chair

Abstract

To provide a chair having a configuration in which a lumbar support hardly comes off from a backrest even when receiving external force from a rear side.SOLUTION: Left and right side frame materials 2 of a backrest E are formed with a rail part n1 projecting forward, and a backward surface n21 as a backward part positioned in a rear part from the tip end of the rail part n1 and facing a rear side. Both left and right end parts of a lumbar support R are provided with a rail engaging part r11 formed so as to cover at least the front side of the rail part n1, and an engaging pawl r12 to be a forward movement regulation part having a forward surface r121 to be a forward part facing forward and engageable with the backward surface n21.SELECTED DRAWING: Figure 9

Description

[Technical field]

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

[0002] 2. Description of the Related Art Chairs that are provided with a lumbar support on the backrest for supporting the lower back of a seated person have been known (see, for example, Patent Document 1).

[0003] In some chairs of this type, the lumbar support is removable from the left and right side frame members of the backrest without the need to attach or detach fasteners. The lumbar support is restricted from moving forward by a mesh-like tension member stretched between the left and right side frame members.

[0004] Therefore, when a conventional lumbar support receives an external force from behind, the tension member that prevents the support from moving forward also stretches forward, making the support prone to coming off the backrest. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-084336 A. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a chair having a configuration in which at least the lumbar support can be attached and detached from the backrest without having to attach or detach a fastening device, and the lumbar support is unlikely to come off the backrest even if it is subjected to an external force from behind. [Means for solving the problem]

[0007] That is, the present invention has the following configuration. The invention described in claim 1 is a chair in which a lumbar support capable of supporting the lower back of a seated person is detachably attached to a backrest without the need for fastening devices, the backrest comprising left and right side frame members extending in the vertical direction and a tension member stretched between the left and right side frame members, the left and right side frame members being formed with rail portions protruding forward and rearward facing portions located rearward of the tips of the rail portions, the left and right ends of the lumbar support being provided with rail engagement portions shaped to cover at least the front side of the rail portions, and a forward movement restricting portion having a forward facing portion that can engage with the rearward facing portions. The left and right side frame members are provided with grooves that open toward the left-right center of the backrest and extend in the up-down direction, and the rearward-facing portion is disposed in the grooves. It's a chair.

[0008] The invention described in claim 2 is the chair described in claim 1, wherein the rail portion extends in the vertical direction, the rail engagement portion is shaped to cover the front and both left and right sides of the rail portion, and the lumbar support is configured so that its position can be changed in the vertical direction relative to the backrest.

[0009] The invention described in claim 3 is the chair described in claim 2, in which a movement range restriction mechanism is provided between the lumbar support and the backrest, which restricts the vertical movement range of the lumbar support relative to the backrest.

[0011] Claim 4 The invention described in claims 1 and 2 is characterized in that the rail engagement portion includes a front wall disposed in front of the rail portion, an outer extension wall extending rearward from an outer edge of the front wall, and an inner extension wall extending rearward from an inner edge of the front wall. or This is the chair described in 3.

[0012] Claim 5 The invention described in claim 2 is characterized in that the forward movement restricting portion protrudes outward from the outer surface of the inner extending wall. 4 This is the chair described.

[0013] Claim6 The invention described in claim 1 is characterized in that the forward movement restricting portion is an engagement claw configured to be able to temporarily change the position when the lumbar support is attached to or detached from the backrest. 5 This is the chair described.

[0014] Claim 7 The invention described in claims 1, 2, 3, 4 and 5 is a lumbar support comprising a lumbar base installed between the left and right side frame members so that its position can be changed in the up and down direction, and a lumbar pad supported on the lumbar base so that its position can be changed in the left and right direction, the lumbar base comprising left and right held parts arranged at both left and right ends and held by the left and right side frame members, and a base body arranged between the left and right held parts, the left and right held parts and the base body being integrally formed from a synthetic resin, and the left and right held parts being provided with the rail engagement parts and the forward movement restricting parts. or This is the chair described in 6. Effect of the Invention

[0015] As described above, according to the present invention, it is possible to provide a chair which at least allows the lumbar support to be attached and detached from the backrest without having to attach or detach a fastening device, and which has a configuration which makes it difficult for the lumbar support to come off the backrest even if it is subjected to an external force from behind. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] Cross-sectional view taken along line AA in FIG. [Figure 10] Cross-sectional view taken along line BB in FIG. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. [Figure 15] FIG. [Figure 16] 16 is a cross-sectional view taken along line CC in FIG. 15. [Figure 17] FIG. [Figure 18] FIG. [Figure 19] FIG. [Figure 20] FIG. [Figure 21] Cross-sectional view taken along line DD in Figure 21. [Figure 22] FIG. [Figure 23] FIG. [Figure 24] FIG. 2 is an exploded perspective view of the embodiment as viewed from the rear side. [Diagram 25] FIG. [Figure 26] FIG. [Figure 27] FIG. 4 is a front view illustrating the attachment of the lumbar pad in the embodiment. [Figure 28] FIG. [Figure 29] FIG. [Diagram 30] 31 is a view seen in the direction of arrow E in FIG. 30 . [Diagram 31] FIG. 4 is a front view illustrating a movement of the lumbar support in the embodiment. [Diagram 32] FIG. 4 is a front view illustrating a movement of the lumbar support in the embodiment. [Diagram 33] FIG. 4 is a front view illustrating a movement of the lumbar support in the embodiment. [Diagram 34] FIG. 4 is a front view illustrating a movement of the lumbar support in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, one embodiment of the present invention will be described with reference to FIGS.

