WO2009090770A1

WO2009090770A1 - Chair

Info

Publication number: WO2009090770A1
Application number: PCT/JP2008/064033
Authority: WO
Inventors: Nobuyuki Ueda
Original assignee: Kokuyo Co., Ltd.
Priority date: 2008-01-16
Filing date: 2008-08-05
Publication date: 2009-07-23
Also published as: JP2009165662A; JP5347142B2; JP5347141B2; JP2009165659A; US20100244521A1; EP2233043A1; WO2009090769A1; EP2233044A1; EP2233043A4

Abstract

A chair (1) includes a tiltable back support rod (6) for supporting a backrest (7), a support base (3) for pivotally supporting a vicinity of a lower end of the back support rod (6) and a coil spring (911) provided between the rod (6) and the base (3) for generating reaction force according to a rear tilt operation of the rod (6). The back support rod (6) includes a pair of right and left lower back frame bodies (621) provided outward from both side faces of the base (3), and a rigid coupling shaft (622) for rigidly coupling the lower ends of the pair of frame bodies (621) with each other and energizing the coil spring (911) in the direction of accumulating the reaction force when the rod (6) is rear-tilted. The rigid coupling shaft (622) is arranged below the lower surface of the base (3).

Description

Chair

The present invention relates to a chair that can tilt the backrest backward in accordance with the backward tilting motion of the back support that supports the backrest.

Conventionally, as a chair that can tilt the backrest with the back tilting motion of the back support rod that supports the backrest, the lower end of the back support rod is pivotally supported on the support base, There has been known one provided with an elastic body such as a coil spring that generates a reaction force with a back tilting operation of the back support rod between the support base (for example, see Patent Document 1 below).

In the following Patent Document 1, the support base is a substantially box-like shape having a bottom wall portion and standing side wall portions that are erected from both side edges of the bottom wall portion and open upward, A pair of left and right back support rod main bodies arranged on the inner side of the both side surfaces (standing side wall portions) of the support base, and the lower ends of the pair of back support rod main bodies are connected to each other and accommodated in the support base There is disclosed a mode in which a connecting shaft moves within a support base and biases a coil spring in a direction in which a repulsive force is accumulated when the back support rod is tilted backward.
Japanese Patent Laying-Open No. 2006-181101 (see FIG. 3)

However, the above-described conventional one is a mode in which the pair of left and right back support rod main bodies are arranged inwardly of the both sides of the support base, so that the lower end of the back support rod main body and the rotation of the connecting shaft are within the support base. In order to secure a moving space, the depth dimension in the support base, in other words, the height dimension of the support base naturally increases, and it is difficult to reduce the thickness of the support base. Further, since the pair of left and right back support rod main bodies are arranged inward of the both sides of the support base portion, the portion of the back support rod main body that protrudes from the support base portion when the back support rod is tilted backward. In order to avoid interference with the support base, the portion of the back support rod body that protrudes from the support base must be shaped to escape from the support base, and the design freedom is reduced and the shape is simplified. There was also a problem that they could not. In addition, since the pair of back support rod bodies are simply connected to each other by the connecting shaft, there is a side face that is difficult to conclude that the back support rod itself is a highly rigid structure. In the state where the heel was assembled to the support base, the back support rod did not contribute much to the improvement of the assembly strength.

The present invention has been made paying attention to such a problem, and a main object of the present invention is a chair that can tilt the backrest with the back tilting motion of the back support rod that supports the backrest. The support base can be made thinner without impairing the function of generating a reaction force when the back support is tilted backward, and the strength of the assembly between the back support and the support base can be improved, and the back support The object is to provide a chair capable of simplifying the structure of the bag.

That is, the chair of the present invention includes a tiltable back support rod that supports the backrest, a support base that pivotally supports a lower end portion of the back support rod or a portion near the lower end portion, the back support rod, and the support base. And an elastic body that generates a reaction force in accordance with the backward tilting motion of the back support rod, wherein the back support rod is outward of both side surfaces of the support base. A pair of left and right back support rod main bodies arranged on the left and bottom ends of the pair of back support rod main bodies are rigidly connected, and the elastic body accumulates repulsive force when the back support rod is tilted backward. And a rigid shaft that biases in the direction. The rigid shaft is arranged below the lower surface of the support base.

