JPH0716006Y2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a silencer for attenuating noise generated by fluid discharged from an internal combustion engine or the like.

[Prior Art] Generally, in a muffler, in order to reduce a wide range of frequency components, a combination of a resonance type and an expansion type muffler or a sound absorbing type muffler using a sound absorbing material is used. Among them, a combination of the resonance type and the expansion type is disclosed in, for example, Japanese Utility Model Publication No. 62-21702. Further, as shown in the publication, the conventional silencer is provided with only one fluid passage.

Here, in the muffler having one fluid passage, the surface area of the perforated plate, the hole diameter and the thickness, the volume of the internal cavity or compartment, the pipe diameter of the fluid passage, and the like are factors of volume reduction. Therefore, in order to obtain a desired sound reduction characteristic, it is necessary to make the surface area of the perforated plate and the pipe diameter of the fluid passage sufficiently large.

[Problems to be Solved by the Invention] However, if the cross-sectional area of the perforated plate is increased, there is a problem that the silencer becomes large in size. Further, in the technique described in the above publication, since the noise reduction effect is obtained by the cavities arranged in series in the fluid flow direction, a large space is required particularly in the fluid flow direction.

Further, the frequency range in which the sound deadening effect is provided in the silencer is greatly influenced by the pipe diameter of the fluid passage, and when the pipe diameter becomes large, the sound deadening effect disappears in the high frequency range. Therefore, the pipe diameter cannot be increased to a predetermined value or more. However, since the pipe diameter of the fluid passage cannot be increased, there are problems that the flow velocity in the passage is increased, the pressure loss is increased, and rubbing noise is generated.

On the other hand, a muffler using a sound absorbing material can be expected to have a sound reducing effect at high frequencies, but the sound absorbing material may contaminate the fluid and is not suitable when it is necessary to keep the fluid clean.

The present invention has been proposed in view of the above-mentioned problems of the prior art, and the sound reduction effect is improved without using a sound absorbing material, and the sound reduction effect is maintained even in a high frequency range, and is compact. The purpose is to provide a silencer.

[Means for Solving the Problems] A muffler of the present invention has an outer cylinder to which an inlet pipe and an outlet pipe are connected, and the inside of the outer cylinder is divided into three sections by a partition plate perpendicular to the longitudinal direction. Of the three compartments, the two compartments communicating with the inlet pipe or the outlet pipe are communicated with each other by a plurality of porous pipes, and the porous pipe penetrates the compartment between the two compartments. The sum of the sectional areas of the plurality of porous tubes is equal to or larger than the sectional area of the inlet tube.

Further, the muffler of the present invention has an outer cylinder to which an inlet pipe and an outlet pipe are connected, and the inside of the outer cylinder is divided into three sections by a partition plate perpendicular to the longitudinal direction, and the three sections are divided. Of the two sections communicating with the inlet tube or the outlet tube of the plurality of porous tubes are communicated with each other, and the porous tube penetrates the section between the two sections, and the plurality of porous tubes are The sum of the inner peripheral lengths of the cross section is equal to or larger than the inner peripheral length of the cross section of the inlet pipe.

[Operation] According to the present invention having the above-described configuration, the sound wave incident from the inlet pipe is divided into a plurality of porous pipes in the section communicating with the inlet pipe. Then, in the plurality of porous tubes, the sound is propagated and reduced into the central section through a large number of small holes on the surface thereof, that is, the section between the section communicating with the inlet tube and the section communicating with the outlet tube. It

In the present invention, since the fluid is divided into a plurality of porous tubes having a diameter smaller than that of the inlet tube in the silencer, the contact area between the fluid and the porous portion (porous tube) is increased, and the individual porous tubes are The cross sectional area of can be reduced. And the sound reduction characteristics are improved by increasing the contact area between the porous portion and the fluid,
On the other hand, by reducing the cross-sectional area of each porous tube, the sound reduction effect can be obtained even in the high frequency range.

Furthermore, since it is not necessary to provide a perforated plate perpendicular to the fluid flow direction, the silencer as a whole can be made compact.

