Chair

Abstract

To provide a chair capable of being easily put in a usable state by erecting a load receiving functional part of a backrest in a reclining state or the like.SOLUTION: A chair includes a support structure, and a load receiving functional part capable of being switched between a reclining state and a standing state. The load receiving functional part includes a load receiving body, a shaft part, and a locked part. The support structure includes a stopper part. The stopper part can be displaced between a first position permitting displacement from a reclining corresponding position to a standing corresponding position of the locked part when the locked part is in a reclining corresponding position, and a second position positioned on a rotation orbit of the locked part, and restricting displacement from a standing corresponding position to a reclining corresponding position of the locked part when the locked part is in a standing corresponding position. The stopper part is energized in a second position direction in a state of being in the first position, is restricted in displacement to the second position by the locked part, and is released from displacement restriction to the second position by rotation displacement to a standing corresponding position of the locked part.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Some office chairs have a backrest whose lower end is rotatably supported on a support base attached to the underside of the seat. However, because the backrest of this type of chair rises upward from the rear of the seat, the chair becomes bulky and difficult to store when stored in a store or factory storage room or when transporting the chair.

[0003] To address this issue, a chair has been devised that allows the backrest (load-receiving functional part) to be reclined (for example, reclined so that the backrest is close to the seat) when storing or transporting the chair before the user actually uses it (see Patent Document 1).

[0004] In the chair described in Patent Document 1, the shaft at the lower end of the backrest is rotatably supported on a support base below the seat body. The backrest is switchable between a lying position in which the backrest main body (the portion that the back of the seated person abuts) is close to the seat surface of the seat body, and an upright position in which the backrest main body stands up from the rear of the seat surface. A locking portion is provided on the shaft at the lower end of the backrest so that it can rotate integrally with the shaft, and a stopper member is provided within the support base so that it can abut against the locking portion. The stopper member is displaceable between a position where it intersects with the rotation path of the locking portion on the backrest side and a position where it is retracted from the rotation path of the locking portion. The stopper member can be fixed in position by a screw at the position where it intersects with the rotation path of the locking portion.

[0005] In the chair described in Patent Document 1, the backrest is in a reclined position during storage, transportation, etc., and the stopper member is positioned to retract from the rotation path of the locked portion in this state. When the user actually assembles and uses the chair, the backrest is moved from the reclined position to an upright position. At this time, the stopper member is positioned to retract from the rotation path of the locked portion of the backrest, allowing the backrest to be raised. In this state, the user displaces the stopper member to a position where it intersects with the rotation path of the locked portion and fixes it with a screw. As a result, the rotational displacement of the backrest in the reclining direction is restricted by the stopper member, and the backrest is maintained in an upright position. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-275363 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the chair described in Patent Document 1, when assembling, after switching the backrest from a reclined position to an upright position, a person must displace the stopper member to a position where it intersects with the rotation path of the locked part, and then fix the stopper member in position with a screw in that state. This makes the work of getting the backrest into a usable state complicated, and an improvement in this respect is desired.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a chair in which a load-receiving functional part such as a backrest that is in a collapsed state can be raised to a usable state with ease. [Means for solving the problem]

[0009] In order to solve the above problems, the chair according to the present invention employs the following configuration. That is, the chair according to the present invention comprises a support structure, and a load receiving functional part rotatably supported by the support structure and switchable between a lying down state and an upright state, the load receiving functional part comprising a load receiving main body part that receives the load of a seated person, a shaft part that rotates integrally with the load receiving main body part and is rotatably supported by the support structure, and an engaged part that rotates integrally with the shaft part, and the support structure is configured such that when the rotation position of the engaged part when the load receiving main body part is in the lying down state is a lying-down corresponding position, and when the rotation position of the engaged part when the load receiving main body part is in the upright state is a standing-up corresponding position, the engaged part is in the lying down corresponding position. and a stopper portion that is disposed so as to be displaceable between a first position that allows the engaged portion to be displaced from the lying-down corresponding position to the standing-up corresponding position when the engaged portion is in the standing-up corresponding position, and a second position that is located on the rotation path of the engaged portion and restricts the displacement of the engaged portion from the standing-up corresponding position to the lying-down corresponding position when the engaged portion is in the standing-up corresponding position, and the stopper portion is biased toward the second position when in the first position, and is restricted from displacement to the second position by the engaged portion, and the restriction on displacement to the second position is released by the rotational displacement of the engaged portion to the standing-up corresponding position.

