JP2005261852A - Chair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avert a danger caused by application of load above the limit on a broken member in a synchronizing chair having a seat moved co-operated with a backrest. <P>SOLUTION: The front part of an intermediate member 8 is connected by a first shaft 9 to the front part of a base 6, the front part of a back frame 10 is connected by a second shaft 11 to the base 6, and the back frame 10 and the intermediate member 8 are connected by a third shaft 14. The first shaft 9 and the intermediate member 8 are integrated by welding, and the first shaft 9 is provided with a stopper 46 formed with a forward projection portion 46. Even if a person sit on the front part of the seat 2 without knowing its breakage, after the intermediate member 8 is separated from the third shaft 14 due to the breakage caused by fatigue, the stopper 46 prevents the seat 2 from being widely tilted and turned forward, so that the person can avert the danger of falling. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a chair.

  For example, an office swivel chair has a basic structure in which a base is fixed to the upper end of a leg post, a seat is supported by the base, and a back frame connected to the base so as to be tilted backward is attached. The tilting is supported by a spring. In addition, a synchro type is often used in which when the backrest tilts backward, the seat moves backward and / or backwards in conjunction with the backrest.

  There are several types of synchro mechanisms that link the seat and the backrest. For example, as an example of the type in which the seat is retracted while being retracted in conjunction with the back tilt of the backrest, the intermediate member that receives the seat is connected to the front portion of the base by the first shaft, and the intermediate member and the back frame Are connected to the third shaft, and the hole into which the first shaft fits in the base is a long hole in the front-rear direction.

  As for the type in which the seat only tilts backward in conjunction with the back tilt of the backrest, the first shaft is connected so as to rotate only with respect to the base. There are some which make the back frame tilt and the back tilt of the seat interlock with each other by using a long hole.

  There is also a link mechanism that uses a seat linked to the backrest. In any case, the seat is connected to the front part of the base directly or via an intermediate member with a shaft (including pins), and the rear part of the seat is connected to the back frame and base via the shafts and links. It is connected to.

  Chairs must be safe because they are used by people, and each manufacturer ships with safety standards. The safety standard in this case is that the product will not break even if it is used for a specified service life under normal conditions of use, and an excessive load exceeding the warranty limit is applied, or a long-term service life exceeding the service life is exceeded. Even if a member breaks down if it is used continuously, it is difficult to say that it is the responsibility of the manufacturer.

  However, even if a member is damaged due to abnormal use exceeding the guarantee limit, it is necessary to prevent endangering the user's body.

  On the other hand, as described above, in the recent swivel chair, the synchro type in which the seat is interlocked with the backrest has become mainstream, but this is nothing but the function of the chair is enhanced so that the seating comfort is good. And if there are many movable parts in the chair, the structure will suddenly become complicated, and the method of applying a load to each member will also become complicated.

  As a result of experiments conducted by the inventors of the present application, it has been found that in a synchro-type chair, the load concentrates on the connecting portion of the third shaft, and the member through which the third shaft passes is easily broken by fatigue. When the member breaks at the third axis, the seat is only connected to the base at the first axis.

  In that case, in the normal posture where the user sat deeply, the seat can be received by the base even if the member is broken, so it can be said that there is almost no danger to the seated person. However, since the seat usually projects to the front side of the first shaft, when a person puts his / her waist on the front end of the seat without knowing that the member is broken, , There is a risk that the seat will be tilted forward and the person may fall on the floor or repeat.

  The present invention is intended to prevent or remarkably suppress such danger.

  To achieve the above object, the invention of claim 1 includes a base supported by legs, and a seat which is disposed above the base and can be tilted backward or backward or both against the spring means. And a backrest disposed behind the seat, and the seat is disposed so as to project to the near side of the base, and the seat is located near the front of the base on the first axis. And a rear portion of the seat portion connected to the base or another member, the rear portion of the seat portion being released due to breakage of the member. In this state, there is provided stopper means for holding the seat portion so that it does not pivot excessively forwardly about the axis of the first shaft even when a downward load is applied to the front end portion of the seat portion.