In such a case, the lower end portions of the pair of back support rods are rigidly connected to each other by a rigid connection shaft, so that at least the portion near the lower end portion of the back support rod becomes a highly rigid structure. In the state where the support is assembled to the support base, the back support greatly contributes to the improvement of the assembly strength. Further, the pair of left and right back support rods are arranged outward from both side surfaces of the support base, and the rigid shaft is arranged below the lower surface of the support base. It is not necessary to set the depth dimension in the support base, in other words, the height dimension of the support base sufficiently large in order to secure the rotational movement space of the lower end of the back support rod body and the rigid connection shaft. Thinning can be effectively achieved. Moreover, since the pair of left and right back support rod main bodies are arranged outward from both side surfaces of the support base, as in the conventional mode, during the back tilting operation of the back support rod, from within the support base of the back support rod main body. Since it is not necessary to make the protruding portion have a shape that avoids interference with the support base, the design freedom of the back support rod main body is not unnecessarily restricted, and it can be made a simple shape. In addition, the rigid support shaft of the back support rod biases the elastic body in the direction of accumulating the repulsive force, so there is no need to apply a separate dedicated biasing member, and the structure of the back support rod can be simplified. Can be planned.

In particular, the support base has a generally box shape opened downward, and the back support rod is fitted from behind the support base so that the support base portion is supported by the pair of left and right back support rod main bodies. If it can be attached to the support base in a state where it is sandwiched from both sides, the assembly work of the back support rod to the support base can be performed smoothly. In addition, since the support base, which is a box-like structure with high rigidity, is sandwiched from both sides by a pair of back support rod main bodies, the assembling strength is improved and the spacing between the back support rod main bodies is increased. Even if an external force acts in the direction of narrowing, the support base portion exists between the back support rod main bodies, so that the deformation of the back support rod main body due to the external force can be prevented.

As a preferred embodiment, the support base includes an upper wall portion and a pair of hanging side wall portions that are suspended from both side edge portions of the upper wall portion, and the lower portion is surrounded by these wall portions. The open accommodation space accommodates at least one end side of the elastic body arranged so that the direction in which the repulsive force is accumulated is inclined at a predetermined angle with respect to the vertical direction, and the other end of the elastic body The aspect which is made to support the part to the said rigid connection axis | shaft arranged below the lower surface of the said support base part is mentioned. As described above, if the support base has an accommodation space opened downward, a configuration in which a part of the elastic body arranged in an oblique posture protrudes downward from the accommodation space is possible. And the dimensions can be appropriately changed according to the specifications.

As described above, according to the present invention, in a chair that can tilt the backrest with the back tilting motion of the back support rod that supports the backrest, the reaction force is applied when the back support rod is tilted backward. The support base can be reduced in thickness without impairing the function of generating sway, the strength of the assembly of the back support bar and the support base can be improved, and the structure of the back support bar can be simplified. Can be provided.

The whole figure which looked at the chair concerning one embodiment of the present invention from the slanting front. The whole figure which looked at the chair concerning the embodiment from the slanting back. The side view of the chair in a normal state in the embodiment. The rear view of the chair in a normal state in the embodiment. Action explanatory drawing which abbreviate | omits and shows a part of FIG. The X direction arrow line view in FIG. The figure which is a part of FIG. 5, and shows only a back shell typically in the left-right width direction center longitudinal cross-section. The figure which shows typically the assembly | attachment aspect of the back shell and back support rod in the Y area | region of FIG. The figure which shows the chair in a synchro-rocking state in the embodiment corresponding to FIG. The figure which shows the chair in a synchro-rocking state in the embodiment corresponding to FIG. The figure which shows the chair in a back tilt state in the same embodiment corresponding to FIG. The figure which shows the chair in a back tilt state in the embodiment corresponding to FIG. The figure which shows typically the modification of the slide engagement mechanism in the embodiment corresponding to FIG.5 and FIG.12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Chair 3 ... Support base 31 ... Upper wall part 32 ... Hanging side wall part 6 ... Back support rod 62 ... Lower back frame 621 ... Back support rod main body (lower back frame main body)
622 ... Rigid shaft 7 ... Backrest 911 ... Elastic body (coil spring)

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

As shown in FIGS. 1 to 5, the chair 1 according to the present embodiment has a leg 2, a support base 3 attached to the upper end side of the leg 2 so as to be horizontally pivotable, and a front part supported by the support base 3. A seat receiver 4, a seat 5 attached to the seat receiver 4, a back support rod 6 that pivotally supports the lower end portion of the support base 3 and supports the rear portion of the seat receiver 4, and a backrest 7 attached to the back support rod 6. And so-called swivel chair.

The leg 2 is composed of a plurality of (five in the illustrated example) leg blades 21 each having a caster at the tip, and leg struts 22 standing from a portion where the base ends of the leg blades 21 are gathered. .

