chair

Abstract

To provide a chair that more reliably prevents obstruction of the rotation of the backrest and seat. [Solution] The chair of the embodiment comprises a support structure 2 having a first shaft body 21 extending in the left-right direction and a second shaft body 22 extending in the left-right direction on its front side; a backrest 3 supported by the first shaft body 21 so as to be rotatable about the first shaft body 21 in a side view when viewed from the left-right direction; and a seat 4 positioned above the support structure 2 and supported by the second shaft body 22 so as to be rotatable about the second shaft body 22 in a side view. The backrest 3 comprises a backrest body portion 30 that supports the back of the sitter above the seat 4, and an extension portion 35 that extends from the backrest body portion 30 so as to straddle the seat vertically in a side view on the left-right side of the seat 4 and is connected to the first shaft body 21. The extension portion 35 has a covering portion 35a that covers at least a part of the first shaft body 21 and the second shaft body 22 from the left-right side in a side view.

Description

Technical Field

[0001] The present invention relates to a chair.

Background Art

[0002] Patent Document 1 discloses a chair in which each of a seat and a backrest is supported on the front end side of a support arm and is configured to be tiltable backward and downward. The backrest is configured to be rotatable about the front end side of the support arm as a fulcrum via a rocking lever that tilts upward and backward in a side view. The rocking lever is supported by the support arm below the seat and extends upward via the outer side of the seat.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the rocking lever crosses the outer side of the seat in the vertical direction. Therefore, below the seat, in a side view, a portion where the distance between the backrest (rocking lever) and the seat changes in conjunction with the relative movement between the backrest and the seat occurs between the backrest (rocking lever) and the seat. Therefore, a structure in which it is less likely for an object to be caught in this portion and for the rotation of the backrest and the seat to be inhibited is desired.

[0005] Therefore, an object of the present invention is to provide a chair that can more reliably prevent the rotation of the backrest and the seat from being inhibited.

Means for Solving the Problems

[0006] (1) A chair according to one aspect of the present invention comprises a support structure having a first shaft body extending in the left-right direction and a second shaft body extending in the left-right direction on its front side; a backrest supported by the first shaft body so as to be rotatable about the first shaft body in a side view taken from the left-right direction; and a seat positioned above the support structure and supported by the second shaft body so as to be rotatable about the second shaft body in a side view, wherein the backrest comprises a backrest body portion that supports the back of the sitter above the seat, and an extended portion that extends from the backrest body portion so as to straddle the seat vertically in a side view on the outside in the left-right direction relative to the seat and is connected to the first shaft body, wherein the extended portion has a covering portion that covers at least a part of the first shaft body and the second shaft body from the outside in the left-right direction in a side view. For example, if the extended portion of the backrest does not cover the first and second shafts from the outside in the left-right direction when viewed from the side, a portion of the support structure containing the first and second shafts and the extended portion of the backrest will have a portion where the spacing changes. Therefore, if an object gets caught in this portion, the rotation of the backrest and seat may be hindered. In contrast, according to this embodiment, the extended portion of the backrest has a covering portion that covers at least a part of the first and second shafts from the outside in the left-right direction when viewed from the side, so the possibility of objects getting caught is low. Therefore, it is possible to more reliably prevent the rotation of the backrest and seat from being obstructed.

[0007] (2) In the embodiment of (1) above, the support structure may include a front link member having a housing that supports the first shaft body, a first support portion that is rotatably supported relative to the first shaft body, a backrest connecting portion that is non-rotatably coupled relative to the extended portion of the backrest, and a second support portion that supports the second shaft body. For example, if the backrest and seat rotate independently and not in conjunction, and the amount of rotation of the backrest is greater than the amount of rotation of the seat, the backrest will continue to rotate even after the seat has rotated to its limit. As a result, the backrest may come too close to the seat, potentially causing objects to get caught. In contrast, according to this embodiment, the first support portion of the front link member is supported so as to be rotatable relative to the first shaft body supported by the housing, the backrest coupling portion is coupled to the extended portion of the backrest so as not to be rotatable relative to it, and the second support portion supports the second shaft body. As a result, the downward and rearward tilt of the backrest around the first shaft body due to the load input to the backrest and the downward and rearward tilt of the seat around the second shaft body are linked. This prevents the backrest from rapidly approaching the seat, and further reduces the possibility of objects getting caught. Therefore, it is possible to more reliably prevent the rotation of the backrest and seat from being hindered.

[0008] (3) In the embodiment of (2) above, the first shaft may be positioned below the second shaft in the side view. According to this embodiment, compared to the case where the first shaft is positioned above the second shaft in a side view, the movement of the front link member becomes smoother, and therefore the coordination between the backrest and the seat also becomes smoother.

[0009] (4) In the embodiment of (2) or (3) above, the backrest connecting portion may protrude outward in the left-right direction relative to the first support portion and the second support portion. According to this embodiment, compared to the case where the entire backrest coupling portion is positioned inward in the left-right direction relative to the first and second support portions, it is easier to connect the backrest coupling portion of the front link member to the extended portion of the backrest in the process after the front link member is supported by the housing.

[0010] (5) In the embodiment of (4) above, the front link member has the first support portion and the second support portion formed thereon and a side plate portion whose left-right direction is the thickness direction, and the backrest connecting portion may protrude outward from the side plate portion in the left-right direction. In this embodiment, the first support portion and the second support portion and the backrest connecting portion are separated in the left-right direction by the side plate portion. Therefore, the possibility of the backrest protruding toward the first support portion and the second support portion and causing adverse effects is low.

[0011] (6) In the embodiments of (1) to (5) above, the support structure may further include a rear support portion that supports the portion of the seat that is rearward from the portion supported by the second shaft from below. According to this embodiment, the part of the seat rearward from the part supported by the second shaft is supported from below by the rear support, so that even when the seat tilts downward and rearward around the second shaft, excessive downward displacement of the seat can be suppressed. Therefore, the effects of changes in relative angles during the rotation of the backrest and seat can be reduced.

