JP2012147938A - Backrest board, and vehicular seat using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backrest board that can reduce a spring constant of a resin spring with a simple construction, and to provide a vehicular seat using the same.SOLUTION: The backrest board 16 includes the resin spring composed of a pair of right and left upper back spring body parts 54 and a plurality of lower back spring body parts 48. The pair of right and left upper back spring body parts 54 arranged facing an upper part of a seated occupant's back have a cantilever structure. Consequently, the spring constant can be reduced as compared with upper back spring body parts having a both-end support structure.

Description

  The present invention relates to a seat backboard and a vehicle seat using the same.

  The following Patent Document 1 discloses a technique using a net-like resin spring body made of a resin material from the viewpoint of reducing the weight of a vehicle seat.

  Here, unlike the above-described prior art, when a configuration in which a belt-shaped resin spring is arranged so as to connect the left and right side frames of the seat back frame, the following matters are raised as problems.

  That is, when a belt-shaped resin spring is arranged so as to connect the left and right side frames as described above, in addition to the spring force as a bending beam, the resin spring is applied to the resin spring in response to load input from the back of the occupant. The spring force due to the tension from both ends is also added. For this reason, the spring constant of the said resin spring may become large.

  In that case, it is considered that the thickness of the resin spring may be reduced to lower the spring constant of the resin spring. However, reducing the plate thickness of the resin spring has its own limitations from the viewpoint of moldability and material characteristics such as fatigue limit stress.

JP 2004-138156 A

  An object of the present invention is to obtain a seat back board capable of reducing the spring constant of a resin spring with a simple configuration and a vehicle seat using the same in consideration of the above facts.

  The seat back board according to the first aspect of the present invention is arranged along the seat width direction between a pair of left and right side frames provided in the seat back frame, and a load action is caused by a load acting on the rear side of the seat back. A back spring main body made of resin that can be bent and deformed in the direction, and further, the back spring main body is divided into right and left, each base end is supported by the side frame, and the front end is a free end. It is a cantilever support structure.

  A seat backboard according to a second aspect of the present invention is the seat backboard according to the first aspect, wherein a plurality of the back spring main body portions are arranged at intervals in the seat back height direction. Among the main body portions, at least a back spring main body portion arranged at a position facing the back of the seated occupant is a back spring main body portion of the cantilever support structure.

  According to a third aspect of the present invention, there is provided a seat backboard according to the second aspect of the present invention, wherein the resin backboard portion is formed of a resin plate and is disposed on the back side of the seat back frame, and the plurality of the backboard portions. Are connected by a pair of right and left connecting and fixing parts fixed to the side frame, and the plurality of back spring body parts including the back spring body parts of the cantilever support structure are connected to the connecting and fixing parts. It is assumed that they are formed integrally or integrally.

  According to a fourth aspect of the present invention, there is provided the seat backboard according to the second or third aspect, wherein the thickness of the back spring body portion of the pair of left and right cantilevered support structures extends from the left and right ends to the center. It is characterized by being set to be thin.

  According to a fifth aspect of the present invention, there is provided the seat backboard according to any one of the second to fourth aspects, wherein the pair of left and right cantilevered structure of the back spring body portion and the inner end of the back spring main body portion. It is characterized in that a back spring body part of a both-end support structure set at a different height from the back spring body part is connected by a connecting part.

  6. The vehicle seat according to claim 6, wherein the vehicle seat is supported by the seat back frame and the pair of left and right side frames in the seat back frame. A seat back board; a seat back pad disposed on a front side of the seat back board; and a cover that covers a surface of the seat back pad.

  According to a seventh aspect of the present invention, a vehicle seat according to the present invention is provided in a seat back, and is disposed along a seat width direction between a seat back frame including a pair of left and right side frames and the pair of left and right side frames. And a plurality of resin back spring main body portions that are arranged at intervals in the seat back height direction and are formed to be able to bend and deform in the load acting direction when a load is applied to the seat back rear side, and the back spring. A seat back pad disposed on the front side of the main body, and a cover that covers the surface of the seat back pad, and further, at least a position facing the back of the seated occupant among the plurality of back spring main bodies The back spring main body arranged on the left and right is divided into left and right parts, the base ends of which are supported by the side frames, and the tip end is the free end. It was there is a cantilevered structure.

  According to the first aspect of the present invention, the resin-made back spring main body portion is disposed along the seat width direction between the pair of left and right side frames included in the seat back frame. In the present invention, the back spring main body is provided separately on the left and right. Specifically, each back spring main body has a cantilever support structure in which a base end portion is supported by a side frame and a distal end portion is a free end. Therefore, when compared with the back spring portion of the both-end support structure, the spring force due to the tension from both ends is not generated with respect to the load input from the upper back of the occupant, but only the spring force as a bending beam is generated. For this reason, according to the back spring main body portion of the present invention, the spring constant can be lowered as compared with the back spring portion of the both-end support structure. In addition, unlike the method of simply reducing the plate thickness by reducing the spring constant, the method of lowering the spring constant is adopted by changing the support structure to the side frame from the both-end support structure to the cantilever support structure. Formability is not deteriorated, and material properties such as fatigue limit stress are not hindered.

