SHEAR CUSHION WITH INTERCONNECTED COLUMNS OF CUSHIONING ELEMENTS

BACKGROUND

When seated on a cushion, vibrations and other forces may cause horizontal movement of an occupant of the cushion. This horizontal movement causes shear forces at the interface between the occupant and the seat cushion, which are absorbed by the cushion and/or the body tissue of the occupant. These interface shear forces can cause the occupant discomfort, irritation, fatigue, and in extreme cases, pressure ulcer development.

SUMMARY

Implementations described herein address at least one of the foregoing problems by providing a shear cushion comprising a first column of two or more interconnected cushioning elements; a second column of two or more additional interconnected cushioning elements, wherein the first column is oriented substantially parallel and adjacent to the second column; and a first binding layer elastically connecting the first column to the second column, wherein the first column and the second column are both extend in a direction substantially normal to the first binding layer.

Implementations described herein address at least one of the foregoing problems by further providing a method of using a shear cushion to reduce peak shear force on an occupant of the shear cushion comprising tilting a first column of two or more interconnected cushioning elements and a second column of two or more additional interconnected cushioning elements in a direction of a shear force applied to the shear cushion, wherein the first column is elastically connected to the second column with a first binding layer, and wherein the first column is oriented substantially parallel to the second column.

Implementations described herein address at least one of the foregoing problems by still further providing a shear cushion comprising a first column of two or more interconnected cushioning elements; a second column of two or more additional interconnected cushioning elements; a third column of two or more additional interconnected cushioning elements; a fourth column of two or more additional interconnected cushioning elements; wherein each of the first column, the second column, the third column, and the fourth column are oriented substantially parallel; a first binding layer elastically connecting the first column, the second column, the third column, and the fourth column at first interfaces between adjacent cushioning elements in each of the first column, the second column, the third column, and the fourth column; and a second binding layer elastically connecting the first column, the second column, the third column, and the fourth column at second interfaces between adjacent cushioning elements in each of the first column, the second column, the third column, and the fourth column, wherein the second binding layer is offset from and oriented substantially parallel to the first binding layer, and wherein the first column, the second column, the third column, and the fourth column are all oriented substantially normal to the first binding layer and the second binding layer.

Further implementations are apparent from the description below.

BRIEF DESCRIPTIONS OF THE DRAWINGS

A further understanding of the nature and advantages of the present technology may be realized by reference to the figures, which are described in the remaining portion of the specification.

FIG. 1A is a side elevation view of an occupant seated on an example shear cushion prior to application of a lateral force.

FIG. 1B illustrates the occupant seated on the example shear cushion of FIG. 1A subjected to a braking lateral force.

FIG. 1C illustrates the occupant seated on the example shear cushion of FIG. 1A subjected to an accelerating lateral force.

FIG. 2A is a rear elevation view of an occupant seated on an example shear cushion prior to application of a lateral force.

FIG. 2B illustrates the occupant seated on the example shear cushion of FIG. 2A subjected to a left-turning lateral force.

FIG. 2C illustrates the occupant seated on the example shear cushion of FIG. 2A subjected to a right-turning lateral force.

FIG. 3 is a perspective view of an example shear cushion.

FIG. 4 is a side elevation view of an example two-layer shear cushion subjected to a shear force.

FIG. 5 is a side elevation view of an example four-layer shear cushion subjected to a shear force.

FIG. 6 is a side elevation view of an example six-layer shear cushion subjected to a shear force.

FIG. 7 is a graph illustrating peak shear force over time of an example shear cushion.

FIG. 8 is a perspective view of an example shear cushion with offset cushioning layers.

FIG. 9 is a side elevation schematic of an example shear cushion.

FIG. 10 is a side elevation schematic of an example shear cushion subjected to a lateral force.

FIG. 11 is a top plan view of an example shear cushion 1102 with directional cushioning elements and non-directional cushioning elements.

FIG. 12 is a side elevation view of an example four-layer shear cushion with columns of progressively changing cushioning elements.

FIG. 13 illustrates example operations for using a shear cushion to reduce peak shear force on an occupant of the shear cushion.

DETAILED DESCRIPTION

Many cushions are designed to absorb compression (or normal) forces (i.e., forces substantially perpendicular (i.e., with less than a 5 degree variation or less than a 1 degree variation) to an user interface plane of a cushion) created when an occupant sits on or otherwise interfaces with a cushion. Often, these compression forces are a result of gravitational forces on the occupant. However, these cushions are not designed to reduce or prevent shear forces (i.e., forces substantially parallel (i.e., with less than a 5 degree variation or less than a 1 degree variation) to the user interface plane of the cushion) between the occupant and the cushion, which can occur when the seated occupant slides horizontally across a top of the cushion. Often, these shear forces are a result of inertial forces on the occupant when a directional change of motion occurs. Such shear forces can be uncomfortable and potentially physically harmful to the occupant. For example, motorcycle saddles may be subjected to intense lateral vibrations and/or inertial forces that can cause irritation, particularly when the occupant turns the motorcycle and is caused to shift or slide laterally with respect to the saddle. This rubbing of body tissue against the motorcycle seat can cause irritation and injury. Similarly, other saddles and seats associated with moving vehicles (e.g., car seats, aircraft seats, motorboat seats, horse saddles, pedal bike saddles, and wheel chair seats) may similarly inadequately protect the occupant from shear forces. Inadequate protection from shear forces can cause rubbing, bruising, irritation, fatigue, and can contribute to the formation of pressure ulcers on an occupant.

Peak shear forces decrease dramatically if a top portion of the cushion elastically moves with an occupant while a bottom portion of the cushion remains fixed. Therefore, allowing the top portion of the cushion to move laterally along with the occupant is an effective way of reducing or eliminating shearing between the occupant and the cushion. Accordingly, the stacked opposed void cushions disclosed herein may provide both a normal pressure distribution (e.g., a pressure distribution oriented substantially normal to the interface surface between the occupant and the cushion) and reduction of peak shear forces between the occupant and the cushion. In one implementation, the normal pressure distribution may be tuned separately from peak shear force reduction. In another implementation, peak shear force reduction may itself be directionally tuned so as to provide for different magnitudes of shear reduction or elimination in different directions.

