Seat back frame for a vehicle and method of manufacturing the same

Abstract

The car seat backrest frame (1) comprises: a first side frame (2) and a second side frame (3) separately arranged in the vehicle width direction; an upper frame (4) connecting the upper end (2a) of the first side frame (2) and the upper end (3a) of the second side frame (3); and an upper bracket (7) mounted on the upper end (2a) of the first side frame (2) and guiding the seat belt. The first side frame (2) is an extruded part extending in the vertical direction of the vehicle, and its lower end (2b) is fixed. The first side frame (2) has a closed section (10) in a cross section perpendicular to the vertical direction of the vehicle. The upper end (2a) of the first side frame (2) is crushed towards the rear of the vehicle, and the thickness of the upper end (2a) in the longitudinal direction of the vehicle is smaller than that of the lower end (2b).

Description

Technical Field

[0001] This invention relates to a car seat back frame and its manufacturing method. Background Technology

[0002] In automotive seat backrest frames, it is known that a built-in seat belt is incorporated. In such a design, during rapid deceleration or a collision, the seat belt applies a significant load to the seat backrest frame. Therefore, to suppress buckling deformation, a seat backrest frame with high load-bearing capacity is required.

[0003] Patent Document 1 discloses a seat back frame for automobiles with high load-bearing capacity. In this seat back frame, the side frames have a closed cross-section shape, resulting in high load-bearing capacity. Furthermore, by bending the upper part of the seat back frame towards the rear of the vehicle and partially cutting it off, more space above the seat surface can be ensured, making getting in and out of the vehicle easier.

[0004] Existing technical documents

[0005] Patent Documents Japanese Patent Application Publication No. 2015-101286.

[0006] In the seat back frame of Patent Document 1, a portion of the side frame with a closed cross-section needs to be cut off. Such a process is complex and difficult in terms of manufacturing procedures, and is preferably omitted. Therefore, there is room for improvement from the perspective of simplifying manufacturing. Summary of the Invention

[0007] The problem to be solved by the present invention

[0008] The objective of this invention is to achieve a structure with high load-bearing capacity and easy manufacturing in a seat belt-integrated automotive seat back frame and its manufacturing method.

[0009] Methods for solving problems

[0010] The first aspect of the present invention provides a car seat back frame.

[0011] have:

[0012] The first side frame and the second side frame are separately configured in the vehicle width direction.

[0013] The upper frame connecting the upper end of the aforementioned first side frame and the upper end of the aforementioned second side frame.

[0014] The upper bracket, which is installed at the aforementioned upper end of the first side frame and guides the seat belt,

[0015] The aforementioned first side frame is an extruded part extending along the vertical direction of the vehicle, with its lower end fixed.

[0016] The aforementioned first side frame has a closed section in a cross-section perpendicular to the vertical direction of the vehicle.

[0017] The aforementioned upper end of the first side frame is crushed towards the rear of the vehicle, and the thickness of the aforementioned upper end of the first side frame in the vehicle longitudinal direction is smaller than that of the aforementioned lower end of the first side frame.

[0018] With this configuration, the first side frame has a closed cross-section, thus exhibiting high load-bearing capacity. Furthermore, the upper end of the first side frame is crushed rearwards, ensuring ample space above the seat surface for easier entry and exit. Additionally, the lower end of the first side frame is fixed, while the upper end is equipped with an upper bracket for guiding the seatbelt. During rapid deceleration or a collision, the upper bracket applies a high load in the generally forward direction of the vehicle, resulting in a relatively high bending torque applied to the lower end and a relatively low bending torque applied to the upper end. In contrast, because the upper end is crushed rearwards, making it smaller than the lower end, the section modulus of the lower end can be larger than that of the upper end, effectively ensuring the necessary load-bearing capacity.

[0019] Alternatively, the aforementioned closed section may have a pair of sidewalls that are separately arranged in the vehicle width direction.

[0020] The aforementioned pair of sidewalls fold inward toward the inner side of the aforementioned closed section at the aforementioned upper end of the aforementioned first side frame as the aforementioned crushing occurs.

[0021] This configuration allows for easy maintenance of the appearance of the first side frame and styling to meet design requirements. Furthermore, even under loads from sudden deceleration or impacts, the pair of side walls support each other, ensuring high load-bearing capacity.

