JP2009165660A - Chair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chair having a back tilting function, which does not make a sitter feel an incongruity as if the back and the waist are locally pushed forward by projecting a lumbar supporting portion forward while elastically deforming an entire back shell with the movement of the chair from a normal condition where no load is imposed on the backrest to the back tilting condition where the backrest is tilted rearward. <P>SOLUTION: The chair comprises the backrest 5 having an elastically deformable back shell 51, an inclining frame 4 supporting the region of the back shell 51 above the lumbar supporting portion 51L supporting the sitter's waist, and a supporting frame 2 supporting the lower portion of the back shell 51, and is structured so as to overall bend and deform to ensure that the back shell 51 projects relatively forward the lumbar supporting portion 51L following the actions of pivotally connecting the inclining frame 4 and the supporting frame 2, setting a pivoting point X1 in the lower end side rear of the back shell 51 and rearward inclining of the inclining frame 4 around the pivoting point X1 with respect to the supporting frame 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a chair, particularly a chair used in an office or the like.

  2. Description of the Related Art Conventionally, chairs are known in which a seat structure and a backrest are supported on a frame structure mainly composed of a metal pipe material.

  As such a chair, a chair having a so-called back tilt function in which the backrest can be tilted according to the sitting posture of the seated person has been developed.

Then, when the backrest is tilted backward (when the seated person leans on the backrest), the lumbar support part that can support the waist of the seated person in the back shell is locally projected forward. A mode of elastic deformation is also considered separately (for example, see Patent Document 1 below).
Japanese Patent No. 3834500

  However, the back shell disclosed in the above patent document is provided with a U-shaped slit in the middle in the vertical direction, and the region surrounded by the slit is locally projected forward according to the load received. Since it is an aspect, when the seated person puts weight on the backrest and tilts the backrest backward, the waist is locally pushed forward. Further, since the deformation state is greatly different between the portion surrounded by the slit in the back shell and the portions on both sides of the portion, it may be possible to give the seated person a sense of incongruity such as feeling a step in the waist.

  In addition, when the seated person leans on the backrest, the lumbar support that can elastically deform the lumbar support part that can support the waist of the seated person among the back shells so as to locally protrude forward is provided as a lumbar support. Although a chair with a special mechanism for projecting the part forward is also considered, this kind of thing invites a special operation on the seated person (user) in addition to incurring a complicated structure Therefore, it takes time to get used to it, and there is a problem that it is inferior in practicality.

  The present invention has been made paying attention to such problems, and a main object of the present invention is to provide a chair having a back tilt function in which a backrest is tilted backward from a normal state in which no load is applied to the backrest. Along with the transition to the tilted state, the lumbar support part protrudes forward while flexing and deforming the entire back shell, and does not give the seated person an uncomfortable feeling that the back and waist are pushed forward locally. To provide a chair.

  That is, the chair of the present invention includes a backrest having an elastically deformable back shell, a tilting frame that supports a portion of the back shell that is above the lumbar support portion that supports the waist of the seated person, and the back shell. The tilt frame and the support are pivotally mounted, the pivot point is set on the rear side of the lower end portion of the back shell, and the pivot point is the center. As the tilting frame tilts backward with respect to the support body, the back shell is generally curved and deformed so that the lumbar support portion protrudes relatively forward.