[0012] (7) In the embodiment of (6) above, the rear support portion may include a third shaft body extending in the left-right direction behind the first shaft body, a fourth shaft body extending in the left-right direction above the third shaft body and supporting the portion behind the portion supported by the second shaft body at the seat, and a rear link member whose lower end is supported by the third shaft body and whose upper end is supported by the fourth shaft body. According to this embodiment, the part of the seat rearward from the part supported by the second shaft is supported by the rear link member. Therefore, even when the seat tilts downward and rearward around the second shaft, it tilts while being constrained by the four-bar linkage formed by the front and rear link members. As a result, excessive downward displacement of the seat can be more reliably suppressed. Consequently, the effects of changes in relative angles during the rotation of the backrest and seat can be more reliably reduced.

[0013] (8) In the embodiment of (7) above, in the side view, at least a portion of the third shaft is positioned forward of the fourth shaft, and in the initial state of the backrest and the seat, at least the upper end portion of the rear link member may be inclined rearward and upward in the side view. According to this embodiment, since at least the upper end portion of the rear link member is inclined rearward and upward in the initial state, upward rotation can be prevented when the seat tilts rearward and downward around the second shaft body. Therefore, the rearward and downward tilting of the seat around the second shaft body becomes smoother. [Effects of the Invention]

[0014] According to one aspect of the present invention, it is possible to more reliably prevent the backrest and the seat from being inhibited from rotating.

Brief Description of the Drawings

[0015] [Figure 1] Perspective view of the chair of the embodiment seen from the right rear. [Figure 2] Right side view of the chair of the embodiment. [Figure 3] Bottom view of the chair of the embodiment. [Figure 4] Right side view including the cross-section along the line IV-IV in FIG. 3. [Figure 5] Perspective view of the seat body of the embodiment in a removed state seen from the right front. [Figure 6] Cross-sectional perspective view along the line VI-VI in FIG. 5. [Figure 7] Cross-sectional perspective view along the line VII-VII in FIG. 5. [Figure 8] Cross-sectional perspective view along the line VIII-VIII in FIG. 5. [Figure 9] Cross-sectional perspective view along the line IX-IX in FIG. 5. [Figure 10] Cross-sectional perspective view along the line X-X in FIG. 5. [Figure 11] Diagram showing the positional relationship between the first shaft body, the second shaft body, and the covering portion in the initial state of the backrest and the seat of the embodiment. [Figure 12] Diagram showing the positional relationship between the first shaft body, the second shaft body, and the covering portion in the tilted state of the backrest and the seat of the embodiment.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, expressions indicating relative or absolute arrangements such as "parallel", "orthogonal", "center", "coaxial", etc. not only strictly mean such arrangements, but also include states where there are tolerances and relative displacements with angles and distances that can obtain the same function. In the drawings used in the following description, the scales of each member may be changed in order to make each member recognizable in size.

[0017] <Chair> Figure 1 is a perspective view of the chair 1 of the embodiment, seen from the right rear. Figure 2 is a right side view of the chair 1 of the embodiment. Figure 3 is a bottom view of the chair 1 of the embodiment. Figure 4 is a right side view including the cross-section along line IV-IV in Figure 3. Figure 5 is a perspective view of the chair with the seat body 40 of the embodiment removed, seen from the right front. Referring to Figures 1 to 5, the chair 1 comprises a support structure 2, a backrest 3, a seat 4, and an operating mechanism 5. The chair 1 is configured such that the seat 4 is displaced backward and downward in conjunction with the reclining movement of the backrest 3.

[0018] In the following explanation, directions such as front, back, up, down, left, and right are considered to be the same as the direction a person (sitter) is facing when seated in chair 1 in a normal posture. In this case, the arrow UP in the diagram indicates upward, the arrow FR indicates forward, and LH indicates left. Also, in the following explanation, in the front-back, up-down, and left-right directions, the side away from the center of chair 1 may be referred to as the outside, and the side toward the center of chair 1 may be referred to as the inside.

[0019] <Support structure> The support structure 2, when installed on the floor surface F, supports the backrest 3 and seat 4 from below. The support structure 2 comprises a leg body 10 and a base 20.

[0020] The leg body 10 comprises a multi-branched leg 11 and a leg column 12. Each leg of the multi-branched leg 11 is fitted with a caster 13 that can move on the floor surface F. Note that the casters 13 are not an essential component of the leg body 10. For example, the leg body 10 may be installed on the floor surface F via adjusters or the like instead of casters 13.

[0021] The leg column 12 extends upward from the central part of the multi-legged leg 11. The leg column 12 houses a gas spring 14, which is the lifting mechanism for the chair 1. The gas spring 14 is configured such that, for example, an inner cylinder 14a is supported so as to be able to rotate relative to an outer cylinder provided inside the leg column 12.

[0022] The support base 20 is connected to the upper end of the leg column 12 (inner cylinder 14a). The support base 20 supports the seat 4 from below and also supports the backrest 3 and seat 4 so that they can tilt. The support base 20 comprises a first shaft body 21, a second shaft body 22, a housing 23, a front link member 24, a rear support part 25, a spring mechanism 26, and a link connecting member 27.

[0023] The first shaft 21 extends linearly in the left-right direction. The second shaft 22 extends linearly in the left-right direction, parallel to the first shaft 21. The first shaft 21 and the second shaft 22 are positioned on the front side of the support base 20. Specifically, it is desirable that the first shaft 21 and the second shaft 22 be positioned within a range of approximately half the length of the housing 23 in the front-rear direction from the front end of the housing 23, and more preferably within a range of approximately one-third of the length of the housing 23 from the front end of the housing 23. In a side view from the left-right direction, the first shaft 21 is positioned below the second shaft 22. In a side view from the left-right direction, the first shaft 21 is positioned behind the second shaft 22. In a side view from the left-right direction, the second shaft 22 is positioned closer to the front end of the support base 20.

[0024] The housing 23 is connected to the upper end of the gas spring 14 (inner cylinder 14a). In a side view from the left and right, the housing 23 is formed in a box shape that is flattened in the vertical direction. The upper end of the gas spring 14 is inserted from below into the rear end of the housing 23. In a side view from the left and right, the housing 23 is cantilevered to the leg column 12, with the housing 23 tilting upward as it approaches the front.

