Safety belt arrangement

A safety belt arrangement, especially one having a lap belt as a constituent of the belt system. One end of the lap belt is connected to a part that is secured to the vehicle, and the other end of the lap belt is provided with a belt buckle part. An anchoring member is provided as a carrier for the other belt buckle part, with the ends of the lap belt, as well as the anchoring member, being connected with a tensioning mechanism that operates in opposite directions. This tensioning mechanism is disposed between the anchoring elements that act as guide elements for the lap belt portion and for the anchoring member, which includes a cable section. The tensioning mechanism is secured to the one end of the lap belt and to the anchoring member via connections that are freely movable in the direction toward the guide elements, and are also movable relative to one another.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a safety belt arrangement, especially for 
motor vehicles, that includes a lap belt as an integral portion of the 
belt system. One end of the lap belt is attached to an element that is 
connected to the vehicle. The other end of the lap belt is provided with a 
belt buckle part. An anchoring member is provided as a carrier for the 
other belt buckle part. The ends of the lap belt on the one hand, as well 
as the anchoring member on the other hand, are connected with a tensioning 
mechanism that operates in opposite directions. 
2. Description of the Prior Art 
The present invention can be used for all types of safety belts. For 
example, the present invention can be used with three-point safety belts 
where the belt extends as a shoulder belt from a belt reeling mechanism, 
which is generally mounted on the B- or C-column of the vehicle (for which 
as generally known such letter designations are used to refer to the front 
or windshield column as the A-column; the middle column referred to as the 
B-column generally laterally adjoining the backrest of the front seat; and 
the rear column referred to as the C-column in the rear quarter panel or 
trunk region of the vehicle), to a belt buckle part (generally a buckle 
tongue), and from there as a lap belt to a point of securement on a part 
of the vehicle. The present invention can also be used with a lap belt 
where the belt extends from the point of securement over the lap of the 
person who is strapped in to another point of securement that is next to 
the person and is in the form of a belt buckle lock having an anchoring 
member. These two types of belts are frequently combined with one another, 
especially on the rear seats of automobiles, with the persons sitting on 
the outsides each being strapped in via three-point belts, and with the 
person sitting between them in the middle being strapped in by a simple 
lap belt. 
Safety belt arrangements for restraining a person generally have the 
problem that in the event of an accident, for example a collision, the 
strapped-in persons have not only their upper body thrown forward, but in 
particular can also slide forward beneath the lap belt, as a result of 
which the lap belt assumes an unfavorable position with regard to the 
geometry of the belt, cutting into the abdomen region of the body of a 
person. This applies in particular, of course, for persons secured merely 
by a simple lap belt. 
U.S. Pat. No. 4,015,806-Tisell et al dated Apr. 5, 1977 corresponding to 
German Offenlegungsschrift No. 25 43 068 Karlstedt et al dated Apr. 8, 
1976 proposes for the front seat of automobiles that the lap belt be 
essentially simultaneously tensioned at both ends, with the two lower 
points of securement of the lap belt being connected via lines with a 
pyrotechnical drive mechanism that is disposed below the seat and has two 
pistons that are movable in opposite directions; in the event that the 
mechanism is triggered, these pistons are driven apart in opposite 
directions, thus tensioning the lap belt. The lines that lead from the lap 
belt to the piston are preferably guided via rollers. However, such an 
approach cannot be used with current safety belt systems. 
It is therefore one object of the present invention, for a safety belt 
arrangement, to provide a direct tensioning of the lap belt independent of 
the tensioning of the shoulder belt. 
