Inflatable seat belt having defined shape

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 a 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 inlet from the gas generating device inside thereof and a buckle which detachably engages the tongue. The envelope part is made of a knitted fabric expanded in the weft direction in a range of contacting the chest of the occupant when the envelope part is inflated. The inflatable seat belt apparatus includes an inflation restricting device for restricting the expansion in the weft direction besides the range.

What is claimed is:  
     
       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 fixed to the webbing and contacting the occupant when the webbing is worn, the inflatable portion including an elastic, heat- resistant  inflatable tube having an elongated shapeand heat resistance , and fixed to the webbing; a knitted, flat member in a flat form and  connected at both longitudinal ends to the webbing to entirely cover the inflatable tube, said knitted member having elasticity in a direction perpendicular to a longitudinal direction of the webbing and non-elasticity in the longitudinal direction of the webbing; and a non-expandable  cover for substantially completely covering the knitted member and having a joining portion extending along the longitudinal direction of the webbing without connecting to the knitted member, said joining portion having a first part corresponding to a chest of the occupant and at least one second part situated adjacent to the first part, said first part being weaker than the second part in strength;  
       a tongue fixed to the inflatable portion and having a gas flow path therein; and  
       a buckle attached to the vehicle and engagable to the tongue, said buckle having a port  body to supply a gas to the inflatable portion through the gas flow path of the tongue so that when the inflatable tube is inflated by the gas, the knitted member expands laterally at the portion corresponding to the first part while breaking the first part, expansion of the knitted member being restricted by the second part.  
     
     
       2. An inflatable seat belt according to claim  1 , wherein said first part is sandwiched between two second parts so that a center portion of the inflatable portion inflates. 
     
     
       3. An inflatable seat belt according to claim  2 , wherein said inflatable portion further includes a filter attached to the gas flow path of the tongue, said webbing extending throughout the entire inflatable portion, and said elastic inflatable tube having an elongated shape and completely surrounding the webbing and the filter. 
     
     
       4. An inflatable seat belt according to claim  2 , wherein said elastic inflatable tube has a shape corresponding to the webbing when the gas is not supplied and is made of silicone rubber . 
     
     
       5. An inflatable seat belt according to claim  4 , wherein said inflatable portion  tongue further includes an end fitting situated inside the  a filter and a caulking fitting situated over the cover to sandwich the filter, the inflatable tube, the knitted member and the cover therebetween, said tongue including a tongue pipe passing through the end fitting and the caulking fitting. 
     
     
       6. An inflatable seat belt according to claim  2 , wherein said inflatable portion further includes a filter attached to the gas flow path of the tongue, said webbing being fixed at one end to the filter, the  inflatable tube, the knitted member and the cover  without entirely extending throughout the inflatable portion. 
     
     
       7. An inflatable seat belt according to claim  6 , wherein said elastic inflatable tube has a shape corresponding to the webbing when the gas is not supplied and is made of silicone rubber . 
     
     
       8. An inflatable seat belt according to claim  4 , wherein said elastic inflatable tube is made of silicone rubber. 
     
     
       9. An inflatable seat belt according to claim  7 , wherein said elastic inflatable tube is made of silicone rubber. 
     
     
       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, 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; and    
       
         a cover disposed over the fabric member, wherein the cover restricts the shape and volume of the inflatable member after the inflatable member is inflated and deployed;  
       
       
         wherein the cover has a joining portion extending along the longitudinal direction of the elongated webbing, the joining portion having a first part and at least one second part, the first part being weaker in strength than the second part; and  
       
       
         wherein the joining portion of the cover is not attached to the fabric member. 
       
     
     
       11. An inflatable occupant protection device according to claim  10 , further comprising a tongue fixed to the inflatable member and having a gas flow path therein. 
     
     
       12. An inflatable occupant protection device according to claim  11 , further comprising a buckle, the buckle being engageable with the tongue and having a body to supply a gas to the inflatable member through the gas flow path of the tongue. 
     
     
       13. An inflatable occupant protection device according to claim  12 , wherein the inflatable member further includes a filter attached to the gas flow path of the tongue. 
     
     
       14. An inflatable occupant protection device according to claim  11 , wherein the inflatable member is made of a heat resistant material. 
     
     
       15. An inflatable occupant protection device according to claim  14 , wherein the heat resistant material is silicone rubber. 
     
     
       16. An inflatable occupant protection device according to claim  10 , wherein the fabric member is tubular knitted textile member. 
     
     
       17. An inflatable occupant protection device according to claim  16 , wherein the tubular knitted textile member is plain- stitched.   
     
     
       18. 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 the fabric member in a direction transverse to a longitudinal direction of the elongated webbing; and    
       
         fixing a cover over the fabric member;  
       
       
         wherein the cover restricts the shape and volume of the inflatable member after the inflatable member is inflated and deployed, and  
       
       
         wherein the cover has a joining portion extending along the longitudinal direction of the elongated webbing, the joining portion having a first part and at least one second part, the first part being weaker in strength than the second part; and  
       
       
         wherein fixing the cover comprises fixing the cover over the fabric member without attaching the joining portion of the cover to the fabric member. 
       
     
     
       19. A method for providing occupant protection according to claim  11 , further comprising the step of providing a tongue fixedly connected to the inflatable member and having a gas flow path therein. 
     
     
       20. A method for providing occupant protection according to claim  19 , 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. 
     
     
       21. A method for providing occupant protection according to claim  19 , further comprising the step of attaching a filter to the tongue.