Backrest and chair

Abstract

To provide a backrest and a chair capable of improving external appearance.SOLUTION: A backrest according to one embodiment of the invention includes a backrest body supported by a support structure that has a tilt member tiltable around an axis line along a longitudinal direction. The backrest body comprises: a horizontal rod part which has an upper face that extends downward toward the front, and extends in the longitudinal direction; a housing part which is provided to project upward from the horizontal rod part at the center of the horizontal rod part in the longitudinal direction and stores part of the tilt member; and a load sustaining part which is located above the horizontal rod part and receives a sitting person's back part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a backrest and a chair. [Background technology]

[0002] A chair backrest is known that is supported on a base of a support structure via an arm so as to be tiltable. This type of backrest includes a back frame and an upholstery material stretched across the back frame. For example, in the following Patent Document 1, the back frame includes a pair of left and right side frame members and a lower frame member that connects the lower ends of the side frame members together and is connected to the arm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-079900 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, if the support base is exposed from below the backrest (lower frame) when the chair is viewed from behind, this is a factor that detracts from the appearance of the chair. On the other hand, if the lower frame is made thicker so that the support base is not exposed from below the lower frame, there is a concern that the appearance of the backrest itself will be degraded.

[0005] The present invention provides a backrest and a chair that can improve the appearance. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following aspects. (1) A backrest in one embodiment of the present invention comprises a backrest main body supported on a support structure via a tilting member that is tiltable around an axis along the left-right direction, and the backrest main body has an upper surface that extends downward as it faces forward, and is equipped with a horizontal rod portion extending in the left-right direction, a storage portion that is provided in the left-right center of the horizontal rod portion and protrudes upward from the horizontal rod portion, and that stores a part of the tilting member, and a load-receiving portion that is located above the horizontal rod portion and supports the back of a seated occupant.

[0007] According to this aspect, since the upper surface of the horizontal rod is formed as a sloping surface that slopes downward toward the front, it is possible to provide a storage section above the horizontal rod in a space within the height range of the front and rear ends of the horizontal rod. Therefore, the exposed area of ​​the support base when viewed from the rear can be reduced, and the appearance of the chair can be improved. In addition, since the upper surface of the horizontal rod is formed as a sloping surface, the horizontal rod can be made to look slimmer (thinner) when viewed from the rear. Therefore, the appearance of the backrest itself can be improved compared to a configuration in which the entire horizontal rod is made thicker in order to reduce the exposed area of ​​the support base.

[0008] (2) In the backrest according to the above aspect (1), it is preferable that the lower surface of the horizontal rod portion extends downward as it moves forward. According to this aspect, by forming the lower surface of the horizontal rod portion as a sloping surface that slopes downward toward the front, it is easier to ensure the vertical dimension of the horizontal rod portion compared to when the lower surface of the horizontal rod portion is formed as a flat surface along a horizontal plane, for example. Therefore, it is easier to ensure the rigidity of the horizontal rod portion while making the horizontal rod portion appear slimmer when the chair is viewed from the rear.

[0009] (3) In the backrest according to the above aspect (1) or (2), it is preferable that the dimension of the horizontal rod portion in the up-down direction gradually increases toward the front. According to this aspect, it is easier to ensure the rigidity of the horizontal rod portion while making the horizontal rod portion appear slimmer when the chair is viewed from the rear.

[0010] (4) In the backrest according to the above aspect (3), it is preferable that the horizontal rod portion is formed with a forward-facing recess that opens forward and extends in the left-right direction. According to this aspect, even if the dimension of the horizontal rod portion in the up-down direction increases toward the front, the thickness of the horizontal rod portion can be made uniform over the entire length in the front-rear direction, which makes it possible to suppress the occurrence of sink marks and the like and to form the horizontal rod portion with high precision.

[0011] (5) In the backrest relating to the above aspect (4), it is preferable that the horizontal rod portion bridges between opposing surfaces of the inner surface of the forward-facing recess in the vertical direction and has a plurality of first ribs spaced apart in the left-right direction. According to this aspect, it is possible to suppress a decrease in rigidity of the horizontal rod portion that would otherwise be caused by the formation of the forward-facing recess.

[0012] (6) In a backrest relating to any one of the above aspects (1) to (5), it is preferable that the horizontal rod portion is formed in a downwardly convex arc shape when viewed from the front, and that a downwardly facing recess that opens downward is formed in the portion of the horizontal rod portion that overlaps the storage portion when viewed in a plane. According to this aspect, the portion of the horizontal rod portion that overlaps with the storage portion, which is formed in an arc shape, can be set to the portion that protrudes the furthest downward. In other words, while reducing the exposed area of ​​the base, it is not necessary to set the position of the entire horizontal rod portion downward. Therefore, a high degree of freedom in design can be ensured. Also, by forming a downward recess in the part that protrudes most downward, the vertical size of the entire backrest can be reduced. The mold for manufacturing this backrest can also be made smaller, leading to reduced manufacturing costs. Moreover, in this embodiment, the part of the horizontal rod where the storage part is provided can be prevented from becoming thicker than the other parts. This prevents the occurrence of sink marks and the like, and allows the horizontal rod to be formed with high precision.

[0013] In the backrest according to the above aspect (7), it is preferable that the rear end edge of the downward recess is located forward of the rear end edge of the horizontal rod portion in the front-rear direction. According to this aspect, the downward recess is unlikely to be exposed when the backrest is viewed from behind, which improves the appearance of the backrest.

