JP2000008830A - Resonator of vehicle exhaust system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost of a resonator and prevent the exhaust gas of high temperature from flowing down to the resonator even when there is a hole on the resonator by molding the resonator mounted on an exhaust pipe through a branch pipe from a resin, and providing the branch pipe with a length of a specific dimension or over. SOLUTION: A resonator 28 is connected through a branch pipe 27 between a catalytic converter 23 and a muffler 25 in an exhaust pipe 17 connected to an engine 21 through an exhaust manifold 19. This resonator 28 is formed by, for example, blow molding a resin of low heat resistance composed of, for example, polypropylene or the like, and the branch pipe 27 is formed by using, for example, stailess steel which is a material same as that of the exhaust pipe 17 with 400 mm length or more. That is, by determining the length to be 400 mm or more, a temperature of the branch pipe 27 becomes equal to the outside air temperature, so that the resonator 29 can be made of the resin of low heat resistance without performing the heat insulating treatment or the like, and the resonator body can be lined with a rubber film to prevent the flowing-down of the exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resonator device mounted on a vehicle exhaust system.

[0002]

2. Description of the Related Art In order to reduce exhaust noise during vehicle running,
Conventionally, a main muffler and a sub-muffler are mounted on a vehicle exhaust system.
As shown in FIG. 1, in recent years, a branch pipe 7 is connected to an exhaust pipe 5 and an end of the main muffler 1 and the sub-muffler 3 are connected to an exhaust pipe 5 in order to improve noise reduction performance and reduce the size and weight of the main muffler 1 and the sub-muffler 3. There is known a resonator device 13 of a vehicle exhaust system 11 to which a metal resonator 9 that is independent from a vehicle is attached.

Normally, the exhaust gas flowing down the exhaust pipe 5 easily reaches a high temperature of about 500 ° C. However, due to the structure, the high-temperature exhaust gas does not flow down inside the resonator 9. It is being studied to mold this with resin instead of 9. Thus, if the resonator can be formed of resin, the shape can be freely formed according to the layout under the floor of the vehicle as compared with the metal resonator 9, and the resonator itself can be reduced in weight. Since the mounting bracket can be integrally formed, the resonator 9 is connected to the sub-muffler 3 through the bracket 15 as shown in FIG.
It is not necessary to fix to a vehicle body or the like directly with a mounting bracket integrally formed of resin.

[0004]

However, since the resonator is connected to the exhaust pipe through the branch pipe, it is affected by heat conduction from the branch pipe and heat of exhaust gas convection in the branch pipe. Therefore, when forming the resonator with a resin, it is necessary to use a heat insulating material or a resin having high heat resistance, and it has been pointed out that the weight of the resonator itself can be reduced, but the cost is increased.

[0005] When a resin resonator is used,
If the resonator is damaged by rock splashes or the like while the vehicle is running, high-temperature exhaust gas will flow down the resonator and the resin will melt.However, due to safety measures, the melting of the resonator Must be prevented. The present invention has been devised in view of such circumstances, and provides a resonator device that can be formed of a low-cost, low-heat-resistance resin when mounting the resonator through a branch pipe in a vehicle exhaust system. The primary purpose is to do so.

A second object of the present invention is to provide a vehicle exhaust system in which high-temperature exhaust gas is not likely to flow down the resonator even if a hole is made in the resin-made resonator due to a stone splash or the like while the vehicle is running. To provide a resonator device.

[0007]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 is directed to a resonator device for a vehicle exhaust system in which a resonator is mounted on an exhaust pipe via a branch pipe. It is characterized in that the branch pipe is formed with a length of 400 mm or more while being formed of resin.

[0008] The invention according to claim 2 is based on claim 1.
In the vehicle exhaust system resonator device described above, the resonator has a double structure of a resonator main body formed of resin and an airtight soft film disposed inside the resonator main body. According to a third aspect of the present invention, in the resonator device for a vehicle exhaust system according to the second aspect, a soft film is internally adhered to the resonator body. Item 2. The resonator device for a vehicle exhaust system according to Item 2, wherein an air layer is provided between the soft film and the resonator main body, and the soft film is expanded by exhaust gas pressure.

(Operation) According to the invention of each claim, if a resonator formed of resin is mounted on the exhaust pipe via the branch pipe, the resonator can be formed according to the capacity of the resonator, the length of the branch pipe, and the pipe diameter. Exhaust noise of a predetermined frequency is muted. In addition, since the resonator is connected to the exhaust pipe through the branch pipe, it is affected by heat conduction from the branch pipe and heat of exhaust gas convection in the branch pipe, but the branch pipe is formed into a length of 400 mm or more. Therefore, each temperature of the connection portion with the resonator decreases to about the outside air temperature.