A further problem encountered during tensioning of lap belts is that the 
anchoring points for the lap belt connection on the one hand, as well as 
the anchoring member as the belt buckle carrier and hence constituent of 
the portion that extends around the abdomen region of the strapped-in 
person, and hence the geometric course of the lap belt, are predetermined 
by the vehicle. This means that, for example, for a small person, the lap 
belt on both sides, or at least on one side, is at a distance from the 
body, so that even if the lap belt is tensioned, there is still enough 
space for the person to slide through beneath the belt. In addition, the 
lap belts extend rearwardly to the points of securement at a spacial acute 
angle relative to the securement plane, so that the belts do not optimally 
extend around the strapped-in person. Moreover, as a result of the acute 
angle high forces result at the points of securement, so that at this 
location a high effort is extracted to secure the strapped-in person. This 
problem attains particular weight with regard to the back seats of 
automobiles, since in particular the back seat can be occupied by up to 
three persons, so that here the points of anchoring could be placed 
particularly unfavorably. 
It is therefore a further object of the present invention to improve the 
geometry of the course of the lap belt at the same time that the latter is 
tensioned, and to conform the belt geometry to all seat configurations. 
SUMMARY OF THE INVENTION 
The safety belt arrangement of the present invention comprises: a first 
anchoring member, which is secured to the vehicle; this anchoring member 
is in the form of a first guide element, with a first one of the ends of 
the lap belt being attached to this guide element, with the other end of 
the lap belt being provided with a first belt buckle part; a second guide 
element, which is secured to the vehicle; a second anchoring member, which 
is in the form of a cable section, is supported by the second guide 
element, and is provided with a second belt buckle part that cooperates 
with the first belt buckle part; and a tensioning mechanism that 
interconnects the first end of the lap belt and a portion of the second 
anchoring member that is remote from the second belt buckle part; in an 
overhung arrangement, the tensioning mechanism operates in opposite 
directions, with the first end of the lap belt and the last-mentioned 
portion of the second anchoring member being freely displaceable toward 
and away from their associated guide elements, and being movable relative 
to one another. 
First of all, the present invention has the general advantage that as a 
result of the tensioning mechanism, which acts upon conventional anchoring 
elements, no structural alterations of the safety belt system are 
required, so that the safety standard associated therewith can be 
retained. 
The improvement advantage achieved with the inventive proposal is that the 
portion of the belt arrangement formed by the lap belt, the anchoring 
member, and the tensioning mechanism, and which extends around the abdomen 
region of the strapped-in person, is reduced by the oppositely directed 
movement of the lap belt and the anchoring member, so that the lap belt 
itself is tensioned. In so doing, in an advantageous manner, and depending 
upon the existing resistant, either the lap belt portion or the anchoring 
member is initially retracted where the resistance is the least, i.e. 
where the existing belt slack is the greatest. The inventive overhung 
pyrotechnical drive mechanism for the belt tensioning moves relative to 
the bottom part of the motor vehicle until a force equilibrium is achieved 
between the lap belt on the one hand and the anchoring member on the other 
hand. Since the tensioning movement of the anchoring member with the 
buckle lock tensions not only the lap belt but also the shoulder belt due 
to the belt strap being looped about the buckle part, the excess energy 
that still exists after the force equilibrium has been achieved serves to 
tension the upper portion of the belt, since when the lap belt is already 
tensioned, the further movement of the buckle on the floor of the vehicle 
brings about a tensioning of the shoulder belt. 
Two specific embodiments are particularly advantageous for realizing the 
objects of the present invention. In one of these embodiments, a linear 
tensioner is disposed between the guide elements, and in the other 
embodiment a belt reeling mechanism having a rotary tensioner that acts 
upon its shaft is provided. 
Beyond the advantages already achieved with the present invention, one 
preferred embodiment proposes, in addition to the overhung arrangement of 
the tensioning mechanism, to also arrange the anchoring mechanism for the 
lap belt portion, as well as the anchoring member in the form of the 
aforementioned guide elements, in such a way that they are displaceable, 
with this displacement capability being made possible only when the 
tensioning mechanism is triggered. The particular advantage of this 
arrangement is that there results a belt orientation that extends more or 
less at right angles to the fastening plane of the belt components, with 
the belts moving towards the person. Thus, in addition to shortening the 
belt run when the lap belt is tensioned, starting with the lap of the 
passenger, the respective shortest connection to the anchoring point of 
the belt system on the vehicle is automatically adjusted, so that after 
the conclusion of the tension movement, there is no longer any free space 
to allow the person that is strapped in to slide through. Hence, the 
inventive arrangement results not only in an improvement of the belt 
geometry but also results in elimination of the belt slack. 
