JP6627444B2 - Chair - Google Patents

Description

  The present invention relates to a chair suitably used in an office or the like.

  2. Description of the Related Art Conventionally, a chair provided with a back frame that performs a backward tilting operation about a main shaft provided on a support base is known (for example, see Patent Literature 1).

  In a conventional general back frame, left and right side frame portions are structurally connected by at least an upper erection member and a lower erection member, and a frame-like portion surrounded by these is formed. And the lower frame part which supports this frame-shaped part is extended downward and forward. In such a case, the frame-shaped portion is separate from the lower frame portion, and is fixed to the lower frame portion by bolts, welding, or the like.

  In the case of the back frame as described above, the number of parts that need to be formed by the mold has to be increased, and the degree of freedom of design for obtaining a suitable appearance and a structure that is easy to assemble is limited. Had become something.

JP 2010-252893 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a chair having a back frame which has an excellent degree of freedom in design for obtaining a suitable appearance and a structure which is easy to assemble.

  That is, the present invention has the following configuration.

The invention according to claim 1 is a chair provided with a back frame that performs a backward tilting operation about a main shaft provided on a support base, wherein the back frame includes left and right side frame portions and a backrest surface. An upper frame portion disposed on an upper back side and connecting upper end portions of the left and right side frame portions to each other; and a front portion continuously extending forward from a lower end portion of the left and right side frame portions , and a front portion is near the support base portion. And the left and right side frame portions are each formed to have a shape that gradually widens downward and are structurally connected only by the upper frame portion. It is those which are the side frame portions of the left and right, the upper frame portion, and, only the lower frame portion of the right and left, are integrally molded of a synthetic resin, to form a portion forming a front view down U shape A chair.

The invention according to claim 2 is the chair according to claim 1, wherein the left and right side frame portions are respectively disposed on the back side of the backrest surface.

The invention according to claim 3 is the chair according to claim 1 or 2, wherein the left and right side frame portions are shaped like a letter in a side view and a front view, respectively.

According to a fourth aspect of the present invention, the left and right side frame portions are formed by connecting an upper frame portion inclined rearward in a side view and a lower frame portion inclined forward in a side view via a bent portion. 4. The chair according to claim 1, 2 or 3.

The invention according to claim 5 is the chair according to claim 1, 2, 3, or 4, wherein the side frame portion and the lower frame portion are continuous so as to form an S-shape in side view.

The invention according to a sixth aspect is the chair according to the first, second, third, fourth, or fifth aspect, wherein the front end of the lower frame portion includes a portion capable of accommodating the end of the main shaft.

  As described above, according to the present invention, it is possible to provide a chair having a back frame that has an excellent degree of freedom in design for obtaining a suitable appearance and a structure that is easy to assemble.

The perspective view showing one embodiment of the present invention. The front view in the embodiment. The rear view in the embodiment. The right view in the embodiment. The left view in the embodiment. The top view in the embodiment. The bottom view in the embodiment. The partial enlarged left side view in the same embodiment. FIG. 4 is a partially enlarged left side view illustrating the positioning mechanism of the embodiment. FIG. 4 is a partially enlarged left side view illustrating the positioning mechanism of the embodiment. Exploded perspective view in the same embodiment. Exploded perspective view in the same embodiment. Exploded perspective view in the same embodiment. Exploded perspective view in the same embodiment. The front view in the embodiment. Exploded perspective view in the same embodiment. FIG. 4 is a partially enlarged rear view of the front frame in the same embodiment. XX sectional drawing in FIG. Exploded perspective view in the same embodiment. Exploded perspective view in the same embodiment. FIG. 5 is a sectional view taken along line U-U in FIG. 4. Exploded perspective view in the same embodiment. The front view which shows the lumbar support of the embodiment. The rear view which shows the lumbar support of the embodiment. The right view which shows the lumbar support of the embodiment. FIG. 16 is a sectional view taken along line YY in FIG. 15. FIG. 17 is a sectional view taken along line ZZ in FIG. 15. The perspective view in the embodiment. The perspective view in the embodiment. Exploded perspective view in the same embodiment. The top view in the embodiment. The top view in the embodiment. The top view in the embodiment. FIG. 5 is a sectional view taken along line VV in the same 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 A suitably used in an office or the like.

  The chair A includes a leg B, a support base C pivotally supported by the leg B, a seat D disposed on the support base C, and a support that can tilt backward with respect to the support base C. And the armrest P attached to the seat D. The backrest structure F includes a back support G rotatably supported by the support base C and a backrest H supported by the support base C via the back support G so as to be capable of tilting backward. Have been.

  Hereinafter, each configuration of the chair A will be described in detail.

<< Leg B >>
The leg B includes a plurality of radially arranged leg blades b1 each having a caster b3 at a distal end, and a leg support b2 provided upright at a base end of the leg blades b1. The leg support b2 has a gas spring (not shown) that can expand and contract in the vertical direction, and supports the support base C so that the position of the support base C can be changed vertically.

<<< Support base C >>>
The support base C mainly includes a main frame c1 having a frame shape in a plan view. The main frame c1 includes left and right side block portions c2, a front block portion c3 connecting the front ends of the left and right side block portions c2, and a rear block portion c4 connecting the rear ends of the left and right side block portions c3. It has.

  A main shaft j1 extending in the left-right direction is penetrated in the side block portion c2. The back support G is rotatably supported by the support base C via the main shaft j1.

  The front block part c3 is provided with a bearing part c5 of the front link shaft j2 arranged in a left and right pair. The bearing portion c5 of the front link shaft j2 projects upward.

  The rear block portion c4 includes a cylindrical portion c6 fixed to the leg support b2, and a rear wall c7 provided at a rear portion of the cylindrical portion c6. The rear wall c7 forms a receiving member N of the rearward tilt locking mechanism I described later, and the rear wall c7, which is the receiving member N, has a plurality of concave engaging portions c8 that are opened rearward. Are provided at intervals in the vertical direction.

<< Seat D >>
The seat D includes a seat receiver d1 having a shell shape, and a seat body d2 provided on the seat receiver d1 so as to be able to change the front-rear position. The front part of the seat D is supported via a front link c9. C, and the rear portion is supported by the support base C via a rear link g4 of the back support G. The seat support d1 has a front bearing portion d3 on its lower surface for holding a front connecting shaft j3 extending in the left-right direction supported by the upper end of the front link c9, and a left-right direction penetrating the rear link g4. A rear bearing portion d4 for holding the extended rear connection shaft j4 is provided. Note that an armrest P is attached to the seat d1.

  The seat D is configured to move in synchronization with the backward tilting operation of the backrest H by the locking mechanism J. The seat support d1 is provided with an operation lever d5 for rearward locking for operating the rearward locking mechanism I, and an operation lever d6 for raising and lowering for operating the gas spring of the leg B.