[0010] With the above configuration, when the load-receiving functional part is in a collapsed state, the locked part of the load-receiving functional part is located in the collapsed corresponding position. At this time, the stopper part on the support structure side is in the first position and is biased toward the second position, and displacement to the second position is restricted by the locked part. When the load-receiving functional part is brought into an upright state from this state, the locked part of the load-receiving functional part is pivotally displaced to the upright corresponding position. This releases the restriction of displacement of the stopper part to the second position by the locked part. As a result, the stopper part is displaced to the second position by the biasing force acting on the stopper part, and the stopper part restricts displacement of the locked part toward the collapsed corresponding position (displacement of the load-receiving functional part in the collapsed direction). Therefore, in a chair employing this configuration, the load-receiving functional part, which is in a collapsed state, can be maintained in an upright state simply by rotating it in the upright direction, without the worker having to perform any other special operations.

[0011] The stopper portion may be rotatably supported by the support structure, and when in the first position, it abuts against the engaged portion in an inclined position in which a rotational biasing force due to its own weight functions, thereby restricting rotational displacement to the second position, and the restriction on displacement to the second position may be released by rotational displacement of the engaged portion to the upright corresponding position.

[0012] In this case, the stopper portion, which is rotatably supported on the support structure, abuts against the locked portion in an inclined position when in the first position, thereby restricting rotation to the second position due to its own weight by the locked portion. Then, when the locked portion rotates in response to the raising operation of the load-receiving functional portion, the stopper portion is displaced to the second position due to its own weight. Therefore, without providing a dedicated biasing member, it is possible to restrict the load-receiving functional portion from returning to its collapsed position after the raising operation of the load-receiving functional portion. Therefore, when this configuration is adopted, the overall structure of the chair can be simplified, resulting in a smaller and lighter chair.

[0013] The load-receiving functional portion may be a backrest that supports the back of the seated occupant, and the support structure may support a cushion unit that receives rearward loads acting on the backrest, and the engaging portion may engage with the cushion unit so as to transmit the load when it displaces beyond the second position in a direction away from the first position.

[0014] In this case, the cushion unit that receives the rear load of the backrest is supported on the support structure, and when the backrest is in the upright position during assembly of the chair, the locking portion on the backrest engages with the cushion unit so as to transmit the load. This simplifies the structure of the backrest shaft compared to when the cushion unit is incorporated into the backrest shaft. Furthermore, when this configuration is adopted, the backrest and cushion unit can be linked using the locking portion that prevents the backrest from returning to its reclining position, thereby reducing the number of parts. [Effects of the Invention]

[0015] In the chair according to the present invention, when the load-receiving functional part in a lying down state is rotated in an upright direction, the restriction of displacement of the stopper part to the second position by the locked part is released, and the stopper part is automatically displaced to the second position by the biasing force acting on the stopper part. Therefore, by the simple operation of rotating the load-receiving functional part in a lying down state in an upright direction, it is possible to restrict the displacement of the load-receiving functional part in the lying down direction. Therefore, when the chair according to the present invention is used, the load-receiving functional part in a lying down state can be easily raised to a usable state. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view of a chair according to an embodiment of the present invention with the backrest in an upright position. [Figure 2] 1 is a perspective view of a chair according to an embodiment of the present invention with the backrest reclined; [Figure 3] 1 is a perspective view of a chair according to an embodiment of the present invention, with some components removed, viewed from below. FIG. [Figure 4] FIG. 1 is a perspective view of a chair according to an embodiment of the present invention with the seat removed. [Figure 5] FIG. 1 is a bottom view of a chair according to an embodiment of the present invention, with some components removed and part of the chair viewed from below. [Figure 6] FIG. 10 is a perspective view of the switching mechanism when the backrest of the embodiment of the present invention is in a reclined state. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 5. [Figure 9] FIG. 10 is a perspective view of the switching mechanism when the backrest of the embodiment of the present invention is in an upright position. [Figure 10] 8 is a cross-sectional view corresponding to FIG. 7 when the backrest of the embodiment of the present invention is in an upright position. [Figure 11] 9 is a cross-sectional view corresponding to FIG. 8 when the backrest of the embodiment of the present invention is in an upright position. [Figure 12] 11 is a view taken along the arrow XII in FIG. 5 when the backrest of the embodiment of the present invention is in an upright state. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the front of a person seated in a normal posture on chair 1 will be referred to as "front," and the opposite side will be referred to as "rear." Furthermore, with regard to "upper," "lower," "left," and "right," the upper side of a person seated in a normal posture on chair 1 will be referred to as "upper," the opposite side will be referred to as "lower," and the left side of a person seated in a normal posture on chair 1 will be referred to as "left." In the drawings, an arrow FR points forward, an arrow UP points upward, and an arrow LH points left.

