The present invention relates to the stretching structure of a tension member for a chair.
Recently in office chairs used in working spaces or meeting rooms of an office, the back of a user is supported by the backrest over which elastic covering material or a tension member is stretched. In the backrest of the chair, a front surface of a back frame molded in a closed loop of metal such as Al which can easily be molded or synthetic resin is covered with the tension member. The circumference of the tension member is attached to the back surface or side of the back frame and the tension member is stretched over the back frame in Patent Literature 1.
Meanwhile, there is a great demand for a cantilever-type chair in which the backrest is connected to a leg frame made of pipes. The chair provides the armrest at part in which the backrest is connected to the leg frame in Patent Literatures 2-4.
In the chair with the armrest, the middle of the back frame is connected to the rear ends of the armrests. The seat is supported by a seat support in the middle of front legs of the leg frame.
However, in the conventional cantilever-type chair with the armrest, a projection on the front surface of the back frame of the backrest is connected to the leg frame. A hole through which the projection passes is formed in the tension member, and the circumference of the tension member engages with the rear surface of the back frame or side groove. The hole is exposed, so that its appearance becomes poor.
The projection projects outward and sideward of the back frame and a groove of the back frame is formed on the front surface. However, a die-drawing direction for opening the groove is crossed with a die-drawing direction for forming the projection, thereby disabling it to be molded once by the same die. The molding increased by one step, so that the operation is complicated to increase the costs. Such problem occurs not only in the backrest connected to the leg frame but also in the backrest connected to the seat.
In order to solve the problem, the applicant provides in JP2011-161049A (Appln. No. 2010-27957) the stretching structure of a tension member for a chair in which the tension member is stretched over a closed-loop frame and an ear for connection to another member of the chair is provided on the circumference of the frame close to the back surface, wherein a recess is formed on the front surface of the projection and an engagement member fits in the recess, a groove being formed on the outer circumferential surface of the frame close to the ear and on the outer circumferential surface of the engagement member, a circumference of the tension member fitting in the groove.
However, in the stretching structure of the tension member for a chair, the engagement member fits in the recess of the frame with a screw. The screw arrangement is complicated, and when the chair is taken to pieces for disposal of wastes, it is necessary to remove the screw, which is complicated.
In view of the disadvantages in the prior art, it is an object of the invention to provide the stretching structure of a tension member for a chair in which an engagement member can easily be attached to and removed from a frame without a screw, a tension member being easily stretched and separated for disposal of wastes, wherein the engagement member cannot be taken off the frame in use of the chair.
It is another object of the invention to provide a chair in which a frame over which a tension member is stretched is connected to another member of the chair, wherein the frame can easily be drawn when the frame is molded to facilitate molding of the frame, the tension member can be prevented from loosening, its appearance is good and the costs can be saved.
Hence, the recess is formed at part closer to the front surface than the ear, and it is not necessary to form a groove on the outer circumferential surface of the part. Thus, a die-drawing direction for forming a groove on the outer circumferential surface of the frame is not crossed with a die-drawing direction for forming the ear thereby facilitating die-drawing in molding of the frame and easily molding the frame at a single step by a simple die to save the costs. The circumference of the tension member engages in the grooves on the outer circumferential surfaces of the engagement member and frame, so that the tension member can be stretched over the front surface of the frame securely without loosening with good appearance. It is not necessary to form a through-hole for putting through the ear of the frame, so that strength of the tension member can be kept with good appearance.
According to the present invention, the engagement member can easily be attached to and removed from the frame without a screw thereby facilitating stretching of the tension member and separation for disposal of wastes. In use of the chair, the engagement member is not taken off the frame in the stretching structure of the tension member for a chair. According to the present invention, there is provided the stretching structure for a tension member for a chair in which, in a chair in which the frame over which the tension member is stretched is connected to another member, die-drawing is easily performed in molding of the frame and the frame can easily be molded without loosening of the tension member with good appearance to save the costs.
Embodiments of the present invention will described with respect to appended drawings.
