JP2021003974A - Skeleton member for vehicle - Google Patents

Abstract

To effectively reduce, in a skeleton member for a vehicle, the frequency of noise causing problems, by using an existing component without requiring additional components.SOLUTION: A skeleton member 1 for a vehicle comprises a front side member 12. The front side member 12 extends in a longitudinal direction, has a closed cross-sectional shape in a cross-section perpendicular to the longitudinal direction, and is closed at both ends in the longitudinal direction to define a capacity portion therein. The front side member 12 is provided with a duct-like hole 12b allowing communication between the capacity portion and outside. The capacity portion 12a and the hole portion 12b compose a Helmholtz resonator that reduces noise having a predetermined frequency.SELECTED DRAWING: Figure 2

Description

The present invention relates to a vehicle frame member.

While the automobile is running, a sound caused by cavity resonance between the tire and the road surface and a sound caused by the unevenness of the road surface are generated. This sound is called road noise or tire noise (hereinafter referred to as road noise). Road noise is radiated along the road and propagated into the vehicle interior via floor panels and dash panels. Road noise propagated into the passenger compartment may cause resonance in the passenger compartment space. The natural frequency of the sound wave that causes resonance in the passenger compartment space depends on the size and shape of the passenger compartment space, and is often 10 to 200 Hz in a general passenger car. Therefore, when the road noise in this frequency range propagates in the vehicle interior, it resonates and becomes unpleasant noise for the occupant. This noise is called muffled noise and is a problem in some automobiles.

Patent Document 1 discloses a sound absorbing structure that reduces noise by using a sound absorbing material in a fender protector installed in a wheel house of a vehicle.

JP-A-2010-6312

The sound absorbing structure of Patent Document 1 requires additional parts such as a sound absorbing material. Further, since the frequency that can be absorbed by the sound absorbing material is generally limited to 1 kHz or more, it is not possible to effectively reduce the noise of 10 to 200 Hz, which is a problem in general passenger automobiles.

An object of the present invention is to effectively reduce a problematic noise frequency by utilizing an existing component in a vehicle skeleton member without requiring an additional component.

The present invention includes a hollow member that extends in the longitudinal direction and has a closed cross-sectional shape in a cross section perpendicular to the longitudinal direction, both ends of the longitudinal direction are closed, and a volume portion is defined therein. A vehicle skeleton member including a duct-shaped hole portion that communicates the volume portion and the outside of the hollow member, and the volume portion and the hole portion constitute a Helmholtz resonator that reduces noise at a predetermined frequency. Provides a vehicle skeleton member.

According to this configuration, a part of the vehicle skeleton member is configured as a Helmholtz resonator. Therefore, noise can be effectively reduced at the resonance frequency (predetermined frequency) of the Helmholtz resonator by utilizing existing components without requiring additional components.

The predetermined frequency of the Helmholtz resonator may be 10 Hz or more and 200 Hz or less.

According to this configuration, in the Helmholtz resonator, the size of the volume portion and the hole portion is appropriately set, and the resonance frequency (predetermined frequency) is set to 10 Hz or more and 200 Hz or less, which causes a problem in a general passenger vehicle. The noise of ~ 200Hz can be effectively reduced.

A sound absorbing material may be attached to the inner surface of the hollow member constituting the volume portion.

According to this configuration, by using the sound absorbing material, it is possible to enhance the noise reduction effect such as the frequency before and after the resonance frequency and the frequency away from the resonance frequency. In particular, when a fiber-based sound absorbing material is used, noise at a high frequency of 1 kHz or higher can be effectively reduced.

A filter that prevents liquid from entering the volume portion from the outside may be attached to the hole portion.

According to this configuration, the filter can prevent the liquid from entering the volume portion. If the filter is not attached to the hole, the liquid or mud collected on the road surface may repel and enter the volume through the hole. Further, once liquid or mud has penetrated into the volume portion, it is difficult to clean the volume portion. Therefore, the filter structure is useful because the labor of such cleaning can be saved.

The hole may be cylindrical.

According to this configuration, the cylindrical hole portion is easy to design and process, so that a Helmholtz resonator can be formed with a simple configuration.