[0010] On the other hand, even if the resonator body is damaged by, for example, a stone splash while the vehicle is running, the soft film forms the exhaust gas in the resonator according to the invention according to the second to fourth aspects. Prevents gas leakage by preventing flow.
In the resonator device according to the fourth aspect, exhaust pulsation of a wide frequency range is absorbed and silenced by the resonator action of the resonator and the membrane vibration of the expanded soft membrane.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view of a vehicle exhaust system equipped with a resonator device according to one embodiment of the present invention. Reference numeral 17 denotes an exhaust pipe connected to the engine 21 via an exhaust manifold 19, and a catalytic converter 23 and a muffler 25 are mounted on the exhaust pipe 17 as in the related art.

The catalytic converter 23 and the muffler 25
A resonator device 31 composed of a branch pipe 27 connected to the exhaust pipe 17 and a cylindrical resonator 29 attached to the end of the pipe is mounted on the exhaust pipe 17 between the two pipes. PP (polypropylene; heat deformation temperature 145 ° C) and PA6 (nylon 6; heat deformation temperature 20)
0 ° C) and blow molding with a resin with low heat resistance.
It is characterized in that the branch pipe 27 is formed into a length of 400 mm or more using the same material (stainless steel) as the exhaust pipe 17, and thus the length of the branch pipe 27 is set to a desired length or more. Therefore, without using a means such as heat insulation, the resonator 29
Can be molded with a resin having low heat resistance such as PP or PA6.

FIG. 2 shows an experimental device for measuring the "temperature distribution of the branch pipe due to a change in temperature at the inlet of the branch pipe". The exhaust pipe 17 is connected, a branch pipe 27 is connected in the middle of the exhaust pipe 17, and the pipe end is closed with a plug 33, so that no exhaust gas flow occurs in the branch pipe 27.

Then, the engine 21 is rotated under a high load, and the gas temperature at the branch between the exhaust pipe 17 and the branch pipe 27 is set to 500 ° C. to 7 ° C.
The temperature was set to 00 ° C., and the exhaust gas in the branch pipe 27 and the temperature distribution on the surface of the branch pipe 27 were measured as shown in the figure. The branch gas temperature simulates the temperature condition of the maximum temperature during normal vehicle running.

FIG. 3 shows “change in gas temperature inside the branch pipe” based on the above experimental apparatus, and FIG. 4 shows “change in surface temperature of the branch pipe”. It is clear that if the length is set to 400 mm or more, each temperature becomes the same as the outside air temperature. As a result, if the length of the branch pipe 27 is set in this way, the heat resistance of the resonator 29 can be reduced without performing a process such as heat insulation. It is possible to mold with a low resin.

Therefore, as described above, this embodiment uses the same material as the exhaust pipe 17 to make the branch pipe 27 400 mm.
Molded to the above length, and set the resonator 29 to PP or PA6
Blow molded with a resin having low heat resistance. Since the present embodiment is configured as described above, if the resonator 29 is mounted at a predetermined position of the exhaust pipe 17 via the branch pipe 27 thus formed, the capacity of the resonator 29 and the Exhaust noise of a specific frequency is silenced according to the length and the pipe diameter.

Since the resonator 29 is connected to the exhaust pipe 17 via the branch pipe 27, the resonator 29 is affected by heat conduction from the branch pipe 27 and heat of exhaust gas convection in the branch pipe 27. Is formed to have a length of 400 mm or more, so that the temperature of each connecting portion with the resonator 29 decreases to about the outside air temperature. As described above, according to the present embodiment, when the resonator 29 is made of resin, the branch pipe 2
By forming the resin 7 into a length of 400 mm or more, the resonator 29 can be formed of a resin having low heat resistance without performing a process such as heat insulation, so that a heat-resistant resin or a heat insulating material is not required. Cost reduction,
Since the resonator 29 is formed of resin, the shape of the resonator 29 can be freely formed according to the layout under the vehicle floor as compared with the resonator device 13 shown in FIG. Since it can be integrally formed, there is no need to fix the resonator 9 to the sub-muffler 3 or the like via the bracket 15 as shown in FIG. 11, and there is an advantage that the number of parts can be reduced and the weight can be reduced.

