Abstract:
A front end structure for a vehicle comprising a bumper, a crush can attaching the bumper to a frame rail, a sub-frame supporting an engine, and an impact spreading rail attached to a front transverse rail of the sub-frame. The impact spreading rail extends perpendicularly outboard relative to the frame rail and upward to a location vertically aligned with the bumper. The impact spreading rail is impacted after the bumper in a collision to spread collision deformation outside the frame rail.

Description:
TECHNICAL FIELD 
     This disclosure relates to a spreading rail attached to a vehicle underbody structure that is subjected to testing in a collision with a progressive deformable barrier and evaluated, in part, based upon the homogeneity of the deformation of the barrier. 
     BACKGROUND 
     Vehicles are subject to a wide variety of tests that are mandated by government regulations and insurance certifications. Tests for energy absorption, durability and passenger protection are conducted on new vehicles. Intrusions into the passenger compartment are analyzed in several tests related to occupant protection in a collision. 
     Due to the numerous types of collisions, new tests are constantly being proposed to improve occupant safety, pedestrian safety and the safety of other vehicle occupants. A new vehicle test for testing a vehicle is a test entitled “2020 Euro NCAP test” that tests for intrusions and also tests for compatibility of a vehicle design with other vehicles that may be involved in a collision. One measure of compatibility in the NCAP test relates to the homogeneity of the deformation of a moving barrier that collides with a moving vehicle. Deeper deformation areas on the movable barrier are undesirable and result in unsatisfactory test results. 
     When modifying elements a vehicle design to meet the requirements of one test, care must be taken to avoid adversely affecting other test results. For example, changes made to improve homogeneity test results cannot be made in such a way as to compromise passenger protection as measured in other tests. 
     The above problems and other problems are addressed by this disclosure as summarized below. 
     SUMMARY 
     According to one aspect of this disclosure, a front end structure is disclosed for a vehicle comprising a bumper, a crush can attaching the bumper to a frame rail, a sub-frame supporting an engine, and a spreading rail attached to a front transverse rail of the sub-frame. The spreading rail extends perpendicularly outboard relative to the frame rail and upward to a location vertically aligned with the bumper. 
     According to another aspect of this disclosure, a front end structure is disclosed for a vehicle that includes a pair of frame rails and a pair of crush cans assembled to the frame rails. A bumper is assembled to the crush cans. A sub-frame is assembled below the frame rails and has a front rail extending in a transverse direction. A pair of rails is assembled to the front rail and extends to a location at a height of the bumper and laterally outboard of the front rail. 
     According to a further aspect of this disclosure, a front end structure is disclosed for a vehicle that includes a bumper and crush cans disposed between the vehicle and the bumper. A sub-frame is configured to support an engine of the vehicle. A recessed body has an attachment portion attached to the sub-frame and an outer portion that extends outboard of a frame rail. The recessed body is impacted after the bumper in a collision to spread collision deformation outside the frame rail. 
     Other aspects of this disclosure that may be incorporated in any of the above described front end structures may further comprise providing the spreading rail (or the recessed body) as a tubular rail. The tubular rail may include a plurality of internal ribs. The spreading rail (or the recessed body) may be attached to the sub-frame at a location vertically below the crush can. The spreading rail (or the recessed body) may include an attachment portion and an outer portion that is joined to the attachment portion at a bend. The spreading rail (or the recessed body) may be disposed below the crush can and longitudinally recessed relative to the bumper. 
     The above aspects of this disclosure and other aspects will be described below with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic top plan view of a vehicle and a movable deformable barrier just prior to an impact in a 2020 Euro NCAP Mobile Progressive Deformable Barrier Front Offset Impact Test. 
         FIG. 2  is a diagrammatic side elevation view of the vehicle and the movable deformable barrier shown in  FIG. 1  in the 2020 Euro NCAP Mobile Progressive Deformable Barrier Front Offset Impact Test. 
         FIG. 3  is a fragmentary perspective view of a front end structure of a vehicle including an impact spreading rail attached to a sub-frame. 
         FIG. 4  is a fragmentary front elevation view of a front end structure of a vehicle including an impact spreading rail attached to a sub-frame. 
