JP2000120435A - Catalyst-built-in muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a heat insulating effect by arranging an inner cylinder on the outer wall inside of a catalyst outlet side cell, and filling a heat insulating material between the inner cylinder and an outer wall in a catalyst-built-in muffler for dividing the inside of a muffler main body for installing a catalyst inside into plural cells and arranging the heat insulating material on the outer wall inside. SOLUTION: The diametrically expanding part 11 having a gradually expanding diameter is arranged in the rear end part of an exhaust pipe 1, and a cylindrical muffler main body 2 composed by welding/joining a semicircular cylinder body divided, for example, on the left and right is installed on the outside of this end part. In the muffler main body 2, the inside is divided into first to third expansion chambers 5 to 7 by parallel two first/second partition walls 3, 4 so that the diametrically expanding part 11 of the exhaust pipe 1 is opened in the first expansion chamber 5. An inner pipe 12 having a smaller diameter than the diametrically expanding part 11 is arranged in a concentric shape on the inside of the diametrically expanding part 11, and an exhaust emission control catalyst is applied to the whole surface of the inner pipe 12 and the inside surface of the diametrically expanding part 11. An inner cylinder 20 is arranged inside the muffler main body 2 constituting an outer wall of the first expansion chamber 5, and glass wool (a heat insulating material) 15 is filled in the space part between the inner cylinder 20 and an outer wall.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a muffler (muffler) mounted on an exhaust pipe of an internal combustion engine. More specifically, the present invention relates to a muffler equipped with an exhaust gas purifying catalyst.

[0002]

2. Description of the Related Art A muffler for reducing exhaust noise is mounted on an exhaust pipe of an internal combustion engine. FIG. 6 is a sectional view of a conventional muffler. An exhaust pipe 51 connected to an engine (not shown) has an enlarged diameter portion 61 whose rear end gradually increases in diameter. A cylindrical muffler main body 52 formed by welding and joining, for example, a half-cylindrical body divided into left and right parts is attached to the outside of the end of the exhaust pipe 51. This muffler body 5
2 is a first expansion chamber 55 on the rear end side and a second expansion chamber 5 on the front end side by two parallel first and second partition walls 53 and 54.
6 and a third expansion chamber 57 at the center. To communicate the first and second expansion chambers 55 and 56, a first communication pipe 58 is provided through the first and second partition walls 53 and 54, and the second and third expansion chambers 56 and 57 are provided.
A second communication pipe 59 is provided to penetrate the first partition wall 53 so as to communicate with each other. The third expansion chamber 57 has a tail pipe 60.
To communicate with the outside.

In such a configuration, the exhaust gas exhausted from the enlarged diameter portion 61 at the rear end of the exhaust pipe 51, in the muffler main body 52, has a first expansion chamber 55 → a first communication pipe 58 → a second expansion chamber. It flows in the order of 56 → second communication pipe 59 → third expansion chamber 57 → tail pipe 60 and is discharged to the outside. In such an exhaust passage, the exhaust gas rapidly expands in the first, second, and third expansion chambers 55, 56, 57 and suddenly expands in the first and second communication pipes 58, 59 and the tail pipe 60. By repeating the contraction alternately, the sound is released to the outside due to the silencing effect.

In such a muffler structure, optimal values for the volume of each expansion chamber and the diameter and length of the communication pipe are selected according to the frequency to be silenced, and the vibration of the sound to be silenced can be efficiently reduced. Decay.

The enlarged diameter portion 61 at the rear end of the exhaust pipe 51 described above.
Is open to the first expansion chamber 55. An inner tube 62 having the same shape and a smaller diameter than the enlarged diameter portion 61 is provided inside the enlarged diameter portion 61. A catalyst having an exhaust gas purifying action is applied to the outer and inner surfaces of the inner tube 62 and the inner surface of the exhaust pipe enlarged portion 61. By providing the inner pipe 62, the contact area between the exhaust gas and the catalyst supporting portion increases, so that a sufficient exhaust gas purifying action can be obtained.

[0006] A punch hole 63 is formed in the exhaust pipe 51 and the first connecting pipe 58 at the root of the enlarged diameter portion 61, and the periphery thereof is covered with a glass wool 65 whose outside is sealed with a non-perforated plate 64. By providing such a glass wool 65, a part of the exhaust gas passes through the inside of the glass wool 65 via the punched holes 63, so that the noise reduction effect is enhanced. The glass wool 65 is also adhered to the inner surface of the first expansion chamber 55 of the muffler main body 52, and is further adhered to the inner surface of the end via a punching metal 66 having a punch hole. At this time, the punching metal 66 is
2 Partially spot welded inside and fixed. Thereby, a part of the exhaust gas passes through the glass wool 65 through the holes of the perforated metal 66, and the noise reduction effect is enhanced. Further, the glass wool 65 on the inner side of the muffler main body 52 is provided.
Has a heat insulating effect as well as a noise suppressing effect, and prevents the outer surface of the muffler main body 52 from being heated.

