# Patent

## Title
Seat back assembly with integral reinforcement structure

## Abstract

A seat back assembly including a frame formed of a low density material such as expanded polypropylene (EPP) and a reinforcement structure encapsulated within the frame is provided. The reinforcement structure includes a load transferring surface extending between opposite ends of the seat back. Each end of the reinforcement structure is secured to a vehicle body structure. The reinforcement structure transfers a load placed upon the seat back assembly throughout the frame so as to maintain the structural integrity of the frame under a predetermined load. Specifically, the load transferring surface of the reinforcement structure is in contact with the frame and transfers the load across a predetermined area of the frame and to the vehicle body.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of application Ser. No. 12/339,862 filed on Dec. 19, 2008.


FIELD OF THE INVENTION
The present invention related to a seat back assembly including a frame molded from a low density material such as expanded polypropylene. The seat back assembly further includes a reinforcement structure encapsulated within the frame so as to provide support for the frame and transfer a load throughout the frame and to the vehicle body.
BACKGROUND OF THE INVENTION
Mass reduction in vehicle parts and components lowers the rate of the vehicle's fuel consumption. Thus different materials are considered to form vehicle structure which may be lighter in weight than steel or metal, but yet provide the sufficient structural strength for body support. In particular, it is known to replace metal frames for vehicle components such as seat assemblies with polyurethane, or polypropylene.
Polypropylene has sufficient compression and tensile strength to replace the metal in the manufacture of the seat back assembly frame. Indeed, some vehicle seat backs have done so. Expanded polypropylene (EPP) is generally polypropylene that has been expanded using gas injection during the molding process. EPP has a lower density than polypropylene and thus weighs less than the same volume of polypropylene. Thus it remains desirable to reduce the mass of a seat back assembly by using a frame than is lighter than metal, but yet has sufficient structural integrity so as to withstand the load associated with vehicle operation.
Another aspect of vehicle design is maintaining the structural integrity of a vehicle component during normal operating conditions. In the course of normal vehicle operation, EPP structure may become damaged due to the load. For instance, the interior of a vehicle trunk may experience a load due to articles contained therein shifting during vehicle operation.
In sedan type vehicles, the seat back assembly may back up to the trunk space. As often the case, the trunk space may contain articles such as groceries and the like. These articles may shift while the vehicle is being driven. In some cases, such as a quick stop, the articles may be forced into contact with the seat back assembly. Such a load may damage the seat back assembly.
It is known to protect the seat back assembly from such damage by using a panel made of hardened resin, or metal. In other instances, the seat back frame may be composed of metal and include reinforcement structures such as a bar. In yet another example of a seat back reinforcement is the use of a rib on a panel of a seat back. The rib helps the panel maintain its structural integrity by providing added rigidity to the panel. However such seat assemblies require a substantial amount of mass or are costly to manufacture. Accordingly, it remains desirable to provide a seat assembly with minimal mass and relatively inexpensive to manufacture.
SUMMARY OF THE INVENTION AND ADVANTAGES
A seat back assembly including a frame formed of a low density material such as expanded polypropylene (EPP) and a reinforcement structure encapsulated within the frame is provided. The reinforcement structure includes a load transferring surface extending between opposite ends of the seat back. Each end of the reinforcement structure is secured to a vehicle body structure.
The reinforcement structure transfers a load placed upon the seat back assembly throughout the frame so as to maintain the structural integrity of the frame under a predetermined load. Specifically, the load transferring surface of the reinforcement structure is in contact with the frame and transfers the load across a predetermined area of the frame and to the vehicle body.



BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
FIG. 1 is a view of front of the seat back assembly according to an embodiment of the present invention, showing the reinforcement bar encapsulated within the frame;
FIG. 2 is a view of the back side of the seat back of FIG. 1;
FIG. 3 is an isolated view of an embodiment of the reinforcement structure;
FIG. 4 is a perspective view of the seat back assembly, wherein the back wall of the seat back forms an inner wall of the trunk, the reinforcement structure is secured to the ceiling of the trunk on one end, and the trunk floor on the other end;
FIG. 5 is a perspective side view of FIG. 4 showing trunk cargo advancing towards the seat assembly;
FIG. 6 is a view of a preferred embodiment of the reinforcement structure, wherein the reinforcement structure is generally an “A” shaped frame, the bar extending between the two legs includes mounting brackets for an armrest; and
FIG. 7 is a view of a second preferred embodiment of the reinforcement structure.



