JPH0218261Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] A muffler for an internal combustion engine that has a structure in which the throat pipe of the resonator and the exhaust gas introduction pipe are coaxially arranged, and the exhaust pressure discharged from the gas introduction pipe is guided to the resonator. (For example, Jikko 54-
44089 and Utility Model Application Publication No. 104311/1983).

[Conventional technology]

A resonator having the above structure is generally referred to as a pulse cushion chamber, and the exhaust gas flow activates pressure within the throat tube, making the resonator more susceptible to excitation and increasing attenuation.

On the other hand, in vehicles such as automobiles and motorcycles where the engine rotation always fluctuates, the exhaust pressure also fluctuates and the amount of attenuation increases or decreases. Furthermore, most of the resonators of mufflers, particularly in automobiles, are used for low-frequency sounds. This is because, as is well known, the fundamental order of engine rotation is low frequency, and this frequency leads to muffled noise inside the room.
The problem lies in the fact that medium and high frequencies can be dealt with relatively easily by other noise reduction means.

[The problem that the idea aims to solve]

Considering mainly low-frequency components in this way, a structure with a large volume and a thick and long throat tube would be ideal in terms of attenuation, but it must be dealt with within the volume determined by the layout of the actual vehicle. In the end, it becomes a small-volume resonance chamber and a narrow throat tube.

However, when a narrow throat tube is used, the exhaust pressure applied to the throat tube decreases when the engine speed is low or during deceleration, resulting in a decrease in the damping effect.

In view of these problems, it is an object of the present invention to provide a structure that does not reduce the damping effect even if the exhaust pressure decreases even if the throat tube is narrow.

[Means to solve the problem]

The present invention consists of an exhaust introduction pipe 2 and a throat pipe 4 of the resonator 3.
In the muffler, the introduction tube 2 is tapered near the throat tube 4, and the opening at the tip 2a is formed smaller than the opening diameter of the throat tube 4, so that both openings are closed. A punching opening 5 is provided on the circumferential surface of the introduction pipe including the tapered constriction part so as to face each other closely.

[Effect]

The introduction tube 2 is tapered near the throat tube 4, and the opening at the tip 2a and the opening of the throat tube 4, which is larger than the opening, are closely opposed to each other.
Even when the engine speed is low and the exhaust flow pressure is low, and even if the throat tube has a small diameter, the exhaust gas primarily flows into the throat tube 4 in a straight injection manner from the tapered portion of the introduction tube 2. During high speed rotation, exhaust gas flows through the punched opening 5.
Since it also flows out from the engine, there is no reduction in engine output due to back pressure loss. In addition, the negative pressure generated around the tapered part effectively activates the pressure inside the throat canal, and this means that the original low-frequency sound reduction function is always ideally exhibited regardless of changes in engine operating conditions. .

〔Example〕

FIG. 1 shows a resonator 3, first and second expansion chambers 6,
7, a silencer consisting of a coupling pipe 8 and a discharge pipe 9 is exemplified, but the overall structure of the silencer is not limited.

Figures 2 to 6 show examples of the constricted shape of the tip 2a of the introduction tube 2, and Figures 2 and 3 are conical,
Fig. 4 shows an example in which a thin tube 2a1 is formed at the tip of the conical part, and Figs. 5 and 6 show examples in which the four radial directions 2a2 are tapered. The opening diameter is smaller than D.

[Effect of idea]

For the reasons described in the above-mentioned operation section, it is possible to obtain a resonance type muffler that functions ideally even in a small-volume resonance chamber and a narrow throat tube, and whose size corresponds to the layout of the automobile.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a silencer implementing the present invention.
FIGS. 2 to 6 are explanatory diagrams of the shape of the tip of the introduction tube. 1 is a silencer, 2 is an introduction tube, 3 is a resonator, 4 is a throat tube, D is its diameter, 5 is a punching opening, 2a
is the tip of the introduction tube.

Claims (1)

[Scope of Claim for Utility Model Registration] In a silencer in which an exhaust inlet pipe and a throat pipe of a resonator face each other on the same axis, the inlet pipe is tapered near the throat pipe, and the opening at its tip is connected to the throat pipe. 1. A muffler for an internal combustion engine, characterized in that a punching opening is formed on the circumferential surface of the introduction pipe including the tapered throttle part, the opening diameter being smaller than the diameter of the opening, the openings being close to each other and facing each other.