JP2001270470A - Panel structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a panel structure allowing easy adjustments of a natural mode frequency with high radiation efficiency. SOLUTION: A panel 6 surrounded by side members 3, side sills 4, a second cross member 1 and a third cross member 2 is provided with flat edges 10 extending from the sides of the panel for connection with the side members 3 and with the side sills 4 to the center of the panel 6, those sides serving as long sides. The remainder 11 of the panel is formed into one continuously curved and projecting surface configuration showing the natural vibration mode configuration of the (1, 1) mode of a flat plate as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a panel structure such as a vehicle panel such as a floor panel, a roof panel, and a dash panel, which can reduce noise.

[0002]

2. Description of the Related Art Conventionally, as a panel structure for reducing the radiated sound of a panel, for example, there is a panel structure disclosed in Japanese Patent Application Laid-Open No. 9-202269. In one embodiment of this publication, for example, a part of a floor panel is formed in a curved shape so as to exhibit a natural vibration mode shape of a (2, 2) mode of a flat plate which is a vibration mode with low radiation efficiency. It is described that the noise in the interior of the vehicle is reduced by reducing the radiation efficiency of the panel by bringing the mode closer to a high frequency of the noise level in the interior of the vehicle. Alternatively, in order to keep the frequency of the high radiation efficiency vibration mode away from the target frequency at which the set radiation noise is to be reduced, in one embodiment, the panel has a vertical bead or rib formed on the panel. Add lateral beads or ribs along the center line to shift the high radiation efficiency (1,1) mode to lower frequency and at the same time annihilate the high radiation efficiency (3,1) mode. Have been. In this embodiment, the (1,1) mode, which was at 160 Hz before the bead or the rib was added, is shifted to 50 Hz by adding the bead or the rib, and the frequency rapidly changes. .

[0003]

However, as described in the above publication, the flat plate is formed into a curved surface shape exhibiting the natural vibration mode shape of the (2, 2) mode, which is a vibration mode with low radiation efficiency, and the radiation efficiency is reduced. By simply bringing the (2, 2) mode having a low noise level closer to the frequency at which the noise level in the vehicle compartment is high, noise reduction in the vehicle interior cannot always be realized by the natural frequency of the mode having high radiation efficiency. The mode with high radiation efficiency does not necessarily reduce the noise in the cabin even if it is away from the high frequency of the noise level. Will be lost. Also, by adding beads and ribs, 50 (1, 1) modes with high radiation efficiency can be added.
However, since the suspension resonance mode exists at 50 Hz (especially in FR vehicles), it is not preferable that the (1, 1) mode be 50 Hz. However, it is basically difficult to finely adjust the frequency in the method disclosed in the above publication in which beads or ribs are added. In addition, variations in bead and rib press working affect the frequency,
Further, the adjustment is difficult.

Further, a vibration damping material is usually attached to the panel to suppress vibration. However, when a bead or a rib is formed, the vibration damping material cannot be attached to the panel in close contact. However, there is also a problem that the effect of the vibration damping material cannot be sufficiently exerted.

The present invention has been made in view of the above problems, and has as its object to provide a panel structure that can easily adjust the frequency of a natural mode having high radiation efficiency.

[0006]

According to a first aspect of the present invention, there is provided a panel structure having a substantially rectangular shape in an environment in which a vibration mode is excited and whose periphery is restricted. A flat edge is provided from at least one non-short side toward the center of the panel, and at least one or more continuously curved concave shapes or at least one of the remaining portions of the panel other than the edge are provided. It is characterized in that the above-mentioned continuously curved convex shape is formed. Providing a flat edge and forming at least one or more continuously curved concave shapes or at least one or more continuously curved convex shapes on the remaining portion of the panel other than the edge, Compared with the case where the whole is formed in a concave shape or a convex shape, the frequency of the higher-order natural mode can be increased without increasing the frequency of the (1, 1) mode.
Therefore, the frequency of the (1,1) mode with high radiation efficiency is
By adjusting the continuously curved concave shape or the continuously curved convex shape to be formed on the remaining portion of the panel other than the edge while adjusting to the optimum frequency without the acoustic resonance mode, The frequency of another higher-order eigenmode can be increased to shift from the frequency range in which noise is to be reduced.