[0018] FIG. 1 is a view of a chair 1 according to this embodiment as seen from above and to the front left. Chair 1 according to this embodiment comprises legs 10 placed on the floor, a support base 11 (see FIG. 3) installed at the upper ends of legs 10, a seat 12 attached to the top of support base 11 to support the buttocks of a seated person, and a backrest 13 that rises upward from the rear of seat 12 to support the back of the seated person. Backrest 13 is rotatably supported on support base 11. Backrest 13 has a back support member 20 that directly supports the weight of the seated person's back. Chair 1 according to this embodiment is switchable between an upright state in which back support member 20 rises upward from the rear of seat 12, and a reclined state in which back support member 20 is reclined forward. Chair 1 is assembled so that it is in the upright state when used by a user, and is in the reclined state when transported or stored before assembly. In this embodiment, the legs 10 and the support base 11 form a support structure. The backrest 13 forms a load-receiving functional part that receives the weight of a seated person, and the back support member 20 forms a load-receiving main body part.

[0019] Fig. 2 is a view of the chair 1 in a reclined position as seen from the upper left front, and Fig. 3 is a view of the chair 1 as seen from the lower front with the lower cover 21 (see Fig. 4) that covers the lower parts of the seat 12 and base 11 removed. The leg 10 includes a multi-leg 14 with casters 14a, and a base 15 that stands up from the center of the multi-leg 14 and has a built-in gas spring as a lifting mechanism, with a base 11 attached to the upper end of the base 15. The chair 1 according to this embodiment can be freely moved on the floor by rolling the casters 14a at the lower ends of the multi-leg 14 on the floor. However, it is not necessary to provide the casters 14a at the lower ends of the multi-leg 14. In addition, reference numeral 16 in the figure denotes an operating lever for adjusting the elevation height of the leg column 15.

[0020] FIG. 4 is a view of the chair 1 with the seat 12 removed, seen from above and to the front left. As shown in Figures 3 and 4, the base 11 is formed in a horizontally elongated (left-right) box shape that opens downward. A leg connecting portion 22, to which the upper end of the leg column 15 is connected, is provided in the center of the width direction (left-right direction) of the horizontally elongated base 11. Furthermore, recessed portions 23 that extend long in the front-rear direction and open downward are provided on both sides of the width direction of the base 11. Each of the left and right recessed portions 23 is surrounded by an upper wall 11u of the outer shell of the base 11, an outer side wall 11s, an inner side wall 24 that is spaced a predetermined distance inward in the width direction from the outer side wall 11s, and a front wall 11f and a rear wall 11r of the outer shell of the base 11. The front and rear ends of the inner side wall 24 are connected to the front wall 11f and the rear wall 11r. Each of the left and right recessed portions 23 houses a cushion unit 30 for elastically supporting the rear load acting on the backrest 13 from the back of the seated person, and a part of a switching mechanism 40 for switching the backrest 13 between a reclined state and an upright state.

