Noise reduction structure for the front grille

Abstract

To provide a noise reduction structure of a front grille which can reduce noise leaking from the front grill to outside a vehicle while suppressing increase of manufacturing cost.SOLUTION: A noise reduction structure 10 of a front grill 30 comprises: a plurality of rod-like members 34 in which the plurality of rod-like members extend in a vehicle width direction, vehicle rear sides thereof are opened in a cross-sectional view from the vehicle width direction to be approximately U-shaped, and the plurality of rod-like members are arranged at prescribed intervals in a vehicle vertical direction at an inner side of an outer peripheral frame 32 of the front grille 30; a plurality of partition walls 36 in which the plurality of partition walls are arranged in the rod-like member 34 at prescribed intervals in the vehicle width direction, the partition wall extends in a vehicle longitudinal direction at approximately center part of the rod-like member in a side view from the vehicle width direction, and a slit part 36A whose vehicle rear side thereof is opened is given; and a plurality of reflection walls 38 which are arranged in the rod-like member 34 between the partition walls 36 and reflect sound to the slit parts 36A.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a noise reduction structure for a front grille.

Background Art

[0002] A noise reduction structure for a front grille that can enhance the noise reduction effect without impairing the design and ventilation of the front grille and without requiring complicated molding has been proposed in the past (see Patent Document 1). In this noise reduction structure for a front grille, a space portion having an opening only on the engine room side is formed in a rod-shaped member extending within the outer peripheral frame of the front grille, and a partition wall that partitions the space portion into a plurality of spaces having a predetermined opening width is erected, and the opening of the space portion is covered with a sound absorbing material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above structure, since it is necessary to attach a sound absorbing material, the manufacturing cost increases along with the man-hours required for manufacturing the front grille. Thus, there is still room for improvement in a noise reduction structure for a front grille that can reduce the noise leaking from the front grille to the outside of the vehicle while suppressing an increase in the manufacturing cost.

[0005] Therefore, an object of the present invention is to obtain a noise reduction structure for a front grille that can reduce the noise leaking from the front grille to the outside of the vehicle while suppressing an increase in the manufacturing cost.

Means for Solving the Problems

[0006] To achieve the above objective, the noise reduction structure for a front grille according to claim 1 of the present invention comprises: a plurality of rod-shaped members that extend in the vehicle width direction and are formed in a substantially "U" shape with the rear side of the vehicle being the open side when viewed in cross-sectional view from the vehicle width direction, and are provided on the inner side of the outer peripheral frame of the front grille at predetermined intervals in the vehicle vertical direction; a plurality of partition walls provided at predetermined intervals in the vehicle width direction inside the rod-shaped members, with slit portions that extend in the vehicle longitudinal direction and have the rear side of the vehicle being open when viewed from the vehicle width direction, approximately in the center of the vehicle vertical direction in a side view; and a plurality of reflective walls provided inside the rod-shaped members and between the partition walls, which reflect sound to the slit portions.

[0007] According to the invention described in claim 1, a plurality of rod-shaped members are provided on the inner side of the outer frame of the front grille, extending in the vehicle width direction and formed in a substantially "U" shape with the rear side of the vehicle being open when viewed in cross-sectional view from the vehicle width direction, at predetermined intervals in the vehicle's vertical direction. Inside each rod-shaped member, a plurality of partition walls are provided at predetermined intervals in the vehicle width direction, each having a slit portion that extends in the vehicle's front-rear direction and is open at the rear side of the vehicle, approximately in the center of the vehicle's vertical direction when viewed in side view from the vehicle width direction. A plurality of reflective walls are provided inside each rod-shaped member and between the partition walls to reflect sound to the slit portion.

[0008] Therefore, sound generated in the vehicle's power unit room and incident inside the rod-shaped member is reflected by the reflective wall to the slit and passes through the slit. The sound that has passed through the slit is then transmitted to the internal space adjacent to the partition wall having the slit, and interferes with sound (sound waves with a phase difference) that is directly incident on that internal space, causing a portion of that sound to be silenced. Furthermore, sound emitted from that internal space to the outside of the vehicle through the opening of the front grille interferes with sound (sound waves with a phase difference) that is directly emitted to the outside of the vehicle through the opening, causing a portion of that sound to be silenced. In this way, according to the present invention, noise leaking from the front grille to the outside of the vehicle is reduced due to sound wave interference with a phase difference, and the increase in manufacturing costs is suppressed compared to when sound-absorbing material is provided. [Effects of the Invention]

