JP3009327U - Airflow silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] With a simple and inexpensive structure, it improves the sound deadening effect on the air flow of high temperature, high pressure and high speed energy such as exhaust of internal combustion engine, and also improves the workability of assembly and maintenance inspection. . [Structure] In a sound deadening chamber 12, ten or more porous sound absorbing ceramic materials 4 having a central hole are concentrically overlapped and filled, and an air flow passage 8 is formed by the central hole of each ceramic material 4. A cushioning material 5 is mounted between the ceramic material 4 and the inner surface of the muffling chamber 12, and the front surface of the most upstream ceramic material 4A and the rear surface of the most downstream ceramic material 4B are held via cushioning materials 6A and 6B, respectively. Hold by 7A and 7B.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure of an airflow silencer suitable for mounting in a place where noise due to airflow is generated, such as an exhaust system of an internal combustion engine.

[0002]

[Prior art]

 In devices such as exhaust systems of internal combustion engines of automobiles and motorcycles, which emit high-temperature, high-pressure, high-speed, and high-energy gas, vibration is propagated through the pipe wall and air, causing a large amount of noise.

As a method of obtaining a sound deadening effect at the time of discharging the sound energy flow, a resistance type that uses frictional resistance on the wall surface of the flow path, an expansion type that uses speed reduction when flowing into the expansion chamber from the throttle portion, and a flow path A diffusion prevention type that absorbs sound with a sound absorbing member such as glass wool that is attached to the inner surface, or an interference type that lowers the sound pressure level by interfering sounds with different phases in different passages with each other is used. Recently, it has also been proposed to use a porous sound-absorbing ceramic material that has sound-absorbing properties and frictional resistance against airflow as part of a sound deadening device.

As a conventional sound deadening device using a ceramic material, a structure in which the ceramic material is appropriately combined with each of the above-described sound deadening mechanisms is generally used. As the structure, for example, a pipe member, It is used in combination with a sheet metal partition plate and sound absorbing glass wool to provide a sound deadening function.

[0005]

[Problems to be solved by the device]

 However, in the conventional airflow silencer of this type, in order to form a chamber of various volumes as an expansion chamber, to arrange a sound absorbing material in each expansion chamber, or to impart a frictional resistance force to the airflow. Since it is necessary to use pipe members of various shapes and dimensions, the arrangement of the airflow passages in the muffler chamber (reverse flow passage, eccentric passage) becomes complicated, and the cost increases due to an increase in the number of parts and assembly man-hours. There was an inconvenience.

In addition, in the conventional configuration in which a ceramic material is used for only a small part of the sound deadening structure, it takes a lot of time to finish it to a desired dimensional accuracy, resulting in a high price, and further, a vibration which is a weak point of ceramics. It is necessary to reinforce the brittleness with high-strength pipe members and partition plates, which requires new structural parts and increases the number of processing man-hours, which raises costs. There is. Therefore, the current situation is that airflow silencers that use ceramics as part of their structure are rarely used in general.

The present invention has been made in view of such technical problems, and an object of the present invention is to use a large amount of a porous sound absorbing ceramic material as a sound deadening material (about 75% or more of the sound deadening chamber volume). ), It has a simple and inexpensive structure, and can exert a high noise reduction effect on high-temperature, high-pressure, and high-speed energy airflow, and also has excellent workability in assembly and maintenance. It is to provide an airflow silencer that has never been seen before.

[0008]

[Means for solving the problem]

 The airflow silencer of the present invention has five or more porous sound-absorbing ceramic materials having a central hole, which are concentrically overlapped with each other, and an airflow passage is formed by the central hole of each ceramic material. A cushioning material is installed between each ceramic material and the wall surface of the muffling room, the front surface of the ceramic material on the most upstream side is held by the holding member via the cushioning material, and the rear surface of the ceramic material on the most downstream side is cushioned material. The above-mentioned object is achieved by adopting a structure in which it is held by a holding member via the above.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an embodiment of an airflow silencer to which the present invention is applied, and FIG. 2 is a sectional view taken along line 2-2 in FIG. 1 and 2, a gas inlet 2 is formed by an inflow pipe portion 10 at the upstream end (front end) of the muffler chamber 12 formed of a hollow cylindrical case, and the downstream end of the muffler chamber 12 is formed. A gas outlet 3 is formed at the (rear end) by the outflow pipe portion 11. The silencing chamber 12 is filled with five or more ceramic materials 4 in an overlapping state. The number of the ceramic materials 4 is variously selected depending on the length of the muffling device and the thickness of the ceramic material 4 itself. For example, usually about 10 to about 30 are selected.

