REVERSIBLE BELT TENSIONER FOR VEHICLE OCCUPANT RESTRAINT SYSTEMS

• US 20130032653A1
• Filed: 12/08/2011
• Published: 02/07/2013
• Est. Priority Date: 03/01/2011
• Status: Active Grant

• Current Assignee: TRW Automotive GmbH (Apollo Global Management, Inc.)
• Original Assignee: TRW Automotive GmbH (Apollo Global Management, Inc.)
• Inventors: Holbein, Wolfgang, Klein, Artur, Kramer, Nathalie, Prokscha, Martin, Roehm, Stefano
• Granted Patent: US 8,777,268 B2
• Time in Patent Office: Days
• US Class Current: 242/390
• CPC Class Codes: B60R 2022/1957 characterised by electric actuators
• CPC Class Codes: B60R 22/03 Means for presenting the belt or part thereof to the wearer , e.g. foot-operated
• CPC Class Codes: B60R 22/1951 characterised by arrangements in vehicle or relative to seat belt

Abstract

The invention relates to a reversible belt tensioner (10) comprising a drive motor (12), a spindle (14) connected to the drive motor (12), a spindle nut (16) adapted to be displaced in axial direction (18) on the spindle (14), a catch (20) the one end of which is connected to the spindle nut (16) and a belt buckle (22) connected to the other end of the catch (20), wherein at least one of the following features prevents the spindle nut (16) from jamming during travel against block:

• • a cylindrical guiding portion (50) inside the spindle nut (16) interacting with the outer geometry of the spindle (14);
  • a freewheel mechanism (48) between the drive motor (12) and the spindle (14);
  • a compression spring (70) between the belt buckle (22) and a stop.

Claims

1. A reversible buckle tensioner comprising

a drive motor (12),

a spindle (14) connected to the drive motor (12),

a spindle nut (16) adapted to be displaced in axial direction (18) on the spindle (14),

a catch (20) the one end of which is connected to the spindle nut (16)

and a belt buckle (22) connected to the other end of the catch (20),

wherein at least one of the following features preventing the spindle nut (16) from jamming upon traveling against block:

a cylindrical guiding portion (50) inside the spindle nut (16) which interacts with the outer geometry of the spindle (14);

a freewheel mechanism (48) between the drive motor (12) and the spindle (14);

a compression spring (70) between the belt buckle (22) and a stop.

2. The belt tensioner according to claim 1, wherein the spindle nut (16) has a female thread (52) engaging in the spindle (14) and wherein the cylindrical guiding portion (50) is arranged ahead of and/or behind the female thread (52) viewed in axial direction (18).

3. The belt tensioner according to claim 2, wherein the axial length (l₁) of the cylindrical guiding portion (50) amounts to at least 25% of the length (l_total) of the spindle nut (16).

4. The belt tensioner according to claim 1, wherein the freewheel mechanism (48) is designed in the form of a dog clutch having clearance in the magnitude of at least 45°

upon reversal of the direction of rotation.

5. The belt tensioner according to claim 1, characterized by an electric insulation (32) between the drive motor (12) and the spindle (14), wherein a mount connected to the drive pinion (34) of the drive motor (12) is made of an electrically insulating material, the spindle (14) acting on said mount.

6. The belt tensioner according to claim 5, wherein the drive motor (12) is mounted on a casing (26) by means a motor flange (24) made of electrically insulating material.

7. The belt tensioner according to claim 5, wherein a ground of the drive motor (12) is connected to an electronic control unit.

8. The belt tensioner according to claim 1, wherein a compression spring (40) loads the spindle in axial direction against a stop and wherein the compression spring (40) is arranged inside the freewheel mechanism (48).

9. The belt tensioner according to claim 8, wherein the stop (42) is formed at a casing (26) and is adjacent to an end (44) of the spindle (14) facing away from the drive motor (12).

10. The belt tensioner according to claim 9, wherein the end (44) of the spindle (14) adjacent to the stop (42) is rounded.

11. The belt tensioner according to claim 9, wherein a ball is pressed into the end (44) of the spindle (14) adjacent to the stop (42).

12. The belt tensioner according to claim 1, wherein the spindle (14) can be supported on a motor flange (24) when it is displaced against the action of the compression spring (40).

13. The belt tensioner according to claim 1, wherein the compression spring (70) is arranged at the catch (20) and is supported between an end fitting (64) of the catch (20) and a shell (72) of the catch (20).

14. The belt tensioner according to claim 1, wherein a motor current of the drive motor (12) is monitored and the drive motor (12) is turned off upon increase in the motor current which is indicative of reaching a stop.