US 5,310,132 AGranted

Belt retractor with tension relief for safety belt restraining systems in motor vehicles

AssigneeTRW Repa GmbH

InventorRobert Kopetzky

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Abstract

A belt retractor with tension relief for safety belt restraining systems includes a retracting spring (6) and an auxiliary spring (8) dimensioned more weakly than the latter. The retracting spring (6) acts between a housing (10) of the belt retractor and a spring receiver (12). The auxiliary spring (8) acts between the spring receiver (12) and the belt spool (2). By blocking a ratchet wheel (48) which is rotatable to a limited extent relatively to the spring receiver (12) a change can be made between a normal operation in which only the retracting spring (6) defines the automatic belt retraction force, and a comfort operation in which only the auxiliary spring (8) is effective. Between the spring receiver (12) and the belt spool (2) a friction brake (22, 24) is operative to dampen a tensioning operation of the auxiliary spring (8) by the retracting spring (6) on changing from comfort to normal operation. The brake (22, 24) can be selectively activated by sensing the relative rotation between the spring receiver (12) and the ratchet wheel (48) so that it is inactive in the comfort operation of the belt retractor.

Claims7

Dependent claims

A safety belt retractor for vehicles comprising:

a housing;
a belt spool rotatably mounted in said housing for coiling and uncoiling of belt webbing;
a hub member connected to said belt spool for joint rotation, said member having a hub;
an intermediate member rotatably mounted in said housing in coaxial relationship with said belt spool;
a retracting spring having a first end connected to said housing and a second end connected to said intermediate member;
an auxiliary spring having a first end connected to said hub and a second end connected to said intermediate member, said auxiliary spring being weaker than said retracting spring;
a ratchet member mounted for limited rotation with respect to said intermediate member and selectively lockable in rotation with respect to said housing;
a biasing spring engaged between said intermediate member and said ratchet member to oppose relative rotation between said intermediate member and said ratchet member;
a braking means frictionally engaged with said hub member and mounted for rotation with respect to said hub member against frictional forces;
a coupling member for selectively coupling said intermediate member with said braking means for joint rotation therewith;
and
said coupling member being controlled by relative rotation of said ratchet member with respect to said intermediate member.

9 more elements

Dependencies are inferred from the claim text.