FIG. 7 is a sectional view taken along line DD of FIG.
8 is a sectional view taken along line EE in FIG. 6, and FIG.
FIG. 2 is a cross-sectional view taken along line FF of FIG. As can be seen from the cross-sectional views, the muffler main body 52 is divided into left and right half cylinders 5.
2a and 52b are welded up and down, and a glass wool 65 is applied to the inner surface of the inner surface before welding. A support frame 67 (see FIG. 8) is provided at an intermediate portion of the first expansion chamber 55, and supports the enlarged diameter portion 61 at the end of the exhaust pipe and the tail pipe 60. The support frame 67 has an opening 68 in the frame and does not obstruct the flow of the exhaust gas in the first expansion chamber 55. Further, in order to increase the strength of the support frame 67, the reinforcing portion 69 is formed by partially bending the support frame 67 itself. The support frame 67 is welded to the inner surface of the muffler main body 52.

The tail pipe 60 has its front end supported by the second partition wall 54 and faces the third expansion chamber 57. The tail pipe 60 is drawn out of the third expansion chamber 57, passes through the first expansion chamber 55, and passes through the rear end. Are exposed from the muffler main body 52 to the outside. In such a muffler with a built-in catalyst, the temperature of the exhaust gas is usually about 600 ° C., but the temperature of the exhaust gas rises to about 900 ° C. by the exothermic reaction when passing through the catalyst. Therefore, it is necessary to sufficiently insulate the first expansion chamber 55 into which the exhaust gas after passing through the catalyst is first introduced.

[0009]

However, in the muffler having the conventional structure, the muffler main body 52 is formed by welding and joining half-cylindrical bodies 52a and 52b which are divided into right and left. 7, the gap G of the glass wool was formed in the upper and lower welding fixed portions as shown in FIG. In addition, when the punching metal 66 is spot-welded to the end of the first expansion chamber 55, the glass wool 65 cannot be stuck to the spot-welded portion, as shown in FIGS. 6 and 9.
There was a gap of glass wool in the weld fixed part. Also, as shown in FIGS. 6 and 8, glass wool cannot be attached to the welded portion of the support frame 67 provided in the middle of the first expansion chamber. In this way, cuts and gaps in glass wool occur,
When the non-sticking portion of the glass wool occurs, the high temperature exhaust gas directly contacts the non-sticking portion of the glass wool through the catalyst, and the outer wall of the muffler main body in this portion becomes hot red, causing deterioration of the coating and the like. Further, heat conduction at a spot welding portion of the support frame 67 and the punching metal 66 to the muffler main body causes the high-temperature support frame 67 and the punching metal
Since the heat is transmitted from 6 to the muffler main body surface, the muffler main body surface temperature further increases.

The present invention has been made in consideration of the above-mentioned prior art, and can be filled with a heat insulating material such as glass wool without gaps so that heat in the muffler main body, which has become high temperature through the catalyst, is not directly transmitted to the wall of the muffler main body. An object of the present invention is to provide a muffler with a built-in catalyst having a heat insulating structure and a high heat insulating effect.

[0011]

In order to achieve the above object, according to the present invention, a catalyst is mounted inside a cylindrical muffler body forming an outer wall of a muffler, and the inside of the muffler body is divided into a plurality of compartments. In the muffler with a built-in catalyst provided with a heat insulating material inside the outer wall, an inner tube is provided inside the outer wall of the compartment on the catalyst outlet side, and a heat insulating material is filled between the inner tube and the outer wall. Provide a built-in muffler.

According to this structure, since the inner wall is provided inside the muffler main body and the outer wall portion has a double-pipe structure, when assembling, a heat insulating material is wound around the outer side of the inner cylinder without any gaps from the outside thereof. The muffler main body of two semi-cylindrical bodies can be put on and attached, and it is not necessary to abut the left and right half-cylindrical bodies with the heat insulating material attached to the inner surface of the semi-cylindrical body as in the related art.
Therefore, the gap of the heat insulating material which has conventionally occurred along the abutting surface of the semi-cylindrical body does not occur in the heat insulating material outside the inner cylinder of the present invention, and the inner surface of the outer wall of the muffler body is covered with the heat insulating material without any gap. Therefore, the exhaust gas heated to a high temperature through the catalyst does not directly touch the outer wall of the muffler main body, thereby preventing the muffler main body from being heated.