         FIG. 5  is a fragmentary top plan view taken along the line  5 - 5  in  FIG. 4 . 
         FIG. 6  is a fragmentary front elevation view of an alternative embodiment of a front end structure of a vehicle including an impact spreading rail that is an extension of a front rail of a sub-frame. 
         FIG. 7  is a chart showing the results of a 2020 Euro NCAP simulated test of a vehicle having a front end structure that does not include the impact spreading rail shown in  FIGS. 3-5  in terms of homogeneity of the deformation of the movable barrier. 
         FIG. 8  is a chart showing the results of a 2020 Euro NCAP simulated test of a vehicle having a front end structure as shown in  FIGS. 3-6  in terms of homogeneity of the deformation of the movable barrier. 
         FIG. 9  is a graph showing the Pulse Average (G) over time (ms) comparing the front end tested in  FIG. 7  to the front end structure tested in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts. 
     Relative terms for spacial relationships as referred to in this disclosure should be understood as being vehicle directions with the vehicle having a “longitudinal direction” that extends from the front of the vehicle to the rear of the vehicle. The “lateral direction” extends in the cross-vehicle direction. A “centerline” of the vehicle extends in the longitudinal direction and is at the lateral center of the vehicle. For example, the term “outboard of the frame rails” refers to a side of the frame rails that is on the opposite side of the frame rails from the centerline. The “outward direction” is the direction extending away from the centerline. 
     Referring to  FIG. 1 , a vehicle  10  is shown with a movable barrier vehicle  12  just prior to a collision in a 2020 Euro NCAP Test. The movable barrier vehicle  12  supports and maneuvers a deformable barrier  14  comprising a tube-shaped assembly of hexagonal crush tubes  16 . 
     Referring to  FIG. 2 , the vehicle  10  is shown with the movable barrier vehicle  12  and the deformable barrier  14  disposed just in front of a bumper assembly  18  of the vehicle  10 . The bumper assembly  18  is shown below the hood  20  of the vehicle  10  and in front of the front wheel  24  of the vehicle  10 . In the test, the vehicle  10  having a mass of 1800 Kg is moved at 50 Km/hr while the movable barrier vehicle  12  having a mass of 1400 Kg is moved at 50 Km/hr in an offset head-on collision. Following the collision, the deformable barrier  14  is scanned with a 3-D scanner that is used to measure the deformation of the deformable carrier  14  as a result of the off-set collision. The extent to which the deformable barrier  14  has consistent deformation across the face of the deformable barrier  14  it is considered to be homogenous while a non-uniform deformation of the deformable barrier  14  is considered to be non-homogenous. Based upon the 3-D scanning data, the value for homogeneity/geometry is assigned as the test result. 
       FIG. 3  illustrates a front end structure  30  for a vehicle  32  in perspective. A bumper  34  is secured to the vehicle  32  by a crush can  36 . It should be understood that the front end structure  30  as illustrated is one-half of the front end structure  30  and that a mirror image of the front end structure is provided on the opposite side of the vehicle. 
     A sub-frame  38  of the vehicle  32  supports the engine  40  (diagrammatically shown in  FIG. 4 ) of the vehicle  32 . A spreading rail  42 , also referred to herein as a recessed body, is a tubular member that includes internal ribs  44 . The spreading rail  42  is secured to a front rail  46  of the sub-frame  38 . Alternatively, the spreading rail  42  can be attached to the bracket  47  that extends downward from the crash can  36  to the location where the bracket  47  is adjacent the front rail  46 . While the illustrated embodiment includes a tubular spreading rail  42 , it should be understood that the spreading rail could also be fabricated from two “C-shaped” channels that are welded together, or may be provided in other shapes or formed of a variety of different materials. 
     A frame rail  48  is partially shown that supports the body of the vehicle  32 . The frame rail  48  may be a separately formed frame rail or may be an integral frame rail for a uni-body constructed vehicle that has a frame formed as part of the body of the vehicle. 
