chair

Abstract

To provide a chair that can prevent a garment of a seated person from being caught when a seat body is in a use posture, and can make the external appearance excellent.SOLUTION: A chair includes a seat body 3 and a leg body 2. The leg body can switch the seat body between a use posture and a storage posture. The leg body has a pair of front legs 21 and a pair of rear legs 22 separated in a chair width direction. The front and rear leg pair at one side in the chair width direction and the front and rear leg pair at the other side in the chair width direction are connected by a horizontal connection rod 24 extending in the chair width direction. The seat body includes a frame-shaped frame and a swelling beam. The frame-shaped frame has a front portion support rod, a rear portion support rod, and left and right side portion support rods. The swelling beam is connected to the front portion support rod and the rear portion support rod, is arranged in an inner area in the chair width direction of the pair of side portion support rods, and has an intermediate area in a front-back direction swelling to an opposite side to a seat side of a seating face. The swelling portion of the swelling beam is abutted on a top face of the horizontal connection rod in a state that a seat plate is in a use posture.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a chair capable of bouncing up the seat body.

Background Art

[0002] In order to make the storage space more compact when not in use, a chair is known in which the seat body can be bounced up with respect to the leg body (see, for example, Patent Document 1).

[0003] The chair described in Patent Document 1 includes a seat body on which a seated person sits, and leg bodies that support the rear portion of the seat body so as to be rotatable about an axis along the chair width direction. The seat body can be switched between a use posture in which the seat surface faces upward and a storage posture in which the seat surface faces rearward by rotation about an axis center along the chair width direction. The leg bodies include a pair of front legs arranged apart from each other in the chair width direction, and a pair of rear legs arranged apart from each other in the chair width direction on the rear side of the front legs. Each front leg and the corresponding left and right rear legs are connected by a pair of front and rear extending portions (horizontal portions) extending in the front and rear directions. On the upper surfaces of the front end portions of the left and right front and rear extending portions, a support member extending in the chair width direction is installed. In the case of this chair, when the seat body is in the use posture, the back surface on the front end portion side of the seat body abuts on the upper surface of the support member on the leg body side, so that the seating load input to the seat body is received by the leg body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the chair described in Patent Document 1, when the seat is in use, the underside of the front part of the seat abuts against the support member on the leg side, which extends in the chair width direction and is approximately the same width as the seat, from above. Therefore, there is a concern that when the clothing of a person sitting on the seat hangs down from the front side of the seat, the clothing of the person sitting on the seat may get caught between the seat and the support member on the leg side.

[0006] Furthermore, in the chair described in Patent Document 1, the support member on the leg side extends in the chair width direction to approximately the same width as the seat at the front end of the front-to-rear extension. Therefore, when the seat is viewed from the side above in a seated position, the contact area between the seat and the support member on the leg side is visible from the outside, raising concerns that it may detract from the appearance.

[0007] Therefore, the present invention aims to provide a chair that can prevent the seater's clothing from getting caught in the seat when the seat is in a seated position, and that also has a good appearance. [Means for solving the problem]

[0008] The chair according to the present invention employs the following configuration to solve the above problems. In other words, the chair according to the present invention comprises a seat body having a seat surface on which a person sits, and a leg body to which the front or rear of the seat body is rotatably connected around an axis along the chair width direction, and which supports the seat body so as to be switchable between a usage position in which the seat surface faces upward and a storage position in which the seat surface faces backward or forward, wherein the leg body has a pair of front legs spaced apart in the chair width direction and a pair of rear legs spaced apart in the chair width direction behind the front legs, and one front and rear leg pair on one side in the chair width direction is connected to each other and the other front and rear leg pair on the other side in the chair width direction is connected to each other The rear leg pair is connected by a transverse connecting rod extending in the chair width direction, and the seat body is characterized by comprising a frame-shaped frame having a front support rod along the front edge of the seat body, a rear support rod along the rear edge of the seat body, and a pair of side support rods along each of the left and right sides of the seat body, and a bulging beam connected to the front support rod and the rear support rod, and positioned in a region in the chair width direction inward from the pair of side support rods, and having an intermediate region in the front-rear direction spaced apart from the axis, which bulges out toward the side opposite to the seating side of the seat surface, and the bulging portion of the seat body in the usage position abuts against the upper surface of the transverse connecting rod.

