Seat back frame for a vehicle

Abstract

A seat back frame (1) for a vehicle has a first side frame (2) and a second side frame (3) disposed separately in a vehicle width direction, an upper frame (4) that links upper end portions of the first side frame (2) and the second side frame (3), and an upper bracket (6) that is attached to the upper end portion of the first side frame (2) and guides a seat belt. The first side frame (2) has a columnar member (10) composed of an aluminum alloy extruded member and having a closed cross section portion (14) in a cross section perpendicular to a vehicle up-down direction, and a plate-shaped reinforcing member (20) composed of high-tension steel and joined to the columnar member (10) and extending toward a vehicle rear of the columnar member (10).

Description

TECHNICAL FIELD

[0001] The present application relates to a seat back frame for a vehicle. BACKGROUND

[0002] In a seat back frame for a vehicle, a structure in which a seat belt is built in is known. In such a structure, a large load is applied to the seat back frame via the seat belt at the time of sudden deceleration or impact of the vehicle. Thus, in order to suppress buckling deformation from occurring, a seat back frame having high load resistance is required.

[0003] Patent Documents 1 and 2 disclose a seat back frame for a vehicle having high load resistance. In this seat back frame, the portion on the front side of the vehicle is in a closed cross-sectional shape, and high load resistance is exerted. In addition, the portion on the rear side of the vehicle is in a plate shape, and is used for joining with other various members. This seat back frame is composed of an extruded member made of an aluminum alloy, and these shapes are integrally formed. In addition, the upper portion of the seat back frame is bent toward the rear side of the vehicle, and the space above the seat surface is ensured to be wide.

[0004] Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2015-101286

[0006] [Patent Document 2] Japanese Patent Application Publication No. 2013-189089 SUMMARY

[0007] Problems to be Solved by the Invention

[0008] In the seat back frames of Patent Documents 1 and 2, complex shapes are integrally formed, so it is difficult to ensure dimensional accuracy required in design. In addition, in order to bend the upper portion of the seat back frame toward the rear side of the vehicle, bending processing needs to be performed after extrusion molding, and in particular, it is likely that adverse effects such as wrinkles and cracks occur in the portion on the rear side of the vehicle which is in a plate shape, and it becomes difficult to ensure high dimensional accuracy.

[0009] The present application relates to a seat back frame for a vehicle.

[0010] Technical Means for Solving the Problems

[0011] The present application provides a seat back frame for a vehicle,

[0012] having:

[0013] a first side frame and a second side frame which are disposed separately in the vehicle width direction;

[0014] an upper frame which links the upper end portion of the first side frame and the upper end portion of the second side frame.

[0015] an upper bracket mounted to the upper end of the aforementioned first side frame and guiding a safety belt,

[0016] The aforementioned first side frame has:

[0017] a columnar member composed of an extruded member of an aluminum alloy and having a closed cross section portion in a cross section perpendicular to the vehicle up-down direction;

[0018] a plate-shaped reinforcing member composed of high-tension steel and joined to the aforementioned columnar member and extending toward the rear of the vehicle from the aforementioned columnar member.

[0019] According to this configuration, in a seat back frame for a vehicle of the safety belt built-in type, a shape and a material that are suitable from the viewpoint of load resistance, ease of construction, and dimensional accuracy are adopted. Specifically, in the seat back frame, a compression load is applied to the front of the vehicle and a tensile load is applied to the rear of the vehicle via the safety belt at the time of sudden deceleration or impact of the vehicle. In relation to this, in the aforementioned configuration, the columnar member disposed on the front of the vehicle is composed of an extruded member of aluminum alloy having a low specific gravity and has a closed cross section portion that is strong against compression loads, so high load resistance can be achieved and weight reduction can be realized. Furthermore, the reinforcing member disposed on the rear of the vehicle is a plate shape of high-tension steel that is strong against tensile loads and low in cost, so high load resistance can be achieved and cost reduction can be realized. Here, high-tension steel refers to steel having a tensile strength of 780 MPa or more. Furthermore, even if the seat back frame has a curved shape that requires bending processing, since the reinforcing member can be joined to the columnar member after bending processing, the reinforcing member does not need to be bent, and adverse effects such as wrinkles or cracks in the reinforcing member can be suppressed. In this way, in the first side frame, the columnar member and the reinforcing member are composed of mutually separate bodies and are of suitable shapes and materials, so high load resistance can be achieved and high dimensional accuracy can be ensured with an easy construction.