DETAILED DESCRIPTION OF THE INVENTION
Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a seat back assembly 10 with a reinforcement structure 12 is provided. The seat back assembly 10 includes a frame 14 constructed from a low density material such as expanded polypropylene (EPP). EPP provides a low mass alternative to metal seat frames 14.
The frame has a contoured outer surface adapted to support the back of an occupant. For instance, the contoured outer surface may include features formed to replicate side bolsters 14a, to help support the side of an occupant. The side bolsters extend beyond the center portion of the frame. A pair of side bolsters may be disposed on opposite ends of the frame, and another pair of side bolsters may be disposed in the mid-section of the frame, on opposite ends of an arm rest 15.
A reinforcement structure 12 is encapsulated within the frame 14 so as to transfer a load. The reinforcement structure 12 is formed of a durable and rigid material such as steel, or a steel composite. The reinforcement structure 12 is operable to translate and diffuse a pointed load throughout the frame 14, so as to prevent the frame 14 from cracking upon application of a pointed load. A pointed load as used herein means a load applied by a pointed end, blunt end or edged section of an object.
With reference now to FIG. 1, a view of the assembled seat back assembly 10 is provided. The seat back assembly 10 may include other features for occupant comforts such as a layer of cushion mounted 17 onto the outer surface of the frame 14. A trim cover 18 may be mounted onto the cushion layer 17. The cushion layer 17 is laid on top of the frame 14 and covered with the trim cover 18.
With reference now to FIGS. 2, 3, 4, and 5, the reinforcement structure 12 has a first end 20 opposite a second end 22. The first and second ends 20, 22 may be mounted to opposing sides of the vehicle, or on the floor 11 of the vehicle 13 as shown in the figures. The reinforcement structure 12 has a load transferring surface 24. The load transferring surface 24 extends between the first and second ends 20, 22. Each end of the reinforcement structure 12 is fixedly secured to the vehicle body structure 26. The frame 14 is mounted above and spaced apart the floor of the vehicle, as shown in FIG. 5.
The portion of the reinforcement structure 12 between the first and second ends 20, 22 is encapsulated wholly within the EPP frame 14. The frame 14 is support above and free of the vehicle body 26. The load transferring surface 24 extends through the mid-section of the frame from the first end to the second end. Thus the load transferring surface 24 is in contact with the frame 14 so as to transfer a load throughout the frame 14 and to the vehicle body 26.
With reference again to FIGS. 4 and 5, the seat back assembly 10 may be mounted in the vehicle so as to form a wall of the trunk 28. Thus, the back surface of the seat back assembly 10 is exposed to loads arising from shifting cargo. The reinforcement structure 12 is provided so as to prevent damage to the seat back assembly 10 as a result of shifting cargo. In particular, the reinforcement structure 12 is configured so as to transfer a load coming from the back of the vehicle towards the front.
The reinforcement structure 12 may be encapsulated within the frame 14 during the molding process using known molding techniques. For instance, the reinforcement structure 12 may be placed in the center of a clamshell mold configured to hold the reinforcement structure 12 in a predetermined position. The EPP may then be injected into the mold so as to encapsulate the reinforcement structure 12 within the frame 14.
The frame 14 is then secured to vehicle body structure 26 so as to provide the reinforcement structure 12 with rigid support. Thus, the load experienced by the reinforcement structure 12 is not only transferred along the load transferring surface 24 to the frame 14, but also to the attached vehicle body structure 26.
With reference again to FIG. 3, a preferred embodiment of the reinforcement structure 12 is provided. The reinforcement structure 12 includes a first leg 32, a second leg 34, and a bar 36. The first and second leg 32, 34 are joined together at one end and are spaced apart from each other at the other end, and the bar 36 extends between both legs 32, 34 so as to form a generally “A” shaped reinforcement structure 12. The load transferring surface 24 of the “A” shaped reinforcement structure 12 is encapsulated within the frame 14. The spaced apart leg portions and the joined leg portions both protrude from the frame 14 and are both fixedly attached to vehicle body structure 26.
The reinforcement structure 12 may include flanges integrally formed to both ends 20, 22 of each leg so as to provide a surface for securing the leg to the vehicle body structure 26. Preferably the reinforcement structure 12 is made of a structural material such as metal or a polymer composite such as carbon and/or glass fiber.
With reference now to FIG. 7, a second preferred embodiment of the reinforcement structure 12 is provided. The reinforcement structure 12 is a generally elongated member 38 that extends between opposite ends of the seat back assembly 10. For instance, the elongated member 38 may extend between opposing wheel wells, or diagonally across the seat back assembly 10 between the bottom of the trunk 28 and top of the trunk 28, or may extend along a generally vertical plane between the bottom of the trunk 28 and top of the trunk 28. The elongated member 38 has a first end 20 opposite a second end 22. A portion of the elongated member 38 is encapsulated in the EPP frame 14, and the first and second ends 20, 22 protrude from the frame and are mounted to the vehicle body structure 26. In particular, the trunk includes a first wall 28a opposite and spaced apart the back side of the seat assembly 10. The first wall 28a extends between opposing side walls of the vehicle. The first and second ends 20, 22 are fixedly mounted to the first wall 28a, accordingly a pointed load placed on the frame is diffused by the load transferring member 24 throughout the body of the frame 14, so as to help prevent the frame 14 from being damaged.
The frame 14 may further include bumpers 14b formed on the back side so as to face the first wall 28a. The bumpers 14b extend beyond the body of the frame 14 and may be formed through injection molding processes. The bumpers 14b are operable to engage the first wall 28a, so as to absorb load and retain a selected distance between the frame 14 and the first wall 28a. 
The reinforcement structure 12 may also include other features such as an armrest bracket 40 for mounting an armrest onto the front side of the seat back assembly 10. With reference now to FIG. 6, the bar 36 of the “A” shaped reinforcement structure 12 includes a pair of spaced apart armrest brackets 40 configured to receive an armrest assembly. As shown in the figure, the reinforcement structure 12 is encapsulated within the frame 14 in such a manner that the armrest bracket 40 protrudes outwardly from the cabin space surface of the seat back assembly 10. The armrest assembly may be mounted thereto.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims.

