Backrest and chair

Abstract

To provide a backrest and a chair that can improve a degree of freedom for designing a backrest and secure support strength of an upholstery material and an armrest while suppressing deterioration in design quality.SOLUTION: A backrest 4 includes: a frame-like back frame 41 having a pair side frame members 43 provided on both sides in a right-left direction, which is formed with an opening part 41p opened in a front-back direction; an upholstery material 42 that covers the opening part 41p of the back frame 41 at least from the front and forms a load support surface for receiving an upper half of the body of a seated person; and an armrest 5 connected to the back frame 41. Each of the pair of side frame members 43 is formed with a side part engagement groove 93 with which an end part of the upholstery material 42 engages, and a connection concave part 57d formed at a position separated downward with respect to the side part engagement groove 93, with which the base end part of the armrest 5 engages.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] For example, Patent Document 1 discloses a configuration in which a frame member to which the peripheral edge of an upholstery material is attached and the base end of an armrest are each connected to a connecting member that is connected to the base of the chair.

[0003] Patent document 2 also discloses a configuration in which the peripheral edge of the upholstery material of the backrest of a chair, which forms a load-bearing surface that supports the upper body of a seated person, is attached to a frame member, and the base ends of the armrests are fixed to the frame member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-93092 A [Patent Document 2] Patent No. 6414964 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration disclosed in Patent Document 1, the frame member and the base end of the armrest are connected to the chair base via connecting members that are provided separately from the frame member and the armrest, which increases the number of parts that make up the chair, leading to higher costs.

[0006] In contrast, in the configuration disclosed in Patent Document 2, the peripheral portion of the upholstery material and the base end of the armrest are attached to the frame member, so the number of parts constituting the chair can be reduced. However, since the peripheral portion of the upholstery material and the base end of the armrest are fixed to a recess (groove) formed in the frame member, it is necessary to enlarge the recess so that the peripheral portion of the upholstery material and the base end of the armrest can be held. Increasing the size of the recess in this way leads to a decrease in the strength of the frame member, and it may become difficult to ensure the support strength of the peripheral portion of the upholstery material and the base end of the armrest. In contrast, if the cross section of the frame member is made thicker in order to ensure the strength of the frame member, this leads to a decrease in the design of the chair and an increase in costs. For this reason, in the configuration disclosed in Patent Document 2, it may be difficult to design in such a way that the support strength of the upholstery material and the armrest is ensured while suppressing a decrease in design. The present invention aims to provide a backrest and chair that can improve the design freedom of the backrest and ensure the supporting strength of the upholstery and armrests while suppressing a decrease in design. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following aspects. (1) A backrest in one embodiment of the present invention is a backrest for a chair, comprising a frame-shaped back frame having a pair of side frame members on both the left and right sides and with an opening that opens in the front-to-back direction, an upholstery material that covers the opening of the back frame at least from the front and forms a load-bearing surface that supports the upper body of a seated occupant, and an armrest connected to the back frame, wherein each of the pair of side frame members is formed with a first engagement portion with which an end of the upholstery material engages, and a second engagement portion that is formed at a position spaced downward from the first engagement portion and with which a base end of the armrest engages. According to this aspect, the second engagement portion, which engages with the base end of the armrest, is formed in a position spaced downward from the first engagement portion, which engages with the end of the upholstery material, on each of a pair of side frame members constituting the back frame. This allows the design of the first engagement portion, which engages with the end of the upholstery material, and the design of the second engagement portion, which engages with the base end of the armrest, to be carried out independently. This makes it easier to carry out a design that ensures sufficient support strength for the upholstery material at the first engagement portion and support strength for the base end of the armrest at the second engagement portion. Furthermore, since the first engagement portion and the second engagement portion are provided on a single side frame member, the number of parts is smaller than in the case where the first engagement portion and the second engagement portion are formed as separate parts, and increases in part costs and assembly labor are suppressed. As a result, it is possible to provide a backrest that improves the design freedom and ensures the supporting strength of the upholstery and armrests while minimizing any loss of aesthetic appeal.

[0008] (2) In the backrest relating to the above aspect (1), the pair of side frame members have an upper side frame portion extending along the lateral edges of the opening on both the left and right sides, and a lower side frame portion extending downward from the lower end of the upper side frame portion, and it is preferable that the first engagement portion is formed in the upper side frame portion and the second engagement portion is formed in the lower side frame portion. According to this aspect, the first engagement portion is formed on the upper frame portion, and the second engagement portion is formed on the lower frame portion. As a result, when the weight of the upper body of the seated person acts through the upholstery, the upper frame portion mainly elastically deforms, providing a comfortable sitting experience, while the lower frame portion extending downward from the lower end of the upper frame portion can be designed to increase the rigidity of the portion that engages with the base end of the armrest.

