Shock-Absorbing Structure and Floor Material

The contents of the following patent application(s) are incorporated herein by reference:

The present invention relates to a shock-absorbing structure for mitigating impact and a floor material including the shock-absorbing structure.

Cushioning materials are known which are provided under the floor surface for absorbing an impact of falling over of elderly people or the like in order to prevent injury such as a fracture of the femur (especially trochanter) when they fall over during walking on the floor surface. For example, Patent Document 1 discloses a floor material that includes a foam layer molded using a foam material such as polyurethane. Such a foam layer has an elastic modulus that increases linearly against an applied load. Hence, when the elastic modulus is set to be high (to cause a small displacement, i.e. firm) against a small load applied during walking, the stability during walking will be maintained, although the large impact upon falling over cannot be absorbed, leading to a fracture. Conversely, when the elastic modulus is set to be low (to cause large displacement, i.e. soft) to absorb the large impact upon falling over, it is displaced softly even against a small load during walking, causing difficulty in walking. Accordingly, a floor material such as those disclosed in Patent Document 2 is needed that allows the elastic modulus to be high (i.e. firm) against a small load applied during walking, while allowing the elastic modulus to be low (i.e. soft) against a large impact upon falling over.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all of the combinations of features described in the embodiments are essential to the solving means of the invention.

In an embodiment of the present invention, a size of a member may be described using “approximately”. Note that this means the size is accurate at least in significant figures (significant digits) and includes an inaccuracy in the extent of non-significant figures. For example, approximately 1 mm includes an inaccuracy in the extent of 0.1 mm.

shows an overall structure of the shock-absorbing structureaccording to the present embodiment in a perspective view. Here, a thickness direction of the shock-absorbing structureis defined as a Z-axis direction and directions orthogonal to each other in a plane that is orthogonal to the Z-axis direction are defined as an X-axis direction and a Y-axis direction. As an example, the shock-absorbing structureconstitutes a floor material that supports a floor surface on a subfloor S (seeand the like) and mitigates impact applied to the floor surface. Here, the subfloor S may be one that includes a walking surface on which a person walks, such as a plane of a floor slab (concrete slab) in a reinforced concrete building, a surface on which flooring or the like is installed, a floorboard in a wooden building, or ground. Particularly, the shock-absorbing structureis a structure that is firm against small loads during walking to allow stable walking, while being soft against large impacts upon falling over to allow the impact to be absorbed to prevent fractures.

The shock-absorbing structureis configured by arraying a plurality of unit structures, each having a thickness in the Z-axis direction, in line in the X-axis direction or in the Y-axis direction or in a matrix-like manner in the XY direction, by joining the overhang portionsof the top platesintegrally with each other. Note that, although the shock-absorbing structureaccording to the present embodiment is constituted by nine unit structuresin total that are arrayed three by three in the X-axis direction and the Y-axis direction, the number of unit structuresthat are arrayed in each of the X-axis direction and the Y-axis direction can be arbitrarily determined, and thus the length of the shock-absorbing structurein each of the X-axis direction and the Y-axis direction can also be determined arbitrarily.

toshow the structures of the unit structuresconstituting the shock-absorbing structure. The unit structureis a minimal constitutional unit that constitutes the shock-absorbing structure. Here,shows an overall structure of the unit structurein a perspective view,shows an internal structure of the unit structure, partially omitted in a perspective view,shows a structure of the unit structurein a top view,shows the structure of the unit structurein a bottom view, andshows the structure of the unit structurein a side view. The unit structureincludes a top plateand legs.

The top plateis a member that includes an upper surface to receive a load. In the present embodiment, the top platehas a rectangular shape (particularly a square shape). Note that, the shape of the top platemay be, for example, hexagonal or other polygonal shapes, as long as it is suitable to array the plurality of unit structuresin one axis direction or two axis directions. When the unit structureis rectangular or hexagonal, it can be densely arrayed.

The size of the top plateis determined to be sufficiently smaller than an area to which a load is applied when a person (including not only an adult but also a child) walks on the floor surface, i.e. the area of one's sole abutting the floor surface during walking or the area of one's knee that strikes against the floor surface when falling over. In the present embodiment, the length Wof one side of the top plateis defined to be approximately 15 mm, as an example. Accordingly, even when not only an adult but also a child falls over on the floor surface, the load applied to the floor surface can be absorbed by the plurality of unit structuresto prevent injuries such as fractures.

