BACKGROUND

[0001] The invention relates generally to the attachment of sheet materials used in vehicular applications, and more particularly, to a method of attachment of sheet materials.

[0002] Sheet materials are used in vehicles for a variety of applications. For example, fabric sheet materials may be used for seat upholstery, headliners, door panels, flooring, and the like. Generally, the sheet materials are applied to a surface with an adhesive to secure the sheet material in place. The adhesive may create a chemical bond that couples the sheet material to an underlying surface. However, the integrity of the bond may degrade over time as the adhesive ages. Additionally, the bond may weaken due to exposure to heat and wear over time. As the bond weakens, the sheet material may partially or fully detach from the underlying surface, resulting in bubbles and air pockets forming under the sheet material. As such, the aesthetic quality of the vehicle is diminished. Further, once the sheet material begins to separate from the underlying surface, it may be difficult and costly to repair. In some cases, the sheet material may need to be completely removed and replaced. Further, sheet materials attached via adhesive may impede the serviceability of internal components.

[0003] To date, however, no real attempt has been made to improve the method of attachment used to couple sheet materials to an underlying surface, particularly in vehicular applications. Accordingly, there is a need in the art for innovative solutions that improve the attachment method, durability, serviceability, and reparability of sheet materials in vehicles. Further, such solutions may be applicable beyond use in vehicles. For example, the solutions may be applied to furniture upholstery, carpeting, padded surfaces, and other scenarios wherein a sheet material is attached to an underlying surface. BRIEF DESCRIPTION

[0004] The present invention provides a novel method for attaching a sheet material to a substrate (i.e., underlying surface) designed to respond to such needs. Such a method may include the use of a magnetic (e.g., rheological materials), thermal (e.g., shape memory alloys), molecular (e.g., Van der Waals forces), mechanical, and/or electromechanical attachment system. In accordance with certain aspects, the attachment system includes attachment fibers having free attachment ends that may be secured adjacent to the substrate, and the attachment fibers may be able to change orientation. With the attachment fibers in one orientation, the sheet material may be disposed adjacent to the attachment fibers and the attachment fibers may be re-oriented to cause the free attachment ends to attach to the sheet material. In this way, the sheet material may be secured to the substrate without relying on an adhesive.

DRAWINGS

[0005] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0006] FIG. 1 is perspective view of an exemplary vehicle incorporating the sheet material attachment methods and an attachment system in accordance with aspects of the present invention;

[0007] FIG. 2 is a perspective view of an electro-mechanical embodiment of the attachment system which may be utilized for sheet material attachment;

[0008] FIG. 3 is a side view of the electro-mechanical attachment system of FIG. 2 in a first orientation; [0009] FIG. 4 is a side view of the electro-mechanical attachment system of FIG. 2 in a second orientation; and

[0010] FIG. 5 is a perspective view of a vehicle seat having an embodiment of the attachment system.

DETAILED DESCRIPTION

[0011] Turning now to the drawings, FIG. 1 illustrates an exemplary vehicle 10, in which the invention may be deployed. The vehicle 10, in this case a car, may include numerous surfaces covered by a sheet material. For example, seats 12, door and body paneling 14, a headliner 16, or other components may include a sheet material covering. The sheet material covering may be applied using a magnetic (e.g., rheological materials), thermal (e.g., shape memory alloys), molecular (e.g., Van der Waals forces), mechanical, and/or electro-mechanical means of attachment, as described in detail below, instead of an adhesive. Such attachment means of the sheet material may provide a smooth, taut surface and may be particularly useful for curved surfaces. Additionally, the means of attachment may enable simple assembly, repair, and replacement processes. For example, the attachment method may use fewer parts than traditional assembly methods. Further, the attachment method may result in less scrap material than assembly via adhesive. The method of attachment may be incorporated in other vehicular applications, such as trucks, busses, aircraft, boats, and any other vehicles.

[0012] FIG. 2 illustrates an embodiment of a portion of an electro-mechanical attachment system 30 which may be used to attach a sheet material 32 to a substrate 34 (i.e., underlying surface). The sheet material 32 may be fabric, foam-like, woven, or any sort of generally porous material. Non-porous materials, such as leather and/or plastics, may be used with a sheet material 32 backing or may include small loops to emulate porosity and/or to provide a surface suitable for attachment as described below. The substrate 34 may be any surface over or on which it is desirable to place the sheet material 32. [0013] The substrate 34 may have multiple attachment fibers 36 on an outer surface 38 (i.e., the surface that receives the sheet material 32). The attachment fibers 36 may be placed over the entire surface 38 or may be arranged in various patterns on the surface 38. The attachment fibers 36 may be extremely small, generally within the micro or nano-scale. As shown, the attachment fibers 36 may have an orientation in which they extend perpendicularly from the substrate 34. Additionally, as described below, the attachment fibers 36 may have a different orientation in which they lay flat along the surface 38 of the substrate 34. Thus, as will also be described below, the attachment fibers 36 may be subject to an effect which enables changing their orientation between standing perpendicularly and laying flat. The attachment fibers 36 may include free attachment ends 40, which are the ends of the attachment fibers 36 that are not attached to the substrate 34. The free attachment ends 40 may couple with the sheet material 32 due to its porosity or texture. In the depicted embodiment, the free attachment ends 40 include a hook structure 42 that may enable a secure connection between the attachment end 40 and the sheet material 32, but other suitable geometry may be used at the attachment ends 40. For example, the attachment ends 40 may include enlarged spheres, L-shapes, notches, or other structures that enable the attachment ends 40 to couple with the sheet material 32. The connection between the sheet material 32 and the plurality of free attachment ends 40 may result in a smooth appearance of the sheet material over the substrate 34. Further, the connection may facilitate quick attachment of the sheet material 32 to the substrate 34, decreasing assembly and/or repair time and improving serviceability to components beneath the sheet material 32.

