Seat belt retractor with hydraulic load limiting

• US 20030189331A1
• Filed: 09/30/2002
• Published: 10/09/2003
• Est. Priority Date: 04/09/2002
• Status: Active Grant

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Heckmayr, Thomas
• Granted Patent: US 6,786,511 B2
• Time in Patent Office: Days
• US Class Current: 280/807
• CPC Class Codes: B60R 2022/282 using fluids or vico-elastic materials
• CPC Class Codes: B60R 2022/283 using tearing or scoring of material
• CPC Class Codes: B60R 22/3413 operating between belt reel and retractor frame B60R22/4676 takes precedence

Abstract

A seat belt retractor for a vehicle seat belt has a belt reel for the seat belt. A free-flowing load limiting medium is arranged in a working chamber. A displacement means is drivable by the belt reel. The load limiting medium is transported through at least one flow channel by the displacement means. The flow cross-section in the flow channel is selected as a function of the kinematic viscosity of the load limiting medium, to achieve a belt force limitation profile over time which approaches that of a torque rod.

Claims

1. A seat belt retractor comprising:

a belt reel;

a free-flowing load limiting medium arranged in a working chamber;

a displacement means drivable by the belt reel;

at least one flow channel through which the load limiting medium is transported by the displacement means;

the flow cross-section in the at least one flow channel exhibits, as a function of the kinematic viscosity of the load limiting medium, a constant area, the dimensions of which lie, in the case of a displacement means, in the range delimited by the two curves (KL1, KL2) (KR1, KR2) in FIG. 6 or, in the case of a rotary displacement means, in the range delimited by the two curves (KR1, KR2) in FIG. 7.

2. The seat belt retractor according to claim 1, wherein the displacement means is driven by the belt reel via a rack and pinion gear.

3. The seat belt retractor according to claim 1, wherein the displacement means is a piston movable along the belt reel axis, which piston is driven by the belt reel by means of cutting engagement.

4. The seat belt retractor according to claim 1, wherein the displacement means is a rotary vane rotor, which is connected non-rotatably with the belt reel.

5. The seat belt retractor according to one of claims 1 to 4, wherein a belt force profile over time is produced at the seat belt which approaches the belt force profile of a force limiter constructed as a torque rod.