  According to a second aspect of the present invention, in the first aspect, the seat includes a seat and an intermediate member to which the seat is fixedly attached or adjustable in the front-rear position. The intermediate member is attached to the base on the first shaft. On the other hand, the backrest is attached to a back frame that is connected to the base by a second shaft so as to be tiltable backward, and the middle part of the back frame is connected to the intermediate member by a third shaft. Furthermore, the backrest and the seat portion are allowed to be interlocked by using a hole in which one of the first shaft and the second shaft is fitted in the base as a long hole.

  According to a third aspect of the present invention, in the second aspect, the intermediate member, the first shaft, and the third shaft are integrated by welding, screwing, or the like, and the intermediate member is an axis of the first shaft on the first shaft. Stopper means that comes into contact with the base when it is pivoted forward is provided so as to protrude outward from the radius of the first shaft.

  According to a fourth aspect of the present invention, in the second aspect, the stopper means is set such that the front end of the intermediate member directly contacts the base from above when the intermediate member is tilted forward around the axis of the first shaft. In addition, a stopper body that comes into contact with the base from above when the intermediate member pivots forward is attached to the front end portion of the intermediate member, and a stopper body that comes into contact with the lower surface of the seat portion is attached to the front end portion of the base. And a cover arranged so as to cover the base, and at least one selected from supporting the portion of the seat portion closer to the first shaft than the first shaft.

  In the invention of claim 5, regarding the breaking strength of each member against the load caused by repeated use by a person, the breaking strength of the base is set larger than the breaking strength of the member at the attachment position of the third shaft.

  According to the present invention, in the chair in which the seat moves backward or backward against the spring means or both, after the rear portion of the seat has been released due to breakage of the member due to usage exceeding the guaranteed limit, Even if a person puts his / her waist on the front edge of the seat without knowing the fact that the member is broken, it can prevent the person from falling on the floor or tipping over and improving safety. it can.

  In the invention of claim 1, the backrest can be fixed to the seat or attached to the seat in a state in which the backrest can be tilted backward. However, in the present invention, the backrest and the seat are It is particularly suitable for a synchronized synchro-type chair.

  In the synchro-type swivel chair, the seat is generally attached to the base via an intermediate member. In this case, when the intermediate member and the front and rear shafts are integrated, there is an advantage that the assembly process can be simplified. According to the third aspect of the present invention, it is possible to prevent the seat from tilting forward when the member is broken by a simple structure in which the stopper means is provided on the front shaft.

  In addition, since the intermediate member and the cover can also be used as the stopper means, the structure can be simplified, and the portion as far as possible from the first shaft can be brought into contact with the base or the like. Therefore, it is possible to suppress the moment when the seat portion is tilted forward and more effectively suppress the seat portion from being tilted forward to the dangerous range.

  It should be noted that in preventing the seat portion from tilting forward, it can be said that it is preferable to tilt the seat forward by a certain angle in order to inform the user of the fact that the member is broken. On the other hand, it can be said that it is preferable to prevent the rotation within a range of at least about 30 ° to 45 ° with respect to the horizontal in order to prevent a person from slipping down or turning over.

  Next, embodiments of the present invention will be described with reference to the drawings.

(1). Basic structure of chair First, the basic structure of a chair will be described with reference to FIGS. FIG. 1 is a side view of a chair. As shown in FIG. 1, the chair includes a leg 1 with casters, a seat portion 2, a backrest 3, and an armrest 4. The leg 1 includes a leg column (gas cylinder) 5 that can be extended and rotated, and a base 6 is fixed to the upper end of the leg column 5.

  The seat portion 2 includes an outer shell 7 and an intermediate member (seat support bracket) 8, and the front end portion of the intermediate member 8 is tilted and retracted backward by a first shaft 9 (front shaft) at the front end portion of the base 6. It is attached movably.

  Further, the front end portion of the back frame 10 is connected to the rear portion of the base 6 so as to be tilted backward by the second shaft 11, and a back column 12 is provided at the rear of the back frame 10, and the back column 12 is backrested. 3 is attached. A lumbar support 13 is disposed between the back column 12 and the backrest 3 so as to be adjustable in height.

  Further, a portion of the back frame 10 that is behind the second shaft 11 and the rear portion of the intermediate member 8 are connected by a third shaft (rear shaft) 14 so as to be relatively rotatable. For this reason, when the backrest 3 tilts backward, the seat portion 2 also moves backward while tilting together. The details of each part will be described below with reference to FIG.