  Further, since the back spring body is changed from the both-end support structure to the cantilever support structure as in the present invention, no new parts are required. For this reason, a structure becomes very simple.

  According to the second aspect of the present invention, the plurality of back spring main body portions are arranged at intervals in the seat back height direction, and are arranged at a position facing at least the back upper part of the seated occupant. The back spring main body is the back spring main body of the above-mentioned cantilever support structure.

  Here, it is generally desirable that the upper back of the seated occupant be softly supported, unlike the waist of the seated occupant. Therefore, if the back spring body portion of the cantilever support structure is used for the back spring body portion arranged at a position facing the upper back of the seated occupant as in the present invention, the required support force and spring constant can be obtained. The relationship is optimized.

  According to the third aspect of the present invention, since the plurality of back spring main body portions including the back spring main body portion of the cantilever support structure are formed integrally or integrally with the connection fixing portion, The load is supported from the back spring body portion of the cantilever support structure to the side frame via the connection fixing portion. Moreover, since it is integrated with the backboard part, the number of parts is reduced.

  According to the fourth aspect of the present invention, since the plate thickness of the back spring body portion of the cantilever support structure is set so as to become thinner from the left and right ends to the center, the left and right ends of the back spring body are more Strength and rigidity become higher than the center side.

  According to the fifth aspect of the present invention, the inner end portion of the back spring body portion of the cantilever support structure and the back spring body portion of the both-end support structure set to a height different from the back spring body portion are connected to each other. Therefore, the spring constant is higher than that of the back spring body portion of the cantilever support structure. That is, a resin spring having an intermediate spring constant between the back spring body portion of the cantilever support structure and the back spring body portion of the both-end support structure can be obtained.

  According to the sixth aspect of the present invention, the vehicle seat includes a seat back frame, a seat back board, a seat back pad, and a cover. And among these, since the seat back board is the seat back board described in any one of claims 1 to 5, the above-described action is obtained.

  According to the seventh aspect of the present invention, between the pair of left and right side frames provided in the seat back frame, the resin back spring main body disposed along the seat width direction is spaced in the seat back height direction. A plurality of them are arranged. In the present invention, among the plurality of back spring main body portions, at least the back spring main body portion disposed at a position facing the upper back of the seated occupant is provided separately on the left and right sides. Specifically, the back spring main body has a cantilever support structure in which a base end portion is supported by a side frame and a distal end portion is a free end. Therefore, when compared with the back spring portion of the both-end support structure, the spring force due to the tension from both ends is not generated with respect to the load input from the upper back of the occupant, but only the spring force as a bending beam is generated. For this reason, according to the back spring main body portion of the present invention, the spring constant can be lowered as compared with the back spring portion of the both-end support structure. In addition, unlike the method of simply reducing the plate thickness by reducing the spring constant, the method of lowering the spring constant is adopted by changing the support structure to the side frame from the both-end support structure to the cantilever support structure. Formability is not deteriorated, and material properties such as fatigue limit stress are not hindered.

  In particular, it is generally desirable to support the upper part of the seated occupant softly unlike the waist of the seated occupant. Therefore, if the back spring body portion of the cantilever support structure is used for the back spring body portion arranged at a position facing the upper back of the seated occupant as in the present invention, the required support force and spring constant can be obtained. The relationship is optimized.

  Further, since the back spring body is changed from the both-end support structure to the cantilever support structure as in the present invention, no new parts are required. For this reason, a structure becomes very simple.

  As described above, the seat backboard according to the first aspect of the present invention has an excellent effect that the spring constant of the resin spring can be lowered with a simple configuration.

  The seat backboard according to the second aspect of the present invention has an excellent effect that the upper part of the seated occupant can be supported with an appropriate supporting force.

  The seat backboard according to the third aspect of the present invention has an excellent effect that the cost can be reduced by reducing the number of parts.

  The seat backboard according to the fourth aspect of the present invention has an excellent effect that it can sufficiently withstand the local stress acting on the left and right ends of the back spring main body.

  The seat backboard according to the present invention described in claim 5 supports the back of the seated occupant with a resin spring having an intermediate spring constant between the back spring body portion of the cantilever support structure and the back spring body portion of the both-end support structure. It has an excellent effect of being able to.

  The vehicle seat according to the sixth aspect of the present invention can reduce the number of parts and improve the productivity, and improve the comfort at the time of sitting by lowering the spring constant of the resin spring with a simple configuration. It has an excellent effect of being able to be made.