FIG. 1A is a side elevation view of an occupant 100 seated on an example shear cushion 102 prior to application of a lateral or shear force. The cushion 102 may be a component cushion of any seat or saddle of a moving or movable (but currently stationary) vehicle (not shown). Further, while the occupant 100 is depicted using the cushion 102 in a sitting position, the presently disclosed technology could also apply to cushion the occupant 100 oriented in another position. For example, the cushion 102 could support the occupant 100 in a prone, supine, or a combination lying/sitting position with a similar effect as described herein. Further, the cushion 102 may provide the occupant 100 support in areas other than the user's posterior (e.g., the cushion 102 could be used to support the occupant's torso, legs, shoulders, head, etc.).

A gravitational (or normal) force is oriented downward as illustrated by arrow 104 pushing the occupant 100 against the cushion 102, which pushes back against the occupant 100 with an equal and opposing force, as illustrated by arrow 106. No lateral load is depicted in FIG. 1A and the cushion 102 merely provides support in a direction generally normal to an interface surface 108 of the cushion 102 with the occupant 100.

FIG. 1B illustrates the occupant 100 seated on the example shear cushion 102 of FIG. 1A subjected to a braking lateral force illustrated by arrow 110. FIG. 1B assumes that the occupant 100 is in motion in the vehicle. Although, in other implementations, a similar effect would occur when the user is accelerated rearward when the vehicle is stationary. The braking lateral force is created due to an inertial force of the moving occupant 100 resisting braking or deceleration of the vehicle, which is oriented in the opposite direction of the braking lateral force illustrated by the arrow 110. Further, in various implementations, the braking lateral force and corresponding inertial force is in addition to and independent of the gravitational (or normal) force and corresponding equal and opposite force depicted in FIG. 1A.

A shear force illustrated by arrow 112 allows the occupant 100 to remain fixed to the cushion 102 even though the inertial force is acting on the occupant 100. Shear force is defined as a force parallel to the interface surface 108 between the occupant 100 and the cushion 102. Shear stress is the shear force per unit of shear area at the interface surface 108 (e.g., the area of the occupant's body in contact with the cushion 102). Shearing movement is any movement that overcomes frictional forces that causes the occupant 100 to move across the interface surface 108 of the cushion 102. The shear cushion 102 is adapted to reduce peak shear force and peak shear stress and reduce or eliminate any shearing movement between the occupant 100 and the cushion 102.

If a conventional cushion were used, an equal and opposing shear force would immediately be applied to the occupant to resist the braking lateral force. When the shear cushion 102 is used, a top portion of the cushion 102 moves laterally with the occupant 100, reducing the opposing shear force/stress magnitude so long as the shear cushion 102 moves laterally with the occupant 100. If the braking lateral force is relatively short in duration compared with the time to move the top portion of the cushion 102 laterally, the peak shear force applied by the cushion 102 to the occupant 100 remains below a peak shear force that would otherwise occur with a conventional cushion. If the braking lateral force is relatively long in duration compared with the time to move the top portion of the cushion 102 laterally, the peak shear force applied by the cushion 102 to the occupant 100 may equal that which would otherwise occur with a conventional cushion, but the peak shear force would be reached more gradually, which can reduce the risk of fatigue or injury on the occupant 100 user.

FIG. 1C illustrates the occupant 100 seated on the example shear cushion 102 of FIG. 1A subjected to an accelerating lateral force illustrated by arrow 114. FIG. 1C assumes that the occupant 100 is in motion in the vehicle. Although, in other implementations, a similar effect would occur when the user is accelerated forward when the vehicle is stationary. The accelerating lateral force is created due to an inertial force of the moving occupant 100 resisting acceleration of the vehicle, which is oriented in the opposite direction of the braking lateral force illustrated by the arrow 114. Further, in various implementations, the accelerating lateral force and corresponding inertial force is in addition to and independent of the gravitational (or normal) force and corresponding equal and opposite force depicted in FIG. 1A.

A shear force illustrated by arrow 116 allows the occupant 100 to remain fixed to the cushion 102 even though the inertial force is acting on the occupant 100. If a conventional cushion were used, an equal and opposing shear force would immediately be applied to the occupant 100 to resist the accelerating lateral force. When the shear cushion 102 is used, a top portion of the cushion 102 moves laterally with the occupant 100, reducing the opposing shear force/stress magnitude so long as the shear cushion 102 moves laterally with the occupant 100. If the accelerating lateral force is relatively short in duration compared with the time to move the top portion of the cushion 102 laterally, the peak shear force applied by the cushion 102 to the occupant 100 remains below a peak shear force that would otherwise occur with a conventional cushion. If the accelerating lateral force is relatively long in duration compared with the time to move the top portion of the cushion 102 laterally, the peak shear force applied by the cushion 102 to the occupant 100 may equal that which would otherwise occur with a conventional cushion, but the peak shear force would be reached more gradually, which can reduce the risk of fatigue or injury on the occupant 100.

Structural details of the cushion 102 are discussed below. Further, while the forces illustrated by arrows 104, 106, 110, 112, 114, 116 are oriented either in the normal direction or in the shearing direction for simplicity sake. Forces applied to the occupant 100 may be oriented in directions that include both a normal component and a shearing component. In these cases, a similar analysis is made by separating out the normal and shearing components.

FIG. 2A is a rear elevation view of an occupant 200 seated on an example shear cushion 202 prior to application of a lateral force. The cushion 202 may be a component cushion of any seat or saddle of a moving or movable (but currently stationary) vehicle (not shown). Further, while the occupant 200 is depicted using the cushion 202 in a sitting position, the presently disclosed technology could also apply to cushion the occupant 200 oriented in another position. For example, the cushion 202 could support the occupant 200 in a prone, supine, or a combination lying/sitting position with a similar effect as described herein. Further, the cushion 202 may provide the occupant 200 support in areas other than the user's posterior.

A gravitational (or normal) force is oriented downward as illustrated by arrow 204 pushing the occupant 200 against the cushion 202, which pushes back against the occupant 200 with an equal and opposing force, as illustrated by arrow 206. No lateral load is depicted in FIG. 2A and the cushion 202 merely provides support in a direction generally normal to an interface surface 208 of the cushion 202 with the occupant 200.