[0009] As described above, the present invention makes it possible to reduce noise leaking from the front grille to the outside of the vehicle while suppressing an increase in manufacturing costs. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic side cross-sectional view showing a partially enlarged view of the front of a vehicle equipped with the noise reduction structure for the front grille according to this embodiment. [Figure 2] (A) A schematic perspective view showing the noise reduction structure of the front grille according to this embodiment. (B) A schematic cross-sectional view taken along the line XX in (A). (C) A schematic cross-sectional view taken along the line YY in (A). (D) A schematic cross-sectional view taken along the line ZZ in (A). [Figure 3] This is a schematic perspective view showing the noise reduction effect of the noise reduction structure of the front grille according to this embodiment. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described in detail below with reference to the drawings. For the sake of explanation, in each figure, the arrow UP will indicate the upward direction of the vehicle, the arrow FR will indicate the forward direction of the vehicle, and the arrow RH will indicate the right direction of the vehicle. Therefore, in the following description, when the directions of up and down, front and back, and left and right are described without further specification, they will refer to the up and down direction of the vehicle, the front and back direction of the vehicle, and the left and right direction of the vehicle (vehicle width direction).

[0012] As shown in Figure 1, the front end of a vehicle 12, such as a plug-in hybrid vehicle or electric vehicle, equipped with the noise reduction structure 10 of the front grille 30 according to this embodiment, is provided with a bumper cover 14 that constitutes the design of the front end. A power unit room 20 is provided behind the bumper cover 14, and a pair of left and right front side members (not shown) extend along the front-rear direction on the outer side in the vehicle width direction of the power unit room 20.

[0013] A bumper reinforcement 16, extending approximately in the vehicle width direction, is provided across the front ends of a pair of left and right front side members located on the front side of the vehicle 12. An absorber 18 is provided between the bumper cover 14 and the bumper reinforcement 16 (on the rear side of the bumper cover 14 and the front side of the bumper reinforcement 16). This absorber 18 is configured to absorb the energy of the collision load input from the front side in the event of a frontal collision of the vehicle 12.

[0014] Inside the power unit room 20 are drive devices such as an engine and a motor (not shown). An electric fan 21 is provided on the front side of the drive device, and a radiator 22 is provided on the front side of the electric fan 21. A radiator support upper 24 is provided on the upper side of the radiator 22, and a radiator support lower (not shown) is provided on the lower side of the radiator 22. In other words, the radiator 22 is fixed by the radiator support upper 24 and the radiator support lower.

[0015] Furthermore, the radiator 22 is positioned behind the bumper reinforcement 16, and air guides 26 and 28 are provided between the radiator 22 and the bumper reinforcement 16. Outside air introduced through the opening 30A of the front grille 30, which will be described later, flows into the radiator 22 and the power unit room 20 through these air guides 26 and 28, and is designed to cool the radiator 22 and the drive unit installed in the power unit room 20.

[0016] As shown in Figures 1 to 3, a resin front grille 30 is provided at the lower part of the bumper cover 14 (below the absorber 18). The front grille 30 has a roughly rectangular outer frame 32 with the vehicle width direction as its longitudinal direction, and on the inner side of the outer frame, a plurality of rod-shaped members 34 extending in the vehicle width direction (with the vehicle width direction as its longitudinal direction) are provided at predetermined intervals in the vertical direction. The spaces between the outer frame 32 and the rod-shaped members 34, and between the rod-shaped members 34 themselves, form a plurality of openings 30A with the vehicle width direction as their longitudinal direction.

[0017] Each rod-shaped member 34 is formed in a roughly "U" shape, with the rear end being the open side when viewed in cross-section from the vehicle width direction. More specifically, each rod-shaped member 34 is formed in a roughly "U" shape, with the length of its upper part protruding to the rear longer than the length of its lower part protruding to the rear, and the rear end of its upper part is located further rear than the rear end of its lower part. In this embodiment, the roughly "U" shape also includes, for example, a roughly "V" shape.

[0018] As shown in Figures 2(A) and 2(B), inside each rod-shaped member 34, multiple partition walls 36 are integrally provided at predetermined intervals in the vehicle width direction, and when viewed from the vehicle width direction in a side view, they have substantially the same shape as the internal space of each rod-shaped member 34. In other words, the internal space of each rod-shaped member 34 is partitioned at predetermined intervals in the vehicle width direction by multiple partition walls 36. Furthermore, a slit portion 36A of a predetermined width is formed in the approximate center of each partition wall 36 in the vertical direction, extending in the front-rear direction and open on the rear side.

[0019] Also, as shown in Fig. 2(A), inside each rod-shaped member 34 and between the partition walls 36, a plurality of reflecting walls 38 configured to be able to reflect sound (sound waves) are integrally provided. As shown in Figs. 2(C) and 2(D), each reflecting wall 38 is formed in a symmetrical shape such that the central portion 38C in the longitudinal direction (vehicle width direction) between the partition walls 36 protrudes toward the rear side. More specifically, each reflecting wall 38 is formed in a symmetrical shape having a substantially arc-shaped inclined surface 38A in a plan view such that the amount of protrusion toward the rear side gradually increases from both longitudinal ends 38B on the partition wall 36 side toward the longitudinal central portion 38C thereof.