  The vehicle seat according to the seventh aspect of the present invention has an excellent effect that the spring constant of the resin spring can be lowered with a simple configuration and the upper back of the seated occupant can be supported with an appropriate supporting force. Have

It is a disassembled perspective view of the seat back of the vehicle seat which concerns on 1st Embodiment. It is a perspective view which shows the state by which the resin spring integrated backboard was assembled | attached to the seat back frame shown by FIG. FIG. 3 is an enlarged plan view (an enlarged plan view along line 3-3 in FIG. 2) showing an enlarged state of the seat back shown in FIG. 1. FIG. 2 is an enlarged longitudinal sectional view showing an assembled state of the seat back shown in FIG. 1. It is a perspective view which shows the resin spring integrated backboard shown by FIG. 1 alone. FIG. 6 is an enlarged plan view (an enlarged plan view taken along line 6-6 in FIG. 2) showing an enlarged state of the seat back shown in FIG. FIG. 7 is a plan sectional view corresponding to FIG. 6, showing an enlarged state of assembly of the seat back of the vehicle seat according to the comparative example. It is a perspective view which shows the resin spring integrated backboard which concerns on 2nd Embodiment alone. FIG. 9 is an enlarged plan cross-sectional view corresponding to FIG. 6 showing an enlarged state of the seat back assembled using the resin spring integrated back board shown in FIG. 8. It is a perspective view which shows the resin spring integrated backboard which concerns on 2nd Embodiment alone.

[First Embodiment]
Hereinafter, 1st Embodiment of the vehicle seat which concerns on this invention is described using FIGS. In these drawings, an arrow FR appropriately shown indicates the vehicle front side, an arrow UP indicates the vehicle upper side, and an arrow IN indicates the vehicle width direction inner side.

<Overall configuration>
FIG. 1 is an exploded perspective view of a seat back corresponding to the backrest of the vehicle seat according to the present embodiment. In FIG. 1, the angle at which each component is viewed is slightly changed. FIG. 4 shows a longitudinal sectional view of a vehicle seat provided with the seat back. As shown in these drawings, a vehicle seat 10 includes a seat cushion 11 (see FIG. 4) on which an occupant is seated, a seat back 12 that is tiltably supported at a rear end portion of the seat cushion 11, and a seat back. 12 and a headrest (not shown) supported by the upper end of 12 so as to be movable up and down.

  As shown in FIG. 1, the seat back 12 includes a metal seat back frame 14 that constitutes a skeleton member of the seat back 12, and a resin spring integrated back board (hereinafter referred to as a front plate) mounted on the front side of the seat back frame 14. , Simply referred to as “seat back board”) 16, a seat back pad 18 that constitutes a cushion material of the seat back 12 and is attached from the front side of the seat back board 16 and supported by the seat back frame 14, The back pad 18 mainly includes a cover (skin) 20 that covers the front surface, and a vertical mounting member 22 and a horizontal mounting member 24 for mounting the cover 20 to the seat back board 16. Hereinafter, each component will be described in detail.

<Configuration of the seat back frame 14>
As shown in FIGS. 1 to 4, the seat back frame 14 is viewed from the front (when viewed from the front of the vehicle. Hereinafter, the direction of the vehicle and the direction of the vehicle seat 10 are assumed to be the same. )) In the shape of a rectangular frame. Specifically, a pair of left and right side frames 26 arranged opposite to each other in the vehicle width direction, an inverted U-shaped upper frame 28 that connects the upper ends of the left and right side frames 26, and the left and right side frames 26 And a lower frame 30 that connects lower end portions in the vehicle width direction. The seat back 12 includes all four members including the upper frame 28 by press molding, but other frame structures may be adopted. For example, only the upper frame may be formed of a pipe material bent in an inverted U shape, or the upper frame and a pair of left and right side frames may be configured of a single pipe material bent in an inverted U shape.

  Next, the sectional structure of the left and right side frames 26 will be described. As shown in FIGS. 2 and 3, the side frame 26 includes a side wall portion 26A, a front wall portion 26B, and a rear wall portion 26C. When viewed alone, the side frame 26 is substantially L-shaped in a plan view. When viewed as a pair on the left and right, it is formed in an open cross-sectional shape with the inside facing the sheet width direction opened in a plan view. The width of the side wall portion 26A becomes narrower from the lower end portion toward the upper end portion as a whole. A plurality of mounting holes 32 (see FIG. 1) are formed in the lower portion of the side wall portion 26A so as to be spaced apart from each other in the vertical direction. The front wall portion 26B extends inward in the seat width direction from the front end of the side wall portion 26A, and the front end portion thereof is bent obliquely toward the vehicle rear side. The rear wall portion 26C extends inward in the seat width direction from the rear end of the side wall portion 26A, and the front end portion thereof is bent obliquely toward the vehicle front side. The width of the rear wall portion 26C is set sufficiently wider than the width of the front wall portion 26B.

<Configuration of seat back board 16>
Next, the structure of the seat back board 16 which comprises the principal part of the vehicle seat 10 which concerns on this embodiment is demonstrated in detail. As shown in FIGS. 1 to 4 (particularly FIGS. 1 and 2), the seat back board 16 is formed of a resin plate and has a back board portion 36 disposed on the back side of the seat back frame 14. The resin is made of resin and is provided integrally with the backboard portion 36 and is supported so as to be directly supported by the pair of left and right side frames 26. Further, a load acting on the rear side of the seat back acts on the load acting direction ( And a back spring portion 38 formed to be able to bend and deform toward the vehicle rear side).