[0022] Alternatively, each of the aforementioned pair of sidewalls may have a groove at the aforementioned lower end of the aforementioned first side frame that is recessed toward the inside of the aforementioned closed section.

[0023] With this configuration, the first side frame is an extruded part, so the upper and lower ends are formed in the same shape during extrusion molding. In the above configuration, since a groove is provided in the lower end, a groove is also provided in the upper end before it is crushed. Using such grooves, the upper end can be easily crushed, and unintended deformation can be suppressed.

[0024] Multiple through holes may also be provided in the central part of the front-rear direction of the aforementioned pair of side walls.

[0025] With this configuration, weight reduction can be achieved by providing multiple through holes. Furthermore, multiple through holes distribute the load more evenly compared to a single, continuous hole, resulting in higher load-bearing capacity. Additionally, the presence of multiple through holes at the upper end facilitates crushing. Moreover, if a load is applied to the first side frame via the upper bracket during rapid vehicle deceleration or an impact, bending deformation may occur in the first side frame. However, since the central portion of the pair of side walls in the vehicle's longitudinal direction is located near the neutral axis of this bending deformation, the stress occurring in this central portion is low, and even with multiple through holes, strength reduction can be suppressed.

[0026] Alternatively, the aforementioned multiple through holes can be configured with a higher density, especially above the vehicle.

[0027] With this configuration, the section modulus of the lower part is greater than that of the upper part, which can effectively ensure the necessary load-bearing performance.

[0028] Alternatively, the aforementioned closed-section portion may have a rear portion, a front portion, and a middle portion at the aforementioned lower end of the aforementioned first side frame, in order of increasing size in the vehicle width direction.

[0029] Alternatively, the aforementioned closed section portion may not have the aforementioned middle portion at the aforementioned upper end of the aforementioned first side frame, but may have the aforementioned front portion and the aforementioned rear portion that are welded together.

[0030] With this configuration, the upper part can be crushed by pushing the front part to the rear part during the manufacturing process, which makes the crushing process and subsequent welding process easier.

[0031] A second aspect of the present invention provides a method for manufacturing a car seat back frame.

[0032] The car seat backrest frame includes: a first side frame and a second side frame separately arranged in the vehicle width direction; an upper frame connecting the upper end of the first side frame and the upper end of the second side frame; and an upper bracket mounted on the upper end of the first side frame and guiding the seat belt.

[0033] This includes the following steps.

[0034] The aforementioned first side frame is extruded in a manner that creates a closed section in a cross-section perpendicular to the vertical direction of the vehicle.

[0035] By crushing the upper end of the aforementioned first side frame toward the rear of the vehicle, the thickness of the upper end of the aforementioned first side frame in the vehicle longitudinal direction is made smaller than that of the lower end of the aforementioned first side frame.

[0036] According to this method, similarly to the above, in the manufacturing method of the seat back frame of an automobile with built-in seat belt, a structure with high load-bearing performance and easy manufacturing can be achieved.

[0037] Alternatively, the aforementioned closed section may have a pair of sidewalls that are separately arranged in the vehicle width direction.

[0038] Alternatively, in the aforementioned extrusion molding process, a groove recessed towards the inside of the aforementioned closed section can be formed on the sidewalls of the aforementioned pair.

[0039] According to this method, since an initial irregularity is applied to the pair of sidewalls toward the inside of the closed section, it is possible to suppress the bending of the pair of sidewalls toward the outside of the closed section when the upper end is crushed.

[0040] The aforementioned method for manufacturing a car seat back frame may also include:

[0041] An opening that increases in size as it rises above the vehicle is formed at the upper end of the aforementioned first side frame.

[0042] Welding is performed continuously after the aforementioned crushing occurs, in a manner that seals the aforementioned opening.

[0043] According to this method, weight reduction can be achieved by forming openings. Furthermore, the opening amount is adjusted so that the section modulus increases towards the bottom of the vehicle, thus effectively ensuring the necessary load-bearing capacity. Additionally, both weight reduction and high load-bearing capacity can be achieved even when the openings are closed by welding. Here, continuous welding refers to linear welding, not spot welding.

[0044] The effects of the invention

[0045] According to the present invention, in the seat belt-integrated automotive seat back frame and the method thereof, a structure with high load-bearing capacity and easy manufacturing can be achieved. Attached Figure Description

[0046] Figure 1 This is a perspective view of an automotive seat back frame according to an embodiment of the present invention.

