JP4483409B2 - Sheet - Google Patents

Description

  The present invention relates to a sheet in which a frame is formed by stacking a plurality of fiber-reinforced composite materials.

  Conventionally, there is JP-A-5-115329 as a technique in such a field. The seat described in this publication has a panel-type seat frame, and this seat frame is formed by FRP so as to satisfy both weight reduction and rigidity at the same time. Apart from this, in recent years, a fiber reinforced composite material (for example, carbon fiber reinforced resin) that is remarkably excellent in rigidity characteristics and light weight characteristics has appeared, and this material is used for bodies such as competition vehicles.

Japanese Patent Laid-Open No. 5-115329 JP-A-7-217689 Japanese Patent Laid-Open No. 9-226039 WO98 / 47693 Japanese Patent Laid-Open No. 4-1029

  However, the conventional sheet described above has the following problems. In other words, when fiber reinforced composite material is used in the frame of a vehicle seat, the safety of the occupant is further improved by controlling the location where the frame breaks and the state after the break when the frame breaks due to a vehicle collision, etc. Is required.

  An object of the present invention is to provide a seat that ensures safety for passengers particularly when a frame is damaged due to a vehicle collision or the like.

The seat according to the present invention includes a vertical frame extending in the vertical direction and a horizontal frame extending in the horizontal direction, and is configured to receive the lateral force by laminating a plurality of fiber-reinforced composite materials. A frame is provided, and the frame is provided with a fragile portion that breaks when subjected to a lateral load on the lateral frame of the non-exposed portion provided with a member covering the frame. It is characterized by.

The frame in this sheet is formed by laminating fiber reinforced composite materials, and has sufficient durability during normal use. However, such a fiber reinforced composite material is required to control the location and the state after destruction when the frame breaks due to a vehicle collision or the like. Therefore, a fragile portion is provided in a non-exposed portion of the frame to control the breakage position so that the breakage portion of the frame is not exposed to the outside, thereby improving the safety of the passenger.
Further, the frame may be provided with a fragile portion that is broken when a load is applied to the longitudinal frame of the non-exposed portion.
Further, the member covering the lateral frame may be a seat bag or a headrest.

  Further, it is preferable that the member covering the frame is a headrest, and the fragile portion has a smaller number of laminated fiber reinforced composite materials than other portions. With this configuration, the break position can be easily controlled.

  Further, it is preferable that the member covering the frame is a headrest, and the fragile portion is provided with a butt joint of the fiber reinforced composite material in a separated state. With this configuration, the break position can be easily controlled.

  Further, it is preferable that the member covering the frame is a seat back, and the weakened portion has a smaller number of laminated fiber reinforced composite materials than other portions. With this configuration, the break position can be easily controlled.

  Further, it is preferable that the member covering the frame is a seat back, and a step is provided in the fragile portion. With this configuration, the break position can be easily controlled.

  Further, it is preferable that the member covering the frame is a seat back, and the fragile portion is adjusted by the fiber direction of the fiber-reinforced composite material based on the longitudinal direction of the frame. With this configuration, the break position can be easily controlled.

A sheet according to the present invention comprises a vertical frame extending in the vertical direction, a horizontal frame extending in the horizontal direction, and a connecting portion that connects the vertical frame and the horizontal frame, and a plurality of fiber-reinforced composite materials. It is good also as providing a frame constituted so that it may receive lateral force by laminating, and a plastic deformation part is provided in the joint part exposed from the member which covers the frame to the frame. .

  The frame in this sheet is formed by laminating fiber reinforced composite materials, and has sufficient durability during normal use. However, such a fiber reinforced composite material is required to further improve the safety of the occupant by controlling the location where the frame breaks and the state after the break when the frame breaks due to a vehicle collision or the like. Therefore, by providing the frame with a portion that causes plastic deformation to be stretched by a load greater than a predetermined value, the fractured portion breaks in a flexible state, so the fiber reinforced composite material is used even in the exposed portion of the frame. be able to. This ensures the safety of the passenger.

  Further, it is preferable that the plastic deformation site is adjusted by the fiber direction of the fiber-reinforced composite material with reference to the longitudinal direction of the frame. By constructing the plastic deformation site in this way, the fractured portion is fractured in a flexible state.