A partition wall for partitioning the volume portion may be further provided inside the hollow member, and the hole portion may be provided for each volume portion partitioned by the partition wall.

According to this configuration, a plurality of Helmholtz resonators can be configured. For example, by making the resonance frequency of each Helmholtz resonator different, it is possible to set a plurality of frequencies for reducing noise. Therefore, noise of various frequencies can be reduced, and noise reduction performance can be improved. Further, by making the resonance frequencies of two or more Helmholtz resonators the same, it is possible to greatly reduce the noise at the frequencies.

The hollow member may be a front side member of the vehicle. Further, the hollow member may be a rear side member of the vehicle. The hollow member may be a rocker member of a vehicle.

According to these configurations, the front side member, the rear side member, or the rocker member can be provided with noise reduction performance. In these, since the hollow member is often provided as an existing structure, the noise reduction structure can be configured by utilizing the existing structure.

According to the present invention, since a part of the skeleton member for a vehicle is configured as a Helmholtz resonator, the frequency of noise that becomes a problem can be effectively reduced by using an existing component without requiring an additional component. ..

The perspective view of the skeleton member for a vehicle which concerns on one Embodiment of this invention. A perspective view showing a front side member. The perspective view which shows the modification of the front side member.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The vehicle skeleton member 1 of the present embodiment shown in FIG. 1 has a function of reducing road noise and muffled noise by utilizing the principle of the Helmholtz resonator. The vehicle skeleton member 1 of the present embodiment is that of a passenger vehicle of a general size.

The vehicle skeleton member 1 includes a front portion 10 in front of the vehicle, a vehicle interior portion 20 in the center of the vehicle, and a rear portion 30 in the rear of the vehicle. In the present embodiment, the front portion 10 is provided with a structure for reducing noise. Therefore, detailed description of the vehicle interior portion 20 and the rear portion 30 will be omitted.

The front portion 10 is provided adjacent to the vehicle interior portion 20 and is a portion in which mechanical elements such as an engine are housed. The front portion 10 is provided with bumpers 11 extending in the vehicle width direction (X direction in FIG. 1) at the lower front portion of the vehicle, and front and rear of the vehicle so as to connect both ends of the bumper 11 in the vehicle width direction and the vehicle interior portion 20. Two front side members (hollow members) 12 extending in a direction (Y direction in FIG. 1) are provided. Further, an upper core support 13 extending in the vehicle width direction is provided in the upper part of the front of the vehicle, and two uppers extending in the vehicle front-rear direction so as to connect both ends of the upper core support 13 in the vehicle width direction and the vehicle interior portion 20. A side support 14 is provided. In FIG. 1, the vehicle height direction is shown as the Z direction.

The front side member 12 has a longitudinal direction in the front-rear direction of the vehicle, and a cross section perpendicular to the longitudinal direction is a rectangular closed cross section. In the longitudinal direction, both ends of the front side member 12 are closed. Specifically, the front end of the front side member 12 is closed by a plate material. The rear end of the front side member 12 is closed by a vehicle body plate 21 constituting the vehicle interior portion 20. However, the mode of the closed structure at both ends of the front side member 12 in the vehicle front-rear direction is not particularly limited.

With reference to FIG. 2, the front side member 12 defines a rectangular parallelepiped volume portion 12a inside. No component is arranged in the volume portion 12a, and the volume portion 12a exists as a space. The size of the volume portion 12a can be suitably set according to the frequency of the noise to be reduced, as will be described later. The size of the volume portion 12a may be a size capable of effectively reducing noise of, for example, 10 to 200 Hz. Further, the shape of the volume portion 12a is not limited to the rectangular parallelepiped shape, and may be any shape.

The front side member 12 is provided with a duct-shaped hole portion 12b that communicates the volume portion 12a with the outside. In the present embodiment, the hole portion 12b has a cylindrical duct shape. Each dimension of the hole 12b can be suitably set according to the frequency of the noise to be reduced, as will be described later. Each dimension of the hole 12b may be such that noise of, for example, 10 to 200 Hz can be effectively reduced. Further, the position of the hole portion 12b can be arbitrarily set. For example, the hole portion 12b may be provided on the inner surface of the front side member 12 in the vehicle width direction so as to face the engine that can be a noise source.