[0014] (8) In the backrest relating to the above-mentioned (6) or (7) embodiment, it is preferable that the downward surface of the inner surface of the downward recess is formed with a second rib that protrudes downward from the downward surface and extends in a direction intersecting the vertical direction. According to this aspect, the storage section can be reinforced from below, which prevents a decrease in the rigidity of the storage section due to the formation of the downward recess, and enables the support base and the backrest to be firmly fixed together.

[0015] (9) In the backrest according to the above aspect (8), it is preferable that a lower end edge of the second rib is positioned higher than a lower end opening of the downward recess. According to this aspect, when the chair is viewed from the rear, the second rib can be prevented from being exposed.

[0016] (10) In a backrest relating to any one of the above aspects (1) to (9), it is preferable that the backrest main body extends downward from both left and right ends of the load-receiving portion and has a pair of side rod portions connected to the horizontal rod portion. According to this aspect, the load receiving portion and the horizontal rod portion are connected via a pair of side rod portions, so that the seating load input to the load receiving portion can be transmitted to the horizontal rod portion from both the left and right sides. This allows the seating load to be mitigated by the entire horizontal rod portion, and the load acting on the connecting portion between the storage portion and the tilting member can be reduced. Therefore, it is possible to provide a backrest with excellent durability while improving the appearance of the backrest.

[0017] (11) A chair according to one aspect of the present invention includes a backrest according to any one of the above aspects (1) to (10). According to this aspect, a chair having excellent durability can be provided while improving the appearance. Effect of the Invention

[0018] According to each of the above aspects, it is possible to improve the durability while improving the appearance. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a perspective view of the chair according to the embodiment, seen from the left rear. [Diagram 2] FIG. 2 is a rear view of the chair according to the embodiment. [Diagram 3] FIG. 2 is an exploded perspective view of the support base and the backrest according to the embodiment. [Figure 4] 4 is a cross-sectional view corresponding to line IV-IV in FIG. 3. [Diagram 5] FIG. 2 is a front view of the lower frame portion according to the embodiment. [Figure 6] 3 is a cross-sectional view corresponding to the line VI-VI in FIG. 2. [Figure 7] FIG. 2 is a bottom view of the chair according to the embodiment with the legs removed. [Figure 8] 8 is a cross-sectional view corresponding to line VIII-VIII in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Next, an embodiment of the present invention will be described with reference to the drawings. In the embodiments and modifications described below, the same reference numerals may be used to designate corresponding configurations, and the description may be omitted. In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," not only strictly indicate such arrangements, but also indicate a state in which the two surfaces are relatively displaced with an angle or distance to the extent that the same function is obtained. In this embodiment, "facing" does not only mean a case in which the orthogonal directions (normal directions) of the two surfaces are aligned with each other, but also includes a case in which the orthogonal directions intersect with each other.

[0021] [Chair 1] Fig. 1 is a perspective view of the chair 1 as seen from the rear left. Fig. 2 is a rear view of the chair 1. As shown in Figures 1 and 2, chair 1 has a support structure 2, seat 3, backrest 4, and armrests 5. In the following description, the directions of front, back, up, down, left and right, etc. are the same as the directions of a person (seater) sitting in the correct posture on chair 1. In this case, arrow UP in the figures indicates upward, arrow FR indicates forward, and arrow LH indicates left. In the following description, the side away from the center of chair 1 in the front-back, up-down, and left-right directions may be referred to as the outside, and the side toward the center of chair 1 may be referred to as the inside.

[0022] <Support structure 2> The support structure 2 includes a leg body 11, a support base 12, and a seat receiving member 20 (see FIG. 3). The leg body 11 includes a multi-pronged leg 13 and a leg column 14 . A caster 15 capable of running on a floor surface F is attached to each leg of the multi-legged stand 13.

[0023] The leg pillar 14 extends upward from the center of the multi-leg 13. A gas spring 16, which is a lifting mechanism for the chair 1, is built into the leg pillar 14. The gas spring 16 is configured such that an inner cylinder 16a is supported so as to be liftable and rotatable relative to an outer cylinder (not shown) provided within the leg pillar 14, for example.

[0024] The support base 12 is connected to the upper end of the leg pillar 14 (inner cylinder 16a). The support base 12 supports the seat 3 from below, and also supports the backrest 4 so that it can tilt.

[0025] Fig. 3 is an exploded perspective view of the support base 12 and the backrest 4. Fig. 4 is a cross-sectional view corresponding to the line IV-IV in Fig. 3. As shown in FIGS. 3 and 4, the support base 12 includes a casing 21 and a tilting member 22. The casing 21 and the tilting member 22 are arranged in a casing shape. The casing 21 is formed in a hollow rectangular parallelepiped shape. The upper end of the inner cylinder 16a is connected to the bottom wall of the casing 21. In addition, a lifting mechanism for operating the gas spring 16, a tilting mechanism for tilting the backrest 4, etc. are provided inside the casing 21.

[0026] The tilting member 22 is a member that connects the backrest 4 and the casing 21. The tilting member 22 is supported by the casing 21 so as to be rotatable about an axis O along the left-right direction. The tilting member 22 is formed in a U-shape that opens forward in a plan view. Specifically, the tilting member 22 includes a pair of arms 25 and a connecting plate 26. The pair of arms 25 extend in the front-rear direction while facing each other in the left-right direction. Each arm 25 is supported within the casing 21 with its rear end protruding rearward from the casing 21. Specifically, a shaft member 28 extending in the left-right direction along an axis O is provided within the casing 21. Each arm 25 is supported by the casing 21 via the shaft member 28, and is configured to be rotatable about the axis O relative to the casing 21 (and the legs 11). A tilting mechanism is connected to a portion of the pair of arms 25 that is located forward of the shaft member 28. The tilting member 22 rotates about the shaft member 28 as a fulcrum by the operation of the tilting mechanism.

