Automotive seat back frame

Abstract

To achieve a high load bearing capacity and secure high dimensional accuracy with a simple structure in a seat back frame for a motor vehicle having a built-in seat belt.SOLUTION: A seat back frame 1 for a motor vehicle includes: a first side frame 2 and a second side frame 3 which are disposed spaced apart from each other in a vehicle width direction; an upper frame 4 which connects an upper end of the first side frame 2 with an upper end of the second side frame 3; and an upper bracket 6 which is attached to the upper end of the first side frame 2 and guides a seat belt. The first side frame 2 has: a columnar member 10 which is formed by an extrusion material made of aluminum alloy and has a closed cross section part 14 on a cross section perpendicular to a vehicle vertical direction; and a plate-like reinforcement member 20 made of high-tension steel, joined to the columnar member 10, and extending at the vehicle rear relative to the columnar member 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a seat back frame for an automobile. [Background technology]

[0002] A seat back frame for an automobile is known to have a structure in which a seat belt is built in. In such a structure, a large load is applied to the seat back frame via the seat belt when the automobile suddenly decelerates or crashes. Therefore, a seat back frame with high load-bearing capacity is required to suppress buckling deformation.

[0003] Patent Documents 1 and 2 disclose seatback frames for automobiles with high load-bearing capacity. The front portion of the seatback frame has a closed cross-sectional shape, which provides high load-bearing capacity. The rear portion of the seatback frame is plate-shaped and can be used to join various other components. The seatback frame is made of an aluminum alloy extrusion, and these shapes are integrally formed. In addition, the upper portion of the seatback frame is curved toward the rear of the vehicle, ensuring a large space above the seat. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-101286 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-189089 Summary of the Invention [Problem to be solved by the invention]

[0005] The seatback frames of Patent Documents 1 and 2 have a complex shape that is integrally formed, making it difficult to ensure the dimensional accuracy required for the design. Furthermore, in order to curve the upper part of the seatback frame toward the rear of the vehicle, bending is required after extrusion molding, which can have adverse effects such as wrinkles and cracks, especially in the plate-shaped portion toward the rear of the vehicle, making it difficult to ensure high dimensional accuracy.

[0006] An object of the present invention is to provide a seat back frame for an automobile with a built-in seat belt that has high load-bearing capacity and ensures high dimensional accuracy with a simple structure. [Means for solving the problem]

[0007] The present invention provides a first side frame and a second side frame arranged apart in a vehicle width direction; an upper frame connecting an upper end portion of the first side frame and an upper end portion of the second side frame; an upper bracket attached to an upper end of the first side frame and guiding a seat belt; Equipped with The first side frame is a pillar-shaped member made of an aluminum alloy extrusion material and having a closed cross-sectional portion in a cross section perpendicular to the vehicle up-down direction; a plate-shaped reinforcing member made of high-tension steel, joined to the pillar-shaped member, and extending rearward of the pillar-shaped member; To provide a seat back frame for an automobile, comprising:

[0008] According to this configuration, a seatback frame for an automobile with a built-in seatbelt employs a shape and materials suitable for load-bearing capacity, structural simplicity, and dimensional accuracy. Specifically, when the vehicle suddenly decelerates or crashes, the seatback frame is subjected to a compressive load on the front side of the vehicle and a tensile load on the rear side of the vehicle via the seatbelt. In contrast, in the above configuration, the columnar member located on the front side of the vehicle is made of an extruded material made of a low-density aluminum alloy and has a closed cross-section that is resistant to compressive loads, thereby achieving high load-bearing capacity and lightweight construction. Furthermore, the reinforcing member located on the rear side of the vehicle is a plate-shaped member made of inexpensive high-tension steel that is resistant to tensile loads, thereby achieving high load-bearing capacity and low cost. Here, high-tension steel refers to steel with a tensile strength of 780 MPa or more. Furthermore, even if the seatback frame has a curved shape that requires bending, the reinforcing member can be joined to the columnar member after bending, eliminating the need to bend the reinforcing member and preventing adverse effects such as wrinkles and cracks from occurring in the reinforcing member. In this way, in the first side frame, the pillar-shaped member and the reinforcing member are formed separately from each other and have suitable shapes and materials, so that the first side frame has high load-bearing capacity and can ensure high dimensional accuracy with a simple structure.

