Chair load-supporting structure and chair

Abstract

To provide a load support structure of a chair capable of appropriately changing a curved shape of a receiving surface component according to sitters of varying physiques without any manual operation, and a chair.SOLUTION: A load support structure of a chair 1 includes a backrest plate 20 (a receiving surface component) having a curved receiving surface 20a for receiving a load from a sitter, a backrest support member 7 (a load support part) for supporting the backrest plate 20 from a back side of the receiving surface 20a, curved shape change means 50 for changing a curvature radius of the receiving surface 20a from an initial-state curvature radius (a shape C1) to a relatively large curvature radius (a shape C2) depending on the load received by the backrest plate 20, and energizing means 60 for returning the curvature radius of the receiving surface 20a to the initial state.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a load-bearing structure for a chair and a chair. [Background technology]

[0002] Patent Document 1 below discloses a chair that can greatly change the curved shape of the backrest (load-bearing structure) while suppressing a decrease in the force that supports a seated occupant. This chair has a backrest with a receiving surface component that comes into contact with the seated occupant and receives the load, a backrest support member (load-bearing member) that supports the backrest from behind, and a curved shape changing means that changes the curved shape of the receiving surface component, the curved shape changing means having an operating member movably supported on either the backrest or the backrest support member, and the operating member having a base end that is rotatably supported on either the backrest or the backrest support member, and a tip end that rotates around the base end and presses against the other side of the backrest or the backrest support member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6465525 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above chair, the curved shape of the backrest's receiving surface can be changed by pressing both widthwise ends of the backrest with an operating member, but the adjustment requires manual operation of the operating member, which is time-consuming. Also, in order to accommodate seated occupants of various physiques, the position of the operating member needs to be adjustable in multiple stages, which makes the chair structure complicated. Furthermore, in the above-mentioned chair, the curved shape of the receiving surface component of the backrest is changed from an initial state with a large radius of curvature to a state with a small radius of curvature, so it is difficult to change the radius of curvature to a value greater than that of the initial state, which poses particular challenges in accommodating seated occupants with large builds.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a load-supporting structure for a chair and a chair in which the curved shape of the receiving surface component can be appropriately changed without manual operation to suit occupants of various physiques. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following aspects. A load support structure for a chair according to one aspect of the present invention comprises a receiving surface component having a curved receiving surface that receives a load from a seated person, a load support component that supports the receiving surface component from the back side of the receiving surface, a curved shape changing means that changes the radius of curvature of the receiving surface from the initial radius of curvature to a relatively larger radius of curvature in accordance with the load received by the receiving surface component, and a biasing means that returns the radius of curvature of the receiving surface to its initial state.

[0007] According to this aspect, the radius of curvature of the receiving surface of the receiving surface component that receives the load from the seated occupant is initially small, and the curved shape is changed from small to large depending on the load received by the receiving surface component. This makes it possible to provide a comfortable fit to seated occupants of various physiques, from small to large. Furthermore, when the load on the receiving surface component is released, the radius of curvature of the receiving surface can be returned to its initial state by the biasing means. Therefore, the curved shape of the receiving surface component can be appropriately changed to suit seated occupants of various physiques without manual operation.

[0008] In the load support structure of the chair of the above-mentioned one embodiment, the curved shape changing means may include free end portions on both widthwise sides of the receiving surface component that are not supported by the load support portion, and a supported portion of the receiving surface component that is supported by the load support portion, widthwise inward from the free end portions. According to this aspect, both widthwise ends of the receiving surface component are free ends that are not fixed to the load support portion, and the free ends are displaced using the supported portion on the inside widthwise side of the receiving surface component as a fulcrum, and this is then urged toward the initial state by a urging means, thereby creating a state in which the load received from the seated occupant is offset, and a curved shape can be formed that can provide a comfortable fit for seated occupants of various body types.

[0009] In the load support structure for a chair according to the above aspect, the supported portions may be provided in pairs spaced apart from each other in the width direction. According to this aspect, by dividing the supported portions of the receiving surface component into two locations spaced apart in the width direction, the outer and inner width regions of the pair of supported portions are more likely to elastically deform individually, improving the ability to conform to the physique of the seated person.

[0010] In the load support structure of the chair of the above-mentioned one embodiment, the load support portion may include a pair of support portions that support the pair of supported portions, and a leaf spring portion that connects the pair of support portions and presses the space between the pair of supported portions from the back side toward the front side when the receiving surface component receives a load. According to this aspect, when the free ends on the outer width sides of the pair of supported parts are elastically displaced toward the back side of the receiving surface, the inner width sides of the pair of supported parts are elastically displaced toward the front side of the receiving surface due to pressure from the leaf spring parts, so that even if the amount of displacement of the free ends is small, the curved shape of the receiving surface component can be significantly changed.

[0011] In the load support structure for a chair according to the above aspect, the receiving surface component may form a backrest plate. According to this aspect, a backrest that can provide an appropriate fit to seated occupants of various physiques can be obtained.

[0012] In the load-supporting structure of the chair of the above-mentioned one aspect, the backrest plate may include a frame portion that forms the outer shape of the backrest plate, and a plurality of band-shaped portions separated by slits inside the frame portion. According to this aspect, by separating the inside of the frame portion that forms the outer shape of the backrest plate into multiple band-like portions via slits, the inside of the frame portion can be easily elastically deformed individually by the multiple band-like portions, thereby improving the ability to conform to the physique of the seated person.

[0013] In the load support structure of the chair of one embodiment described above, the multiple band-like portions include a pair of band-like portions separated to the left and right by the slit at the widthwise center of the backrest plate, and the widthwise inner ends of each of the pair of band-like portions may be supported by the load support portion at the widthwise center of the backrest plate. According to this aspect, the separation of the backrest plate at the widthwise center allows the pair of left and right band-shaped portions to elastically deform individually, making it easier to change the curved shape of the receiving surface of the backrest plate starting from the widthwise center, improving its ability to conform to the physique of the seated person.