  The backboard portion 36 includes a board body 40 that is formed slightly smaller than the seatback frame 14, and a U-groove locking portion 42 that is integrally formed on the outer periphery of the board body 40. . More specifically, the board body 40 is formed slightly smaller than the inner peripheral edge of the opening of the seat back frame 14 formed in a rectangular frame shape. In the assembled state to the seat back frame 14, the board body 40 is disposed slightly on the vehicle rear side between the front end portions (inner end portions) of the rear wall portions 26 </ b> C of the left and right side frames 26. Therefore, the board main body 40 can be assembled from the vehicle front side of the seat back frame 14 (see FIG. 3). The cross-sectional shape of the locking portion 42 is U-shaped with the vehicle rear side open. The locking portion 42 is used to lock the outer peripheral portion of the cover 20 described later, and has a function of reinforcing the plate-like board body 40 and increasing the surface rigidity of the entire backboard portion 36. Yes.

  The back spring portion 38 includes a lower back spring main body portion 48 integrally formed on the lower side of the back board portion 36, a pair of left and right upper back spring main body portions 54 integrally formed on the upper side of the back board portion 36, A pair of left and right connecting and fixing portions 50 that connect the backboard portion 36 and both ends of the lower back spring main body portion 48 in the longitudinal direction and both ends of the pair of left and right upper back spring main body portions 54 in the seat width direction. ing. The upper back spring portion 46 is provided at a position separated from the lower back spring portion 44 by a predetermined distance in the seat back height direction.

  The lower back spring main body portions 48 are each formed in a belt shape and are arranged in parallel in three upper and lower stages in the seat back height direction. Note that the number of the lower back spring main body portions 48 to be set is arbitrary, and is appropriately changed in relation to the required cushion performance. Therefore, the upper and lower widths of the lower back spring main body portion may be widened to one, or conversely, two or four or more.

  A corrugated portion 48A having a corrugated plane cross-sectional shape is formed at two locations on the left and right sides near the center of the lower back spring body 48. As a result, the load on the backboard portion 36 (the vehicle rear side) acts to cause the wave-like portion 48A to expand, and to bend and deform (elastically deform) toward the backboard portion 36 that is the load acting direction. Yes. However, the wavy portion 48 </ b> A may be formed over the entire lower back spring body 48. In addition, in the vicinity of both end portions 48B in the seat width direction of the lower back spring main body portion 48 of the upper stage and the middle stage, a vertical resin claw portion 58 to be described later for attaching the cover 20 is integrally formed.

  As shown in FIG. 3, the above-described backboard portion 36 is disposed at a position separated by a predetermined distance on the vehicle rear side of the lower back spring main body portion 48. That is, a predetermined gap 52 is formed between the lower back spring main body portion 48 and the back board portion 36. The lower back spring body 48 can be elastically deformed within the gap 52. That is, the backboard portion 36 also functions as a limiting member that limits the amount of bending of the lower back spring main body portion 48 to a predetermined amount or less.

  The connection fixing part 50 is formed in a substantially inverted U shape in a plan view, and has an inner side wall 50A to which the end part in the seat width direction of the lower back spring main body part 48 is connected, and the inner side wall 50A. An outer side wall 50B that is arranged in parallel and is engaged with the outer surface of the side wall portion 26A of the side frame 26 in a surface contact state, and a front end of the inner side wall 50A and a front end of the outer side wall 50B are connected in the vehicle width direction. A front wall 50C that is locked to the front wall portion 26B of the 26 in a partial surface contact state.

  The connecting and fixing part 50 is fixed to the side frame 26 by fixing the outer side wall 50B from the outer side in the seat width direction to the mounting hole 32 of the side wall part 26A of the side frame 26 by fixing means (not shown). As fixing means, a structure in which a resin clip is integrally formed on the outer side wall 50B and engaged with the mounting hole 32, a structure in which a rivet, a screw, a screw or a bolt and a fastener such as a weld nut are fastened, and a structure Various aspects, such as a structure of bonding with an adhesive, can be applied.

<Configuration of the seat back pad 18>
As shown in FIG. 1, the seat back pad 18 is roughly composed of a pad center upper part 62, a pad center lower part 64, and a pair of left and right pad side parts 66. The seat back pad 18 is made of urethane foam or the like.

  As shown in FIG. 4, the vertical cross-sectional shape of the pad center upper portion 62 is formed in a substantially J shape that is upside down and left and right. The pad center upper part 62 is locked to the upper frame 28 of the seat back frame 14 from above the seat back. The vertical cross-sectional shape of the pad center lower portion 64 is formed in a substantially J shape that is opposite to the left and right. The pad center lower part 64 has a shape in which the lower part swells in a convex curve shape from the upper part to the vehicle front side. The pad center lower portion 64 is locked from the lower side of the seat back to a connecting rod 68 that connects the lower ends of the side frames 26 in the seat width direction. The connecting rod 68 is disposed in parallel to the front side of the lower frame 30 of the seat back frame 14.