[0009] The lower end of the first side frame may be fixed, The lower portion of the reinforcing member may be larger than the upper portion in the vehicle longitudinal direction.

[0010] With this configuration, the lower end of the first side frame is fixed and the upper bracket is disposed at the upper end, so a relatively high bending moment is applied to the lower part and a relatively low bending moment is applied to the upper part. Therefore, by making the section modulus of the lower part larger than that of the upper part, the required load-bearing capacity can be efficiently ensured.

[0011] The yield stress of the reinforcing member may be at least twice the yield stress of the columnar member.

[0012] This configuration allows for a specific design from the viewpoint of cost.

[0013] The pillar-shaped member may include the closed cross-sectional portion and a flange portion protruding rearward from the closed cross-sectional portion by a length of 20 mm or more and 30 mm or less, The reinforcing member may be joined to the flange portion.

[0014] This configuration facilitates manufacturing because the reinforcing member is joined to the flange. In particular, because the flange has a dimension of 20 mm or more, mechanical joining using SPR (self-piercing rivets) or blind rivets can be easily performed. Furthermore, because the flange has a dimension of 30 mm or less, the structure of the columnar member can be easily maintained. Even if the seatback frame has a curved shape, a flange of 30 mm or less can reduce adverse effects such as wrinkles and cracks caused by bending the columnar member.

[0015] The columnar member may have a lower portion and an upper portion extending linearly, and a curved middle portion connecting the lower portion and the upper portion, The flange portion may not protrude from the middle portion, but may protrude from the lower portion and the upper portion.

[0016] With this configuration, the columnar member has a curved middle section, which ensures a large space above the seat surface. In addition, because the flange does not protrude from the middle section, the adverse effects of wrinkles and cracks mentioned above can be avoided.

[0017] The reinforcing member may be bent when viewed from the vehicle vertical direction.

[0018] According to this configuration, since the reinforcing member is bent, the rigidity of the reinforcing member can be improved, thereby ensuring higher load-bearing capacity and component rigidity. In particular, since the reinforcing member is separate from the columnar member, the shape of the reinforcing member can be set in various ways.

[0019] The closed cross-sectional portion may have a polygonal shape formed by a front wall located in the front of the vehicle and other walls when viewed from the vehicle vertical direction, The front wall may be thicker than the other walls.

[0020] According to this configuration, the front wall is positioned further forward in the vehicle than the other walls, and therefore a relatively large compressive load is applied to it. However, since the front wall is relatively thick, it can effectively exhibit high load-bearing capacity. [Effects of the Invention]

[0021] According to the present invention, a seat back frame for an automobile with a built-in seat belt has high load-bearing capacity and can ensure high dimensional accuracy with a simple structure. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a perspective view of a seat back frame for an automobile according to an embodiment of the present invention; [Figure 2] FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view showing a first modified example of the first side frame corresponding to FIG. 3. FIG. [Figure 5] 5 is a cross-sectional view showing a second modified example of the first side frame corresponding to FIG. 3. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0024] Fig. 1 shows a perspective view of a seat back frame 1 for an automobile according to one embodiment of the present invention. In Fig. 1, the outward direction in the vehicle width direction is indicated by the symbol X, the forward direction in the vehicle longitudinal direction is indicated by the symbol Y, and the upward direction in the vehicle vertical direction is indicated by the symbol Z.

[0025] The seatback frame 1 has a first side frame 2 and a second side frame 3 that are spaced apart in the vehicle width direction. The first side frame 2 and the second side frame 3 extend in the vehicle up-down direction. The first side frame 2 is located on the outer side in the vehicle width direction, and the second side frame 3 is located on the inner side in the vehicle width direction.

[0026] The seatback frame 1 has an upper frame 4 that connects the upper ends of the first side frames 2 and the second side frames 3. The seatback frame 1 also has a lower frame 5 that connects the lower parts of the first side frames 2 and the second side frames 3. The upper frame 4 and the lower frame 5 extend in the vehicle width direction. In this embodiment, the upper frame 4 is a cylindrical member made of aluminum alloy, and the lower frame 5 is a plate member made of high-tension steel.

