Patent Publication Number: US-2020276950-A1

Title: Bumper assembly

Description:
BACKGROUND 
     Bumpers of vehicles are designed to absorb energy and/or transfer energy during vehicle impacts. Such vehicle impacts may include frontal and rear impacts. Impacts may occur with objects of varying size and mass, and various testing simulates such impacts. For example, one test is for low-speed damageability, which is simulated by impact tests that measure the amount of damage to the exterior of the bumper resulting from low-speed impacts. In these tests, little or no exterior damage to the bumper is desired to reduce the likelihood of costly repairs resulting from low-speed impacts. As another example, the vehicle may impact narrower, lighter objects, such as pedestrians. These impacts may be simulated by pedestrian protection (PedPro) impact tests. 
     These different classes of impacts present competing design factors for the bumper. During low-speed damageability tests, it may be beneficial for the bumper to be rigid, with no deformation, to reduce the likelihood of damage to the exterior of the bumper. In contrast, during an impact with a narrower object that may be a pedestrian, it may be more beneficial to reduce the stiffness of the bumper during deformation, which may reduce injuries to the pedestrian. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle. 
         FIG. 2  is a perspective view of a bumper assembly of the vehicle. 
         FIG. 3A  is a top view of the bumper assembly with a first example cylinder. 
         FIG. 3B  is a top view of the bumper assembly with a second example cylinder. 
         FIG. 3C  is a top view of the bumper assembly with a third example cylinder. 
         FIG. 4  is a front view of the bumper assembly. 
         FIG. 5  is a top view of the bumper assembly after a first example impact. 
         FIG. 6  is a top view of the bumper assembly after a second example impact. 
     
    
    
