Seat back for vehicle seats

In the case of a seat back for vehicle seats, in particular motor vehicle seats, with two side outriggers (1), which consist of a back and front support (3,4), which are connected in the area of their lower end section through a connecting body (5) and above the connecting body to each other, both the front support (4) and the back support (3) continue into the transverse spar (2), which connects the side outriggers (1) to each other in the area of its upper end. The front support (4) lies above the connecting body (5) and below the transverse spar (2) on a piece of its segment on the back support (3). On transverse parts (6,7) of the back and front supports (3,4) that extend from one side outrigger (1) to the other in the area of the transverse spar (2) are positioned at an interval from one another over each other. Both transverse parts (6,7) are connected to each other so they are rigid by means of a separator (8) abutting on them.

BACKGROUND OF THE INVENTION 
The invention relates to a seat back for vehicle seats, in particular motor 
vehicle seats. 
In the case of a known seat back of this type (DE 43 03 006 A1), each of 
the two front supports on the outside of the corresponding back supports 
is led through to a transverse spar, which connects the upper end of both 
front supports to each other and abuts on the back side of the back 
supports. Because of both the arrangement of the supports and the 
transverse spars and the connection of each of the two front supports to 
the corresponding back supports by means of two connecting plates in the 
area of its lower sides, the seat back's stability under load leaves 
something to be desired. 
OBJECTS AND SUMMARY OF THE INVENTION 
A primary object of the invention is to provide a seat back of the type 
just mentioned, with which it is possible to obtain greater stability 
under load than conventional seat backs without making the seat back 
heavier. Other objects and advantages of the invention will become 
apparent from the description and drawings which follow. 
In the case of a preferred working form of the invention, the separator, 
which connects the transverse parts of both supports to each other, is 
designed as a holding device for a headrest that makes a separate headrest 
holding device unnecessary. Advantageously, the transverse parts of the 
two supports are provided with a flattened out segment on both of their 
front sides, which lie on a common level and form a bearing surface for 
the separator. In so doing, it is easy to obtain a definite position of 
the separator, as well as a highly stable connection between it and the 
transverse parts. The transverse part of the back supports lies, 
advantageously, under the transverse part of the front support. 
Both due to production considerations and for greater stability under load, 
the two connecting bodies, which connect the lower end sections of the 
supports to each other, are as cast bodies that are each provided with two 
channels for taking up the lower end of the front and back support. The 
seat back obtains an especially high stability under load in the area of 
the connecting bodies because it has an extension piece, which is formed 
on the material parts lying between the channels and which projects 
upwards in such a way that it props both supports against each other. For 
the purpose of obtaining a favorable relation between stability under load 
and weight, this extension piece has, preferably, a double T-shaped 
profile section, whereby both transverse bars abut on the front and back 
supports. 
Again, for the purpose of obtaining a favorable relation between stability 
under load and weight, the supports are formed by hollow members, e.g., 
pipes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The supporting structure of the seat back of a motor vehicle seat displays 
a side outrigger (1) on each side of the back rest. Both side outriggers 
(1), which are designed the same and are mirror-inverted, are connected to 
each other through an upper transverse spar (2) in the area of their upper 
ends. Each of the two side outriggers (1) consists of a back support (3) 
and a front support (4), which are connected to each other by a connecting 
body (5) in the area of their lower end section. 
As shown in FIG. 1, the back support (3) first extends upwardly from the 
connecting body (5) in a straight line and then angles towards the back. 
At the bend, the back support (3) is also bent inward--that is, it is 
lightly bent against the other side outrigger (1), as is shown in FIG. 2. 
By way of a hollowing, the back support (3) merges with a transverse part 
(6) that runs horizontally and is formed as one piece with it. In the area 
of its lower end section, the front support (4) forms an angle with the 
back support (3) that opens upwardly and then, as FIG. 1 shows, follows a 
curve towards the back--forming an acute angle that opens downward--before 
running in a straight path--albeit one that is inclined toward the back. 
