Drive unit for a belt pretensioner in a safety belt system for vehicles

• US 5,450,723 A
• Filed: 03/03/1994
• Issued: 09/19/1995
• Est. Priority Date: 03/06/1993
• Status: Expired due to Fees

• Current Assignee: TRW Repa GmbH
• Original Assignee: TRW Repa GmbH
• Inventors: Fohl, Artur
• Primary Examiner(s): Husar, Stephen F.
• Application Number:
  US08/206,598
• Time in Patent Office: 565 Days
• Field of Search: 60/632, 60/638, 297/480, 280/806
• US Class Current: 60/638
• CPC Class Codes: B60R 2022/4661 comprising venting means, e.g. for avoiding overpressure in case of fire or for allowing return motion with energy absorption
• CPC Class Codes: B60R 22/4619 Transmission of tensioning power by cable, e.g. using a clutch on reel side
• CPC Class Codes: F15B 15/19 Pyrotechnical actuators
• CPC Class Codes: F16F 7/12 using plastic deformation of members F16F9/30 takes precedence; yieldable means for mounting bumpers on vehicles B60R19/26; yieldable or collapsible steering columns B62D1/192

Abstract

A belt pretensioner for vehicle safety belt systems is provided with a drive unit which comprises a pyrotechnic gas generator (12) and a piston and cylinder unit (16, 20). The piston (20) is arranged at a first end (161) of the cylinder (16) and is connected with a cable (22). By means of the gas pressure produced by the gas generator (12) the piston is accelerated towards the second, tapered end (162) of the cylinder (16). A sleeve-like insert (18) is arranged in the tapered cylinder end. The insert (18) has ribs and grooves alternating in the peripheral direction to offer sufficient room for plastic deformation.

Claims

1. A drive unit for a safety belt pretensioner, comprising a cylinder, a piston slidingly received in said cylinder, a cable connected to said piston and a pyrotechnic gas generator, said cylinder having a tapered end wherein an insert sleeve is accommodated, said insert sleeve having a non-circular cross section.

2. The drive unit of claim 1, wherein said insert sleeve is of a material which has a fusion temperature above a self-ignition temperature of a pyrotechnic substance in said gas generator.

3. The drive unit of claim 2, wherein said insert sleeve is of a metallic alloy.

4. The drive unit of claim 1, wherein said piston has a reduced cross section on its side facing said insert sleeve.

5. The drive unit of claim 1, wherein said piston is tapered on its side facing said insert sleeve.

6. The drive unit of claim 1, wherein said insert sleeve has an inner surface provided with ridges and grooves alternating in a peripheral direction.

7. The drive unit of claim 1, wherein said insert sleeve has an outer surface provided with ridges and grooves alternating in a peripheral direction.

8. The drive unit of claim 1, wherein said insert sleeve has an outer surface adapted to the inner surface of said tapered cylinder end.