     DETAILED DESCRIPTION 
     An apparatus includes a bumper beam including an outer face, a plate elongated along the outer face, a plurality of ribs elongated from the plate transverse to a direction of elongation of the plate, and a plurality of cylinders each fixed to one of the ribs and spaced from the plate. 
     Each of the ribs may have a planar shape and extends parallel to an axis defined by the respective cylinder. 
     Each of the cylinders may be cantilevered from the plate on the respective rib. 
     The ribs may be first ribs, and the cylinders may be first cylinders. The apparatus may further include a plurality of second ribs each elongated from one of a subset of the first cylinders, and a plurality of second cylinders each fixed to one of the second ribs and spaced from the first cylinders and the from the plate. Each of the second ribs may extend toward the plate. 
     Each of the second cylinders may be cantilevered from the respective first cylinder on the respective second rib. 
     Each of the subset of first cylinders may have two respective second ribs. 
     The subset of first cylinders may be a first subset, the first subset may be a strict subset, a second subset may include the first cylinders not in the first subset, and the first cylinders in the second subset may be disconnected except for the first ribs. The first cylinders in the first subset may be alternated with the first cylinders in the second subset along the direction of elongation of the plate. 
     The plate may be elongated from a first end to a second end, and a sum of the diameters of the first cylinders and second cylinders may be greater than a length of the plate from the first rib closest to the first end of the plate to the first rib closest to the second end of the plate. A sum of the diameters of the first cylinders may be less than the length of the plate from the first rib closest to the first end of the plate to the first rib closest to the second end of the plate. 
     A sum of the diameters of the second cylinders may be less than the length of the plate from the first rib closest to the first end of the plate to the first rib closest to the second end of the plate. 
     The cylinders may be oriented vertically. 
     The cylinders may be tubular. The cylinders may be hollow. 
     Each cylinder may define an axis, and each cylinder may include an outer wall and three extensions each extending from the axis to the outer wall. 
     Each cylinder may include an outer wall and three extensions constituting a triangular prism shape extending in an axial direction defined by the cylinder and circumscribed by the outer wall. 
     Each stiffness of one of the cylinders may be greater than a stiffness of the respective rib in a vehicle-rearward direction. 
     The cylinders may be parallel to each other. 
     The apparatus may further include a fascia coupled to the bumper beam and extending around the cylinders. 
     An apparatus  32  for a vehicle  30  includes a bumper beam  34  including an outer face  36 , a plate  38  elongated along the outer face  36 , a plurality of first ribs  40  elongated from the plate  38  transverse to a first direction A of elongation of the plate  38 , and a plurality of first cylinders  42  each fixed to one of the first ribs  40  and spaced from the plate  38 . 
     The apparatus  32  can provide good performance for both low-speed-damageability tests and pedestrian-protection tests. The apparatus  32  can provide different regimes of resistance for the different types of tests while being a passive device, i.e., lacking actuated or moving parts, which simplifies the design. The apparatus  32  is cost-efficient and weight-efficient. The apparatus  32  can be retrofitted on existing vehicles as well as being installed on new vehicles. 
     With reference to  FIG. 1 , the vehicle  30  may be any passenger or commercial automobile such as a car, a truck, a sport utility vehicle, a crossover, a van, a minivan, a taxi, a bus, etc. 
     The vehicle  30  includes a frame  44 . The vehicle  30  may be of a unibody construction, in which the frame  44  and a body of the vehicle  30  are a single component, as shown in  FIG. 1 . The vehicle  30  may, alternatively, be of a body-on-frame construction, in which the frame  44  supports a body that is a separate component from the frame  44 . The frame  44  and body may be formed of any suitable material, for example, steel, aluminum, etc. 
     The vehicle  30  includes a bumper assembly  46 . The bumper assembly  46  extends across a front or rear of the vehicle  30 . The bumper assembly  46  is positioned to absorb energy during a frontal or rear impact to the vehicle  30 . 
     The bumper assembly  46  includes a fascia  48 . The fascia  48  may extend parallel to the bumper beam  34 , in the direction A of elongation of the bumper beam  34 . The fascia  48  is coupled to the bumper beam  34 , either directly or indirectly. The fascia  48  may extend around the bumper beam  34 , the first cylinders  42 , and the plate  38 , thereby concealing the rest of the bumper assembly  46 . The fascia  48  may present a class-A surface, i.e., a surface specifically manufactured to have a high-quality, finished aesthetic appearance free of blemishes. The fascia  48  may be supported by the frame  44  and/or body components of the vehicle  30 . 
     With reference to  FIG. 2 , the frame  44  may include crush cans  50  supporting the bumper assembly  46  on the frame  44 . The crush cans  50  may extend in a vehicle-forward direction from the rest of the frame  44  to the bumper beam  34  of the bumper assembly  46 . The crush cans  50  may be fastened, welded, etc. to the rest of the frame  44 . The crush cans  50  may serve as energy absorbers, sometimes known as “crumple zones.” The crush cans  50  may absorb some of the energy of a collision of the vehicle  30  through deformation, thus lessening the amount of energy transferred to the rest of the frame  44  and the vehicle  30 . 
     The bumper assembly  46  includes the bumper beam  34 , the plate  38 , the first ribs  40 , the first cylinders  42 , second ribs  52 , and second cylinders  54 , all fixed relative to each other. 
     The bumper beam  34  extends longitudinally across a front or rear of the vehicle  30 , parallel to the plate  38 , and defines the first direction A. The first direction A points laterally relative to the vehicle  30 , i.e., right or left. The bumper beam  34  is fixed to the frame  44 , and, specifically, may be fixed to the crush cans  50 . The bumper beam  34  has the outer face  36 , which for a front bumper assembly  46  faces the direction of travel of the vehicle  30  when traveling forward and for a rear bumper assembly  46  faces the direction of travel of the vehicle  30  when traveling in reverse. The bumper beam  34  may reinforce the structural integrity of the vehicle  30 . The bumper beam  34  may be formed of any suitable material, for example, steel, aluminum, etc. 
