JP2021133721A - Vehicle underfloor structure - Google Patents

Abstract

To efficiently reduce noise while a vehicle travels with an acoustic material and to minimize a protrusion dimension of the acoustic material from a frame member to the extent possible.SOLUTION: A vehicle underfloor structure which constitutes a lower edge section of a door opening 12 of a vehicle body comprises: a frame member 30 which is extended in a longitudinal direction of the vehicle; a door 20 which covers the frame member 30 from an outside when the door opening 12 is closed and has a door trim vertically extended at a position of the frame member 30; and an acoustic member installed at a lower side of the frame member 30. The acoustic member has: a diffraction point K which changes a propagation direction of noise outwardly radiated in a vehicle width direction along a road surface to an obliquely upward direction and a plate-like acoustic material 50 which covers a lower surface of the frame member 30 and reduces energy of the noise with the propagation direction thereof changed to the obliquely upward at the diffraction point K. A space S is formed between the acoustic material 5 and the lower surface of the frame member 30.SELECTED DRAWING: Figure 3

Description

The present invention relates to a vehicle underfloor structure including a skeleton member extending in the front-rear direction of the vehicle and a noise reducing member provided under the skeleton member, which constitutes a lower edge portion of a door opening of the vehicle body.

Patent Document 1 describes a technique relating to the underfloor structure of the vehicle. In the vehicle underfloor structure described in Patent Document 1, as shown in FIGS. 9 and 10, a wall-shaped noise reducing member 110 is attached to the lower side of the rocker portion 104 of the vehicle. As shown in FIG. 10, the noise reduction member 110 includes a side guard portion 112 having an L-shaped cross section including a vertical wall portion 112t and a horizontal wall portion 112y. The side guard portion 112 is screwed to the lower end flange 104f of the rocker portion 104 so that the horizontal wall portion 112y is on the inside and the vertical wall portion 112t is on the outside.

Inside the side guard portion 112, a plate-shaped sound absorbing material 113 is provided in an inclined state so as to connect the tip of the horizontal wall portion 112y and the upper end of the vertical wall portion 112t, and the sound absorbing material 113 and the side guard portion are provided. A space S is formed between the inner wall surfaces of the 112. Further, the space S is partitioned in the length direction (front-back direction) by a plurality of partition walls (not shown). As a result, the noise radiated to the outside in the vehicle width direction along the road surface (the arrow indicates the propagation direction) is received by the sound absorbing material 113, so that the energy of the noise is reduced in the sound absorbing material 113 and the space S. Be made to.

Japanese Unexamined Patent Publication No. 2004-168134

However, the noise reduction member 110 described above is configured to receive the noise radiated to the outside in the vehicle width direction along the road surface as it is by the sound absorbing material 113. Therefore, in order to increase the noise reduction effect, it is necessary to increase the height dimension of the side guard portion 112 and the sound absorbing material 113. As a result, the downward protrusion dimension of the side guard portion 112 (sound absorbing material 113) from the rocker portion 104 of the vehicle becomes large.

The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to efficiently reduce noise during vehicle running by a sound absorbing material and to absorb the sound from the skeleton member. It is to make the protruding dimension of the material as small as possible.

The above-mentioned problems are solved by each invention. The first invention constitutes a lower edge portion of a door opening of a vehicle body, covers a skeleton member extending in the front-rear direction of the vehicle, and covers the skeleton member from the outside when closing the door opening, and the skeleton member. It is a vehicle underfloor structure including a door formed so that the door parting line extends in the vertical direction at the position of, and a noise reducing member provided under the skeleton member, and the noise reducing member is a road surface. The diffusion starting point that changes the propagation direction of the noise radiated outward in the vehicle width direction diagonally upward along the vehicle width, and the noise that covers the lower surface of the skeleton member and whose propagation direction is changed diagonally upward by the diffraction starting point. A plate-shaped sound absorbing material for reducing energy is provided, and a space is formed between the sound absorbing material and the lower surface of the skeleton member.

