JP2014076154A - Chair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chair not only improving efficiency of connection work between an auxiliary member and a backrest but also preventing concentration of moment applying between both in a specific site.SOLUTION: Left/right forward arm parts 12 of a backrest 8A are coupled to left/right auxiliary parts fitted to leg parts 6A, with upward movement. A coupling part 47 of each auxiliary member 40 engages with mutually different positions of the front part of the forward arm part 12, applies a reaction to the front part such that rotation moment generates inversely to moment caused by the weight of the backrest 8A of a rear part with respect to the front part, and has a plurality of engagement retention portions (an upward inclined surface 46 and a first engagement portion 48) that retain the backrest 8A so as not to fall by the reaction.

Description

  The present invention relates to a chair that supports a backrest on the leg by connecting the backrest to an auxiliary member pivotally supported on the leg.

2. Description of the Related Art Conventionally, in a chair that supports a backrest on a leg, an auxiliary member for connecting the backrest is pivotally supported in advance on an operation mechanism portion that is located below the seat and connects the backrest and the like. There is one in which the backrest is supported by the actuating mechanism portion of the leg by connecting the fins (for example, see Patent Documents 1-3).
These technologies include a pair of left and right forward arms that are pivotally supported on the left and right sides of the operating mechanism, and these forward arms are integrated so as to avoid the operating mechanism. The attachment can be performed efficiently.

JP 2008-119251 A JP 2010-0944456 A JP 2011-092381 A

However, the chair disclosed in the above document has the following problems.
In Patent Document 1, first, a pin 14 protruding from a rear portion of an armrest 13 as an auxiliary member is placed above a recessed groove 17 that is formed in a rear portion of a backrest supporting rod 10 that forms a part of the backrest and is opened downward. And then temporarily holding the pin 14 as a fulcrum, the back support rod 10 is pivoted forward and upward, and the pivot shaft is provided so as to protrude outward from the front portion of the arm rod 13. 7 is a structure in which a concave groove 18 opened upward at the front portion of the back support rod 10 is fitted from below. According to this structure, since the backrest support rod 10 can be temporarily held, the operation of rotating the backrest support rod 10 can be performed efficiently. On the other hand, while holding the upper part of the L-shaped backrest support rod 10 by hand, the pivot shaft 7 that is separated from the concave groove 18 at the tip and the pin 14 that serves as a rotation fulcrum, is difficult to apply force. Need to be fitted properly, which requires work time and causes a loss in the process.
In Patent Document 2, the tip of the arm portion 6 that forms a part of the backrest is fitted to the swing frame 8 as an auxiliary member, and the arm portion 6 is integrated with the upper surface of the swing frame 8. This is a structure in which the bottom plate portion 7 is placed and these are screwed together. This structure makes it very easy to support the backrest on the auxiliary member. On the other hand, since the backrest, which is larger than the swing frame 8 and has a large load, is placed in a wide area, a large bending moment is applied to the swing frame when the backrest is rotated. Frame wear is likely to occur.
In Patent Document 3, as in Patent Document 1, the swinging member 18 as an auxiliary member and the forward arm 16 of the back frame 10 that forms a part of the backrest are fitted to the frame receiving shaft 37 and the forward opening groove 38. In this structure, the first shaft 19 and the downward opening groove 39 are fitted together. Therefore, there is a possibility that the same problem as in Patent Document 1 occurs.

  The present invention has been made in view of the above circumstances, and provides a chair that not only increases the efficiency of the connecting operation between the auxiliary member and the backrest, but also prevents the concentration of the moment acting between the two on a specific part. For the purpose.

