Seat backs for vehicle seats

Abstract

To hardly form a large gap between a back surface constitution part of a skin material and a lumbar support when a shape of the lumbar support is varied so that one part is positioned in front of the other parts.SOLUTION: A seat back for a vehicle seat includes: a cushion member 20 having a pair of side parts 28 connected to a central part and a pair of side edge parts of the central part to relatively rotate; a lumbar support 60 which makes contact with a rear surface of the central part, and in which a position in a front-back direction of one part is varied; a bag-like skin material 76 covering the cushion member and the lumbar support; a pair of side part restraint members 92, 95 which are connected to an inner surface of the skin material and restrain each of the pair of the side parts; and a pair of back surface restraint members 97 which are provided on an inner surface of a back surface constitution part 87A, 87B of the skin material and are connected to the respective side part restraint members.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a seat back for a vehicle seat. [Background technology]

[0002] Patent Document 1 below discloses a vehicle seat. The seat back of this vehicle seat includes a cushion member supported by a seat back frame, a lumbar support supported by the seat back frame, a drive device that changes the shape of the lumbar support, and a bag-shaped covering material that covers the cushion member and the lumbar support. When a force generated by the drive device is applied to the lumbar support, the lumbar support deforms so that a portion of the lumbar support is positioned further forward than other portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-4927 Summary of the Invention [Problem to be solved by the invention]

[0004] When the shape of the lumbar support changes, the shape of the back surface forming part of the covering material does not follow the change in shape of the lumbar support, and there is a risk that a large gap will be formed between the lumbar support and the back surface forming part.

[0005] In consideration of the above, the present invention aims to provide a seat back for a vehicle seat in which a large gap is unlikely to form between the back surface forming part of the upholstery material and the lumbar support when the shape of the lumbar support is changed so that a part of it is positioned further forward than the other parts. [Means for solving the problem]

[0006] The seat back of a vehicle seat according to the invention of claim 1 comprises: a cushion member having a central portion in the seat width direction and a pair of side portions connected to each of a pair of side edges of the central portion so as to be rotatable relative to the side edges; a lumbar support that contacts the rear surface of the central portion and is deformable so that a portion of the central portion's position in the fore-aft direction can change; a bag-shaped upholstery material that covers the cushion member and the lumbar support; a pair of side restraint members that are connected to the inner surface of the upholstery material and restrain each of the pair of side portions; and a pair of back restraint members that are provided on the inner surface of a back constituent portion of the upholstery material and are connected to the pair of side restraint members, respectively, so as to bring the back constituent portion closer to the lumbar support than when not connected to the side restraint members.

[0007] When a portion of the lumbar support of the seat back of claim 1 is moved forward, the cushion member receives a force from the lumbar support, causing both sides of the cushion member to rotate relative to the center. However, a pair of side restraint members connected to the inner surface of the upholstery material restrain each of the pair of side portions. Furthermore, a pair of back restraint members provided on the inner surface of the back component of the upholstery material are connected to the pair of side restraint members, respectively. Therefore, when a portion of the lumbar support is moved forward, each side portion is less likely to rotate relative to the center portion.

[0008] Furthermore, when the pair of rear restraint members are connected to the pair of side restraint members, respectively, the pair of rear restraint members brings the rear constituent part closer to the lumbar support than when the pair of rear restraint members are not connected to the side restraint members, so when the shape of the lumbar support is changed so that one part is positioned more forward than the other parts, a large gap is less likely to form between the rear constituent part of the upholstery material and the lumbar support.

[0009] The seat back of a vehicle seat according to the invention of claim 2 is the seat back of the vehicle seat according to claim 1, in which the left rear restraint member is connected to the right edge of the left side restraint member that restrains the side, and the right rear restraint member is connected to the left edge of the right side restraint member that restrains the side.

[0010] In the seat back of the vehicle seat according to the invention of claim 2, the distance in the left-right direction between the connection portions of the left and right rear restraint members with the corresponding side restraint members and the lumbar support is shorter than in the comparative example in which the left rear restraint member is connected to the left edge of the left side side restraint member that restrains the side and the right rear restraint member is connected to the right edge of the right side side restraint member that restrains the side. Therefore, compared to the comparative example, in the seat back of the vehicle seat according to the invention of claim 2, it is less likely that a large gap will be formed between the back surface forming portion of the upholstery material and the lumbar support.