[0027] The connecting plate 26 connects the rear ends of the arms 25 together. The connecting plate 26 extends in the left-right direction with the thickness direction being the up-down direction. The connecting plate 26 has a plurality of through holes 26a that penetrate the connecting plate 26 in the up-down direction. In this embodiment, the tilting member 22 has been described as a part of the support base 12, but this is not limited to the configuration. The tilting member 22 may be provided as a part of the backrest 4, or may be provided separately from both the support base 12 and the backrest 4.

[0028] The seat receiving member 20 is fixed to the upper wall of the casing 21 in a state in which it covers the casing 21 from above.

[0029] <Location 3> The seat 3 is formed in a downwardly protruding arc shape when viewed from the front, and supports the portion of the seated person from the buttocks to the thighs from below. As shown in Figure 1, the seat 3 includes a seat shell 30 and a seat body 31. The seat shell 30 is a resin-molded plate-like member that forms the framework of the seat 3. The seat shell 30 is attached to the seat receiving member 20 in a state in which it covers the entire seat receiving member 20 from above. In the illustrated example, the lower surface of the seat shell 30 is formed into an inclined surface (curved surface) that extends upward toward the outside in the left-right direction.

[0030] The seat body 31 is supported from above by the seat shell 30. The seat body 31 includes a cushion material placed on the upper surface of the seat shell 30, and a cover material that covers the cushion material from above.

[0031] <Backrest 4> The backrest 4 supports the seated occupant's lower back and back from behind. The backrest 4 is connected to a tilting member 22 so as to be tiltable relative to the leg 11 about an axis O (see FIG. 4).

[0032] The backrest 4 includes a back frame (backrest main body) 41 and a surface material 42. The back frame 41 is a strength member that constitutes the outer shape of the backrest 4. The back frame 41 is molded from a resin material or the like. The back frame 41 is formed in a circular arc shape protruding backward in a plan view, and in an S-shape in a side view. As shown in Figs. 1 and 2, the back frame 41 is formed in an 8 (B) shape in a front view with the upper frame portion 41A and the lower frame portion 41B connected in the vertical direction. Specifically, the back frame 41 includes an upper horizontal rod portion 51, a pair of upper vertical rod portions 52, a middle horizontal rod portion 53, a pair of lower vertical rod portions 54, a lower horizontal rod portion 55, a support base attachment portion 56, and an armrest attachment portion 57.

[0033] The upper horizontal rod portion 51 constitutes the upper end portion of the back frame 41. The upper horizontal rod portion 51 extends in the left-right direction in a convex arc shape toward the rear in a plan view. The vertical dimension of the upper horizontal rod portion 51 gradually increases toward the front.

[0034] The upper vertical rod portion 52 extends downward from both left-right ends of the upper horizontal rod portion 51. The upper vertical rod portion 52 has a bent portion at a portion located below the center in the up-down direction. In a side view, the portion of the upper vertical rod portion 52 located above the bent portion extends at an incline backward as it extends upward, and the portion of the upper vertical rod portion located below the bent portion extends at an incline backward as it extends downward. On the other hand, in a front view, the portion of the upper vertical rod portion 52 located above the bent portion extends inward in the left-right direction as it extends upward, and the portion of the upper vertical rod portion located below the bent portion extends inward in the left-right direction as it extends downward. The left-right dimension of the upper vertical rod portion 52 gradually increases toward the front.

[0035] The middle horizontal rod portion 53 connects the lower ends of the upper vertical rod portions 52. In a plan view, the middle horizontal rod portion 53 extends in the left-right direction in a circular arc shape that protrudes backward. In a cross-sectional view, the middle horizontal rod portion 53 is formed into a C-shape that opens forward with the rear ends of the upper wall portion 53a and the lower wall portion 53b connected to each other. A rib 53c (see FIG. 6) that connects the lower surface of the upper wall portion 53a and the upper surface of the lower wall portion 53b is provided on the inside of the middle horizontal rod portion 53. The vertical dimension of the middle horizontal rod portion 53 gradually increases toward the front. As shown in FIG. 4, the upper surface of the middle horizontal rod portion 53 (upper wall portion 53a) is formed into an inclined surface that slopes upward toward the front. On the other hand, the lower surface of the middle horizontal rod portion 53 (lower wall portion 53b) is formed into a flat surface that extends in the front-rear direction. However, the lower surface of the middle horizontal rod portion 53 may be inclined upward toward the front as long as the angle (elevation angle) between the lower surface and the horizontal plane is smaller than the angle (elevation angle) between the upper surface and the horizontal plane. The upper frame portion 41A of the back frame 41 is composed of the upper horizontal rod portion 51, the upper vertical rod portion 52, and the middle horizontal rod portion 53. The upper frame portion 41A is open in the front-rear direction.

[0036] As shown in Fig. 2, a lumbar support 50 for supporting the waist of a seated person is provided in the center of the middle horizontal rod portion 53 in the left-right direction. The lumbar support 50 protrudes upward from the middle horizontal rod portion 53 so as to face the inside of the upper frame portion 41A. Note that the lumbar support 50 is not an essential component.