In a preferred configuration, the inner surface of the outer wall of the compartment on the catalyst outlet side is covered with the inner cylinder and / or heat insulating material without being exposed. According to this configuration, since the inner surface of the outer wall of the muffler main body is covered with the heat insulating material or is covered with the inner cylinder, for example, a gap is formed at the abutting portion of the heat insulating material at the cylindrical portion of the inner cylinder and the heat insulating material at the end face portion of the inner cylinder. Even when the heat generation occurs, the high-temperature exhaust gas does not directly touch the outer wall of the muffler main body because the gap is covered by the inner cylinder through the thickness of the heat insulating material.

[0014]

FIG. 1 is a sectional view of a muffler according to an embodiment of the present invention. 2 is a sectional view taken along line AA of FIG. 1, FIG. 3 is a sectional view taken along line BB of FIG. 1, and FIG. 4 is a sectional view taken along line CC of FIG. is there.

The exhaust pipe 1 connected to an engine (not shown) has an enlarged diameter portion 11 whose rear end gradually increases in diameter. A cylindrical muffler main body 2 formed by welding and joining, for example, a half-cylindrical body divided into left and right sides is attached to the outside of the end of the exhaust pipe 1. The muffler body 2 is composed of two parallel first and second partition walls 3 and 4, a first expansion chamber 5 on the rear end side, a second expansion chamber 6 on the front end side, and a third expansion chamber 7 in the center.
Is divided into three expansion chambers. First and second partition walls 3 and 4 for communicating the first and second expansion chambers 5 and 6
A first communication pipe 8 is provided to penetrate the first partition wall 3 to provide communication between the second and third expansion chambers 6 and 7. The third expansion chamber 7 communicates with the outside through a tail pipe 10.

In such a configuration, the exhaust gas discharged from the enlarged diameter portion 11 at the rear end of the exhaust pipe 1 is supplied from the first expansion chamber 5 to the first communication pipe 8 to the second expansion chamber 6 in the muffler main body 2. → 2nd
It flows in the order of the communication pipe 9 → the third expansion chamber 7 → the tail pipe 10 and is discharged to the outside. In such an exhaust passage, the exhaust gas rapidly expands in the first, second, and third expansion chambers 5, 6, 7, and suddenly expands in the first and second communication pipes 8, 9, and the tail pipe 10. By repeating the contraction alternately, the sound is released to the outside due to the silencing effect.

In such a muffler structure, optimal values are selected for the volume of each expansion chamber and the diameter and length of the communication pipe in accordance with the frequency to be silenced, and the vibration of the sound to be silenced can be efficiently reduced. Decay.

The enlarged diameter portion 11 of the exhaust pipe 1 is open to the first expansion chamber 5. An inner tube 12 having the same shape and a smaller diameter than the enlarged diameter portion 11 is provided inside the enlarged diameter portion 11. The outer surface and inner surface of the inner pipe 12 and the exhaust pipe enlarged portion 1
A catalyst having an exhaust gas purifying function is applied to the inner surface of the first member. By providing the inner pipe 12, the contact area between the exhaust gas and the catalyst-carrying portion increases, so that a sufficient exhaust gas purifying action can be obtained.

The exhaust pipe 1 and the first
A punch hole 13 is formed in the connection pipe 8, and the periphery thereof is covered with a glass wool 15 whose outside is sealed by a non-perforated plate 14. By providing such a glass wool 15,
A part of the exhaust gas passes through the glass wool 1 through the punch holes 13.
5 and the noise reduction effect is enhanced.

In the present embodiment, the inner cylinder 20 is provided inside the muffler main body 2 constituting the outer wall of the first expansion chamber 5 into which the exhaust gas after passing through the catalyst is first introduced. Structure. The inner cylinder 20 is formed by fitting and welding a cylindrical portion 20a formed of punched metal and a dome portion 20b formed of a non-perforated plate covering an end surface portion thereof.

Since the glass wool 15 is wound around the outside of the cylindrical portion 20a without any gap as shown in FIGS. 2 and 4, the high temperature exhaust gas does not directly touch the muffler main body. Can prevent the outer wall from being heated. Further, the cylindrical portion 20a and the dome portion 20b are fitted to each other, and even if the gap 23 of the glass wool
Through the thickness of the first expansion chamber 5, the dome portion 20 of the non-perforated plate
The hot gas does not directly touch this outer wall because it is covered with b.