Just after the bend in the back support (3), the front support (4) is 
installed on the back support (3). There it is welded inward to the back 
support (3) on a segment running up to the beginning of the bend. Above 
this welded segment a inward curve is provided, which, however, is not as 
sharply curved as the curve of the back support (3). A transverse part 
(7), which is formed as one piece with the front support (4) and merges 
with the front support (4), is positioned above the transverse part (6) at 
a distance from it, as FIG. 1 shows. 
Both transverse parts (6 and 7) are rounded on their front side. These two 
flattened out segments (6' and 7') lie on a common plane and serve as 
bearing surfaces for a separator (8), which is welded to both transverse 
parts (6 and 7) and form with them the upper transverse spar (2). As FIG. 
4 shows particularly well, the separator (8) is designed as an extruded 
section, which serves not only as a connection for the two transverse 
parts (6 and 7), but also as a holding device for a headrest. For this 
reason, the two side end sections of the separator (8)--each having a 
guide bore (9) for taking up a support rod--is provided with a headrest. 
The weld seams, which connect the separator (8) to the two transverse 
parts (6 and 7), are designated as 10. 
As FIG. 5 especially shows, the two connecting bodies (5), which are 
designed the same and mirror-inverted (in the working examples they are 
casting bodies or a press object made from a magnesium alloy), are 
provided with two channels (11) for taking up the end sections of the back 
support (3) or the front support (4). From the middle part of the 
connecting bodies (5) that form these two channels (11) an embracing 
hook-formed part (12) extends downwards behind the swivel pin of the seat 
back. The hook-shaped part serves to connect both side outriggers (1) to 
the lower transverse spar. On the upper side of the middle section that 
has the channels (11) an extension part (14) is formed, which extends 
upwards in the area lying between the two channels. This extension part 
(14), formed as one piece with the middle part, has, as FIG. 4 shows, a 
double T-shaped profile section. Between the two transverse bars (14' and 
14") and the front side of the back support (3) and the back side of the 
front support (4) a functional clearance exists. The front support (4) is 
thus supported from behind when stressed in the area of its curve; the 
back support (3) is supported from the front at the extension part (14) 
when stressed--which contributes to a considerable increase in the seat 
back's stability under load both towards the front and the back. Because 
of the curving of the front support (4), the transverse bar (14") lying on 
it has a corresponding curve. 
Due to weight considerations, the supports and transverse parts are made of 
pipes. 
For the installation of the upper mounting parts of a joint fitting (built 
in the normal fashion and therefore not shown in the diagram) several 
cover strips (16), formed as one piece with the connecting body (5), 
define a level bearing surface. Screws, which are not shown, penetrate the 
upper mounting parts of the joint fitting, which connects the side 
outrigger to the seat, and connect the side outrigger to the connecting 
body (5). A material part (17) of the connecting body (5), which is 
trapezoidal in the working example, projects from above into a 
correspondingly formed recess of the upper mounting part and forms--alone 
or together with one of the gradations bordering the edge of the bearing 
surface--an additional form-fit connection for the forces directed towards 
the back or the front. 
A flat support (15) is fastened on both back supports (3). On it and on the 
upper transverse spar (2) and the sidewall supports formed by the two side 
outriggers (1), there is a cushion that is not shown in the diagram, which 
is covered by a covering that is also not depicted. 
The connection of the seat back to the supporting structure of a seat takes 
place through two joint fittings, whose mounting part is connected to one 
or the other side outrigger (1). The upper mounting part abuts on the side 
of the middle part of the connecting body that is visible in FIG. 5, which 
overlaps the upper mounting part on the side and top. Feeding forces from 
the side outrigger (1) into the joint fitting therefore takes place not 
only by means of screws or something similar, which connect the upper 
mounting parts to the connecting body (9); the material parts of the 
connecting body (5) overlapping the upper mounting part on the sides and 
top also contribute to a highly stable connection. 
Although certain presently preferred embodiments of the present invention 
have been specifically described herein, it will be apparent to those 
skilled in the art to which the invention pertains that variations and 
modifications of the various embodiments shown and described herein may be 
made without departing from the spirit and scope of the invention. 
Accordingly, it is intended that the invention be limited only to the 
extent required by the appended claims and the applicable rules of law.