Seat Back Structure

Abstract

A seat back structure consisting of a supporting frame and a unitary seating back unit mounted on the frame. The seating back unit consists of a molded foam body of seat back shape having a spring assembly embedded therein. The spring assembly includes a plurality of linear springs which yieldably resist seating loads and a border wire on which the linear springs are mounted. Rearwardly extending projections on the foam body engage the frame so as to provide a space into which the linear springs can deflect when subjected to seating loads. The spring assembly is shaped to conform to the seat back shape of the foam body and cooperates with the foam body to provide added stiffness in the lower back area of the seat occupant.

Description

BACKGROUND OF THE INVENTION

In the seating field, particularly the automotive seating field, a combination of foam and wire spring materials are becoming extensively used. However, past practice has not fully utilized the cooperative capabilities of these materials and complex frames have been required to properly locate the spring material so that it can deflect under load. It is an object of the present invention, therefore, to provide an improved seat back structure which overcomes these objections.

SUMMARY OF THE INVENTION

The seat back structure of this invention includes a frame having side rail and bottom rail portions and a seating back unit consisting of a molded foam body having a spring assembly embedded therein. The spring assembly includes a continuous loop shape border wire having upright side portions disposed adjacent the sides of the foam body and a plurality of vertically spaced linear springs mounted at their ends on the border wire side portions. The rear side of the foam body is provided with projections which seat on the frame rail portions and cooperate to define a space into which some of the linear springs can deflect when subjected to seating loads. In addition, the border wire has a bottom portion which is utilized to stiffen the lowermost linear spring to provide increased firmness in the seating back area of the seat occupant. The front side of the foam body is contoured to a desired seat shape and the spring assembly is shaped to conform to this contour so as to provide for improved cooperation of the foam body and the spring assembly in resisting seating loads. Thus, the seat back structure of this invention can be economically produced to provide improved seating comfort to the seat occupant.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIG. 1 is an exploded perspective view of the seat back structure of this invention;

FIG. 2 is a perspective view of the seat back structure of this invention;

FIG. 3 is a front view of the seating back unit in the seat back structure of this invention, showing the foam body in broken lines;

FIG. 4 is a rear view of the seating back unit in the seat back structure of this invention;

FIG. 5 is an elevational view of one end of the seat back structure of this invention;

FIG. 6 is an elevational view of the other end of the seating back unit in the seat back structure of this invention, with some parts broken away and other parts shown in section for the purpose of clarity;

FIG. 7 is a transverse sectional view of the seating unit in the seat back structure of this invention as seen from substantially the line 7--7 in FIG. 3; and

FIG. 8 is an end view of the seating back unit of this invention as seen from substantially the line 8--8 in FIG. 3, with some parts broken away and other parts shown in section for the purpose of clarity.

With reference to the drawing, the seat back structure of this invention, indicated generally at 10, is illustrated in FIGS. 1 and 2 as consisting of a frame 12 provided with side rail portions 14 and a bottom rail portion 16 and a seating back unit 18 mounted on the frame 12. In the illustrated embodiment of the invention the frame 12 has a headrest 20 mounted thereon and the unit 18 is provided at its top end 22 with a cavity 24 shaped to receive the headrest 20. The unit 18 includes a molded foam body 26 shaped to provide a front side 28 contoured to a seat shape as shown in FIG. 6. A lower portion 30 of the foam body 26 projects forwardly in the lower back area of the seat occupant for a purpose to appear presently.

Embedded in the foam body 26 is a spring assembly 32 consisting of a plurality of vertically spaced linear springs 34 and a continuous loop shape border wire 36 disposed adjacent the side, top and bottom edges of the foam body 26. The linear springs 34 are of corrugated type, namely, either the well known formed wire springs or sinuous springs and are shown as sinuous springs in the illustrated embodiment of the invention. The border wire 36 has generally upright side portions 37 and the linear springs 34 are secured at their ends by conventional clips 38 to the border wire portions 37. The border wire 36 also includes a lower portion 42 and the lowermost linear spring 34 is secured intermediate its ends by a clip 40 to the border wire portion 42. As shown in FIG. 6, the border wire side portions 37 are bent to conform generally to the seat shape of the front side 28 of the foam body 26. As shown in FIG. 8, the lowermost linear spring 34 has forwardly inclined end portions 44 to substantially conform the shape of the lowermost linear spring 34 to the transverse cross sectional shape of the foam body 26. As a result of the configuration of the two lowermost linear springs 34 and the attachment of the lowermost spring 34 to the border wire 36, the unit 18 imparts desirable added stiffness to the lower back area of the seat occupant.