[0037] FIG. 5 is a front view of lower frame portion 41B. As shown in FIG. 2 and FIG. 5, the lower vertical rod portion 54 extends downward from the boundary portion between the upper vertical rod portion 52 and the middle horizontal rod portion 53. In a front view, the lower vertical rod portion 54 is inclined toward the outside in the left-right direction as it goes downward. The upper end portion of the lower vertical rod portion 54 is connected so as to straddle between the lower end portion of the upper vertical rod portion 52 and the lower wall portion 53b of the middle horizontal rod portion 53. In a front view, the middle portion of the lower vertical rod portion 54 in the up-down direction overlaps with the outer end portion of the seat 3 in the left-right direction. The lower end portion of the lower vertical rod portion 54 is located below the seat 3. As shown in FIG. 1, the lower vertical rod portion 54 is inclined toward the front as it goes downward in a side view. The front end portion of the lower vertical rod portion 54 is located forward of the bent portion of the upper vertical rod portion 52. The lower vertical rod portion 54 is formed in a rectangular shape with its short sides in the left-right direction and its long sides in the front-rear direction in a plan view. The lower vertical rod portion 54 extends obliquely outward in the left-right direction as it extends forward.

[0038] As shown in FIG. 2 and FIG. 5, the lower horizontal rod portion 55 bridges the lower ends of the lower vertical rod portions 54. The lower horizontal rod portion 55 is formed in a downwardly convex arc shape in a front view. The radius of curvature of the entire lower horizontal rod portion 55 in a front view is set to be equal to the radius of curvature of the lower surface of the seat 3. That is, the lower horizontal rod portion 55 extends below the seat 3 following the lower surface of the seat 3 in a front view. In the illustrated example, the radius of curvature of the upper surface of the lower horizontal rod portion 55 is larger than the radius of curvature of the lower surface. Therefore, the dimension of the lower horizontal rod portion 55 in the vertical direction gradually decreases toward the outside in the left-right direction. However, the radius of curvature of the lower horizontal rod portion 55 may be the same on both the upper and lower surfaces.

[0039] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. As shown in FIG. 6, the lower horizontal rod portion 55 is located forward of the middle horizontal rod portion 53 in side view. Specifically, the upper surface of the lower horizontal rod portion 55 is formed as an inclined surface (or a curved surface) that extends downward as it approaches the front. Therefore, above the lower horizontal rod portion 55, the space within the height range of the front end and the rear end of the lower horizontal rod portion 55 functions as a shielded space Q that cannot be seen from behind the backrest 4. On the other hand, the lower surface of the lower horizontal rod portion 55 is formed as an inclined surface (or a curved surface) that extends downward as it approaches the front. The angle (depression angle) θ1 between the lower surface of the lower horizontal rod portion 55 and the horizontal plane is larger than the angle (depression angle) θ2 between the upper surface of the lower horizontal rod portion 55 and the horizontal plane. Therefore, in a side view, the lower horizontal rod portion 55 is inclined downward as it approaches the front, and the vertical dimension T gradually increases as it approaches the front. In this embodiment, the dimension T is the dimension in the normal direction of the lower surface (or upper surface) of the lower horizontal rod portion 55 in a side view.

[0040] The rear end surface of the lower horizontal rod portion 55 connects the rear ends of the upper and lower surfaces of the lower horizontal rod portion 55. The rear end surface of the lower horizontal rod portion 55 is an inclined surface that extends upward as it approaches the front. The front end surface of the lower horizontal rod portion 55 connects the front ends of the upper and lower surfaces of the lower horizontal rod portion 55. The front end surface of the lower horizontal rod portion 55 is an inclined surface that extends upward as it approaches the front.

[0041] As shown in Figs. 5 and 6, the lower horizontal rod portion 55 has a forward recess 55a that opens on the front end surface of the lower horizontal rod portion 55. Specifically, the front end opening of the forward recess 55a opens diagonally downward toward the front. The forward recess 55a is formed in a triangular shape whose vertical dimension gradually decreases toward the rear in a side view. In this embodiment, the forward recess 55a is formed on both sides of the lower horizontal rod portion 55 except for the central portion in the left-right direction. The forward recess 55a has a vertical dimension gradually decreasing toward the outside in the left-right direction in a front view, similar to the lower horizontal rod portion 55.

[0042] A plurality of vertical ribs 60 are formed on the inside of the forward recess 55a. The vertical ribs 60 are provided at intervals in the left-right direction in each forward recess 55a. Each vertical rib 60 extends vertically and connects the inner surfaces of the forward recess 55a that face each other in the up-down direction (the upward surface 55b facing upward and the downward surface 55c facing downward). The vertical ribs 60 extend over the entire length of the forward recess 55a in the front-rear direction.

[0043] FIG. 7 is a bottom view of the chair 1 with the legs 11 removed. As shown in FIG. 4, FIG. 5, and FIG. 7, a downward recess 55d is formed in the center of the lower horizontal rod portion 55 in the left-right direction. The downward recess 55d is open from the front end surface to the lower surface of the lower horizontal rod portion 55. Specifically, the front end opening 55d1 of the downward recess 55d is formed in a rectangular shape in a front view. The front end opening 55d1 has a uniform width in the left-right direction over the entire vertical direction. The lower end opening 55d2 of the downward recess 55d is connected to the lower end of the front end opening 55d1. The lower end opening 55d2 is formed in a trapezoid shape whose width in the left-right direction gradually decreases toward the rear in a plan view. The rear end edge of the downward recess 55d terminates at a portion located forward of the rear end surface of the lower horizontal rod portion 55.