<< Back support G >>
The back support G includes left and right arms g1 rotatably supported by a main shaft j1 via a bush g3, and a mounting plate g2 rigidly connecting the rear ends of the arms g1. The back support G is made of metal, and the arm g1 and the mounting plate g2 are joined by welding.

  The left and right arms g1 are a pair of plates extending in the front-rear direction and have a shaft hole a1 at an intermediate portion in the front-rear direction. The left and right arms g1 are rotatably supported by the main shaft j1 via a bush g3 mounted on the shaft hole a1.

  The bush g3 is formed of a synthetic resin, has a cylindrical shape having a flange portion g5 on the outer periphery of an inner end, and is mounted from inside to a shaft hole a1 provided in the arm g1. In the mounted state, the flange g5 of the bush g3 is in contact with the inner surface of the arm g1. Note that a positioning projection g6 is provided on the outer surface of the flange g5 so as to project therefrom, and the positioning projection g6 is fitted into a positioning hole a2 provided in the arm g1.

  In the vicinity of the shaft hole a1 at the upper edges of the left and right arms g1, a rear link g4 extending diagonally forward and upward is integrally formed. A shaft hole g41 is formed at an upper end portion of the rear link g4, and a rear connection shaft j4 extending in the left-right direction is penetrated. Both ends of the rear connecting shaft j4 are engaged with the rear bearing d4 of the seat receiver d1. A receiving shaft j5 is provided between the front ends of the left and right arms g1, and the backrest H is turned forward between the receiving shaft j5 and the front end of the support base C via a back support G. A reaction force mechanism E for urging the movement is provided. Here, reference symbol E is a coil spring constituting the reaction force mechanism E.

  The mounting plate g2 is provided with a plurality of bolt insertion holes h1 for inserting the plurality of bolts v1. A nut (not shown) is provided on the lower surface side of each bolt insertion hole h1. In addition, a wire insertion for inserting an operation force transmitting wire w provided between a rearward locking operation lever d5 provided on the seat D and a rearward locking mechanism I described later is inserted through the mounting plate g2. A hole e1 is formed.

<< Backrest H >>
The backrest H is provided on a back frame 1, a concealing member 2 provided at the front end of the back frame 1, a front back frame 3 arranged on the front side of the back frame 1, and stretched on the front back frame 3. A tension member 4, a lumbar support 5 positioned on the back side of the tension member 4 and attached to the front back frame 3, and the lumbar support 5 and the front back frame 3 supporting the tension member 4 are attached to the back frame 1. And a positioning mechanism 6 for positioning so that the position can be changed in the front-rear direction.

  The backrest H has a front frame 3 on which a tension member 4 is provided on the front side of the back frame 1 so as to be changeable in the front-rear direction. With such a configuration of the backrest H, the front back frame 3 is easily made to have a structure that is easily elastically deformed as a whole, and the front back frame 3 is provided with flexibility to wrap the back of the seated person. It is easy. The entire backrest H can perform a backward tilting operation around a main shaft j1 provided on the support base C. Specifically, the backrest H is rotatably supported around a main axis j1 of the support base C via a back support G.

<Spine frame 1>
The back frame 1 performs a backward tilting operation around a main shaft j1 provided on the support base C, and is provided between the left and right side frame portions 1a and the upper ends of the left and right side frame portions 1a. The frame portion 1b, the left and right lower frame portions 1c extending forward from the lower ends of the left and right side frame portions 1a, respectively, and these left and right lower frame portions 1c are joined together and fastened to the mounting plate g2 of the back support G. And a lower connecting portion 1d. The left and right side frame portions 1a, the upper frame portion 1b, the left and right lower frame portions 1d, and the lower connecting portion 1d are integrally formed of synthetic resin.

  The left and right side frame portions 1a of the back frame 1 each have a shape of a member that gradually widens downward. The side frame portion 1a of the back frame 1 is disposed on the back side of the side of the backrest surface mainly constituted by the tension member 4 stretched on the front back frame 3. Each of the left and right side frame portions 1a has a substantially rectangular shape in a side view and a front view, and connects the upper frame portion 11 and the lower frame portion 13 via the bent portion 12. It is made continuous. In the standing state, the upper frame portion 11 is inclined rearward in a side view, and the lower frame portion 13 is inclined forward in a side view.

  The upper frame portion 1b of the back frame 1 is disposed on the upper back side of the backrest surface, and is a structural frame that connects the upper ends of the side frame portions 1a. The upper frame portion 1b is provided with an element constituting an upper connecting portion for attaching an upper end portion of the front back frame 3. That is, a plurality of concave portions 14 opening forward are provided on the front surface of the upper frame portion 1b at intervals in the left-right direction. A bolt insertion hole h2 communicating with each recess 14 is provided on the bottom surface of the upper frame portion 1b.

  The left and right lower frame portions 1c of the back frame 1 are continuous with the left and right side frame portions 1a, and the front portion extends from the lower ends of the left and right side frame portions 1a to a position corresponding to the main axis j1. That is, the left and right lower frame portions 1c are partially located outside the left and right arms g1 in the back support G. In other words, the left and right lower frame portions 1c extend in the front-rear direction, and the front end portions extend to both sides of the support base C disposed below the seat D.

  The left and right lower frame portions 1c have, at the front thereof, concave portions 15 which are open to the front and inside, and into which both ends of the main shaft j1 are inserted. The recess 15 constitutes a portion for accommodating the main shaft j1. A recessed step 15c is formed on the opening end face on the front end side of the recess 15. A plurality of wall-shaped mounting ribs 15a externally fitted to the bush g3 are provided inside the recessed portion 15 at intervals in the left-right direction. Each mounting rib 15a is provided with a cutout 15b that can receive the bush g3 from the front side.

  The left and right lower frame portions 1c have a curved shape so as to gradually rise rearward in a side view. Further, the left and right lower frame portions 1c are in a rearwardly inclined form in a side view. The left and right lower frame portions 1c are provided with bearing projections 16 having shaft holes a3 forming the positioning mechanism 6 on the upper surface side of the rear portions.

  The lower connecting portion 1d of the back frame 1 is for rigidly connecting the left and right lower frame portions 1c to each other, and includes an upper plate portion 17 disposed on a mounting plate g2 of the back support G, and an upper plate portion And a back plate portion 18 hanging down from a lower edge of the lower plate 17. The upper plate portion 17 is provided with a plurality of bolt insertion holes h3, and a bolt v1 inserted through the bolt insertion holes h3 from above is screwed to a nut (not shown) on the mounting plate g2 side to thereby form the back frame 1. Can be fixed to the back support G. The lower connecting portion 1d has an upper plate portion 17 through which a wire w for transmitting an operating force provided between an operation lever d5 for rearward tilt lock provided on the seat D and the rearward tilt lock mechanism I is inserted. The wire insertion hole a4 is formed.

