JPS59101517A - Exhaust muffler for internal-combustion engine - Google Patents

Abstract

PURPOSE:To muffle exhaust noise of internal-combustion engine considerably without blocking exhaust flow, by forming exhaust flow path with linear flow path having enlarged diameter section and reduced diameter section alternatively. CONSTITUTION:Sound wave (s) led into a casing 1 together with exhaust gas is reflected by a noise shielding board 12 then reflected repeatedly by tubular structure 6 and casing 1 where acoustic energy is converted to thermal energy by acoustic members 9, 10 and absorbed. Since sound wave (s) is reflected repeatedly by tubular structure 6 and casing 1, it will provide same effect with expanded acoustic material layer 8 to absorb sound wave effectively. Furthermore the acoustic material layer 8 will function as a resonant cavity (spring) while a vent 11 will function as a neck section (mass) to consume energy of sound wave (s) through resonance (including absorption through acoustic members 9, 10). While since the cross-section of exhaust flow path 7 will repeat enlarged and reduced sections by means of tubular structure 6 and sound shielding board 12, pressure vibration of sound wave is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust silencing device for an internal combustion engine, and more particularly to an exhaust silencing device for an internal combustion engine that can significantly reduce exhaust noise and reduce engine exit loss.

Conventional exhaust silencing methods include the following.

(,) An expansion method that expands sound waves into a cavity, dilutes the acoustic energy density, and muffles the sound by squeezing it at the edge of the cavity.

(b) A resonance method in which the exhaust pipe and a resonance cavity provided in parallel with the exhaust pipe are communicated with each other through a communication hole or the like, and all of the sound energy is consumed by resonance.

('C) A sound absorption method that absorbs sound by converting acoustic energy into thermal energy using sound absorbing materials.

(d) An interference method in which the acoustic tube is branched to give a path difference to split the sound waves, and then they join together again to attenuate the sound waves by sound interference.

And in the past, these methods? Exhaust noise is silenced by appropriate combinations.

However, none of the conventional exhaust mufflers has a sufficient silencing effect, and those that have a certain degree of silencing effect V'c have detoured and branched the exhaust flow, or The exhaust gas flow was obstructed because the exhaust gas was over-squeezed, resulting in a loss of engine output.

The present invention has been devised to effectively solve all of the above-mentioned conventional problems, and an object of the present invention is to provide exhaust silencing for an internal combustion engine that can significantly reduce exhaust noise and completely reduce engine output loss. There is an I/C that provides the device.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 11, 1 is a cylindrical casing, an exhaust pipe 2 is connected to one end of the casing, and a discharge pipe 3 is connected to the other end of the casing 1 on the central axis of the casing 1. An exhaust gas introduction port 4 is formed at the tip of the exhaust pipe 2, and an exhaust gas discharge port 5 is provided on the side wall of the discharge pipe 3.

Inside the casing 1, a bellows-shaped cylindrical structure 6 is provided along the same axis as shown in FIG. The cylindrical structure 6 has a cross section shaped like a 7-shaped uneven wave or a 1-triangular wave, and the cylindrical structure 6 allows the inside of the casing 1 to have a diameter increasing from the exhaust pipe 2 to the discharge pipe 3. Part γ
A linear exhaust flow path 7 is formed in which the diameter-reduced portions 1b and 1b are alternately repeated.

A sound absorbing material layer 8 filled with a sound absorbing material is formed between the cylindrical structure 6 and the casing 1. The sound-absorbing material layer 8 includes a heat-insulating sound-absorbing material 9 such as glass wool or asbestos arranged on the inner wall surface of the casing 1, and lathe scraps, which have a rougher gap than glass wool, on the inner cylindrical structure 6 side. The sound absorbing material 10 is composed of two types of sound absorbing materials. Further, the cylindrical structure 6 is provided with a large number of ventilation holes 11 so that sound waves can freely pass between the sound absorbing material layer 8 and the exhaust flow path 7 in the cylindrical structure 6. It has become.

