Tubular energy management system for absorbing impact energy

Abstract

An energy-absorbing system includes a tube made of a continuous material, such as heat-treatable steel. The tube has first and second ring sections connected by an intermediate section. In one aspect, the intermediate section is flared and/or pinched to cause one tube section to predictably telescopingly roll upon impact. In another aspect, one section is annealed to optimize elongation and yield properties to facilitate rolling upon impact. By this arrangement, upon the bumper system receiving a longitudinal impact, the first and second ring sections telescopingly collapse with a predictable and consistent rolling collapse. Methods related to the above are also disclosed.

1 . An energy management tube adapted to reliably and predictably absorb substantial impact energy when impacted longitudinally, comprising: 
 a first tube section;    a second tube section aligned with the first tube section;    an intermediate tube section with first and second end portions integrally connecting the first and second tube sections, respectively;    the first tube section being dimensionally larger in size than the second tube section, and the intermediate tube section having a shape transitioning from the first tube section to the second tube section;    a crushable support member positioned inside the first tube section and configured to crush and to simultaneously assist in controlling rolling of materials upon receiving a longitudinal impact; and    a support member positioned inside the first end portion and supporting the second end portion, the support member providing additional resistance to rolling.    
   
   
       2 . The energy management tube defined in  claim 1 , wherein the support member engages the intermediate tube section.  
   
   
       3 . The energy management tube defined in  claim 2 , wherein the support member has an elongated constant shape that matably fits within the first tube section.  
   
   
       4 . A shock absorber comprising: 
 the smaller-diameter tube portion and the larger-diameter tube portion which are integrally formed by partially reducing or partially enlarging a straight tube that can be plastically deformable; and    a step portion formed continuously between an edge of the smaller-diameter tube portion and the larger-diameter tube portion by folding the edge back to each tube portion;    wherein a frictional member is mounted in an interior of the larger-diameter tube portion in order to control an amount of absorption of impact energy applied.    
   
   
       5 . A shock absorber according to  claim 4 , wherein the step portion comprises a sectional structure in which a cross-sectional circular arc-shaped annular folded-back portion of the smaller-diameter tube portion has a smaller radius of curvature in a cross section thereof, a cross-sectional circular arc-shaped annular folded-back portion of the larger-diameter tube portion has a larger radius of curvature in a cross section thereof, and an annular side surface joins edges of the annular folded-back portions through edges thereof, thereby forming the step portion integrally in S-shaped cross section.  
   
   
       6 . A shock absorber according to  claim 4 , wherein the frictional member is an annular elastic member having an outer diameter which is smaller than an inner diameter of the larger-diameter tube portion and an inner diameter of which is larger than an outer diameter of the smaller-diameter tube portion, and the annular elastic member is inserted to an interior of the larger-diameter tube portion.  
   
   
       7 . A shock absorber according to  claim 4 , wherein the frictional member is an annular elastic member having an outer diameter which is substantially equal to an inner diameter of the larger-diameter tube portion and an inner diameter of which is larger than an outer diameter of the annular folded-back portion of the smaller-diameter tube portion, the annular elastic member being press-inserted to the interior of the larger-diameter tube portion.  
   
   
       8 . A shock absorber comprising a smaller-diameter tube portion and a larger-diameter tube portion integrally formed by partially reducing or partially enlarging a plastically deformable straight tube, and a step portion that joins the smaller-diameter tube portion and the larger-diameter tube portion, wherein: 
 both a folded-back portion of the smaller-diameter tube portion and a folded-back portion of the larger-diameter tube portion, joining to each other through the step portion, have a circular arc-shaped section with an arcuate angle more than 90 degrees; and    the step portion is formed to have an S-shaped section by joining the folded-back portion of the smaller-diameter tube portion and the folded-back portion of the larger-diameter tube portion.    
   
   
       9 . The shock absorber according to  claim 8 , wherein: 
 the step portion is formed to have an S-shaped section, in which the radius of the circular arc-shaped section of the folded-back portion of the smaller-diameter tube portion is made smaller than that of the circular arc-shaped section of the folded-back portion of the larger-diameter tube portion.    
   
   
       10 . The shock absorber according to  claim 8 , wherein: 
 the step portion is formed to have an S-shaped section by joining the folded-back portion of the smaller-diameter tube portion and the folded-back portion of the larger-diameter tube portion through an annular side surface.