Seat back assembly with low density frame

The present invention is related to a seat back assembly having a frame molded from expanded polypropylene and having a standoff registered to engage a vehicle body structure.

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 flame. 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. Accordingly, 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.

Seat back assemblies contain numerous parts. For instance, a seat back assembly with a pivotable armrest requires a bracket for which the armrest pivots about. The bracket must be further fixed to the seat back assembly. It is known to fix the armrest bracket to the metal frame. This increases production costs as the armrest bracket must be welded to the frame. Further, the armrest bracket must have a planar surface large enough to apply the spot welder to. Thus it remains desirable to have a seat back assembly that requires less mass than that of the prior art seat back assemblies, but yet retains comfort features such as an armrest, headrest, and the like.

A seat back assembly including a frame molded from expanded polypropylene (EPP), and a headrest integrally formed with the frame. The expanded polypropylene frame includes a first surface and a second surface. A cushion body is mounted onto the first surface. The seat back assembly is also molded to include a standoff. The standoff extends outwardly from the second surface into a contact surface. The contact surface is registered to engage a vehicle body structure when the seat back experiences a frontal load so as to transform the frontal load to compress the standoff, and wherein the standoff further transfers a load to the vehicle body structure.

The seat back assembly further includes other structure encapsulated within the EPP frame, to include a pair of attachment wires. Each of the attachment wires includes a base portion and a hook portion. The base portion is encapsulated within the expanded polypropylene frame and the hook portion protrudes from the EPP frame so as to secure the seat back assembly to the vehicle body.

An armrest bracket is also encapsulated within the EPP frame. The armrest bracket includes a first portion and a second portion. The first portion is encapsulated within the EPP frame so as to transfer a load placed on the armrest bracket along the first portion and into the EPP frame. The second portion is configured to pivotably hold an armrest.

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 taken from the front of the seat back assembly according to an embodiment of the present invention, the seat back assembly includes a frame made of EPP, a cushion body mounted onto the frame, a trim cover fitted over the cushion body, and a pivotable armrest is in a stowed position;

FIG. 2 is shows the cross-section of FIG. 1 taken along lines 2 - 2 ;

FIG. 3 view of FIG. 1 showing the seat back assembly without the cushion body or trim cover, the figure also includes a hidden view of the armrest bracket and a portion of the attachment wires both encapsulated within the EPP frame, thus minimal parts are need to support the armrest and attachment wires;

FIG. 4 is a view of FIG. 3 showing the pivotable armrest in the use position;

FIG. 5 is an isolated view of the armrest bracket, a portion of the armrest bracket is encapsulated within the EPP frame (seen by the dashed lines), while the mounting portion, which is configured to pivotably fix the armrest, is exposed;

FIG. 6 is a view taken from the back of the seat back assembly showing the contact surfaces of the standoffs, and cutouts;

FIG. 7 is a view of an embodiment of the standoff and reinforcement structure, as shown the standoff is registered to engage the reinforcement structure when the seat back assembly experiences a frontal load;

FIG. 8 is a view of the seat back assembly secured to the trunk of the vehicle, the second surface of the EPP frame defines a trunk wall; and

FIG. 9 is a view of another embodiment of the standoff, wherein the standoff has a shape complimentary with the shape of the vehicle reinforcement structure.

Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a seat back assembly 10 including a frame 12 formed of a low density material such as expanded polypropylene (EPP) is provided. Expanded polypropylene has a lower density than conventional frame 12 material such as polypropylene and metal. The seat back assembly 10 may further include a cushion body 14 mounted onto the EPP frame 12 so as to provide comfort, and a trim cover 16 fitted over the cushion for aesthetics, as shown in FIG. 1 . A cross section of the seat back assembly 10 is provided in FIG. 2 to show the different layers. The seat back assembly 10 includes standoffs 18 so as to transfer a frontal load to a vehicle body structure 20 and transform the frontal load into the compression of the standoffs 18 . The standoffs 18 of the EPP frame 12 provide rigid support for the occupant, and the EPP reduces fuel consumption because of its low density.