[0027] The seatback frame 1 has a built-in seatbelt and includes a retractor (not shown) that winds up the seatbelt and an upper bracket 6 that guides the seatbelt. In this embodiment, the upper bracket 6 is attached to the upper end of the first side frame 2 and the outer end of the upper frame 4 in the vehicle width direction. The retractor is also attached to the upper bracket 6. However, the retractor may be attached to a part other than the upper bracket 6, for example, it may be attached to the lower frame 5 described below.

[0028] Fig. 2 shows a side view of the first side frame 2. Fig. 3 shows a cross-sectional view taken along line III-III in Fig. 2.

[0029] The lower end of the first side frame 2 is fixed to a seat cushion frame (not shown) via a recliner 7. The first side frame 2 has a columnar member 10 made of an aluminum alloy extrusion material and a reinforcing member 20 made of high-tension steel plate. Here, high-tension steel refers to steel with a tensile strength of 780 MPa or more.

[0030] The columnar member 10 has a lower portion 11 and an upper portion 12 that extend linearly, and a curved middle portion 13 that connects the lower portion 11 and the upper portion 12 .

[0031] The pillar-shaped member 10 has a closed cross-sectional portion 14 in a cross section perpendicular to the vehicle vertical direction. In this embodiment, the closed cross-sectional portion 14 is rectangular. The closed cross-sectional portion 14 includes a front wall 14a located at the front of the vehicle, a rear wall 14b located at the rear of the vehicle, and side walls 14c and 14d connecting the front and rear walls. The front wall 14a is thicker than the other walls 14b to 14d.

[0032] In this embodiment, the pillar-shaped member 10 includes, in addition to the closed cross-sectional portion 14, a flange portion 15 that protrudes from the closed cross-sectional portion 14 toward the rear of the vehicle by a length of 20 mm or more and 30 mm or less. In this embodiment, the flange portion 15 extends continuously from the rear wall 14b toward the rear of the vehicle. Moreover, the flange portion 15 does not protrude from the middle portion 13, but protrudes from the lower portion 11 and the upper portion 12. Furthermore, in the vertical direction of the vehicle, the flange portion 15 is provided on the entire lower portion 11 and on a part of the upper portion 12. That is, during the manufacturing process, the flange portion 15 in the other portions of the middle portion 13 and the upper portion 12 is cut and removed.

[0033] The reinforcing member 20 is made of high-tension steel and has a plate shape that extends rearward of the pillar-shaped member 10. In this embodiment, the reinforcing member 20 is joined to the flange portion 15 of the pillar-shaped member 10 by SPR (self-piercing rivet) (see SPR portion 21). The reinforcing member 20 is also bent at a right angle at one location when viewed from the vehicle vertical direction. In other words, the reinforcing member 20 is configured in a roughly L-shape so as to extend in the vehicle longitudinal direction and the vehicle width direction.

[0034] The lower portion 22 of the reinforcing member 20 is larger in the vehicle longitudinal direction than the upper portion 23 (d2>d1). Preferably, the length in the vehicle longitudinal direction gradually increases from the upper portion 23 toward the lower portion 22.

[0035] In this embodiment, the yield stress of the reinforcing member 20 is at least twice as high as that of the columnar member 10. This allows for a specific design from the viewpoint of cost. Preferably, the yield stress of the reinforcing member 20 is at least three times as high as that of the columnar member 10.

[0036] In this embodiment, the first side frame 2 is fastened to the recliner 7 with bolts 16a, 16b and nuts 17a, 17b. The bolt 16a passes through the closed cross-sectional portion 14 in the vehicle width direction and is covered by a collar 18 within the closed cross-sectional portion 14. The collar 18 supports the side walls 14c, 14d in the vehicle width direction.