[0018] In this embodiment, the present invention is applied to a swivel chair for business use (hereinafter simply referred to as a "chair") suitable for use in an office or the like.

[0019] The chair comprises legs A, a support base B supported so as to be rotatable relative to the legs A, a seat C disposed on the support base B, a backrest E supported so as to be able to tilt backward relative to the support base B via a back support (not shown), and a lumbar support R attached to the backrest E.

[0020] <<Legs A>> The leg A includes a plurality of leg blades a1 each having a caster a11 at its tip, and a leg support a2 erected at the base end of the leg blade a1.

[0021] <<Support base B>> The support base B supports the seat C and the backrest E. The support base B is mainly composed of a support base main body 1 which is an integrally molded synthetic resin product. The support base main body 1 is connected to the upper end of the leg support a2.

[0022] <<Location C>> Seat C has a seating surface on which a seated person sits. Seat C is disposed on support base B. Seat C includes a seat support c1, also called an outer shell, and a seat body c2 having a seating surface and disposed on seat support c1. Seat C is supported on support base B via a seat support mechanism (not shown).

[0023] <<Back support (not shown)>> The back support is supported rotatably with respect to the support base B via a main shaft (not shown). The back support is interposed between the support base B and the backrest E, and between the support base B and the seat C.

[0024] <<Backrest E>> The backrest E comprises a back frame M attached to the back support and a mesh-like tension member P stretched over the back frame M.

[0025] The backrest E has a backrest surface pm that supports the back of a seated person from behind, and is formed from an upholstery member P that is mainly made of mesh fabric.

[0026] In this embodiment, a lumbar support R capable of supporting the waist of a seated person from the rear side is installed on the left and right side frame members 2 of the backrest E. Whether the lumbar support R is attached to the backrest E afterwards or detached from the backrest E, it can be performed by only temporarily bending the lumbar support R and engaging and disengaging the held portion r1 with the lumbar support holding portion N without using fasteners such as screws.

[0027] <Back frame M> The back frame M comprises left and right side frame members 2 each having a tension member mounting groove mz opening outward, an upper frame member 3 having a tension member mounting groove mz opening upward and connecting the upper parts of the left and right side frame members 2, a lower frame member 4 connecting the lower parts of the left and right side frame members 2, and an intermediate connecting frame member 5 having a tension member mounting groove mz opening downward and connecting the left and right side frame members 2 together while forming an upper cavity sa between the upper frame member 3 and a lower cavity sb between the lower frame member 4.

[0028] In this embodiment, the left and right side frame members 2, the upper frame member 3, the lower frame member 4, and the intermediate connecting frame member 5 that constitute the back frame M are integrally molded from synthetic resin.

[0029] The back frame M comprises an upper frame-shaped portion wa which is formed with an upper cavity sa therein by the left and right side frame members 2, an upper frame member 3 and an intermediate connecting frame member 5, and a lower frame-shaped portion wb which is formed with a lower cavity sb therein by the left and right side frame members 2, a lower frame member 4 and the intermediate connecting frame member 5.

[0030] The backrest E is configured such that the tension member P that can form the backrest surface pm is tensioned only to the upper frame portion wa provided on the back frame M. On the other hand, the tension member P is not tensioned to the lower frame portion wb.

[0031] [Left and right side frame material 2] The left and right side frame members 2 extend in the up-down direction. The left and right side frame members 2 have a bent portion 23 in the middle in the up-down direction, and are generally V-shaped in side view.

[0032] A tension member mounting groove mz is formed on the outer surface of the left and right side frame members 2, continuing from the upper end of the side frame members 2 to a height position approximately corresponding to the lower edge of the intermediate connecting frame member 5. A tension member P is tensioned between the left and right side frame members 2 extending in the vertical direction.

[0033] The left and right side frame members 2 each have an outer frame portion 21 having a tension member mounting groove mz that is open outward, and an inner frame portion 22 that is located inside the outer frame portion 21 and has its front portion located rearward of the front portion of the outer frame portion 21.

[0034] A lumbar support holding portion N capable of holding the lumbar support R in an adjustable vertical position is provided in the vertical middle portion of the left and right side frame members 2, which is at a height position corresponding to the waist of a seated person, more specifically, in the vertical middle portion of the inner frame portion 22 of the left and right side frame members 2.

[0035] The lumbar support holding portion N is provided near the bent portion 23, which is a portion of the left and right side frame members 2 that is bent so as to convex forward in side view (a portion that is bent so as to form a L-shape and jut out forward in side view).

[0036] The inner frame portion 22 of the left and right side frame materials 2 is provided with a rail portion n1 that protrudes forward and extends in the vertical direction, a groove portion n2 that opens toward the left-right central portion of the backrest E and extends in the vertical direction, and a guide groove n3 that is provided forward of the groove portion n2, opens toward the left-right central portion of the backrest E, and extends in the vertical direction.

[0037] The rail portion n1, the groove portion n2, and the guide groove n3 appear only by molding into the inner frame portions 22 of the left and right side frame materials 2. In other words, the rail portion n1, the groove portion n2, and the guide groove n3 are formed without attaching other separate and independent parts to the left and right side frame materials 2.

[0038] The rail portion n1 has a front surface n11 facing forward, an outward surface n12 facing the outer frame portion 21, and an inward surface n13 facing the opposite side to the outward surface n12, i.e., toward the center of the backrest E in the left-right direction.