[0047] Figure 2 This is a side view of the first side frame.

[0048] Figure 3 It is along Figure 2 A sectional view along line III-III.

[0049] Figure 4 It is along Figure 2 A cross-sectional view along line IV-IV.

[0050] Figure 5 This is a side view showing a first variant of the first side frame.

[0051] Figure 6 This is a side view showing a second variant of the first side frame.

[0052] Figure 7 yes Figure 6 The first step diagram of the manufacturing method of the first side frame.

[0053] Figure 8 yes Figure 6 The second step diagram of the manufacturing method of the first side frame.

[0054] Figure 9 yes Figure 6 The third step diagram of the manufacturing method of the first side frame.

[0055] Figure 10 yes Figure 6 The fourth step of the manufacturing method for the first side frame.

[0056] Explanation of reference numerals in the attached figures

[0057] 1 Seat back frame

[0058] 2 First side frame

[0059] 2a upper end

[0060] 2b lower end

[0061] 2c Central Department

[0062] 3 Second side frame

[0063] 3a upper end

[0064] 3b lower end

[0065] 4. Upper frame

[0066] 5. Lower Frame

[0067] 6 frameworks

[0068] 7. Upper bracket

[0069] 8 reclining chair mechanism

[0070] 10 Closed Section

[0071] 10a front

[0072] 10b rear

[0073] 10c middle section

[0074] 11 Anterior Wall

[0075] 12 Rear Wall

[0076] 13 and 14 side walls

[0077] 13a and 14a grooves

[0078] 15 through holes

[0079] 16a and 16b bolts

[0080] 17a and 17b nuts

[0081] 18a, 18b hoop

[0082] 19 starting hole

[0083] 20. Opening. Detailed Implementation

[0084] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0085] Figure 1 This is a perspective view of a car seat back frame 1 according to an embodiment of the present invention. Figure 1 In the vehicle width direction, the symbol X indicates the outward direction; in the vehicle front-to-back direction, the symbol Y indicates the forward direction; and in the vehicle vertical direction, the symbol Z indicates the upward direction.

[0086] The seat back frame 1 has a first side frame 2 and a second side frame 3 separately configured in the vehicle width direction. The first side frame 2 and the second side frame 3 extend in the vehicle vertical direction. The first side frame 2 is configured on the outer side in the vehicle width direction, and the second side frame 3 is configured on the inner side in the vehicle width direction.

[0087] The seat back frame 1 has an upper frame 4 that connects the upper end 2a of the first side frame 2 and the upper end 3a of the second side frame 3. Furthermore, the seat back frame 1 has a lower frame 5 that connects the lower end 2b of the first side frame 2 and the lower end 3b of the second side frame 3. Additionally, the seat back frame 1 has a middle frame 6 that connects the central portion of the first side frame 2 and the central portion of the second side frame 3. In this embodiment, the upper frame 4, lower frame 5, and middle frame 6 are aluminum alloy tubular components extending along the width direction of the vehicle. Furthermore, in this embodiment, the second side frame 3 and the upper frame 4 are constructed as separate parts, but this is not a limitation; they could also be constructed as a single unit.

[0088] The seat back frame 1 is a seat belt-integrated type, featuring a retractor (not shown) for retracting the seat belt and an upper bracket 7 for guiding the seat belt. The upper bracket 7 is mounted on the upper end 2a of the first side frame 2 and the outer end of the upper frame 4 in the vehicle width direction. Furthermore, the retractor is mounted on the upper bracket 7. Alternatively, the retractor may also be mounted, for example, on the middle frame 6. In this case, the seat belt extends forward from the rear of the seat back frame 1 via the upper bracket 7.

[0089] Figure 2 A side view of the first side frame 2 is shown. Figure 3 Show along Figure 2 A sectional view along line III-III. Figure 4 Show along Figure 2 A cross-sectional view along line IV-IV.

[0090] The first side frame 2 is an extruded part extending in the vertical direction of the vehicle. In this embodiment, the first side frame 2 is an extruded part made of aluminum alloy. The lower end 2b of the first side frame 2 is fixed to the seat cushion frame (not shown) via the recliner mechanism 8.

