JP5543117B2 - Chair backrest device - Google Patents

Description

  The present invention relates to a chair backrest device in which a tension material is stretched on the front surface of a backrest frame of the backrest.

In so-called office chairs, the backrest is supported by the upper part of the backrest support frame that extends upward from the legs and pivots around the pivot in the left-right direction as necessary. What has a structure is common.
In recent years, many have been developed in which the backrest is constructed by stretching an elastic tension material on the front side of the backrest frame that is closed on all sides and has a space at the center.

  Some backrests in such a chair have, for example, a structure in which the backrest support frames are paired on the left and right sides, and the upper part of the left and right backrest support frames and the lower part of the backrest frame are connected in place. (See Patent Documents 1 and 2).

  However, in the backrest structures described in Patent Documents 1 and 2, since the contact area between the backrest support frame and the backrest frame during connection is large, the connection strength can be increased, but the rotation of the backrest support frame can be increased. It is difficult to make a structure that gives movement to the backrest by movement.

  Further, like the backrest in the chair described in Patent Document 3, the connecting piece formed on the upper portion of the backrest frame is sandwiched between the side vertical frame portion and the upper horizontal frame portion constituting the backrest support frame. Some have a structure that is pivotally supported.

  However, although the structure described in Patent Document 3 is an effective structure when the backrest frame and the backrest support frame are relatively rotatable, the number of parts and the number of assembly steps are increased, resulting in a complicated structure. In order to achieve a structure and secure design, it is necessary to reduce the size of each component. As a result, the support area between the backrest frame and the backrest support frame is reduced, and the connection strength is reduced. There was a problem that was inferior.

JP 2006-102130 A JP 2008-104523 A Japanese Patent No. 4105914

  In view of the above-described present situation, the present invention provides a chair backrest device that can firmly connect a backrest frame and a backrest support frame that constitute a backrest with an uncomplicated structure. It is aimed.

  The above-described problems are solved by the invention having the following configuration, as described in each claim in the section “Claims”.

(1) An upper end of a back support frame that includes a back frame made of a belt-like frame member having a space at the center and a tension member that closes the space, and stands up from the rear of the seat A backrest device for a chair that supports the backrest frame on a portion thereof, and is arranged so as to be opposed to each other in the left-right direction at substantially the middle position in the vertical direction at the inner edge in the left-right direction of the backrest frame. The backrest is formed in a state in which a pair of left and right projecting portions projecting in the direction is formed, and a rear surface of the projecting portion integrally formed with the backrest frame and a front surface of the upper end portion of the backrest support frame face each other. The upper end portion of the support frame is pivotally supported by the projecting portion so as to be capable of rotating by a predetermined angle around the axis of the pivot that faces in the left-right direction , and also in a direction deviating from the axis of the pivot .

(2) In the above item (1), the overhanging portion bulges backward.

(3) In the above item (1) or (2), a buffer member made of a soft elastic body is sandwiched between the rear surface of the overhang portion and the front surface of the upper end portion of the backrest support frame.

According to the present invention, the following effects can be obtained.
According to the first aspect of the present invention, the pair of left and right projecting portions projecting inward so as to be opposed to each other in the left-right direction is provided at substantially the middle position in the vertical direction on the inner edge in the left-right direction of the backrest frame. Since it is formed, the backrest frame constituting the backrest can be easily molded.
In addition, since the load applied to the backrest frame during reclining acts in the bending direction of the backrest frame as the backrest leans backward, the bending strength of the backrest frame itself is improved by forming an overhanging portion. be able to.
Furthermore, the formation of the overhanging portion can sufficiently secure the area required for the connection between the backrest frame and the backrest supporting frame with a wide area of the overhanging portion, so that the backrest frame and the backrest supporting frame can be secured. Can be connected to each other with a strong and uncomplicated structure.
Furthermore, since the upper end portion of the backrest support frame is pivotally supported on the overhanging portion by a pivot that faces in the left-right direction, the upper end portion of the backrest support frame can reliably follow the reclining operation of the backrest frame.
In addition, since the upper end of the backrest support frame is pivotally supported by the overhanging portion so as to be able to rotate at a predetermined angle in a direction deviating from the axis of the pivot, the backrest support frame smoothly rotates following the backrest movement. be able to.