[0044] A plurality of front-rear ribs 64a and left-right ribs 64b are formed in the downward recess 55d. The front-rear ribs 64a are provided at intervals in the left-right direction. The front-rear ribs 64a protrude downward from a downward surface 55d3 facing downward among the inner surfaces of the downward recess 55d and extend in the front-rear direction. The rear end edge of the front-rear rib 64a is connected to a front surface 55d4 facing forward among the inner surfaces of the downward recess 55d. The front-rear rib 64a is set so as not to protrude from the downward recess 55d. Specifically, the vertical dimension of the front-rear rib 64a is smaller than the vertical dimension of the front surface 55d4. Therefore, the lower end edge of the front-rear rib 64a is located above the lower end opening 55d2 of the downward recess 55d. However, the lower end edge of the front-rear rib 64a may be located at the same height as the lower end opening 55d2 of the downward recess 55d or below the lower end opening 55d2. On the other hand, the front end surface of the front-rear rib 64a is formed as an inclined surface that extends upward as it approaches the front, following the front end surface of the lower horizontal rod portion 55.

[0045] The left and right ribs 64b protrude downward from the center in the front-rear direction of the downward surface 55d3 of the downward recess 55d and extend in the left-right direction. The left and right ribs 64b intersect with the front-rear ribs 64a. The left and right ribs 64b bridge the left and right faces of the inner surface of the downward recess 55d. The left and right ribs 64b protrude from the downward surface 55d3 by the same amount as the front-rear rib 64a. However, the dimensions of the front-rear ribs 64a and the left and right ribs 64b can be changed as appropriate.

[0046] A hanging wall 55d5 is formed on the front end edge of the downward surface 55d3 of the downward recess 55d. The hanging wall 55d5 protrudes downward from the downward surface 55d3 and bridges the left and right surfaces of the inner surface of the downward recess 55d. The front surface of the hanging wall 55d5 is flush with the front end surface of the lower horizontal rod portion 55. The amount of protrusion of the hanging wall 55d5 from the downward surface 55d3 is smaller than the amount of protrusion of the ribs 64a and 64b from the downward surface 55d3.

[0047] The back frame 41 is made up of a middle horizontal rod portion 53, a lower vertical rod portion 54, and a lower horizontal rod portion 55 to form a lower frame portion 41B. The lower frame portion 41B is open in the front-rear direction. As shown in Figs. 1 and 6, the rear end portion of the seat 3 enters the inside of the lower frame portion 41B from the front of the lower frame portion 41B. Specifically, the rear end portion of the seat 3 is surrounded on both the front and rear sides by the middle horizontal rod portion 53 and the lower horizontal rod portion 55, and is surrounded on both the left and right sides by the lower vertical rod portion 54. As shown in Fig. 4, the front end surface of the middle horizontal rod portion 53 of the lower frame portion 41B is located forward of the rear end of the seat 3, and the rear end surface of the lower horizontal rod portion 55 is located forward of the rear end of the seat 3.

[0048] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. As shown in FIG. 4 and FIG. 8, the base mounting portion 56 is integrally formed with the lower horizontal rod portion 55. The base mounting portion 56 is formed in a box shape that protrudes upward from the lower horizontal rod portion 55 and opens forward. That is, at least a part of the base mounting portion 56 is located within the shielded space Q. Specifically, the base mounting portion 56 includes a bottom wall portion 70, a pair of side walls 71, and a top wall portion 72. The bottom wall portion 70 is formed by a portion of the lower horizontal rod portion 55 that is located above the downward recess 55d (a portion that divides the downward recess 55d in the vertical direction). The bottom wall portion 70 is formed with a through hole 70a that penetrates the bottom wall portion 70 in the vertical direction. A plurality of through holes 70a are formed in the bottom wall portion 70 at positions that avoid the front and rear ribs 64a. In the illustrated example, a boss portion 70a1 surrounding the through hole 70a is formed in the bottom wall portion 70 at a portion located around the through hole 70a. The boss portion 70a1 protrudes downward from the downward surface 55d3. The outer peripheral surface of the boss portion 70a1 is appropriately connected to the inner surface of the downward recess 55d, the ribs 64a, 64b, and the hanging wall 55d5.

[0049] As shown in Fig. 8, the side wall portion 71 protrudes upward from portions of the lower horizontal rod portion 55 located on both the left and right sides of the downward recess 55d. The left-right thickness of the side wall portion 71 is greater than the up-down thickness of the bottom wall portion 70 (and the top wall portion 72). As shown in Fig. 6, the up-down dimension of the side wall portion 71 (the amount of protrusion from the upper surface of the lower horizontal rod portion 55) gradually decreases toward the rear. The rear end of the side wall portion 71 is located forward of the rear end surface of the lower horizontal rod portion 55.

[0050] As shown in Figs. 4 and 8, the top wall 72 connects the upper ends of the side walls 71. In a side view, the top surface of the top wall 72 is formed as a flat surface extending linearly in the front-rear direction, or an inclined surface extending upward toward the front. When the top surface of the top wall 72 is inclined with respect to the horizontal plane, it is preferable that the absolute value of the angle between the top surface of the top wall 72 and the horizontal plane is smaller than the absolute value of the angle θ2 at the top surface of the lower horizontal rod 55. This reduces the amount of protrusion of the top wall 72 upward from the rear end of the lower horizontal rod 55, as shown in Fig. 2.

[0051] As shown in FIG. 8, the inside of the base mounting portion 56 forms an insertion groove 56a into which the tilting member 22 is inserted. The insertion groove 56a is formed in an H-shape when viewed from the front. Specifically, the insertion groove 56a includes a pair of vertical grooves 56a1 and a horizontal groove 56a2 that connects the pair of vertical grooves 56a1. The arms 25 of the tilting member 22 are inserted from the front into the vertical grooves 56a1. The connecting plate 26 is inserted from the front into the horizontal grooves 56a2. In the horizontal grooves 56a2, a screw seat plate 76 is overlapped above the connecting plate 26.