  2 is an exploded perspective view of the main members constituting the support mechanism, FIG. 3 is an exploded perspective view of the back frame 10 and related members, FIG. 4 is a longitudinal side view of the seat portion, and FIG. 5 is a VV view of FIG. 6 is a sectional side view taken along the line VII-VII of FIG. 6, FIG. 8 is a sectional view taken along the line VIIIA-VIIIA of FIG. 2, and FIG. 9 is a perspective view of the base 6. 10 is a plan view of the base 6, FIG. 11 is a longitudinal side view of the base 6, FIG. 12 is a view showing a support structure of the first shaft 9, (A) is a separated plan view, and (B) is a perspective view of a front bearing. (C) is a rear view of the front spring receiver, (D) is a side view of the front spring receiver, (E) is a sectional view taken along line EE of (A), and FIG.

(2). Base / intermediate member / back frame / seat As is clear from FIG. 2 and FIGS. 9 to 11, for example, the base 6 is formed in a box-like shape having an upward opening with left and right side plates 6a. The inner bracket 15 is fixed to the upper end of the leg support 5 via the inner bracket 15. A slit 16 for supporting the first shaft 9 is formed in the front portion of the left and right side plates 6a in the base 6 so as to open forward.

  A pair of intermediate members 8 are arranged on the left and right, a first shaft 9 made of a round pipe is fixed to the front by welding, and a third shaft 14 made of a round pipe is fixed to the rear by welding. ing.

  The seat outer shell 7 is placed on the intermediate member 8. The intermediate member 8 is formed with a flange 8a extending outward in the left and right directions. As shown in FIG. 7, the seat outer shell 7 has a holding portion 7a for holding the flange 8a of the intermediate member 8 from the outside. The seat 2 is attached to the intermediate member 8 so as to be movable back and forth.

  The front and rear positions of the outer shell 7 (and the seat 2 ') can be adjusted stepwise by a locking means (not shown). As a part of this locking means, as shown in FIGS. 2 and 5, the flange 8a of one intermediate member 8 is formed with a plurality of notches 8b for engaging and disengaging the lever.

  As shown in FIGS. 4 and 6, the seat portion 2 includes a seat 2 ′, and the seat 2 ′ includes a synthetic resin inner shell (seat plate) 18, a cushion 19 stretched on the upper surface thereof, and a cushion. And a skin material 20 that wraps the material 19 from above. The seat inner shell 18 is attached to the outer shell 7 by a locking method comprising a claw and an engagement hole.

  For example, as shown in FIG. 3, the back frame 10 is formed in an outward U-shaped cross section and is disposed on the left and right, while the back struts 12 are disposed on the left and right with a slight gap therebetween. The lower portions of the back struts 12 are bent sideways and fitted into the back frame 10 and fixed by welding. The lower portions of the left and right back struts 12 are integrally connected by a lower connection fitting 12a welded thereto.

  It should be noted that the back frame 10 and the back column 12 can be integrated. Moreover, it is not necessary to arrange the back frame 10 and the back column 12 one by one on the left and right, and there may be one. Further, it is possible to directly attach the backrest 3 to the back frame 10 without providing the back column 12.

  The inner bracket 15 includes a front wall 15a that is substantially perpendicular to the bottom surface of the base 6, and a movable rear spring receiving device 21 is disposed on the front side of the front wall 15a to support the spring 22 from the rear. ing.

(3) Support structure of each shaft The left and right front bushes 23 and the front spring receivers 24 sandwiched between the first shaft 9 and the inner portion of the base 6 are fitted. .

  The left and right front bushes 23 are made of synthetic resin, and are formed in a U-shape (bifurcated) in a side view opened rearward as shown in FIG. 12A, and the first shaft 9 is formed in a space of the forward opening. Fits slidable back and forth. Further, the front bush 23 is formed with a groove 23 a that is fitted to the inner peripheral edge of the slit 16 of the base 6. For this reason, the left and right front bushes 23 are held so that they cannot be displaced left and right.

