JP2012010939A - Chair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chair that achieves simple assembly work while guaranteeing the strength of the chair itself.SOLUTION: A backrest support body has right and left back support arms 151. The back support arms are respectively turnably supported to a support base. The back support arms are mounted from the lateral outside of a back support bracket 155 so as to cover a spindle, the back support bracket 155, and a lower connecting member 157. Namely, the back support arms 151 are mounted from the lateral outside of the back support bracket 155 so as to cover, particularly, the back support bracket 155 and the lower connecting member 157 and to reinforce each other, thereby effectively enhancing the strength as the backrest support body.

Description

  The present invention relates to a chair configured so that the backrest can tilt backward.

  Conventionally, in a chair configured to support a seat and a backrest on a support base and to be operable with respect to each of the support bases, a back support that supports the backrest on a back support bracket configured to be rotatable on the support base. Various chairs have been proposed in which the backrest attached to the back support arm can be tilted backward by attaching the arm (see, for example, Patent Document 1).

  In such a chair, it is required to make the strength of the chair itself as high as possible.

  In order to increase the strength of the chair itself, for example, a high-strength metal connecting member is often used at the main part of the chair that is easily loaded by the weight of the seated person and the movement. At this time, a cover member for concealing these metals may be attached depending on the specifications of the chair, for example, when it is desired to make the appearance entirely of resin.

  However, when the number of parts of such a cover member increases, the process of assembling these cover members directly affects the work efficiency at the time of assembly, and as a result, much labor is required for the assembly. End up.

JP 2008-206765 A

  The present invention focuses on simplifying the assembly work of the back support arm based on the background described above, and provides a chair that can realize simple assembly work while ensuring the strength of the chair itself. The purpose is to do.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the chair according to the present invention supports the left and right back support brackets, whose rear ends are connected by a connecting material, to the support base via the support shaft, and the both ends of the support shaft that protrude outward from the back support bracket. The left and right back support arms that rotate together with the back support bracket are supported, and the back support arm supports the backrest, and the left and right back support arms are connected to the left and right sides of the back support bracket. The support shaft, the back support bracket, and the connecting material are covered by being attached from the outside.

  If this is the case, since it is possible to cover a plurality of members at once, the number of parts for covering each member can be effectively reduced, and consequently the number of assembly work steps can be effectively reduced. can do. Further, by covering a plurality of members at a time, the joints between the parts generated by the cover can be reduced, which can contribute to a simple appearance.

  As a configuration for effectively contributing the strength of the connecting material to the strength of the back support arm, the back support arm is a strength member that supports the backrest so that it can be tilted backward, and a cover member that covers the connecting material is integrally molded. Can be mentioned.

  Further, in order to realize both the relative positioning of the left and right back support arms and the guarantee of strength, the cover members are provided on the left and right back support arms, respectively, and the cover members and the connecting members are fixed. It is desirable.

  In order to effectively position the cover member and the connecting member, it is preferable that the cover member has a U-shape facing forward in a sectional view and the rear surface of the connecting member is covered.

  In particular, the mounting strength is not easily affected by the load applied to the back support arm, and in order to always achieve a strong mounting state, the cover member is in close contact with the upward surface of the connecting material. It is desirable to fix the cover member.

  In order to effectively improve the strength against the load in the torsional direction, it is desirable that the connecting material be bent in a side sectional view.

  In order to effectively cover the movable part and the fixed part, respectively, and to achieve positioning using the fixed part, the shaft end cover that covers the back end of the rotating shaft that protrudes left and right from the support base It is preferable to have a part.

  In order to receive the load applied to the backrest appropriately and to support the backrest indirectly on the support base without interfering with the seat or other components, the back support arm extends in the front-rear direction extending in the front-rear direction It is preferable to form a substantially U-shape in a side view including a portion and an upright portion continuously extending upward from the rear end of the front-rear direction extending portion, and to support the backrest in the upright portion.

  And in order to implement | achieve a back seat synchro-rocking mechanism with a simple structure, reducing a number of parts effectively, it is preferable to integrally form the seat support protrusion for supporting a seat to a back support arm.

  If this seat support protrusion raises the seat as the backrest tilts backward, the weight-sensing back seat synchro-rocking mechanism can be realized with a simple configuration. On the other hand, if this seat support projection lowers the seat as the back leans backward, the back seat synchro locking mechanism of the type in which the rear end of the seat descends as the back leans backward is realized with a simple configuration Can do.

  As a specific configuration to realize a weight-sensing back seat synchro-rocking mechanism that is simple and can reliably lift the seat as the back leans backward, the seat support protrusion is forward facing the shaft end cover part. An embodiment in which the link is inclined to protrude to support the seat can be exemplified.

  According to the present invention, since a plurality of members can be covered at a time, a chair that can effectively reduce the number of man-hours for assembly work can be provided.

The perspective view from the front which shows one Embodiment of this invention. The perspective view from the front which decomposes | disassembles and shows the tension ground of the embodiment. The front which abbreviate | omits and shows the tension | tensile_strength of the embodiment partially. The left view which decomposes | disassembles and shows the tension ground of the embodiment. The rear view which abbreviate | omits and shows the tension place of the embodiment partially. The perspective view from the back which abbreviate | omits and shows the leg of the embodiment. The disassembled perspective view which abbreviate | omits and shows a part of the whole embodiment. The perspective view from the front which expands and shows the principal part of the support base and back support arm of the embodiment. The disassembled perspective view which expands and shows the principal part of the support base of the same embodiment, and a back support arm. The perspective view from the back which abbreviate | omits and shows the support base part of the embodiment abbreviate | omitting. The front view which decomposes | disassembles and shows the support base part of the embodiment. The left view which shows the support base and seat of the embodiment. Explanatory drawing equivalent to FIG. 12 which shows the locking mechanism of the embodiment. The disassembled perspective view which shows the seat and seat receiver of the embodiment. Sectional view on the AA line which showed the principal part in FIG. BB sectional drawing which showed the principal part in FIG. CC sectional view which showed the principal part in FIG. The perspective view which showed the attachment structure of the backrest support body and back support member of the embodiment. The perspective view which decomposes | disassembles and shows the back shell and back support member of the embodiment. The front view of the back shell of the embodiment. The front view of the back support member of the embodiment. DD line sectional drawing which showed the principal part in FIG. EE sectional view which showed the principal part in FIG. The FF line expanded sectional view in FIG. The GG sectional view taken on the line in FIG. The figure which shows the principal part which concerns on the modification 1 of this embodiment. The figure which shows the principal part which concerns on the modification 2 of the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the present invention is applied to an office swivel chair.

  As shown in FIGS. 1 to 7, the chair includes a leg 1, a support base 3 supported by the leg 1, a seat receiver 5 disposed on the support base 3, and a support supported by the seat receiver 5. The seat 7, the back support 9 that is rotatably supported by the support base 3, the back 11 attached to the back support 9, and the back tilting operation of the back 11 are performed. And a rocking mechanism 13 for moving the seat receiver 5 and the seat 7 upward and downward, and an armrest 15 provided on the backrest support 9.