Each ceramic material 4 has a through hole in the center thereof, and these ceramic materials 4 are concentrically overlapped with each other, so that the gas inlet 2 to the gas outlet 3 are provided in the center of the sound deadening chamber 12. An airflow passage 8 communicating therewith is formed. In the embodiment shown in FIGS. 1 and 2, the airflow passage 8 is a cylindrical through hole having substantially the same diameter (inner diameter) from the upstream side opening (front end opening) 9A toward the downstream side opening (rear end opening) 9B. Is formed by. The diameter of the central hole of the ceramic material 4 is determined by an experiment. For example, when the diameter of the silencing chamber 12 is about 100 mm, the diameter of the central hole is selected to be about 30 to 50 mm.

FIG. 3 is a longitudinal sectional view showing another embodiment of the airflow silencer to which the present invention is applied. In this embodiment, the air flow passage 8 formed in the central portion by stacking five or more ceramic materials 4 is formed in a stepwise manner from the upstream side opening 9A to the downstream side opening 9B as shown in the figure. It is formed so that the diameter gradually decreases. That is, in the present embodiment, the diameter of the central hole of the ceramic material 4 arranged on the upstream side and the diameter of the central hole of the ceramic material 4 arranged on the downstream side are changed in a stepwise direction. Therefore, the inner diameter (cross-sectional area) of the airflow passage 8 changes in a stepwise decreasing direction. For example, when the diameter of the airflow passage having a length of about 30 cm is gradually reduced, the cross-sectional area of the upstream opening 9A is set to about 20 cm ^{2 and} the cross-sectional area of the downstream opening 9B is set to 4.5 cm ^2. It is selected to be about 16.0 cm ² .

1 to 3, the ceramic used as the ceramic material 4 is excellent in heat resistance, but may be brittle against vibration or impact. Therefore, for holding the ceramic material 4 between the outer peripheral surface of the ceramic material 4 and the inner surface of the muffling chamber 12, which are stacked five or more (for example, about 10 to about 30 normally). A buffer material 5 having elasticity is provided. The front surface of the most upstream ceramic 4A is positioned and held by a plate-shaped holding member 7A fixed in the muffling chamber 12 via an elastic cushioning material 6A on the upstream side. Further, the rear surface of the most downstream ceramic 4B is positioned and held by the flanged holding member 7B fixed in the muffling chamber 12 via the elastic cushioning material 6B on the downstream side.

Next, the operation of the airflow silencer described above will be described. A high-energy air current, such as the exhaust system of an internal combustion engine, that is subject to noise reduction is made to flow in the direction of the arrows in FIGS. 1 and 3. That is, the air flow (exhaust gas) coming from the arrow a flows from the inflow pipe portion 10 into the air flow passage (through hole) 8 through the upstream opening 9A of the ceramic material 4. Due to the high pressure, this exhaust gas enters the inside of the ceramic material 4 as indicated by the arrow c, and is reflected on the inner surface of the cushioning material 5 as indicated by the arrow e, or between the ceramic materials 4 as indicated by the arrow d. Inflow or. Further, this exhaust gas flows out from the inside of the ceramic material 4 into the airflow passage 8 as shown by an arrow f, or in the most downstream ceramic material 4B as an internal backflow as shown by an arrow g, becomes a main flow passing through the airflow passage 8. Join together. The entire exhaust gas, including the exhaust gas having various behaviors as described above, flowing into the muffling chamber 12 flows out to the atmosphere (outside) from the downstream side opening 9B through the gas outlet 3 as shown by an arrow b. .