FIG. 2B illustrates the occupant seated on the example shear cushion of FIG. 2A subjected to a left-turning lateral force illustrated by arrow 210. FIG. 2B assumes that the occupant 200 is in motion in the vehicle. Although, in other implementations, a similar effect would occur when the user is accelerated to the left when the vehicle is stationary. The left-turning lateral force is created due to an inertial force of the moving occupant 200 resisting turning of the vehicle, which is oriented in the opposite direction of the lateral force illustrated by the arrow 210. Further, in various implementations, the left-turning lateral force and corresponding inertial force is in addition to and independent of the gravitational (or normal) force and corresponding equal and opposite force depicted in FIG. 2A.

A shear force illustrated by arrow 212 allows the occupant 200 to remain fixed to the cushion 202 even though the inertial force is acting on the occupant 200. If a conventional cushion were used, an equal and opposing shear force would immediately be applied to the occupant 200 to resist the left-turning lateral force. When the shear cushion 202 is used, a top portion of the cushion 202 moves laterally with the occupant 200, reducing the opposing shear force/stress magnitude so long as the shear cushion 202 moves laterally with the occupant 200. If the left-turning lateral force is relatively short in duration compared with the time to move the top portion of the cushion 202 laterally, the peak shear force applied by the cushion 202 to the occupant 200 remains below a peak shear force that would otherwise occur with a conventional cushion. If the left-turning lateral force is relatively long in duration compared with the time to move the top portion of the cushion 202 laterally, the peak shear force applied by the cushion 202 to the occupant 200 may equal that which would otherwise occur with a conventional cushion, but the peak shear force would be reached more gradually, which can reduce the risk of fatigue or injury on the occupant 200.

FIG. 2C illustrates the occupant 200 seated on the example shear cushion 202 of FIG. 2A subjected to a right-turning lateral force illustrated by arrow 214. FIG. 2C assumes that the occupant 200 is in motion in the vehicle. Although, in other implementations, a similar effect would occur when the user is accelerated to the right when the vehicle is stationary. The right-turning lateral force is created due to an inertial force of the moving occupant 200 resisting turning of the vehicle, which is oriented in the opposite direction of the lateral force illustrated by the arrow 214. Further, in various implementations, the right-turning lateral force and corresponding inertial force is in addition to and independent of the gravitational (or normal) force and corresponding equal and opposite force depicted in FIG. 2A.

A shear force illustrated by arrow 216 allows the occupant 200 to remain fixed to the cushion 202 even though the inertial force is acting on the occupant 200. If a conventional cushion were used, an equal and opposing shear force would immediately be applied to the occupant 200 to resist the right-turning lateral force. When the shear cushion 202 is used, a top portion of the cushion 202 moves laterally with the occupant 200, reducing the opposing shear force/stress magnitude so long as the shear cushion 202 moves laterally with the occupant 200. If the right-turning lateral force is relatively short in duration compared with the time to move the top portion of the cushion 202 laterally, the peak shear force applied by the cushion 202 to the occupant 200 remains below a peak shear force that would otherwise occur with a conventional cushion. If the right-turning lateral force is relatively long in duration compared with the time to move the top portion of the cushion 202 laterally, the peak shear force applied by the cushion 202 to the occupant 200 may equal that which would otherwise occur with a conventional cushion, but the peak shear force would be reached more gradually, which can reduce the risk of fatigue or injury on the occupant 200.

Structural details of the cushion 202 are discussed below. Further, while the forces illustrated by arrows 204, 206, 210, 212, 214, 216 are oriented either in the normal direction or in the shearing direction for simplicity sake. Forces applied to the occupant 200 may be oriented in directions that include both a normal component and a shearing component. In these cases, a similar analysis is made by separating out the normal and shearing components.

FIG. 3 is a perspective view of an example shear cushion 302. The shear cushion 302 includes six cushioning layers 318, 320, 322, 324, 326, 328, but in other implementations (see e.g., FIGS. 4-6) a greater or fewer number of cushioning layers may be used than that shown in FIG. 3. Each of the cushioning layers 318, 320, 322, 324, 326, 328 includes a planar array of cushioning elements. For example, the cushioning layer 318 includes cushioning elements 330, 332 oriented in the x-direction and cushioning 330, 334 elements oriented in the y-direction. In other implementations (see e.g., FIGS. 4-6), a greater or fewer number of cushioning elements make up each cushioning layer.

Each of the cushioning elements includes an upper void cell and a lower void cell bounded by two binding layers. The upper and lower void cells are attached together at a cell interface. For example, cushioning element 340 includes upper void cell 336 and lower void cell 338, and is bound by binding layers 342, 344 and attached together at cell interface 346. In some implementations, the void cells integrally protrude from each binding layer. In other implementation, the void cells are independently formed and attached to each binding layer. Further, each binding layer between adjacent cushioning layers can include two layers, one associated with an upper cushioning layer with void cells protruding there from and the other associated with a lower cushioning layer with void cells protruding there from. The two layers are attached together to form the binding layer. For example, the two layers may be physically attached to one another, such as by an adhesive. In another implementation, the two layers are not physically attached and frictional forces prevent the two layers from sliding relative to one another under a shear force. In other implementations, each binding layer lying between adjacent cushioning layers is a singular planar layer with void cells protruding in both directions from the binding layer.

Each cushioning element relies on elastic cell walls to operate as a spring in conjunction with other cushioning elements in the shear cushion 302. Further, each cushioning element in a cushioning layer is aligned with other cushioning elements in other cushioning layers of the shear cushion 302 to form substantially parallel (i.e., with less than a 5 degree variation or less than a 1 degree variation) columns of interconnected cushioning elements. For example, cushioning element 340 in cushioning layer 318 is aligned in the z-direction with cushioning elements 348, 350, 352, 354, 356 in cushioning layers 320, 322, 324, 326, 328 to form column 358. Column 358 is centered on axis 360, which is oriented in the z-direction.

As used herein, the term “vertically adjacent” shall mean adjacent to a given element along an axis in the z-direction. For example, the binding layer 344 is positioned between vertically adjacent cushioning elements 340 and 348. The binding layers can provide an adhesion interface to bind the vertically adjacent cushioning elements together and also to connect each cushioning element to one or more cushioning elements in horizontally adjacent columns (adjacent along an axis in the x-y plane).