  The front spring receiver 24 is formed in a U shape in a side view of the rearward opening, and a protrusion 24a that holds the spring 22 so as not to be displaced is formed on the front surface thereof. Further, the first shaft 9 is fitted in the rearward opening 24a. The front spring receiver 24 is held between the left and right front bushes 23 so as not to move left and right. In addition, the left and right front bushes 23 and the front spring receiver 24 are fitted in the interior of a front metal fitting 25 made of a metal plate with a U-shape facing forward when viewed from the side.

  The front metal fitting 25 is fixed to the base 6 by welding or the like, and the left and right front bushes 23 are fastened to the front metal fitting 25 by screws 25a.

  An arc-shaped stopper body 46 that holds the first shaft 9 from above is fixed to the portion of the first shaft 9 that fits into the front spring receiver 24 by welding. On the inner surface of the opening groove in 24, a fitting groove 24c is formed in which the stopper 46 is fitted so that it cannot be displaced laterally. For this reason, even if it is in the state which left the space | interval between the side surface of the intermediate member 8, and the base 6, the 1st axis | shaft 9 and the intermediate member 8 are hold | maintained so that a left-right movement is impossible.

  Further, a forward projecting portion 46a extending substantially horizontally is formed at the lower end of the front end portion of the stopper 46 as an example of the stopper means recited in the claims. As shown in FIG. 13, when the seat 2 is tilted forward to some extent about the first shaft 9, the forward projecting portion 46 a of the stopper 46 comes into contact with the bottom plate of the base 6 via the front metal fitting 25, The above forward rotation is prevented.

  The second shaft 11 is fastened to the lower surface of the base 6 with a screw via a center bush 26 and a center fitting 27.

  The third shaft 14 is connected to a bridge member 28 arranged so as to span the left and right back frame 10 by a pair of left and right synthetic resin rear bushes 29 and rear metal fittings 30. The bridge member 28 is fixed to the back frame 10 by welding (it may be screwed).

(4). Other structures When the backrest 3 tilts backward, the seat 2 also interlocks and moves backward while retracting. However, in order to regulate the rearward tilt angle of the backrest 3 and the seat 2, as shown in FIG. A receiving member 31 with which the third shaft 14 abuts at the lower limit is provided on the upper surface of the bracket 15.

  In FIG. 3, reference numeral 32 denotes a back inner shell constituting the backrest 3, reference numeral 33 denotes a back cover, and reference numeral 34 denotes a center cover. The center cover 34 is configured to cover the back frame 10 and the space between the back frame 10 and the rear portion of the bridge member 28.

  As shown partially in FIGS. 3 and 4, a gas spring 36 for switching the backrest 3 between a free state in which the backrest 3 can be tilted and a locked state in which the backrest 3 cannot be tilted is disposed so as to extend in the front-rear direction. Yes. The front end of the gas spring 36 is attached to a U-shaped bearing bracket 37 fixed to the rear surface of the base 6 so as to be vertically rotatable by a horizontal pin 38.

  The gas spring 36 includes a piston 39. A movable bracket 40 is fixed to the rear end of the piston 39, and a fixed pin 41 fixed to the lower portion of the back column 12 with a horizontal pin 42. It is attached. A push valve (not shown) protrudes from the tip of the piston 39, and the lock of the gas spring 35 is released by pressing the push valve with a lever (not shown).

  The center cover 34 is provided with a front wall 34a, and a notch 43 for avoiding interference with the gas spring 35 and a projection 44 for avoiding interference with the lever are provided on the front wall 34. Forming. The elbow strut of the armrest 4 is fixed to the left and right end portions 28 a of the bridge member 28 and the back frame 10.

(5) Summary As a result of experiments conducted by the inventors of the present application, when a large load was repeatedly applied to the seat portion 2, cracks and fractures were found in members such as the base 6. Naturally, cracks and fractures are generated by a load, but in this case, an influence due to the downward action of the seated person's load and an impact when the seat portion is restored by the spring 22 are considered.

  And as a fracture | rupture of a member, the phenomenon by which the rear part fitting part (refer code | symbol 8c of FIG. 8) which the 3rd axis | shaft 14 attaches among the intermediate members 8 is divided up and down was seen. Although the details of the reason have not been sufficiently analyzed yet, an upward force is applied to the rear portion of the intermediate member 8 when the downward load on the seat portion 2 is released and the seat portion 2 returns to its original posture by the spring 22. Can be assumed to be the main cause.