  Further, as shown in FIG. 3, the cross-sectional shape of the pad side portion 66 is formed in a substantially C shape. The pad side portion 66 is attached so as to be wound around the side frame 26 in a state where the connection fixing portion 50 is attached. The pad side portion 66 has a shape in which the lower portion bulges in a convex curved shape from the upper portion toward the front side of the vehicle, and bulges further toward the front side of the vehicle than the pad central upper portion 62 and the pad central lower portion 64. It has a shape that secures the side support performance.

  Returning to FIG. 4, the seat back board 16 described above is disposed from the back side lower end 62 </ b> A of the pad center upper part 62 to the back side upper end part 64 </ b> A of the pad center lower part 64 in the longitudinal sectional view. Precisely, the back side upper end portion 64A of the pad center lower portion 64 is formed thinner than the back side lower end portion 62A, and the lower end portion of the backboard portion 36 is disposed so as to overlap in the thinned portion. .

  Further, a lateral slit 70 as a through groove for hanging the cover is formed between the pad center upper part 62 and the pad center lower part 64 described above. Further, between the pad center upper part 62, the pad center lower part 64, and the pad side part 66, vertical slits 72 are formed as through grooves for hanging a pair of left and right covers. The slit width of the horizontal slit 70 and the vertical slit 72 is set to a length that allows the vertical mounting member 22 and the horizontal mounting member 24 to be described later to be inserted. Further, both the horizontal slit 70 and the vertical slit 72 are formed in a straight line, and penetrate the seat back pad 18 in the thickness direction (also in the vehicle front-rear direction).

<Configuration of cover 20>
As shown in FIG. 1, the cover 20 is formed in a size that can cover the seat back pad 18 from the front side. Further, the cover 20 includes a cover center upper portion 74, a cover center lower portion 76, and a pair of left and right cover side portions 78 in accordance with the divided configuration of the seat back pad 18.

<Mounting structure of cover 20>
The cover 20 is attached by means of a vertical mounting member 22, a horizontal mounting member 24, a vertical resin claw portion 58, a horizontal resin claw portion 60, an outer peripheral locking portion 80, and the like.

  As shown in FIG. 1, the vertical mounting member 22 includes a belt-shaped mounting member main body 22A, and a resin engaging portion formed on one side edge of the mounting member main body 22A and formed in a wedge shape. 22B. The other side edge of the attachment member main body 22A is attached in advance to the cover center upper portion 74, the cover center lower portion 76, and the cover side portion 78 by sewing. In FIG. 1, the vertical mounting member 22 (and the horizontal mounting member 24) is drawn separately from the cover 20, but the vertical mounting member 22 (and the horizontal mounting member 24) is attached to the cover 20 in advance. It has been. Correspondingly, longitudinal resin claws 58 are integrally formed on both outer sides of the back spring body 48 in the sheet width direction with respect to the corrugated portion 48A. The engaging portion 22 </ b> B of the vertical mounting member 22 can be elastically engaged with the vertical resin claw portion 58. Then, by engaging the engaging portions 22B of the pair of left and right vertical mounting members 22 with the corresponding vertical resin claws 58 of the respective back spring main body portions 48, the central portion of the cover 20 is seated in the vertical direction. Attached to the backboard 16.

  Similarly, the lateral mounting member 24 is configured by a mounting member main body 24A formed in a band shape, and a resin engaging portion 24B formed on one side edge of the mounting member main body 24A and formed in a wedge shape. Has been. The other side edge of the attachment member main body 24A is attached in advance to the cover center upper part 74 and the cover center lower part 76 by sewing. Correspondingly, the back spring main body portion 48 arranged at the uppermost stage is integrally formed with a lateral resin claw portion 60 at a central portion in the sheet width direction and at two locations on both outer sides. The engaging portion 24 </ b> B of the lateral mounting member 24 can be elastically engaged with the lateral resin claw portion 60. Then, as shown in FIG. 4, the engaging portions 24B of the lateral mounting members 24 provided at three locations are elastically engaged with the lateral resin claws 60 of the back spring main body portion 48 arranged at the uppermost stage. By doing so, the center portion of the cover 20 is attached to the seat back board 16 in the lateral direction.

  Further, an outer peripheral locking portion 80 having a hook shape is attached to an appropriate position of the outer peripheral portion of the cover 20 by sewing. The outer peripheral locking portion 80 is inserted and locked to the locking portion 42 of the backboard portion 36 from the vehicle rear side. Thereby, the outer peripheral part of the cover 20 is detachably locked to the backboard part 36.