  According to the second aspect of the present invention, since the overhanging portion is bulged rearward, the strength of the backrest frame can be further increased. The strength of the backrest frame can be ensured.

According to invention of Claim 3 , since the buffer member which consists of a soft elastic body is clamped between the rear surface of the overhang | projection part, and the upper end part front surface of a backrest support frame, With long-term use of a chair Further, it is possible to effectively prevent the connecting portion between the backrest frame and the upper portion of the backrest support frame from being worn or damaged.

It is a perspective view of the chair provided with the backrest apparatus of one Embodiment in this invention. (Example) Similarly, it is a rear view. Similarly, it is a side view. It is an expansion perspective view of the frame in the state where the tension member is not stretched. It is the disassembled perspective view seen from the front of the frame in the state where the tension member is not stretched. Similarly, it is the disassembled perspective view seen from the back of a frame. FIG. 7 is an enlarged vertical cross-sectional view of a stretched state of a tension member taken along line VII-VII in FIG. 4. FIG. 5 is an enlarged cross-sectional view of a stretched state of a tension member taken along line VIII-VIII in FIG. 4. FIG. 5 is an enlarged vertical cross-sectional view of a stretched state of a tension member taken along line IX-IX in FIG. 4. FIG. 5 is an enlarged longitudinal sectional view of a tensioned state of the tension member taken along line XX in FIG. 4. FIG. 4 is an enlarged cross-sectional view of a main part showing a connection state between a frame body and a backrest support frame taken along line XI-XI in FIG. 3. Similarly, it is a disassembled perspective view which shows the connection state of a frame and a backrest support frame.

  An embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view of a chair provided with a backrest device according to an embodiment of the present invention, FIG. 2 is a rear view, and FIG. 3 is a side view.
In the present embodiment, a reclining chair will be described as an example.

  As shown in FIGS. 1 to 3, the reclining chair 1 of the present invention includes a leg body 4 having five leg rods 3 having a radial shape with a caster 2 provided at the tip, and a center of the leg body 4. A telescopic leg column 5 provided with a gas spring (not shown) standing upright and a backrest 7 erected via a support base 6 having a rear portion fixed to the upper end of the leg column 5. Yes.

  The support base 6 has a substantially hollow box shape whose upper surface is open, and the opening portion of the upper surface is covered with a removable cover (not shown), and in the direction in which the backrest 7 stands, That is, a biasing means for biasing forward, a biasing means for biasing the seat 8 forward (both not shown), etc. are provided, but these are not directly related to the present invention. Therefore, illustration and detailed description are omitted.

A hexagonal column-shaped pivot 9 that faces in the left-right direction is pivotally supported at the rear portion of the support base 6 so as to be rotatable about the center axis, and both ends of the pivot 9 are connected to both side walls of the support base 6. Projected left and right.
The pivot 9 is provided in the support base 6 by a biasing means (not shown) made of, for example, a torsion coil spring, and the like. 10 is erected in the direction in which it stands up, that is, counterclockwise in FIG.
The first backrest support rod 10 constitutes a backrest support frame with a second backrest support rod (link 16) to be described later, and the front end portions thereof are fixed to both ends of the pivot 9. It is designed to rotate integrally around the axis.

  As shown in FIG. 3, the first back support ridge 10 has an upright portion 10a facing upward and a forward portion 10b facing forward through a bent portion 10c, as shown in FIG. In addition, it is formed so as to be substantially L-shaped in side view.

  The standing portion 10a is composed of a pair of left and right standing ridges 11 and 11 extending upwardly in a bifurcated manner from the bent portion 10c, and the forward portion 10b extends forwardly in a bifurcated shape from the bent portion 10c. The left and right pairs of forward saddles 12 and 12 are projected to the left and right hexagonal holes 13 and 13 provided at the front ends of the forward and backward pairs 12 and 12, respectively. Is fixed.