Further advantageous features of the present invention will be described in 
detail subsequently.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to the drawings in detail, FIG. 1 schematically illustrates a 
back seat 6 of an automobile, with two different safety belt arrangements 
being secured there. As can be seen in detail in the right half of FIG. 1, 
a shoulder belt portion 7 extends from a non-illustrated anchoring 
location on the vehicle, preferably in the form of a self-locking belt 
reeling mechanism, in the direction toward the seat area of the back seat 
6, where the shoulder belt portion 7 changes, at a buckle tongue 8, into a 
lap belt portion 10 which, in turn, is connected to the vehicle via an 
anchoring mechanism 13. 
When a person puts on the safety belt, the buckle tongue 8 is placed into a 
belt buckle lock 12 that is connected to the vehicle via an anchoring 
member 11 and a guide element 14. As will de described subsequently, not 
only the anchoring mechansim or guide element 13 for the lap belt 10, but 
also the guide element 14 for the anchoring member 11, are disposed on 
guide rails 31 in such a way that they can be moved toward one another in 
the direction of the arrows 9. Details of the tensioning mechanism of FIG. 
1 are shown in FIG. 4, which will be described subsequently. 
Also schematically illustrated in FIG. 1, on the left side of the back seat 
6, is a different type of arrangement of a tensioning mechanism that is 
disposed between the associated buckle lock 12 and a non-illustrated 
anchoring mechanism for the lap belt, with guidance of the belt 
corresponding to that described for the right half of FIG. 1. For this 
embodiment, particular reference is made to FIGS. 5 and 6, which will be 
described in detail subsequently. 
One embodiment of an overhung linear tensioner will now be described in 
detail in conjunction with FIG. 2. 
The direction of the lap belt portion 10 is changed at the guide element 
13, and the direction of the anchoring member 11 is changed at the guide 
element 14. A drive mechansim 15 is disposed between the guide elements 13 
and 14 for the tensioning movement of the lap belt 10 and the anchoring 
member 11. The drive mechanism 15 is movably mounted in a support 16 that 
is secured to the non-illustrated bottom part of a vehicle. The drive 
mechanism 15 is furthermore held firmly in its rest position by means of 
appropriately shaped elements 17 that are embodied in such a way that 
under normal conditions the drive mechanism 15 is held and secured in a 
rattle-free manner, with a longitudinal displacement of the drive 
mechanism 15 in the support 16 being effected only in the event that the 
mechanism is triggered. The drive mechanism 15 itself comprises, in the 
manner known per se, a guide tube, a piston that is longitudinally movable 
therein, and a pyrotechnical propellant charge that releases gases in the 
event that the mechanism is triggered to provide for movement of the 
piston in the guide tube. Thus, the piston and the guide tube of the drive 
mechanism 15 are movable relative to one another. 
The lap belt 10 is attached to the guide tube of the drive mechanism 15, 
while the anchoring member 11 is introduced in a suitable manner into the 
drive mechanism, where it is secured to the piston. This arrangement can, 
of course, also be reversed. The piston is provided with a return stop, 
for example via a cutting ring, so that the position achieved after the 
mechanism is triggered as a result of the relative movement between the 
piston and the guide tube is retained after the conclusion of the 
movement. 
The tensioning mechanism illustrated in FIG. 2 operates as follow: as soon 
as in the event of danger an ignition of the propellant charge in the 
drive mechanism 15 is effected in the customary manner, the gases propel 
the piston in the guide tube, resulting in a relative movement between 
these two components. Depending upon on which side of the drive mechanism 
15, i.e. on the side facing the lap belt 10 or on the side facing the 
anchoring member 11, the resistance is less, in other words the pertaining 
belt slack is greater, there is effected a movement of the drive mechanism 
15 through the support 16 in the direction of either the guide element 13 
or the guide element 14 until a force equilibrium is achieved. 