[0021] 4, portions of the left and right recessed portions 23 of the base 11 bulge upward relative to the central region of the top wall 11u of the base 11. Hereinafter, the portions of the recessed portions 23 that bulge upward relative to the central region of the top wall 11u of the base 11 will be referred to as bulging portions 23e. A recessed portion 25 that is recessed downward is formed in approximately the center of the upper surface of the top wall 11u of the base 11. The recessed portion 25 accommodates a lift adjustment portion 26 that protrudes upward from the upper end of the leg 15 and a base end portion 16b of the operating lever 16 that presses down the lift adjustment portion 26.

[0022] The seat 12 comprises a seat frame 12A (see Fig. 3) made of hard resin and having a substantially rectangular shape when viewed from above, a cushion member 19 (see Fig. 8) placed on the upper part of the seat frame 12A, and a cover material 21B that covers the upper surface of the cushion member 19 and the outer periphery of the seat frame 12A. The support base 11 is attached integrally to the central region in the front-to-rear direction of the underside of the seat frame 12A by screws or the like.

[0023] The backrest 13 includes a back support member 20, a backrest frame 27 that is substantially U-shaped in a front view and supports the back support member 20, and a pair of shafts 28 provided at the left and right ends of the backrest frame 27. As shown in Fig. 4, the axis o of each of the left and right shafts 28 extends substantially horizontally along the width direction of the chair (left-right direction). The left and right shafts 28 are rotatably supported on the left and right side portions of the support base 11 near the rear, below the seat 12.

[0024] The back support member 20 is formed in a horizontally elongated, approximately oval shape when viewed from the front, with the central region in the chair width direction curved to encase the back of the seated occupant. The back support member 20 is fixed to the central region of a substantially U-shaped backrest frame 27. Short-axis cylindrical boss portions 29 facing inward in the chair width direction are formed integrally with the left and right ends of the backrest frame 27. The left and right shaft portions 28 are coaxially fixed to the corresponding left and right boss portions 29 of the backrest frame 27. The shaft portions 28 are fixed to the corresponding left and right boss portions 29 so as to be rotatable integrally therewith.

[0025] Fig. 5 is a view from below of a portion of the right side of chair 1 with lower cover 21 removed. In Fig. 5, backrest 13 is in a reclined position. Fig. 6 is a perspective view of switching mechanism 40 when backrest 13 is in a reclined position. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 5, and Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 5. The left and right recessed portions 23 of the support base 11 and the cushion unit 30 and switching mechanism 40 housed therein have the same structure on both sides. The left and right shafts 28 of the backrest 13 penetrate the outer side wall 11s and inner side wall 24 of the corresponding left and right recessed portions 23 and are rotatably supported by the outer side wall 11s and inner side wall 24 in this state. As shown in FIG. 6 , the shafts 28 have a pair of cylindrical guide portions 28a (supported portions) slidably supported in respective through-holes (not shown) in the outer side wall 11s and inner side wall 24, and a rectangular connecting portion 28b connecting the pair of guide portions 28a. A lever piece 41, which serves as a locked portion, is attached to the connecting portion 28b. The lever piece 41 is made of a rectangular plate material of a predetermined thickness. A rectangular connecting hole 41a into which the connecting portion 28b is press-fitted in the thickness direction is formed at one end side (hereinafter referred to as the "base side") of the lever piece 41 in the longitudinal direction. A substantially U-shaped notched groove 41b that opens to one side in the short length direction is formed at the other end side (hereinafter referred to as the "tip side") of the lever piece 41 in the longitudinal direction.

[0026] The switching mechanism 40 is mainly composed of a lever piece 41, which is a portion to be locked, and a stopper piece 45, which will be described later, which is a stopper portion. The base side of the lever piece 41 is press-fitted into the connecting portion 28b of the shaft portion 28, allowing it to rotate integrally with the shaft portion 28. The lever piece 41 is disposed inside the recessed portion 23 when the shaft portion 28 is supported by the outer side wall 11s and the inner side wall 24 of the recessed portion 23 via a pair of guide portions 28a. The lever piece 41 is rotatable between an initial rotation position shown by a solid line in FIG. 7 and an in-use rotation position shown by a dotted line in FIG. 7. The initial rotation position is the rotation position of the lever piece 41 when the backrest 13 is in a reclined state. The initial rotation position is the reclining position of the lever piece 41 (the latched portion). Hereinafter, the initial rotation position will be referred to as the "reclining position." The in-use rotation position is the rotation position of the lever piece 41 when the backrest 13 is in an upright state. The in-use rotation position is a position corresponding to the standing up of the lever piece 41 (the locked portion). Hereinafter, the in-use rotation position will be referred to as the "standing up position." In the lying-down position, the lever piece 41 is in a substantially horizontal position with the tip facing toward the rear of the chair, whereas in the standing-up position, the lever piece 41 is in a position with the tip facing vertically downward.

