Abstract:
A vehicle includes a bumper, a floor and a subframe. The subframe is attached to the floor at a plurality of attachment points and below the bumper. The subframe has a base member extending across the subframe, parallel to the bumper and including a bracket. The bracket has first and second tabs connected by a platform extending from the first and second tabs. The bracket is fixedly attached at the second tab and angled relative to the base member such that the second tab is defined closer to the bumper. Upon loading, the first tab moves in a direction substantially parallel to the base member and the platform is deformed substantially perpendicular to the base member.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to an energy absorbing bracket on a vehicle subframe. 
       BACKGROUND 
       [0002]    Vehicle subframes may connect vehicle frames to vehicle floors. Typically, subframes define a rigid structure to provide added support between the frame and the floor. The subframe may support certain vehicle components such as the engine, drivetrain, or suspension. The subframe allows for the distribution of weight of the vehicle components across the vehicle. This allows for a reduction of the overall weight of the vehicle and, as such, improves fuel efficiency. 
       SUMMARY 
       [0003]    A vehicle underbody structure includes a floor and a subframe. The subframe is connected to the floor and has a base extending a width of the subframe. The base includes a bracket attached offset from a center and substantially adjacent a side of the base. The bracket has a first and a second tab. The second tab is secured to the base, and the first tab is configured such that, upon impact, a platform connecting and extended from the first and second tabs is loaded substantially perpendicular to the base and the first tab is extended substantially parallel to the base. 
         [0004]    A vehicle includes a bumper, a floor and a subframe. The subframe is attached to the floor at a plurality of attachment points and below the bumper. The subframe has a base member extending across the subframe, parallel to the bumper and including a bracket. The bracket has first and second tabs connected by a platform extending from the first and second tabs. The bracket is fixedly attached at the second tab and angled relative to the base member such that the second tab is defined closer to the bumper. Upon loading, the first tab moves in a direction substantially parallel to the base member and the platform is deformed substantially perpendicular to the base member. 
         [0005]    A subframe for a vehicle includes a base member having a bracket attached at a first tab of the bracket. The bracket is disposed offset a center of the base member and further includes a second tab and a platform. The platform connects the first and second tabs and is oriented such that upon loading, the platform is loaded perpendicular to the base member and the first tab is loaded parallel to the base member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is plan view of an underbody structure of a vehicle; 
           [0007]      FIG. 2  is a perspective view of the subframe and bracket attached the base of the subframe; 
           [0008]      FIG. 3  is a top view of the bracket before an impact; and 
           [0009]      FIG. 4  is a top view of the bracket after an impact. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
         [0011]    Referring to  FIG. 1 , a plan view of a vehicle  10  having an underbody structure  12  is shown. The underbody structure  12  includes a frame  14 , a subframe  16 , and a floor  18 . The subframe  16  uses a rear end joint  20  to attach to the floor  18 . The floor  18  attaches to the subframe  16  using a fastener  24 . In at least one embodiment, the fastener  24  may be a bolt, screw, or shaft that allows for rigid attachment between the floor  18  and the subframe  16 . 
         [0012]    In the event of an impact with the vehicle  10 , and specifically the underbody structure  12 , various factors may further aid to improve performance of the underbody structure  12  and specifically the subframe  16 . For example, as depicted in  FIG. 1 , a barrier  26  may be impacted by the vehicle  10 . The barrier  26  may include, by way of example another vehicle, the rigid object, or any other object that may be impacted by the vehicle  10  and contacted by the underbody structure  12  in subframe  16 . Important factors that may improve performance of the vehicle  10  and underbody structure  12  including the subframe  16  include, but are not limited to, energy absorption of the barrier  26 , change in velocity of the barrier  26 , the bottoming-up of the barrier  26 , and homogeneity of the barrier  26  post impact. 