  In such a case, when the seated person puts his / her weight on the backrest, the tilting frame tilts backward around the pivot point set at the rear side on the lower end side of the back shell, and accordingly the back frame While the upper part of the shell supported by the tilting frame warps backward, the lower part of the back shell supported by the support body remains in the position before the backward tilting action, so there is a gap between the upper and lower parts of the back shell. Area, more specifically, the entire back shell is bent and deformed so that the lumbar support part naturally protrudes forward, and the back and waist are pushed forward in a locally unnatural state. Can be eliminated or suppressed to give the seated person a good feeling of drowning. In addition, a special structure is not required for the back shell, the structure of the back shell can be simplified, and the lumbar support portion can be elastically deformed as a whole over the entire lateral width direction of the back shell. The above-mentioned problem, which is a concern when the back shell is provided with a U-shaped slit in front view, that is, the deformed state differs greatly between the part surrounded by the slit and the part on both sides of the part, It can also eliminate the feeling of strangeness. In addition, in a state where the backrest is tilted backward, the lumbar support portion of the back shell is not directly supported from the back by another member, in other words, the lumbar portion of the seated person is supported only by the elasticity of the back shell itself. Because it is an aspect, if the lumbar support part is pressed and supported from behind by another member or mechanism and protrudes forward, the discomfort of the waist that can be given to the seated person is eliminated or suppressed, and it is impossible for the seated person There will be no natural feeling of waist contact. In addition, a dedicated mechanism for projecting the lumbar support part forward becomes unnecessary, the structure of the chair itself can be simplified, and the lumbar support part can be moved forward according to the degree of weight applied to the backrest. Since the amount of protrusion also changes, the seater should set the protrusion amount of the lumbar support part to obtain his / her favorite waist feeling by changing his / her weight without operating a dedicated operation part. Can do.

  In particular, any one member of the tilting frame or the support is provided with an overhang portion extending in a predetermined direction from the pivot point, and between the overhang portion and the other member. If an elastic body that generates a reaction force along with the backward tilting operation of the tilting frame is disposed, a reaction force mechanism dedicated to the back tilt operation in which the tilting frame tilts backward with respect to the support body is supported with the tilting frame. It can be aggregated in the region near the pivot point with the body, resulting in a simple structure.

  In addition, the support includes a leg frame structure, and a base frame having a lower end fixed to the leg frame structure and a lower end of the tilting frame pivoted at the upper end. For example, it is possible to configure a support body applicable to the chair of the present invention simply by fixing the base frame to the conventionally used leg frame structure, and it can be shared with the leg frame structure of other chairs. Can be effectively achieved.

  In order to prevent the convex deformation of the lumbar support part forward due to the lumbar support part interfering with the tilt, the backrest is interposed between the tilt frame and the lumbar support part of the back shell. What is necessary is just to form the space which accept | permits the curve deformation | transformation of the said shell at the time of back tilting operation | movement.

  Further, if at least one of the tilting frame or the support body supports the back shell in a state where the back shell is slidably movable in the height direction, the seated person puts his weight on the backrest, When the tilting frame tilts backward about the pivot point, the back shell slides and moves in the height direction with respect to at least one member of the tilting frame or the support body, thereby smoothly bending the entire back shell. Can be done.

  In addition, if the tilting frame is a portion above the lumbar support portion of the back shell and supports only the substantially central portion in the left-right width direction, both side ends of the back shell are in a free state. Even if the back shell, which is a plate member made of resin, is configured to have a strength that supports the back load of the seated person, if a load is applied to both left and right end portions of the back shell, depending on the load Can be bent flexibly and greatly. In this way, twisting deformation of the back shell is allowed, and three-dimensional deformation of the back shell according to how the seated person's weight is applied and the movement of the back is possible.

  To ensure that the lumbar support can protrude forward while the entire back shell is curved and deformed when the seated person puts weight on the back shell and the tilting frame tilts backward around the pivot point In order to orient the deformation characteristics of the back shell, it is preferable that the lumbar support portion of the back shell is provided with a deformation inducing means that is more easily deformed than the peripheral portion of the lumbar support portion.

  A preferred embodiment of the deformation inducing means includes an aspect in which the deformation inducing means is constituted by one or a plurality of slits extending in the lateral width direction of the back shell.

  As described above, according to the present invention, in the chair having the back tilt function, the whole back shell is moved along with the transition from the normal state in which no load is applied to the backrest to the back tilt state in which the backrest is tilted backward. The lumbar support part protrudes forward while being bent and deformed to provide a chair that does not give the seated person an uncomfortable feeling that the back and waist are forced forward locally.