  Further, it is preferable that at least one aramid fiber layer or an aramid / carbon mixed woven layer is provided in the plastic deformation portion. By configuring the plastic deformation site in this way, plastic deformation occurs between the aramid fiber layer of the frame and the FRP layer as the base material, or between the aramid mixed fiber layer and the FRP layer as the base material, The broken part breaks in a flexible state.

A sheet according to the present invention comprises a vertical frame extending in the vertical direction, a horizontal frame extending in the horizontal direction, and a connecting portion for connecting the vertical frame and the horizontal frame, and a plurality of fiber-reinforced composite materials. It is good also as providing the flame | frame comprised so that it might receive the force of a horizontal direction by laminating | stacking, and having arrange | positioned the release film between the said fiber-reinforced composite materials laminated | stacked in the coupling | bond part.

The frame in this sheet is formed by laminating fiber reinforced composite materials, and has sufficient durability during normal use. However, such a fiber reinforced composite material is required to control the location and the state after destruction when the frame breaks due to a vehicle collision or the like. Therefore, by interposing the release film between the fiber reinforced composite materials, plastic deformation occurs between the release film and the fiber layer as the base material, and the fractured portion breaks in a flexible state.
The seat according to the present invention includes a frame composed of a vertical frame extending in the vertical direction and a horizontal frame extending in the horizontal direction, and the frame is a non-exposed portion provided with a member covering the frame. It is good also as the weak part being provided in the horizontal direction flame | frame.
Further, the frame may be provided with a fragile portion in the longitudinal frame of the non-exposed portion.
The seat according to the present invention includes a frame composed of a vertical frame extending in the vertical direction, a horizontal frame extending in the horizontal direction, and a coupling portion that couples the vertical frame and the horizontal frame, The coupling portion may be provided with a plastic deformation portion.

  According to the present invention, when a frame is damaged due to a vehicle collision or the like, safety for passengers can be ensured.

  Hereinafter, a preferred embodiment of a sheet according to the present invention will be described in detail with reference to the drawings. However, the same or equivalent components are denoted by the same reference numerals. Further, the “lateral direction” in the specification is a direction orthogonal to the longitudinal direction of the vehicle, that is, a direction when a side collision occurs.

[First embodiment]
As shown in FIG. 1, a vehicle seat 1 includes a seat cushion 2 attached to a floor surface via a slide adjustment mechanism, and a seat back 3 attached to the seat cushion 2 via a reclining mechanism. And. The seat back 3 is held by a pipe-shaped frame 4, and a U-shaped bed rest frame portion 4 a is integrally formed on the upper portion of the frame 4. A headrest 5 is fixed to the headrest frame portion 4a.

  The frame 4 used for such a sheet 1 is configured to receive a lateral force by laminating a plurality of fiber-reinforced composite materials, and has sufficient durability during normal use. The fiber reinforced composite material here is CFRP (carbon fiber reinforced resin) and has a beautiful texture pattern, which is excellent in design, and is desired to be used by exposing a part thereof.

  In forming the pipe-like frame 4 with this CFRP, wet carbon is used as a material in which a carbon fiber is soaked with a thermosetting resin. First, a length necessary for frame forming is created while overlapping end portions of wet carbon having a predetermined length, and a wet carbon layer having a desired thickness is created by laminating the wet carbon in a flat state while adhering. Thereafter, the shape of the frame 4 is created by adjusting the shape in the baking mold while rolling the laminated wet carbon layer into a pipe shape. And a wet carbon layer is hardened by heating a baking mold at predetermined temperature, and the flame | frame 4 as shown in FIG. 1 is shape | molded. In addition, as the wet carbon, there are bidirectional prepregs twilled or plain woven with longitudinal carbon fibers and lateral carbon fibers, and unidirectional prepregs having unidirectional carbon fibers, In consideration of the rigidity of the frame 4, a bidirectional prepreg is mainly used.

  However, such a fiber reinforced composite material is required to further improve the safety of the occupant by controlling the location where the frame breaks and the state after the break when the frame breaks due to a vehicle collision or the like. At this time, if the fracture surface and the plastically deformed portion are controlled so as to be generated in the non-exposed portion of the frame, the fracture surface and the plastically deformed portion are not exposed, so that safety for the occupant can be further improved. In this case, the member that generates the non-exposed portion of the frame 4, that is, the member that covers the frame 4 is the seat back 3 and the headrest 5.

