Patent Publication Number: US-8967700-B2

Title: Motor vehicles having bumper counter rotation brackets

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/296,701 filed Nov. 15, 2011. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally directed to motor vehicles having bumper counter rotation brackets, and is specifically directed to bumper counter rotation brackets that apply moment loads to the structure of the motor vehicles. 
     BACKGROUND 
     Motor vehicles are required to maintain structural integrity of vehicle subsystems in the event of a collision with another vehicle or stationary object. In order to dissipate energy associated with a collision, vehicles include bumpers that absorb energy by resisting impact and/or deforming to prevent a colliding vehicle from damaging the vehicle subsystems. 
     As the speed at which a collision takes places increases, the energy required to be dissipated by the bumper of the vehicle increases. The requirement to dissipate increased energy may be complicated by uneven bumper heights of the colliding vehicles. Because the bumpers of the colliding vehicles do not contact one another evenly, the energy dissipation systems of the vehicles may not activate in the event of a collision, which may lead to damage to vehicle subsystems. 
     Accordingly, alternative systems and methods for dissipating the energy of a vehicle collision are needed. 
     SUMMARY 
     In one embodiment, a motor vehicle includes a first side member having a first lower dart and a first upper dart, where the first upper dart is positioned between the first lower dart and an end portion of the first side member. The motor vehicle also includes a second side member parallel with and spaced apart from the first side member, the second side member having a second lower dart and a second upper dart, where the second upper dart is positioned between the second lower dart and an end portion of the second side member. The motor vehicle further includes a first bumper bracket coupled to the end portion of the first side member, a second bumper bracket coupled to the end portion of the second side member, a bumper reinforcement member coupled to the first and second bumper brackets, and a counter rotation bracket coupled to the bumper reinforcement member and extending upwards from the bumper reinforcement member. The lower darts and the upper darts form a preferential buckling zone of the first and the second side members. 
     In another embodiment, an impact energy dissipation system for a vehicle structure including a first bumper bracket and a second bumper bracket coupling the system to the vehicle structure, a bumper reinforcement member coupled to the first and second bumper brackets and having a bumper height, and a counter rotation bracket coupled to and extending upwards from the bumper reinforcement member, where the counter rotation bracket has a bracket height that is at least approximately 50% of the bumper height. 
     In yet another embodiment, a motor vehicle includes a first side member having a first lower dart and a first upper dart, where the first upper dart is positioned rearward of the first lower dart. The motor vehicle also includes a second side member parallel with and spaced apart from the first side member, the second side member having a second lower dart and a second upper dart, where the second upper dart is positioned rearward of the second lower dart. The motor vehicle further includes a first bumper bracket coupled to the end portion of the first side member, a second bumper bracket coupled to the end portion of the second side member, a first gusset coupled to the first side member and the first bumper bracket, and a second gusset coupled to the second side member and the second bumper bracket. The motor vehicle also includes a bumper reinforcement member coupled to the first and second bumper brackets, and a counter rotation bracket coupled to the bumper reinforcement member and extending upwards from the bumper reinforcement member, where the lower darts and the upper darts form a preferential buckling zone of the first and the second side members. 
     These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
         FIG. 1  depicts a perspective view of an impact energy dissipation system for a motor vehicle including a counter rotation bracket according to one or more embodiments shown and described herein; 
         FIG. 2  depicts a side view of a portion of the impact energy dissipation system for a motor vehicle of  FIG. 1  along line  2 - 2 ; 
         FIG. 3  depicts a side view of a motor vehicle including a counter rotation bracket in an undeformed state according to one or more embodiments shown and described herein; and 
         FIG. 4  depicts a side view of a motor vehicle including a counter rotation bracket in a deformed state according to one or more embodiments shown and described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an impact energy dissipation system for a vehicle structure is schematically depicted. The impact energy dissipation system generally includes first and second side members, first and second bumper brackets, a bumper reinforcement member, and a counter rotation bracket. The first and second side members each include a lower dart and an upper dart, where the upper darts are positioned between the lower darts and the end portions of the side members. The lower darts and the upper darts form a preferential buckling zone of the first and the second side members. The impact energy dissipation system further includes first and second bumper brackets coupled to the end portions of the respective side members, a bumper reinforcement member coupled to the bumper brackets, and a counter rotation bracket coupled to the bumper reinforcement member and extending upwards from the bumper reinforcement member. In the event of a collision with an incoming vehicle, the counter rotation bracket and the bumper reinforcement member contact the incoming vehicle, and may apply a moment load that tends to buckle the side members at the preferential buckling zone. The impact energy dissipation system and vehicles incorporating the same will be described in more detail herein with specific reference to the appended drawings. 