[0009] (3) In the backrest according to the above aspect (2), it is preferable that the back frame has a lower connecting portion extending in the left-right direction and connecting the lower ends of the lower side frame portions to each other. According to this aspect, by connecting the lower ends of the lower side frame portions with the lower connecting portion, the rigidity of the lower ends of the pair of side frame members can be increased, and the base end of the armrest can be supported more firmly.

[0010] (4) In a backrest relating to any one of the above aspects (1) to (3), it is preferable that each of the first engagement portion and the second engagement portion has a recess formed recessed into the inside of the back frame in the left-right direction and opening toward the outside of the back frame in the left-right direction. According to this aspect, the first engagement portion and the second engagement portion are each recessed on the inside of the back frame in the left-right direction and open toward the outside of the back frame in the left-right direction. This allows the demolding direction to be aligned when molding the back frame by injecting the material that forms the back frame into a mold, improving moldability.

[0011] (5) In a backrest relating to any one of the above aspects (1) to (4), the first engagement portion is formed recessed on the inside in the left-right direction of the back frame, and the side frame member has a first wall portion extending in the left-right direction and forming a front groove side surface of the first engagement portion, and a second wall portion spaced rearward in the fore-and-aft direction from the first wall portion, extending in the left-right direction and forming a rear groove side surface of the first engagement portion, and it is preferable that the second wall portion protrudes outward in the left-right direction more than the first wall portion. According to this aspect, the second wall portion forming the rear groove side of the first engagement portion protrudes outward in the left-right direction more than the first wall portion forming the front groove side of the first engagement portion. With this configuration, when another object contacts the seat from behind, the object contacts the second wall portion, and the upholstery material engaged with the first engagement portion is prevented from being damaged by the object contacting the upholstery material. In addition, the end of the upholstery material engaged with the first engagement portion contacts the rear groove side over a wider range in the left-right direction than the front groove side. This increases the contact area between the peripheral edge of the upholstery material and the inner surface of the first engagement portion, allowing the upholstery material to be more firmly engaged with the back frame.

[0012] (6) A chair according to one aspect of the present invention includes a backrest according to any one of the above aspects (1) to (5). According to this aspect, it is possible to provide a chair equipped with a backrest that improves the design freedom of the backrest, suppresses a decrease in design quality, and ensures the supporting strength of the upholstery and armrests. Effect of the Invention

[0013] According to one aspect of the present invention, it is possible to improve the design freedom of the backrest and ensure the support strength of the upholstery and armrests while minimizing any loss of design. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of a chair according to an embodiment of the present invention, 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 a perspective view of a back frame according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. [Diagram 5] 13 is a front view of the lower part of the back frame according to the embodiment. FIG. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. 2. [Figure 7] FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 5. [Figure 8] FIG. 2 is a perspective view showing a base end portion of an armrest support member according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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.

[0016] [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.

[0017] <Support structure 2> The support structure 2 includes a leg body 11 and a support base 12 . 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.

[0018] 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.

[0019] 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. The support base 12 supports the backrest 4 so that it can tilt.

[0020] <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 support base 12 in a state in which it covers the entire support base 12 from above. The seat main body 31 is supported from below by the seat shell 30. The seat main body 31 includes a cushioning material that is placed on the upper surface of the seat shell 30, and a skin material that covers the cushioning material from above.

[0021] <Backrest 4> The backrest 4 supports the seated occupant's lower back and back from behind. The backrest 4 is connected to the support base 12 so as to be tiltable about an axis along the left-right direction. However, the backrest 4 may also be connected to the support base 12 so as not to be tiltable.

[0022] FIG. 3 is a perspective view of the back frame 41 according to the present embodiment. As shown in FIGS. 1 to 3, the backrest 4 includes a back frame 41 and an upholstery material 42 . The back frame 41 is a strength member that constitutes the outer shape of the backrest 4. The back frame 41 is a molded product made of synthetic resin that is integrally formed by means of injection molding or the like. The back frame 41 is formed in a circular arc shape that convex backward in a plan view, and in an S-shape in a side view. The back frame 41 is formed in an 8 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 a pair of side frame members 43, a first connecting portion 51, a second connecting portion 52, and a third connecting portion (lower connecting portion) 53.