  Here, as a measure for controlling the fracture position, as shown in FIG. 2, a fragile portion A1 is provided in the non-exposed portion S1 (see FIG. 1) of the pipe-like frame 4. In this fragile portion A1, the number of laminated CFRP (carbon fiber reinforced resin) 8 is less than that of other portions. For example, when the entire frame 4 is formed by laminating ten CFRP 8 having the same thickness so that the frame 4 has a predetermined thickness, the outer three CFRPs 8 are reduced in the weakened portion A1. As a result, in the fragile portion A1, the wall thickness becomes two thirds compared to other portions. Accordingly, the fragile portion A1 can be ruptured, and the rupture position can be controlled by the non-exposed portion S1.

  Further, as shown in FIG. 3, when the entire frame 4 is formed by laminating ten CFRPs 8 having the same thickness, the inner three CFRPs 8 are reduced in the fragile portion A2. Thereby, in weak part A2, thickness can be made into 2/3 compared with another part.

  In forming such a fragile portion A1, the thickness of the fragile portion A1 is set to 2 / of the average thickness of the entire frame 4 under conditions that provide sufficient durability during normal use. By setting it to 3 or less, the initial purpose can be achieved. Further, if the aforementioned weak portions A1 and A2 are provided in the lateral beam portion 4b (see FIG. 1) that is stretched laterally so as to handle the lateral load, the lateral beam portion 4b can be easily broken at the time of a vehicle collision. Become.

[Second Embodiment]
As a measure for controlling the breaking position, as shown in FIGS. 4 and 5, a butt seam P of CFRP 8 is provided in a separated state at the fragile portion A3 in the unexposed portion S1 (see FIG. 1) of the pipe-like frame 4. ing. At the butt joint P, the gap between the ends of the CFRP 8 is about 10 mm. When the entire frame 4 is formed by stacking eight CFRPs 8 having the same thickness, the butt joint P is provided at four locations in the fragile portion A3. The butt joint P is disposed on the same straight line in the thickness direction. Thereby, in the fragile part A3, the thickness is halved compared to other parts. Accordingly, the fragile portion A3 can be ruptured, and the rupture position can be controlled by the non-exposed portion S1.

  Further, as shown in FIG. 6, when the entire frame 4 is formed by stacking eight CFRP 8 of the same thickness, the butt joint P at the weakened portion A4 has the same straight line with an accuracy error of about 2 mm in the thickness direction. It may be arranged on a line. Moreover, as shown in FIG. 7, in the weak part A5, you may form the butt | joint joint P in step shape so that the continuous one piece of CFRP8 may be interposed. In this case, the butt joint P at the fragile portion A5 is arranged on the same straight line with an accuracy error of about 2 mm in the thickness direction.

  In addition, the location of the butt joint P of the fragile portions A3 to A5 is preferably about 1/4 or more of the total number of laminated layers of CFRP8 under conditions that provide sufficient durability during normal use. Further, if the above-mentioned weakened portions A3 to A5 are provided in the lateral beam portion 4b (see FIG. 1) that is stretched laterally so as to handle the lateral load, the lateral beam portion 4b can be easily broken at the time of a vehicle collision. Become.

[Third embodiment]
As a measure for controlling the breaking position, as shown in FIG. 8, the fragile portion A6 is reduced in diameter in the non-exposed portion S1 (see FIG. 1) of the pipe-like frame 4, and steps R1 are provided at both ends of the fragile portion A6. ing. When the entire frame 4 is formed by stacking eight CFRPs 8 having the same thickness, a tapered step R1 is formed in the fragile portion A6 so that stress is easily concentrated. Therefore, since the fragile portion A6 can easily cause a break, the break position can be controlled by the non-exposed portion S1.

  As shown in FIG. 9, when the entire frame 4 is formed by stacking eight CFRP 8 of the same thickness, an L-shaped step R2 is formed at the fragile portion A7 so that stress is easily concentrated. ing. Also, as shown in FIG. 10, a V-shaped step R3 is formed at the fragile portion A8 so that stress is easily concentrated.

  Note that the step depth D of the steps R1 to R3 is set to one third or more of the wall thickness under conditions that provide sufficient durability during normal use. Further, if the above-mentioned weakened portions A6 to A8 are provided in the lateral beam portion 4b (see FIG. 1) that is stretched laterally so as to handle the lateral load, the lateral beam portion 4b can be easily broken at the time of a vehicle collision. Become.