According to the present invention, the sound absorbing material covers the lower surface of the skeleton member, and a space is formed between the sound absorbing material and the lower surface of the skeleton member. Therefore, the noise when the vehicle is running can be efficiently reduced by the action of the sound absorbing material and the space. Further, the sound absorbing material is configured to be able to reduce the energy of noise whose propagation direction is changed obliquely upward by the diffraction origin. Therefore, as compared with the conventional case where the sound absorbing material is arranged so as to directly reduce the noise radiated to the outside in the vehicle width direction along the road surface, the protruding dimension of the sound absorbing material from the lower surface of the skeleton member. Can be made smaller.

According to the second invention, an exterior member extending in the front-rear direction of the vehicle is attached to the outer surface of the skeleton member with its lower end protruding below the lower surface of the skeleton member, and the lower surface of the skeleton member. Is formed so that the flange portion extends in the front-rear direction of the vehicle in a vertically oriented state, and the sound absorbing material covers the lower end of the exterior member and the lower end of the flange portion of the skeleton member from below. A space is formed between the sound absorbing material and the lower surface of the skeleton member. By providing the sound absorbing material so as to cover the lower end of the exterior member and the lower end of the flange portion of the skeleton member from below, the protruding dimension of the sound absorbing material from the lower surface of the skeleton member can be minimized. In addition, a wide space can be secured between the sound absorbing material and the lower surface of the skeleton member, and low-frequency noise with large energy can be efficiently absorbed.

According to the third invention, the height position of the space formed between the sound absorbing material and the lower surface of the skeleton member is set to be the same as the lower end position of the door that opens and closes the door opening of the vehicle body.

According to the fourth invention, the diffraction origin is provided on the flange inner cover portion of the sound absorbing material arranged at the inner position in the vehicle width direction with respect to the flange portion of the skeleton member. Therefore, the noise whose propagation direction is changed obliquely upward by the diffraction origin can be guided to the sound absorbing material and the space arranged at the outer position in the vehicle width direction from the flange portion of the skeleton member.

According to the fifth invention, the flange inner cover portion of the sound absorbing material includes a reverse groove-shaped portion formed in a reverse groove shape in cross section and a horizontal plate portion formed inside the reverse groove shape portion in the vehicle width direction. The ridgeline portion extending in the front-rear direction of the vehicle at the boundary position between the horizontal plate portion and the inverted groove-shaped portion serves as the diffraction starting point. Therefore, it is possible to guide the noise whose propagation direction is changed obliquely upward by the diffraction origin into the inverted groove-shaped portion of the sound absorbing material, and to absorb the noise at this portion.

According to the sixth invention, the inverted groove-shaped portion of the flange inner cover portion of the sound absorbing material is fitted in the recess formed by the lower surface of the skeleton member and the flange portion. Therefore, the amount of protrusion of the flange inner cover portion of the sound absorbing material with respect to the lower surface of the skeleton member can be minimized.

According to the present invention, noise during vehicle running can be efficiently reduced by the sound absorbing material. In addition, the protruding dimension of the sound absorbing material from the skeleton member can be made as small as possible.

It is a schematic perspective view of the vehicle provided with the underfloor structure of the vehicle according to the first embodiment of the present invention. It is a vertical cross-sectional view (II-II arrow view of FIGS. 1 and 5) in the lower part of the floor of the vehicle. It is a vertical cross-sectional view (III-III arrow view of FIG. 5) in the lower part of the floor of the vehicle. It is a perspective view which shows the attachment state of the rocker molding with respect to the rocker under the floor of a vehicle. It is a perspective view which shows the attachment state of the sound absorbing material with respect to the rocker molding under the floor of a vehicle. It is an enlarged vertical sectional view of a sound absorbing material. It is a schematic diagram which shows the function of a sound absorbing material. It is a vertical cross-sectional view which shows the noise reduction (sound absorption) action in the lower part of the floor of the vehicle which concerns on this embodiment. It is a schematic perspective view of the vehicle provided with the conventional noise reduction member. 9 is a cross-sectional view taken along the line XX of FIG.