  The side frame portion 1a and the lower frame portion 1c that constitute the back frame 1 are integrally continuous so as to form an S shape in a side view. The lower frame portion 13 and the lower frame portion 1c of the side frame portion 1a have a U-shape in a side view, and the side frame portion 1a and the lower frame portion 1c are integrally connected via a bent portion 19. are doing.

  The side frame portion 1a and the bent portion 19 have a substantially rectangular shape in cross section, and are formed so that the front side faces obliquely inward and the rear side faces obliquely outward. . That is, the side frame 1a and the bent portion 19 have an inwardly inclined surface m1 that is inclined inward on the front side, and an outwardly inclined surface m2 that is inclined outwardly on the back side. .

  The left and right side frame portions 1a of the back frame 1 described above are structurally connected only by the upper frame portion 1b. That is, the side frame portion 1b and the lower frame portion 1c (hereinafter, the side frame portion 1b and the lower frame portion 1c are collectively referred to as a "side frame") integrally and vertically continuous in a front view and a rear view. , And a pair of left and right side frames (1b, 1c) are integrally connected by an upper frame portion 1b. That is, the upper frame portion 1b and the left and right side frames (1b, 1c) form a downward U-shaped portion as viewed from the front. In this embodiment, the left and right side frames (1b, 1c) are integrally connected by a lower connecting portion 1d, but the lower connecting portion 1d may be separate.

<Hiding member 2>
The concealing member 2 is disposed on the front side of the lower frame portion 1c in the back frame 1, and closes the front side of the concave portion 15 of the lower frame portion 1c. More specifically, the concealing member 2 is made of a synthetic resin, and has a plate-shaped concealing member main body 21 and protrudingly provided on an inner surface of the concealing member main body 21 and directly or directly on the main shaft j1 in the concave portion 15. And a mounting arm 22 that is indirectly involved. In this embodiment, the mounting arm 22 is indirectly engaged with the main shaft j1 via the bush g3, and can be fitted onto the bush g3 by utilizing the elastic deformation of the member.

  The concealing member main body 21 has a shape slightly curved so as to protrude toward the front side, and is set to have a size that fits into the recessed step 15 c of the recessed portion 15 of the back frame 1. The concealing member main body 21 is set to have such a thickness that, when fitted to the recessed step portion 15c, its outer surface is substantially flush with the outer surface of the lower frame portion c1 around the recessed portion 15.

  The mounting arm 22 is a plate-shaped one protruding rearward from the concealing member main body 21 and fitted to the bush g3 while being inserted into the gap sm formed between the mounting ribs 15a of the concave portion 15. It is. Each mounting arm 22 has a cutout portion 23 that opens rearward and can receive the bush g3 from the front side. The notch portion 23 has an opening width w1 at the back set to a value substantially equal to the outer diameter of the bush g3, and an opening width w2 at the opening end side set to a value smaller than the outer diameter of the bush g3. Therefore, when these mounting arms 22 are pushed into the recessed portions 15 of the lower frame portion 1c, the distal ends of the mounting arms 22 are temporarily elastically deformed outward, and then are fitted to the bush g3. In the mounted state, the concealing member main body 21 is stably held by the recessed step 15c. In a state where the concealing member 2 is mounted on the concave portion 15 of the back frame 1, the mounting rib 15a of the concave portion 15 and the mounting arm 22 of the concealing member 2 are positioned in the axial direction of the main shaft j1, that is, in the left-right direction. Are different from each other.

  In the concealing member 2 having the above configuration, when the back frame 1 is rotated by the backward tilting operation or the like, the outer edge of the concealing member main body 21, that is, mainly the upper and lower edges are engaged with the recessed step portion 15c of the back frame 1. , And can rotate integrally with the back frame 1.

<Front back frame 3>
The front back frame 3 has an upper end and a lower end supported by the back frame 1 via connecting portions. The front back frame 3 has a continuous frame shape when viewed from the front, and a backrest surface is formed by the tension member 4 so as to substantially match the shape of the frame. The front back frame 3 is configured to be able to take a front position (f) and a rear position (r) by a positioning mechanism 6 described later. The front back frame 3 includes a frame body K and a plate L attached to the frame body K. The front and back frames 3 are made of a material and a shape so as to be easily deformed as compared with the back frame 1, and have a protruding portion 32 that protrudes most forward at an intermediate portion thereof. The front back frame 3 has a side frame portion 3a, which is a substantially U-shaped frame in side view.

  The frame body K has a continuous frame shape formed of a synthetic resin, and includes left and right side frame portions 3a, an upper frame portion 3b provided between upper ends of the left and right side frame portions 3a, A lower connecting frame portion 3c provided between lower ends of the side frame portions 3a.

  The left and right side frame portions 3a of the front back frame 3 are provided with mounting grooves mz for fixing the band-shaped member 41 as an edge of the tension member 4 on the outer surface, and the upper frame portion 31 inclined rearward in a side view. In the side view, the lower frame portion 33 that is inclined forward is connected to the front frame via the projecting portion 32 that projects most forward. A bearing projection 35 having a shaft hole a6 constituting the positioning mechanism 6 is protruded from a lower end portion of the left and right side frame portions 3a.

  The upper frame portion 31 constituting the side frame portion 3a is set to have a structure that is more flexible than the lower frame portion 33. In other words, the upper frame portion 31 is configured to be easily elastically deformed rearward with the protruding portion 32 located at the upper end of the lower frame portion 33 as the center of rotation.

  The lower frame portion 33 constituting the side frame portion 3a is formed so as to be gradually displaced inward downward. In other words, the left and right lower frame portions 33 are arranged so as to form a lower constriction in which the distance between the lower frame portions 33 gradually decreases downward. The front surface of the lower frame portion 33 is provided with a groove-shaped concave portion a5 for positioning the lumbar support 5.

  The upper frame portion 3b of the front back frame 3 is integrally provided between the upper ends of the left and right side frame portions 3a, and has a curved shape so as to protrude rearward. The upper frame portion 3b is provided with an element constituting an upper connection portion for attaching the upper end portion of the back frame 1. That is, a projection 36 is formed on the back surface of the upper frame portion 3b so as to fit into each of the concave portions 14 of the back frame 1. Each projection 36 is provided so as to protrude rearward, and has a vertical screw hole h4. These projections 36 are fitted into the recesses 14 of the back frame 1, and then the bolts v4 inserted from below into the screw holes h4 are screwed into the upper frame portions 3b of the front back frame 3. Are fixed to the upper frame portion 1b of the back frame 1. A mounting groove mz for fastening the tension member 4 is provided on the upper surface of the upper frame portion 3b, and both ends are continuous with the mounting groove mz of the side frame portion 3a.

  The lower connecting frame portion 3c of the front back frame 3 is provided between the lower end portions of the left and right side frame portions 3a, and has a curved shape so as to project rearward in plan view. The lower connection frame portion 3c is provided with a plurality of boss portions n1 having screw holes for mounting the plate L on the front surface thereof at intervals in the left-right direction.