According to a second aspect of the present invention, the width of the flat edge portion according to the first aspect is the length of a side adjacent to the side from the side other than the short side of the panel toward the center of the panel. It is characterized in that the length is not less than 1/6 of the dimension and less than 3/6, and the length is not the short side.

According to a third aspect of the present invention, the width of the flat edge portion according to the first aspect changes along a side other than the short side.

According to a fourth aspect of the present invention, the width of the flat edge in the third aspect is larger than the average value of the width of the flat edge at the center in the length direction of the side other than the short side. It is characterized by being set large.

According to a fifth aspect of the present invention, the width of the flat edge in the third aspect is larger than the average value of the width of the flat edge at the center in the length direction of the side other than the short side. It is characterized by being set small.

The invention according to claim 6 is the invention according to claims 3 to 5
The maximum value of the width of the flat edge described above is not less than 1/6 of the length of a side adjacent to the side other than the short side of the panel.

The invention according to claim 7 provides the invention according to claims 1 to 6
Wherein the remaining portion is formed into a curved shape so as to exhibit a natural vibration mode shape of a (1,3) mode or a (3,1) mode of a flat plate substantially as a whole. I do.

The invention according to claim 8 is the first to sixth aspects.
The remaining portion described in any one of the above is formed in a curved surface shape so as to exhibit a natural vibration mode shape of a (1,2) mode or a (2,1) mode of a flat plate substantially as a whole. I do.

The panel structure according to the ninth aspect of the present invention is
In a substantially rectangular panel which is in an environment where a vibration mode is excited and whose surroundings are restrained to some extent, all or at least a part of the panel is entirely (1,
3) It is characterized by forming a smooth uneven curved surface shape having a natural vibration mode shape of mode or (3, 1) mode.

According to a tenth aspect of the present invention, the panel according to any one of the first to ninth aspects is a vehicle configuration panel.

According to an eleventh aspect of the present invention, in the vehicle configuration panel according to the tenth aspect, one side extending in the vehicle longitudinal direction is connected to a side sill or a side member, and the other side extending in the vehicle longitudinal direction is a side member. Connected to the junction of the tunnel member or tunnel vertical wall and floor panel,
The side extending in the vehicle left-right direction is a part of the floor panel connected to the floor cross member.

[0017]

According to the first aspect of the present invention, higher-order eigenmodes other than the (1,1) mode can be used without greatly changing the frequency of the (1,1) mode having high radiation efficiency.
The frequency can be shifted from the frequency range in which noise is to be reduced, and the adjustment can be easily performed.

Further, since a continuously curved concave shape or a continuously curved convex shape is formed on the remaining portion of the panel other than the edge portion, even when the vibration damping material is used, the vibration damping material can be closely adhered. Can be attached to the panel, and the effect of the vibration damping material can be fully exhibited.

Further, the shape of the remaining portion of the panel other than the edge portion has a small effect on the natural frequency of the (1,1) mode having high radiation efficiency, and has a continuously curved concave shape or continuous shape. Since it has a convex shape with a curved shape, strict accuracy is not required for processing accuracy of the panel, and manufacturing can be easily performed.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the dimension of the flat edge portion is not less than 1/6 of the length dimension of the side adjacent to the side other than the short side, and By setting it to less than ３, the natural frequency of the (1, 1) mode can be sufficiently suppressed. Further, the influence of the shape of the remaining portion of the panel other than the edge on the natural frequency of the (1, 1) mode can be reduced.

According to the third aspect of the present invention, in addition to the effect of the first aspect, the natural frequency of the (1, 1) mode having high radiation efficiency is adjusted to the optimum frequency depending on the panel. In such a case, by changing the width of the flat edge, the frequency of the (1, 1) mode can be changed, and the adjustment can be performed. In this manner, only the (1, 1) mode can be efficiently adjusted to a frequency that does not cause a problem, so that the panel noise can be reduced.

