Seat back frame

Abstract

To support a seat belt with high strength by a simple structure.SOLUTION: A seat back frame is provided with a first belt guide 15 for inserting a seat belt B1 delivered from a seat belt winding device B, and a second belt guide 16 different from the first belt guide 15 for inserting the seat belt B1 delivered from the seat belt winding device B. The load from the seat belt B1 is dispersed and received by the first belt guide 15 and the second belt guide 16, thereby supporting the seat belt with high strength.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to Seat back frame this.

Background Art

[0002] In Japanese Patent Application Laid-Open No. 2018-184037, a guide wire for guiding a seat belt was provided at the upper center of a pipe frame constituting a seat back frame of a vehicle seat. The guide wire passes the seat belt fed out from a belt winding mechanism provided below it from below. And the guide wire guides the seat belt so as to fold it back downward to the front side (see Patent Document 1).

[0003] Further, in Japanese Patent Application Laid-Open No. 2017-226376, the seat back frame is composed of a panel frame and a pipe frame, and the seat belt is passed through a gap between the upper part of the pipe frame and the panel frame (see Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The seat back frame of Patent Document 1 supports the seat belt with a guide wire. Therefore, it has been difficult to ensure sufficient support strength against a large load applied from the seat belt. Furthermore, the seat back frame described in Patent Document 2 has a structure through which the seat belt passes in the gap between the pipe frame and the panel frame. Therefore, the seat back requires resin protective parts on both the pipe frame side and the panel frame side to prevent the seat belt from directly rubbing against the pipe frame and the panel frame, which has resulted in a problem of increased complexity in the structure supporting the seat belt.

[0006] This invention was made in view of the above circumstances, and its objective is to support a seat belt with high rigidity using a simple configuration. [Means for solving the problem]

[0007] To solve the above problems, the invention described in claim 1 relates to a seat back frame, A first belt guide through which the seat belt unwound from the seat belt retractor passes, A second belt guide, separate from the first belt guide, through which the seat belt unwound from the seat belt retractor passes, Equipped with It is.

[0008] Furthermore, the invention described in claim 1 is, Equipped with a pipe frame, The first belt guide and the second belt guide are characterized in that they are mounted along the circumferential surface of the pipe frame.

[0009] The invention described in claim 2 is the same as claim 1 In the seat back frame described above, Both the first belt guide and the second belt guide consist of a U-shaped wire. Both the first belt guide and the second belt guide are attached such that one end and the other end of the wire are mounted along the circumferential surface of the pipe frame. When the seat back frame is positioned with one side forward and the other side backward, the seat belt insertion portion of the first belt guide extends forward from the center of the seat belt retractor, while the seat belt insertion portion of the second belt guide does not extend forward from the center of the seat belt retractor.

[0010] The invention described in claim 3 is the same as claim 1 or claim 2 In the seat back frame described above, Both the first belt guide and the second belt guide consist of a U-shaped wire. When the seat back frame is positioned with one side facing forward and the other side facing backward, both the first belt guide and the second belt guide are attached so that one end and the other end of the wire are along the circumferential surface of the pipe frame. The end of the first belt guide on the seat belt insertion side extends forward from the upper part of the pipe circumferential surface of the pipe frame, and the end of the second belt guide on the seat belt insertion side extends forward from the lower part of the pipe circumferential surface of the pipe frame.

[0011] The invention described in claim 4 is the same as claim 3 In the seat back frame described above, The first belt guide and the second belt guide are characterized by being made of members of the same shape.

[0012] The invention described in claim 5 is the same as claim 1 In the seat back frame described above, The pipe frame is provided along the outer edge of the seat back frame, The pipe frame has connecting members arranged vertically inside it, The connecting member is characterized in that it is bent to bypass the first belt guide or the second belt guide, and its upper end is connected to the pipe frame.

[0013] The invention described in claim 6 is the same as claim 1 In the seat back frame described above, The first belt guide and the second belt guide are characterized by being formed of an integrated single member.

[0014] The invention described in claim 7 is the same as claim 1 In the seat back frame according to [reference], it includes a panel frame joined to the pipe frame, and the panel frame has a relief portion that avoids the first belt guide and the second belt guide with respect to the attachment portions of the first belt guide and the second belt guide on the pipe frame.

Advantages of the Invention

[0015] The invention according to claim 1 has a first belt guide and a second belt guide through which a seat belt fed out from a seat belt retractor is inserted. Therefore, even when a large load is applied to the seat belt, the load applied from the seat belt can be dispersed to the first belt guide and the second belt guide, and it is possible to improve the support strength with a simple structure.

[0016] Furthermore, claim 1 In the described invention, since the first belt guide and the second belt guide are attached along the circumferential surface of the pipe of the pipe frame, it is possible to widely secure the area of the attachment surface and improve the attachment strength. Also, by attaching each belt guide along the circumferential surface of the pipe, when a load is applied to each belt guide in a specific direction, the force is likely to be applied along the circumferential surface, which is the attachment surface, rather than in the direction in which the attachment surface peels off, to the attachment surface with the pipe frame. For this reason, each belt guide is unlikely to come off from the pipe frame, and it is possible to improve the strength against the load.

[0017] Claim 2 In the described invention, the insertion portions of the first belt guide and the second belt guide are located on the front side and the rear side with respect to the center of the seat belt retractor. Therefore, when the seat belt is fed out from the seat belt retractor to the front side of the seat back frame through the second belt guide and the first belt guide, each belt guide can guide well. Furthermore, when a load is applied from the seat belt, the insertion portions of the first and second belt guides can be appropriately distributed, suppressing any unevenness in the load applied to each belt guide. Therefore, it is possible to improve the strength against load. Furthermore, because the second belt guide is located behind the center of the seat belt retractor, the load that separates the seat belt retractor from its mounting position through the seat belt when a large load is applied to the seat belt can be reduced. Therefore, it is possible to improve the mounting strength of the seat belt retractor B.

[0018] Claim 3 In the described invention, the end of the first belt guide on the seat belt insertion side extends forward from the upper part of the pipe surface of the pipe frame, and the end of the second belt guide on the seat belt insertion side extends forward from the lower part of the pipe surface of the pipe frame. Therefore, when a load is applied to the seat belt, the force applied to each belt guide is less likely to be generated in a direction that promotes separation from the pipe surface of the pipe frame, and can be directed in a direction along the pipe surface, thereby improving the strength against load.

[0019] Claim 4 In the described invention, since the first belt guide and the second belt guide are made of members of the same shape, it is possible to simplify manufacturing and reduce manufacturing costs by standardizing parts.

[0020] Claim 5 The described invention provides a pipe frame along the outer edge of the seat back frame, and a connecting member positioned inside the pipe frame is bent to bypass the first or second belt guide, with its upper end connected to the pipe frame. This makes it possible to properly secure the mounting position of the first or second belt guide. Furthermore, regardless of the arrangement of the first or second belt guide, it becomes possible to position the connecting member inside the pipe frame, thereby improving the frame strength.

[0021] Claim 6 The invention described above makes it possible to reduce the number of parts, lower manufacturing costs, and reduce weight, as the first belt guide and the second belt guide are made of a single, integrated component.

[0022] Claim 7 The described invention makes it possible to avoid interference between each belt guide and the panel frame because the panel frame has a clearance portion for the mounting portions of the first and second belt guides in the pipe frame. Furthermore, since the panel frame is made of panel material, it is easy to form a clearance portion by creating irregularities, which makes it easy to secure the mounting portion for each belt guide and increases the degree of freedom in arranging the mounting portions. [Brief explanation of the drawing]

[0023] [Figure 1] This is a front view of the seat back frame according to the first embodiment. [Figure 2] This is a rear view of the seat back frame. [Figure 3] This is a perspective view of the seat back frame. [Figure 4] This is a partial perspective view of the upper center of the seat back frame. [Figure 5] Enlarged front view of the upper center of the seat back frame [Figure 6] This is a cross-sectional view of the seat back frame along line AA in Figure 1. [Figure 7] This is a front view of the seat back frame according to the second embodiment. [Figure 8] This is a perspective view of the belt guide according to the third embodiment. [Figure 9] This is a front view of the seat back frame according to the fourth embodiment. [Figure 10] This is a front view of the seat back frame according to the fifth embodiment. [Figure 11] This is a front view of the seat back frame according to the sixth embodiment. [Figure 12] This is a front view of the seat back frame according to the seventh embodiment. [Figure 13] This is a front view of the seat back frame according to the eighth embodiment. [Modes for carrying out the invention]

[0024] [First Embodiment] An embodiment of the seat back frame will be described with reference to Figures 1 to 6. However, while various technically preferable limitations are attached to the following embodiments for carrying out the present invention, the scope of the present invention is not limited to the following embodiments and illustrated examples. This embodiment is a seat back frame applied to the backrest of a bench seat for a vehicle. Vehicles equipped with bench seats to which the seat back frame shown below is applied include all vehicles that carry and transport people, such as ships, aircraft, and cars. However, in this embodiment, the application of the seat back frame to a bench seat of a vehicle, particularly an automobile, is given as an example.

[0025] For example, a bench seat in a car has a seat cushion that serves as the seating area, a seat back that serves as the backrest, and a headrest. For example, in the case of a three-seater bench seat, the seat back is composed of the left seat back which forms the seat back of the center seat and the left seat, and the seat back of the right seat. Each seatback consists of a seatback frame that forms the skeleton, a pad material made of cushioning material, and a surface material made of fabric or the like that covers these components. The following embodiments will be described as seatback frames used for the left seatback.