[0011] The seat back of a vehicle seat according to the invention described in claim 3 is the seat back of a vehicle seat described in claim 1 or claim 2, in which a first recess is provided on the rear surface of the central portion, the first recess being located between a pair of side portions and accommodating the lumbar support, and the connection portions between the left and right rear restraint members and the side restraint members are located in the first recess.

[0012] In the seat back of the vehicle seat according to the invention of claim 3, the connection portions between the left and right rear restraint members and the side restraint members are located in the first recesses, which reduces the risk of these connection portions coming into contact with the inner surface of the rear constituent portion of the upholstery material, causing part of the rear constituent portion to bulge outward.

[0013] The seat back of a vehicle seat according to the invention of claim 4 is the seat back of a vehicle seat according to claim 1 or claim 2, wherein a pair of left and right through holes penetrating the central portion is provided in the central portion, and the side restraint members include a first restraint member having one end connected to the inner surface of the upholstery material and a first engagement portion provided at the other end, and a second restraint member having one end connected to the inner surface of the upholstery material and a second engagement portion engageable with the first engagement portion, and the first engagement portion of the first restraint member passing rearward through the through holes from the front of the cushion member engages with the second engagement portion of the second restraint member that contacts the rear surface of the side portion.

[0014] In the seat back of the vehicle seat according to the invention of claim 4, each side portion is surrounded by the inner surface of the upholstery material, the first restraining member, and the second restraining member, making it more difficult for each side portion to rotate relative to the center portion when a portion of the lumbar support is moved forward.

[0015] The seat back of a vehicle seat according to the invention described in claim 5 is the seat back of a vehicle seat described in claim 1 or claim 2, in which a second recess is formed on the rear surface of the left and right side portions, and the first engagement portion and the second engagement portion engage in the second recess.

[0016] In the seat back of the vehicle seat according to the invention of claim 5, the first engaging portion and the second engaging portion engage in the second recess formed on the rear surface of the left and right side portions, so that there is little risk that the first engaging portion and the second engaging portion will come into contact with the inner surface of the back surface constituent portion of the upholstery material, causing a portion of the back surface constituent portion to bulge outward. [Effects of the Invention]

[0017] As described above, with the seat back of the vehicle seat according to the present invention, when the shape of the lumbar support is changed so that one part is positioned further forward than the other parts, a large gap is unlikely to form between the back surface forming part of the upholstery material and the lumbar support. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a vehicle seat including a seat back according to an embodiment of the present invention; [Figure 2] FIG. 2 is an exploded perspective view of the cover material, the cushion member, and the lumbar support as viewed from the front. [Figure 3] FIG. 2 is an exploded perspective view of the cover material, the cushion member, and the lumbar support as viewed from the rear. [Figure 4] FIG. 2 is a rear view of the cushion member, the seat back frame, and the lumbar support. [Figure 5] FIG. 5 is a cross-sectional view taken along the arrow line 5-5 in FIG. 4. [Figure 6] FIG. 10 is a view of the left side of the cover material and cushion member separated from each other, as seen from the rear. [Figure 7] 10 is a view seen from behind showing a state in which a part of the cover material is placed over the cushion member and the first restraint member has passed through the slit to the rear. FIG. [Figure 8] 10 is a rear view showing the state in which the tip engaging portion and the engaging portion are connected in the rear recess of the cushion member. FIG. [Figure 9] FIG. 6 is a cross-sectional view of the completed seat back, corresponding to FIG. 5. [Figure 10] FIG. 10 is an enlarged view of a portion of FIG. [Figure 11] FIG. 2 is a schematic vertical cross-sectional side view of a cushion member, a lumbar support, a base material, and a buffer material. DETAILED DESCRIPTION OF THE INVENTION

[0019] A vehicle seat 10 (hereinafter referred to as seat 10) according to an embodiment of the present invention will be described below with reference to the accompanying drawings. Note that the arrow FR shown as appropriate in each drawing indicates the front direction of the vehicle, the arrow UP indicates the upward direction of the vehicle, and the arrow LH indicates the left side in the left-right direction of the vehicle (seat width direction). Hereinafter, when the terms front-rear, left-right, and up-down are used in the description, they refer to front-rear in the front-rear direction of the vehicle, left-right in the left-right direction of the vehicle (seat width direction), and up-down in the up-down direction of the vehicle.

[0020] 1 is provided on a floor surface 100 of the vehicle interior. The seat 10 includes a seat cushion 11, a seat back 15 whose lower end is rotatably connected to the rear end of the seat cushion 11, and a headrest 99. The seat cushion 11 is supported by slide rails (not shown) installed on the floor surface 100.