  The plate L is attached to substantially the entire front surface side of the lower connection frame portion 3c in the frame body K and a part of the front surface side of the side frame portion 3a. Can be supported. The plate L includes a plate body 3d that covers the front surface of the lower connection frame 3c, and both ends 3e provided integrally on both sides of the plate body 3d.

  The plate body 3d includes a front wall 37 whose upper part is in contact with an upper part of the front surface of the lower connection frame part 3c, and a rear wall 38 which is in contact with a lower part of the front surface of the lower connection frame part 3c. .

  The lower portion 37b of the front wall 37 is spaced apart from the front side of the rear wall 38. A mounting groove mz which is opened downward is formed between the rear wall 38 and the lower portion of the front wall 37, and the lower edge 41 of the tension member 4 is mounted in the mounting groove mz. .

  Near the boundary between the upper portion 37a and the lower portion 37b of the front wall 37, a bolt holding portion h5 corresponding to the boss portion n1 of the lower connecting frame portion 3c is formed. Further, a portion corresponding to the bolt holding portion h5 in the lower portion 37b of the front wall 37 is cut out downward so as to screw the bolt v5 to the boss portion n1 of the lower connection frame portion 3c through the bolt holding portion h5. A cutout portion 37c is provided.

  Both end portions 3e face the front surface of the lower end portion of the side frame portion 3a via the gap sk. In other words, a gap sk for attaching the lumbar support 5 is formed between the back surface of the both end portions 3e and the front surface of the side frame portion 3a of the front back frame 3.

  Both ends 3e are provided with claw members 39 which are engaging elements for holding the lumbar support 5. At both ends 3e, a slit s1 having an upward U-shape is formed, and a portion surrounded by the slit s1 is a claw member 39 which can be elastically deformed in the thickness direction. These claw members 39 are provided with a projection (not shown) elastically engaged with the claw receiving portions 57 of the lumbar support 5 on the back side thereof.

<Tension member 4>
The tension member 4 is formed by fastening a band-shaped member 41 to the periphery of a mesh-like cloth capable of forming a backrest surface by sewing or the like. The tension member 4 is tensioned on the front surface of the front frame 3 by engaging a band-shaped member 41 as an edge thereof with a mounting groove mz provided around the front frame 3.

  The tension member 4 is located in front of the lumbar support 5. For this reason, the tension member 4 in this embodiment can exert the function of restricting the movement of the lumbar support 5 to the front side with respect to the front back frame 3, that is, the function of preventing the lumbar support 5 from moving forward with respect to the front back frame 3. It has become.

<Lumbar support 5>
The lumbar support 5 is for mainly supporting the waist portion of the occupant from the back side. In this embodiment, the lumbar support 5 is retrofitted to the front back frame 3 on which the tension member 4 is provided. It is configured to be able to. Here, the term “retrofitting” does not mean mounting after the stage at which the chair A reaches the consumer, but more specifically, after the backrest H on which the tension member 4 is provided is configured. , Which means mounting after the tension member 4 is stretched on the front frame 3.

  The lumbar support 5 is disposed between the left and right side frame portions 3a of the front back frame 3 constituting the backrest H, and is provided at a lower portion of the front back frame 3 which is set to have relatively higher rigidity than other parts. Installed. In other words, both ends of the lumbar support 5 are attached to the lower frame portion 33 of the side frame portion 3a. The lower frame portion 33 is set to have relatively high rigidity, so that the lumbar support 5 does not easily come off even when receiving the weight of the occupant. That is, the lower frame portion 33 can stably support the lumbar support 5, and can appropriately exhibit the function as the lumbar support 5.

  The lumbar support 5 includes a curved plate-shaped lumbar support main body 5a that receives a load from a user, and mounting portions 5b provided at both ends of the lumbar support main body 5a, and is integrally formed of synthetic resin. ing.

  The lumbar support body 5a has a plate shape, and has a substantially horizontal band-shaped region 51 whose left and right ends are continuous with the mounting portion 5b, and an upper region 52 extending upward from the upper edge of the band-shaped region 51. It is made. Further, the lumbar support main body 5 a includes a lower region 53 extending downward from a lower edge of the band-shaped region 51.

  In other words, the lumbar support main body 5a is located at the middle part in the left-right direction and has a substantially horizontally elongated rectangular shape in front view, and diagonally downward and outward from the lower left and right corners of the main part 54, respectively. And a continuous portion 55 extending toward the front. At the extension end of the continuous portion 55, a mounting portion 5b formed in a strip shape in a front view is integrally provided. The band-shaped region 51 is constituted by a part of the main part 54 and a part of the continuous part 55. The upper region 52 mainly includes an upper portion of the main portion 54. The lower region 53 is constituted by a part of the continuous portion 55.

  The band-shaped region 51 is a portion that extends linearly in the left-right direction when viewed from the front, and the mounting portion 5b is provided integrally over the entire region at both ends. The band-shaped region 51 cooperates with the side frame portion 3a of the front back frame 3 and serves as a main portion for receiving the load of the occupant. 23 to 25, the band-shaped region 51 is shaded for easy understanding. The band-shaped region 51 connects the left and right mounting portions 5b in a straight line, and the lumbar support 5 as a whole has a strength for receiving the load of the occupant as a whole with these as main components.

  The upper region 52 is set to have a size and a shape such that spaces sp are formed between both side edges thereof and left and right side frame portions 3 a of the front back frame 3. In other words, the upper region 52 extends upward from the entire upper edge region of the belt-shaped region 51, and has a form in which the left-right width dimension gradually decreases upward. A space sp is formed between both side edges of the upper region 52 and the upper frame portion 31 of the side frame portion 3a. The upper region 52 is easy to bend rearward from the vicinity of the boundary with the belt-shaped region 51 as a base when receiving a load of a seated person.

  The upper region 52 is set so as to be arranged at a height position corresponding to the upper frame portion 31 of the front back frame 3, and is set to be more easily bent in the thickness direction than the belt-shaped region 51. In this embodiment, the upper region 52 has a hat shape in a front view in which the lower end portion is configured to be longer than the upper portion. The upper region 52 has a curved shape that, together with the band-shaped region 51, is convex rearward in plan view corresponding to the shape of the tension member 4. The upper region 52 is provided with two recessed portions 52a extending in the left-right direction at two upper and lower portions on the back side, and is configured to be easily bent in the thickness direction. The upper region 52 has a shape in which an upper edge portion is warped rearward in a side view. That is, the upper region 52 is provided with the rear warp portion 52b at the upper end.

  The lower region 53 extends downward from the lower edge of the belt-shaped region 51. The lower region 53 is provided between the vicinity of both ends of the lower edge of the belt-shaped region 51 and the mounting portion 5b. The lower region 53 has a role of securing the mounting strength between the band-shaped region 51 and the mounting portion 5b.