The support base 3 is integrally bent from the upper wall portion 31 and both side edges of the upper wall portion 31, as shown in FIG. The upper wall portion is made of, for example, a metal having a pair of suspended sidewall portions 32 and a pair of

partition walls

33 and 34 functioning as reinforcing ribs provided between the front end portions of the pair of suspended sidewall portions 32. The upper end portion of the leg column 22 is attached to the rear end portion of 31 and supported by the leg column 22. In addition, the partition 33 on the relatively rear side of the pair of

partition walls

33 and 34 is provided with a retainer guide portion 33a drilled in the thickness direction, and a retainer 912b inserted into the retainer guide portion 33a is provided with a coil spring described later. 911 is guided to advance and retreat in the compression advance / retreat direction. The support base 3 has a first support shaft X1 that pivotally supports the back support rod 6 so that the back support rod 6 can be pivoted between the portions of the left and right hanging side wall portions 32 that are slightly rearward from the substantially central portion. Yes. Further, elongated holes 32a for supporting a front frame (not shown) of the seat receiver 4 to be described later are formed in the front end portions of the left and right hanging side wall portions 32 in the thickness direction. The support base 3 is covered with a support base cover body 3c from below so that it cannot be directly seen (see FIG. 3).

The seat 4 is arranged above the support base 3 and supported by the support base 3 in a state where a rod-shaped front frame (not shown) provided at the front end is inserted into the long hole 32a of the support base 3. The chair 1 of this embodiment includes armrests 8 that extend upward from the vicinity of the left and right side edges of the seat 4. The armrest 8 shown in FIG. 1 and the like cannot be adjusted in height, but instead of this, an armrest that can be adjusted in height may be applied. Moreover, the chair which does not have an armrest may be sufficient.

The seat 5 includes a seat shell 51 that plays a role as a structural member that uniformly supports the load applied to the seat 5, a seat cushion (not shown) provided above the seat shell 51, and a seat cushion that covers the seat cushion. And a cover 52.

The backrest 7 plays a role as a structural member that uniformly supports the load applied to the backrest 7 and is supported by the back support 6 and a back cushion (not shown) provided in front of the back shell 71. ) And a back cushion cover 72 that covers the back cushion.

The back shell 71 is mainly composed of a resin elastic plate-like body, and the upper and lower portions protrude rearward from the central portion in the height direction, and the left and right side edge portions protrude forward from the central portion in the left-right width direction. It has a three-dimensional shape. A large number of openings 711 are provided in a region above the lumbar support portion 71L that can support the waist of the seated person in the back shell 71, more specifically, in a region above the center in the height direction of the back shell 71. The opening ratio, which is the ratio of the opening 711 in a predetermined region of the back shell 71, is set so as to gradually increase toward the upper edge and both side edges of the back shell 71. In the following description, the entire region of the back shell 71 provided with the opening 711 is referred to as “back shell upper portion 71T”. That is, as shown in FIG. 4 and the like, the back shell 71 is positioned slightly below the back shell upper portion 71T, the back shell central portion 71S that is the central portion in the height direction of the back shell 71, and the back shell central portion 71S. The lumbar support portion 71L and the back shell lower portion 71U, which is a region below the lumbar support portion 71L, are integrally provided. The curvature of the curved surface in plan view of the back shell central portion 71S, the lumbar support portion 71L, and the back shell lower portion 71U is the same, and this curvature is set larger than the curvature of the curved surface in plan view of the back shell upper portion 71T. Yes. 7 (this figure corresponds to FIG. 5 and is a diagram schematically showing only the back shell 71 in the central longitudinal section in the left-right width direction), and has a relatively large curvature. The central portion 71S, the lumbar support portion 71L, and the back shell lower portion 71U have a curved shape that is continuous with a bow, while the back shell upper portion 71T having a relatively small curvature has a substantially linear shape along the height direction. Become. The back shell central portion 71S and the back shell upper portion 71T are continuous with each other with a discontinuous line 712 as a boundary.

The lumbar support portion 71L of the back shell 71 is provided with a deformation inducing means 713 that is partly easier to deform than the peripheral portion of the lumbar support portion 71L. In the present embodiment, a slit 713a extending in the left-right width direction is applied as the deformation inducing means 713. The number of slits 713a may be singular or plural, and in the present embodiment, a pair of upper and lower slits 713a are provided that are spaced apart from each other in the height direction.

FIG. 8 shows a state before the back shell upper portion 71T is assembled to the back support rod 6 in order to show the manner of assembling the back shell 71 and the back support rod 6 in the Y region of FIG. As shown in FIG. 4, an engagement portion 714 that protrudes rearward and can be engaged with a slide engagement hole 611 formed at an upper end portion of the upper back frame 61 described later is integrally or integrally provided. ing. In FIG. 8, the opening 711 of the upper back shell 71T is omitted. The engaging portion 714 has a substantially block shape, and has a flange portion 714a integrally at the distal end portion (the end portion on the side away from the back surface of the back shell 71).