[0014] In the load support structure for a chair according to the above aspect, the widthwise inner ends of the pair of band-shaped portions may each include a pivot shaft that is pivotally supported by the load support portion around a rotation axis that extends in the vertical direction. According to this aspect, when a load is applied by a seated occupant to the frame portion on the widthwise outer side of the pair of left and right band-shaped portions, each of the pair of band-shaped portions rotates around a pivot axis extending in the vertical direction provided at the end on the inner side in the widthwise direction, making it easier for the backrest plate to deform forward and backward in conjunction with the load input to the frame portion.

[0015] In the load support structure for a chair according to the above aspect, the receiving surface component may form a seat plate. According to this aspect, a seat can be obtained that can provide an appropriate fit for seated occupants of various physiques.

[0016] In the load support structure for a chair according to the above aspect, the seat plate may include a pair of mesh plate portions formed to be spaced apart in the width direction. According to this aspect, the widthwise outer and inner regions of the pair of mesh plate portions are easily elastically deformed separately, improving the ability to conform to the physique of the seated person.

[0017] A chair according to one aspect of the present invention comprises the load-bearing structure described above. According to this aspect, a chair can be obtained that can provide an appropriate fit to seated occupants of various physiques. [Effects of the Invention]

[0018] According to the above aspects, it is possible to obtain a load support structure for a chair and a chair in which the curved shape of the receiving surface component can be changed appropriately to suit seated occupants of various physiques without manual operation. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of a chair according to a first embodiment, viewed from the front side. [Figure 2] FIG. 1 is a front view of a chair according to a first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 10 is a front view of a chair according to a modified example of the first embodiment. [Figure 5] FIG. 2 is a perspective view of a seat body and a seat receiving member according to the first embodiment. [Figure 6] FIG. 2 is an exploded perspective view of a seat body and a seat receiving member according to the first embodiment. [Figure 7] FIG. 2 is a plan view of a seat body and a seat receiving member according to the first embodiment. [Figure 8] FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 7. [Figure 9] 9 is a cross-sectional view taken along the line IX-IX in FIG. 7. [Figure 10] FIG. 10 is a front view of a chair according to a second embodiment. [Figure 11] FIG. 11 is an enlarged view of an area XI shown in FIG. [Figure 12] 12 is a cross-sectional view taken along the line XII-XII in FIG. 11. [Figure 13] 13 is a cross-sectional view taken along the line XIII-XIII in FIG. 11. [Figure 14] 14 is a cross-sectional view taken along the line XIV-XIV in FIG. 10. [Figure 15] 11 is a cross-sectional view taken along the line XV-XV of FIG. 10. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. In the following description, the direction indicated by the arrow FR in the figure, which points toward the front of a person seated in a chair in a normal posture, will be referred to as "front," and the opposite direction will be referred to as "rear." Regarding "up," "down," "left," and "right," the direction indicated by the arrow UP in the figure above a person seated in a chair in a normal posture will be referred to as "up," and the opposite direction will be referred to as "down." The direction indicated by the arrow LH in the figure to the left of a person seated in a chair in a normal posture will be referred to as "left," and the opposite direction will be referred to as "right." In the following description, an example will be given in which the width direction of the load-supporting structure of the chair coincides with the left-right direction.

[0021] (First embodiment) FIG. 1 is a perspective view of a chair 1 according to a first embodiment, viewed from the front side. As shown in Figure 1, the chair 1 of this embodiment comprises legs 2 placed on the floor, a box-shaped support base 3 installed at the upper ends of the legs 2, a seat body 4 on which an occupant sits, a seat support member 5 attached to the upper surface of the support base 3 and supporting the seat body 4, a backrest 6 that supports the back of the occupant seated on the seat body 4, a backrest support member 7 (see Figure 2 described later) that supports the backrest 6 from behind, and armrests 8 that support the elbows of the occupant seated on the seat body 4.

[0022] The leg section 2 comprises a multi-pronged leg 11 with casters 2a, and a base 12 that rises from the center of the multi-pronged leg 11 and has a built-in gas spring that serves as a lifting mechanism. A support base 3 is attached to the upper end of the base 12 so that it can rotate horizontally. The support base 3 houses a lift adjustment mechanism (not shown) for the base 12 and a tilt adjustment mechanism (not shown) for the backrest support member 7. Reference numeral 13 denotes an operating knob for the tilt adjustment mechanism that protrudes from the side of the base 3. Reference numeral 14 denotes a slider that extends the front end of the seat body 4 forward when it is in a folded and extended state.

[0023] [Backrest load-bearing structure] Fig. 2 is a front view of the chair 1 according to the first embodiment. In Fig. 2 and subsequent figures, the cushioning material and seat covering material covering the surfaces of the seat board 40 and back board 20 have been removed to improve visibility of the main parts of the seat body 4 and backrest 6. Fig. 3 is a cross-sectional view taken along the line III-III in Fig. 2. As shown in Fig. 2, the backrest 6 includes a resin-molded backrest plate 20 (receiving surface component) that forms the framework of the backrest 6. Reference numeral 15 shown in Fig. 2 denotes an operating lever for the elevation adjustment mechanism in the support base 3.

[0024] The backrest plate 20 has a generally rectangular shape with rounded corners when viewed from the front as shown in Fig. 2. The backrest plate 20 includes a frame portion 21 that forms the outer shape of the backrest plate 20, and a plurality of band-shaped portions 22 separated by slits 23 inside the frame portion 21. The slits 23 that separate the band-shaped portions 22 include a first slit 23a, a second slit 23b, and a third slit 23c.

[0025] The first slit 23a extends in the vertical direction at the left-right central position of the backrest plate 20. The first slit 23a is a slit that separates the left and right band-shaped portions 22 inside the frame portion 21. The second slit 23b is a slit that extends to both the left and right sides from the first slit 23a and separates the upper and lower band-shaped portions 22. The second slits 23b are formed in multiple stages spaced apart in the vertical direction. As a result, pairs of left and right band-shaped portions 22 are formed in multiple stages inside the frame portion 21.

[0026] The angles of the second slits 23b with respect to the horizontal plane are not uniform, and with the second slit 23b in the second row from the bottom as the reference (0 degrees), the second slits 23b in the upper rows have positive angles where the outer ends in the left and right direction are higher, and conversely, the second slits 23b in the lower rows have negative angles where the outer ends in the left and right direction are lower. Also, the angles of the second slits 23b in the upper rows with respect to the horizontal plane become larger on the positive side as they go up.

