Abstract: A piston for a pretensioner device (10) for a motor vehicle seat belt system of a type having a gas generator (17) with the piston (21) guided in a tube (16) that closes a pressure space (20) in the tube (16). The pressure space (20) can be pressurized by the gas generator (17), driving the piston (21) to undergo pretensioning operation transmitted to the seat belt system by a force transmission means. The piston has a dome shaped front side adapted to engage a force transmission element and a skirt forming a sealing lip oriented toward the pressure space. At least one slot is formed in the outer surface of the piston extending axially from the sealing lip. The slot can be enlarged by the material erosion caused by the pressure and/or pressure conditions in the pressure space produced by gas from the gas generator.

Abstract: A tensioning device (10) for a seat belt, in particular in a motor vehicle, having a gas generator (17) and a piston (21) guided in a tube (16) that closes a pressure space (20) in the tube (16), whereas the pressure space (20) can be pressurized by the gas generator (17), as a result of which the piston (21) can be driven to perform a tensioning operation which can be transmitted to the seat belt by means of the force transmission means. The piston (21) having a closed or constricted opening (1, 1a), and the opening (1, 1a) can be enlarged and/or opened by the material erosion caused by the pressure and/or pressure conditions in the pressure space (20).

Abstract: A pretensioning device (10) for a safety belt, of a motor vehicle, having a gas generator (17), a piston (21) guided in a tube (16), which closes a pressure area (20) in the tube (16) that is pressurized by the gas generator (17) whereupon the piston (21) is able to move in a pretensioning movement which is able to be conveyed to the safety belt by means of an inertia body (19a) resting on a front face (9) of the piston (21). The piston (21) forms a pass-through opening (1) releasable upon exceeding of a predetermined pressure and a recess (26) is provided in the front face (9) with an inertia body (19a) resting thereon, so that a flow connection is created from the pass-through opening (1) to the area (25) located behind the piston (21) in the direction of the pretensioning movement (S).

Abstract: A pretensioning device (10) for a safety belt, of a motor vehicle, having a gas generator (17), a piston (21) guided in a tube (16), which closes a pressure area (20) in the tube (16) that is pressurized by the gas generator (17) whereupon the piston (21) is able to move in a pretensioning movement which is able to be conveyed to the safety belt by means of an inertia body (19a) resting on a front face (9) of the piston (21). The piston (21) forms a pass-through opening (1) releasable upon exceeding of a predetermined pressure and a recess (26) is provided in the front face (9) with an inertia body (19a) resting thereon, so that a flow connection is created from the pass-through opening (1) to the area (25) located behind the piston (21) in the direction of the pretensioning movement (S).

Abstract: A tensioning device (10) for a seat belt, in particular in a motor vehicle, having a gas generator (17) and a piston (21) guided in a tube (16) that closes a pressure space (20) in the tube (16), whereas the pressure space (20) can be pressurized by the gas generator (17), as a result of which the piston (21) can be driven to perform a tensioning operation which can be transmitted to the seat belt by means of the force transmission means. The piston (21) having a closed or constricted opening (1, 1a), and the opening (1, 1a) can be enlarged and/or opened by the material erosion caused by the pressure and/or pressure conditions in the pressure space (20).