Back rest for a vehicle seat

In a back rest for a vehicle seat, the upholstery support is provided at least in one upper corner area in its front side with an opening to form a receptacle for a belt retraction device, which receptacle is open toward the front and closed at the rear by a back wall lying behind and spaced from the front side. An upper and a lower wall, which form the top and bottom of the receptacle, are connected with the front wall and/or the back wall and are spaced from each other so as to allow the receptacle to receive the belt retraction device without play. Form-fitting, overlapping restraining elements on the upper wall and the facing upper side of the belt retraction device, as well as on the back wall and the facing back side of the belt retraction device, together with a connecting element that engages the underside of the belt retraction device, secure the retraction device against being moved out of the receptacle.

BACKGROUND OF THE INVENTION 
The present invention relates to a back rest for a vehicle seat, 
particularly a motor vehicle seat, the upholstery support of which 
includes a back wall and side walls at least in its upper corner areas. 
Generally speaking with motor vehicle seats, the seat belt of a three-point 
safety belt passes through the buckle and its free end of the lap belt 
portion is connected with the vehicle seat. The shoulder strap portion, in 
contrast, leads to a pillar or other point on the vehicle body. This is 
also the case with a seat having a known back rest of the above-described 
type (DE-PS No. 35 21 402), although the upholstery support of this known 
back rest has a very high loading capacity. 
SUMMARY AND OBJECTS OF THE INVENTION 
In view of the foregoing limitations and shortcomings of the prior art 
devices, as well as other disadvantages not specifically mentioned above, 
a primary object of the invention is to create a back rest in which a belt 
retraction device of a safety belt can be attached to the upholstery 
support in the simplest possible manner and with the requisite load 
carrying capacity. 
Beginning with a back rest of the above-described type, this object is 
achieved according to the invention by providing an opening provided in 
the front side of the upholstery support to form a receptacle for a belt 
retraction device, which receptacle is open towards the front and bounded 
at the rear by the back wall of the upholstery support. An upper and lower 
wall formed in the upholstery support delimit the receptacle and are 
connected to the front and/or back wall and hold the belt retraction 
device without play. Restraining and connecting elements hold the belt 
retraction device in the receptacle. 
According to the invention, the embodiment of the receptacle for the belt 
retraction device results in an extremely simple mounting, because the 
belt retraction device need only be inserted through the opening into the 
receptacle with a pivoting movement about a contact point on the upper 
edge of the opening, and then secured in place by means of the connection 
element. The force exerted by the seat belt on the belt retraction device 
when in the blocking position is not borne by individual connection 
elements, but is finally distributed over a large surface area or at least 
over a plurality of contact points between the belt retraction device and 
the upholstery support. A tensile loading of the seat belt, namely due to 
the torque exerted thereby on the belt retraction device, results in the 
belt retraction device being braced between the upper and lower walls of 
the receptacle. In addition there is the restraining force of the holding 
elements. In case of an accident, the belt retraction device is thus held 
securely in the receptacle. The connection element is not loaded thereby 
and can therefore be made in the form of a relatively weak screw or the 
like. 
Aside from the simple from-the-front mounting of the belt retraction device 
and the avoidance of a point-focused force introduction into the sheet 
metal structure of the upholstery support, the solution according to the 
invention also has a series of additional advantages. The belt retraction 
device can be integrated optimally into the back rest structure without 
play or rattling. In addition, the arrangement of the belt retraction 
device in the upholstery support results in there being fewer belt 
diversion points, so that a smaller belt retraction force will suffice, 
thus increasing wearer comfort. 