Note that, as will be described below, the shape of the top platemay not be limited to the plate shape extending throughout a plane but may have a frame shape with an openingat the center, as long as the top platecan receive the load applied to the unit structurevia the surface materialand the like, because the top platesupports a surface materialand the like that forms the floor surface on the shock-absorbing structure. The shape of the openingmay be circular (oval may also be possible), rectangular (including square), hexagonal, or other polygonal shapes. The top platehaving a plate shape has somewhat high rigidity and the legsare difficult to tilt relative to the top platewhile the top platehaving a frame shape has moderately low rigidity and the legstilt easily to buckle relative to the top plate, thus allowing itself to become soft against the large impact upon falling over to absorb the impact.

shows the shock-absorbing structuresin a stacked state. By the top platesincluding the openingsthe legsof a plurality of unit structuresincluded in the shock-absorbing structurecan each be inserted between the legsof a plurality of unit structuresincluded in another shock-absorbing structurethrough the openingsof the top plates, and the legsof the plurality of unit structuresincluded in another shock-absorbing structurecan each be further inserted between the legsof a plurality of unit structuresincluded in still another shock-absorbing structurethrough the openingsof the top plates, thus allowing the plurality of shock-absorbing structuresto be stacked with a small thickness.

In the present embodiment, the top platehas a rectangular (particularly square) frame body including a rectangular openingat the center. The top plateincludes an overhang portionthat overhangs toward the outside (in ±X direction and ±Y direction) from a location to which the legsare connected as described below, that is, in the case of the present example, from an inner edge portion which sections the openingThe width Wof the overhang portion(see) may be almost the same as or more than the width of the inner edge portion to which the legsare connected. As an example, in the present embodiment, the width of the inner edge portion is defined to be approximately 1 mm, which is almost equal to the thickness dof the leg, and the width of the overhang portionis defined to be approximately 1 mm. That is, the frame width Wof the top plateis defined to be approximately 2 mm. Accordingly, a large support surface is obtained and the upper surface layeror the like can be stably supported.

In addition, the thickness dof the overhang portion(see) may be defined to be equal to or smaller than the thickness dof the leg. In the present embodiment, it is defined to be 1 mm, which is almost equal to the thickness dof the leg. Accordingly, due to the relatively small thickness of the overhang portionthe rigidity of the top platebecomes moderately low and the legseasily tilt to buckle relative to the top plate, thus allowing the deformation stroke by which the top plateis displaced in the Z-axis direction to be larger.

shows the shock-absorbing structurein a wound state. As described above, the shock-absorbing structureis integrally configured by joining the overhang portionswith each other from the plurality of unit structures. The top platehas a low rigidity at a location where overhang portionsare joined with each other between the adjacent unit structures. Hence, by arraying the unit structuresin a matrix-like manner, the shock-absorbing structurecan be flexed at the joint location and easily wound up in the array direction of the unit structure. At this time, the shock-absorbing structurecan be wound up in a small thickness by inserting the legsof the unit structureinto the openingsof the top platesof another unit structure.

The legis a member that extends in −Z direction from the lower surface of the top plateand supports the top plateon the subfloor S. At least one legis provided in each of the top platesof the plurality of unit structuresconstituting the shock-absorbing structure, preferably a plurality of legsare provided in each top plate, and particularly the plurality of legsare arranged along the circumference of each top plate. Note that, when the top platehas a polygonal shape, the legsare each arranged near one of a plurality of corners and when the top platehas a circular shape, the legsare each arranged at at least three or more locations at an arbitrary interval. Accordingly, the top platecan be stably supported since a load is distributed among the plurality of legswhen the load is applied to the top plate.

The height Hof the legcan be determined according to the deformation stroke required to absorb a load in one unit structure. In the present embodiment, the height Hof the legis defined to be approximately 9 mm, as an example.

Each legis tilted toward the center of the top plate(or the unit structure) relative to the lower surface of the top plate. In the side view associated with the X-axis direction (see), the tilt angle θof the legrelative to the Z-axis is 6 to 13 degrees, preferably 8 to 11 degrees, more preferably approximately 9.5 degrees. The same applies to the tilt angle of the legin the side view associated with the Y-axis direction. Accordingly, the legeasily buckles toward the center of the top plate.