As shown in FIG. 5 and the like, the back shell lower portion 71U is integrally or integrally provided with a supported portion 715 that protrudes rearward and is supported by an upper end portion of a lower frame described later. In the present embodiment, a pair of left and right thin plate-like supported portions 715 are provided on the lower end portion of the back shell lower portion 71 </ b> U, that is, the lower end portion of the back shell 71.

As shown in FIG. 5 and the like, the back support rod 6 that supports the back shell 71 is a portion of the back shell 71 that is above the lumbar support portion 71L that supports the waist of the seated person. An upper back frame 61 that supports the back shell upper portion 71T and a lower back frame 62 that supports the back shell lower portion 71U are provided, and pivot points between the upper back frame 61 and the lower back frame 62 (third support shaft described later) X3) is set rearward on the lower end side of the back shell 71, and the upper back frame 61 is configured to be tiltable (tilted) with respect to the lower back frame 62 around the pivot point. As shown in FIG. 2, the upper back frame 61 and the lower back frame 62 are covered with an upper back frame cover body 61c and a lower back frame cover body 62c from the rear or below, respectively, so that they cannot be directly seen. .

As shown in FIGS. 5 and 6 and the like, the lower back frame 62 has a pair of left and right lower back frame main bodies 621 arranged on the outer side than both side surfaces of the support base 3 (in the “back support rod main body” of the present invention). And a rigid connection shaft 622 that is rigidly connected to the lower ends of the pair of lower back frame main bodies 621 and that is disposed below the lower surface of the support base 3.

Each lower back frame main body 621 is substantially plate-shaped, and has a side view shape that gradually extends obliquely rearward from the lower end portion toward the vicinity of the upper end portion and bends the vicinity of the upper end portion obliquely forward. *

The rigid connection shaft 622 has a rod shape and is fixed so as not to be detached while being bridged between lower ends of the lower back frame main body 621 by appropriate means such as welding.

In order to attach such a lower back frame 62 to the support base 3, a pair of left and right lower back frame main bodies 621 are rigidly connected by a rigid connection shaft 622, and the lower portion of each lower back frame main body 621 is located between the vicinity of the lower end portions. An insertion hole (not shown) provided in the penetrating side wall 32 of the support base 3 and an insertion hole 621a provided in the vicinity of the lower end of each lower back frame main body 621, approaching from the rear of the support base 3 so as to sandwich the support base 3 therebetween. This is performed by inserting the first support shaft X1 in a state where the holes communicate with each other. As a result, the lower back frame 62 and thus the back support rod 6 can rotate with respect to the support base 3 about the first support shaft X1. In the present embodiment, an extension portion 621b that extends forward from the other portion is integrally provided in the vicinity of the lower end portion of each lower back frame main body 621, and an insertion hole 621a is formed in each extension portion 621b. ing. The first support shaft X1 is disposed rearward and upward relative to the rigid connection shaft 622.

In the chair 1 according to this embodiment, in a state where the lower back frame 62 is attached to the support base 3, the rigid shaft 622 of the lower back frame 62 is the lower surface of the support base 3 (specifically, the lower surface of the hanging side wall portion 32). A coil spring 911 which is an elastic body of the present invention is disposed between the rigid coupling shaft 622 and the support base 3 and generates a reaction force in accordance with the backward tilting motion of the back support rod 6. When the lower back frame 62 is tilted rearward about the first support shaft X1, the rigid shaft 622 biases the coil spring 911 in the direction in which the repulsive force is accumulated.

Specifically, as shown in FIG. 6, the rigid coupling shaft 622 supports a coil spring receiving portion 911 x provided on one end side of a coil spring 911 described later at the center in the longitudinal direction. The coil spring 911 and the coil spring receiving portion 911x constitute the tilting reaction force adjusting device 9 for adjusting the reaction force when the back support rod 6 is tilted backward.

As shown in FIGS. 5 and 6, the tilting reaction force adjusting device 9 is at least partially housed in the support base 3, and the reaction force when the back support rod 6 is tilted backward is independent of the seat support 4. And a reaction force adjusting operation unit 92 for adjusting the strength of the reaction force of the reaction force generating unit 91 provided on the side edge front end side of the seat 5. It is.

More specifically, the reaction force generation unit 91 compresses or compresses the coil spring 911 in conjunction with a coil spring 911 and an adjustment operation provided on one end side of the coil spring 911 and received by the reaction force adjustment operation unit 92. And a compression / decompression unit 912 for decompression. The compression / extension unit 912 is a substantially trapezoidal slider 912a in plan view that moves forward and backward in a direction orthogonal to the compression / extension direction of the coil spring 911 in conjunction with the adjustment operation received by the reaction force adjustment operation unit 92, and the slider 912a and the slider 912a. A retainer 912b having a substantially trapezoidal shape in plan view that moves and supports the coil spring 911 and moves back and forth in the compression / extension direction, and the retainer guide portion 33a that guides the advance / retreat of the retainer 912b in the compression / extension direction. Is. As described above, the retainer guide portion 33a is formed in the partition wall 33 of the support base 3 for supporting the seat receiver 4.