         [0013]    The homogeneity of the barrier  26  post impact refers to deformation of the barrier  26  after impact with the vehicle  10  and specifically the underbody structure  12  including the subframe  16 . Improving the homogeneity of the barrier  26  requires energy absorption from the subframe  16 . Specifically, improving homogeneity of the barrier  26  requires elimination of a hard load imposed on the barrier by absorbing energy to create a soft load through a sliding bracket  28  attached to the subframe  16 . As will be described in more detail below, the sliding bracket  28  is attached to the subframe  16  and configured to absorb energy upon impact with the barrier  26 . Absorbing impact energy in the event of an impact with the barrier  26  allows the subframe  16  to absorb more of the energy load from the impact without providing further damage to either the subframe  16  or the barrier  26 . Since the sliding bracket  28  is configured to absorb energy from the impact with the barrier  26 , the total deformation of the barrier  26  will be more homogenized. 
         [0014]    Further, the sliding bracket  28  also further aids to reduce the vehicle pulse index during an impact with the barrier  26 . The vehicle pulse index may be defined by a crash pulse that acts on the vehicle  10  to affect an occupant&#39;s (not shown) movement within the vehicle  10 . For example, the more energy absorbed by the underbody structure  12 , and more specifically the subframe  16 , the less force will be transferred to the vehicle  10  and the less an occupant will move within the vehicle  10 . Therefore, attaching the sliding bracket  28  to the subframe  16  increases the crush space available on the underbody structure  12 . Increasing the crush space by using the sliding bracket  28  allows for more energy absorption by the underbody structure  12  and subframe  16  and further aids to reduce the force exerted on the vehicle  10  and likewise the movement of occupant within the vehicle  10 . The sliding bracket  28  reduces the crash pulse and, as such, the vehicle pulse index by increasing the crush space of the underbody structure  12 . 
         [0015]    Referring to  FIG. 2 , a perspective view of the subframe  16  with the sliding bracket  28  is depicted. The subframe  16  includes a base  30  that extends between a first side  32  and a second side  34  defining an entire width  36  of the subframe  16 . Further, the subframe  16  defines a center  38  that is equal to a center  38  of the base  30 . As can be seen in  FIG. 2 , the sliding bracket  28  is disposed on the base  30  offset from the center  38 . The sliding bracket  28  is depicted in  FIG. 2  as being disposed on the base  30  offset from the center  38  adjacent the first side  32 . However, the sliding bracket  28  may also be disposed on the base  30  offset from the center  38  adjacent the second side  34 . Likewise, the subframe  16  may also include a sliding bracket  28  disposed on the base  30  offset from the center  38  and adjacent the first and second sides  32 ,  34 . The position of the sliding bracket  28  on the base  30  may also be optimized according to deformation homogeneity of the barrier  26  and the vehicle pulse index, as discussed above. 
         [0016]    As can be seen in the depiction of  FIG. 2 , the sliding bracket  28  may be attached nonlinearly relative to the base  30 . The base  30  includes a first edge  40  and a second edge  42  as well as a central horizontal axis  44 . The first edge  40  and the second edge  42  extend in a horizontal direction parallel to the central horizontal axis  44  of the base  30 . Therefore, the first and second edges  40 ,  42  extend from the first side  32  to the second side  34  of the subframe  16 . The sliding bracket  28  attaches to the base  30  between the first edge  40  and the second edge  42 . Further, the bracket  28  may be disposed on the base  30  at an angle α relative to the horizontal axis  44  of the base  30 . In at least one other embodiment, the sliding bracket  28  may be disposed on the base  30  between the first and second edges  40 ,  42  such that the sliding bracket  28  is in line with the horizontal axis  44 . 
         [0017]    The angle α may be determined according to the necessary energy absorption to improve homogeneity and the vehicle pulse index. For example, the angle of the sliding bracket  28  shown in  FIG. 2  represents a positive angle α. In at least one other embodiment, the angle of the sliding bracket  28  may define a negative angle α relative to the horizontal axis  44 . As stated above, the subframe  16  may include more than one sliding bracket  28  defined adjacent to both the first and second sides  32 ,  34 . Each of sliding bracket on the first side  32  and the second side  34  may also define the same angle α relative to the horizontal axis  44 . Likewise, each sliding bracket  28  on the first side  32  and the second side  34  may also define different angles α relative to the horizontal axis  44 . Using differing angles between sliding brackets  28  defined adjacent to the first side  32  and the second side  34  allows the vehicle  10  to account for differing impact scenarios associated with each of the first and second sides  32 ,  34  of the subframe  16 . 
