BELT RETRACTOR WITH SPRING BIASED AUXILIARY RATCHET WHEEL

• US 3,822,840 A
• Filed: 01/08/1973
• Issued: 07/09/1974
• Est. Priority Date: 01/08/1973
• Status: Expired due to Term

• Current Assignee: Robert L. Stephenson
• Original Assignee: Robert L. Stephenson
• Inventors: Stephenson, Robert L.
• Primary Examiner(s): Huckert, John W.
• Assistant Examiner(s): Henry, John W.
• Application Number:
  US05/321,899
• Time in Patent Office: 547 Days
• Field of Search: 242/107.4,107.5,107.2,107.3,107.6,107.7,17SB,17R,99 188/82.7 74/575,576,577R 297/386,387,388 280/15SB
• US Class Current: 242/384
• CPC Class Codes: B60R 2022/3427 Seat belt connection on reels
• CPC Class Codes: B60R 22/36 self-locking in an emergency B60R22/3405 , B60R22/343 take precedence
• CPC Class Codes: Y10T 74/2133 Pawls and ratchets

Abstract

A reel-type retractor for a vehicle safety belt having the feature that a spring-biased light-weight ratchet wheel, rotatable within limits with respect to a ratchet wheel serving as a flange for the reel, is biased with its teeth maintained slightly in advance of those of the flange. This light-weight rotatable auxiliary ratchet wheel prevents the pawl from striking the tip of the teeth of the flange and rebounding, to thereby skip teeth. In such a situation, the pawl strikes the advanced tooth of the auxiliary ratchet wheel causing it to give way against its bias. As a result, the pawl will not rebound, but engage the first tooth presented.

Claims

1. In a safety belt retractor having a rotatable reel to which a seat belt is attached, said reel having as a flange at least one first ratchet wheel having ratchet teeth including tips, and a pawl adapted to engage the first ratchet wheel to halt rotation of the reel, the improvement which comprises a second ratchet wheel mounted adjacent to the first ratchet wheel, for axial rotation relative to the first ratchet wheel the second ratchet wheel having ratchet teeth including tips for engagement with the pawl, means for limiting the relative axial rotation between the first and second ratchet wheels, biasing means acting between the first and second ratchet wheels urging the second ratchet wheel to a first rotational position with respect to the first ratchet wheel such that the tips of the teeth of the second ratchet wheel are normally maintained a circumferential distance in advance, in the belt unwinding direction, of corresponding tips of adjacent teeth on the first ratchet wheel, said advance circumferential distance being a small portion of the total circumferential distance separating the tips of successive teeth of the first ratchet wheel;

whereby the second ratchet wheel, when engaged by the pawl, rotates against bias provided by said biasing means to a second rotational position wherein the tips of the teeth of the second ratchet wheel are substantially in line with the tips of adjacent teeth of the first ratchet wheel.

2. The safety belt retractor as claimed in claim 1 wherein said means for limiting relative axial rotation comprises:

at least one pin attached to one ratchet wheel and at least one slot in the adjacent ratchet wheel, said pin engaging said slot, said slot having sufficient length along a line concentric to the axis of rotation to limit the rotation of the second ratchet wheel from the first rotational position to the second rotational position, and said biasing means is a spring acting between both ratchet wheels to bias them toward the first rotational position.

3. The safety belt retractor as claimed in claim 2 wherein between two and four said pins extend from the surface of the first ratchet wheel and wherein the second ratchet wheel has a number of said slots corresponding to the number of said pins, said slots being elongated, said pins being adapted to cooperate with said elongated slots positioned along lines concentric to the point of rotation of the second ratchet wheel, and sized to limit the rotation of the second ratchet wheel to the first position and the second position.

4. The safety belt retractor as claimed in claim 3 wherein the tips of the teeth of the second ratchet wheel in the first position extend beyond the tips of the teeth of the first ratchet wheel in the belt unwinding direction by an amount less than one-third of the distance between the tips of the teeth on the ratchet wheel.

5. The safety belt retractor as claimed in claim 1 wherein the weight of the second ratchet wheel is less than the weight of the first ratchet wheel.

6. The safety belt retractor as claimed in claim 5 wherein the weight of the second ratchet wheel is between 1/4 and 3/4 of the weight of the first ratchet wheel.