Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
244 words
In 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 one of said drum and axle, and is movable along a helicoidal path relative to the other of said drum and 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, the improvement which comprises the annular piston being formed by two annular half-pistons, one of said half-pistons cooperating through said first guide means with the drum, the other of said half-pistons cooperating through said second guide means with said shaft, and said half-pistons having means for interconnecting said half-pistons to move together.
Claim 2
Dependent Claim
244 words
In 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 one of said drum and axle, and is movable along a helicoidal path relative to the other of said drum and 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, the improvement which comprises the annular piston being formed by two annular half-pistons, one of said half-pistons cooperating through said first guide means with the drum, the other of said half-pistons cooperating through said second guide means with said shaft, and said half-pistons having means for interconnecting said half-pistons to move together.
Claim 3
Dependent Claim
34 words
The improvement of claim 1, wherein said interconnecting means is adapted to operate when said pyrotechnic charge is ignited, whereby said drum is able to rotate initially without said annular half-pistons being axially displaced.
Claim 4
Dependent Claim
42 words
The improvement of claim 2, wherein said half-pistons have opposed faces and said interconnecting means is constituted by substantially radial teeth formed on said opposed faces of the half-pistons which are adapted to engage each other when the pyrotechnic charge is ignited.
Claim 5
Dependent Claim
247 words
In 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 one of said drum and axle, and is movable along a helicoidal path relative to the other of said drum and 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, the improvement which comprises a retaining mechanism interposed between said drum and said shaft, for opposing rotation of said drum relative to said shaft in a direction to unwind the flexible element therefrom and to move said piston from the said final position to said initial position thereof, after said pyrotechnic charge has been ignited.
Claim 6
Dependent Claim
247 words
In 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 one of said drum and axle, and is movable along a helicoidal path relative to the other of said drum and 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, the improvement which comprises a retaining mechanism interposed between said drum and said shaft, for opposing rotation of said drum relative to said shaft in a direction to unwind the flexible element therefrom and to move said piston from the said final position to said initial position thereof, after said pyrotechnic charge has been ignited.
Claim 7
Dependent Claim
38 words
The improvement of claim 4, wherein said retaining mechanism comprises at least one wedging element, and a portion fast with said drum or said shaft, said wedging elements being adapted to penetrate said portion to a predetermined depth.
Claim 8
Dependent Claim
16 words
The improvement of claim 5, wherein said wedging elements are balls having very high mechanical strength.
Claim 9
Dependent Claim
22 words
The improvement of claim 5 wherein said retaining mechanism comprises a plurality of wedging elements which are staggered longitudinally of said drum.
Claim 10
Dependent Claim
29 words
The improvement of claim 4, wherein said first or second guide means comprises at least one groove and said retaining mechanism comprises a wedging element accommodated in said groove.
Claim 11
Dependent Claim
47 words
The improvement of claim 5, wherein said drum has an interior surface with at least two longitudinally extending keying grooves in said interior surface, said wedging elements being fitted in said grooves and longitudinally staggered by at least one locating element which extends into said longitudinal grooves.
Claim 12
Dependent Claim
22 words
The improvement of claim 5, wherein said portion fast with said drum or shaft comprises a ring made of a deformable material.