Abstract:
An energy absorber for improving passenger safety in a vehicle during an impact to the vehicle, the energy absorber comprising a hollow body having a base defining a proximal end of the body, the base being configured to affix the body to a portion of the vehicle, the body further including a sidewall extending from the base and terminating in a distal end of the body, the sidewall having an interior surface and an exterior surface, the interior surface including a portion defining an interior step transition, the exterior surface including a portion defining an exterior step transition, the interior and exterior step transitions being provided at locations axially offset from each other along the sidewall.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention generally relates to energy absorbing systems and, in particular, to an energy absorbing component of such systems. Energy absorbing systems, of the kind to which the invention relates, are utilized in various automotive vehicle applications to absorb forces during an impact and to enhance the collision protection of the vehicle&#39;s occupants. 
     2. Description of Related Art 
     In numerous applications, it is desirable to provide a means by which the shock or impact forces of a collision are absorbed. This is particularly true in automotive vehicles, where the side of the vehicle is often subjected to impact. Side impacts may occur anywhere along the side of the vehicle, but when they occur in the door regions, they may particularly result in the forces of the impact being transferred through the door regions into the passenger compartment or cabin of the vehicle. For this reason, many original equipment manufacturers include energy absorbing components (also known as energy absorbers), of one type or another, between exterior and interior panels, or other structures, of the vehicle doors. 
     Various types of energy absorbing components are known. Typically, these energy absorbing components operate by being positioned between two elements of the vehicle, such as a sheet metal panel and then interior trim panel of a door, and deforming under stress. The energy absorbing components may take many forms, including foam blocks of suitable density and rigidity. Suitable foam blocks, because of the required density, can significantly add to the weight of the door and, ultimately, the vehicle, particularly when the distance between the two elements is large. 
     In such instances, hollow elongated bodies have found use as the energy absorbing components. These hollow bodies are generally made of plastic and have a variety of shapes including rectangular, cylindrical or conical. During use, a force applied exteriorly to the door is transferred to one end of the hollow body. The hollow body is designed so that when the body experiences a given stress, it will either elastically or plastically deform, thereby absorbing some of the force being exerted against the door and reducing the amount of force that is transmitted through the door and potentially to an occupant of the vehicle. 
     When undergoing deformation, the hollow body may be designed to react in a variety of ways. In one known reaction manner, while the hollow body is crushed, it collapses upon itself. Controlling such a collapse is an important consideration in the design of an energy absorbing component of this variety. 
     SUMMARY 
     In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides an energy absorber for improving passenger safety in a vehicle during an impact to the vehicle, the energy absorber comprising a hollow body having a base defining a proximal end of the body, the base being configured to affix the body to a portion of the vehicle, the body further including a sidewall extending from the base and terminating in a distal end of the body, the sidewall having an interior surface and an exterior surface, the interior surface including a portion defining an interior step transition, the exterior surface including a portion defining an exterior step transition, the interior and exterior step transitions being provided at locations axially offset from each other along the sidewall. 
     In another aspect of the invention, the interior and exterior step transitions define thickness changes in the sidewall. 
     In a further aspect of the invention, proceeding along the sidewall from the distal end toward the base, one of the interior and exterior step transitions decreases the thickness of the sidewall and the other of the interior and exterior step transitions increases the thickness of the sidewall. 
     In yet another aspect of the invention, proceeding along the sidewall from the distal end towards the base, the interior step transition decreases the thickness of the sidewall and the exterior step transition increases the thickness of the sidewall. 
     In an additional aspect of the invention, the sidewall exhibits a tapered thickness in a region between the interior step transition and the exterior step transition. 
     In another aspect of the invention, the sidewall exhibits a tapered thickness, the tapered thickness increasing in thickness proceeding from the distal end towards the base. 
     In still a further aspect of the invention, the sidewall includes two interior step transitions and one exterior step transition. 
     In an additional aspect of the invention, the exterior step transition is axially located at a position along the sidewall between the two interior step transitions. 
     In another aspect of the invention, the sidewall has a first sidewall thickness on one side of the interior step transition and a second sidewall thickness on the other side of the interior step transition, the first sidewall thickness being different from the second sidewall thickness. 
     In still another aspect of the invention, the sidewall exhibits a minimum sidewall thickness defined at a location adjacent to the one of the interior and exterior step transitions that is located closest to the distal end. 
