JPH06264710A - Exhaust device for vehicle - Google Patents

Abstract

PURPOSE:To embody lighter weight, the manufacturing cost reduction, higher degree of freedom in space and easier assembly comparing with the exhaust system by the prior art by preventing occurrence of unusual noise and resonance caused by pulsation exhaust gas discharged from an engine mounted type muffler equipped with the exhaust gas purification function by means of solely an exhaust pipe. CONSTITUTION:Regarding a vehicle exhaust device composed of a muffler 2, which is mounted and supported directly on an internal combustion engine of the vehicle and equipped with the exhaust gas purification function, and an exhaust system connected to the muffler 2, the exhaust system is formed by a nonmetalic heat resisting elastic pipe 22.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vehicle exhaust system.

[0002]

2. Description of the Related Art A muffler with a built-in catalytic converter that is directly attached to an internal combustion engine and muffles exhaust noise of the internal combustion engine (commonly referred to as an exhaust manifold) is provided with the silencer. The exhaust system is generally
It is configured as shown in.

In FIG. 5, 1 is an internal combustion engine, 2 is an exhaust manifold, which is attached to the engine 1 by an exhaust manifold 3. 4 is a muffler outer cylinder of the exhaust manifold 2, 5 is a muffler end plate fixed to the muffler outer cylinder,
An outer pipe 6 is welded to the muffler end plate 5.
Reference numeral 7 is a first exhaust pipe, the front end of which is connected to the outlet pipe 6 by a flange 8 and the rear end of which is welded to the front end of a flexible pipe 9.

Reference numeral 10 is a second exhaust pipe, the front end of which is welded to the rear end of the flexible pipe 9 and the rear end of which is welded to the front end of the sub-muffler 11. Reference numeral 12 denotes a third exhaust pipe, the front end of which is welded to the rear end of the sub-muffler 11, and the rear end is open.

Reference numeral 13 is a vehicle body, and 14 and 15 are suspension supports for attaching the exhaust pipes 10 and 12 to the vehicle body 13. In such an exhaust manifold exhaust system, the first, second and third exhaust pipes 7, 10 and 12 are conventionally formed of hard metal pipes.

[0006]

In the exhaust manifold exhaust system, originally, sufficient exhaust volume can be obtained in the exhaust manifold 2, but the exhaust gas is elongated from the exhaust manifold 2 to the discharge port at the rear of the vehicle. You have to guide with an exhaust pipe.

However, in the conventional exhaust pipe formed of a hard metal pipe as described above, the exhaust gas energy is attenuated by the exhaust manifold so that a sufficient volume can be obtained. However, there is still enough energy to generate the standing wave in the pipe, and the standing wave is generated in the flow process of the exhaust gas or abnormal noise is radiated from the wall of the pipe. Therefore, it is necessary to suppress the generation of standing waves and prevent the generation of abnormal noise by arranging the sub-muffler having an appropriate capacity as described above, or to eliminate the abnormal noise caused by the standing wave in the pipe.

Further, a mechanical vibration system is formed by the long metal pipe and the sub muffler, which resonates with the vibration of the internal combustion engine and the vehicle vibration to generate noise and vibration. If the resonance becomes excessive, the exhaust system is damaged. There is also a connecting problem. As a countermeasure against this vibration, a flexible coupling or a mass damper may be added to slightly shift the resonance frequency of the exhaust system, but this is not a fundamental solution. In addition, the weight of the exhaust system increases.

An object of the present invention is to propose a vehicle exhaust system capable of solving each of the above problems.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the first invention is a silencer which is directly attached to and supported by an internal combustion engine of a vehicle and has an exhaust gas purification function, and the silencer. In a vehicle exhaust system including an exhaust system connected to, the exhaust system connected to the silencer is formed of a non-metal heat-resistant elastic tube.

A second aspect of the invention is characterized in that the silencer and the heat resistant elastic tube are connected via a heat insulating member. A third aspect of the invention is characterized in that a heat exchange section is provided in the middle of the heat resistant elastic tube.

A fourth aspect of the present invention is that the heat-resistant elastic tube has an outer periphery,
It is characterized in that the heat insulating material is wound only around the portion where heat dissipation is desired to be avoided. A fifth aspect of the invention is characterized in that the heat resistant elastic tube is fitted to a clip member provided on a vehicle.