[0021] The seat back 15 includes a cushion member 20, a seat back frame 50, a lumbar support 60, a drive unit 65, a cover material 76, a first restraint member (side restraint member) 92, a second restraint member (side restraint member) 95, and a back restraint member 97.

[0022] The cushion member 20 shown in FIGS. 2 to 5 is made of, for example, polyurethane foam. The cushion member 20 has a main body portion 22 and a back portion 24. The back portion 24 forms the rear portion of the cushion member 20, and the main body portion 22 forms the rest of the cushion member 20. The back portion 24 has an upper constituent portion 26 and a pair of left and right side constituent portions 28 extending downward from both left and right ends of the upper constituent portion 26. Furthermore, a central recess (first recess) 29 is formed on the rear surface of the cushion member 20 and is located between the upper constituent portion 26 and the left and right side constituent portions 28. As shown in FIGS. 4 and 5, a frame storage space 30 that is approximately U-shaped in rear view is formed between the rear surface of the main body portion 22 and the back portion 24. The frame storage space 30 includes an upper space 32 formed between the upper constituent portion 26 and the rear surface of the main body portion 22, a left side space 34 formed between the right half of the left side constituent portion 28 and the rear surface of the main body portion 22, and a right side space 36 formed between the left half of the right side constituent portion 28 and the rear surface of the main body portion 22. Furthermore, the lower ends of the left side space 34 and the right side space 36 open at the lower end surfaces of the left and right side constituent portions 28.

[0023] The cushion member 20 has a central portion 37 and a pair of left and right side portions 38. The central portion 37 is formed by the left-right central portion of the main body portion 22 and the left-right central portion of the upper constituent portion 26. The left side portion 38 is formed by the left side portion of the main body portion 22, the left end portion of the upper constituent portion 26, and the left side constituent portion 28, while the right side portion 38 is formed by the right side portion of the main body portion 22, the right end portion of the upper constituent portion 26, and the right side constituent portion 28. Furthermore, the front portions of the left and right side portions 38 are formed by bulging portions 39 that protrude forward beyond the central portion of the front surface of the cushion member 20 (see FIG. 5). The left and right side portions 38 are rotatable relative to the central portion 37 around each side edge of the central portion 37. A rear recess (second recess) 40 is formed on the rear surface of the left and right side constituent portions 28, with the end portion on the central recess 29 side and the rear surface being open. Furthermore, a pair of left and right slits (through holes) 42 extending in the up-down direction are formed in the main body portion 22. Each slit 42 penetrates the main body portion 22 in the front-rear direction. As shown in Figure 4, when the cushion member 20 is viewed from behind, the left and right slits 42 are exposed through the central recess 29.

[0024] The metal seatback frame 50, which is a framework member of the seatback 15, includes an upper frame 52 extending in the left-right direction and a pair of left and right side frames 54 extending downward from both left and right end portions of the upper frame 52. The seatback frame 50 also has a support member (not shown) for supporting a lumbar support 60. As shown in FIG. 4 , the cushion member 20 is fixed to the seatback frame 50 in a state in which the upper frame 52 is inserted into the upper space 32, the left side frame 54 is inserted into the left side space 34, and the right side frame 54 is inserted into the right side space 36. The lower ends of the left and right side frames 54 protrude downward from the lower ends of the left and right side constituent portions 28.

[0025] The lumbar support 60 shown in Figures 2 to 4 is a one-piece molded product made of hard resin. The lumbar support 60 is elastically deformable. The overall shape of the lumbar support 60 is approximately rectangular when viewed from the front. The lumbar support 60 has multiple linear portions extending in the vertical direction and multiple linear portions extending in the horizontal direction. The shape of the lumbar support 60 is not limited to the shape shown in the drawings. For example, the lumbar support 60 may be a plate-like member whose front shape is approximately rectangular. The vertical and horizontal dimensions of the lumbar support 60 are smaller than those of the central recess 29. The lumbar support 60 is supported by the support member while being located inside the central recess 29. Furthermore, at least a portion of the front surface of the lumbar support 60 is in contact with the rear surface of the main body 22 (the bottom surface of the central recess 29).

