JPS60175716A - Silencer for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the silencing effect while providing sufficient strength of a silencer by forming an outer box of a silencer of an acoustic molding and covering the outer peripheral surface of the outer box with a ordinary net cloth. CONSTITUTION:An outer box 2 of a silencer 1 is constituted from left and right divided bodies made of an acoustic molding with excellent heat resisting, adiabatic and acoustic properties and bonded to each other by a heat resisting adhesives. The divided bodies are formed by impregnating mat-like fibers with binder, putting them into a mold having a forming surface for forming the divided body, pressurizing and baking them to provide a hard layer (tight layer) 2b and a perforated layer (porous layer) 2a. And the outer peripheral surface of the outer box 2 is covered with an ordinary net cloth 3 knitted with heat resisting fibers. Also, a holder 5 of an exhaust pipe 4 projects from a front end opening of the ordinary net cloth 3 and a tail pipe portion 6 projects from a rear end opening.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a muffler that constitutes a part of an exhaust system for a motorcycle or the like.

In the case of motorcycles, if the exhaust gas from the engine, which is an internal combustion engine, is directly discharged to the outside, it will generate a loud exhaust noise, so the exhaust gas is first guided into the expansion chamber of the silencer, where it is expanded. The exhaust noise is reduced by consuming the energy contained in the exhaust gas.

Here, since the outer box forming the expansion chamber of the muffler is generally made of a steel plate by press molding, etc., the heat of the exhaust gas is transmitted to the steel plate, and the surface of the outer box becomes high temperature. For this reason, the location of the silencer is limited to a location where the influence of heat on other members is small, making it impossible to make the silencer large-capacity. Furthermore, although the steel plate outer box has some degree of sound insulation, the steel plate itself has almost no sound absorption. Therefore, in the past, it has been difficult to obtain a muffler that exhibits a sufficient muffling effect.

Therefore, it is possible to form the outer box of the silencer using a molded sound absorbing material that has excellent heat insulation, heat resistance, and sound absorption properties, but when compared to steel plates, molded sound absorbing materials are slightly inferior in terms of rigidity. That is undeniable.

The present invention has been made in view of the above, and an object of the present invention is to provide a muffler for an internal combustion engine that can improve the sound absorption effect and has sufficient strength.

In order to achieve this object, the gist of the present invention is to form the outer box of the silencer from a molded sound-absorbing material, and to cover the outer peripheral surface of the outer box with a mesh cloth.

Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a silencer according to the present invention, and FIG.
It is an enlarged sectional view of the main part of the figure, showing the outer box (2) of the silencer (1).
The left and right parts are made of molded sound-absorbing material with excellent heat resistance, heat insulation, and sound absorption properties, and are joined using a heat-resistant adhesive.
An example of a method for forming this divided body will be described below.

First, inorganic fibers such as long glass fibers, ceramic fibers, or metal fibers, or organic long fibers such as polyester are cut into appropriate lengths and mixed, and this is subjected to roller pressure and needling to form mat-like fibers. After the matte fibers are impregnated with a binder such as water glass, the matte fibers are placed in a mold having a molding surface capable of forming a predetermined shape, that is, a divided body, and then baked under pressure. Then, a divided body is obtained in which the portion in contact with the hot molding surface is a hard layer (tight layer) (2b) and the other portion is a porous layer (2a). In order to increase the thickness and hardness of the hard layer (2b), for example, the surface of the matte fibers may be impregnated with a thermosetting resin such as epoxy resin as a binder separately from water glass and then fired. Alternatively, a thermoplastic resin may be applied after firing.

An outer box (2
) is covered with a mesh cloth made of heat-resistant fibers (
3). This mesh cloth (3) has a cylindrical shape with openings at the front end and rear end, and is stretchable before firing. And such a mesh cloth (3)
To cover the outer box (2) with the mesh cloth (3), widen the opening at the front or rear end of the mesh cloth (3) and cover the outer box (2) with the mesh cloth (3).
After storing it in the container, it is fired again.

In addition, when the outer box (2) is not composed of divided bodies and is fired as a single body, the surface of the outer box-shaped mat fibers is covered with the mesh cloth (3) and fired simultaneously in the mold. Fire.

