Abstract:
A vehicle frame assembly has an energy absorbing structure including a first portion having a first generally uniform dimension. A second portion extends from the first portion and has a second generally uniform dimension that is greater than the first generally uniform dimension of the first portion, thereby defining a first shoulder between the first portion and the second portion. A third portion extends from the second portion and has a third generally uniform dimension that is less than the first generally uniform dimension of the first portion, thereby defining a second shoulder between the second portion and the third portion. The second portion has at least one stiffening rib formed therein. The third portion has at least one stiffening rib formed therein that is discontinuous with the stiffening rib formed in the second portion. The energy absorbing structure is adapted to be deformed during a collision such that the third portion is moved within the second portion to absorb energy.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to body and frame assemblies for vehicles. More specifically, this invention relates to an improved structure for such a vehicle body and frame assembly that includes a structure that is capable of absorbing energy in a controlled manner during a collision, thereby providing additional safety to the occupants of the vehicle. 
     Many land vehicles in common use, such as automobiles, vans, and trucks, include a body and frame assembly that is supported upon a plurality of ground-engaging wheels by a resilient suspension system. The structures of known body and frame assemblies can be divided into two general categories, namely, separate and unitized. In a typical separate body and frame assembly, the structural components of the body portion and the frame portion of the vehicle are separate and independent from one another. When assembled, the frame portion of the assembly is resiliently supported upon the vehicle wheels by the suspension system and serves as a platform upon which the body portion of the assembly and other components of the vehicle can be mounted. Separate body and frame assemblies of this general type are found in most older vehicles, but remain in common use today for many relatively large or specialized use modern vehicles, such as large vans, sport utility vehicles, and trucks. In a typical unitized body and frame assembly, the structural components of the body portion and the frame portion are combined into an integral unit that is resiliently supported upon the vehicle wheels by the suspension system. Unitized body and frame assemblies of this general type are found in many relatively small modern vehicles, such as automobiles and minivans. 
     A recent trend in the development of passenger, sport utility, pickup truck, and other vehicles has been to design the various components of the vehicle in such a manner as to absorb energy during a collision, thereby providing additional safety to the occupants of the vehicle. As a part of this trend, it is known to design portions of the vehicle body and frame assembly so as to be at least partially collapsible during a collision so as to absorb to energy. To accomplish this, it is known to form such portions of the vehicle body and frame assembly to have corrugated or similarly deformed shapes that are somewhat weaker than the other non-deformed portions of the vehicle body and frame assembly. During a collisions, such deformed portions are designed to be the first portions of the vehicle body and frame assembly that are axially collapsed. Thus, the absorption of energy during a collision occurs in a somewhat controlled manner. A variety of such pre-deformed axially collapsible vehicle body and frame assembly structures are known in the art. Nonetheless, it would be desirable to provide an improved structure for a vehicle body and frame assembly including a structure that is capable of absorbing energy in a controlled manner during a collision, thereby providing additional safety to the occupants of the vehicle. In particular, it would also be desirable to provide such an energy absorbing structure that is replaceable after a collision. 
     SUMMARY OF THE INVENTION 
     This invention relates to a vehicle frame assembly including a structure that is capable of absorbing energy in a controlled manner during a collision, thereby providing additional safety to the occupants of the vehicle. The vehicle frame assembly can include a pair of longitudinally extending side rails having a plurality of transverse cross members extending therebetween. One or more energy absorbing structures can be provided at the front end of each of the side rails or elsewhere on the vehicle frame assembly. In a first embodiment, the energy absorbing structure includes a hollow nose cap that is secured to the front end of the side rail. The nose cap includes a first portion that is received telescopically with the front end of the side rail and a second portion that extends from the first portion. The second portion of the nose cap is preferably formed integrally with the first portion and has an outer size that is larger than the outer size of the first portion so as to define a first shoulder therebetween. The nose cap further includes a third portion that extends from the second portion and has an outer size that is somewhat smaller than the inner size of the second portion so as to define a second shoulder therebetween. If a relatively large force is exerted against the outermost end of the third portion of the nose cap, the second shoulder will bend, allowing the third portion of the nose cap to move telescopically inwardly relative to the second portion. Such bending of the second shoulder and concurrent telescopic movement of the third portion within the second portion absorbs energy from the collision. In a second embodiment, the energy absorbing structure includes a first portion that is formed integrally with the front end of the side rail and a second portion that extends therefrom. The second portion is preferably formed having an outer size that is somewhat smaller than the inner size of the first portion so as to define a shoulder therebetween. In a third embodiment, the energy absorbing structure includes a first hollow member that is received telescopically with the front end of the side rail in engagement with one or more inwardly extending first tabs formed thereon. Similarly, a second hollow member is received telescopically with the first hollow member in engagement with one or more inwardly extending second tabs formed thereon. If a relatively large force is exerted against the outermost end of the second member, the tabs will bend, allowing the second member to move telescopically inwardly relative lo the first member and the first member to move telescopically inwardly relative to the front end of the side rail. Such bending of the tabs and concurrent telescopic movement of the members absorbs energy from the collision. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a vehicle frame assembly including a first embodiment of an energy absorbing structure in accordance with this invention. 