The reaction force adjusting operation portion 92 includes a rod 921 that extends in the left-right width direction through one of the hanging side wall portions 32 of the support base 3, and a rod 921 that is provided at the distal end portion of the rod 921 and rotates around the rod 921. And an operation grip 922 to be rotated.

Return to the description of the lower back frame 62. Each lower back frame main body 621 of the lower back frame 62 is integrally provided with a second extending portion 621c that extends forward from the peripheral portion at a position slightly below the central portion in the height direction. The rear end side of the seat receiver 4 is supported by a second support shaft X2 that is fixed in a state of being bridged between the protruding portions 621c. Furthermore, the supported portion 715 of the back shell 71 is fixed to a portion near the upper end of each lower back frame main body 621 by an appropriate means such as screwing so that the relative angle cannot be changed.

The upper back frame 61 pivotally supported by the upper end of the lower back frame 62 having such a configuration has a width dimension that is sandwiched between the pair of left and right lower back frame bodies 621 as shown in FIG. In addition, the upper end portion and the lower end portion are formed in a substantially U shape in a side view in which the upper end portion and the lower end portion are protruded rearward from the central portion in the height direction. As shown in FIG. 8, a slide engagement hole 611 in which the engagement portion 714 provided in the back shell upper portion 71T is slidably engageable is formed in the upper end portion of the upper back frame 61. The slide engagement hole 611 is continuously provided above the large hole 611a and the large hole 611a into which the flange 714a of the engagement part 714 can be inserted and removed, and the flange 714a inserted from the large hole 611a. And a small hole 611b that can allow the relative sliding movement of the engaging portion 714 in a state where it cannot be removed. The height dimension of the small hole part 611b is set to be larger than the height dimension of the large hole part 611a, and a margin for relative sliding movement between the slide engagement hole 611 and the engagement part 714 is secured.

An insertion hole penetrating in the left-right width direction (not shown) is formed at the lower end portion of the upper back frame 61, and this insertion hole and the insertion hole 621d provided at the upper end portion of each lower back frame main body 621 are communicated with each other. By inserting the third support shaft X3 in this state, the upper back frame 61 can be tilted backward about the third support shaft X3. In the present embodiment, the third support shaft X <b> 3 is set so as to be arranged rearward on the lower end side of the back shell 71. Further, the upper back frame 61 includes an overhang portion 612 that extends downward from the pivot point (third support shaft X3), and the upper back frame 61 is interposed between the overhang portion 612 and the lower back frame 62. A second coil spring 63 that generates a reaction force in association with the backward tilting operation of the frame 61 is provided. In the present embodiment, in a state where the fourth support shaft X4 is bridged between portions slightly below the bent upper end portion of the pair of left and right lower back frame main bodies 621 of the lower back frame 62. It is fixed, and one end portion of the second coil spring 63 is supported by the fourth support shaft X4, and the other end portion of the second coil spring 63 is supported by the overhang portion 612 of the upper back frame 61.

With the back shell upper portion 71T and the back shell lower portion 71U supported by the upper end portion of the upper back frame 61 and the upper end portion of the lower back frame 62, respectively, the back shell 71 and the back support rod 6 (specifically, the upper back frame 61). A space is formed between

Next, the usage method and operation of the chair 1 according to the present embodiment composed of the above-described members will be described.

As shown in FIGS. 1 to 5, the chair 1 according to the present embodiment is in a normal state (S) in which the backrest 7 takes a standing posture, and the backrest 7 is tilted backward as shown in FIGS. In accordance with the movement, the seat 5 is slid in the direction of sinking backward in a synchronized state (R) in which the seat 5 slides backward, and in the normal state (S) as shown in FIG. 11 and FIG. When the weight is applied to the upper part of the backrest 7, the upper back frame 61 tilts backward about the third support shaft X3, and accordingly, the entire back shell 71 is bent and deformed like a bow in a side view. At least the back tilt state (T) can be taken.

When in the normal state (S), the back shell 71 mainly composed of an elastic plate-like body has a curved shape like a side view bow against its elasticity.