Note that, the legmay be perpendicular to the lower surface of the top plateas long as it buckles when a large impact upon falling over is applied. In addition, the legmay be tilted toward the outside of the top plate. In such a case, the tilt angle of the legmay be the same as the tilt angle when it is tilted toward the center of the top plate.

Each leghas a cross-sectional shape flexed convexly toward one side in the X-Y plane. The legmay be convexly curved toward one side and is preferably convexly bent toward one side. Accordingly, a shift between deformation modes of the legwhen the load is applied to the leg, i.e. a shift from a contraction mode to a buckling mode or a shift from the buckling mode to the contraction mode, becomes more obvious. That is, a characteristic shift becomes more obvious in which the legremains firm until the load exceeds the threshold strength and becomes soft once the load exceeds the threshold strength. Here, a threshold load at which the deformation mode shifts is adjusted by selecting the thickness dof the leg(see). In the present example, the thickness dis defined to be approximately 1 mm as an example.

Since the top plateof the present embodiment has a rectangular shape, the four legsare each arranged near one of the four corners of the top platewith their convexly-flexed outside surface facing outwardly in a radial direction having a reference point at the center of the unit structure(or of the top plate) in the top view. In other words, the legarranged near an −X, −Y corner of the top plateis bent outwardly from the center of the top plate, i.e. bent convexly at 90 degrees in an −X, −Y direction (in an L-shaped manner from the −X direction to the +Y direction), and is joined at its upper end to the lower surface of the −X, −Y corner of the top platewith its inside surface flush with the interior surface of the −X, −Y corner of the top plate. In addition, the legarranged near an −X, +Y corner of the top plateis bent outwardly from the center of the top plate, i.e. bent convexly at 90 degrees in an −X, +Y direction (in an L-shaped manner from the +Y direction to the +X direction), and is joined at its upper end to the lower surface of the −X, +Y corner of the top platewith its inside surface flush with the interior surface of the −X, +Y corner of the top plate. In addition, the legarranged near an +X, +Y corner of the top plateis bent outwardly from the center of the top plate, i.e. bent convexly at 90 degrees in an +X, +Y direction (in an L-shaped manner from the +X direction to the −Y direction), and is joined at its upper end to the lower surface of the +X, +Y corner of the top platewith its inside surface flush with the interior surface of the +X, +Y corner of the top plate. In addition, the legarranged near an +X, −Y corner of the top plateis bent outwardly from the center of the top plate, i.e. bent convexly atdegrees in an +X, −Y direction (in an L-shaped manner from the −Y direction to the −X direction), and is joined at its upper end to the lower surface of the +X, −Y corner of the top platewith its inside surface flush with the interior surface of the +X, −Y corner of the top plate. Accordingly, the top plateis supported by the plurality of (four in the present example) legs, arranged along its circumference, and the legscan be prevented from spreading toward the outside and interfering with the legsof adjacent unit structuresby buckling toward the inside in the radial direction when the load equal to or more than the threshold load is applied to the top plate.

The legincludes a leading end that has a similar shape to the convexly-flexed cross-sectional shape as described above. That is, no end surface is provided which is parallel to the X-Y plane that connects the insides of the leading ends flexed at 90 degrees at each of the legs, no bottom surface is provided which is parallel to the X-Y plane that connects the leading ends of four legs, but a spaceis formed which is open in the Z-axis direction among the leading ends of the four legs. Accordingly, the four legsdeform to spread respective body portions (the middle associated with the Z-axis direction) to equal to or more than 90 degrees in the X-Y plane (provision of the end surface or the bottom surface would increase the rigidity and cause difficulty in spreading), and then buckle entirely toward the center of the top plate, thus allowing the top plateto be largely displaced in the Z-axis direction. In addition, since the unit structurehas a through hole in the Z-axis direction, air is allowed to pass through easily.

With such a shape of the leg, despite the small volume of the member occupying the space, the rigidity of the legcan be maintained until it buckles, while deformation stroke associated with the Z-axis direction can also be increased as much as possible due to the reduced volume of the member.