《Leg composition》
As shown in FIGS. 1 to 7, the leg 1 includes a leg base 17 and a leg support 19 provided at the center of the leg base 17.

  As shown in FIG. 1 to FIG. 5 and FIG. 7, the leg base 17 is provided with a plurality of leg blades 23 radially projecting from a hub 21 provided in the center portion. 25 are provided.

  As shown in FIGS. 1 to 5, 7, and 14, the leg support 19 is a gas spring type that is elastically expanded and contracted in the vertical direction so that it can be locked at a desired position. belongs to. That is, the leg support 19 includes a gas spring main body 27 fitted to the hub 21 of the leg base 17 and a rod 29 protruding from the upper end of the gas spring main body 27. An operation button 31 for unlocking is projected. The support base 3 is attached to the upper end of the rod 29. The unlocking operation button 31 is operated by an elevating operation lever 295 provided on an armrest 15 described later.

《Support base configuration》
As shown in FIGS. 7 to 13, the support base 3 includes a main frame 33 attached to the rod 29 of the leg support 19, and a front link shaft 35 and a support shaft 37 attached to the main frame 33. It will be. The front link shaft 35 is for supporting the front end portion of the seat receiver 5 through the front link 39. The support shaft 37 is for supporting the backrest support body 9 and supporting a substantially intermediate portion of the seat receiver 5 via the rear link 41.

  As shown in FIGS. 7 to 13, the main frame 33 has a boss portion 43 fitted to the upper end portion of the rod 29 in the leg support 19 and a semicircular arc shape in plan view surrounding the upper end side of the boss portion 43. The rear frame member 45, a pair of side frame members 47 extending forward from the left and right front ends of the rear frame member 45, and the front end portions of the side frame members 47 are coupled to each other and have a flat surface at the front end. A front frame member 49 is provided. The boss portion 43, the rear frame member 45, the side frame member 47, and the front frame member 49 are integrally formed by aluminum die casting or the like. A front bearing portion 51 that supports the front link shaft 35 is integrally provided on the upper surface portion of the front frame member 49, and the support shaft is located near the boundary between the rear frame member 45 and the side frame member 47. A rear bearing portion 53 that supports 37 is integrally provided. In addition, the height from the floor surface of the shaft center of the two bearing portions 51 and 53 is different, and the front bearing portion 51 is set at a higher position than the rear bearing portion 53.

  As shown in FIG. 12, the main frame 33 incorporates a tilt reaction force generation mechanism 55 that biases the backrest 11 forward.

  As shown in FIGS. 8 to 13, the tilt reaction force generating mechanism 55 includes a torque transmission bracket 57 having a base end portion supported by the support shaft 37 and a left and right torque transmission bracket 57. The movable shaft 59 is provided between the front end portions of the spring 57, and a spring 63 that elastically biases the movable shaft 59 backward as a scaffold by using a spring receiver 61 provided on the main frame 33 as a scaffold. Reference numeral 64 designates a lifting / lowering unlocking arm for pressing the unlocking operation button 31 provided on the rod 29 of the leg post 19, and as shown in FIGS. , A lifting wire for transmitting the operating force of the lifting control lever 295 provided on the armrest 15 to the lifting lock release arm 64. When the wire 297 is pulled by operating the operation lever 295, the base end boss portion 66 externally fitted to the support shaft 37 rotates and is provided integrally on the opposite side of the wire 297 across the base end boss portion 66. The unlocked arm 64 is rotated downward.

  The support base 3 is covered with an upper cover 65 and a lower cover 67 as shown in FIGS. 3 to 6, 10, and 11.

  As shown in FIGS. 10 and 11, the upper cover 65 covers the support base 3 from the upper surface side, and is provided with an upper locking claw 69 protruding downward to engage with the support base 3. The lower cover 67 covers the support base 3 from the lower surface side, and is provided with a lower locking claw 71 protruding upward to engage with the support base 3. Further, the upper cover 65 and the lower cover 67 are arranged so that the opening end edges 73 and 75 abut each other.

  On the outer peripheral surface of the front side of the main frame 33 of the support base 3, in other words, on the flat surface of the front end of the front frame member 49, as shown in FIGS. And a common upper / lower mounting portion 77 for mounting the upper and lower sides.

  More specifically, the main frame 33 of the support base 3 includes an upper locking claw 69 of the upper cover 65 and a lower locking claw 71 of the lower cover 67, as shown in FIGS. An upper and lower common mounting portion 77 for engaging is provided, and the upper and lower common mounting portion 77 is engaged with an engagement end surface 79 with which the upper locking claw 69 is engaged and with the lower locking claw 71. An end face 81, a locking end face 83 for preventing lateral shift for locking lateral shift of the upper locking claw 69, and a locking end face 85 for preventing lateral shift for locking lateral shift of the lower locking claw 71 are provided. Yes.

  As shown in FIGS. 8, 10, and 11, the upper and lower common mounting portion 77 is provided on the outer peripheral surface 87 of the front end of the front frame member 49 in the main frame 33, and the outer peripheral surface 87 of the front end is rectangular. It is recessed in the shape. In the upper and lower mounting part 77, the upper side is an engagement end surface 79 with which the upper locking claw 69 of the upper cover 65 is engaged, and the lower side is an engagement end surface 81 with which the lower locking claw 71 of the lower cover 67 is engaged. Further, in the upper and lower common mounting portion 77, the left and right sides are locking end surfaces 83 and 85 for preventing lateral displacement with respect to the upper locking claw 69 and the lower locking claw 71 of the upper cover 65 and the lower cover 67.

  Note that, in the vicinity of the middle in the front-rear direction on the outer periphery of the main frame 33, as shown in FIGS. 8 to 10, 12, and 13, an upper dedicated mounting portion 89 for mounting the upper cover 65 and a lower cover 67 are mounted. And a lower dedicated mounting portion 91. The upper cover 65 is provided with a claw 93 that engages with the upper dedicated mounting portion 89, and the lower cover 67 is provided with a claw 95 that engages with the lower dedicated mounting portion 91.

  Further, as shown in FIG. 10, an upper dedicated mounting portion 97 for mounting the upper cover 65 and a lower dedicated mounting portion 99 for mounting the lower cover 67 are provided at the rear end of the outer periphery of the main frame 33. Yes. The upper cover 65 is provided with a claw 101 that engages with the upper dedicated mounting portion 97, and the lower cover 67 is provided with a claw 103 that engages with the lower dedicated mounting portion 99. In other words, the rear frame member 45 of the main frame 33 includes a substantially horizontal central protrusion that is the lower dedicated mounting portion 99 and a pair of upper dedicated mounting portions 97 disposed on both sides of the lower dedicated mounting portion 99. Side ridges are provided. The upper dedicated mounting portion 97 is arranged with a height different from that of the lower dedicated mounting portion 99.