     FIG. 2 is an enlarged sectional elevational view of the first embodiment of the energy absorbing structure illustrated in FIG. 1 prior to being axially collapsed. 
     FIG. 3 is an enlarged sectional elevational view similar to FIG. 2 showing the first embodiment of the energy absorbing structure after being axially collapsed. 
     FIG. 4 is a perspective view of a vehicle frame assembly including a second embodiment of an energy absorbing structure in accordance with this invention. 
     FIG. 5 is an enlarged sectional elevational view of the second embodiment of the energy absorbing structure illustrated in FIG. 5 prior to being axially collapsed. 
     FIG. 6 is a perspective view of a vehicle frame assembly including a third embodiment of an energy absorbing structure in accordance with this invention. 
     FIG. 7 is an enlarged sectional elevational view of the third embodiment of the energy absorbing structure illustrated in FIG. 7 prior to being axially collapsed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, there is illustrated in FIG. 1 a portion of a first embodiment of a vehicle body frame assembly, indicated generally at  10 , in accordance with this invention. The vehicle frame assembly  10  is generally conventional in the art, and only those portions thereof that are necessary for a complete understanding of this invention will be described and illustrated. Furthermore, it will be appreciated that the illustrated vehicle frame assembly  10  is intended to be representative of any conventional structure, separate or unitized, for a frame assembly for use in a vehicle. The illustrated vehicle frame assembly  10  is a ladder frame assembly including a pair of longitudinally extending side rails  11  and  12  or similar structural members having a plurality of transverse cross members  13 ,  14 ,  15 ,  16 , and  17  extending therebetween. The side rails  11  and  12  extend longitudinally throughout the entire length of the assembly  10  and are generally parallel to one another. Each of the side rails  11  and  12  in the illustrated embodiment is formed from a single closed channel structural member. However, it will be appreciated that one or both of the side rails  11  and  12  may be formed from a plurality of individually formed closed channel structural members that are secured together by any conventional means, such as by welding, riveting, bolting, and the like. Furthermore, portions of the side rails  11  and  12  may be formed from open channel structural members if desired. 
     The cross members  13  through  17  extend generally perpendicular to the side rails  11  and  12  and may be formed having any conventional structure. The cross members  13  through  17  are spaced apart from one another along the length of the ladder frame assembly  10  and can be secured to the side rails  11  and  12  by any conventional means, such as by welding, riveting, bolting, and the like. When secured to the side rails  11  and  12 , the cross members  13  through  17  provide lateral and torsional rigidity to the ladder frame assembly  10 . The structure of the vehicle body and frame assembly thus far described is conventional in the art. 
     An energy absorbing structure, indicated generally at  20 , is provided at the front end of each of the side rails  11  and  12  of the vehicle body and frame assembly  10 . However, it will be appreciated that the energy absorbing structure  20  may be provided at any desired location on the vehicle body and frame assembly  10 . The structure of one of the energy absorbing structures  20  is illustrated in FIG.  2 . As shown therein, the energy absorbing structure  20  includes a hollow nose cap, indicated generally at  21 , that is secured to the front end of the side rail  11  in a conventional manner, such as by one or more welds  22 . The illustrated nose cap  21  is formed having a generally rectangular cross sectional shape that corresponds with the cross sectional shape of the front end of the side rail  11 . However, the nose cap  21  may be formed having any desired cross sectional shape. 
     The nose cap  21  includes a first portion  23  that is received telescopically with the front end of the side rail  11 . Preferably, the first portion  23  is formed having an outer size that is only slightly smaller than an inner size of the front end of the side rail  11 . Thus, the first portion  23  of the nose cap  21  is received snugly within the front end of the side rail  11 . In this manner, the first portion  23  of the nose cap  21  can be mechanically supported within the front end of the side rail  11 . 