[0052] The tilting member 22 is fixed to the backrest 4 (lower horizontal rod portion 55) by a screw 77 inserted from below the bottom wall portion 70 through the through hole 70a. Specifically, the screw 77 is inserted into the through hole 70a of the bottom wall portion 70 and the through hole 26a of the connection plate 26, and then penetrates the bottom wall portion 70 and the connection plate 26, and is then fastened to the screw seat plate 76. That is, the connection plate 26 and the bottom wall portion 70 are sandwiched in the vertical direction between the head of the screw 77 and the screw seat plate 76, thereby connecting the tilting member 22 and the backrest 4. The vertical height of the head of the screw 77 is lower than the vertical height of the front surface 55d4 of the downward recess 55d. Therefore, as shown in FIG. 2 and FIG. 4, the head of the screw 77 does not protrude downward from the lower surface of the lower horizontal rod portion 55.

[0053] Here, as shown in Fig. 8, the curved surface 71a is formed on the outer surface of the side wall portion 71 facing both left and right directions. In a front view, the curved surface 71a is a convex arc shape toward the boundary portion between the outer surface of the side wall portion 71 and the upper surface of the lower horizontal rod portion 55, and extends outward in the left and right direction as it goes downward. Therefore, the width of the side wall portion 71 in the left and right direction gradually increases as it goes downward. The outer surface of the side wall portion 71 and the upper surface of the lower horizontal rod portion 55 are smoothly connected via the curved surface 71a.

[0054] The curved surface 71a has a larger radius of curvature than the chamfered portions (for example, the chamfered portion 100 formed at the boundary portion between the side wall portion 71 and the top wall portion 72) formed at various boundary portions constituting the back frame 41. In this embodiment, the curved surface 71a is formed over a range of at least 1 / 3 of the lower side of the vertical height of the front end portion of the side wall portion 71. In this embodiment, since the height of the side wall portion 71 decreases toward the rear, the vertical ratio of the curved surface 71a to the outer surface of the side wall portion 71 increases toward the rear. In addition, the entire vertical length of the outer surface of the side wall portion 71 may be formed by the curved surface 71a.

[0055] 1 and 3, the armrest attachment portion 57 protrudes on both the left and right sides from the lower horizontal rod portion 55. In a front view, the lower surface of the armrest attachment portion 57 is flush with the lower surface of the lower horizontal rod portion 55.

[0056] The surface material 42 is a part that directly supports the waist and back of a seated person. The surface material 42 is provided so as to cover the front of the upper frame portion 41A. The surface material 42 is configured to be elastically deformable, for example, by a membrane-like member such as mesh or cloth. The outer periphery of the surface material 42 is fixed to the outer surface of the upper frame portion 41A (upper horizontal rod portion 51, upper vertical rod portion 52, and middle horizontal rod portion 53) so as to wrap the upper frame portion 41A. Note that the backrest 4 may be configured so that the back frame 41 is covered with a cushion and a covering material instead of the surface material 42.

[0057] <Armrest 5> 1 and 2, the armrest 5 is attached to each armrest attachment portion 57 and supports the portion of the seated occupant's elbow to forearm from below. The armrest 5 includes an armrest support member 80 and an armrest main body 81.

[0058] The armrest support member 80 is a member that connects the armrest attachment portion 57 and the armrest main body 81, and functions as a strength member of the armrest 5. The armrest support member 80 is formed in an L-shape when viewed from the front. The lower end of the armrest support member 80 is attached to the armrest attachment portion 57 from the outside in the left-right direction.

[0059] The armrest main body 81 is supported so as to be vertically movable relative to the armrest support member 80. The armrest main body 81 includes an armrest support 82 and an elbow rest portion 83. The armrest support pillar 82 is inserted from above the armrest support member 80 into an insertion hole 80a that vertically penetrates the armrest support member 80. The armrest support pillar 82 is configured to be able to move up and down along the insertion hole 80a.

[0060] The armrest 83 is provided on the upper end of the armrest support 82. The armrest 83 is formed, for example, by covering a shell and padding material with a skin material. The upper surface of the armrest 83 forms an armrest surface that supports the elbow of the seated occupant. The armrest 83 covers the armrest support 82 from above, and is attached to the armrest support 82 in a state where it protrudes in the front-to-back and left-to-right directions relative to the armrest support 82. The armrest 5 may be attached to the seat 3 or the support base 12. The armrest 5 may also be configured not to move up and down.

[0061] In this manner, in the backrest 4 of this embodiment, the back frame (backrest main body) 41 has an upper surface that extends downward as it approaches the front, and is configured to include a lower horizontal rod portion (horizontal rod portion) 55 extending in the left-right direction, a support mounting portion (accommodating portion) 56 that is arranged at the left-right center of the lower horizontal rod portion 55, protruding upward from the lower horizontal rod portion 55, and accommodates part of the tilting member 22, and an upper frame portion (load-receiving portion) 41A that is located above the lower horizontal rod portion 55 and supports the back of a seated person. According to this configuration, since the upper surface of the lower horizontal rod portion 55 is formed as a sloping surface that slopes downward toward the front, it is possible to provide the support base attachment portion 56 above the lower horizontal rod portion 55 in a space (shielded space Q) within the height range of the front end and rear end of the lower horizontal rod portion 55. Therefore, the exposed area of ​​the support base 12 when the chair 1 is viewed from the rear can be reduced, and the appearance of the chair 1 can be improved. In addition, since the upper surface of the lower horizontal rod portion 55 is formed as a sloping surface, the lower horizontal rod portion 55 can be made to look thin (thin) when the chair 1 is viewed from the rear. Therefore, the appearance of the backrest 4 itself can be improved compared to a configuration in which the entire lower horizontal rod portion 55 is made thick in order to reduce the exposed area of ​​the support base 12.