[0027] 5, a notch 42 that opens downward is provided in a rearward portion of the inner side wall 24 of the recessed portion 23. The notch 42 is formed slightly rearward of the position of the shaft 28 of the backrest 13. A base member 43 is fixed by screws or the like to the lower surface of the upper wall 11u of the base 11 at a position inside the notch 42 in the chair width direction. The base member 43 has a general shape in which a substantially U-shaped cross section continues in the width direction of the chair. Hereinafter, with respect to the base member 43, the direction in which the substantially U-shaped cross section extends will be referred to as the "longitudinal direction." Also, the wall located on the opposite side of the opening of the substantially U-shaped section will be referred to as the "top wall 43t." The top wall 43t of the base member 43 is fixed to the upper wall 11u of the support base 11 so that one end face in the longitudinal direction abuts against the inner side wall 24.

[0028] 6, the upper portion of one longitudinal end of the base member 43 (the top wall 43t and the upper portions of the front and rear side walls) is cut out, and the cutout portions in the upper portions of the front and rear side walls serve as shaft support portions 43h. A stopper piece 45, which will be described later, is rotatably supported on the shaft support portion 43h.

[0029] As shown in Fig. 6, the stopper piece 45 includes a rectangular pillar-shaped stopper main body 45a, a bulging portion 45b that bulges outward in a semicircular shape from the top surface of the stopper main body 45a at a position offset to one side from the longitudinal center of the stopper main body 45a, and a support shaft 45c that protrudes forward and rearward from the arc center of the bulging portion 45b. The bulging portion 45b has a semicircular cross section that extends in the front-to-rear direction. Hereinafter, the end of the stopper main body 45a that is longer in the longitudinal direction relative to the bulging portion 45b will be referred to as the "operating end 45ao," and the end of the stopper main body 45a that is shorter in the longitudinal direction will be referred to as the "restricting end 45ar."

[0030] The front-to-rear width of the stopper main body 45a and the bulging portion 45b is narrower than the separation width between the front wall and rear wall of the base member 43. The stopper piece 45 is housed between the front wall and rear wall of the base member 43, with the bulging portion 45b and the restricting end 45ar side of the stopper main body 45a, and in this state, the support shaft 45c is rotatably supported by the shaft support portion 43h of the base member 43. The bulging portion 45b abuts against the front wall and rear wall of the base member 43, thereby restricting displacement of the stopper piece 45 in the front-to-rear direction.

[0031] Fig. 9 is a perspective view of the switching mechanism 40 when the backrest 13 is in the upright position. Fig. 10 is a cross-sectional view similar to Fig. 7 when the backrest 13 is in the upright position, and Fig. 11 is a cross-sectional view similar to Fig. 8 when the backrest 13 is in the upright position. The stopper piece 45 is rotatable about the support shaft 45c between a first position shown in Figures 6 to 8 and a second position shown in Figures 9 to 11. The first position is a rotational position where the operating end 45ao side of the stopper main body 45a is inclined upward at a predetermined angle outward in the chair width direction. The second position is a rotational position where the stopper main body 45a is approximately horizontal.

[0032] Here, the support shaft 45c of the stopper piece 45 is positioned toward the restricting end 45ar from the longitudinal center position of the stopper main body 45a. Therefore, when the stopper main body 45a is in the first position in an inclined posture, the center of gravity G of the stopper main body 45a is positioned above the support shaft 45c and outward in the chair width direction, as shown in Fig. 8. Therefore, the weight of the stopper piece 45 in the first position acts as a biasing force toward the second position.