Further, each enlarged diameter portion 7aVc of the exhaust flow path 7 is arranged so that a sound insulating plate 12 having a larger diameter than the reduced diameter portion 7b crosses the exhaust flow path 7 at right angles so that sound waves do not pass through the exhaust flow path 7. It is provided. As shown in FIG. 11 or FIG. 13, the sound insulating plate 12 has a uniform and relatively thick disk shape at the center, and a distal portion on the outer periphery extends outward in the radial direction so as to fully guide the exhaust gas. It is formed in a tapered shape that gradually becomes thinner towards the end. The sound insulating plate 12 is supported by a support member (not shown) on the tapered structure 6.

Next, the operation of this embodiment will be described.

Exhaust gas discharged from an internal combustion engine or the like is introduced into the casing 1 through the exhaust pipe 2 and through the exhaust introduction port 4. The introduced exhaust gas hits the sound insulating plate 12, is guided by this, passes between the sound insulating plate 12 and the cylindrical structure 6, sequentially flows downstream through the exhaust flow path 7, and then reaches the exhaust outlet 5. It is then discharged into the atmosphere from the discharge pipe 3. The exhaust flow path 7 is formed straight from the exhaust pipe 2 toward the discharge pipe 3, and
Since the sound insulating plate 12 is provided on the enlarged diameter part 1a so as not to excessively restrict the cross section of the flow path, the exhaust gas is smoothly discharged from the discharge pipe 3, and the output loss of the internal combustion engine due to this muffler is extremely small. .

On the other hand, the sound waves (
Exhaust noise) is silenced as follows.

The sound waves 8 are reflected by the sound insulating plate 12, and then repeatedly reflected by the cylindrical structure 6 and the casing 1, as shown in FIG. converted and absorbed. In this way, the cylindrical structure 6 having a large number of ventilation holes 11 and having a V-shaped cross section and an uneven wave shape is provided, and the cylindrical structure 6 and the casing 1 are connected to each other.
Since the sound absorbing material layer 8 is formed between the
Since the sound waves are reflected many times by the cylindrical structure 6 and the casing IVfC, the same effect as when the sound absorbing material layer 8 is expanded is achieved, and the sound waves are effectively absorbed.

Furthermore, the sound absorbing material layer 8 acts as a resonant cavity (spring), and the ventilation hole 1
1 acts as a neck (mass), and the energy of the sound wave S is consumed by resonance (accompanied by sound absorption by the sound absorbing materials 9 and 10). Further, since the cross section of the exhaust flow path 1 is repeatedly expanded and contracted by the cylindrical structure 6 and the sound insulating plate 12, the pressure vibration of the sound wave is thereby suppressed.

Next, a second embodiment of the present invention will be described with reference to the drawings from FIG. 1 to FIG. 1O. In this embodiment, the sound insulation plate 13
, 14, 15 are movably supported in the casing 1 axis direction, and the damper shaft 16 is provided with
This embodiment is characterized by the fact that a magnetic damper is attached to the end of the magnet 6, and the differences from the above embodiments will be described below.

The cylindrical structure 6, as shown in FIG. 3, has a large number of plate-shaped bodies 11 having a ventilation hole 1γat in the center stacked one on top of the other in a facing manner, and welded or soldered together to integrate them. A damper shaft 16 is provided on the central axis of the casing 1, which is connected to the damper shaft 16, and sound insulating plates 13 and 15 are attached to the damper shaft 16. The sound insulation board 13 has almost the same shape as the sound insulation board 12, as shown in FIG. 6, and the sound insulation board 14 has many concentric shapes on its upstream side, as shown in FIGS. The rib 1sai is provided with several rows of holes 15b arranged radially.

The damper shaft 16 has a sliding sound insulating plate 1 shown in FIG.
4 boss portion 14b and slide bearing 18t shown in FIG.
- penetrates the casing and is supported for axial movement; The boss portion 14b is supported by 94 tension wires 19 arranged radially around the dish-shaped body 1γ. The sound insulating plate 14 has a disk shape of equal thickness and has one row of holes 14 and radially in each of the four directions.A slide bearing 18 is suspended from the inner wall surface of the discharge pipe 3 by a tension wire 19'. ing. Note that a rod member may be used instead of a tension wire.