[0027] The third slits 23c extend from the outer left-right ends of the second slits 23b in a direction intersecting with the second slits 23b, forming the boundary between the frame portion 21 and the band-like portion 22. The third slits 23c are bent in an L-shape relative to the second slits 23b, making the connection width between the frame portion 21 and the band-like portion 22 narrower than the vertical width of the band-like portion 22. This makes it easier for the individual band-like portions 22 to elastically deform individually relative to the frame portion 21, improving the ability to conform to the physique of the seated person.

[0028] As shown in Fig. 3, the backrest plate 20 configured as described above has a curved receiving surface 20a that receives the weight of a seated occupant. The receiving surface 20a has a curved shape that convexly faces rearward in a plan view. The backrest support member 7 supports the backrest plate 20 from the back side of the receiving surface 20a. As shown in Fig. 2, the backrest support member 7 includes a first support portion 30 that extends in the vertical direction and supports the center portion of the backrest plate 20 in the left-right direction, and a second support portion 31 that extends from the upper end of the first support portion 30 to both left and right sides and supports the upper end of the backrest plate 20.

[0029] The lower end of the first support part 30 has a generally L-shape in side view, and its front lower end is connected to the tilt adjustment mechanism inside the support base 3. The first support part 30 is formed like a column extending in the vertical direction, and supports the inner end in the left-right direction of the band-shaped part 22 of the backrest plate 20 via a supported part 52 (described later). The second support part 31 is formed like a plate extending in the left-right direction, and fixes one side extending in the left-right direction at the upper end of the frame part 21 of the backrest plate 20 at multiple points via fixing members 32 such as bolts.

[0030] 3, the backrest plate 20 has free end portions 51 on both left and right sides that are not supported by the backrest support member 7, and supported portions 52 that are supported by the backrest support member 7 and are located inside the free end portions 51 in the left and right direction. The free end portions 51 and the supported portions 52 form a curved shape changing means 50 that changes the radius of curvature of the receiving surface 20a from the initial radius of curvature (shape C1) to a relatively larger radius of curvature (shape C2) in accordance with the load received by the backrest plate 20.

[0031] The free end portion 51 is formed by both left and right sides of the frame portion 21 and the left and right outer ends of the left and right band-shaped portions 22. The supported portion 52 is formed by the left and right inner ends of the left and right band-shaped portions 22 supported by the backrest support member 7. The supported portion 52 is provided in pair, spaced apart in the left and right direction. The supported portion 52 is formed by a ball stud 52a attached to the rear surface 20b of the backrest plate 20 and a socket 52b that spherically receives the ball stud 52a. The socket 52b is attached to a mounting plate 33 fixed to the front side of the first support portion 30 of the backrest support member 7.

[0032] Next, a description will be given of the shape change of the backrest 6 configured as described above using the load support structure.

[0033] When a seated person applies a load to the backrest 6, the free end 51 on the outer side in the left-right direction of the backrest plate 20, which is not fixed to the backrest support member 7, is elastically displaced rearward in response to the load, with the supported portion 52 on the inner side in the left-right direction of the backrest plate 20 as a fulcrum. When the free end 51 of the backrest plate 20 is elastically displaced rearward, the radius of curvature of the receiving surface 20a is changed from the radius of curvature in the initial state (shape C1) to a relatively larger radius of curvature (shape C2).

[0034] Specifically, depending on the physique (back width) of the seated person, the portion of the free end 51 that is actually pressed varies between the left and right, thereby changing the amount of rearward pressure applied by the free end 51 in the front-to-rear direction. In other words, the supported portion 52 serves as the fulcrum for the elastic displacement of the free end 51, so the greater the distance from the supported portion 52 in the left-to-right direction to a portion, the greater the amount of rearward displacement in the front-to-rear direction. Here, the free end 51 that has been elastically displaced rearward attempts to return to its initial state before elastic displacement due to the restoring force of the backrest plate 20 itself. This acts as the biasing means 60, and as the free end 51 attempts to return to its initial state, the load received from the seated person and the biasing force of the biasing means 60 cancel each other out, allowing for the formation of a curved shape that provides a comfortable fit for seated people of various physiques.

[0035] In addition, since the supported portions 52 are provided in pairs spaced apart in the left-right direction, the regions on the outside and inside in the left-right direction of the pair of supported portions 52 are easily elastically deformed individually. Furthermore, since the band-shaped portion 22 is separated into left and right parts by the slits 23, when the free end portion 51 is displaced toward the back side of the receiving surface 20a, the region between the pair of supported portions 52 (referred to as the inter-support portion 53) is displaced toward the front side of the receiving surface 20a, so that even if the displacement of the free end portion 51 is small, the overall curved shape of the backrest plate 20 can be changed significantly.

[0036] As such, the load support structure of the backrest 6 (load support structure of a chair) in this embodiment comprises a backrest plate 20 (receiving surface component) having a curved receiving surface 20a that receives the load from a seated person, a backrest support member 7 (load support portion) that supports the backrest plate 20 from the back side of the receiving surface 20a, a curved shape changing means 50 that changes the radius of curvature of the receiving surface 20a from the initial state radius of curvature (shape C1) to a relatively larger radius of curvature (shape C2) depending on the load received by the backrest plate 20, and a biasing means 60 (backrest plate 20) that returns the radius of curvature of the receiving surface 20a to its initial state.

[0037] According to this configuration, the radius of curvature of the receiving surface 20a of the backrest plate 20 that receives the load from the seated person is initially small, and the curved shape is changed from small to large depending on the load received by the backrest plate 20. This allows a comfortable fit for seated occupants of various physiques, from small to large. Furthermore, when the load on the backrest plate 20 is released, the biasing means 60 can return the radius of curvature of the receiving surface 20a to its initial state. Therefore, the curved shape of the backrest plate 20 can be changed appropriately to suit seated occupants of various physiques without manual operation.

[0038] In this embodiment, the curved shape changing means 50 includes free end portions 51 on both left and right sides of the backrest plate 20 that are not supported by the backrest support member 7, and supported portions 52 of the backrest plate 20 that are supported by the backrest support member 7 and are located laterally inward of the free end portions 51. With this configuration, the ends on both left and right sides of the backrest plate 20 are free end portions 51 that are not fixed to the backrest support member 7, and the free end portions 51 are displaced using the supported portions 52 on the inner left and right sides of the backrest plate 20 as fulcrums. These free end portions 51 are then urged toward their initial state by the urging means 60, thereby creating a state in which the load received from the seated person and the urging force of the urging means 60 cancel each other out, making it possible to form a curved shape that provides a comfortable fit for seated people of various physiques.

