JPH06294323A - Exhaust muffler of engine - Google Patents

Abstract

PURPOSE:To reduce the number of parts and increase assembly property by plastically forming a hollow box which constitutes an exhaust muffler and a bulkhead which constitutes an exhaust passage on its inner face integrally. CONSTITUTION:A hollow box which constitutes an exhaust muffler 20 is formed by superposing a plural number of box members 21, 22, which have an outer wall face, on each other, and a plural number of expansion chambers are constituted by a bulkhead 25 which is plastically formed integrally with the outer wall face on an inner face of the box. One of the expansion chambers is used as a flow-in chamber 27 which is connected to an engine through a flow-in port, and the other is used as an exhaust chamber 29 which is led to atmospheric air through an exhaust port. The flow-in chamber 27 and the exhaust chamber 29 are connected by a communicating passage 30. Further, a plural number of labyrinth grooves 32 are provided in a wall face which acts as the flow-in port the flow-in chamber 27, and an exhaust pipe 16 is inserted into the flow-in port. Consequently, it is possible to reduce the number of parts and produce parts and perform assembly work easily at low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust silencer connected to a motorcycle or a small general-purpose engine.
In particular, the present invention relates to an exhaust silencer molded from a light alloy or a heat resistant synthetic resin.

[0002]

2. Description of the Related Art Conventionally, as an exhaust silencer for motorcycles,
The half sections with a substantially semi-circular cross section obtained by press forming a steel sheet face each other and are polymerized and welded to form a cylindrical shape. It is known that chambers are formed and a steel pipe is connected between them to form a series of exhaust passages from an inflow port to an exhaust port (for example, Japanese Utility Model Publication).

Further, the engine and the exhaust silencer are connected by an iron exhaust pipe. Generally, the exhaust silencer and the exhaust pipe are integrally inseparably welded or formed separately to connect them. The part is air-tightly sealed with a heat-resistant rubber packing.

[0004]

Therefore, in general, the number of parts constituting the exhaust silencer is large, and a lot of man-hours are required for press-molding and welding and assembling those parts, so that the manufacturing cost is remarkably reduced. It was difficult. The inventors
In order to eliminate such problems, we tried to replace the exhaust silencer with conventional press molding and use a mold made of light alloy or heat resistant synthetic resin (hereinafter referred to as plastic molding), but connect it to the engine. If the exhaust pipe and the subsequent exhaust silencer were to be made integrally, the heat resistance of the portion of the exhaust pipe through which the hot exhaust gas flows did not reach. We also attempted to connect the two by molding them separately, but the need for a sealing member at those connecting parts not only complicates the structure, but also complicates the assembly work, which causes a problem that increases difficulty. It was

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and has the durability of an exhaust silencer made of a steel pipe or a steel plate, the number of parts of a plastic exhaust silencer, or the ease of assembly. According to the invention of claim 1, an exhaust muffler for an engine having both goodness is provided.
A plurality of box members having outer wall surfaces are superposed on each other to form a hollow box body, and a plurality of expansion chambers are formed on the inner surface of the box body by partition walls integrally formed with the outer wall surface. One of them is an inflow chamber connected to the engine through an inflow port, and the other is an exhaust chamber communicating with the atmosphere through an exhaust port, and the inflow chamber and the exhaust chamber are connected by a communication passage. The invention according to claim 2 is further characterized in that a plurality of labyrinth grooves are provided on the wall surface forming the inflow port to the inflow chamber, and the exhaust pipe is inserted into the inflow port.

[0006]

[Function] If a plurality of box members are overlapped with each other,
A box forming an exhaust silencer is completed, and at the same time, an expansion chamber that attenuates exhaust energy is formed inside the box. That is, a plurality of expansion chambers partitioned by the partition wall integrally formed with the outer wall surface are formed, and further, an inflow port for connecting the exhaust pipe and the muffler is formed together with the labyrinth groove provided on the wall surface.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, 10 is a motorcycle. Motorcycle 1
Reference numeral 0 has a vehicle body frame 13 supported by front wheels 11 and rear wheels 12. Engine 14 on body frame 13
Is supported. The engine 14 has an intake pipe 15 connected to the rear side and an exhaust pipe 16 connected to the front side. 17 is a carburetor installed in the intake pipe 15, and 18 is the carburetor 17
Is a fuel tank for supplying fuel to. Further, the exhaust pipe 16 is connected to an exhaust port (not shown) opened to the front side of the engine 14, is largely curved from the exhaust port 16 and extends rearward and downward, and an exhaust silencer 20 is connected to a rear end portion thereof.
It should be noted that there is no great difference in the above configuration from a conventionally known motorcycle.

