Air intake duct for motor vehicle

Abstract

To inhibit airflow sound generated by air passing through a drain hole of a resonator.SOLUTION: The invention relates to an air intake duct for a motor vehicle having a resonator. The resonator has an outer wall that encloses an internal space. A bottom surface of the outer wall is provided with at least one drain hole configured as a penetrating channel penetrating through the outer wall. A thick portion is disposed at at least a peripheral edge of the drain hole to increase a length of the penetrating channel.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an air intake duct for a motor vehicle. [Background technology]

[0002] To operate an engine such as an automobile, an intake duct is required to supply outside air to the engine. When air flows through the intake duct, intake noise can occur due to natural vibrations and the like. Because this intake noise is unpleasant to automobile drivers and others, resonators have traditionally been provided in intake ducts to reduce this intake noise. Because resonators have a structure that makes them prone to water accumulation depending on their installation location and shape, they often have drain holes (see, for example, Patent Documents 1 to 5). However, at certain air flow speeds in the intake duct, air passing through these drain holes can generate airflow noise. As the demand for low noise in automobiles increases year by year, there is a need to suppress such airflow noise.

[0003] Conventionally, there are known methods for suppressing the airflow noise generated from the drain holes by adding tuning holes, protrusions, or straightening plate shapes, or a combination of these, to the resonator. However, these methods require significant modifications to the intake duct path and the internal shape of the resonator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 2-1460 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-240520 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-144560 [Patent Document 4] Japanese Patent Application Laid-Open No. 2014-118920 [Patent Document 5] Japanese Patent Publication No. 2022-144027 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an intake duct that can easily suppress airflow noise generated by air flowing through a drain hole of a resonator. [Means for solving the problem]

[0006] According to one embodiment of the present invention, the above problem is solved by an intake duct for an automobile having a resonator, the resonator having an outer wall surrounding an internal space, at least one drain hole formed as a through-passage penetrating the outer wall being provided on the bottom surface of the outer wall, and the length of the through-passage being extended by providing a thick portion at least around the periphery of the drain hole.

[0007] This allows drain holes to be provided where necessary and suppresses airflow noise without being restricted by the flow path of the intake duct or the internal shape of the resonator. Also, because the effect of suppressing airflow noise is achieved simply by providing drain holes with extended through-path lengths, it is possible to avoid major modifications to the route of the intake duct or the internal shape of the resonator.

[0008] Preferably, the through passage has a rounded chamfer at the entrance.

[0009] Preferably, the length of the through passage is twice the thickness of the outer wall. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a bottom view of an air intake duct for an automobile. [Figure 2] 1A and 1B are schematic cross-sectional views of a resonator. [Figure 3] 10 is a graph showing the effect of suppressing airflow noise by a resonator. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the following description, the drawings are schematic, and the dimensional relationships and ratios of elements may differ from the actual ones. The dimensional relationships and ratios may differ between the drawings.

[0012] FIG. 1 is a bottom view of an intake duct 10 for an automobile. Arrows indicate the flow of outside air. Outside air introduced from outside the vehicle passes through the intake duct 10 and is supplied to an air cleaner (not shown), where it is filtered. The filtered outside air is then guided downstream to the engine. The bottom surface of the intake duct 10 is provided with multiple resonators 20, 20', and 20'' to suppress intake noise in the intake duct. The resonators 20, 20', and 20'' have the effect of suppressing airflow noise generated due to natural vibrations and the like when outside air flows through the intake duct 10. In FIG. 1, the resonators 20 and 20' each have a drain hole 24, but the resonator 20'' does not have a drain hole.