[0025] In plan view, the housing 23 is formed in a triangular shape, with its width gradually increasing from left to right towards the front. The front end of the housing 23 is open to allow communication between the inside and outside of the housing 23 in the left-right direction. The housing 23 opens upward from the front end towards the center in the front-rear direction. The housing 23 supports the first shaft 21. The first shaft 21 is supported at the front ends of the side wall portions 23a located on both sides of the housing 23 in the left-right direction.

[0026] The front link member 24 includes a front link main body 24a, a first support portion 24b supported so as to be rotatable relative to the first shaft 21, a backrest connecting portion 24c that is coupled so as not to be rotatable relative to the extended portion 35 of the backrest 3, and a second support portion 24d that supports the second shaft 22.

[0027] The front link body portion 24a is housed at the front end of the housing 23. The front link body portion 24a extends in the left-right direction and is formed in a plate shape with the plate thickness direction in the vertical direction.

[0028] The first support portion 24b and the second support portion 24d are positioned inward in the left-right direction from the portion of the housing 23 where the first shaft body 21 is supported (the left and right side wall portions 23a). The backrest connecting portion 24c protrudes outward in the left-right direction from the first support portion 24b and the second support portion 24d.

[0029] The front link member 24 has a first support portion 24b and a second support portion 24d formed thereon, and a side plate portion 24e with the left-right direction being the thickness direction. The backrest coupling portion 24c protrudes outward in the left-right direction from the side plate portion 24e. The backrest coupling portion 24c is formed in a plate shape with the up-down direction being the thickness direction. The backrest coupling portion 24c is located in front of the portion of the housing 23 where the first shaft body 21 is supported (the left and right side wall portions 23a), and protrudes outward in the left-right direction from the left and right side plate portions 24e. In addition, in the housing 23, the length of the side wall portion 23a in the front-rear direction does not reach the area where the backrest coupling portion 24c is located, and the bottom side of the housing 23 is open outward in the left-right direction. In other words, the area in front of the front end of the side wall portion 23a of the housing 23 is a space (lateral connection opening 23b) for the backrest connection portion 24c to extend in the left-right direction. A lateral connection opening 23b is formed at the front end of the housing 23, which connects the inside and outside of the housing 23 in the left-right direction. The lateral connection opening 23b is formed by opening the area in front of the side wall portions 23a located on both sides of the housing 23 in the left-right direction. An upper connection opening 23c is formed at the front of the housing 23, which opens upward. The upper connection opening 23c is in communication with the lateral connection opening 23b. The portion of the housing 23 located behind the upper connection opening 23c constitutes the top wall portion 23d. The top wall portion 23d faces the lower surface of the seat 4 with a vertical gap between them, at least in the portion that overlaps with the leg column 12 in a plan view.

[0030] The rear support portion 25 supports the central part of the seat 4 (an example being the part of the seat 4 that is rearward from the part supported by the second shaft 22) from below. The rear support portion 25 includes a third shaft 25a that extends in the left-right direction behind the first shaft 21, a fourth shaft 25b that extends in the left-right direction above the third shaft 25a and supports the central part of the seat 4 (the central part of the seat receiving member 41), and a rear link member 25c whose lower end is supported by the third shaft 25a and whose upper end is supported by the fourth shaft 25b.

[0031] In a side view from the left and right directions, at least a portion of the third shaft body 25a is positioned forward of the fourth shaft body 25b. In the initial state of the backrest 3 and seat, at least the upper end portion of the rear link member 25c is inclined rearward and upward in a side view from the left and right directions (see Figure 4). In this embodiment, the rear link member 25c extends inclined so that it is positioned rearward as it goes upward in a side view from the left and right directions.

[0032] The spring mechanism 26 applies a reaction force (biasing force) to the front link member 24 when the front link member 24 tilts. The spring mechanism 26 is housed inside the housing 23. The spring mechanism 26 comprises a compression spring 26a, a fifth shaft body 26b extending linearly in the left-right direction in front of the compression spring 26a, a front spring receiving portion 26c supported so as to be rotatable relative to the fifth shaft body 26b and receiving the biasing force of the compression spring 26a from the front, and a rear spring receiving portion 26d that receives the biasing force of the compression spring 26a from the rear. The compression spring 26a is positioned between the front spring receiving portion 26c and the rear spring receiving portion 26d in a compressed state such that its length in the front-rear direction is shorter than its length when no compression force is applied, and constantly stores a biasing force that elastically presses the front spring receiving portion 26c forward.

[0033] In a side view from the left or right, the fifth axis 26b is positioned above the first axis 21. In a side view from the left or right, at least a portion of the fifth axis 26b is positioned behind the first axis 21. In a side view from the left or right, the fifth axis 26b is positioned behind the second axis 22. In a side view from the left or right, the fifth axis 26b is positioned in front of the fourth axis 25b.

[0034] The front link member 24 has a support wall portion 24f that supports the fifth shaft body 26b, located inward in the left-right direction from the side plate portion 24e on which the first support portion 24b and the second support portion 24d are formed. The support wall portion 24f is formed in a plate shape with the left-right direction being the thickness direction. The left and right support wall portions 24f have shaft holes into which the left-right ends of the fifth shaft body 26b are inserted.

[0035] The link connecting member 27 is a member for effectively maintaining the biasing force of the spring mechanism 26 (the reaction force that the spring mechanism 26 exerts on the front link member 24 when the front link member 24 tilts). The link connecting member 27 is formed in a plate shape that extends in the front-rear direction and has the plate thickness direction in the left-right direction. A pair of link connecting members 27 are provided via the spring mechanism 26, spaced apart in the left-right direction.

[0036] The front end of the link connecting member 27 has an axial hole that opens in the left-right direction for the first shaft body 21 to pass through. The rear upper end of the link connecting member 27 has an axial hole that opens in the left-right direction for the third shaft body 25a to pass through. The rear end of the link connecting member 27 is fixed to the rear of the housing 23 via fastening members such as bolts.

[0037] For example, if a reaction force (biasing force of the spring mechanism 26) acts on the first shaft body 21, a notch may be formed in the front link member 24 to prevent the link connecting member 27 from interfering with the front link member 24. The link connecting member 27 functions as a reinforcing member that reinforces the portion of the front link member 24 whose strength has been reduced. In addition, a rotation limiting member (e.g., a bolt) may be provided at the rear of the front link member 24 to limit the range of rotation of the front link member 24.