[0020] The lower end of the aforementioned first side frame can also be fixed,

[0021] The lower portion of the aforementioned reinforcing member can also be larger than the upper portion in the vehicle front-rear direction.

[0022] According to 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 torque is applied to the lower portion and a relatively low bending torque is applied to the upper portion. Thus, by making the cross-sectional coefficient of the lower portion larger than that of the upper portion, the necessary load resistance can be efficiently ensured.

[0023] The yield stress of the aforementioned reinforcing member can also be 2 times or more the yield stress of the aforementioned columnar member.

[0024] According to this configuration, specific design can be performed from the viewpoint of cost.

[0025] The aforementioned columnar member can also include the aforementioned closed cross section portion, a flange portion protruding from the aforementioned closed cross section portion toward the rear of the vehicle by a length of 20 mm or more and 30 mm or less,

[0026] The aforementioned reinforcing member can also be joined to the aforementioned flange portion.

[0027] According to this configuration, the flange portion has the reinforcing member joined thereto, so manufacturing becomes easy. In particular, the flange portion has a size of 20 mm or more, so mechanical joining of an SPR (Self Piercing Rivet), a countersunk rivet, or the like can be easily performed. Furthermore, the flange portion has a size of 30 mm or less, so the configuration of the columnar member can be easily maintained. Furthermore, even in the case where the seatback frame has a curved shape, as long as the flange portion is 30 mm or less, adverse effects such as wrinkles or breaks caused by bending processing of the columnar member can be less likely to occur.

[0028] The aforementioned columnar member can also have a lower portion that extends straight, an upper portion, and a curved intermediate portion that connects the aforementioned lower portion and the aforementioned upper portion,

[0029] The aforementioned flange portion can also not protrude from the aforementioned intermediate portion, but can protrude from the aforementioned lower portion and the aforementioned upper portion.

[0030] According to this configuration, the columnar member has the curved intermediate portion, so it is possible to more broadly secure a space above the seat surface. Furthermore, since the flange portion does not protrude from the intermediate portion, it is possible to avoid the aforementioned adverse effects of wrinkles or breaks.

[0031] The aforementioned reinforcing member can also be bent as viewed in the vehicle up-down direction.

[0032] According to this configuration, the reinforcing member is bent, so it is possible to improve the rigidity of the reinforcing member. Thus, it is possible to secure higher load resistance and part rigidity. In particular, since the reinforcing member is separate from the columnar member, it is possible to variously set the shape of the reinforcing member as such.

[0033] The aforementioned closed cross section portion can also be a polygonal shape composed of a front wall located in front of the vehicle and another wall as viewed in the vehicle up-down direction,

[0034] The aforementioned front wall can also be thicker than the aforementioned another wall.

[0035] According to this configuration, the front wall is located in front of the vehicle compared to the another wall, and is subjected to a relatively large compressive load, but since the front wall is relatively thick, it is possible to effectively exhibit high load resistance.

[0036] Effects of the Invention

[0037] According to the present application, in a seat back frame for a vehicle of a seat belt built-in type, high load resistance and high dimensional accuracy can be achieved with a simple configuration. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a perspective view of a seat back frame for a vehicle according to an embodiment of the present application.

[0039] Figure 2 is a side view of a first side frame.

[0040] Figure 3 is a cross-sectional view along the line III-III of Figure 2 .

[0041] Figure 4 is a cross-sectional view corresponding to Figure 3 , showing a first modification of the first side frame.

[0042] Figure 5 is a cross-sectional view corresponding to Figure 3 , showing a second modification of the first side frame.

[0043] REFERENCE NUMERALS

[0044] 1 seat back frame

[0045] 2 first side frame

[0046] 3 second side frame

[0047] 3a lower portion

[0048] 3b upper portion

[0049] 4 upper frame

[0050] 5 lower frame

[0051] 6 upper bracket

[0052] 7 reclining mechanism

[0053] 10 columnar member

[0054] 11 lower portion

[0055] 12 upper portion

[0056] 13 intermediate portion

[0057] 14 closed cross-section portion

[0058] 14a front wall

[0059] 14b rear wall (other wall)

[0060] 14c, 14d side walls (other walls)

[0061] 15 flange portion

[0062] 16a, 16b bolt

[0063] 17a, 17b nut

[0064] 18 hoop

[0065] 20 reinforcing member

[0066] 21 SPR portion

[0067] 22 lower portion

[0068] 23 upper portion

[0069] 24 countersunk head rivet DETAILED DESCRIPTION

[0070] Embodiments of the present application will be described below with reference to the drawings.