A support frame 17 (see FIG. 3) is provided at an intermediate portion of the first expansion chamber 5 having a large volume.
1 and the tail pipe 10 are supported. This support frame 17
Has an opening 18 in the frame and does not hinder the flow of exhaust gas in the first expansion chamber 5. Further, in order to increase the strength of the support frame 17, the reinforcing portion 19 is formed by partially bending the support frame 17 itself. Since the support frame 17 is also welded to the inner surface of the inner cylinder 20, there is no gap between the glass wool 15 in the welded portion unlike the related art. Further, no heat is transmitted to the outer wall of the muffler main body 2 by heat conduction through the support frame.

In this case, the glass wool 15 is firmly wound around the outer surface of the inner cylinder 20 over several layers, so that the glass wool is densely and firmly compressed, the rigidity is increased, and the support frame 17 can be supported sufficiently reliably. Since the exhaust pipe 1 can be sufficiently firmly supported by the entrance of the muffler main body 2 and the first and second partition walls 3 and 4 including the enlarged diameter portion 11 at the rear end, the support frame at the intermediate portion of the enlarged diameter portion 11 is supported. 17 may be omitted.

FIG. 5 is a sectional view of the tail pipe end. The tail pipe 10 is exposed from the rear end of the muffler main body 2 to the outside. At this time, as shown, the tail pipe 1
The gap between the glass wool 15 around the tail pipe 10 is welded to the tail pipe 10 by welding the dome 20b of the inner cylinder of the non-perforated plate to the dome 20b of the inner cylinder 20. Therefore, the hot gas in the first expansion chamber 5 does not directly touch the outer wall of the muffler main body 2.

[0025]

As described above, in the present invention, since the inner wall is provided inside the muffler main body and the outer wall portion has a double-pipe structure, a heat insulating material is wound around the outer side of the inner cylinder without gaps when assembling. The muffler main body of two semi-cylindrical bodies can be put on from the outside in a state where it is placed, and there is no need to butt the left and right half-cylindrical bodies with the heat insulating material attached to the inner surface of the semi-cylindrical body as in the conventional case . Therefore, the gap of the heat insulating material which has conventionally occurred along the abutting surface of the semi-cylindrical body does not occur in the heat insulating material outside the inner cylinder of the present invention, and the inner surface of the outer wall of the muffler body is covered with the heat insulating material without any gap. Therefore, the exhaust gas heated to a high temperature through the catalyst does not directly touch the outer wall of the muffler main body, and thus the heating of the muffler main body can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a muffler according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

FIG. 4 is a sectional view taken along the line CC of FIG. 1;

FIG. 5 is a sectional view of an end of a tail pipe.

FIG. 6 is a sectional view of a conventional muffler.

FIG. 7 is a sectional view taken along the line DD of FIG. 6;

FIG. 8 is a sectional view taken along the line EE in FIG. 6;

FIG. 9 is a sectional view taken along the line FF of FIG. 6;

[Explanation of symbols]

1: exhaust pipe, 2: muffler body, 3: first partition, 4: second
Partition wall, 5: first expansion chamber, 6: second expansion chamber, 7: third expansion chamber, 8: first connection pipe, 9: second connection pipe, 10: tail pipe, 11: enlarged diameter portion, 12: Inner tube, 13: punch hole, 1
4: non-perforated plate, 15: glass wool, 17: support frame, 1
8: Opening, 19: Reinforcement, 20: Inner cylinder, 20a: Cylindrical, 20b: Dome, 23: Gap.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01N 7/08 F01N 7/08 A (72) Inventor Toshinori Inomori 2500 Shinkai, Iwata-shi, Shizuoka Yamaha Motor F term in reference (reference) 3G004 CA04 CA06 CA13 DA04 DA08 DA09 EA05 FA01 FA07 GA06 3G091 AA02 HA05

Claims (2)

[Claims] A muffler with a built-in catalyst, wherein a catalyst is mounted inside a cylindrical muffler main body forming an outer wall of the muffler, the inside of the muffler main body is divided into a plurality of compartments, and a heat insulating material is provided inside the outer wall. A muffler with a built-in catalyst, wherein an inner cylinder is provided inside the outer wall of the compartment on the catalyst outlet side, and a heat insulating material is filled between the inner cylinder and the outer wall. 2. The muffler with a built-in catalyst according to claim 1, wherein an inner surface of an outer wall of the compartment on the catalyst outlet side is covered without being exposed by the inner cylinder and / or a heat insulating material.