Since when the force equilibrium is achieved the lap belt is tensioned, the 
energy that is still available from the drive mechanism 15 leads to a 
movement of the buckle lock 12 toward the bottom part of the vehicle. 
However, due to the tensioned state of the lap belt, this movement is 
possible only when the belt strap is pulled through the belt tongue, i.e. 
when the lap belt is lengthened to load the shoulder belt, whereby the 
adjusted force equilibrium is constantly maintained. 
In the embodiment illustrated in FIG. 3, the drive mechanism 15 is not 
disposed in the connection between the guide elements 13 and 14. A Bowden 
cable 18 having a core 19 that is movable in a conduit 20 is provided as 
the transfer element for the driving movement. In the illustrated 
embodiment, the Bowden core 19 is connected with the cable-like anchoring 
member 11, and the Bowden conduit 20 is connected with the lap belt 10 via 
a belt strap connector 21. The latter is also provided with a return stop. 
In the event that the mechanism is triggered, a pulling force is exerted 
upon the Bowden core 19 from a drive mechanism that is not illustrated in 
FIG. 3, and which can comprise movable vehicular matter that can be 
activated in the event of an accident, or a pyrotechnically driven 
piston-cylinder unit. As a result of this pulling force, the relative 
movement between the Bowden conduit and the Bowden core is taken advantage 
of in order to achieve the described force equilibrium between the lap 
belt 10 and the anchoring member 11. The Bowden conduit 20 conducts the 
compressive force onto the belt strap connector 21, while the anchoring 
member 11, which is connected to the Bowden core 19, is subjected to a 
pulling force. One specific embodiment of such a configuration is 
illustrated in FIG. 4, where the Bowden core 19 is connected to the piston 
of a pyrotechnical piston-cylinder unit 22 that has a gas generator 23 
which provides for the movement of the Bowden core 19 and hence for the 
tensioning movement. The advantage of such an embodiment is that, to the 
extent necessary due to the space that is available, the drive mechanism 
22 can be disposed at any suitable location in the vehicle, such as in or 
on the channel for the drive shaft. 
FIGS. 5 and 6 illustrate another embodiment, with the linear tensioner 
being replaced by a belt reeling mechanism having a pyrotechnical rotary 
tensioning mechanism that acts upon its shaft. Here again the lap belt 10 
changes direction at the guide element 13, and the anchoring member 11 
changes direction at the guide element 14, with a belt reeling mechanism 
24 for the tensioning movement of the lap belt 10 and the anchoring member 
11 being disposed between the guide elements 13 and 14. The belt reeling 
mechanism 24 is movably mounted in a guide rail 25 that is secured to the 
non-illustrated bottom part of a vehicle. Via bores 26 and similarly 
non-illustrated connecting means, the guide rail 25 is positively 
connected with the bottom plate of the vehicle in such a way that the rail 
25 is precluded from bowing or bending up between the bores 26. The 
housing 27 of the belt reeling mechanism 24 is provided with hook-like 
members 28 that extend around the outwardly bent rail 25 (FIG. 6). 
The lap belt 10 is threaded into the belt reeling mechanism 24 and is wound 
onto a shaft 29 that is mounted in the housing 27. At the same time, the 
anchoring member 11 is rigidly connected to the housing 27 of the belt 
reeling mechanism 24. A tensioning mechanism 30 acts upon the shaft 29 of 
the belt reeling mechanism 24, with the tensioning mechanism 30 being 
connected to the shaft 29 in a manner known per se. A gas-driven piston in 
the tensioning mechanism 30 provides for rotary movement of the shaft 29 
in the event that the mechanism is triggered. Furthermore, mounted on the 
shaft 29 is a locking member that can be deflected radially until it 
engages a locking gear-tooth system that is secured to the housing. This 
locking member, as a return stop, blocks the shaft from rotating back 
after the conclusion of the winding movement. 