In addition to providing an adhesion interface for vertically adjacent cushioning elements in a column, the binding layers also function to elastically connect together multiple columns. For example, the binding layer 344 connects column 358 to a laterally adjacent column 374. In this way, the cushioning elements are interconnected in columns (in the z-direction) and also in rows (in the x-direction and/or the y-direction) and sheets (in the x-y plane). The connections between cushioning elements in adjacent columns are non-rigid. Thus, each of the columns may bend, mimicking a cantilever beam, to absorb shear forces and to reduce the impact of the shear forces on an occupant in contact with the cushion, as described in further detail below with regard to FIGS. 4-6.

In some implementations, the binding layers are thin, flexible sheets of resilient material offset at a regular spacing and the columns (e.g., a column 312) bend without substantial deformation of the individual cushioning elements. In other implementations, both the individual cushioning elements and the binding layers are resiliently deflectable in response to shear loading of the shear cushion 300. Further, individual columns of cushioning elements may deflect in response a load substantially normal (i.e., with less than a 5 degree variation or less than a 1 degree variation) to the shear cushion 300. While individual columns of cushioning elements may deflect in this manner, the shear cushion 300 is stabilized by interactions of the surrounding columns of cushioning elements. Because the binding layers non-rigidly connect the columns of cushioning elements together, the binding layers prevent the individual columns within the cushion 300 from falling over or collapsing under shear and/or normal forces.

In one implementation, the binding layers have a substantially uniform elasticity in the x-y plane. In another implementation, the binding layers are tuned to allow for a different elasticity in one direction (e.g., the x-direction) than another direction (e.g., the y-direction). In still other implementations, the binding layers may contain perforations, areas of increased thickness, or other fine features that may influence elasticity. Such features may have the effect of providing the binding layers with directionalized elasticity, such that the binding layers have a greater elasticity in one direction as compared to another direction. As a result, an occupant of the cushion 300 may benefit from shear protection directionalized to target an expected shear loading direction.

The cushioning elements and binding layers can be of any material including elastomers, gels, stretched textiles, and air cells. In at least one implementation, the void cells (i.e., air cells) are made of two thermoformed sheets of plastic that, when formed with a cavity of a particular geometry, mimic a linear spring when compressed in the z-direction. In another implementation, the cushioning elements are solid elements constructed of another force absorbing material such as foam, rubber, etc.

In the implementation shown, the cushioning elements each include two opposed rectangular void cells, but the cushioning elements include void cells of any shape or geometry. In one implementation, the shapes of the cushioning elements in a row and/or column are different from the shapes of cushioning elements in other rows or columns of the cushion (see e.g., FIGS. 11 & 12).

The cushioning elements may be a variety of dimensions, ranging from small (less than a centimeter in the x-direction, y-direction, and/or z-direction) to large (several decimeters in the x-direction, y-direction, and/or z-direction). In one implementation, each of the opposed void cells of a cushioning element are cubes with dimensions of approximately 4 mm in the x-direction and the y-direction and 4-5 mm in z-direction. In another implementation, the cubes have dimensions of approximately 54 mm in the x-direction and the y-direction and 82 mm in z-direction. In further implementations, the cushioning element dimensions may vary between the aforementioned cube sizes.

The shear cushion 302 includes fixed surface 362 and an interface surface 308, each of which is oriented generally normal (i.e., with less than a 5 degree variation or less than a 1 degree variation) to the cushioning element column axes (e.g., the axis 360). The fixed surface 362 may be rigidly attached to a fixed structure (e.g., a seat frame of a vehicle) and the interface surface 308 is allowed to elastically move while interfaced with an occupant of the shear cushion 302 (see e.g., occupants 104, 204 of FIGS. 1 and 2). The interface surface 308 is located at an end of the columns opposite the fixed surface 362 an is permitted to move and respond to force inputs on the interface surface 308. Each column is configured to elastically deflect under a shear load, as described below in further detail with regard to FIGS. 4-6.

In at least one implementation, the vertical and/or adjacent cushioning elements are non-rigidly bound together. Although each of FIGS. 3-6 illustrate an x-z cross section, the y-z cross section may be the same or substantially similar in at least one implementation. For example, the cushion may be a cube or a rectangular box (see e.g., shear cushion 102, 202 of FIGS. 1A-2C) that includes stacked layers of cushioning elements.

An inherent instability in the columns (e.g., column 358) causes some x-y plane deflection of the columns under shear force, but the interconnections between the cushioning elements create a controlled stability within each of the cushioning layers. Thus, the multiple cushioning layers act together to create a controlled stability system. In the implementations that follow in FIGS. 4-6, an amount that each column laterally shifts in response to a shear force is inversely proportional to a length of the column. Therefore, taller columns (see e.g., FIG. 6) provide for greater shear force reduction than shorter columns (see e.g., FIG. 4). In at least one implementation, the movement of the columns and the binding layers in response to a changing shear force does not substantially affect the compression rate of the shear cushions 402, 502, 602 of FIGS. 4-6 in the z-direction.

FIG. 4 is a side elevation view of an example two-layer shear cushion 402 subjected to a shear force 412. The shear cushion 402 includes two cushioning layers 418, 420, each of which including an array of cushioning elements arranged generally in the y-z plane. For example, the cushioning layer 418 includes cushioning elements 430, 432, 448. Each of the cushioning elements includes an upper an upper void cell and a lower void cell bounded by two binding layers. The upper and lower void cells are attached together at a cell interface. For example, cushioning element 440 includes upper void cell 436 and lower void cell 438, and is bound by binding layers 442, 444 and attached together at cell interface 446.

Each cushioning element relies on elastic element walls to operate as a spring in conjunction with other cushioning elements in the shear cushion 402. Further, each cushioning element in a cushioning layer is aligned with other cushioning elements in other cushioning layers of the shear cushion 402 to form a column of cushioning elements. For example, cushioning element 440 in cushioning layer 420 is aligned in the z-direction with cushioning element 448 in cushioning layer 418 to form column 458. Column 458 is centered on axis 460, which is oriented in the z-direction when the shear cushion 402 is not under the shear force 412.

The shear cushion 402 includes fixed surface 462 and an interface surface 408, each of which is oriented generally normal to the cushioning element column axes (e.g., the axis 460). The fixed surface 462 may be rigidly attached to a fixed structure (e.g., a seat frame of a vehicle) and the interface surface 408 is allowed to elastically move while interfaced with an occupant of the shear cushion 402 (see e.g., occupants 104, 204 of FIGS. 1 and 2). Each column is configured to elastically deflect under a shear load, as described in detail below.