     In yet another aspect of the invention, the sidewall has a tapered thickness between successive ones of the interior and exterior step transitions, the tapered thickness increasing in thickness proceeding from the distal end toward the base. 
     In a further aspect of the invention, the sidewall has a plurality of tapered thickness regions, the tapered thickness regions increasing in thickness proceeding from the distal end toward the base. 
     In another aspect of the invention, the distal end includes an end wall closing off one end of the body. 
     In still another aspect of the invention, an energy absorber for improving passenger safety in a vehicle during an impact to the vehicle is provided, the energy absorber comprising a hollow body having a base defining a proximal end of the body, the base being configured to affix the body to a portion of the vehicle, the body further including a sidewall extending from the base and terminating in a distal end of the body; and proceeding along the sidewall from the distal end toward the base, the sidewall transitioning at a first step transition from a first sidewall thickness to a second sidewall thickness, the second sidewall thickness being less than the first sidewall thickness. 
     In a further aspect of the invention, proceeding along the sidewall from the first step transition toward the base, the sidewall transitioning at a second step transition from a third sidewall thickness to a fourth sidewall thickness, the third sidewall thickness being greater than the second sidewall thickness but less than the fourth sidewall thickness. 
     In yet another aspect of the invention, between the first and second step transitions, the sidewall exhibits a tapered thickness. 
     In an additional aspect of the invention, proceeding along the sidewall from the second step transition toward the base, the sidewall transitioning at a third step transition from a fifth sidewall thickness to a sixth sidewall thickness, the sixth sidewall thickness being less than the fifth sidewall thickness. 
     In another aspect of the invention, between the second and third step transitions, the sidewall exhibits a tapered thickness. 
     In still a further aspect of the invention, the taper thickness increases in thickness between the third step transition and the base. 
     In an additional aspect of the invention, the tapered thickness increases in thickness between the third step transition and the base. 
     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an automotive vehicle door having energy absorbing components incorporating the principles of the present invention; 
         FIG. 2A  is a quartering view, taken from the base, of one embodiment of an energy absorbing component incorporating the principles of the present invention; 
         FIG. 2B  is a quartering view, also taken from the base, to a second embodiment of an energy absorbing component incorporating the principles of the present invention; 
         FIG. 3  is a side elevational view of an energy absorbing component incorporating the principles of the present invention; 
         FIGS. 4A and 4B  are cross-sectional views, generally taken along line  4 - 4  of  FIG. 3 , through an energy absorbing component incorporating the principles of the present invention; and 
         FIGS. 5-7  are cross-sectional views, similar to that seen in  FIG. 4 , respectively illustrating the energy absorbing component in progressively collapsed states. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, an energy absorbing system embodying the principles of the present invention is illustrated in  FIG. 1  and designated at  10 . As depicted in  FIG. 1 , the energy absorbing system  10  is a component of an automotive vehicle, namely a door. As its primary components, the application of the energy absorbing system  10  in an automotive vehicle door includes an exterior panel  12 , an interior panel  14  and one or more energy absorbing components  16  positioned so as to at least partially fill a void  18  or space between the exterior and interior panels  12 ,  14 . In this application, the exterior panel  12  may be the sheet metal panel defining the exterior skin of the door, and the interior panel  14  may be the interior trim panel of the door. As seen in  FIG. 1 , a plurality of energy absorbing components  16  are mounted to the interior panel  14  and extend in a direction away from the interior panel  14  toward the exterior panel  12 . 
     During a collision in which the door is subjected to an impact force, such as a side-impact to the automotive vehicle, the impact force causes the exterior panel  12  to deform toward the interior panel  14 . With the energy absorbing components  16  located within the void  18  between the exterior panel  12  and the interior panel  14 , the amount of force that is transmitted through the door and to an occupant located in the passenger compartment of the vehicle is diminished and reduced by the energy absorbing components  16 , which crush and/or deform during the collision. The passenger compartment of the vehicle is represented in  FIG. 1  as the area generally to the right of the interior panel  14  and is designated at  20 . 
     While the energy absorbing system  10  is illustrated in  FIG. 1  as including four energy absorbing components  16 , provided as a linear array or straight-line series, it will be appreciated that the number of energy absorbing components  16  and their arrangement within the void  18  will and can depend upon the particular design of the energy absorbing system  10  for the vehicle. For example, the system  10  may include as many energy absorbing components  16  as can be arranged and fitted within the void  18  so that the void is completely or substantially filled. In another example, the system  10  may include just one energy absorbing component  16  that is strategically positioned within the void  18 . 
