Silencing device

Abstract

A muffling device (10) has a muffling container (1) and a communication pipe (3) that communicates an intake passage (2) of an internal combustion engine with the muffling container (1). The communication pipe (3) has a main pipe (3a) connected at one end to the intake passage (2) and a plurality of branch pipes (3b, 3c) branched from the main pipe (3a) and each communicating with the muffling container (1). The plurality of branch pipes (3b, 3c) each reduce sound pressure of a different frequency. According to the muffling device, sound pressure of a plurality of frequencies can be reduced in one resonance cavity.

Description

Technical Field

[0001] This disclosure relates to a muffler device having a muffler container connected to the intake passage of an internal combustion engine. Background Technology

[0002] Japanese Patent Application Publication No. 2019-143478 discloses a noise reduction device that uses a resonator (Helmholtz resonator) in the intake passage of an internal combustion engine to reduce intake noise caused by the opening and closing of the intake valve of the internal combustion engine. Figure 2 This is a schematic diagram of the structure of a resonator 20 in the prior art. The resonator 20 includes: a resonating cavity 21; and a generally cylindrical connecting pipe 22 that connects the intake passage of the internal combustion engine to the resonating cavity 21. Figure 2 As shown, if the length of the connecting tube 22 is set to l, the cross-sectional area of ​​the connecting tube 22 is set to S, the volume of the resonating cavity 21 is set to V, the speed of sound is set to c, and the circumference ratio is set to π, then the resonator 20 can reduce the sound pressure at frequency f by resonating at the frequency f shown in the following formula 1.

[0003] Formula 1 Figure 2 The resonators shown in the prior art can only reduce the sound pressure at one frequency. Therefore, in order to reduce the sound pressure at multiple frequencies, multiple resonating cavities are required. Patent Document 1 discloses a silencing device with multiple resonating cavities for reducing the sound pressure at multiple frequencies. However, in order to set up multiple resonating cavities in the intake passage of an internal combustion engine, a large space is required for setting up multiple resonating cavities, and the cost increases accordingly with the increase in the number of resonating cavities. Utility Model Content

[0004] Therefore, the purpose of this disclosure is to provide a noise reduction device with a single resonating cavity that can reduce the sound pressure at multiple frequencies.

[0005] The silencing device disclosed herein has a silencing container and a connecting pipe that connects the intake passage of an internal combustion engine to the silencing container. The connecting pipe is characterized in that it 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. The plurality of branch pipes are respectively connected to the silencing container, and the plurality of branch pipes respectively reduce the sound pressure at different frequencies.

[0006] This disclosure provides a noise reduction device with a single resonating cavity that can reduce the sound pressure at multiple frequencies. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the structure of the silencing device according to an embodiment of the present disclosure.

[0008] Figure 2This is a schematic diagram of the structure of a resonator in the prior art. Detailed Implementation

[0009] The following is for reference Figure 1 The silencing device 10 of this embodiment will be described. Figure 1 This is a diagram showing the structure of the silencer 10. (For example...) Figure 1 As shown, the muffler 10 has a muffler container 1 and a connecting pipe 3. The muffler container 1 serves as a resonance chamber, and the connecting pipe 3 connects the intake passage 2 of the vehicle's internal combustion engine and the muffler container 1. The connecting pipe 3 includes: a main pipe 3a, one end of which is connected to the intake passage 2 of the internal combustion engine; a first branch pipe 3b and a second branch pipe 3c, which branch off from the other end of the main pipe 3a. The main pipe 3a penetrates the wall 11 of the muffler container 1, and the first branch pipe 3b and the second branch pipe 3c branching off from the main pipe 3a are disposed inside the muffler container 1. Figure 1 In this diagram, to illustrate the first branch pipe 3b and the second branch pipe 3c disposed inside the silencing container 1, the silencing container 1 is only shown as a cross-sectional schematic diagram. Both the first branch pipe 3b and the second branch pipe 3c extend in a direction orthogonal to the main pipe 3a. Furthermore, both the first branch pipe 3b and the second branch pipe 3c have open ends, thereby communicating with the silencing container 1. The main pipe 3a, the first branch pipe 3b, and the second branch pipe 3c all have a generally cylindrical shape with the same cross-sectional area.

[0010] like Figure 1 As shown, if the length of the main pipe 3a is set as la, the length of the first branch pipe 3b is set as lb, the cross-sectional area of ​​the main pipe 3a is set as Sa, the cross-sectional area of ​​the first branch pipe 3b is set as Sb, the volume of the silencing container 1 is set as V, the speed of sound is set as c, and pi is set as π, then the silencing device 10 can make the frequency fb shown in the following formula 2 resonate through the main pipe 3a, the first branch pipe 3b and the silencing container 1, thereby reducing the sound pressure of the frequency fb.

[0011] Formula 2 Furthermore, such as Figure 1 As shown, if the length of the second branch pipe 3c is set to lc and the cross-sectional area of ​​the second branch pipe 3c is set to Sc, then the silencing device 10 can make the frequency fc shown in the following formula 3 resonate through the main pipe 3a, the second branch pipe 3c and the silencing container 1, thereby reducing the sound pressure of the frequency fc.

[0012] Formula 3 exist Figure 1In the silencing device 10 of the illustrated embodiment, 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, and 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 fc is a different frequency from the frequency fb. That is, the first branch pipe 3b and the second branch pipe 3c reduce the sound pressure at different frequencies. In this way, the silencing device 10 has only one silencing container 1, but by making the two frequencies fb and fc resonate in one silencing container 1, the sound pressure at both frequencies fb and fc can be reduced.

[0013] The noise reduction device disclosed herein is not limited to the above-described manner and can be implemented in various ways within the scope 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. Furthermore, 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. In addition, the number of branch pipes branching from the main pipe 3a may be three or more. Increasing the number of branch pipes branching from the main pipe 3a increases the number of frequencies at which sound pressure can be reduced. For example, when there are three branch pipes branching from the main pipe 3a, sound pressure at three frequencies can be reduced. Furthermore, the internal combustion engine connected to the intake passage 2 is not limited to an internal combustion engine for vehicles, but may also be an internal combustion engine for ships, aircraft, construction machinery, or generators, etc.

[0014] Explanation of reference numerals in the attached figures 1: Silencer container 2: Intake passage 3: Connecting pipe 3a: Supervisor 3b: First branch pipe; 3c: Second branch pipe 10: Silencing device 11: wall 20: Resonator 21: Resonating cavity 22: Connecting pipe.

Claims

1. A muffler, comprising a muffler container and a connecting pipe communicating with the intake passage of an internal combustion engine to the muffler container, characterized in that, The connecting pipe has the following features: The main pipe, one end of which is connected to the intake passage; and Multiple branch pipes branch off from the main pipe. The multiple branch pipes are respectively connected to the silencing container. The multiple branch pipes reduce the sound pressure at different frequencies.

Images