The EPP frame 12 may be molded in a clam shell mold, using known molding techniques. The molded EPP frame 12 includes a first surface 22 and a second surface 24 , also referenced herein as a front surface 22 and a rear surface 24 . A center portion 23 is between the front and rear surfaces 22 , 24 . The cushion 14 is mounted to the second surface 24 , and the second surface 24 is molded so as to include at least one standoff 18 .

With reference now to FIG. 3 , the EPP frame 12 may be contoured to accommodate the natural contours of a human back, and include other features for occupant support. For instance, the EPP frame 12 may be molded so as to have side bolsters 26 . The EPP frame 12 may also be molded so as to form an integral headrest 28 . The headrest 28 includes a head support body 30 and a pair of flanges 32 extending radially from the head support body 30 . The flanges provide support for a head cushion.

The EPP frame 12 may further include an armrest compartment 34 configured so as to store an armrest 36 . Preferably the armrest 36 is also formed of EPP and is pivotably attached to the armrest 36 frame 12 and may also be cushioned and covered with a trim cover 16 . The armrest 36 may be molded so as to include a storage compartment 38 for articles such as coins. The armrest 36 is movable between a use position, as shown in FIG. 4 and a stowed position as shown in FIG. 3 . When the armrest 36 is in the stowed position, the body of the armrest 36 is nestled within the compartment and when the armrest 36 is in the use position the storage compartment 38 is accessible.

With now to FIGS. 5 and 5 a , an armrest bracket 40 encapsulated within the EPP frame 12 is illustrated. The armrest bracket 40 has plate 41 presenting a planar surface 42 in contact with the EPP frame 12 so as to transfer a load placed on the armrest bracket 40 along the planar surface 42 and into the EPP frame 12 , and an armrest 36 pivotably attached to the armrest bracket 40 . The armrest bracket 40 includes a mounting portion 43 integral to the planar surface 42 . The mounting portion 43 is exposed so as to be able to receive the armrest bracket 40 .

With reference now to FIG. 6 , the standoff 18 extends outwardly from the second surface 24 into a contact surface 44 . The seat back assembly 10 may further include cut-outs 46 so as to reduce the mass of the seat back assembly 10 . With reference now to FIG. 7 , the contact surface 44 is registered to engage a vehicle body structure 20 when the seat back experiences a frontal load so as to transform the frontal load into compression. Meaning, when a load coming from the front of the vehicle impacts the seat back assembly 10 , the seat back assembly 10 is pushed backwards such that the contact surface 44 of the standoff 18 engages the vehicle body structure 20 . The standoff 18 also transfers the frontal load to the vehicle body structure 20 .

With reference now to FIG. 8 , the seat back assembly 10 may be mounted onto the back of the vehicle to form the rear seats. Thus, the second surface 24 of the seat back assembly 10 forms a wall defining the interior trunk space. With reference again to FIG. 6 , the seat back assembly 10 may further include at least one attachment wire 48 . The attachment wire 48 has a base portion 50 and a hook portion 52 . The base portion 50 is encapsulated within the EPP frame 12 and the hook portion 52 protrudes from the EPP frame 12 so as to secure the seat back assembly 10 to the vehicle body. Specifically, one of the attachment wires 48 is configured to secure the seat back assembly 10 to the floor of the vehicle's trunk, while the other attachment wire 48 is configured to secure the seat back assembly 10 to the upper back panel.

As stated above, the seat back assembly 10 is secured to the vehicle such that the standoff 18 is registered to engage a vehicle body structure 20 , particularly a reinforcement structure 21 of the vehicle body. The reinforcement structure 21 may be a bar extending between the trunk floor 54 and the trunk ceiling 56 , or may extend transversally across the trunk between the rear wheel wells (not shown). For illustrative purposes, the reinforcement structure 21 is shown as a generally “V” shaped frame 12 and wherein the standoff 18 is also generally “V” shaped. The reinforcement structure 21 is secured to the vehicle body at both ends so as to transfer load throughout the vehicle body.

As shown in FIG. 9 , the standoff 18 may have a shape complimentary with the shape of the reinforcement structure 21 . Thus, the contact surface 44 of the standoff 18 be pressed against the reinforcement structure 21 under a predetermined frontal load such that the contact surface 44 is generally flush against the reinforcement structure 21 .

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.