  And as shown in FIG. 8, although the rear part fitting part 8c of the 3rd axis | shaft 14 in the intermediate member 8 is in the state protruded in inclination (for weight reduction etc.), in this case, a welding part (building up) Part) 47 is only about the lower half of the third shaft 14, a phenomenon in which the rear fitting portion 8 c is broken at both ends of the welded portion 47 was observed. This is presumably because the edge of the weld is hardened and the brittleness is reduced.

  On the other hand, as shown in FIG. 8 (A), it is set so as to extend to the upper end portion of the third shaft 14 of the welded portion 47, so that the start end of the welded portion 47 is more than the base portion of the rear fitting portion 8c. The fracture phenomenon could be greatly reduced by positioning it above a certain dimension h. Therefore, it can be said that welding as shown in FIG.

  Of course, the entire circumference of the third shaft 14 may be welded. Furthermore, it can be said that it is worth considering that only the upper end of the third shaft 14 is welded to the intermediate member 8 in order to prevent the rear fitting portion 8c from being brittle. It is also possible to weld a washer-shaped reinforcing member to the rear fitting portion 8c.

  When the base 6 is made of sheet metal, it is preferable to reduce the thickness as much as possible from the viewpoint of workability and cost, but the strength decreases as the thickness decreases. In particular, it can be said that stress concentration tends to occur because the base 6 is subjected to many drilling processes such as lever insertion holes.

  Therefore, when the inner bracket 15 and the front metal fitting 25 are fixed to the base 6 by welding as in the present embodiment, the welded portion 47 has a certain length as shown in FIG. When extended, the base 6, the inner bracket 15, and the front metal fitting 25 reinforce each other, and high durability could be secured.

  In any chair, if an excessive load exceeding the guaranteed limit is applied, some member may be broken or damaged. In the present embodiment, the strength of the base 6 is set to the rear fitting portion 8c of the intermediate member 8. It is set larger than the intensity. In other words, the strength of the rear fitting portion 8 c is set lower than the strength of the base 6.

  This is because, if the base 6 breaks first, the seated person may turn over or receive a large impact, and the danger is great, whereas if the rear fitting portion 8c of the intermediate member 8 breaks. This is because the seat 2 is received by the base 6 and there is little danger.

  Even if a moment is applied to the front portion of the seat 2 'and a person tilts forward to the seat portion 2 without knowing that the rear fitting portion 8c of the intermediate member 8 is broken, the stopper 46 Since the forward projecting portion 46a hits the base 6 and the seat portion 2 is prevented from pivoting forward largely, it is possible to prevent a dangerous situation in which a person turns over. In the case of the present embodiment, the forward projecting portion 46 a of the stopper 46 may be brought into contact with the front spring receiver 24.

(6). Second to fourth embodiments (FIGS. 14 to 16)
14 and 15 show a second embodiment. 14 is a side view of an essential part, and FIG. 15 is a sectional view taken along line XV-XV in FIG. In this embodiment, the first shaft 9 is movably connected to the base 6, while the through hole 48 is a long hole that is inclined backward in side view when the second shaft 11 passes through the base 6. Accordingly, the seat 2 is tilted backward in conjunction with the backrest.

  The intermediate member 8 is formed in a U-shape that is open downward when viewed from the front, and the intermediate member 8 is excessively tilted forward by projecting the front end of the base 6 toward the front side of the intermediate member 8. Is to be blocked. Therefore, in this embodiment, the front part of the intermediate member 8 and the front part of the base 6 also serve as stopper means. The seat 2 'may be set so as to contact the base 6.

  FIG. 16A shows a third embodiment which is a modified example of the second embodiment. In this embodiment, a stopper portion 48 which is obliquely forward in a side view is formed on the intermediate member 8 by bending. In this embodiment, it can be said that the angle from when the seat portion 2 is tilted forward until it stops is very small, and thus it can be said that the safety is more excellent. As indicated by the alternate long and short dash line, the stopper portion 48 may be formed on the base 6.