According to the fourth aspect of the invention, in addition to the effect of the third aspect, the width of the flat edge is set to be larger than the average value at the center in the length direction of the side other than the short side. Thereby, the natural frequency of the (1, 1) mode can be efficiently reduced.

According to the fifth aspect of the invention, in addition to the effect of the third aspect, the width of the flat edge is set to be smaller than the average value at the center in the length direction of the side other than the short side. Thereby, the natural frequency of the (1, 1) mode can be efficiently increased.

According to the sixth aspect of the present invention, the maximum dimension of the flat edge is set to 1/6 or more of the length of the side adjacent to the side other than the short side, whereby (1, 1) 1) The natural frequency of the mode can be reliably reduced.

According to the seventh aspect of the present invention, in addition to the effects according to any one of the first to sixth aspects, in addition to the eigenmode having a high radiation efficiency, particularly the (1,3) mode or the (3,1) mode. The natural frequency can be increased. In this manner, the (1,3) mode or the (3,1) mode having high radiation efficiency can be shifted from the frequency range in which the noise is to be reduced, and the noise of the panel can be reduced.

According to the eighth aspect of the invention, in addition to the effect according to any one of the first to sixth aspects, the natural frequency of the (1,2) mode or the (2,1) mode can be increased. Become like When the noise level is high in the (1,2) mode or the (2,1) mode of the panel, the (1,2) mode or the (2,1) mode is shifted from the frequency range in which the noise is to be reduced. Panel noise can be reduced.

According to the ninth aspect of the present invention, the eigenmode having high radiation efficiency, in particular, the (1,3) mode or the (3,3) mode.
1) The natural frequency of the mode can be increased. In this manner, the (1,3) mode or the (3,1) mode having high radiation efficiency can be shifted from the frequency range in which the noise is to be reduced, and the noise of the panel can be reduced. By forming a concave and convex curved surface shape without forming a bead or a rib, noise can be reduced, so that adjustment and manufacturing thereof can be easily performed. Also, by forming a smooth uneven shape on the panel, even when using a damping material, the damping material can be attached to the panel in close contact, and the effect of the damping material can be fully exhibited. Can be.

According to the tenth aspect, the first aspect is
In addition to the effects according to any one of (9) to (9), by applying the panel of the present invention to a vehicle configuration panel, it is possible to reduce noise in the vehicle interior.

According to the eleventh aspect of the present invention, the first aspect
In addition to the effect according to 0, by applying the panel of the present invention to a floor panel that is easily affected by road noise, it is possible to effectively reduce the noise in the vehicle interior.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1B is a view showing a first embodiment of the present invention, in which a floor is viewed obliquely from above, and mainly shows a floor portion. And interior parts such as floor carpets are omitted.

First, the configuration will be described. Normally, the floor structure of an automobile is constituted by a floor panel 7 and members running in front, rear, left and right of the vehicle as shown in FIG. That is, in the present embodiment, the side members 3 and the side sills 4 are arranged in the vehicle front-rear direction, the second cross member 1 and the third cross member 2 are arranged in the vehicle left-right direction, and the tunnel length is arranged in the vehicle center part front-rear direction. The wall 8 and the tunnel member 5 are arranged. Floor panel 7
Has a plurality of portions 6 surrounded by the plurality of members. Hereinafter, the substantially rectangular portion surrounded by the members of the floor panel 7 and whose periphery is restricted to some extent is simply referred to as the panel 6. If the panel 6 surrounded by the side member 3, the side sill 4, the second cross member 1, and the third cross member 2 shown in FIG. 1A is taken as an example, the panel 6 has side members each having a long side. A flat edge 10 having a width of about 1/4 of the short side dimension is provided from the entire side connected to 3 and the entire side connected to the side sill 4 toward the center of the panel 6, and the remaining portion 11 is formed. Substantially as a whole, it is formed into one smooth convex curved surface shape exhibiting a (1,1) mode natural vibration mode shape of a flat plate. In addition, the side member 3, the side sill 4, the second cross member 1, and the third cross member 2
The panel 6 surrounded by other members such as the tunnel member 5, the sheet cross member 9 and the tunnel vertical wall 8 is not limited to the panel 6 surrounded by
And the remaining part 11 can be provided.