In order to achieve the above object, the present invention employs the following means.
That is, the chair according to the present invention is a chair including a leg and a backrest supported by the leg, and the backrest extends forward from the lower side of the standing portion that supports the back of the seated person. A pair of left and right forward arm portions whose front portions are arranged on the left and right outer sides of the leg body, and a rotation shaft that projects from the leg body to the left and right sides so as to be integrally rotatable, and the upward movement of the forward arm portion An auxiliary member having a connecting portion for connecting the front portion of the forward arm portion, and the connecting portion engages at different positions of the front portion of the forward arm portion, and the front portion A plurality of engagement holdings that cause a reaction force to act on the front part and keep the backrest so that it cannot fall off by the reaction force so that a moment opposite to the moment due to the weight of the backrest is generated behind It has the part.
The chair configured as described above can be easily assembled even if the backrest is formed by integrating the left and right forward arms by the upward movement of the forward arms relative to the auxiliary member. Further, the moment due to the weight of the backrest can be distributed to the plurality of engagement holding portions of the auxiliary member, and the backrest can be temporarily held at the assembled position by the action of the plurality of engagement holding portions.

Further, in the chair according to the present invention, the plurality of engagement holding portions include an upward first inclined surface and a convex or concave first engagement portion, and the front portion of the forward arm portion is It is preferable to have a downward second inclined surface that faces the first inclined surface, and a concave or convex second engaging portion that engages the first engaging portion.
In the chair configured as described above, a plurality of engagement holding portions can be formed in a simple shape, and the plurality of engagement holding portions of the connecting portion and the front portion of the forward arm portion engaged with the engagement holding portion can be easily formed. Can be formed.

In the chair according to the present invention, it is preferable that the first engagement portion and the second engagement portion abut against each other and are fastened in the abutting direction.
In the chair configured as described above, the forward arm portion can be easily positioned when the forward arm portion is moved upward with respect to the auxiliary member, and the forward arm portion can be fastened to the auxiliary member in this state.

In the chair according to the present invention, the front portion of the forward arm portion is engaged with the auxiliary member so as to overlap from the left and right outer sides, and the shaft end portion of the rotation shaft is parallel to the rotation shaft. Fastened by a shaft end screw, on the left and right outer sides of the auxiliary member, has a convex or concave first positioning part that engages with the left and right inner sides of the front part of the forward arm part, and the front part of the front arm part It is preferable to have a concave or convex second positioning portion that engages with the first positioning portion on the left and right inner sides.
In the chair configured as described above, the forward arm and the auxiliary member can be easily positioned based on the rotation axis.

  According to the present invention, it is possible to provide a chair that not only increases the efficiency of the connecting operation between the auxiliary member and the backrest but also prevents the moment acting between them from concentrating on a specific part.

It is a perspective view of the chair in the embodiment of the present invention. It is a side view of the said chair, (a) shows the state before tilting the backrest backward, (b) shows the state which tilted the backrest backward, respectively. It is a perspective view around the forward arm portion of the backrest. It is a perspective view in the state where the auxiliary member was separated from the front part of the forward arm. It is a front view around the forward arm portion. It is VI-VI sectional drawing of FIG. It is VII-VII sectional drawing of FIG. It is sectional drawing equivalent to FIG. 7 which shows the modification of the said embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a chair 1 according to this embodiment includes a multi-legged leg 3 with casters 2, a pedestal 4 standing from the center of the multi-legged leg 3, and an upper end of the pedestal 4. A support base 6 that supports 5, and an L-shaped back support that has a front lower end pivotally attached to both right and left sides of the support base 6 and can be tilted backward by a reclining mechanism (not shown) in the support base 6. 7, a backrest main body 8 attached to the front surface of the rear upper portion of the backrest support body 7, and armrests 9 supported on the left and right sides of the lower portion of the backrest support body 7. The multi-leg 3, the pillar 4 and the support base 6 constitute the leg 6A of the chair 1, and the back support 7 and the back body 8 constitute the back 8A of the chair 1.

  2 and 3 together, the backrest support 7 is a die-cast product made of, for example, an aluminum alloy, and a standing part 11 disposed at the lower rear of the backrest body 8 and a lower part of the standing part 11. And a pair of left and right forward arms 12 that extend while curving forward and branching left and right. On both the left and right sides of the support base 6, a rotation shaft 19 that extends in the left-right direction of the reclining mechanism protrudes, and the front end portion 12 a of the left-right forward arm portion 12 is attached to the rotation shaft 19 so as to be integrally rotatable. The backrest support 7 can be tilted back and forth or stopped at a desired rearward tilt position by the action of the reclining mechanism.