The exhaust gas flow from the airflow passage 8 to the gas outlet 3 is accompanied by the sound absorption, sound pressure attenuation, and sound attenuation along with the flow as indicated by the arrows c 1, d 2, and e 3 as described above. Reflection and sound interference occur, and the sound is mixed with the main flow in the intake passage 8 along with the flow as indicated by the arrows f and g to generate gas friction and attenuate the sound due to the interference. Outflow from 3 to the atmosphere. By filling the silencing chamber 12 with five or more ceramic materials 4 each having a central hole, various gas flows and accompanying sound attenuation are performed, and the sound absorption effect and the friction resistance effect of each ceramic material 4 are remarkable. I was able to obtain a great muffling effect. In addition, the increase in outflow resistance and the loss (decrease in horsepower) hardly occurred in spite of the increase in the silencing effect.

FIG. 4 is a schematic diagram showing a schematic configuration when the airflow silencer 1 of FIG. 1 or 3 is used as an exhaust silencer of the internal combustion engine 20. In FIG. 4, an exhaust pipe 22 of a predetermined length made of a steel pipe is connected to an exhaust port 21 of an internal combustion engine 20, and the exhaust pipe 22 is connected to an inflow pipe portion 10 of an airflow silencer 12 according to the present invention. Has been done. In some cases, the exhaust pipe 22 and the inflow pipe portion 10 may be formed of a common pipe.

According to the arrangement shown in FIG. 4, high-temperature, high-pressure, high-speed, high-energy exhaust gas (exhaust gas) from the exhaust port 21 is introduced into the muffler 1 through the exhaust pipe 22, and the muffler 1 is placed there. The sound pressure level of the exhaust gas (exhaust gas) is effectively reduced by the action of the above-mentioned sound deadening mechanism. After being silenced to a predetermined level in this way, it is discharged to the atmosphere from the outflow pipe portion 11 having a predetermined length. The length of the outflow pipe portion 11 can be selected to be, for example, about 5 to 10 cm in consideration of the wavelength of exhaust pulsation and the like.

[0017]

[Effect of device]

 As is clear from the above description, according to the airflow silencer of the present invention, five or more porous sound-absorbing ceramic materials having a central hole are concentrically arranged in the sound deadening chamber, and An air flow path is formed by the center hole, and a cushioning material is installed between each ceramic material and the wall surface of the sound absorbing room, and the front surface of the ceramic material on the most upstream side is held by the holding member via the cushioning material, and the most downstream side. Since the rear surface of the ceramic material is held by a holding member via a cushioning material, it is possible to obtain a sufficient silencing effect for high-temperature, high-pressure, high-speed, high-energy airflow such as exhaust from an internal combustion engine. Therefore, an airflow silencer can be obtained which can significantly reduce the cost by simplifying the structure and reducing the number of assembling steps.

[Brief description of drawings]

FIG. 1 is a vertical sectional view schematically showing a schematic configuration of an embodiment of an airflow silencer to which the present invention is applied.

FIG. 2 is a schematic cross-sectional view taken along the line 2-2 in FIG.

FIG. 3 is a vertical sectional view schematically showing a schematic configuration of another embodiment of an airflow silencer to which the present invention is applied.

FIG. 4 is a schematic view showing a state in which the airflow silencer according to the present invention is used in an exhaust system silencer of an engine of a motorcycle.

[Explanation of reference numerals] 1 airflow silencer 2 gas inlet 3 gas outlet 4 porous sound absorbing ceramic material 4A most upstream ceramic material 4B most downstream ceramic material 5 elastic cushioning material 6A upstream cushioning material 6B Downstream cushioning material 7A Holding member 7B Holding member 8 Airflow passage 9A Upstream side opening 9B Downstream side opening 10 Inflow pipe part 11 Outflow pipe part 12 Silence chamber 20 Internal combustion engine 21 Exhaust port 22 Exhaust pipe

Claims (1)

[Scope of utility model registration request] 1. A sound-absorbing chamber, wherein five or more porous sound-absorbing ceramic materials having a central hole are concentrically overlapped with each other, and an air flow passage is formed by the central hole of each ceramic material. A cushioning material is mounted between the inner wall surface of the muffler room, the front surface of the ceramic material on the most upstream side is held by the holding member via the cushioning material, and the rear surface of the ceramic material on the most downstream side is held by the holding member via the cushioning material. An airflow silencer characterized by holding.