduction of the in-vehicle sound can be obtained by a simple configuration of flattening the cross section of the vehicle.

The embodiments of the present invention are not limited to the above-described embodiments, and it goes without saying that various forms can be adopted as long as they fall within the technical scope of the present invention. For example, in the above-described embodiment, the bent portion 11b of the first exhaust pipe 11 is flattened. However, if the vibration level of the first support member 21 can be reduced, other parts of the first exhaust pipe 11 or other parts may be used. The exhaust pipes 12 to 14 may be flattened. However, since the first exhaust pipe 11 is closer to the engine than the other exhaust pipes, the rolling of the engine,
The phase of vibration due to pitching or the like can be effectively shifted, which is preferable in this respect.

In the above embodiment, the case where the vibration level of the first support member 21 is in the vertical direction of the vehicle has been described. However, when the vibration level of the first support member 21 is in the horizontal direction of the vehicle, the first exhaust pipe 11 What is necessary is just to flatten the cross section by crushing it in the left-right direction. Thereby, the phase of the vibration is shifted and the vibration level can be effectively reduced.

Further, in the above embodiment, the catalytic converter 2
However, it is needless to say that the present invention can be similarly applied to the case where there is one catalytic converter (three-way catalyst) as shown in FIG.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an exhaust system of a vehicle according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a graph showing a relationship between an engine speed and a vibration level of a first support member.

FIG. 4 is a schematic explanatory view of an exhaust system of a conventional vehicle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exhaust manifold, 2 ... Catalytic converter, 3 ... Catalytic converter, 4 ... Sub muffler,
5 ... Main muffler, 6 ... Tail pipe, 11-
14 ... first to fourth exhaust pipes, 11b ... bent parts,
21, 22 ... first and second support members.

Continued on the front page (72) Inventor Masateru Akiyama 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G004 AA01 BA04 DA13 GA04

Claims (4)

[Claims] 1. An exhaust system structure for a vehicle in which an exhaust pipe constituting an exhaust system is supported on a vehicle body by a support member at a predetermined position, wherein a vibration level of the support member at a position that influences vehicle interior noise is reduced. An exhaust system structure for a vehicle, wherein a cross section of the exhaust pipe is flattened so as to reduce the exhaust pipe. 2. An exhaust system structure for a vehicle according to claim 1, wherein said exhaust member is configured to reduce a vibration level corresponding to a predetermined engine speed of a support member at a position affecting said in-vehicle sound. Exhaust system structure for vehicles where the cross section of the pipe is flattened. 3. The exhaust system structure for a vehicle according to claim 1, wherein the vibration level of the support member at a position that affects the sound inside the vehicle is reduced between the exhaust manifold and the catalytic converter. The exhaust system structure of a vehicle in which the cross section of the exhaust pipe is flattened. 4. The exhaust system structure for a vehicle according to claim 1, wherein the vibration level of the support member at a position that affects the sound inside the vehicle is a vertical vibration level of the vehicle. The cross section of the exhaust pipe is crushed in the vertical direction and flattened, and when the vibration level of the support member at the position affecting the in-vehicle sound is the vibration level in the horizontal direction of the vehicle, the cross section of the exhaust pipe is horizontal. Exhaust system structure of a crushed and flattened vehicle.