     The plate  38  extends in the first direction A, parallel to the bumper beam  34 . The plate  38  is elongated along the outer face  36  of the bumper beam  34  from a first end  56  to a second end  58 , and the plate  38  may extend a full length of the bumper beam  34 . The plate  38  is adjacent to the outer face  36  of the bumper beam  34 ; that is, nothing is between the plate  38  and the outer face  36 . The plate  38  is fixed relative to the bumper beam  34 . For example, the plate  38  may be fixed directly to the bumper beam  34 , e.g., fastened or adhered to the bumper beam  34 . For another example, the plate  38  may be coupled to the fascia  48 , directly or indirectly. 
     With reference to  FIGS. 3A-C , the first ribs  40  are elongated from the plate  38  transverse to the first direction A, e.g., in a vehicle-forward second direction B. Each first rib  40  has a planar shape and extends in two directions, the second direction B and a generally vertical third direction C. The first, second, and third directions A, B, C may be mutually orthogonal. In other words, each first rib  40  extends in a direction away from the plate  38  and extends parallel to an axis defined by the respective first cylinder  42 . 
     The first cylinders  42  are fixed relative to the plate  38  by the first ribs  40 . Each first cylinder  42  is fixed to one of the first ribs  40 , and each first rib  40  supports one of the first cylinders  42 . The first ribs  40  extend from the plate  38  to the respective first cylinders  42 . The first cylinders  42  are each cantilevered from the plate  38  on the respective first rib  40 . For the purposes of this disclosure, “A is cantilevered from B” means that A is supported by a single support attached at B but is otherwise freely suspended. 
     The first cylinders  42  are tubular, i.e., the first cylinders  42  each have an outer wall  60  defining their cylindrical shape. Each first cylinder  42  defines an axis, i.e., the axis along which a circular cross-section is elongated to define that first cylinder  42 . The first cylinders  42  are oriented so that their axes extend vertically, in the third direction C. 
     With reference to  FIG. 3A , as a first example, the first cylinders  42  can be hollow, i.e., no structure is both attached to the outer walls  60  of the first cylinders  42  and disposed internally to the first cylinders  42 . 
     With reference to  FIG. 3B , as a second example, the first cylinders  42  may each include three extensions  62  forming a Y-shape. The extensions  62  extend from the respective axis to the respective outer wall  60 . The extensions  62  can be circumferentially equally spaced around the axis, i.e., each extension can form a 120° angle with the other two respective extensions  62 . The extensions  62  can be elongated with a constant cross-section vertically in the third direction C. 
     With reference to  FIG. 3C , as a third example, the first cylinders  42  may each include three extensions  62  constituting a triangular prism shape extending in the third direction C and circumscribed by the outer wall  60 . In a cross-section orthogonal to the axis defined by the first cylinder  42 , the outer wall  60  has a circular shape circumscribing a triangular shape formed by the three extensions  62 . The triangular shape may be equilateral, i.e., the extensions  62  have equal length and form 60° angles with each other. 
     With reference to  FIGS. 3A-C , the second ribs  52  are each elongated from one of a first subset of the first cylinders  42 . For the purposes of this disclosure, “subset” means a group of items consisting of at least one item from another group, up to all items from the other group, and “strict subset” means a group of items consisting of at least one item from another group and less than all items from the other group. The first cylinders  42  in the first subset may each have two second ribs  52  elongated from each first cylinder  42 . 
     A second subset includes the first cylinders  42  not in the first subset, i.e., the first subset is a strict subset. The first subset and the second subset are mutually exclusive and exhaustive, i.e., each first cylinder  42  is a member of either the first subset or the second subset, but not both. The first cylinders  42  in the second subset are disconnected except for the first ribs  40 , i.e., are not supported by or contacting other components except for the first ribs  40 . The first cylinders  42  in the first subset are alternated with the first cylinders  42  in the second subset along the first direction A; i.e., each first cylinder  42  in the first subset is adjacent to one or two first cylinders  42  in the second subset and not to any first cylinder  42  in the first subset, and vice versa. 
     Each second rib  52  has a planar shape and extends in two directions, the third direction C (i.e., vertically, i.e., parallel to an axis defined by the respective first cylinder  42 ) and in a direction toward the plate  38 . The second ribs  52  extend in directions that are partially toward the plate  38  (i.e., opposite the second direction B) and partially in or opposite to the first direction A. 
     The second cylinders  54  are fixed relative to the plate  38  by the first ribs  40 , first cylinders  42 , and second ribs  52 . Each second cylinder  54  is fixed to one of the second ribs  52 , and each second rib  52  supports one of the second cylinders  54 . The second cylinders  54  are spaced from the first cylinders  42  and from the plate  38 . Each second rib  52  extends from the respective first cylinder  42  to the respective second cylinder  54 . The second cylinders  54  are each cantilevered from the respective first cylinder  42  on the respective second rib  52 . 
     Each second cylinder  54  is closer to the plate  38  than the respective first cylinder  42 . The second cylinders  54  are arranged in a row along the first direction A. Along the first direction A, the first cylinders  42  and the second cylinders  54  alternate; i.e., each first cylinder  42  is adjacent to one or two second cylinders  54  in the first direction A and not to any first cylinder  42 , and vice versa. The shapes of the second cylinders  54  match the shapes of the first cylinders  42 . 
     With reference to  FIG. 4 , the first cylinders  42  and second cylinders  54  are oriented vertically, i.e., the axes defined by the first cylinders  42  and second cylinders  54  are oriented in the third direction C. The first cylinders  42  and the second cylinders  54  are parallel to each other, i.e., the axes of the first cylinders  42  and the second cylinders  54  extend in the same direction as each other. 
     The stiffness of each first cylinder  42  is greater than the stiffness of the respective first rib  40  in a vehicle-rearward direction, i.e., opposite the second direction B, and the stiffness of each second cylinder  54  is greater than the stiffness of the respective second rib  52  in the vehicle-rearward direction. For the purposes of this disclosure, “stiffness” of an object in a direction is the resistance to deformation of the object to a force in the direction, i.e., k=F/δ, in which k is the stiffness, F is the applied force, and δ is the deformation in the direction. 
     A sum of the diameters d 1  of the first cylinders  42  and of the diameters d 2  of the second cylinders  54  is greater than a length L of the plate  38  from the first rib  40  closest to the first end  56  of the plate  38  to the first rib  40  closest to the second end  58  of the plate  38 , as represented by the following equation: 
     