Further, by setting the length of the branch pipe 27 as described above, it is used between the branch pipe 27 and the resonator 29 as a mount rubber of a radiator or the like as in the resonator device 31-1 shown in FIG. EP used for CR (chloroprene rubber; heat-resistant temperature 100 ° C) and radiator hoses
A rubber tube 35 having low heat resistance such as DM (ethylene propylene rubber; heat-resistant temperature of 150 ° C.) can be attached without a heat insulating structure.

Thus, according to the resonator device 31-1, in addition to the effect of the resonator device 31 shown in FIG. 1, vibration can be absorbed by the rubber tube 35 during running of the vehicle.
It has the advantage that it can cope with some offset and does not require the mounting accuracy of the resonator 29. FIG. 6 shows an embodiment of the resonator device according to claim 2 and claim 3. Hereinafter, this embodiment will be described with reference to the drawings, and the same components as those in the embodiment shown in FIG. The description thereof will be omitted.

In the figure, reference numeral 37 denotes a resonator mounted on the pipe end of the branch pipe 27. The resonator 37 is a cylindrical resonator main body 3 formed of the same material as the resonator 29.
The resonator device 31 according to the present embodiment has a dual structure of a rubber film 37b such as CR or EPDM that is air-tightly bonded inside the resonator body 37a.
Reference numeral -2 indicates that the resonator 37 is mounted on the exhaust pipe 17 via the branch pipe 27.

Since the present embodiment is configured as described above, similarly to the embodiment shown in FIG. 1, if the resonator 37 is mounted on the exhaust pipe 17 via the branch pipe 27, the capacity of the resonator 37 and the branch pipe Exhaust noise of a specific frequency is muted according to the length and the pipe diameter of 27. Further, since the resonator 37 is connected to the exhaust pipe 17 via the branch pipe 27, the resonator 37 is affected by heat conduction from the branch pipe 27 and heat of exhaust gas convection in the branch pipe 27.
mm or more, the resonator 37
Each temperature at the connection with the temperature drops to about the outside air temperature.

The rubber film 37b prevents the gas from leaking out of the resonator 37 by preventing the exhaust gas from flowing down even if the resonator body 37a is damaged by a stone splash while the vehicle is running. Become. FIG. 7 shows that the pipe end of the branch pipe 27 was damaged by the resonator using the experimental apparatus shown in FIG. 2 (in FIGS. 8 and 9, “muffler damage” means “damage of the resonator”). An experiment was conducted by changing the diameter of the small hole, and the engine 21 was rotated under a high load, and the temperature of the gas at the branch portion was adjusted to 60 °.
At 0 ° C., the exhaust gas in the branch pipe 27 and the temperature distribution on the surface of the branch pipe 27 were measured at each part of the branch pipe 27.

FIG. 8 shows the "change in gas temperature inside the branch pipe" based on the experimental apparatus described above, and FIG. 9 shows the "change in surface temperature of the branch pipe".
By setting the length of the branch pipe 27 to 400 mm or more, each temperature becomes equal to the outside air temperature. However, as the hole diameter increases, the gas flow to the branch pipe 27 increases, and the temperature of each part rises.

Therefore, as described above, the present embodiment employs 4
A resonator main body 37a formed of a resin having low heat resistance is mounted on a branch pipe 27 formed to a length of 00 mm or more, and a rubber film 37b for preventing gas leakage is adhered inside the resonator main body 37a. Therefore, according to the present embodiment, similarly to the embodiment of FIG. 1, the resonator 37 can be formed of a resin having low heat resistance, and even if the resonator body 37a is damaged by a stone while the vehicle is running. Thus, it is possible to prevent the occurrence of gas leakage.

FIG. 10 shows an embodiment of the resonator device according to claims 2 and 4, wherein 39 is a branch pipe.
7 and the resonator 3
Reference numeral 9 denotes a rubber body made of the same material and the same shape as the resonator body 37a, and a balloon-shaped CR or EPDM attached to the insertion side end of the branch pipe 27 protruding into the resonator body 39a. Membrane 39
b, the rubber film 39b and the resonator body 39a
The rubber layer 39b is expanded by the exhaust gas pressure applied to the branch pipe 27, as shown in FIG.
When pulsation enters the expanded rubber film 39b, exhaust pulsation of a specific frequency is absorbed by film vibration (resonance) of the rubber film 39b.

