Abstract:
An energy absorbing system including a first connection portion for connection to a first structure, a second connection portion for connection to a second structure, an energy absorbing means including first and second spaced apart wall portions and a control means for controlling deformation of at least part of the energy absorbing means during energy absorption resulting from an impact on the first structure whereby one end portion of the energy absorbing means is adapted to deform before the other end portion.

Description:
[0001]     The present invention relates primarily to vehicles and in a particular application relates to energy absorbing systems for vehicles.  
         [0002]     According to one application the energy absorbing system of the invention may be incorporated in an assembly used to mount a protective bar such as a bull bar to the front of a vehicle.  
       BACKGROUND OF THE INVENTION  
       [0003]     Typically a bull bar is mounted to a vehicle using mounting brackets which at one end are connected to the chassis of the vehicle underneath the vehicle bumper bar and at the other end are connected to the bull bar.  
         [0004]     The problem with existing mounting brackets is that they are not specifically adapted to do anything other than hold the bull bar in place. If the bull bar is hit by something the bull bar is supposed to absorb the majority of the impact and prevent or reduce transferal of any significant impact forces to the vehicle itself. If the vehicle is involved in an accident in which significant impact forces are experienced by the bull bar then the majority of the impact forces will ultimately be transferred to the vehicle. In such a situation the vehicle itself must be designed to absorb forces associated with the impact and to protect the occupants of the vehicle. Most modern vehicles therefore have air bags to protect the occupants.  
         [0005]     Thus it is more common that bull bars are used as a buffer for minor impact. However, because of the design of most modern vehicles it is desirable that a bull bar be mounted in a manner which does not seriously affect the normal functioning of air bags or energy absorbing design of the vehicle.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention is aimed at providing an energy absorbing system which may assist with mounting protective bars such as bull bars to a vehicle in a manner which is able to assist the energy absorbing characteristics of the vehicle to which the bull bar is attached. The energy absorbing system may also be applicable to other situations where mechanical devices are required to absorb impact forces.  
         [0007]     According to the present invention there is provided an energy absorbing system comprising a first connection portion for connection to a first structure, a second connection portion for connection to a second structure, an energy absorbing means including first and second spaced apart wall portions and a control means for controlling deformation of at least part of the energy absorbing means during energy absorption resulting from an impact on the first structure whereby one end portion of the energy absorbing means is adapted to deform before the other end portion.  
         [0008]     It is preferred that the first structure includes a protective bar and the second structure includes a chassis of a vehicle.  
         [0009]     It is preferred that the first connection portion is configured for connection to the first structure through a first mounting means.  
         [0010]     Preferably the second connection portion is configured for connection to the second structure through a second mounting means.  
         [0011]     The energy absorbing means may comprise a hollow section at least in part formed by the first and second wall portions.  
         [0012]     It is preferred that the hollow section has upper and lower end portions.  
         [0013]     The one end portion may correspond with the upper end portion.  
         [0014]     The hollow section preferably comprises a plurality of wall portions including the first and second wall portions.  
         [0015]     The first wall portion may include a front wall portion and a rear wall portion.  
         [0016]     The second wall portion may include a front wall portion and a rear wall portion.  
         [0017]     Preferably the first and second wall portions are connected at front and rear ends.  
         [0018]     Preferably the front wall portions are connected at the front ends and the rear wall portions are connected at the rear ends.  
         [0019]     The front wall portions preferably diverge from the front ends.  
         [0020]     The rear wall portions preferably diverge from the rear ends.  
         [0021]     It is preferred that the rear end of the front portion and the front end of the rear portion of the first portion are connected.  
         [0022]     Preferably the rear end of the front portion and the front end of the rear portion of the first portion are integrally formed together.  
         [0023]     It is preferred that the front and rear portions are separated by a bend.  
         [0024]     Preferably the front and rear portions extend outwardly towards each other.  
         [0025]     The hollow section may have a quadrilateral cross-section.  
         [0026]     According to another embodiment the hollow section has either one of the following cross-sections: 
        diamond shaped, trapezoidal, triangular, elliptical, circular, other geometrical shape, an irregular shape with a space separating the first and second walls.        
 
         [0028]     According to another embodiment the energy absorbing means includes additional wall portions.  
         [0029]     The first connection portion may have a rear end connected directly or indirectly with the energy absorbing means.  
