The present invention is generally related to modular composite seat back frames for use in passenger seat assemblies.
In the airline industry, conventional seats and seat back frames have been formed from metals such as aluminum. Such conventional frames have a number of drawbacks. For example, they have numerous and costly components that contribute to excessive assembly time and increased cost. Also, they are often difficult to form the complex geometry required by to accommodate both the contours of the passenger as well as any devices such as trays, phones, monitors, and the like. Furthermore, the overall weight of each conventional frame increases the overall weight of an airplane, thereby decreasing fuel efficiency.
While there have been attempts to replace aluminum with composite materials, those materials have not achieved the desired properties possessed by aluminum. For example, such composite materials exhibit limited stiffness properties in comparison to aluminum and do not satisfy necessary safety standards. While material stiffness can be compensated to some degree by shaping the components to enhance structural stability, the composite materials still lack the appropriate stiffness and therefore do not offer the potential for necessary improvements in structural performance. Furthermore, such composite materials are typically thermosets that could pose potential safety issues regarding use on airplanes.
For composites to be correctly utilized in airplane seats and seat backs, the composite structure as well as the design and configuration of the composite parts comprising the seat or seat back must be combined in a way that takes advantage of their physical properties.
The invention is particularly directed to a seat back for use in airplanes and airplane applications made from a composition including carbon fiber and a thermoplastic. In one aspect, a seat back is provided having a composite body having a first end, a center section, and a second end that is thicker than the center section. The first end, the center section, and the second end comprise a plurality of layers of highly aligned fibers in a thermoplastic matrix. The seat back also is provided with a member extending outwardly from the second end and a leg secured along at least a portion of the second end. The leg is positioned along the member to form a cavity defined by the second end, the member, and the leg, the cavity capable of receiving a connecting rod for connecting the seat back assembly to a seat.
In another aspect, a seat back is provided having a body comprising a first end, a second end, a center section between the first end and the second end, a top section adjacent the center section and between the first end and the second end, and a bottom section adjacent the center section, opposite the top section and between the first end and the second end. The seat back is also provided with a first member extending outwardly from the first end, a second member extending outwardly from the second end, a first leg secured to said first end and positioned along the first member, and a second leg secured to the second end and positioned along the second member to define a cavity capable of receiving a connecting rod for connecting the seat back to a seat. Each of the body, the first member, the second member, the first leg, and the second leg comprise a plurality of layers of highly aligned fibers in a thermoplastic matrix, and at least one layer having said highly aligned fibers oriented at a different angle than the highly aligned fibers of another layer.
Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
While the present invention is described with reference to embodiments described herein, it should be clear that the present invention is not limited to such embodiments. Therefore, the description of the embodiments herein is merely illustrative of the present invention and will not limit the scope of the invention as claimed.
As generally described herein,
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One or more walls are provided that extend outward from the anterior surface 40 of the body 20.
In an illustrative example, as best shown in
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The seat back 10 may also vary in thickness to provide greater strength and stiffness where needed, while minimizing the overall weight. In an embodiment shown in
In a non-limiting example as shown in
One or more legs 30 may also be provided with different thicknesses. For example, a lock-side leg 30 may have a thickness of about 0.08″ to about 0.10″, and preferably about 0.09″. A non-lockside leg 30 may have a thickness of about 0.05″ to about 0.065″, and preferably about 0.055″. Accordingly, the lock-side leg 30 provides the strength necessary to secure the seat back 10 to a seat assembly (not shown) and minimizes the overall weight of the assembly. In a non-limiting example (not shown), the first member 150, the second member 160, and the lip 170 of the leg 30 may also vary in thickness.
