JPH10141050A - Muffler with built-in catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler with a built-in catalyst to have a high muffling effect and reduce the generation of a back pressure by effectively utilizing a space. SOLUTION: A muffler with a built-in catalyst comprises a tubular muffler body provided at two ends with a pair of first and second end plates 12 and 13, a monolith catalyst 16 arranged in the muffler body and partitioning the interior of the muffler body into an inlet chamber 14a and an outlet chamber 14b, an inlet pipe 17 arranged in a state to extend through a first end plate 12 and having a plurality of first ventilation holes 17a formed in a part fronting on the inlet chamber 14a, an outlet pipe 18 arranged in a state to extend through a second end plate 13 and having a plurality of second ventilation holes 18a formed in a part fronting on the outlet chamber 14b, and a cone body 19 for dispersing exhaust gas having one end connected to the end part of an inlet pipe 17 fronting on the inlet chamber 14a and the other end adhered on the inner peripheral surface of the inlet camber 14a of the muffler body 14. A resonance sound absorbing camber 14c communicated with the first ventilation hole 17a is formed at the outside of the cone body 19 for dispersing exhaust gas of the inlet chamber 14a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for suppressing exhaust noise of an engine. More specifically, the present invention relates to a muffler in which a catalyst is provided.

[0002]

2. Description of the Related Art As shown in FIG. 2 (a), a conventional muffler 1 for suppressing the exhaust sound of an engine has a cylindrical muffler body having both ends sealed by a pair of first and second end plates 2 and 3. The inside of 4 is partitioned into first to third expansion chambers 4a, 4b, 4c by first and second partition plates 5, 6, and the end of an inlet pipe 7 is inserted from the first end plate 2 to the first expansion chamber 4a. , Outlet pipe 8
Is known in which the base end is inserted from the second end plate 3 to the third expansion chamber 4c. A large number of first small holes 7a are formed in a portion of the inlet pipe 7 located in the first expansion chamber 4a, and a large number of second small holes are formed in a portion of the outlet pipe 8 located in the third expansion chamber 4c. 8a are formed. The first partition plate 5 is formed with a first through hole 5a communicating the first and second expansion chambers 4a and 4b, and the second partition plate 6 is formed with the second and third expansion chambers 4a and 4b.
A second through hole 6a communicating between b and 4c is formed. In the muffler 1 configured as described above, the proximal end of the inlet pipe 7 is connected to an upstream exhaust pipe (not shown), and the distal end of the outlet pipe 8 is connected to a downstream exhaust pipe (not shown).

On the other hand, it has been known that a catalyst 9 is incorporated in the second expansion chamber 4b due to a recent demand for versatility of the muffler 1. The catalyst 9 is provided via a pair of brackets 9a, 9a as shown in FIG.
All the exhaust gas that has entered the second expansion chamber 4b from the through hole 5a passes through the catalyst 9, passes through the through hole 6a of the second partition plate 6, and enters the third expansion chamber 4c. Such a catalyst 9 is formed on a ceramic carrier such as porous alumina formed in a honeycomb shape or a metal carrier made of metal by Pt or Pd.
The catalyst is formed by carrying a noble metal such as SOF, and SOF (Soluble Organic Fraction) in exhaust gas is oxidized by this catalyst, purified into carbon dioxide and water, and discharged to the atmosphere.

In this muffler 1, when high-temperature and high-pressure exhaust gas discharged from the engine enters the first expansion chamber 4a from the first small hole 7a through the upstream exhaust pipe and the inlet pipe 7, the first expansion is performed. The pressure is reduced by expanding in the chamber 4a, and further, when the exhaust gas enters the second expansion chamber 4b from the first through hole 5a of the first partition plate 5, the pressure is also reduced and the sound is reduced. In the second expansion chamber 4b, the exhaust gas is purified by the catalyst 9,
The pressure is further reduced when entering the third expansion chamber 4c from the expansion chamber 4b through the through hole 6a of the second partition plate 6. Also, the heat of the exhaust gas is transmitted to the atmosphere through the muffler body 4 having a large area. As a result, the exhaust gas is purified, and the exhaust noise is muted.