  In addition to the above, the opening edges 73 and 75 of the upper and lower covers 65 and 67 are provided with grooves, except for the vicinity of the rotating shaft, so that the outer peripheries of the upper cover 65 and the lower cover 67 are also brought into contact with each other. Specifically, one of the upper cover 65 and the lower cover 67 has a fitting recess exposed to the outside, and the other has an L-shaped groove that can be fitted to each other with the fitting recess exposed to the inside. . In this way, the upper and lower covers 65, 67 adapted to engage with the upper and lower dedicated mounting portions 89, 91 of the support base 3 are arranged so as to cover the claws 93, 95 at a certain distance from the support base 3. Even if it has comprised, upper and lower covers 65 and 67 can be reliably fitted.

  The left and right front links 39 are rotatably attached to the bearing portion 51 in front of the support base 3 described above via the front link shaft 35. The structure for attaching the front link 39 to the support base 3 is as follows. That is, as shown in FIGS. 8 to 13, the support base 3 includes a bearing portion 51 that supports the front link shaft 35 on the left and right sides, and a pair of opposed flat surfaces 105 that are perpendicular to the axial direction. The front link 39 is located between the planes 105 in the rotation range (U) when used so that the chair can perform its original function, and the front link 39 can be inserted into and removed from the support base 3 (not shown). In the rotation range at the time of insertion / removal, a plane corresponding portion 107 located outside the plane 105 is provided, and the front link 39 is rotatably supported by the support base 3 via the front link shaft 35.

  In other words, as shown in FIGS. 8 to 13, the support base portion 3 is positioned forward and upward at a bearing portion 51 that supports the front link shaft 35 and a position adjacent to the axial direction of the bearing portion 51. And an open link arm housing portion 109. The link arm housing portion 109 is formed between a pair of flat surfaces 105 orthogonal to the front link shaft 35. The front link 39 has a shaft hole 113 for holding the front coupling shaft 111 at the upper end portion and a boss portion 115 that is externally mounted on the front link shaft 35 at the base end portion. A link arm 117 is provided. The link arm 117 has a plane corresponding portion 107 corresponding to the link arm accommodating portion 109.

  In the in-use rotation range (U), the plane corresponding portion 107 of the link arm 117 is located between the opposing planes 105 of the link arm accommodating portion 109. Therefore, the left and right front links 39 are prohibited from being detached from the front link shaft 35 and the front connecting shaft 111. On the other hand, in the rotation range at the time of insertion / removal, the plane corresponding portion 107 of the link arm 117 is located outside the plane 105 facing the link arm housing portion 109. Therefore, the left and right front links 39 can be detached from the front link shaft 35 and the front connecting shaft 111. In the assembled state, the front link 39 is set so as not to rotate to the rotation range during insertion / removal. At the time of assembly, the front link 39 is laid back to the front link shaft 111 passed through the front link mounting portion 121 of the seat 5 and the front link shaft 35 passed through the front bearing portion 51 of the main frame 33 from the left and right. Fit. In this state, the front link 39 is tilted forward, and the link arm 117 of the front link 39 is fitted between the opposing flat surfaces 105 of the link arm housing portion 109. Thereafter, the rear link shafts 123 are fitted into the rear link mounting portions 127 located substantially in the middle of the seat receiver 5 and the back support arms 151 are attached from the left and right, whereby the assembly state described above is achieved. That is, the left and right front links 39 can be attached to the main frame 33 without using a retaining part such as a screw.

  The seat base 5 is supported on the support base 3 configured as described above via the front link 39 and the rear link 41.

《Composition of the seat》
As shown in FIG. 4 to FIG. 6, FIG. 12, FIG. 13, and FIG. On the lower surface of the seat 5, a front link mounting portion 121 for mounting the rotation end 119 of the front link 39 via the front connection shaft 111 and a rotation end 125 of the rear link 41 via the rear connection shaft 123 are provided. A rear link attachment portion 127 for attachment is provided. The front link mounting portion 121 and the rear link mounting portion 127 are provided integrally with the seat receiver 5.

  Ribs 126 are formed in a grid pattern in the vertical and horizontal directions on the upper surface of the seat 5, and two parallel parts of the ribs 126 extend so as to protrude below the seat 5, and the front link mounting portion 121. And the rear link attaching part 127 is comprised. The left and right sides of the front link mounting portion 121 and the rear link mounting portion 127 are closed by side walls 128 and 130 having through holes. These side walls 128 and 130 may also be formed by extending a part of the rib 126 downward. The other ribs 126 are formed so as to be connected to these ribs 126 at a plurality of locations, and are designed to contribute not only to the strength of the seat 5 itself but also to the strength of the front link mounting portion 121 and the rear link mounting portion 127. ing. That is, the front link mounting portion 121 and the rear link mounting portion 127 are hollow bodies having front walls 118 and 122, rear walls 120 and 124, and left and right side walls 128 and 130, respectively. , 122, the rear walls 120, 124, and the left and right side walls 128, 130 are formed by extending a part of the rib 126 downward.

《Composition of the seat》
As shown in FIGS. 7, 14, and 15, the seat 7 includes an inner shell 129 attached to the upper surface of the seat receiver 5, a cushion 131 disposed on the inner shell 129, and the cushion 131. And a tension fabric 133 stretched on the outer surface.

  As shown in FIG. 15, the inner shell 129 is integrally formed of synthetic resin, and is fixed to the seat receiver 5 with a claw or the like (not shown). The inner shell 129 is provided with a front end drooping portion 135 that gently hangs obliquely downward on the front side, and the intermediate portion 137 bulges below the peripheral portion 139 at the boundary between the intermediate portion 137 and the peripheral portion 139. An annular step 141 is formed.

  As shown in FIGS. 14 and 15, the cushion 131 is made of urethane foam or the like, and includes a cushion hanging portion 143 along the front end hanging portion 135 of the inner shell 129 on the front side. In addition, the upper surface of the cushion 131 which is the core material of the seat 7 is provided with a plurality of uneven portions arranged in one direction, in other words, a plurality of grooves 145 arranged in the front-rear direction in this embodiment.

  As shown in FIGS. 1 to 7, 14, and 15, the upholstery 133 is a bag that covers the cushion 131 and the peripheral edge 139 of the inner shell 129, and the upholstery that is wound around the lower surface of the inner shell 129. The edge 147 of 133 is arranged along the end surface of the step 141 of the inner shell 129. The step 141 and the edge 147 of the upholstery 133 are covered by the seat 5 so as to be hidden. The upholstery 133 has a visual feature portion associated with the groove 145 formed in the cushion 131. In this embodiment, the visual feature portion is a line 149 formed by embossing the stretch fabric 133. In this embodiment, a plurality of the filaments 149 exist so as to be arranged in the front-rear direction, and are present at positions where they overlap with the grooves 145 of the planar cushion 131 from above when the upholstery 133 is placed on the cushion 131. . However, it is important that the line 149 is recognized by the user's vision, and the groove 145 of the cushion 131 and the line 149 of the upholstery 133 do not necessarily overlap in plan view.