Without application of the shear force 412, column axes 460, 464, 466, 468, 470 are generally aligned and oriented in the z-direction. Upon application of the shear force 412, the surfaces of the cushioning elements adjacent the fixed surface 462 (e.g., cushioning element 440) remain fixed but the cushioning elements tilt in the direction of the shear force 412. Moving from the fixed surface 462 toward the interface surface 408, adjacent cushioning elements in each column also tilt and are displaced in the direction of the shear force 412, as illustrated by the tilted column axes 460, 464, 466, 468, 470. The orientation of each of the column axes 460, 464, 466, 468, 470 remains substantially the same due to the binding layers linking each of the individual adjacent cushioning elements in adjacent columns together.

Further, since the individual cushioning elements are elastically compressible, the deflection of the columns of cushioning elements is also elastic. Further, the binding layers are elastically stretchable. As a result, as the column axes 460, 464, 466, 468, 470 are tilted in the shear force 412 direction, the binding layers elastically stretch (see e.g., elastic deflection of binding layer 442 at point 472), which further elastically resists the deflection of the columns of cushioning elements. The two-layer shear cushion 402 is relatively rigid to shear deflection in the x-y plane as compared to a four-layer shear cushion 502 of FIG. 5 and a six-layer shear cushion 602 of FIG. 6 due to a limited number of cushioning elements in each column (i.e., 2 elements per column in shear cushion 402). This yields a relatively short beam length if the individual columns of cushioning elements are characterized as deflecting beams.

FIG. 5 is a side elevation view of an example four-layer shear cushion 502 subjected to a shear force 512. The shear cushion 502 includes four cushioning layers 518, 520, 522, 524, each of which including an array of cushioning elements arranged generally in the y-z plane. For example, the cushioning layer 518 includes cushioning elements 530, 532, 548. Each of the cushioning elements includes an upper void cell and a lower void cell bounded by two binding layers. The upper and lower void cells are attached together at a cell interface. For example, cushioning element 540 includes upper void cell 536 and lower void cell 538, and is bound by binding layers 542, 544 and attached together at cell interface 546.

Each cushioning element relies on elastic element walls to operate as a spring in conjunction with other cushioning elements in the shear cushion 502. Further, each cushioning element in a cushioning layer is aligned with other cushioning elements in other cushioning layers of the shear cushion 502 to form a column of cushioning elements. For example, cushioning element 540 in cushioning layer 524 is aligned in the z-direction with cushioning elements 548, 550, 552 in cushioning layers 518, 520, 522 to form column 558. Column 558 is centered on axis 560, which is oriented in the z-direction when the shear cushion 502 is not under the shear force 512.

The shear cushion 502 includes fixed surface 562 and an interface surface 508, each of which is oriented generally normal to the cushioning element column axes (e.g., the axis 560). The fixed surface 562 may be rigidly attached to a fixed structure (e.g., a seat frame of a vehicle) and the interface surface 508 is allowed to elastically move while interfaced with an occupant of the shear cushion 502 (see e.g., occupants 104, 204 of FIGS. 1 and 2). Each column is configured to elastically deflect under a shear load, as described in detail below.

Without application of the shear force 512, column axes 560, 564, 566, 568, 570 are generally aligned and oriented in the z-direction. Upon application of the shear force 512, the surfaces of the cushioning elements adjacent the fixed surface 562 (e.g., cushioning element 540) remain fixed but the cushioning elements tilt in the direction of the shear force 512. Moving from the fixed surface 562 toward the interface surface 508, adjacent cushioning elements in each column also tilt and are displaced in the direction of the shear force 512, as illustrated by the tilted column axes 560, 564, 566, 568, 570. The orientation of each of the column axes 560, 564, 566, 568, 570 remains substantially the same due to the binding layers linking each of the individual adjacent cushioning elements in adjacent columns together.

Further, since the individual cushioning elements are elastically compressible, the deflection of the columns of cushioning elements is also elastic. Further, the binding layers are elastically stretchable. As a result, as the column axes 560, 564, 566, 568, 570 are tilted in the shear force 512 direction, the binding layers elastically stretch (see e.g., elastic deflection of binding layer 542 at point 572), which further elastically resists the deflection of the columns of cushioning elements. The four-layer shear cushion 502 is relatively rigid to shear deflection in the x-y plane as compared to a six-layer shear cushion 602 of FIG. 6 and relatively compliant as compared to the two-layer shear cushion 402 of FIG. 4. This yields a relatively medium beam length if the individual columns of cushioning elements are characterized as deflecting beams.

FIG. 6 is a side elevation view of an example six-layer shear cushion 602 subjected to a shear force 612. The shear cushion 602 includes six cushioning layers 618, 620, 622, 624, 626, 628 each of which including an array of cushioning elements arranged generally in the y-z plane. For example, the cushioning layer 618 includes cushioning elements 630, 632, 648. Each of the cushioning elements includes an upper an upper void cell and a lower void cell bounded by two binding layers. The upper and lower void cells are attached together at a cell interface. For example, cushioning element 640 includes upper void cell 636 and lower void cell 638, and is bound by binding layers 642, 644 and attached together at cell interface 646.

Each cushioning element relies on elastic element walls to operate as a spring in conjunction with other cushioning elements in the shear cushion 602. Further, each cushioning element in a cushioning layer is aligned with other cushioning elements in other cushioning layers of the shear cushion 602 to form a column of cushioning elements. For example, cushioning element 640 in cushioning layer 628 is aligned in the z-direction with cushioning elements 648, 650, 652, 654, 656 in cushioning layers 618, 620, 622, 624, 626 to form column 658. Column 658 is centered on axis 660, which is oriented in the z-direction when the shear cushion 602 is not under the shear force 612.

The shear cushion 602 includes fixed surface 662 and an interface surface 608, each of which is oriented generally normal to the cushioning element column axes (e.g., the axis 660). The fixed surface 662 may be rigidly attached to a fixed structure (e.g., a seat frame of a vehicle) and the interface surface 608 is allowed to elastically move while interfaced with an occupant of the shear cushion 602 (see e.g., occupants 104, 204 of FIGS. 1 and 2). Each column is configured to elastically deflect under a shear load, as described in detail below.