When a seated person leans the entire back on the backrest 7 with respect to the chair 1 in such a normal state (S), as shown in FIG. While maintaining the relative angle to the lower back frame 62, the back shell 71 tilts backward with the first support shaft X1 as the center. At this time, since the weight of the seated person is applied almost evenly to the entire backrest 7, the upper back frame 61 does not tilt backward with respect to the lower back frame 62, in other words, the upper back frame 61 and the lower back frame. The relative angle with the frame 62 does not change, and the back shell 71 also tilts backward while maintaining substantially the same shape as in the normal state (S). A front frame (not shown) provided at the front end of the seat support 4, the rear end of which is supported by the second support shaft X <b> 2 of the lower back frame 62 in accordance with the backward tilting operation of the back support rod 6. Is slid in the direction of sinking backward while moving in the long hole 32a. As a result, the entire seat 5 supported by the seat receiver 4 slides and moves in the same direction as the seat receiver 4, that is, in the direction of sinking backward (see FIG. 9), and the chair 1 enters the synchro-rocking state (R).

In the synchro-rocking state (R), the rigid shaft 622 of the lower back frame 62 presses the coil spring 911 in the direction in which the repulsive force is accumulated, so that the seated person separates his back from the backrest 7, that is, When the upper body is raised, the entire back support 6 is automatically returned to the normal posture before being tilted backward by the repulsive force of the coil spring 911. In the present embodiment, the tilting reaction force adjusting device 9 can adjust the reaction force when the backrest 7 is tilted backward. Specifically, when the operation grip 922 is rotated in one of the clockwise and counterclockwise directions (for example, clockwise), the slider 912a moves in a direction approaching the operation grip 922 in conjunction with this, and the slider 912a presses the retainer 912b. Then, the retainer 912b pressed by the slider 912a moves in a direction in which the coil spring 911 is compressed, and the reaction force when the backrest 7 is tilted backward can be increased. On the other hand, if the operation grip 922 is rotated in the reverse direction (for example, counterclockwise), the reaction force when the backrest 7 is tilted backward can be reduced.

On the other hand, in the normal state (S), when the seated person intentionally puts weight on the back shell upper portion 71T, the upper back frame 61 of the back support rod 6 is centered on the third support shaft X3 as shown in FIG. As shown in FIG. Along with the backward tilting action of the upper back frame 61, the back shell upper portion 71T of the back shell 71 supported by the upper back frame 61 is acted on by the lower back frame 62 while a force is exerted to warp backward. Since the lower end portion of the back shell 71 tries to stay at the position in the normal state (S) by the lower back frame 62 that does not tilt backward, the back shell 71 is a portion between the back shell upper portion 71T and the back shell lower portion 71U. Is further curved and deformed so as to protrude further forward. In this embodiment, since the lumbar support portion 71L of the back shell 71 is provided with the deformation inducing means 713, specifically, the slit 713a, when the entire back shell 71 is curved and deformed like a bow, the opening height of the slit 713a is set. The lumbar support portion 71L is deformed in the narrowing direction, and as a result, the lumbar support portion 71L protrudes relatively forward as compared to the normal state (S). In this embodiment, the back shell upper portion 71T is engaged with and supported by the upper back frame 61 so as to be relatively slidable in the height direction, and is provided on the back shell upper portion 71T when the upper back frame 61 tilts backward. Further, the engaging portion 714 is relatively slid in the height direction within a range in which the engagement state with respect to the slide engaging hole 611 is not released in the slide engaging hole 611 formed in the upper end portion of the upper back frame 61. The entire back shell 71 can be curved and deformed following the backward tilting action of the upper back frame 61. The chair 1 of the present embodiment has a curved upper surface curvature in the back shell 71 that is smaller than that of the other portions, and is substantially straight along the height direction. Therefore, the sliding movement can be performed smoothly in a stable state.

With the transition of the chair 1 from the normal state (S) to the back tilt state (T), the overhang portion 612 of the upper back frame 61 is interposed between the overhang portion 612 and the lower back frame 62. The two-coil spring 63 is pressed in the direction in which the repulsive force is accumulated. Therefore, when the occupant moves his back away from the backrest 7, that is, when the upper body is raised, the upper back frame 61 automatically returns to the normal position before the upper back frame 61 is tilted backward by the repulsive force of the second coil spring 63, and the chair 1 is in the back tilt state. The normal state (S) is returned from (T). Further, when the chair 1 shifts from the normal state (S) to the back tilt state (T), the elastic return force of the back shell 71 that is curved and deformed more like a bow than the shape in the normal state (S) causes the upper back frame 61 to be restored. Acts as a force for energizing in the direction of pulling forward. Therefore, when the chair 1 is in the back tilt state (T), if the seated person intentionally puts his / her weight on the lumbar support portion 71L, the biasing force further increases, and the biasing force and the repulsion of the second coil spring 63 are increased. Combined with the force, when the occupant lifts his back from the backrest 7, that is, when the upper body is raised, the upper back frame 61 follows its movement and quickly automatically returns to the normal posture before tilting backward. It will be.

