Composite bow mono-leaf spring

Abstract

A fiberglass composite monoleaf bow spring for use in a vehicle chassis system capable of multi-linear response when compressed. The fiberglass composite monoleaf bow spring extends longitudinally below a vehicle frame and is secured at each end of the vehicle frame typically using a pair of pinned end attachments and is secured in the middle to an axle. The spring has a central upwardly curved region introduced between two downwardly curved regions that are introduced between two more upwardly curved regions. The spring can be made using either a pre-preg process or three-dimensional weaving process. By varying the curvature either the upwardly curved regions or downwardly curved regions, or by varying the length and width of the bow spring, the rate of displacement along each portion of the multi-linear deflection response curve may be controlled.

What is claimed is:  
     
         1 . A monoleaf bow spring comprising: 
 a central concave region;    a pair of convex regions, one of said pair of convex regions located adjacent to one side of said central concave region and the other of said pair of convex regions located adjacent to the other side of said central concave region; and    a pair of outer concave regions, each of said concave regions having an attachment region, wherein one of said pair of outer concave regions is located adjacent to said one of said pair of convex regions and the other of said pair of outer concave regions is located adjacent to said other of said pair of convex regions.    
     
     
         2 . The monoleaf bow spring of  claim 1 , wherein the monoleaf bow spring is symmetrical about a vertical axis running through the middle of said central concave region.  
     
     
         3 . The monoleaf bow spring of  claim 1 , wherein said central concave region curves upward at a first angle relative to a horizontal axis.  
     
     
         4 . The monoleaf bow spring of  claim 3 , wherein said first angle is between approximately ten degrees and sixty degrees relative to said horizontal axis.  
     
     
         5 . The monoleaf bow spring of  claim 1 , wherein the monoleaf bow spring is asymmetrical about a vertical axis running through the middle of said central concave region.  
     
     
         6 . The monoleaf bow spring of  claim 1 , wherein the monoleaf bow spring is comprised of a fiberglass composite material.  
     
     
         7 . The monoleaf bow spring of  claim 1 , wherein one of said pair of convex regions curves downward at a second angle relative to a second horizontal axis, said second angle being between zero and forty-five degrees relative to said second horizontal axis; 
 wherein the other of said pair of convex regions curves downward at a third angle relative to a third horizontal axis, said third angle being between zero and forty-five degrees relative to said third horizontal axis;    wherein one of said pair of outer concave regions curves upward at a fourth angle relative to a fourth horizontal axis, said fourth angle being between ten and eighty degrees relative to said fourth horizontal axis; and    wherein the other of said pair of outer concave regions curves upward at a fifth angle relative to a fifth horizontal axis, said fifth angle being between ten and eighty degrees relative to said fifth horizontal axis.    
     
     
         8 . The monoleaf bow spring of  claim 1 , wherein said outer concave regions each have an integral pinned end attachment for securing the monoleaf spring to a vehicle frame of a vehicle chassis system.  
     
     
         9 . The monoleaf bow spring of  claim 9 , wherein each of said an integral pinned end attachments comprises a molded-in pinned end attachment.  
     
     
         10 . The monoleaf bow spring of  claim 1 , wherein said monoleaf spring achieves a multi-linear deflection response when compressed under a load demand.  
     
     
         11 . A method for making a composite monoleaf bow spring for use in a chassis system, the method comprising the steps of: 
 three dimensional weaving a plurality of glass fibers into a preform;    placing said preform into a mold;    adding a first quantity of curable resin to said preform to form a composite;    molding said composite to a desired shape, said desired shape comprising a middle upwardly curved region, a pair of downwardly curved regions, and a second pair of upwardly curved regions, said second pair of upwardly curved regions each having a pinned end attachment; and    removing said composite from said mold.    
     
     
         12 . The method of  claim 11 , wherein the step of three dimensional weaving a plurality of glass fibers onto a preform comprises the step of weft knitting a plurality of E-type glass fibers into a preform.  
     
     
         13 . The method of  claim 11 , wherein the step of three dimensional weaving a plurality of glass fibers onto a preform comprises the step of warp knitting a plurality of E-type glass fibers into a preform.  
     
     
         14 . The method of  claim 11 , wherein the composite spring having said desired shape has a multi-linear spring rate when compressed.  
     
     
         15 . The method of  claim 11 , wherein the step of adding a first quantity of curable resin to said preform comprises the step of adding a first quantity of curable epoxy resin to said preform.  
     
     
         16 . The method of  claim 11  further comprising the step of securing each end of the composite bow mono-leaf spring to a vehicle frame and securing said middle upwardly curved region of the composite bow mono-leaf spring to an axle.  
     
     
         17 . The method of  claim 16 , wherein the step of securing each end of the composite bow mono-leaf spring to a vehicle frame comprises the steps of: 
 comolding a pinned end attachment into each end of the composite bow monoleaf spring;    inserting a bolt through one of said pinned end attachments and through a front pair of holes in a vehicle frame to secure one of said pinned end attachment to said vehicle frame;    inserting a second bolt through the other of said pinned end attachments and through a back pair of holes in said vehicle frame to secure said other of said pinned end attachments to said vehicle frame.    
     
     
         18 . The method of  claim 16 , wherein the step of securing each end of the composite bow mono-leaf spring to a vehicle frame comprises the steps of: 
 comolding a pinned end attachment into each end of the composite bow monoleaf spring, each of said pinned end attachments having a bolt secured within said pinned end attachment;    inserting one of said pinned end attachments through a front pair of holes in a vehicle frame to secure said one of said pinned end attachments to said vehicle frame; and    inserting the other of said pinned end attachments through a back pair of holes in said vehicle frame to secure said other of said pinned attachments to said vehicle frame.    
     
     
         19 . A method for making a composite monoleaf bow spring for use in a chassis system, the method comprising the steps of: 
 stacking a plurality of layers of pre-preg tape on top of each other, wherein each of said plurality of layers is comprises of a plurality of unidirectional fibers and a quantity of polymer resin; and    compacting and heating said plurality of layers to a first desired shape, said first desired shape comprising a middle upwardly curved region, a pair of downwardly curved regions, and a second pair of upwardly curved regions, said second pair of upwardly curved regions each having a pinned end attachment.    
     
     
         20 . The method of  claim 19  further comprising the step of securing each end of said pinned end attachments to a vehicle frame and securing said middle upwardly curved region to a vehicle axle.