Inflatable seat belt having bag filter

Abstract

An inflatable seat belt apparatus is formed of an inflatable portion which is usually maintained in a band shape and has an envelope part inflated and deployed in a spindle shape by introducing gas generated by a gas generating device, the gas generating device acting in case of exceeding a predetermined threshold, a webbing having the inflatable portion extending over at least a range directly contacting with an occupant, a tongue fixed to an end of the inflatable portion and having a gas path from the gas generating device and a buckle to which the tongue is detachably engaged. The inflatable portion has an elastic inflatable unit inserted into the envelope part and is inflated and deployed by introducing the gas generated by the gas generating device into the elastic inflatable unit via a filter.

We claim: 
     
       1. An inflatable seat belt for restraining movement of an occupant in a vehicle, comprising: a webbing attached to the vehicle and extending for restraining movement of the occupant;   an inflatable portion formed over a part of the webbing and contacting the occupant when the webbing is worn, said inflatable portion including a cylindrical skirt disposed on one side of the webbing and formed of a heat resisting material; a filter directly attached to and completely surrounding the skirt; an elastic inflatable tube having an elongated shape and completely surrounding the webbing and the filter containing the skirt, said elastic inflatable tube having heat resistance and being fixed to the webbing; and a knitted member in a flat form and connected to the webbing to cover the entire inflatable tube, said knitted member having an elasticity in a direction perpendicular to a longitudinal direction of the webbing;   a tongue fixed to the skirt and having a gas flow path therein; and   a buckle attached to the vehicle and engagable to the tongue, said buckle having a .[.port.]. .Iadd.body .Iaddend.to supply hot gas to the inflatable portion through the gas flow path of the tongue, said hot gas flowing through the skirt and passing through the filter to lower temperature of the hot gas so that the inflatable tube is inflated by the gas while the knitted member is expanded by enlargement of the tube.   
     
     
       2. An inflatable seat belt according to claim 1, wherein said inflatable portion formed of the skirt, the filter, the inflatable tube and the knitted member is .[.a.]. laminated .[.and not folded.].. 
     
     
       3. An inflatable seat belt according to claim 2, wherein said inflatable portion further includes a .[.non-expandable.]. cover for covering the knitted member, said cover being sewn by a thread along the longitudinal direction of the webbing so that when the inflatable tube is inflated, the thread is torn to allow the inflatable tube to inflate easily. 
     
     
       4. An inflatable seat belt according to claim 3, wherein said skirt has a length of about one third of the length of the filter. 
     
     
       5. An inflatable seat belt according to claim 4, wherein said inflatable portion further includes an end fitting situated inside the skirt and a caulking fitting situated over the cover to sandwich the skirt, the filter, the inflatable tube and the knitted member therebetween, said tongue passing through the end fitting and the caulking fitting. 
     
     
       6. An inflatable seat belt according to claim 5, wherein said elastic inflatable tube is made of silicone rubber. .Iadd. 
     
     
       7.  An inflatable occupant protection device comprising: an elongated webbing;   an inflatable member;   a bag filter disposed within the inflatable member which filters gas flowing into the inflatable member upon inflation thereof; and   a fabric member connected to the elongated webbing to cover the inflatable member;   wherein the fabric member expands in a direction transverse to a longitudinal direction of the elongated webbing upon inflation of the inflatable member, thereby pre-tensioning the elongated webbing..Iaddend..Iadd.8. An inflatable occupant protection device according to claim 7, wherein the inflatable member includes a skirt disposed within the bag filter..Iaddend..Iadd.9. An inflatable occupant protection device according to claim 8, wherein the skirt is formed of a heat resisting material..Iaddend..Iadd.10. An inflatable occupant protection device according to claim 8, wherein the fabric member is a knitted fabric member that is easily expandable in the direction transverse to the longitudinal direction of the elongated webbing..Iaddend..Iadd.11. An inflatable occupant protection device according to claim 7, further comprising a tongue having a gas flow path therein, the tongue being connected to the inflatable member..Iaddend..Iadd.12. An inflatable occupant protection device according to claim 11, further comprising a buckle for engaging the tongue, the buckle having a body to supply gas to the inflatable member   
     
     
        through the gas flow path of the tongue..Iaddend..Iadd.13.  A method for providing occupant protection comprising the steps of: attaching an elongated webbing to a vehicle;   fixing to the elongated webbing an inflatable member, the inflatable member being covered by a fabric member which is connected to the elongated webbing, the fabric member pre-tensioning the elongated webbing upon inflation of the inflatable member by expanding in a direction transverse to a longitudinal direction of the elongated webbing; and   disposing a bag filter within the inflatable member, the bag filter filtering gas flowing into the inflatable member upon inflation of the inflatable member..Iaddend..Iadd.14. A method for providing occupant protection according to claim 13, further comprising the step of disposing a skirt within the inflatable member..Iaddend..Iadd.15. A method for providing occupant protection according to claim 14, wherein the step of disposing a skirt within the inflatable member comprises disposing a skirt formed of a heat resisting material within the inflatable member..Iaddend..Iadd.16. A method for providing occupant protection according to claim 13, further comprising the step of connecting a tongue to the inflatable member, the tongue having a gas flow path therein..Iaddend..Iadd.17. A method for providing occupant protection according to claim 16, further comprising the step of providing a buckle for engaging the tongue, the buckle having a body to supply gas to the inflatable member through the gas flow path of the   
     
     
        tongue..Iaddend..Iadd.  .  A method for providing occupant protection according to claim 13, wherein the step of fixing to the elongated webbing an inflatable member comprises fixing to the elongated webbing an inflatable member that is covered by a knitted fabric member that is easily expandable in the direction transverse to the longitudinal direction of the elongated webbing..Iaddend.