[0009] With the above configuration, when the seat is in use, the bulging portion of the bulging beam provided on the seat comes into contact with the upper surface of the lateral connecting rod on the leg side, thereby supporting the seating load applied to the seat through the bulging beam to the lateral connecting rod on the leg side. In this configuration, the bulging beam on the seat side is positioned inward in the chair width direction from the left and right side support rods of the frame-shaped frame, and when the seat is in use, it contacts the lateral connecting rod on the leg side at a position inward in the chair width direction from the left and right side support rods of the frame-shaped frame. Therefore, when a person sits on the seat, even if the person's clothing hangs down from the side of the seat, the clothing is prevented from being displaced in the direction of the contact point by the side support rods of the frame-shaped frame. This makes it possible to prevent the person's clothing from getting caught in the contact point between the bulging beam on the seat side and the lateral connecting rod on the leg side. Furthermore, in this configuration, the bulging beam on the seat side is positioned inward in the chair width direction compared to the left and right side support rods of the frame-like structure. As a result, when the seat is viewed from above the side in the user's posture, the bulging beam is less visible from the outside. Therefore, adopting this configuration results in a better appearance from the outside.

[0010] The bulging beam comprises a first bulging beam and a second bulging beam, which are spaced apart in the chair width direction, and the spacing between the first and second bulging beams in the chair width direction may be such that the spacing between them narrows from one end to the other in the front-to-back direction.

[0011] In this case, the first and second bulging beams form a truss structure between them and the frame-like frame, making it possible to efficiently increase the rigidity of the seat.

[0012] The first bulging beam and the second bulging beam may be configured such that the spacing between them in the chair width direction narrows from the front-rear end on the side closer to the axis towards the front-rear end on the side further away from the axis.

[0013] In this case, the contact points between the first bulge beam and the lateral connecting rod of the second bulge beam are positioned further inward in the chair width direction. Therefore, it is possible to more reliably prevent clothing from getting caught in the contact points when the seat is in use.

[0014] It is desirable that the distance between the outer ends of the front ends of the pair of front legs in the chair width direction be narrower than the distance between the inner ends of the rear ends of the pair of rear legs in the chair width direction.

[0015] In this case, when stacking multiple chairs front to back with the seats folded, the front legs of the rear chairs can be inserted between the rear legs of the front chairs. This makes it possible to compactly stack multiple chairs front to back.

[0016] The spacing between the pair of front and rear extensions of the leg body in the chair width direction may be made to narrow towards the front.

[0017] In this case, when the seats are put in the storage posture and a plurality of chairs are stacked one behind the other, the subsequent chair can be inserted deeper between the left and right rear legs of the front chair and stacked front and back. Therefore, when this configuration is adopted, it becomes possible to stack and arrange a plurality of chairs more compactly in the front-back direction.

Effects of the Invention

[0018] The chair according to the present invention has a structure in which when the seat body is in the use posture, the bulging portion of the bulging beam abuts against the lateral connecting rod on the leg body side at a position inside the chair width direction from the left and right side support rods of the frame-shaped frame. Therefore, when the chair according to the present invention is adopted, it is possible to surely prevent the clothes of the seated person from being sandwiched between the contact portions on the seat body side and the leg body side, and moreover, since the contact portions on the seat body side and the leg body side are not easily visible from the outside, the appearance of the chair can be improved.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a perspective view of the chair of the embodiment. [Figure 2] FIG. 2 is a side view of the chair of the embodiment when the seat body is in the use posture. [Figure 3] FIG. 3 is a plan view of the skeleton portion of the seat body of the chair of the embodiment. [Figure 4] FIG. 4 is a side view of the chair of the embodiment when the seat body is in the storage posture.

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described based on the drawings. In the following description, the direction indicated by the arrow FR in the figure facing the front of a person sitting on the chair 1 in the normal posture is referred to as "front", and the opposite direction is referred to as "rear". Also, regarding "up", "down", "left", and "right", the direction indicated by the arrow UP in the figure above the person sitting on the chair 1 in the normal posture is referred to as "up", and the opposite direction is referred to as "down", and the direction indicated by the arrow LH in the figure on the left side of the person sitting on the chair 1 in the normal posture is referred to as "left", and the opposite direction is referred to as "right". Also, the direction facing the left and right of the chair 1 is referred to as the "chair width direction".