[0038] <Backrest> The backrest 3 supports the portion of the seated person's back from the waist to the upper back from behind. The outer parts of the backrest 3 in the left-right direction function as armrests to support the seated person's elbows. In a side view from the left-right direction, the backrest 3 is supported on the first shaft 21 so as to be rotatable around the first shaft 21.

[0039] The backrest 3 comprises a backrest body portion 30 and an extended portion 35. The backrest body 30 supports the seater's back above the seat 4. The backrest body 30 is formed in a shape that is convex to the rear in a plan view, and curves toward the rear and downward in a side view when viewed from the left or right direction.

[0040] The backrest body 30 comprises an inner shell 31 and an outer material 32. The inner shell 31 is a structural member that forms the framework of the backrest 3. The inner shell 31 is made of a different material from the extended portion 35. The inner shell 31 is a molded product integrally formed by stamping a synthetic resin material, for example. The inner shell 31 may also be formed by injection molding or the like.

[0041] The exterior material 32 comprises a cushioning material 32a and a surface material 32b. The cushioning material 32a covers the inner surface (front and the surfaces facing inward in the left and right directions) and the upper end surface of the inner shell 31. The outer material 32b covers the cushioning material 32a and the inner shell 31 together. The outer material 32b is installed so as to overlap the inner shell 31 from above. The cushioning material 32a and the inner shell 31 are covered by the outer material 32b from both sides in the front-to-back direction, both sides in the left-to-right direction, and from above. The lower end of the outer material 32b is fixed to the lower end of the inner shell 31, etc., by a stapler or the like.

[0042] The extended portion 35 is formed of, for example, a metal material (e.g., aluminum). The extended portion 35 is a molded product integrally formed from, for example, a metal material. The extended portion 35 connects the support base 20 and the backrest body portion 30.

[0043] The extension portion 35 extends from the backrest body portion 30 to the outside of the seat in the left-right direction, and in a side view taken from the left-right direction, it straddles the seat in the vertical direction. A pair of extension portions 35 are provided, spaced apart in the left-right direction. In a side view taken from the left-right direction, the extension portion 35 comprises a first arm portion 36 extending downward from the front lower end of the backrest body portion 30, a second arm portion 37 connected to the lower end of the first arm portion 36 and extending inward in the left-right direction, and a connecting arm portion 38 extending rearward from the upper end of the first arm portion 36.

[0044] The first arm section 36, when viewed from the left or right in a side view, extends downward from the front lower end of the backrest body section 30 (armrest section), sloping forward as it goes downward. The front-to-back dimension of the first arm section 36, when viewed from the left or right in a side view, gradually decreases as it goes downward.

[0045] The second arm portion 37 extends horizontally below the seat. The second arm extends from the side of the seat 4 to the support base 20, inclining downward as it moves inward in the horizontal direction. The front-to-back dimension of the second arm portion 37 gradually increases as it moves inward in the horizontal direction, as viewed from above.

[0046] The connecting arm portion 38 functions as a connecting part between the backrest body portion 30 (armrest portion) and the extension portion 35. The connecting arm portion 38 protrudes upward from a part of the upper end surface of the first arm portion 36 and then extends rearward. The inner shell 31 has a recess into which the connecting arm portion 38 enters from below. With the connecting arm portion 38 housed in the recess of the inner shell 31, the inner shell 31 and the connecting arm portion 38 are connected to each other, for example, via a fastening member such as a bolt. This allows the inner shell 31 and the extension portion 35 to be fixed to each other.

[0047] The extended portion 35 is connected to the first shaft body 21. A recess 37a is formed on the left-right inner side of the second arm portion 37 into which the left-right outer end of the first shaft body 21 fits. The second arm portion 37 has a hollow portion 37b into which the backrest connecting portion 24c enters from the left-right inner side.

[0048] The extended portion 35 has a covering portion 35a that covers at least a part of the first shaft body 21 and the second shaft body 22 from the outside in the left-right direction when viewed from the left-right direction. The covering portion 35a covers the first shaft body 21 and the second shaft body 22 from the outside in the left-right direction in both the initial state and the tilted state of the backrest 3 and the seat.

[0049] <za> The seat 4 supports the portion of the seated person's body from the buttocks to the thighs from below. The seat is positioned above the support structure 2. In a side view from the left and right directions, the seat 4 is supported on the second shaft 22 so as to be rotatable about the second shaft 22.

[0050] The seat comprises a seat body 40 and a seat support member 41. The seat body 40 comprises a seat shell 40a, a cushioning material 40b, and a surface material 40c. The seat shell 40a is a structural member that forms the framework of the seat 4. The seat shell 40a is made of a hard material such as synthetic resin or metal. The seat shell 40a is fixed to the seat support member 41 (seat support body 42) via fastening members such as bolts.

[0051] The cushioning material 40b is provided on at least the portion of the seat shell 40a that overlaps with the seating surface, and elastically supports the sitter. In this embodiment, the cushioning material 40b covers the upper surface of the seat shell 40a and, by wrapping around the outer edge of the seat shell 40a to the lower surface of the seat shell 40a, also covers the outer periphery of the lower surface of the seat shell 40a. The upholstery material 40c forms the surface of the seat 4, including the seating surface. The upholstery material 40c covers the seat shell 40a and the cushioning material 40b together.

[0052] The seat support member 41 is supported by the second shaft 22 and the fourth shaft 25b, covering the housing 23 from above. The seat support member 41 comprises a seat support body 42 and a front connecting member 43.

[0053] The seat support body 42 is formed in a plate shape with the vertical direction being the thickness direction. The seat support body 42 is formed in a rectangular shape that is larger than the outer shape of the support base 20 when viewed from above. A relief recess is formed on the front end side of the seat support body 42 to avoid the bolt. A relief hole is formed on the front side of the seat support body 42 to avoid the front spring support portion 26c. The corners on the rear end side of the seat support body 42 are formed in a rounded shape when viewed from above.