[0023] Each of the pair of side frame members 43 has an upper side frame portion 44 and a lower side frame portion 45 . The upper side frame portion 44 has a first side frame portion 46 and a second side frame portion 47. The first side frame portion 46 constitutes the upper portion of the side frame member 43 and extends in the up-down direction. The first side frame portion 46 extends diagonally forward from the upper end toward the lower end in a side view. The second side frame portion 47 extends downward from the lower end of the first side frame portion 46. The second side frame portion 47 extends diagonally backward from the upper end toward the lower end in a side view. 2 and 3, the first side frame portion 46 extends downward and outward in the left-right direction. The second side frame portion 47 extends downward and inward in the left-right direction from a lower end portion of the first side frame portion 46.

[0024] The lower frame portion 45 extends downward from the lower end of the upper frame portion 44. In side view, the lower frame portion 45 extends downward and forward from the lower end of the second frame portion 47. In other words, the lower frame portion 45 extends obliquely forward from the upper end to the lower end. As a result, in side view, the connection portion between the lower end of the second frame portion 47 and the upper end of the lower frame portion 45 is bent so as to protrude rearward. The lower side frame portions 45 extend downward and outward in the left-right direction from the lower ends of the second side frame portions 47. As a result, the left-right distance between the pair of lower side frame portions 45 gradually increases downward in a front view. 1 and 2, the vertical middle portion of the lower frame portion 45 overlaps with the outer left-right end portion of the seat 3 in a front view. The lower end portion of the lower frame portion 45 is located below the seat 3. The front end portion of the lower frame portion 45 is located forward of the bent portion of the upper frame portion 44.

[0025] As shown in Figs. 1 to 3, the first connecting portion 51 constitutes the upper end portion of the back frame 41. The first connecting portion 51 connects the upper ends of the first side frame portions 46. The first connecting portion 51 extends in the left-right direction in an arc shape that convex rearward in a plan view.

[0026] FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. The second connecting portion 52 connects the boundary portions between the lower end of the second side frame portion 47 and the upper end of the lower side frame portion 45. The second connecting portion 52 extends in the left-right direction in a circular arc shape that protrudes rearward in a plan view. As shown in FIG. 4, the thickness of the second connecting portion 52 in the vertical direction gradually increases from the rear to the front. The upper surface 52t of the second connecting portion 52 is formed as an inclined surface that slopes upward toward the front. On the other hand, the lower surface 52d of the second connecting portion 52 is formed so that the vertical distance between the lower surface 52d and the upper surface 52t gradually increases toward the front.

[0027] FIG. 5 is a view of the lower part of the back frame 41 as seen from the front. As shown in Figs. 4 and 5, the second connecting portion 52 has a forward-facing recess 52a formed on the front end surface of the second connecting portion 52. Specifically, the front end opening of the forward-facing recess 52a opens obliquely downward and forward. In a side view, the forward-facing recess 52a is formed in a triangular shape whose vertical dimension gradually decreases toward the rear. In this embodiment, the forward-facing recess 52a is formed over the entire left-right direction of the second connecting portion 52. The forward-facing recess 52a is formed in the second connecting portion 52, thereby improving moldability and reducing weight.

[0028] As shown in FIG. 5, a plurality of vertical ribs 58 are formed on the inside of the forward recess 52a. The vertical ribs 58 are provided at intervals in the left-right direction in each forward recess 52a. Each vertical rib 58 connects the inner surfaces of the forward recess 52a that face each other in the up-down direction (the upward surface 52b facing upward and the downward surface 52c facing downward). The vertical ribs 58 extend over the entire length of the forward recess 52a in the front-rear direction. The plurality of vertical ribs 58 reinforce the second connecting portion 52 in which the forward recess 52a is formed.

[0029] 1 to 3, an upper frame portion 41A is configured by the first connecting portion 51, the upper side frame portion 44, and the second connecting portion 52. The upper frame portion 41A has an opening 41p that opens in the front-rear direction.

[0030] As shown in Figs. 2, 3, and 5, the third connecting portion 53 extends in the left-right direction and connects the lower ends of the lower side frame portions 45 to each other. The third connecting portion 53 is formed in a downwardly convex arc shape in a front view. The third connecting portion 53 is located forward of the second connecting portion 52 in a side view. As shown in Figs. 3 and 5, the thickness of the third connecting portion 53 in the vertical direction gradually increases from the rear to the front. The upper surface 53t of the third connecting portion 53 is formed as an inclined surface that slopes downward toward the front. On the other hand, the lower surface 53d of the third connecting portion 53 is formed so as to slope downward toward the front, and the vertical distance between the lower surface 53d and the upper surface 53t gradually increases toward the front.