       
         
           
             
               
                 
                   ∑ 
                   i 
                 
                  
                 
                   d 
                   
                     1 
                     , 
                     i 
                   
                 
               
               + 
               
                 
                   ∑ 
                   j 
                 
                  
                 
                   d 
                   
                     2 
                     , 
                     j 
                   
                 
               
             
             &gt; 
             L 
           
         
       
     
     in which d 1,i  is the diameter of the ith first cylinder  42 , d 2,j  is the diameter of the jth second cylinder  54 , and L is the length of the plate  38  from the first rib  40  closest to the first end  56  to the first rib  40  closest to the second end  58 . The sum of the diameters of the first cylinders  42  is less than the length L: 
     
       
         
           
             
               
                 ∑ 
                 i 
               
                
               
                 d 
                 
                   1 
                   , 
                   i 
                 
               
             
             &lt; 
             L 
           
         
       
     
     The sum of the diameters of the second cylinders  54  is less than the length L: 
     
       
         
           
             
               
                 ∑ 
                 i 
               
                
               
                 d 
                 
                   2 
                   , 
                   i 
                 
               
             
             &lt; 
             L 
           
         
       
     
       FIGS. 5 and 6  show deformation of the bumper assembly  46  in response to two different types of impact. In  FIG. 5 , the bumper assembly  46  was subject to an impact with a broad object at a relatively high speed, and in  FIG. 6 , the bumper assembly  46  was subject to an impact with a narrow object at a relatively low speed. The bumper assembly  46  provides greater resistance to the type of impact in  FIG. 5  than to the type of impact in  FIG. 6  for a few reasons. First, because the combined diameters of the first cylinders  42  and second cylinders  54  are longer than the length of the portion of the plate  38  to which the first cylinders  42  are attached, the first cylinders  42  and the second cylinders  54  interfere with each other, causing mutual deformation, when impacting a broad object, as shown in  FIG. 5 . By contrast, because the combined diameters of the first cylinders  42  are shorter than the length of the portion of the plate  38  to which the first cylinders  42  are attached, and the same is true of the second cylinders  54 , the first cylinders  42  and the second cylinders  54  have sufficient room to push each other out of the way rather than deforming when impacting a narrow object, as shown in  FIG. 6 . Second, the higher relative stiffness of the first cylinders  42  than the first ribs  40 , and the same for the second cylinders  54  and second ribs  52 , permits the first cylinders  42  and second cylinders  54  to move out of the way of each other when impacting a narrow object, as shown in  FIG. 6 , without deforming. Third, the first ribs  40  are long enough to place the first cylinders  42  farther from the bumper beam  34  than the second cylinders  54 , which increases the ability of the first cylinders  42  and second cylinders  54  to move out of the way of each other when impacting a narrow object, as shown in  FIG. 6 . 
     The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. The adjectives “first” and “second” are used throughout this document as identifiers and are not intended to signify importance or order. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described.