Next, the operation of the first embodiment will be described.

The vibration excited by the unevenness of the road surface or the engine vibration causes the panel 6 to vibrate through the vibration of the member which is the body frame system. The panel 6 radiates noise into the room by vibrating, but the easiness of the sound largely depends not only on the level of the vibration level but also on the shape of the vibration mode of the panel 6. In the frequency range of the road noise considered here, usually (1, 1), (1, 3), (3,
1) Large mode radiation efficiency. In particular, the (1,1) mode has a high radiation efficiency and needs to be kept away from the road noise region.
1) It is necessary to reduce the noise in the road noise region (that is, about 200 Hz to about 500 Hz) by utilizing the interaction between the anti-vibration effect that appears on the natural frequency of the mode and the mode that produces the next sound. is there. Therefore, the natural frequency of the (1, 1) mode is in a road noise region (that is, about 200H).
The frequency should be set at a frequency slightly lower than about 500 Hz (from z) and slightly higher in radiation efficiency, but less influencing the noise in the vehicle compartment, for example, about 100 Hz or 150 Hz. In this embodiment, by providing a flat edge 10 and further setting the width of the edge 10 to an appropriate width,
By setting the (1,1) mode at a frequency lower than such a road noise region and having a small influence on noise, and by setting the remaining portion 11 to the natural vibration mode shape of the (1,1) mode, By increasing the surface rigidity of the panel 6, the natural frequency of the higher-order mode is shifted upward from the road noise area, and the vibration-damping effect that appears on the (1,1) mode and appears next in the road noise area. Noise is reduced by interaction with the mode.

FIG. 2 shows a panel 6 of the present embodiment and a curved surface shape such that the panel as a whole exhibits a (1,1) mode natural vibration mode shape in order to explain the effect of the present embodiment. Panel (called a comparison panel)
The result of calculating the frequency dependence of the radiation efficiency is shown. In the drawing, P11 and P12 represent the peak frequencies of the (1,1) mode of the present embodiment and the comparative example, respectively.
3 and P14 represent the respective (3, 1) modes of the present embodiment and the comparative example. In the graph of FIG. 2, the radiation efficiency is obtained by making the volume change generated by the panel 6 in response to the vibration of the member surrounding the panel 6 non-dimensional by the volume change when the panel 6 is completely rigid. The efficiency of 0 dB indicates that the same volume velocity as that of the vibration of the member surrounding the panel 6 is generated, and that the sound is generated at the radiation efficiency of 0 dB or more. Further, the dimensions of the panel 6 in the calculation are set to 0.35 m on the long side and 0.25 m on the short side in accordance with the typical size of the panel around this. (1,1)
When the natural frequencies of the modes are the same (150 Hz),
It can be seen that the peak of the radiation efficiency in the road noise region is smaller in the present embodiment, and is effective for noise reduction. Stated another way, in the comparison panel, only the higher-order mode cannot be increased, and if the overall curvature is increased, the natural frequencies of all modes including the (1, 1) mode increase. However, in this embodiment, since the flat edge portion 10 is provided, by adjusting the curvature of the curved shape of the remaining portion 11 without increasing the natural frequency of the (1, 1) mode, Only higher modes can be raised.

The width of each flat edge 10 is preferably not less than 1/6 and less than 3/6 of the short side, and the length is preferably set to be equal to the long side, whereby (1,1) The natural frequency of the mode can be reliably kept low. Further, in this embodiment, since the curved shape formed on the remaining portion 11 is a smooth convex shape, when the damping material is used, the damping material can be attached to the panel 6 in close contact with the damping material. The effect of the material can be sufficiently exhibited, and the panel 6 can be easily manufactured.