[Fourth Embodiment]
The frame 4 in the sheet 1 shown in FIG. 1 is configured by laminating CFRP (carbon fiber reinforced resin) 8, and has sufficient durability during normal use. However, such a fiber reinforced composite material is required to control the location and the state after destruction when the frame breaks due to a vehicle collision or the like.

  Therefore, as a measure for controlling the break position at the exposed portion S2, by providing the frame 4 with a portion B1 that causes plastic deformation to be stretched by a predetermined load or more, the break portion is broken in a flexible state. Therefore, CFRP (carbon fiber reinforced resin) 8 can be used for the frame 4 even in the exposed portion S2 (see FIG. 11) in the bedrest frame portion 4a. This ensures the safety of passengers. In particular, CFRP8 is excellent in design because it has a beautiful texture, and is desired to be exposed.

  As shown in FIG. 12, a release film 9 is disposed between the laminated CFRP (carbon fiber reinforced resin) 8 at the plastic deformation site B1. The release film 9 is made of a material (PP, PE, PTFE, etc.) having a thickness of 100 μm or less. When the above-described plastic deformation portion B1 is provided in the lateral beam portion 4b (see FIG. 1) that is stretched in the lateral direction so as to handle the lateral load, the compressive strength can be increased without reducing the rigidity of the frame 4 itself. It becomes easy to be broken inside the frame 4 at the time of a vehicle collision. Thus, the plastic deformation occurs inside the frame, and the deformation of the surface of the frame is suppressed, and the plastic deformation portion is not exposed to the surface, so that there is an effect that the safety becomes higher.

  Further, by providing the aforementioned plastic deformation portion B1 in the exposed portion S2 (see FIG. 11) in the bedrest frame portion 4a, when a lateral collision load is applied as shown in FIG. The corner portion C is deformed so as to be stretched, and the impact energy can be absorbed in the portion C. At this time, since the carbon fibers of each CFRP 8 are separated so as to be loosened at the corner portion C, the FRP layer divided into the respective layers is flexible even if it breaks, so that there is an effect that the safety becomes higher.

[Fifth Embodiment]
As a measure for controlling the breaking position in the exposed portion S2 (see FIG. 11) of the bed rest frame portion 4a, as shown in FIG. 14, ten CFRP (carbon fiber reinforced resins) laminated at the plastic deformation portion B2. ) 8 is provided with an intermediate layer 10 made of an aramid fiber layer or an aramid / carbon mixed layer. Such an aramid fiber layer or an aramid / carbon mixed woven layer has a large elongation, so when a lateral impact load is applied to the frame 4, it is deformed so as to stretch at the upper corner portion C (see FIG. 13), This portion C can absorb impact energy. At this time, since the carbon fibers of each CFRP 8 are separated so as to be loosened at the corner portion C, the FRP layer divided into the respective layers is flexible even if it breaks, so that there is an effect that the safety becomes higher.

[Sixth Embodiment]
The fragile portion A9 or the plastic deformation sites B3 and B4 are easily created by adjusting the direction of the CFRP (carbon fiber reinforced resin) 7 fiber with respect to the longitudinal direction of the frame 4.

  For example, as shown in FIG. 15, when the lateral beam portion 4b (see FIG. 1) spanned in the lateral direction so as to handle the lateral load in the non-exposed portion S1 is used as the fragile portion A9, In the beam portion 4b, ten unidirectional CFRPs 7 are laminated. At this time, with reference to the longitudinal direction L of the transverse beam portion 4b in the frame 4, the fibers of each CFRP 7 are arranged in a 0 ° direction, that is, a direction along the longitudinal direction L. In addition, when the fibers are arranged at 0 ° or 90 °, the transverse beam portion 4b is not easily deformed by tension, but is weakened by compression. As a result, only the strength can be reduced without lowering the rigidity. Therefore, since the fragile portion A9, that is, the transverse beam portion 4b can be broken, the break position can be controlled by the non-exposed portion S1.