## Claims

1. A seat back assembly mounted to a vehicle body, the seat back assembly comprising:
a frame formed completely of a low density material selected from the group consisting of expanded polypropylene, expanded polyethylene, and expanded polyurethane, the frame having a peripheral outer edge, a first end portion, and a second end portion opposite the first end portion, the peripheral outer edge defining a body, the body including a contoured outer surface adapted to support an occupant's back; and
at least one reinforcement structure having a first end opposite a second end, the at least one reinforcement structure formed of a rigid material, wherein each of the at least one reinforcement structure includes a load transferring surface extending through the mid-section of the body of the frame from the first end portion to the second end portion, and a portion of the reinforcement structure between the first and second ends of the reinforcement structure is fully encapsulated within the expanded polypropylene frame and the first and second ends of the at least one reinforcement structure protrudes from the respective first end portion and second end portion of the body of the frame, the first and second ends are secured to opposing portions of the vehicle body, the reinforcement structure positioning the frame above a floor of the vehicle body, and wherein the peripheral outer edge of the body is spaced apart from the vehicle body.

2. The seat back assembly as set forth in claim 1 wherein the reinforcement structure is a generally elongated member extending between opposite ends of the seat back assembly.

3. The seat back assembly as set forth in claim 1, wherein the vehicle body includes a trunk having a first wall, the frame spaced apart and opposite the first wall, the first and second ends of the reinforcement structure are mounted to the first wall.

4. The seat back assembly as set forth in claim 3, wherein the frame further includes at least one bumper, the bumper formed on the outer surface of the frame and facing the first wall.