JPH0241294Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a cylinder body for a silencer for an internal combustion engine.

The muffler cylinder of an internal combustion engine generates transmitted sound depending on the explosion energy of the engine, although it varies depending on the size, shape, plate thickness, and internal structure.

Especially in the case of layouts where there is not enough space for installing a silencer, such as in cars and motorcycles, the shape of the silencer (outer cylinder) becomes gradually flatter to ensure sufficient noise reduction effect. There are many cases in which the volume increases. Therefore, the proportion of transmitted sound can be equal to or even higher than that of exhaust sound.

Conventional countermeasures include increasing the thickness of the outer cylinder to increase its mass, wrapping damping material (e.g. glass wool, asbestos, etc.) around the entire circumference, or partially bridging the left and right sides of the cylinder with pipes or plates. Things like connecting are performed. However, these damping materials not only have poor workability but also have the disadvantage of being expensive.

In addition, it has been proposed that a sealed space is formed between the inner and outer plates of the silencer cylinder and a perforated plate is disposed within the space, but this method suffers from the drumming phenomenon of the inner and outer plates and the interference chatter noise of the perforated plate holding part. Generates noise.
Also, since it cannot be rolled and formed, there is a problem in manufacturing cost.

The purpose of the present invention is to obtain a cylinder for a muffler that solves this problem.
A corrugated plate c is sandwiched between the parts where transmitted sound is generated to form a triple layer, and the crests of the waves of the corrugated plate c are pressed against the outer cylinder a and the troughs of the waves are pressed against the inner cylinder b by seaming process to create a space between the inner and outer cylinders. This is a cylindrical body of a silencer for an internal combustion engine in which a large number of substantially independent small space layers d are formed.

In particular, areas that generate transmitted sound, such as the cylindrical wall surface of the first chamber where the exhaust gas introduction pipe of a silencing chamber that is divided into many sections with partition plates, or the chamber with the largest volume, or the long side of the flat shape shown in the figure. High sound absorption performance is achieved by making the surface a triple wall with corrugations c in between, and by forming a large number of substantially independent small space layers d in parallel. Furthermore, continuous seaming can be performed using a mandrel.

Fig. 1 shows a cross-sectional view of a cylinder according to the present invention, in which a material plate 1 is wound around a three-fold oval flat cylinder of a, b, and c, and the ends 1a and 1b are fixed by welding. , Before the winding process, the required part of the flat plate (the illustrated example is the long side surface of the flat cylinder) is coated with a height of 2 to 3 mm, for example.
By forming the corrugation, the long side surface is integrally formed with a triple wall of the inner tube a, the outer tube b, and the corrugated plate c therebetween. Then, by seaming, the crests of the outer waves abut against the outer cylinder a, and the troughs of the waves abut against the inner cylinder b, forming substantially independent small spaces d between the crests and troughs.

The length of the corrugated portion c is, for example, as shown in FIG.
This is the entire circumferential length of the first chamber 5 where the exhaust gas introduction pipe 4 opens. Alternatively, use the wall surface of the room where the degree of transmission of sound is large, such as the largest sound-deadening room.

Fig. 3 shows an embodiment in which another plate e formed in a corrugated shape is pre-spot welded to the required part of the material plate 1, and the material plate 1 is wound. A double cylinder is formed.

In addition to forming the waveform in the cross section as shown in FIGS. 1 and 3, it is also possible to form it in the longitudinal section by devising processing.

As mentioned above, the present invention has a three-layer structure in which the part of the muffler cylinder that generates transmitted sound in particular has a corrugated plate sandwiched between the inner and outer cylinders, forming many independent small space layers. is well attenuated. Since it can be made using the usual method of wrapping it around a metal core and forming a cylinder, material and labor costs can be kept low. Due to the integral continuous seaming process, the peaks of the corrugated plate are pressed against the outer cylinder, the valleys are pressed against the inner cylinder, the small space layers are each independent, and the inner and outer cylinders face each other through the small air layer and the corrugated plate, so that No drumming phenomenon occurs. Further, since the peaks and valleys of the corrugated plate are in pressure contact with the outer cylinder and the inner cylinder, respectively, there is no interference chatter between them, and there is also an effect that no noise is generated.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the cylindrical body of the present invention, FIG. 2 is a partially vertical side view of the cylindrical body, and FIG. 3 is a cross-sectional view of another embodiment. a...Inner cylinder, b...Outer cylinder, c...Corrugated plate, d...
...Small space layer, 5...First sound deadening chamber.

Claims (1)

[Scope of utility model registration request] A corrugated plate is sandwiched between the inner and outer cylinders in the areas where transmitted sound is generated to make a triple layer, and the crests of the waves of the corrugated plate are pressed against the outer cylinder and the troughs of the waves are pressed against the inner cylinder by seaming process to create a space between the inner and outer cylinders. A cylindrical body of a silencer for an internal combustion engine that forms a number of almost independent small space layers.