  FIG. 16B shows a fourth embodiment. In this embodiment, a downward stopper body 50 is fixed to the front end portion of the intermediate member 8 by appropriate means such as screwing. In this case, the same effect as that of the third embodiment can be obtained. The stopper body 50 may be provided on the base 6 (in this case, the stopper body 50 may be brought into contact with the intermediate member 8 or may be brought into contact with the lower surface of the seat 2 ').

  When the separate stopper 50 is provided on the intermediate member 8 or the base 6, the stopper 50 is made of a synthetic resin, and is snapped into the intermediate member 8 or the base 6 by using a snap engagement such as a sandwiching type or a plugging type. It is also possible to install.

(7). Fifth to sixth embodiments (FIGS. 17 to 19)
FIG. 17 shows a fifth embodiment. In this embodiment, when the lower cover 51 made of synthetic resin or the like surrounding the base 6 is provided, the front portion of the lower cover 51 is brought close to or in contact with the lower surface of the seat portion 2, thereby Prevents forward tilt rotation. Since the cover 51 is slightly deformed, it can be said that a buffering action is generated.

  Note that the cover 51 needs to have a strength that can prevent the seat portion 2 from rotating forwardly.

  18 to 19 show a sixth embodiment. 18 is a longitudinal side view, and FIG. 19 is a cross-sectional view taken along the line XIX-XIX in FIG. In this embodiment, the cover 51 fixed to the lower surface of the seat portion 2 is also used as a forward tilt prevention stopper (when the seat portion 2 has an outer shell as in the first embodiment, the cover 51 51 is preferably fixed to the outer shell).

  As a specific mode in which the cover 51 that has been wound around the seat portion 2 is also used as a stopper, it is possible to first apply the cover 51 to the lower surface of the base 6. Further, when the lower surface of the cover 51 is open, a method is adopted in which a stopper 56 projects from the side surface of the base 6 and the bottom 51a (inwardly projecting portion) of the cover 51 is brought into contact with the stopper 56 from below. it can. The bottom portion 51a of the cover 51 can be brought into contact with the front end portion of the back frame 10 without providing the stopper 56 separately.

  The stopper 56 may be formed integrally with the base 6 by, for example, cutting and raising, or a separate member may be fixed by screwing or welding. Further, the cover 51 needs to have a strength capable of preventing the seat portion 2 from rotating forwardly.

(8). Seventh embodiment (FIG. 20)
FIG. 20 shows a seventh embodiment. (A) is a side view, (B) is a BB view sectional view of (A).

  In this embodiment, the synchro mechanism is the same as that of the first embodiment, while the intermediate member 8 is formed in a downward opening U-shape in front view as in the second embodiment, and the back frame 10 has a cross section. It is formed in an upward opening U-shape.

  And the stopper 53 fitted to the 3rd axis | shaft 14 is attached to the intermediate member 8 and the back frame 10 by means, such as welding and screwing. Further, the hole in which the third shaft 14 is fitted in the stopper 53 is set so that the third shaft 14 is loosely fitted. The stoppers 52 and 53 may be formed with slits instead of holes.

  In this embodiment, when the intermediate member 8 and the third shaft 14 are separated from each other, the connection relationship between the third shaft 14 and the intermediate member 8 is maintained by the stopper 52 provided on the intermediate member 8, and the back frame 10 and the third shaft 14 is separated, the connection relationship between the third shaft 14 and the back frame 10 is maintained by the stopper 53 provided on the back frame 10, and in any case, the seat part 2 is largely tilted forward. Can be prevented. As the stoppers 52 and 53, a wire or a wire can be used.

(9) Reference examples (Figures 21 to 22)
21 to 22 show reference examples. 21 is a side view, and FIG. 22 is a sectional view taken along line XXII-XXII in FIG. In this reference example, the intermediate member 8 is separated into a lower member 8 ′ and an upper member 8 ″ fixed by welding or screwing, and the lower member 8 ′ is separated from the base 6 in the same manner as in the first embodiment. The seat 2 'is attached to the flange 8a "of the upper member 8" so as to be adjustable in the front-rear position.

  An auxiliary bracket 54 through which the third shaft 14 passes is attached to the lower member 8 '. In this embodiment, the lower member lower member 8 ′ of the intermediate member 8 includes the auxiliary bracket 54, so that the lower member 8 ′ and the third shaft 14 are not separated.