  A seat body connecting portion 13 extending toward the lower surface of the front and rear intermediate portion of the seat body 5 projects from the front upper side of the left and right forward arm portion 12. The lower surface of the front portion of the seat body 5 is supported by the upper surface of the front portion of the support base 6 so as to be slidable back and forth. On the left and right outer sides of the front part of the left and right forward-facing arms 12, the inner ends of the lower curved portion that curves toward the left and right inner sides of the support column 14 of the armrest 9 are fixed by fastening or the like.

  As shown in FIG. 2A, when the backrest support 7 tilts backward from the standing state before the backrest support 7 tilts backward as shown in FIG. 2B, the backrest body The armrest 9 together with 8 tilts backward in the same manner. At this time, the seat body 5 is pulled downward and rearward by the seat body connecting portion 13 of the forward arm 12, and the front portion of the seat body 5 slides backward with respect to the support base 6. It tilts backward and downward while moving backward in conjunction with the tilting of the support 7.

  As shown in FIG. 1, the backrest main body 8 has a configuration in which a mesh fabric 16 is stretched on the front opening of a backrest frame 15 that forms the skeleton. The backrest frame 15 is an injection-molded product made of, for example, a synthetic resin, and integrally includes a frame portion 17 that forms a front opening and a central trunk portion 18 that extends rearward and rearward of the frame portion 17. The rear side of the lower portion of the central trunk 18 overlaps the front side of the upright portion 11 of the backrest support 7 in the front-rear direction, and these are integrally connected.

  As shown in FIG. 3, the front portions of the left and right forward arm portions 12 are disposed on the left and right outer sides of the support base 6. The left and right forward arms 12 are connected to the left and right auxiliary members 40 pivotally supported in advance on the left and right outer sides of the support base 6 so as to overlap each other from the left and right outer sides. The portion 12 and the backrest 8A are pivotally supported by the support base 6 and the leg body 6A. Hereinafter, unless otherwise specified, the left and right auxiliary members 40 are attached to the legs 6A, and the respective configurations will be described based on the state in which the left and right forward arms 12 are connected to the left and right auxiliary members 40.

  As shown in FIGS. 3 and 4, the left and right forward arms 12 form an inner side surface 21 and an outer side surface 22 that are inclined so as to be positioned on the left and right inner sides as the lower side. A rectangular parallelepiped projecting portion 23 projecting from the inner side surface 21 to the left and right outer sides is formed on the left and right inner sides of the front and rear intermediate portion of the left and right forward arm portion 12. The protrusion 23 forms an inner surface 24 that is substantially orthogonal to the left-right direction. On the left and right outer sides of the front and rear intermediate portion of the left and right forward arm portion 12, a fitting concave portion 25 having a polygonal shape in a side view opened to the left and right outer sides is formed. The fitting recess 25 is fitted with the inner end of the lower curved portion of the support column 14 of the armrest 9 and is fixed with a screw (fastening bolt, not shown). The internal space of the fitting recess 25 is formed so as to enter the protrusion 23.

  Referring to FIG. 4, a low protruding portion 26 with a relatively small protruding amount is formed in front of the protruding portion 23 in a stepped manner. The step surface between the protrusion 23 and the low protrusion 26 is a downward inclined surface 27 that is substantially parallel to the left-right direction and inclined downward. The low protruding portion 26 forms a low inner surface 28 that is substantially orthogonal to the left-right direction. The upper surface 29 of the protruding portion 23 and the upper surface 30 of the low protruding portion 26 are flush with each other, and are formed in a stepped shape below the upper edge of the forward arm portion 12. The lower surface 31 of the protruding portion 23 and the lower surface 32 of the low protruding portion 26 are flush with the lower surface 33 of the forward arm portion 12.