In addition to this, if the sum of the cross-sectional areas of the plurality of porous tubes is made larger than the cross-sectional area of the inlet tube, the contact area increases and the flow velocity and pressure loss decrease. Further, even if the sum of the inner peripheral lengths of the cross sections of the plurality of porous tubes is equal to or more than the inner peripheral length of the cross section of the inlet tube, the total sum of the contact area and the cross sectional area is increased, and the above-described action is achieved.

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

In FIG. 1, a muffler of the present invention, which is generally designated by reference numeral 10, has an outer cylinder 12, to which an inlet pipe 14 and an outlet pipe 16 are connected. The inside of the outer cylinder 12 has two partition plates.
It is divided into three sections S1, S2 and S3 by 18 and 20.

Section S1 communicating with the inlet pipe 14 and section S3 communicating with the outlet pipe 16
Are connected by four porous tubes 22, 22, 22, 22 (see FIG. 2), and a large number of holes are formed on the surface of the porous tubes 22.
24 are perforated. And the porous tube 22 is the central compartment
It extends through S2. The holes 24 are bored in the section S2.

The fluid as shown by the arrow I in FIG. 1 flowing in through the inlet pipe 14 has four porous pipes 22, 22, 2 as shown by the arrow D.
Divide into 2 and 22. The sound wave incident from the inlet pipe 14 propagates through the hole 24 into the compartment S2 and is attenuated when the fluid flows through the porous pipe 22.

Here, as is clear from FIG. 1, since the diameter (inner diameter) φ1 of the porous tube 22 is smaller than the diameter φ2 of the inlet tube 14, as shown in FIG. Is higher than conventional silencers. Further, by increasing the surface area of the porous portion, that is, the total area of the portions where the holes 24 are perforated, the contact area with the fluid is increased and the sound reduction effect is further improved.

In FIG. 3, the volume reduction peak of the conventional silencer is shown to be larger than the volume reduction of the embodiment of the present invention, but various conditions such as the inner type φ1 of the porous tube 24 are appropriately selected. By doing so, the volume reduction of the embodiment of the present invention can be made higher than that of the conventional type in all areas.

[Effects of the Invention] The effects of the present invention are listed below.

(1) The sound volume reduction or sound reduction efficiency is improved.

(2) Since the cross-sectional area of each porous tube can be reduced, the region where the sound reduction effect can be obtained can be expanded to the high frequency side.

(3) It is not necessary to provide a perforated plate perpendicular to the fluid flow direction, and the silencer as a whole can be made compact.

(4) The flow velocity in the silencer becomes slower and the pressure loss decreases.

(5) Since the sound absorbing material is not used, the fluid is kept clean.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the arrow A in FIG. 1, and FIG. 3 is a diagram showing the sound reduction characteristics of the present invention and the prior art. 10 …… silencer, 12 …… outer cylinder, 14 …… inlet pipe, 16 …… outlet pipe, 18, 20 …… partition plate, 22 …… porous pipe, S1 …… compartment communicating with inlet pipe, S2 …… Section between the section communicating with the inlet pipe and the section communicating with the outlet pipe, S3 …… Section communicating with the outlet pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Maeda 11-11 Haneda Asahi-cho, Ota-ku, Tokyo Inside the EBARA CORPORATION (56) References -5906 (JP, U)

Claims (2)

[Scope of utility model registration request] 1. An outer cylinder to which an inlet pipe and an outlet pipe are connected, and the inside of the outer cylinder is divided into three compartments by a partition plate perpendicular to the longitudinal direction, and the inlet of the three compartments. The two sections communicating with the pipe or the outlet tube are communicated with each other by a plurality of porous tubes, and the porous tube penetrates the section between the two sections, and the plurality of porous tubes are disconnected from each other. A silencer characterized in that the total area is equal to or larger than the sectional area of the inlet pipe. 2. An outer cylinder to which an inlet pipe and an outlet pipe are connected, and the inside of the outer cylinder is divided into three sections by a partition plate perpendicular to the longitudinal direction, and the inlet of the three sections is divided. The two sections communicating with the pipe or the outlet tube are communicated with each other by a plurality of porous tubes, and the porous tube penetrates a section between the two sections, and the plurality of porous tubes have cross sections thereof. A silencer characterized in that the total inner peripheral length is equal to or greater than the inner peripheral length in cross section of the inlet pipe.