<< Configuration of back support body >>
As shown in FIGS. 7 to 9, 16, and 17, the backrest support 9 includes left and right back support arms 151 that extend rearward and upward from the support base 3, and the left and right back support arms 151. The upper connecting member 153 that connects the upper end portions 169 of each of the left and right sides, and the left and right sides that extend integrally from the base end of the torque transmission bracket 57 toward the rear upper side and that contact the inner side surface of the base end portion of the back support arm 151. A back support bracket 155 and a lower connection member 157 that connects the rear ends of the left and right back support brackets 155 and is a connection member according to the present invention are provided.

  As shown in FIGS. 1 to 9, 13, and 16 to 18, the left and right back support arms 151 are made of resin and are rotatably supported on the support base 3, respectively. Are attached from the left and right outer sides to cover the support shaft 37, the back support bracket 155, and the lower connecting member 157. The back support arm 151 is integrally formed of, for example, glass fiber reinforced resin having a certain level of strength or more, and functions as a so-called strength member that ensures the strength of the back support 9 itself. In other words, the back support arm 151 is attached from the left and right outer sides of the back support bracket 155, and particularly reinforces each other by covering the back support bracket 155 and the lower connecting member 157. Strength is effectively secured.

  The left and right back support arms 151 include a front-rear direction extending portion 159 extending in the front-rear direction and a standing portion 161 extending continuously upward from the rear end of the front-rear direction extending portion 159. In the example of illustration, the front-back direction extension part 159 and the standing part 161 have comprised the substantially U shape in the side view. Each back support arm 151 has a base end portion, that is, a shaft end for fitting from the outside to an end portion 165 of a support shaft 37 provided on the support base portion 3 at a front end portion 163 of the front-rear extension portion 159. A shaft mounting portion 167 as a cover portion is provided. Each back support arm 151 is provided with an arm protrusion 171 for attaching the upper connecting member 153 to the tip, that is, the upper end 169 of the upright portion 161.

  As shown in FIG. 3 to FIG. 9 and FIG. 16, the shaft mounting portion 167 of each back support arm 151 is fitted with the end portion 165 of the rotating shaft that protrudes left and right from the support base, that is, the end portion 165 of the support shaft 37. A shaft hole 173 that is opened only inward is provided. Specifically, the end 165 of the support shaft 37 is fitted into the shaft hole 173 via the bush 175 so as to be relatively rotatable. The bush 175 is inserted from the inner surface side of the back support bracket 155 before the support shaft 37 is mounted, and the support shaft 37 is fitted into the inner periphery of the bush 175 so as to be relatively rotatable. The flange portion 177 of the bush 175 is located between the back support bracket 155 and the main frame 33. The shaft mounting portion 167 is fitted on the outer periphery of the bush 175, and the end portion 165 of the support shaft 37 is covered by the shaft mounting portion 167. The shaft hole 173 has a tapered shape with a large diameter on the opening end side, and the support shaft 37 has a cylindrical shape. The bush 175 has a shape filling the space between the inner peripheral surface of the shaft hole 173 and the outer peripheral surface of the shaft 37. That is, the outer peripheral surface of the bush 175 has a tapered shape, and the inner peripheral surface has a cylindrical shape having the same cross-sectional shape in each part.

  As shown in FIGS. 3 to 9, 16 and 17, a rear link 41 which is a seat support protrusion according to the present invention is integrally provided on the outer periphery of the shaft mounting portion 167. In other words, in the present invention, the seat 7 is supported by the back support arm via the seat receiver 5 so that the backrest 11 and a part of the locking mechanism 13 that operates the seat 5 are operated as described later. . By providing the rear link 41 while tilting forward from the outer periphery of the shaft mounting portion 167 in a state where the backrest 11 is raised, the tip supporting the seat receiver 5 is raised as the backrest 11 is tilted backward. By configuring as described above, a weight sensing type synchro-rocking operation as described later is enabled.

  In addition, on the inner side surface of the left and right back support arms 151 in the vicinity of the shaft mounting portion 167, a front U-shaped cover member 181 that covers the half portion 179 of the lower connecting member 157 is integrally formed. It is molded to project. The cover member 181 is provided with a screw insertion hole 183. The screw 187 inserted into the screw insertion hole 183 in the state shown in FIGS. 8, 16, and 17 in which the contact surface 181a which is the lower surface of the cover member 181 and the pressure receiving surface 179a of the lower connecting member are in close contact with each other. Are screwed into a screw hole 185 provided in the lower connecting member 157, whereby the left and right back support arms 151 are attached to the lower connecting member 157. And as shown in FIG. 17, in the state which attached the cover member to the lower connection material 157, the rear surface of the lower connection material 157, ie, the standing wall part 157b, is covered from the outside invisible.

  In this state, the left and right back support arms 151 are coupled to each other via the lower connecting member 157, so that the shaft mounting portion 167 does not come out of the support shaft 37. That is, the left and right back support brackets 155 whose rear ends are connected by the lower connecting member 157 are supported by the support base 3 via the support shaft 37, and both ends of the support shaft 37 projecting outward from the back support bracket 155. Since the left and right back support arms 151 that rotate together with the back support bracket 155 are supported by the part 165, the left and right back support arms 151 are attached from the left and right outside of the back support bracket 155, so 37, the back support bracket 155 and the lower connecting member 157 can be covered. In this embodiment, the ends 189 of the cover member 181 of the left and right back support arms 151 are closely abutted in the assembled state.

  As shown in FIGS. 7 and 18, the arm projecting portion 171 of the back support arm 151 is for attaching the end of the upper connecting member 153, and is a screw insertion hole 191 and a screw hole continuous to the screw insertion hole 191. And a nut not shown.

  As shown in FIGS. 7 and 18, the upper connecting member 153 is a metal metal having a channel shape, and is installed between the arm projecting portions 171 of the left and right back support arms 151 and screwed to the nut. The screw 195 is attached to each back support arm 151. That is, the upper connecting member 153 has a shape that opens rearward, and is fitted between the upper end portion 169 of the back support arm 151 by being fitted to the arm projecting portion 171 from the front side.

  As shown in FIGS. 9, 12, 13, 16, and 17, the back support bracket 155 is made of metal and is integrally formed with the torque transmission bracket 57. Via the main frame 33 so as to be rotatable.

  As shown in FIGS. 9, 16 and 17, the lower connecting member 157 is made of metal, and both ends thereof are rigidly connected to the rear end of the back support bracket 155 by welding. The lower connecting member 157 receives the load from the back support arm 151 in a state where the left and right half 179 are in close contact with the close contact surface 181a of the cover member and the sheet metal at the rear end. It has a so-called side-view shape that has a bent portion 157a bent and a standing wall portion that hangs downward from the bent portion. Thereby, the rigidity with respect to the external force of the twist direction in the state welded to the back support bracket 155 is improved effectively.

  The lower connecting member 157 has a skeletal function of the back support arm 151 made of synthetic resin in cooperation with the back support bracket 155. Moreover, it also has a function as a base for preventing the back support arm 151 fitted from the left and right from being detached from the left and right. Further, the lower connecting member 157 receives a backward tilting load acting on the backrest 11 via the back support arm 151, and transmits the load via the back support bracket 155 for torque transmission of the tilt reaction force generation mechanism 55. It also has a function of transmitting to the bracket 57.