[0039] The front surface n11 and the outward surface n12 of the rail portion n1 are arranged to be substantially perpendicular to each other. Similarly, the front surface n11 and the inward surface n13 of the rail portion n1 are arranged to be substantially perpendicular to each other. Also, the outward surface n12 and the inward surface n13 of the rail portion n1 are arranged to be substantially parallel to each other. The rail portion n1 is adapted to engage with a rail engagement portion r11 provided on the lumbar base RB.

[0040] Between the rail portion n1 and the outer frame portion 21, a receiving groove n4 is formed which is open forward and receives a rearwardly protruding outwardly extending wall r112 formed on the outer end of the lumbar base RB.

[0041] The left rail portion n1 and the right rail portion n1 are formed so as to gradually move toward each other in an upward direction when viewed from the front. In other words, the left rail portion n1 and the right rail portion n1 are not arranged parallel to each other in the vertical direction.

[0042] The groove portion n2 is located rearward of the tip end of the rail portion n1, i.e., the front-facing surface n11. The groove portion n2 has a rearward-facing surface n21 that is a rearward-facing portion that faces rearward. The groove portion n2 is formed rearward of the rail portion n1.

[0043] The groove portion n21 is formed in a V-groove shape having a rearward surface n21 that is substantially parallel to the forward surface n11 of the rail portion n1. An engagement claw r12 provided on the lumbar base RB is adapted to engage with the groove portion n21.

[0044] The guide groove n3 constitutes a movement range restriction mechanism Q that restricts the vertical movement range of the lumbar support R relative to the backrest E. The guide groove n3 is disposed approximately parallel to the groove portion n2. The guide groove n3 is set to be longer in the vertical direction than the groove portion n2. A pair of guide protrusions r13 provided on the lumbar base RB and spaced apart from each other in the vertical direction engage with the guide groove n3. The guide groove n3 has a groove shape that corresponds to the guide protrusions r13 that have rounded tips.

[0045] [Top frame material 3] The upper frame material 3 extends in the left-right direction. The upper frame material 3 has an outer frame portion 31 in which a tension member mounting groove mz that opens upward for mounting the tension member P is formed, and an inner frame portion 32 disposed below the outer frame portion 31.

[0046] [Bottom frame material 4] The lower frame material 4 connects the lower parts of the left and right side frame materials 2 and has a portion that is connected to the back support body via fasteners such as screws.

[0047] [Intermediate connection frame material 5] The intermediate connecting frame member 5 extends in the left-right direction and is installed between the portions of the left and right side frame members 2 that are inclined forward when viewed from the side. The intermediate connection frame member 5 has a curved shape that is convex toward the rear in a plan view. The intermediate connection frame member 5 is formed with a tension member mounting groove mz that opens downward.

[0048] <Upholstery material P> The upholstery member P is mainly made of a mesh-like fabric capable of forming the backrest surface pm.

[0049] The tensile member P is adapted to be attached at its peripheral portion to a tensile member attachment groove mz provided in the upper frame-shaped portion wa of the back frame M. The tensile member P is stretched over the front side of the upper frame-shaped portion wa of the back frame M.

[0050] <<Lumbar Support R>> The lumbar support R is supported by the backrest E in a detachable manner.

[0051] The lumbar support R is installed between the left and right side frame members 2 so that its position can be changed in the vertical direction. The lumbar support R is located behind the tension member P and is capable of supporting the lower back of a seated person.

[0052] The lumbar support R comprises a component attached to the backrest E, namely, a lumbar base RB, which is a single component that is spanned between the left and right side frame members 2 of the backrest E so that its position can be changed in the vertical direction, and a pair of left and right lumbar pads RP, which are supported on the lumbar base RB so that their position can be changed in the horizontal direction.

[0053] The lumbar support R comprises a lumbar base RB, which is a first part, having a through hole r211 extending in a predetermined left-right direction, and a lumbar pad RP, which is a second part, capable of adopting a first position, a preparatory position (J), and a mounting position (S), which is a second position different from the preparatory position (J), and which maintains its mounted state relative to the lumbar base RB in the mounting position (S).

[0054] The mounting position (S) is a position in which the lumbar pad RP is properly mounted on the lumbar base RB. As will be described in detail later, the lumbar pad RP can be slid naturally left and right relative to the lumbar base RB only in the mounting position (S) by the user applying left and right operating force to the operating body r4. The mounting position (S) is rotated about the axis of the connecting shaft portion r5 at an angle of about 90° from the preparation position (J).

[0055] <Lumber base RB> The lumbar base RB includes left and right held portions r1 disposed on both left and right ends and held by the left and right side frame members 2, and a base body r2 disposed between the left and right held portions r1.

[0056] The lumbar base RB is an integrally molded product made of synthetic resin. That is, the left and right held portions r1 and the base body r2 are integrally formed of synthetic resin.

[0057] [Left and right holding parts] The left and right held portions r1 are attached in the vicinity of the bent portions 23 of the left and right side frame members 2 in a detachable manner and slidable in the up and down direction.

[0058] The left and right held parts r1 are held by the lumbar support holding part N without using fasteners such as screws. The user flexes and deforms the base main body r2 to align the left and right holding parts r1 with the lumbar support holding part N in the left-right direction. Then, the user simply moves the left and right holding parts r1 backward and brings them closer to the lumbar support holding part N, so that they are attached to the left and right side frame members 2 in a state where they are difficult to come off.