In addition, it is not necessary to provide an extra length of seat belt to 
accommodate a longitudinal adjustment of the seat, so that a smaller belt 
coil is sufficient, which substantially reduces or entirely eliminates the 
disruptive film spool effect. Furthermore, the exit angle of the seat belt 
can be predetermined in a simple manner by means of an integrated 
diverter. If the back rest has a limited force tolerance, the loading to 
be assumed by the belt retraction device can be reduced, which results in 
smaller material thicknesses for the retraction device and makes it 
possible to manufacture the housing of the belt retraction device from 
simpler or lighter weight material. An additional, significant advantage 
of the arrangement of the belt retraction device in the receptacle of the 
upholstery support according to the invention is that the safety belt is 
fully functional in all reclining positions. 
Advantageously, the depth of the recess is smaller than the dimension of 
the belt retraction device measured in this same direction, so that the 
belt can be comfortably grasped by the seat user. 
By adapting the contour of the opening to the outside contour of the belt 
retraction device, the opening is capable of also positioning the belt 
retraction device in the direction of its rotational axis. 
Because a high load is placed on the upper wall of the receptacle when the 
belt is heavily loaded, the upper wall is formed by curved elements in the 
front wall and the back wall, which here, for purposes of the invention, 
are directly connected with each other. 
In order to further simplify the placement of the belt retraction device 
into the receptacle and to avoid play in the belt retraction device 
between the upper and lower walls, the lower wall is formed in one 
preferred embodiment as a sloping plane. Particularly advantageous hereby 
is an embodiment in which the lower wall is formed at least in part by a 
resilient tongue which is formed from a portion of the front wall and is 
bent toward the back wall, because a resilient tongue, which can be formed 
from the material to be removed to form the opening, assures that the belt 
retraction device will abut against the upper wall, even with large 
tolerances. If a resilient tongue is provided, it is advantageous to form 
a portion of the lower wall as a reinforcing crease. 
Restraining elements provided on the back wall and the upper wall and 
formed from sections of material that are pressed out of these walls and 
are roof-shaped in cross-section are particularly advantageous, because 
they are capable of bearing large forces, and because they are also 
economical to manufacture, namely in the shaping of the back wall. 
It is preferred for the belt retraction to have a U-shaped roll housing 
provided with openings to form teeth which engage beneath the associated 
holding elements in the back wall. Teeth of this type are also very 
economical to manufacture and provide a connection with a high load 
bearing capacity. 
The belt retraction device advantageously includes a bar to cooperate with 
the holding elements provided on the upper wall. A bar of this type makes 
it possible to be able to provide holding elements on the upper wall also 
in the area between the shanks of the roll housing and to bring them into 
engagement with the bar, so that a very high restraining force can be 
achieved. 
To simplify mounting, both shanks of the roll housing can be provided with 
a step that is adjacent to the upper end of the opening. 
In the interest of making the mounting process as simple as possible, in 
one preferred embodiment the yoke section of the belt retraction device 
housing has a strap that is bent opposite to the direction in which the 
shanks extend and is provided with a hole to allow for the passage of a 
screw which engages a nut that is connected to the front wall. The 
retraction device then need only be introduced into the receptacle until 
the strap contacts the front wall. Then, the strap need only be connected 
with the front wall by means of a screw or the like, by which means 
movement of the belt retraction device in the receptacle, which could 
result in rattling, can simultaneously be avoided. 
With the foregoing and other objects, advantages and features of the 
invention that will become apparent hereinafter, the nature of the 
invention may be more clearly understood by reference to the following 
detailed description of the views, the appended claims and to the several 
views illustrated in the attached drawings.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring now in detail to the drawings wherein like parts are designated 
by like reference numerals throughout, there is illustrated in FIGS. 1 and 
2 a back rest for a motor vehicle seat having an upholstery support 
comprised of a front sheet metal shell 1 and a rear sheet metal shell 2, 
which upholstery support has the shape illustrated in FIG. 1. The two 
sheet metal shells 1 and 2 have flange-like bent edge zones 1' and 2' that 
abut each other, are connected with each other in this zone and form two 
hollow longitudinal beams 4 and 5, the lower ends of which are connected 
with respective hinge fittings 6. As shown in FIG. 1, the two longitudinal 
beams 4 and 5 approach each other steplessly from the bottom until about 
the center of the upper half, and then extend upwardly and outwardly. A 
hollow central portion 7 which is also formed by the two sheet metal 
shells 1 and 2 connects the two longitudinal beams 4 and 5 with each other 
in the area of their upper halves. The two upper end sections 4' and 5' of 
the longitudinal beams 4, 5, which extend at an angle upwardly and toward 
the side, project above the central portion 7. 