[0037] 1, the second side frame 3 is made of high-tension steel and has a plate shape. When viewed from the vertical direction of the vehicle, the second side frame 3 is bent at right angles at two locations, i.e., configured to have a roughly C-shape. Similar to the reinforcing member 20, the second side frame 3 has a lower portion 3a that is larger in the longitudinal direction of the vehicle than an upper portion 3b.

[0038] The lower frame 5 connects the lower portion of the reinforcing member 20 of the first side frame 2 and the lower portion of the second side frame 3 together.

[0039] The seat back frame 1 of this embodiment provides the following advantages.

[0040] The seatback frame 1 for automobiles with built-in seatbelts employs a shape and materials suitable for load-bearing capacity, structural simplicity, and dimensional accuracy. Specifically, in the seatback frame 1, a compressive load is applied to the front of the vehicle and a tensile load is applied to the rear of the vehicle via the seatbelt when the vehicle suddenly decelerates or collides. In contrast, in this embodiment, the columnar member 10 located on the front side of the vehicle is made of an extruded material made of a low-density aluminum alloy and has a closed cross-sectional portion 14 that is resistant to compressive loads, thereby achieving high load-bearing capacity and lightweight construction. Furthermore, the reinforcing member 20 located on the rear side of the vehicle is a plate-shaped member made of inexpensive high-tension steel that is resistant to tensile loads, thereby achieving high load-bearing capacity and low cost. Furthermore, although the seatback frame 1 of this embodiment has a curved shape that requires bending, the reinforcing member 20 can be joined to the columnar member 10 after bending, eliminating the need to bend the reinforcing member 20 and preventing adverse effects such as wrinkles and cracks from occurring in the reinforcing member 20. In this way, in the first side frame 2, the columnar member 10 and the reinforcing member 20 are constructed separately from each other and have suitable shapes and materials, so that the first side frame 2 has high load-bearing capacity and can ensure high dimensional accuracy with a simple structure.

[0041] The lower end of the first side frame 2 is fixed, the upper bracket 6 is disposed at the upper end, and a load is applied to the upper bracket 6 via the seat belt, so a relatively high bending moment is applied to the lower portion 22 and a relatively low bending moment is applied to the upper portion 23. Therefore, by making the lower portion 22 of the reinforcing member 20 larger in the vehicle fore-and-aft direction than the upper portion 23 (d2>d1), the section modulus of the lower portion 22 is made larger than that of the upper portion 23, and the required load-bearing performance can be efficiently ensured.

[0042] Since the reinforcing member 20 is joined to the flange portion 15, manufacturing is easy. In particular, since the flange portion 15 has a dimension of 20 mm or more, SPR joining can be easily performed. Furthermore, since the flange portion 15 has a dimension of 30 mm or less, the structure of the columnar member 10 can be easily maintained. Furthermore, even if the seat back frame 1 has a curved shape, if the flange portion 15 is 30 mm or less, adverse effects such as wrinkles and cracks caused by bending the columnar member can be reduced.

[0043] Since the pillar-shaped member 10 has the middle portion 13 that curves toward the rear of the vehicle, a large space can be secured above the seat surface. In addition, since the flange portion 15 does not protrude from the middle portion 13, the adverse effects of wrinkles and cracks mentioned above can be avoided.

[0044] Because the reinforcing member 20 is bent, the rigidity of the reinforcing member 20 can be improved. Therefore, higher load-bearing capacity and component rigidity can be ensured. In particular, because the reinforcing member 20 is separate from the columnar member 10, the shape of the reinforcing member 20 can be set in various ways, such as in this embodiment or other bent shapes.

[0045] Since the front wall 14a is located further forward in the vehicle than the other walls 14b to 14d, a relatively large compressive load is applied to the front wall 14a. However, since the front wall 14a is relatively thick, it can effectively exhibit high load-bearing capacity.

[0046] (First Modification) FIG. 4 shows a cross-sectional view illustrating a first modified example of the first side frame 2 corresponding to FIG.

[0047] In this modification, the shape of the closed cross-sectional portion 14 is different from that of the above embodiment, but other than the shape of the closed cross-sectional portion 14, the configuration is substantially the same as the above embodiment, and therefore detailed description may be omitted.