[0059] The left and right held portions r1 are equipped with rail engagement portions r11 that engage with the rail portions n1 provided on the left and right side frame members 2 in a hugging manner from the front, engagement claws r12 that serve as forward movement restricting portions that engage with groove portions n2 provided on the left and right side frame members 2, and a pair of upper and lower guide protrusions r13 that engage with guide grooves n3 provided on the left and right side frame members 2.

[0060] The rail engagement portion r11 has a generally U-shaped portion covering the front side and both the left and right sides of the rail portion n1. More specifically, the rail engagement portion r11 includes a front wall r111 serving as a rearward movement restricting portion disposed on the front side of the rail portion n1, an outward extending wall r112 serving as an inward movement restricting portion extending rearward from the outer edge of the front wall r111, and an inward extending wall r113 serving as an outward movement restricting portion extending rearward from the inner edge of the front wall r111.

[0061] The front wall r111 of the rail engagement portion r11 covers the front surface n11 of the rail portion n1. The outwardly extending wall r112 of the rail engagement portion r11 covers the outwardly facing surface n12 of the rail portion n1. The inwardly extending wall r113 of the rail engagement portion r11 covers the inwardly facing surface n13 of the rail portion n1.

[0062] The vertical dimension of the outwardly extending wall r112 is set shorter than the vertical dimension of the front wall r111. The inwardly extending wall r113 forms a base for supporting the engaging claw r12 and extends rearward from the front wall r111 longer than the outwardly extending wall r112.

[0063] The engagement claw r12 has a forward surface r121 that is a forward portion that can engage with the rearward surface n21 that is the rearward portion of the groove portion n2. The engagement claw r12 protrudes outward from the outer surface of the inner extension wall r113 that constitutes the rail engagement portion r11.

[0064] The engaging claw r12 is configured to be able to temporarily change its position when the lumbar support R is attached to or detached from the backrest E. Only the rear end r122, which is the base end, of the engaging claw r12 is connected to the inner extending wall r113. In other words, the engaging claw r12 is supported in a cantilever manner with respect to the inner extending wall r113 so that a temporary change in position due to elastic deformation can be easily realized.

[0065] On the outer side between the rear end portion r122 and the front surface r121 of the engaging claw r12, a pressed inclined surface r123 that is pressed against the rail portion n1 when the lumbar support R is attached to the backrest E is provided.

[0066] The lumbar support R is attached to the backrest E by moving the left and right held portions r1 rearward toward the lumbar support holding portions N of the left and right side frame members 2.

[0067] As the engaging claw r12 moves rearward, the pressed inclined surface r123 provided on the engaging claw r12 is pressed by the rail portion n1 provided on the left and right side frame members 2. The engaging claw r12 with the pressed inclined surface r123 pressed thereon temporarily changes its position due to elastic deformation of the member, so that the left and right held portions r1 are allowed to move rearward until they reach the predetermined mounting positions.

[0068] Thereafter, the engaging claw r12 reaches the groove portion n2, and is released from the engagement with the rail portion n1, returning to its original position. The front surface r121 of the engaging claw r12 that has returned to its original position faces the rear surface n21 of the groove portion n2.

[0069] When an external force acts on the lumbar support R in a direction from the rear to the front, the forward surfaces r121 of the engaging claws r12 and the rearward surfaces n21 of the left and right side frame members 2 are surface-engaged, making it difficult for the left and right held portions r1 to move forward. Therefore, after the left and right held portions r1 are appropriately held by the lumbar support holding portion N, they are suitably prevented from coming off the lumbar support holding portion N.

[0070] In addition, when actively removing the left and right held portions r1 from the lumbar support holding portion N, a tool or the like can be used to press the pressed inclined surface r123 of the engaging claw r12 while releasing it from its engagement with the groove portion n2.

[0071] The guide protrusions r13 are provided on the inner extending wall r113 of the rail engagement portion r11 so as to protrude outward. The guide protrusions r13 are arranged in pairs on the upper and lower parts of the inner extending wall r113. The guide protrusions r13 have rounded tips. The guide protrusions r13 constitute a movement range restriction mechanism Q that restricts the vertical movement range of the lumbar support R relative to the backrest E.

[0072] In other words, between the backrest E and the lumbar support R, a movement range restriction mechanism Q is provided which restricts the vertical movement range of the lumbar support R relative to the backrest E.

[0073] [Base body r2] The base body r2 is disposed between the left and right held portions r1 and has a generally horizontally elongated rectangular shape in a front view. The left and right ends of the base body r2 are integrally connected to the left and right held portions r1. The base body r2 is curved so as to be convex toward the rear.

[0074] The base body r2 has a plate-like portion r21 having a horizontally elongated rectangular shape that is in an upright position and located in the center in the vertical direction, and a peripheral portion r22 that surrounds the upper, lower, left and right peripheral portions of the plate-like portion r21 and has a concave shape that protrudes toward the rear.

[0075] The plate-like portion r21 is a flat upright plate having no protruding portions such as ribs. The plate-like portion r21 is more easily deformed in the thickness direction than the peripheral portion r22. The plate-like portion r21 is configured to be temporarily elastically deformable when the left and right lumbar pads RP are attached and detached.

[0076] As will be described in detail later, the lumbar pad RP is allowed to change its position from the preparation position (J) to the mounting position (S) by temporary elastic deformation of a plate-like portion r21 provided on the base body r2 of the lumbar base RB. The plate-like portion r21 is capable of temporary elastic deformation in the thickness direction at least when the lumbar pad RP rotates from the preparation position (J) to the mounting position (S) by being pressed by the connecting shaft portion r5.

