JPS60175720A - Muffler for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a muffler having a sufficient strength and a high sound absorbing effect, by forming the front half of the muffler which constitutes the outer box of the muffler into an integrally formed cylinder, and as well by forming the rear half of the muffler with a plurality of axially sectioned members which is made of molded sound absorbing materials and which are jointed together. CONSTITUTION:An outer box 12 attached to the outside of an exhaust pipe 11 is composed of front and rear halves 12a, 12b with both axes of the latter crossing together at a certain angle. The front half 12a is integrally formed from a steel plate in a cylindrical shape, the diameter of the half 12a being gradually increased from its front end to its rear end. Meanwhile the rear half 12b is axially divided into two sections 12b-1, 12b-2 which are made of molded sound absorbing materials and which are jointed together. Upon assembly of the muffler the front half 12a is welded to the exhaust pipe 11, and thereafter, the rear half 12b is jointed to the rear end of the front half 12a and to the rear end of a tail pipe 13 with the use of a bonding agent 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a muffler forming a part of an exhaust system for an internal combustion engine.

A muffler is attached to the exhaust system of an internal combustion engine to reduce exhaust noise. For example, as a silencer for a motorcycle, a silencer having a structure as shown in FIG. 1 or 2 is generally used. The silencer shown in Fig. 1 has a cylindrical outer box (2) made of integrally molded steel plate arranged on the outside of an exhaust pipe (1), and the front part of the outer box (2) is tapered ( 2
a) Weld the tip to the exhaust pipe (1) and attach it to the outer box (
2), weld the partition plate (3) provided near the boundary between the front half (2a) and the rear half (2b) and the exhaust pipe (1), and attach it to the rear end opening of the exhaust pipe (1). The tip of the tail pipe (4) is welded, and the rear end of the tail pipe (4) is attached to the end plate (5) attached to the outer box (2).
), and a large number of small holes (6) are formed in the tail pipe (0), which has a structure that exhibits a sound absorption effect by interposing glass wool (8) held in a cylindrical case (7) around the outer circumference of the middle part. On the other hand, the silencer shown in Figure 2 is
The front half (2) of the outer box (2), which is also integrally formed from a steel plate.
a) Attach the tip to the rear end of the exhaust pipe (1) and install a bunching plate (2a) inside the front half (2a).
A sound-absorbing glass wool (8) held by a sound-absorbing glass wool (8) is provided, and inside the rear part (2b), a plurality of expansion chambers are divided by partition plates (3) (3), and these expansion spaces are connected by a communicating pipe ( 10
) and (10), and the final expansion chamber and the outside are communicated through a tail pipe (4).

In this way, in the past, glass wool was interposed inside the silencer in order to increase the sound absorption effect of the silencer, but in order to hold the glass wool, a punching plate (8) was used to hold the glass wool.
The problem is that the structure becomes complicated, such as attaching the tail pipe separately, or forming a small hole in the tail pipe (0, etc.) and providing a case (7) on the outside of the hole, which also makes manufacturing troublesome.

On the other hand, since the front half of a silencer is strongly influenced by vibration and heat due to its structure, the front half is required to have a corresponding strength.

Therefore, there is a demand for a silencer having a structure in which the front half has sufficient strength and can enhance the sound absorption effect without interposing glass wool or the like inside as in the conventional case.

The present invention was created in view of such conventional demands,
The purpose is to provide a muffler for an internal combustion engine that can obtain a high sound absorbing effect while maintaining sufficient strength required for a muffler, and can achieve a simple structure and a reduction in weight.

In order to achieve the above object, a silencer for an internal combustion engine according to the present invention has an outer box composed of two members, a front part and a rear part, in which the front part is an integrally molded cylinder having excellent strength, and the latter part is an integrally molded cylinder. Its feature is that it is composed of divided bodies made of molded sound absorbing material divided along the axial direction.

Below, a first embodiment of the present invention will be explained based on FIGS. 3 and 4, and a second embodiment will be explained based on FIGS. 5 and 6.

First, to explain the first embodiment, the outer box (12) provided on the outside of the exhaust pipe (11) has a front half (
It consists of the front half (12a) and the second half (12b), and the first half (12b).
The axis of 2a) and the axis of the second half body (12b) intersect at an angle, forming a curved shape as a whole.

The front half (12a) has a cylindrical shape formed by integrally molding a steel plate, and the diameter gradually increases from the tip to the rear half. The second half body (12b) is divided into two parts (12b-1) (12b-1) along the axial direction as shown in FIG.
2), and these divided bodies (12b-1), (
12b-2) is made of molded sound absorbing material. Specifically, long glass fibers, ceramic fibers, and other inorganic fibers or organic long fibers are cut into appropriate lengths, mixed to form a layer, and then subjected to roller pressure and needling to form a mat. By coating or impregnating a binder such as water glass, placing it in a mold of a predetermined shape and firing it, a porous layer with a low density inside and excellent sound absorption properties (112
), divided bodies (12b-1) and (12b-2) are formed in which the outer portion in contact with the high-temperature mold surface is a hard layer (tight layer) (112) with high density and excellent sound insulation properties.

On the other hand, the method of fixing the exhaust pipe (11) and the outer box (12) is as follows.

That is, the tail pipe (13) is welded to the rear end of the exhaust pipe (11).
) is inserted into the front half body (12a) of the outer box (12), and the tip of the front half body (12a) and the exhaust pipe (11) are welded together. Here, 4 on the outer circumference of the rear end of the front half body (12a)
Projections (10) are formed in advance at these locations, and a ring-shaped retaining plate (15) is welded to the front of the projection (14).