  The front end portion 12 a of the forward arm 12 forms a front end inner surface 34 that is flush with the low inner surface 28 of the low protruding portion 26, and also forms a semicircular front end surface 35 that is coaxial with the rotary shaft 19. To do. The upper surface 30 of the low projecting portion 26 forms a sloped upper surface 30a that rises forward behind the front end portion 12a of the forward arm portion 12, and then smoothly joins and continues to the front end surface 35 of the forward arm portion 12.

  On the left and right outer sides of the support base 6, for example, a shaft end portion (not shown) having a regular hexagonal cross section in the rotation shaft 19 protrudes to the left and right outer sides. The shaft end portion is inserted into the hexagonal hole 41 of the auxiliary member 40 with an intermediate fit. The auxiliary member 40 forms a pair of left and right, and is formed to be long in the front-rear direction along the forward arm portion 12 so as to form the left and right inner portions of the front portion of the left and right forward arm portion 12, respectively. The left and right auxiliary members 40 are attached to the rotation shaft 19 so as to be integrally rotatable. By connecting the front portions of the left and right forward arm portions 12 to the left and right auxiliary members 40, the backrest 8A can be tilted to the leg body 6A. Pivoted.

  Referring to FIGS. 3 and 4, the auxiliary member 40 forms a member inner surface 42 that is flush with the inner surface 24 of the protruding portion 23, and faces the lower inner surface 28 of the low protruding portion 26. 42a is formed. The auxiliary member 40 is flush with the upper surface 29 of the protruding portion 23 and the upper surface 30 of the low protruding portion 26, and the inclined upper surface 30 a of the low protruding portion 26 and the front end surface 35 of the forward arm portion 12. It has a side view shape surrounded by a member front end surface 44 formed, a member lower surface 45 flush with the lower surface 33 of the forward arm 12, and an upward inclined surface 46 facing the downward inclined surface 27.

  As shown in FIGS. 4, 6, and 7, the auxiliary member 40 includes the forward arm portion 12 along with the forward upward movement of the forward arm portion 12 (movement in the direction along the line S in FIGS. 6 and 7). The connecting part 47 which connects 12 front parts is provided. The connecting portion 47 is an upward inclined surface 46 that is a rear end surface of the auxiliary member 40, and a concave first engaging portion that is formed on the rear portion of the member outer surface 42a and that opens to the left and right outer sides (forward arm portion 12 side) and downward. 48 and a relatively shallow concave first positioning portion 49 that is formed at the front portion of the member outer surface 42a and opens to the left and right outer sides and downward. The upward inclined surface 46 and the downward inclined surface 27 are formed substantially parallel to the line S. The direction along the line S is also the dividing direction of the auxiliary member 40 and the back support 7.

  In the first engagement portion 48, an upper end surface 51 that is substantially orthogonal to the line S and an inner peripheral surface 52 that extends downward from the upper end surface 51 in the direction along the line S with a predetermined draft angle are formed. A screw insertion hole 53 that penetrates the upper end surface 51 along the line S is formed above the upper end surface 51. On the upper part of the screw insertion hole 53, a seat 54 is formed for allowing the head of a screw (fastening bolt) 69 inserted from above to enter.

  In the first positioning portion 49, a semicircular upper end inner peripheral surface 55 coaxial with the rotation shaft 19, and spread from the front and rear ends of the upper end inner peripheral surface 55 downward in the direction along the line S at a predetermined draft angle. Front and rear surfaces 55a and 55b extending to the member lower surface 45, and an inner displacement surface 56 that is displaced stepwise from the member outer surface 42a to the left and right inner sides in a region surrounded by the upper end inner peripheral surface 55 and the front and rear surfaces 55a and 55b. Is formed. A hexagonal hole 41 that passes through the inner displacement surface 56 coaxially with the rotation shaft 19 is formed on the inner side of the inner displacement surface 56.

  Referring to FIG. 4, an arm side connecting portion 57 that engages with the connecting portion 47 of the auxiliary member 40 is provided on the left and right inner sides of the front portion of the forward facing arm portion 12. The arm side connecting portion 57 engages the downward inclined surface 27 formed by the protruding portion 23, the convex second engaging portion 58 that engages with the first engaging portion 48, and the first positioning portion 49. And a convex second positioning portion 59.

