Abstract:
A seat cushion system that reduces the vertical impact to the seat occupant within the space and cost constraints of existing seat support structures. In one embodiment, the seat cushion employs a series of layers of varying density and lateral displacement foams with a rigid or semi-rigid material within the cushion. Each layer of foam can change in both density and lateral displacement depending on the volumetric space available. Another embodiment demonstrates how only two layers of differing densities and lateral displacement can greatly reduce the impact force from vertical thrust.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application under 35 U.S.C. §371 of PCT application PCT/US95/06736 filed 26 May 1995, which is a continuation-in-part of PCT application PCT/US93/12017 filed December 1993, which was a continuation-in-part of PCT application PCT/US93/08771 filed 16 September 1993 of U.S. application Ser. No. 07/984,089, filed Nov. 30, 1992, now U.S. Pat. No. 5,269,590, which was a continuation-in-part of U.S. Ser. No. 07/840,592, filed Feb. 19, 1992, now abandoned, which was a continuation of U.S. Ser. No. 07/673,242, filed Mar. 19, 1991, now abandoned, which was a continuation of U.S. Ser. No. 07/525,920, filed May 21, 1990, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to high impact seating, specifically, seating that is associated with a moving device, i.e. boat, tractor, etc. and the ability to reduce impact on the human body, within the space and cost constraints of existing seat configurations. 
     2. Description of Prior Art 
     The shape and size of the human frame present a sizable challenge when trying to fit this into a uniform product. Much of the existing seating is no more than a cushion constructed of a single piece of medium density foam rubber with an internal lateral displacement of 20 to 30. More elaborate seats have added mechanical equipment to enhance the impact reduction attributes. Most of these remove the impact by use of devices such as an oil or air filled type shock absorbers. The mechanical devices accomplish this by a series of hinges and levers attached to the shock absorber mounted under the cushion area of the seat. This allows the impact of the vertical thrust to be transferred to the occupant over a longer period of time, thus reducing the force. The shock absorber also takes the bounce out of the recoil when returning to the original position. This point is critical; not only is it necessary to extend the duration of the impact but also the return from the impact as to not eject the occupant from his seat. 
     A short-coming of the current available high impact seating is that the mechanical devices require substantial space under the cushion area of the seat. 
     Another short-coming of the prior art is that the mechanical devices require maintenance. 
     Another short-coming is that the mounting of these devices is not adaptable for tractors, cars, trucks and boats, and that these devices are too large and heavy for aircraft. 
     A final short-coming of the prior art is the high cost associated with both purchase and installation. 
     OBJECTS 
     Accordingly, several objects of my invention are reduction of force transmitted to the human structure, volumetric space reduction, weight and cost. When a human being is sitting in a moving device such as a boat, plane, tractor, car, etc., there are a variety of forces at work. The primary purpose of this invention is to greatly reduce the force from vertical impact or thrust. Vertical impact is oriented to the human structure whereas the force from centrifugal energy within a moving device (i.e. aircraft, boat, car, etc.) can be horizontal to a gravitational point of reference but still transmit energy through the longitudinal direction of the occupant. This impact causes the greatest injury and/or discomfort, due to the structure of the human body, primarily between the head and the pelvic area, there is a great deal of lateral flexibility. It can not however, be compressed, due to the spinal structure which is nothing more than a stacking of relatively non-compressible bones and cartilage. The organs in the lower abdominal area are also susceptible to damage or injury as a result of sudden and repetitive impact(s). To remove the impact from a vertical motion one must deal with this energy as a function of time. Force equals mass of the human times the acceleration of the vertical lift (F=MA) and acceleration is equal to velocity or speed over time (A=V/T). Thus if the time is extended the acceleration is decreased and finally the force is reduced. (F=M(V/T)) 
     By the use of several densities of foam rubber materials in a precise manner a cushion can be constructed that will take both the shape of the human structure as well as reduce the force due to sudden vertical impact. In the preferred embodiment, this is accomplished by starting with a low density foam in the range of 1.05 to 1.08 with an internal lateral displacement of 18 to 80, that forms to the immediate surface area of the human structure, primarily the buttocks. This is then laminated to a higher density foam in the 1.25 range with an internal lateral displacement of 30 to 36, that spreads the force laterally as well as vertically, taking full advantage of the internal lateral displacement. Further lamination to even higher density and internal lateral displacement might be necessary in some extreme conditions. These two or more layers of foam may be attached by an adhesive through manufacturing or individually to a semi-rigid piece of material i.e. ply wood or sheet plastic, aluminum, metal which is of substantially uniform rigidity throughout. This semi-rigid material will be then placed atop an adhesive to a section of foam of uniform density, the preferred embodiment of which will be of medium density with an internal lateral displacement of 30 to 80. The thickness of each of these layers is contingent upon the total volumetric area available and the average anticipated vertical thrust. Depending on the situation and application, a minimum arrangement would be the use of a medium density to high density foam with an internal lateral displacement of 30 to 80 at a depth of only 2 inches placed atop a low density foam with an internal lateral displacement of 18 to 80 of similar depth with an optional 1/4 inch piece of semi-rigid material separating the two foam rubber pieces. This would be enough to reduce a force by 50% or greater. In this last case of minimum foam area, the internal lateral displacement properties of the foam can by itself disperse the vertical thrust by allowing the higher density foam or semi-rigid foam to transmit its energy to the lesser density foam directly. Accordingly, manufacturing techniques are such that foam rubber could be made so that both the density and internal lateral displacement could be varied within a homogeneous sheet with a straight line progression of softening or hardening through the piece of material. All of these cushions must be placed atop a structure that would support the cushion and occupant. This structure could be flat, curved, rigid or semi-flexible or any combination thereof. These seat structures are commercially available and the adaptability of this invention straightforward and cost effective. 