[0054] The front connecting member 43 extends in the front-rear direction and is formed in a plate shape with the left-right direction being the thickness direction. A pair of front connecting members 43 are provided, one on the left and one on the right. The upper edge of the front connecting member 43 is connected to the lower surface of the seating body 42. An axial hole 43a is formed on the front end side of the front connecting member 43 into which the left-right outer end of the second shaft body 22 is inserted. The seat 4 is supported on the second shaft body 22 so as to be rotatable about the second shaft body 22, by having the left-right outer ends of the second shaft body 22 inserted into the front ends of the left and right front connecting members 43.

[0055] A rear connecting member 44 is provided between the left and right front connecting members 43. The rear connecting member 44 is formed in a U-shape (inverted U-shape) that opens downward when viewed from the front-rear direction. The upper wall portion (plate-like portion with the vertical direction being the thickness direction) of the rear connecting member 44 is fixed to the seating body 42 via a plurality (for example, four) of bolts 45. Relief holes are formed in the upper wall portion of the rear connecting member 44 to avoid the left and right rear link members 25c. The left and right side walls of the rear connecting member 44 (left and right plate-like portions with the left-right direction being the thickness direction) have shaft holes formed in them into which the left-right ends of the fourth shaft body 25b are inserted.

[0056] In this embodiment, the seat 4 (seat support member 41) is connected to the rear link member 25c at its center in the front-rear direction. As a result, a gap is formed in the vertical direction between the rear end of the seat 4 and the rear end of the support base 20 when viewed from the left-right direction in a side view. The rear part of the seat 4 extends cantilevered backward from the support base 20 when viewed from the left-right direction in a side view.

[0057] <Operation mechanism> The operating mechanism 5 is located on the underside of the seat. In a side view from the left and right directions, the operating mechanism 5 is located on the underside of the seat 4, behind the extended portion 35 and in front of the leg column 12. The operating mechanism 5 is located in front of the rear end of the support base 20. In a plan view, the operating mechanism 5 is located to the right of the support base 20.

[0058] The operating mechanism 5 comprises a lever body 50 and a lever stay 55 for fixing the lever body 50 to the seat. The lever body 50 comprises a base member 51 fixed to a portion of the lever stay 55 that protrudes outward in the left-right direction from the seat support body 42, and an operating element 52 supported by the base member 51 below the base member 51 so as to be rotatable around an axis along the vertical direction.

[0059] The operator 52 is a component operated by a seated person or the like when raising or lowering the seat 4. In a plan view, the operator 52 is formed in a fan shape, with its width gradually increasing in the left-right direction towards the rear. The operator 52 is connected to a linkage mechanism (not shown) for linking the operating mechanism 5 and the gas spring 14 via a wire (not shown). The linkage mechanism is operated by the displacement of the wire caused by the rotation of the operator 52 around its axis in the vertical direction. The operation of the linkage mechanism by the rotation of the operator 52 enables the expansion and contraction of the gas spring 14. In other words, the seat 4 can be raised or lowered by the rotation of the operator 52.

[0060] <Rotation limiting member for backrest> The support structure 2 is provided with a rotation limiting member 6 for the backrest 3 to restrict the rotation of the backrest 3. The rotation limiting member 6 for the backrest 3 is provided on the lower side of the housing 23. The rotation limiting member 6 for the backrest 3 is a member for fixing the position of the front link member 24 in the initial state of the backrest 3 and seat 4. The rotation limiting member 6 for the backrest 3 is supported on the front part of the housing 23 so as to be movable in the left-right direction relative to the housing 23. In a plan view, the rotation limiting member 6 for the backrest 3 is provided on the side opposite to the operating mechanism 5 in the left-right direction. In a plan view, the rotation limiting member 6 for the backrest 3 is provided so as to be able to overlap with the rearward portion of the first shaft body 21 on the front link member 24. In the initial state of the backrest 3 and seat 4, the seated person or the like can operate an unillustrated operating member provided on the backrest 3, seat 4, or housing 23, which enables the rotation limiting member 6 of the backrest 3 to slide in the left-right direction.

[0061] When the operating member is operated, the rotation limiting member 6 of the backrest 3 slides inward in the left-right direction, causing the rotation limiting member 6 of the backrest 3 to overlap with the rearward portion of the first shaft 21 on the front link member 24. In other words, the rotation limiting member 6 of the backrest 3 slides under the rearward portion of the first shaft 21 on the front link member 24, supporting this portion from below. As a result, the position of the front link member 24 is fixed in the initial state of the backrest 3 and seat 4. In other words, the downward displacement of the backrest 3 is limited in the initial state of the backrest 3 and seat 4.

[0062] Furthermore, in the initial state of the backrest 3 and seat 4, when the operating member is operated, the rotation limiting member 6 of the backrest 3 slides outward in the left-right direction, causing the rotation limiting member 6 of the backrest 3 to no longer overlap with the rearward portion of the first shaft 21 on the front link member 24. In other words, the rotation limiting member 6 of the backrest 3 moves outward from below the rearward portion of the first shaft 21 on the front link member 24, thus releasing support for this portion. As a result, in the initial state of the backrest 3 and seat 4, rotation of the front link member 24 around the first shaft 21 is permitted. In other words, in the initial state of the backrest 3 and seat 4, downward displacement of the backrest 3 is permitted.

[0063] <Connection between the backrest and the front link member> Figure 5 is a perspective view from the front right of the embodiment with the seat body 40 removed. Figure 6 is a cross-sectional perspective view along the line VI-VI in Figure 5. Figure 7 is a cross-sectional perspective view along the line VII-VII in Figure 5. Referring to Figures 5 to 7, the extended portion 35 of the backrest 3 and the backrest connecting portion 24c of the front link member 24 are connected so as not to rotate relative to each other via fastening members such as bolts 46. In the example shown in the figure, the extended portion 35 on one side in the left-right direction and the backrest connecting portion 24c are fixed to each other via a pair of bolts 46 on the left and right sides.

[0064] The second arm portion 37 of the extended portion 35 has a hollow portion 37b into which the backrest connecting portion 24c enters from the inside in the left-right direction. Bolt holes are formed in both the second arm portion 37 and the backrest connecting portion 24c, opening in the vertical direction to allow the male threads of the bolt 46 to pass through. A nut 47 is provided on the lower surface of the backrest connecting portion 24c, into which the bolt 46 is screwed.

