JPS60228718A - Sound arrestor - Google Patents

Abstract

An reverse type silencer (10) is combined with a resonance type silencer (20). The resonance type section has a core (22) housed in a shell (26) and filled with a sound absorbing material. Open notches (24) are spirally arranged in the core (22) and include downwardly depending lips (28) forming openings to incoming wave forms. Second waves passing the silencer are reflected and attenuated to dampen noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an exhaust system, and more particularly to an absorption type muffler for an exhaust system.

[Technical background of the invention]

The absorption type muffler has a cylindrical body with a large number of holes,
It consists of a sound-absorbing material such as glass or ceramic fiber filled in the space between the outer surface of the main body and the inner surface of the jacket.

An object of the present invention is to provide a muffling device that can absorb exhaust noise more effectively.

[Summary of the invention]

The silencer according to the present invention includes a cylindrical body having a plurality of notches on its surface.

The notch may have any shape, but is preferably transverse and has a curved portion, which curved portion is pressed down to form a tongue. This curved section may be oriented either forwardly or backwardly.

In a preferred embodiment of the present invention, the notches occupy 30% or less of the surface area and are arranged on a plurality of spiral lines along the longitudinal direction of the cylinder. Each notch forms a group, and longitudinally adjacent notches are about 1 inch apart from each other.
They have a spacing of 0m. This arrangement relies on one wavelength or group of wavelengths of sound being concentrated in one or a group of notches. That is, when the wave is reflected back into the sound wave body into the sound absorbing material, it is shifted out of phase and the input wave is attenuated.

This damping results from the inertia of the gas within the notch. The spiral arrangement of the crater reduces turbulence at high gas velocities.

Although the silencing device of the present invention may be used alone, it is preferable.

It is combined with a second muffler, especially at high exhaust noises. This muffler is preferably arranged downstream of the muffler described above.

Further according to the invention, this second muffling device comprises a core centrally located within the envelope.

The jacket ends at the constricted end and is twisted, and the core has two parts. This first part has an opening that opens on the side of the second part, while the second part opens on the side of the first part and faces rearward (relative to the exhaust gas flow). ing.

The end of the second portion may be secured inside the constricted end of the cover. In this way, gas exiting the first section passes through the second section and is reflected by the aperture end. It then enters the rearwardly facing opening of the second portion forming the air passage.

In a preferred embodiment of the invention, the opening is formed by pinching the ends of adjacent cylindrical bodies (without changing the effective cross-sectional area). As a result, each main body is connected so that the openings thereof face each other and are orthogonal to each other.

Further, the first absorption type silencing chamber and the second silencing chamber may be partitioned by a plate.

Sound waves entering the second muffler are diffused by the first aperture and reflected by the aperture end (which may be an uneven surface). The reflected sound waves act to attenuate the forward moving sound waves both in terms of angle and phase. Furthermore, sound wave energy losses are caused by viscosity and frictional losses, and attenuation is caused by propagating the sound wave energy through a diaphragm or plate that separates the two silencers.

According to a preferred embodiment of the invention, the second portion of the second muffler is provided with a plurality of holes to handle overpressure air in the muffler plenum and to facilitate attenuation of sound waves. .

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

The drawing shows an exploded perspective view of an absorption type muffler according to the present invention, in which a reversible muffler 10 and a resonant muffler 20 are combined.

The resonant portion of the absorption silencer has a core 22.

A jacket 26 is provided to surround the core 22, and the space formed between the core 22 and the jacket is filled with a suitable sound absorbing material such as glass fiber or ceramic fiber.

A feature of the present invention is that a cut hole 24 is provided on the wall surface of the core 22. The above-mentioned crater has a horizontal cutout 27 in the wall of the core.
It is formed by making a tongue piece 28 by pressing down this transverse cutout 27. The row of notches 2'4 has a wave shape. This is because the laws of physics apply to sound waves and are more obvious than their analogues to wind instruments. Therefore, if a waveform passes a certain distance from the opening of the core 22 through a specific crater or a group of craters, that waveform will be absorbed by the sound absorbing material, and the waveform that returns to the core will be returned to the core 22 as the distance between the crater openings is a fraction of the wavelength. If there is, they will be out of phase, resulting in other waveforms with common characteristics.