[0031] The third connecting portion 53 has a forward recess 53a formed on the front end surface of the third connecting portion 53. The forward recess 53a is formed in the third connecting portion 53 to improve moldability and reduce weight. Specifically, the front end opening of the forward recess 53a opens diagonally downward toward the front. The forward recess 53a is formed in a triangular shape whose vertical dimension gradually decreases toward the rear in a side view. In this embodiment, the forward recess 53a is formed on both sides of the third connecting portion 53 except for the central portion in the left-right direction.

[0032] A plurality of vertical ribs 59 are formed on the inner side of the forward recess 53a. The vertical ribs 59 are provided at intervals in the left-right direction in each forward recess 53a. Each vertical rib 59 connects the inner surfaces of the forward recess 53a that face each other in the up-down direction (the upward surface 53b facing upward and the downward surface 53c facing downward). The vertical ribs 59 extend over the entire length of the forward recess 53a in the front-rear direction. The third connecting portion 53 in which the forward recess 53a is formed is reinforced by the plurality of vertical ribs 59.

[0033] A base connecting portion 56 is provided in the left-right center of the third connecting portion 53. The back frame 41 is connected to the base 12 via the base connecting portion 56. The base connecting portion 56 is provided in the left-right center of the third connecting portion 53. The base connecting portion 56 is formed integrally with the third connecting portion 53. The base connecting portion 56 is connected to the base 12. The base connecting portion 56 protrudes upward from the third connecting portion 53 and is formed in a box shape that opens forward. The inside of the base connecting portion 56 forms an insertion groove 56a into which a part of the base 12 is inserted.

[0034] As shown in Figures 1 and 3, the upper frame part 41A of the back frame 41 has an upholstery engagement groove 90 with which the peripheral edge (end) of the upholstery 42 engages. The upholstery engagement groove 90 is formed continuously around the entire circumference of the upper frame part 41A. The upholstery engagement groove 90 has an upper engagement groove 91, a lower engagement groove 92, and a pair of side engagement grooves (first engagement parts, recesses) 93. The upper engagement groove 91 is formed on the upper surface of the first connecting part 51.

[0035] The upper engagement groove 91 is formed across the entire left-right direction of the first connecting portion 51. The upper engagement groove 91 is open upward on the top surface of the first connecting portion 51.

[0036] As shown in FIG. 4, the lower engagement groove 92 is formed in the tension material holding member 70 provided in the second connecting portion 52. The tension material holding member 70 is a separate part from the back frame 41, and is fitted into the forward recess 52a of the second connecting portion 52. The tension material holding member 70 has an upper contact surface 70a that contacts the downward surface 52c of the forward recess 52a, and a lower contact surface 70b that contacts the upward surface 52b. The tension material holding member 70 is formed so that the vertical distance between the upper contact surface 70a and the lower contact surface 70b gradually decreases toward the rear in a side view. The tension material holding member 70 extends in the left-right direction, and is fitted from the front into the entire left-right direction of the forward recess 52a, and is fixed to the second connecting portion 52 by a bolt or the like (not shown).

[0037] The lower end of the front edge of the upholstery holding member 70 protrudes forward further than the downward surface 52c of the second connecting portion 52. The lower engagement groove 92 is formed at the lower end of the front edge of the upholstery holding member 70 (the portion that protrudes forward further than the forward-facing recess 52a). The lower engagement groove 92 is formed across the entire left-right direction of the upholstery holding member 70. The lower engagement groove 92 opens downward at the lower end of the front edge of the upholstery holding member 70. The lower engagement groove 92 opens obliquely downward and towards the rear in a side view.

[0038] FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. The pair of side engagement grooves 93 are formed in the upper side frame portions 44 of the pair of side frame members 43. The upper side frame portions 44 are formed in a triangular shape that protrudes rearward in a plan view. The thickness of the upper side frame portions 44 in the left-right direction gradually increases from the rear to the front. Each side engagement groove 93 is formed on a side surface 44s of the upper side frame portion 44 facing outward in the left-right direction. Each side engagement groove 93 is formed by being recessed inward in the left-right direction from the side surface 44s. The side engagement groove 93 opens outward in the left-right direction on the side surface 44s of the upper side frame portion 44. Each side engagement groove 93 is formed over the entire upper side frame portion 44 in the up-down direction. Of the pair of side engagement grooves 93, one side engagement groove 93 connects one end of the upper engagement groove 91 and the lower engagement groove 92 in the left-right direction. Of the pair of side engagement grooves 93, the other side engagement groove 93 connects the other end of the upper engagement groove 91 and the lower engagement groove 92 in the left-right direction.