     Referring to  FIG. 1 , one embodiment of a motor vehicle  90  including an impact energy dissipation system  100  is schematically depicted. The vehicle structure  92  of the motor vehicle  90  includes a first side member  110  that includes a first lower dart  112  and a first upper dart  114 , where the first upper dart  114  is positioned between the first lower dart  112  and an end portion  116  of the first side member  110 . Similarly, vehicle structure  92  of the motor vehicle  90  includes a second side member  120  that includes a second lower dart  122  and a second upper dart  124 , where the second upper dart  124  is positioned between the second lower dart  122  and an end portion  126  of the second side member  120 . The impact energy dissipation system  100  of the motor vehicle  90  includes a first bumper bracket  130  coupled to the first side member  110  and a second bumper bracket  140  coupled to the second side member  120 . The impact energy dissipation system  100  further includes a bumper reinforcement member  150  coupled to the first and second bumper brackets  130 ,  140 , and a counter rotation bracket  160  coupled to the bumper reinforcement member  150  and extending upwards from the bumper reinforcement member  150 . 
     The first and second lower darts  112 ,  122  and the first and second upper darts  114 ,  124  form a preferential buckling zone  106  of the first and second side members  110 ,  120 . The lower darts  112 ,  122  and the upper darts  114 ,  124  arc local regions of the respective first and second side members  110 ,  120  that decrease the buckling strength of the first and second side members  110 ,  120 . As used herein, “buckling strength” refers to the maximum compressive strength an element can withstand before failing, where the compressive stress at the location of the failure is less than the compressive stresses the material of the element is capable of withstanding. The buckling strength of an element can be determined experimentally or approximated using analysis, for example, finite element analysis. The darts  112 ,  122 ,  114 ,  124  may take a variety of shapes, including having a chevron-like shape as illustrated in  FIGS. 3 and 4 . The darts  112 ,  122 ,  114 ,  124  can be locally deformed regions of the first and second side members  110 ,  120  that interrupt the otherwise continuous first and second side members  110 ,  120 . The darts  112 ,  122 ,  114 ,  124  reduce the buckling strength of the first and second side members  110 ,  120  such that, when the first and second side members  110 ,  120  are subject to an impact force directed along the length of the side member  110 ,  120 , the first and second side members  110 ,  120  tend to “close” the darts  112 ,  122 ,  114 ,  124 , encouraging controlled deformation of the first and second side members  110 ,  120 . 
     As illustrated in  FIG. 1 , in some embodiments, the impact energy dissipation system  100  of the motor vehicle  90  further includes a first gusset  132  coupled to the first side member  110  and the first bumper bracket  130 , and a second gusset  142  coupled to the second side member  120  and the second bumper bracket  140 . The first and second gussets  132 ,  142  may be located on the top surface  111 ,  121  of the respective first side member  110  and the second side member  120 . The first and second gussets  132 ,  142  are located between the upper darts  114 ,  124  and the end portions  116 ,  126  of the first and second side members  110 ,  120 . The first and second gussets  132 ,  142  provide reinforcement between the respective side member  110 ,  120  and the bumper bracket  130 ,  140 . The first and second gussets  132 ,  142  are adapted to absorb force and moment applied to the bumper brackets  130 ,  140  and direct any such force and moment into the respective side member  110 ,  120 . Additionally, the first and second gussets  132 ,  142  may terminate before the first and second upper darts  114 ,  124  of the first and second side members  110 ,  120  and concentrate any moment into the side members  110 ,  120  in regions local to the upper darts  114 ,  124 . 
     As discussed herein, the bumper reinforcement member  150  and the counter rotation bracket  160  may be located towards a front of the motor vehicle  90 , such that the bumper reinforcement member  150  forms a front vehicle bumper; or the bumper reinforcement member  150  and the counter rotation bracket  160  may be located towards a rear of the motor vehicle  90 , such that the bumper reinforcement member  150  forms a rear vehicle bumper. Discussion of the motor vehicle  90  below is made in reference to the bumper reinforcement member  150  and the counter rotation bracket  160  located towards a rear of the motor vehicle  90 . As depicted in  FIG. 1 , a forward-facing surface  133  of the first bumper bracket  130  is oriented to face towards the first side member  110  and the first gusset  132 . A forward-facing surface  143  of the second bumper bracket  140  is oriented to face towards the second side member  120  and the second gusset  142 . 