The chair 1 comprises a backrest 10, a seat 11 and a leg frame 12 supporting the backrest 10 and seat 11. In
The tension member 14 is elastically formed in mesh. A circumference 14a of the tension member 14 is formed like a bag in which elongate elastic-synthetic-resin edge member 14b is disposed in
A pair of ears 15,15 for connecting the frame 13 to the leg frame 12 is provided on an outer side surface 13b close to a back surface 13c of the frame 13.
In
A boss 15c which faces the front is provided on the end of the each of the ears 15. A plurality of splines 15d is provided on the outer circumferential surface of the boss 15c. In the boss 15c, there is formed a blind hole 15e which faces the front of the frame 13. At the bottom of the blind hole 15e, in
In
In
The projection 13e of the inner side surface 13d of the frame 13 is continuous with the inner side surface 13d and the front surface 13a of the frame 13. The protrusion 13f of the outer side surface 13b is disposed inward of the recess 16 than the outer side surface 13b and the front surface 13a of the frame 13.
A plurality of horizontal reinforcement ribs 13g is vertically spaced between the projection 13e and the protrusion 13f at the rear of the recess 16. An engagement groove 13h extends longitudinally of the frame 13 between the projections 13e and 13f from the front ends of the projections 13e, 13f to the front edge of the reinforcement rib 13g. An opening 13i is formed forward of the ear 15 outside the protrusion 13f of the recess 16 of the frame 13.
The upper and lower edges of the recess 16 comprise tilted surfaces 16a,16a so that a vertical distance between the tilted surfaces 16a and 16a gradually becomes shorter outward, and horizontal surfaces 16b,16b extending outward from the tilted surfaces 16a,16a.
In
Part between the horizontal surfaces 16b and 16b of the recess 16 is open to the front and back surfaces and outer side, and the dovetail groove is open only to the front surface. The rectangular portion of the engagement member 17 which fits between the horizontal surfaces 16b and 16b is exposed to the front and back sides and outer side. The dovetail portion which fits in the dovetail groove of the recess 16 is exposed only to the front surface of the frame 13.
In
In
In the middle of the inner protrusion 18b, there is provided a projection 18c which fits in the opening 13i of the recess 16 of the frame 13.
A plurality of engagement projections 20,21 is spaced vertically to fit in the engagement groove 13h of the recess 16 of the frame 13 on the back surface of the engagement member 17 near the inner side surface 17d.
In
Between the engagement projections 20,21 and the inner protrusion 18b, a vertical groove 17g is formed to fit with the protrusion 13f in the recess 16 of the frame 13.
In
On the back surface of the rectangular portion of the engagement member 17, the groove 25 is formed between the protrusions 18a and 18b and communicates with the groove 24 of the frame 13. In this embodiment, the grooves 24,25 are open backward around the frame 13 and engagement member 17, but may be open toward the outer side.
The engagement projections 20,21 of the engagement member 17 fits in the engagement groove 13h of the recess 16 of the frame 13. The protrusion 13f of the recess 16 of the frame 13 fits in the groove 17g. Hence, the front surface 17c and outer side surface 17f are coplanar with the front surface 13a and the outer side surface 13b and the groove 25 is continuous with the groove 24 of the frame 13.
After the engagement member 17 is fitted in the recess 16 of the frame 13, the circumference 14a of the tension member 14 is fitted with the edge member 14b into the groove 24 of the frame 13 and the groove 25 of the engagement member 17 by force and attached in
When the tension member 14 is stretched over the surface of the frame 13 and the engagement member 17, the outer front part of the engagement member 17 intends to turn inward of the frame 13 around the inner rear part. Moment of the engagement member 17 increases frictional force between the engagement projections 20,21 and engagement groove 13h to cause stick phenomenon thereby preventing the engagement member 17 from leaving the frame 13.
When the protrusion 13f of the frame 13 as second engagement projection fits in the groove 17g of the engagement member 17 as second engagement groove, frictional force increases at the engagement to prevent the engagement member 17 from leaving the frame 13 even if moment of the engagement member 17 acts to the engagement portion.