<Structure of Upper Back Spring Body 54>
Next, the structure of the upper back spring body 54, which is a main part of the present embodiment, will be described in detail. As shown in FIGS. 5 and 6, the upper back spring main body 54 of a pair of left and right cantilever support structures is disposed on the upper side of the seat back board 16. Each upper back spring main body 54 is formed in a band plate shape. The length of the upper back spring body 54 in the longitudinal direction is set shorter than the length of the lower back spring body 48 in the longitudinal direction. Further, the base end portion 54 </ b> A of the upper back spring main body portion 54 is formed integrally with the inner side wall 50 </ b> A of the connection fixing portion 50. However, the upper back spring main body 54 is formed separately from the seat back board 16 including the connection fixing portion 50, and the base end portion of the upper back spring main body portion is integrated with the inner side wall 50A of the connection fixing portion 50 by heat welding or the like. May be. Further, a wavy portion 54C having the same shape as the wavy portion 48A described above is formed in a predetermined range including the front end portion 54B of the upper back spring main body portion 54.

  Further, the plate thickness of the upper back spring main body 54 described above is set so as to gradually decrease from the base end portion 54A on the left and right ends to the front end portion 54B on the center side. Therefore, the thickness t1 of the base end portion 54A of the upper back spring main body 54 and the thickness t2 of the distal end portion 54B have a relationship of t1> t2. As a result, the spring constant of the upper back spring body 54 is set smaller than the spring constant of the lower back spring body 48. 5 and 6, the thickness on the base end portion 54A side is drawn thicker than the actual thickness in order to emphasize this thickness difference. Further, in the present embodiment, the plate thickness of the upper back spring main body portion 54 is a gradual change structure, but it is only necessary that the distal end portion 54B side is thinner than the base end portion 54A that is the root side. Therefore, for example, a configuration in which the plate thickness changes in a stepped shape or a stepped shape may be used.

  In the present embodiment, the upper back spring main body 54 is configured in one stage (a pair of left and right), but is not limited thereto, and may be configured in a plurality of stages (a plurality of pairs of left and right). A configuration may be adopted in which a plurality of (a plurality of) back spring main body portions are provided at equal intervals.

(Operation and effect of this embodiment)
Next, the operation and effect of this embodiment will be described.

  The vehicle seat 10 having the above configuration includes the seat back board 16 in which a resin back spring part 38 is integrally formed with a resin back board part 36. Then, the seat back board 16 is fitted to the metal seat back frame 14 from the front side of the vehicle. Specifically, the left and right connecting and fixing portions 50 are fitted to the left and right side frames 26 from the front side of the vehicle, and are fixed to the side frames 26 from the outside in the seat width direction in this state. Thereafter, the seat back pad 18 is mounted on the seat back frame 14 from the front side of the vehicle, and the cover 20 is further put on the seat back pad 18. A vertical mounting member 22 and a horizontal mounting member 24 are fixed in advance to the cover 20 by sewing, and the vertical mounting member 22 and the horizontal mounting member 24 correspond to the vertical mounting member 22 while covering the seat back pad 18 with the cover 20. It inserts in the direction slit 72 and the horizontal direction slit 70, and is made to latch to the vertical resin claw part 58 and the horizontal resin claw part 60, respectively. Further, the outer peripheral locking portion 80 of the cover 20 is locked to the locking portion 42 of the backboard portion 36.

  The seat back 12 assembled as described above is a vehicle seat 10 to which a seat cushion 11 and a headrest (not shown) are attached. When the occupant sits on the vehicle seat 10, a load toward the rear side of the seat back (indicated by an arrow F in FIG. 3) is input to the back spring portion 38 via the cover 20 and the seat back pad 18. For this reason, the lower back spring main body 48 and the upper back spring main body 54 are bent and deformed to the rear side of the seat back, which is the load acting direction. Further, since the load at this time is transmitted from the connecting and fixing portion 50 to the left and right side frames 26, a reaction force from the side frames 26 to the front side of the vehicle (indicated by an arrow f in FIG. 3) is generated.

  Thus, when a load is input from the occupant to the back spring portion 38, the load is deformed and contributes to securing the cushioning property of the seat back 12, and the load itself is transmitted to the left and right side frames 26 to be transmitted to the left and right side frames. 26. As a result, the cushion performance of the seat back 12 is sufficiently ensured. Further, since the back spring portion 38 is made of resin and is provided integrally with the back board portion 36, the number of parts and the number of assembling steps are reduced as compared with the case where the back spring portion 38 is formed of a metal seat back spring. Is done. Therefore, according to the present embodiment, the cushion performance of the seat back 12 can be sufficiently secured, and further weight reduction and cost reduction can be achieved.