[Embodiment 1]
Hereinafter, the underfloor structure of the vehicle according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 8. The underfloor structure of the vehicle according to the present embodiment relates to a structure that reduces noise during traveling of the vehicle radiated to the outside in the vehicle width direction along the road surface. Here, the front-rear, left-right, and top and bottom shown in the figure correspond to the front-back, left-right, and top and bottom of the vehicle having the underfloor structure according to the present embodiment.

<Overview of vehicle body 10>
As shown in FIG. 1, the vehicle body 10 is provided with a front door opening 11 corresponding to the front seat and a rear door opening 12 corresponding to the rear seat. A rocker 30 which is a hexagonal tubular frame extending in the front-rear direction of the vehicle is provided at the lower edges of the door openings 11 and 12. The front door opening 11 is configured to be openable and closable by a front door 15 that can rotate around a door hinge (not shown). Further, the rear door opening 12 is configured to be openable and closable by a slide door 20 that slides in the front-rear direction of the vehicle. Here, as shown in FIGS. 2 and 3, the lower end position of the slide door 20 is set to a position lower than the lower surface of the locker 30 and higher than the lower end position of the rocker molding 40 (described later). There is. That is, since the sliding door 20 is configured to cover the locker 30 from the outside when the rear door opening 12 is closed, the sliding door 20 is formed so that the door parting line extends in the vertical direction at the position of the locker 30.

<About the locker 30 that constitutes the underfloor structure of the vehicle>
The lockers 30 are provided so as to be symmetrical on both sides of the lower floor of the vehicle body 10 in the vehicle width direction. As shown in FIGS. 2 to 5, the rocker 30 includes a rocker inner 31 extending in the front-rear direction of the vehicle, a rocker outer 33, and a rocker reinforcement 34 for reinforcing the inner wall surface of the rocker outer 33. Further, as shown in FIG. 2 and the like, the rocker 30 includes a side outer 35 that covers the upper outer side of the rocker outer 33. In FIG. 5, the side outer 35 is omitted. Further, in FIGS. 2 to 5, the locker 30 on the left side of the vehicle is displayed, and the locker 30 on the right side is omitted.

As shown in FIG. 2, the rocker inner 31 constituting the rocker 30 is formed in a substantially horizontal U-shape in cross section, and an upper end flange portion 31u is formed at the upper end position and a lower end flange portion 31d is formed vertically at the lower end position. ing. Further, the floor panel 16 is fixed to the upper end corner of the rocker inner 31 by welding or the like while being overlapped from above. The rocker outer 33 constituting the rocker 30 is formed in a substantially horizontal U-shape in cross section, and an upper end flange portion 33u is formed at the upper end position and a lower end flange portion 33d is formed vertically at the lower end position. Then, the upper end flange portion 33u and the lower end flange portion 33d of the rocker outer 33 and the upper end flange portion 31u and the lower end flange portion 31d of the rocker inner 31 are aligned with each other to form a hexagonal tubular rocker 30 extending in the vehicle front-rear direction. Will be done.

As shown in FIG. 2, the upper end flange portion 31u of the rocker inner 31 and the upper end flange portion 33u of the rocker outer 33 are fixed by welding or the like in a state of being overlapped with the upper end flange portion 35u of the side outer 35. Further, the lower end flange portion 31d of the rocker inner 31 and the lower end flange portion 33d of the rocker outer 33 are fixed to each other by welding or the like in a state of being overlapped with each other. Further, on the rocker 30, a fixing step 12s is provided at the position of the rear door opening 12 so as to cover the upper surface of the rocker 30 and the edge of the floor panel 16.