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

  As shown in FIG. 1, the chair 1 according to the present embodiment has a support frame 2 (corresponding to the “support” of the present invention), a seat 3 fixed to the support frame 2, and a lower end rotated to the support frame 2. The chair includes a tilting frame 4 that can be attached and a backrest 5 mainly composed of a back shell 51 in which an upper part and a lower part are supported by the tilting frame 4 and the support frame 2, respectively.

  The support frame 2 includes a pair of left and right front leg frames 21, a pair of left and right rear leg frames 22, and a pair of left and right first connection frames that connect upper ends of the front leg frame 21 and the rear leg frame 22 that face each other in the front-rear direction. 23, a second connection frame 24 that connects the vicinity of the upper end portions of the rear leg frame 22, and a third connection frame (not shown) that connects the vicinity of the upper end portions of the front leg frame 21. The main frame is further provided with a base frame 25 for supporting the tilting frame 4. A seat support frame that can directly support the back surface of the seat 3 together with the first connection frames 23 is provided between the pair of left and right first connection frames 23 (not shown). In the present embodiment, the front leg frame 21, the rear leg frame 22, the first connection frame 23, the second connection frame 24, and the third connection frame that constitute the leg frame structure are made of a metal pipe material. The leg frame structure of the present embodiment uses the leg frame structure of another existing chair, and the base frame 25 is integrally provided on such a leg frame structure as the support of the present invention. A functioning support frame 2 is formed.

  The base frame 25 has a pair of left and right base frame main bodies 251 each having a lower end fixed to the center in the left-right width direction of the second connecting frame 24 by appropriate means such as welding. Each base frame main body 251 has a substantially plate shape, and has a side view shape in which a central portion in the height direction is bent so as to protrude rearward from the lower end portion and the upper end portion.

  The seat 3 is composed of a seat shell that plays a role as a structural member that evenly supports the load applied to the seat 3. The seat cushion may be provided with a seat cushion provided above the seat shell and a seat cushion cover that covers the seat cushion.

  The backrest 5 has a size that can support the entire upper body of the seated person, and includes a back shell 51 that serves as a structural member that evenly supports the load applied to the backrest 5. In addition, you may provide the back cushion provided in front of the back shell 51, and the back cushion cover which coat | covers this back cushion.

  The back shell 51 is mainly composed of a resin-made elastic plate-like body, and the upper and lower portions protrude rearward from the central portion in the height direction, and the left and right side edges are forward from the central portion in the left-right width direction. It has a protruding three-dimensional shape. A large number of openings 511 are provided in a region above the lumbar support portion 51L that can support the waist of the seated person in the back shell 51, more specifically, in a region above the center in the height direction of the back shell 51. The opening ratio, which is the ratio occupied by the opening 511 in a predetermined region of the back shell 51, is set so as to gradually increase toward the upper edge and both side edges of the back shell 51. In the following description, the entire region provided with the opening 511 in the back shell 51 is referred to as “back shell upper portion 51T”. That is, as shown in FIG. 4 and the like, the back shell 51 is positioned slightly below the back shell upper part 51T, the back shell central part 51S that is the central part in the height direction of the back shell 51, and the back shell central part 51S. The lumbar support 51L and the back shell lower portion 51U, which is a region below the lumbar support 51L, are integrally provided. The curvature of the curved surface in plan view of the back shell central portion 51S, the lumbar support portion 51L, and the back shell lower portion 51U is the same, and this curvature is set larger than the curvature of the curved surface in plan view of the back shell upper portion 51T. Yes. 2 (this figure corresponds to FIG. 1 and is a diagram schematically showing only the back shell 51 in the central longitudinal section in the left-right width direction), and has a relatively large curvature. The central portion 51S, the lumbar support portion 51L, and the back shell lower portion 51U have a curved shape that is continuous with a bow, while the back shell upper portion 51T having a relatively small curvature has a substantially straight shape along the height direction. Become. The back shell central portion 51S and the back shell upper portion 51T are continuous with each other with a discontinuous line 512 as a boundary.