This aforementioned arrangement operates as follows: As soon as in the 
event of danger an ignition of the propellant charge in the tensioning 
mechanism 30 of the belt reeling mechanism 24 is effected via a vehicle 
sensor, the gases drive the piston of the tensioning mechanism 30, and 
cause the shaft 29 to rotate. Depending upon which position of the safety 
belt system, i.e. at the lap belt 10 or at the anchoring member 11, the 
resistance is less, in other words the pertaining belt slack at that 
location is greater, there is initially effected either a winding up 
movement of the belt 10 on the shaft 29, or the pulling force tries to 
bear against the housing 27 and hence on the anchoring member 11. A 
pulling force exerted in this fashion leads to a displacement of the belt 
reeling mechanism 24 on the rail 25 in the direction of the guide element 
13, so that in such a situation, initially the anchoring member 11 is 
pulled through the guide element 14, and the buckle lock 12 is moved in 
the direction of the bottom of the vehicle. In this way there results a 
tensioning movement of the lap belt as well as of the shoulder belt as a 
consequence of the change of direction of the buckle lock of the belt 
strap. This movement sequence is carried out until a force equilibrium is 
achieved, as already described. 
Although not illustrated, the belt reeling mechanism 24 for the lap belt 10 
could be advantageously replaced by a known belt reeling mechanism having 
a vehicle-sensitive or belt strap-sensitive locking system that is 
provided with automatic retraction of the belt strap. Such an arrangement 
has the particular advantage that this type of belt reeling mechanism 
yields or retracts the lap belt after every movement of the person who is 
strapped in, as is the case with known belt reeling mechanisms of safety 
belt systems. Thus, the slack of the lap belt is already less right from 
the start, as a consequence of which the tensioning of the lap belt 
pursuant to the present invention operates even more effectively. 
FIGS. 7 to 9 show how, in addition to the overhung arrangement of the 
tensioning mechanisms 15, 23, and 24, the respective guide elements 13 and 
14 for the lap belt portion 10 and the anchoring member 11 can be disposed 
in a movable manner. For this purpose, for each element 13, 14 there is 
provided a guide rail 31 that is mounted on the vehicle via bushings 32. A 
sliding carriage 33 is movably disposed on the guide rail 31 as a carrier 
for the respective guide element 13, 14. As can be seen in detail in FIG. 
7, the sliding carriage 33 illustrated there supports the guide element 13 
for the lap belt 10, with the latter being guided in the direction of the 
arrow 34 to the tensioning mechanism 15 in conformity with the 
illustration of FIG. 2. A corresponding arrangement is shown in FIG. 9, 
where the sliding carriage 33 with the guide element 14 for the anchoring 
member 11 is movable in the direction of the arrow 35. 
As shown in detail in FIG. 8, the sliding carriages 33 and guide rails 31 
are prevented via a return stop from moving counter to the direction of 
the arrows 34 35. Such a return stop includes two cooperating wedge-like 
members 36, 37, with the member 36 being positively connected with the 
sliding carriage 33, with the further member 37 that is disposed on the 
associated wedge surface under yielding preload, being inserted against 
the guide rail 31 between the latter and the sliding carriage 33, which 
extends around the guide rail in a U-shaped manner. This provides a 
cooperating locking action when the sliding carriage moves in the 
direction of the arrow 38. 
Although not illustrated in detail, yet already described in connection 
with the overhung arrangement of a tensioning mechanism, the sliding 
carriages 13 are also secured in the guide rails 31 by shear pins which 
are of such a size that they do not shear until the tensioning mechanism 
has been triggered, whereupon the movement of the sliding carriages 33 
with the associated guide elements 13, 14 is released. 
The present invention is, of course, in no way restricted to the specific 
disclosure of the specification and drawings, but also encompasses any 
modifications within the scope of the appended claims.