<About Locker Mall 40>
As shown in FIGS. 2 and 3, the outer surface of the rocker 30 is covered by a rocker molding 40 extending in the vehicle front-rear direction from the lower half of the side outer 35 to the lower side of the outer surface of the rocker outer 33. The rocker molding 40 is an exterior member that covers the corners between the outer surface and the lower surface of the rocker 30 and the periphery thereof, and also serves as protection and decoration for the rocker 30. The rocker molding 40 is formed into a substantially L-shaped cross section by a vertical wall portion 43 that covers the outer surface of the rocker 30 and a horizontal wall portion 45 that covers the lower surface of the rocker 30 from below.

As shown in FIGS. 2 and 3, clips 43c for fixing the upper portion of the rocker molding 40 to the rocker outer 33 and the side outer 35 of the rocker 30 are provided on the upper portion of the vertical wall portion 43 of the rocker molding 40 in the vehicle front-rear direction. A plurality of them are provided at equal gaps. The lower portion of the vertical wall portion 43 of the rocker molding 40 projects downward from the lower surface of the rocker outer 33 by a dimension substantially equal to the protruding dimension of the lower end flange portion 33d. Therefore, the side wall portion 45 of the rocker molding 40 is separated from the lower surface of the rocker outer 33 by a dimension substantially equal to the protruding dimension of the lower end flange portion 33d.

As shown in FIG. 2, a fixed flange plate 47 is connected to the tip of the lateral wall portion 45 of the rocker molding 40 via an integral hinge 46. The fixed flange plate 47 is a member for fixing the lower end portion (horizontal wall portion 45) of the rocker molding 40 to the lower surface of the rocker outer 33 of the rocker 30, and as shown in FIG. It is provided. Further, as shown in FIGS. 4 and 5, the fixed flange plate 47 fixed to the front end portion and the rear end portion of the rocker 30 supports the front end portion and the rear end portion of the sound absorbing material 50 (described later). The bracket portion 47z is formed.

Further, as shown in FIGS. 3 and 4, the lateral wall portion 45 of the rocker molding 40 is provided with an outer edge (edge flange portion 51) of the sound absorbing material 50 in the vehicle width direction between adjacent fixed flange plates 47. A fixing bracket 49 for sandwiching and fixing is attached.

<About sound absorbing material 50>
The sound absorbing material 50 is a plate-shaped member formed of a fiber material or the like, and converts noise energy into heat energy by friction of the fiber material or the like to reduce the noise. As shown in FIGS. 2, 3 and 5, the sound absorbing material 50 extends in the front-rear direction of the vehicle while covering both sides of the lower floor of the vehicle in the vehicle width direction, that is, the rocker 30 and its periphery from below. It is provided. The sound absorbing material 50 is provided with an edge flange portion 51, a space forming lid portion 53, a reverse groove shape portion 55, and a horizontal plate portion 57 in order from the outside in the vehicle width direction. Then, as described above, the sound absorbing material 50 is fixed to the side wall portion 45 of the rocker molding 40 by, for example, a tapping screw in a state where the end edge flange portion 51 is sandwiched between the fixing metal fittings 49.

As shown in FIGS. 2 and 3, the space forming lid portion 53 of the sound absorbing material 50 is arranged so as to cover the side wall portion 45 of the rocker molding 40 and the tips of the lower end flange portions 31d and 33d of the rocker 30 from below. There is. That is, the space forming lid portion 53 of the sound absorbing material 50 has a groove shape formed by the lower end flange portions 31d and 33d of the rocker 30, the lower surface of the rocker 30 (rocker outer 33), and the vertical wall portion 43 of the rocker molding 40. The space S is covered from below like a lid. Further, as shown in FIG. 2, the fixed flange plate 47 of the rocker molding 40 is fixed to the lower surface of the rocker outer 33 of the rocker 30, so that a space is also provided between the rocker molding 40 and the lower surface of the rocker 30 (rocker outer 33). Is formed. As a result, the protruding dimension of the space forming lid 53 of the sound absorbing material 50 with respect to the lower end of the rocker 30 can be suppressed to be small, and a wide space S can be formed between the sound absorbing material 50 and the lower surface of the rocker 30 (rocker outer 33). .. Here, as shown in FIG. 5, the front end portion and the rear end portion of the space forming lid portion 53 of the sound absorbing material 50 are supported by the bracket portion 47z of the fixed flange plate 47 of the rocker molding 40.