  The lumbar support portion 51L of the back shell 51 is provided with deformation inducing means 513 that makes it easier to partially deform than the peripheral portion of the lumbar support portion 51L. In this embodiment, a slit 513a extending in the left-right width direction is applied as the deformation inducing means 513. The slit 513a may be a single slit or a plurality of slits. In the present embodiment, a pair of upper and lower slits 513a spaced apart from each other in the height direction are provided.

  The back shell upper portion 51T is schematically shown in FIG. 3 (the figure shows a state before the back shell upper portion 51T is assembled to the tilting frame 4 in order to show the manner of assembling the back shell 51 and the tilting frame 4 in the region X of FIG. As shown in the figure, an engaging portion 514 that protrudes rearward and engages with a slide engaging hole 41 formed at an upper end portion of a tilting frame 4 described later is integrally or integrally provided. In FIG. 3, the opening 511 of the upper back shell 51T is omitted. The engaging portion 514 has a substantially block shape, and has a flange portion 514a integrally at a tip portion (an end portion on the side away from the back surface of the back shell 51).

  The back shell lower portion 51U is integrally or integrally provided with a supported portion 515 that protrudes rearward and is supported by the upper end portion of the base frame 25, as shown in FIG. In the present embodiment, a pair of left and right thin plate-like supported portions 515 are provided at the lower end portion of the back shell lower portion 51 </ b> U, that is, the lower end portion of the back shell 51.

  As shown in FIG. 1 and the like, the tilting frame 4 supports a portion of the back shell 51 above the lumbar support portion 51L that supports the waist of the seated person, specifically, the back shell upper portion 51T. A pivot point (support shaft X1 to be described later) with the base frame 25 is set rearward on the lower end side of the back shell 51, and the tilting frame 4 tilts with respect to the base frame 25 around the pivot point. (Tilt operation) is possible. The tilt frame 4 has a width dimension that is sandwiched between the pair of left and right base frame bodies 251 and has an upper end portion and a lower end portion that protrude rearward from the central portion in the height direction and is omitted in a side view. It is a letter shape. As shown in FIG. 3, a slide engagement hole 41 in which the engagement portion 514 provided in the back shell upper portion 51T is slidably engaged is formed in the upper end portion of the tilting frame 4. The slide engagement hole 41 is continuously provided above the large hole portion 41a and the large hole portion 41a into which the flange portion 514a of the engagement portion 514 can be inserted and removed, and the flange portion 514a inserted from the large hole portion 41a. And a small hole portion 41b that can allow the relative sliding movement of the engaging portion 514 in a state where it does not come off. The height dimension of the small hole portion 41b is set to be larger than the height dimension of the large hole portion 41a, and the margin for relative sliding movement of the engagement portion 514 with respect to the slide engagement hole 41 is ensured.

  An insertion hole penetrating in the left-right width direction is formed in the lower end portion of the tilting frame 4, and the support shaft is connected to the insertion hole and the insertion hole provided in the upper end portion of each base frame body 251. By inserting X1, the tilting frame 4 can be tilted backward about the support shaft X1 (corresponding to “the pivot point” of the present invention). In the present embodiment, the support shaft X <b> 1 is set so as to be arranged rearward on the lower end side of the back shell 51. Furthermore, the tilting frame 4 includes an overhang portion 42 extending downward from the pivot point (support shaft X1), and the tilting frame 4 is tilted backward between the overhang portion 42 and the base frame 25. A coil spring 6 which is an elastic body of the present invention that generates a reaction force in accordance with the operation is provided. In this embodiment, the base frame main body 251 is fixed in a state where a connecting shaft 252 for connecting the base frame main body 251 is bridged between portions slightly lower than the bent portion. One end of the coil spring 6 is supported by 252 and the other end of the coil spring 6 is supported by the overhang portion 42 of the tilting frame 4. Further, the supported portion 515 of the back shell 51 is fixed to a portion near the upper end of each base frame main body 251 by an appropriate means such as a screw so that the relative angle cannot be changed.