Without application of the shear force 612, column axes 660, 664, 666, 668, 670 are generally aligned and oriented in the z-direction. Upon application of the shear force 612, the surfaces of the cushioning elements adjacent the fixed surface 662 (e.g., cushioning element 640) remain fixed but the cushioning elements tilt in the direction of the shear force 612. Moving from the fixed surface 662 toward the interface surface 608, adjacent cushioning elements in each column also tilt and are displaced in the direction of the shear force 612, as illustrated by the tilted column axes 660, 664, 666, 668, 670. The orientation of each of the column axes 660, 664, 666, 668, 670 remains substantially the same due to the binding layers linking each of the individual adjacent cushioning elements in adjacent columns together.

In one implementation, the column axes 660, 664, 666, 668, 670 act substantially as cantilever beams, which primarily provides the desired shear performance of the shear cushion 602. In other implementations, the column axes 660, 664, 666, 668, 670 substantially bend under shear load and the bending of column axes 660, 664, 666, 668, 670 primarily provides the desired shear performance of the shear cushion 602. In still other implementations, both cantilever beam and bending characteristics of the column axes 660, 664, 666, 668, 670 provide the desired shear performance of the shear cushion 602.

Further, since the individual cushioning elements are elastically compressible, the deflection of the columns of cushioning elements is also elastic. Further, the binding layers are elastically stretchable. As a result, as the column axes 660, 664, 666, 668, 670 are tilted in the shear force 612 direction, the binding layers elastically stretch (see e.g., elastic deflection of binding layer 642 at point 672), which further elastically resists the deflection of the columns of cushioning elements. The six-layer shear cushion 602 is relatively compliant to shear deflection in the x-y plane as compared to the two-layer shear cushion 402 of FIG. 4 and the four-layer shear cushion 502 of FIG. 5 due to a greater number of cushioning elements in each column (i.e., 6 elements per column in shear cushion 602). This yields a relatively long beam length if the individual columns of cushioning elements are characterized as deflecting beams.

FIG. 7 is a graph 700 illustrating peak shear force over time of an example conventional cushion and an example shear cushion (not shown). The conventional cushion and the shear cushion are each subjected to an equal lateral shear force (illustrated by solid shear force curve 702) that has a duration of t₂. A reaction force of the conventional cushion in the opposite direction of the shear force is illustrated by dashed conventional reaction curve 704. A reaction force of the shear cushion in the opposite direction of the shear force is illustrated by dashed stacked opposed void reaction curve 706.

The conventional reaction curve 704 rapidly increases from 0 at t₀to a peak reaction force equal to the shear force (F₁) at t₁, which occurs prior to end of the shear force at t₂. After the shear force ends at time t₂, the conventional reaction curve 704 rapidly decreases back to 0 at t₄. Since the conventional reaction curve 704 does not provide a reduced peak reaction force, the corresponding conventional cushion does not provide a user substantial relief from discomfort caused by peak shear force.

The stacked opposed void reaction curve 706 increases more slowly over time from 0 at t₀to a peak reaction force (F₂) at t₃. Since the shear force ends before the stacked opposed void reaction curve 706 reaches the a peak reaction force (F₂), the peak reaction force (F₂) of the stacked opposed void reaction curve 706 remains below the shear force (F₁). After the shear force ends at time t₂, the stacked opposed void reaction curve 706 slowly decreases back to 0 at t₅. Since the stacked opposed void reaction curve 706 provides a reduced peak reaction force, the corresponding shear cushion may provide the user substantial relief from discomfort caused by peak shear force. A similar effect may occur as the shear force changes over time with different directional components and durations. So long as shear force duration is insufficient to cause the shear cushion to fully deflect.

Further, the slope of the conventional reaction curve 704 as compared to the stacked opposed void reaction curve 706 also influences user comfort. The relatively steep increasing and decreasing slope of the conventional reaction curve 704 causes rapid changes in reaction force, which decreases user comfort. The relatively shallow increasing and decreasing slope of the stacked opposed void reaction curve 706 insulates the user from rapid changes in shear force, increasing user comfort.

In various implementations, the disclosed shear cushions provide a linear or monotonically increasing force-deflection response to shear and/or normal loading. The linear or monotonically increasing force-deflection response is a result or one or both of stretching of the binding layer(s) within the shear cushions and elastic collapse of individual cushioning elements within the shear cushions.

FIG. 8 is a perspective view of an example shear cushion 802 with offset cushioning layers. The shear cushion 802 includes seven cushioning layers 818, 820, 822, 824, 826, 828, 876 and each of the cushioning layers 818, 820, 822, 824, 826, 828, 876 includes a planar array of cushioning elements (e.g., cushioning elements 830, 832, 834, 840, 848, 850, 852). Still further, each of the cushioning layers 818, 820, 822, 824, 826, 828, 876 are bound by binding layers (e.g., binding layer 844). For additional details regarding the cushioning layers, cushioning elements, and binding layers, see FIG. 3 and detailed description thereof

The offset shear cushion 802 includes columns of cushioning elements, but the individual cushioning elements are not vertically adjacent as depicted in FIGS. 3-6. In shear cushion 802, every other cushioning element in aligned in a vertical column. For example, column 858 is centered on axis 860 and is made up of four cushioning elements 840, 848, 850, 852. Column 874 is centered on axis 864 and is made up of three cushioning elements 830, 832, 834. Additional columns of three or four cushioning elements are centered on axes 866, 868, 870, 878, 880, 882 in the offset shear cushion 802. Offsetting cushioning layers 818, 820, 822, 824, 826, 828, 876 in this manner may increase rigidity of the cushion 802 in the x-y plane while maintaining the same or similar rigidity in the z-direction as compared to a non-offset shear cushion (e.g., cushion 300 of FIG. 3) and maintaining the aforementioned shear force reduction characteristics.

In other implementations, a greater or fewer quantity of cushioning elements make up each cushioning layer and/or a greater or fewer quantity of cushioning layers make up the shear cushion 802. Further, the x-y plane offsets between adjacent cushioning layers may be changed to increase the number of layers between cushioning elements in a column (e.g., a column of cushioning elements may be made up vertically of every third cushioning element in a stack of cushioning layers).

FIG. 9 is a side elevation schematic of an example shear cushion 902. The cushion 900 includes cushioning elements (e.g., cushioning elements 930, 932, 934, 948, 950) arranged in columns (z-direction) and rows (x-direction and y-direction). Although each column in the implementation illustrated has three cushioning elements, any quantity of two or more cushioning elements per column is contemplated herein.