[0039] In this embodiment, the supported portions 52 are provided in pairs spaced apart in the left-right direction. With this configuration, by dividing the supported portions 52 of the backrest plate 20 into two parts spaced apart in the left-right direction, the outer and inner regions of the pair of supported portions 52 in the left-right direction can easily elastically deform individually, improving the ability to conform to the physique of a seated occupant. Furthermore, with this configuration, when the outer free ends 51 of the pair of supported portions 52 in the left-right direction elastically deform toward the back side of the receiving surface 20a, the inner region of the pair of supported portions 52 in the left-right direction (the inter-supporting portion 53) elastically deforms toward the front side of the receiving surface 20a. Therefore, even if the displacement of the free ends 51 is small, the curved shape of the backrest plate 20 can be changed significantly.

[0040] In this embodiment, the backrest plate 20 forms the backrest 6. This configuration provides the backrest 6 that can provide an appropriate fit to seated occupants of various physiques.

[0041] In this embodiment, the backrest plate 20 includes a frame portion 21 that forms the outer shape of the backrest plate 20, and a plurality of band-like portions 22 that are separated by slits 23 inside the frame portion 21. With this configuration, by separating the inner side of the frame portion 21 that forms the outer shape of the backrest plate 20 into a plurality of band-like portions 22 by the slits 23, the inner side of the frame portion 21 can be easily elastically deformed individually by the plurality of band-like portions 22, improving the ability to conform to the physique of a seated person.

[0042] In this embodiment, the plurality of band-like portions 22 include a pair of band-like portions 22 separated into left and right parts by a slit 23 (first slit 23a) at the widthwise center of the backrest plate 20, and the widthwise inner ends of each of the pair of band-like portions 22 are supported by the backrest support member 7 at the widthwise center of the backrest plate 20. With this configuration, the separation at the widthwise center of the backrest plate 20 allows the pair of left and right band-like portions 22 to elastically deform individually, making it easier to change the curved shape of the receiving surface of the backrest plate 20 starting from the widthwise center, improving its ability to conform to the physique of a seated person.

[0043] The chair 1 according to this embodiment includes the load-supporting structure of the backrest 6, and therefore can provide an appropriate fit to seated persons of various physiques.

[0044] As described above, according to this embodiment, the curved shape of the backrest 6 can be changed appropriately to suit seated occupants of various physiques without manual operation.

[0045] The load support structure of the backrest 6 may have a configuration as shown in FIG.

[0046] FIG. 4 is a front view of the chair 1 according to a modified example of the first embodiment. 4, the third slits 23c are formed in a T-shape extending on both sides in the up-down direction relative to the second slits 23b, and the connection width between the frame portion 21 and the band-like portion 22 is narrower than the up-down width of the band-like portion 22. Even with this configuration, as in the above embodiment, each band-like portion 22 can easily elastically deform individually relative to the frame portion 21, improving the ability to conform to the physique of the seated person.

[0047] [Load-bearing structure of the seat] Fig. 5 is a perspective view of the seat body 4 and the seat receiving member 5 according to the first embodiment. Fig. 6 is an exploded perspective view of the seat body 4 and the seat receiving member 5 according to the first embodiment. Fig. 7 is a plan view of the seat body 4 and the seat receiving member 5 according to the first embodiment. Fig. 8 is a cross-sectional view taken along arrows VIII-VIII in Fig. 7. Fig. 9 is a cross-sectional view taken along arrows IX-IX in Fig. 7. As shown in FIG. 5, the seat body 4 includes a resin-molded seat plate 40 (receiving surface component) that forms the framework of the seat body 4.

[0048] The seat panel 40 has a generally rectangular shape with rounded corners in a plan view shown in FIG. 7. The seat panel 40 includes a pair of mesh panel portions 42 spaced apart in the left-right direction across a central panel portion 41. The pair of mesh panel portions 42 extend from the rear edge of the seat panel 40 to a position forward of the midpoint of the seat panel 40 in the front-to-rear direction. The mesh panel portion 42 is formed by rows of slits extending in the front-to-rear direction that are slightly curved outward in the left-to-right direction, with adjacent rows of slits in the left-to-right direction being offset from each other by approximately half a pitch in the front-to-rear direction. In other words, the mesh panel portion 42 is formed by slits arranged in a staggered pattern.

[0049] The seat panel 40 includes a central plate portion 41 that forms the center in the left-right direction, a pair of mesh plate portions 42 formed on both left-right sides of the central plate portion 41, and outer plate portions 43 formed on both left-right sides of the pair of mesh plate portions 42. A locked portion 44 that locks with the locking piece 74 of the seat receiving member 5 is formed on the rear side of the central plate portion 41. In addition, the central plate portion 41 and the outer plate portions 43 are formed with fixing pieces 45 that are arranged across the mesh plate portion 42 and that fix a seat covering material (not shown).

[0050] As shown in Fig. 5, the seat panel 40 configured as described above has a curved receiving surface 40a that receives the load of a seated occupant. The receiving surface 40a has a curved shape that is convex downward when viewed from the front. The seat receiving member 5 supports the seat panel 40 from the back side of the receiving surface 40a. As shown in Fig. 6, the seat receiving member 5 has a main body 70A that is rectangular in plan view, and armrest mounting portions 70B that extend outward in the left-right direction from left-right side portions 70A1 of the main body 70A. The seat receiving member 5 is a strong member made of a metal material such as drawn sheet metal or aluminum die-cast, and has a saucer shape that is open at the top in the vertical direction.

[0051] Specifically, the seat receiving member 5 has a bottom wall 71 and a side wall 72 that stands upright from the peripheral edge of the bottom wall 71. An outwardly extending flange 73 is provided at the upper end of the side wall 72. The armrest 8 fits onto the armrest mounting portion 70B and is attached to the armrest mounting portion 70B by screwing the armrest mounting portion 70B into the bottom wall 71 from below. As shown in FIG. 8 , the rear side of the seat panel 40 in the front-to-rear direction is supported in a state where it is engaged with an engaging piece 74 of the seat receiving member 5, and the front side of the seat panel 40 in the front-to-rear direction is supported by the flange 73 on the front edge of the main body 70A of the seat receiving member 5.