(Second Embodiment) FIG. 3 (b) is a diagram showing a floor according to a second embodiment of the present invention viewed obliquely from above, and mainly shows the floor portion. Interior parts such as seats and floor carpets are omitted, and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 3A, the panel 6-2 of the present embodiment surrounded by the side member 3, the side sill 4, the second cross member 1, and the third cross member 2.
The panel 6-6 includes the entire side connected to the side member 3 which is a long side and the entire side connected to the side sill 4.
2, flat edges 10-2 each having a width of about 1/4 of the short side dimension are provided. Rest 11
In the present embodiment, the ratio of the long side direction to the short side direction is about 3: 1, and almost the entire surface has a smooth (2, 1) mode natural vibration mode shape. It is formed in a curved shape in which two concave shapes and one convex shape are alternately connected. In addition, the side member 3, the side sill 4, the second cross member 1, and the third cross member 2
The panel 6-2 surrounded by other members, such as the tunnel member 5, the seat cross member 9, and the tunnel vertical wall portion 8, is not limited to the panel 6-2 surrounded by. -2 and the remaining portion 11-2.

Next, the operation of the second embodiment will be described.

In panel 6-2, the (3, 1) mode has the second highest radiation efficiency after the (1, 1) mode. In the present embodiment, the central portion of the panel 6-2 has the (3, 1) mode shape as a whole,
The natural frequency of the (3, 1) mode can be increased, and the number of modes that produce sounds in the road noise range can be further reduced as compared with the first embodiment. As a result, noise can be further reduced. become. Further, by adjusting the width of the flat edge portion 10-2, it is not only easy to adjust the natural frequency of the (1, 1) mode, but also in this embodiment, the panel 6-2 Even if the height of the curved surface irregularities of the remaining portion 11-2 is changed, the natural frequency of the (1,1) mode is hardly changed, and the characteristic that the radiation efficiency can be stably reduced is obtained. Have.

FIG. 4 shows the result of calculating the frequency dependence of the radiation efficiency in order to explain the effect of this embodiment. In the drawing, P21 and P22 represent the peak frequencies of the respective (1,1) modes when the maximum height of the concavo-convex shape of the remaining portion 11 is 0.01 m and 0.02 m.
3 and P24 represent the respective (3,1) modes when the maximum height of the uneven shape is 0.01 m and 0.02 m. The (1,1) mode is the same as that of the first embodiment, but it can be seen that a peak with high radiation efficiency can be eliminated in the road noise region. Also the rest 1
0.02m when the maximum height of 1-2 is 0.01m
In this case, it can be seen that the natural frequency of the (1, 1) mode hardly changes, and a low radiation efficiency characteristic can be stably realized even if the shape slightly changes.

When the maximum height of the unevenness of the remaining portion 11-2 of the panel 6-2 is 0.01 m and 0.02 m, the difference between the natural frequencies in the (1,1) mode is determined by the flat edge. 10
FIG. 5 shows the result of calculation by changing the width of -2. When the width dimension of each flat edge 10-2 is 1/6 or more of the short side dimension, the difference in the natural frequency due to the height of the unevenness hardly changes, whereas when the width dimension is smaller than 1/6. It can be seen that the difference in the natural frequency due to the height of the unevenness sharply increases. The dimensions of the panel and the dimensions of the flat edge in the calculation are the same as those in the first embodiment.

Also in this embodiment, each flat edge 10
It is preferable that the width dimension of −2 is not less than １ ／ and less than ／ of the short side dimension, and the length dimension is set to be equal to the long side dimension, thereby ensuring the natural frequency of the (1,1) mode. In the present embodiment, as described above, the width of each flat edge portion 10-2 is set to 1/6 or more of the short side dimension, so that the remaining portion 11
-2, the influence of the curved surface shape on the natural frequency of the (1,1) mode can be reduced. Therefore,
It is easy to adjust the natural frequency of the higher mode,
Since strict accuracy is not required for the processing accuracy of the panel, manufacturing can be easily performed.

Also in this embodiment, since the curved surface formed in the remaining portion 11-2 is a smooth uneven shape, when the damping material is used, the damping material is adhered to the panel 6-2. It can be attached, and the effect of the damping material can be sufficiently exhibited.