Furthermore, the circumference 14a and edge member 14b of the tension member 14 are continuously fitted and attached in the grooves 24,25 in the outer circumferences of the frame 13 and engagement member 17, so that the circumference 14a of the tension member 14 is unlikely to leave the grooves 24,25, and a force for preventing the engagement member 17 from leaving the frame 13 is assisted.
Thus, without attaching means such as a screw, the engagement member 17 merely fits in the recess 16 of the frame 13 thereby ensuring easy engagement and facilitating stretching of the tension member 14.
In order to separate the frame 13 from the tension member 14 to get rid of chairs, for example, the tension member 14 is pulled off without loosening attaching means such as a screw thereby easily separating the engagement member 17 from the frame 13 and facilitating separation for disposal of wastes.
In
The recess 26 is formed in front of the lower connecting portion 27 closer to the front surface 13a. The right and left side ends of the recess 26 are parallel vertically. The bottom of the recess 26 has a screw-through hole 28.
In
When the groove 30 communicates with the groove 24 of the frame 13 and the engagement member 29 fits in the recess 26 of the frame 13, the engagement member 29 is fixed to the frame 13 with a screw 31 which is put into the screw-through hole 28 from the back of the frame 13.
After the engagement member 29 is fixed to the frame 134, the circumference of the tension member 14 is fitted with and attached to the edge member 14b in such a manner that the engagement member 17 is fitted in the groove 25.
In the engagement member 29 and the recess 26 of the frame 13, what are similar to the engagement projections 20,21 of the engagement member 17 and engagement groove 13h of the recess 16 are provided thereby preventing the engagement member 29 from leaving the recess 26 by moment of the engagement member 29 resulting from tension of the tension member 14. Thus, the screw 31 may be omitted.
In
In
The front legs 39,39 are connected to each other in the middle via a cross beam 41. A U-shaped support 42 for supporting the seat 11 projects backward. Synthetic-resin arm pads 43,43 are provided over the armrests 40,40. The leg frame 12 may preferably be a double-pipe structure partially or totally to improve the strength.
In
In
Then, the surface 13a of the frame 13 is covered with the tension member 14 the circumference 14a of which is pulled toward the back surface 13c along the outer side surface 13b of the frame 13. The circumference 14a and the edge member 14b are engaged and fixed in the outer circumferential groove 24 of the frame 13, the groove 25 of the engagement member 17 and the groove 30 of the engagement member 29 while facing the front. Each of the engagement members 17 may preferably be engaged in the recess 16 of the frame 13 while the circumference 14a of the tension member 14 and edge member 14b fits in the groove 25 of the engagement member 17.
When the tension member 14 is stretched over the surface 13a of the frame 13, each of the engagement members 17 will become unlikely to leave the frame 13 by moment of the tension member 14. Thus, the engagement member 17 can securely be attached in the recess 16 of the frame 13 without attaching means such as a screw, thereby facilitating stretching of the tension member 14.
When the frame 13 is separated from the tension member 14 to get rid of the chair, the engagement member 27 can easily be separated from the frame 13 without loosening attaching means such as a screw thereby facilitating separation of the tension member 14.
Furthermore, it is not necessary to provide the groove 24 in front of the ear 15 and lower connector 27 of the frame 13. Thus, when the frame 13 is molded, a die-drawing direction for forming a groove in the outer side surface 13b of the frame 13 is not crossed with a die-drawing direction for forming the frame 13 thereby facilitating molding of the frame 13. The frame 13 is easily molded by a single step by a simple die thereby saving the costs.
The tension member 14 covers the outer side surface 17f and front surface 17c of the engagement member 17 and outer side surface and front surface of the engagement member 29 thereby improving the appearance of the backrest.
It is not necessary to form a through hole in the ear 15 of the frame 13 thereby maintaining the strength of the tension member 14 and improving its appearance.
The engagement projections 20 of the engagement member 17 are provided in the plural number longitudinally of the engagement member 17 and are connected by the connecting portion 22 thereby increasing strength of the engagement projections 20 and engagement member 17 to enable the engagement member 17 to get smaller.