  The left and right standing rods 11 and 11 extend in an arc shape obliquely upward and upward from the bent portion 10c, and the left and right forward rods 12 and 12 extend diagonally outward and downward to the first back. The bending support rod 10 has an X-shape when viewed from the rear, and the lateral width of the bent portion 10c, which is the intersection of the center, is larger than the lateral width of each standing rod 11 and forward rod 12, and is substantially spherical toward the rear. It is supposed to bulge out.

A continuous shallow concave portion 14 is provided on the rear surface of the bent portion 10c and the upright rods 11 and 11 and on the portion from the rear surface of the left and right forward saddles 12 and 12 to the rear portion of the lower surface. A protective cover 15 made of a soft synthetic resin material, rubber, or other cushioning material is attached to the recess 14 with an adhesive or a hook-and-loop fastener so as to cover the rear surface of the first backrest support rod 10, or It is detachably fitted by screwing as necessary.
The thickness of the protective cover 15 is preferably substantially equal to the depth of the recess 14 so that the surface of the protective cover 15 and the surface of the first back support rod 10 are aligned so that no step is generated.
By providing such a protective cover 15 on the first back support rod 10, the first back support rod 10 comes into contact with other objects when the reclining chair 1 is turned, and the first back support rod 10 may be damaged. It is possible to reliably prevent the back support heel 10 itself from being damaged.
In particular, the lower surface of the forward facing portion 10b of the first backrest support rod 10 comes into contact with the upper corner portion of the lower floor-mounted object and damages it, or the first backrest support rod 10 itself is damaged. Can be prevented.

  The portion of the support base 6 behind the pivot 9 and the lower portion of the backrest 7 above it are connected by a link 16 that constitutes a second backrest support frame (backrest support frame). When the leaning support rod 10 is tilted rearward, the lower portion of the backrest 7 is pushed backward with respect to the first backrest supporting rod 10 by a link 16 that is rotated rearward and downward.

That is, the front end portion of the link 16 is pivotally supported by the support base 6 behind the front end portion of the first back support rod 10 pivotally supported by the pivot 9 with a shaft 17 facing left and right. The rear end portion is connected to the lower end portion of the mounting bracket 18 fixed to the rear surface of the lower end portion of the backrest 7 so as to project downward from the backrest 7 by pivoting with a shaft 19 facing in the left-right direction.
Thereby, it is possible to prevent an excessive load from being applied to the peripheral edge portion of the frame 29 with respect to the movement of the backrest 7.

  The link 16 is a rigid body having a circular arc when viewed from the side with the center of curvature located above (or below) the link 16, and is disposed between the left and right forward saddles 12, 12 of the first backrest support rod 10. In this way, it is sandwiched between the two forward-facing rods 12 and 12 so as not to be exposed to the outside.

  The rear and front portions of the seat support 20 that supports the seat 8 so as to be adjustable in the front-rear position are guided rearwardly and downwardly in conjunction with the rearward tilt of the first backrest support rod 10. (No symbol) and the front support means 22 are supported by the support base 6.

The rear support means is configured such that the upper end portion of the link 24 whose lower end portion is pivotally attached to the portion of the support base 6 behind the pivot shaft 9 and forward of the shaft 17 of the link 16 with the shaft 23 in the left-right direction is seat support 20. It is pivotally attached to the rear portion, and the upper end portion of the link 24 is slidable in the front-rear direction to the portion behind the shaft 23 at the lower end portion of the link 24 in each forward saddle 12 of the first backrest support rod 10. As fitted.
The upper end portion of the link 24 is fitted to an upward projecting piece 10d provided at a portion slightly rearward from the hexagon hole 13 in each forward saddle 12 of the first back support rod 10 so as to be slidable in the front-rear direction.

The front support means 22 is configured such that a left and right shaft 25 provided at the front portion of the seat support 20 is slidably fitted into a long hole 26 provided at the support base 6 and directed downward.
The shaft 25 is constantly urged forward by an urging means (not shown) provided in the support base 6.