[0052] As shown in Figure 6, a reinforcing bracket 80 and a spring member 90 are attached to the inside of the seat support member 5. A pair of reinforcing brackets 80 are attached to the bottom wall portions 71 of the left and right armrest mounting portions 70B. The reinforcing brackets 80 are formed in a box shape that covers the screw-fastening portion of the armrest 8 on the bottom wall portions 71 of the armrest mounting portions 70B. An engaging piece 81 that engages with the spring member 90 is formed on the edge of the reinforcing bracket 80 facing inward in the left-right direction. A positioning hole 82 that positions the spring member 90 is formed on the top surface of the reinforcing bracket 80.

[0053] The spring member 90 includes a pair of support portions 91 spaced apart in the left-right direction, a leaf spring portion 92 connecting the pair of support portions 91, and an attachment portion 93 provided on the outside of the pair of support portions 91 in the left-right direction. In this embodiment, the pair of support portions 91, the leaf spring portion 92, and the attachment portion 93 are integrally formed by resin molding. Note that some or all of the pair of support portions 91, the leaf spring portion 92, and the attachment portion 93 may not be integrally molded, but may be formed by combining separate parts.

[0054] The pair of support portions 91 are spring elements formed in a C-shape when viewed from the front, and are arranged so that the gap in the C-shape faces outward in the left-right direction. A through-hole 91a is formed in the pair of support portions 91, penetrating in the up-down direction. The pair of support portions 91 are arranged at positions sandwiching, in the left-right direction, a pair of protrusions 71A formed on the bottom wall portion 71 of the main body portion 70A of the seat-receiving member 5. The pair of protrusions 71A extend parallel to the front-rear direction, and increase the bending rigidity of the seat-receiving member 5 while avoiding interference with structures (adjustment mechanisms, etc.) within the support base 3 that support the seat-receiving member 5.

[0055] The leaf spring portion 92 is a flat spring element that has a thickness in the vertical direction and is formed into a rectangular shape in a plan view, and connects the pair of support portions 91. The attached portion 93 is a plate piece that bends from the lower part of the C-shaped gap between the pair of support portions 91 and extends outward in the left-right direction. An engagement hole 93a is formed in the bent portion of the attached portion 93, into which the engagement piece 81 of the reinforcing bracket 80 is inserted. A positioning pin 93b that is inserted into the positioning hole 82 of the reinforcing bracket 80 protrudes from the underside of the attached portion 93.

[0056] As shown in Fig. 9, the upper side of the armrest attachment portion 70B is covered by the seat panel 40. A vertical space is formed between the seat body 4 and the armrest attachment portion 70B to allow downward displacement of the seat body 4. In this embodiment, the armrest attachment portion 70B extends approximately horizontally in the left-right direction, while the seat panel 40 is curved upward as it extends outward in the left-right direction.

[0057] The seat panel 40 has free end portions 51 on both left and right sides that are not supported by the seat receiving member 5, and supported portions 52 that are supported by the spring members 90 of the seat receiving member 5, located inside the free end portions 51 in the left and right direction. The free end portions 51 and the supported portions 52 constitute a curved shape changing means 50 that changes the radius of curvature of the receiving surface 40a from the radius of curvature in the initial state (shape C1) to a relatively larger radius of curvature (shape C2) in accordance with the load received by the seat panel 40.

[0058] The free end portion 51 is formed by the end portions on both the left and right sides of the seat plate 40. A pair of supported portions 52 is provided corresponding to the pair of mesh plate portions 42 of the seat plate 40, and is supported by a pair of support portions 91 of the spring member 90. The supported portion 52 is formed by inserting a boss 52c formed on the rear surface 40b of the seat plate 40 into a through-hole 91a on the upper side of the support portion 91, and then fitting a washer onto the outside and screwing a tapping screw 52d into the boss 52c from the underside of the support portion 91.

[0059] Next, a description will be given of the shape change of the seat body 4 configured as described above using the load support structure.

[0060] When a seated person applies a load to the seat body 4, the free end 51 on the outer side in the left-right direction of the seat plate 40, which is not fixed to the seat receiving member 5, is elastically displaced downward in response to the load, with the supported portion 52 on the inner side in the left-right direction of the seat plate 40 as a fulcrum. When the free end 51 of the seat plate 40 is elastically displaced downward, the radius of curvature of the receiving surface 40a is changed from the radius of curvature in the initial state (shape C1) to a relatively larger radius of curvature (shape C2).

[0061] Specifically, depending on the physique of the seated person (width of the buttocks and thighs), the portion of the free end 51 that is actually pressed varies between the left and right, and this changes the amount of downward pressure of the free end 51 in the up-down direction. In other words, because the supported portion 52 serves as the fulcrum for the elastic displacement of the free end 51, the greater the distance from the supported portion 52 in the left-right direction to the free end 51, the greater the amount of downward displacement in the up-down direction. Here, the free end 51 that has been elastically displaced downward attempts to return to its initial state before elastic displacement due to the restoring force of the seat panel 40 itself. This acts as the biasing means 60, and as the free end 51 attempts to return to its initial state, the load received from the seated person and the biasing force of the biasing means 60 cancel each other out, allowing for the formation of a curved shape that provides a comfortable fit for seated people of various physiques.

[0062] Furthermore, since the supported portions 52 are provided in pairs spaced apart in the left-right direction, the outer and inner regions in the left-right direction of the pair of supported portions 52 are easily elastically deformed individually. The seat receiving member 5 includes a pair of support portions 91 that support the pair of supported portions 52, and a leaf spring portion 92 that connects the pair of support portions 91 and presses the space between the pair of supported portions 52 from the back side toward the front side when the seat plate 40 is subjected to a load.