The cushioning elements are interconnected vertically and horizontally by springs (e.g., springs 942, 944). More specifically, each cushioning element is connected to vertically adjacent cushioning elements by a column spring (e.g., a column spring 942). Further, each cushioning element is also connected to horizontally adjacent cushioning elements in an adjacent column by way of a row spring (e.g., a row spring 944). Additional row springs connect adjacent cushioning elements in the y-direction. The column and row springs establish and maintain axial alignment between the rows and columns of cushioning elements.

Although actual springs may be used, both the column springs and rows springs may also be any type of elastic material that mimics the behavior of a linear spring when compressed along the length of the spring (i.e., when compressed in the x-direction or y-direction for row springs and when compressed in the z-direction for column springs). For example, the springs may be elastic, rubber, thermoplastic urethane, thermoplastic elastomers, styrenic co-polymers, rubber, DOW Pellethane™, Lubrizol Estane™, Dupont™ Hytrel™, ATOFINA Pebax™, Krayton polymers, etc.

Although not pictured, a y-z cross section of the cushion 902 may be similar to the depicted x-z cross-section of FIG. 9, and springs may connect horizontally adjacent cushioning elements in the y-direction as well as in the x-direction. In other implementations, springs may diagonally connect cushioning elements between. These diagonal springs may exist in lieu of or in addition to the springs in the x-direction, y-direction, and/or z-direction.

The column springs can be uniquely tuned to absorb and distribute z-direction compression forces, such as the compression force created by an occupant transferring his or her weight to the cushion 902. In one implementation, the effective spring of the columns differs from one to another. For example, the effective spring constant of columns near the center of the cushion could have a smaller effective spring constant than columns near the edges of the cushion. Such configuration could encourage the occupant to sit properly on the center of the cushion 902 instead of off to one side where the occupant may fall or be thrown off a corresponding vehicle, such as during sharp turns of the vehicle, collisions, etc. Further, the individual cushioning elements within a single layer (e.g., those cushioning elements in the x-y plane at a given z-direction height) may be shaped differently from one another and/or made of different materials to allow for directionalized pressure distribution at an interface surface of the cushion 902 with the occupant.

Still further, the row springs may be uniquely tuned to allow for lateral movement (i.e., movement in the x-y plane) of each row of cushioning elements. Such lateral movement may substantially reduce or eliminate shear forces created between the cushion 902 and an occupant of the cushion 902. In one implementation, the effective spring constant of each row of cushioning elements is different from the effective spring constant of one or more columns in the cushion 902. For example, the column springs may be uniquely tuned for pressure distribution and the row springs may be uniquely tuned for absorbing weight-shift or shear (x-y plane) forces.

Further yet, the rows of cushioning elements within the cushion 902 may have different effective spring constants. For example, one or more rows near the bottom of the cushion (i.e., rows furthest from the occupant) may have smaller effective spring constants than rows near the top of the cushion 902. This may result in increased instability at the top of the cushion 902 and offer greater shear force protection to the occupant. The row springs may also be tuned to mitigate or prevent collisions between horizontally adjacent cushioning elements. For example, the row spring 944 may be compressed a maximum distance to prevent a collision between cushioning elements 930 and 950.

FIG. 10 is a side elevation schematic of an example shear cushion 1002 subjected to a lateral force 1012. The cushion 1002 includes cushioning elements (e.g., cushioning elements 1030, 1032, 1034, 1048, 1050) arranged in columns (z-direction) and rows (x-direction and y-direction). Although each column in the implementation illustrated has three cushioning elements, any quantity of two or more cushioning elements per column is contemplated herein.

The cushioning elements are interconnected vertically and horizontally by springs (e.g., springs 1042, 1044). More specifically, each cushioning element is connected to vertically adjacent cushioning elements by a column spring (e.g., a column spring 1042). Further, each cushioning element is also connected to horizontally adjacent cushioning elements in an adjacent column by way of a row spring (e.g., a row spring 1044). Additional row springs connect adjacent cushioning elements in the y-direction. The column and row springs establish and maintain axial alignment between the rows and columns of cushioning elements.

Upon application of the lateral force 1012, the surfaces of the cushioning elements adjacent a fixed surface 1062 (e.g., cushioning element 1034) remain fixed. Moving away from the fixed surface 1062, adjacent cushioning elements in each column are displaced in the direction of the shear force 1012. Since the springs are elastically stretchable, the displacement of the cushioning elements as a result of the shear force 1012 is elastic and may be used to reduce or prevent a peak shear force on an occupant of the cushion 1002.

FIG. 11 is a top plan view of an example shear cushion 1102 with directional cushioning elements (e.g., cushioning element 1130) and non-directional cushioning elements (e.g., cushioning element 1132). While only one cushioning layer 1118 of the shear cushion 1102 is depicted in FIG. 11, one or more additional cushioning layers may exist over or under the cushioning layer 1118 in the z-direction with individual cushioning elements arranged in columns (i.e., extending in the z-direction). Further, the individual cushioning elements of cushioning layer 1118 are also arranged in rows (i.e., in the x-direction and the y-direction) and are interconnected by a binding layer 1142. More specifically, each cushioning element is connected to horizontally adjacent cushioning elements (i.e., cushioning elements adjacent in the x-y plane) by the binding layer 1142. The binding layer 1142 establishes and maintains axial alignment between the columns of cushioning elements.

Some of the cushioning elements have an elongated rectangular shape in plan view (e.g., cushioning element 1130), which permits substantial shearing displacement in one direction while limiting the shearing displacement in another direction. For example, a column of similarly sized and shaped cushioning elements that includes cushioning element 1130 will displace under shear force significantly more readily in the x-direction than in the y-direction. A column of similarly sized and shaped cushioning elements that includes cushioning element 1132 will displace under shear force similarly in the x-direction and in the y-direction.

Since the non-directional cushioning elements can move in both the x-direction and the y-direction to absorb shear forces. Thus, a cushioning element including non-directional cushioning elements may be able to prevent or reduce shearing equally in both the x-direction and the y-direction. In contrast, a cushion including directional cushioning elements can readily move in the x-direction but less so in the y-direction. Thus, directional cushioning elements may be highly effective at absorbing weight shifts in the x-direction and less effective at absorbing weight shifts in the y-direction. Therefore, directional cushioning elements may be particularly well suited for mitigating shear forces in a single direction.

