JP2000257418A - Exhaust silencer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high silencer effect when exhaust gas flow rate is low, while maintaining power performance when exhaust gas flow rate is high, in a exhaust silencer where a sub muffler is provided between a catalyst converter and a main muffler. SOLUTION: A sub muffler 2 is provided between a catalyst converter 1, which purifies exhaust gas and a main muffler 3 which reduces exhaust noise. An expansion chamber is provided in the sub muffler 2 and a valve device 9 which makes a flow path area of exhaust gas variable is provided between the expansion chamber and the catalyst converter 1. With this configuration, silencer operates immediately after exhaust noise is generated with increased energy after being heated up inside the catalyst converter. For instance, when an exhaust gas flow is low, flow path area of the exhaust gas is controlled to be smaller by the valve device 9 and expansion ratio with regard to the expansion chamber of the sub muffler 2 is made larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust silencer, and more particularly to an exhaust silencer suitable for an exhaust system of a vehicle.

[0002]

2. Description of the Related Art Recently, an exhaust muffler connected to an internal combustion engine of a vehicle includes a catalytic converter for purifying exhaust gas, and a main muffler and a sub-muffler for reducing exhaust noise. Regarding this exhaust silencer, the main muffler is generally arranged behind the vehicle because it has a large capacity and is difficult to mount on a vehicle, and the sub-muffler is arranged between the catalytic converter and the main muffler. Furthermore, various measures have been taken to satisfy conflicting demands such as silence and improvement of power performance. For example, Japanese Patent Publication No. 62-24609 discloses a downstream side of an end of an exhaust pipe connected to a main muffler. An exhaust silencer provided with a reed valve has been proposed.

The exhaust muffler described in the above-mentioned Japanese Patent Publication No. 62-24609 exhibits an excellent muffling effect even at low output and low revolution while maintaining a large muffling effect at high output and high revolution. For the purpose, a reed valve opposed to the exhaust pipe opening opening into the expansion chamber with a predetermined gap in an engine stopped state is arranged, and the area of the exhaust pipe opening changes according to the engine output. is there.

[0004] Japanese Utility Model Publication No. 4-20976 discloses that
There has been proposed an exhaust pipe silencer in which a butterfly valve is provided in the exhaust pipe on the upstream side of the main muffler. In this publication, a butterfly valve is provided in the middle of an exhaust pipe for the purpose of sufficiently reducing the airflow noise of a high frequency region component and the noise level of a low to middle frequency region component in accordance with the operation state of an engine. An opening / closing annular ring plate pivotally supported by the exhaust pipe so as to form a gap between the inner wall of the exhaust pipe and a peripheral edge thereof; Or it is constituted by a circular inner peripheral plate pivotally supported by an annular ring plate.

[0005]

The exhaust mufflers described in the above publications all control the opening of a reed valve or a butterfly valve in accordance with the operating condition of an internal combustion engine, so that a high exhaust gas flow rate can be achieved. Without impairing the power performance,
It is intended to achieve a high noise reduction effect even at low exhaust gas flow rates. However, a sufficient silencing effect cannot be expected simply by providing a reed valve on the main muffler or by providing a butterfly valve on the exhaust pipe upstream of the main muffler as described in the above-mentioned publication.

Accordingly, the present invention provides an exhaust silencer in which a sub-muffler is disposed between a catalytic converter and a main muffler, and obtains a high silencing effect at a low exhaust gas flow while maintaining power performance at a high exhaust gas flow. That is the task.

[0007]

According to a first aspect of the present invention, there is provided a fuel cell system comprising: a catalyst converter for purifying exhaust gas; and a main muffler for reducing exhaust noise. In an exhaust silencer provided with a sub-muffler, an expansion chamber is provided in the sub-muffler, and a valve device for varying the flow area of exhaust gas is provided between the expansion chamber and the catalytic converter. Things. Thus, the exhaust noise heated in the catalytic converter and having increased energy is immediately silenced. For example, when the exhaust gas flow rate is low, the exhaust gas flow area is controlled by the valve device to be small, and the sub-muffler is controlled. Since the expansion ratio of the airbag to the expansion chamber is increased, a good noise reduction effect can be obtained.

[0008] The valve device may be configured as follows.
A valve member for varying the flow area of the exhaust gas; and a biasing means for biasing the valve member in a direction in which the flow area of the exhaust gas is minimized. It is preferable to drive the exhaust gas in a direction in which the flow area of the exhaust gas increases against the urging force of the urging means in accordance with the increase in the flow rate of the exhaust gas. As the urging means, for example, a coil spring can be used.

