Fuel tablet and propellan for a gas generator

Abstract

The invention relates to a propellant pellet for pyrotechnical safety devices in vehicles, such as airbag modules, belt tensioners, micro-inflators and igniters. The propellant pellet according to the invention has a substantially cylindrical shape and can be obtained by dry injection of a powdered propellant composition. The pellets have a maximum diameter of 2 mm and preferably a relative bulk density, defined as ratio of bulk density of the propellant pellets to the maximum theoretical density of the propellant composition, of at least 0.5. A propellant charge, an igniter and an inflator each comprising a plurality of said propellant pellets are provided.

1 . A propellant pellet for use in a safety device for vehicles that is obtained by dry injection of a powdered propellant composition, having a substantially cylindrical shape and a maximum diameter of 2 mm, wherein the propellant pellet especially has a relative bulk density of at least 0.5, defined as ratio of the bulk density of the propellant pellet to the maximum theoretical density of the propellant composition. 
     
     
         2 . The propellant pellet according to  claim 1 , wherein the propellant pellet has a relative bulk density of from 0.5 to 0.7. 
     
     
         3 . The propellant pellet according to  claim 1 , wherein the propellant pellet has a diameter within the range of 1 to 2 mm. 
     
     
         4 . The propellant pellet according to  claim 1 , wherein the propellant pellet has a ratio of height to diameter of from 0.2 to 0.8. 
     
     
         5 . The propellant pellet according to  claim 1 , having dimensions of diameter×height ranging from 1.0 mm×0.4 to 2 mm×1.5 mm, wherein the height-to-diameter ratio amounts to a maximum of 0.8. 
     
     
         6 . The propellant pellet according to  claim 5 , wherein the dimensions are within the range of 1.5 mm×0.4-0.9 mm. 
     
     
         7 . The propellant pellet according to  claim 5 , wherein the dimensions are within the range of 2 mm×0.4-1.5 mm. 
     
     
         8 . A propellant charge comprising a plurality of propellant pellets according to  claim 1 , especially as part of an igniter, inflator and/or actuator. 
     
     
         9 . An igniter ( 14 ) for use in a safety device comprising a plurality of propellant pellets according to  claim 1 . 
     
     
         10 . An inflator ( 10 ) or actuator for use in a safety device for vehicles, comprising an igniter ( 14 ), at least one combustion chamber associated with the igniter and a propellant charge ( 16 ) accommodated in the combustion chamber ( 18 ) for generating gas, wherein the propellant charge is provided in the form of a filling of propellant pellets, wherein the filling comprises propellant pellets according to  claim 1 . 
     
     
         11 . An inflator ( 10 ) or actuator according to  claim 10 , wherein the propellant pellets are provided in the filling in a single-mode distribution. 
     
     
         12 . The propellant pellets according to  claim 1 , wherein the propellant pellet is adapted for use as at least one of a booster charge and a propellant charge of at least one of an inflator, a micro-inflator and an igniter. 
     
     
         13 . The propellant pellet according to  claim 1 , wherein the propellant pellet is adapted for use in at least one of an advanced ignition device and an advanced ignition mixture directly integrated in an inflator propellant.