[0021] FIG. 1 is a perspective view of the chair 1 of the present embodiment as viewed obliquely from the upper left front. FIG. 2 is a side view of the chair 1 as viewed from the left side. In FIG. 2, some members (cushion body 30) are omitted. As shown in these figures, the chair 1 includes a leg body 2, a seat body 3, a backrest 4, and an armrest 5.

[0022] The leg body 2 includes a pair of front legs 21 arranged apart in the chair width direction, and a pair of rear legs 22 arranged apart in the chair width direction on the rear side of the front legs 21. At each lower end of the front legs 21 and the rear legs 22, casters 15 that can roll on the ground surface are attached. On each of the left and right front legs 21, a front-back extending portion 23 that extends in the front-back direction toward the rear side from the upper end of the upright portion that stands up upward from the lower end is integrally formed. The rear end portion of each front-back extending portion 23 is connected to the substantially central portion in the vertical direction of the corresponding left and right rear legs 22. The front legs 21 and the rear legs 22 on one side in the chair width direction are connected to each other through the front-back extending portion 23 to constitute a pair of front and rear legs on one side. Similarly, the front legs 21 and the rear legs 22 on the other side in the chair width direction are connected to each other through the front-back extending portion 23 to constitute a pair of front and rear legs on the other side. The pair of front and rear legs on one side and the pair of front and rear legs on the other side are connected to each other by a horizontal connecting rod 24 at a portion closer to the front than the substantially central portion in the front-back direction of the front-back extending portion 23. In the present embodiment, the left and right front-back extending portions 23 are connected to each other by the horizontal connecting rod 24.

[0023] The lateral connecting rod 24 comprises a support arm portion 24a that protrudes upward from the upper surface of each of the front and rear extension portions 23 on the left and right sides, and a transverse beam portion 24b that extends along the width direction of the chair and connects the upper parts of the left and right support arm portions 24a. The left and right support arm portions 24a are inclined upward and inward in the width direction of the chair.

[0024] The distance between the outer ends of the front ends of the left and right front legs 21 in the chair width direction is narrower than the distance between the inner ends of the rear ends of the left and right rear legs 22 in the chair width direction. The front and rear extensions 23 connect the approximately central part of the rear leg 22 in the vertical direction to the upper ends of the corresponding left and right front legs 21. The front and rear extensions 23 are connected to the inner surface of the rear leg 22 in the chair width direction, and extend forward after curving forward from the inner surface of the rear leg 22 in the chair width direction. In addition, the front and rear extensions 23 are inclined inward and downward in the chair width direction from the rear leg 22 side to the front leg 21 side. Therefore, the distance between the left and right front and rear extensions 23 in the chair width direction narrows towards the front. In this embodiment, the chair 1 is configured such that, when not in use, the left and right front legs 21 of the rear chair 1 can be inserted between the left and right rear legs 22 of the front chair 1 (making it nestable).

[0025] Furthermore, the left and right rear legs 22 are inclined forward at a predetermined angle from the lower end to which the casters 15 are attached, upward. Above the connection point between the left and right rear legs 22 and the front and rear extensions 23, a pivot arm 25 is provided to rotatably support the rear of the seat body 3. The pivot arm 25 extends forward from the rear legs 22. The pivot arm 25 supports a pivot shaft (not shown) that extends in the chair width direction. The pivot shaft rotatably supports the rear of the seat body 3. The seat body 3 is designed to be able to flip up and rotate around the axis of the pivot shaft of the pivot arm 25.

[0026] Mounting bases 26 are formed at the upper ends of the left and right rear legs 22, to which the backrest 4 and armrests 5 are attached. Support projections 27 are provided on the mounting bases 26 to support the left and right sides of the backrest 4. The backrest 4 is fixed to the mounting bases 26 by bolts or the like with its left and right sides fitted into the support projections 27. The armrests 5 are fixed to the mounting bases 26 by bolts or the like with their contact with the lower ends of the sides of the backrest 5. The armrests 5 extend forward from the upper ends of the rear legs 22.

[0027] As shown in Figure 1, the seat body 3 comprises a rectangular frame-shaped frame 29 in plan view and a cushion body 30 supported by the frame-shaped frame 29. The frame-shaped frame 29 is made of metal, hard resin, or the like. The cushion body 30 is constructed, for example, by placing a cushioning material such as urethane on the upper surface of a rectangular seat plate, and covering the upper surface and periphery of the cushioning material with a surface material. However, the structure of the seat 3 is not limited to this. The seat 3 may, for example, have a structure in which upholstery is stretched over the upper surface of the frame-shaped frame 29.

