DE20021223U1 - Belt tensioners - Google Patents

Description

PRINZ & PARTNER uk

PATENT ATTORNEYS Manzingerweg 7

EUROPEANPATENTATTORNEYS D-81241 Munich

EUROPEANTRADEMARKATTORNEYS Tel. +49 89 89 69 80

15 December 2000

TRW Occupant Restraint Systems GmbH

& Co. KG
Industriestrasse 20
D-73553 Alfdorf

Our reference: T 9519 DE

St/SF

Belt tensioners

The invention relates to a belt tensioner for a safety belt system of vehicles, with a

attached holding element and a retraction element rotatably mounted thereon, wherein a belt buckle of the safety belt system is arranged on the retraction element and an actuating element engages.
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In the event of a vehicle impact, a belt tensioner system retracts the belt and eliminates the so-called belt slack so that the belt strap is as tight as possible around the vehicle occupant before the occupant moves forward, so that there is no risk of the vehicle occupant coming into contact with the steering wheel or dashboard.

Such a belt tensioner system is known, for example, from EP 404 989. The actuating element consists of a tensioned spiral spring. A release system with rolling elements is provided, which hold the retraction element in a stable rest position. The release system has a vehicle-sensitive inertia mass, which acts on the rolling elements in the event of a restraint so that the

-2-

The retraction element is forced from the rest position into a retaining position by the energy stored in the spiral spring, thereby moving the belt buckle so that the belt is tightened.

The disadvantage of such a system, however, is that the energy that can be stored in a coil spring is limited by the size of the spring and the coil spring in any case significantly increases the geometric dimensions of the belt tensioner.

The invention aims to create a belt tensioner with a powerful actuating element, while keeping the geometric dimensions of the entire belt tensioner small.

This is achieved in a belt tensioner of the type mentioned above by the fact that the actuating element is a piston-cylinder system. This creates a powerful actuating element for the belt tensioner. In addition, the dimensions of this belt tensioner are smaller than those of the state-of-the-art belt tensioner described above. In addition, an electrical trigger system can now be used, which can be used much more flexibly than a mechanical one.

Further advantageous embodiments of the invention emerge from the subclaims.
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The invention is described below with reference to a preferred embodiment, which is shown in the accompanying drawings.

- Figure 1 is a partially sectioned side view of an embodiment of the belt tensioner according to the invention in the rest position;

- Figure 2 is a partially sectioned side view of an embodiment of the belt tensioner according to the invention in the retightening position.
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Figure 1 shows a holding element 10 that can be attached to a vehicle and a lever-like retraction element 14 that is rotatably mounted on the holding element via a bearing 12.

an actuating element 16 is provided which consists of a cylinder 18 which is attached to the holding element 10 and a piston 20 which is mounted in the cylinder and acts on the retraction element 14. A pyrotechnic charge 21 is mounted in the cylinder which can be ignited by an igniter (not shown) so that it supplies the piston with compressed gas.

Furthermore, a belt buckle 22 of a safety belt system is arranged on the retraction element 14. The belt buckle is rotatably mounted on the free end 24 of the retraction element 14, and the piston 20 is rotatably mounted on a holding point 26 of the retraction element 14, which lies between the bearing 12 and the free end 24 of the retraction element. The piston 20 is completely pushed into the cylinder 18 in the rest position shown in Figure 1, and the retraction element holds the belt buckle 22 in its rest position.

A locking toothing 28 is provided on the holding element, and the retraction element 14 is provided with a locking pawl 30 which is engaged with the locking toothing. In the rest position, the locking pawl 30 is located above the locking toothing 28.

In Figure 2, the belt tensioner is shown in a retightening position after the pyrotechnic charge 21 has been ignited. The piston 20 is here largely pushed out of the cylinder 18. The piston 20, which is rotatably mounted at the holding point 26, presses against the retraction element 14, whereby the retraction element and the belt buckle 22 attached to it are pivoted clockwise compared to the rest position in Figure 1. In this way, the slack in a safety belt, which is engaged by a tongue inserted into the belt buckle, can be eliminated.

The embodiment shown in the figures has the advantage that a small displacement of the piston 20 enables a large displacement of the belt buckle 22. As can be seen in Figure 2, the pawl 30 prevents the retraction element 14 from being returned to its rest position, for example by a large pulling force on the belt buckle.

According to a further embodiment not shown here, the piston of the piston-cylinder system can be mounted at one end of the retraction element and the belt buckle can be mounted at a holding point between the bearing and the end of the retraction element. This embodiment enables particularly good power transmission from the piston-cylinder system to the belt buckle.

Claims (4)

1. Belt tensioner for a safety belt system of vehicles, with a holding element ( 10 ) fastened to the vehicle and a retraction element ( 14 ) rotatably mounted thereon, wherein a belt buckle ( 22 ) of the safety belt system is arranged on the retraction element ( 14 ) and an actuating element ( 16 ) engages, characterized in that the actuating element ( 16 ) is a piston-cylinder system. 2. Belt tensioner according to claim 1, characterized in that the belt buckle (22) is rotatably mounted at one end ( 24 ) of the retraction element ( 14 ) and a piston ( 20) of the piston-cylinder system is pivotally mounted at a holding point (26 ) between a bearing ( 12 ) and the end of the retraction element. 3. Belt tensioner according to claim 1, characterized in that the belt buckle ( 22 ) is rotatably mounted on the holding point ( 26 ) and the piston ( 20 ) of the piston-cylinder system is pivotally mounted on the end ( 24 ) of the retraction element ( 14 ). 4. Belt tensioner according to one of the preceding claims, characterized in that the holding element ( 10 ) has a locking toothing ( 28 ) and the retraction element ( 14 ) has a pawl ( 30 ), wherein the locking toothing ( 28 ) and the pawl ( 30 ) allow the movement of the retraction element ( 14 ) in one direction and prevent it in the opposite direction.