[0039] The upper side frame portion 44 has a first wall portion 44f forming a front groove side surface facing rearward in the side engagement groove 93, and a second wall portion 44b forming a rear groove side surface facing forward in the side engagement groove 93. The second wall portion 44b is provided rearward and spaced apart from the first wall portion 44f. The outer tip portion of the second wall portion 44b in the left-right direction protrudes outward in the left-right direction further than the first wall portion 44f. As a result, the rear groove side surface has a greater left-right length than the front groove side surface. Furthermore, a hollowed-out recess 44r recessed toward the rear is formed in a portion of the upper side frame portion 44 that forms the periphery of the opening 41p on the inner side in the left-right direction. The hollowed-out recess 44r extends in the extension direction of the upper side frame portion 44 (the up-down direction).

[0040] FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 1 to 3 and 5, an armrest attachment portion 57 to which the armrest 5 is joined is provided at the lower end portion of the lower frame portion 45. The armrest attachment portion 57 is provided at the boundary between the lower end portion of the lower frame portion 45 and the outer end portion in the left-right direction of the third connecting portion 53. As a result, the armrest attachment portion 57 is firmly attached to the lower end portion of the lower frame portion 45 of the back frame 41.

[0041] As shown in FIG. 7, the armrest attachment portion 57 has an outward surface 57f facing outward in the left-right direction. The armrest attachment portion 57 has a connection recess (second engagement portion, recess) 57d on the inner periphery of the outward surface 57f, which is recessed inward in the left-right direction relative to the outward surface 57f. The connection recess 57d is formed at a position spaced downward from the side engagement groove 93. The connection recess 57d is formed at a position not overlapping with the side engagement groove 93 when viewed from the front-rear direction. The connection recess 57d opens toward the outside in the left-right direction of the back frame 41. The connection recess 57d is formed in a polygonal shape when viewed from the outside in the left-right direction.

[0042] A protrusion 57t is formed in the center of the connection recess 57d, protruding outward in the left-right direction from the bottom surface of the connection recess 57d. A bolt accommodating portion 57k is formed in the protrusion 57t, recessed outward in the left-right direction from the side frame surface 45f facing inward in the left-right direction in the lower side frame 45. A main body insertion hole 57h is formed in the armrest attachment portion 57, extending so as to connect the bottom surface of the bolt accommodating portion 57k (the surface facing inward in the left-right direction among the inner surfaces of the protrusion 57t) and the tip surface of the protrusion 57t (the surface facing outward in the left-right direction among the outer surfaces of the protrusion 57t). That is, the main body insertion hole 57h is open in the bolt accommodating portion 57k and in the connection recess 57d.

[0043] <Upholstery material 42> 1 and 2, the upholstery material 42 forms a load-bearing surface that supports the upper body of the seated person, specifically, the waist to back of the seated person. The upholstery material 42 is provided so as to cover the opening 41p of the upper frame portion 41A from the front. The upholstery material 42 is made of a membrane-like material such as mesh or cloth and is configured to be elastically deformable.

[0044] The outer peripheral portion of the upholstery material 42 is fixed to the upper frame portion 41A (first connecting portion 51, upper side frame portion 44, and second connecting portion 52) so as to wrap around the upper frame portion 41A. The ends of the outer peripheral portion of the upholstery material 42 are engaged with the upholstery material engagement grooves 90 (upper engagement groove 91, lower engagement groove 92, and a pair of side engagement grooves 93). Of the outer circumferential portion of the upholstery material 42, the upper end portion of the upholstery material 42 passes through the front surface of the first connecting portion 51, wraps around the first connecting portion 51 from above, and is inserted into the upper engagement groove 91. Of the outer circumferential portion of the upholstery material 42, the lower end portion of the upholstery material 42 passes through the front surface of the upholstery material holding member 70, wraps around the upholstery material holding member 70 from below, and is inserted into the lower engagement groove 92. Of the outer circumferential portion of the upholstery material 42, the ends on both left and right sides of the upholstery material 42 are engaged with the side engagement grooves 93, as shown in Fig. 6. The ends on both left and right sides of the upholstery material 42 pass over the front surface of the first wall portion 44f, wrap around the first wall portion 44f from the outside in the left and right direction, and are inserted into the side engagement grooves 93. Here, a core material (not shown) may be attached to the end of the outer circumferential portion of the upholstery material 42, and the end of the upholstery material 42 may be engaged with the upholstery material engagement groove 90 by inserting the end of the upholstery material 42 together with the core material into the upholstery material engagement groove 90.