[0013]

The exhaust gas discharged from the exhaust manifold (3) of the internal combustion engine (1) passes through the exhaust manifold (2), the outlet pipe (20) and the exhaust pipe (22) to reach the rearmost portion of the vehicle. It is discharged to the atmosphere from the positioned downstream end (22b).

In the process of the exhaust gas passing through the exhaust manifold (2), the exhaust gas is silenced (energy attenuated) and purified, and the temperature of the exhaust gas drops to about 700 ° C. Max.

Further, since the exhaust pipe (22) has sufficient flexibility and elasticity, the pulsating energy of the pressure wave, which is a longitudinal wave of the exhaust gas, passes through the exhaust pipe (22) in the process of passing through the exhaust pipe (22). It is spent in the radial expansion and contraction of the pipe wall of (22), and the standing wave inside the pipe is not generated. Furthermore, the pipe radiated sound generated by the gas pulsation hitting the pipe wall from the inside does not occur.

Further, the mechanical vibration transmitted from the exhaust manifold (2) to the exhaust pipe (22) does not resonate because the exhaust pipe (22) is made of a flexible material and has a very low resonance point.

[0017]

EXAMPLE A first example of the present invention shown in FIGS. 1 and 2 will be described. 1 is an internal combustion engine, 2 is an exhaust manifold, 3
Is an exhaust manifold, 4 is a muffler outer cylinder, and these are the same as the conventional structure.

Reference numeral 20 is an outlet pipe projecting from the exhaust manifold 2 and its projecting length is short. Reference numeral 21 denotes an annular heat insulating member wound around the outer periphery of the projecting end of the outlet pipe 20 to prevent heat generated in the exhaust manifold 2 from being transferred from the heat insulating member 21 to an exhaust pipe 22 described later. is there. The material of the heat insulating member 21 may be a known gasket material, for example, but a ceramic material is preferable.

Reference numeral 22 denotes an exhaust pipe, the upstream opening end 22a of which is fitted on the outer circumference of the heat insulating member 21 and the outer circumference of which is tightened by a tightening band 27 so that the upstream opening end of the exhaust pipe 22 is It is fixedly connected to the outlet pipe 20 via a heat insulating member 21.

The exhaust pipe 22 is preferably 5
Heat resistance that is flexible and elastic, with heat insulation of around 00 ° C (when the exhaust gas temperature is high, the actual required adiabatic temperature is 500 ° C or less because cooling is performed by the running wind) It is formed of an elastic tube, for example, a carbon fiber, an aramid fiber, a fluorine coating sheet, a ceramic paper, or the like and formed into a tubular shape.

The exhaust pipe 22 and its connecting portion have not been kept highly airtight and heat-retaining, but since they have passed through the catalyst, they are not required to be completely airtight and heat-retaining.

Reference numeral 23 is a clip provided on the vehicle body 24, and the exhaust pipe 22 is fitted and held in the clip 23. The clip 23
Are provided so as to hold the exhaust pipes 22 at several places.

In this embodiment, the exhaust gas discharged from the exhaust manifold 3 of the internal combustion engine 1 passes through the exhaust manifold 2, the outlet pipe 20 and the exhaust pipe 22, and is located at the rear end of the vehicle at the rear end. The air is discharged from the end 22b to the atmosphere.

In the process in which the exhaust gas passes through the exhaust manifold 2, the noise is reduced (energy attenuation) and purification is performed, and the temperature of the exhaust gas drops to about 700 ° C. Max. Further, since the exhaust pipe 22 has sufficient flexibility and elasticity, in the process of the exhaust gas passing through the exhaust pipe 22, the pulsating energy of the pressure wave, which is a longitudinal wave of the exhaust gas, is generated in the radial direction of the pipe wall of the exhaust pipe 22. It is spent on the expansion and contraction of the pipe, and the standing wave in the pipe is not generated. Furthermore, the pipe radiated sound generated by the gas pulsation hitting the pipe wall from the inside does not occur.

Further, the mechanical vibration transmitted from the exhaust manifold 2 to the exhaust pipe 22 has a very low resonance point because the exhaust pipe 22 is made of a flexible material,
It will not resonate.

FIG. 3 shows a second embodiment of the present invention.
In the exhaust pipe 22 in the above embodiment,
A heat insulating material 25, for example, ceramic paper is wound around the outer peripheral surface of the portion where heat damage to the peripheral components is concerned.