  The attachment portions 5b are provided at both ends of the lumbar support main body 5a, and are attached to the lower frame portion 33 of the side frame portion 3a and both ends 3e of the plate L. The attachment portion 5b is an elongated plate-shaped member extending below the band-shaped region 51 and the lower region 53 along the lower frame portion 33, and has a rib-shaped rearwardly projecting portion 56 on the back surface thereof. The lower end is provided with a square hole-shaped claw receiving portion 57 with which the claw member 39 of the plate L is engaged.

  The mounting portion 5 b is arranged between the front surface of the lower frame portion 33 of the front back frame 3 and the back surface of the tension member 4. The attachment portion 5b is attached to the front frame 3 with the tension member 4 stretched by moving the lumbar support 5 from the rear side. That is, the lumbar support 5 is pressed from behind the backrest H against the back surface of the tension member 4, and the mounting portion 5 b of the lumbar support 5 is inserted between the tension member 4 and the frame body K. I do. With this operation, in the final stage, the protrusion 56 of the mounting portion 5b fits into the recessed portion a5 of the lower frame portion 33, and at the same time, the claw receiving portion 57 of the mounting portion 5b is The gap sk between the portion 33 and both ends 3e of the plate L is interrupted, and the claw member 39 of the plate L is engaged. In this manner, the mounting portion 5b is located between the lower frame portion 33 and the tension member 4, and the protruding portion 56 and the recessed portion a5 are engaged with the claw receiving portion 57 and the claw member 39, respectively. In this state, the lumbar support 5 is attached to the front back frame 3 so as not to come off. In other words, the protrusion 56 and the recessed part a5 constitute a separation preventing element, and the claw receiving part 57 and the claw member 39 constitute an engaging element.

  The detachment preventing element is for receiving a load applied to the lumbar support 5, and is provided between the mounting portion 5b and the front back frame 3 as a frame. In this embodiment, the disengagement preventing element is constituted by a concave portion a5 extending along the longitudinal direction of the front back frame 3 and a projecting portion 56 provided on the lumbar support 5.

  The engagement element is for attaching the lumbar support 5 to the front frame 3 as a frame by utilizing elastic deformation of the member. In this embodiment, the engagement element is constituted by a claw member 39 provided on the front back frame 3 and a claw receiving portion 57 provided on the lumbar support 5.

  In this embodiment, the position of the engagement element (39, 57) and the position of the disengagement prevention element (a5, 56) are separately provided. Then, the fixing when the lumbar support 5 is attached to the front back frame 3 is mainly performed by the engagement elements (39, 57), and the lumbar support 5 is attached to the load of the occupant after the lumbar support 5 is attached to the front back frame 3. The resistance is made to function mainly by the separation preventing elements (a5, 56). For this reason, the configuration of the mounting portion 5b and the front back frame 3 can be suitably provided separately for each function.

  The front frame 3 is attached to the connection between the front frame 3 and the back frame 1 holding the lumbar support 5 as described above, that is, the connection between the lower part of the front frame 3 and the back frame 1. And a positioning mechanism 6 capable of selectively positioning two different positions.

<Positioning mechanism 6>
The positioning mechanism 6 can select the position of the lower end portion of the front back frame 3 at the front position (f) or the rear position (r) and position it. It is configured so that it can be stably positioned at either the position (f) or the rear position (r).

  The positioning mechanism 6 includes left and right links 6 a and 6 b pivotally supported so as to be able to rotate in the front-rear direction with respect to the back frame 1, and a rotating end of the left and right links 6 a and 6 b of the front frame 3. And a tip shaft j7 which is a pivoting element pivotally connected to the lower end. The left and right links 6a and 6b can rotate only between a front position (a), which is a front dead center inclined forward, and a rear position (c), which is a rear dead center inclined backward. Is set.

  Between the front position (a) and the rear position (c) of the left and right links 6a, 6b, an intermediate position as a conceivable point where the direction of the rotational bias of the front back frame 3 on the left and right links 6a, 6b is reversed. (B) is set. In other words, the intermediate position (b) exists between the front position (a) and the rear position (c) in the left and right links 6a, 6b. The upper end portion of the front back frame 3 has the left and right links 6a, 6b in comparison with the amount of elastic deformation of the front back frame 3 when the left and right links 6a, 6b are at the front position (a) or the rear position (c). The front frame 3 is connected to the upper end of the back frame 1 so as to increase the amount of elastic deformation of the front frame 3 at the intermediate position (b).

  The positioning mechanism 6 is provided between a rearwardly inclined portion of the lower portion of the back frame 1 in a side view and a lower end portion of the front back frame 3. The positioning mechanism 6 includes left and right links 6 a and 6 b provided in the back frame 1 and arranged in a pair on the left and right, and the rotating ends of the left and right links 6 a and 6 b are connected to the lower end of the front back frame 3. It is provided with a tip shaft j7 as a pair of left and right pivoting elements pivotally connected to both side portions, and an operation lever 6c for directly rotating the left link 6a, which is one of the links.

  The left link 6a (located to the left in front view) is rotated in the front-rear direction by an operation force applied to the operation lever 6c, and includes an inner link member 61 and an outer link member 62. .

  The inner link member 61 has a lower portion in contact with the inner surface of the bearing protrusion 16 in the back frame 1 and an upper portion in contact with the inner surface of the bearing protrusion 35 in the front frame 3. The inner link member 61 includes a base shaft j6 inserted through the shaft hole a3 of the bearing protrusion 16 in the back frame 1 and a distal shaft serving as a pivoting element inserted through the shaft hole a6 of the bearing protrusion 35 in the front frame 3. j7. At an intermediate position of the inner link member 61, a bolt insertion hole h6 is formed.

  The outer link member 62 has a lower portion in contact with the outer surface of the bearing projection 16 in the back frame 1 and an upper portion in contact with the outer surface of the bearing projection 35 in the front frame 3. It has a base-side fitting hole a7 into which the penetrating end fits, and a distal-side fitting hole a8 into which the penetrating end of the distal shaft j7 fits. A spacer projection 63 is provided at an intermediate position between the outer link members 62 to keep the distance between the outer link members 62 and the inner link members 61 constant. The spacer projection 63 has a screw hole n2 into which the bolt v6 inserted through the bolt insertion hole h6 is screwed. That is, the inner link member 61 and the outer link member 62 are connected by screwing the bolt v6 into the screw hole n2.

  The spacer projection 63 has a front edge or a rear edge that can contact the front or rear surface of the bearing projection 16 in the back frame 1, and the left link 6 a moves from the front position (a) to the rear position ( It has a function of restricting the rotation range so that it can rotate only up to c). In this embodiment, as shown in FIGS. 9 and 10, the left link 6a at the front position (a) and the left link 6a at the rear position (c) are centered on the virtual center line ct on the base axis j6. It is set so that it can take a posture that is substantially symmetrically inclined.