     Referring now to  FIG. 2 , the counter rotation bracket  160  and the bumper reinforcement member  150  are illustrated in cross-section. The counter rotation bracket  160  extends upwards from the bumper reinforcement member  150 . The counter rotation bracket  160  includes a contact portion  162  and a reinforcement portion  164 . The contact portion  162  is approximately parallel with a face of the bumper reinforcement member  150 , shown here approximately parallel to the rearward-facing surface  152 . As depicted in  FIG. 2 , the reinforcement portion  164  is transverse to the contact portion  152 . The contact portion  162  of the counter rotation bracket  160  is coupled to the bumper reinforcement member  150  at a contact flange  163 , while the reinforcement portion  164  of the counter rotation bracket  160  is coupled to the bumper reinforcement member  150  at a support flange  165 . As depicted in  FIG. 2 , the contact flange  163  may define a lip  168  that is generally parallel to and offset rearwardly from the contact portion  162  of the counter rotation bracket  160 . The lip may be positioned along the bumper reinforcement member  150  such that the contact flange  163  of the counter rotation bracket  160  overlaps both a portion of a top surface  158  of the bumper reinforcement member  150  and a portion of a rearward surface  159  of the bumper reinforcement member  150 . The support flange  165  of the counter rotation bracket  165  may be transverse to the reinforcement portion  164  of the counter rotation bracket  160 . The support flange  165  may be coupled to the top surface  158  of the bumper reinforcement member  150 . A variety of attachment methods are contemplated including, but not limited to, structural spot welding, welding, riveting, bolting, or adhesively bonding along the contact flange  163  and/or the support flange  165 . 
     Referring to  FIGS. 1 and 2 , the counter rotation bracket  160  is sized and positioned to provide increased protection to the motor vehicle  90  while allowing the counter rotation bracket  160  to be packaged within the bodywork of the motor vehicle  90 , including the bumper cover (not shown). The counter rotation bracket  160  extends a bracket width  167  that is at least approximately ⅓ of a distance  104  between the first side member  110  and the second side member  120 . The counter rotation bracket  160  also has a bracket height  166  that is at least approximately 50% of a bumper height  156  of the bumper reinforcement member  150 . Further, the first bumper bracket  130  has a first bumper bracket height  136  and the second bumper bracket  140  has a second bumper bracket height  146 . The first side member  110  has a first side member height  117  and the second side member  120  has a second side member height  127  as evaluated in a vertical direction  80 . As depicted in  FIGS. 1 and 3 , the first bumper bracket height  136  may be greater than the first side member height  117  and the second bumper bracket height  146  may be greater than the second side member height  127 . The first gusset  132  may have a first gusset height  137  and the second gusset  142  may have a second gusset height  147 . As further depicted in  FIGS. 1 and 3 , the first bumper bracket height  136  may be greater than the first gusset height  137  and the second bumper bracket height  146  may be greater than the second gusset height  147 . 
     Components of the motor vehicle  90  may be made from a variety of materials having appropriate material properties, including strength, modulus, impact resistance, and fracture toughness, for the application. The first and second side members  110 ,  120  may be made of a galvanized steel, for example, SCGA 570D. In one embodiment, the first and second side members  110 ,  120  may include a “top hat” design, where each of the first and second side members  110 ,  120  are a weldment formed by an inside and an outside portion of the first and second side members  110 ,  120 . The first and second bumper brackets  130 ,  140  may be made of a galvanized steel, for example SCGA 270D, and may be deep-drawn from sheet stock to the required shape. The bumper reinforcement member  150  may be made of an aluminum alloy and may be formed using an extrusion process. The counter rotation bracket  160  may be made of an aluminum alloy or a corrosion resistant steel and may be formed using an extrusion process. The first and second gussets  132 ,  142  may be made of a corrosion resistant steel, for example  440  stainless, and may be drawn from sheet stock to the required shape. 
     Referring now to  FIGS. 3 and 4 , a motor vehicle  90  including a counter rotation bracket  160  is illustrated before and after a collision with a barrier  200 . A first, undeformed orientation of the motor vehicle  90  is illustrated in  FIG. 3 , while a second, deformed orientation of the motor vehicle  90  is illustrated in  FIG. 4 . The counter rotation bracket  160  of the motor vehicle  90  depicted in  FIGS. 3 and 4  is located towards a rear of the motor vehicle  90 , and the collision with the barrier  200  represents a rear collision with the motor vehicle  90 . Sensitive subsystems of the motor vehicle  90 , for example, a vehicle fueling system  170 , which includes a fuel filler inlet  172 , a fuel filler neck  174 , and a fuel tank (not shown), are located forward of the bumper reinforcement member  150 , and forward of the second lower and upper darts  122 ,  124 , such that the components of the vehicle fueling system  170  are located forward of the preferential buckling zone  106 . While discussion of  FIGS. 3 and 4  is made in reference to the second side member  120 , the second lower and upper darts  122 ,  124 , and the second bumper bracket  140 , it should be understood that during a collision, similar phenomena occur with regard to the first side member  110 , the first lower and upper darts  112 ,  114 , and the first bumper bracket  130 . 