The present invention is an improvement of the exhaust silencer 20. That is, the exhaust silencer 20 first
Instead of conventional iron or stainless steel, a light alloy or heat-resistant synthetic resin is used. The light alloy is specifically an aluminum alloy, and the heat-resistant synthetic resin is a glass fiber reinforced phenol resin, 6 nylon, or the like.

In view of the structure, instead of the conventional welded and assembled structure, as shown in FIG. 2 and thereafter, its outer shell and partition wall are molded (molded as described above) by a mold such as casting or injection molding. . Further, the two box members 21 and 22 which are made almost symmetrically are overlapped face to face and connected by bolts 23 to form a hollow box shape, which is also a novel structure. That is, each of the box members 21 and 22 forming the exhaust silencer 20 has a box shape with one side opened by the outer wall surface 24. Further, three expansion chambers are formed on the inner surface of the box body by the partition wall 25 integrally formed with the outer wall surface 24.

That is, one of the expansion chambers is an inflow chamber 2 having an inflow port 26 connected to the downstream end of the exhaust pipe 14.
7 and the other one is two discharge pipes 28 made of steel pipe,
An exhaust chamber 29 communicating with the atmosphere via 28, and an intermediate chamber 31 communicating with both chambers 27, 29 at the same time by intermediate pipes 30, 30 forming a communicating passage. In this way, a series of exhaust passages E are formed inside the exhaust silencer 20.

Here, the outer wall surface 24 forming the inflow chamber 27 is provided with an inflow port 26 into which the exhaust pipe 14 is inserted. The inlet 26 is formed to have the same diameter as the outer diameter of the exhaust pipe 14 or a small diameter, and the wall surface is formed thick and a plurality of labyrinth grooves 32 are formed on the wall surface. The inflow chamber 27 is configured in this way, and the exhaust pipe 14 is simply inserted into the inflow port 26, and can be easily inserted and removed to facilitate the assembling work. In addition, although the exhaust pipe 14 is assembled in such a manner that it is movable in the axial direction, the exhaust pipe 14
Since the labyrinth groove 32 is formed around the area, the exhaust gas and the exhaust noise hardly leak to the outside from this portion. Further, even if it is used for a long period of time, its sealing performance does not deteriorate. Exhaust gas flowing from the engine into the inflow chamber 27 flows in a pulsating flow through the exhaust pipe 14 when the exhaust stroke of the engine starts. At this time, the exhaust gas expands and attenuates in the inflow chamber 27, becomes a relatively smooth airflow, and flows through the intermediate pipe 30 to the next intermediate chamber 31.

The intermediate chamber 31 is provided with the outer wall surface 2 provided so as to face each other.
4, the labyrinth walls 33 formed so as to project alternately and in parallel from
33, thereby forming a curved labyrinth 34 from one side to the other. That is, since a long exhaust passage is formed in a relatively narrow space, the exhaust gas flowing from the inflow chamber 27 through the intermediate pipe 30 has a further decreased flow velocity due to passage resistance, gas expansion, or cooling, resulting in pulsation of the airflow or pressure wave. Is attenuated and flows to the next discharge chamber 29.

The discharge chamber 29 is internally provided with a partition wall 35 which is formed so as to project inward from the outer wall surface 24, and is composed of two small chambers connected to each other through a narrow space formed at the tip thereof. One of the small chambers communicates with the upstream intermediate chamber 31 through the intermediate pipe 30, and the other is opened to the atmosphere through the two discharge pipes 28. Therefore, the exhaust gas that has flowed in through the intermediate pipe 30 reaches the exhaust pipe 28 through the narrow space and is exhausted into the atmosphere from there.
That is, the pressure fluctuation of the exhaust gas that has exited the intermediate pipe 30 does not reach the exhaust pipe 28. The lengths of the two exhaust pipes 28 and the intermediate pipe 30 are determined in consideration of the reduction of exhaust resistance and the sound quality of exhaust sound. Therefore, its length is generally obtained experimentally. However, it is said that better sound quality can be obtained by making the lengths of the two intermediate pipes 30 slightly different.