  A prismatic boss portion h7 is provided on the outer surface of the proximal end portion of the outer link member 62 such that the axis coincides with the axis of the proximal-side fitting hole a7. The base end of the operation lever 6c is fitted to the boss h7, and is prevented from being removed from the boss h7 by a bolt v7. A ring member 6d is interposed between the periphery of the base end of the operation lever 6c and the outer link member 62. The operation lever 6c connected to the outer link member 62 can rotate integrally with the outer link member 62.

  The right link 6b (located to the right in front view) has a configuration similar to that of the above-described left link 6a, and the corresponding components have the same reference characters allotted and description thereof will not be repeated.

  The right link 6b is different from the left link 6a in that no operation lever is provided on the outer link member 62. Here, the front back frame 3 is operated at the lower end thereof, that is, at a portion between the left bearing protrusion 35 and the right bearing protrusion 35 in the front back frame 3 to directly operate the left link 6a by operating the operation lever 6c. The rigidity is such that the operating force when turned to the right can be transmitted to the right link 6b. Therefore, the operation force of the operation lever 6c attached to the left link 6a can be reduced without providing an operation lever on the right link 6b or providing a special mechanism for connecting the left and right links 6a, 6b. This is transmitted to the right link 6 b via the front frame 3.

  The operation related to the positioning mechanism 6 described above will be described as follows.

  As shown in imaginary lines in FIGS. 1, 4, 5 and 8 to 10, when the left and right links 6a, 6b are at the front position (a), the left and right links 6a, 6b It is urged in the forward leaning direction by receiving the elastic repulsive force from, and is stably held at the front position (a). In this state, the lower part of the front back frame 3 is held at a position away from the back frame 1 in a side view in a side view. In this state, when the operation lever 6c provided on the left link 6a is rotated backward, the left link 6a passes from the front position (a) through the intermediate position (b) to the rear position (c). As a result, the lower part of the front back frame 3 moves to a position where it partially covers the back frame 1 in a side view. At this time, the right link 6b follows the movement of the lower end portion of the front frame 3 and rotates from the front position (a) through the intermediate position (b) to the rear position (c). Become. The left and right links 6a and 6b rotate while elastically deforming the protruding portion 32 of the front back frame 3 so that the degree of bending of the protruding portion 32 increases, and a predetermined intermediate position as shown by a solid line in FIG. Beyond (b), the elastic repulsion force for the return of the protruding portion 32 of the front back frame 3 immediately thereafter acts as a force for rotating the left and right links 6a and 6b backward. The left and right links 6a, 6b which have received the elastic repulsive force of the front frame 3 are positioned and stably held when reaching the rear position (c) as shown by the solid lines in FIGS. Become.

  As shown by the solid line in FIG. 8, in a state where the left and right links 6a and 6b are held at the rear position (c), the rear edge of the side frame portion 3a of the front frame 3 It moves to a position where it covers the side frame portion 1a of the back frame 1 in side view, and is positioned. In other words, when the left and right links 6a and 6b are held at the rear position (c), the front and back frames are compared with the state where the left and right links 6a and 6b are held at the front position (a). The lower frame 3, that is, the side frame 3 a of the front frame 3, the lower connecting frame 3 c, and the plate L are close to the frame 1.

  In this embodiment, the upper end of the front back frame 3 is fixed to the back frame 1 by bolts v4. For this reason, when the left and right links 6a, 6b rotate from the front position (a) to the rear position (c), the upper end of the front back frame 3 becomes a rotation center, that is, a base end, and hardly moves. The lower end of the front frame 3 becomes a rotating end and moves rearward. The height position of the rotating end when the left and right links 6a and 6b are at the front position (a) and the height position of the rotating end when the left and right links 6a and 6b are at the rear position (c) are as follows. They are set to be almost the same.

  In this embodiment, when the front back frame 3 is at the front position (f), the lumbar support 5 supported by the front back frame 3 has the band-shaped region 51 located on the front side of the upper region 52, When the frame 3 is at the rear position (r), the upper region 52 is located on the front side of the belt-shaped region 51. In other words, the lumbar support 5 when the front back frame 3 is at the rear position (r) has a more inclined posture than when the front back frame 3 is at the front position (f).

  The positioning mechanism 6 sets the rotation range of the left and right links 6a and 6b, thereby setting the height position of the rotation end at the front position (a) and the height position of the rotation end at the rear position (c). If the left and right links 6a and 6b are at the front position (a) and the rear position (c), the relative position between the side frame portion 3a of the front back frame 3 and the lumbar support 5 is different. Can be changed. That is, in the state where the left and right links 6a and 6b are at the front position (a) and the state where the left and right links 6a and 6b are at the rear position (c), the side view shape of the front back frame 3 is made different. Can be done. Specifically, the relative angle between the upper frame portion 31 and the lower frame portion 33 of the side frame portion 3a constituting the front back frame 3 (that is, the degree of bending of the protruding portion 32) changes, and The relative position between the upper region 52 of the lumbar support 5 supported by the portion 33 and the upper frame portion 31 changes. That is, the lumbar support 5 is attached at a position where the relative position of the upper region 52 with respect to the upper frame portion 31 changes with the deformation of the side frame portion 3a of the front back frame 3.

  For example, the relative angle between the upper frame portion 31 and the lower frame portion 33 in a state where the left and right links 6a, 6b are positioned at the rear position (c) is determined by setting the left and right links 6a, 6b to the front position (a). It is also possible to make the relative angle between the upper frame portion 31 and the lower frame portion 33 in the state of being positioned at a larger angle. That is, by rotating the left and right links 6a, 6b from the front position (a) to the rear position (c), the lumbar support 5 performs a forward tilting operation, and the upper region 52 of the lumbar support 5 is moved. , Will be relatively close to the upper frame portion 31 in side view. When the left and right links 6a, 6b are at the rear position (c), the upper region 52 of the lumbar support 5 is tighter in a no-load state than when the left and right links 6a, 6b are at the front position (a). It will approach the back side of the member 4.

<< Backward tilt lock mechanism I >>
The backward tilt lock mechanism I is for locking the backrest H at a desired backward tilt position, and is provided between the back support G and the support base C in this embodiment.

  The backward tilt lock mechanism I includes a lock unit M which is a main part of the rear tilt lock mechanism I on the back support G side, and the engaging member 7 of the lock unit M is selectively engaged on the support base C side. Receiving member N having a plurality of engaging portions c8.

  The lock unit M is a lock position (h) at which the backrest structure F (the back support G and the backrest H) prohibits the backward tilt operation with respect to the support base C, or a free position that allows the backrest structure F to tilt backward. An engagement member 7 that can take a position (i), a drive mechanism 8 that drives the engagement member 7 between a lock position (h) and a free position (i), and a drive mechanism 8 and an engagement member 7 And a supporting member 9 for supporting the above.