[0026] Figure 1 is a front view of the seat back frame 100 according to the first embodiment, Figure 2 is a rear view, and Figure 3 is a perspective view. In the figures of this embodiment, the directions up, down, left, right, front, and back all indicate the direction when the seat back frame 100 is installed in a vehicle. The following descriptions of each part of the seat back frame 100 will be based on the directions when it is installed. In Figure 1, the front of the page is "front" and the back is "rear," and when facing forward, the left side is "left" and the right side is "right." Furthermore, although each seat back frame 100 is strictly mounted to the vehicle with its upper end slightly tilted backward, for the sake of explanation, unless otherwise specified, the surface of each seat back frame 100 shall be assumed to be aligned in the vertical and horizontal directions.

[0027] The seat back frame 100 mainly consists of a pipe frame 20, a panel frame 30 which is a plate-shaped member serving as a back panel, a support bracket 40 for the seat belt retractor B, a mounting bracket 50 for the locking device, headrest frames 11 and 12, armrest brackets 13 and 14, a first belt guide 15, a second belt guide 16, a tether member 17, and a set bracket 18.

[0028] [Pipe frame] The pipe frame 20 has first to fourth pipe members 21 to 24.

[0029] The first pipe member 21 has a left frame section 211, a right frame section 212, and an upper frame section 213. The first pipe member 21 is formed by bending a single pipe material to create the left frame section 211, the right frame section 212, and the upper frame section 213. This reduces the number of parts and simplifies the manufacturing of the pipe frame 20, as well as reducing costs. The left frame section 211 and the right frame section 212 are positioned at the left and right ends of the seat back frame 100, respectively. Both the left frame section 211 and the right frame section 212 are oriented parallel to each other in the vertical direction. The upper frame section 213 connects the upper end of the left frame section 211 and the upper end of the right frame section 212. The upper frame section 213 is positioned parallel to the left-right direction at the upper end of the seat back frame 100.

[0030] The left frame section 211, the right frame section 212, and the upper frame section 213 have a circular cross-section and are formed by bending a single metal pipe, such as steel, into a roughly U-shape. This reduces weight, simplifies manufacturing, and lowers costs.

[0031] Furthermore, among the first to fourth pipe members 21 to 24, the second to fourth pipe members 22 to 24 are made of metal pipes with the same outer diameter, while the first pipe member 21 is made of metal pipe with a larger outer diameter than the second to fourth pipe members 22 to 24. The first pipe members 21 are located at the upper end and both left and right ends of the seat back frame 100. The lower end of the seat back frame 100 is supported by the vehicle body. Therefore, by positioning the first pipe members 21, which have higher rigidity, at the upper end and both left and right ends, which are separated from the lower end supported by the vehicle body, the seat back frame 100 maintains high rigidity as a whole. Furthermore, since the first pipe member 21 is positioned to surround the entire plane of the seat back frame 100, it also increases the overall rigidity of the plane of the seat back frame 100.

[0032] The second pipe member 22 is made of a straight metal pipe, such as steel, with a circular cross-section. The second pipe member 22 is positioned parallel to the left-right direction at the lower end of the seat back frame 100. The second pipe member 22 corresponds to the lower frame. The second pipe member 22 has its left and right ends joined to the lower ends of the left frame portion 211 and the right frame portion 212 of the first pipe member 21. As a result, the first pipe member 21 and the second pipe member 22 form a rectangular frame along the outer edge of the seat back frame 100.

[0033] The second pipe member 22 has both its left and right ends compressed and flattened. Correspondingly, the lower ends of the left frame section 211 and the right frame section 212 are also processed so that the rear portions of their respective outer surfaces, which are the pipe circumferential surfaces, are flattened. The second pipe member 22 and the left frame section 211 and the right frame section 212 are joined together by welding their flat surfaces. In this way, the first pipe member 21 and the second pipe member 22 are joined with high strength by joining their planes together.

[0034] In the following description, "joining" refers to joining by welding, more preferably by laser welding. However, it is not limited to laser welding; other welding methods such as spot welding or arc welding may be used, or joining methods other than welding may be employed.

[0035] Furthermore, a portion of the second pipe member 22 between its left-right middle section and its left end is compressed to form a flat section 221. This flat section 221 is planar in shape along the front-rear and left-right directions. The lower end of the tether member 17, which will be described later, is joined to the front surface of the flat section 221.

[0036] The third pipe member 23 has a circular cross-section and is made of a straight metal pipe such as steel. The third pipe member 23 is arranged vertically inside the pipe frame 20. The upper end of the third pipe member 23 is joined to the upper frame portion 213 of the first pipe member 21. The lower end of the third pipe member 23 is joined to the second pipe member 22. The third pipe member 23 corresponds to a connecting member that connects the middle portion of the upper frame portion 213 to the middle portion of the second pipe member 22, which is the lower frame portion.

[0037] The upper and lower ends of the third pipe member 23 are both compressed and processed to be flat. Similarly, the joint portion of the upper frame portion 213 with the third pipe member 23 is also processed so that the rear part of the outer surface of the pipe is flat. Likewise, the joint portion of the second pipe member 22 with the third pipe member 23 is also processed so that the rear part of the outer surface of the pipe is flat. As a result, the third pipe member 23, the first pipe member 21, and the second pipe member 22 are joined with high strength through planar joints.

[0038] The third pipe member 23 is fixed inside the pipe frame 20 in a position aligned with the vertical direction. This provides rigidity to the seat back frame 100 against bending stress with a horizontal axis in the inner region of the pipe frame 20. Furthermore, it is possible to suppress deflection that causes the gap between the upper frame portion 213 and the second pipe member 22 in the pipe frame 20 to expand or contract.

[0039] The fourth pipe member 24 is made of a straight metal pipe, such as steel, with a circular cross-section. The fourth pipe member 24 is positioned parallel to the left and right between the left frame portion 211 of the first pipe member 21 and the third pipe member 23. The left end of the fourth pipe member 24 is joined to the vertically intermediate portion of the left frame portion 211. The right end of the fourth pipe member 24 is joined to the vertically intermediate portion of the third pipe member 23. The fourth pipe member 24 corresponds to a transverse member that crosses between the connecting member and either the left or right frame (side frame), connecting their respective intermediate portions.

[0040] The left and right ends of the fourth pipe member 24 are both compressed and flattened. Similarly, the joint portion between the left frame portion 211 and the fourth pipe member 24 is also processed so that the rear part of the outer surface of the pipe is flat. Likewise, the joint portion between the third pipe member 23 and the fourth pipe member 24 is also processed so that the rear part of the outer surface of the pipe is flat. As a result, the fourth pipe member 24, the first pipe member 21, and the third pipe member 23 are joined with high strength through planar joints.

[0041] The fourth pipe member 24 is fixed inside the pipe frame 20, to the left of the third pipe member 23, in a position aligned with the left-right direction. This provides rigidity to the seat back frame 100 against bending stress with a vertical axis in the region to the left of the third pipe member 23 inside the pipe frame 20. Furthermore, the area to the right of the third pipe member 23 inside the pipe frame 20 is narrower in width than the area to the left. Therefore, the upper frame portion 213 of the first pipe member 21 and the second pipe member 22 ensure sufficient rigidity against bending stress in the vertical direction in this right-side area. On the other hand, the left-side region of the pipe frame 20 is wider than the left-side region. Therefore, in addition to the upper frame portion 213 and the second pipe member 22, the fourth pipe member 24 ensures high rigidity.

[0042] Furthermore, the fourth pipe member 24 can suppress deflection that causes the gap between the left frame portion 211 and the third pipe member 23 in the pipe frame 20 to expand or contract.

[0043] [Panel frame] As shown in Figures 1 to 3, the panel frame 30 is positioned behind the pipe frame 20. The panel frame 30 is made of a metal plate such as steel or aluminum alloy. The panel frame 30 has a generally rectangular surface shape when viewed from the front. The panel frame 30 has a width that is roughly equal to that of the pipe frame 20 in both the vertical and horizontal directions. Therefore, the panel frame 30 is integrally joined to the pipe frame 20 in the front-to-back direction, with the pipe frame 20 overlapping it with almost no overhang.

[0044] As shown in Figure 2, the panel frame 30 has a low, periphery-wall-like flange portion 301 that extends forward along almost the entire circumference of its outer edge. Note that a portion of this flange portion 301 is removed by cutting or other means. This flange portion 301 provides the panel frame 30 with the rigidity necessary to maintain its overall planar shape.

[0045] As shown in Figure 2, the panel frame 30 can divide its flat surface into multiple regions, including a first region P1, a second region P2, a third region P3, and a fourth region P4.

[0046] The first part P1 is the region enclosed by the right frame portion 212, the upper frame portion 213, the second pipe member 22, and the third pipe member 23 of the first pipe member 21, in a front view of the panel frame 30. The first part P1 is located behind the occupant sitting in the center seat when the seat back frame 100 is incorporated into a three-seater bench seat.

[0047] The second part P2 is the region enclosed by the left frame portion 211, the upper frame portion 213, the second pipe member 22, and the third pipe member 23 of the first pipe member 21, in a front view of the panel frame 30. The second part P2 is located behind the occupant sitting on the left seat when the seat back frame 100 is incorporated into a three-seater bench seat.