Next, the behavior of the exhaust gas discharged from the engine will be described. First, in the exhaust stroke, in a two-stroke engine, when the piston descends to open the exhaust port, in a four-stroke engine, the exhaust valve opens and the exhaust stroke starts at the same time. Exhaust gas discharged from the combustion chamber causes a high-pressure pressure wave to act on the exhaust passage, and at the same time, becomes a high-temperature, high-speed, violent airflow and flows into the exhaust pipe 16. And the exhaust pipe 16
It expands or cools inside and reaches the exhaust silencer 20. The pressure wave is reflected at the open end of the exhaust pipe 16 and returns to the exhaust port of the engine again, but at that time, the scavenging stroke ends in the two-stroke engine and the exhaust stroke ends in the four-stroke engine. Is set. Also, during this time,
Although it depends on the operating state, generally, the exhaust temperature is cooled to around 200 ° C. and flows into the inflow chamber 27 having a relatively large volume. The resin material used in this example, such as phenol resin and 6-nylon, can withstand a temperature of about 270 ° C., and there is no problem in durability.

Then, it further expands there, the pressure and temperature are lowered, and then flows to the next intermediate chamber 31. A relatively long labyrinth 34 is created in the intermediate chamber 31, through which the exhaust flow slowly expands while expanding and also decreasing in temperature. While doing so, the engine 14 enters the next cycle and the exhaust gas is again discharged to the exhaust pipe, and when the engine speed is high, it becomes a substantially continuous flow and is discharged through the other intermediate pipe 30. It flows into the chamber 29.

In the above embodiment, the intermediate pipe 30 and the discharge pipe 28 communicating with each expansion chamber are connected to the box member 21,
Although an example in which it is configured separately from 22 is shown, it is also within the scope of the present invention to form these integrally with the main frame 41 having a partition wall as shown in FIG.

In the present invention, the box member 21,
The method of dividing 22 is not limited to the above embodiment, and for example, as shown in FIGS. 6 and 7, the main frame 41 having a partition wall and both surfaces thereof are opened, and the opening is a symmetrical cover. It is also within the scope of the present invention to configure the body 42, 42 to be closed. Moreover, it is also the same as using the screw nails 43 and 43 instead of the said bolt 23.

[0018]

As described above, according to the present invention, the hollow box body forming the exhaust silencer 20 and the partition wall 25 for forming the exhaust passage are integrally formed on the inner surface thereof. Therefore, the number of parts constituting the same is small, the parts can be easily produced and assembled, and the parts can be manufactured at low cost. Further, according to the second aspect of the present invention, the inflow port 26 into which the exhaust pipe 16 is inserted is made the same as or slightly thicker than the exhaust pipe 16 and the labyrinth groove 32 is provided around the exhaust port 16.
6 is easily inserted, its assemblability is good, and there is an effect that there is no leakage of exhaust gas or exhaust noise.

[Brief description of drawings]

FIG. 1 is a side view of a motorcycle equipped with an exhaust silencer according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the exhaust silencer.

FIG. 3 is a sectional view taken along the line III-III.

FIG. 4 is a IV-IV sectional view thereof.

FIG. 5 is a VV sectional view thereof.

FIG. 6 is a sectional view corresponding to FIG. 3 showing another embodiment.

FIG. 7 is a sectional view corresponding to FIG. 4 showing another embodiment.

[Explanation of symbols]

 16 ... Exhaust pipe 20 ... Exhaust silencer 21, 22 ... Box member 24 ... Outer wall surface 25 ... Partition wall 26 ... Inflow port 27 ... Inflow chamber 29 ... Exhaust Chamber 31 ... Intermediate chamber 32 ... Labyrinth groove

Claims (2)

[Claims] 1. A plurality of box members having outer wall surfaces are superposed on each other to form a hollow box body, and a plurality of expansion chambers are formed on the inner surface of the box body by partition walls integrally formed with the outer wall surface. And one of the expansion chambers is an inflow chamber connected to the engine through an inflow port, and the other is an exhaust chamber communicating with the atmosphere through an exhaust port, and between the inflow chamber and the exhaust chamber. An engine exhaust muffler that is connected by a communication passage to form a series of exhaust passages. 2. A plurality of box members each having an outer wall surface are polymerized with each other to form a hollow box body, and a plurality of expansion chambers are formed on the inner surface of the box body by partition walls integrally formed with the outer wall surface. However, one of the expansion chambers is an inflow chamber that is connected to the engine through an inflow port, and the other is an exhaust chamber that communicates with the atmosphere through an exhaust port.The inflow chamber and the exhaust chamber are connected to each other. An exhaust silencer for an engine, comprising a series of exhaust passages connected by passages, a plurality of labyrinth grooves provided on the wall surface forming the inlet, and an exhaust pipe inserted through the inlet.