In addition, with the outer box (2) covered with the mesh cloth (3), the holding part (5) of the exhaust pipe (4) protrudes from the front end opening of the mesh cloth (3), and the holding part (5) of the exhaust pipe (4) protrudes from the rear end opening. A tail pipe portion (6) integrally molded with the outer box (2) protrudes. A sealing material (7) is interposed between the inner peripheral surface of the holding part (5) and the exhaust pipe (4) to prevent exhaust leakage, and a tightening band (8) is installed around the outer circumference of the holding part (5). It is wound around to firmly hold the exhaust pipe (4). Furthermore, the inside of the outer box (2) is connected to the outside via a separator (lO) equipped with a communication pipe (8) and the 111th tension chamber (11) where the exhaust pipe (4) faces and the tail pipe section (8). Connecting to the 211th room (
12) It is divided into two parts.

Figure 3 shows the engine (
13), the engine (13) has a crankcase (10) at the bottom, a cylinder (15) is provided at the top of the crankcase (14), and a cylinder head (18) is provided at the top of the cylinder (15). A crank (17) is installed inside the crankcase (14).
A sleeve (18) is provided on the inner surface of the cylinder (15),
A piston (18) that is slidable against this sleeve (18)
) and the crank (17) are connected by a connecting rod (20). Further, the cylinder head (16) is formed with an intake passage (22) connected to the inlet manifold (21) and an exhaust passage (24) connected to the outlet manifold (23).
23) is connected to the exhaust pipe (4).

Further, the intake passage (22) and the exhaust passage (20) include
For example, an intake bow (25) and an exhaust bow (213) made of a molded sound absorbing material having heat resistance of 300° C. or higher are fixed via a heat-resistant adhesive (27). Also,
The surface of these molded sound absorbing materials may be covered with a mesh cloth made of knitted heat-resistant fibers. (More each bow)
Through holes are formed in (25) and (2B), valve guides (28) and (28) are inserted into these through holes, and intake and exhaust valves (213) are inserted into these valve guides (28) and (28).
).

(28) is inserted. Note that (30) in the figure is a spark plug.

In addition, the shape of the intake boat (25) or exhaust boat (C26) is as shown in Figure 4.
It is not necessary to form a hole for passing the through.

In this way, if the engine intake boat (25) is made of a heat-resistant and heat-insulating molded sound-absorbing material, engine heat will be difficult to transfer to the inlet manifold, etc., and the intake air temperature will always be approximately equal to the outside air temperature. In addition, if the exhaust port (26) is made of molded sound absorbing material, the exhaust heat will be difficult to be transmitted to the cylinder head etc., and the surface temperature of the engine can be lowered. Further, it is possible to reduce noise caused by engine driving. In the illustrated example, the intake and exhaust ports are made of molded sound-absorbing material, but it is also conceivable that the exhaust port or the manifold itself be made of molded sound-absorbing material.

In the above, the gas burned in the engine (13) is the exhaust bow) (2B), the outlet manifold (23)
) and enters the exhaust pipe (4) as exhaust gas, and passes through this exhaust pipe (0) to the muffler (
1) is introduced into the first expansion chamber (11), where it expands and consumes the stored energy, and then enters the second expansion chamber (12) via the communication pipe (8), where it expands again and is retained. The energy is consumed and is finally discharged to the outside through the tail pipe section (6).

Here, the exhaust gas consumes its retained energy due to expansion, and since the inner part of the muffler (1) is a porous layer (2a) with excellent sound absorption properties, the exhaust noise becomes extremely small.

As is clear from the above description, according to the present invention, the outer box of the silencer is constructed of molded sound-absorbing material, which dramatically improves the sound deadening effect and reduces weight compared to the conventional method. Since the outer peripheral surface of the box is covered with a mesh cloth, the strength of the entire outer box can be increased, and especially when the outer box is formed by joining divided pieces, it is possible to increase the adhesive strength of the joint. Become. In addition, since it is a mesh cloth, it has many effects such as improved appearance.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a silencer according to the present invention, FIG. 2 is an enlarged sectional view of the main parts of the same, FIG. 3 is a sectional view of an engine disposed upstream of the silencer, and FIG. 4 FIG. 7 is a sectional view showing another embodiment of the port portion. In the drawings, (1) is a silencer, (2) is an outer box, (3) is a mesh cloth, (4) is an exhaust pipe, (6) is a tail pipe section, (13) is an engine, and (25) is a ,(2
B) is a port. Patent Applicant Honda Motor Co., Ltd. Agent Patent Attorney 1) Kuni Ohashi, Patent Attorney, Department, Yu Koyama, Patent Attorney, Department

Claims (1)

[Claims] In a muffler into which exhaust gas from an internal combustion engine such as a gasoline engine is introduced, the outer case of the muffler is made of a molded sound-absorbing material, and the outer peripheral surface of the outer case is covered with a mesh cloth. Features of this silencer for internal combustion engines.