  Here, in this embodiment, as shown in FIG. 6, the resin spring disposed at a position facing the upper back of the seated occupant is divided into a pair of left and right upper back spring main body portions 54. Specifically, the pair of left and right upper back spring main body portions 54 has a cantilever support structure in which a base end portion 54A is connected to the coupling fixing portion 50 and a distal end portion is a free end. For this reason, the spring force due to the tension from both ends is not generated with respect to the load input P from the upper back of the seated occupant, and only the spring force Q as a bending beam is generated. Therefore, according to the present embodiment, the spring constant of the upper back spring main body portion 54 that supports the upper back of the seated occupant can be reduced as compared with the proportionality described later. Unlike the method of simply reducing the spring thickness to reduce the spring constant, the method of lowering the spring constant is adopted by changing the support structure for the side frame 26 from the double-support structure to the cantilever support structure. Further, the formability is not deteriorated, and the material properties such as fatigue limit stress are not hindered.

  On the other hand, as shown in FIG. 7, in the case of the upper back spring main body 90 of the both-end support structure, the load input P from the upper back of the seated occupant is received from both ends in addition to the spring force Q as a bending beam. The spring force R due to the tension is generated. For this reason, there is a possibility that the spring constant may be larger than that of the upper back spring main body 54 of the present embodiment, and the supporting force for supporting the seat back of the seated occupant may be stronger than necessary.

  In the present embodiment, the upper back spring main body 54 is configured to be changed from the both-end support structure to the cantilever support structure, so that a new component or the like is not necessary. For this reason, a structure becomes very simple.

  As described above, according to the present embodiment, the spring constant of the resin spring can be lowered with a simple configuration.

  In general, it is desirable that the upper part of the seated occupant is softly supported unlike the waist of the seated occupant. In the present embodiment, this required characteristic is required because the uppermost upper back spring main body 54 disposed at least in a position facing the back of the seated occupant in the back spring portion 38 is a cantilever support structure. The relationship between the supporting force and the spring constant is optimized. As a result, according to the present embodiment, the upper back of the seated occupant can be supported with an appropriate support force. In view of optimization of the spring constant, it is desirable to arrange a back spring part of a cantilever spring structure only on the back of the seated occupant.

  Further, in the present embodiment, when the pair of left and right upper back spring main body portions 54 are formed in a cantilever support structure, the load from the upper back of the seated occupant is the upper back spring of the cantilever support structure. The main body 54 is supported by the side frame 28 via the connection fixing portion 50. Moreover, since it is integrated with the backboard part 36, the number of parts is reduced. As a result, according to the present embodiment, it is possible to achieve cost reduction by reducing the number of parts.

  In the present embodiment, since the plate thickness of the upper back spring main body 54 of the cantilever support structure is set so as to decrease from the left and right end sides to the center side (because t1> t2 is set), the lower back spring Strength and rigidity are higher on the base end portion 54A side disposed on the left and right ends of the main body portion 54 than on the distal end portion 54B disposed on the center side. As a result, according to the present embodiment, it is possible to sufficiently withstand the local stress acting on the left and right ends of the upper back spring main body 54.

  As described above, the vehicle seat 10 including the seat back board 16 according to the present embodiment can reduce the number of parts and improve the productivity, and lower the spring constant of the resin spring with a simple configuration. Comfort at the time of sitting can be improved.

[Second Embodiment]
Next, a second embodiment of the seat back according to the present invention and a vehicle seat using the same will be described with reference to FIGS. In addition, about the same component as 1st Embodiment mentioned above, the same number is attached | subjected and the description is abbreviate | omitted.

  As shown in FIGS. 8 and 9, also in the seat back board 100 according to the second embodiment, the pair of left and right upper back spring main body portions 102 are connected to the base end portions 102 </ b> A, as in the first embodiment described above. A cantilever support structure connected to the fixed portion 50 is used. However, in this embodiment, the wavy portion is not formed in the tip portion 102B of the upper back spring main body portion 102. The point that the plate thickness gradually decreases from the base end portion 102A toward the tip end portion 102B is the same as in the first embodiment described above.

(Action / Effect)
Also with the above configuration, the pair of left and right upper back spring main body portions 102 have a cantilever support structure, so that the spring constant can be lowered as compared with the upper back spring main body portion of the both-end support structure. Therefore, the same effect as the first embodiment described above can be obtained.

[Third Embodiment]
Next, a third embodiment of the seat back according to the present invention and a vehicle seat using the same will be described with reference to FIG. In addition, about the same component as 1st Embodiment mentioned above, the same number is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 10, in the seat back board 110 according to the third embodiment, the front end portions 102 </ b> B of the pair of left and right upper back spring main body portions 102 in the configuration of the second embodiment described above are disposed directly below. The lower back spring body 48 is characterized by being connected by a pair of left and right connecting portions 112. Each connection part 112 is comprised as a strip | belt-shaped member arrange | positioned by making the seat back height direction into a longitudinal direction. Further, the connecting portion 112 is integrally formed when the seat back board 110 is molded.

(Action / Effect)
According to the above configuration, the front end portion 102B, which is the inner end portion of the upper back spring body portion 102 of the cantilever support structure, and the lower back spring of the both-end support structure set to a different height from the upper back spring body portion 102. Since the main body portion 48 is connected by the connecting portion 112, the spring constant is increased as compared with the case of only the upper back spring main body portion 102 having a cantilever support structure. That is, a resin spring having an intermediate spring constant between the upper back spring body portion 102 having a cantilever support structure and the upper back spring body portion 48 having a both end support structure can be obtained. As a result, the seat back of the seated occupant can be supported by a resin spring having an intermediate spring constant between the first embodiment and the second embodiment.