         [0018]    The sliding bracket  28  includes a first tab  46 , a second tab  48 , and a platform  50 . The platform  50  extends above and connects the first and second tabs  46 ,  48 . The second tab  48  is fixedly attached to the base  30 . The first tab  46  is freely disposed on the base  30 . The platform  50  is spaced from and parallel to the base  30 . The angle α of the sliding bracket  28  may be defined as the angle between the first tab  46  and the horizontal axis  44  of the base  30 . Therefore, in order to define a positive angle α, the first tab  46  extends in a direction above the horizontal axis  44  toward the first edge  40 . If a positive angle α is defined between the sliding bracket  28  and the horizontal axis  44  of the base  30 , then the second tab  48  is fixedly attached to the base  30  below the horizontal axis  44 . Likewise, in order to define a negative angle α, the first tab  46  extends in a direction below the horizontal axis  44  toward the second edge  42 . If a negative angle α is defined between the sliding bracket  28  and the horizontal axis  44  of the base  30 , then the second tab  48  is fixedly attached to the base  30  above the horizontal axis  44 . As stated above, the angle α may be optimized according to the crush requirements to absorb energy from an impact with the barrier  26 . 
         [0019]    The sliding bracket  28  may be mechanically fixed to the base  30 . For example, the second tab  48  may be welded to the base  30 . In at least one other embodiment, the second tab  48  may be fastened to the base using a fastener, rivet, or any other mechanical fastening device that will fixedly attach the second tab  48  to the base  30 . As will be discussed in more detail below, fixedly attaching the second tab  48  to the base  30  allows the sliding bracket  28  to create more crush space on the underbody structure  12  and more specifically the subframe  16 . In at least one other embodiment, the first tab  46  may be fixedly attached to the base  30  and the second tab  48  may be freely disposed on the base  30 . If the first tab  46  is fixedly attached to the base  30 , it may also be mechanically fastened to the base  30  such as through welding, riveting, or using a fastener. 
         [0020]    Referring to  FIGS. 3 and 4 , a top view of the sliding bracket  28  on the base  30  is depicted.  FIG. 3  depicts the sliding bracket  28  before an impact and  FIG. 4  depicts the sliding bracket  28  after an impact. The sliding bracket  28  is depicted in  FIGS. 3 and 4  as being substantially parallel to or in line with the horizontal axis  44  of the base  30 . As stated above, the sliding bracket  28  may also be disposed at an angle α relative to the horizontal axis  44  of the base  30  in other embodiments. 
         [0021]      FIG. 3  depicts the sliding bracket  28  before deformation. As can be seen in  FIG. 3 , the platform  50  is spaced apart and parallel to the base  30  and connects the first tab  46  to the second tab  48 . The platform  50  is spaced apart from the base  30  at a distance  52 . The distance  52  between the platform  50  and the base  30  may vary depending on vehicle size, type, or any other parameter that requires an increased crush space for the subframe  16 . Therefore, the distance  52  between the platform  50  and the base  30  may be optimized based upon the loading characteristics of an impact. The distance  52  allows the sliding bracket  28  to absorb energy in the event of an impact instead of transferring the energy through the subframe  16 . As stated above, the distance  52  further allows the sliding bracket to increase the homogeneity and vehicle pulse index in the event of an impact. Further, the platform  50  also defines a length  54 . The length  54  of the platform  50  may also aid the sliding bracket  28  to absorb energy in the event of an impact. 