  The tilt frame 4 and the base frame 25 are covered with a tilt frame cover body and a base frame cover body (not shown) from the rear or the lower side, respectively, so that they cannot be directly seen.

  A space is formed between the back shell 51 and the tilt frame 4 in a state where the back shell upper portion 51T and the back shell lower portion 51U are supported by the upper end portion of the tilt frame 4 and the upper end portion of the base frame 25, respectively.

  Next, the usage method and effect | action of the chair 1 which concerns on this embodiment comprised from each member mentioned above are demonstrated.

  As shown in FIG. 1, the chair 1 according to the present embodiment has a backrest 5 in a normal state (S) in which the backrest 5 takes a standing posture and a normal state (S) as shown in FIG. The tilt frame 4 tilts backward about the support shaft X1 (the pivot point of the present invention) by applying the weight to the back, and accordingly, the back shell 51 as a whole is bent back like a bow in side view ( T) can be taken at least.

  In the normal state (S), the back shell 51 mainly composed of an elastic plate-like body is held in a curved shape like a side view bow against its elasticity.

  When the seated person puts his / her weight on the backrest 5 with respect to the chair 1 in the normal state (S), the tilting frame 4 is supported by the support frame 2 (specifically, the base frame 25) about the support shaft X1. Tilt backwards. Along with the backward tilting operation of the tilting frame 4, the back shell 51 of the back shell 51 supported on the tilting frame 4 is subjected to a force to warp backward, while the back shell 51 supported on the base frame 25 is supported. Since the lower end portion of the shell 51 tries to stay at the position in the normal state (S) by the base frame 25 that does not tilt backward, the back shell 51 further moves forward through a portion between the back shell upper portion 51T and the back shell lower portion 51U. Further curved and deformed like a bow so as to protrude. In this embodiment, since the lumbar support 51L of the back shell 51 is provided with the deformation inducing means 513, specifically, the slit 513a, when the entire back shell 51 is curved and deformed like a bow, the opening height of the slit 513a is set. The lumbar support 51L is deformed in the narrowing direction, and as a result, the lumbar support 51L protrudes relatively forward as compared to the normal state (S). Even in the back tilt state (T), a space is formed between the tilt frame 4 and a portion of the back shell 51 that is not supported by the tilt frame 4 (the central portion 51S and the lumbar support portion 51L). Further, in the present embodiment, the back shell upper portion 51T is engaged with and supported by the tilting frame 4 so as to be relatively slidable in the height direction, and when the tilting frame 4 tilts backward, the back shell upper portion 51T is provided. By tilting the engagement portion 514 in the height direction within a range in which the engagement state with respect to the slide engagement hole 41 is not released within the slide engagement hole 41 formed in the upper end portion of the tilt frame 4, the tilt frame is provided. 4 so that the entire back shell 51 can be smoothly curved and deformed in accordance with the backward tilting operation. The chair 1 of the present embodiment has a tilting frame 4 in the region of the upper portion 51T of the back shell 51T that has a curvature of a curved surface in plan view that is smaller than other portions and is substantially straight along the height direction. Therefore, the sliding movement can be smoothly performed in a stable state.