[0028] Figure 3 is a plan view showing the skeletal structure of the seat body 3. Note that, for illustrative purposes, parts of the front legs 21 and rear legs 22 of the leg body 2 are omitted in Figure 3. Also, in Figure 3, the left and right front-to-back extensions 23 and the lateral connecting rods 24 of the leg body 2 are shown by dashed lines. The frame-shaped frame 29 includes a front support rod 29f along the front edge of the seat body 3, a rear support rod 29r along the rear edge of the seat body 3, and a pair of side support rods 29s (side frames) along the left and right sides of the seat body 3. Support pieces 31 (see Figures 1 and 2) that bulge upward in a mountain shape are integrally formed on the rear of the left and right side support rods 29s. Each of the left and right support pieces 31 is positioned between the left and right pivot arms 25 on the leg body 2 side and is rotatably supported on each axis of the pivot arms 25.

[0029] Figure 4 is a side view of the chair 1 showing the seat 3 in a state where it is flipped up around the axis of the pivot arm 25. The seat body 3 can be switched between a usage position (see Figure 2) where the seat surface 3a faces upward and a storage position where the seat surface 3a faces backward by rotating the seat body 3 around the axis of the pivot arm 25. The seat body 3 is maintained almost horizontally in the usage position, and the front side is flipped up towards the backrest 4 in the storage position.

[0030] A first bulging beam 40F and a second bulging beam 40S are installed on the front support rod 29f and rear support rod 29r of the frame-shaped frame 29. The first bulging beam 40F and the second bulging beam 40S are made of, for example, solid rod material or pipe material. However, the structure of the first bulging beam 40F and the second bulging beam 40S is not limited to this structure as long as it can ensure sufficient strength. The first bulging beam 40F and the second bulging beam 40S are spaced apart from each other in the chair width direction and are positioned in the area in the chair width direction inward from the left and right side support rods 29s. In addition, the central area in the front-rear direction of the first bulging beam 40F and the second bulging beam 40S (the area spaced apart from the axis of rotation of the seat body 3) bulges out convexly on the side that is below the seat body 3 in the usage posture (the side opposite to the seat surface 3a of the seat body 3).

[0031] When the seat 3 is in use, the first bulging beam 40F and the second bulging beam 40S have their most downwardly bulging portions (hereinafter referred to as "bulging portions 41") in contact with the upper surface of the lateral connecting rod 24 (lateral beam portion 24b) on the leg body 2 side. Here, the entire front-to-back range of the first bulging beam 40F and the second bulging beam 40S is located in the inward region in the chair width direction compared to the left and right side support rods 29s. For this reason, the contact points between the bulging portions 41 of both bulging beams 40F and 40S and the lateral connecting rods 24 on the leg body 2 side are located inward in the chair width direction compared to the left and right side support rods 29s. The seat 3 is maintained in a nearly horizontal position by the contact of the bulging portions 41 of the first bulging beam 40F and the second bulging beam 40S with the upper surface of the lateral connecting rod 24 on the leg body 2 side, and the load of the seated person applied to the seat 3 is supported by the leg body 2.

[0032] Furthermore, as shown in Figure 3, the first bulging beam 40F and the second bulging beam 40S are inclined inward in the chair width direction from the rear end connected to the rear support rod 29r to the front end connected to the front support rod 29f. The two bulging beams 40F and 40S are arranged symmetrically with respect to the center of the frame-shaped frame 29 in the width direction. Therefore, the distance between the first bulging beam 40F and the second bulging beam 40S in the chair width direction narrows from the rear side (one end in the front-rear direction) to the front side (the other end in the front-rear direction). Also, in this embodiment, since the axis that rotates the seat body 3 is located on the rear side of the seat body 3, it can be said that the distance between the first bulging beam 40F and the second bulging beam 40S in the chair width direction narrows from the front-rear end on the side closer to the axis to the front-rear end on the side further away from the axis.