[0077] The plate-shaped portion r21 has left and right through-holes r211 at the center in the vertical direction, which penetrate in the front-rear direction and extend in the left-right direction. The left and right through-holes r211 are elongated in the left-right direction, penetrate in the front-rear direction, and have a substantially constant vertical width dimension w1. The left and right through-holes r211 are provided corresponding to the left and right lumbar pads RP. The left through-hole r211 and the right through-hole r211 are drilled at a distance from each other on the left and right sides of the plate-shaped portion r21. In other words, a non-perforated portion is provided between the left through-hole r211 and the right through-hole r211 in the plate-shaped portion r21. The left and right through-holes r211 define the left-right movable range of the left and right lumbar pads RP in the wearing posture (S).

[0078] The peripheral portion r22 has recesses hk that can function as ribs over its entire area. Due to the presence of the recesses hk, the peripheral portion r22 has a structure that is less susceptible to bending deformation in the thickness direction compared to the plate-like portion r21.

[0079] The peripheral portion r22 has an upper peripheral portion forming portion r221 located above the plate-shaped portion r21, a lower peripheral portion forming portion r222 located below the plate-shaped portion r21, and left and right peripheral portion forming portions r223 located on the left and right sides of the plate-shaped portion r21.

[0080] In this embodiment, in order to stabilize the mounting position S of the lumbar pad RP, i.e., to prevent the lumbar pad RP in the mounting position (S) from rotating toward the preparation position (J), the protruding ends t1 of the upper and lower positioning protrusions r33 provided on the lumbar pad RP are configured to contact the upper peripheral portion forming portion r221 and the lower peripheral portion forming portion r222.

[0081] <How to attach the lumber base RB to the left and right side frame materials 2> An example of a method for attaching the lumber base RB to the left and right side frame members 2 will be described below.

[0082] The lumbar base RB can be attached to the left and right side frame materials 2 and can be detached from the left and right side frame materials 2 without using fasteners such as screws for the backrest E.

[0083] Even when the lumbar pad RP is not attached to the lumbar base RB, the lumbar base RB can be attached to the left and right side frame members 2.

[0084] In addition, even when the lumbar pad RP is attached to the lumbar base RB, the incoming lumbar base RB can be attached to the left and right side frame members 2.

[0085] First, the left and right held portions r1 provided on the left and right sides of the lumbar base RB are positioned in front of the lumbar support holding portions N of the left and right side frame members 2. A tension member P is preliminarily tensioned between the left and right side frame members 2 constituting the backrest E.

[0086] Therefore, when positioning the left and right held portions r1 in front of the lumbar support holding portion N, the lumbar base RB is passed from the rear through the upper cavity sa formed by the upper frame-shaped portion wa, and the left and right held portions r1 are positioned in front of the lumbar support holding portion N while the lumbar base RB temporarily presses the tension member P forward.

[0087] The position of the lumbar support holding portion N is gradually inclined upward toward the center of the backrest E in the left-right direction. In other words, the left lumbar support N and the right lumbar support N extending in the vertical direction are not always spaced apart by the same distance in the vertical direction.

[0088] Therefore, when engaging the left and right held portions r1 with the lumbar support holding portion N, the base body r2 of the lumbar base RB is elastically deformed (deformed so that the degree of curvature of the base body r2 becomes smaller, or deformed so that the degree of curvature of the base body r2 becomes larger), thereby fine-tuning the left and right positions of the left and right held portions r1 to match the positions of the lumbar support holding portion N.

[0089] Next, the left and right held portions r1 are moved while being pressed backward, so that the rail engagement portion r11, the engagement claw r12, and the guide protrusion r13 are engaged with the rail portion n1, the groove portion n2, and the guide groove n3 of the left and right side frame members 2. As described above in detail, when the left and right held portions r1 move backward, the engagement claw r12 temporarily changes its position to a position retreated from the rail portion n1, and then returns to its original position and is positioned within the groove portion n2.

[0090] <Left and right lumbar pads RP> A plurality of lumbar pads RP, i.e., left and right (two) lumbar pads RP, are arranged in pairs on the left and right sides of the lumbar base RB. As shown in Figures 33 and 34, the left and right lumbar pads RP are mounted so as to be slidable in the left and right directions relative to the lumbar base RB. The left lumbar pad RP and the right lumbar pad RP have the same structure. The left lumbar pad RP and the right lumbar pad RP are independently movable in the left and right directions relative to the lumbar base RB.

[0091] In this specification, the top and bottom and the left and right of the left and right lumbar pads RP will be described based on the wearing position S, which is the second position in which the longitudinal direction is the up and down direction, unless otherwise specified.

[0092] The left and right lumbar pads RP are equipped with a pad main body r3 which is an impassable part arranged between the tension member P and the lumbar base RB and can press the tension member P from the rear, an operating body r4 which is a passable part located on the rear side of the lumbar base RB and can be grasped by the user, and a connecting shaft portion r5 which is interposed between the pad main body r3 and the operating body r4 and engages with the left and right through holes r211.

[0093] The pad body r3 has a vertically long rectangular shape with four rounded corners when viewed from the front. The pad body r3 constitutes an impassable portion that cannot pass through the through hole r211. The vertical dimension w2 of the pad body r3 is set to be approximately the same as the vertical dimension w3 of the base body r2 of the lumbar base RB.