  The second engaging portion 58 includes an upper end surface 61 that is substantially orthogonal to the line S and an outer peripheral surface 62 that extends from the upper end surface 61 in a direction along the line S downward at a predetermined draft angle. The second engagement portion 58 is formed with a nut hole 63 that passes through the second engagement portion 58 along the line S. The upper end surface 61 of the second engagement portion 58 hits the upper end surface 51 in the first engagement portion 48 from below and defines the vertical position of the forward arm portion 12 with respect to the auxiliary member 40. The outer peripheral surface 62 of the second engagement portion 58 is generally aligned with the inner peripheral surface 52 in the first engagement portion 48 and defines the position of the nut hole 63 with respect to the screw insertion hole 53. Under the neck of the screw 69 inserted from above into the screw insertion hole 53 is screwed into the nut hole 63. The lower end surface 64 of the second engagement portion 58 is flush with the lower surface 33 of the forward arm portion 12.

  The second positioning portion 59 includes an upper end outer peripheral surface 65 that substantially matches the upper end inner peripheral surface 55 of the first positioning portion 49, and front and rear surfaces 65a and 65b that substantially match the front and rear surfaces 55a and 55b of the first positioning portion 49. And an inner displacement surface 66 that is displaced stepwise from the front inner surface 34 in the region surrounded by the upper outer peripheral surface 65 and the front and rear surfaces 65a and 65b. The inner displacement surface 66 is formed with a screw insertion hole 67 that passes through the inner displacement surface coaxially with the rotation shaft 19. Referring also to FIG. 5, on the left and right outer sides of the screw insertion hole 67, a counterbore 68 for entering the head of a screw (fastening bolt) 70 inserted from the left and right outer sides is formed.

The left and right auxiliary members 40 are attached to the rotation shaft 19 on the left and right outer sides of the support base 6 by pushing the shaft end portion of the rotation shaft 19 into the hexagonal hole 41.
The procedure for connecting the backrest 8A (backrest support 7) to the left and right auxiliary members 40 is as follows. First, the left and right forward arms 12 positioned below the line S of the left and right auxiliary members 40 are moved along the line S. The slanting surfaces 27 and 46 are brought into sliding contact with each other, and the engaging portions 48 and 58 and the positioning portions 49 and 59 are engaged with each other. The downward inclined surface 27, the second engagement portion 58, and the second positioning portion 59 of the forward arm 12 are linear with respect to the upward inclined surface 46, the first engagement portion 48, and the first positioning portion 49 of the auxiliary member 40. Engage only by upward movement along S. For this reason, even if the left and right forward arm 12 is integrated behind the support base 6, the left and right auxiliary arm 40 can be easily engaged with the left and right auxiliary member 40.

The upper end surface 61 of the second engaging portion 58 of the left and right forward arm portion 12 and the upper outer peripheral surface 65 of the second positioning portion 59 are the upper end surface 51 of the first engaging portion 48 of the left and right auxiliary member 40 and the first positioning portion 49. It hits against the inner peripheral surface 55 of the upper end from below. Thereby, the upward movement of the left and right forward arm portion 12 with respect to the left and right auxiliary member 40 is stopped, and the upper and lower relative positions thereof are defined. This state is defined as a state in which the left and right forward arms 12 are fully engaged with the left and right auxiliary members 40.
In this state, if the support of the backrest support 7 is removed by, for example, releasing the hand from the backrest support 7, the connection portion 47 and the arm side connection portion 57 are engaged with each other. In the arm side connecting portion 57, a backward moment is generated due to the weight behind the front portion of the left and right forward arm portion 12 in the backrest 8A. Note that the phrase “eliminating the support of the backrest support 7” includes releasing the backrest support 7 from an assembling jig or the like that supports the backrest support 7.