Each leghas a concave portionformed on at least part of the corner on the outside in the radial direction having a reference point at the center of the unit structure(or of the top plate) in the top view. Accordingly, bending of each legstarting from the concave portiontoward the inside in the radial direction can be induced when the load equal to or more than the threshold load is applied to the top plateof the unit structure.

The concave portionis located in the middle of the legassociated with the Z-axis direction. Particularly, the concave portionis formed to have a wedge shape with the deepest portion at the middle of the leg, in a region spanning from the base end (i.e. the upper end that is connected to the lower surface of the top plate) to the leading end (i.e. the lower end) of the leg. The maximum width Wof the concave portion(see) is defined to be approximately 1 mm, as an example. Accordingly, the upper edge and the lower edge of the concave portionare prevented from interfering with each other and the bending angle, i.e. the deformation stroke of the legassociated with the Z-axis direction, is not restricted when the legis bent, allowing buckling thereof in its entirety to maximize the deformation stroke. Note that, the concave portionmay be formed into a concave-surface shape. In addition, a plurality of concave portionsmay be arranged side by side in the Z-axis direction.

Two adjacent legsamong the plurality of legsform a gaptherebetween. The gapis the smallest on the upper-end side of the two legsand the minimum width wis defined to be approximately 2 mm, as an example. Note that, the adjacent legsof the plurality of legsmay be joined with each other at their upper ends. In such a case, the minimum width Wof the gapis determined at a position immediately below the joint location. Accordingly, when the plurality of legsbuckle, the air inside the unit structureeasily flows through the gapto the outside, and an air-damping effect is decreased moderately to cause the legto buckle easily.

Moreover, the shape of the side surface of the legis determined to make the gapbetween the two adjacent legsbecome wider from the lower surface of the top plate(or the joint location of the two adjacent legs) in the −Z direction. In the side view in the X-axis direction, an angle ϕof the side surface of the legrelative to the Z-axis (see) is 3 to 10 degrees, preferably 5 to 8 degrees, more preferably approximately 6.3 degrees. Accordingly, the gapbecomes wider from the lower surface of the top plateor the joint location to the lower end, in a range of, for example, approximately 2 to approximately 4 mm. Note that, the length W(see) of one side of the legis approximately 4 mm. Accordingly, the deformation stroke of the top plateassociated with the Z-axis direction can be restricted by the two adjacent legsinterfering with each other when they buckle when the load equal to or more than the threshold load is applied to the top plate.

shows a structure of the sliding ribof the unit structure. The sliding ribis provided on an outermost unit structureof the plurality of unit structuresconstituting the shock-absorbing structure, and is formed to extend from the overhang portionof the top platein the −Z direction on the outside surface of the legand to be tilted toward the outside surface of the leg. Accordingly, an end surfacethat extends from the side surface of the overhang portionin the −Z direction is formed, and an inclined surfacewhich is connected to the outside surface of the legis formed thereunder. Note that, the width wof the sliding ribis defined, for example, to be approximately 1 mm.

toshow a function of the sliding rib. When two shock-absorbing structuresare to be arranged side by side on the subfloor S, the end (i.e. overhang portion) of the outermost unit structureof the shock-absorbing structureon the right-hand side may be lifted onto the end (i.e. the overhang portion) of the shock-absorbing structureon the left-hand side as shown in. At this time, the inclined surfaceof the sliding ribof the unit structureon the right-hand side is lifted onto the overhang portionof the unit structureon the left-hand side.

Hence, a load is applied downwardly on the top plateof the unit structureon the right-hand side (in the direction of an outlined arrow). Accordingly, an end of the overhang portionof the unit structureon the left-hand side slides over the inclined surfaceof the sliding ribof the unit structureon the right-hand side, and the unit structureon the right-hand side is pushed downwardly while being shifted to the right-hand side as represented by a black-colored arrow.

Accordingly, as shown in, the unit structureon the right-hand side is positioned relative to the unit structureon the left-hand side in the left and right direction, and the end surfaceof the sliding ribof the unit structureon the right-hand side is in surface contact with the end surfaceof the sliding ribof the unit structureon the left-hand side. Moreover, the load is applied downwardly on the top plateof the unit structureon the right-hand side (in the direction of an outlined arrow). Accordingly, the end surfaceof the sliding ribof the unit structureon the right-hand side slides over the end surfaceof the sliding ribof the unit structureon the left-hand side, and the unit structureon the right-hand side is pushed further downwardly as represented by a black-colored arrow.