[0005]

However, in the above-described muffler with a built-in catalyst, the flow of exhaust gas becomes complicated and the back pressure rises, and there still remains a problem to be solved. That is, as shown by the solid line arrow in the figure, the exhaust gas that has entered the first expansion chamber 4a from the first small hole 7a through the inlet pipe 7 from the upstream exhaust pipe flows through the first through hole 5a of the first partition plate 5. It is necessary to enter the second expansion chamber 4b and further pass through the catalyst 9 supported by the bracket 9a, and the back pressure increases due to the complexity of the flow of the exhaust gas. 9 has a problem that the exhaust gas does not pass evenly. Further, the unevenness of the catalyst 9 caused a tendency to further increase the back pressure.

In order to solve this problem, as shown in FIG. 2 (b), the first expansion chamber 4a is eliminated, and the inlet pipe 7 is gradually expanded toward the catalyst 9 so that the exhaust gas can be smoothly removed. It is conceivable that the muffler silencing effect is reduced due to the elimination of the first expansion chamber, and the temperature is radiated to the outside from the gently enlarged inlet pipe to lower the catalyst performance. There is a problem that a useless space is generated outside the device. The purpose of the present invention is
An object of the present invention is to provide a muffler with a built-in catalyst that has a high noise reduction effect and reduces the back pressure without generating unnecessary space.

[0007]

The invention according to claim 1 is
As shown in FIG. 1, a pair of first and second end plates 12 and 13 are provided.
Are provided at both ends, and a cylindrical muffler main body 14 is provided inside the muffler main body 14 and the inside of the muffler main body 14 is
and an inlet pipe 17 having a plurality of first air holes 17a formed in a portion facing the inlet chamber 14a and provided through the first head plate 12 and defining the outlet chamber 14a.
One end is connected to one end of an outlet pipe 18 provided through the second end plate 13 and having a plurality of second ventilation holes 18a formed at a portion facing the outlet chamber 14b and an inlet pipe 17 facing the inlet chamber 14a. And an exhaust gas diffusion cone 19 bonded at the other end to the inner peripheral surface of the inlet chamber 14a of the muffler main body 14, and communicates with the first vent hole 17a outside the exhaust gas diffusion cone 19 of the inlet chamber 14a. This is a muffler with a built-in catalyst in which a resonance sound absorbing chamber 14c is formed.

[0008] In the muffler with a built-in catalyst 11 according to the first aspect,
When the exhaust gas passes through the inlet pipe 17 and enters the inlet chamber 14a, the exhaust gas expands from the first ventilation hole 17a to the resonance sound absorbing chamber 14c, thereby being silenced. The silenced exhaust gas is guided from the inlet pipe 17 by the cone body 19 and reaches the catalyst 16 smoothly.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIG. 1, a muffler 11 for suppressing exhaust noise of an engine has a pair of first and second ends.
Cylindrical muffler body 14 sealed by end plates 12 and 13
The muffler body 14 has a monolithic catalyst 16
Is provided. The monolith catalyst 16 has a ceramic carrier,
An example is a metal carrier catalyst. Both ends of the monolith catalyst 16 are supported by a pair of brackets 16a, 16a, and the outer peripheral surfaces of the brackets 16a, 16a are
The catalyst 16 is fixed to the inner peripheral surface of the
Built in. The catalyst 16 in the present embodiment is an oxidation catalyst formed by dispersing and supporting Pt or Pd on a porous alumina carrier (not shown) formed in a honeycomb shape. In addition, the catalyst 16 partitions the inside of the muffler main body 14 into an inlet chamber 14a and an outlet chamber 14b by being attached in this manner.

The first end plate 12 is provided with a distal end of an inlet pipe 17 therethrough, and the second end plate 13 has a base end of an outlet pipe 18 inserted into an outlet chamber 14b. One end of an exhaust gas diffusion cone 19 is connected to an end of the inlet pipe 17 facing the inlet chamber 14a, and the other end of the cone 19 is connected to the muffler body 14.
Is bonded to the inner peripheral surface of the inlet chamber 14a. This cone 1
Numeral 9 is configured to gradually expand from the inlet pipe 17 toward the catalyst 16, and the other end is bonded to the inner peripheral surface of the inlet chamber 14 a to further partition the inlet chamber 14 a to resonate outside the cone body 19. The sound absorbing chamber 14c is formed. A plurality of first ventilation holes 17a are formed in a portion of the entrance pipe 17 facing the entrance chamber 14a, and the first ventilation holes 17a allow the interior of the entrance pipe 17 to communicate with the resonance sound absorbing chamber 14c.