As shown in FIGS. 2 and 3, the reverse groove-shaped portion 55 of the sound absorbing material 50 has a reverse groove shape in cross section due to the outer vertical wall 55w on the outer side in the vehicle width direction, the ceiling wall 55t, and the inner vertical wall 55y on the inner side in the vehicle width direction. It is molded into (a substantially trapezoidal cross section). The outer vertical wall 55w and the ceiling wall 55t of the reverse groove-shaped portion 55 are fitted into the recess formed by the lower surface of the rocker inner 31 of the rocker 30 and the lower end flange portion 31d.

As shown in FIGS. 2 and 3, the edge of the horizontal plate portion 57 of the sound absorbing material 50 is connected to the lower end of the inner vertical wall 55y of the inverted groove-shaped portion 55 of the sound absorbing material 50. The horizontal plate portion 57 of the sound absorbing material 50 is formed substantially parallel to the road surface. Therefore, the inner vertical wall 55y of the inverted groove-shaped portion 55 of the sound absorbing material 50 is bent diagonally upward with respect to the horizontal plate portion 57. As a result, a ridge line K extending in the front-rear direction of the vehicle is formed at the boundary position between the inner vertical wall 55y and the horizontal plate portion 57 of the inverted groove-shaped portion 55 of the sound absorbing material 50. Then, the ridge line K becomes a diffraction origin K that changes the propagation direction (see the arrow in FIG. 8) of the noise radiated outward in the vehicle width direction along the road surface diagonally upward. Here, the horizontal plate portion 57 of the sound absorbing material 50 and the diffraction starting point K are provided at positions lower than the space forming lid portion 53. It is also possible to provide the horizontal plate portion 57 of the sound absorbing material 50 and the diffraction starting point K at the same height position as the space forming lid portion 53.

<About the composition of the sound absorbing material 50>
As shown in FIG. 6, the sound absorbing material 50 includes a resin skin layer 502 having a plurality of pinholes 501, a relatively hard first fiber layer 504 made of fibers such as pressed glass wool, and a relatively soft glass wool or the like. It is formed by laminating a second fiber layer 506 made of the above fibers. The weight (weighting) per unit area of the first fiber layer 504 ^{is set to, for example, 1300 g / m 2} , and the weight of the second fiber layer 506 is set to ^{, for example, 300 g / m 2.}

Here, road noise and the like during vehicle traveling are generally about 500 Hz to about 2 kHz. The sound absorbing material 50 is set with a mounting position and a size of a space S between the sound absorbing material 50 and the rocker 30 so that noise of about 500 Hz to 1 kHz, which has a particularly large energy in the frequency range, can be efficiently reduced. As shown in FIG. 7, it is efficient to arrange the sound absorbing material 50 at a position having a 1/4 wavelength where the amplitude of the sound is the largest (a position where the vibration is the largest). Therefore, by increasing the size of the space S between the sound absorbing material 50 and the rocker 30 as much as possible, noise in a low frequency band can be efficiently reduced by the sound absorbing material 50.