Finally, as shown in, the unit structure(i.e. the shock-absorbing structure) on the right-hand side is arranged side by side with the shock-absorbing structureon the left-hand side on the subfloor S. In this manner, by utilizing the end surfaceand the inclined surfaceof the plurality of shock-absorbing structures(unit structures), it is possible to position the plurality of shock-absorbing structuresin the lateral direction and to array them on the subfloor S so that their upper surfaces of the top platesare flush with each other.

andshow a structure of a reinforcement ribof the shock-absorbing structurein a side view and a bottom view, respectively. The reinforcement ribmay be provided between two adjacent unit structuresof the plurality of unit structuresconstituting the shock-absorbing structure. The reinforcement ribis formed to join the lower surfaces of overhang portionsby which two adjacent unit structuresare joined and the outside surfaces of the legsof the two unit structuresthat face each other across the overhang portionsin a bottom view. The width dand the height hof the reinforcement ribare defined to be approximately 1 mm and approximately 2 mm, respectively as an example. By providing the reinforcement ribbetween the top plateand the leg, the rigidity of the legcan be adjusted.

Note that, the reinforcement ribmay be provided between the outside surfaces of the legsfacing each other in all the unit structures, or alternatively, it may only be provided between the outside surfaces of the legsfacing each other in some of the unit structures.

In order to join the adjacent shock-absorbing structureswith each other when arraying the plurality of shock-absorbing structureson the subfloor S, a joint structure may be provided on the outermost unit structureof the plurality of unit structuresconstituting the shock-absorbing structure. Multiple joint structures may be provided in one shock-absorbing structure.

andshow the joint structure of the shock-absorbing structure(unit structure) in a perspective view and a side view, respectively. The joint structure includes a claw portionprovided on one of the adjacent shock-absorbing structures(unit structures) and a claw-reception portionprovided on another of the shock-absorbing structures(unit structures). Here, the joint structure is exemplified that joins the +Y end of the outermost unit structureof one of the shock-absorbing structuresand the −Y end of the outermost unit structureof another of the shock-absorbing structures, although the joint structure can be provided on an outer edge (+X edge, −X edge, +Y edge, or −Y edge) of any outermost unit structureof the two shock-absorbing structures.

The claw portionis a member that engages with the claw-reception portionformed on the top plateof the unit structureThe claw portionextends, in the +Y direction, from the top plateand the upper-end side of the outside surface on the +Y side of the legon the +X, +Y side of the unit structureand includes a grooved portionextending in the X-axis direction formed on the lower surface near the leading end and a grooved portionextending in the X-axis direction formed at the base end side on the upper surface, forming an S-shape in the side view. Note that, the claw portionmay be formed between the top plateand the legon the −X, +Y side of the unit structure

The claw-reception portionis a member that are engaged with the claw portionformed on the top plateof the unit structureThe claw-reception portionis provided on the +X, −Y side of the unit structureinstead of the leg, and includes a step portiona block bodyand engagement blocksThe step portionis formed to protrude toward the −X side from the inner edge of the top plateon the +X side. The block bodyis formed to extend out toward the +Y side from the inner edge of the top plateon the −Y side. The engagement blockis formed integrally with a part of the top plateon the −Y, +Z side between the step portionand the block bodyso as to connect them. The engagement blockis formed on the +Y, −Z side between the step portionand the block bodyso as to connect them. By the presence of the engagement blocksan S-shaped spaceis formed between the step portionand the block bodyin a side view associated with the X-axis direction.

andshow a state in which two shock-absorbing structures(two unit structures) are joined by the joint structure in a perspective view and a side view, respectively. First, the claw portionof the unit structureis inserted into the spacein the claw-reception portionof the unit structurefrom below the engagement blockto above the engagement blockThen, the engagement blockof the claw-reception portionis fitted into the grooved portionof the claw portion, and the engagement blockof the claw-reception portionis fitted into the grooved portionof the claw portion. Then, the overhang portionon the +Y side of the top plateof the unit structureand the overhang portionon the −Y side of the top plateof the unit structureare abutted with each other, and the two unit structuresare arranged side-by-side so that their top platesare flush with each other. Accordingly, the two unit structuresi.e. two shock-absorbing structuresare joined.