[0062] In the backrest 4 of this embodiment, the lower surface of the lower horizontal rod portion 55 is configured to extend downward toward the front. According to this configuration, by forming the lower surface of the lower horizontal rod portion 55 as a sloping surface that slopes downward toward the front, it is easier to ensure the vertical dimension of the lower horizontal rod portion 55 compared to a case in which the lower surface of the lower horizontal rod portion 55 is formed as a flat surface along a horizontal surface, for example. Therefore, it is easy to ensure the rigidity of the lower horizontal rod portion 55 while making the lower horizontal rod portion 55 look slimmer when the chair 1 is viewed from the rear.

[0063] In the backrest 4 of this embodiment, the dimension of the lower horizontal rod portion 55 in the up-down direction is gradually increased toward the front. According to this configuration, when the chair 1 is viewed from the rear, the lower horizontal rod portion 55 appears slimmer, and the rigidity of the lower horizontal rod portion 55 is more easily ensured.

[0064] In the backrest 4 of this embodiment, the lower horizontal rod portion 55 is configured to have a forward-facing recess 55a that opens forward and extends in the left-right direction. According to this configuration, even if the dimension of the lower horizontal rod portion 55 in the up-down direction increases toward the front, the thickness of the lower horizontal rod portion 55 can be made uniform over the entire length in the front-rear direction. This makes it possible to suppress the occurrence of sink marks and the like, and to form the lower horizontal rod portion 55 with high precision.

[0065] In the backrest 4 of this embodiment, the lower horizontal rod portion 55 spans between the surfaces of the forward-facing recess 55a that face each other in the vertical direction, and is configured to have a plurality of vertical ribs (first ribs) 60 spaced apart in the left-right direction. This configuration can prevent the rigidity of the lower horizontal rod 55 from decreasing due to the formation of the forward recess 55a. In addition, by providing the vertical rib 60 in the forward recess 55a, the upper surface of the lower horizontal rod 55 can be formed into a smooth surface without any ribs. This can improve the appearance of the backrest 4.

[0066] In the backrest 4 of this embodiment, the lower horizontal rod portion 55 is formed in a downwardly convex arc shape when viewed from the front, and a downwardly facing recess 55d that opens downward is formed in the central portion in the left-right direction of the lower horizontal rod portion 55, which overlaps with the base mounting portion 56 when viewed in a plan view. According to this configuration, the portion of the lower horizontal rod portion 55 formed in an arc shape that overlaps with the base mounting portion 56 can be set to the portion of the lower horizontal rod portion 55 that protrudes most downwardly. In other words, while reducing the exposed area of ​​the base 12, it is not necessary to set the position of the entire lower horizontal rod portion 55 downward. Therefore, a high degree of freedom in design can be ensured. Moreover, by forming the downward recess 55d in the portion that protrudes most downward, the vertical size of the entire backrest 4 can be reduced. The mold for manufacturing the backrest 4 can also be made smaller, leading to a reduction in manufacturing costs. Moreover, by providing the downward recess 55d below the base mounting portion 56, the portion of the lower horizontal rod portion 55 where the base mounting portion 56 is provided can be prevented from becoming thicker than other portions. Therefore, the occurrence of sink marks and the like can be prevented, and the lower horizontal rod portion 55 can be formed with high precision.

[0067] In the backrest 4 of this embodiment, the rear end edge of the downward recess 55d is configured to be located forward of the rear end edge of the lower horizontal rod portion 55 in the front-rear direction. According to this configuration, the downward recess 55d is unlikely to be exposed when the backrest 4 is viewed from behind. Therefore, the appearance of the backrest 4 can be improved.

[0068] In the backrest 4 of this embodiment, the downward recess 55d has a downward surface 55d3 provided with front-rear ribs (second ribs) 64a that protrude downward from the downward surface 55d3 and extend in the front-rear direction. According to this configuration, the support base mounting portion 56 can be reinforced from below. This makes it possible to suppress a decrease in the rigidity of the support base mounting portion 56 due to the formation of the downward recess 55d, and to firmly fix the support base 12 and the backrest 4. Furthermore, since the left and right ribs 64b are provided on the downward surface 55d3 of the downward recess 55d, a decrease in rigidity of the lower horizontal rod portion 55 (rigidity in the bending direction starting from the downward recess 55d) due to the formation of the downward recess 55d can be suppressed.

[0069] In the backrest 4 of this embodiment, the lower end edges of the front and rear ribs 64a are configured to be located above the lower end opening 55d2 of the downward recess 55d. According to this configuration, when the chair 1 is viewed from the rear, the front-rear ribs 64a can be prevented from being exposed.

[0070] In the backrest 4 of this embodiment, the back frame 41 is configured to include a pair of lower vertical rods (side rods) 54 extending downward from both left and right ends of the upper frame portion 41A and connected to a lower horizontal rod portion 55. According to this configuration, the upper frame portion 41A and the lower horizontal rod portion 55 are connected via a pair of lower vertical rod portions 54, so that the seating load input to the upper frame portion 41A can be transmitted to the lower horizontal rod portion 55 from both the left and right sides. This allows the seating load to be mitigated by the entire lower horizontal rod portion 55, and reduces the load acting on the connection portion between the support base mounting portion 56 and the tilting member 22. Therefore, it is possible to provide a backrest 4 with excellent durability while improving the appearance of the backrest 4.