  As the chair 1 shifts from the normal state (S) to the back tilt state (T), the overhang portion 42 of the tilting frame 4 causes the coil spring 6 interposed between the overhang portion 42 and the base frame 25 to move. Press in the direction to accumulate the repulsive force. Therefore, when the seated person removes his / her back from the backrest 5, that is, raises his / her upper body, the chair frame 1 naturally returns to the normal posture before the tilting frame 4 is tilted backward by the repulsive force of the coil spring 6. Will return to the normal state (S). Further, when the chair 1 shifts from the normal state (S) to the back tilt state (T), the elastic return force of the back shell 51 that is curved and deformed more like a bow than the shape in the normal state (S) moves the tilt frame 4 forward. Acts as a force for energizing in the direction of pulling back. Accordingly, when the chair 1 is in the back tilt state (T), the urging force further increases when the seated person puts his / her weight on the lumbar support portion 51L, and the urging force and the repulsive force of the coil spring 6 are in combination. In other words, when the seated person lifts his back from the backrest 5, that is, when the upper body is raised, the tilting frame 4 automatically returns to the normal posture before tilting back following the movement.

  As described above, the chair 1 according to this embodiment includes the tilting frame 4 that supports a portion of the back shell 51 above the lumbar support portion 51L, specifically the back shell upper portion 51T, and the lower end portion of the back shell 51. Since the pivot point (support shaft X1) with the supporting base frame 25 is set to the rear on the lower end side of the back shell 51, when the seated person puts his weight on the backrest 5, the tilting frame 4 It tilts backward about the pivot point (support axis X1), and accordingly, the upper side of the back shell 51 warps backward, and as a result, the region between the upper and lower portions of the back shell 51, specifically, The lumbar support portion 51L is naturally bent and deformed in a direction protruding forward, so that a good comfort can be given to the seated person. In addition, in the back tilt state (T), the lumbar support portion 51L is not supported from the back by other members, in other words, the back portion of the seat shell 51 itself is supported only by the elasticity of the back shell 51 itself. If the lumbar support 51L is pressed and supported from behind by another member or mechanism and protrudes forward, it eliminates or suppresses the uncomfortable feeling of the waist that can be given to the seated person, and is natural for the seated person. It gives a feeling of waist contact. Further, the amount of protrusion of the lumbar support 51L forward also changes depending on the degree of weight applied to the upper portion of the back shell 51, so that the seated person can apply his / her own weight without operating the dedicated operation part separately. Can be set to the protruding amount of the lumbar support portion 51L that gives a desired feeling of waist contact, and simplification of the structure and improvement in usability can be achieved at the same time.

  In particular, the tilt frame 4 includes an overhang portion 42 that extends further downward than the pivot point (support shaft X1), and the tilt frame is provided between the overhang portion 42 and the base frame 25. 4 is provided with a coil spring 6 that generates a reaction force in accordance with the backward tilting operation of the rear frame 4. Therefore, the reaction force mechanism for the back tilt is disposed in the region near the pivot point (support axis X1) between the tilting frame 4 and the base frame 25. It can be made into a compact one.

  In addition, since it is set so that a space is formed between the tilting frame 4 and the lumbar support part 51L of the back shell 51, the lumbar support part 51L interferes with the tilting frame 4 so that the lumbar support part 51L It is possible to reliably prevent the forward convex deformation from being suppressed.

  Further, since the tilt frame 4 supports the back shell 51 in a state of being slidably movable in the height direction, the seated person puts weight on the back shell 51 and the tilt frame 4 is pivotally attached. When the back shell 51 is tilted backward about the point (support axis X1), the back shell 51 slides in the height direction with respect to the tilting frame 4 to allow the back shell upper portion 51T to be warped backward, and the back shell 51 It is possible to smoothly perform a deformation operation in which the whole is bent like a bow.

