Spiral wrapped gas generator filter

Claim 1

A gas generator filter element comprising; a hollow cylindrical core having first and second open ends and internal and external surfaces, comprising a spirally wound first gas permeable support material of bendable material having a first edge and a second edge, forming adjacent wraps of said first gas permeable support material, wherein said first edge of said first gas permeable support material is joined to said second edge of said first gas permeable support material of said adjacent wrap by joining means such that said hollow cylindrical core retains a cylindrical form without need for additional clamping; at least one filter layer spirally wound radially outward of said core, wherein each filter layer comprises at least one layer of spirally wound first filter media, having an inner and outer surface, and at least one layer of spirally wound second gas permeable support material radially outward of said first filter media; and an outer layer radially outward of said spirally wound filter layer comprising at least one layer of spirally wound third gas permeable support material forming adjacent wraps of said third gas permeable support material wherein said third gas permeable support material having inner and outer surfaces, a third edge and a fourth edge, and an end portion, wherein said third edge and said fourth edge of the most radially outward layer of said third gas permeable support material is joined to the next most radially outward gas permeable support material by joining means such that said outer layer retains said outer layer and said filter layer in a cylindrical relation about said core without further structural support.

Claim 14

A method for continuous fabrication of filter units for use in automotive air bag inflators comprising: spirally winding a first gas permeable support material of bendable material around a rotating mandrel to form a hollow cylindrical core having internal and external surfaces, said first gas permeable support material having a first edge and a second edge, forming adjacent spiral wraps of said first gas permeable support material wherein said first edge of said first gas permeable support material is joined to said second edge of said first gas permeable support material of said adjacent spiral wrap by means such that said cylindrical core retains a cylindrical form without the application of external forces; spiral winding at least one filter layer radially outward of said cylindrical core, wherein each filter layer comprises spirally winding at least one layer of first filter media radially outward of said hollow cylindrical core and spirally winding at least one layer of a first gas permeable support material layer radially outward of said first filter media; spirally winding an outer layer radially outward of said filter layer comprising spirally winding at least one third gas permeable support material forming adjacent spiral wraps of said third gas permeable support material, wherein said third gas permeable support material having inner and outer surfaces, third and fourth edges, and an end portion, wherein said third edge and said fourth edge of the most radially outward spiral wrap of said third gas permeable support material is joined to the next most radially outward layer by means such that said outer layer retains said outer layer and said filter layer in a cylindrical relation about said cylindrical core without further structural support, thereby forming a continuous spiral wound filter unit; and transversely cutting said continuous spiral wound filter unit at intervals to form individual spiral wound filter units of desired lengths.

Claim 15

A method for continuous fabrication of filter units for use in automotive air bag inflators comprising: spirally winding a first gas permeable support material of bendable material around a rotating mandrel to form a hollow cylindrical core having internal and external surfaces, said first gas permeable support material having a first edge and a second edge, forming adjacent spiral wraps of said first gas permeable support material wherein said first edge of said first gas permeable support material is joined to said second edge of said first gas permeable support material of said adjacent spiral wrap by means such that said cylindrical core retains a cylindrical form without the application of external forces; spiral winding at least one filter layer radially outward of said cylindrical core, wherein each filter layer comprises spirally winding at least one layer of first filter media radially outward of said hollow cylindrical core and spirally winding at least one layer of a first gas permeable support material layer radially outward of said first filter media; spirally winding an outer layer radially outward of said filter layer comprising spirally winding at least one third gas permeable support material forming adjacent spiral wraps of said third gas permeable support material, wherein said third gas permeable support material having inner and outer surfaces, third and fourth edges, and an end portion, wherein said third edge and said fourth edge of the most radially outward spiral wrap of said third gas permeable support material is joined to the next most radially outward layer by means such that said outer layer retains said outer layer and said filter layer in a cylindrical relation about said cylindrical core without further structural support, thereby forming a continuous spiral wound filter unit; and transversely cutting said continuous spiral wound filter unit at intervals to form individual spiral wound filter units of desired lengths.