Relative to the upper end section 4', as shown in FIG. 4, both end sections 
are bounded at the top by an upper wall, which is formed by a backwardly 
bent portion 8 of the front sheet metal shell 1 serving as the front wall 
of the upholstery support and by a forwardly bent portion 9 of the sheet 
metal shell 2 serving as the back wall. Accordingly, the two upper end 
sections 4' and 5' are bounded laterally by a backwardly bent portion 10 
of the front sheet metal shell 1 and a forwardly bent portion 11 of the 
rear sheet metal shell 2. 
In the area of the upper end section 4', the front sheet metal shell 1 is 
provided with a rectangular opening 12, which extends over the entire 
width of the upper end section 4' and on to the upper wall formed by the 
portions 8 and 9. This opening 12 forms the access to a receptacle formed 
by the upper end section 4' for a seat retraction device designated 
generally by the reference numeral 13, which is to be mounted in the 
receptacle in order to transfer the forces exerted on it by its seat belt 
14 into the upholstery support. 
The belt retraction device 13 includes a known and therefore unillustrated 
take-up shaft which is rotatably mounted in a U-shaped take-up spool 
housing 15, which in the exemplary embodiment is made of aluminum sheet. 
An encapsulated return take-up spring is arranged adjacent to the outside 
of one shank 15' of this take-up spool housing 15, and the blocking 
device, also encapsulated, is arranged adjacent to the outside of the 
other shank 15'. This blocking device can be formed in a known manner. In 
the exemplary embodiment a release is accomplished by means of a stroke 
magnet in conjunction with an acceleration absorbing device. 
As shown in FIG. 1, the width of the opening 12 and the receptacle are 
adaped to the width of the belt retraction device 13, so that this device 
13 is arranged in the receptacle without any signficant lateral play. As 
shown in FIGS. 2 and 7, in contrast, the depth of the receptacle is 
smaller than the dimension of the belt retraction device 13 measured in 
the same direction, so that this device 13 projects forward beyond the 
front sheet metal shell 1. 
In the downward direction the receptacle is bounded by a lower wall, which 
is formed in part by a tongue 16, which itself is formed in one place with 
the front sheet metal shell 1 and, at the lower edge of the opening 12, is 
bent toward the back sheet metal shell 2. The tongue 16 is made from a 
portion of the same material that had to be removed from the front sheet 
metal shell 1 to form the opening 12. As may be seen especially in FIG. 4, 
the tongue 16 forms an inclined plane, namely in such a manner as to form 
an acute angle with the plane defined by the opening 12 and an obtuse 
angle with the surface of the back sheet metal shell 2 defining the rear 
of the receptacle. 
In the free end of the somewhat resilient tongue 16 ending near the back 
sheet metal shell 2, there is provided a central opening 16', into which a 
reinforcing crease 17 of the rear sheet metal shell 2 projects. The 
upwardly facing outer wall 17' of the back sheet metal shell 2 lies in the 
plane defined by the tongue 16 and forms a portion of the lower wall 
defining the receptacle. As shown in FIG. 7, the yoke section 15" of the 
take-up spool housing 15 rests on this lower wall. The distance of the 
lower wall from the upper wall formed by the elements 8 and 9 is selected 
in such a manner that, when mounted, the upper edges of the two shanks 15' 
of the take-up spool housing 15 lying inside the receptacle directly 
contact the upper wall with no play, whereby the amount of resilience of 
the tongue 16 compensates for manufacturing tolerances. 