[0063] When the seat panel 40 is subjected to a load, the leaf spring portion 92 bends upward, convex, with the connection points with the pair of support portions 91 (both ends of the leaf spring portion 92) as fulcrums. Here, the vertically elongated slits of the mesh plate portion 42 widen in the left-right direction, making it difficult for the elastic displacement of the central plate portion 41 to be hindered. As a result, the inner regions of the pair of supported portions 52 in the left-right direction (the central plate portion 41 forming the inter-support portion 53) are elastically displaced toward the front side of the receiving surface 40a by the pressure of the leaf spring portion 92, so that the curved shape of the seat panel 40 can be changed significantly even if the displacement of the free end portion 51 is small.

[0064] As described above, the load support structure of the chair 1 according to this embodiment includes the seat plate 40 having the curved receiving surface 40a that receives the load from the seated occupant, the seat receiving member 5 (load support portion) that supports the seat plate 40 from the back side of the receiving surface 40a, the curved shape changing means 50 that changes the radius of curvature of the receiving surface 40a from the initial radius of curvature (shape C1) to a relatively larger radius of curvature (shape C2) in accordance with the load received by the seat plate 40, and the biasing means 60 (seat plate 40) that returns the radius of curvature of the receiving surface 40a to the initial state. Note that the biasing means 60 includes not only the restoring force of the seat plate 40 but also the restoring force of the spring member 90.

[0065] According to this configuration, the radius of curvature of the receiving surface 40a of the seat plate 40, which receives the load from the seated occupant, is initially small, and the curved shape is changed from small to large depending on the load received by the seat plate 40. This allows for a comfortable fit for occupants of various builds, from small to large. Furthermore, when the load on the seat plate 40 is released, the biasing means 60 can return the radius of curvature of the receiving surface 40a to its initial state. Therefore, the curved shape of the seat plate 40 can be changed appropriately to accommodate occupants of various builds without manual operation.

[0066] In this embodiment, the curved shape changing means 50 includes free end portions 51 on both left and right sides of the seat panel 40 that are not supported by the seat receiving member 5, and supported portions 52 of the seat panel 40 that are supported by the seat receiving member 5 and are located inside the free end portions 51 in the left and right direction. With this configuration, the ends on both left and right sides of the seat panel 40 are free end portions 51 that are not fixed to the seat receiving member 5, and the free end portions 51 are displaced using the supported portions 52 on the inside of the left and right direction of the seat panel 40 as fulcrums, and are then urged toward their initial state by the urging means 60, thereby creating a state in which the load received from the seated occupant and the urging force of the urging means 60 cancel each other out, making it possible to form a curved shape that provides a comfortable fit for seated occupants of various physiques.

[0067] In this embodiment, the supported portions 52 are provided in pairs spaced apart in the left-right direction. With this configuration, by dividing the supported portions 52 of the seat panel 40 into two parts spaced apart in the left-right direction, the outer and inner regions of the pair of supported portions 52 in the left-right direction can easily elastically deform individually, improving the ability to conform to the physique of the seated person.

[0068] In this embodiment, the seat receiving member 5 includes a pair of supporting portions 91 that support the pair of supported portions 52, and a leaf spring portion 92 that connects the pair of supporting portions 91 and presses the space between the pair of supported portions 52 from the back side toward the front side when the seat panel 40 is subjected to a load. With this configuration, when the free ends 51 on the outer sides in the left-right direction of the pair of supported portions 52 are elastically displaced toward the back side of the receiving surface 40a, the inner regions in the left-right direction of the pair of supported portions 52 are elastically displaced toward the front side of the receiving surface 40a due to the pressure from the leaf spring portion, so that even if the displacement of the free ends 51 is small, the curved shape of the seat panel 40 can be changed significantly.

[0069] In this embodiment, the seat panel 40 forms the seat body 4. This configuration provides a seat body 4 that can provide an appropriate fit to seated occupants of various physiques.

[0070] In this embodiment, the seat panel 40 includes a pair of mesh plate portions 42 spaced apart in the left-right direction. This configuration allows the outer regions (outer plate portions 43) and inner regions (central plate portions 41 forming the support portion 53) of the pair of mesh plate portions 42 to easily deform elastically independently, improving the ability to conform to the physique of the seated person.

[0071] The chair 1 according to this embodiment includes the load-supporting structure of the seat body 4, and therefore can provide an appropriate fit to seated persons of various physiques.

[0072] As described above, according to this embodiment, the curved shape of the seat body 4 can be changed appropriately to accommodate seated occupants of various physiques without manual operation.

[0073] (Second embodiment) Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those in the above-described embodiment will be denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0074] Fig. 10 is a front view of a chair according to a second embodiment. Fig. 11 is an enlarged view of area XI shown in Fig. 10. Fig. 12 is a cross-sectional view taken along arrows XII-XII shown in Fig. 11. Fig. 13 is a cross-sectional view taken along arrows XIII-XIII shown in Fig. 11. Fig. 14 is a cross-sectional view taken along arrows XIV-XIV shown in Fig. 10. Fig. 15 is a cross-sectional view taken along arrows XV-XV shown in Fig. 10. As shown in FIG. 10, the chair 1 according to the second embodiment differs from the above-described embodiments in that the supported portion 52 of the curved shape changing means 50 is formed integrally with the backrest plate 20.

[0075] The backrest plate 20 of the second embodiment has a generally rectangular shape with rounded corners when viewed from the front as shown in Fig. 10. The backrest plate 20 includes a frame portion 21 that forms the outer shape of the backrest plate 20, a plurality of strip-shaped portions 22 separated by slits 23 inside the frame portion 21, and column-shaped portions 24 that are arranged between the left and right strip-shaped portions 22 inside the frame portion 21. The slits 23 include a first slit 23a, a second slit 23b, and a third slit 23c.

[0076] The pillar-shaped portion 24 extends in the up-down direction in the center in the left-right direction of the backrest plate 20. The first slits 23a in the second embodiment are formed on both the left and right sides of the pillar-shaped portion 24. The second slits 23b in the second embodiment extend outward in the left-right direction from the first slit 23a on the left side of the pillar-shaped portion 24, and also extend outward in the left-right direction from the first slit 23a on the right side of the pillar-shaped portion 24.

[0077] The third slits 23c of the second embodiment are bent in an L-shape from the outer left-right end of the second slits 23b, and the connection width between the frame portion 21 and the band-shaped portion 22 is narrower than the vertical width of the band-shaped portion 22. In the second embodiment, the vertical width of the band-shaped portion 22 is also narrow at the inner left-right end, and a supported portion 52 is formed integrally with the tapered tip.