  And, for example, when a hollow hole having a large vertical opening is formed in the lower member 8 'for weight reduction, the strength of the front and rear halfway portion of the lower member 8' is lower than the strength of the connection portion with the third shaft 14, For this reason, it can be predicted that the crack 55 will enter the middle part of the front and rear, but even in that case, the entire intermediate member 8 can be prevented from breaking due to the presence of the upper member 8 ″.

(10). Others The present invention can be embodied in various ways other than the above embodiments. For example, the connecting shafts such as the first shaft and the third shaft do not need to extend long to the left and right in one state, and may be separated to the left and right, for example. Further, a link mechanism may be used to connect the rear part of the seat part.

  Furthermore, specific forms of each member such as the base, the intermediate member, and the back frame can be freely set. Each axis may be solid. There may be a plurality of intermediate members.

It is a side view of the chair concerning a 1st embodiment. It is a separation perspective view of the main member which constitutes a support mechanism. It is a separation perspective view of a back frame and a member related to this. It is a vertical side view of a seat part. FIG. 5 is a plan view taken along the line V-V in FIG. 4. It is a vertical side view of a seat part. FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6. FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 2. It is a perspective view of a base. It is a top view of a base. It is a vertical side view of a base. It is a figure which shows the support structure of a 1st axis | shaft. It is a figure which shows an effect | action. It is a principal part side view of 2nd Embodiment. It is XV-XV view sectional drawing of FIG. It is a figure which shows 3rd Embodiment and 4th Embodiment. It is a figure which shows 5th Embodiment. It is a vertical side view of 6th Embodiment. It is the XIX-XIX sectional view taken on the line of FIG. It is a figure which shows 7th Embodiment. It is a side view of a reference example. FIG. 22 is a sectional view taken along line XXII-XXII in FIG. 21.

Explanation of symbols

1 leg 2 seat 2 'seat 3 backrest 6 base 9 first axis 10 back frame 11 second axis 14 third axis
24 Front spring holder 46 Stopper 46a Forward projection

Claims (5)

A base supported by a leg; a seat disposed above the base and capable of performing backward tilting and / or backward movement against the spring means; and a backrest disposed behind the seat. The seat portion is arranged so as to protrude to the front side of the base, and the seat portion is connected to the front side portion of the base by the first shaft, and the seat portion is connected to the first shaft. Is a chair formed by connecting the rear part to a base or other member,
Even if a downward load is applied to the front end portion of the seat portion in a state where the connection of the rear portion of the seat portion is released due to the breakage of the member, the seat portion does not pivot excessively forward around the axis of the first axis. Stopper means to hold is provided,
Chair. The seat includes a seat and an intermediate member to which the seat is fixedly or adjustable in the front-rear position, and connects the intermediate member to the base with a first shaft,
The backrest is attached to a back frame that is connected to the base by a second shaft so as to be tiltable rearwardly. The midway portion of the back frame and the intermediate member are connected by a third shaft, and the first shaft By allowing a hole in which either one of the second shaft and the second shaft is fitted to the base to be a long hole, the backrest and the seat portion are allowed to work together.
The chair according to claim 1. The intermediate member and the first shaft and the third shaft are integrated by welding, screwing, or the like, and a stopper that comes into contact with the base when the intermediate member is tilted forward around the axis of the first shaft. The means is provided so as to protrude outside the radius of the first axis.
The chair according to claim 2. The stopper means includes
Setting the intermediate member so that the front end of the intermediate member directly contacts the base from above when the intermediate member is tilted forward and rotated about the axis of the first axis;
At the front end of the intermediate member, attaching a stopper body that comes into contact with the base from above when the intermediate member is tilted forward,
Attach a stopper body that the lower surface of the seat abuts to the front end of the base;
The cover arranged to cover the base is at least one selected from supporting the front wing portion of the seat portion with respect to the first axis.
The chair according to claim 2. Regarding the breaking strength of each member with respect to the load due to repeated use by a person, the breaking strength of the base is set larger than the breaking strength of the member at the attachment position of the third shaft,
The chair as described in any one of Claims 1-4.

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