Method of improving impact absorbing and deformation control characteristics of vehicle components

Abstract

A crush rail or other structural member of a vehicle is provided with crush triggers. The crush triggers are formed by heating localized areas of the crush rail or other part and allowing them to cool slowly to provide increased ductility and reduced strength in a localized region. The crush rail is designed to collapse in a series of convolutions in a regular and repeated pattern. Crush triggers may be provided on body pillars, steering columns, drive shafts, engine support cradles, and other parts of a vehicle. A plurality of crush triggers may be provided on a single structural member depending upon impact absorption requirements.

1 . A body pillar assembly of a vehicle comprising: 
 an elongated pillar formed of a heat treatable alloy, the pillar having a bottom end attached to the chassis of the vehicle and a top end attached to the body of the vehicle at a point spaced above the chassis of the vehicle; and    at least one crush trigger made by heat treating a localized area of the pillar to reduce locally the yield strength and increase the ductility of the pillar.    
   
   
       2 . The body pillar assembly of  claim 1  wherein the crush trigger is created by means of induction heating.  
   
   
       3 . The body pillar assembly of  claim 1  wherein the crush trigger is heated circumferentially.  
   
   
       4 . The body pillar assembly of  claim 1  wherein one crush trigger is provided proximate the top end of the pillar, and a second crush trigger is provided proximate the bottom end of the pillar which is attached to the chassis.  
   
   
       5 . A steering column assembly of a vehicle having improved crash worthiness, comprising: 
 steering column component made from a heat treatable tube having circular cross section, the steering column component having a first end that is closest to a steering wheel and a second end that is closest to the steering gear; and    a crush trigger created by heat treating a localized area of the metal to decrease the yield strength and increase the ductility of the metal, the crush trigger being on the end of the elongated member that is attached to the steering gear.    
   
   
       6 . The steering column assembly of  claim 5  wherein the crush trigger is made by means of induction heating.  
   
   
       7 . The steering column assembly of  claim 5  wherein the crush trigger is heat treated circumferentially.  
   
   
       8 . A drive shaft for a rear wheel drive vehicle with improved crash worthiness, comprising: 
 an elongated member made from a heat treatable metal, having a circular cross section, and having two ends, one end being attached to a transmission, and the other end being attached to a rear differential gear assembly; and    a crush trigger created by heat treating the metal to decrease the yield strength and increase the ductility of the metal, the crush trigger being on the end of the drive shaft that is connected to the rear differential assembly.    
   
   
       9 . The drive shaft of  claim 8  wherein the elongated member is formed by means of extrusion.  
   
   
       10 . An engine support frame with improved crash worthiness, comprising: 
 an engine cradle made of a heat treatable metal; and    a crush trigger created by heat treating the engine cradle to locally reduce the yield strength and increase the ductility of the engine cradle.    
   
   
       11 . A steering wheel for a vehicle, comprising: 
 a hub assembly adapted to be connected to a steering column assembly;    a ring formed of a heat treatable alloy and being secured to the hub assembly; and    at least one area being formed on the ring by locally heating the area to reduce its strength and increase its ductility so that local area will more easily bend in a collision than other portions of the ring.