As shown in FIG. 7, the rear side 46 of the foam body 26 is formed with a pair of side projections 48 which terminate in curved surfaces 50 shaped to seat on the side rails 14. The projections 48 thus cooperate to provide a space 52 therebetween into which the intermediate and upper linear springs 34 can deflect when subjected to seating loads. To further insure a correct assembly of the unit 18 with the frame 12 and preserve the space 52, the foam body 26 is provided with a lower projection 54 (FIG. 6) which terminates in a curved surface 56 adapted to seat on the rail 16.

The unit 18 is thus readily assembled with the frame 12 by seating the foam body surfaces 50 and 56 on the rails 14 and 16, respectively, and securing the unit 18 to the frame 12. As shown in FIG. 4, the rear side 46 of the foam body 26 is shaped to fit on and mate with frame 12 so that the frame 12 will provide a firm support for the seating unit 18. A suitable trim material 60 is then applied to the composite frame 12 and seating unit 18 so as to provide the desired finished seat product.

In the use of the structure 10, when seating loads are applied to the front side 28 of the foam body 26, increased resistance is provided to loads in the lower back area of the seat occupant and the desired yieldable resistance to loads is applied above the lower back area by the cooperative action of the foam body 26 and the linear springs 34. The provision of the projections 48 provides the space 52 into which the linear springs 34 in the intermediate and upper areas of the unit 18 can deflect. As shown in FIG. 7, these linear springs 34 are forwardly bowed in their unloaded condition to further enhance the ability of these springs to yieldably resist seating loads. Thus, in the structure 10 of this invention, the foam body 26 and the spring assembly 32 cooperate to provide the desired varying degrees of resistance to seating loads which are conventionally associated with occupant seating comfort.

Claims

What is claimed is:

1. A seat back structure comprising a frame having upright side rail portions, a seating back unit mounted on said frame, said back unit comprising a molded foam body and a spring assembly embedded in said body, said spring assembly comprising a border wire having upright spaced portions and a plurality of linear springs connected to and extending between said upright portions, said body having rearwardly extending molded foam projections disposed adjacent the sides of said body and rearwardly of said linear springs in the unloaded condition thereof, said projections being engaged with said side rail portions so as to locate said springs forwardly of said frame and provide a space between said body and said frame into which said springs can deflect when loaded.

2. The structure according to claim 1 wherein said frame also includes a bottom rail portion and said foam body includes a rearwardly extending molded foam projection at the lower end thereof engaged with said bottom rail portion.

3. The structure according to claim 1 wherein at least some of said linear springs disposed above said lower projection and located between said side projections are forwardly bowed in the unloaded condition thereof.

4. The structure according to claim 1 wherein said side projections terminate in concave surfaces shaped to seat on said side rail portions.

5. In a seating structure, a unitary seating back unit comprising a molded foam body having a front and a rear and a pair of sides, said body being disposed in a generally upright position so that it has a top end and a bottom end, a spring assembly embedded in said body and comprising a border wire having portions thereof located adjacent the sides of said body and a plurality of vertically spaced linear springs connected to and extending between said border wire portions, said body being formed with a pair of rearwardly extending molded foam projections adjacent the sides thereof which are disposed in a spaced relation, said projections cooperating to form therebetween a space into which some of said linear springs can deflect when said springs are subjected to a seating load.

6. A seating back unit according to claim 5 wherein said some linear springs are bowed in a forward direction in the unloaded condition thereof.

7. A seating back unit according to claim 5 wherein said border wire forms a continuous loop in said body and has top and bottom portions connected to said side portions and disposed adjacent the top and bottom ends, respectively, of said body.

8. A seating back unit according to claim 7 wherein the front of said body is of a curved shape in vertical section and wherein said border wire side portions are curved to conform substantially to said shape.

9. A seating back unit according to claim 8 wherein said body is curved to extend forwardly adjacent the bottom end thereof and the lowermost one of said linear springs is secured intermediate the ends thereof to said bottom border wire portion to impart an increased resistance to seating loads to the lower back portion of said unit.

10. A seating back unit according to claim 9 wherein said lowermost one of said linear springs has forwardly inclined end portions.