It is also to be understood that the walls 115, 120, 125, and 130 may also vary in thickness. In one illustrative example, the walls 115, 120, 125, and 130 may have the same thickness as the section 60, 70, 80, 90, to which they are positioned on or adjacent to. For example, as shown in
In addition, the seat back 10 may include one or more members 185 to provide additional strength or stiffness properties to the seat back 10. The members 185 can be of any geometric shape and may be secured to, stamped, molded, or otherwise formed on the anterior surface 40 and/or posterior surface 50. While
The seat back assembly 10 is formed from a composite material. As used herein, the term “composite” is defined as highly-aligned reinforcements of carbon, glass, aramid fibers, and the like in a suitable polymer matrix of a thermoplastic resin. The composite material preferably includes one or more ply layers, each ply having substantially unidirectionally aligned continuous fibers of carbon, glass, or aramid fibers in a polymer matrix of thermoplastic resins. Thermoplastic resins include, but are not limited to, polybutyleneterephthalate (PBT), polyphenylene sulfide (PPS), polysulfone (PS), polypropylene (PP), polyethylene (PE), ABS resin, thermoplastic elastomer, or composite materials of these thermoplastic resins.
Thermoplastic composites are reinforced with high-strength, high-modulus fibers that provide dramatic increases in strength and stiffness, toughness, and dimensional stability. Advantages of using thermoplastic composites as opposed to thermoset composites are their superior impact and damage resistance properties, high toughness and ease of recycling, which is increasingly important in the airline industry.
In contrast, thermoset composites are inherently brittle and cannot be usefully recycled. For instance, an advanced thermoplastic composite component can be chopped to pellet-size and injection-molded to yield long-fiber reinforced moldings, which can in turn be recycled at the end of their life. Thermoset composite materials, in contrast, can only be ground and used as filler, a process that decreases the value of the composite enormously. There are also environmental issues associated with thermoset processing, as a chemical reaction is necessary to form the solid structure of the polymer (e.g., impregnation of the fibers is followed by chemical curing to give a solid structure, which is usually carried out isothermally). In contrast, with thermoplastics, the molding can be carried out non-isothermally (e.g., a hot melt into a cold mold) in order to achieve fast cycle times.
To prepare the composite material, the thermoplastic resins are compounded with composite or reinforcement materials, such as carbon fibers, glass fibers, or metal, so as to improve heat resistance, dimensional stability and rigidity. Glass fiber reinforced composites improve both short-term and long-term mechanical properties of a resin, including tensile modulus, dimensional stability, hydrolytic stability, and fatigue endurance. Deformation under load of these stiffer materials is also reduced significantly. Aramid fiber reinforced composites have low warpage, excellent wear and abrasion resistance, low coefficient of friction, and low thermal expansion. In addition, the mechanical properties of the aramid composites are relatively uniform in all directions. Although, aramid fibers are stronger on a weight basis than steel or aluminum, they are not as easy to work with as compared to glass and carbon.
Carbon fiber composites have superior fatigue properties to known metallic structures, and when coupled with the proper resins, carbon fiber composites are one of the most corrosion resistant materials available. Carbon fiber is used to create materials that can withstand extremely high temperatures along with significant abrasive wear. Carbon fiber composites are stronger than steel, yet lighter. In comparison to aluminum, carbon fiber composites are stronger, stiffer and lighter. Carbon fiber reinforced materials, at two to four times the cost of comparable glass-reinforced thermoplastics, offer the ultimate in tensile strength, stiffness, and other mechanical properties. Compared to the glass-reinforced materials discussed above, these compounds have a lower coefficient of expansion and mold shrinkage, improved resistance to creep and wear, and higher strength-to-weight ratios.
Accordingly, the seat back 10 preferably includes carbon fibers added to thermoplastic resins to provide the highest strength, modulus, heat-deflection temperature, creep, and fatigue-endurance values available in composites. These mechanical property improvements, coupled with increased thermal conductivity and low friction coefficients, make carbon fibers ideal for wear and frictional applications. In applications where the abrasive nature of glass fibers wears the mating surface, the softer carbon fibers can be substituted to reduce the wear rate. In general, carbon fibers have a length of at least 50 meters, and may be as long as a kilometer or more. Typically, continuous carbon fibers have an average fiber diameter ranging from approximately 4 micrometers to 12 micrometers. Carbon fibers are marketed under various trade names. For example, one suitable carbon fiber is from Zoltek Corporation of St. Louis, Mo., and has the trade name “Panex 35.” In an illustrative example, the fiber volume fraction is about 0.5 to about 0.7, and preferably about 0.58.