     The nose cap  21  also includes a second portion  24  that extends from the first portion  23 . The second portion  24  of the nose cap  21  is preferably formed integrally with the first portion  23 , although such is not necessary. The second portion  24  of the nose cap  21  is preferably formed having an outer size that is larger than the outer size of the first portion  23  so as to define a first shoulder  24   a  therebetween, although such is not necessary. The first shoulder  24   a  provides a structure for positively positioning the nose cap  21  relative to the front end of the side rail  11  prior to securement thereto by the welds  22 . The second portion  24  of the nose cap  21  is preferably formed having an outer size that is approximately the same as or only slightly smaller that the outer size of the front end of the side rail  11 . Thus, the outer surfaces of the nose cap  21  and the front end of the side rail  11  are preferably substantially flush when secured together. If desired, one or more embossed stiffening ribs  24   b  may be formed in the second portion  24  of the nose cap  21  for a purpose that will be described below. 
     The nose cap  21  further includes a third portion  25  that extends from the second portion  24 . The third portion  25  of the nose cap  21  is preferably formed integrally with the second portion  24 , although such is not necessary. The third portion  25  of the nose cap  21  is preferably formed having an outer size that is somewhat smaller than the inner size of the second portion  24  so as to define a second shoulder  25   a  therebetween. If desired, one or more embossed stiffening ribs  25   b  may be formed in the third portion  25  of the nose cap  21  for a purpose that will be described below. 
     FIG. 2 illustrates the energy absorbing structure  20  during normal operation of the vehicle body and frame assembly  10 . If the front end of the vehicle frame assembly  10  collides with an object at a relatively low speed, a relatively small force will be exerted against the outermost end of the third portion  25  of the nose cap  21 . So long as the magnitude of such a relatively small force is not sufficient to overcome the strength of the second shoulder  25   a,  then the nose cap  21  will remain substantially as shown in FIG.  2 . 
     However, if the front end of the vehicle frame assembly  10  collides with an object at a relatively high speed, a relatively large force will be exerted against the outermost end of the third portion  25  of the nose cap  21 . The exertion of such a relatively large force causes the second shoulder  25   a  to bend, allowing the third portion  25  of the nose cap  21  to move telescopically inwardly relative to the second portion  24 , as shown in FIG.  3 . Such bending of the second shoulder  25   a  and concurrent telescopic movement of the third portion  25  within the second portion  24  absorbs energy from the collision. As a result, additional safety is provided to the occupants of the vehicle. The stiffening ribs  24   b  and  25   b  provided on the second and third portions  24  and  25  of the nose cap  21  are provided to maintain the second and third portions  24  and  25  in their original shapes during the collision. This is done to facilitate the absorption of energy in a controlled manner during a collision. Because the nose cap  21  is formed as a separate piece from the side rail  11 , it can be removed from the side rail  11  with relative ease after a collision and replace with another non-deformed nose cap  21 . 
     Referring now to FIGS. 4 and 5, there is illustrated a portion of a second embodiment of a vehicle body frame assembly, indicated generally at  10 ′, in accordance with this invention. The second embodiment of the vehicle frame assembly  10 ′ is generally the same as the first embodiment of the vehicle frame assembly  10  described above, and like reference numbers are used to indicate similar structures. An energy absorbing structure, indicated generally at  30 , is provided at the front end of each of the side rails  11  and  12  of the vehicle body and frame assembly  10 ′. However, it will be appreciated that the energy absorbing structure  30  may be provided at any desired location on the vehicle body and frame assembly  10 ′. The structure of one of the energy absorbing structures  30  is illustrated in FIG.  5 . As shown therein, the energy absorbing structure  30  includes a first portion  31  that is formed integrally with the front end of the side rail  11 . The illustrated first portion  31  is formed having a generally rectangular cross sectional shape that corresponds with the cross sectional shape of the front end of the side rail  11 . However, the first portion  31  may be formed having any desired cross sectional shape. The energy absorbing structure  30  also includes a second portion  32  that extends from the first portion  31 . The second portion  32  is preferably formed integrally with the first portion  31 , although such is not necessary. The second portion  32  is preferably formed having an outer size that is somewhat smaller than the inner size of the first portion  31  so as to define a shoulder  32   a  therebetween. If desired, one or more embossed stiffening ribs  32   b  may be formed in the second portion  32  of the energy absorbing structure  30 . The energy absorbing structure  30  functions in the same manner as the energy absorbing structure  20  discussed above. 
     Referring now to FIGS. 6 and 7, there is illustrated a portion of a third embodiment of a vehicle body frame assembly, indicated generally at  10 ″, in accordance with this invention. The third embodiment of the vehicle frame assembly  10 ″ is generally the same as the first embodiment of the vehicle frame assembly  10  described above, and like reference numbers are used to indicate similar structures. 
