Tensioner drive for a seatbelt installation, and assembly having a tensioner drive

A tensioner drive (11) for a seatbelt installation, having a tube (30), at least one piston (25) which within the tube (30) is displaceable along a propulsion direction (P2), and a gas generator (40) for generating a propulsion gas (G) and a propulsion pressure on a pressure-facing side of the at least one piston (25),

• wherein
• the at least one piston (25) on the pressure-facing side thereof has a first sealing element (90) which, upon triggering the gas generator (40), is impinged with the propulsion pressure and seals a first tubular portion (31) of the tube (30) that is filled with propulsion gas (G) in relation to a second tubular portion (32) of the tube (30) that in the propulsion direction (P2) lies behind said first tubular portion (31);
• a second sealing element (100) which, upon triggering the gas generator (40), is separated from the propulsion gas (G) of the gas generator (40) by the first sealing element (90) disposed in the propulsion direction (P2) behind the first sealing element (90);
• wherein the second sealing element (100) is displaceable relative to the first sealing element (90), and when a leakage of the first sealing element (90) occurs and when impinged with pressure by the propulsion gas (G) is displaced along the propulsion direction (P2) while enlarging a spacing (A) between the first sealing element (90) and the second sealing element (100);
• the at least one piston (25) is in at least two parts and, when viewed in the propulsion direction (P2), has a front first piston part (25a) and, when viewed in the propulsion direction (P2), has a second piston part (25b) that lies behind said first piston part (25a);
• the first sealing element (90) is attached to the first piston part (25a), and the second sealing element (100) is attached to the second piston part (25b);
• the second piston part (25b), when viewed in the propulsion direction (P2), is able to be moved away from the first piston part (25a) when the first piston part (25a) is blocked or decelerated in terms of the movement thereof and the second sealing element (100) is impinged with the propulsion pressure of the propulsion gas (G)
• the first piston part (25a) and the second piston part (25b) in an initial state, prior to the triggering of the gas generator (40), are connected by means of a plug connection (60);
• and
• the plug connection (60) is released when the second piston part (25b) is moved away from the first piston part (25a) while the second sealing element (100) is impinged with pressure.