[0065] For example, first, the backrest coupling portion 24c is inserted into the hollow portion 37b of the second arm portion 37. Next, in this state, bolts 46 are inserted from above through the relief recesses of the seat support body 42, the bolt holes of the second arm portion 37 and the backrest coupling portion 24c, and screwed into nuts 47. This makes it possible to connect the extended portion 35 of the backrest 3 and the backrest coupling portion 24c of the front link member 24 so that they cannot rotate relative to each other.

[0066] <Positional relationship between the backrest joint and the side panel> Figure 8 is a cross-sectional perspective view along the line VIII-VIII in Figure 5. Figure 9 is a cross-sectional perspective view along the line IX-IX in Figure 5. Referring to Figures 8 and 9, in the front link member 24, the backrest coupling portion 24c protrudes outward in the left-right direction from the side plate portion 24e on which the first support portion 24b and the second support portion 24d are formed. The backrest coupling portion 24c is located in front of the portion of the housing 23 on which the first shaft body 21 is supported (the left and right side wall portions 23a), and protrudes outward in the left-right direction from the left and right side plate portions 24e. The first support portion 24b and the second support portion 24d and the backrest coupling portion 24c are separated in the left-right direction by the side plate portion 24e.

[0067] <Arrangement of link connecting members> Figure 10 is a cross-sectional perspective view along line XX in Figure 5. Referring to Figures 9 and 10, the link connecting member 27 is positioned inward in the left-right direction from the left and right side plate portions 24e on which the first support portion 24b and the second support portion 24d are formed. The front end of the link connecting member 27 is supported by the first shaft body 21. The rear upper end of the link connecting member 27 is supported by the third shaft body 25a. Referring to Figure 5, the link connecting member 27 is positioned inward in the left-right direction from the left and right support wall portions 24f on which the fifth shaft body 26b of the spring mechanism 26 is supported.

[0068] <Positional relationship between the backrest and seat in their initial positions> Figure 11 shows the positional relationship between the first shaft 21 and the second shaft 22 and the cover portion 35a in the initial state of the backrest 3 and seat 4 of the embodiment. The initial state of the backrest 3 and seat 4 corresponds to the state of the chair 1 when the occupant is not seated on the seat 4 and the occupant is not pressing the backrest 3 with their back (the state before reclining). Referring also to Figure 11, in the initial state of the backrest 3 and seat 4, the covering portion 35a of the extended portion 35 of the backrest 3 covers the first shaft body 21 and the second shaft body 22 from the outside in the left-right direction, and also covers a part of the fifth shaft body 26b from the outside in the left-right direction.

[0069] <Positional relationship of the backrest and seat in tilted positions> Figure 12 shows the positional relationship between the first shaft 21 and the second shaft 22 and the cover portion 35a in the tilted state of the backrest 3 and seat 4 of the embodiment. The tilted state of the backrest 3 and seat 4 corresponds to the state of the chair 1 (the state after reclining) in which a person is seated on the seat 4 and the person is pushing against the backrest 3 with their back. In Figure 12, the initial state is shown by a dashed line. Referring also to Figure 12, in the tilted state of the backrest 3 and seat 4, the covering portion 35a of the extended portion 35 of the backrest 3 covers the first shaft body 21 and the second shaft body 22 from the outside in the left-right direction, and also covers a part of the fifth shaft body 26b from the outside in the left-right direction.

[0070] <Backrest reclining motion> Referring to Figures 11 and 12, in the initial state of the chair 1, when a person sits on the seat 4 and leans against the backrest 3, the seating load acting on the backrest 3 is transmitted to the front link member 24 via the extended portion 35 of the backrest 3. As a result, the front link member 24 rotates around the first shaft 21 in the direction of arrow R in Figure 12, causing the entire backrest 3 to rotate backward and downward.

[0071] The rotation of the front link member 24 around the first shaft 21 causes the second shaft 22 to revolve around the first shaft 21. As a result, the front end of the seat 4 rotates backward and upward. Meanwhile, the central part of the seat 4 is connected to the rear of the housing 23 via the seat support member 41, the rear support part 25 (third shaft 25a, fourth shaft 25b, and rear link member 25c), and the link connecting member 27. Therefore, in accordance with the displacement of the front end of the seat 4, the rear link member 25c rotates so that the third shaft 25a revolves around the fourth shaft 25b. As a result, in accordance with the displacement of the front end of the seat 4, the rear end of the seat 4 rotates backward and downward. In the chair 1 of this embodiment, the seat 4 is displaced backward and downward in accordance with the reclining operation of the backrest 3.

[0072] In the chair 1 of this embodiment, when viewed from the left and right in a side view, the distance between the centers of the third axis 25a and the fourth axis 25b is shorter than the distance between the centers of the first axis 21 and the second axis 22. Therefore, the amount of rotation of the seat 4 around the first axis 21 is smaller than the amount of rotation of the backrest 3 around the first axis 21.

[0073] Furthermore, if the seated person moves away from the backrest 3, for example, when the chair 1 is in a tilted state, the seating load acting on the backrest 3 is released. As a result, the front link member 24 rotates around the first shaft 21 in the opposite direction to the arrow R in Figure 12 due to the reaction force of the spring mechanism 26. This returns the backrest 3 and seat 4 to their initial state.