Further, as set forth in claim 3, the valve member is disposed on the upstream side of the expansion chamber in the sub-muffler, and the urging means is provided in the sub-muffler so as to shield the biasing means from exhaust gas. It is good to arrange.

[0010]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an exhaust silencer according to an embodiment of the present invention, wherein an exhaust gas of an internal combustion engine (not shown) is a catalytic converter 1 for purifying exhaust gas,
It is configured to be discharged to the atmosphere via a sub muffler 2 and a main muffler 3 for reducing exhaust noise. Specifically, the catalytic converter 1 is connected to an internal combustion engine (not shown) via an exhaust pipe 4 and connected to the sub-muffler 2 via an exhaust pipe 5. The sub-muffler 2 is connected to the main muffler 3 via exhaust pipes 6 and 7, and the discharge side of the main muffler 3 is connected to the exhaust pipe 8. In the present embodiment, a valve device 9 that changes the flow area of the exhaust gas is disposed between the sub-muffler 2 and the catalytic converter 1 (and the exhaust pipe 5). Hereinafter, these catalytic converters 1,
The sub-muffler 2, the main muffler 3, and the valve device 9 will be sequentially described.

First, the catalytic converter 1 removes harmful components in exhaust gas by oxidation and reduction reactions, and detailed description is omitted, but various structures are mounted on the vehicle. Internal combustion engine (not shown) to catalytic converter 1
Is heated by the reaction heat in the catalytic converter 1 to a high temperature, and the energy of the exhaust gas increases.

The sub-muffler 2 has one open end (see FIG. 2) of a cylindrical outer cylinder 10 as shown in an enlarged sectional view in FIG.
On the right side of the figure, an open end of the outlet pipe 13 is fixed coaxially with the axis of the outer cylinder 10. A plurality of small holes (represented by 14) are formed in the side surface of the outlet pipe 13 in the axial direction. A stainless steel wool 16 is wound around the outer circumference of the outlet pipe 13, and a glass wool 15 is interposed between the stainless steel wool 16 and the outer tube 10. The separator 1 is located between the outlet pipe 13 and the outer cylinder 10.
2 is fixed.

Next, the cross section of the main muffler 3 is shown in FIG.
As shown in enlarged form in FIG. 1, separators 35 and 36 are fixed in a cylindrical outer cylinder 31 and outer plates 37 and 38 are fixed to both ends.
Three expansion chambers are formed in one. Separator 3
A plurality of small holes (not shown) are formed in the respective 5, 36, and the respective expansion chambers communicate with each other through these small holes.
Then, the outer plate 37 and the separators 35, 36
Through the inlet pipe 32 in parallel with the axis of the outer cylinder 31.
Is fixed. The outlet pipe 34 is supported from the outer plate 38 side through the separators 36 and 35 in parallel with the axis of the outer cylinder 31. Further, a U-shaped pipe 33 is accommodated in an expansion chamber between the separator 35 and the outer plate 37, and both ends of the U-shaped pipe 33 are
It is fixed to the separator 35 so as to open to the expansion chamber between the six.

The valve device 9 is configured as shown in FIGS. 4 and 5. FIG. 4 shows a cross section parallel to the axis of the exhaust pipe 5, and FIG. 5 is a cross section taken along line AA in FIG. 2 shows a cross section perpendicular to the axis of the exhaust pipe 5. 4, the exhaust pipe 5 is divided into two parts, and one end of one exhaust pipe 5a is enlarged to form a valve housing 18, and one end of the other exhaust pipe 5b is formed in the valve housing 18. Are connected so as to open. A bulging portion 18a is formed at an upper portion of the valve housing 18 and extends in a direction perpendicular to the axis of the exhaust pipe 5.

A valve member 19 is provided so as to cover a part of the opening of the exhaust pipe 5b. This valve member 19
Has a semi-circular shape, and has a projection 19a projecting into the exhaust pipe 5b on the exhaust gas introduction side. The valve member 19 is
The valve housing 1 extends above the opening of the exhaust pipe 5b.
8 has an extension 19b housed in the bulge 18a,
The rotating shaft 20 is fixed to the extension 19b. The rotating shaft 20 is supported by the bulging portion 18 a of the valve housing 18 so as to be rotatable perpendicularly to the axis of the exhaust pipe 5.
8a extends out of the valve housing 18. FIG.
As shown in FIG. 2, a stopper 21 is fixed to the extending end of the rotating shaft 20, and one end is fixed to the stopper 21.
A coil spring 22 having the other end fixed to the valve housing 18 is mounted. This coil spring 22
By the urging force, the valve member 19 is urged in a direction in which it contacts the opening end of the exhaust pipe 5b, and is maintained in the state shown in FIGS. 4 and 5 while the flow rate of the exhaust gas is small.