[0078] The backrest support member 7 includes a first support portion 30 that extends in the vertical direction and supports the center portion of the backrest plate 20 in the left-right direction, and a second support portion 31 that extends from the upper end of the first support portion 30 to both sides in the left-right direction and supports the upper end of the backrest plate 20. The first support portion 30 is fixed to the columnar portion 24 at two points, one at the lower end and one near the upper end of the columnar portion 24, via fixing members 32 such as bolts. The second support portion 31 is fixed to the frame portion 21 of the backrest plate 20 at two points, one on the left and one on the right, of one side extending in the left-right direction at the upper end of the frame portion 21, via fixing members 32 such as bolts.

[0079] As shown in FIG. 11 , the supported portion 52 of the curved shape changing means 50 is integrally formed with the inner end of the band-shaped portion 22 in the left-right direction. The supported portion 52 has a pivot shaft 100 that is pivoted around a rotation axis extending in the vertical direction by the backrest support member 7. The backrest support member 7 has a pair of pivot portions 34 that pivotally support the pair of pivot shafts 100 that extend on both sides in the vertical direction from the supported portion 52. The pair of pivot portions 34 are formed integrally with the first support portion 30. In other words, in the second embodiment, the ball stud 52a, socket 52b, and mounting plate 33 (see FIG. 3) described in the first embodiment are not provided, and the band-shaped portion 22 is directly supported by the first support portion 30.

[0080] As shown in Figure 12, the supported portion 52 has a U-shaped cross section that is convex toward the rear in the front-rear direction. The pivot shaft 100 protrudes from the top and bottom surfaces of the supported portion 52 on both sides in the vertical direction. The pivot shaft 100 is formed in a cylindrical shape with an inclined surface 100a at the corner on the rear side in the front-rear direction of its tip, which is beveled. The pivot portion 34 has an L-shaped hook shape that engages with the front side of the pivot shaft 100 in the front-rear direction. The surface of the pivot portion 34 facing the front side in the front-rear direction is formed with an inclined surface 34a that comes into sliding contact with the inclined surface 100a of the pivot shaft 100 when the pivot shaft 100 is inserted.

[0081] The supported portion 52 has a spherical portion 101 located further back in the front-to-rear direction than the pivot shaft 100. The spherical portion 101 is separated into upper and lower portions by a slit 102. The vertical width of the slit 102 is preferably equal to or greater than the engagement allowance between the pivot shaft 100 and the pivot support portion 34. As a result, when the inclined surface 100a of the pivot shaft 100 is aligned with the inclined surface 34a of the pivot support portion 34 and the supported portion 52 is pushed in, the supported portion 52 is compressed and deformed in accordance with the vertical width of the slit 102, and the pivot shaft 100 overcomes the pivot support portion 34. Thereafter, the supported portion 52 undergoes restoration deformation, causing the pivot shaft 100 to engage with the back side of the pivot support portion 34. As shown in FIG. 11 , the slit 102 may extend to the band-shaped portion 22 to adjust the ease of elastic deformation of the supported portion 52.

[0082] The first support part 30 has a spherical receiving part 35 that faces the spherical part 101 at the rear in the front-to-rear direction when the pivot shaft 100 is engaged with the pivot part 34. As shown in Figures 12 and 13, the spherical receiving part 35 has an opposing surface 35a that faces the spherical part 101 with a small gap 110 between them. This allows the supported part 52 (band-shaped part 22) to respond not only to rotation about the pivot shaft 100 extending in the up-down direction, but also to twisting around an axis extending in the front-to-rear direction and an axis extending in the left-to-right direction.

[0083] 10, in the load support structure for the backrest 6 (load support structure for a chair) according to the second embodiment described above, the multiple band-like portions 22 include a pair of band-like portions 22 separated into left and right parts by a slit 23 at the widthwise center of the backrest plate 20, and the widthwise inner ends of each of the pair of band-like portions 22 are supported by the backrest support member 7 at the widthwise center of the backrest plate 20. With this configuration, the separation at the widthwise center of the backrest plate 20 allows the pair of left and right band-like portions 22 to elastically deform individually, making it easier to change the curved shape of the receiving surface of the backrest plate 20 starting from the widthwise center, improving the ability to conform to the physique of a seated person.

[0084] In the second embodiment, as shown in Fig. 12, the inner widthwise end of each of the pair of band-like portions 22 is provided with a pivot shaft 100 that is pivoted around a rotation axis extending in the vertical direction by the backrest support member 7. With this configuration, when a load is applied from a seated occupant to the frame portions 21 (free ends 51) on the outer widthwise sides of the pair of left and right band-like portions 22, each of the pair of band-like portions 22 rotates around the pivot shaft 100 extending in the vertical direction provided at the inner widthwise end, thereby making it easier for the backrest plate 20 to deform forward and backward in conjunction with the load input to the frame portions 21. Furthermore, by providing a small gap 110 between the spherical portion 101 and the spherical receiving portion 35, it is possible to accommodate torsion around an axis extending in the front-rear direction and an axis extending in the left-right direction.

[0085] 14, in the second embodiment, a space S1 that allows elastic deformation of the columnar portion 24 in the front-to-rear direction is formed between the columnar portion 24 of the backrest plate 20 and the first support portion 30 of the backrest support member 7. Specifically, the columnar portion 24 is provided with a spacer portion 24a that protrudes rearward at a position where it is fixed by the fixing member 32. A cylindrical counterbore with a bottom that accommodates the head of the fixing member 32 (bolt) is formed in the spacer portion 24a. The spacer portion 24a abuts against the front side of the first support portion 30 at two upper and lower fixing positions of the columnar portion 24, thereby forming the space S1.

[0086] The backrest plate 20 is configured so that the free ends 51 on both the left and right sides are flexible in the front-to-rear direction, and the fixed position with the backrest support member 7 is limited to the center in the left-to-right direction, but if there is no play in the front-to-rear direction at the center, as in the first embodiment shown in Figure 2 above, it tends to feel relatively stiff compared to the flexibility of the free ends 51 on both the left and right sides. In the second embodiment, to avoid this, play in the front-to-rear direction (space S1) is provided with respect to the first support part 30 between the fixed positions of the fixing members 32 that fix the columnar part 24 at two points, above and below.