[0071] Since the chair 1 of this embodiment is provided with the above-mentioned backrest 4, it is possible to provide a chair 1 having excellent durability while improving the appearance.

[0072] (Other variations) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the attached claims. In the above embodiment, the back frame 41 is configured to include the upper frame portion 41A as a load receiving portion, but the present invention is not limited to this configuration. The load receiving portion may be, for example, a plate-like portion. In the above embodiment, the back frame 41 is configured to include the upper frame portion 41A and the lower frame portion 41B, but is not limited to this configuration. The back frame 41 may be formed into a single frame shape as a whole. In the above embodiment, the back frame 41 is described as being integrally formed as a whole, but the back frame 41 may be formed by combining a plurality of members. For example, a first frame member in which the upper horizontal rod portion 51, the upper vertical rod portion 52, and the upper portion of the middle horizontal rod portion 53 are integrally formed in advance may be fixed to a second frame member in which the lower portion of the middle horizontal rod portion 53, the lower vertical rod portion 54, and the lower horizontal rod portion 55 are integrally formed in advance. In this case, it is preferable that at least one of the upper vertical rod portion 52 and the lower vertical rod portion 54, or the upper portion of the middle horizontal rod portion 53 and the lower portion of the middle horizontal rod portion 53, is fastened to the first frame member and the second frame member by a screw.

[0073] In the above embodiment, the vertical dimension of the lower horizontal rod portion 55 gradually increases toward the front, but the present invention is not limited to this configuration. The vertical dimension of the lower horizontal rod portion 55 may be uniform over the entire length in the front-rear direction. In the above embodiment, the forward recess 55a is formed in the lower horizontal rod portion 55, but the present invention is not limited to this configuration. The lower horizontal rod portion 55 may be solid or may be cylindrical with a covered front surface. In the above-described embodiment, the vertical rib 60 is provided as the first rib, but the first rib may be an inclined rib extending in a direction inclined in the left-right direction with respect to the vertical direction when viewed from the front. In addition, a so-called cross rib may be formed by crossing an inclined rib inclined to one side in the left-right direction as it extends downward and an inclined rib inclined to the other side in the left-right direction as it extends downward, or the inclined rib and the vertical rib 60 may be appropriately connected. In the above embodiment, the configuration in which both the front-rear rib 64a and the left-right rib 64b are provided as the second rib has been described, but the present invention is not limited to this configuration. The second rib may be provided with either the front-rear rib 64a or the left-right rib 64b.

[0074] In the above embodiment, the chair 1 is described as having the armrests 5, but the armrests 5 are not an essential component. In the above embodiment, the base mounting part 56 as the housing part is formed in a box shape opening forward, but the present invention is not limited to this configuration. The base mounting part 56 may be configured to house the tilting member 22 and to be connected to the tilting member 22. In this case, the base mounting part 56 may be configured without the top wall part 72, for example.

[0075] In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0076] 1: Chair 2: Support structure 22: Tilting member 41: Back frame (backrest body) 41A: Upper frame part (load receiving part) 55: Lower horizontal rod part (horizontal rod part) 54:Lower vertical rod part (side rod part) 55a: forward recess 55c: Downward side 55d: Downward recess 55d2: Bottom opening 55d3:Downward face 56: Support base mounting part (accommodation part) 60: Vertical rib (first rib) 64a: Front and rear ribs (second rib) 64b: Left and right ribs (second rib) O: Axis line

Claims

1. The seat back includes a backrest body supported on a support structure via a tilting member that is tiltable around an axis along a left-right direction, The backrest body includes: A horizontal rod portion having an upper surface extending downward toward the front and extending in the left-right direction; a housing portion provided at a central portion of the horizontal rod portion in a left-right direction so as to protrude upward from the horizontal rod portion and housing a part of the tilting member; The backrest is provided with a load-receiving portion located above the horizontal rod portion and configured to support the back of a seated occupant.

2. The backrest according to claim 1 , wherein a lower surface of the horizontal rod portion extends downward as it moves forward.

3. 3. The backrest according to claim 1 or 2, wherein the dimension of said horizontal rod portion in the up-down direction gradually increases toward the front.

4. The backrest according to claim 3 , wherein the horizontal rod portion is formed with a forward-facing recess that opens forward and extends in the left-right direction.

5. The backrest according to claim 4, wherein the horizontal rod portion bridges between the inner surfaces of the forward-facing recess that face each other in the vertical direction and has a plurality of first ribs spaced apart in the left-right direction.

6. The horizontal rod portion is formed in a downwardly convex arc shape when viewed from the front, The backrest according to claim 1 or 2, wherein a downward recess that opens downward is formed in a portion of the horizontal rod portion that overlaps with the storage portion in a plan view.

7. The backrest according to claim 6, wherein a rear end edge of the downward recess is located forward of a rear end edge of the horizontal rod portion in the front-rear direction.

8. The backrest according to claim 6, wherein a second rib is formed on the inner surface of the downward recess, the downward surface facing downward, the second rib protruding downward from the downward surface and extending in a direction intersecting the vertical direction.

9. The backrest according to claim 8, wherein a lower end edge of the second rib is positioned above a lower end opening of the downward recess.

10. 3. The backrest according to claim 1 or 2, wherein the backrest body includes a pair of side rod portions extending downward from both left and right ends of the load receiving portion and connected to the horizontal rod portion.

11. A chair comprising the backrest according to claim 1 or 2.

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