Filtration in hybrid inflators

A hybrid inflator for a vehicle occupant restraint, said hybrid inflator comprising:

• an elongated cylindrical container having a first chamber for storing a gas generating material and a second chamber for storing a supply of gas under pressure, the gas generating material when ignited generating a hot gas, the generated hot gas containing particulate of the gas generating material and byproducts thereof and being releasable from said first chamber into said second chamber by means of at least one gas exit nozzle at a first end of a first end portion of said first chamber with said gas exit nozzle being opposite a first inner end of said second chamber, and wherein a distance D separates the first end of said first chamber from the first inner end of said second chamber;
• an elongated cylindrical structure comprising at least one filter material housed in said container and extending into said second chamber about said gas exit nozzle of said first chamber a distance L from the first end of said first chamber toward the first inner end of said second chamber, said filter structure being secured about said first end portion of said first chamber and defining an inner mixing zone in said second chamber for mixing at least a portion of the particulate-containing generated hot gas with at least a portion of the stored gas to form a gas mix, said filter structure being contacted by a gas comprising at least a portion of the particulate-containing generated hot gas and effecting significant reduction in the particulate content of the contacting gas, said filter structure further defining an outer mixing zone in said second chamber wherein an inflation gas for use in inflating the vehicle occupant restraint and comprising a mix of gas of reduced particulate content and stored gas is formed;
• and
• a diffuser having at least one controlling orifice for providing passage therein of the inflation gas from said container and at least one exit port for dispensing the inflation gas into the vehicle occupant restraint.

A method for producing inflation gas in an apparatus suitable for use in inflating a vehicle occupant restraint and comprising a container having a first chamber for storing a gas generating material and a second chamber in which a supply of gas under pressure is stored, said method comprising the steps of:

• igniting the gas generating material stored in the first chamber to generate a hot gas, the generated hot gas containing particulate of the gas generating material and byproducts thereof,
• releasing the particulate-containing generated hot gas from the first chamber into the second chamber by means of at least one gas exit nozzle, the container housing a structure comprising at least one filter material extending into the second chamber about said gas exit nozzle, the filter structure defining an inner mixing zone and an outer mixing zone in the second chamber,
• mixing at least a portion of the particulate-containing generated hot gas with at least a portion of the stored gas in the inner mixing zone to form a gas mix,
• contacting the filter structure with a gas comprising at least a portion of the particulate-containing generated hot gas to effect significant reduction in the particulate content of the contacting gas,
• mixing gas of reduced particulate content and stored gas in the outer mixing zone to form an inflation gas for use in inflating the vehicle occupant restraint, and
• passing the inflation gas by means of a diffuser having at least one controlling orifice for providing passage therein of at least a portion of the inflation gas and at least one exit port for dispensing at least a portion of the inflation gas passing therein into the vehicle occupant restraint.