         [0022]    For example, to increase the area  56  between the platform  50  and the base  30 , the length  54  of the platform  50  may be extended in a direction substantially parallel to the base  30 . Likewise, in certain embodiments, the area  56  between the platform  50  and the base  30  may be decreased by reducing the length  54  of the platform  50  in a direction substantially parallel to the base  30 . The area  56  further defines the available crush space for the sliding bracket  28  to absorb energy from an impact. The area  56  may be optimized based upon the required energy absorption of the sliding bracket  28  to prevent energy transfer through the subframe  16 . The area  56  of the sliding bracket  28  further allows for a less rigid impact with the subframe  16 . This further aids to increase homogeneity after impact, the vehicle pulse index during impact, as well as intrusion of the subframe  16 . 
         [0023]      FIG. 4  depicts the sliding bracket  28  after impact. After deformation of the sliding bracket  28 , the platform  50  is loaded with a force being perpendicular to the base  30  and the first tab  46  is loaded with a force substantially parallel to the base  30 . Loading of the platform  50  and the first tab  46  is aided by the fixed attachment of the second tab  48 . The second tab  48  does not move when the base  30  of the subframe  16  is loaded due to the fixed attachment of the second tab  48  on the base  30 . Therefore, energy from an impact may be transferred to the sliding bracket  28  through deformation of the platform  50  and first tab  46 . Transferring energy through deformation of the platform  50  and the first tab  46  reduces the deformation on the subframe  16 . 
         [0024]    As stated above, the first tab  46  may be fixedly attached to the base  30  and the second tab  48  may be disposed freely on the base  30 . In this scenario, in the event of an impact, the platform  50  deforms in a manner substantially perpendicular to the base  30  and the second tab  48  deforms in a manner substantially parallel to a horizontal axis  44  of the base  30 . Again, energy is absorbed by the sliding bracket  28  through the deformation of the platform  50  and the second tab  48 . The area  56  between the platform  50  and the base  30  is therefore reduced. 
         [0025]    As can be seen in both  FIGS. 3 and 4 , the first and second tabs  46 ,  48  define a substantially circular cross-section. In at least one other embodiment, the first and second tabs  46 ,  48  may define a substantially rectangular cross-section, elliptical cross-section, trapezoidal cross-section, or any other cross-sectional area which allows the sliding bracket  28  to absorb energy. The dimensions of the first and second tabs  46 ,  48  may further aid to define energy absorption through the sliding bracket  28 . The first and second tabs  46 ,  48  may define a first length  58  and second length  60 , respectively. The first and second tabs  46 ,  48  may define a first width  62  and a second width  64 , respectively. For example, the first length  58  of the first tab  46  may be greater than the second length  60  of the second tab  48 , or vice versa. Likewise, the first width  62  of the first tab  46  may be greater than the second width  64  of the second tab  48 , or vice versa. In at least one other embodiment, the first length  58  of the first tab  46  may be equal to the second length  60  of the second tab  48  and the first width  62  the first tab  46  may be equal to the second width  64  of the second tab  48 . 
         [0026]    The dimensions and geometry of the first and second tabs  46 ,  48  define the rigidity of the sliding bracket  28 . Therefore, the cross-sectional area, length and width of the first and second tabs  46 ,  48  of the sliding bracket  28  may be optimized based upon the rigidity added to the base  30  and the impact characteristics. For example, to absorb more energy from an impact, the sliding bracket  28  may define first and second tabs  46 ,  48  to provide more rigidity to the base  30  such that more energy is required to deform the sliding bracket  28 . Likewise, to absorb less energy from an impact, the sliding bracket  28  may define first and second tabs  46 ,  48  to provide less rigidity to the base  30  such that less energy is required to deform the sliding bracket  28 . This allows the sliding bracket  28  to be optimized depending on the impact characteristics as well as the amount of energy absorbed by the sliding bracket  28 . 
         [0027]    Sliding bracket  28  may be composed of aluminum. In at least one other embodiment, the sliding bracket  28  may be composed of high-strength steel, carbon fiber, or any other material that allows the sliding bracket  28  to absorb energy in the event of an impact. As shown in  FIGS. 3 and 4 , the sliding bracket  28  is depicted as hollow. However, in at least one other embodiment, the sliding bracket  28  may define a single, extruded part. 
         [0028]    While exemplary to embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.