According to the exhaust silencer having the above structure, the exhaust gas discharged from the internal combustion engine (not shown) is introduced into the catalytic converter 1 through the exhaust pipe 4, and is oxidized and reduced. The exhaust gas is purified by the reaction. This exhaust gas flows into the sub-muffler 2 via the exhaust pipe 5. In this case, when the flow rate of the exhaust gas is small, the valve member 19 causes the exhaust pipe 5
Since the exhaust gas is maintained in contact with the opening end of the exhaust pipe 5b, the exhaust gas is introduced into the expansion chamber 10a of the sub-muffler 2 through a portion of the exhaust pipe 5b that is not shielded by the valve member 19. At this time, the ratio (S1 / S2) between the cross-sectional area (S1) of the expansion chamber 10a and the flow path area (S2) of the exhaust gas, that is, the expansion ratio is determined by the fact that the flow path area is limited by the valve member 19. Since it is larger than the one without the valve member 19, the silencing effect is increased accordingly. In addition, since the exhaust noise heated by the reaction heat of the oxidation and reduction reactions in the catalytic converter 1 and increased in energy can be immediately silenced, a good silencing effect can be obtained.

When the flow rate of the exhaust gas increases, the valve member 19 is driven in the opening direction against the urging force of the coil spring 22, and the opening area of the exhaust pipe 5b increases. Therefore, the back pressure does not increase excessively, and the power performance does not decrease at a high exhaust gas flow rate. Then, the exhaust gas discharged from the sub-muffler 2 is introduced into the main muffler 3 through the exhaust pipes 6 and 7, where the exhaust gas is further silenced and discharged from the exhaust pipe 8. Note that the silencing effect in the main muffler 3 is the same as that of the conventional muffler, and a description thereof will be omitted.

In general, the noise of the internal combustion engine is amplified when passing through the exhaust pipe and becomes a large exhaust noise. However, in the present embodiment, as described above, the noise of the internal combustion engine is sufficiently suppressed in the upstream sub-muffler 2. Therefore, when the vehicle reaches the main muffler 3, the noise has not grown so large. Therefore, there is a margin in the sound volume of the main muffler 3, so that the capacity of the main muffler 3 can be reduced, and the weight can be reduced.
The size can be reduced. Exhaust gas blown down from an exhaust valve (not shown) of the internal combustion engine grows into a shock wave with a sharp rise in the process of propagating as pressure pulsation in the exhaust pipe, and this shock wave causes the inner wall of the tube wall and the muffler outer cylinder to form an inner surface. In this embodiment, the energy of exhaust pulsation in the upstream sub-muffler 2 is greatly attenuated, and the shock wave grows. Therefore, there is also an effect that occurrence of the abnormal noise can be prevented.

In order to confirm the exhaust noise reduction effect of the exhaust silencer, in FIG. 1, when the valve device 9 is arranged at the position a of the exhaust pipe 5 as in this embodiment, the exhaust
Exhaust noise was measured when it was arranged at the position and when it was arranged at the position c of the exhaust pipe 7. FIG. 6 shows the measurement results at the time of acceleration and deceleration. In each case, the exhaust noise according to the change of the primary frequency of the engine explosion is indicated by a thick solid line by connecting the valve device 9 to the exhaust pipe 5. The minimum value is obtained at the position a.

FIGS. 7 and 8 show an exhaust silencer according to another embodiment of the present invention. The valve device is housed in a sub-muffler 2. FIG. In this embodiment, an inlet pipe 17 is fixed to the exhaust gas introduction side of the sub-muffler 2 shown in FIG. 2, and a valve member 19 is disposed in the sub-muffler 2 so as to close a part of the opening of the inlet pipe 17. ing. This valve member 19 is the same as the valve member 19 shown in FIGS.
The valve housing 18 is fixed to the separator 11, and the separator 11 is fixed to the outer cylinder 10. As a result, as shown in FIG. 7, a closed space 10b is formed in the outer cylinder 10 and the coil spring 22 is housed in the closed space 10b, so that the coil spring 22 is protected from flying stones and mud. In addition, since the coil spring 22 is not directly exposed to the exhaust gas, thermal deterioration can be prevented.