In an embodiment, the body 20 and walls 115, 120, 125, 130 may be integrally formed from a composite blank. The composite blank includes several layered plies with substantially unidirectionally aligned continuous length carbon fiber. The plies are configured so that the carbon fibers of at least one ply are oriented at a different angle than the carbon fibers of at least one other ply. The blanks may also be configured so that different portions have different numbers of ply layers, thereby allowing for thickness variations thereacross. In an illustrative example, the thickness per ply may be about 0.0075″ to about 0.0095″, and preferably about 0.008″.
In an embodiment, as shown in
It is to be understood that each portion 205, 210, 215, 220 of the blank 200 may have a different number of ply layers. In a non-limiting example, the first portion 205 includes three ply layers, the second portion 210 includes six ply layers, the third portion 215 includes eight ply layers, and the fourth portion 220 includes eight ply layers.
It is also understood that the carbon fibers of a ply may be aligned in a variety of orientations with respect to the carbon fibers of one or more other plies. As defined herein, 0° is taken along the centerline of the longitudinal axis of the blank 200 toward the top portion 220; −90° is defined as perpendicular to the 0° axis, from the central axis toward the second portion 210; 90° is defined as perpendicular to the 0° axis, from the central axis toward the third portion 215.
In a non-limiting example using the above referenced number of ply layers for each portion 205, 210, 215, 220, the first portion 205 includes a first ply having carbon fibers oriented at about 40° to about 60°, and preferably at about 50°; a second ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; and a third ply having carbon fibers oriented at about −40° to about −60°, and preferably at about −50°.
The second portion 210, which may be the non-lock side in the present example, includes a first ply having carbon fibers oriented at about −10°to about 10°, and preferably at about 0°; a second ply having carbon fibers oriented at about 40° to about 60°, and preferably at about 50°; a third ply having carbon fibers oriented at about −40° to about −60°, and preferably at about −50°; a fourth ply having carbon fibers oriented at about −40° to about −60°, and preferably at about −50°; a fifth ply having carbon fibers oriented at about 40° to about 60°, and preferably at about 50°; and a sixth ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°.
The third portion, which may be the lock-side portion, includes a first ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; a second ply having carbon fibers oriented at about 40° to about 60°, and preferably at about 50°; a third ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; a fourth ply having carbon fibers oriented at about −40° to about −60°, and preferably at about −50°; a fifth ply having carbon fibers oriented at about −40° to about −60°, and preferably at about −50°; a sixth ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; a seventh ply having carbon fibers oriented at about 40° to about 60°, and preferably at about 50°; and an eight ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°.
The fourth portion 220 has a first ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; a second ply having carbon fibers oriented at about 30° to about 50°, and preferably at about 40°; a third ply having carbon fibers oriented at about −30° to about −50°, and preferably at about −40°; a fourth ply having carbon fibers oriented at about 90°, a fifth ply having carbon fibers oriented at about 90°, a sixth ply having carbon fibers oriented at about −30° to about −50°, and preferably at about −40°; a seventh ply having carbon fibers oriented at about 30° to about 50°, and preferably at about 40°; and an eighth ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°.
In an illustrative example, the leg 30 may be formed from a second blank 230. For example, a lock-side leg blank 230 for connecting to the body 20 along a lock-side section, such as the second section 70, may have eleven ply layers. In such a non-limiting example, a first and a second ply have carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; a third ply having carbon fibers oriented at about 47° to about 67°, and preferably at about 57°; a fourth ply having carbon fibers oriented at about −47° to about −67°, and preferably at about −57°; a fifth, a sixth, and a seventh ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; an eighth ply having carbon fibers oriented at about −47° to about −67°, and preferably at about −57°; a ninth ply having carbon fibers oriented at about 47° to about 67°, and preferably at about 57°; and a tenth ply and an eleventh ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°.
In an illustrative example, a non lock-side leg blank, similar to leg blank 230, may be provided for forming a non-lock side leg for connecting to the body 20 along a non lock-side section, such as the first section 60. Such a leg blank may have seven layers. A first ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; a second ply having carbon fibers oriented at about 47° to about 67°, and preferably at about 57°; a third ply having carbon fibers oriented at about −47° to about −67°, and preferably at about −57°; a fourth ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°; a fifth ply having carbon fibers oriented at about 47° to about 67°, and preferably at about 57°; a sixth ply having carbon fibers oriented at about −47° to about −67°, and preferably at about −57°; and a seventh ply having carbon fibers oriented at about −10° to about 10°, and preferably at about 0°.