FIG. 4 shows a third embodiment of the present invention.
A heat exchange section 26 is provided in the middle of the exhaust pipe 22 of the first embodiment. A metal heat sink, a heat pipe, or the like is used as the heat exchange section 26, and is fixed to the vehicle body 24. According to this embodiment, the temperature of the exhaust gas flowing through the exhaust pipe 22 can be lowered and the durability of the exhaust pipe 22 can be improved. Further, the exhaust pipe 22 can be made of a material having low heat resistance, for example, a heat resistant resin.

Next, a comparison between the exhaust system of this embodiment and the conventional exhaust system will be described. Regarding weight, in the conventional exhaust system, metal exhaust pipes 7, 10, 12 + metal flexible pipe 9 + metal sub-muffler 11 + metal support (bracket) 14, 1
In contrast to this, in the present embodiment, since the non-metallic exhaust pipe 22 + the resin clip 23 + the heat insulating member 21 is used, the weight is reduced in the present embodiment. Regarding the product cost, in the present embodiment, the cost is lower than that of the conventional exhaust system, and the cost is low because the conventional flexible pipe 9 and the sub muffler 11 are not used. Regarding the degree of freedom of space, this embodiment can omit the large-diameter flexible pipe 9 and the sub-muffler 11 as compared with the conventional exhaust system, and the exhaust pipe 22 can be formed of a flexible material to be freely handled. Therefore, the degree of freedom of space increases. Furthermore, the margin of the minimum ground clearance also increases. Regarding assembly, in the conventional exhaust system, a plurality of exhaust pipes 7, 10 and 12 are connected to the outlet pipe 6 and the sub muffler 1.
In the present embodiment, the exhaust pipe 22 is only connected to the exhaust manifold pipe 22 and is hung on the supports 14 and 15, so that it is necessary to connect the exhaust pipe 22 to the supports 14 and 15. In the example, the exhaust system is easily assembled. Others In the exhaust system of this embodiment, compared with the conventional exhaust system,
Since the number of parts is small, parts can be easily managed and transported.

[0029]

As described above, according to the exhaust manifold exhaust system of the present invention, it is possible to simultaneously prevent generation of abnormal noise due to exhaust gas pulsation and resonance due to the rigid exhaust system, and muffling and damaging the exhaust system. Can be prevented.

As a result, the sub-muffler, the flexible coupling, the mass damper, etc., which are additionally provided in the conventional exhaust manifold exhaust system made of metal, become unnecessary,
The exhaust system of the present invention is reduced in weight and cost as compared with the conventional exhaust system, and further, the degree of freedom of space is increased and the margin of the minimum ground clearance is increased.

Furthermore, the number of parts in the exhaust system is reduced, assembly is easy, and parts management and transportation are easy.

[Brief description of drawings]

FIG. 1 is a diagram showing an exhaust system of a first embodiment of the present invention.

FIG. 2 is a sectional view of the connecting portion.

FIG. 3 is a diagram showing an exhaust system of a second embodiment of the present invention.

FIG. 4 is a diagram showing an exhaust system of a third embodiment of the present invention.

FIG. 5 is a diagram showing a conventional exhaust system.

[Explanation of symbols]

 1 Internal Combustion Engine 2 Silencer 20 Outlet Pipe 21 Insulation Member 22 Exhaust Pipe 23 Clip 24 Vehicle Body 25 Insulation Material

Claims (5)

[Claims] 1. A direct attachment to and support of an internal combustion engine of a vehicle,
In a vehicle exhaust system including a silencer having an exhaust gas purification function and an exhaust system connected to the silencer, the exhaust system connected to the silencer is formed of a non-metallic heat-resistant elastic tube. A characteristic vehicle exhaust system. 2. The vehicle exhaust system according to claim 1, wherein the silencer and the heat resistant elastic tube are connected via a heat insulating member. 3. The vehicle exhaust system according to claim 1, wherein a heat exchange section is provided in the middle of the heat resistant elastic tube. 4. The vehicle exhaust system device according to claim 1, wherein a heat insulating material is wound around an outer periphery of the heat resistant elastic tube only at a portion where heat radiation is desired to be avoided. 5. The vehicle exhaust system according to claim 1, wherein the heat resistant elastic tube is fitted to a clip member provided on the vehicle.