Device for winding a seat belt in vehicles
First Claim
1. A device for winding up an elongate flexible element, such as a vehicle safety belt, comprising a casing, an axle mounted in said casing and rotationally fast therewith, a hollow winding-drum rotatably mounted in said casing coaxial with and surrounding said axle, an annular piston positioned between said drum and axle and axially movable relative thereto between initial and final positions, an annular pressure chamber defined within said drum by said piston in said initial position thereof, a pyrotechnic charge for pressurising said pressure chamber with combustion gases therefrom to propel said piston axially along said drum and axle from said initial position, to said final position, first cooperable guide means on said piston and said drum, and second cooperable guide means on said piston and said axle, said first and second guide means being so arranged that said piston is rotationally fast with said drum or said axle and is movable along a helicoidal path relative to said axle when the piston is rotationally fast with said drum and is movable along a helicoidal path relative to said drum when the piston is rotationally fast with said axle, whereby axial displacement of the piston by the combustion gases causes said drum to be rotated for winding said flexible element on to said drum.
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Accused Products
Abstract
A device for winding up a vehicle seat belt in the event of a vehicle impact comprises a hollow winding drum rotatably mounted in a casing coaxially surrounding a threaded central axle which is rotationally fast with the casing. An annular piston inserted between the drum and axle is axially movable by the pressure generated by combustion gases issuing from a pyrotechnic charge detonated by a signal from an impact detector, to rotate the drum and wind up the belt, the piston being keyed for rotation with the drum and for helical movement relative to the axle. Under normal conditions the drum is free to rotate to wind up and unwind the belt, but a mechanism is automatically actuated upon impact to prevent or oppose rotation of the drum in an unwinding direction.
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Citations
11 Claims
- 1. A device for winding up an elongate flexible element, such as a vehicle safety belt, comprising a casing, an axle mounted in said casing and rotationally fast therewith, a hollow winding-drum rotatably mounted in said casing coaxial with and surrounding said axle, an annular piston positioned between said drum and axle and axially movable relative thereto between initial and final positions, an annular pressure chamber defined within said drum by said piston in said initial position thereof, a pyrotechnic charge for pressurising said pressure chamber with combustion gases therefrom to propel said piston axially along said drum and axle from said initial position, to said final position, first cooperable guide means on said piston and said drum, and second cooperable guide means on said piston and said axle, said first and second guide means being so arranged that said piston is rotationally fast with said drum or said axle and is movable along a helicoidal path relative to said axle when the piston is rotationally fast with said drum and is movable along a helicoidal path relative to said drum when the piston is rotationally fast with said axle, whereby axial displacement of the piston by the combustion gases causes said drum to be rotated for winding said flexible element on to said drum.
Specification