  FIG. 4 is an enlarged perspective view of the frame body when the tension member is not stretched, FIG. 5 is an exploded perspective view when viewed from the front of the frame body when the tension member is not stretched, and FIG. 7 is an exploded perspective view as seen from the rear side, FIG. 7 is an enlarged vertical sectional view of the tensioned state of the tension member taken along the line VII-VII of FIG. 4, and FIG. 8 is the tension of the tension member taken along the line VIII-VIII of FIG. FIG. 9 is an enlarged longitudinal sectional view of the tensioned state of the tension member taken along the line IX-IX of FIG. 4, and FIG. 10 is a tensioned state of the tension material taken along the line XX of FIG. It is an enlarged vertical sectional view.

As shown in FIGS. 4 to 6, the backrest 7 is a backrest frame in which a mesh-like tension member 27 and the tension member 27 are stretched on the front surface and can close the space portion 28 opened in the center. A certain frame 29 is used.
The frame 29 is made of a synthetic resin band plate-like frame member that is continuous in the circumferential direction, and includes an upper horizontal frame portion 30A and a pair of left and right side vertical frame portions 30B and 30B having a desired rearward tilt state. A main frame 30 having a substantially square shape in front view continuous in the circumferential direction is provided by the lower horizontal frame portion 30C.

  As shown in FIG. 7, the upper horizontal frame portion 30A that forms a part of the peripheral edge of the main frame 30 has an arcuate curved surface whose front surface is inclined upward and is thick from the inner edge toward the outer edge. In addition, an engaging groove portion 31 is provided along the left-right direction at the rear end portion of the outer peripheral edge. The engaging groove portion 31 engages with the edge member 27a provided on the peripheral portion of the tension member 27.

  As shown in FIG. 8, the side vertical frame portion 30 </ b> B has a cross-sectional shape extending from the inner edge of the thick portion where the outer edge side is thick toward the space portion 28 so as to become a thin portion. On the outer edge, an engagement groove 32 that engages with the edge 27a provided on the peripheral edge of the tension member 27 is provided along the vertical direction so as to communicate with the engagement groove 31. It has been.

As shown in FIGS. 5 and 6, the lower horizontal frame portion 30 </ b> C is divided into two in the thickness direction in the front-rear direction, leaving a part of the left and right ends, and the rear surface side is a base portion 33. A part of the center part in the left-right direction is cut off at a desired interval, and the opposed end parts 34a, 34a of the cut-out part 34 are assembled with the rear face facing the front face of the base part 33. It is connected by a connecting frame 35.
A fitting portion 36 that fits into the cut-out portion 34 of the base portion 33 protrudes rearward from the central portion of the connecting frame 35 in the left-right direction, and the fitting portion 36 is provided in the main frame 30. In the initial state, the width dimension is substantially the same as the distance dimension between the opposed surfaces of the opposed end portions 34a, 34a of the cut portion 34.

Note that the mounting bracket 18 to which the rear end of the link 16 pivotally supported by the lower part of the frame body 29 forming the backrest 7 is attached with the shaft 19 straddles between the opposed end portions 34a and 34a in the cut portion 34, It is fixed to the rear surface of the base portion 33.
Thereby, at the time of reclining of the backrest 7, the base portion 33 can be elastically deformed against a load caused by the link 16 applied to the center of the rear surface of the base portion 33 via the mounting bracket 18.

The connection frame 35 is formed with a pair of left and right fastening portions 37, 37 extending from both front side ends of the fitting portion 36 toward the front side of the opposed ends 34 a, 34 a of the cut portion 34 of the base 33. Has been.
The rear surfaces of these fastening portions 37 are in contact with the front surfaces of the opposed end portions 34a and 34a of the cut portion 34, and are placed on the front surface of the base portion 33 so as to straddle between the opposed end portions 34a and 34a of the cut portion 34. Each is to be fastened.

As shown in FIGS. 9 and 10, the lower horizontal frame portion 30C is formed in a thick cross-sectional shape having a hollow structure as shown in FIGS. A plurality of ribs 38 and 39 along the longitudinal direction in the up-down direction and the left-right direction are respectively provided on the portion so as to project in the front-rear direction.
Further, the end portions of the ribs 38 facing the facing surfaces of the facing end portions 34a and 34a in the cutout portion 34 of the base portion 33 come into contact with the left and right end surfaces of the fitting portion 36 when the connecting frame 35 is assembled to the base portion 33. It is the contact part 38a.