     An energy absorbing structure, indicated generally at  40 , is provided at the front end of each of the side rails  11  and  12  of the vehicle body and frame assembly  10 . However, it will be appreciated that the energy absorbing structure  40  may be provided at any desired location on the vehicle body and frame assembly  10 ″. The structure of one of the energy absorbing structures  40  is illustrated in FIG.  7 . As shown therein, the front end of the side rail  11  has at least one, and preferably a plurality, of tabs  11   a  formed therein that extend inwardly into the interior thereof. Such tabs  11   a  can be formed in any conventional manner, such as by punching or cutting and bending. The purpose for such tabs  11   a  will be explained below. 
     The energy absorbing structure  40  includes a first hollow member  41  that is secured to the front end of the side rail  11 . The illustrated first member  41  is formed having a generally rectangular cross sectional shape that corresponds with the cross sectional shape of the front end of the side rail  11 . However, the first member  41  may be formed having any desired cross sectional shape. If desired, an end  41   a  of the first member  41  may be formed having a frusto-conical or otherwise reduced dimensional shape. The purpose for this reduced dimension end  41   a  will be explained below. The first member  41  is received telescopically with the front end of the side rail  11  such that the reduced dimension end  41   a  of the first member  41  abuts the tabs  11   a  extending within the side rail  11 . Preferably, the first member  41  is formed having an outer size that is only slightly smaller than an inner size of the front end of the side rail  11 . Thus, the first member  41  is received snugly within the front end of the side rail  11 . In this manner, the first member  41  can be mechanically supported within the front end of the side rail  11 . The first member  41  can be secured to the front end of the side rail  11  by any conventional means, such as by one or more welds  41   b.  The front end of the first member  41  has at least one, and preferably a plurality, of tabs  41   c  formed therein that extend inwardly into the interior thereof. Such tabs  41   a  can be formed in any conventional manner, such as by punching or cutting and bending. The purpose for such tabs  41   a  will be explained below. 
     The energy absorbing structure  40  further includes a second hollow member  42  that is secured to the front end of the first member  41 . The illustrated second member  42  is formed having a generally rectangular cross sectional shape that corresponds with the cross sectional shape of the first member  41 . However, the second member  42  may be formed having any desired cross sectional shape. If desired, an end  42   a  of the second member  42  may be formed having a tapered or otherwise reduced dimensional shape. The purpose for this reduced dimension end  42   a  will be explained below. The second member  42  is received telescopically with the front end of the first member  41  such that the reduced dimension end  42   a  of the second member  42  abuts the tabs  41   c  extending within the first member  41 . Preferably, the second member  42  is formed having an outer size that is only slightly smaller than an inner size of the first member  41 . Thus, the second member  42  is received snugly within the first member  41 . In this manner, the second member  42  can be mechanically supported within the front end of the side rail  11 . The second member  42  can be secured to the first member  41  by any conventional means, such as by one or more welds  42   b.    
     FIG. 7 illustrates the energy absorbing structure  40  during normal operation of the vehicle body and frame assembly  10 ″. If the front end of the vehicle frame assembly  10 ″ collides with an object at a relatively low speed, a relatively small force will be exerted against the outermost end of the second member  42 . So long as the magnitude of such a relatively small force is not sufficient to overcome the strength of the tabs  11   a  and  41   c,  then the energy absorbing structure  40  will remain substantially as illustrated in FIG.  7 . 
     However, if the front end of the vehicle frame assembly  10 ″ collides with an object at a relatively high speed, a relatively large force will be exerted against the outermost end of the second member  42 . The exertion of such a relatively large force causes the tabs  42   c  to bend, allowing the second member  42  to move telescopically inwardly relative to the first member  41 . Such bending of the tabs  42   c  and concurrent telescopic movement of the second member  42  within the first member  41  absorbs energy from the collision. In some instances, the exertion of such a relatively large force also causes the tabs  11   a  to bend, allowing the first member  41  to move telescopically inwardly relative to the front end of the side rail  11 . Such bending of the tabs  11   a  and concurrent telescopic movement of the first member  41  within the front end of the side rail  11  absorbs additional energy from the collision. As a result, additional safety is provided to the occupants of the vehicle. 
     Because the first and second members  41  and  42  are formed as separate pieces from the side rail  11 , they can be removed from the side rail  11  with relative ease after a collision and replace with another non-deformed nose cap  21 . Furthermore, it will be appreciated that the energy absorbing device  40  may include only one such member or three or more of such members if desired. Although not illustrated in FIGS. 6 and 7, either or both of the first and second members  41  and  42  may be formed having stiffening ribs for the same purpose as described above. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.