In this embodiment, the flat edge 10-2 is provided so that the (1, 1) mode is suppressed to be lower than the road noise region. If the (1,1) mode can be suppressed sufficiently low, the flat edge 10-2 is omitted, and almost the entire panel 6 is entirely made of a flat (3,1) mode or (3,1) mode. It may be formed in a curved shape exhibiting a natural vibration mode shape. Thus, (3,
Increase the frequency of 1) mode or (1, 3) mode,
It can be shifted from the road noise area.

(Third Embodiment) FIG. 6B is a diagram showing a floor according to a third embodiment of the present invention viewed obliquely from above, and mainly shows the floor portion. Interior parts such as seats and floor carpets are omitted, and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 6A, the panel 6-3 of the present embodiment surrounded by the side member 3, the side sill 4, the second cross member 1, and the third cross member 2.
The panel 6-6 includes the entire side connected to the side member 3 which is a long side and the entire side connected to the side sill 4.
3 are provided with flat edges 10-3 each having a width of about 1/4 of the short side dimension toward the center of each. Rest 11
In the present embodiment, the ratio of the long side direction to the short side direction is about 2: 1, and a smooth -1 indicates a natural vibration mode shape of a (2, 1) mode of a flat plate as a whole as a whole. It is formed in a curved surface shape in which one concave shape and one convex shape continue. In addition, not only the panel 6-3 surrounded by the side member 3, the side sill 4, the second cross member 1, and the third cross member 2, but also other members such as the tunnel member 5, the seat cross member 9, the tunnel vertical wall portion 8, and the like. Likewise, the panel 6-3 surrounded by the flat edge 10
-3 and the remaining portion 11-3.

Next, the operation of the third embodiment will be described.

The vehicle interior 12 at the frequency of the road noise
Although the mode shape of the resonance mode is not so complicated, the panel 6-3 of a part of the floor panel may be located on the nodal line N of the resonance mode as shown in FIG. In this case, the radiation efficiency of the (2, 1) mode, which is a mode in which normal sound is difficult to emit, increases, and as a result, the noise level in the vehicle interior 12 increases. In this embodiment,
The remaining portion 11-3 of panel 6-3 is referred to as (2,
Since the natural vibration mode shape of the 1) mode is exhibited, the natural frequency of the (2, 1) mode can be shifted to a high level and kept away from the road noise region.

Also in this embodiment, each flat edge 10
It is preferable that the width dimension of −3 is set to 1/6 or more and less than 3/6 of the short side dimension, and the length dimension is set to be equal to the long side dimension, thereby ensuring the natural frequency of the (1,1) mode. In the present embodiment, as described above, the width of each flat edge portion 10-3 is set to 1/6 or more of the short side dimension, so that the remaining portion 11
The influence of the curved surface shape formed in the −3 on the natural frequency of the (1, 1) mode can be reduced. Therefore,
It is easy to adjust the natural frequency of the higher mode,
Since strict accuracy is not required for the processing accuracy of the panel, manufacturing can be easily performed.

Also in this embodiment, since the curved shape formed in the remaining portion 11-3 is a smooth uneven shape, when the damping material is used, the damping material is closely attached to the panel 6-3. It can be attached, and the effect of the damping material can be sufficiently exhibited.

(Fourth Embodiment) FIG. 8B is a diagram showing a floor according to a fourth embodiment of the present invention as viewed obliquely from above, and mainly shows the floor portion. Interior parts such as seats and floor carpets are omitted, and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 8A, the panel 6-4 of the present embodiment surrounded by the side member 3, the side sill 4, the second cross member 1, and the third cross member 2.
The panel 6-6 includes the entire side connected to the side member 3 which is a long side and the entire side connected to the side sill 4.
4, flat edges 10-4 are provided. The width of each flat edge 10-4 is not constant, but varies along the long side, and is maximum at the center in the longitudinal direction of the long side, and the maximum width is about 1/1 / the short side dimension.
It is 3. As in the second embodiment, the remaining portion 11-4 has two smooth concave shapes each having a (3, 1) mode natural vibration mode shape as a substantially flat plate.
It is formed in a curved surface shape in which two convex shapes are alternately connected. In addition, not only the panel 6-4 surrounded by the side member 3, the side sill 4, the second cross member 1, and the third cross member 2, but also other members such as the tunnel member 5, the seat cross member 9, the tunnel vertical wall portion 8, and the like. Similarly, a flat edge portion 10-4 and a remaining portion 11-4 can be provided for the panel 6-4 surrounded by.