[0026] As shown in FIG. 1, a drive device 65 having an electric actuator is provided inside the cushion member 20. When a switch member (not shown) provided in the seat back 15 is operated, the drive force of the electric actuator is transmitted from the drive device 65 to the lumbar support 60, causing the side shape of the lumbar support 60 to change. For example, the lumbar support 60 may assume the shape shown in FIGS. 2 and 3 inside the seat back 15. In this case, the side shape of the lumbar support 60 is substantially linear. Furthermore, as the drive force of the electric actuator is transmitted from the drive device 65 to the lumbar support 60, the lumbar support 60 may assume the shape shown in FIG. 11 inside the seat back 15. In this case, the side shape of the lumbar support 60 is a curved shape in which the central portion in the up-down direction is positioned forward relative to other portions.

[0027] As shown in FIGS. 1 to 3 , the covering material 76 has an upper component 78, a front center component 80, a pair of left and right front side component parts 82, a pair of left and right side component parts 84, and a back component part 86. The back component part 86 has a base material 87A and a cushioning material 87B. The upper edge of the base material 87A is connected to the rear edge of the upper component part 78, and the upper edge of the cushioning material 87B is connected to the upper part of the inner surface of the base material 87A. The front shape of the cushioning material 87B in the unfolded state is slightly smaller than the front shape of the central recess 29 and larger than the front shape of the lumbar support 60. The upper edge of the front center component part 80 is connected to the front edge of the upper component part 78, and both left and right side edges of the upper component part 78 are connected to the upper edges of the left and right side component parts 84. Furthermore, the left and right front side component parts 82 are connected to the side edges of the front center component part 80 and the front edges of the left and right side component parts 84.

[0028] The cover material 76 is made of a flexible material. For example, the upper component 78, the front center component 80, the pair of left and right front side component parts 82, the pair of left and right side component parts 84, and the base material 87A are made of genuine leather or synthetic leather. For example, the cushioning material 87B is made of a felt material that is thicker than the base material 87A. Furthermore, a first fastener 88 is provided at the rear edge of the left side component part 84 and the left edge of the base material 87A, and a second fastener 90 is provided at the rear edge of the right side component part 84 and the right edge of the base material 87A.

[0029] As shown in Figures 3 and 6, one end of a pair of left and right first restraining members 92 made of fabric material is connected to the connection between the front center component 80 and the left and right front side component parts 82. The vertical dimension of each first restraining member 92 is shorter than that of the front side component parts 82. A tip engagement part (first engagement part) 93 made of hard resin is fixed to the other end of each first restraining member 92. The tip engagement part 93 is a substantially rectangular plate material. Furthermore, an intermediate engagement part (connection part) 94 made of hard resin is fixed to one surface of the first restraining member 92. As shown in Figures 9 and 10, the cross section of the intermediate engagement part 94 is substantially J-shaped. That is, the intermediate engagement part 94 has an engagement groove 94A.

[0030] As shown in Figures 3 and 6, one end of a pair of second restraining members 95 made of left and right fabric materials is connected to the vicinity of the side edge (near the rear edge) of the inner surface of the left and right side surface constituent parts 84. The vertical dimension of each second restraining member 95 is shorter than that of the side surface constituent part 84. An engaging part (second engaging part) 96 made of hard resin is fixed to the other end of each second restraining member 95. As shown in Figures 9 and 10, the cross section of the engaging part 96 is approximately J-shaped. That is, the engaging part 96 has an engaging groove 96A. The vertical dimension of the engaging part 96 is approximately the same as that of the tip engaging part 93.

[0031] Furthermore, as shown in Figure 3, one end of rear restraint members 97, which are a pair of left and right cloth members, is connected to two locations on the inner surface of the base material 87A, one on each side. The vertical dimension of the rear restraint members 97 is shorter than that of the base material 87A. An engaging portion (connecting portion) 98 made of hard resin is fixed to the other end of the rear restraint member 97. The engaging portion 98 is a substantially rectangular plate material. The vertical dimension of the engaging portion 98 is substantially the same as that of the intermediate engaging portion 94.

[0032] The cover material 76 (first restraining member 92, second restraining member 95, back surface restraining member 97) is attached to the cushion member 20 in the following procedure.

[0033] 6, the first fastener 88 and the second fastener 90 of the cover material 76 that has been separated from the cushion member 20 are opened. Next, the front center constituent part 80 and the front side constituent part 82 of the cover material 76 that are positioned immediately in front of the cushion member 20 are placed over the front surface of the cushion member 20, and the upper constituent part 78 is placed over the top surface of the cushion member 20.

