Inflatable seat belt with leak detection device

Abstract

An inflatable seat belt apparatus is formed of an inflatable portion which is usually maintained in a band shape and has an envelope shaped elastic inflatable member inflated and deployed in a rough spindle shape by introducing gas generated by a first gas generating device. The gas generating device operates in case of exceeding a predetermined threshold. A webbing includes the inflatable portion and extends over at least a range directly contacting with an occupant. A tongue is fixed to an end of the inflatable portion and includes a gas path extending from the gas generating device. A buckle is detachably engaged with the tongue. The envelope shaped inflatable member is inflated in a predetermined shape by introducing gas for a leak testing from a second gas generating device when the tongue is engaged with the buckle, and is inspected whether or not the gas leaks by a gas leak detecting device disposed in the gas path. A state of the damage is inspected.

We claim: 
     
       1. An inflatable seat belt apparatus 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 having an elongated shape and being formed over at least a part of the webbing, said inflatable portion contacting the occupant when the webbing is worn and having an elastic inflatable tube;   a tongue fixed to the elastic inflatable tube and having a gas flow path therein;   a buckle attached to the vehicle and engagable to the tongue, said buckle including a gas path having one end engagable to the gas flow path of the tongue;   first gas generating means connected to the gas path of the buckle, said first gas generating means providing a gas to the elastic inflatable tube to fully inflate the elastic inflatable tube when the vehicle receives a predetermined deceleration;   second gas generating means attached to the gas path of the buckle, said second gas generating means providing a gas for a leak test to the elastic inflatable tube at a pressure less than that supplied by the first gas generating means when the tongue is engaged with the buckle; and   gas leak detecting means disposed adjacent to the gas path of the buckle, said gas leak detecting means checking leakage of the gas in the elastic inflatable tube when the gas from the second gas generating means is supplied to the elastic inflatable tube so that the leakage of the elastic inflatable tube is inspected.   
     
     
       2. An inflatable seat belt apparatus according to claim 1, wherein said gas leak detecting means is a pressure sensor to detect change of the pressure in the elastic inflatable tube. 
     
     
       3. An inflatable seat belt apparatus according to claim 2, wherein said buckle further includes a valve attached to the gas path for switching connection of the gas path, said valve allowing the gas path to communicate the second gas generating means at the leak test and to communicate the first gas generating means after the leak test so that the elastic inflatable tube can be fully inflated by the first gas generating means when the vehicle receives the predetermined deceleration. 
     
     
       4. An inflatable seat belt apparatus according to claim 3, wherein said buckle further includes a gas exhaust pipe connected to the valve so that the gas in the elastic inflatable tube supplied from the second gas generating means is exhausted, after the leak test, from the gas exhaust pipe through the valve. 
     
     
       5. An inflatable seat belt apparatus according to claim 4, wherein said buckle further includes a tongue connection detecting sensor to detect connection between the tongue and the buckle. 
     
     
       6. An inflatable seat belt apparatus according to claim 3, further comprising controlling means connected to the gas leak detecting means, said controlling means preventing the first gas generating means from operating when the gas leak detecting means detects leakage of the elastic inflatable tube. 
     
     
       7. An inflatable seat belt apparatus according to claim 6, further comprising indicating means connected to the gas leak detecting means for indicating a detection result of the gas leak detecting means. 
     
     
       8. An inflatable seat belt apparatus according to claim 1, wherein said inflatable portion further includes a filter attached to the tongue and situated inside the elastic inflatable tube, 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. 
     
     
       9. An inflatable seat belt apparatus according to claim 8, wherein said inflatable portion further includes a .[.non-expandable.]. cover for covering the knitted member, said cover being sewn by first and second threads along the longitudinal direction of the webbing, said first threads being stronger than the second threads so that when the elastic inflatable tube is inflated, the second threads are torn to allow the elastic inflatable tube to inflate at a portion covered by the second threads. .Iadd. 
     
     
       10.  An inflatable occupant protection device comprising: an elongated webbing;   an inflatable member;   a fabric member connected to the elongated webbing to cover the inflatable member;   a tongue fixed to the inflatable member and having a gas flow path therein;   a buckle engageable with the tongue and having a gas flow path engageable with the gas flow path of the tongue;   a gas source connected to the gas flow path of the buckle to supply gas for inflation of the inflatable member; and   a leak detection control unit connected to the gas flow path of the buckle, the leak detection control unit detecting gas leakage upon engagement of the buckle and tongue;   wherein the fabric member is expandable in a direction transverse to a longitudinal direction of the elongated webbing upon inflation of the inflatable member, thereby pretensioning the elongated webbing. .Iaddend..Iadd.   
     
     
       11.  An inflatable occupant protection device according to claim 10, further comprising a filter attached to the tongue. .Iaddend..Iadd.12. An inflatable occupant protection device according to claim 10, wherein the inflatable member is formed of a heat resisting material. .Iaddend..Iadd.13. An inflatable occupant protection device according to claim 10, 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.14.  An inflatable occupant protection device according to claim 10, wherein the leak detection control unit detects gas leakage with a sensor that detects a change in pressure of the inflatable member while the tongue and the 
     
     
        buckle are engaged. .Iaddend..Iadd.15.  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;   fixing a tongue to the inflatable member, the tongue having a gas flow path therein;   providing a buckle engageable with the tongue and having a gas flow path engageable with the gas flow path of the tongue;   connecting a gas source to the gas flow path of the buckle to supply gas for inflation of the inflatable member; and   connecting a leak detection control unit to the gas flow path of the buckle, the leak detection control unit detecting gas leakage upon   
     
     
        engagement of the buckle and tongue. .Iaddend..Iadd.16.  A method for providing occupant protection according to claim 15, further comprising 
     
     
        the step of attaching a filter to the tongue. .Iaddend..Iadd.17.  A method for providing occupant protection according to claim 15, wherein the step of fixing to the elongated webbing an inflatable member comprises fixing to the elongated webbing an inflatable member formed of a heat resisting material. .Iaddend..Iadd.18. A method for providing occupant protection according to claim 15, 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..Iadd.19. A method for providing occupant protection according to claim 15, wherein the leak detection control unit includes a sensor, and the method further comprises the step of detecting gas with the sensor, thereby detecting a change in pressure of the inflatable member while the tongue and the buckle are engaged. .Iaddend.