  At this time, in the connecting portion 47 and the arm-side connecting portion 57, the lower end portions of the inclined surfaces 27 and 46, the inner peripheral surface 52 of the first engaging portion 48, and the rear upper end portion of the outer peripheral surface 62 of the second engaging portion 58. Contact points T1 and T2 that are press-contacted by the moment are generated in the part (see FIG. 7). These two contact points T1, T2 are arranged on the rear inclined surface 27 of the arm side connecting portion 57 and the second engaging portion 58 so that a moment in the opposite direction (forward direction) to the moment is generated in the arm side connecting portion 57. Generates a reaction force against the input of the moment around. The backrest 8A is in a state in which the left and right forward arm portions 12 are fully engaged with the left and right auxiliary members 40 by the pressure contact of both the inclined surfaces 27 and 46 at the contact point T1 and the pressure contact of both the engagement portions 48 and 58 at the contact point T2. Is temporarily held.

  That is, the connecting portion 47 of the auxiliary member 40 is engaged with different positions of the front portion of the forward arm portion 12 so that a moment opposite to the moment due to the weight of the backrest 8A behind the front portion is generated. A plurality of engagement holding portions (each inclined surface 27, 46 and each engagement member) generate a reaction force at the front portion of the forward arm portion 12 and hold the forward arm portion 12 and thus the backrest 8A so as not to fall off by the reaction force. Joint portions 48, 58). Also at the contact T3 at the upper end position between the upper end inner peripheral surface 55 of the first positioning portion 49 and the upper end outer peripheral surface 65 of the second positioning portion 59, a reaction force against the input of the backward moment is generated. The load on T1 and T2 is reduced.

  In a state where the forward arm 12 is temporarily held by the auxiliary member 40, the screw insertion hole 53 and the nut hole 63 are positioned by the engagement of the engaging portions 48 and 58, and the positioning portions 49 and 59 are connected to each other. The front end 12a of the forward arm 12 and the front of the auxiliary member 40 and the rotation shaft 19 are positioned by the engagement. In this state, the screw 69 inserted from above into the screw insertion hole 53 is screwed into the nut hole 63 of the second engaging portion 58 and tightened, and the screw 70 inserted from the left and right outer sides into the screw insertion hole 67 is rotated. The connection of the left and right forward arms 12 to the left and right auxiliary members 40 is completed by screwing and tightening to the shaft end portion 19. The insertion and fastening of the screws 69 and 70 are easy because the screw insertion holes 53 and 67 and the fastening holes are positioned, and the connecting process of the forward arm 12 and the auxiliary member 40 can be shortened.

As described above, the chair 1 in the above embodiment is configured such that the left and right forward arms 12 of the backrest 8A are connected to the left and right auxiliary members 40 attached to the legs 6A with upward movement, The connecting portion 47 of the auxiliary member 40 is engaged with a different position of the front portion of the front arm portion 12 so that a moment opposite to the moment due to the weight of the backrest 8A behind the front portion is generated. It has a plurality of engagement holding portions (upward inclined surfaces 46 and first engagement portions 48) that apply a reaction force to the front portion and hold the backrest 8A so as not to drop off due to the reaction force.
According to this configuration, the backrest 8A in which the left and right forward arms 12 are integrated by the upward movement of the forward arms 12 with respect to the auxiliary member 40 can be easily assembled. Further, the moment due to the weight of the backrest 8A can be distributed to the plurality of engagement holding portions of the auxiliary member 40, and the backrest 8A can be temporarily held at the assembly position by the action of the plurality of engagement holding portions.

  In the chair 1, the plurality of engagement holding portions include an upward inclined surface 46 and a concave first engaging portion 48, and the front portion of the forward arm portion 12 faces the upward inclined surface 46. By having the downward inclined surface 27 and the convex second engagement portion 58 for engaging the first engagement portion 48, it becomes possible to form a plurality of engagement holding portions in a simple shape, A plurality of engagement holding portions of the connecting portion 47 and the front portion of the forward arm portion 12 engaged with the plurality of engagement holding portions can be easily formed.

  Further, the chair 1 has the first engagement portion 48 and the second engagement portion 58 that abut against each other and are fastened in the abutting direction so that the front arm 12 is directed upward with respect to the auxiliary member 40. The forward arm 12 can be easily positioned when moved to the position, and the forward arm 12 can be fastened to the auxiliary member 40 in this state.