  The backrest 11 is supported by the backrest support body 9 as described above.

《Composition of backrest》
As shown in FIGS. 1 to 7, the backrest 11 is made of a resin-made back shell 205 that is curved until it becomes substantially horizontal at the top 201 and has an opening 203 for promoting elastic deformation at an almost middle portion thereof. The back shell 205 includes a back support member 209 that supports a leading edge 207 located behind the top portion 201 of the back shell 205, and a tension fabric 206 attached to the surface side of the back shell 205.

  The back shell 205 is made of a resin supported by the backrest support 9 as shown in FIGS. 2 to 7, 19, 20, 22 to 24, and is substantially horizontal at the top 201. And has an opening 203 for promoting elastic deformation substantially in the middle. That is, in the back shell 205, a plurality of belt-like members 213 extending in the vertical direction are arranged in the upper region 211 on the left and right, and the opening 203 is formed between the belt-like members 213. Further, the back shell 205 has a shape corresponding to the waist of the seated person, that is, the waist-corresponding portion 215 having a wide left and right width and gradually becoming narrower as it goes upward in a front view.

  As shown in FIGS. 2 to 7, 19, 20, 22, and 24, the upper region 211 is provided continuously on the front portion 217 that receives the back of the seated person and the upper edge of the front portion 217. The top portion 201 includes an upper curved portion 219 that is curved until it is substantially horizontal, and a back portion 221 that is provided continuously from the rear edge of the upper curved portion 219 and curves downward and hangs down. A groove 223 that opens downward is formed at the leading edge 207 of the back surface portion 221.

  The groove 223 includes a main insertion portion 225 for fitting the back support member 209, and a sub-opening on the back side of the back support member 209 in a state where the back support member 209 is fitted to the main insertion portion 225. And a fitting portion 227. That is, the groove 223 provided in the distal end edge 207 of the back shell 205 is a stepped groove shape in which a main insertion portion 225 and a sub insertion portion 227 are continuously formed, and the main insertion portion 225 has a back support member. When an upper mounting portion 251 (described later) 209 is inserted, only the auxiliary insertion portion 227 is left open and left. The sub insertion portion 227 is continuous with a side edge groove 235 described later, and by attaching the tension fabric 206 using the sub insertion portion 227 and the side edge groove 235, the front shell 205 is moved from the front surface to the upper back surface side. It can be covered with a stretch fabric 206. It should be noted that a rib 228 for adjusting elastic deformation is formed on the belt-like member 213 of the back surface portion 221.

  Further, as shown in FIGS. 2 to 7, 19, 20, and 23, the lower region 229 of the back shell 205 has a concave shape in which the left and right sides protrude forward from the middle in the left-right direction. In the lower region 229, a protrusion 231 continuous with the strip member 213 is formed, and a thin portion 233 continuous with the opening 203 is formed between adjacent protrusions 231. A lower region 229 of the back shell 205 has a portion 215 corresponding to the waist of the seated person raised upward in a side view, and is curved so that the center in plan view is recessed.

  As shown in FIGS. 1, 2, 4, 6, 19, 22, and 23, the back shell 205 has side edge grooves 235 that are opened outward on the left and right side edges, respectively. The side edge grooves 235 and the sub-insertion portions 227 in the grooves 223 are continuous. In addition, a lower edge groove 237 that is continuous with the side edge groove 235 is provided at the lower end of the back shell 205.

  As shown in FIGS. 1 to 6, the lower portion 239 of the back shell 205 is attached to the front surface of the back support arm 151, and the upper portion 243 is supported by the back support member 209. The attachment of the lower part 239 of the back shell 205 will be described. A plurality of nut holes 204 are formed on the front side of the upright portion 161 of the left and right back support arms 151 so as to be spaced apart from each other. On the other hand, screw insertion holes respectively corresponding to the nut holes 204 are provided on the left and right sides of the lower portion 239 of the back shell 205. Accordingly, the mounting screws 241 are inserted through the screw insertion holes from the front and then screwed into the nut holes 204 to tighten the left and right sides of the lower portion 239 of the back shell 205 between the left and right back support arms 151. It can be fixed to the front surface of the upright portion 161. The screw 241 is concealed when the upholstery 206 is provided.

  As shown in FIGS. 1, 2, 4 to 7, 19, 21, 22, 22, 24 and 25, the back support member 209 is opened to the left and right and below the back surface of the back shell 205. It is a plate-like one disposed so as to form a space 245, and is supported by the backrest support 9 to control the deflection of the back shell 205 in the front-rear direction. The back support member 209 has a concave shape when viewed from the front in which the left and right sides protrude forward from the middle in the left-right direction. The width of the back support member 209 is smaller than the width of the front portion 217 and the lower region 229 of the upper region 211 of the back shell 205. A supporting member main body 247 having a lower mounting portion 249 provided at the lower end of the supporting member main body 247 and attached to the upper connecting member 153; and a main fitting portion 225 of the groove 223 provided at the upper end of the supporting member main body 247. And the rib 253 formed over the upper mounting portion 251, the support member main body 247 and the lower mounting portion 249. Note that the left and right end edges of the back support member are thicker than the middle part, and this functions as a peripheral reinforcing material.

  The support member main body 247 is plate-shaped as shown in FIGS. 4 to 7, 18, 19, 19, 21, 22, 24 and 25, and the left and right sides are more forward than the middle in the left-right direction. A protruding curved shape is formed, and a bent portion 255 is formed below the upper mounting portion 251. The bent portion 255 is shaped such that the upper side of the bent portion 255 is inclined forward with respect to the lower side. In other words, the bent portion 255 is bent in a square shape when viewed from the side.

  As shown in FIGS. 4 to 7, 19, 21, and 24, the upper mounting portion 251 has a thickness dimension that can be closely fitted to the main fitting portion 225, and is in a fitted state. And attached to the back shell 205 using screws 263. That is, the upper attachment portion 251 is a plate-like member extending upward from the upper end of the support member main body 247, and the upper end portion of the rib 253 is located on the front surface thereof. On the front surface of the upper mounting portion 251, the plate nut 257 is disposed between the adjacent ribs 253, and the upper end portion thereof is fitted into the main fitting portion 225 of the groove 223, thereby positioning and holding the plate nut 257. Be able to. The back support member 209 can be attached to the back shell 205 by screwing the screw 263 inserted from the back side through the screw hole 261 of the back shell 205 into the screw hole 259 of the plate nut 257. It has become. In this state, the plate nut 257 is hidden by the back shell 205 and the back support member 209.

  As shown in FIGS. 4 to 7, 19, 21, and 25, the lower mounting portion 249 includes a rear wall 265 that continuously extends downward from the lower end of the support member main body 247, and the rear wall 265. A top wall 267 that extends forward from the upper end of the wall and connects the ribs 253 located in the middle to each other, and a front wall 269 that hangs downward from the front edge of the top wall 267, and the upper connection The material 153 has a shape opened downward so that it can be fitted from above. A screw insertion hole 273 for inserting a screw 271 for attaching the back support member 209 to the upper connecting member 153 is formed in the front wall 269 of the lower attachment portion 249.

