Method for operating a belt retractor and a belt retractor for a safety belt

Abstract

In a method for operating a belt retractor, the belt retractor comprising a belt tensioner drive and with a pre-tensioner drive which can both exert a torque onto a belt spool in a direction for winding a safety belt, the pre-tensioner drive is prevented from exerting a torque onto the belt spool through the activation of the belt tensioner drive. In a belt retractor for a safety belt, having a belt spool, a pre-tensioner drive with a drive motor, which can turn the belt spool in the winding direction for the purpose of pre-tensioning the safety belt, and with a belt tensioner drive which can drive the belt spool for the purpose of a belt tensioning, a safety mechanism is provided, which through an activation of the belt tensioner drive prevents the pre-tensioner drive from driving the belt spool in the winding direction.

1 . A method for operating a belt retractor, said belt retractor being provided with a belt tensioner drive and with a pre-tensioner drive, both said belt tensioner drive and said pre-tensioner drive being adapted to exert a torque onto a belt spool in a direction for winding a safety belt, the method containing the following steps: 
 activating said belt tensioner drive,    preventing said pre-tensioner drive from exerting a torque on said belt spool as a consequence of said activation of said belt tensioner drive.    
   
   
       2 . The method according to  claim 1 , characterized in that a flux of force from said pre-tensioenr drive to said belt spool is interrupted as a consequence of said activation of said belt tensioner drive.  
   
   
       3 . The method according to  claim 1 , characterized in that the belt tensioner drive has a pyrotechnic gas generator which is actuated when said belt tensioner drive is actuated and which prevents said pre-tensioner drive from exerting a torque on said belt spool.  
   
   
       4 . The method according to  claim 3 , characterized in that activation of said pyrotechnic gas generator displaces a separating element from an initial position, in which said pre-tensioner drive is drivingly connected to said belt spool in a direction for winding said safety belt onto the belt spool and hence for pre-tensioning said safety belt, into a separating position in which said pre-tensioner drive is disconnected from said belt spool.  
   
   
       5 . The method according to  claim 3 , characterized in that activation of said pyrotechnic gas generator displaces a connecting element from an initial position, in which said pre-tensioner drive is drivingly connected to said belt spool in a direction for winding said safety belt onto said belt spool and hence for pre-tensioning said safety belt, into a separating position in which said pre-tensioner drive is disconnected from said belt spool.  
   
   
       6 . The method according to  claim 1 , characterized in that said pre-tensioner drive has an electric motor and in that activation of said belt tensioner drive interrupts a current supply of said electric motor.  
   
   
       7 . The method according to  claim 1 , characterized in that said pre-tensioner drive has an electric motor and in that activation of said belt-tensioner drive results in operation of said electric motor in a direction for unwinding said safety belt.  
   
   
       8 . The method according to  claim 1 , characterized in that both said pre-tensioner drive and also said belt-tensioner drive are uncoupled from said belt spool by a rotation of said belt spool in an unwinding direction of said safety belt.  
   
   
       9 . A belt retractor for a safety belt, having a belt spool, a pre-tensioner drive with a drive motor which can rotate said belt spool in a winding direction so as to pre-tension a safety belt, and having a belt tensioner drive which can drive said belt spool so as to tension a safety belt, characterized in that a safety mechanism is provided which through an activation of said belt tensioner drive prevents said pre-tensioner drive from driving said belt spool in said winding direction.  
   
   
       10 . The belt retractor according to  claim 9 , characterized in that said safety mechanism has a separating element.  
   
   
       11 . The belt retractor according to  claim 10 , characterized in that said separating element is adapted for mechanically separating a connection from said pre-tensioner drive to said belt spool.  
   
   
       12 . The belt retractor according to  claim 11 , characterized in that said separating element separates a shaft.  
   
   
       13 . The belt retractor according to  claim 11 , characterized in that said pre-tensioner drive has one f a belt drive and a chain drive and that said separating element is adapted to destroy said belt or said chain.  
   
   
       14 . The belt retractor according to  claim 11 , characterized in that said pre-tensioner drive has a planetary gear and that said separating element can destroy a support which is fixed to said housing.  
   
   
       15 . The belt retractor according to  claim 11 , characterized in that said pre-tensioner drive has a toothed wheel gear and that said separating element can make a bearing of said gear inoperative.  
   
   
       16 . The belt retractor according to  claim 11 , characterized in that said pre-tensioner drive has a toothed wheel gear and that said separating element can transfer a connecting pin from an initial position, in which it can transfer a torque from one component of said gear to another, into a separating position.  
   
   
       17 . The belt retractor according to  claim 11 , characterized in that said pre-tensioner drive has a coupling and that said separating element brings said coupling into an uncoupled state or holds it in said uncoupled state.  
   
   
       18 . The belt retractor according to  claim 9 , characterized in that said separating element interrupts a supply of a drive motor.  
   
   
       19 . The belt retractor according to  claim 18 , characterized in that said separating element is a switch.  
   
   
       20 . The belt retractor according to  claim 18 , characterized in that said separating element destroys at least one supply line for said drive motor.  
   
   
       21 . The belt retractor according to  claim 18 , characterized in that said separating element is part of a buckle- or end fitting tensioner.  
   
   
       22 . The belt retractor according to  claim 18 , characterized in that said separating element short-circuits supply lines of said drive motor.  
   
   
       23 . The belt retractor according to  claim 1  (, characterized in that said separating element reverses a direction of rotation of said drive motor.  
   
   
       24 . The belt retractor according to  claim 9 , characterized in that said belt tensioner drive has a pyrotechnic gas generator and that said separating element is driven by a gas pressure which is generated upon activation of said belt tensioner drive.