[0048] The third part P3 is the region located behind the third pipe member 23 in a front view of the panel frame 30. The fourth part P4 is located behind the first pipe member 21 and the second pipe member 22 in a front view of the panel frame 30. The fourth part P4 corresponds to the entire outer edge of the panel frame 30.

[0049] The panel frame 30 has a plurality of first reinforcing portions 311 within the first to third portions P1 to P3, which are convex portions that bulge forward in a band shape relative to the reference surface, when the rearmost surface is taken as the reference surface. The first reinforcing portions 311 are recessed forward when viewed from the rear side. Among the multiple first reinforcing sections 311, some have different vertical lengths and horizontal widths, but all are formed in a bead shape that follows the vertical direction. By providing the first reinforcing portion 311 that bulges forward along the vertical direction in this manner, the panel frame 30 can be given high rigidity against bending stress with an axis in the left-right direction perpendicular to the longitudinal direction of the first reinforcing portion 311.

[0050] In the following explanation, the term "reinforcement section" refers to a part or component that has higher rigidity than a flat plate due to a three-dimensional structure such as a protruding strip, frame-like structure, protrusion, or bent section.

[0051] Within the first section P1, three vertically elongated first reinforcing sections 311 are formed side by side. The first reinforcing section 311 located in the middle is wider than the first reinforcing sections 311 on either side. The central first reinforcing section 311 has multiple circular through holes 311a formed vertically at uniform intervals. These multiple through holes 311a contribute to reducing the weight of the panel frame 30. Furthermore, since each through hole 311a is formed within the plane of the bulging area of ​​the first reinforcing section 311, the first reinforcing section 311 itself is reinforced so that the rigidity is not reduced by the through holes 311a.

[0052] Within the second section P2, four first reinforcing sections 311 are formed in a row from left to right. The rightmost first reinforcing section 311 is shorter in height and is formed below the mounting position of the support bracket 40 of the seat belt retractor B. Multiple through holes 311a are also formed in this first reinforcing section 311, arranged vertically. Furthermore, the two first reinforcing sections 311 on the left side are divided vertically by an opening 32, which will be described later. In addition, multiple through holes 311a are formed in these two first reinforcing sections 311, arranged vertically.

[0053] At the rightmost end of the second section P2, above the aforementioned rightmost first reinforcing section 311, a first joining reinforcing section 312 is formed to which the rear side of the support bracket 40 of the seat belt retractor B is joined. This first joining reinforcing section 312 is located approximately in the center of the entire plane of the panel frame 30, more precisely, slightly above the center and slightly to the left of the center, that is, at the left end of the second section P2. Furthermore, in the vertical direction, the first joining reinforcing section 312 is located between two second joining reinforcing sections 314, which are arranged vertically in the third section P3 and will be described later. Therefore, the first joint reinforcement portion 312 is positioned within the range where the rigidity is increased by the two second joint reinforcement portions 314, and deflection and orientation fluctuations of the support bracket 40 of the seat belt rewinding device B supported by the first joint reinforcement portion 312 can be suppressed.

[0054] The first joint reinforcement portion 312 is circular in front view and protrudes forward. The first joint reinforcement portion 312 is recessed forward when viewed from the rear side. The first joint reinforcement portion 312 has a circular flat surface in the center, with this flat surface located at the very front. The area around the first joint reinforcement portion 312 is sloped such that the amount of forward protrusion increases the closer it is to the central flat surface. Note that the front view shape of the first joint reinforcement portion 312 is not limited to a circle; it may also be rectangular or polygonal, but a circle is the easiest to manufacture. Furthermore, the first joint reinforcement portion 312 may be formed in a spherical shape. In that case as well, it is preferable to provide a flat surface in the center.

[0055] The central flat surface of the first joint reinforcement portion 312 is joined to the rear surface of the support bracket 40 of the seat belt retractor B. Because the first joint reinforcement portion 312 has an uneven structure on the surface of the panel frame 30, the rigidity of the first joint reinforcement portion 312 and its surroundings is increased. As a result, the seat belt retractor B is firmly supported via the support bracket 40. Furthermore, when a load is received from the seat belt B1 through the seat belt retractor B, the first joint reinforcement portion 312 can suppress deflection and deformation around it.

[0056] Within the second part P2, near the left end and slightly below the midpoint in the vertical direction, a roughly rectangular opening 32 is formed that penetrates from front to back. A tether member 17 is provided on the front side of the periphery of this opening 32.

[0057] The tether member 17 is a component for attaching the child seat to a seat equipped with a seat back frame 100. The tether member 17 has a rod-shaped portion capable of engaging with the hooks provided on the child seat. The tether member 17 is made of a rigid, roughly U-shaped wire and has a horizontal bar portion and a pair of left and right vertical bar portions extending downward from both ends of the horizontal bar portion. The left vertical bar portion is shorter in length than the right and is joined to the pipe circumferential surface, which is the outer circumferential surface of the left frame portion 211 of the first pipe member 21. The right vertical bar portion is long enough to reach the second pipe member 22, and its lower end is joined to the flat portion 221 of the second pipe member 22. The tether member 17 is also joined to the front side of the periphery of the opening 32, on both the left and right sides of the opening 32. The tether member 17 is positioned such that its horizontal bar crosses the middle section of the opening 32 in the vertical direction on the front side of the opening 32 of the second part P2 of the panel frame 30. In other words, the opening 32 is a relief hole to prevent the panel frame 30 from interfering when the child seat hooks are fastened.

[0058] The opening 32 is located in the middle of the two first reinforcing parts 311 in the vertical direction, so as to divide the two first reinforcing parts 311. A peripheral reinforcing portion 313 is formed around the opening 32, bulging forward to surround the opening 32. The peripheral reinforcing portion 313 is recessed towards the front when viewed from the rear side. Therefore, this surrounding reinforcement portion 313 reinforces the plate surface to prevent a decrease in rigidity caused by the opening 32 that penetrates it.

[0059] At the lower part of the third section P3, two first reinforcing sections 311 are formed side by side on the left and right. Furthermore, above the two first reinforcing parts 311 in the third section P3, two second joining reinforcing parts 314 are formed side by side, one above the other, to which the pipe circumferential surface of the third pipe member 23 of the pipe frame 20 is joined. In a plan view, the third pipe member 23 joined to the second joint reinforcement 314 is positioned to pass between the two first reinforcement parts 311. In this case, the forward projection height of the two first reinforcement parts 311 may be set to the height at which they contact the pipe surface of the third pipe member 23, and they may be joined together. This holds the third pipe member 23 between the two first reinforcement parts 311. Therefore, the tilting of the third pipe member 23 is suppressed, and deflection when a load is applied to the seat back frame 100 can be suppressed.

[0060] The upper and lower second joint reinforcement portions 314 are both circular in shape when viewed from the front and protrude forward. When viewed from the rear, the second joint reinforcement portions 314 are recessed forward. In addition, each second joint reinforcement portion 314 has a larger diameter than the first joint reinforcement portion 312 described above. Each second joint reinforcement portion 314 also has a circular flat surface in the center, with this flat surface protruding furthest forward. The area around each second joint reinforcement portion 314 is sloped such that the amount of forward protrusion increases the closer it is to the central flat surface. The front view shape of each second joint reinforcement portion 314 is not limited to a circle; it may also be rectangular or polygonal. Furthermore, each second joint reinforcement portion 314 may be formed in a spherical shape, but it is preferable to provide a flat surface in the center.

[0061] As described above, the central flat surface of each second joint reinforcement portion 314 is joined to the rear of the pipe circumferential surface of the third pipe member 23 at two locations, upper and lower. At this time, the joining portion at the rear of the pipe circumferential surface of the third pipe member 23 may be pressurized to form a flat surface. This joins the flat surfaces together, making it possible to more firmly connect each second joint reinforcement portion 314 and the third pipe member 23. Furthermore, since there are two second joint reinforcement sections 314, one above and one below, the third pipe member 23 is held in two places, both above and below. As a result, the third pipe member 23 can be firmly held in a position parallel to the top and bottom. Consequently, bending in the direction of inclination of each part of the pipe frame 20 along the vertical or horizontal directions can be effectively suppressed. Furthermore, each second joint reinforcement portion 314 also has an uneven structure relative to the surface of the panel frame 30, thereby increasing the rigidity of each second joint reinforcement portion 314 and its surroundings. As a result, the third pipe member 23 can be firmly supported, and deflection and deformation of the surrounding area can be suppressed.

[0062] The fourth section P4 is a rectangular frame-shaped region surrounding the first to third sections P1 to P3. The upper and lower planes of the fourth section P4 are located in front of the reference plane. Therefore, stepped reinforcement sections 315 are formed along the left-right direction near the boundary between the upper part of the fourth section P4 and the other sections P1 to P3, and near the boundary between the lower part of the fourth section P4 and the other sections P1 to P3. Since the upper and lower stepped reinforcement sections 315 are aligned along the left-right direction, high rigidity can be imparted to the panel frame 30 against bending stress with the vertical axis.