Next, the operation of the fourth embodiment will be described.

Where the natural frequency of the (1,1) mode is placed is extremely important, and it may be difficult to reduce the natural frequency to an optimum natural frequency when the panel size is small.
In the present embodiment, under the condition that the area of the flat edge is the same, compared with the case where the width of the flat edge is made uniform,
By making the width of the central portion of the edge 10-4 having a large influence on the (1,1) mode larger than the average width dimension, preferably the maximum, the efficiency is improved without affecting the higher-order mode. In addition, the natural frequency of the (1,1) mode can be reduced, and a panel having low radiation efficiency in a required frequency range can be realized.

Further, the maximum value of the width of the flat edge portion 10-4 is preferably set to 1/6 or more of the short side, whereby the natural frequency of the (1,1) mode is sufficiently suppressed. be able to.

FIG. 9B is a diagram showing the floor according to the fifth embodiment of the present invention viewed obliquely from above, and mainly shows the floor portion. Interior parts such as seats and floor carpets are omitted, and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 9A, the panel 6-5 of the present embodiment surrounded by the side member 3, the side sill 4, the second cross member 1, and the third cross member 2.
The panel 6-6 includes the entire side connected to the side member 3 which is a long side and the entire side connected to the side sill 4.
A flat edge portion 10-5 is provided toward the center of each of the five. The width of each flat edge 10-5 is not constant but varies along the long side, and is minimum at the center in the length direction of the long side and maximum at both ends in the length direction of the long side. As in the second embodiment, the remaining portion 11-5 has two smooth concave shapes and one convex shape alternately exhibiting the natural vibration mode shape of the (3,1) mode of the flat plate substantially as a whole. It is formed in a continuous curved shape. The side member 3, side sill 4, second cross member 1
And floor panel 7 surrounded by third cross member 2
Not only part of panel 6-5, but also tunnel member 5,
Similarly, a flat edge portion 10-5 and a remaining portion 11-5 can be provided for the panel 6-5 surrounded by other members such as the seat cross member 9, the tunnel vertical wall portion 8, and the like.

Next, the operation of the fifth embodiment will be described.

It is extremely important where the natural frequency of the (1,1) mode is set, and it may be difficult to raise the natural frequency to the optimum natural frequency depending on the panel. In the present embodiment, under the condition that the area of the flat edge is the same, the edge 10-that has a higher influence on the (1, 1) mode as compared with the case where the width of the flat edge is made uniform. By making the width of the central part of 5 smaller than the average width dimension, preferably the minimum,
Efficiently (1,
1) The natural frequency of the mode can be increased, and a panel with low radiation efficiency in a required frequency range can be realized.

In the above embodiment, the flat edges are provided from the two opposite long sides of the panel. However, the present invention is not limited to this. Only one long side is provided at the center of the panel. It is also possible to provide a flat edge towards the end. Further, in each embodiment, a rectangular panel has been described. However, the present invention is not limited to this. The present invention can be similarly applied to a rectangular panel such as a square or a rhombus having all sides equal in length. May be provided with a flat edge from any side toward the center of the panel.

[Brief description of the drawings]

FIG. 1A is a perspective view illustrating a configuration of a first embodiment of the present invention, and is a detailed view of a part of the panel,
(B) is an overall view showing the entire floor panel.

FIG. 2 shows the results of calculating the frequency dependence of the radiation efficiency between the panel of the first embodiment and a comparative panel in order to explain the effects of the first embodiment.