     Referring to  FIG. 4 , as the motor vehicle  90  impacts the barrier  200 , the bumper portion  204  of the barrier first contacts the bumper reinforcement member  150 . This impact initially causes the bumper reinforcement member  150  to translate towards the end portion  126  of the second side member  120  by deforming the second bumper bracket  140 . The impact causes the second bumper bracket  140  to buckle, which causes the bumper reinforcement member  150  and the counter rotation bracket  160  to pivot about the second bumper bracket  140  such that the counter rotation bracket  160  pitches towards the fascia portion  202  of the barrier  200 . As the bumper reinforcement member  150  contacts the bumper portion  204  of the barrier  200  and the counter rotation bracket  160  contacts the fascia portion  202  of the barrier  200 , the continued application of force due to the impact of the barrier  200  with the motor vehicle  90  causes a counter-moment to be applied through the counter rotation bracket  160  into the second side member  120 . The counter-moment is applied to the second side member  120  in a direction that tends to “close” the second upper dart  124 . Additionally, because the second gusset  142  is attached to the second side member  120  and is located between the second upper dart  124  and the end portion  126 , the second gusset  142  tends to direct the counter-moment into a region of the second side member  120  immediately surrounding the second upper dart  124 . 
     With the bumper reinforcement member  150  contacting the bumper portion  204  of the barrier  200 , the counter rotation bracket  160  contacting the fascia portion  202  of the barrier  200 , and the second side member  120  at least partially deformed about the second upper dart  124 , the continued application of force due to the impact of the barrier  200  with the motor vehicle  90  causes a moment to be applied to the second side member  120  in a direction that tends to “close” the second lower dart  122 . 
     The second bumper bracket  140  has a bumper bracket buckling strength, and the second side member  120  has a side member buckling strength which is evaluated at the second upper dart  124 . In the embodiment of the motor vehicle  90  depicted in  FIGS. 3 and 4 , the second bumper bracket  140  and the second side member  120  are designed such that the bumper bracket buckling strength is less than the side member buckling strength. Because the bumper bracket buckling strength is less than the side member buckling strength, the second bumper bracket  140  will reach a critical buckling load at a lower force than the second side member  120  will reach a critical buckling load. Because the second bumper bracket  140  reaches its critical buckling load first, the second bumper bracket  140  will buckle and deform before the second side member  120 , which allows the bumper reinforcement member  150  and the counter rotation bracket  160  to pitch forward to contact the barrier  200 . Therefore, by buckling the second bumper bracket  140  before the second side member  120 , the counter rotation bracket  160  will be positioned to apply a counter-moment to the second side member  120 . 
     Parameters of the barrier  200  and an impact between the motor vehicle  90  and the barrier  200  are found in Federal Motor Vehicle Safety Standard (FMVSS) No. 301. FMVSS No. 301 requires a motor vehicle  90  to maintain integrity of the vehicle fueling system  170  after the motor vehicle  90  sustains an impact with a barrier  200  moving in excess of 80 kilometers per hour. 
     Without being bound by theory, as the bracket height  166  of the counter rotation bracket  160  increases, the greater the counter-moment that can be applied through the first and second bumper brackets to the first and second side members  110 ,  120 . Therefore, the bracket height  166  of the counter rotation bracket  160  may be made as large as possible to increase the counter moment, while maintaining the ability to package the counter rotation bracket  160  within the confines of the bodywork of the motor vehicle  90 . Similarly, as the bracket width  167  of the counter rotation bracket  160  increases, the counter rotation bracket  160  provides an increased zone of protection to motor vehicle  90  and its subsystems. Bracket width  167  may be limited by the ability to package the counter rotation bracket  160  within the confines of the bodywork of the motor vehicle  90 . 
     It should now be understood that the buckling of the first and second side members  110 ,  120  and the first and second bumper brackets  130 ,  140  dissipates energy associated with the barrier  200  impacting the motor vehicle  90 . The preferential buckling zone  106  formed by the lower darts  112 ,  122  and the upper darts  114 ,  124  allows the first and second side members  110 ,  120  to buckle at a location rearward of the vehicle fueling system  170 . The buckling of the first and second side members  110 ,  120  prevents energy due to the collision of the barrier  200  with the motor vehicle  90  from traveling forward beyond the preferential buckling zone  106 . By dissipating the energy caused by the collision rearward of the vehicle fueling system  170 , damage to the vehicle fueling system  170  can be minimized. 
     It is noted that the terms “substantially” and “about” may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. 
     While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.