     As the cushion gets thinner, the ILD of the layers must increase. Therefore ILDs could reach as high as 80 for thin cushions. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an objective of this invention to provide a high and low impact seating through the lamination of multi-layers of foam product with differing densities and internal lateral displacements with an optional rigid or semi-rigid product to greatly reduce the pressure and stress on the human body. 
     It is another objective of the invention to provide high and low impact seating with the ability to be adapted to all existing physical constraints. 
     It is another objective of the invention to provide high and low impact seating with little or no cost increase. 
     It is another objective of the invention to provide high and low impact seating without adding significant weight or size. 
     The attainment of these and related objects may be achieved through the use of the novel multi-layer foam impact seating herein disclosed. 
    
    
     Further objects and advantages of my invention will become apparent from consideration of the drawings and ensuring description thereof. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention: 
     Additional objects and features of the invention will be more readily apparent from the following detailed description and appended claims when taken in conjunction with the drawings, in which: 
     FIG. 1 is a perspective with partial sectional view of the preferred embodiment of a multi-layer high impact seat. 
     FIG. 2 is a plan view of the first preferred embodiment of a multi-layer high impact seat. 
     FIG. 3 is a perspective view of a second embodiment of a multi-layer high impact seat in accordance with the present invention. 
     FIG. 4 is a perspective view of a third embodiment of a multi-layer high impact seat in accordance with the present invention. 
     FIG. 5 is a perspective view of a fourth embodiment of a multi-layer high impact seat in accordance with the present invention. 
     FIG. 6 schematically depicts seats in a moving vehicle in accordance with the present invention. 
     FIG. 7 is a vertical sectional view of a modification. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to those embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     Several preferred embodiments of the invention are present. FIGS. 1 and 2 relate to the first embodiment in which a piece of multi-layer foam is shown. FIG. 3 is the second embodiment in which the form of the seat has been included. FIG. 4 depicts a third embodiment which is similar to the first embodiment, except showing how more layers of foam might be arranged. 
     Referring to FIG. 1, there is shown a piece of multi-layer high impact seat 100 having faces 108, 109, 110 and 111 and top 107 and bottom 107a. The seat 100 in this first preferred embodiment is comprised of layers 101, 102, 103 and 106 of differing densities and internal lateral displacements of foam rubber material. Layered within the layers 102 and 103 is a piece of rigid or semi-rigid material 104. Layer 104 is of substantially uniform rigidity throughout. This rigid material is reduced in width and length but is generally the same size as the foam material so as to provide comfort to the occupant of the seat by means of an over lapping piece of foam rubber 105. The dimension of one implementation of one seat 100 are 2 ft.×2 ft.×43/8 in. The dimensions of layers 102, 103, 105 and 106 are 2 ft.×2 ft.×4 in. The dimension of the rigid material is 1 ft. 111/4 in.×1 ft. 113/4 in.×3/8 in. The dimension of the set back 105 is 3/4 in. The set back 105 in the first embodiment would be an integral part of layer 102 and 106. The sides of the first embodiment 108, 109, 110 and 111, are equal in dimension measuring 43/8 in.×2 ft. The density of layer 101 would be in the range of 1.05 to 1.08 with an internal lateral displacement of 18 to 80. The density of layer 102 and 103 would be in the range of 1.25 with an internal lateral displacement of 30 to 80. It would be allowable to construct these layers of differing densities and internal lateral displacement of either open or closed cell foam rubber, depending on the application. Close cell foam rubber would render the seat cushion as a flotation device which would be an advantage in a marine or exterior application. Other material with similar properties to foam rubber would also be quite suitable for this type of seating. The preferred embodiment is shown placed atop a flat structure 140 which supports the invention. 