A bolt insertion hole 40 is provided in the vicinity of the rib 38 in the base portion 33, and a fitting portion is provided in the vicinity of the rib 39 in the left and right fastening portions 37 of the connecting frame 35 facing the bolt insertion hole 40. A plurality of female screw holes 41 are provided on the left and right sides of 36.
As shown in FIG. 9, bolts 42 inserted through the bolt insertion holes 40 are screwed into the female screw holes 41 from the rear of the base portion 33, and the bolts 42 connect the base portion 33 to the left and right sides of the connection frame 35. The fastening portion 37 is fastened.

The left and right fastening portions 37 in the connecting frame 35 are divided into two parts on the left and right sides. The divided portions 37A are provided with a plurality of bolt insertion holes 43 so as to face the bolt insertion holes 43. The bolts 45 are respectively inserted from the front through the bolt insertion holes 43 and screwed into the female screw holes 44 provided in the front surface of the base portion 33 so that the divided portion 37A is fixed to the front surface of the base portion 33. It has come to be.
In this way, by dividing the fastening 37 of the connecting frame 35, the base 33 can be easily elastically deformed with respect to the load applied to the center of the rear surface of the base 33 during the reclining of the backrest 7, and stress concentration can be reduced. Dispersion can be achieved, and an allowable range of processing accuracy for the base 33 can be expanded.

  The vicinity of the female screw hole 41 in the connecting frame 35 is a protruding portion 46 protruding rearward, and this protruding portion 46 is a recess formed in the vicinity of the bolt insertion hole 40 of the base portion 33 in the fastened state as shown in FIG. 47 can be engaged.

  A groove portion 48 is formed on the rear surface of the fastening portion 37 in the connection frame 35, and the groove portion 48 is opposed to the front surfaces of the opposed end portions 34 a and 34 a in the cut portion 34 of the base portion 33, thereby the side portion. The engaging groove portion 32 provided on the vertical frame portion 30B and the engaging groove portion 36a provided on the lower surface of the fitting portion 36 can communicate with each other, and the edge member 27a provided on the peripheral edge portion of the tension member 27 is engaged. It has come to be.

The upholstery 27 has an engagement groove 31, 32 and groove 48 formed on the peripheral edge of the main frame 30, and an edge member 27a provided on the peripheral edge of the upholstery 27 is directed rearward from the front side of the main frame 30. By being folded and engaged so as to be wound around, the entire space on the front surface side of the frame body 29 is stretched and the space portion 28 at the center of the frame body 29 can be closed.
As a result, the tension member 27 can be stretched in a tensioned state over the entire front surface of the frame body 29, and the entire front surface of the frame body 29 is covered with the tension material 27. Can be given.

  The upholstery material 27 is preferably a net-like or mesh-like material in which a high-tensile plastic or other elastic fiber is knitted or woven into a net shape, but is simply a woven fabric, a synthetic resin sheet, a porous seal. You may form with a material etc.

Next, the procedure for tensioning the tension member 27 to the frame 29 will be described below.
First, in a state where the connecting frame 35 is removed from the main frame 30 while leaving the divided portion 37A of the fastening portion 37 in the base portion 33, the left and right side vertical frame portions 30B in the main frame 30 are resisted against the elastic force. Then, as shown by an imaginary line in FIG. 5, the base end 33 is elastically deformed in a shrinking direction in which the opposed end portions 34 a and 34 a of the cut portion 34 can approach each other.

  In this state, the tension member 27 is folded around the periphery of the main frame 30 so as to be wound from the front side toward the rear, and the engagement grooves 31, 32, and 36a formed on the periphery of the main frame 30 are inserted into the engagement grooves 27, 32, and 36a. The tension member 27 is attached to the peripheral portion of the main frame 30 in a tensioned state by engaging the edge member 27 a provided on the peripheral portion.