  As shown in FIGS. 7, 19, 21, 22, 24, and 25, the rib 253 extends in the vertical direction, and a plurality of ribs 253 are provided on the front surface of the back support member 209. These ribs 253 are shaped so that the projecting dimension gradually decreases toward the upper side. The ribs 253 are arranged on the left and right with a substantially constant interval. The ribs 275 located on both the left and right sides are cut off at the lower end of the support member main body 247 and do not extend to the lower mounting portion 249. The top wall 267 is located below the ribs 275 located on the left and right sides. And the front wall 269 is not provided. On the other hand, the rib 277 located in the middle extends to the front surface of the front wall 269 of the lower mounting portion 249. The protruding dimensions of the ribs 275 located on the left and right sides are set to be smaller than the protruding dimensions of the ribs 277 positioned in the middle. Further, below the back support member 209, the thickness dimension of the ribs 275 located on the left and right sides is larger than the thickness dimension of the ribs 277 located in the middle. Specifically, the ribs 275 located on the left and right sides, which are shorter in the vertical direction than the ribs 277 located in the middle, have a thickness dimension of about 6 millimeters below, while the ribs 277 located in the middle are located below. The thickness dimension is about 4 millimeters. Therefore, when the back support member 209 is viewed from the back side, it seems that there are frames extending in the vertical direction on both the left and right sides.

  As shown in FIGS. 1 to 7 and FIGS. 22 to 24, the tension fabric 206 is mainly composed of a breathable and translucent cloth material, and covers almost the entire area of the back shell 205. The end portion 279 is fixed to the outer peripheral edge of the back shell 205. More specifically, the lower end portion 281 of the upholstery 206 is pushed into the lower edge groove 237 of the back shell 205 and fixed, and the left and right end portions 283 are pushed into the side edge groove 235 of the back shell 205. It is fixed. Further, the upper portion 285 of the upholstery 206 is placed on the outer surface of the upper curved portion 219 and the rear portion 221 of the back shell 205, and the end portion 279 is pushed into the sub-insertion portion 227 of the groove 223 to be fixed. Specifically, a pushing material (not shown) is sewn on the entire periphery of the end portion of the upholstery fabric 206, and together with the pushing material, an end portion 279, a lower end portion 281 of the upholstery fabric 206, and left and right end portions. 283 is attached to the sub-insertion portion 227, the lower edge groove 237, and the side edge groove 235 of the groove 223 of the back shell 205, respectively. Note that the head of the screw 263 that connects the back shell 205 and the back support member 209 is covered with the tension fabric 206 attached to the back shell 205.

  The backrest 11 as described above is visible in a state in which both side edges of the back shell 205 protrude outward from both side edges of the back support member 209 in the rear view. In addition, the back side of the upholstery 206 can be visually recognized through the opening 203 of the back shell 205 when viewed obliquely from the rear, and the rib 253 of the back support member 209 can be visually recognized from the perspective viewed from diagonally forward. It is.

  The backrest 11 configured as described above and the seat 7 are interlocked by a locking mechanism 13.

《Configuration of locking mechanism》
As shown in FIGS. 4 to 13, the locking mechanism 13 is of a weight sensing type in which the seat 7 is moved upward while being tilted in accordance with the backward tilting motion of the backrest 11.

  Specifically, as shown in FIGS. 4 to 13, the locking mechanism 13 includes a support base portion 3 that holds a front link shaft 35 on the front side and a support shaft 37 on the rear side, and a lower end portion on the front side. After the front link 39 that is rotatably supported by the support base 3 via the link shaft 35 and the lower end portion are integrated with the shaft mounting portion 167 of the back support arm 151 supported by the support shaft 37. The link 41 and the front link attaching part 121 are connected to the turning end 119 of the front link 39 via the front connecting shaft 111 and the rear link attaching part 127 is connected to the turning end of the rear link 41 via the rear connecting shaft 123. The main body is composed of a seat 5 connected to 125.

  That is, as shown in FIGS. 4 to 13, the locking mechanism 13 supports the seat base 5 supporting the seat 7 on the support base 3 by the front link 39 and the rear link 41 inclined in the same direction. In accordance with the backward tilting operation of the back support arm 151 supported by the base 3, the front link 39 and the rear link 41 are rotated in the upright direction to lift the seat receiver 5 upward. When the backrest 11 is tilted backward, the front portion of the seat 7 is lifted more than the rear portion of the seat 7. That is, in the normal backrest and seat synchro-rocking mechanism, the seat is tilted only downward in accordance with the backward tilting motion of the backrest, but the weight sensing type locking mechanism as shown in this embodiment 13, unlike a normal locking mechanism, as shown by a two-dot chain line in FIG. 13, the seat 7 is tilted against the load of the seated person while the seat 7 is tilted in accordance with the backward tilting motion of the backrest 11. It is configured to lift.

  More specifically, as shown in FIG. 13, when the backrest 11 is not tilted backward, the forward link 39 has a forward inclination degree larger than the forward inclination degree of the rear link 41. Is set. In other words, the inclination angle α with respect to the horizontal line at the front link 39 is set smaller than the inclination angle β with respect to the horizontal line at the rear link 41 when the backrest 11 is not tilted backward. Further, the center of rotation of the front link 39 relative to the support base 3 is set at a position higher than the center of rotation of the rear link 41 relative to the support base 3. In other words, the axis of the front link shaft 35 is set at a position higher than the axis of the support shaft 37 by a distance h. The effective length dimension of the front link 39, that is, the inter-center distance L1 between the front link shaft 35 and the front connecting shaft 111, and the effective length dimension of the rear link 41, that is, the support shaft that is the rear link shaft. 37 and the rear connecting shaft 123 are set to be substantially the same distance L2. Further, the back support arm 151 is pivotally supported by a portion of the support base 3 that is in front of the leg column 19. In other words, the shaft mounting portion 167 of the back support arm 151 is supported by the support shaft 37 positioned in front of the leg support 19 in a side view.

  The point that the forward tilting degree of the front link 39 is larger than the forward tilting degree of the rear link 41 is intended to lift the front side of the seat 7 relatively larger than the rear side during the rearward tilting. By making the forward tilting degrees of the link 39 and the rear link 41 greatly different from each other, it is possible to set the lift of the front side of the seat 7 when tilting backward to a large value. That is, the front link 39 has many operations for lifting the front portion of the seat 7, that is, the front portion 7a1 of the seating surface 7a, and the rear link 41 is mainly for the operation of moving the seat 7 rearward. As a result, the seat surface 7a1 lifts the front portion 7a a lot while the rear portion 7a2 of the seat surface 7a moves backward and moves backward so as to follow the backrest 11 tilting backward. As a result, the relative positional relationship between the rear end portion of the seat 7 and the lower end portion of the backrest 11 is effectively suppressed by tilting the seat surface 7a relatively rearward.