<About the function of the sound absorbing material 50, etc.>
Road noise and the like during vehicle travel are radiated outward in the vehicle width direction along the road surface (not shown), as shown by the arrows in FIG. The noise radiated to the outside in the vehicle width direction propagates along the lower surface of the horizontal plate portion 57 of the sound absorbing material 50. Then, the noise radiated along the horizontal plate portion 57 of the sound absorbing material 50 wraps around from the diffraction origin point K to the inside of the reverse groove-shaped portion 55 due to the sound diffracting action. That is, the noise propagation direction is changed diagonally upward by the diffraction origin K (see the arrow). As a result, the noise comes into contact with the ceiling wall 55t of the inverted groove-shaped portion 55 of the sound absorbing material 50 and the outer vertical wall 55w in a state of being substantially perpendicular to each other. That is, the energy of the noise whose propagation direction is changed diagonally upward is absorbed by the ceiling wall 55t and the outer vertical wall 55w of the inverted groove-shaped portion 55 of the sound absorbing material 50, and the space after that. Here, the dimensions from the diffraction origin K to the ceiling wall 55t of the inverted grooved portion 55 and the outer vertical wall 55w are set to about 40 mm to about 60 mm when the noise frequency is about 500 Hz to 1 KHz. However, it is more preferable to set it between 45 mm and 55 mm.

Further, the noise whose propagation direction is changed obliquely upward at the diffraction starting point K reaches the space forming lid portion 53 of the sound absorbing material 50 and the space S thereafter, and the noise energy is absorbed at this position. As described above, since the sound absorbing material 50 absorbs the energy of the noise whose propagation direction is changed obliquely upward by the diffraction origin K, the protruding dimension of the sound absorbing material 50 from the lower surface of the rocker 30 can be suppressed to a small size. can.

<Correspondence between the term according to the present embodiment and the term according to the present invention>
The rocker 30 of the vehicle body 10 in the present embodiment corresponds to the skeleton member of the vehicle body of the present invention, and the lower end flange portions 31d and 33d of the rocker 30 correspond to the flange portions formed on the lower surface of the skeleton member of the present invention. Further, the sound absorbing material 50 in the present embodiment corresponds to the noise reducing member of the present invention, and the inverted grooved portion 55 and the horizontal plate portion 57 of the sound absorbing material 50 correspond to the flange inner cover portion in the sound absorbing material of the present invention. Further, the rocker molding 40 in the present embodiment corresponds to the exterior member of the present invention. Further, the sliding door 20 in the present embodiment corresponds to the door of the present invention.

<Advantages of the underfloor structure of the vehicle according to this embodiment>
According to the underfloor structure of the vehicle according to the present embodiment, the sound absorbing material 50 covers the lower surface of the rocker 30 (skeleton member), and a space S is formed between the sound absorbing material 50 and the lower surface of the rocker 30. Therefore, the noise when the vehicle is running can be efficiently reduced by the action of the sound absorbing material 50 and the space S. Further, the sound absorbing material 50 is configured to be able to reduce (absorb) the energy of noise whose propagation direction is changed obliquely upward by the diffraction origin K. Therefore, as compared with the conventional case where the sound absorbing material is arranged so as to directly absorb the noise radiated to the outside in the vehicle width direction along the road surface, the sound absorbing material 50 protrudes from the lower surface of the rocker 30. The dimensions can be reduced.

Further, by providing the sound absorbing material 50 so as to connect the lower end of the rocker molding 40 (exterior member) and the lower ends of the lower end flange portions 31d and 33d of the rocker 30, the protruding dimension of the sound absorbing material 50 from the lower surface of the rocker 30 is minimized. Can be done. Further, a wide space S can be secured between the sound absorbing material 50 and the lower surface of the rocker 30, and low-frequency noise having a large energy can be efficiently absorbed. Further, the noise whose propagation direction is changed obliquely upward by the diffraction origin K is guided into the inverted groove-shaped portion 55 of the sound absorbing material 50, and sound can be absorbed at this portion. Further, since the inverted groove-shaped portion 55 of the sound absorbing material 50 is fitted in the recess formed by the lower surface of the rocker 30 and the lower end flange portions 31d and 33d, the amount of protrusion of the sound absorbing material 50 with respect to the lower surface of the rocker 30 is minimized. Can be suppressed to.