Furthermore, by filling the closed space 10b with a heat insulating material such as glass wool or covering the inlet pipe 17 with a heat insulating material, the ambient temperature in the closed space 10b can be lowered, so that the effect of preventing heat deterioration is further improved. Can be done In any of the above-described embodiments, a separate drive unit is provided as a drive source of the valve device in addition to the exhaust gas flow rate, and opening and closing control is performed according to the intake air amount, the load of the internal combustion engine, the accelerator opening, and the like. It may be. In the above embodiment, only one sub-muffler is provided. However, one or more sub-mufflers may be provided downstream of the sub-muffler 2 (ie, the main muffler 3).
Also, various types of main mufflers 3 can be used, and for example, a valve or the like may be provided in the main muffler.

[0022]

The present invention has the following effects because it is configured as described above. That is, in the exhaust muffler of the present invention, as described in claim 1, an expansion chamber is provided in the sub-muffler, and a valve that varies a flow passage area of the exhaust gas between the expansion chamber and the catalytic converter is provided. Since the device is configured to be disposed, a noise reduction effect is immediately performed on exhaust noise heated and increased in the catalytic converter, and a good noise reduction effect can be obtained even at a low exhaust gas flow rate. Further, since the energy of the exhaust pulsation is greatly attenuated in the sub-muffler, the growth of the shock wave is suppressed, so that the generation of the radiation noise and the discharge noise can be prevented.

If the valve device is configured as described in claim 2, an inexpensive device can be provided without requiring expensive driving means or control means such as an actuator.

Further, if the valve device is constructed as described in claim 3, foreign matter such as mud does not adhere to the urging means, and it is not exposed to exhaust gas. , Good durability can be ensured.

[Brief description of the drawings]

FIG. 1 is a plan view showing the overall configuration of an exhaust silencer according to one embodiment of the present invention.

FIG. 2 is a sectional view of a sub-muffler according to an embodiment of the present invention.

FIG. 3 is a sectional view of a main muffler according to an embodiment of the present invention.

FIG. 4 is a sectional view of a valve device according to an embodiment of the present invention.

5 is a cross-sectional view of the valve device according to the embodiment of the present invention, which is a cross-sectional view taken along line AA of FIG.

FIG. 6 is a graph showing the results of an experiment performed to confirm the exhaust noise reduction effect of the exhaust silencer according to one embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a sub-muffler accommodating a valve device in an exhaust silencer according to another embodiment of the present invention.

8 is a cross-sectional view showing a sub-muffler according to another embodiment of the present invention, and is a cross-sectional view taken along the line BB of FIG.

[Explanation of symbols]

1 catalytic converter, 2 sub muffler, 3 main muffler, 4-8 exhaust pipe, 9 valve device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) F01N 7/08 F01N 7/08 B (72) Inventor Masayuki Yokoi Hachiwada Miyoshi-cho, Miyoshi-cho, Nishikamo-gun, Aichi Prefecture No. 5 35 Yamatohachiwadayama Plant (72) Inventor Toshiyuki Imagawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tadashi Kondo 1 Toyota Town Toyota City, Aichi Prefecture Toyota F-term (reference) in Automobile Co., Ltd. 3G004 AA01 BA01 BA03 BA06 CA07 CA11 CA13 DA24 DA25 EA02 EA03 FA04 GA01 3G091 AA02 AB03 CB00 DA05 EA03 EA05 EA07 HB01

Claims (3)

[Claims] 1. A catalytic converter for purifying exhaust gas,
In an exhaust silencer in which a sub-muffler is disposed between a main muffler for reducing exhaust noise, an expansion chamber is provided in the sub-muffler, and a flow passage area of exhaust gas is variable between the expansion chamber and the catalytic converter. An exhaust silencer characterized by including a valve device. 2. The valve device according to claim 1, further comprising: a valve member configured to change a flow area of the exhaust gas; and a biasing unit configured to bias the valve member in a direction in which the flow area of the exhaust gas is minimized. 2. The valve member according to claim 1, wherein the valve member is driven in a direction in which a flow path area of the exhaust gas increases against an urging force of the urging means in accordance with an increase in a flow rate of the exhaust gas. Exhaust silencer. 3. The apparatus according to claim 2, wherein the valve member is disposed upstream of the expansion chamber in the sub-muffler, and the urging means is disposed in the sub-muffler so as to shield the urging means from exhaust gas. Item 2. An exhaust silencer according to Item 2.