  The lock unit M has a plurality of parts assembled and assembled on the support member 9. In the manufacturing stage of the chair A, the lock unit M is assembled on an independent specific manufacturing line, and the operation is independently checked on the manufacturing line. Can be done. In other words, the lock unit M is a package in which the engagement member 7 and the drive mechanism 8 are held by the support member 9 as a base body, and is configured to be applicable to other chairs as it is. In the completion stage of the chair A, the first housing 9a constituting the support member 9 of the lock unit M is joined to the back support G by welding.

  Hereinafter, the configuration of the lock unit M will be described in detail.

  The engagement member 7 is a plate-like member having a substantially rectangular shape in a plan view and having an engagement protrusion 71 disposed on the distal end side. It is supported by. A long hole 72 extending in a direction orthogonal to the advance / retreat direction is formed in an intermediate portion of the engagement member 7. In the center of the rear edge of the engaging member 7, a projection 73 serving as a spring retainer for engaging the front end of the locking spring 81 is provided.

  The drive mechanism 8 relates a lock spring 81 that urges the engagement member 7 in the locking direction, that is, the direction of the engagement portion c8, and an operation force transmitted from the operation lever d5 for backward tilt locking via the wire w. And an operation conversion mechanism 82 for converting the force into a force for retracting the joint member 7.

  The locking spring 81 is of a compression coil type, and is interposed between the engagement member 7 and a rear wall 96 of a second housing 9b described later.

  The operation conversion mechanism 82 includes an operation arm 83 whose base end is rotatably supported by the second housing 9 b constituting the support member 9 and whose distal end is connected to the wire w. An unlocking spring 86 is provided in which an operation end 86 b that rotates with the rotation of the operation arm 83 is engaged with the elongated hole 72.

  The operation arm 83 is supported by a shaft j8 provided in the second housing 9b and rotates in the front-rear direction. A shaft hole a9 with which the shaft j8 of the second housing 9b is engaged is provided at a base end. And a wire connecting portion 84 for connecting the tip of the wire w to the rotating end. A spring mounting portion 85 for mounting a lock release spring 86 is provided at the base end of the operation arm 83. The unlocking spring 86 includes a spring body 86a wound in a coil shape, one coil end 86b extending from one end of the spring body 86a, and the other coil end 86c extending from the other end of the spring body 86a. In this embodiment, one coil end 86b forms an operating end 86b for biasing the engagement member 7. The spring mounting portion 85 is provided at a base end portion of the operation arm 83 to accommodate the spring body 86a in alignment with the axis of the shaft hole a9, and the spring body 86a accommodated in the notch 85a. And a coil end holding portion 85b for holding the other coil end 86c extending from the coil end 86c.

  The support member 9 is a basic structure for unitization so that a plurality of parts, that is, the engagement member 7 and the drive mechanism 8 can be collectively handled in the manufacturing stage of the chair A. It has a first housing 9 a that slidably supports the member 7 and a second housing 9 b that supports the drive mechanism 8.

  The first housing 9 a has a channel shape opened upward, and has a bottom wall 91, a front wall 92 extending upward from the front edge of the bottom wall 91, and a rear wall 91. And a rear wall 93 extending upward from the edge.

  The bottom wall 91 includes a window 91a for passing the operating end 86b of the unlocking spring 86, a housing mounting hole 91b for mounting the second housing 9b, and a back support G including a rearwardly inclined locking mechanism I. And a cover mounting hole 91c for mounting a cover g7 that covers the lower surface side of the rear portion of the cover. A slit s2 extending in the left-right direction is formed in the front wall 91, and the front end side of the engaging member 7 is held in the slit s2 so as to be slidable in the front-rear direction. A slit s3 extending in the left-right direction is formed in the rear wall 92, and the rear end side of the engaging member 7 is slidably held in the front-rear direction in the slit s3. That is, the engaging member 7 is held by the first housing 9a so as to be able to advance and retreat in the front-rear direction while penetrating the front wall 92 and the rear wall 93 of the first housing 9a.

  The second housing 9b is provided with a bottom wall 94, a side wall 95 extending upward from both left and right edges of the bottom wall 94, and a rear wall extending upward from the rear edge of the bottom wall 94. It has a wall 96 and a mounting collar 97 extending rearward from the upper edge of the rear wall 96.

  The bottom wall 94 has a cross-rib-shaped shaft j8 that pivotally supports the operation arm 83 of the drive mechanism 8 so as to be able to turn horizontally. That is, the operation arm 83 is rotatably attached to the second housing 9b by engaging the shaft hole a9 of the operation arm 83 holding the unlocking spring 86 with the shaft j8.

  The side wall 95 includes an upward edge 95a that contacts the lower surface of the bottom wall 91 of the first housing 9a, and a forward edge 95c for locking the rear end of the engaging member 7 at the free position (i). An elastic claw 95b that engages with the housing mounting hole 91b of the first housing 9a is projected from the upward edge 95a.

  The rear wall 96 includes a front wall portion 96a facing the front and an inclined wall portion 96b facing diagonally forward. The front wall portion 96a is provided with a spring retainer portion 96c for holding a rear end of the locking spring 81. ing. A window 96d is formed in the inclined wall portion 96b, and a mounting portion 96e for mounting one end of a tube t that holds the wire w is formed on a lower edge portion of the window 96d.

  The mounting flange 97 is in contact with the lower surface of the mounting plate g2 of the back support G, and includes a bolt insertion hole h8 in which a bolt v8 for fastening the second housing 9b to the mounting plate g2 is mounted. ing.

  In this embodiment, the first housing 9a is made of metal, and the second housing 9b is made of synthetic resin. The first and second housings 9b are arranged between the left and right arms g1 of the back support G.

  When the chair A is completed, the first housing 9a is connected to the left and right arms g1 by welding, and also functions as a strength member. Even after the chair A is completed, the second housing 9b containing the driving mechanism 8 is removed from the back support G and the first housing 9a by removing the bolt v8 and deforming the elastic claws 95b. You can do it.

  The engaging member 7 of the lock unit M configured as described above selectively engages with any of the plurality of engaging portions c8 of the receiving member N provided at the rear end of the support base C, and The backrest structure F can be locked at a desired backward tilt position.

  The receiving member N is a wall-shaped member that also serves as a rear wall c7 of the support base C, and includes a plurality of sets of engaging portions c8 spaced apart in the vertical direction. In this embodiment, the receiving member N includes a pair of left and right engagement portions c8 provided in the upper stage, a pair of left and right engagement portions c8 provided in the middle stage, and a pair of left and right engagement portions provided in the lower stage. And a joint c8. A pair of left and right engaging portions c8 provided at the upper stage is for locking the backrest H at the initial position shown in FIGS. 1 to 6, and is constituted by a concave stepped portion. The middle and lower engaging portions c8 are formed by recessed through holes.

  Next, the operation of the backward tilt lock mechanism I will be described.