Once the front half (12a) of the outer box (12) is welded to the exhaust pipe (11), the divided body (12b-1),
(12b-2) from left and right, and use heat-resistant adhesive (
1B) through the split body (12b-1), (12b-
2) Join. At the same time, the second half of the body (12b
) Heat-resistant adhesive (1B) is applied to the inner surface of the insertion hole (17) of the tail pipe (13) formed at the rear end of the tail pipe (13) and the front end surface of the rear half body (12b), and then the split body (12b-1 ),
At the same time as joining (12b-2), these divided bodies (12b-2)
-1), (12b-2)
2b), the tail pipe (13) and the stop plate (15). Then, the exhaust pipe (11) and the outer box (
12).

In addition, in the second embodiment, the tip of the front half body (22a) integrally molded into a cylindrical shape of the outer box (22) is similarly tied to the rear end of the exhaust pipe (21). Rest (2
2a) is divided into two along the axial direction (22b-
1) The latter half (22b) consisting of (22b-2) is joined. In particular, in this embodiment, the front half (22
a) and the second half body (22b) both have a molded sound absorbing material as a constituent material, and this molded sound absorbing material has a porous layer (122a) on the inner side and a hard layer (tight layer) (12) on the outer side.
2b). Here, in order to increase the hardness of the hard layer (122b) and increase the thickness of the hard layer (122b),
For example, at the time of firing, the surface of the molded sound absorber is coated or impregnated with a thermosetting resin such as phenol resin, epoxy resin, polyester, etc. in advance.

Further, as a manufacturing method of the silencer according to the second embodiment, for example, elasticity is applied to the outer periphery of the rear end of the exhaust pipe (21) via a heat-resistant adhesive (20) on the outside of the porous heat insulating layer (23). A seal collar (26) formed by adhering a semi-hard layer (25) having the above-mentioned semi-hard layer (25) is covered with a seal collar (26) and fixed with a band (27),
The tip of the front half body (22a) is externally fitted onto this seal collar (26) via a heat-resistant adhesive (20) to integrate the exhaust pipe (21) and the front half body (22a).

On the other hand, the second half body (22b) has partition plates (28), (2
The communication pipes (30), (30) and tail pipe (31) are fixed to the left and right divided bodies (31) from the outside.
22b-1) (22b-2) and heat-resistant adhesive (
24) through these split bodies (22b-1), (
22b-2) are joined and integrated. In this case, the split field (2
2b-1) and (22b-2), the attachment hole (32) of the tail pipe (31) is coated with heat-resistant adhesive (24) in advance, unlike the first embodiment. The same is true.

After that, a punching plate (
33), butt them together, and apply heat-resistant adhesive (24).
) to obtain the desired silencer.

According to such a silencer, the exhaust pipes (11) and (2
The exhaust air from 1) expands and expands inside the outer boxes (12) and (22).
While being compressed, an effective sound damping effect is produced in the molded sound absorbing material that constitutes part or all of the outer boxes (12), (22).

As explained above, according to the present invention, the outer box of the silencer is composed of a front half body and a rear half body, and the front half body, which is strongly affected by vibration and heat, is integrally molded into a cylindrical shape, so it has excellent strength. In addition, since the rear half body is constructed from a divided body made of molded sound absorbing material, the structure can be simplified and the sound absorbing effect can be increased compared to the conventional structure in which the glass wool is held in a separate member such as a punching plate inside the muffler. . Furthermore, manufacturing the silencer becomes easier by dividing it into the front half body and the rear half body, and in particular, it is possible to manufacture a silencer with a curved shape where the axes of the front half body and the rear half body intersect at an angle, instead of conventional integral molding. It has many effects such as being much easier to use compared to

[Brief explanation of drawings]

Figures 1 and 2 are longitudinal sectional views showing the structure of a conventional silencer, Figure 3 is a longitudinal sectional view of the silencer according to the first embodiment, and Figure 4 is a sectional view taken along line ^-A in Figure 3. 5 is a vertical sectional view of a silencer according to the second embodiment, and FIG. 6 is a sectional view taken along the line B--B in FIG. 5. In addition, (11) and (21) in the drawing are exhaust pipes,
(12), (22) are outer boxes, (12a), (22
a) is the front half of the outer box, (12b), (22b) is the back half of the outer box, (12b-1), (12b-2), (
22b-1), (22b-2) are split fields, (112
a), (122a) are porous layers, (112b), (12
2b) is a hard layer. Patent applicant Honda Motor Co., Ltd. Agent Patent attorney 2 1) Part 1 Patent attorney Kunihiko Ohashi Patent attorney Yu Koyama

Claims (3)

[Claims] (1) In a silencer in which an outer box is constructed from a front half body and a rear half body, the first half body has an integrally molded cylindrical shape, and the second half body has a plurality of molded sound absorbers divided along the axial direction. A silencer for an internal combustion engine characterized by being formed by joining divided bodies made of wood. (2) An internal combustion engine according to claim 1, wherein the outer box is joined so that the axes of the front half body and the rear half body intersect at an angle, and has a bent shape as a whole. Silencer. (3) The muffler for an internal combustion engine according to claim 1 or 2, wherein the molded sound absorbing material has a porous layer on the inside and a hard layer on the outside.