[0063] Furthermore, third joint reinforcement portions 316 are formed on the left and right sides of the upper end of the fourth portion P4, respectively. The upper end of the fourth portion P4 is located in front of the reference plane, but each of the third joint reinforcement portions 316 protrudes further forward from there. Also, the third joint reinforcement portions 316 are recessed forward when viewed from the rear side. Each third joint reinforcement portion 316 is rectangular in front view and has an inclined surface that curves diagonally upward and forward relative to its periphery. Each third joint reinforcement portion 316 has this inclined surface joined to the pipe circumferential surface, which is the outer circumferential surface of the upper frame portion 213 of the first pipe member 21, thereby fixing the first pipe member 21. Because the third joint reinforcement portion 316 has an uneven structure on the surface of the panel frame 30, the rigidity of the third joint reinforcement portion 316 and its surroundings is increased. Furthermore, because the third joint reinforcement portion 316 is an inclined surface, it can suppress the vertical movement of the first pipe member 21.

[0064] Furthermore, fourth joint reinforcement portions 317 are formed at the lower left end and the upper and lower right ends of the fourth portion P4, respectively. Each fourth joint reinforcement portion 317 protrudes forward. When viewed from the rear side, the fourth joint reinforcement portion 317 is recessed forward. The fourth joint reinforcement portion 317 has a generally rectangular flat surface in the center, and this flat surface protrudes furthest forward.

[0065] The flat surfaces of each fourth joint reinforcement portion 317 are joined to the pipe circumferential surface, which is the outer surface of either the left frame portion 211 or the right frame portion 212 of the first pipe member 21. Because the fourth joint reinforcement portion 317 has an uneven structure relative to the surface of the panel frame 30, the rigidity of the fourth joint reinforcement portion 317 and its surroundings is increased. The joint portion between the pipe circumferential surface, which is the outer surface of the first pipe member 21, and the fourth joint reinforcement portion 317 may be pressurized to form a flat surface. This increases the strength of the joint between them. In addition, this suppresses the mutual deflection of the pipe frame 20 and the panel frame 30.

[0066] Furthermore, at the lower end of the fourth section P4, three fifth joint reinforcement sections 318 are formed side by side on the left and right. Each fifth joint reinforcement section 318 protrudes forward. When viewed from the rear side, the fifth joint reinforcement section 318 is recessed forward. The fifth joint reinforcement 318 has a generally rectangular flat surface in the center, and this flat surface protrudes furthest forward.

[0067] The flat surfaces of each fifth joint reinforcement portion 318 are joined to the pipe circumferential surface, which is the outer surface of the second pipe member 22. Because the fifth joint reinforcement portion 318 has an uneven structure relative to the panel surface of the panel frame 30, the rigidity of the fifth joint reinforcement portion 318 and its surroundings is increased. The joint portion between the second pipe member 22 and the fifth joint reinforcement portion 318 on the pipe circumferential surface may be pressurized to form a flat surface. This increases the strength of the joint between them. In addition, this suppresses the mutual deflection of the pipe frame 20 and the panel frame 30.

[0068] Furthermore, in the area directly below the first part P1 at the lower end of the fourth part P4, two undulating connecting parts 33 are formed side by side on the left and right, with the inner portion of each undulating connecting part 33 being raised diagonally upwards and forwards by inverted, roughly U-shaped notches. The inclined surface of each undulating connecting part 33, which is raised diagonally upwards and forwards, is joined to the pipe surface of the second pipe member 22, thereby fixing the second pipe member 22.

[0069] A roughly rectangular notch 34 is formed in the left-right center of the upper end of the fourth part P4, extending downward from the upper edge. This notch 34 reaches the upper ends of the second part P2 and the third part P3. The first belt guide 15 and the second belt guide 16 are attached to the upper frame portion 213 of the first pipe member 21 in a position that is in front of the notch 34. The roughly rectangular cutout 34 serves as a relief section to avoid interference with the upper end of the panel frame 30 when passing the seat belt or components attached to the seat belt through the first belt guide 15 and the second belt guide 16.

[0070] Figure 4 is a partial perspective view of the upper center of the seat back frame 100. As mentioned above, the upper plane of the fourth part P4 is located in front of the reference plane, and with respect to this upper plane, the left and right sides of the notch 34 are second reinforcing parts 319 consisting of protrusions that project backward. The second reinforcing parts 319 are recessed backward when viewed from the front. The second reinforcement section 319 maintains high rigidity around the notch 34, thereby suppressing the reduction in rigidity caused by the notch 34. Furthermore, the flat surface of the second reinforcing portion 319 is located behind the upper plane of the fourth portion P4. In addition, both the notch 34 and the second reinforcing portion 319 have a flange portion 301 formed on the outer edge of the panel frame 30 partially removed. Due to these structures, the flat surface of the second reinforcing portion 319 is spaced rearward from the pipe circumferential surface of the upper frame portion 213 of the first pipe member 21. Moreover, the rearward-spaced structure of the second reinforcing portion 319 functions as a clearance portion to avoid interference with the first belt guide 15 and the second belt guide 16 joined to the upper frame portion 213.

[0071] [Support bracket for seat belt retractor] Figure 5 is an enlarged front view of the upper central part of the seat back frame 100. As shown in Figures 1 to 5, the support bracket 40 of the seat belt retractor B is located slightly above the center of the front surface of the panel frame 30. The support bracket 40 is formed by sheet metal processing of a metal plate such as steel or aluminum alloy. The support bracket 40 has a support portion 41 that fixes and supports the seat belt retractor B, and a connecting portion 42 that is joined to the third pipe member 23. The support portion 41 is flat and has a hole for inserting a bolt 43. The head of the bolt 43, which is inserted from the rear, is fixed to the rear surface of the support portion 41 by welding. The seat belt retractor B is fixed to the support portion 41 by the shaft of the bolt 43, which protrudes forward, and a nut (not shown). Furthermore, the rear surface of the support portion 41 is joined to the flat surface of the first joint reinforcement portion 312. A gap is formed between the support portion 41 and the panel frame 30 in areas other than the joint with the first joint reinforcement portion 312.

[0072] The support bracket 40 is located to the left of the third pipe member 23. The connecting portion 42 extends diagonally to the front right from the right end of the support portion 41. The extended end of the connecting portion 42 embraces the third pipe member 23 by wrapping around the front portion of the pipe surface of the third pipe member 23. The rear surface of the extended end of the connecting portion 42 is joined to the third pipe member 23. Furthermore, bead-shaped reinforcing portions 421 are formed at the upper and lower ends of the connecting portion 42, bulging forward along the extension direction. These reinforcing portions 421 can provide the connecting portion 42 with high rigidity against bending stress with an axis in the vertical direction perpendicular to the extension direction.

[0073] The support bracket 40 not only supports the seat belt retractor B, but also contributes to improving the connection strength between the panel frame 30 and the pipe frame 20 through the connecting portion 42. Furthermore, the connecting portion 42 suppresses the deflection and tilting of the third pipe member 23, contributing to improving the rigidity of the seat back frame 100. Furthermore, since the support bracket 40 is supported by the third pipe member 23 via the connecting portion 42, it is no longer necessary to support the pipe frame 20 with a support frame that extends across both the left and right ends, as in the conventional design, and the support frame can be omitted. This eliminates the feeling of foreign objects that occupants of the bench seat may experience due to the support frame. Furthermore, since the first joint reinforcement portion 312 that supports the support bracket 40 from behind has a convex structure, it is possible to achieve both support for the support bracket 40 and improvement of the rigidity of the panel frame 30.

[0074] The seat belt retractor B has a cylindrical main body that is fixed to the support bracket 40 in a horizontal position. The seat belt retractor B has a retraction shaft connected to a retraction spring inside its main body, which allows it to retract the seat belt B1. The seat belt retractor B can also pull out the seat belt B1 from the top of its main body, and the retraction spring constantly applies tension to pull the pulled-out seat belt B1 back into the main body. Furthermore, the seat belt retractor B incorporates a retaining mechanism to prevent the seat belt B1 from being pulled out suddenly.

[0075] The seat belt retractor B has an opening for unwinding the seat belt B1 at the top of its main body, and immediately above it is a plate-shaped seat belt B1 insertion guide B2 with a slit. The insertion guide B2 guides the seat belt B1 upward as it is unwinded from the opening of the seat belt retractor B.

[0076] [First and second belt guides] Figure 6 is a cross-sectional view along line AA in Figure 1. As shown in Figures 4 to 6, both the first belt guide 15 and the second belt guide 16 guide the seat belt B1, which is unwound from the seat belt retractor B, through a predetermined unwinding direction.

[0077] The first belt guide 15 and the second belt guide 16 are both identical components formed by bending a rigid metal wire into the same shape. The first belt guide 15 and the second belt guide 16 are both attached to the left-right center of the upper frame portion 213 of the first pipe member 21. As shown in Figures 5 and 6, the first belt guide 15 and the second belt guide 16 are positioned in a manner that substantially coincides with the unwinding opening of the seat belt retractor B in the left-right direction.

[0078] The first and second belt guides 15 and 16 consist of wires formed in a roughly U-shape. The first belt guide 15 has a pair of arms 151, each consisting of one end and the other end of a wire extending in the same direction, and an insertion portion 152 connecting the pair of arms 151. The insertion portion 152 extends from one arm 151 to the other arm 151, forming an annular portion through which the seat belt B1 is inserted. The second belt guide 16 has a pair of arm portions 161, each consisting of one end and the other end of a wire extending in the same direction, and an insertion portion 162 connecting the pair of arm portions 161. The insertion portion 162 also forms an annular portion between one arm portion 161 and the other arm portion 161.