A filter 15 for preventing liquid from entering the volume portion 12a from the outside is attached to the hole portion 12b. As the filter 15, for example, a PVD (Physical Vapor Deposition) film can be used. The PVD film is a film that allows sound to pass through but does not allow liquid to pass through.

In this embodiment, a Helmholtz resonator that reduces noise at a predetermined frequency is configured by a volume portion 12a and a hole portion 12b. In the Helmholtz resonator, in a structure having a volume portion 12a (see broken line) and a hole portion 12b as shown in FIG. 2, the flow path cross-sectional area S of the hole portion 12b, the length L of the hole portion 12b, and the volume of the volume portion 12a When defined as V and the speed of sound c, the characteristic of mainly absorbing the sound of the frequency f represented by the following equation is exhibited. At this time, the frequency f of the sound mainly absorbed is also referred to as a resonance frequency.

For example, in the present embodiment, the length of the volume portion 12a in the vehicle body front-rear direction is set to 580 mm, the length in the vehicle width direction is set to 76 mm, the length in the vehicle height direction is set to 140 mm, and the diameter of the hole portion 12b is set to 10 mm and the length (plate). Thickness) is set to 2 mm. When the resonance frequency is calculated from the above formula based on this exemplary dimension, the resonance frequency is about 137 Hz. Further, under the same conditions, if the diameter of the hole 12b is 5 mm, the resonance frequency is about 68 Hz, and if the diameter of the hole 12b is 1 mm, the resonance frequency is about 14 Hz. As described above, it is preferable to set the resonance frequency (predetermined frequency) of the Helmholtz resonator to 10 Hz or more and 200 Hz or less. As a result, noise having a frequency of 10 to 200 Hz, which is a problem in general passenger automobiles, can be effectively reduced.

Further, a sound absorbing material 16 is attached to the inner surface of the front side member 12 constituting the volume portion 12a. In FIG. 2, the sound absorbing material 16 is virtually taken out and shown in a shaded line in a broken line circle. The sound absorbing material 16 may be, for example, a non-woven fabric formed in a mesh shape by a plurality of fibers, a porous urethane sponge, or the like. In the present embodiment, the sound absorbing material 16 is attached to the entire surface of the inner surface. However, the method of attaching the sound absorbing material 16 is not particularly limited, and for example, the sound absorbing material 16 may be attached only to the surface facing the hole 12b.

According to the front side member 12, which is the vehicle skeleton member 1 of the present embodiment, the following effects can be obtained.

A part of the vehicle frame member 1 is configured as a Helmholtz resonator. Therefore, noise can be effectively reduced at the resonance frequency of the Helmholtz resonator using existing components without the need for additional components.

By appropriately setting the sizes of the volume portion 12a and the hole portion 12b in the Helmholtz resonator and setting the resonance frequency to 10 Hz or more and 200 Hz or less, the noise of 10 to 200 Hz, which is a problem in general passenger automobiles, can be effectively reduced. Can be reduced.

Since the sound absorbing material 16 is used in the volume portion 12a, it is possible to enhance the noise reduction effect of frequencies before and after the resonance frequency and frequencies away from the resonance frequency. In particular, when a fiber-based sound absorbing material is used as in the present embodiment, noise at a high frequency of 1 kHz or higher can be effectively reduced.

Since the filter 15 is attached to the hole portion 12b, it is possible to prevent the liquid from entering the volume portion 12a. If the filter 15 is not attached to the hole 12b, the liquid or mud collected on the road surface may repel and enter the volume 12a from the hole 12b. Further, once liquid, mud, or the like has penetrated into the volume portion 12a, it is difficult to clean the volume portion 12a. Therefore, the filter structure is useful because the labor of such cleaning can be saved.

Since the hole portion 12b is formed in a cylindrical shape, the hole portion 12b can be easily designed and processed, and a Helmholtz resonator can be formed with a simple configuration.