[0087] In the second embodiment, the columnar portion 24 is plate-shaped and has a thickness in the front-rear direction. This makes the columnar portion 24 more flexible in the front-rear direction. Specifically, as shown in Fig. 10, the columnar portion 24 is a strip-shaped body extending in the up-down direction, has a width in the left-right direction, and has a thickness in the front-rear direction. The columnar portion 24 is plate-shaped in both a planar cross-sectional view and a side cross-sectional view.

[0088] 15, in the second embodiment, the front surface of the pillar portion 24 is located forward of the supported portion 52 (more specifically, the front surface of the inner end of the band portion 22 in the left-right direction). This ensures a sufficient amount of deflection of the pillar portion 24 in the front-rear direction, and also allows the pillar portion 24 to come into contact with the seated occupant before the supported portion 52 (a portion that is likely to feel hard). Note that a step occurs in the front-rear direction between the pillar portion 24 and the band portion 22, but as shown in FIG. 1, if a cushioning material and a seat covering material are attached to cover the backrest plate 20, the step will not be felt by the seated occupant.

[0089] While the preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0090] For example, the spring member 90 described in the load support structure of the seat body 4 may be applied to the load support structure of the backrest 6. That is, the curved shape changing means 50 of the backrest 6 may include the spring member 90 (plate spring portion 92) in addition to the free end portion 51 and the supported portion 52, and the biasing means 60 of the backrest 6 may include the spring member 90 (support portion 91) in addition to the backrest plate 20. Also, for example, the load support structure of the seat body 4 may not include the spring member 90, and the curved shape changing means 50 of the seat body 4 may be composed of the free end portion 51 and the supported portion 52, and the biasing means 60 of the seat body 4 may be composed of the seat plate 40. [Explanation of symbols]

[0091] 1 chair 4 Seat 5 Seat support member 6 Backrest 7 Backrest support member 20 Backrest plate 20a Receiving surface 21 Frame 22 Belt 23 Slit 40 Seat board 40a Receiving surface 41 Center plate part 42 Mesh plate 43 Outer plate part 50 Curved shape changing means 51 Free end 52 Supported part 52a ball stud 52b socket 52c Boss 52d tapping screw 53 Support area 60 Actuation means 91 Support part 92 Leaf spring part 100 Pivot

Claims

1. a receiving surface component having a curved receiving surface that receives a load from a seated person; a load support portion that supports the receiving surface constituent portion from the back side of the receiving surface; a curved shape changing means for changing the radius of curvature of the receiving surface from the radius of curvature in an initial state to a relatively larger radius of curvature in accordance with the load received by the receiving surface constituent portion; and a biasing means for returning the radius of curvature of the receiving surface to its initial state, The curved shape changing means is Free end portions on both sides in the width direction of the receiving surface constituent portion that are not supported by the load supporting portion; a supported portion of the receiving surface constituent portion supported by the load supporting portion, the supported portion being located on the inner side of the free end portion in the width direction, The supported portions are provided in pairs spaced apart in the width direction, The load support portion is a pair of supporting portions that support the pair of supported portions; A load support structure for a chair, comprising: a leaf spring portion that connects the pair of supporting portions and presses the space between the pair of supported portions from the back side toward the front side in response to the load received by the receiving surface component.

2. 2. The load-bearing structure of claim 1, wherein the support structure forms a backrest plate.

3. The backrest plate is A frame portion that forms the outer shape of the backrest plate; 3. The load-bearing structure of claim 2, further comprising a plurality of strips separated by slits inside the frame.

4. A receiving surface component having a curved receiving surface that receives a load from a seated person; a load support portion that supports the receiving surface constituent portion from the back side of the receiving surface; a curved shape changing means for changing the radius of curvature of the receiving surface from the radius of curvature in an initial state to a relatively larger radius of curvature in accordance with the load received by the receiving surface constituent portion; and a biasing means for returning the radius of curvature of the receiving surface to its initial state, The receiving surface component forms a backrest plate, The backrest plate is A frame portion that forms the upper edge, lower edge, and side edge of the backrest plate and forms the outer shape of the backrest plate; A load-bearing structure for a chair, comprising: a plurality of strips separated by slits inside the frame portion.

5. A load-supporting structure for a chair as described in Claim 4, wherein the outer ends of the multiple band-shaped portions are connected to the frame portion.

6. The plurality of band-shaped portions include a pair of band-shaped portions separated into left and right sides by the slit at the widthwise center portion of the backrest plate, 6. A load support structure for a chair according to claim 3, wherein the widthwise inner ends of the pair of belt-shaped portions are supported by the load support portion at the widthwise center of the backrest plate.

7. A receiving surface component having a curved receiving surface that receives a load from a seated person; a load support portion that supports the receiving surface constituent portion from the back side of the receiving surface; a curved shape changing means for changing the radius of curvature of the receiving surface from the radius of curvature in an initial state to a relatively larger radius of curvature in accordance with the load received by the receiving surface constituent portion; and a biasing means for returning the radius of curvature of the receiving surface to its initial state, The receiving surface component forms a backrest plate, The backrest plate is A frame portion that forms the outer shape of the backrest plate; a plurality of strip-shaped portions separated by slits inside the frame portion, The plurality of band-shaped portions include a pair of band-shaped portions separated into left and right sides by the slit at the widthwise center portion of the backrest plate, A load support structure for a chair, wherein the widthwise inner ends of each of the pair of band-shaped portions are supported by the load support portion at the widthwise center of the backrest plate.

8. 8. The load support structure for a chair according to claim 6, wherein the widthwise inner ends of the pair of band-shaped portions are provided with a pivot shaft that is pivotally supported by the load support portion around a rotation axis that extends in the vertical direction.

9. The load-supporting structure for a chair according to any one of claims 1 to 8, wherein the receiving surface constituent portion forms a seat plate.

10. 10. The load-supporting structure for a chair according to claim 9, wherein the seat plate comprises a pair of mesh plate portions formed to be spaced apart in the width direction.

11. A chair comprising a load-bearing structure according to any one of claims 1 to 10.

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