[0091] The upper end 2a of the first side frame 2 is crushed towards the rear of the vehicle. In this embodiment, not only the upper end 2a, but also approximately the upper half of the first side frame 2 is crushed towards the rear of the vehicle, with the crushing becoming more pronounced towards the top of the vehicle. Furthermore, the lower end 2b of the first side frame 2 is not crushed, maintaining its shape as it was during extrusion molding. Therefore, compared to the lower end 2b, the thickness of the upper end 2a in the longitudinal direction of the vehicle is smaller. Figure 2 In the middle, D1 < D2).

[0092] The first side frame 2 has a closed section 10 in a cross-section perpendicular to the vertical direction of the vehicle. In this embodiment, the closed section 10 includes a front wall 11 located at the front of the vehicle, a rear wall 12 located at the rear of the vehicle, and a pair of side walls 13 and 14 connecting them. The pair of side walls 13 and 14 are arranged opposite each other in the width direction of the vehicle. Each of the pair of side walls 13 and 14 has a groove 13a and 14a at its lower end 2b that is recessed inward toward the closed section 10.

[0093] In this embodiment, the closed section portion 10 comprises a front portion 10a located at the front of the vehicle, a rear portion 10b located at the rear of the vehicle, and an intermediate portion 10c (grooves 13a, 14a) between them. The front portion 10a and the rear portion 10b are equal in size in the vehicle width direction. Figure 4 In the middle section, D3 = D4), the width of the vehicle in the middle section 10c is smaller than theirs ( Figure 4 In the middle, D5 < D3, D4).

[0094] The pair of sidewalls 13 and 14 fold inward toward the closed section 10 in the upper end 2a as a result of the aforementioned crushing. Figure 3 (Refer to). That is, the intermediate portions 10c (grooves 13a, 14a) narrow in the vehicle's longitudinal direction and are formed deeper into the closed section portion 10. In the intermediate portions 10c (grooves 13a, 14a), the folded-in pair of sidewalls 13, 14 abut and support each other. Alternatively, in the intermediate portions 10c (grooves 13a, 14a), the folded-in pair of sidewalls 13, 14 may not abut and may separate. Furthermore, when they abut as in this embodiment, bonding with an adhesive may be performed, for example.

[0095] In this embodiment, the first side frame 2 is fastened relative to the recliner mechanism 8 by means of bolts 16a and 16b and nuts 17a and 17b. Bolts 16a and 16b respectively penetrate the front part 10a and rear part 10b of the closed section portion 10 in the vehicle width direction, and are respectively covered by hoop rings 18a and 18b within the closed section portion 10. Hoop rings 18a and 18b support side walls 13 and 14 in the vehicle width direction.

[0096] Reference Figure 1 The second side frame 3 is made of high-tensile steel and is plate-shaped. Viewed from above and below the vehicle, the second side frame 3 bends at two right angles, forming a roughly C-shape. The lower end 3b of the second side frame 3 is larger than the upper end 3a in the longitudinal direction of the vehicle.

[0097] Next, the manufacturing method of the above-mentioned automotive seat backrest frame 1 will be described. Hereinafter, the manufacturing method of the first side frame 2 will be mainly described.

[0098] First, the first side frame 2 is extruded to form a closed section 10 in a cross-section perpendicular to the vertical direction of the vehicle. During this extrusion, grooves 13a and 14a, recessed towards the inside of the closed section 10, are also formed in conjunction on a pair of sidewalls 13 and 14. Next, the upper end portion 2a of the first side frame 2 is crushed towards the rear of the vehicle. At this time, the lower end portion 2b is not crushed, maintaining the shape formed during extrusion. As a result, the thickness of the upper end portion 2a in the longitudinal direction of the vehicle is reduced compared to the lower end portion 2b. Figure 2 In the middle, D1 < D2). Furthermore, the seat back frame 1 is formed by combining the first side frame 2 with the second side frame 3, upper frame 4, lower frame 5, middle frame 6, upper bracket 7, and reclining chair mechanism 8. Figure 1 reference).

[0099] The seat back frame 1 according to this embodiment achieves the following effects.