[0071] Figure 1 A perspective view of a seat back frame 1 for an automobile according to an embodiment of the present application is shown. Figure 1 In the drawings, the outward direction in the vehicle width direction is indicated by the symbol X, the forward direction in the vehicle front-rear direction is indicated by the symbol Y, and the upward direction in the vehicle up-down direction is indicated by the symbol Z.

[0072] The seat back frame 1 has a first side frame 2 and a second side frame 3 arranged 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 arranged on the vehicle width direction outer side, and the second side frame 3 is arranged on the vehicle width direction inner side.

[0073] The seat back frame 1 has an upper frame 4 that links the upper end portions of the first side frame 2 and the second side frame 3. Further, the seat back frame 1 has a lower frame 5 that links the lower portions of the first side frame 2 and the second side frame 3. The upper frame 4 and the lower frame 5 extend in the vehicle width direction. In the present embodiment, the upper frame 4 is an aluminum alloy round pipe member, and the lower frame 5 is a high-tension steel plate member.

[0074] The seat back frame 1 is of the seat belt built-in type, and has a retractor (not shown) that winds up a seat belt, and an upper bracket 6 that guides the seat belt. In the present embodiment, the upper bracket 6 is mounted to the upper end portion of the first side frame 2 and the vehicle width direction outer end portion of the upper frame 4. Further, the retractor is mounted to the upper bracket 6. However, the retractor can also be mounted to a member other than the upper bracket 6, for example, to the lower frame 5 described later.

[0075] Figure 2 A side view of the first side frame 2 is shown. Further, Figure 3 A view alongFigure 2 a cross-sectional view of the III-III line.

[0076] The first side frame 2 is fixed to a seat cushion frame (not shown) at a lower end via a reclining mechanism 7. The first side frame 2 has a columnar member 10 of an extruded member of an aluminum alloy and a reinforcing member 20 of a high-tension steel plate. Here, the high-tension steel refers to a steel having a tensile strength of 780 MPa or more.

[0077] The columnar member 10 has a lower portion 11 extending linearly and an upper portion 12, and a curved intermediate portion 13 connecting the lower portion 11 and the upper portion 12.

[0078] The columnar member 10 has a closed cross-section portion 14 in a cross section perpendicular to the vehicle up-and-down direction. In the present embodiment, the closed cross-section portion 14 is rectangular. The closed cross-section portion 14 includes a front wall 14a located in front of the vehicle, a rear wall 14b located behind the vehicle, and side walls 14c and 14d connecting them. The front wall 14a is thicker than the other walls 14b to 14d.

[0079] In the present embodiment, the columnar member 10 further includes a flange portion 15 protruding from the closed cross-section portion 14 by a length of 20 mm or more and 30 mm or less toward the rear of the vehicle. In the present embodiment, the flange portion 15 extends continuously from the rear wall 14b toward the rear of the vehicle. Further, the flange portion 15 does not protrude from the intermediate portion 13, but protrudes from the lower portion 11 and the upper portion 12. Further, in the vehicle up-and-down direction, the flange portion 15 is provided at the entirety of the lower portion 11 and a part of the upper portion 12. That is, during manufacture, the flange portion 15 in the intermediate portion 13 and the other part of the upper portion 12 is cut away.

[0080] The reinforcing member 20 is made of a high-tension steel and is plate-shaped, extending toward the rear of the vehicle from the columnar member 10. In the present embodiment, the reinforcing member 20 is joined to the flange portion 15 of the columnar member 10 by an SPR (Self Piercing Rivet) (see an SPR portion 21). Further, the reinforcing member 20 is bent at a right angle at one place in the vehicle up-and-down direction. That is, the reinforcing member 20 is formed in a substantially L shape so as to extend in the vehicle front-and-rear direction and the vehicle width direction.

