| 摘要 |
<p>A device for tightening a seat belt has a piston-like drive member (2) arranged in a guide tube (1). A propellant gas drives the drive member (2) by expanding in a pressure chamber adjoining the drive member. A movement transmitting system connects the drive member to the seat belt. The drive member is a step piston which is provided with a first pressure chamber (36) and a second pressure chamber (38). A propellant gas discharge system (21) supplies propellant gas into the pressure chambers (36, 38). In the starting position the step piston (2) communicates with the propellant gas discharge system in such a way that the first and second pressure chambers (36, 38) are separated from one another and the propellant gas initially flows into the first pressure chamber (36) and the step piston (2) which is set into motion by the propellant gas acting in the first pressure chamber (36) clears a discharge orifice (37) in the second pressure chamber (38) after covering a first distance so the propellant gas flowing into the second pressure chamber (38) and acting therein additionally drives the step piston.</p> |