[0013] FIG. 2 is a schematic cross-sectional view of a resonator 20 according to this embodiment. The resonator 20 has an outer wall 22 surrounding an internal space. At least one drain hole 24 is provided in the bottom surface of the outer wall 22 to prevent the accumulation of water and other contaminants. The drain hole 24 may have any shape, but is preferably circular. The drain hole 24 is formed as a through-passage 26 penetrating the outer wall 22, and the length of the through-passage 26 is extended by providing a thickened portion at least around its periphery. The thickened portion may be formed integrally with the outer wall, or may be formed by post-attaching a member surrounding the drain hole 24 to the resonator by adhesive or the like. The extended through-passage 26 effectively suppresses airflow noise generated when air is drawn into the resonator 20 through the drain hole 24.

[0014] The entrance of the through passage 26 may not be chamfered as shown in Fig. 2(A), or may be rounded as shown in Fig. 2(B). Experiments conducted by the inventors of the present application have shown that either shape of the through passage 26 will produce the same effect of suppressing airflow noise.

[0015] Preferably, the length of the through passage 26 is twice the thickness of the outer wall 22. However, depending on the frequency of the airflow sound, etc., the length of the through passage 26 may be set to be greater than or less than twice the thickness of the outer wall 22.

[0016] FIG. 3 is a graph showing the flow noise suppression effect of the resonator 20 according to this embodiment. The graph shows the frequency spectrum of the flow noise generated from one of the resonators 20 shown in FIG. 2, with the horizontal axis representing frequency (Hz) and the vertical axis representing sound pressure (dB). Curve G1 in the graph corresponds to the flow noise generated from a resonator with a conventional drain hole, curve G2 corresponds to the flow noise generated from a resonator with a drain hole that extends the through hole according to this embodiment, and curve G3 corresponds to the flow noise generated from a resonator with the drain hole completely blocked. It can be seen that the sound pressure value of curve G2 is suppressed relative to the sound pressure value of curve G1 in almost the entire frequency range shown. It can also be seen that the sound pressure value of curve G2 has many frequency ranges that are not significantly different from the sound pressure value of curve G3 when the drain hole is blocked. Thus, by forming the drain hole 24 of the resonator 20 as an extended through passage 26, it is possible to significantly suppress flow noise.

[0017] The extended through-holes in the resonator according to this embodiment may be used in combination with known tuning holes, protrusions, or rectifier plate shapes also provided in the resonator.

[0018] In this embodiment, the resonators 20, 20' are each provided with one drain hole 24 at the end of the resonator in the flow direction of the intake duct 10. This is because by separating the drain hole 24 from the neck of the resonators 20, 20' (i.e., the flow path side of the intake duct) as far as possible, it becomes difficult for air to pass through the resonators 20, 20' through the drain hole 24, thereby minimizing the generation of resonance noise caused by the drain hole 24. The reason for providing only one hole is to prevent a reduction in the resonator effect caused by providing a hole.

[0019] In this embodiment, the drain holes 24 of the resonator 20 are provided with thickened portions, but the drain holes 24 of the resonator 20' are not provided with thickened portions. This is because it has been confirmed through actual measurements that the resonator 20' is not affected by the resonance sound caused by the drain holes 24. [Explanation of symbols]

[0020] 10 Intake duct 20, 20', 20'' resonator 22 Exterior Wall 24 drain holes 26 Passage

Claims

1. An air intake duct for a motor vehicle having a resonator, The resonator has an outer wall surrounding an internal space, At least one drain hole formed as a through-passage penetrating the outer wall is provided on the bottom surface of the outer wall, The length of the through passage is extended by providing a thickened portion at least around the periphery of the drain hole. Intake duct.

2. The air intake duct of claim 1 , wherein the through passage has a radiused chamfer at the inlet.

3. 3. An intake duct according to claim 1, wherein the length of the through passage is twice the thickness of the outer wall.

4. The intake duct according to claim 1, characterized in that the resonators are provided in multiple numbers on the side of the intake duct, and in the resonators provided with the drain holes, each of the drain holes is provided at one end of the resonator.

5. 5. The intake duct according to claim 1, wherein the thick portion is provided only on a resonator that generates a large resonance sound due to the drain hole.

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