[0100] The first side frame 2 has a closed section 10, thus exhibiting high load-bearing capacity. Furthermore, the upper end 2a of the first side frame 2 is crushed towards the rear of the vehicle, thereby ensuring ample space above the seat and facilitating easy entry and exit. Additionally, the lower end 2b of the first side frame 2 is fixed, and an upper bracket 7 is positioned on the upper end 2a. A high load is applied towards the front of the vehicle via the upper bracket 7, resulting in a relatively high bending torque on the lower end 2b and a relatively low bending torque on the upper end 2a. In contrast, by crushing the upper end 2a towards the rear of the vehicle without crushing the lower end 2b, the section modulus of the lower end 2a can be made larger than that of the upper end 2b, effectively ensuring the necessary load-bearing capacity.

[0101] In the upper end 2a, as the aforementioned crushing occurs, the pair of side walls 13, 14 fold inward toward the closed section 10. This allows for easy maintenance of the appearance of the first side frame 2 and fulfillment of the required shape arrangement. Furthermore, even when the vehicle is subjected to load during rapid deceleration or a collision, the pair of side walls 13, 14 support each other, ensuring high load-bearing capacity.

[0102] The pair of sidewalls 13 and 14 are provided with initial irregularities (grooves 13a and 14a) towards the inside of the closed section portion 10, so that when the upper end portion 2a is crushed, the pair of sidewalls 13 and 14 can be prevented from bending outward towards the closed section portion 10.

[0103] (First variation)

[0104] Figure 5 Indicates and Figure 2 The corresponding sectional view shows the first modified example of the first side frame 2.

[0105] In this modified example, a plurality of through holes 15 are provided on a pair of side walls 13, 14 of the first side frame 2 in the above embodiment. Specifically, a plurality of through holes 15 are provided in a vertical arrangement at the center of the pair of side walls 13, 14 in the vehicle longitudinal direction.

[0106] In this embodiment, each of the plurality of through holes 15 is circular, and five holes are provided. At the upper end 2a, it is deformed into an elliptical shape as it is crushed during the crushing process.

[0107] The multiple through holes 15 are arranged in a higher density closer to the top of the vehicle. That is, the vertical spacing of the multiple through holes 15 (the distance between the center points D6 to D9) becomes shorter closer to the top of the vehicle. Figure 5 In the order of D6 < D7 < D8 < D9), multiple through holes 15 can be arranged at equal intervals, with the larger holes formed towards the top of the vehicle.

[0108] According to this modified example, weight reduction is achieved by providing multiple through holes 15. Furthermore, multiple through holes 15 distribute the load more evenly than a single continuous hole, thus providing high load-bearing capacity. Additionally, the multiple through holes 15 in the upper end 2a facilitate crushing processing. Moreover, if the vehicle decelerates rapidly or experiences a collision, a load is applied to the first side frame 2 via the upper bracket 7, potentially causing bending deformation of the first side frame 2. However, the central portion of the pair of side walls 13 and 14 in the vehicle's longitudinal direction is located near the neutral axis of this bending deformation, resulting in low stress in this central portion. Therefore, even with multiple through holes 15, strength reduction can be suppressed.

[0109] Furthermore, by increasing the density of the multiple through holes 15 towards the top of the vehicle, the lower section modulus of the first side frame 2 is made larger than that of the upper section, which effectively ensures the necessary load-bearing performance.

[0110] (Second variation)

[0111] Figure 6 Indicates and Figure 2 The corresponding sectional view shows a second variant of the first side frame 2.

[0112] In this modified example, it is not simply a matter of crushing the upper end 2a of the first side frame 2, but also partially cutting off the upper end 2a, and continuously welding it by crushing the cut-off portion together (see reference). Figure 6 (W, the oblique region). Here, continuous welding refers to linear welding, not spot welding.

[0113] Figures 7-10 The diagrams show the first to fourth steps of the manufacturing method of the first side frame 2 in this modified example. Figures 7-10 The diagram shows a side view in the center, a top view at the top, and a bottom view at the bottom. Additionally, the top and bottom views show the shapes of the upper and lower surfaces, respectively.

[0114] Refer to the first process Figure 7 The first side frame is extruded in such a way that it has a closed section 10 in a cross-section perpendicular to the vertical direction of the vehicle. In this modified example, the closed section 10 includes a rear section 10b, a front section 10a, and a middle section 10c in order of increasing size in the vehicle width direction. Figure 7 In this process, the upper end 2a and the lower end 2b have the same shape. Furthermore, after extrusion molding, a starting hole 19 is formed on a pair of sidewalls 13 and 14. In the illustrated example, the starting hole 19 is circular and located approximately in the center of the vehicle in the vertical direction.