In the recess 16 of the frame 13 and the ends of the engagement member 17, the length of the frame 13 gradually becomes smaller outward by the tilted surfaces 16a,17a thereby preventing the engagement member 17 from dropping out of the frame 13.
The engagement member 17 can be molded in a line separate from the die molding line of the frame 13 or by injection molding to save the costs. When the chair is thrown away or when the tension member 14 is replaced, the engagement member 17 can easily be taken off the recess 16 of the frame 13 thereby facilitating the replacement and separate disposal of wastes.
In
In
In
In
On the front surface of the engagement member 49, a plurality of lightening openings 51 is formed to make the engagement projections 50 hollow respectively.
On the outer circumference of the engagement member 49, there is formed a groove 52 similar to the groove 25 of the engagement member 17 in the first embodiment. The groove 52 is continuous with the groove 24 of the frame 13 when the engagement member 49 fits in the recess 48.
In the second embodiment, the rectangular engagement projections 50 fit in the rectangular grooves 48g of the engagement recess 48e respectively, and the engagement member 49 fits in the recess 48 of the frame 13. The circumference 14a of the tension member 14 is pressingly fitted in the groove 24 of the frame 13 and the groove 52 of the engagement member 49 continuously. By moment of the engagement member 49 resulting from tension of the tension member 14, the engagement member 49 does not leave the frame 13. Similar function and advantages to the first embodiment can be achieved.
The rectangular engagement projection 50 of the engagement member 49 engages in the rectangular groove 48g of the engagement recess 48e of the recess 48 thereby not only facilitating molding of the frame 13 and engagement member 49 but also ensuring that the engagement member 49 is exactly positioned with respect to the frame 13 to prevent the engagement member from deviation.
Furthermore, at one end of the recess 48 of the frame 13, the arc-shaped enlarged portion 48b is provided and the projection 49a complementary to the enlarged portion 48b is provided at the corresponding part of the engagement member 49. Hence, when the engagement member 49 fits into the recess 48 of the frame 13, damage by contacting the corner of the engagement member 49 with the inner surface of the recess 48 can be prevented. When the user leans against the backrest 10, stress is prevented from gathering parts close to the recess 48 on the outer side surface 13b of the frame 13.
In the first and second embodiments, the present invention is applied to the backrest of a chair, but may be applied to the seat or headrest of a chair by modifying the direction and/or shape.
Various embodiments may be made without departing from the scope of claims:
(1) The groove 24 of the frame 13 and grooves 25,30,52 of the engagement member may be open to the outer side.
(2) The engagement projection 20 of the engagement member 17 may be provided on the recess 16, and the engagement groove 13h of the recess 16 may be provided on the engagement member 17.
(3) The tilted surfaces 16a,17a at the upper and lower ends of the recess 16 and the engagement member 17 may be made such that a vertical distance between the tilted surfaces 16a and 17a gradually becomes greater.
(4) At the upper and lower ends of the recess 16 and engagement member 17, an engagement projection and an engagement groove may be made instead of the tilted surfaces 16a,17a.
(5) In the lower recess 26 of the frame 16 and engagement member 29, an engagement projection and an engagement groove may be made as well as in the grooves 16 of the frame 13 and the engagement member 17 thereby omitting screw-attachment of the engagement member 29.
(6) At the right and left ends of the recess 26 and engagement member 29, there may be provided a tilted surface similar to that at each end of the recess 16 and engagement member 17.
(7) The present invention may be applied to case in which a projection is not provided in the recess 16.
Number | Date | Country | Kind |
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2011-020317 | Feb 2011 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2012/051571 | 1/25/2012 | WO | 00 | 8/2/2013 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2012/105390 | 8/9/2012 | WO | A |
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6942300 | Numa et al. | Sep 2005 | B2 |
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8777321 | Masunaga et al. | Jul 2014 | B2 |
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07-37552 | Aug 1995 | JP |
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2004113503 | Apr 2004 | JP |
2005118439 | May 2005 | JP |
2006-271622 | Oct 2006 | JP |
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Number | Date | Country | |
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20130307311 A1 | Nov 2013 | US |