[0094] The pad main body r3 includes a pad base r31 having a vertically elongated rectangular plate shape, flange portions r32 extending rearward from the upper and lower ends of the pad base r31, upper and lower positioning protrusions r33 protruding rearward from the vertical center of each of the upper and lower halves of the pad main body r3, and whose protruding ends t1 can abut the forward surface of the base main body r2 of the lumbar base RB, a vertical reinforcing rib r34 protruding rearward from the left-right center of the pad main body r3 and extending in the vertical direction connecting the upper and lower positioning protrusions r33 and the connecting shaft portion r5, and a horizontal reinforcing rib r35 protruding rearward from the vertical center of the pad main body r3 and connected to the connecting shaft portion r5.

[0095] The operating body r4 is shaped so that the user can grasp it with his / her fingers in order to slide the lumbar pad RP left and right relative to the lumbar base RB.

[0096] The operating body r4 is generally in the shape of a block extending in the vertical direction. The operating body r4 constitutes a passable portion that can pass through the through hole r211 provided in the lumbar base RB while widening it only when the preparation posture (J) is adopted. The vertical dimension w4 of the operating body r4, which is the longitudinal direction, is set shorter than the vertical dimension w2 of the pad main body r3, which is the longitudinal direction. The vertical dimension w4 of the operating body r4, which is the longitudinal direction, is set shorter than the longitudinal dimensions of the left and right through holes r211 provided in the plate-like portion r21.

[0097] The width dimension (short-side dimension) w4 of the rear end portion, i.e., the tip portion t2, of the operating body r4 is set shorter than the width dimension (short-side dimension) w5 of the base end portion t3, which is the front end portion, i.e., the connection portion with the connecting shaft portion r5 of the operating body r4.

[0098] In other words, the width dimension of the operation body r4 is set so as to gradually increase from the tip end t2 toward the base end t3 (so as to gradually increase in width from the tip end t2 toward the base end t3). The width dimension w4 of the tip end t2 of the operation body r4 is set so as to substantially match the vertical width dimension w1 of the through hole r211 provided in the plate-like portion r21 of the base main body r2.

[0099] The connecting shaft portion r5 is a rectangular columnar member. The connecting shaft portion r5 extends in the front-rear direction so as to connect the vertical and horizontal center portions of the pad main body r3 and the vertical center portion of the operation body r4. The connecting shaft portion r5 connects the pad main body r3 and the operation body r4, and a portion of the connecting shaft portion r5 is disposed within the through-hole r211.

[0100] The connecting shaft portion r5 is substantially prismatic in shape and has a vertical dimension w7 portion set to a value that substantially matches the vertical width dimension w1, which is the short dimension of the through hole r211. The vertical dimension w7 of the connecting shaft portion r5 in the mounting position S is set to a dimension that substantially matches the vertical width dimension w1 of the through hole r211 provided in the plate-like portion r21 of the base main body r2.

[0101] On the other hand, the left-right dimension w8 of the connecting shaft portion r5 in the mounting posture S is set to be longer than the up-down dimension w7 of the connecting shaft portion r5 in the mounting posture S. The width dimension w5 of the base end portion t3 of the operating body r4 and the left-right dimension w8 of the connecting shaft portion r5 are set to be approximately the same dimension.

[0102] <How to attach the lumbar pad RP to the lumbar base RB> An example of a method for attaching the left and right lumbar pads RP to the lumbar base RB will be described below. The left and right lumbar pads RP can be attached to the lumbar base RB when it is not attached to the backrest E, and can also be attached to the lumbar base RB when it is attached to the backrest E.

[0103] The left and right lumbar pads RP can take a preparatory position (J), which is the position when they are attached to the lumbar base RB, i.e., a position in which the operating body r4 can be inserted and removed into the through hole r211 of the lumbar base RB, and an attached position (S), which is a position different from the preparatory position (J) and in which the pads are attached to the lumbar base RB.

[0104] The mounting position (S) is rotated about the axis of the connecting shaft portion r5 at an angle of about 90° with respect to the preparation position (J). The mounting position (S) is a position of the lumbar pad RP in which the operating body r4 cannot be inserted into or removed from the through hole r211 of the lumbar base RB. In this embodiment, in the preparation position (J), the pad main body r3 and the operating body r4 are horizontally elongated, and in the mounting position (S), the pad main body r3 and the operating body r4 are vertically elongated.

[0105] First, as shown in FIG. 24, the lumbar pad RP is placed in the preparation position (J) and then positioned in front of the lumbar base RB.

[0106] Next, as shown in Fig. 25, the tip t2 of the operating body r4 of the lumbar pad RP is inserted from the front to the rear into the through hole r211 while in the preparation posture (J). The operating body r4 can pass through the through hole r211 from the front to the rear only when the operating body r4 is in the preparation posture (J).

[0107] The vertical width dimension w1 of the through hole r211 is approximately the same as the width dimension w5 of the tip end t2 of the operating body r4, but is shorter than the width dimension w6 of the base end t3 and the width dimension w8 of the connecting shaft portion r5.

[0108] Therefore, when the operating body r4 and the connecting shaft portion r5 of the lumbar pad RP in the preparatory position (J) pass through the through hole r211, the plate-shaped portion r21 in which the through hole r211 is provided is elastically deformed so as to be pushed open by the operating body r4 and the connecting shaft portion r5.

[0109] In other words, when the operating body r4 and the connecting shaft portion r5 in the preparatory position (J) are inserted from the front to the rear into the through hole r211, the plate-shaped portion r21 is pressed by the operating body r4 and the connecting shaft portion r5 and can temporarily elastically deform to allow them to pass through.