[0074] <Effects and Effects> As described above, the chair 1 of the above embodiment comprises a support structure 2 having a first shaft body 21 extending in the left-right direction and a second shaft body 22 extending in the left-right direction on its front side; a backrest 3 supported by the first shaft body 21 so as to be rotatable about the first shaft body 21 in a side view when viewed from the left-right direction; and a seat 4 positioned above the support structure 2 and supported by the second shaft body 22 so as to be rotatable about the second shaft body 22 in a side view. The backrest 3 comprises a backrest body portion 30 that supports the back of the sitter above the seat 4, and an extension portion 35 that extends from the backrest body portion 30 so as to straddle the seat vertically in a side view on the left-right side of the seat 4 and is connected to the first shaft body 21. The extension portion 35 has a covering portion 35a that covers at least a part of the first shaft body 21 and the second shaft body 22 from the left-right side in a side view. For example, if the extended portion 35 of the backrest 3 does not cover the first shaft 21 and the second shaft 22 from the outside in the left-right direction when viewed from the side, a portion of the support structure 2 with a change in spacing will occur between the portion containing the first shaft 21 and the second shaft 22 and the extended portion 35 of the backrest 3. Therefore, if an object gets caught in this portion, the rotation of the backrest 3 and the seat 4 may be hindered. In contrast, with this configuration, the extended portion 35 of the backrest 3 has a covering portion 35a that covers at least a part of the first shaft body 21 and the second shaft body 22 from the outside in the left-right direction when viewed from the side, so the possibility of objects getting caught is low. Therefore, it is possible to more reliably prevent the rotation of the backrest 3 and the seat 4 from being obstructed.

[0075] In the above embodiment, the support structure 2 comprises a housing 23 that supports the first shaft 21, a front link member 24 having a first support portion 24b that is rotatably supported relative to the first shaft 21, a backrest connecting portion 24c that is non-rotatably coupled to the extended portion 35 of the backrest 3, and a second support portion 24d that supports the second shaft 22. For example, if the backrest 3 and seat 4 rotate independently without being linked, and the amount of rotation of the backrest 3 is greater than the amount of rotation of the seat 4, the backrest 3 will continue to rotate even after the seat 4 has finished rotating. As a result, the backrest 3 may come too close to the seat 4, potentially causing objects to get caught. In contrast, with this configuration, the first support portion 24b of the front link member 24 is supported so as to be rotatable relative to the first shaft body 21 supported by the housing 23, the backrest coupling portion 24c is coupled so as to be non-rotatable relative to the extended portion 35 of the backrest 3, and the second support portion 24d supports the second shaft body 22. As a result, the downward and rearward tilt of the backrest 3 around the first shaft body 21 due to the load input to the backrest 3 and the downward and rearward tilt of the seat 4 around the second shaft body 22 are linked. This prevents the backrest 3 from rapidly approaching the seat 4, further reducing the possibility of objects getting caught. Therefore, it is possible to more reliably prevent the rotation of the backrest 3 and seat 4 from being hindered.

[0076] In the above embodiment, in a side view, the first shaft body 21 is positioned below the second shaft body 22. With this configuration, the movement of the front link member 24 becomes smoother compared to the case where the first shaft body 21 is positioned above the second shaft body 22 in a side view, and therefore the linkage between the backrest 3 and the seat 4 also becomes smoother.

[0077] In the above embodiment, the backrest connecting portion 24c protrudes outward in the left-right direction relative to the first support portion 24b and the second support portion 24d. With this configuration, compared to the case where the entire backrest coupling portion 24c is positioned inward in the left-right direction relative to the first support portion 24b and the second support portion 24d, it is easier to connect the backrest coupling portion 24c of the front link member 24 to the extended portion 35 of the backrest 3 in the process after the front link member 24 is supported by the housing 23.

[0078] In the above embodiment, the front link member 24 has a first support portion 24b and a second support portion 24d formed thereon, and a side plate portion 24e whose left-right direction is the thickness direction. The backrest connecting portion 24c protrudes outward in the left-right direction from the side plate portion 24e. In this configuration, the first support portion 24b and the second support portion 24d and the backrest connecting portion 24c are separated in the left-right direction by the side plate portion 24e. Therefore, the possibility of the backrest 3 protruding toward the first support portion 24b and the second support portion 24d and causing adverse effects is low.

[0079] In the above embodiment, the support structure 2 further includes a rear support portion 25 that supports the central part of the seat 4 from below. With this configuration, the central part of the seat 4 is supported from below by the rear support 25, which prevents the seat 4 from being displaced too far downward even when it tilts downward and rearward around the second shaft 22. Therefore, the effects of changes in the relative angle during rotation of the backrest 3 and the seat 4 can be reduced.

[0080] In the above embodiment, the rear support portion 25 includes a third shaft body 25a extending in the left-right direction behind the first shaft body 21, a fourth shaft body 25b extending in the left-right direction above the third shaft body 25a and supporting the central part of the seat 4, and a rear link member 25c whose lower end is supported by the third shaft body 25a and whose upper end is supported by the fourth shaft body 25b. With this configuration, the central part of the seat 4 is supported by the rear link member 25c, so even when the seat 4 tilts downward and rearward around the second shaft body 22, it tilts while being constrained by the four-bar linkage formed by the front link member 24 and the rear link member 25c. Therefore, excessive downward displacement of the seat 4 can be more reliably suppressed. Consequently, the effects of changes in the relative angle during rotation of the backrest 3 and the seat 4 can be more reliably reduced.

[0081] In the above embodiment, in a side view, at least a portion of the third shaft 25a is positioned forward of the fourth shaft 25b. In the initial state of the backrest 3 and seat 4, at least the upper end portion of the rear link member 25c is inclined rearward and upward in a side view. With this configuration, at least the upper end portion of the rear link member 25c is inclined rearward and upward in the initial state, so when the seat 4 tilts rearward and downward around the second shaft body 22, it is prevented from rotating upward. Therefore, the rearward and downward tilting of the seat 4 around the second shaft body 22 becomes smoother.

[0082] <Variation> In the above embodiment, the second shaft body was described as extending linearly in the left-right direction parallel to the first shaft body, but the invention is not limited to this. For example, the second shaft body may be arranged coaxially with the first shaft body. For example, at least a portion of the second shaft body may be arranged so as to overlap with the first shaft body when viewed from the left-right direction in a side view. The arrangement of the first and second shaft bodies can be changed according to the design specifications.

[0083] In the above embodiment, the support structure was described with an example comprising a housing that supports a first shaft body, a front link member having a first support portion supported so as to be rotatable relative to the first shaft body, a backrest coupling portion coupled so as to be non-rotatable relative to the extended portion of the backrest, and a second support portion that supports a second shaft body, but is not limited to this. For example, the front link member does not have to have a first support portion supported so as to be rotatable relative to the first shaft body. For example, the backrest and the seat may rotate independently without being linked. For example, the support structure may be configured with the first shaft body and the second shaft body on the front side so that the backrest and the seat rotate independently of each other. The configuration of the support structure can be changed according to the design specifications.