[Change example]
The present invention is not limited to the above embodiment, and changes can be made without departing from the present invention. For example, in the present embodiment, an example is shown in which the ridge line at the boundary between the inner vertical wall 55y of the inverted groove-shaped portion 55 of the sound absorbing material 50 and the horizontal plate portion 57 is set as the diffraction origin K. However, it is also possible to form the diffraction origin K by a member different from the sound absorbing material 50. Further, although the example in which the sound absorbing material 50 is provided on the portion covering the lower surface of the rocker 30, the sound absorbing material 50 can be extended to the positions of the front and rear wheel houses. Further, as shown in FIGS. 2 and 3, an example is shown in which the inverted groove-shaped portion 55 of the sound absorbing material 50 is formed into a substantially trapezoidal cross section by the inner vertical wall 55y, the ceiling wall 55t, and the outer vertical wall 55w. However, it is also possible to form the ceiling wall 55t of the inverted grooved portion 55 and the outer vertical wall 55w in an arc shape centered on the diffraction origin K.

10 ... Vehicle body 20 ... Sliding door (door)
30 ... Rocker (skeleton member)
31d ・ ・ ・ Lower end flange part (flange part)
33d ・ ・ ・ Lower end flange part (flange part)
40 ... Rocker mall (exterior member)
50 ... Sound absorbing material (noise reduction member)
55 ... Reverse groove shape (flange inner cover)
57 ... Horizontal plate (flange inner cover)
K ・ ・ ・ ・ ・ Diffraction starting point S ・ ・ ・ ・ ・ Space

Claims (6)

The lower edge of the door opening of the vehicle body is formed, and the skeleton member extending in the front-rear direction of the vehicle and the skeleton member are covered from the outside when the door opening is closed, and the door parting is performed at the position of the skeleton member. A vehicle underfloor structure including a door formed so as to extend in the vertical direction and a noise reducing member provided under the skeleton member.
The noise reduction member is
A diffraction starting point that changes the propagation direction of noise radiated outward in the vehicle width direction diagonally upward along the road surface,
A plate-shaped sound absorbing material that covers the lower surface of the skeleton member and reduces the energy of the noise whose propagation direction is changed obliquely upward by the diffraction origin.
Is equipped with
A vehicle underfloor structure in which a space is formed between the sound absorbing material and the lower surface of the skeleton member. The vehicle underfloor structure according to claim 1.
An exterior member extending in the front-rear direction of the vehicle is attached to the outer surface of the skeleton member with its lower end protruding below the lower surface of the skeleton member, and a flange portion is attached to the lower surface of the skeleton member. It is formed so as to extend in the front-rear direction of the vehicle in a vertical orientation.
A vehicle underfloor structure in which a space is formed between the sound absorbing material and the lower surface of the skeleton member by covering the lower end of the exterior member and the lower end of the flange portion of the skeleton member from below with the sound absorbing material. The vehicle underfloor structure according to claim 1 or 2.
The height position of the space formed between the sound absorbing material and the lower surface of the skeleton member is set to be equivalent to the lower end position of the door that opens and closes the door opening of the vehicle body. The vehicle underfloor structure according to claim 2 or 3.
The underfloor structure of a vehicle in which the diffraction origin is provided on the flange inner cover portion of the sound absorbing material arranged at a position inside the flange portion of the skeleton member in the vehicle width direction. The vehicle underfloor structure according to claim 4.
The flange inner cover portion of the sound absorbing material includes a reverse groove-shaped portion formed in a reverse groove shape in cross section and a horizontal plate portion formed inside the reverse groove-shaped portion in the vehicle width direction.
The underfloor structure of the vehicle in which the ridge line portion extending in the front-rear direction of the vehicle at the boundary position between the horizontal plate portion and the inverted groove-shaped portion serves as the diffraction starting point. The vehicle underfloor structure according to claim 5.
A vehicle floor lower structure in which a reverse groove-shaped portion of the flange inner cover portion of the sound absorbing material is fitted in a recess formed by the lower surface of the skeleton member and the flange portion.

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