[0034] 7, the tip engaging portions 93 of the left and right first restraining members 92 are inserted into the corresponding slits 42 from the front of the main body 22, and the tip engaging portions 93 and portions of the first restraining members 92 are positioned immediately behind the main body 22. Furthermore, the left and right second restraining members 95 are brought close to the outer surfaces and rear surfaces of the corresponding side constituent portions 28.

[0035] 8 to 10, while the left and right first restraining members 92 and second restraining members 95 are stretched from their free states, the tip engaging portions 93 and engaging portions 96 are engaged with each other in the corresponding rear recesses 40. That is, each tip engaging portion 93 is inserted into the engaging groove 96A of the corresponding engaging portion 96. As a result, as shown in FIGS. 9 and 10, each front side constituent portion 82 of the covering material 76 is pressed against the front surface of the corresponding side portion 38, each side surface constituent portion 84 is pressed against the outer surface of the corresponding side portion 38, the second restraining member 95 is pressed against the rear surface of the corresponding side portion 38, and each first restraining member 92 is pressed against the inner surface of the corresponding side portion 38. That is, the covering material 76 (front side constituent portion 82, side surface constituent portion 84), the first restraining member 92, and the second restraining member 95 form a ring and restrain the corresponding side portion 38. At this time, the first restraining member 92 generates a forward tension T92 as shown in FIG.

[0036] Next, as shown in FIGS. 9 and 10 , the left and right rear restraint members 97 are extended from their free positions, and the engaging portions 98 are engaged with the corresponding intermediate engaging portions 94. That is, each engaging portion 98 is inserted into the engaging groove 94A of the corresponding intermediate engaging portion 94. At this time, the intermediate engaging portions 94, rear restraint members 97, and engaging portions 98 are positioned in the central recess 29. That is, the left rear restraint member 97 is connected to the right edge of the left first restraint member 92, and the right rear restraint member 97 is connected to the left edge of the right first restraint member 92. Furthermore, the first restraint members 92, which generate forward tension T92, pull the rear restraint member 97 forward. Therefore, the expanded cushioning material 87B moves forward and enters the central recess 29, and the cushioning material 87B comes into contact with the rear surface of the lumbar support 60. Furthermore, the left-right center of the base material 87A comes into contact with the rear surface of the cushioning material 87B. Furthermore, at this time, the rear surface restraining member 97 generates a rearward tension T97 as shown in FIG.

[0037] Finally, the first zipper 88 and the second zipper 90 are closed. This causes the cover material 76 to take on a bag-like shape, completing the seat back 15 shown in FIG. 1. A headrest 99 is attached to the upper end of the completed seat back 15. Furthermore, the lower ends of the left and right side frames 54 are connected to reclining devices (not shown) provided at the rear end of the seat cushion 11. This completes the seat 10 shown in FIG. 1.

[0038] Next, the operation and effects of this embodiment will be described.

[0039] For example, assume that an occupant seated in the seat 10, in which the side shape of the lumbar support 60 is substantially linear, operates a switch member to change the side shape of the lumbar support 60 to the curved shape shown in FIG. 11 . When a portion of the lumbar support 60 is positioned further forward than the other portions in this manner, the central portion 37 of the cushion member 20 receives force from the lumbar support 60, causing the left and right side portions 38 to attempt to rotate in the direction of arrow RW shown in FIG. 5 relative to the vertically extending side edges of the central portion 37. However, the upholstery material 76 (front side portion forming portion 82, side portion forming portion 84), the first restraining member 92, and the second restraining member 95 form an annular shape and restrain the corresponding side portions 38. Furthermore, the rear restraining member 97 applies a rearward tension T97 to the first restraining member 92. When this tension T97 extends from the first restraining member 92 to the side portions 38, it attempts to rotate the side portions 38 in the direction opposite to the direction of arrow RW shown in FIG. 5 . Therefore, the left and right side portions 38 are less likely to rotate relative to the central portion 37 than when the cover material 76 does not include the first restraining member 92, the second restraining member 95, and the back restraining member 97.

[0040] Furthermore, when the engagement portions 98 fixed to the rear restraint members 97 provided on the base material 87A are connected to the intermediate engagement portions 94 fixed to the first restraint members 92, respectively, the base material 87A and the cushioning material 87B are closer to the lumbar support 60 than when the rear restraint members 97 are not connected to the intermediate engagement portions 94. In particular, in this embodiment, the left rear restraint member 97 is connected to the right edge portion of the left first restraint member 92, and the right rear restraint member 97 is connected to the left edge portion of the right first restraint member 92. Therefore, the left-right distance between the left and right engagement portions 98 and the lumbar support 60 is shorter than when the left rear restraint member 97 is connected to the left edge portion of the left first restraint member 92, and the right rear restraint member 97 is connected to the right edge portion of the right first restraint member 92. Therefore, regardless of the shape of the side edges of the lumbar support 60, the shapes of the base material 87A and the cushioning material 87B tend to follow the shape of the lumbar support 60. Therefore, a large gap is unlikely to be formed between the cushioning material 87B and the lumbar support 60.