     Generally, the energy absorbing component  16  is defined by a body  22  that includes a sidewall  24  extending from a proximal end  26  to a distal end  28 . The proximal end  26  defines a base  30  that is configured to secure the energy absorbing component  16  to the interior panel  14  of the energy absorbing system  10 . The base  30  may be provided in the form of a flange extending radially outward from the sidewall  24 . 
     The distal end  28  of the body  22  is provided with an end wall  34  that extends radially inward so as to close off the distal end of the body  22 . It will be appreciated, however, that the end wall  34  may alternatively only extend partially across the distal end  28  or may be omitted altogether. In those embodiments, the body  22  is not closed off at the distal end  28 . In each of the above embodiments, it is seen that the body  22  is a hollow body. 
       FIGS. 2A and 2B  illustrate two alternative configurations for the energy absorbing component  16  and, in particular, the shape of the sidewall  24  of the body  22 . As seen in  FIG. 2A , the sidewall  24  is generally square or rectangular in cross-section, with rounded corners. This provides the body  22  with what may be characterized as a cube or boxed shape. In  FIG. 2B , the cross-section of the sidewall  24  is generally round. This provides the body  22  with a shape characteried as tubular or cylindrical. As will be appreciated, other closed sidewall shapes could be provided as the cross-sectional shape of the sidewall  24 . 
     To absorb the impact force, the construction of the energy absorbing component  16  allows it to crush or collapse in a predetermined or controlled manner during an impact. This controlled collapsing of the energy absorbing components  16  is facilitated by the incorporation of specific features into the sidewall  24  of the body  22 . While these features are illustrated in  FIGS. 1-2B , they are perhaps best seen with reference to  FIGS. 3 ,  4 A and  4 B. As will be appreciated from a study of the figures,  FIGS. 3 ,  4 A and  4 B can and are to be interpreted as elevational and cross-sectional representations of both embodiments shown in  FIGS. 2A and 2B . 
     By collapsing during an impact, some of the energy of the impact is absorbed by the energy absorbing component  16 , reducing the energy potentially transferred to an occupant of the vehicle. In the energy absorbing component  16  of the present invention, the collapsing of the body  22  is controlled by specifically configuring the sidewall  24 . More specifically, the sidewall  24  is provided with a series of steps  36 , each of which defines a failure point enabling the controlled collapsing of the energy absorbing component  16 . Additionally, the thickness of the sidewall  24  varies along its axial length, or more specifically, the length progressing from the proximal end  26  to the distal end  28 . 
     Regarding the formation of the steps  36  along the sidewall  24 , the sidewall  24  is provided with at least one step  36  and is preferably provided with more than one step  36 . In the illustrated embodiment, the sidewall  24  has three steps  36 . 
     Each step  36  forms a transition or change in height or thickness of the sidewall  24 . Alternatively, the steps  36  can be viewed as defining a change in the distance of the sidewall&#39;s interior or exterior surfaces  38 ,  40  from a central axis  42 , defined longitudinally through the body  22 . In providing the steps  36 , the steps  36  are alternatingly formed on the interior and exterior surfaces  38 ,  40  of the sidewall  24 . As seen in  FIG. 4A , when proceeding from the distal end  28  toward the proximal end  26 , a first step  44  is encountered on the interior surface  38 , a second step  46  is encountered on the exterior surface  40 , and a third step  48  is thereafter again encountered on the interior surface  38 . The steps  36  may be evenly spaced along the sidewall  24  or they may be unevenly spaced. 
     As is evident from  FIGS. 4A and 4B , the general thickness of the sidewall  24  changes at each of the steps  36 . Again proceeding from the distal end  28  toward the proximal end  26 , it is seen that, at the first step  44 , the thickness of the sidewall  24  changes from a general thickness T1 to a second general thickness T2, with the first thickness T1 being greater than the second thickness T2. At the second step  46 , the thickness of the sidewall changes from the second general thickness T2 to a third general thickness T3, with the second thickness T2 being less than the third thickness T3. At the third step  48 , the thickness changes from the third general thickness T3 to a fourth general thickness T4, wherein the third thickness T3 is greater than the fourth thickness T4. Stated another way, as illustrated, the thickness of the sidewall  24  goes from an increased thickness to a decreased thickness, back to an increased thickness, and then again back to a decreased thickness. Alternatively, the thickness changes would be reversed. 