[0115] Refer to the second process Figure 8An opening 20 is formed at the upper end 2a of the first side frame 2, with the opening increasing in size as it moves towards the top of the vehicle. In the illustrated example, the opening 20 extends from the upper end 2a to the central portion 2c. The opening 20 is a right-angled triangle with the starting hole 19 as the starting point and the upper end as one side. As a result, the middle portion 10c of the upper end 2a is removed.

[0116] Refer to the third process shown Figure 9 The upper end portion 2a is crushed towards the rear of the vehicle by abutting against and closing the opening 20 with the front portion 10a and the rear portion 10b. At this time, the lower end portion 2b is not crushed and maintains the shape formed during extrusion molding. As a result, the thickness of the upper end portion 2a in the vehicle's longitudinal direction becomes smaller than that of the lower end portion 2b. Figure 9 , D13<D14).

[0117] Refer to the fourth process Figure 10 At the upper end 2a, the front part 10a and the rear part 10b are continuously welded together (see reference). Figure 10 The diagonal area W). In the illustrated example, the front part 10a and the rear part 10b are welded linearly in the vertical direction of the vehicle. Moreover, the first side frame 2 is combined with the second side frame 3, the upper frame 4, the lower frame 5, the middle frame 6, the upper bracket 7, and the reclining chair mechanism 8 to form the seat back frame 1 ( Figure 1 reference).

[0118] According to this modified example, the upper end 2a can be crushed by pushing the front part 10a against the rear part 10b, thus making the crushing process and subsequent welding process easier.

[0119] Furthermore, weight reduction is achieved by forming the opening 20. Moreover, the opening 20 is adjusted in such a way that the section modulus increases towards the lower part of the vehicle, thus effectively ensuring the necessary load-bearing capacity. Additionally, even when the opening 20 is closed by welding, both weight reduction and high load-bearing capacity are achieved. Furthermore, in this modified example, the pair of sidewalls 13 and 14 do not abut against each other and therefore do not support each other, but the load can be transmitted along the longitudinal direction of the vehicle via the sidewalls 13 and 14 respectively, ensuring high load-bearing capacity.

[0120] The above describes specific embodiments and variations of the present invention, but the present invention is not limited to the above methods and can be implemented with various modifications within the scope of the present invention. For example, an embodiment of the present invention can also be formed by appropriately combining the contents of various embodiments.

Claims

1. A car seat back frame, have: The first side frame and the second side frame are separately configured in the vehicle width direction. The upper frame connecting the upper end of the aforementioned first side frame and the upper end of the aforementioned second side frame. The upper bracket, which is installed at the aforementioned upper end of the first side frame and guides the seat belt, The aforementioned first side frame is an extruded part extending along the vertical direction of the vehicle, with its lower end fixed. The aforementioned first side frame has a closed section in a cross-section perpendicular to the vertical direction of the vehicle. The aforementioned upper end of the first side frame is crushed towards the rear of the vehicle, and the thickness of the aforementioned upper end of the first side frame in the vehicle's longitudinal direction is smaller than that of the aforementioned lower end of the first side frame. The aforementioned closed-section portion has a rear portion, a front portion, and a middle portion at the aforementioned lower end of the aforementioned first side frame, in order of increasing size in the vehicle width direction. The aforementioned closed section portion does not have the aforementioned middle portion at the aforementioned upper end of the aforementioned first side frame, but has the aforementioned front portion and the aforementioned rear portion that are welded together.

2. The automotive seat back frame according to claim 1, characterized in that, The aforementioned closed section has a pair of sidewalls that are arranged opposite each other in the vehicle width direction. The aforementioned pair of sidewalls fold inward toward the inner side of the aforementioned closed section at the aforementioned upper end of the aforementioned first side frame as the aforementioned crushing occurs.

3. The automotive seat back frame according to claim 2, characterized in that, Each of the aforementioned pair of sidewalls has a groove at the aforementioned lower end of the aforementioned first side frame that is recessed toward the inside of the aforementioned closed section.

4. The automotive seat back frame according to claim 2, characterized in that, Multiple through holes are provided in the central part of the front-rear direction of the aforementioned pair of side walls.

5. The automotive seat back frame according to claim 4, characterized in that, The aforementioned through holes are arranged in a higher density above the vehicle.

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