  Furthermore, since the single tilting frame 4 is arranged only at the substantially center part in the left-right width direction of the back shell 51, both side ends of the back shell 51 are opened, and the torsional deformation of the back shell 51 is allowed. The three-dimensional bending deformation of the back shell 51 according to how the seated person's weight is applied becomes possible. In the present embodiment, since the plurality of openings 511 are formed in the back shell upper portion 51T, the presence of the plurality of openings 511 enables smooth twist deformation of the back shell upper portion 51T capable of supporting the vicinity of the shoulder of the seated person. Has contributed greatly to the realization of In addition, the smoothness of the upper portion of the back shell 51 </ b> T is that the opening ratio, which is the ratio of the opening 511 in the predetermined region, is set to gradually increase toward the upper edge and both side edges of the back shell 51. This contributes to the realization of a torsional deformation.

  In order to orient the deformation characteristics of the back shell 51, the lumbar support portion 51L of the back shell 51 is provided with deformation inducing means 513 that is more easily deformed than the peripheral portion of the lumbar support portion 51L. Is tilted backward about the pivot point (support axis X1), the lumbar support 51L can be reliably projected forward while the entire back shell 51 is curved and deformed. In particular, in the present embodiment, since the deformation inducing means 513 is configured by the plurality of slits 513a extending in the left-right width direction of the back shell 51, the deformation inducing means 513 can be realized by a very simple method.

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

  For example, in the above-described embodiment, the tilt frame 4 includes the overhang portion 42 that extends in a predetermined direction from the pivot point (support shaft X1), and the tilt frame 4 is disposed between the overhang portion 42 and the base frame 25. Although the aspect which arranged the elastic body (coil spring 6) which generate | occur | produces a reaction force with back tilting operation was illustrated, it replaced with this and a base frame is further predetermined direction (for example, upward) from the pivot point with a tilting frame. It is also possible to provide an overhang portion that extends to the top and an elastic body that generates a reaction force in association with the backward tilting motion of the tilting frame between the overhanging portion and the tilting frame.

  In addition, as an elastic body that generates a reaction force in accordance with the backward tilting motion of the tilting frame, the leaf spring or the axial direction is made to substantially coincide with the widthwise direction of the chair, and both ends are extended in directions away from the axial center. A so-called wound spring or rubber may be applied. Furthermore, the overhang provided on either the tilting frame or the base frame accumulates a repulsive force with the elastic body interposed between the overhanging part and the other frame as the tilting frame is tilted backward. Of course, it does not matter even if it pulls in the direction to do.

  In the above-described embodiment, the tilt frame 4 supports the back shell upper portion 51T in a state in which the back shell upper portion 51T is slidably engaged in the height direction. (Base frame) may support the lower part of the back shell in a state of being slidably movable in the height direction, or both the tilting frame and the support body It may be supported in a state of being slidably movable in the vertical direction. That is, a mode in which a slide engagement mechanism that allows relative sliding movement between the back shell and the tilting frame and / or the support is provided only between the tilting frame and the back shell, or between the support and the back shell. Any of these modes may be employed, or a mode provided between the tilting frame and the back shell and a mode between the support and the back shell. Furthermore, the slidable distance may be appropriately changed according to the specifications. In the said embodiment, although the aspect which engages an engaging part with an engagement hole was illustrated, it may replace with an engagement hole and may apply an engagement groove | channel. In addition, as the slide engagement mechanism, an engagement recess such as an engagement hole or an engagement groove is integrally provided on the back shell side, and an engagement projection that can slide-engage with the engagement recess on the tilt frame and / or the support body side. You may employ | adopt the aspect which provided the part. As an example, as shown in FIG. 5, a pocket-shaped engaging recess 514 ′ opening only downward is integrally provided on the back surface of the back shell 51 (upper shell upper portion), while the tilting frame 41 is engaged with the engagement. An upward engaging engagement convex portion 41 ′ having an L-shape that can be inserted from below is provided in the concave portion 514 ′, and the engaging convex portion 41 ′ and the engaging concave portion are engaged with the backward tilting operation of the tilting frame 4. The back shell 51 slides in the height direction relative to the tilting frame 41 by reducing the amount of squeezing of the engaging recess 514 ′ with respect to the engaging protrusion 41 ′ within a range where the engagement state with 514 ′ is not released. The aspect made to obtain is mentioned. In this case, the engaging concave portion and the engaging convex portion can be engaged with each other by dropping the back shell into the tilting frame from above, and the assembling work can be easily performed.