[0081] The lower portion 22 of the reinforcing member 20 is larger than the upper portion 23 in the vehicle front-and-rear direction (d2 > dl). Preferably, the length in the vehicle front-and-rear direction gradually increases from the upper portion 23 toward the lower portion 22.

[0082] In the present embodiment, the yield stress of the reinforcing member 20 is 2 times or more the yield stress of the columnar member 10. Thereby, a specific design can be made in consideration of cost. Preferably, the yield stress of the reinforcing member 20 is 3 times or more the yield stress of the columnar member 10.

[0083] In this embodiment, the first side frame 2 is fastened with respect to the reclining chair mechanism 7 by the bolts 16a, 16b and the nuts 17a, 17b. The bolt 16a penetrates the closed section portion 14 in the vehicle width direction, and is covered by the collar 18 inside the closed section portion 14. The collar 18 supports the side walls 14c, 14d in the vehicle width direction.

[0084] Referring to Figure 1 The second side frame 3 is made of high-tension steel and is plate-shaped. The second side frame 3 is bent at right angles at two places as viewed in the vehicle up-down direction, and is configured in a substantially C shape. The second side frame 3, like the reinforcing member 20 described above, has a lower portion 3a that is larger in the vehicle front-rear direction than an upper portion 3b.

[0085] The lower frame 5 links the lower portion of the reinforcing member 20 of the first side frame 2 and the lower portion of the second side frame 3.

[0086] The seat back frame 1 according to this embodiment can achieve the following effects.

[0087] In the seat back frame 1 for a vehicle of the safety belt built-in type, a shape and a material that are appropriate from the viewpoint of load resistance, ease of construction, and dimensional accuracy are adopted. Specifically, in the seat back frame 1, a compressive load is applied to the vehicle front side and a tensile load is applied to the vehicle rear side via the safety belt at the time of sudden deceleration or impact of the vehicle. In relation to this, in this embodiment, the columnar member 10 disposed on the vehicle front side is made of an extruded member of aluminum alloy having a low specific gravity, and has the closed section portion 14 that is strong against the compressive load, so it can have high load resistance and achieve weight reduction. Further, the reinforcing member 20 disposed on the vehicle rear side is a plate-shaped member made of high-tension steel that is strong against the tensile load and is low in cost, so it can have high load resistance and achieve cost reduction. Further, the seat back frame 1 of this embodiment has a curved shape that requires bending processing, but the columnar member 10 after the bending processing is joined to the reinforcing member 20, so it is not necessary to bend the reinforcing member 20, and it is possible to suppress adverse effects such as wrinkling or cracking of the reinforcing member 20. In this way, in the first side frame 2, the columnar member 10 and the reinforcing member 20 are configured separately from each other and are appropriate in shape and material, so it is possible to have high load resistance and to ensure high dimensional accuracy with an easy construction.

[0088] The lower end of the first side frame 2 is fixed, and the upper bracket 6 is disposed at the upper end, to which a load is applied via the safety belt, so a relatively high bending torque is applied to the lower portion 22 and a relatively low bending torque is applied to the upper portion 23. Thus, by making the lower portion 22 of the reinforcing member 20 larger than the upper portion 23 in the vehicle front-rear direction (d2 > dl), it is possible to make the cross-sectional coefficient of the lower portion 22 larger than that of the upper portion 23, and it is possible to effectively ensure the necessary load resistance.

[0089] The flange portion 15 is joined with the reinforcing member 20, so manufacturing becomes easy. In particular, the flange portion 15 has a size of 20 mm or more, so SPR joining can be easily performed. Further, the flange portion 15 has a size of 30 mm or less, so the configuration of the columnar member 10 can be easily maintained. Further, even when the seat back frame 1 has a curved shape, as long as the flange portion 15 is 30 mm or less, adverse effects such as wrinkles or cracks caused by bending processing of the columnar member can be prevented.

[0090] The columnar member 10 has the intermediate portion 13 in a manner curved toward the rear of the vehicle, so a space above the seat surface can be ensured more widely. Further, since the flange portion 15 does not protrude from the intermediate portion 13, the adverse effects of wrinkles or cracks described above can be avoided.

[0091] The reinforcing member 20 is bent, so the rigidity of the reinforcing member 20 can be improved. Thus, higher load resistance and part rigidity can be ensured. In particular, the reinforcing member 20 is separate from the columnar member 10, so the shape of the reinforcing member 20 can be variously set like the present embodiment and other bent shapes.