  In a state where the wire w is not pulled by the operation lever d5 for locking backward, the operation arm 83 is held at the front position (j), and the engaging member 7 is moved forward by the urging force of the locking spring 81. Elastic biased. Therefore, when the engaging member 7 faces the engaging portion c8 of the receiving member N due to the rotation of the backrest H, the engaging member 7 moves forward, and the engaging portion c8 faces the engaging protrusion 71. Will be engaged. When the engagement protrusion 71 is engaged with the engagement portion c8, the backrest H cannot be tilted backward.

  When the operation to release the lock is performed by pulling the wire w by the operation lever d5 for locking the backrest from the state where the backrest H is locked rearward, the operation force is applied via the wire w. This is transmitted to the operation arm 83, and the operation arm 83 rotates rearward, that is, toward the rear position (k). As the operation arm 83 rotates rearward, the operation end 86b of the unlocking spring 86 also moves rearward, and the engaging member 7 retreats to cause the engaging protrusion 71 to engage with the engaging portion c8. The engagement is released. When the engagement between the engagement protrusion 71 and the engagement portion c8 is released, the backrest H can be freely tilted backward. At this time, the operation lever d5 for the backward tilt lock can be fixed in a state where the wire w is pulled, and in this case, the seated person can freely move the backrest H rearward by his own load. Can be tilted.

  Even if the operation arm 83 rotates toward the rear position (k), if the friction between the engaging member 7 and the receiving member N is large, the engaging member 7 cannot temporarily move backward. The operating end 86b of the unlocking spring 86 is left with the engaging member 7 at the lock position (h). In this state, the operation end 86b of the unlocking spring 86 is restricted from moving backward by the engaging member 7 in a state where it does not move, and the elastic repulsive force in the unlocking direction is increased. In other words, when the operating end 86b of the unlocking spring 86 is left at the lock position (h) together with the engaging member 7, the engaging member 7 receives the elastic biasing force of the unlocking spring 86 rearward. Will work. Therefore, at the moment when the friction between the engaging portion c8 and the receiving member N decreases due to the slight movement of the backrest H or the like, the engaging member 7 retreats backward by the elastic urging force of the unlocking spring 86, and the lock is released. Will be released.

<< Locking mechanism J >>
The locking mechanism J is for synchronously moving the seat D in accordance with the tilt of the backrest H, and is capable of moving the front portion of the seat receiver d1 back and forth at the front end of the support base C via the front link c9. In addition to the support, the rear portion of the seat D is pivotally supported by a rear link g4 provided on the back support G via a rear connection shaft j4.

  In the locking mechanism J according to this embodiment, in the initial state, the front link c9 and the rear link g4 are each inclined forward, and when the backrest H is inclined backward, the seat D is entirely raised. It is a so-called weight sensing system configured as described above.

  As described above, the chair A according to the present embodiment includes the back frame 1 that performs a backward tilting operation around the main shaft j1 provided on the support base C. The back frame 1 includes left and right side frame portions 1a, an upper frame portion 1b disposed on the upper back side of the backrest surface and connecting upper end portions of the left and right side frame portions 1a, and a left and right side frame portion 1a. A lower frame portion 1c which is continuous and extends to a position corresponding to the main axis j1 is integrally provided. The left and right side frame portions 1a are structurally connected only by the upper frame portion 1b. For this reason, it is possible to provide the chair A having the back frame 1 having an excellent degree of freedom in design for obtaining a suitable appearance and a structure that is easy to assemble.

  The left and right side frame portions 1a each have a shape of a member that gradually widens downward. For this reason, a suitable structure having excellent strength toward the lower portion is provided.

  The side frame portion 1a is disposed on the back side of the backrest surface. For this reason, the load of the seated person can be favorably supported from the back side of the backrest surface.

  The side frame portion 1a has a U-shape in a side view and a front view. Further, the side frame portion 1a is formed by connecting the upper frame portion 11 and the lower frame portion 13 via the bent portion 12. For this reason, it is possible to give a suitable impression that the side frame 1a has a shape that narrows toward the top and bottom in appearance. Further, the bent portion 12 at the center in the vertical direction forming the U-shape can be suitably positioned at the waist portion of the seated person on the backrest surface, and has a suitable shape for supporting the seated person. Become.

  The side frame portion 1a and the lower frame portion 1c are continuous so as to form an S-shape in side view. For this reason, it is possible to realize the back frame 1 of a three-dimensional shape and an integrally molded product.

  At the front end of the lower frame portion 1c, there is provided a recess 15 which is a portion that can accommodate the end of the main shaft j1. Therefore, it is possible to realize a structure in which the main shaft j1 is hardly visually recognized in appearance.

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

  In the above-described embodiment, the back frame, in addition to the side frame portion, the upper frame portion, and the lower frame portion, the lower connection portion is integrally provided, but the lower connection portion is not necessarily provided integrally. It does not have to be. That is, in the back frame, the lower connecting portion does not have to be integrally formed. In other words, the back frame may not have a configuration corresponding to the lower connecting portion.

  The backrest may be constituted mainly by a back frame. That is, the backrest is not applied only to the configuration in which the front frame is arranged on the front side of the back frame as in the above-described embodiment, but can be applied to various backrests. .

  The left and right side frame portions only need to be structurally connected only by the upper frame portion. In other words, there may be one that connects the left and right side frame portions by using a tension member or a member having a lower strength than the upper frame portion.

  It goes without saying that the front part of the lower frame part does not have to be connected to the main shaft.

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

DESCRIPTION OF SYMBOLS 1 ... Back frame 1a ... Side frame part 1b ... Upper frame part 1c ... Lower frame part C ... Support base j1 ... Spindle

Claims (6)

A chair provided with a back frame that performs a backward tilting operation about a main shaft provided on a support base,
The left and right side frame portions, the upper frame portion disposed on the upper back side of the backrest surface and connecting the upper end portions of the left and right side frame portions , and the lower frame portion of the left and right side frame portions , respectively. A lower frame portion extending continuously forward and having a front portion positioned near the support base portion,
The left and right side frame portions each have a shape gradually widening downward and are structurally connected only by the upper frame portion ,
A chair in which only the left and right side frame portions, the upper frame portion, and the left and right lower frame portions are integrally formed of a synthetic resin to form a downward U-shaped portion as viewed from the front . The chair according to claim 1, wherein the left and right side frame portions are respectively disposed on the back side of the backrest surface. The side frame portions of the left and right, in each side view and front view, claim forms a dogleg shape 1 or 2 chair according. The side frame portions of the left and right, according to claim 1, wherein is obtained by continuously and lower frame portion which is inclined forward through the bent portions in the upper frame portion and a side view when tilted backward in each side view Chair. The side frame portion and said lower frame section, according to claim 1, 2, 3 or 4 chair according is obtained by continuously so as to form a side view S-shape. The front end portion of the lower frame portion, a chair according to claim 1, 2, 3, 4 or 5, characterized in that comprises a site capable of accommodating an end portion of the main shaft.

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