[0045] <Armrest 5> 1 and 2, the armrest 5 is connected to the back frame 41. The armrest 5 is attached to each armrest attachment part 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.

[0046] The armrest support member 80 is a member that connects the armrest attachment part 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 armrest support part 80 is attached to the armrest attachment part 57 from the outside in the left-right direction via a part of the lower end of the armrest support part 80 that extends inward in the left-right direction (hereinafter referred to as the base end part 86).

[0047] FIG. 8 is a perspective view showing the proximal end 86 of the armrest support member 80. As shown in FIG. As shown in FIG. 7 and FIG. 8, the base end 86 is formed with a coupling surface 86f facing inward in the left-right direction. The coupling surface 86f contacts the outward surface 57f of the armrest attachment portion 57 facing outward in the left-right direction. The base end 86 has a connection protrusion 86d protruding outward in the left-right direction on the inner periphery of the coupling surface 86f. The connection protrusion 86d is formed in a polygonal shape corresponding to the connection recess 57d when viewed from the inside in the left-right direction. The connection protrusion 86d is inserted into the connection recess 57d. When the connection protrusion 86d is inserted into the connection recess 57d, the coupling surface 86f abuts against the outward surface 57f. Since the connection recess 57d and the connection protrusion 86d are polygonal when viewed from the left-right direction, the armrest support member 80 is restrained from swinging in the front-rear direction relative to the armrest attachment portion 57 by inserting the connection protrusion 86d into the connection recess 57d.

[0048] The connecting protrusion 86d has a recess 86g recessed inward in the left-right direction from a tip surface of the connecting protrusion 86d facing inward in the left-right direction. The protrusion 57t is inserted into the recess 86g. As shown in FIG. 7, the base end 86 is formed with an insertion hole opening 86k that opens outward in the left-right direction. The insertion hole opening 86k is formed by being recessed inward in the left-right direction from a surface of the base end 86 facing outward in the left-right direction. The insertion hole opening 86k accommodates a nut. As shown in FIG. 7 and FIG. 8, the base end 86 further has a fastening member insertion hole 86h. The fastening member insertion hole 86h extends in the left-right direction and is formed to communicate between the recess 86g and the insertion hole opening 86k. The fastening member insertion hole 86h is formed to communicate with the main body insertion hole 57h when the connection protrusion 86d is inserted into the connection recess 57d and the protrusion 57t is inserted into the recess 86g.

[0049] The armrest 5 is connected to the armrest attachment part 57 by a bolt and nut (not shown). With the connection protrusion 86d inserted into the connection recess 57d, the bolt is inserted into the main body insertion hole 57h and the fastening member insertion hole 86h from the inside in the left-right direction, and the head of the bolt is accommodated in the bolt accommodation part 57k. The nut is accommodated in the insertion hole opening 86k from the outside in the left-right direction and fastened to the bolt.

[0050] 1 and 2, 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 pillar 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.

[0051] 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 elbows 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.

[0052] <Lumbar Support 100> A lumbar support 100 for supporting the lower back of a seated person is provided in the center of the second connecting portion 52 in the left-right direction. The lumbar support 100 protrudes upward from the second connecting portion 52 so as to be visible inside the upper frame portion 41A. Note that the lumbar support 100 is not an essential component of the chair 1 of this embodiment, and the lumbar support 100 may be omitted. The chair 1 includes a lumbar support main body 101 and an attachment portion 130.

[0053] The lumbar support body 101 abuts against the back of the seated occupant through the upholstery 42, and supports the weight of the seated occupant from behind. The attachment portion 130 is a member that attaches the lumbar support body 101 to the back frame 41. The attachment portion 130 is attached to the center of the second connecting portion 52 in the left-right direction.