[0092] The front wall 14a is located in front of the vehicle compared to the other walls 14b to 14d, so a relatively large compression load is applied to the front wall 14a, and the front wall 14a is relatively thick, so high load resistance can be effectively exhibited.

[0093] (First Modification)

[0094] Figure 4 is a cross-sectional view corresponding to Figure 3 indicating the first modification of the first side frame 2.

[0095] In the present modification, the shape of the closed cross section portion 14 is different from the above-described embodiment, but the shape of the closed cross section portion 14 is substantially the same as the above-described embodiment except for the shape, so detailed description is sometimes omitted.

[0096] In the present modification, the closed cross section portion 14 is a trapezoidal shape. In the present modification, the front wall 14a is also thicker than the other walls 14b to 14d.

[0097] In the present modification, the bolt 16a terminal is located in the closed cross section portion 14. Therefore, a work hole H is provided in the side wall 14c in the closed cross section portion 14, and workability is improved.

[0098] As shown in the above-described embodiment and the present modification, the shape of the closed cross section portion 14 is not particularly limited, and can be, for example, an arbitrary polygonal shape.

[0099] (Second Modification)

[0100] Figure 5 is a cross-sectional view corresponding to Figure 3A cross-sectional view corresponding to the second modification of the first side frame 2.

[0101] In this modification, the columnar member 10 does not have the flange portion 15 (refer to Figure 3 , 4 ). Thus, the SPR portion 21 (refer to Figure 3 , 4 ) is not provided either, and instead, the reinforcing member 20 is joined to the columnar member 10 using the countersunk rivet 24.

[0102] The reinforcing member 20 is bent at right angles at two places as viewed in the vehicle up-down direction, i.e., is configured in a substantially C shape, and is partially disposed in front of the columnar member 10. That is, the C-shaped reinforcing member 20 is disposed so as to wrap around the columnar member 10.

[0103] The reinforcing member 20 is fastened to the front wall 14a using the countersunk rivet 24 in addition to the fastening of the bolts 16a, 16b and the nuts 17a, 17b in the above-described embodiment.

[0104] As shown in the above-described embodiment and this modification, the shape of the reinforcing member 20 is not particularly limited, and can be, for example, an arbitrary plate shape having a bent shape.

[0105] The above describes a specific embodiment of the present application and a modification thereof, but the present application is not limited to the above-described mode, and various modifications can be made within the scope of the present application.

Claims

1. A seat back frame for a vehicle, provided with: a first side frame and a second side frame arranged separately in a vehicle width direction, an upper frame linking upper end portions of the first side frame and the second side frame, an upper bracket mounted to the upper end portion of the first side frame and guiding a seat belt, the first side frame has: a columnar member composed of an extruded member of an aluminum alloy and having a closed cross section portion in a cross section perpendicular to a vehicle vertical direction, a plate-shaped reinforcing member composed of high-tension steel, engaged with the columnar member and extending toward a vehicle rear of the columnar member, the columnar member includes the closed cross section portion, a flange portion protruding toward the vehicle rear from the closed cross section portion by a length of 20 mm or more and 30 mm or less, the reinforcing member is engaged with the flange portion.

2. The seat back frame for a vehicle according to claim 1, characterized in that: a lower end portion of the first side frame is fixed, a lower portion of the reinforcing member is larger than an upper portion in a vehicle front-rear direction.

3. The seat back frame for a vehicle according to claim 1 or 2, characterized in that: a yield stress of the reinforcing member is 2 times or more a yield stress of the columnar member.

4. The seat back frame for a vehicle according to claim 1, characterized in that: the columnar member has a lower portion and an upper portion extending linearly, and a curved intermediate portion connecting the lower portion and the upper portion, the flange portion does not protrude from the intermediate portion, but protrudes from the lower portion and the upper portion.

5. The seat back frame for a vehicle according to claim 1 or 2, characterized in that: the reinforcing member is bent as viewed in a vehicle vertical direction.

6. The seat back frame for a vehicle according to claim 1 or 2, characterized in that: the closed cross section portion is a polygonal shape composed of a front wall located in a vehicle front and other walls as viewed in the vehicle vertical direction, the front wall is thicker than the other walls.

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