[0020] Next, the operation of the noise reduction structure 10 of the front grille 30 according to the present embodiment configured as described above will be described.

[0021] As described above, inside the inner side of the outer peripheral frame 32 of the front grille 30, a plurality of rod-shaped members 34 extending in the vehicle width direction and formed in a substantially "U" shape with the rear side being the open side in a cross-sectional view seen from the vehicle width direction are provided at predetermined intervals in the vertical direction. And inside each rod-shaped member 34, a plurality of partition walls 36 having a slit portion 36A extending in the front-rear direction at a substantially central portion in the vertical direction in a side view seen from the vehicle width direction and having the rear side open are provided at predetermined intervals in the vehicle width direction. Inside each rod-shaped member 34 and between the partition walls 36, a plurality of reflecting walls 38 for reflecting sound (sound waves) to the slit portion 36A are provided.

[0022] Therefore, as shown in Fig. 3, the sound (sound waves) generated in the power unit room 20 of the vehicle 12 (particularly by the electric fan 21) and incident inside the rod-shaped member 34 is reflected by the reflecting wall 38 to the slit portion 36A and passes through the slit portion 36A. Then, the sound (sound waves) passing through the slit portion 36A is transmitted to the internal space adjacent to the partition wall 36 having the slit portion 36A and interferes with the sound (sound waves with a phase difference) directly incident on the internal space and the sound (sound waves with a phase difference) reflected by the reflecting wall 38 in the internal space, and a part of those sounds is silenced.

[0023] In addition, the sound (sound wave) emitted from the internal space to the outside of the vehicle through the opening 30A of the front grille 30 interferes with the sound (sound wave with a phase difference) directly emitted from the opening 30A of the front grille 30 to the outside of the vehicle, and a part of these sounds is silenced. Thus, according to the noise reduction structure 10 according to the present embodiment, the noise leaking from the front grille 30 to the outside of the vehicle can be reduced by the interference of sound waves with a phase difference, and compared with the case where a sound absorbing material is provided, it is natural that the man-hours for attaching the sound absorbing material can be reduced, and an increase in the manufacturing cost can be suppressed.

[0024] In the noise reduction structure 10 according to the present embodiment, since it is only necessary to integrally form the partition wall 36 and the reflection wall 38 inside each rod-shaped member 34, the design property and the air permeability of the front grille 30 are not impaired. Further, since the shapes of the partition wall 36 and the reflection wall 38 are not complicated shapes having, for example, an undercut, the moldability when injection molding the front grille 30 is not impaired. Further, since the partition wall 36 and the reflection wall 38 can improve the rigidity of each rod-shaped member 34, as a result, the rigidity of the entire front grille 30 can be improved.

[0025] As described above, the noise reduction structure 10 of the front grille 30 according to the present embodiment has been described based on the drawings. However, the noise reduction structure 10 of the front grille 30 according to the present embodiment is not limited to the illustrated one, and can be appropriately designed and changed within a range not departing from the gist of the present invention.

[0026] For example, the interval between the partition walls 36, the width and length of the slit portion 36A, the inclination angle of the reflection wall 38, etc. can be appropriately designed and changed. Further, the noise reduction structure 10 according to the present embodiment can be applied to a rod-shaped member constituting a slit for introducing outside air in a cowl louver, and can also be applied to a rod-shaped member constituting a slit for ventilation to the passenger compartment provided in an interior trim, a deck side trim, or the like.

Explanation of Reference Numerals

[0027] 10. Noise Reduction Structure 30 Front Grille 32 Outer frame 34 Rod-shaped member 36 Partition Wall 36A Slit section 38 Reflection Wall

Claims

[Claim 1] It is formed in a roughly "U" shape, extending in the vehicle width direction and with the rear side of the vehicle being the open side when viewed in cross-section from the vehicle width direction, and consists of multiple rod-shaped members provided on the inner side of the outer frame of the front grille at predetermined intervals in the vehicle vertical direction, The rod-shaped member is provided with a plurality of partition walls at predetermined intervals in the vehicle width direction, which, when viewed from the vehicle width direction, extend in the vehicle front-rear direction and have slits that are open on the rear side of the vehicle, approximately in the center of the vehicle in the vertical direction. A plurality of reflective walls are provided inside the rod-shaped member and between the partition walls, which reflect sound to the slit portion, A noise-reducing structure for the front grille.

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