[0033] When a person actually sits on the chair 1 of this embodiment, the seat 3 is positioned in the usage posture shown in Figures 1 and 2, and the first bulging beam 40F and the second bulging beam 40S below the seat 3 are brought into contact with the upper surface of the lateral connecting rod 24 on the leg body 2 side. When the person sits on the seat surface 3a in this state, the seating load is supported by the lateral connecting rod 24 on the leg body 2 side through the first bulging beam 40F and the second bulging beam 40S. At this time, the contact points between the bulging portions 41 of the first and second bulging beams 40F and 40S and the lateral connecting rod 24 on the leg body 2 side are sufficiently spaced below the seat surface 3a of the seat 3 and are positioned offset inward in the chair width direction compared to the side of the seat 3 (side support rod 29s).

[0034] Furthermore, when storing multiple chairs 1 together in the storage space, the seat 3 of each chair 1 is flipped upwards to the storage position as shown in Figure 4. Next, in this state, the front legs 21 of the rear chair are inserted from the rear side between the left and right rear legs 22 of the front chair 1, and the left and right front and rear extensions 23 of the rear chair 1 are inserted between the left and right front and rear extensions 23 of the front chair 1. By stacking the rear chair 1 on top of the rear chair 1 in this way, the overall front-to-back width is narrowed, making it possible to arrange them compactly in the storage space. Note that three or more chairs 1 can be stacked front to back in the same manner.

[0035] As described above, the chair 1 of this embodiment is structured so that when the seat 3 is in the seating position, the bulging portions 41 of the first and second bulging beams 40F and 40S abut against the lateral connecting rod 24 on the leg body 2 side at a position inward in the chair width direction from the left and right side support rods 29s of the frame-shaped frame 29. Therefore, even if the seated person's clothing hangs down from the side of the seat 3, it is possible to reliably prevent the seated person's clothing from getting caught between the contact points on the seat 3 side and the leg body 2 side. In addition, when the seat 3 is viewed from above the side, the first and second bulging beams 40F and 40S on the seat 3 side are less visible from the outside. Therefore, when the chair 1 of this embodiment is adopted, it is possible to prevent the seat body 3 from trapping the sitter's clothing when the seat is in use, and to improve the appearance.

[0036] Furthermore, in this embodiment, the chair 1 has a first bulging beam 40F and a second bulging beam 40S connected to a frame-shaped frame 29 such that the distance between them narrows from one end to the other in the front-to-back direction. As a result, the first bulging beam 40F and the second bulging beam 40S form a truss structure between them and the frame-shaped frame 29, which makes it possible to efficiently increase the rigidity of the seat 3.

[0037] In particular, in this embodiment, the first bulging beam 40F and the second bulging beam 40S of the chair 1 have a spacing between them in the chair width direction that narrows from the front-rear end on the side closer to the pivot axis of the seat 3 towards the front-rear end on the side further away from the pivot axis. As a result, the contact points between the first and second bulging beams 40F, 40S and the lateral connecting rod 24 are positioned further inward in the chair width direction. Therefore, when this configuration is adopted, it is possible to more reliably prevent clothing from getting caught in the contact points when the seat 3 is in a user position.

[0038] Furthermore, in this embodiment, the distance between the outer ends of the front ends of the left and right front legs 21 in the chair width direction is narrower than the distance between the inner ends of the rear ends of the left and right rear legs 22 in the chair width direction. Therefore, when stacking multiple chairs 1 front to back with the seat 3 in the stowed position, the left and right front legs 21 of the rear chair 1 can be inserted between the left and right rear legs 22 of the front chair 1. Thus, when this configuration is adopted, multiple chairs 1 can be compactly stacked front to back.

[0039] Furthermore, in this embodiment, the chair 1 has a pair of front-to-rear extensions 23 on the leg body 2 side that are spaced further apart in the chair width direction, with the spacing narrowing towards the front. Therefore, when stacking multiple chairs 1 front to back with the seat 3 in the stowed position, the rear chairs 1 can be inserted more deeply between the left and right rear legs 22 of the front chairs 1, allowing them to be stacked front to back. Consequently, when this configuration is adopted, multiple chairs 1 can be stacked and arranged more compactly front to back.

[0040] Furthermore, in this embodiment, the chair 1 has a lateral connecting rod 24 on the leg body 2 side, which includes a pair of support arm portions 24a that protrude upward from the upper surfaces of the left and right front and rear extension portions 23, and a transverse beam portion 24b that extends in the chair width direction and connects the upper parts of the pair of support arm portions 24a. As a result, the transverse beam portion 24b that abuts the first and second bulging beams 40F and 40S on the seat body 3 side is located above the front and rear extension portions 23, which allows the bulging height of the first and second bulging beams 40F and 40S to be reduced. Therefore, when this configuration is adopted, when stacking multiple chairs 1 front to back with the seat body 3 in the stored position, the bulging height of the first and second bulging beams 40F and 40S is reduced, making it possible to stack the chairs 1 more deeply front to back.