  In addition, as shown in FIG. 16, in the fragile portion A10, that is, the lateral beam portion 4b, an intermediate layer of ten laminated unidirectional CFRPs (carbon fiber reinforced resins) 7 is placed in an obliquely arranged intermediate CFRP 12. It may be changed to The fibers of the intermediate CFRP 12 are disposed within a range of 20 ° to 60 ° with reference to the longitudinal direction L of the transverse beam portion 4b in the frame 4. Since the fibers of the intermediate CFRP 12 are disposed obliquely with respect to the longitudinal direction L, an elongation property is obtained, but it is necessary to cause breakage at the fragile portion A9, that is, the transverse beam portion 4b. Is preferably 10% or less in the thickness of the transverse beam portion 4b. For example, by using the thin intermediate CFRP 12 with respect to the thickness of the CFRP 7, the thickness of the intermediate CFRP 12 can be easily reduced to 10% or less in the thickness of the lateral beam portion 4b.

  The fiber arrangement direction may be 90 ° with respect to the longitudinal direction L. Bidirectional CFRP (carbon fiber reinforced resin) 8 may be laminated. When using bi-directional CFRP (carbon fiber reinforced resin) 8, the amount of fibers arranged in the range of 20 ° to 60 ° with respect to the amount of fibers arranged at 0 ° -90 ° is a predetermined ratio. By doing so, the initial purpose can be achieved.

[Seventh Embodiment]
As shown in FIG. 17, when the exposed portion S2 (see FIG. 11) in the bedrest frame portion 4a is used as the plastic deformation portion B3, ten unidirectional CFRPs 7 are laminated on the exposed portion S2. . At this time, the fibers of each CFRP 7 are arranged in a 45 ° direction with reference to the longitudinal direction L of the exposed portion S2 in the frame 4. Such an arrangement of the fibers can increase the elongation in the exposed portion S2. Accordingly, when a lateral impact load is applied to the frame 4, the frame 4 is deformed so as to extend at the upper corner portion C (see FIG. 13), and the impact energy can be absorbed by this portion C.

  Further, as shown in FIG. 18, in the plastically deformed portion B4, that is, the exposed portion S2 (see FIG. 11) in the bed rest frame portion 4a, the unidirectionality in which the fiber direction is arranged at 45 ° with respect to the longitudinal direction L. However, in the middle one of these layers, the fiber arrangement direction may be changed to an intermediate CFRP 14 of 20 ° or less with respect to the longitudinal direction L. Since the fibers of the intermediate CFRP 14 are arranged substantially along the longitudinal direction L, the intermediate CFRP 14 is not easily deformed by tension but is weakened by compression. Therefore, since it is necessary to cause a deformation such as stretching at the upper corner portion C (see FIG. 13) at the time of impact load, the thickness of the intermediate CFRP 14 is preferably 10% or less in the thickness of the exposed portion S2. For example, by using the thin intermediate CFRP 14 with respect to the thickness of the CFRP 7, the thickness of the intermediate CFRP 14 can be easily reduced to 10% or less in the thickness of the exposed portion S2.

  Bidirectional CFRP (carbon fiber reinforced resin) 8 may be laminated. When the bidirectional CFRP (carbon fiber reinforced resin) 8 is used, the amount of fibers arranged at 20 ° or less is set to a predetermined ratio with respect to the amount of fibers arranged at 45 °. Aim can be achieved.

  The present invention is not limited to the embodiment described above. For example, the plastic deformation sites B1 to B4 may be provided in the non-exposed portion S1.