[0041] 10, the intermediate engaging portion 94, the rear surface restraining member 97, and the engaging portion 98 are located in the central recess 29. Therefore, there is little risk that the intermediate engaging portion 94, the rear surface restraining member 97, and the engaging portion 98 will come into contact with the cushioning material 87B of the cover material 76, causing a portion of the base material 87A to bulge rearward.

[0042] Furthermore, the tip engaging portion 93 and the engaging portion 96 engage in the rear recesses 40 formed on the rear surfaces of the left and right side constituent portions 28. Therefore, compared to a case where the rear recesses 40 are not formed in the side constituent portions 28, there is less risk that a part of the base material 87A will bulge rearward due to the tip engaging portion 93 and the engaging portion 96 coming into contact with the cushioning material 87B.

[0043] Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment.

[0044] For example, the back surface forming portion 86 of the covering material 76 does not have to include the cushioning material 87B.

[0045] The back surface forming portion 86 may be deformed in accordance with the deformation of the lumbar support 60 so that the back surface forming portion 86 does not come into contact with the lumbar support 60 .

[0046] Furthermore, the tip engaging portion 93 and the engaging portion 96 may have shapes different from those shown in the drawings, as long as they are shapes that allow them to engage with each other. Similarly, the intermediate engaging portion 94 and the engaging portion 98 may have shapes different from those shown in the drawings, as long as they are shapes that allow them to engage with each other.

[0047] The drive unit 65 may be a manual drive unit without an actuator. [Explanation of symbols]

[0048] 10 Vehicle seats (seats) 15 Seat back 20 Cushion member 29 Central recess (first recess) 37 Central part 38 Side 40 Rear recess (second recess) 42 Slit (through hole) 60 Lumbar Support 65 Drive unit 76 Skin material 86 Rear component 92 First restraint member (side restraint member) 93 Tip engaging part (first engaging part) 94 Intermediate engagement part (connection part) 95 Second restraint member (side restraint member) 96 Engagement portion (second engagement portion) 97 Rear restraint member 98 Engagement part (connection part)

Claims

1. a cushion member having a central portion in a seat width direction and a pair of side portions connected to a pair of side edges of the central portion so as to be relatively rotatable around the side edges; a lumbar support that is in contact with the rear surface of the central portion and is deformable so that a portion of the lumbar support changes its position in the front-to-rear direction; a bag-shaped covering material that covers the cushion member and the lumbar support; a pair of side restraining members connected to an inner surface of the skin material and restraining the pair of side portions, respectively; a pair of back restraint members that are provided on an inner surface of the back constituent part of the upholstery material and are connected to the pair of side restraint members, respectively, to bring the back constituent part closer to the lumbar support than when not connected to the side restraint members; A seat back of a vehicle seat comprising:

2. 2. The seat back of a vehicle seat as described in claim 1, wherein the left rear restraint member is connected to the right edge of the left side restraint member that is restraining the side portion, and the right rear restraint member is connected to the left edge of the right side restraint member that is restraining the side portion.

3. a first recessed portion located between the pair of side portions and configured to accommodate the lumbar support is provided on the rear surface of the central portion; 3. The seat back of a vehicle seat according to claim 1, wherein connection portions between the left and right rear restraint members and the side restraint members are located in the first recesses.

4. a pair of left and right through-holes penetrating the central portion are provided in the central portion, the side restraining member comprises a first restraining member having one end connected to the inner surface of the skin material and having a first engaging portion at the other end, and a second restraining member having one end connected to the inner surface of the skin material and having a second engaging portion at the other end that can engage with the first engaging portion, 3. A seat back of a vehicle seat as described in claim 1 or claim 2, wherein the first engagement portion of the first restraint member passing through the through hole from the front of the cushion member to the rear engages with the second engagement portion of the second restraint member contacting the rear surface of the side portion.

5. a second recess formed in the rear surface of each of the left and right side portions; The seat back of a vehicle seat according to claim 4 , wherein the first engaging portion and the second engaging portion engage with each other in the second recess.

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