Since the resonator device 31-3 according to this embodiment is configured as described above, if the resonator 39 is mounted on the exhaust pipe 17 through the branch pipe 27, the rubber film 3
Exhaust noise of a specific frequency is silenced by a resonator action in accordance with the capacity of 9b and the length and diameter of the branch pipe 27, and exhaust pulsation of another specific frequency is absorbed and silenced by the film vibration of the rubber film 39b. It will be.

Further, even if the resonator body 39a receives damage such as a hole caused by a stone splash while the vehicle is running, the rubber film 39b prevents the exhaust gas from flowing down in the resonator 39 and prevents gas leakage. Therefore, according to the present embodiment, similarly to the embodiment of FIG. 6, the resonator 39 can be formed of a resin having low heat resistance, and even if the resonator main body 37a is damaged by a stone while the vehicle is running,
Although it is possible to prevent the occurrence of gas leakage, according to the present embodiment, there is an advantage that a wide range of exhaust noise can be suppressed by the resonator effect and the film vibration of the rubber film 39b.

FIGS. 6 and 10 show a rubber film 37 as a soft film provided in the resin resonator bodies 37a and 39a.
Although b and 39b were used, air-tight vinyl or the like may be used instead of the rubber material. Although not shown, a detachable cap is attached to the resonator body 39a with airtightness, and the pressure of the air layer 39c is adjusted to adjust the pressure of the air layer 39c.
The tension of b may be changed. According to such a structure, the resonance frequency of the rubber film 39b can be changed as appropriate.

[0029]

As described above, according to the resonator device of the vehicle exhaust system according to each claim, it is possible to mold the resonator with a resin having low heat resistance without performing a process such as heat insulation. This eliminates the need for highly heat-resistant resin and heat insulating material, thereby reducing costs.Because the resonator is made of resin, the resonator can be shaped according to the layout under the vehicle floor compared to the conventional case where the resonator is molded with metal. Since the shape can be freely formed, the resonator itself can be reduced in weight, and the mounting bracket can be integrally formed, there is no need to fix the resonator to an exhaust pipe or the like via a bracket as in the past, reducing the number of parts. There is an advantage that the weight can be reduced.

According to the resonator device of the second to fourth aspects, even if the resonator is damaged by a stone splash or the like while the vehicle is traveling, there is no gas leakage and the resonator may be melted. In addition, the resonator device according to claim 4 has an advantage that a wide range of exhaust noise can be suppressed by the resonator effect and the vibration of the soft film.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a vehicle exhaust system equipped with a resonator device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an experimental device for measuring a temperature distribution of a branch pipe due to a temperature change at a branch pipe inlet.

FIG. 3 is a graph showing a change in gas temperature inside a branch pipe.

FIG. 4 is a graph showing a change in a branch pipe surface temperature.

FIG. 5 is a schematic diagram of a vehicle exhaust system to which a modified example of the resonator device shown in FIG. 1 is mounted.

FIG. 6 is a sectional view of a resonator used in a resonator device according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of an experimental apparatus for measuring a temperature distribution of a branch pipe due to a temperature change at a branch pipe inlet.

FIG. 8 is a graph showing a change in gas temperature inside a branch pipe.

FIG. 9 is a graph showing a change in a branch pipe surface temperature.

FIG. 10 is a sectional view of a resonator used in a resonator device according to an embodiment of the present invention.

FIG. 11 is an overall perspective view of a vehicle exhaust system equipped with a conventional resonator device.

[Explanation of symbols]

 17 Exhaust pipe 25 Muffler 27 Branch pipe 29, 37, 39 Resonator 31, 31-1, 31-2, 31-3 Resonator device 35 Rubber pipe 37a, 39a Resonator main body 37b, 39b Rubber film 39c Air layer

Claims (4)

[Claims] 1. A vehicle exhaust system having a resonator (29, 37, 39) mounted on an exhaust pipe (17) via a branch pipe (27), wherein the resonator (29, 37, 39) includes: A resonator device for a vehicle exhaust system, wherein the branch tube (27) is formed with a length of 400 mm or more while being formed of resin. 2. A resonator body (37a, 39a) formed by molding a resonator (37, 39) with a resin, and an airtight soft film (37b, 39b) disposed inside the resonator body (37a, 39a). 2. The resonator device for a vehicle exhaust system according to claim 1, wherein the resonator device has a dual structure. 3. The resonator device for a vehicle exhaust system according to claim 2, wherein the soft film (37b) is internally attached to the resonator body (37a). 4. A soft film (39b) and a resonator body (3)
The resonator device according to claim 2, wherein an air space (39c) is provided between the soft film (9c) and the soft film (39b) due to exhaust gas pressure.