     Described in terms of the relative distance of the surfaces of the sidewall  24  from the longitudinal axis  42  of the body  22 , it is seen that both the interior surface  38  and the exterior surface  40  increase in their distance from the longitudinal axis  42  at each of the steps  36  (when progressing along the sidewall  24  from the distal end  28  to the proximal end  26  of the body  22 ). Thus, the interior surface  38  defines a first general distance D1 before the first step  44  and a second general distance D2 after the first step  44 , as well as a third general distance D3 after the third step  48 , with each of these distances being successively greater than the preceeding distance. Regarding the exterior surface  40 , a fourth general distance D4 is defined before the second step  46 , and a fifth general distance D5 is defined after the second step  46 , with the fourth distance D4 being less than the fifth distance D5. It further follows that the fourth distance D4 is greater than the first distance D1 and the second distance D2, and that the fifth distance D5 is greater than the second distance D2 and the third distance D3 since the relative locations of these two exterior surfaces are radially outward of the noted/corresponding interior surfaces. 
     As will be appreciated from a review of  FIG. 4 , the above-mentioned thicknesses and distances are general in nature and cover a region or portion of the sidewall  24 . These thicknesses and distances are referred to as being general in nature because the interior and exterior surfaces  38 ,  40  of the sidewall  24  are not parallel to the central axis  42 . Rather, the interior and exterior surfaces  38 ,  40  are slightly angled outwardly from the central axis  42 , again proceeding from the distal end  28  to the proximal end  26  of the body  22 . 
     Additionally, the interior and exterior surfaces  38 ,  40  themselves are not parallel to one another. Instead, these surfaces  38 ,  40  diverge from one another in the direction of the base  30 . In other words, for a given length of the sidewall  24  between any two steps  36 , the thickness of the sidewall generally increases when proceeding in the direction toward the base  30 . For this reason, the general thickness T2 is specifically seen to be thinner immediately after the first step  44  than immediately before the second step  46 . 
     Referring now to  FIGS. 5-7 , seen therein is a sequential representation of the energy absorbing component  16  during a collision in which the exterior panel  12  is deformed towards the interior panel  14 . While the exact movement of the collapsing of the sidewall  24  may vary due to the actual nature of the collision, the following discussion is representative of the controlled collapse experienced by the energy absorbing structure  16 . 
     Seen in  FIG. 5  is an initial stage of collapse. During this initial stage of collapse, the energy absorbing structure  16  has suffered a failure at the first step  44 . With this failure, the thinnest portion of the sidewall  24  (which has a thickness of t 2  immediately after the first step  44 ) folds back upon itself and the thicker portion t 1  of the sidewall  24  before the first step  44 , forming a folded portion  50 . During this, the thicker portion t 1  is driven slightly radially inward and alongside of the folded portion  50 . 
     Further collapse of the energy absorbing component  16  results in the unfolding of the folded portion  50  as the first step  44  is driven axially past the second step  46 . In this state, which is seen in  FIG. 6 , a second failure of the sidewall  24  occurs at the second thinnest portion of the sidewall  24 , which is at the thickness t 2  immediately before the second step  46 . With the second failure, that portion (generally T2) of the sidewall  24  located between the first step  44  and the second step  46 , now lies adjacent and radially inward of the thicker portion (generally T3) of the sidewall after the second step  46 , in other words, between T1 and T3. 
     If the energy absorbing component  16  is further collapsed, the collapsing proceeds in a manner similar to that of the initial collapse. During this third state of failure, the third thinnest portion of the sidewall  24 , with thickness t 4  immediately after the third step  48 , fails and folds upon itself, forming another folded portion  52 . 
     As seen from the above description of the collapsing of the energy absorbing component  16 , the collapse can generally be described as one in which the sidewall  24  of the component  16  progresses into an accordion or corrugated structure. With the changes in thicknesses of the sidewall  24  at and between each of the steps  36 , the deformation and collapse of the energy absorbing component  16  is consistent and exhibits more controlled energy absorption properties. The component  16  first fails at the thinnest location of the sidewall  24  (which is thickness t 2  immediately after the first step  44 ), and then fails at the second thinnest location (which is thickness t 3  immediately before the second step  46 ), and so on as failure continues. 
     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles of this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.