The cushioning element shape in plan view may be of any shape, including but not limited to round, triangular, cylindrical, non-traditional shapes, etc. Further, the cushioning elements may also be any volume-enclosing shape, including but not limited to spheres, prisms, cylinders, cubes, non-traditional shapes, etc. The amount of force needed to bend a vertical column of cushioning elements may be directly related to the shape of the individual cushioning elements within that column. Therefore, different cushioning element shapes can be used to achieve varying shear mitigation in various directions. As a result, the shear cushion 1102 may be tuned with a distinct response to shear forces in a variety of directions as well as normal loading of the shear cushion 1102.

In another example implementation, the cushioning elements have a round shape in plan view and are thus capable of reducing shear equally in all lateral directions. In another example implementation, the cushioning elements have a triangular shape in plan view capable of reducing shear primarily in three lateral directions. Here, the amount of shear reduction achieved in each direction may vary depending upon the length of each side of the triangular cushioning element.

FIG. 12 is a side elevation view of an example four-layer shear cushion 1202 with columns 1258, 1272 of progressively changing cushioning elements (e.g., cushioning elements 1230, 1232, 1234, 1240). The shear cushion 1202 includes four cushioning layers 1218, 1220, 1222, 1224, each of which including an array of cushioning elements arranged generally in the y-z plane. For example, the cushioning layer 1218 includes cushioning elements 1230, 1231. Two binding layers bound each of the cushioning elements. For example, cushioning element 1230 is bound by binding layers 1242, 1244.

Each cushioning element relies on elastic element walls to operate as a spring in conjunction with other cushioning elements in the shear cushion 1202. Further, each cushioning element in a cushioning layer is aligned with other cushioning elements in other cushioning layers of the shear cushion 1202 to form columns (e.g., columns 1258, 1274) of cushioning elements. For example, cushioning element 1230 in cushioning layer 1218 is aligned in the z-direction with cushioning elements 1232, 1234, 1240 in cushioning layers 1220, 1222, 1224 to form the column 1274. Column 1274 is centered on axis 1260, which is oriented in the z-direction when the shear cushion 1202 is not under a shear force.

The shear cushion 1202 includes fixed surface 1262 and an interface surface 1208, each of which is oriented generally normal to the cushioning element column axes (e.g., the axis 1260). The fixed surface 1262 may be rigidly attached to a fixed structure and the interface surface 1208 is allowed to elastically move while interfaced with an occupant of the shear cushion 1202 (see e.g., occupants 104, 204 of FIGS. 1 and 2). Each column is configured to elastically deflect under a shear load, as described in detail above.

The cushioning elements progressively decrease in size from the top of the shear cushion 1202 (i.e., the largest cushioning element 1230 in column 1274) to the bottom of the shear cushion 1202 (e.g., the smallest cushioning element 1240 in the column 1274). This configuration may allow for greater instability of the individual columns of cushioning elements as compared to a shear cushion 1202 with similarly sized cushioning elements. The binding layers control this instability within the shear cushion 1202 by binding together both vertically adjacent cushioning elements and horizontally adjacent cushioning elements.

In other implementations, the cushioning elements progressively increase in size from the top of the shear cushion 1202 to the bottom of the shear cushion 1202. This configuration may allow for greater stability of the individual columns of cushioning elements as compared to a shear cushion 1202 with similarly sized cushioning elements.

FIG. 13 illustrates example operations 1300 for using a shear cushion to reduce peak shear force on an occupant of the shear cushion. An interfacing operation 1305 interfaces an occupant with a shear cushion. In various implementations, the occupant sits, stands, and/or lies on the shear cushion, thus interfacing the occupant with the cushion. A first subjecting operation 1307 subjects the shear cushion to a normal force. More specifically, the normal force is a force on the shear cushion normal to the cushioning layers and binding layers, and user interface surface of the shear cushion. The normal force may compression partially or completely one or more cushioning elements within the shear cushion. In various implementations, the normal force is the result of a gravitational force on the user pushing the user against the shear cushion. Further, the normal force may be a component force of any force acting on the shear cushion at the user interface surface. In that implementation, the other component force is shear force acting on the user interface surface in a direction parallel to the user interface surface.

A subjecting operation 1310 subjects the shear cushion and the occupant to a shear force. The shear force may be applied as a result of inertial force acting on the occupant and the shear cushion. For example, a change of direction or speed of a vehicle within which the occupant is traveling may cause the shear force. In another example, vibration of the vehicle causes the shear force. A surface of the shear cushion opposite the interface surface with the occupant is attached to a fixed surface within the vehicle. As a result, the inertial force creates an opposite shear force at the interface surface between the occupant and the shear cushion so long as the occupant does not slide with respect to the shear cushion.

A shifting operation 1315 shifts the interface surface between the shear cushion and the occupant in the direction of the shear force. A tilting operation 1317 tilts individual columns of cushioning elements within the shear cushion in the direction of the shear force. The shifting operation 1315 and the tilting operation 1317 are in response to the subjecting operation 1310 and can reduce the peak shear force acting on the occupant.

A reducing/changing operation 1320 reduces or changing the direction of the shear force prior to the end of the shifting operation 1315 and the tilting operation 1317. So long as reducing/changing operation 1320 occurs prior to the end of the operations 1315,1317, the reducing/changing operation 1320 can reduce the peak shear force acting on the occupant to a magnitude less than the inertial force acting on the shear cushion and the occupant.

The subjecting operation 1310, shifting operation 1315, tilting operation 1317, and reducing/changing operation 1320 can be repeated in quick succession as the shear force changes over time, reducing the peak forces acting on the occupant over time. As a result, the shifting operation 1315, tilting operation 1317, and reducing/changing operation 1320 can increase comfort and reduce the possibility of injury to the occupant.

The aforementioned operations 1300 may be performed in any order, adding or omitting operations as desired, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.

The above specification provides a complete description of the structure and use of exemplary embodiments of the invention. Since many implementations of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. Furthermore, structural features of the different implementations may be combined in yet another implementation without departing from the recited claims.

SHEAR CUSHION WITH INTERCONNECTED COLUMNS OF CUSHIONING ELEMENTS

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CROSS-REFERENCE TO RELATED APPLICATIONS

Provisional Applications (1)