[0054] In this manner, in this embodiment, the connection recess 57d, into which the base end 86 of the armrest 5 engages, is formed at a position spaced downward in each of a pair of side frame members 43 constituting the back frame 41, relative to the side engagement groove 93 into which the end of the upholstery material 42 engages. According to this configuration, the side engagement groove 93 with which the end of the upholstery material 42 engages can be designed independently from the connection recess 57d with which the base end of the armrest 5 engages. This makes it easier to design the side engagement groove 93 to provide sufficient support strength for the upholstery material 42, and the connection recess 57d to provide sufficient support strength for the base end of the armrest 5. Furthermore, since the side engagement groove 93 and the connection recess 57d are provided in a single side frame member 43, the number of parts required is reduced compared to the case in which the side engagement groove 93 and the connection recess 57d are formed in separate parts, thereby suppressing increases in parts costs and assembly labor. As a result, it is possible to provide a backrest that improves the design freedom of the backrest 4 and ensures the supporting strength of the upholstery 42 and the armrests 5 while minimizing deterioration of the design.

[0055] In this embodiment, the side engagement grooves 93 are formed in the upper frame portion 44, and the connection recesses 57d are formed in the lower frame portion 45. According to this configuration, a side engagement groove 93 with which the end of the upholstery 42 engages is formed in the upper frame portion 44, and a connection recess 57d with which the base end 86 of the armrest 5 engages is formed in the lower frame portion 45. As a result, when the weight of the upper body of the seated occupant acts via the upholstery 42 at the upper part of the back frame 41, the upper frame portion 44 mainly elastically deforms, realizing a comfortable sitting experience, while the lower frame portion 45 extending downward from the lower end of the upper frame portion 44 can be designed to increase the rigidity of the armrest attachment portion 57 with which the base end 86 of the armrest 5 engages.

[0056] In this embodiment, the lower ends of the lower side frame portions 45 are connected to each other by the third connecting portion 53. According to this configuration, the rigidity of the lower ends of the pair of side frame members 43 can be increased, and the base end 86 of the armrest 5 can be supported more firmly.

[0057] In this embodiment, each of the side engagement grooves 93 and the connection recesses 57d is recessed inside the back frame 41 in the left-right direction and opens toward the outside of the back frame 41 in the left-right direction. According to this configuration, since the side engagement grooves 93 and the connection recesses 57d are open in the same direction, it is possible to suppress the complexity of the mold when forming the portions of the back frame 41 other than the upholstery holding member 70 by injection molding. This improves the moldability of the back frame 41.

[0058] In this embodiment, the second wall portion 44b forming the rear groove side surface of the side engagement groove 93 protrudes outward in the left-right direction more than the first wall portion 44f forming the front groove side surface of the side engagement groove 93. According to this configuration, when another object comes into contact with the back frame 41 from the rear, the object comes into contact with the second wall portion 44b, and therefore it is possible to prevent the object from coming into contact with the peripheral portion of the upholstery material 42 engaged with the side engagement groove 93. This makes it possible to prevent damage to the upholstery material 42. Also, the end of the upholstery material 42 engaged with the side engagement groove 93 comes into contact with the rear groove side surface over a wider range in the left-right direction than the front groove side surface. This increases the contact area between the peripheral portion of the upholstery material 42 and the inner surface of the side engagement groove 93, and allows the upholstery material 42 to be engaged with the back frame 41 more firmly.

[0059] In this embodiment, a pair of side frame members 43 are configured to have a second connecting portion 52 that connects the boundary portions between the lower end portion of the upper side frame portion 44, in which the side engagement groove 93 is formed, and the upper end portion of the lower side frame portion 45, in which the connection recess 57d is formed. According to this configuration, among the seating load, the load inputted to the upper side frame portion 44 via the upholstery material 42 is also transmitted to the second connecting portion 52. On the other hand, the load inputted to the lower side frame portion 45 via the armrest 5 is also transmitted to the second connecting portion 52. That is, the load transmitted via the upholstery material 42 and the load transmitted via the armrest 5 can be prevented from being directly transmitted between the upper side frame portion 44 and the lower side frame portion 45. Therefore, deformation of one side frame member 43 due to a load acting on the other side frame member 43 can be prevented. As a result, the durability of the backrest 4 can be improved, and the seating comfort can be improved.

[0060] In this embodiment, the chair 1 is configured to include the above-mentioned backrest 4. According to this configuration, it is possible to provide a chair 1 equipped with a backrest 4 that achieves a good balance between the flexibility of the backrest 4 and the rigidity of the armrest attachment portion 57 while suppressing increases in costs.

[0061] (Other embodiments) 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. For example, in the above-described embodiment, the side engagement groove 93 as the first engagement portion is formed in the upper frame portion 44, and the connection recess 57d as the second engagement portion is formed in the lower frame portion 45, but this is not limited to the above. The first engagement portion and the second engagement portion may be formed at appropriate positions depending on the shape of the side frame member 43 of the back frame 41, etc., so long as they are provided spaced apart downward.