[0014] In certain embodiments, as shown, the electro-mechanical form of the attachment system 30 may include an electroactive polymer (EAP) 44. The EAP 44 may be disposed around the attachment fibers 36 in the form of a grid or a similar structure that includes multiple openings. The EAP 44 may physically move when activated by an electric charge, current, field, etc. Accordingly, the EAP 44 may physically interact with the attachment fibers 36, causing the attachment fibers 36 to change orientation depending on the direction of the EAP 44 movement. For example, the EAP 44 may contract to make the attachment fibers 36 stand perpendicularly to the substrate 34, and the EAP 44 may expand to make the attachment fibers 36 lay flat. In alternative embodiments, the attachment system 30 may utilize the magnetic properties of rare earth elements and/or electromagnets or the thermal properties of a shape memory alloy with a heat source and/or resistive current.

[0015] FIG. 3 provides a depiction of the electro-mechanical attachment system 30 wherein the EAP 44 is contracted, and the attachment fibers 36 are standing. In some embodiments, the attachment fibers 36 may utilize Van der Waals forces to attract and attach to the sheet material 32. Accordingly, one surface may be sufficiently smooth to attract the attachment fibers 36. The molecular attraction of the Van der Waals forces may enable the attachment fibers 36 to securely affix to the sheet material 32, thereby reducing or eliminating the need to use an adhesive or electrical stimulus. The sheet material 32 may be coupled to the attachment ends 40 when the attachment fibers 36 are in the perpendicular position, as shown. Further, when the attachment fibers 36 are reoriented to lay down, the attachment fibers 36 may pull the sheet material 32 taut over the substrate 34. As will be appreciated, using the attachment fibers 36 with Van der Waals forces to attach the sheet material 32, in place of adhesive, may simplify the assembly process. For example, the sheet material 32 may attach evenly and smoothly to the substrate 34, without creating discontinuities due to air bubbles and uneven adhesive distribution in certain prior art structures.

[0016] The attachment fibers 36 may be oriented perpendicularly using the EAP 44. The EAP 44 may be a polymer that changes size and/or shape when subjected to an electric field. As such, when the electric field is applied to the EAP 44, it may cause the EAP 44 to contract, thereby orienting the attachment fibers 36 perpendicularly to the substrate 34. However, in alternative embodiments, the attachment fibers 36 may achieve perpendicular orientation when exposed to an electrostatic charge. Utilizing an electrical stimulus (e.g., as with the EAP 44 or the electrostatic charge) to orient the attachment fibers 36 may enable the sheet material 32 to be easily attached and adjusted. Similarly, magnetic and thermal stimuli may enable improved sheet material 32 attachment. For example, if the sheet material becomes damaged (e.g., stained, torn, etc.), the electrical, magnetic, and/or thermal stimulus may be applied to the attachment fibers 36 to orient them perpendicularly, the sheet material 32 may be quickly removed and replaced, and the electrical, magnetic, and/or thermal stimulus may be removed from the attachment fibers 36 such that they return to laying along the substrate 34.

[0017] FIG. 4 provides a depiction of the electro-mechanical attachment system 30 wherein the EAP 44 is expanded and the attachment fibers 36 are laying flat against the substrate 34. In certain embodiments, the laying position of the attachment fibers 36 may be the natural orientation of the attachment fibers 36. In other words, without the presence of the electrical stimulus, the attachment fibers 36 may lay flat against the substrate 34. Accordingly, it may be desirable that the sheet material 32 is in its final position (i.e., smoothly applied to the substrate 34) when the attachment fibers 36 are in the laying position, thereby only requiring the use of the electrical stimulus during the attachment and assembly process. As described below, the attachment hooks 36 may be arranged on the substrate 34 such that they lay in varying arrangements and directions.

[0018] FIG. 5 depicts the seat 12 of the vehicle 10, which has a concave surface 60 to complement body shape. The concave surface 60 may form a seating surface of a foam cushion, polymer, and/or knitted scrim, which is the substrate 34. Multiple attachment fibers 36 may be fixed to the substrate 34. As depicted, the EAP 44 may be incorporated in strips 62 on the seat 12. In certain embodiments, the different strips 62 may be arranged such that the EAPs 44 will contract in opposing directions when subjected to the electrical stimulus. Accordingly, the sheet material 32 may be pulled in opposing directions when the attachment fibers 36 are laid flat. This may enable the sheet material 32 to be held tautly against the surface of the substrate 34, preventing the formation of air pockets, bubbles, and wrinkles in the sheet material 32. Since the strips 62 of the EAP 44 need the electrical stimulus to become activated, a conductive region 64 may connect the strips 62. The conductive region may be formed of a suitable conductive material and geometry. For example, the conductive region may be a wire, strip, bar, sheet, conductive pad, conductive ink, ribbon, thin layer, or other shape. Although described with respect to a vehicle seat 12, the electro-mechanical attachment system 30 may be used in a variety of applications wherein the sheet material 32 needs to be smoothly coupled to the substrate 34 and the use of adhesive is undesirable. Further, although described with respect to an electrical stimulus, a magnetic and/or thermal stimulus may also be applied.

[0019] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.