Further, the saw shaft 16 extends outward through the discharge pipe 3, and an end member 20 is provided at the end thereof, and the end member 20 extends in a direction perpendicular to the saw shaft 16. One end of each of the arms 21 and 21 is fixed. And the other end I/c/ of the arms 21, 21
li, two each (D support nm 22.23 are attached, and the tips of the support rods 22 and 23 have magnets 24.24' and 2
5.25' are provided respectively. Between each pair of magnets 24, 24' and 25, 25', copper plate-shaped conductor members 26, 27 are arranged, respectively, as shown in FIG. It is K-shaped so that it can move relative to each other. The conductor members 26, 27 are connected to the support member 28.
29, the support member 28°29 is supported by the discharge pipe 3
It is supported by support protrusions 30.degree. 31 projecting from the top. Note that 32 and 33 are return springs. Incidentally, instead of the sound insulating plate 13, as shown in FIG.
The provided wing-shaped sound insulating plate 34 may be provided on one shaft 16. In this case, acoustic energy can be absorbed by the vibrations of the blades of the sound insulating plate 34 themselves.

In this embodiment, in addition to the above-mentioned embodiment, a Danno IP that vibrates with pulsation and vibration energy is used.
- The shaft 16 is connected to a magnet 24, 24' and a conductor member 26, and a magnet 25, 25' and a conductor member 2T.
The purpose is to dampen and absorb the p-vibration.

As is clear from the above description, according to the present invention, the exhaust noise of an internal combustion engine can be significantly muffled.
When an automobile engine is operated indoors, no matter how good a conventionally known muffler is attached, the noise is unbearable.However, with the muffler of the present invention, it is possible to have a conversation without any difficulty even when having a conversation indoors. What is it? Further, since the exhaust flow path is straight and a sound insulating plate is provided at the enlarged diameter portion, the exhaust flow is not obstructed, and the loss of output of the internal combustion engine can be reduced. Furthermore, it has a simple structure, can be manufactured easily, and can exhibit excellent effects such as being highly useful.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway plan view showing an embodiment of the device of the present invention, Fig. 2 is an enlarged vertical sectional view of the same, Fig. 3 is a front view and a sectional view of the dish-shaped body, and Fig. 4 is FIG. 5 is a partially enlarged longitudinal sectional view of the casing, FIG. 5 is an end view of the magnetic damper, FIG. 6 is a front view of the sound insulating plate seen from the vi-vtm direction of FIG. 2, and FIG. A front view of the sound insulation board seen from the vll-■ line direction,
Figure 8 is a front view of the sound insulation board seen from the W-■ line direction in Figure 2, and Figure 9? i IX-D in Figure 2 (cross-sectional view taken along the line, No. 1O
11 is a vertical sectional view showing another embodiment of the device of the present invention, FIG. 12 is an enlarged sectional view of the same, and FIG. 13 is a plan view of the sound insulating plate. FIG. 14 is a front view showing another embodiment of the sound insulating plate. In the figure, 1 is the casing, 2 is the exhaust pipe, 3 is the discharge pipe, 4 is the exhaust inlet, 5 is the exhaust outlet (exhaust outlet), 6 is the cylindrical structure, γ is the exhaust flow path, and 1a is the expansion The diameter part, 7b is the reduced diameter part,
8 is a sound absorbing material layer, 9 and 10 are sound absorbing materials, 11 is a ventilation hole, 12
, 13, 14. is is a sound insulating board.

Claims (1)

[Claims] 1. In order to form an exhaust flow path, an exhaust inlet port is provided at one end of the exhaust flow path,
A cylindrical casing having an exhaust outlet at the other end, and a bellows-like cylindrical casing provided in the casing to form enlarged diameter portions and reduced diameter portions alternately along the axial direction of the casing. a structure, a large number of ventilation holes provided in the cylindrical structure, a sound absorbing material layer filled between the casing and the cylindrical structure, and a sound absorbing material layer formed in the expanded diameter part of the cylindrical structure. An exhaust silencing device for an internal combustion engine, characterized by comprising a sound insulating plate provided across the entire exhaust flow path. 2. The exhaust silencing device for an internal combustion engine according to claim 1, wherein the cylindrical structure has a substantially V-shaped cross section with a four-wave shape formed by the enlarged diameter portion and the reduced diameter portion. .