Silencing device

Abstract

The present invention provides a sound-dampening device that can reduce sound pressure at multiple frequencies using a single resonance chamber. [Solution] A silencing device 10 having one silencing container 1 and a connecting pipe 3 that connects the intake passage 2 of an internal combustion engine to the silencing container 1, wherein the connecting pipe 3 comprises a main pipe 3a with one end connected to the intake passage 2 and a plurality of branch pipes 3b, 3c that branch off from the main pipe 3a, and each of the plurality of branch pipes 3b, 3c is in communication with the silencing container 1, and each of the plurality of branch pipes 3b, 3c reduces sound pressure of different frequencies.

Description

[Technical Field]

[0001] The present invention relates to a sound-dampening device comprising a sound-dampening container that communicates with the intake passage of an internal combustion engine. [Background technology]

[0002] Patent Document 1 discloses a noise reduction device that uses a resonator (Helmholtz resonator) in the intake passage of an internal combustion engine to reduce intake noise generated by the opening and closing of the intake valve of the internal combustion engine. Figure 2 shows the configuration of a prior art resonator 20. The resonator 20 comprises a resonance chamber 21 and a substantially cylindrical connecting pipe 22 that connects the intake passage of the internal combustion engine to the resonance chamber 21. As shown in Figure 2, if the length of the connecting pipe 22 is l, the cross-sectional area of ​​the connecting pipe 22 is S, the volume of the resonance chamber 21 is V, the speed of sound is c, and pi is π, then the resonator 20 can reduce the sound pressure at frequency f by resonating at the frequency f shown in the following Equation 1.

[0003]

number

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-143478 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The conventional resonator shown in Figure 2 can only reduce sound pressure at one frequency. Therefore, in order to reduce sound pressure at multiple frequencies, it is necessary to provide multiple resonance chambers. Patent Document 1 discloses a sound-dampening device that has multiple resonance chambers to reduce sound pressure at multiple frequencies. However, providing multiple resonance chambers in the intake passage of an internal combustion engine requires a large space for the multiple resonance chambers, and the cost increases with each additional resonance chamber.

[0006] Therefore, the present invention aims to provide a sound-dampening device that can reduce sound pressure at multiple frequencies using a single resonance chamber. [Means for solving the problem]

[0007] The sound-dampening device according to the present invention is a sound-dampening device comprising a sound-dampening container and a connecting pipe that connects the intake passage of an internal combustion engine to the sound-dampening container, wherein the connecting pipe comprises a main pipe with one end connected to the intake passage and a plurality of branch pipes branching off from the main pipe, each of the plurality of branch pipes communicating with the sound-dampening container, and each of the plurality of branch pipes reducing sound pressure of different frequencies. [Effects of the Invention]

[0008] The present invention provides a sound-dampening device that can reduce sound pressure at multiple frequencies using a single resonance chamber. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the configuration of the sound-dampening device according to the disclosed embodiment. [Figure 2] This diagram shows the configuration of a conventional resonator. [Modes for carrying out the invention]

[0010] The silencing device 10 of this embodiment will be described below with reference to Figure 1. Figure 1 is a diagram showing the configuration of the silencing device 10. As shown in Figure 1, the silencing device 10 has a silencing container 1 that functions as a resonance chamber and a connecting pipe 3 that connects the intake passage 2 of an internal combustion engine for a vehicle to the silencing container 1. The connecting pipe 3 has a main pipe 3a at one end which is connected to the intake passage 2 of the internal combustion engine, and a first branch pipe 3b and a second branch pipe 3c that branch off from the other end of the main pipe 3a. The main pipe 3a penetrates the wall 11 of the silencing container 1, and the first branch pipe 3b and the second branch pipe 3c that branch off from the main pipe 3a are located inside the silencing container 1. In Figure 1, only the silencing container 1 is drawn as a cross-sectional view to show the first branch pipe 3b and the second branch pipe 3c located inside the silencing container 1. Both the first branch pipe 3b and the second branch pipe 3c extend in a direction perpendicular to the main pipe 3a. The first branch pipe 3b and the second branch pipe 3c are both open at their ends and are in communication with the sound-dampening container 1. The main pipe 3a, the first branch pipe 3b, and the second branch pipe 3c all have a roughly cylindrical shape with a uniform cross-sectional area.

[0011] As shown in Figure 1, if the length of the main pipe 3a is la, the length of the first branch pipe 3b is lb, the cross-sectional area of ​​the main pipe 3a is Sa, the cross-sectional area of ​​the first branch pipe 3b is Sb, the volume of the silencer container 1 is V, the speed of sound is c, and pi is π, then the silencer 10, through the main pipe 3a, the first branch pipe 3b, and the silencer container 1, produces a sound at the frequency f shown in the following equation 2. b By resonating, the frequency f b It can reduce the sound pressure.

[0012]

number

[0013] Furthermore, as shown in Figure 1, if the length of the second branch pipe 3c is lc and the cross-sectional area of ​​the second branch pipe 3c is Sc, then the silencer 10, consisting of the main pipe 3a, the second branch pipe 3c, and the silencer container 1, produces a frequency f as shown in the following equation 3. c By resonating, the frequency f c It can reduce the sound pressure.

[0014]

number

[0015] In the silencer 10 of the embodiment shown in FIG. 1, the cross-sectional area Sc of the second branch pipe 3c is the same as the cross-sectional area Sb of the first branch pipe 3b, but the length lc of the second branch pipe 3c is shorter than the cross-sectional area lb of the first branch pipe 3b. Therefore, the frequency f c is a frequency different from the frequency f b . That is, the first branch pipe 3b and the second branch pipe 3c reduce the sound pressure of different frequencies. Thus, although the silencer 10 has only one silencing container 1, by resonating two frequencies of the frequency f b and the frequency f c in one silencing container 1, the sound pressures of the two frequencies of the frequency f b and the frequency f c can be reduced.

[0016] <Supplementary Explanation of the Embodiment> The silencer of the present disclosure is not limited to the above-described form, and can be implemented in various forms within the scope of the gist of the present disclosure. For example, the cross-sectional area Sc of the second branch pipe 3c may be different from the cross-sectional area Sb of the first branch pipe 3b. And when the cross-sectional area Sc of the second branch pipe 3c is different from the cross-sectional area Sb of the first branch pipe 3b, the length lc of the second branch pipe 3c may be the same as the cross-sectional area lb of the first branch pipe 3b. Also, the number of branch pipes branching from the main pipe 3a may be three or more. By increasing the number of branch pipes branching from the main pipe 3a, the number of frequencies for which the sound pressure can be reduced can be increased. For example, when there are three branch pipes branching from the main pipe 3a, the sound pressures of three frequencies can be reduced. Further, the internal combustion engine to which the intake passage 2 is connected is not limited to an internal combustion engine for a vehicle, and may be an internal combustion engine used in a ship, an aircraft, a construction machine, a generator, or the like.

Explanation of Reference Numerals

[0017] 1 Silencing container, 2 Intake passage, 3 Communication pipe, 3a Main pipe, 3b First branch pipe, 3c Second branch pipe, 10 Silencer, 11 Wall, 20 Resonator, 21 Resonance chamber, 22 Communication pipe.

Claims

[Claim 1] A silencing device comprising one silencing container and a connecting pipe that connects the intake passage of an internal combustion engine to the silencing container, The aforementioned connecting pipe comprises a main pipe, one end of which is connected to the intake passage, and a plurality of branch pipes that branch off from the main pipe. Each of the aforementioned branch pipes is in communication with the sound-dampening container. A sound-dampening device characterized in that the multiple branch pipes each reduce sound pressure at different frequencies.

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