It is a front view showing one embodiment of a sheet concerning the present invention. It is a figure which shows the 1st example of the weak part applied to the sheet | seat which concerns on this invention, (a) is a perspective view which shows an external appearance, (b) is a perspective view which shows a lamination | stacking state. It is a perspective view which shows the 2nd example of the weak part applied to the sheet | seat which concerns on this invention. It is a figure which shows the 3rd example of the weak part applied to the sheet | seat which concerns on this invention, (a) is a perspective view which shows an external appearance, (b) is sectional drawing of the part enclosed with the dashed-dotted circle. It is a perspective view which shows the lamination | stacking state in the weak part shown in FIG. It is sectional drawing which shows the 4th example of the weak part applied to the sheet | seat which concerns on this invention. It is sectional drawing which shows the 5th example of the weak part applied to the sheet | seat which concerns on this invention. It is a figure which shows the 6th example of the weak part applied to the sheet | seat based on this invention, (a) is a perspective view which shows an external appearance, (b) is sectional drawing of the part enclosed with the dashed-dotted circle. It is sectional drawing which shows the 7th example of the weak part applied to the sheet | seat which concerns on this invention. It is sectional drawing which shows the 8th example of the weak part applied to the sheet | seat which concerns on this invention. It is a front view which shows the exposed part in a flame | frame. It is a perspective view which shows the 1st example of the plastic deformation site | part applied to the sheet | seat which concerns on this invention. It is a front view which shows the deformation | transformation state in the exposed part in a flame | frame. It is a perspective view which shows the 2nd example of the plastic deformation site | part applied to the sheet | seat which concerns on this invention. It is a perspective view which shows the 9th example of the weak part applied to the sheet | seat which concerns on this invention. It is a perspective view which shows the 10th example of the weak part applied to the sheet | seat which concerns on this invention. It is a perspective view which shows the 3rd example of the plastic deformation site | part applied to the sheet | seat which concerns on this invention. It is a perspective view which shows the 4th example of the plastic deformation site | part applied to the sheet | seat which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Seat, 3 ... Seat back, 4 ... Frame, 5 ... Headrest, 7 ... Unidirectional CFRP (carbon fiber reinforced resin), 8 ... Bidirectional CFRP (carbon fiber reinforced resin), 9 ... Release film DESCRIPTION OF SYMBOLS 10 ... Aramid fiber layer, Aramid carbon mixed woven layer, A1-A10 ... Fragile part, B1-B4 ... Plastic deformation part, R1-R3 ... Step, S1 ... Unexposed part, S2 ... Exposed part, P ... Butt Seam, L: Longitudinal direction of the frame.

Claims (15)

Comprising a vertical frame extending in the vertical direction and a horizontal frame extending in the horizontal direction, comprising a frame configured to receive the lateral force by laminating a plurality of fiber-reinforced composite materials;
The frame is provided with a fragile portion that breaks when subjected to a lateral load in the lateral frame of the non-exposed portion provided with a member that covers the frame. Sheet. The sheet according to claim 1, wherein the frame is further provided with a fragile portion that breaks when subjected to a load on the longitudinal frame of the non-exposed portion.   The seat according to claim 1, wherein the member covering the lateral frame is a seat bag or a headrest.   The sheet according to claim 1, wherein the member covering the frame is a headrest, and the weakened portion has a smaller number of laminated fiber reinforced composite materials than other portions.   The sheet according to claim 1, wherein the member covering the frame is a headrest, and the fragile portion is provided with a butt joint of the fiber-reinforced composite material in a separated state.   The seat according to claim 1, wherein the member covering the frame is a seat back, and the weakened portion has a smaller number of laminated fiber reinforced composite materials than other portions.   The seat according to claim 1, wherein the member covering the frame is a seat back, and the fragile portion is provided with a step.   2. The seat according to claim 1, wherein the member covering the frame is a seat back, and the weakened portion is adjusted by a fiber direction of the fiber-reinforced composite material with reference to a longitudinal direction of the frame. . By laminating a plurality of fiber-reinforced composite materials, comprising a vertical frame extending in the vertical direction, a horizontal frame extending in the horizontal direction, and a coupling portion that couples the vertical frame and the horizontal frame. a configuration has been said frame so as responsible for the force of the lateral,
The sheet according to claim 1 , wherein the frame is provided with a plastic deformation portion at the coupling portion partially exposed from a member covering the frame.   The sheet according to claim 9, wherein the plastic deformation portion is adjusted by a fiber direction of the fiber-reinforced composite material with respect to a longitudinal direction of the frame.   The sheet according to claim 9, wherein at least one aramid fiber layer or aramid carbon mixed woven layer is provided in the plastic deformation portion. By laminating a plurality of fiber-reinforced composite materials, comprising a vertical frame extending in the vertical direction, a horizontal frame extending in the horizontal direction, and a coupling portion that couples the vertical frame and the horizontal frame. a configuration has been said frame so as responsible for the force of the lateral,
The sheet according to claim 1, wherein a release film is disposed between the laminated fiber reinforced composite materials in the joint portion. With the frame constructed from the lateral frame extending vertically frame and transversely extending vertically,
The seat according to claim 1 , wherein the fragile portion is provided in the lateral frame in a non-exposed portion where a member covering the frame is provided in the frame.   14. The seat according to claim 13, wherein the fragile portion is provided in the frame in the longitudinal frame of the non-exposed portion. Comprising a vertical frame extending vertically, and lateral frame extending in the transverse direction, a coupling portion for coupling the transverse frame and the vertical frame, the frame constructed from,
The sheet according to claim 1, wherein a plastic deformation portion is provided in the joint portion.

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