Another variant of the invention is that the pressed-down tongue 28 is located below the transverse cutout 27.

Although there is one hole at one point at the position of the smallest fraction of the wavelength, it is effective to have two or more holes.

By forming the cutout to an effective depth, it acts not only as an orifice but also as a lateral tributary. The presence of this depth creates an acoustic impedance at the coupling point that is different from the characteristics for the planar waveform in the pipe. As a result, a reflected wave will be formed. A portion of the incident sound energy is transmitted to this branch and dissipated. Both of these factors can attenuate the sound energy transmitted through the pipe section located behind the tributary.

In an embodiment of the invention, the absorption muffler has a reversible muffler 10, which has a pair of cylindrical sections 12.13, opposite ends of the cylindrical sections 12.13. are arranged so as to be crushed and butted as shown in the drawing. A slot is formed for this purpose. A plurality of holes (not shown) may be provided in the surface of the cylindrical portion 12°14.

The jacket 30 of the reversible muffler, which is integral with the jacket 26, has a constricted end 32, which is made by crushing the end of a cylindrical part. The end of the cylindrical portion 14 defines an orifice 34 within the jacket 30.

It extends through.

By crushing the ends of the cylindrical parts 1g and 14, the cylindrical part 12 is
An opening 16 is formed in the cylindrical portion 14, and an opening 28 is formed in the cylindrical portion 14, respectively. These openings 16,18 each adjoin the cylindrical part on both sides.

A reversible silencer of a combined silencer having two routes, one in the central part of two parts formed by crossing the collapsing part, and one in the side opening for gas or sound waves hitting the constriction end 32. Exhaust gas and sound waves enter the area. The shaped portion that intersects the crushed portion changes the cross-sectional area and attenuates sound energy by changing the sound impedance.

The reflected gas and sound waves move in opposite directions from different points on the aperture end 32, with some of the gas flowing through the aperture 18 into the atmosphere and some of the reflected sound waves moving in opposite directions as they join the incoming sound waves. The remainder of the sound wave impinges on the diaphragm 40 provided in the two parts l of the silencer and is transmitted via the diaphragm 40 to the part that is weakened by the absorbing medium.

[Brief explanation of the drawing]

The figure is an exploded perspective view of the silencer according to the present invention. 12... Second part, 14... First part 16.18... Opening, 22... Core, 24... Notch opening, 28...tongue piece. Applicant's agent Ino Writ of amendment for cancellation procedure (method) May 1985 JPO Commissioner Manabu Shiga 1 Indication of case Patent Application No. 76 of 1985 2 Title of invention Silencing device 3 Amendment Relationship with the case of the applicant Patent applicant Jonado, (proprietary), Limited 4 agent April 10, 1985 (Shipping date: April 30, 1985) 6 Applicant column of application subject to amendment, delegation letter, "Brief description of drawings" section of the specification, drawings, and corporate certificate. 7 Contents of amendment (1) The application, power of attorney, and corporate certificate will be amended as shown in the attached sheet. (2) Amend drawings that include serial numbers (no change in content). (3) Page 8, line 16 of the specification [The figures are according to the present invention...]
. . is a perspective view. [FIG. 1 is a perspective view showing one embodiment of the noise reduction according to the present invention, and FIGS. 2 and 3 are perspective views showing the outer cover. ] Correct.

Claims (1)

[Claims] 1. A silencer comprising a cylindrical body having a plurality of glue holes on its surface. 2. The notch opening is formed laterally on a plurality of spiral lines in the longitudinal direction of the cylindrical body, and the circular arc portion of the notch opening is bent inward from the surface to form a tongue piece. A silencer according to claim 1. 3. The muffler has a second muffler including a core disposed in the center of an envelope having a curved outlet, the core comprising a first part and a second part. , the first part is formed by constricting the end of the cylindrical body and joining it to the second part in such a way that the openings are located in opposite directions and a phase difference of 90° is formed between them, 2. The muffling device according to claim 1, wherein the second portion has openings on both sides of the first portion toward the rear.