Note that, one of the shock-absorbing structuresmay include the unit structureprovided with the claw-reception portionin addition to the unit structureprovided with the claw portion. In addition, another of the shock-absorbing structuresmay include the unit structureprovided with the claw portionin addition to the unit structureprovided with the claw-reception portion. That is, the shock-absorbing structuremay include one or more unit structuresprovided with the claw portionand one or more unit structuresprovided with the claw-reception portion.

toshow a shock-absorbing principle of the shock-absorbing structure(unit structure). Note that, one unit structureof the plurality of unit structuresconstituting the shock-absorbing structureis exemplified. An upper section and a lower section ofshow the unit structurein the unloaded state in a top view and a side view, respectively. The unit structureis installed on the subfloor S. The top plateof the unit structureis supported at its height H(see) by the four legs.

An upper section and a lower section ofshow the unit structurein the contracted state in a top view and a side view, respectively. A load is applied downwardly (in the direction of an outlined arrow) from the upper surface side of the top plate. However, the load is smaller than a predetermined threshold load. In such a case, the four legssupporting the top platecontract to some extent in the Z-axis direction and cause the top plateto be lowered to some extent downwardly (in the direction of a black-colored arrow) to absorb the load.

An upper section and a lower section ofshow the unit structurein the buckled state in a top view and a side view, respectively. It is assumed that the load (the white-colored arrow) applied to the top platehas increased to exceed the threshold load. In such a case, the four legssupporting the top platebend (i.e. buckle) toward the inside of the unit structure(in the direction of a small black-colored arrow) and are displaced largely in the Z-axis direction while spreading their convexly-flexed cross-sectional surfaces in the X-Y plane, thus causing the top plateto be largely lowered downwardly (in the direction of a large black-colored arrow).

An upper section and a lower section ofshow the unit structurein the collapsed state in a top view and a side view, respectively. It is assumed that the load (the white-colored arrow) applied to the top platehas further increased. The four legssupporting the top platecause the top plateto be further lowered downwardly (in the direction of a large black-colored arrow) to absorb the load by completely spreading their convexly-flexed cross-sectional surfaces in the X-Y plane, further bending toward the inside of the unit structure(in the direction of a small black-colored arrow) to be soft, and abutting the upper side and the lower side of the outside surface to contract in the Z-axis direction.

In this manner, the shock-absorbing structure(the unit structure) is firm against small load applied during walking which is smaller than the threshold load, providing stability during walking, and is soft against large impact upon falling over which is equal to or more than the threshold load, allowing large displacement to absorb the impact.

shows a cross-sectional structure of a floor materialincluding the shock-absorbing structureaccording to the present embodiment. The floor materialinclude a surface material, an intermediate material, and the shock-absorbing structure.

The surface materialis a layer material that includes an upper surface which forms the floor surface (i.e. a surface for walking). The surface materialmay be made of a hard material such as wood, plywood, stone, sheet-vinyl floor made of vinyl chloride, tile, carpet, cork, continuous sheet or the like, so as to be provided with walkability. Note that, the surface materialmay be integrally configured with the intermediate material.

The intermediate materialis a layer material that is arranged between the surface materialand the shock-absorbing structureto flatten surface irregularities on the upper surface of the shock-absorbing structurearrayed on the subfloor S. As the intermediate material, a foam layer may be adopted that is molded using foam materials such as polyurethane, as an example. The intermediate materialis arranged to cover at least two shock-absorbing structures. Accordingly, the load locally applied to the surface materialis distributed among the plurality of shock-absorbing structures.

The multiple shock-absorbing structuresare arrayed on the subfloor S and support the surface materialand the intermediate material. The shock-absorbing structureis configured as described above, and absorbs the load applied via the surface material.

The shock-absorbing structureaccording to the present embodiment can be manufactured by an injection molding method. Here, the top plateand the legsare integrally molded. The shock-absorbing structureis formed from an elastic material such as NR rubber or thermoplastic elastomer so that the buckled legsare restored and stand upright when they are released from the load. Accordingly, the legshave rubber hardness of 10 to 100, preferably 50 to 80.