After the chair 1 is shifted from the normal state (S) to the back tilt state (T), when the seated person puts his / her weight on the entire backrest 7, the upper back frame 61 is rearward of the lower back frame 62. While maintaining the tilted posture, the lower back frame 62 tilts backward about the first support shaft X1. As a result, the chair 1 is in the last tilted state (not shown) that combines the back tilt state (T) and the synchro-rocking state (R). In a similar manner, after the transition from the normal state (S) to the synchro-rocking state (R), when the seater intentionally puts weight on the upper back frame 61, the upper back frame 61 is moved to the third support shaft. It tilts backward with respect to the lower back frame 62 around X3, and becomes a final tilted state combining the synchro-rocking state (R) and the back tilt state (T) (not shown).

That is, the chair 1 according to the present embodiment has a normal state (S), a synchro-rocking state (R), a back tilt state (T), depending on how a seated person sits, more specifically, how to apply weight. The last tilted state, or an intermediate state that is intermediate between two different states (for example, an intermediate state between a normal state (S) and a synchro-rocking state (R), a normal state (S), and a back tilt state (T) Intermediate state: not shown).

The chair 1 of this embodiment includes a tilt braking device A that is provided between the back support 6 and the support base 3 so as to selectively allow the backrest 7 to tilt. The tilt braking device A supports the lower end portion of the tilt braking device A on the rear end side of the support base 3 so as to be swingable, and the upper end portion of the tilt braking device A is supported on the fourth support shaft X4 of the lower back frame 62. In this embodiment, as shown in FIG. 6, as the tilt braking device A, a substantially cylindrical gas spring main body A1 is housed, and substantially the whole is accommodated in the gas spring main body A1. A well-known gas spring having a piston rod portion (not shown) that advances and retreats as much as possible and functions as a tilt braking portion is applied, and detailed description thereof is omitted.

As described above, in the chair 1 according to the present embodiment, the lower back frame 62 that is rotatably attached to the support base 3 of the back support rod 6 is configured such that the lower ends of the pair of lower back frame main bodies 621 are rigidly connected to each other. Therefore, at least a portion near the lower end of the back support 6 is a highly rigid structure, and the lower back frame 62 is attached to the support base 3 in such a state that the lower back frame 62 is assembled to the support base 3. This will greatly contribute to the improvement of assembly strength. Furthermore, a pair of left and right lower back frame main bodies 621 are arranged on the outer side of both side surfaces of the support base 3 (specifically, the outward surface of the hanging side wall portion 32), and the rigid shaft 622 is disposed on the lower surface of the support base 3. Therefore, it is not necessary to secure a rotational movement space for the lower end portion of the lower back frame main body 621 and the rigid shaft 622 in the support base 3, and the support base 3 can be thinned. In addition, since the pair of left and right lower back frame main bodies 621 are arranged outside the both side surfaces of the support base 3, the support base is supported when the back support rod 6 is tilted backward with respect to the lower back frame main body 621. 3 is not required, and the shape of the lower back frame main body 621 can be set to a simple shape without being affected by the height dimension or shape of the support base 3. Further, since the rigid coupling shaft 622 biases the coil spring 911 in the direction in which the repulsive force is accumulated, it is not necessary to separately apply a dedicated biasing member, and the structure of the lower back frame 62 and eventually the back support rod 6 is achieved. Simplification can be effectively achieved.

In particular, the support base 3 has a generally box-like shape opened downward, and the lower back frame 62 is brought close to be fitted from the rear of the support base 3, so that a pair of left and right lower back frame main bodies 621 are used. Since the lower back frame 62 and thus the back support rod 6 can be attached to the support base 3 with the support base 3 sandwiched from both sides, the assembly work of the back support rod 6 to the support base 3 is performed smoothly. be able to. Further, since the support base 3 that is a box-like structure having high rigidity is sandwiched from both sides by the pair of lower back frame main bodies 621, the assembling strength is improved and the lower back frame main bodies 621 are separated from each other. Even if an external force acts in the direction of narrowing the dimensions, the support base portion 3 exists between the lower back frame main bodies 621, so that the deformation of the lower back frame main body 621 due to the external force can be prevented.