[0079] The pair of arms 151 of the first belt guide 15 and the pair of arms 161 of the second belt guide 16 are both curved in a concentric arc shape. Each of the arms 151 and 161 is joined to the pipe circumferential surface of the upper frame portion 213 of the first pipe member 21 in the left-right direction. The inner diameter of each of the arms 151 and 161 is approximately the same as the outer diameter of the upper frame portion 213. As a result, the inner circumference of each of the arms 151 and 161 can contact the pipe circumferential surface of the upper frame portion 213 over a wide area, allowing for a strong and secure connection. Furthermore, the pair of arms 151 of the first belt guide 15 and the pair of arms 161 of the second belt guide 16 are joined with a slight offset in the left-right direction so as not to interfere with each other.

[0080] The first belt guide 15 is located in the left-right central part of the upper frame portion 213, with the insertion portion 152 side extending forward and slightly downward from the upper part of the pipe circumference of the upper frame portion 213. The second belt guide 16 extends forward and downward from the lower part of the pipe surface of the upper frame portion 213 at the center of the upper frame portion 213, with the insertion portion 162 side extending forward. The insertion portion 162 of the second belt guide 16 has a greater downward inclination than the insertion portion 152 of the first belt guide 15.

[0081] Furthermore, as shown in Figure 6, the extended end of the insertion portion 152 of the first belt guide 15 extends forward from the center B3 of the seat belt retractor B. Furthermore, the extended end of the insertion portion 162 of the second belt guide 16 extends forward of the panel frame 30, but does not reach forward of the center B3 of the seat belt retractor B. Note that the center B3 of the seat belt retractor B refers to the position of its central axis if the outer shape of the seat belt retractor B is approximately cylindrical. Alternatively, the position of the rotation center of the retraction shaft of the seat belt B1 may be defined as center B3. In this embodiment, regardless of which side is considered the center B3, the front-to-back positional relationship between the extended end of the insertion portion 152 of the first belt guide 15 and the extended end of the insertion portion 162 of the second belt guide 16 is maintained.

[0082] When the seat belt retractor B is installed on the seat back frame 100, the seat belt B1 unwound from the seat belt retractor B must first be guided above the occupant's shoulders, then its path bends and it is guided diagonally downwards and forwards. Because the insertion portion 162 of the second belt guide 16 is arranged as described above, it is easy to insert the seat belt B1, which is unwound upward from the unwinding opening provided at the rear of the upper end of the seat belt retractor B, from rear to front. Since the insertion portion 162 has a round bar portion that runs in the left-right direction at its tip, it is possible to guide the seat belt B1, which has been inserted through the inside, to curve its path forward along the outer surface of the round bar portion. The first belt guide 15 also has a round bar portion that runs in the left-right direction at the tip of its insertion portion 152. And, because the insertion portion 152 of the first belt guide 15 is positioned above and in front of the insertion portion 162 of the second belt guide 16, as described above. For this reason, the insertion portion 152 of the first belt guide 15 can guide the seat belt B1, which has been guided forward by the insertion portion 162, by bending its path downward along the round bar portion from a higher position than the insertion portion 162. Therefore, the first belt guide 15 and the second belt guide 16 can properly guide the seat belt B1 to the seated person.

[0083] [Headrest frame] As shown in Figures 1 and 3, the headrest frames 11 and 12 are provided on the left and right sides of the upper frame portion 213 of the first pipe member 21. Both headrest frames 11 and 12 are formed from a relatively large outer diameter metal wire. The headrest frames 11 and 12 consist of a wire formed in a roughly U-shape, with a pair of rod-shaped portions extending upward both bent downwards. The folded rod-shaped portions of the headrest frames 11 and 12 are joined to the front portion of the outer circumferential surface of the upper frame portion 213.

[0084] The left headrest frame 11 has a pair of folded rod-shaped sections, both of which are curved backward near the lower ends, and the rear portion above these curved sections is joined to the upper frame section 213. The joint portion of the upper frame section 213 with the headrest frame 11 may be machined flat to follow the rod-shaped sections of the headrest frame 11. With the headrest frame 11 joined to the upper frame 213, the lower ends of the pair of rod-shaped portions of the headrest frame 11 are in contact with the front side of the panel frame 30. The lower ends of the pair of rod-shaped portions of the headrest frame 11 may also be joined to the front of the panel frame 30.

[0085] The right-side headrest frame 12 has a pair of folded rod-shaped sections, each with a lower end curved backward in an arc shape, and the inner circumference of these curved sections is joined to the outer surface of the upper frame section 213. The inner diameter of the curved section of the headrest frame 12 is approximately the same as the outer diameter of the upper frame section 213. Therefore, the lower end of the headrest frame 12 can be joined to the outer surface of the upper frame section 213 over a wide area.

[0086] The top of each headrest frame 11, 12 is ultimately covered with a pad made of cushioning material, and then further covered with a surface material such as fabric. These components then constitute the headrest.

[0087] Note that the headrest frame 11 and headrest frame 12 have different shapes for their pair of rod-shaped sections, but they may be made the same shape for both. Furthermore, each headrest frame 11, 12 may be attached by inserting it into a cylindrical support member attached to the upper frame 213, rather than being directly joined to the upper frame 213.

[0088] [Armrest bracket] Both armrest brackets 13 and 14 are formed from a single sheet of metal by press molding. The left armrest bracket 13 comprises a base end joined to the front side of the outer circumferential surface near the lower end of the third pipe member 23, a support arm extending forward from the base end, and a flange formed along the outer edges of the base end and the support arm. The right armrest bracket 14 comprises a base end joined to the front side of the outer circumferential surface near the lower end of the right frame portion 212 of the first pipe member 21, a support arm extending forward from the base end, and a flange portion formed along the outer edge of the base end and the support arm. The left and right armrest brackets 13 and 14 each have support holes for the armrests formed at their respective ends, at positions that are identical when viewed from the left and right directions. The left and right armrest brackets 13 and 14 rotatably support the lower ends of the armrests (not shown) from both the left and right sides.

[0089] [Mounting bracket for locking device] The mounting bracket 50 supports a locking device (not shown). The seat back frame 100 is supported so that its lower end can rotate around an axis along the left-right direction relative to the vehicle body. The seat back frame 100 is normally in an upright position, and can be tilted forward as needed. The locking device can maintain the seat back frame 100 in an upright position by engaging a striker, which consists of an oval-shaped wire extending to the right from the vehicle body. Furthermore, the locking device can switch between engaging and disengaging the striker via external operation.

[0090] As shown in Figures 1 and 3, the mounting bracket 50 is positioned on the upper front side of the left end of the seat back frame 100. The mounting bracket 50 is joined to the left frame portion 211 of the first pipe member 21 of the pipe frame 20 and to the front surface of the panel frame 30. The mounting bracket 50 has an open cross-section structure with a roughly U-shaped horizontal cross-section, and is joined to the front side of the panel frame 30 with its opening facing the front. The mounting bracket 50 is formed by press working from a single metal plate such as steel or aluminum alloy.

[0091] The mounting bracket 50 has a mounting surface 51 for the locking device on its left side. A notch 52 is formed on the rear edge of the mounting surface 51, extending forward. When the seat back frame 100 is rotated backward to raise or lower it, the striker provided on the vehicle body side moves relatively forward and engages with the locking device. This notch 52 serves as a clearance for the striker as it moves relatively forward. A notch 35 corresponding to the notch 52 is also formed on the left edge of the panel frame 30, and similarly serves as a clearance for the striker.

[0092] The mounting bracket 50 may have a flange portion having a flat surface facing the front surface of the panel frame 30 and a flange portion having a curved surface facing the outer circumferential surface of the left frame portion 211. By using these as joining surfaces, the mounting bracket 50 can be more firmly joined to the pipe frame 20 and the panel frame 30.

[0093] [Set Bracket] As shown in Figures 1 and 3, a set bracket 18 is provided at the left end of the lower front side of the seat back frame 100. The set bracket 18 is joined to the lower left corner of the panel frame 30 and to the front side of the outer peripheral surface of the lower end of the left frame portion 211 of the first pipe member 21. The set bracket 18 is formed from a single sheet of metal by press processing.

[0094] The set bracket 18 has a flat portion that is joined to the panel frame 30 and a curved portion that rises forward from the flat portion and is joined to the outer circumferential surface of the left frame portion 211. As a result, the set bracket 18 can make contact with the panel frame 30 and the left frame portion 211 over a wide area, and a high level of bonding strength can be maintained. Furthermore, ribs are formed on the upper and lower edges of the set bracket 18, serving as a reinforcing structure that rises forward from the plate surface. Two projection nuts are fixed to the front of the flat surface of the set bracket 18, one above the other, by projection welding. Through holes are formed in the flat surface of the set bracket 18 and the panel frame 30, corresponding to the screw holes of these projection nuts. When fixing the seat back frame 100 to the vehicle body, fixing bolts are screwed into each projection nut.

[0095] [Technical Effects of the First Embodiment] The seat back frame 100 has a first belt guide 15 and a second belt guide 16. Therefore, even when a large load is applied to the seat belt B1, the load applied from the seat belt B1 can be distributed to the first belt guide 15 and the second belt guide 16, making it possible to improve both the support rigidity of each belt guide 15, 16 and the support rigidity of the seat belt B1 with a simple configuration.