[0084] In the above embodiment, an example was given in which the first shaft is positioned below the second shaft in a side view, but the embodiment is not limited to this. For example, the first shaft may be positioned above the second shaft in a side view. The vertical positional relationship between the first shaft and the second shaft can be changed according to the design specifications. The first shaft and the second shaft may be positioned on the same axis, and the amount of rotation of the backrest relative to the first shaft and the amount of rotation of the seat relative to the second shaft may be configured to be different.

[0085] In the above embodiment, the backrest connecting portion was described as protruding outward in the left-right direction relative to the first support portion and the second support portion, but it is not limited to this. For example, the backrest connecting portion does not have to protrude outward in the left-right direction relative to the first support portion and the second support portion. For example, the entire backrest connecting portion may be positioned inward in the left-right direction relative to the first support portion and the second support portion. The left-right positional relationship between the first support portion, the second support portion and the backrest connecting portion can be changed according to the design specifications.

[0086] In the above embodiment, the front link member was described as having a first support portion and a second support portion formed thereon, and a side plate portion with the left-right direction being the thickness direction, and the backrest coupling portion protruding outward in the left-right direction from the side plate portion, but it is not limited to this. For example, the first support portion and the second support portion may be formed on a member other than the side plate portion. For example, the backrest coupling portion does not have to protrude outward in the left-right direction from the side plate portion. For example, the entire backrest coupling portion may be positioned inward in the left-right direction relative to the side plate portion. The left-right positional relationship between the side plate portion and the backrest coupling portion can be changed according to the design specifications.

[0087] In the above embodiment, the support structure was described as further comprising a rear support portion that supports the central part of the seat from below, but it is not limited to this. For example, the rear support portion may support the rear part of the seat from below. The rear support portion only needs to support the part of the seat that is rearward from the part supported by the second shaft from below. For example, the support structure does not need to have a rear support portion. The installation method of the rear support portion can be changed according to the design specifications.

[0088] In the above embodiment, the rear support portion was described as having a third shaft extending laterally behind the first shaft, a fourth shaft extending laterally above the third shaft and supporting the central part of the seat, and a rear link member whose lower end is supported by the third shaft and whose upper end is supported by the fourth shaft, but it is not limited to this. For example, the fourth shaft (rear link member) may support the rear part of the seat from below. The fourth shaft (rear link member) only needs to support the part of the seat that is rearward from the part supported by the second shaft from below. For example, the rear support portion does not need to have a rear link member. For example, the rear support portion may be configured with an expandable / contractable member (e.g., an elastic member such as a spring). The configuration of the rear support portion can be changed according to the design specifications.

[0089] In the above embodiment, in a side view, the third shaft is positioned in front of the fourth shaft, and in the initial state of the backrest and seat, at least the upper end portion of the rear link member is inclined rearward and upward in a side view. However, the embodiment is not limited to this. For example, in a side view, the third shaft may be positioned after the fourth shaft. For example, in the initial state of the backrest and seat, at least the upper end portion of the rear link member may extend upward in a side view, or it may be inclined forward and upward. The front-rear positional relationship between the third shaft and the fourth shaft, and the manner in which the rear link member extends in the initial state of the backrest and seat, can be changed according to the design specifications.

[0090] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and additions, omissions, substitutions, and other modifications of the configuration are possible without departing from the spirit of the invention, and the above-described modifications can be combined as appropriate. [Explanation of Symbols]

[0091] 1…Chair 2...Support structure 3...backrest 4…za 21...First Axis Body 22...Second Axis Body 23… Housing 24…Front link member 24b...First support part 24c...backrest joint 24d…Second support part 24e...Side plate part 25...Rear support part 25a…Third axis body 25b…4th axis body 25c... Rear link component 30...Backrest main body 35...Extension part 35a... Covering part

Claims

1. A support structure having a first shaft body extending in the left-right direction and a second shaft body extending in the left-right direction on its front side, In the aforementioned side view from the left and right directions, a backrest is supported by the first shaft so as to be rotatable about the first shaft, The support structure comprises a seat positioned above the support structure and supported by the second shaft so as to be rotatable about the second shaft in a side view, The aforementioned backrest is, A backrest body that supports the seated person's back above the aforementioned seat, The backrest body extends from the main body so as to straddle the seat vertically in a side view, with respect to the seat, and is connected to the first shaft body, The extended portion has a covering portion that covers at least a part of the first shaft and the second shaft from the outside in the left-right direction in the side view. chair.

2. The aforementioned support structure is A housing supporting the aforementioned first shaft, A front link member comprising: a first support portion supported so as to be rotatable relative to the first shaft; a backrest connecting portion coupled so as not to be rotatable relative to the extended portion of the backrest; and a second support portion supporting the second shaft, The chair according to claim 1.

3. In the aforementioned side view, the first shaft is positioned below the second shaft. The chair according to claim 2.

4. The backrest connecting portion protrudes outward in the left-right direction relative to the first support portion and the second support portion. The chair according to claim 2 or 3.

5. The aforementioned front link member has the first support portion and the second support portion formed thereon, and side plate portions whose left-right direction is the thickness direction, The aforementioned backrest connecting portion protrudes outward from the side plate portion in the left-right direction. The chair according to claim 4.

6. The support structure further comprises a rear support portion that supports the portion of the seat that is rearward from the portion supported by the second shaft body from below. The chair according to any one of claims 1 to 3.

7. The rear support portion includes a third shaft extending in the left-right direction behind the first shaft, a fourth shaft extending in the left-right direction above the third shaft and supporting the portion behind the part supported by the second shaft at the seat, and a rear link member whose lower end is supported by the third shaft and whose upper end is supported by the fourth shaft. The chair according to claim 6.

8. In the aforementioned side view, at least a portion of the third shaft is positioned forward of the fourth shaft. In the initial state of the backrest and the seat, at least the upper end portion of the rear link member is inclined rearward and upward in the side view. The chair according to claim 7.

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