Inflatable seat belt having bag filter

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 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.