[0033] The stopper piece 45 is arranged so that the rotation path of the stopper body 45a centered on the support shaft 45c intersects with the rotation path of the lever piece 41 centered on the shaft 28 of the backrest 13 within the recessed portion 23. The operating end 45ao side of the stopper body 45a is displaced from the first position to the second position through the notch 42 (see FIG. 5) in the inner side wall 24.

[0034] When the backrest 13 is in a reclined position and the lever piece 41 is in the reclining position, the stopper piece 45 is in the first position, where the operating end 45ao of the stopper body portion 45a abuts against the flat side surface of the lever piece 41, which is in a horizontal position. This restricts rotation of the stopper piece 45 due to its own weight, and the stopper piece 45 is maintained in the first rotation position. At this time, the operating end 45ao of the stopper piece 45 abuts against the flat side surface of the lever piece 41 with only a weak force (its own weight), so the rotational displacement of the lever piece 41 from the reclining position to the standing position is not restricted by the stopper piece 45 (the rotational displacement is permitted). Therefore, when the stopper piece 45 is in the first rotation position, the lever piece 41, which is in the reclining position, is permitted to move to the standing position, and as a result, the backrest 13 can be operated from the reclined state to the standing state. Note that the rotational displacement of the stopper piece 45 in the first position in the direction opposite to the second position is restricted by the inner wall of the bulging portion 23e of the support base 11 shown in FIG.

[0035] As shown in FIGS. 9 to 11 , when the backrest 13 is moved from its reclined position to its upright position, the lever piece 41 on the backrest 13 side pivots from the reclining position toward the upright position. This causes the stopper piece 45 to pivot to a position where the operating end 45ao faces vertically downward, and the restriction on the rotation of the stopper piece 45 by the lever piece 41 is released. As a result, the stopper body 45a of the stopper piece 45 pivots from the first position to the second position and is maintained in a substantially horizontal position. At this time, the operating end 45ao of the stopper body 45a abuts or stops in close proximity to the rear surface of the tip end of the lever piece 41 facing vertically downward. The stopper body 45a is positioned on the pivot path of the lever piece 41, at the rear side of the lower end of the lever piece 41. This restricts the rotation of the lever piece 41 from the upright position toward the reclining position by the stopper piece 45. As a result, the backrest 13 is maintained in an upright position. When the stopper piece 45 is rotated to the second rotation position, the restricting end 45ar of the stopper main body 45a abuts against the underside of the top wall 43t of the base member 43, thereby restricting excessive rotation beyond the substantially horizontal position. Furthermore, a wall provided in the recessed portion 23 is positioned close to the rear portion of the stopper piece 45 that has been rotated to the second rotation position. Therefore, when an excessive load acts from the lever piece 41 on the stopper piece 45 in the direction toward the folding corresponding position, the rear surface of the stopper piece 45 abuts against the wall of the recessed portion 23, thereby reliably restricting the displacement of the lever piece 41 to the folding corresponding position (displacement of the backrest 13 in the folding direction).

[0036] FIG. 12 is a view taken along the arrow XII in FIG. 5 when the backrest 13 is in an upright position. 5, 7, and 12, the cushion unit 30 is disposed below the shaft portion 28 within the recessed portion 23 of the support base 11. The cushion unit 30 includes a coil spring 32 which is an elastic member, a guide shaft 31 disposed inside the coil spring 32, a first spring seat block 33 slidably mounted on the front side of the guide shaft 31, and a second spring seat block 34 slidably mounted on the rear side of the guide shaft 31.

[0037] The first spring seat block 33 has a guide tube 33a into which the front end of the guide shaft 31 is inserted from one end, a spring receiving flange 33f integrally formed on the other end of the guide tube 33a, a pair of shaft support walls 33b protruding forward from the spring receiving flange 33f, and a front shaft 33c supported by the pair of shaft support walls 33b. With one end of the guide shaft 31 inserted inside the guide tube 33a, the guide tube 33a is inserted into the inside of the coil spring 32 together with the guide shaft 31. The spring receiving flange 33f abuts against the front end face of the coil spring 32 and receives the reaction force of the coil spring 32. The front shaft 33c supported by the pair of shaft support walls 33b extends in the chair width direction, which is perpendicular to the axial direction of the guide tube 33a. Both ends of the front shaft 33c are rotatably supported by the front end regions of the left and right walls (the inner side wall 24 and the outer side wall 11s) of the recessed portion 23 of the support base 11.