     Member 104 spreads force applied to the top layers over generally the entire horizontal area of the lower cushion, which absorbs such forces by lateral displacement of materials in the lower cushion. 
     Referring to FIG. 2, there is shown a plan view of a seat 100. The dimension of this plan view of the first embodiment are 2 ft.×2 ft. with the rigid material set back with a dimension of 1 ft. 111/4 in.×1 ft. 111/4 in. 
     Referring to FIG. 3, there is shown a perspective view of a second embodiment showing possible contours 113 in the portion of the seat 112 which would be placed against the occupant. The construction of this seat would be in the same fashion as the first embodiment with the exception of the higher density of the contour. Layers 114, 115, 116, 117 and 118 would be the same density and lateral displacement as layers 101, 102, 103, 106, and 104 in FIG. 1 in the first embodiment. 
     Referring to FIG. 4, there is shown another perspective of additional layers of foam with still greater diversity in the density and internal lateral displacement. These layers 126, 127, 128, and 129 are dimensionally and functionally the same as 101, 102, 103 and 106 but the additional layers 125 and 130 are dimensionally the same but have lower density and lateral displacements. The example is to show that the comfort of the seat 141 is not limited to the four layer preferred embodiment but can be tailored to an individual&#39;s needs and space requirements. 
     Referring to FIG. 5, there is shown a perspective view of a multi-layer foam product 137 manufactured with a varied density and internal lateral displacement within what appears to be a homogeneous material 132 or 133. With the manufacturing techniques available it is also possible to include the rigid material 134 within this seemingly homogeneous material. This approach would only be feasible for larger production runs. 
     Further referring to FIG. 5, applicant has discovered that excellent results are obtained if lower layer 133 is formed of foam rubber having internal lateral displacement in the range of 20 to 80. It will be understood that the internal lateral displacement may be varied, depending on the weight of the expected user. The heavier the user, the higher the internal lateral displacement number. Rigid member 134 may be assembled with the foam layers or separately installed, as desired. It has substantially uniform rigidity throughout. Upper layer 132 may be of any internal lateral displacement range, within practical limits. 
     As a specific example, layer 132 is preferably 2 ft.×2 ft.×1 in. and of foam rubber with an internal lateral displacement in the range of 20 to 80. Rigid member 134 is preferably 1 ft. 111/4 in.×1 ft. 113/4 in.×3/8 in. and formed of a material such as plywood or particle board. Layer 133 is preferably 2 ft.×2 ft.×1 in. and of foam rubber with an internal lateral displacement in the range of 20 to 80. As previously set forth with reference to FIG. 1, there may be a 3/4 in. set back for the reasons previously stated. The ranges of thickness of layers 132 and 133 may be from 3/4 in. to 4 in. and the lateral ranges may be greater or less than 2 ft., as required 
     Referring to FIG. 6, there is shown a boat 200, with a passenger compartment 202 in which there is at least one passenger seat 210 made in accordance with the present invention. 
     The seat 210 includes a seat base 212 fastened to the boat, and a seat cushion 214 attached on top of the seat base 212. The seat cushion 212 includes multiple cushion layers, as described above. More generally, such seats can be used in any moving device or vehicle so as to reduce impacts on the person associated with vertical movements of the device. 
     FIG. 7 shows a modification in which relatively rigid member 148 is preferably molded or pressed into a shape complementary to that of the buttocks of an average person likely to sit on the cushion. Any suitable material of relatively uniform rigidity, such as plastic or metal, may be used to construct members 148. Layers 146, 147, 149 and 150 may be materials similar to layers 106, 103, 102 and 101, respectively, of the modification of FIG. 1. It will be understood that the top and bottom of the cushion are planar and that the boundary surfaces of the layers are complementary to the shape of relatively rigid member 148. 
     As used in the accompanying claims, the words &#34;vertical,&#34; &#34;horizontal,&#34; &#34;below,&#34; and &#34;on top&#34; are used in the sense of the orientation of FIG. 1 of the accompanying drawings. 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.