A Helmholtz resonator is configured for the front side member 12 to have noise reduction performance. Since the front side member 12 is generally provided as an existing vehicle structural member, the noise reduction structure can be configured by utilizing the existing structure.

(Modification example)
FIG. 3 shows a modified example of the front side member 12 of the above embodiment.

In this modification, a plurality of Helmholtz resonators are provided for one front side member 12. Specifically, the inside of the front side member 12 is partitioned by a partition wall 12c, and a plurality of volume portions 12a are provided. Further, a hole portion 12b is provided for each volume portion 12a.

In the example of FIG. 3, the inside of the front side member 12 is partitioned by two partition walls 12c, and three same Helmholtz resonators are provided. That is, three volume portions 12a having the same size and three hole portions 12b having the same size are provided. As a result, noise at a frequency set as a resonance frequency can be greatly reduced.

Alternatively, multiple Helmholtz resonators may be different from each other. For example, the resonance frequency may be set differently for each Helmholtz resonator by changing the dimensions of the volume portion 12a or the hole portion 12b. For example, in the volume portion 12a, the length in the vehicle body front-rear direction is set to 580 mm, the length in the vehicle width direction is set to 76 mm, and the length in the vehicle height direction is set to 140 mm, and in the hole portion 12b, the diameter is set to 5 mm and the length (plate thickness) is set. Set to 2 mm. When the resonance frequency is calculated based on this exemplary dimension, the resonance frequency is about 68 Hz. Further, by providing the partition wall 12c under the above conditions, the resonance frequency becomes about 97 Hz when the vehicle body front-rear direction length is 290 mm, and the resonance frequency becomes 134 Hz when the vehicle body front-rear direction length is 150 mm. By setting various resonance frequencies in this way, noise at various frequencies can be reduced and noise reduction performance can be improved.

Although specific embodiments of the present invention and variations thereof have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, the target member constituting the Helmholtz resonator is not limited to the front side member 12. Alternatively, a rear side member, a rocker side member 22 (see FIG. 1), and the like can form a Helmholtz resonator as a hollow member of the present invention. Even in these cases, since the rear side member and the rocker side member 22 are generally provided as existing vehicle structural members, the noise reduction structure can be configured by utilizing the existing structure.

1 Vehicle skeleton member 10 Front part 11 Bumper 12 Front side member (hollow member)
12a Volume 12b Hole 12c Partition wall 13 Upper core support 14 Upper side support 15 Filter 16 Sound absorbing material 20 Vehicle interior 21 Body plate 22 Rocker side member (hollow member)
30 rear part

Claims (9)

A hollow member that extends in the longitudinal direction, has a closed cross-sectional shape in a cross section perpendicular to the longitudinal direction, has both ends in the longitudinal direction closed, and defines a volume portion inside.
A vehicle skeleton member having a duct-shaped hole portion that communicates the volume portion and the outside of the hollow member.
A vehicle skeleton member in which a Helmholtz resonator that reduces noise at a predetermined frequency is configured by the volume portion and the hole portion. The vehicle skeleton member according to claim 1, wherein the predetermined frequency of the Helmholtz resonator is 10 Hz or more and 200 Hz or less. The vehicle skeleton member according to claim 1 or 2, wherein a sound absorbing material is attached to the inner surface of the hollow member constituting the volume portion. The vehicle skeleton member according to any one of claims 1 to 3, wherein a filter for preventing liquid from entering the volume portion from the outside is attached to the hole portion. The vehicle skeleton member according to any one of claims 1 to 4, wherein the hole is cylindrical. A partition wall for partitioning the volume portion into a plurality of parts is further provided inside the hollow member.
The vehicle skeleton member according to any one of claims 1 to 5, wherein the hole portion is provided for each volume portion partitioned by the partition wall. The vehicle skeleton member according to any one of claims 1 to 6, wherein the hollow member is a front side member of the vehicle. The vehicle skeleton member according to any one of claims 1 to 6, wherein the hollow member is a rear side member of the vehicle. The vehicle skeleton member according to any one of claims 1 to 6, wherein the hollow member is a rocker member of a vehicle.

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