The outlet chamber 14 b is partitioned by a partition plate 21, and an end of an outlet pipe 18 inserted through the second end plate 13 is fixed to the partition plate 21. Outlet chamber 14 of outlet pipe 18
A plurality of second ventilation holes 18a are formed in the outer peripheral portion facing b, and through holes 21a are formed in the partition plate 21. This muffler 11 has a base end of an inlet pipe 17 connected to an upstream exhaust pipe (not shown) connected to an exhaust manifold of the engine, and a downstream exhaust pipe (not shown) having a front end open to the atmosphere at a distal end of an outlet pipe 18. Is connected.

The operation of the muffler with a built-in catalyst constructed as described above will be described. In the muffler 11, high-temperature and high-pressure exhaust gas discharged from the engine expands from the first ventilation hole 17a to the resonance sound absorbing chamber 14c when entering the inlet chamber 14a through the upstream exhaust pipe and the inlet pipe 17. Will be muted. The muffled exhaust gas travels from the inlet pipe 17 to the cone body 19, and is guided by the cone body 19 and reaches the catalyst 16 smoothly as shown by the arrow in the figure. The exhaust gas that has reached the catalyst 16 passes through the inside of the catalyst 16 so that the SOF in the exhaust gas is oxidized by the catalyst,
It is purified into carbon dioxide and water. The exhaust gas that has passed through the catalyst 16 advances to the outlet chamber 14b and is further reduced in pressure when passing through the through hole 21a of the partition plate 21, and is discharged from the downstream exhaust pipe to the atmosphere via the outlet pipe 18. Also, the heat of the exhaust gas is transmitted to the atmosphere through the muffler body 14 having a large area.

[0013]

As described above, according to the present invention, the monolithic catalyst for partitioning the inside of the muffler main body into an inlet chamber and an outlet chamber, and a plurality of first vent holes are formed in a portion facing the inlet chamber. An inlet pipe and an exhaust gas diffusion cone having one end connected to the end of the inlet pipe facing the inlet chamber and the other end bonded to the inner peripheral surface of the inlet chamber of the muffler body, Since the resonance sound absorbing chamber communicating with the first ventilation hole is formed outside the body, the exhaust gas expands from the first ventilation hole into the resonance sound absorbing chamber when the exhaust gas enters the inlet chamber through the inlet pipe, so that the noise is reduced. The exhaust gas is guided by a cone from the inlet pipe and smoothly reaches the catalyst. As a result, the muffler with a built-in catalyst according to the present invention has a high sound deadening effect,
The back pressure can be reduced without producing useless space.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a muffler with a built-in catalyst of the present invention.

FIG. 2A is a diagram corresponding to FIG. 1 showing a conventional example. (B) The figure corresponding to FIG. 1 which shows the improved conventional example.

[Explanation of symbols]

 12 First End Plate 13 Second End Plate 14 Muffler Main Body 14a Inlet Chamber 14b Outlet Chamber 14c Resonant Sound Absorbing Chamber 16 Monolith Catalyst 17 Inlet Pipe 17a First Vent Hole 18 Outlet Pipe 18a Second Vent Hole 19 Exhaust Gas Diffusion Cone

Claims (1)

[Claims] 1. A muffler body (14) having a pair of first and second end plates (12, 13) disposed at both ends, and a muffler body (14) provided inside the muffler body (14). )
A monolithic catalyst (16) that divides the interior into an inlet chamber (14a) and an outlet chamber (14b); and the inlet chamber (14a) provided through the first end plate (12).
An inlet pipe (17) in which a plurality of first ventilation holes (17a) are formed at a portion facing the, and the outlet chamber (14b) provided through the second end plate (13).
An outlet pipe (18) in which a plurality of second ventilation holes (18a) are formed at a part facing the inlet, one end is connected to an end of the inlet pipe (17) facing the inlet chamber (14a), and the other end is connected to the other end. Entrance room (14a) of muffler body (14)
An exhaust gas diffusion cone (19) bonded to the inner peripheral surface of the exhaust gas diffusion cone (19) in the inlet chamber (14a), and communicating with the first ventilation hole (17a). A muffler with a built-in catalyst, wherein a resonance sound absorbing chamber (14c) is formed.