Method for actuating a reversible belt pretensioner

• US 20040056471A1
• Filed: 06/06/2003
• Published: 03/25/2004
• Est. Priority Date: 12/08/2000
• Status: Active Grant

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Bullinger, Wilfried, Eberle, Walter
• Granted Patent: US 7,029,032 B2
• Time in Patent Office: Days
• US Class Current: 280/806
• CPC Class Codes: B60R 2021/01272 Belt tensioners
• CPC Class Codes: B60R 2022/4666 characterised by electric actuators
• CPC Class Codes: B60R 2022/469 reusable
• CPC Class Codes: B60R 21/01 Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents electrical circuits for transmission of signals between steering wheel and the vehicle itself B60R16/027; for electrically actuating belt retractor locking means B60R22/343
• CPC Class Codes: B60R 22/3416 Unlocking devices for retractors B60R22/3405 takes precedence
• CPC Class Codes: B60R 22/343 with electrically actuated locking means B60R22/3405 takes precedence
• CPC Class Codes: B60R 22/46 Reels with means to tension the belt in an emergency by forced winding upelectrical circuits for triggering safety arrangements B60R21/01 ; tensioners using reels only guiding the belt during normal use, e.g. splitted reels B60R22/195

Abstract

The invention relates to a method for actuating a reversible belt pretensioner for pretensioning a belt webbing, wound around a belt reel, of a seat belt in a motor vehicle, the belt pretensioner having a drive which acts on the belt reel. The seat belt has a locking device, acting on the belt reel in the unwinding direction, as a belt extraction lock. According to the invention, after the triggering of the belt pretensioner and when a predefinable condition is met, the belt pretensioner is actuated in such a way that the belt reel rotates at least to such an extent in the winding-up direction that the locking device of the belt reel opens and releases the belt webbing for unwinding.

Claims

1. Method for actuating a reversible belt pretensioner for pretensioning the belt webbing, wound around a belt reel, of a seat belt in a motor vehicle,

the belt pretensioner having a drive which acts on the belt reel, and

the seat belt having, as a belt extraction lock, a locking device (10, 11) which acts on the belt reel in the unwinding direction and whose locking can be released only if the belt reel is turned about an angular element in the winding-on direction,

characterized in that, after the triggering of the belt pretensioner and when a predefined condition is met, the belt pretensioner is actuated in such a way that the belt reel (12) turns at least so far in the winding-on direction (B) that the locking device (10, 11) of the belt reel (12) opens and releases the belt webbing (13) for unwinding.

2. Method according to claim 1, characterized in that

a variable which is indicative of the opening of the locking device (10, 11) is registered, and

the belt pretensioner is actuated in such a way that the belt reel (12) rotates just to such an extent that the locking device (10, 11) of the belt reel (12) opens and releases the belt webbing (13) for unwinding.

3. Method according to one of claims 1 or 2, characterized in that the locking device (10, 11) of the belt reel (12) has a rotatably attached locking latch (10) with a toothing which interacts with a complementary toothing (11) on the belt reel (12), the two toothings engaging in one another when the belt extraction lock is active.

4. Method according to claim 3, characterized in that the opening of the locking device (10, 11), through the release of the locking latch (10) from the toothing (11) located on the belt reel (12), is registered by means of a switch.

5. Method according to one of claims 1 or 2, characterized in that the angle of rotation of the rotation of the belt reel (12) is registered by means of an angle-of-rotation sensor, and in that the angle of rotation is used to determine the opening of the locking device (10, 11).

6. Method according to one of claims 1 or 2, characterized in that the belt pretensioner has an electromotive drive, and in that the value of an electrical operating variable of the electromotive drive of the belt pretensioner is registered during the actuation of the belt pretensioner and this value is used to conclude whether the belt extraction lock is active.

7. Method according to one of claims 1 or 2, characterized in that the belt pretensioner has an electromotive drive, the angle of rotation of this electromotive drive is registered and the belt pretensioner is actuated in such a way that the torque of the belt pretensioner drive is increased until a predefined angle of rotation is reached.

8. Method according to one of the preceding claims, characterized in that the belt pretensioner is actuated in such a way that when the belt webbing (13) is pretensioned and after the locking device (10, 11) opens, the belt webbing (13) is unwound from the belt reel (12) in such a way that a belt-webbing-sensitive sensor does not bring about the triggering of the belt extraction lock.

9. Method according to one of the preceding claims, characterized in that there is a drive for a seat adjustment means, and in that the seat adjustment means is actuated in such a way that the locking device (10, 11) can be opened by means of the belt pretensioner drive.

10. Method according to one of the preceding claims, characterized in that there is a drive for an adjustment device of the belt deflection roller and in that the adjustment device of the belt deflection roller is actuated in such a way that the locking device (10, 11) can be opened by means of the belt pretensioner drive.

11. Method according to one of claims 1 or 2, characterized in that the disappearance of the signal which brings about the triggering of the belt pretensioner is predefined as a predefinable condition for the actuation of the belt pretensioner in order to release the locking device (10, 11).

12. Method according to one of claims 1, 2 or 11, characterized in that the disappearance of an actuation signal for the brake booster system or a vehicle-movement dynamics control system is predefined as a predefinable condition for the actuation of the belt pretensioner in order to release the locking device (10, 11).

13. Method according to one of claims 1 or 2, characterized in that a waiting time T₀ after the disappearance of the signal which brings about the triggering of the belt pretensioner is predefined as a predefinable condition of the actuation of the belt pretensioner in order to release the locking device (10, 11), after the expiry of which waiting time T₀ the belt pretensioner is actuated in order to release the locking device (10, 11).

14. Method according to one of claims 1, 2, 13, 14 or 15, characterized in that, when the belt pretensioner is actuated in order to open the locking device (10, 11), the regulation of the motor current in order to hold the belt reel in a predefinable position is carried out until it is detected that the locking device (10, 11) has opened.