[0038] The second spring seat block 34 has a guide cylinder 34a into which the rear end of the guide shaft 31 is inserted from one end side, a spring receiving flange 34f formed integrally with the other end side of the guide cylinder 34a, a pair of shaft support walls 34b protruding rearward from the spring receiving flange 34f, and a rear shaft 34c supported by the pair of shaft support walls 34b. The guide cylinder 34a, spring receiving flange 34f, shaft support walls 34b, and rear shaft 34c of the second spring seat block 34 have substantially the same structure and function as the guide cylinder 33a, spring receiving flange 33f, shaft support walls 33b, and front shaft 33c of the first spring seat block 33, except that they are oriented in the opposite front-to-rear direction.

[0039] However, both ends of the rear shaft 34c are supported rotatably and slidably in the front-rear direction by sliding bearings 35 in the rear regions of the left and right walls (the inner side wall 24 and the outer side wall 11s) of the recessed portion 23. As shown in FIG. 12, the support position of the rear shaft 34c by the sliding bearings 35 is located approximately directly below the support position of the shaft 28 of the backrest 13 on the left and right walls of the recessed portion 23. The front end of the cushion unit 30 on the front shaft 33c side is a fixed end, and the rear end on the rear shaft 34c side is a free end. The rear end of the cushion unit 30 (rear shaft 34c) is movable in the front-rear direction within the range of the elongated bearing hole 35a (see FIG. 12) of the sliding bearing 35. The bearing hole 35a is formed in an arc shape centered on the support position (axis center o) of the shaft 28 of the backrest 13. In the initial state where the cushion unit 30 is assembled in the recessed portion 23, the rear shaft 34c is positioned slightly forward from the rear end of the bearing hole 35a. When a load acts on the rear shaft 34c in the forward direction from this state, the coil spring 32 is compressed via the second spring seat block 33.

[0040] When the backrest 13 is operated to an upright position and the lever piece 41 is accordingly rotated to the second position (the position where the tip of the lever piece 41 faces vertically downward) as described above, the rear shaft 34c of the cushion unit 30 is inserted into the notched groove 41b formed in the lever piece 41. At this time, when the bottom of the notched groove 41b abuts against the outer peripheral surface of the rear shaft 34c, the rearward load of the backrest 13 can be input to the cushion unit 30 through the lever piece 41. Therefore, when the backrest 13 is switched to the upright position by the switching mechanism 40 in response to the upright operation of the backrest 13, the rearward load acting on the backrest 13 is absorbed by the cushion unit 30. Furthermore, when the backrest 13 is displaced rearward (tilted backward) beyond the initial upright position, the elastic force of the cushion unit 30 returns the backrest 13 to the initial upright position.

[0041] As described above, in the chair 1 of this embodiment, when the backrest 13 in the reclined state is rotated in the upright direction, the restriction on the displacement of the stopper piece 45 to the second position by the lever piece 41 (locked portion) of the switching mechanism 40 is released, and the stopper piece 45 automatically rotates to the second position due to the biasing force of its own weight. As a result, the stopper body portion 45a of the stopper piece 45 stops at a position behind the lower end of the lever piece 41, and the displacement of the lever piece 41 toward the reclined position is restricted by the stopper body portion 45a. Therefore, in the chair 1 of this embodiment, the backrest 13 can be maintained in an upright state simply by rotating the backrest 13 from a reclined state in the upright direction without the worker having to perform any other special operation. Therefore, when the chair 1 of this embodiment is employed, the backrest 13 can be easily raised from a reclined state to be usable.