[0048] In this modification, the closed cross-sectional portion 14 has a trapezoidal shape. In this modification as well, the front wall 14a is thicker than the other walls 14b to 14d.

[0049] In this modified example, the bolt 16a terminates inside the closed cross-sectional portion 14. Therefore, a work hole H is provided in the side wall 14c of the closed cross-sectional portion 14, improving workability.

[0050] As shown in the above embodiment and this modification, the shape of the closed cross-sectional portion 14 is not particularly limited, and may be any polygonal shape, for example.

[0051] (Second Modification) FIG. 5 shows a cross-sectional view illustrating a second modified example of the first side frame 2 corresponding to FIG.

[0052] In this modified example, the columnar member 10 does not have a flange portion 15 (see FIGS. 3 and 4). Therefore, the SPR portion 21 (see FIGS. 3 and 4) is not provided either, and instead, a blind rivet 24 is used to join the reinforcing member 20 to the columnar member 10.

[0053] The reinforcing member 20 is bent at right angles at two locations when viewed from the top-bottom direction of the vehicle, i.e., is configured to be roughly C-shaped, and is also positioned partially forward of the pillar-shaped member 10. In other words, the C-shaped reinforcing member 20 is positioned so as to hold the pillar-shaped member 10 in its mouth.

[0054] The reinforcing member 20 is fastened to the front wall 14a by a blind rivet 24 in addition to the fastening by the bolts 16a, 16b and nuts 17a, 17b in the above embodiment.

[0055] As shown in the above embodiment and this modification, the shape of the reinforcing member 20 is not particularly limited, and may be, for example, a plate shape having any bent shape.

[0056] Although specific embodiments of the present invention and their modifications have been described above, the present invention is not limited to the above-described embodiments and can be implemented with various modifications within the scope of the present invention. [Explanation of symbols]

[0057] 1 Seat back frame 2. First side frame 3 Second side frame 3a bottom 3b upper part 4 Upper Frame 5 Lower frame 6 Upper bracket 7 Reclining Chair 10 Columnar member 11 Lower 12 Upper 13 Middle section 14 Closed section 14a front wall 14b Back wall (other walls) 14c, 14d Side walls (other walls) 15 Flange 16a, 16b bolts 17a, 17b nuts 18 colors 20 Reinforcement member 21 SPR Department 22 Lower 23 Upper 24 Blind Rivet

Claims

1. a first side frame and a second side frame arranged to be spaced apart in a vehicle width direction; an upper frame connecting an upper end portion of the first side frame and an upper end portion of the second side frame; an upper bracket attached to an upper end of the first side frame and guiding a seat belt; Equipped with The first side frame is a pillar-shaped member made of an aluminum alloy extrusion material and having a closed cross-sectional portion in a cross section perpendicular to the vehicle up-down direction; a plate-shaped reinforcing member made of high-tension steel, joined to the pillar-shaped member, and extending rearward of the pillar-shaped member; and the pillar-shaped member includes the closed cross-sectional portion and a flange portion that protrudes rearward from the closed cross-sectional portion by a length of 20 mm or more and 30 mm or less, The reinforcing member is joined to the flange portion.

2. The lower end of the first side frame is fixed to the seat cushion frame, 2. The seat back frame for an automobile according to claim 1, wherein a lower portion of the reinforcing member is larger than an upper portion in the longitudinal direction of the vehicle.

3. 3. The seat back frame for an automobile according to claim 1, wherein the yield stress of the reinforcing member is at least twice as large as the yield stress of the columnar member.

4. the columnar member has a lower portion and an upper portion that extend linearly, and a curved middle portion that connects the lower portion and the upper portion; 2. The seat back frame for an automobile according to claim 1, wherein the flange portion does not protrude from the middle portion, but protrudes from the lower portion and the upper portion.

5. 3. The seat back frame for an automobile according to claim 1, wherein the reinforcing member is bent when viewed from the vertical direction of the vehicle.

6. the closed cross-sectional portion has a polygonal shape formed by a front wall located in the front of the vehicle and other walls when viewed from the vehicle vertical direction, 3. The seat back frame for an automobile according to claim 1, wherein the front wall is thicker than the other walls.

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