Importance

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Abstract

A hydraulic velocity damper for use in a seat belt retractor system to control and limit the maximum velocity of seat belt payout during loading. The seat belt webbing payout is independent of the amount of load applied to a spindle body of the hydraulic velocity damper. In one embodiment, two pistons within an elliptical housing of a rotatable spindle body rotate about two independent drive screws. As the pistons rotate about respective drive screws, the pistons move towards each other to pressurize a hydraulic fluid within a chamber defined by the housing. At a predetermined pressure, a web covering at least one metering hole in each piston ruptures and the hydraulic fluid is positively displaced from within the chamber into an inner cavity of each piston. The rate at which the spindle body rotates is limited by the fluid displacement, regardless of the pressure within the chamber.

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First Claim