     The spreading rail  42  includes an attachment portion  50  and an outer portion  52 . A bend  54  may be formed in the spreading rail  42  between the attachment portion  50  and the outer portion  52 . A fastener  56 , or bolt, is used to secure the spreading rail  42  to the front rail  46  of the sub-frame  38 . 
     Referring to  FIG. 4 , the front end structure  30  is shown in a front elevation view. The bumper  34  is disposed in front of and above the front rail  46 . The bumper  34  is also disposed in front of and above the attachment portion  50  and bend  54  of the impact spreading rail  42 . The outer portion  52  of the impact spreading rail  42  extends outboard of the frame rail (shown in  FIG. 3 ). The engine  40  is schematically shown to be supported on the sub-frame  38 . 
       FIG. 5  provides a fragmentary top plan view taken along the line  5 - 5  in  FIG. 4 . The fastener  56  is inserted through the attachment portion  50  of the spreading rail  42  and into the front rail  46  of the sub-frame  38 . The spreading rail  42  is attached to the front rail  46  of the sub-frame  38  by a fastener  56 . The bumper  34  is attached to the crush can  36 . The outer portion  52  of the impact spreading rail  42  extends outboard of the frame rail  48  in a transverse plane perpendicular to the frame rail  48 . 
     In a collision of a movable barrier vehicle (shown in  FIGS. 1 and 2 ) with the bumper  34 , impact is first made with the bumper  34  that causes the crush can  36  to collapse absorbing energy from the collision. After the bumper  34  collapses the crush can  36 , the spreading rail  42  is engaged by the movable barrier vehicle and begins to absorb energy from the collision. The spreading rail  42  spreads the deformation caused by the collision across the portion of the vehicle outboard of the bumper. By spreading the deformation, the homogeneity of the impact on the movable barrier vehicle  12  (shown in  FIGS. 1 and 2 ) is improved as will be explained with reference to  FIGS. 7-8  below. 
     Referring to  FIG. 6 , an alternative embodiment is illustrated wherein a front rail  60  of a sub-frame  62  supporting the engine  64  includes an integral spreading rail  66 . The integral spreading rail  66  is an extension of the front rail  60  that extends outwardly and upward from the sub-frame  62  to a location outboard of the frame rail  48  (shown in  FIG. 3 ) and laterally outboard of the bumper  68 . 
     Referring to  FIG. 7 , a chart rating the homogeneity/geometry of the barrier after a 2020 Euro NCAP simulated test collision is presented that reflects that the front end structure without an impact spreading rail was rated at  95 . The homogeneity/geometry rating is weighted at 75% and was determined to be “Average.” In the simulated test, a value is also assigned for the energy input to the movable barrier was rated at 3.4 and was given a 25% weight. The energy input is a product of the barrier energy rating of 79% and the delta velocity of the barrier of 56.2 Km/hr. The barrier energy value and delta velocity barrier values were each weighted 50% and resulted in an “Average” acceptability rating for the barrier energy and an “Average” acceptability rating for the delta velocity barrier value. The overall rating for the simulated bumper beam was evaluated as being “Average.” 
     Referring to  FIG. 8 , a chart rating the homogeneity/geometry test for a front end underbody structure made according to the embodiment of  FIGS. 3-6  resulted in a homogeneity/geometry result of 66. The barrier energy and delta velocity barrier values were held the same as in the test reported in  FIG. 7 , but the homogeneity/geometry result of 95 improved to a 66 that is rated as a “Good” acceptability rating. When the homogeneity/geometry rating was combined with the energy input value and weighted as described above, the overall rating of the bumper with the reduced height and cut-away wall in the central portion improved to a “Good” acceptability rating and represents a substantial improvement over the test result reported in  FIG. 7 . 
     Referring to  FIG. 9 , a graph comparing the NCAP Vehicle Pulse Index (VPI) of the front end structure without an impact spreading rail is compared to a front end structure made according to the embodiment of  FIGS. 3-6 . The embodiment of  FIGS. 3-6  resulted in an enhanced VPI showing a reduction of 1.2 G in the VPI. 
     The embodiments described above are specific examples that do not describe all possible forms of the disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and also includes modifications of the illustrated embodiments.