[0096] Furthermore, the seat back frame 100 has the first belt guide 15 and the second belt guide 16 attached along the pipe surface of the upper frame portion 213 of the pipe frame 20. Therefore, each belt guide 15 and 16 can be joined to the pipe surface over a wide area, high joint strength can be obtained, and it can withstand a larger load from the seat belt B1. Furthermore, by mounting each belt guide 15, 16 along the circumferential surface of the pipe, when a load is applied along the extension direction of the insertion portion 152 of each belt guide 15, 16, the force applied to the mounting surface with the upper frame portion 213 is more likely to be applied in a direction along the circumferential surface that is the mounting surface, rather than in a direction that would cause the mounting surface to peel off. As a result, each belt guide 15, 16 is less likely to peel off from the pipe frame 20, and the strength against load can be improved. Furthermore, by making the arms 151 and 161 of each belt guide 15 and 16 arc-shaped along the circumference of the pipe, the arms 151 and 161 themselves function as hooks. As a result, they can withstand even greater loads from the seat belt B1.

[0097] Furthermore, the seat back frame 100 has the extended ends of the insertion portion 152 of the first belt guide 15 and the extended ends of the insertion portion 162 of the second belt guide 16 positioned in front of and behind the center B3 of the seat belt retractor B, respectively. Therefore, when the seat belt is unwound from the seat belt retractor B through the second belt guide 16 and the first belt guide 15 to the front of the seat back frame, the belt guides 15 and 16 can guide it effectively. In other words, the seat belt B1 is unfurled upward from the seat belt retractor B, and then folded back and unfurled diagonally downwards and forwards. This allows the seat belt B1 to be guided to change its path in stages from the insertion portion 162 of the second belt guide 16 to the insertion portion 152 of the first belt guide 15, making it possible to smoothly unfurl the seat belt B1.

[0098] Furthermore, the above arrangement of the insertion portions 152 and 162 makes it possible to suppress uneven distribution of the load applied to each belt guide when a load is applied from the seat belt B1, and to distribute the load appropriately. Therefore, it is possible to improve the mounting strength and durability of each belt guide 15 and 16 against load.

[0099] Furthermore, since the insertion portion 162 of the second belt guide 16 is located behind the center B3 of the seat belt retractor B, when a large load is applied to the seat belt B1, the load that pulls the seat belt retractor B away from the support bracket 40 through the seat belt B1 can be reduced. Therefore, it is possible to improve the mounting strength and durability of the seat belt retractor B.

[0100] Furthermore, in the seat back frame 100, the extended end of the insertion portion 152 of the first belt guide 15 extends forward from the upper part of the pipe circumferential surface of the upper frame portion 213, and the extended end of the insertion portion 162 of the second belt guide 16 extends forward from the lower part of the pipe circumferential surface of the upper frame portion 213. Therefore, when a load is applied to the seat belt B1, the force applied to each belt guide 15, 16 can be directed in a direction along the pipe surface rather than in a direction that promotes separation of the upper frame portion 213 from the pipe surface, thereby improving the strength against load.

[0101] Furthermore, since the first belt guide 15 and the second belt guide 16 are made of the same shaped material, it is possible to simplify manufacturing and reduce manufacturing costs by standardizing parts.

[0102] Furthermore, the seat back frame 100 has a second reinforcing portion 319 that serves as a clearance for the first and second belt guides 15 and 16 provided on the upper frame portion 213, making it possible to avoid interference between each belt guide 15 and 16 and the panel frame 30. Panel materials such as the panel frame 30 make it easy to form clearance portions by creating irregularities, making it easy to secure the mounting positions for each belt guide 15 and 16, and also allowing for a high degree of freedom in arranging the mounting positions.

[0103] Furthermore, the seat back frame 100 is joined to the pipe frame 20 at multiple points by the panel frame 30, which is joined to the pipe frame 20 by the second, third, fourth, and fifth joint reinforcement parts 314, 316, 417, and 518 that protrude forward. The panel frame 30 forms a gap with respect to the pipe frame 20 in the front-to-back direction, except for these joint points that protrude forward. Therefore, the generation of rattling noises and other abnormal noises between the panel frame 30 and the pipe frame 20 can be suppressed.

[0104] [Second Embodiment] In the second embodiment, a seat back frame 100A is provided which includes a pipe frame 20A that differs in some configuration from the pipe frame 20. Figure 7 is a front view of the seat back frame 100A. Regarding the seat back frame 100A, components identical to those of the aforementioned seat back frame 100 are denoted by the same reference numerals, and redundant explanations are omitted. The seat back frame 100A will primarily be described in terms of its differences from the seat back frame 100.

[0105] The seat back frame 100A has a panel frame 30 and a pipe frame 20A provided on its front side. The pipe frame 20A differs from the pipe frame 20 in that it has a third pipe member 23A in place of the third pipe member 23, and also has a new fifth pipe member 25A.

[0106] The third pipe member 23A has a circular cross-section and is made of a metal pipe such as steel. The third pipe member 23A has the same outer diameter as the third pipe member 23. The third pipe member 23A is arranged inside the pipe frame 20A, generally along the vertical direction. The third pipe member 23A corresponds to a connecting member that connects the intermediate portion of the upper frame portion 213 to the intermediate portion of the second pipe member 22, which serves as the lower frame. However, the connection position of the third pipe member 23A to the upper frame portion 213 is different from that of the third pipe member 23 described above. The connection position of the third pipe member 23A to the upper frame portion 213 is located to the right of the connection position so as to avoid the first and second belt guides 15 and 16. The connection position of the third pipe member 23A to the upper frame portion 213 is an intermediate position between the connection positions of the first and second belt guides 15 and 16 and the connection position of the headrest frame 12.

[0107] The connection position of the lower end of the third pipe member 23A to the second pipe member 22 is the same as that of the third pipe member 23. For this reason, the third pipe member 23A has two bends 231A and 232A at its upper part, which allows for a change in the connection position to the upper frame 213. The lower bent portion 231A is located somewhat above the joint position with the upper second joint reinforcement portion 314 of the third pipe member 23A. The portion of the third pipe member 23A below the bent portion 231A is straight and oriented parallel to the vertical direction. The portion of the bent portion 231A above it is inclined diagonally upward to the right. The upper bent portion 232A is located near the upper end of the third pipe member 23A. The upper bent portion 232A tilts the portion above it diagonally upward and to the left. This bent portion 232A straightens the portion above it so that it is parallel in the vertical direction.

[0108] The upper end of the third pipe member 23A is joined to the upper frame portion 213 at a position to the right of its connection point, bypassing the first and second belt guides 15 and 16 by two bends 231A and 232A. The upper and lower ends of the third pipe member 23A are also compressed and flattened, and are joined to the upper frame portion 213 and the second pipe member 22 with high strength.

[0109] Furthermore, the third pipe member 23A has two bends 231A and 232A, both of which are positioned above the upper second joint reinforcement 314. Therefore, the third pipe member 23A can be joined to the two second joint reinforcement 314 without modifying the panel frame 30. It can also be joined to the connecting portion 42 without modifying the support bracket 40. Moreover, it can be joined to the fourth pipe member 24 without modifying the fourth pipe member 24. Therefore, the high-strength connection between the pipe frame 20A and the panel frame 30 is maintained, and the effect of improving the rigidity of the seat back frame 100A through their mutual connection is preserved.

[0110] The fifth pipe member 25A has a circular cross-section and is made of a metal pipe such as steel. The fifth pipe member 25A is positioned diagonally upward inside the pipe frame 20A. The fifth pipe member 25A connects the portion of the fourth pipe member 24 that is slightly to the right of the middle section to the upper left corner of the first pipe member 21, that is, the boundary between the left frame section 211 and the upper frame section 213. The fifth pipe member 25A functions as a diagonal bracing frame connecting the vicinity of corners in an arrangement approximately diagonally across the rectangular frame formed by the first pipe member 21, the third pipe member 23, and the fourth pipe member 24.

[0111] Both ends of the fifth pipe member 25A are compressed and flattened, and are joined with high strength to the rear outer surface of the fourth pipe member 24 and the rear outer surface of the first pipe member 21. Furthermore, the fifth pipe member 25A uses a pipe member with a smaller outer diameter compared to the fourth pipe member 24 and the like. This makes it possible to place it in the narrow space between the pipe frame 20A and the panel frame 30.

[0112] Furthermore, the fifth pipe member 25A may be a pipe member with the same outer diameter as the fourth pipe member 24, etc. Furthermore, the fifth pipe member 25A may be positioned on the front side of the pipe frame 20A.

[0113] In the seat back frame 100A, the third pipe member 23 is bent to bypass the first belt guide 15 and the second belt guide 16, and its upper end is connected to the upper frame portion 213. This makes it possible to properly secure the mounting positions of the first belt guide 15 and the second belt guide 16. Furthermore, regardless of the arrangement of the first belt guide 15 and the second belt guide 16, it becomes possible to position the third pipe member 23A inside the pipe frame 20A, thereby improving the frame strength in the same way as the third pipe member 23.

[0114] Furthermore, the third pipe member 23A is joined to the upper frame portion 213 at a position separated from the first belt guide 15 and the second belt guide 16. This prevents other members from being connected in a concentrated area relative to the upper frame portion 213. As a result, when a load is applied to the seat back frame 100A, the load is not concentrated in a narrow area of ​​the upper frame portion 213, which suppresses deformation and damage to the upper frame portion 213 and improves the durability of the seat back frame 100A.

[0115] Furthermore, since the fifth pipe member 25A is provided in a roughly diagonal arrangement on the frame-shaped portion of the pipe frame 20A, it is possible to suppress the deflection of each component of the pipe frame 20A in the direction of inclination, thereby improving the rigidity of the pipe frame 20A.