[0042] In particular, in the chair 1 of this embodiment, the stopper piece 45 is rotatably supported on the base 11 (support structure), and when the stopper piece 45 is in the first position, it abuts against the lever piece 41 (engaged portion) in an inclined position in which the rotational biasing force due to its own weight functions, thereby restricting rotational displacement to the second position. The stopper piece 45 is then released from the restriction on displacement to the second position when the lever piece 41 is rotated to the standing-up position. Therefore, in the case of the chair 1 of this embodiment, it is possible to restrict the return of the backrest 13 in the collapsed direction during the standing operation of the backrest 13 without providing a dedicated biasing member. Therefore, when the chair 1 of this embodiment is adopted, the structure of the entire chair 1 can be simplified, and the chair can be made smaller and lighter accordingly.

[0043] Furthermore, in the chair 1 of this embodiment, a cushion unit 30 that receives a rearward load acting on the backrest 13 is supported on the support base 11 below the seat 12, and when the lever piece 41 is pivotally displaced beyond the second position in a direction away from the first position, the lever piece 41 abuts (engages) with the cushion unit 30 so as to be able to transmit the load. With this configuration, when the backrest 13 is placed in an upright position during assembly of the chair 1, the lever piece 41 on the backrest 13 side engages with the cushion unit 30 so as to be able to transmit the load. Therefore, when this configuration is adopted, the structure of the shaft 28 of the backrest 13 can be simplified compared to when the cushion unit is incorporated into the shaft 28 of the backrest 13. Furthermore, when this configuration is adopted, the backrest 13 and the cushion unit 30 can be connected by using a lever piece 41 that restricts the return of the backrest 13 to the tilting direction, thereby reducing the number of parts.

[0044] The present invention is not limited to the above-described embodiment, and various design modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, when the stopper portion (stopper piece 45) is in the first position, the weight of the stopper portion (stopper piece 45) functions as a biasing force that displaces the stopper portion (stopper piece 45) to the second position. However, the present invention is not limited to this configuration, and a biasing member that biases the stopper portion from the first position toward the second position may be provided. Furthermore, in the above embodiment, the stopper portion (stopper piece 45) is rotatably supported on the support structure (support base 11), but the stopper portion may also be supported on the support structure so as to be able to move forward and backward in a linear manner. Furthermore, in the above embodiment, the backrest is given as an example of the load-receiving functional portion, but the load-receiving functional portion is not limited to the backrest. The load-receiving functional portion may be, for example, an armrest. [Explanation of symbols]

[0045] 1. Chair 10…Legs (support structure) 11...Support base 11 (support structure) 13...Backrest (load-bearing function part) 20...Back support member (load-receiving main body) 28...Shaft 30...Cushion unit 41... Lever piece (engaged part) 45...Stopper piece (stopper part)

Claims

1. a support structure; a load-receiving functional part that is rotatably supported by the support structure and is switchable between a lying state and an upright state; The load receiving functional portion is a load-receiving main body that receives the load of a seated person; a shaft portion that rotates integrally with the load-receiving main body portion and is rotatably supported by the support structure; and a locked portion that rotates integrally with the shaft portion, the support structure includes a stopper portion that is displaceable between a first position that allows displacement of the locked portion from the lying-down corresponding position to the standing-up corresponding position when the locked portion is in the lying-down corresponding position and a second position that is located on a rotation path of the locked portion and restricts displacement of the locked portion from the standing-up corresponding position to the lying-down corresponding position when the locked portion is in the standing-up corresponding position, The chair is characterized in that, when in the first position, the stopper portion is biased toward the second position and is restricted from displacement to the second position by the engaging portion, and the restriction on displacement to the second position is released by the rotational displacement of the engaging portion to the standing-up corresponding position.

2. The chair of claim 1, characterized in that the stopper portion is rotatably supported on the support structure, and when in the first position, it abuts against the engaged portion in an inclined position in which a rotational biasing force due to its own weight acts, thereby restricting rotational displacement to the second position, and the restriction on displacement to the second position is released by rotational displacement of the engaged portion to the standing-up corresponding position.

3. The load-receiving functional portion is a backrest that supports the back of a seated person, a cushion unit that receives a rear load acting on the backrest is supported on the support structure; The chair according to claim 1 or 2, wherein the engaged portion engages with the cushion unit so as to transmit a load when the engaged portion is displaced beyond the second position in a direction away from the first position.

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