Retractor with electro-rheological lock

• US 4,815,674 A
• Filed: 12/21/1987
• Issued: 03/28/1989
• Est. Priority Date: 12/21/1987
• Status: Expired due to Fees

• Current Assignee: General Motors Auto OOO (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Kurtti, Gary R., Blake, Thomas B.
• Primary Examiner(s): Jillions, John M.
• Application Number:
  US07/135,714
• Time in Patent Office: 463 Days
• Field of Search: 242/107.4 A, 242/107.4 R, 242/107.4 B, 280/806, 297/478, 297/480, 192/21.5, 188/267, 188/290, 188/266, 188/322.5
• US Class Current: 242/384
• CPC Class Codes: B60R 22/343 with electrically actuated locking means B60R22/3405 takes precedence
• CPC Class Codes: F16D 37/008 the particles being carried by a fluid, to vary viscosity when subjected to electric change, i.e. electro-rheological or smart fluids composition of such fluids C10M171/001

Abstract

According to the present invention a seat belt reel is mounted on a housing by a reel shaft. A locking mechanism for the reel includes a housing of electrically conductive material mounted on the retractor housing and defining a closed cavity communicating with the end of the reel shaft. A disc shaped electrode is located in the cavity of the housing and is attached on the end of the reel shaft by an electrically insulating connector. An electro-rheological fluid fills the cavity to fill the space between the electrode and the housing. An electrical circuit including an inertia sensor and a high voltage source applies a voltage differential between the electrode and the housing upon the occurrence of a vehicle deceleration condition so that the electro-rheological fluid changes to a solid to fix the electrode to the housing and thereby lock the reel shaft against rotation to fix the length of the seat belt.

Claims

1. A locking mechanism for a seat belt retractor having a belt reel rotatably mounted on a retractor housing by a reel shaft having an end, comprising:

rotationally stationary housing means of electrically conductive material mounted on the retractor housing and defining a closed cavity communicating with the end of the reel shaft;

a disk shaped electrode located in the cavity of the housing;

means attaching the electrode on the end of the reel shaft for rotation therewith and effective to electrically insulate the electrode from the reel shaft;

electrical circuit means adapted to apply a voltage differential to the electrode and the housing upon the occurrence of a sensed vehicle deceleration condition;

and an electo-rheological fluid filling the cavity, said fluid changing to a solid upon the application of the voltage thereto by the electrode and the housing so that the electrode is solidly fixed to the housing and thereby locks the electrode and the reel shaft against rotation to fix the length of the seat belt.

2. A locking mechanism for a seat belt retractor having a belt reel rotatably mounted on a retractor housing by a reel shaft having an end, comprising:

rotationaly stationary housing means of electrically conductive material mounted on the retractor housing and defining a cavity communicating with the end of the reel shaft;

a disk shaped electrode located in the cavity of the housing;

attaching means of dielectric material attaching the electrode on the end of the reel shaft for rotation therewith;

a cover of electrically conductive material mounted on the housing and closing the cavity;

electrical circuit means adapted to apply a voltage differential between the electrode and the housing and cover upon the occurrence of a sensed vehicle deceleration condition;

and an electro-rheological fluid filling the cavity, said fluid changing to a solid upon the application of the voltage thereto by the electrode and the housing so that the electrode is solidly fixed to the housing and thereby locks the electrode and the reel shaft against rotation to fix the length of the seat belt.