[0110] 26 and 27, the worker rotates the operating body r4 or the pad main body r3 by approximately 90 degrees while gripping them to change the position of the lumbar pad RP from the preparation position (J) to the mounting position (S). That is, after passing the operating body r4 through the through hole r211 and positioning the connecting shaft part r5 in the through hole r211, the lumbar pad RP is rotated around the axis of the connecting shaft part r5 to change the position from the preparation position (J) to the mounting position (S).

[0111] In detail, the worker passes the lumbar pad RP in the preparatory position (J) through the through hole r211 in the order of the operating body r4 and the connecting shaft portion r5, and then rotates the lumbar pad RP to the right or left around the axis of the connecting shaft portion r5 to change its position from the preparatory position (J) to the mounting position (S).

[0112] When the connecting shaft r5 rotates about 90° from the preparation position (J) to the mounting position (S) in the through hole r211, the plate-like portion r21 is temporarily pushed outward by the diagonal corners of the connecting shaft r5, widening the through hole r211 to the maximum. In this way, the lumbar pad RP is allowed to change its position from the preparation position (J) to the mounting position (S) by the temporary elastic deformation of the plate-like portion r21.

[0113] When the lumbar pad RP transitions from the preparation position (J) to the mounting position (S), the vertical dimension w7 of the connecting shaft portion r5 in the mounting position (S) approximately matches the vertical width dimension w1 of the through hole r211, and the plate-shaped portion r21 of the base body r2 returns from its spread-out state to its original relatively flat state.

[0114] In this embodiment, a reversal prevention means G is provided between the lumbar base RB and the lumbar pad RP to prevent the lumbar pad RP from reversing from the mounting position (S) to the preparation position (J). The reversal prevention means G is provided on the lumbar pad RP side and is composed of a connecting shaft part r5 whose up-down dimension w7 in the mounting position (S) is set shorter than the left-right dimension w8, and a through hole r211 provided on the lumbar base RB side, extending in the left-right direction, and whose up-down width dimension w1 is set to be approximately the same as the up-down dimension w7 of the connecting shaft part r5.

[0115] Through the above steps, the lumbar pad RP is attached to the lumbar base RB. The left and right lumbar pads RP attached to the lumbar base RB can be moved left and right relative to the lumbar base RB at the user's discretion by operating the operating body r4 left and right while gripping it.

[0116] When the lumbar pad RP is to be removed from the lumbar base RB, the above-mentioned procedure can be carried out in reverse.

[0117] The above-described embodiment can provide a chair with excellent design freedom, allowing the second part, lumbar pad RP, to be easily attached to the first part, lumbar base RB.

[0118] Furthermore, with the above-described embodiment, at least the lumbar support R can be attached and detached from the backrest E without attaching or detaching a fastening device, and a chair can be provided having a configuration in which the lumbar support S is unlikely to come off the backrest E even if it is subjected to an external force from behind.

[0119] Furthermore, with the above-described embodiment, it is possible to provide a chair having a lumbar support R that can flexibly adjust the degree of support for the lumbar region of the seated person to suit the physique and preferences of the seated person.

[0120] As described above, in the chair according to this embodiment, the lumbar support R capable of supporting the lower back of a seated person is detachably provided to the backrest E without the need to attach or detach a fastener.

[0121] The backrest E includes left and right side frame members 2 extending in the vertical direction and a tension member P stretched between the left and right side frame members 2.

[0122] The left and right side frame members 2 are formed with a rail portion n1 that protrudes forward and a rearward facing surface n21 that is located rearward of the tip of the rail portion n1, i.e., the forward facing surface n11, and faces rearward.

[0123] A rail engagement portion r11 having a shape covering at least the front side of the rail portion n1 is provided at both left and right ends of the lumbar support R, and an engagement claw r12 serving as a forward movement restricting portion is provided having a forward facing surface r121 which is a forward facing portion facing forward and can engage with the rearward facing surface n21.

[0124] As a result, at least the lumbar support R can be attached and detached from the backrest E without having to attach or detach fasteners such as screws, and a chair can be provided having a configuration in which the lumbar support R is unlikely to come off the backrest E even if it is subjected to an external force from behind.

[0125] That is, the lumbar support R is provided with an engagement claw r12 having a front surface r121 that can engage with the rear surface n21. Therefore, even if the lumbar support R receives an unexpected external force from the rear to the front, the front surface r121 of the engagement claw r12 engages with the rear surfaces n21 of the left and right side frame members 2, so that the lumbar support R is unlikely to come off the backrest E.

[0126] The rail portion n1 extends in the vertical direction, and the rail engagement portion r11 is shaped to cover the front side and both the left and right sides of the rail portion n1. The lumbar support R is configured so that its position can be changed in the vertical direction with respect to the backrest E.

[0127] Therefore, the rail engagement portion r11 has a suitable shape that allows it to be appropriately positioned with respect to the rail portion n1 and to be movable in the vertical direction.

[0128] A movement range restriction mechanism Q is provided between the lumbar support R and the backrest E, which restricts the vertical movement range of the lumbar support R relative to the backrest E.

[0129] Therefore, the lumbar support R can move up and down relative to the backrest E within an appropriate range.

[0130] The left and right side frame members 2 are provided with grooves n2 that are open toward the left-right center of the backrest E and extend in the vertical direction. A rearward surface n21, which is a rearward portion, is disposed in the grooves n2.

[0131] Therefore, by arranging the engagement claw r12 in the groove portion n2, the engagement claw r12 is difficult to see when viewed from behind, thereby achieving a desirable appearance while providing the desired anti-dislodging function.