  In the above-described embodiment, the distal end portions 102B of the pair of left and right upper back spring main body portions 102 are connected to the lower back spring main body portion 48 arranged immediately below by the pair of left and right connecting portions 112. Instead, other connection methods may be employed. For example, instead of the pair of left and right connecting portions 112 arranged in parallel with the seat back height direction, the two may be connected by a connecting portion formed in a Y shape in front view.

[Supplementary explanation of the above embodiment]
In the embodiment described above, the resin back spring part 38 is integrally formed with the resin back board part 36. However, the present invention is not limited to this, and the resin back spring part is integrally provided with the resin back spring part 38. Also good. That is, the backboard portion and the back spring portion may be manufactured separately and then integrated by welding or the like. Further, the back spring main body portion and the connecting and fixing portion constituting the back spring portion may be manufactured as separate parts and then integrated by welding or the like. In addition, in the above-described embodiment, the connection fixing portion 50 has been described as a component on the back spring portion 38 side. However, even if the connection fixing portion 50 is regarded as a component on the backboard portion 36 side, it is interpreted as such. The thing itself can be one way. This is because, in the state of the finished seat backboard, whether to include the component of the connecting and fixing part on the back spring part side or on the backboard part side is just a matter of how to classify. is there.

  In the above-described embodiment, for example, the first embodiment, the thickness of the base end portion 54A of the upper back spring main body portion 54 is thicker than the thickness of the distal end portion 54B. In this relation, the back spring main body divided into the left and right may have a cantilever support structure.

  Further, in the above-described embodiment, for example, the first embodiment, the configuration in which the seat backboard 16 includes the backboard portion 36 in addition to the lower backspring body portion 48 and the upper backspring body portion 54 has been described. As described in the present invention, the vehicle seat does not include a backboard portion, and the base end portions of the pair of left and right upper back spring main body portions of the resin cantilever support structure are provided on each of the pair of left and right side frames. The vehicle seat may be supported.

DESCRIPTION OF SYMBOLS 10 Vehicle seat 12 Seat back 14 Seat back frame 16 Seat back board 18 Seat back pad 20 Cover 26 Side frame 36 Back board part 48 Lower back spring main part (back spring main part)
50 Connecting and fixing part 54 Upper back spring body part (back spring body part)
54A Base end 54B Tip 100 Seat back board 102 Upper back spring body (back spring body)
102A Base end portion 102B Tip end portion 110 Seat back board 112 Connecting portion

Claims (7)

A resin-made back spring body which is arranged along the seat width direction between a pair of left and right side frames provided in the seat back frame and which can be bent and deformed in the load acting direction by applying a load to the rear side of the seat back. Department,
Further, the back spring main body portion is divided into left and right, each base end portion is supported by the side frame, and the tip end portion has a cantilevered support structure.
Seat back board. A plurality of the back spring main body portions are arranged at intervals in the seat back height direction,
Of the plurality of back spring main body portions, at least a back spring main body portion disposed at a position facing the back of the seated occupant is a back spring main body portion of the cantilever support structure.
The seat back board according to claim 1. A resin backboard portion formed of a resin plate material and disposed on the back side of the seat back frame and the plurality of back spring main body portions are connected by a pair of left and right connection fixing portions fixed to the side frame. Has been
The plurality of back spring body portions including the back spring body portion of the cantilever support structure are integrally or integrally formed with the connection fixing portion.
The seat back board according to claim 2, wherein: The plate thickness of the back spring body portion of the pair of left and right cantilever support structures is set so as to become thinner from the left and right ends to the center side.
The seat back board according to claim 2 or claim 3, wherein The inner ends of the pair of left and right cantilevered back spring bodies and the back spring body of the both-end support structure set at a different height from the back spring body are connected by a connecting portion.
The seat backboard according to any one of claims 2 to 4, wherein the seatback board is characterized by the above. The seat back frame;
The seatback board according to any one of claims 1 to 5, supported by the pair of left and right side frames in the seatback frame,
A seat back pad disposed on the front side of the seat back board;
A cover covering the surface of the seat back pad;
A vehicle seat having: A seat back frame provided in the seat back and provided with a pair of left and right side frames;
Arranged between the pair of left and right side frames along the seat width direction and arranged at intervals in the seat back height direction, a load acting on the rear side of the seat back acts to bend in the load acting direction. A resin-made back spring body formed to be deformable,
A seat back pad disposed on the front side of the back spring body,
A cover covering the surface of the seat back pad;
With
Further, among the plurality of back spring main body portions, at least a back spring main body portion arranged at a position facing the back of the seated occupant is divided into left and right, and each base end portion is supported by the side frame and the distal end The part is a cantilever support structure with a free end.
Vehicle seat.