Next, the left and right side vertical frame portions 30B of the main frame 30 are expanded to an initial state using the elastic return force, and are connected to the front surface of the base portion 33 with further tension applied to the tension member 27. The rear surface of the frame 35 is assembled, and the fitting portion 36 of the connecting frame 35 is fitted so that the left and right end faces thereof can come into contact with the contact portion 38a on the opposing surface between the opposing end portions 34a and 34a of the cut portion 34. After that, the opposite end portions 34 a and 34 a of the cut portion 34 are connected to each other by fastening the left and right fastening portions 37 and 37 in the connection frame 35 with bolts 42.
Thereby, the tension member 27 can be stretched with high work efficiency without performing complicated processing, and the tension of the tension member 27 can be uniformly maintained over the entire frame body 29.

  When the connection frame 35 is fixed to the front surface of the base portion 33, for example, a downward claw is provided on the rear upper edge of the fixing portion 37 and the split portion 37A, and an upward claw is provided on the lower rear edge thereof. May be engaged with the front surface of the base portion 33 so that the vertical displacement of the connecting frame 35 with respect to the base portion 33 may be effectively prevented.

The upper part of the first back support rod 10 constituting the back support frame is connected to the rear portion of the frame body 29 by being pivotally supported.
That is, as shown in FIG. 4, the space portion 28 can be opposed to each other in the left-right direction at substantially the middle position in the up-down direction on the inner edge in the left-right direction of the left and right side vertical frame portions 30 </ b> B of the main frame 30. A pair of left and right projecting portions 49 projecting inward toward the rear are formed to bulge rearward.
At the rear end of the overhanging portion 49, as shown in FIG. 2, the upper end portions 11 a of the left and right upright rods 11 in the first backrest support rod 10 can follow the reclining operation of the backrest 7. It is connected so as to be rotatable in a non-directional direction with a desired limit range at a required angle around an axis line substantially in the left-right direction and in a direction deviating from the axis line.

  The left and right overhang portions 49 are inclined inward toward each other so that the center axis thereof can be aligned with the concave curved surface of the frame body 29 facing forward (see FIGS. 4 and 6). ), And tilted upward toward the front so as to match the rearward tilt angle of the frame body 29 (see FIG. 3).

  FIG. 11 is an enlarged cross-sectional view of the main part showing the connection state between the frame body and the backrest support frame along the line XI-XI in FIG. 3, and FIG. 12 shows the connection state between the frame body and the backrest support frame. It is a disassembled perspective view shown.

As shown in FIGS. 11 and 12, a convex shaft 51 fixed by a fixing screw 50 is provided on the front surface of the upper end portion 11a of the left and right upright rods 11 in the first backrest support rod 10 so as to protrude forward. In addition, the front end of the convex shaft 51 is a spherical sliding contact surface 52, and a shaft hole 53 is formed in the sliding contact surface 52 so as to penetrate substantially in the left-right direction.
In the shaft hole 53, tapered hole portions 54 and 54 that gradually increase in diameter toward the outside are formed on the left and right sides from the center portion of the sliding contact surface body 52.

On the other hand, the overhanging portion 49 of the side vertical frame portion 30B is provided with a fitting hole 55 that opens backward, and the fitting hole 55 has a receiving tube in which a receiving hole 56 opens backward. The member 57 is fitted.
The sliding contact surface body 52 of the convex shaft 51 is inserted into the receiving hole 56 of the receiving cylinder member 57 from the rear side so as to be slidable. 58 is loosely fitted, and both left and right end portions of the retaining pin 58 are inserted and locked in locking holes 59 provided on the left and right sides of the receiving cylinder member 57, whereby the convex shaft 51 and the receiving cylinder member 57 are locked. Are connected to each other.

A bolt shaft 60 protrudes forward from the front end of the receiving member 57, and the bolt shaft 60 passes through the bottom end of the fitting hole 55 of the projecting portion 49. The tube member 57 is projected toward the front side of the overhanging portion 49 through the hole 61, and the nut 62 is screwed and fastened to the protruding shaft portion 60a from the front, so that the receiving cylinder member 57 can The fitting portion 55 of the protruding portion 49 is firmly fixed.
As a result, the upper end portions 11a of the left and right upright rods 11 in the first backrest support rod 10 can be rotated around the axis of the retaining pin 58 and can also be rotated at a required angle in a direction deviating from the axis. The rear portion 49 is connected to the rear portion.