[0132] The rail engagement portion r11 comprises a front wall r111 arranged in front of the rail portion n1, an outer extending wall r112 extending rearward from the outer edge of the front wall r111, and an inner extending wall r113 extending rearward from the inner edge of the front wall r111.

[0133] Therefore, the rail engagement portion r11 can be suitably positioned in a manner that allows smooth vertical movement relative to the rail portion n1 extending in the vertical direction.

[0134] The engagement claw r12, which is a forward movement restricting portion, protrudes outward from the outer surface of the inner extending wall r113.

[0135] For this reason, the engaging claw r12 is preferably disposed within the groove portion n2.

[0136] The engagement claw r12, which serves as a forward movement restricting portion, is configured to be able to temporarily change its position when the lumbar support R is attached to or detached from the backrest E.

[0137] Therefore, when the lumbar support R is properly supported relative to the backrest E, the engagement claw r12 is likely to return from a temporary change in posture and position itself within the groove portion n2, thereby enabling the lumbar support R to optimally perform its function of preventing itself from slipping off the backrest E.

[0138] The lumbar support R comprises a lumbar base RB installed between left and right side frame members 2 so that its position can be changed in the vertical direction, and left and right lumbar pads RP supported on the lumbar base RB so that its position can be changed in the horizontal direction.

[0139] The lumbar base RB comprises left and right retained portions r1 arranged at both left and right ends and retained by the left and right side frame materials 2, and a base main body r2 arranged between the left and right retained portions r1, the left and right retained portions r1 and the base main body r2 being integrally formed from synthetic resin, and the left and right retained portions r1 are provided with rail engagement portions r11 and engagement claws r12 which act as forward movement restricting portions.

[0140] For this reason, the lumbar base RB is a one-piece molded product made of synthetic resin, which not only contributes to reducing the number of parts but also allows for a suitable configuration that easily ensures overall rigidity.

[0141] Furthermore, the left and right retained portions r1 are provided with rail engagement portions r11 that can perform a positioning function with respect to the rail portion n1, and engagement claws r12 that can prevent dislodging against external forces from the rear, resulting in excellent design freedom that can compactly achieve the desired purpose.

[0142] It should be noted that the present invention is not limited to the embodiment described above in detail.

[0144] The rearward-facing portion is not limited to having a flat surface, but may have projections and recesses.

[0145] The rail engagement portion needs to cover at least the front side of the rail portion.

[0146] The forward movement restricting portion is not limited to an engaging claw, but may be of any configuration as long as it has a forward facing portion that faces forward and can engage with the rearward facing portion.

[0147] The forward-facing portion is not limited to having a flat surface, but may have projections and recesses.

[0148] The lumbar support does not have to be configured so that its position can be changed in the vertical direction relative to the backrest.

[0149] The specific configuration of the movement range restriction mechanism may be any configuration that is capable of restricting the vertical movement range of the backrest in the lumbar support, and is not limited to a configuration using a guide groove and a guide protrusion.

[0150] Furthermore, the specific configuration of each part is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0151] E…Backrest P…Stretching material 2...Left and right side frame members n1…Rail section n21…Rearward facing surface (backward facing part) R…Lumbar support r11...Rail engagement part r12...Engagement claw (forward movement restriction part)

Claims

1. A chair in which a lumbar support capable of supporting the lower back of a seated person is detachably provided on a backrest without attaching or detaching a fastener, The backrest is provided with left and right side frame members extending in the vertical direction and a tension member stretched between the left and right side frame members, The left and right side frame members are formed with rail portions protruding forward and rearward-facing portions located rearward of the tips of the rail portions, A rail engagement portion having a shape covering at least the front side of the rail portion is provided at both left and right ends of the lumbar support, and a forward movement restriction portion having a forward facing portion that can engage with the rearward facing portion is provided, The chair has a groove portion on the left and right side frame members that opens toward the left-right central portion of the backrest and extends in the vertical direction, and the rearward-facing portion is disposed in the groove portion.

2. The rail portion extends in a vertical direction, The rail engagement portion is shaped to cover the front side and both left and right sides of the rail portion, 2. The chair according to claim 1, wherein the lumbar support is configured so that its position can be changed in the up and down direction relative to the backrest.

3. 3. The chair according to claim 2, further comprising a movement range limiting mechanism provided between the lumbar support and the backrest for limiting a vertical movement range of the lumbar support relative to the backrest.

4. A chair as described in claim 1, 2 or 3, wherein the rail engagement portion comprises a front wall arranged in front of the rail portion, an outer extending wall extending rearward from the outer edge of the front wall, and an inner extending wall extending rearward from the inner edge of the front wall.

5. 5. The chair according to claim 4, wherein the forward movement restricting portion protrudes outward beyond an outer surface of the inner extending wall.

6. 6. The chair according to claim 5, wherein the forward movement restricting portion is an engaging claw configured to be able to temporarily change the position when the lumbar support is attached to or detached from the backrest.

7. The lumbar support includes a lumbar base that is installed between the left and right side frame members so as to be vertically positionally changeable, and a lumbar pad that is supported on the lumbar base so as to be horizontally positionally changeable, The lumber base includes left and right retained parts disposed at both left and right ends and retained by the left and right side frame members, and a base body disposed between the left and right retained parts, and the left and right retained parts and the base body are integrally formed from a synthetic resin, 7. The chair according to claim 1, 2, 3, 4, 5 or 6, wherein the rail engaging portion and the forward movement restricting portion are provided on the left and right held portions.

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