In addition, if it is a box-shaped support base having an accommodation space opened upward as in the prior art, the coil spring must be accommodated in the accommodation space, so the shape and dimensions of the coil spring are the accommodation space of the support base. However, in this embodiment, the support base 3 is a pair of upper wall 31 and a pair of both sides of the upper wall 31 that hang down from each other. A direction in which the repulsive force is accumulated in a vertical direction with respect to a housing space opened downwardly surrounded by each of the wall portions (upper wall portion 31, hanging wall portion 32). A mode in which at least one end portion side of the coil spring 911 arranged so as to be in an angle-inclined direction is accommodated, and the other end portion of the coil spring 911 is supported by the rigid coupling shaft 622 arranged below the lower surface of the support base 3. Is , Configuration popping below the accommodation space portion within the support base 3 of the coil spring 911 which is arranged in an oblique posture becomes possible can be set appropriately changed according to the shape and dimensions of the coil spring 911 to the specifications.

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

For example, in the above-described embodiment, the back support rod includes a lower back frame and an upper back frame that can be tilted backward with respect to the lower back frame. It may be a back support that cannot change the angle relative to the side. As an example of the back support rod in this case, there is a mode in which the side view is substantially L-shaped and the lower end portion or a portion near the lower end portion is pivotally supported by a support base portion disposed below the seat.

In addition, as an elastic body that generates a reaction force in response to the backward tilting motion of the back support rod, rubber, a leaf spring, or the axial direction is made to substantially coincide with the lateral width direction of the chair, and both ends are separated from the axial center. You may apply what is called a winding spring extended in the direction. Furthermore, the rigid shaft may of course pull the elastic body in the direction in which the repulsive force is accumulated in accordance with the backward tilting motion of the back support rod.

Moreover, in the said embodiment, although the upper back frame 61 illustrated the aspect which supports in the state which engaged the back shell upper part 71T so that sliding movement was possible in a height direction, it replaces with this and a lower back frame, The lower part of the back shell may be supported so as to be slidably movable in the height direction, or both the upper back frame and the lower back frame slide the back shell in the height direction. You may support in the state engaged so that movement was possible. That is, a mode in which a slide engagement mechanism that allows relative sliding movement between the back shell and the back support rod is provided only between the upper back frame and the back shell, or provided only between the lower back frame and the back shell. Alternatively, it may be an aspect provided between each back frame and the back shell, or any of these aspects. Furthermore, the slidable distance may be appropriately changed according to the specifications. In the said embodiment, although the aspect which engages an engaging part with an engagement hole was illustrated, it may replace with an engagement hole and may apply an engagement groove | channel. In addition, as a slide engagement mechanism, an engagement concave portion such as an engagement hole or an engagement groove is integrally provided on the back shell side, and an engagement convex portion capable of sliding engagement with the engagement concave portion is provided on the back frame side. Aspects may be adopted. As an example, as shown in FIG. 13, a pocket-shaped engaging recess 714 ′ opening only downward is integrally provided on the back surface of the back shell 71 (upper shell upper portion), while a back support rod (upper back frame 61 is provided. ) Is provided with an upward engaging engagement convex portion 611 ′ having an L shape in side view that can be inserted from below, and the engagement convex portion 714 ′ By reducing the amount of squeezing of the engagement recess 714 ′ with respect to the engagement protrusion 611 ′ within a range in which the engagement state between the portion 611 ′ and the engagement recess 714 ′ is not released, the back shell 71 can be A mode in which the frame 61) can slide in the height direction is mentioned. In this case, the engaging concave portion and the engaging convex portion can be engaged with each other by dropping the back shell into the back support rod from above, and the assembling work can be easily performed.

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

Claims

A tiltable back support that supports the backrest, a support base that pivotally supports a lower end of the back support or a portion in the vicinity of the lower end, and a support base that is disposed between the back support and the support base, and A chair provided with an elastic body that generates a reaction force in accordance with the backward tilting motion of the back support rod,
The back support rod is configured to rigidly connect a pair of left and right back support rod main bodies disposed on the outer sides of both side surfaces of the support base, and lower ends of the pair of back support rod main bodies, and the back support rod And a rigid coupling shaft that urges the elastic body in a direction to accumulate a repulsive force when tilted backward, and the rigid coupling shaft is disposed below the lower surface of the support base. A chair characterized by that.
The support base has a generally box shape opened downward;
2. The back support rod can be attached to the support base in a state where the support base is sandwiched from both sides by the pair of left and right back support rod main bodies by fitting from behind the support base. The listed chair.
The support base includes an upper wall portion and a pair of hanging side wall portions that hang from both side edge portions of the upper wall portion, and in an accommodation space that is open downwardly surrounded by these wall portions, The elastic body is arranged so that the direction in which the repulsive force is accumulated is inclined at a predetermined angle with respect to the vertical direction, and at least one end portion side of the elastic body is accommodated, and the other end portion of the elastic body is disposed on the lower surface of the support base The chair according to claim 1 or 2, wherein the chair is supported by the rigid shaft disposed below the chair.