[0062] In the above-described embodiment, the side engagement groove 93 as the first engagement portion and the connection recess 57d as the second engagement portion are opened outward in the left-right direction, but the opening direction of the side engagement groove 93 and the connection recess 57d may be inclined forward or backward with respect to the left-right direction. Also, the side engagement groove 93 and the connection recess 57d may be opened forward or backward. Furthermore, the opening direction of the side engagement groove 93 may be different from the opening direction of the connection recess 57d.

[0063] In the above-described embodiment, the connection recess 57d as the second engagement portion is recessed inward in the left-right direction, but is not limited thereto. The second engagement portion may be a protrusion that protrudes outward in the left-right direction from the outer circumferential surface of the lower frame portion 45.

[0064] In the above embodiment, the cross-sectional shape of the side frame member 43 has been described, but the cross-sectional shape of the side frame member 43 is not limited to the example shown here. The cross-sectional shape of the side frame member 43 can be changed as appropriate as long as the side engagement groove 93 and the connection recess 57d are formed therein. For example, in the above-described embodiment, the second wall portion 44b is configured to protrude outward in the left-right direction from the first wall portion 44f, but this is not limited thereto. The tip of the first wall portion 44f and the tip of the second wall portion 44b may be at the same position in the left-right direction, or the first wall portion 44f may protrude outward in the left-right direction from the second wall portion 44b. In addition, in order to prevent objects or the like from contacting the upholstery material 42 engaged with the side engagement groove 93 from the rear, a cover or the like may be provided behind the second wall portion 44b.

[0065] In the above-described embodiment, the upholstery material 42 is configured to cover the opening 41p of the back frame 41 from the front, but this is not limited to the above. In addition to the upholstery material 42, a further upholstery material may be provided to cover the opening 41p of the back frame 41 from the rear.

[0066] In the above embodiment, the base end portion 86 of the armrest 5 is configured to engage with the connection recess 57d, but the specific shape of the connection recess 57d can be changed as appropriate.

[0067] In the above embodiment, the configuration of the back frame 41 has been described, but the configuration of the back frame 41 can be appropriately changed. For example, the third connecting portion 53 that connects the lower ends of the lower frame portions 45 to each other may be omitted, and the lower ends of the pair of lower frame portions 45 may be connected to the support base 12. 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]

[0068] 1: Chair 3: Za 4: Backrest 5: Armrest 41: Back frame 41p: opening 42: Upholstery 42f: Load support surface 43: Side frame member 44: Upper side frame 44f: First wall 44b:Second wall part 45: Lower side frame 53: Third connection part (lower connection part) 57: Armrest attachment part 57d: Connection recess (second joining recess, recess) 86: Proximal end 93: Side engagement groove (first joining recess, recess)

Claims

1. The backrest of a chair. A frame-shaped back frame having a pair of side frame members provided on both left and right sides and an opening portion opening in the front and rear direction; A tension material that covers the opening of the back frame at least from the front and forms a load support surface that supports the upper body of a seated person; An armrest connected to the back frame, Each of the pair of side frame members has A first engagement portion with which an end portion of the upholstery material is engaged; A second engagement portion is formed at a position spaced downward from the first engagement portion, and the base end portion of the armrest is engaged with the second engagement portion. Backrest.

2. The pair of side frame members are An upper side frame portion extending along the periphery on both left and right sides of the opening; A lower side frame portion extending downward from a lower end of the upper side frame portion, The first engagement portion is formed on the upper side frame portion, The second engagement portion is formed in the lower side frame portion.

2. The backrest according to claim 1.

3. The back frame includes a lower connecting portion that extends in the left-right direction and connects the lower ends of the lower side frames to each other.

3. The backrest according to claim 2.

4. Each of the first engagement portion and the second engagement portion has a recess formed on the inner side of the back frame in the left-right direction and opening toward the outer side of the back frame in the left-right direction.

3. The backrest according to claim 1 or 2.

5. The first engagement portion is formed by being recessed on the inner side in the left-right direction of the back frame, The side frame members are A first wall portion extending in the left-right direction and forming a front groove side surface of the first engagement portion; a second wall portion that is provided rearward in the front-rear direction from the first wall portion and extends in the left-right direction, and forms a rear groove side surface of the first engagement portion, The second wall portion protrudes outward in the left-right direction further than the first wall portion.

3. The backrest according to claim 1 or 2.

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

Images