  Moreover, it is good also as an aspect which has arrange | positioned the tilting frame to the both-sides edge part or both-sides edge part vicinity of a back shell, respectively. That is, a chair provided with a plurality (including three or more) of tilting frames may be used. In this case, the support may be provided with the same number of base frames as the number of tilting frames.

  As a means for inducing deformation, instead of slits extending in the lateral width direction of the back shell, thin-walled portions (thin-wall hinges), notched portions cut out from the both side edges of the back shell toward the lateral center in the lateral direction, A plurality of holes provided at equal intervals or intermittently along the left-right width direction may be applied.

  Further, the support body may support a portion near the lower end portion instead of the lower end portion of the back shell.

  A support provided with casters at the lower ends of the front leg frame and the rear leg frame, or a support frame that connects the lower ends of the front leg frame and the rear legs may be applied. Further, a support that does not include the base frame shown in the above embodiment may be applied. In this case, the tilting frame is pivotally supported by a part of the leg frame structure, or the lower end of the back shell. What is necessary is just to make it support a part or a lower end part vicinity.

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

The figure which abbreviate | omits some side surfaces of the chair (normal state) which concerns on one Embodiment of this invention, and shows typically. The figure which shows typically only a back shell in the left-right width direction center longitudinal cross-section in FIG. The figure which shows typically the assembly | attachment aspect of the back shell and tilting frame in the X area | region of FIG. The figure which shows the chair in a back tilt state in the same embodiment corresponding to FIG. The figure which shows typically the modification of the slide engagement mechanism in the embodiment corresponding to FIG.1 and FIG.4.

Explanation of symbols

1 ... chair 2 ... support (support frame)
25 ... Base frame 4 ... Tilt frame 42 ... Overhang part 5 ... Backrest 51 ... Back shell 513 ... Deformation inducing means 513a ... Slit 51L ... Lumber support part 6 ... Elastic body (coil spring)
X1 ... pivot point (support axis)

Claims (8)

A backrest having an elastically deformable back shell;
A tilting frame that supports a portion above the lumbar support part that supports the waist of the seated person in the back shell;
A support for supporting the lower end of the back shell or the vicinity of the lower end, and
The tilting frame and the support are pivotally mounted, the pivoting point is set to the rear on the lower end side of the back shell, and the tilting frame tilts backward with respect to the support with the pivoting point as a center. In accordance with the operation, the back shell is generally curved and deformed so that the lumbar support portion protrudes relatively forward. Any one member of the tilting frame or the support body includes an overhang portion extending in a predetermined direction from the pivot point, and between the overhang portion and the other member, The chair according to claim 1, wherein an elastic body that generates a reaction force with a backward tilting motion of the tilting frame is disposed. 2. The support includes a leg frame structure, and a base frame having a lower end fixed to the leg frame structure and a lower end of the tilting frame pivoted at the upper end. Or the chair of 2. The chair according to claim 1, 2, or 3, wherein a space is formed between the tilt frame and the lumbar support portion of the back shell. The chair according to claim 1, 2, 3, or 4, wherein at least one of the tilting frame and the support body supports the back shell in a state of being slidably engaged in a height direction. The chair according to claim 1, 2, 3, 4 or 5, wherein the tilting frame is a part above the lumbar support part of the back shell and supports only the substantially central part in the left-right width direction. In order to orient the deformation characteristics of the back shell, the lumbar support part of the back shell is provided with a deformation inducing means that makes it easier to partially deform than the peripheral part of the lumbar support part. The chair according to 3, 4, 5 or 6. The chair according to claim 7, wherein the deformation inducing means is one or a plurality of slits extending in a lateral width direction of the back shell.

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