A buffer member 63 made of a soft elastic body such as an elastomer is sandwiched between the front surface of the upper end portion 11 a of the standing rod 11 and the rear end surface of the overhang portion 49.
The buffer member 63 can prevent the connection portion between the frame body 29 and the upper portion of the first backrest support rod 10 from being worn or damaged with the long-term use of the chair.

A cap member 64 is crowned from the front of the overhanging portion 49 to the fastening portion between the projecting shaft portion 60a of the bolt shaft 60 and the nut 62 exposed in front of the overhanging portion 49, and the fastening portion is exposed to the outside. Prevents exposure.
The cap member 64 is attached to the front surface of the overhang portion 49 by press-fitting a fixing rod 65 projecting rearward from the inner center thereof into a fixing hole 66 opened at the front end of the bolt shaft 60. Yes.

  A gap a is provided at a desired interval between the front surface of the cap member 64 and the rear surface of the tension member 27 stretched on the front surface of the frame body 29. For example, when the backrest 7 is reclined. Even if the tension member 27 is bent backward by the back of the seated person, the bolt shaft 60 and the nut 62 are prevented from contacting the cap member 64 by the gap a or by elastic deformation of the cap member 64. The fastening portion is provided with a cushioning action so that it does not directly hit the back of the seated person.

DESCRIPTION OF SYMBOLS 1 Reclining chair 2 Caster 3 Leg pad 4 Leg body 5 Pillar 6 Support base 7 Backrest 8 Seat 9 Axis 10 1st backrest support collar (backrest support frame)
10a Standing portion 10b Forward portion 10c Bending portion 10d Upward protruding piece 11 Standing rod 11a Upper end portion 12 Forward rod 13 Hexagonal hole 14 Recess 15 Protective cover 16 Link (second backrest support rod)
17 Shaft 18 Mounting bracket 19 Shaft 20 Seat support body 22 Front support means 23 Shaft 24 Link 25 Shaft 26 Long hole 27 Tension material 27a Edge material 28 Space 29 Frame (Backrest frame)
30 Main frame 30A Upper horizontal frame part 30B Side vertical frame part 30C Lower horizontal frame part 31 Engaging groove part 32 Engaging groove part 33 Base part 34 Cutting part 34a Opposing end part 35 Connecting frame (cover part)
36 fitting part 36a locking groove part 37 fixing part 37A division part 38 rib 38a contact part 39 rib 40 bolt insertion hole 41 female screw hole 42 bolt 43 bolt insertion hole 44 female screw hole 45 bolt 46 projecting part 47 concave part 48 groove part 49 Protruding portion 50 Fixing screw 51 Convex shaft 52 Sliding contact surface body 53 Shaft hole 54 Taper hole portion 55 Fitting hole 56 Receiving hole 57 Receiving member 58 Retaining pin 59 Locking hole 60 Bolt shaft 60a Protruding shaft portion 61 Through hole 62 Nut 63 Buffer member 64 Cap member 65 Fixing rod 66 Fixing hole a Clearance

Claims (3)

A backrest frame made of a band plate-like frame member having a space portion in the center and a tension member that closes the space portion is stretched, and the upper end portion of the backrest support frame standing up from the rear of the seat A chair backrest device adapted to support a backrest frame,
A pair of left and right projecting portions projecting inward so as to be able to oppose each other in the left and right direction at a substantially intermediate position in the vertical direction on the inner edge in the left and right direction of the backrest frame;
With the rear surface of the overhang portion integrally formed with the backrest frame and the front surface of the upper end portion of the backrest support frame facing each other, the upper end portion of the backrest support frame is placed in the left-right direction with respect to the overhang portion. A backrest device for a chair, characterized in that the backrest device is pivotally supported so as to be capable of rotating by a predetermined angle around the axis of the pivot axis facing , and so as to be capable of rotating by a predetermined angle in a direction deviating from the axis of the pivot axis .   The chair backrest device according to claim 1, wherein the overhang portion is bulged rearward. The chair backrest device according to claim 1 or 2, wherein a cushioning member made of a soft elastic body is sandwiched between the rear surface of the overhang portion and the front surface of the upper end portion of the backrest support frame.

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