  The point of making the rotation center positions of the front link 39 and the rear link 41 different in the vertical direction is mainly for the purpose of adjusting the level of the seat 7 when standing upright. By combining with the forward tilt degree difference, the posture of the seat 7 when the backrest 11 stands and the posture of the seat 7 when the backrest 11 is tilted backward are both set to an optimum state. By making the effective length dimension L1 of the front link 39 and the effective length dimension L2 of the rear link 41 substantially the same, the setting can be made more appropriate.

  In general, in a chair in which the back support arm is pivotally supported at a position in front of the leg column in the support base, the backrest tends to sink downward when the backrest is tilted. When the normal weight-sensing locking mechanism that allows the entire seat to lift upward when tilting is used, a large sense of incongruity, more specifically, against the seated person's expectation, As a result of the entire seat including the seat being lifted up, there is a sense of incongruity caused by the simultaneous movement of the backrest sinking motion and the seat lifting motion opposite to the sinking motion in the vicinity of the seated person's waist. According to the configuration of the embodiment, the uncomfortable feeling is alleviated. That is, although the thing of this embodiment is a body weight sensing type, even when the backrest 11 is tilted backward, the rear side of the seat 7 is not lifted greatly, so that it is difficult to give a great sense of incongruity.

  In the present embodiment, the rear link 41 rotates integrally with the back support arm 151 and the torque transmission bracket 57 around the support shaft 37 that is the rotation center of the back support arm 151. Thereby, not only the interlocking operation of the seat 7 accompanying the back tilting operation of the backrest 11 but also the accurate positioning of the seat 7 by the support base 3 via the rear link 41 is realized. Further, in the present embodiment, the rotation range of the backrest 11 is set to 20 degrees, and the angle formed by the seat surface 7a in the state where the backrest 11 is tilted back as much as possible is compared to when the backrest 11 stands. It is set to tilt 4 degrees backward. That is, in the present embodiment, the backrest 11 by the front link 39 is larger than the dimension γ2 in which the rear portion 7a2 of the seating surface 7a is lifted mainly by lifting the substantially central portion of the seat 5 when the backrest 11 is tilted backward. As a result of setting the dimension γ1 at which the front portion 7a1 of the seat surface 7a is lifted when tilted backward to be larger, the angle of the seat surface 7a when the backrest 11 is fully tilted is tilted by 4 degrees than when the backrest 11 is upright. I have to. In addition, in the present embodiment, since the rear link 41 is connected to the substantially central portion in the front-rear direction of the seat receiver 5, both the front and rear links 39, 41 when the backrest 11 is tilted backward are lifted up. However, since the front link 39 lifts the seat receiver 5 more than the rear link 41, the rear end portion of the seat receiver 5 can be set relatively lower than the front end portion, and the front end portion of the seat receiver 5 is raised. At this time, the height position of the rear end portion of the seat receiver 5 is hardly changed between when the backrest 11 stands and when it tilts backward.

《Arrangement of armrest》
As shown in FIGS. 1 to 7 and 18, the armrest 15 includes an elbow support portion 287 that integrally projects forward from the front surface of the upper end portion of the back support arm 151 of the backrest support 9, and the elbow support portion. And an elbow rest 289 provided on 287.

  As shown in FIGS. 3 to 6 and 18, the elbow support portion 287 has a bottomed boat shape opened upward. One elbow support portion 287, in this embodiment, a bottom wall 291 at the front end portion of the right elbow support portion 287 when viewed from the seated person, is formed with a penetrating window 293, and the lower side through the window 293 The operation lever 295 is protruded. The operation lever 295 is for operating the operation button 31 for unlocking the leg column. The operation lever 295 and the operation button 31 are connected by a wire 297, and the operation force applied to the operation lever 295 is transmitted to the operation button 31 by the wire 297, so that the operation button 31 can be operated. The leg strut can be locked / unlocked. A proximal end portion of the operation lever 295 and one end portion of the wire 297 connected to the operation lever 295 are accommodated in the elbow support portion 287.

  The internal space of the elbow support portion 287 communicates with the wire guide space 298 formed in the standing portion 161 of the back support arm 151. The wire guide space 298 extends in the vertical direction, and a part or all of the wire guide space 298 opens forward. The lower end portion of the wire guide space 298 reaches just above the longitudinally extending portion 159, and is located slightly below the lower end of the back shell 205 in a state where the lower portion 239 of the back shell 205 is attached to the upright portion 161. Open to the front. Therefore, the wire 297 connected to the operation lever 295 is led from the inner space of the elbow support portion 287 to the lower end portion of the wire guide space 298, and then reaches the support base portion 3 along the longitudinally extending portion 159. The

  As shown in FIGS. 1 to 5, 7, and 18, the elbow rest 289 is detachable from the elbow support 287. As a result, any one of a plurality of types of elbow rests 289 that can be attached to the common elbow support 287 can be selected and used. In the elbow rest 289 shown in this embodiment, an attachment base 299 that is directly attached to the elbow support 287 and an elbow rest main body 301 that is supported by the attachment base 299 and on which a seated person's arm is placed are integrated. Is provided.

  The mounting base 299 includes a base 303 that is attached to the upper end 169 of the elbow support 287 and the back support arm 151, and a spacer 305 that extends substantially horizontally from the inner end of the base 303. The base 303 is hooked to the elbow support 287 by a locking mechanism (not shown) on the front side, and the rear side is attached to the front side of the back support arm 151 using screws 307. The spacer 305 of the elbow rest 289 is for filling a space where the top wall 267 directly below the rib 275 does not exist, and has a plate shape substantially continuous with the top wall 267 of the lower mounting portion 249 of the back support member 209. ing. The spacer 305 is closely interposed between the upper surface of the upper connecting member 153 and the lower end surfaces of the ribs 275 located on the left and right sides of the back support member 209.

  Thus, the chair according to the present embodiment covers the support shaft 37, the back support bracket 155, and the lower connecting member 157 by attaching the back support arm 151 from the left and right outside of the back support bracket 155. Therefore, the number of parts for covering each member can be effectively reduced, and as a result, the number of assembly steps can be effectively reduced. Thereby, while reducing the number of parts which comprise a chair, the man-hour and work time which concern on the assembly | attachment of this chair were able to be reduced effectively.

  In this embodiment, since the back support arm 151 is integrally formed with the cover member 181 that covers the lower connecting member 157, the strength of the lower connecting member 157 is effectively contributed to the strength of the back supporting arm 151. Realized.

  In addition, in the present embodiment, the cover member 181 and the lower connecting member 157 provided on the left and right back support arms 151 are fixed, respectively, so that the relative positions of the left and right back support arms 151 and the lower connecting member 157 are in close contact with each other. The strength of the backrest support 9 is ensured together with the support.

  In this embodiment, the cover member 181 and the lower connecting member 157 are positioned effectively and the lower connecting member 157 is preferably covered. In this embodiment, the cover member 181 has a U-shaped cross-sectional shape having an open portion in front. The cover member 181 covers the bent portion 157a and the standing wall portion 157b on the rear side of the lower connecting member 157.