In one illustrative example, the plies are formed from carbon fiber tape infused with a thermoplastic resin. However, it is to be understood that numerous processes may be used to prepare the blanks 200 and 230 for fabricating the seat back 10. For example, U.S. Pat. No. 6,939,423, herein incorporated by reference in its entirety, describes a process for making composite blanks that may be used to form blanks 200 and 230 for fabricating the seat back 10. The blank making process generally includes a ply-layering step followed by a consolidation step. A brief, non-limiting summary of the process is provided below.
The layering step generally begins by selecting the materials to be used in making the composite part, as discussed above. At least one material placement station is provided for distributing the materials onto a conveyor into the desired layering and carbon fiber orientation. To accommodate such distribution, each material placement station can be moved in a direction that is different than the direction of motion of a conveyor. For example, the placement stations can move in a direction that is perpendicular to the motion of the conveyor. The stations may include a plurality of heads that are disposed in a direction similar to the direction of motion. Each of the heads includes a rotating portion that permits the head to dispense a material in a variety of directions relative to the head.
The material placement stations are able to dispense a plurality of materials. It is to be understood that the starting materials may be either dry fiber and resin or pre-impregnated tape. By selectively rotating heads and moving the placement station, the material can be dispensed in a variety of orientations and directions. It is to be understood that different placement stations may dispense material in directions different than one another. In addition, the material dispensed by the heads can be turned on or turned off when desired. Accordingly, the heads feed, heat, and position the materials to create a ply. A laminate is formed by layering plies on top of each other. The placement heads can also allow for the starting and stopping of the materials to allow for cutouts, thereby reducing scrap, which is a significant source of cost.
The number of stations required is determined by the desired production rate, the number of plies, angles, and special details, and the selected starting material form. Each head would lay down a single ply at a given angle. Once a given point on the belt has moved through all the activated placement stations, the result is a laminate of the desired combination of number of plies and respective angles, optionally including other special reinforcements.
The consolidation step generally comprises a series of heated consolidation rollers that compresses the laminate stack to a desired level of consolidation and thickness. A variation of this approach is to place binderized tows into a band of highly aligned dry fibers at the prescribed angle. Binderizing powders (a resin powder that is chemically compatible with the intended matrix resin) could be deposited between the plies as well, if required. After the final ply is laid down, a thermal compaction step could be applied to hold the fibers in their proper position prior to subsequent processing steps. The resultant sheet could then be cut and kitted if it is destined for a liquid infusion fabrication process. If the material is to be used in a stamping operation, an additional step of liquid infusion and consolidation, much like a pultrusion or extrusion process, could be applied to fully impregnate and consolidate the laminate prior to cut and kit. This kit could then be used in a solid state stamping fabrication process. Consolidation if required, would be performed at the end of the laminating operation using a series of heated and cooled rollers or heated and cooled platens. This step would be tailored to the intended final fabrication process.
Regardless of the end use (e.g., liquid infusion molding, solid state stamping, etc.), the laminated stack can be cut and kit into predefined bins for delivery to the final processing cell. Additional elements of the final component, such as adhesives sheets, colored decals, or fittings, etc., could be added to the bins prior to delivery to the final processing cell.
The component fabrication step includes a pre-processing and molding station. A pre-heat shuttle would be utilized to heat the laminate stack to the desired temperature and then rapidly shuttle the stack between the tools in the stamping press. The second station, a single stage heated stamping die, will clamp the perimeter of the laminated sheet and stamp the component. After stamping, the stamping tool is rapidly cooled from 220° Celsius to below the glass transition temperature and then demolded. Final trim operations can involve high speed routing in vacuum chucked jigs for high performance advanced composite structures.
The invention has been described above and, obviously, modifications and alternations will occur to others upon a reading and understanding of this specification. The claims as follows are intended to include all modifications and alterations insofar as they come within the scope of the claims or the equivalent thereof.
This application claims benefit to Provisional Application No. 60/928,887 filed on May 11, 2007, which is hereby incorporated in its entirety by reference.
Number | Date | Country | |
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60928887 | May 2007 | US |