JPS587049Y2 - muffler - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a so-called extended resonance type muffler in which a front side insertion tube and a rear side insertion tube are inserted and fixed in a sealed casing.

Generally, in a single-stage expansion type muffler 1 as shown in FIG. 1, an inlet-side exhaust pipe 2. Outlet side exhaust pipe 3, tubular body 4
It is known that resonance sounds are generated in the air column inside the tube due to such factors.

If the type is open at both ends as shown in this figure, f=-・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・ (1) L where f: Resonant frequency C: Speed of sound L: Length of the tubular body n: Expressed as an integer.

Also, if it is one end closed type.

The fact that such a frequency occurs when exhaust gas passes through is that
This means that sounds with this frequency characteristic go out without being muffled.

Therefore, if the relationship between the attenuation and the frequency of this open-ended muffler 1 is illustrated, as shown in FIG. 3, the attenuation decreases significantly when the frequency increases.

For this reason, the length of the insertion tube 6.7 on the front side or the rear side of the extended resonance type muffler 5 has traditionally been selected so that the amount of attenuation increases at the point where the amount of attenuation is significantly reduced. ing.

This length 11.13 is the acoustic effective length I am trying to make it so that

In addition. You may make it so that

If the length is set in this way, attenuation opposite to that of the single-stage expansion type muffler 1 described above will occur.

Normally, the amount of attenuation is large where the resonance frequency occurs.

In this case, each of the insertion tubes 6 and 7 can be considered to be of the one-end closed type, so the resonant frequency that should occur under normal conditions is calculated from the equation (2) above: for the front insertion tube 6, for the rear insertion tube 7 should be.

Substituting equations (3) and (4) into equations (5) and (6) yields.

Therefore, in this muffler 5 Freon On the side On the tour side The amount of attenuation for each frequency increases.

However, if the relationship between the amount of attenuation and the frequency of this muffler 5 is illustrated, there is a problem that attenuation does not occur at some positions as shown in FIG.

Therefore, the present invention was developed with the aim of preventing such incomplete attenuation, and its features include a closed casing in which both ends of the tubular body are closed by end plates;
In a muffler provided with a front side insertion tube and a rear side insertion tube that are respectively inserted through the end plates, the acoustically effective lengths of the two insertion tubes are determined to be a combination of.

One or more small holes are formed in one or both of these push-in tubes at a distance from or to the tip position of the acoustically effective length.

The present invention will be explained below with reference to the drawings.

FIG. 5 is a longitudinal sectional view showing an example of a muffler according to the present invention. This muffler 10 has a front side insertion pipe 15 connected to a closed casing 14 in which both ends of a tubular body 11 are closed by end plates 12 and 13. and rear side insertion tube 16 are inserted by a predetermined length.

Here, the predetermined length means that the acoustic effective lengths 11 and 13 are 1l-io
+03d1 A3=A'2+0.3 d2 The lengths of 11 and 13 are L or a combination of L.

Here, L: axial length of tubular body 11, 0.3: opening end correction coefficient of insertion tube, dl, d2: each insertion tube 15.16
is the inner diameter of

In particular, according to the present invention, one or more small holes 17, 18 are formed in one or more of the two push-in tubes 15, 16 at a distance of L or L from the tip position p1 to p2 of the acoustically effective length. We have opened an individual.

Namely.

Small holes 17 and 18 were opened in connection with this.

Therefore, these small holes 17, 18 and the p1. Since the pipe located between the position p2 and the position p2 becomes a muffler with both ends open, the resonant frequency is calculated using the above equation (1).

If we substitute equation (9) into equation (10), we get becomes.

therefore If L is adopted, frequency is attenuated If you adopt L The frequency of ... can be attenuated.

This is mentioned in (7) above. This means that it is possible to attenuate something that cannot be attenuated at the frequency derived from equation (8).

If the relationship between the amount of attenuation and the frequency of the muffler 10 having such characteristics is illustrated, it can be seen that the muffler 10 exhibits attenuation at all frequencies, as shown in FIG. 6, and the muffler 10 has a high silencing effect.

As is clear from the above description, according to the present invention, small holes are simply opened at a predetermined distance from the tip positions of the front side insertion tube and the rear side insertion tube.

It is possible to remove the so-called bass frequency and obtain a muffler with a high silencing effect.Moreover, since the structure is extremely simple, it is easy to manufacture and the product cost does not increase.

[Brief explanation of drawings]

Figure 1 is a schematic vertical cross-sectional view of a single-stage expansion type muffler. Figure 2 is a schematic vertical cross-sectional view of a conventional extended resonance type muffler.
Figures 3 and 4 are graphs showing the damping characteristics of a single-stage expansion type muffler and an expansion resonance type muffler, Figure 5 is a vertical cross-sectional view showing an example of a muffler according to the present invention, and Figure 6 shows the damping characteristics of the same muffler. It is a graph. 10... Muffler 11... Tubular body, 12゜13... End plate, 14... Sealed casing, 15...°°° Front side Insertion tube, 16
・・・・・・Rear side insertion tube. 17.18... Small hole, L... Length of tubular body.

Claims (1)

[Scope of Claim for Utility Model Registration] In a muffler comprising a closed casing in which both ends of a tubular body are closed by end plates, a front side insertion pipe and a rear side insertion pipe are provided, which are inserted through the end plates, respectively. The acoustically effective length of the tube is determined to be a combination of -IL and 27L (L: length of the tubular body), and the tip of the acoustically effective length is attached to either or both of the insertion tubes. A muffler with one or more small holes opened at a distance of IL4 or iL from the position.