[0116] The third pipe member 23A may also be made from a straight pipe material without the bent portions 231A and 232A. In that case, it may be attached in a slightly upward-right inclined orientation so that its upper and lower ends are joined to the connection position to the upper frame portion 213 and the connection position to the second pipe member 22, respectively. In this case as well, it is possible to obtain a rigidity that is almost the same as that of the third pipe member 23A having the bent portions 231A and 232A. However, in that case, it is necessary to change the arrangement of the two second joint reinforcement parts 314, change the shape of the joint surface of the connecting part 42 of the support bracket 40, and adjust the length of the fourth pipe member 24.

[0117] [Third Embodiment] In the third embodiment, a belt guide 15B, which is different from the first belt guide 15 and the second belt guide 16, is illustrated. Figure 8 is a perspective view of the belt guide 15B.

[0118] The belt guide 15B is a belt guide formed from a single wire, integrating the aforementioned first belt guide 15 and second belt guide 16 into a single component. The belt guide 15B has the same shape and function as the first belt guide 15 and the second belt guide 16 described above. Therefore, the parts of the belt guide 15B that are identical to those of the first belt guide 15 and the second belt guide 16 described above shall be given the same reference numerals.

[0119] The belt guide 15B is formed by bending a rigid metal wire. The arrangement of the belt guide 15B relative to the upper frame portion 213 is consistent with the arrangement of the first belt guide 15 and the second belt guide 16.

[0120] The belt guide 15B has two roughly U-shaped sections, and two insertion sections 152 and 162 formed at the bottom of each U-shaped section. Furthermore, the right end of insertion section 152 and the right end of insertion section 162 are connected by an arc-shaped arm 151. The inner diameter of the arm 151 is approximately the same as the outer diameter of the upper frame section 213, and the inner circumference of the arm 151 is joined to the outer circumference of the upper frame section 213. Furthermore, the left end of the insertion portion 152 extends rearward and is formed in an arc shape to constitute the other arm portion 151. This arm portion 151 is also joined to the upper frame portion 213 in the same manner as the arm portion 151 described above. Furthermore, the left end of the insertion portion 162 also extends rearward and is formed in an arc shape to constitute the arm portion 161. This arm portion 161 is joined to the upper frame portion 213 next to the arm portion 151 in the same manner as the arm portion 151.

[0121] Furthermore, the right arm portion 151 of the insertion portion 152 in the first belt guide 15 and the right arm portion 161 of the insertion portion 162 in the second belt guide 16 are shared by a single arm portion 151. Furthermore, the insertion portion 162 is, strictly speaking, formed to be slightly longer than the insertion portion 162 of the second belt guide 16.

[0122] The arrangement of the linear portion of the insertion portion 152 and the linear portion of the insertion portion 162 in the belt guide 15B relative to the upper frame portion 213 corresponds to the arrangement of the linear portion of the insertion portion 152 of the first belt guide 15 and the linear portion of the insertion portion 162 of the second belt guide 16, respectively. Therefore, the belt guide 15B functions identically to the first belt guide 15 and the second belt guide 16, and achieves the same technical effect. Furthermore, since the belt guide 15B consists of a single, integrated component, it is possible to reduce the number of parts, lower manufacturing costs, and reduce weight.

[0123] [Fourth Embodiment] In the fourth embodiment, a seat back frame 100C is provided which includes a pipe frame 20C that has some configuration differences from the pipe frame 20. Figure 9 is a front view of the seat back frame 100C. Regarding the seat back frame 100C, components identical to those of the aforementioned seat back frame 100A are denoted by the same reference numerals, and redundant explanations are omitted. The seat back frame 100C will primarily be described in terms of its differences from the seat back frame 100A.

[0124] The seat back frame 100C has a panel frame 30 and a pipe frame 20C provided on its front side. The pipe frame 20C differs from the pipe frame 20A in that it includes a third pipe member 23C in place of the third pipe member 23A, and first and second belt guides 15C and 16C in place of the first and second belt guides 15 and 16. Furthermore, pipe frame 20C differs from pipe frame 20A in that it does not have a fifth pipe member 25A.

[0125] The third pipe member 23C differs from the third pipe member 23A in that it uses a smaller outer diameter metal pipe. Therefore, the joint positions at both ends of the third pipe member 23C in the pipe frame 20C, and the bending positions of the two bent sections 231C and 232C of the third pipe member 23C, are the same as those of the third pipe member 23A.

[0126] The first and second belt guides 15C and 16C differ only in that the outer diameter of the wire used is larger than that of the first and second belt guides 15 and 16. The shape, arrangement, and structure of the first and second belt guides 15C and 16C are identical to those of the first and second belt guides 15 and 16. The outer diameter of the wires of the first and second belt guides 15C and 16C may be larger than the outer diameter of the metal pipe of the third pipe member 23C.

[0127] The seat back frame 100C, having the above configuration, can be made lighter than the seat back frame 100A by reducing the diameter of the third pipe member 23C. Furthermore, by omitting the fifth pipe member 25A, even greater weight reduction is achieved. Furthermore, the first and second belt guides 15C and 16C have improved load-bearing capacity against the load received from the seat belt B1 by increasing the outer diameter of the wire used.

[0128] The seat back frame 100C is designed to reduce weight while improving load-bearing capacity from the seat belt B1. However, if the focus is solely on weight reduction, the frame may be configured to include the first and second belt guides 15 and 16 described above.

[0129] [Fifth Embodiment] In the fifth embodiment, a seat back frame 100D is provided which includes a first belt guide 15D that has some configuration differences from the first belt guide 15. Figure 10 is a front view of the seat back frame 100D. Regarding the seat back frame 100D, components identical to those of the aforementioned seat back frame 100 are denoted by the same reference numerals, and redundant explanations are omitted. The seat back frame 100D will primarily be described in terms of its differences from the seat back frame 100.

[0130] The first belt guide 15D differs from the first belt guide 15 in that its insertion portion 152D is longer in the left-right direction than the insertion portion 152 of the first belt guide 15. The left arm 151 of the first belt guide 15D has the same connection position to the upper frame 213 as the connection position of the left arm 151 of the first belt guide 15. On the other hand, the connection position of the right arm portion 151 of the first belt guide 15D to the upper frame portion 213 is to the right of the connection position of the right arm portion 151 of the first belt guide 15. More specifically, it is to the right of the connection position of the third pipe member 23 on the upper frame portion 213, and is at a position that is further away than the distance between the right arm portion 151 of the first belt guide 15 and the third pipe member 23.

[0131] The seat back frame 100D has the same effect as the seat back frame 100. Furthermore, the first belt guide 15D has an insertion portion 152D that is long in the left-right direction, making it easier to insert the seat belt B1. Furthermore, because the insertion portion 152D is long in the left-right direction, it becomes possible to optimize the joining positions of the left and right arm portions 151 to the upper frame portion 213. For example, by joining the arm portions 151 to a position further away from the joining position of the third pipe member 23 on the upper frame portion 213, it is possible to avoid the members being connected in a concentrated area. When a load is applied to the seat back frame 100D, it is possible to avoid the load being concentrated in a narrow area of ​​the upper frame portion 213, thereby suppressing deformation and damage to the upper frame portion 213 and improving the durability of the seat back frame 100D.

[0132] [Sixth Embodiment] In the sixth embodiment, a seat back frame 100E is provided which includes a second belt guide 16E that differs in some configuration from the first belt guide 15. Figure 11 is a front view of the seat back frame 100E. Regarding the seat back frame 100E, components identical to those of the aforementioned seat back frame 100 are denoted by the same reference numerals, and redundant explanations are omitted. The seat back frame 100E will primarily be described in terms of its differences from the seat back frame 100.

[0133] The second belt guide 16E differs only in that its insertion portion 162E is longer in the left-right direction than the insertion portion 162 of the second belt guide 16E. The left arm portion 161 of the second belt guide 16E has the same connection position to the upper frame portion 213 as the connection position of the left arm portion 151 of the second belt guide 16. On the other hand, the connection position of the right arm 161 of the second belt guide 16E to the upper frame 213 is to the right of the connection position of the right arm 161 of the second belt guide 16. More specifically, it is to the right of the connection position of the third pipe member 23 on the upper frame 213, and is at a position that is further away than the distance between the right arm 161 of the second belt guide 16 and the third pipe member 23.

[0134] The seat back frame 100E has the same effect as the seat back frame 100. Furthermore, the second belt guide 16E has an insertion portion 162E that is long in the left-right direction, making it easier to insert the seat belt B1. Furthermore, because the insertion portion 162E is long in the left-right direction, it becomes possible to optimize the joining positions of the left and right arm portions 161 to the upper frame portion 213. This makes it possible to improve the durability of the seat back frame 100E.

[0135] [Seventh Embodiment] In the seventh embodiment, a seat back frame 100F equipped with a blower device 60 is illustrated. Figure 12 is a front view of the seat back frame 100F. Regarding the seat back frame 100F, components identical to those of the aforementioned seat back frame 100 are denoted by the same reference numerals, and redundant explanations are omitted. The seat back frame 100F will primarily be described in terms of its differences from the seat back frame 100.

[0136] The seat back frame 100F has one blower device 60 on each side of the seat belt retractor B, located on the front side of the upper part of the panel frame 30. Each blower device 60 may be attached to a bracket (not shown) made of a metal plate joined to the front side of the panel frame 30 by fastening it with bolts or the like.