  The upper chair 1 is a screw parallel to the pivot shaft 19 at the shaft end of the pivot shaft 19 in a state where the front portion of the forward arm 12 is engaged with the auxiliary member 40 so as to overlap from the left and right outer sides. In the configuration fastened by 70, the left and right outer sides of the auxiliary member 40 have concave first positioning portions 49 that engage with the left and right inner sides of the front part of the forward arm part 12, and the left and right parts of the front part of the forward arm part 12 are left and right. By having the convex second positioning portion 59 that engages with the first positioning portion 49 on the inner side, the forward arm portion 12 and the auxiliary member 40 can be easily positioned with reference to the rotation shaft 19.

  The present invention is not limited to the above-described embodiment. For example, a convex first engagement portion is provided in the connecting portion 47 of the auxiliary member 40 and the first engagement is provided in the front portion of the forward arm portion 12. You may provide the concave 2nd engaging part which engages a part. Similarly, a convex first positioning portion may be provided in the connecting portion 47 of the auxiliary member 40 and a concave second positioning portion for engaging the first positioning portion with the front portion of the forward arm portion 12 may be provided. .

FIG. 8A schematically shows the above embodiment. In this way, in contrast to the configuration in which the convex second engaging portion 58 of the forward arm 12 is engaged with the concave first engaging portion 48 of the auxiliary member 40, FIG. A configuration in which the concave second engaging portion 58 ′ of the forward arm 12 is engaged with the convex first engaging portion 48 ′, and contacts T1 ′ and T2 ′ are set therebetween. Further, FIG. 8 (c) shows that the concave first engaging portion 48 "of the auxiliary member 40 and the convex second engaging portion 58" of the forward arm portion 12 do not have a matching shape, but have protrusions and contact points. A configuration in which T1 ″ and T2 ″ are set is shown.
And the structure in the said embodiment is an example of this invention, A various change is possible in the range which does not deviate from the summary of the said invention.

1 Chair 6A Leg 8 Backrest body (standing part)
8A Backrest 12 Forward arm part 19 Rotating shaft 27 Downward inclined surface (second inclined surface)
40 Auxiliary member 46 Upward inclined surface (engagement holding portion, first inclined surface)
47 connecting portion 48 first engaging portion (engagement holding portion)
49 1st positioning part 58 2nd engaging part 59 2nd positioning part 70 Screw (shaft end screw)

Claims (4)

In a chair comprising a leg and a backrest supported by the leg,
The backrest extends forward from the lower side of the upright portion that supports the back of the seated person, and the front portion is disposed on the left and right outer sides of the leg, and the pair of left and right forward arms, and the left and right outer sides of the leg. An auxiliary member that is attached to the projecting pivot shaft so as to be integrally rotatable, and has a connecting part that connects the front part of the forward arm part with upward movement of the forward arm part,
The connecting portion engages with different positions of the front portion of the forward arm portion so that a counterclockwise moment is generated opposite to the moment due to the weight of the backrest behind the front portion. A chair having a plurality of engagement holding portions that apply force and hold the backrest so as not to fall off by the reaction force. The plurality of engagement holding portions include an upward first inclined surface and a convex or concave first engagement portion,
The front portion of the forward arm portion has a downward second inclined surface facing the first inclined surface, and a concave or convex second engaging portion that engages the first engaging portion. The chair according to claim 1.   The chair according to claim 2, wherein the first engagement portion and the second engagement portion abut against each other and are fastened in the abutting direction. In a state where the front part of the forward arm is engaged with the auxiliary member so as to overlap from the left and right outer sides, it is fastened to the shaft end of the rotating shaft by a shaft end screw parallel to the rotating shaft,
On the left and right outer sides of the auxiliary member, a convex or concave first positioning portion that engages with the left and right inner sides of the front portion of the forward arm portion,
4. The concave or convex second positioning part that engages with the first positioning part is provided on the left and right inner sides of the front part of the forward arm part, according to claim 1. Chair.

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