  In particular, it is assumed that the mounting strength is not easily affected by the load applied to the back support arm 151, and in this embodiment, the close contact surface 181a positioned on the lower surface of the cover member 181 is provided in the lower connecting member 157 in order to always realize a strong mounting state. The contact surface 181a and the pressure receiving surface 179a are fixed with screws from above in a state where the pressure receiving surface 179a is pressed and in close contact with the upward pressure receiving surface 179a.

  In particular, in the present embodiment, in order to effectively improve the strength against the load in the so-called torsional direction that is biased to the left or right with respect to the backrest support 9, a bent portion 157a is provided to form a metal lower connecting member 157. Is bent in an L shape in a side sectional view. That is, by making the shape of the lower connecting member 157 itself strong against twisting, the torsional rigidity of the backrest support 9 itself is effectively improved.

  In the present embodiment, the back support arm 151 is provided with a shaft mounting portion 167 that is a shaft end cover portion that covers the end portion 165 of the rotating shaft end portion 165 of the support shaft 37 that protrudes from the support base portion 3 to the left and right. The movable part and the fixed part are each covered by a single back support arm 151 to further reduce the number of parts.

  The back support arm 151 is preferably subjected to the load applied to the backrest 11, and the backrest 11 is indirectly supported by the support base 3 without the back support arm 151 interfering with the seat 7 or other components. Therefore, in the present embodiment, the back support arm 151 includes a front-rear direction extending portion 159 extending in the front-rear direction and a standing portion 161 extending continuously upward from the rear end of the front-rear direction extending portion 159. It is assumed that the backrest 11 is supported by the upright portion 161 as an approximately square shape.

  In this embodiment, the rear link 41, which is a seat support projection for supporting the seat 7 on the back support arm 151, is provided in order to realize a back seat synchro-rocking mechanism with a simple configuration while effectively reducing the number of parts. It is assumed that it is integrally molded.

  In particular, in the present embodiment, the operation of the rear link 41 is provided so that the seat receiver 5 rises as the backrest 11 is tilted backward, thereby realizing a weight-sensing back seat synchro-rocking mechanism with a simple configuration. ing. Specifically, in such a configuration, the rear link 41 is integrally formed so as to support the seat 7 in a state where the back link 41 is inclined forward with the backrest 11 standing.

<< Modification 1 >>
Below, each modification concerning this embodiment is described. In each modification, the same reference numerals are given to the components corresponding to the components of the above embodiment, and the detailed description thereof is omitted.

  In the above embodiment, as shown in FIG. 9 and the like, the end 189 of the cover member 181 is set to have a shape that can be closely attached, but by using this end 189, the left and right back support arms 151 can be connected to each other. Positioning can be performed more reliably.

  That is, as shown in FIG. 26, an elastic claw 189a that extends further from the end 189 of one cover member 181 to the front end side is integrally formed, and the other cover member 181 has the elastic claw 189a against the elastic clog 189a. Further, a claw receiving hole 189b that can be elastically engaged may be provided.

  If this is the case, the left and right end portions 189 are surely closely attached to each other and are not allowed to be separated from each other during assembly. Therefore, the assembling work can be further facilitated.

<< Modification 2 >>
Further, as in Modification 2 shown in FIG. 27, a protrusion 189c extending in a letter-like shape as viewed from the side is provided from the end 189 of one cover member 181, and the end of the other cover member 181 is provided. It is good also as what provided the slot 189d which can accommodate the said protrusion 189c in 189, while the protrusion 189c fits closely.

  In such a case, the left and right end portions 189 are accurately positioned with respect to each other. Further, since the protrusions 189c and the slots 189d are closely fitted, it is difficult to separate them after assembly due to mutual friction, and the assembly work of the back support arm 151 is easy as in the first modification. It has become a thing.

  The present invention is not limited to the embodiment described in detail above.

  For example, in the above-described embodiment, the lower connecting member is bent into a dogleg shape in order to increase the torsional rigidity of the connecting member, but may be formed in a cylindrical shape, a partial circle shape, or a wave shape in a side view. That is, various embodiments can be realized as long as they are curved or bent in a side view. In the above embodiment, the present invention is applied to a chair having a weight sensing type synchro-rocking mechanism that raises the seat as the back leans backward. Of course, after a backrest that is often used in offices. The present invention may be applied to a chair having a synchro-rocking mechanism of a type in which the seat is lowered with inclination. Further, the member covered by the back support arm may serve as a cover for various components other than those described above.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The present invention can be used as a chair configured so that the backrest can be tilted backward.

3 ... support base 7 ... seat 11 ... backrest 37 ... support shaft 39 ... seat support protrusion (rear link)
151 ... Back support arm 155 ... Back support bracket 157 ... Connecting material (lower connecting material)
157a ... Bent part 159 ... Front / rear direction extending part 161 ... Standing part 165 ... End part 167 Shaft end cover part (shaft mounting part)
175 ... Bush 179a ... Upward surface (pressure receiving surface)
181 ... Cover member

Claims (11)

The left and right back support brackets, whose rear ends are connected by a connecting material, are supported by a support base via a support shaft, and rotate together with the back support bracket at both ends of the support shaft that protrude outward from the back support bracket. A chair that supports the left and right back support arms and supports the backrest with this back support arm,
A chair that covers the support shaft, the back support bracket, and the connecting member by attaching the left and right back support arms from the left and right outside of the back support bracket.   The chair according to claim 1, wherein the back support arm is a strength member that supports the backrest so that the backrest can be tilted backward, and a cover member that covers the connecting member is integrally formed.   The chair according to claim 1 or 2, wherein the left and right back support arms each have the cover member, and the cover member and the connecting member are fixed. The chair according to claim 2 or 3, wherein the cover member has a U-shape facing forward in a sectional view and covers a rear surface of the connecting member.   The chair according to claim 2, 3 or 4, wherein the cover member is fixed to the cover member in a state where the cover member is in close contact with the connection member. The chair according to claim 1, 2, 3, 4 or 5, wherein the connecting member is bent in a side sectional view. The chair according to claim 1, 2, 3, 4, 5, or 6, wherein the back support arm has a shaft end cover portion that covers a rotating shaft end portion protruding left and right from the support base portion.   The support arm has a substantially U-shape in a side view including a front-rear direction extending part extending in the front-rear direction and a standing part continuously extending upward from the rear end of the front-rear direction extension part. The chair according to claim 1, 2, 3, 4, 5, 6 or 7, wherein a backrest is supported by the upright portion. The chair according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the back support arm integrally forms a seat support protrusion for supporting the seat. The chair according to claim 9, wherein the seat support protrusion is raised as the backrest tilts backward. The back support arm has a shaft end cover portion that covers a rotation shaft end portion protruding left and right from the support base,
The chair according to claim 10, wherein the seat support protrusion is a link that protrudes forwardly from the shaft end cover portion and supports the seat.

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