A strap 18, which projects slightly forward from the yoke section 15" and 
then curves downward, is formed in one piece with the yoke section 15" of 
the take-up spool housing 15. Strap 18 is provided with a longitudinal 
hole 18' which aligns with a nut 19 when the belt retraction device 13 is 
in its mounted position. This nut 19 is rigidly connected with the front 
sheet metal shell 1 in the area of a depression in which the strap 18 
engages. After the belt retraction device 13 is set in place, a screw 20 
secures it in the correct position, but assumes no part of any tensile 
load on the seat belt 14. 
As shown in FIGS. 3 and 4, holding elements 21 pressed out from the back 
sheet metal shell 2 project into the receptacle, have a roof-like 
cross-sectional profile and are downwardly open. The arrangement of these 
holding elements 21 is selected such that two of them are aligned with 
each of the two shanks 15' of the take-up spool housing 15 and are spaced 
from each other in the longitudinal direction of the shanks. When the belt 
retraction device 13 is mounted, each tooth 22 of the shanks 15' grips 
beneath the holding elements 21. The teeth 22 provided on the rear edge of 
the shanks 15' are exposed by means of openings 23. 
Holding elements 24 formed in the same manner as the holding elements 21 
project out of the element 9 of the rear sheet metal shell 2 into the 
receptacle. As shown in FIG. 3, these holding elements 24 lie adjacent to 
and spaced from one another between the two contact surfaces for the 
shanks 15'. When the belt retraction device 13 is in its mounted position, 
a bar 25 which is rectangular in cross-section extends behind these 
holding elements 24, the end sections of which bar 25 are placed into 
correspondingly shaped openings in the upper edge of the two shanks 15' 
and are secured there in place. 
As a mounting aid the upper edge of each of the two shanks 15' of the 
take-up spool housing 15 is also provided with a step 26. These steps 26, 
as shown in FIG. 5 are brought into contact with the upper limiting edge 
of the opening 12 at the beginning of the mounting process. The insertion 
of the belt retraction device 13 into the receptacle then takes place in 
such a manner that the entire belt retraction device 13 is pivoted about 
the axis defined by the step 26. As this is done, first the bar 25 engages 
behind the holding elements 24. Shortly before the rear edge of the shank 
15' comes into contact against the rear wall of the receptacle, the teeth 
22 engage beneath the holding elements 21. At the end of the insertion 
process the shanks 15' abut the rear and upper boundary walls of the 
receptacle. In addition, the yoke section 15" rests on the boundary wall 
17' on the tongue 16. Finally, the strap 18 rests against the front sheet 
metal shell 1, as shown in FIG. 7. The seat belt 14, which because of the 
mounting of the belt retraction device 13 from the front does not need to 
be threaded through any type of slot, can be diverted to the necessary 
degree by a guide element 27 secured to the take-up spool housing 15. 
If the seat belt 14 exerts a tensile force on the belt retraction device 13 
when the blocking effect is active, then a torque acting in the sense of a 
clock-wise pivot movement as viewed according to FIGS. 5 through 7 acts on 
the take-up spool housing 15 about the front edge of the yoke section 15" 
to which the strap 18 is connected. This torque has the result that the 
shanks 15' are pressed against the upper wall of the receptacle formed by 
the elements 8 and 9 with increased force. In addition to this tensioning, 
the holding elements 21 and 24 together with the teeth 22 and the bar 25 
of the take-up spool housing 15, also serve to prevent a movement out of 
the position illustrated in FIG. 7. The screw 20 thereby is not subjected 
to a load and therefore can be of smaller dimensions. 
Although only preferred embodiments are specifically illustrated and 
described herein, it will be appreciated that many modifications and 
variations of the present invention are possible in light of the above 
teachings and within the purview of the appended claims without departing 
from the spirit and intended scope of the invention.