[0137] Each blowing device 60 has a housing 61 that houses a fan and a drive source such as a motor, and a duct 62 that extends upward from the housing 61 and opens to the front. The left-side air blower device 60 is positioned within a gap area with ample clearance in the front-to-back direction, surrounded by the first pipe member 21, the third pipe member 23, and the fourth pipe member 24. Furthermore, the left-side air blower device 60 is positioned so as not to interfere with the headrest frame 11, with the duct 62 located between the ends of two wires extending downward from the headrest frame 11. The right-side air blower device 60 is surrounded by the first pipe member 21, the second pipe member 22, and the third pipe member 23, and is positioned in the upper part of a gap area with ample space in the front-to-back direction. Furthermore, the right-side air blower device 60 is positioned so as not to interfere with the headrest frame 12, with the upward-extending duct 62 located between the ends of two wires extending downward from the headrest frame 12.

[0138] The seat back frame 100F is equipped with ventilation devices 60 on both sides, making it possible to add a ventilation function to the seat. Furthermore, since each blower device 60 is positioned utilizing the gap space in the seat back frame 100F, it is possible to avoid increasing the size of the seat back frame 100F. In addition, because it is surrounded by pipe members, the blower device 60 can be effectively protected even when a load is applied to the seat.

[0139] [Eighth Embodiment] In the eighth embodiment, another example of a seat back frame 100G is shown. Figure 13 is a front view of the seat back frame 100G. Regarding the seat back frame 100G, components identical to those of the aforementioned seat back frame 100 are denoted by the same reference numerals, and redundant explanations are omitted. The seat back frame 100G will primarily be described in terms of its differences from the seat back frame 100.

[0140] The seat back frame 100G differs from the seat back frame 100 mainly in that it does not have a panel frame 30. In the seat back frame 100, the support bracket 40 of the seat belt retractor B is supported by the panel frame 30. In the seat back frame 100G, the support bracket 40G of the seat belt retractor B is supported by the pipe frame 20.

[0141] The support bracket 40G is made of a roughly rectangular or roughly square metal plate. The support bracket 40G only needs to be slightly larger than the seat belt retractor B when viewed from the front. The front of the right edge of the support bracket 40G is joined to the rear of the outer circumferential surface of the third pipe member 23. Also, the front of the lower edge of the bracket 40G is joined to the rear of the outer circumferential surface of the fourth pipe member 24. The support bracket 40G also has an insertion hole for the bolt 43, and the head of the bolt 43 is joined on the rear side. The seat belt retractor B is fixed to the front side of the support bracket 40G by the bolt 43 and a nut (not shown).

[0142] The support bracket 40G does not have to be approximately rectangular or approximately square. However, it is preferable that it be a metal plate having an approximately right-angle portion with an outer edge along the third pipe member 23 and an outer edge along the fourth pipe member 24. Alternatively, the support bracket 40G may extend its left edge to the left frame portion 211, and the front surface of the left edge may be joined to the rear of the outer circumferential surface of the left frame portion 211. In this case, the lower edge of the support bracket 40G may or may not be joined to the fourth pipe member 24.

[0143] The seat back frame 100G does not have a panel frame 30, which allows for a dramatic reduction in weight. Furthermore, because it does not have the panel frame 30, which is the largest component, it is possible to reduce the number of parts and lower manufacturing costs. Furthermore, since the support bracket 40G of the seat belt retractor B is joined to the rear of the outer circumferential surfaces of the third pipe member 23 and the fourth pipe member 24 of the pipe frame 20, high support strength against the load received from the seat belt B1 can be obtained.

[0144] [others] Embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments described above. For example, a component integrally formed from a single member in an embodiment may be replaced with a component divided into multiple members that are connected or fixed to each other. Also, a component formed by connecting multiple members may be replaced with a component integrally formed from a single member. Furthermore, details shown in the embodiments can be modified as appropriate without departing from the spirit of the invention.

[0145] For example, the pipe frame 20 may consist of a first pipe member 21 forming the left and right frames and the upper frame, and a second pipe member 22 forming the lower frame, but is not limited to this configuration. The first pipe member 21 may also consist of the left and right frames and the lower frame, and the second pipe member 22 may also constitute the upper frame. Furthermore, the first pipe member 21 may be substantially U-shaped, having an upper frame portion along the upper edge of the seat back frame 100, a lower frame portion along the lower edge of the seat back frame 100, and a left frame portion or a right frame portion along the left or right edge of the seat back frame 100. In that case, it is preferable that the second pipe member 22 be a right frame portion or a left frame portion parallel to the vertical direction along the right or left edge of the seat back frame 100. It is also preferable that the third pipe member 23 be oriented horizontally and the fourth pipe member 24 be oriented vertically.

[0146] Furthermore, the number of the first reinforcing section 311, the third joint reinforcing section 316, the fourth joint reinforcing section 317, and the fifth joint reinforcing section 318 in the panel frame 30 can be increased or decreased. Also, the arrangement of the first reinforcing section 311, the third joint reinforcing section 316, the fourth joint reinforcing section 317, and the fifth joint reinforcing section 318 can be changed.

[0147] [Additional Solution 1] In a method for manufacturing a seat back frame, The process involves preparing a first belt guide through which the seat belt unwound from the seat belt retractor passes, A step of preparing a second belt guide, separate from the first belt guide, through which the seat belt unwound from the seat belt winding device is inserted, A method for manufacturing a seat back frame, characterized by comprising the following features.

[0148] The above solution 1 includes a step of preparing a first belt guide and a step of preparing a second belt guide, making it possible to suitably manufacture a seat back frame with high seat belt support rigidity.

[0149] [Additional Solution 2] The process of preparing the pipe frame, The steps include: attaching the first belt guide and the second belt guide along the pipe surface of the pipe frame; A method for manufacturing a seat back frame according to Solution 1, characterized by comprising:

[0150] The above solution 2 includes a step of preparing a pipe frame and a step of attaching the first belt guide and the second belt guide along the pipe surface of the pipe frame, making it possible to suitably manufacture a seat back frame with high attachment strength for each belt guide. [Explanation of Symbols]

[0151] 11,12 Headrest frame 13,14 Armrest Bracket 15,15B First Belt Guide 151 Arm 152, 152D Insertion section 16. Second Belt Guide 161 Arm 162, 162E Insertion section 17 Tether component 18-set bracket 20, 20A, 20C pipe frame 21-24 1st-4th pipe members 211 Left frame section 212 Right frame section 213 Upper frame section 221 Flat area 231A,231C,232A,232C Bend part 30 Panel Frames 32 openings 33 Relief connection part 34 Notches 35 Notches 40,40G support bracket 41 Support part 42 Connecting part 421 Reinforcement section 43 volts 50 Mounting Brackets 51 Mounting surface 52 Notches 100, 100A, 100C~100G Seat Back Frame 301 Flange section 311 First Reinforcement Section 311a Through hole 312 First joint reinforcement section 313 Surrounding reinforcement section 314 Second joint reinforcement section 315 Reinforcement section of the step 316 Third joint reinforcement section 317 Fourth joint reinforcement section 318 Fifth joint reinforcement section 319 Second Reinforcement Section 421 Reinforcement section B Seat belt retractor B1 Seatbelt B2 Insertion Guide B3 center P1~P4 1st~4th part

Claims

1. A first belt guide through which the seat belt unwound from the seat belt retractor passes, A second belt guide, separate from the first belt guide, through which the seat belt unwound from the seat belt retractor passes, Equipped with a pipe frame, A seat back frame characterized in that the first belt guide and the second belt guide are mounted along the circumferential surface of the pipe frame.

2. Both the first belt guide and the second belt guide consist of a U-shaped wire. Both the first belt guide and the second belt guide are attached such that one end and the other end of the wire are mounted along the circumferential surface of the pipe frame. The seat back frame according to claim 1, characterized in that, when the seat back frame is positioned with one side forward and the other side backward, the seat belt insertion portion of the first belt guide extends forward from the center of the seat belt winding device, and the seat belt insertion portion of the second belt guide does not extend forward from the center of the seat belt winding device.

3. Both the first belt guide and the second belt guide consist of a U-shaped wire. When the seat back frame is positioned with one side facing forward and the other side facing backward, both the first belt guide and the second belt guide are attached so that one end and the other end of the wire are along the circumferential surface of the pipe frame. The seat back frame according to claim 1 or 2, characterized in that the end of the first belt guide on the seat belt insertion side extends forward from the upper part of the pipe circumferential surface of the pipe frame, and the end of the second belt guide on the seat belt insertion side extends forward from the lower part of the pipe circumferential surface of the pipe frame.

4. The seat back frame according to claim 3, characterized in that the first belt guide and the second belt guide are made of members of the same shape.

5. The pipe frame is provided along the outer edge of the seat back frame, The pipe frame has connecting members arranged vertically inside it, The seat back frame according to claim 1, characterized in that the connecting member is bent to bypass the first belt guide or the second belt guide, and its upper end is connected to the pipe frame.

6. The seat back frame according to claim 1, characterized in that the first belt guide and the second belt guide consist of a single integrated member.

7. The panel frame is joined to the aforementioned pipe frame, The seat back frame according to claim 1, characterized in that the panel frame has relief portions that avoid the first belt guide and the second belt guide in relation to the mounting portions of the first belt guide and the second belt guide in the pipe frame.

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