FIG. 3A is a perspective view illustrating a configuration of a second embodiment of the present invention, and is a detailed view of a part of the panel,
(B) is an overall view showing the entire floor panel.

FIG. 4 shows a result of calculating frequency dependence of radiation efficiency in order to explain an effect of the second embodiment.

FIG. 5 shows the maximum height of the unevenness at the center of the panel being 0.01 m.
The result of calculating the difference between the natural frequencies of the (1,1) mode when the width is 0.02 m and the width of the flat edge is changed.

FIG. 6A is a perspective view illustrating a configuration of a third embodiment of the present invention, and is a detailed view of a part of the panel,
(B) is an overall view showing the entire floor panel.

FIG. 7 is an explanatory diagram showing a panel having a high noise level in a (1, 2) mode or a (2, 1) mode suitable for the third embodiment.

FIG. 8A is a perspective view illustrating a configuration of a fourth embodiment of the present invention, and is a detailed view of a part of the panel,
(B) is an overall view showing the entire floor panel.

FIG. 9A is a perspective view illustrating a configuration of a fifth embodiment of the present invention, and is a detailed view of a part of the panel.
(B) is an overall view showing the entire floor panel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Second cross member 2 Third cross member 3 Side member 4 Side sill 5 Tunnel member 6, 6-2, 6-3, 6-4, 6-5 Panel 7 Floor panel 8 Tunnel vertical wall part 9 Seat cross member 10, 10- 2,10-3,10-4,10-5 Flat edge 11,11-2,11-3,11-4,11-5 Remaining part other than flat edge

Claims (11)

[Claims] 1. A substantially rectangular panel in an environment where a vibration mode is excited and whose periphery is constrained, wherein at least one side other than the short side of the panel has a flat edge toward the center of the panel. A panel structure, wherein at least one or more continuously curved concave shapes or at least one or more continuously curved convex shapes are formed in a remaining portion of the panel other than the edge portion. . 2. The flat edge portion has a width from the side other than the short side of the panel toward the center of the panel, which is 1/6 or more of a length dimension of a side adjacent to the side and 3 / The panel structure according to claim 1, wherein the length is less than 6, and the length is the length of the side other than the short side. 3. The panel structure according to claim 1, wherein the width of the flat edge portion changes along a side that is not a short side. 4. The width of the flat edge is set to be larger than the average value of the width of the flat edge at the center in the length direction of the side other than the short side. 3. The panel structure according to 3. 5. The width of the flat edge is set to be smaller than the average value of the width of the flat edge at the center in the length direction of the side other than the short side. 3. The panel structure according to 3. 6. The maximum value of the width of the flat edge is 1/6 of the length of a side adjacent to the side other than the short side of the panel.
The panel structure according to any one of claims 3 to 5, wherein: 7. The method according to claim 6, wherein the remaining portion is formed in a curved shape so as to exhibit a (1,3) mode or a (3,1) mode natural vibration mode shape substantially as a whole. The panel structure according to any one of claims 1 to 6. 8. The method according to claim 1, wherein the remaining portion is formed in a curved shape so as to exhibit a natural vibration mode shape of a (1,2) mode or a (2,1) mode of a flat plate substantially as a whole. The panel structure according to any one of claims 1 to 6. 9. A substantially rectangular panel which is in an environment where a vibration mode is excited and whose surroundings are constrained to some extent, wherein all or at least a part of the panel is entirely (1,3) mode or ( (3) A panel structure characterized by forming a curved surface shape having a smooth uneven shape so as to exhibit a natural vibration mode shape of a mode. 10. The panel structure according to claim 1, wherein the panel is a vehicle configuration panel. 11. The vehicle configuration panel, wherein one side extending in the vehicle longitudinal direction is connected to a side sill or a side member, and the other side extending in the vehicle longitudinal direction is a side member.
The panel according to claim 10, wherein the panel is a part of the floor panel connected to a junction between the tunnel member or the vertical wall portion of the tunnel and the floor panel, and a side extending in the vehicle left-right direction is connected to a cross member of the floor. Construction.