[0041] It should be noted that the present invention is not limited to the embodiments described above, and various design modifications are possible without departing from the spirit of the invention. For example, in the above embodiment, the rear of the seat 3 is supported by the leg 2 so as to be able to flip up and rotate around an axis along the width direction of the chair, but the support configuration of the seat 3 is not limited to this. The front end of the seat 3 may also be supported by the leg 2 so as to be able to flip up and rotate around an axis along the width direction of the chair. In this case, when the seat 3 is in the stored position, the seat surface faces forward. Furthermore, in the above embodiment, the bulging beams connected to the front support rod 29f and rear support rod 29r of the frame-shaped frame 29 are composed of a first bulging beam 40F and a second bulging beam 40S, but the number of bulging beams is not limited to two; it may be three or more, or even just one. Furthermore, the shape of the bulging beam does not necessarily have to be rod-shaped or pipe-shaped; it may be a trapezoidal hollow block or a solid block when viewed from the front. Furthermore, in the above embodiment, the front and rear extensions 23 are integrally formed at the upper end of the upright portion of the front leg 21, but the front and rear extensions 23 may be integrally formed with the rear leg 22. Alternatively, the front and rear extensions 23 may be integrally formed with the front leg 21 and the rear leg 22, respectively, and the front and rear extensions 23 may be connected to each other. Alternatively, the front and rear extensions 23 may be formed from separate members from the front leg 21 and the rear leg 22, and the front and rear ends of the front and rear extensions 23 may be connected to the front leg 21 and the rear leg 22. [Explanation of symbols]

[0042] 1…Chair 2…Leg body 3…Seat 3a...Seat 21...front leg 22... hind legs 23…Front and rear extensions 24…Horizontal connecting rod 29…Frame-like frame 29f…Front support rod 29r…Rear support rod 29s…Side support rod 40F…1st bulging beam (bulging beam) 40S…Second bulging beam (bulging beam)

Claims

1. A seat having a seat surface on which a person sits, The front or rear of the seat is connected so as to be rotatable around an axis along the width direction of the chair, and the seat is supported by legs that allow it to be switched between a usage position in which the seat surface faces upward and a storage position in which the seat surface faces backward or forward. The aforementioned leg body is A pair of front legs are spaced apart in the width direction of the chair, It has a pair of rear legs positioned at the rear of the front legs and spaced apart in the chair width direction, The front and rear legs on one side of the chair, connected to each other in the chair's width direction, and the front and rear legs on the other side, connected to each other in the chair's width direction, are connected by a transverse connecting rod extending in the chair's width direction. The aforementioned seat body is A frame-shaped frame having a front support rod along the front edge of the seat, a rear support rod along the rear edge of the seat, and a pair of side support rods along each of the left and right sides of the seat, The front support rod and the rear support rod are connected, and the bulging beam is positioned inward in the chair width direction compared to the pair of side support rods, and the intermediate region in the front-rear direction, spaced apart from the axis, bulges out toward the side opposite to the seating side of the seat surface, and the bulging portion of the seat body abuts against the upper surface of the lateral connecting rod when the seat is in the usage position, The aforementioned bulging beam comprises a first bulging beam and a second bulging beam, which are spaced apart in the chair width direction. A chair characterized in that the first bulging beam and the second bulging beam have a spacing between them in the chair width direction that narrows from one end to the other in the front-to-back direction.

2. The chair according to claim 1, characterized in that the first bulging beam and the second bulging beam have a spacing width in the chair width direction that narrows from the front-rear end on the side closer to the axis to the front-rear end on the side further away from the axis.

3. The chair according to claim 1 or 2, characterized in that the distance between the outer ends in the chair width direction on the front end side of a pair of front legs is narrower than the distance between the inner ends in the chair width direction on the rear end side of a pair of rear legs.

4. The chair according to claim 3, characterized in that the leg body extends in the front-rear direction and has a pair of front-rear extensions whose spacing in the chair width direction narrows toward the front.

5. The chair according to any one of claims 1 to 4, wherein the seat is provided with a tensioning material stretched over the upper surface of the frame-shaped frame.

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