         [0030]     The rear end of the first connection portion may connect with the first and second wall portions.  
         [0031]     It is preferred that the first connection portion has its rear end connected to the front wall portions of the first and second wall portions.  
         [0032]     According to another embodiment the first connection portion has a rear end connected to the junction of front wall portions.  
         [0033]     It is preferred that the first connection portion extends axially.  
         [0034]     It is preferred that the system extends generally in an axial direction.  
         [0035]     The energy absorbing means may be aligned axially with the first connection portion to absorb energy from an impact transferred to the connection portion.  
         [0036]     It is preferred that the first connection portion extends co-linear with front and rear corners of the energy absorbing means hollow section.  
         [0037]     The front wall portions preferably diverge from the first connection portion at approximately 45°.  
         [0038]     The front and rear wall portions preferably diverge at approximately 45°.  
         [0039]     The second connection portion may have a front end connected to the rear end of the energy absorbing means.  
         [0040]     The front end of the second connection portion may be connected to the first and second walls.  
         [0041]     It is preferred that the front end of the second connection portion is connected to the rear ends of the rear wall portions.  
         [0042]     Preferably the front end of the second connection portion is connected to the junction of the rear wall portions.  
         [0043]     The second connection portion preferably extends axially.  
         [0044]     The second connection portion may extend co-linear with the front and rear corners of the hollow section.  
         [0045]     The first connection portion may be substantially planar.  
         [0046]     The second connection portion may be substantially planar.  
         [0047]     It is preferred that the first and second connection portions are substantially co-planar.  
         [0048]     The hollow section may have upper and lower ends.  
         [0049]     The upper and lower ends may be adjacent upper and lower ends of the first and second connection portions.  
         [0050]     The upper end of the hollow section may be substantially co-planar with the upper end of the first and/or second connection portion.  
         [0051]     The first and second connection portions may respectively include additional connection portions.  
         [0052]     The upper ends of the first and second wall portions may be substantially flush with the upper ends of the first and/or second connection portion.  
         [0053]     Preferably upper ends of the wall portion of one of the first or second wall portions is substantially parallel with rear wall portions of the other of the first or second wall portions.  
         [0054]     The hollow section may include wall portions which are curved, flat, irregular or include additional features.  
         [0055]     It is preferred that the lower end of the hollow section slopes downwardly from the front end to the rear end.  
         [0056]     The energy absorbing means may be adapted to crumple, deform, buckle first at one of the upper or lower ends.  
         [0057]     The control means may include a strengthening means for strengthening one of the upper/lower ends.  
         [0058]     The control means may include weakening means for weakening one of the upper or lower ends.  
         [0059]     It is preferred that the strengthening means includes a strengthening assembly.  
         [0060]     The strengthening means may include a plurality of strengthening portions.  
         [0061]     The strengthening means may include a strap.  
         [0062]     The strengthening means may include at least one member for bridging the first and second connection portions.  
         [0063]     It is preferred that the strengthening means includes at least one member connected between the first and second connection portions.  
         [0064]     It is preferred that the members are connected at upper ends of the first and second connection portions.  
         [0065]     According to one embodiment the strengthening means comprises a device for reducing deformability of the upper end of the energy absorbing means/hollow member.  
         [0066]     The strengthening means may comprise a member located inside the hollow section.  
         [0067]     Preferably the strengthening means comprises a device connected to the upper end of the hollow section/first and second wall portions.  
         [0068]     The strengthening means may comprise a device for at least partially closing the upper end of the hollow section.  
         [0069]     Preferably the device for reducing deformability includes at least one member.  
         [0070]     The strengthening means may comprise a first generally planar member.  
         [0071]     Preferably the first generally planar member is connected between the first and second connection portions.  
         [0072]     It is preferred that the strengthening means includes a second member connected to an upper end of the first connection portion.  
         [0073]     The second member is preferably generally planar.  
         [0074]     The second member is preferably connected to the top edge of the first connection portion.  
         [0075]     It is preferred that the second member is connected across the top edge of first connection portion.  
         [0076]     Preferably the second member is connected symmetrically across the top edge of the first connection portion.  
         [0077]     The first and second connection portions are preferably planar.  
         [0078]     The strengthening means may include a third member which may be generally planar and which is connected to the upper end of the second connection portion.  
         [0079]     It is preferred that the third member is connected to the top edge of the second connection portion.  
         [0080]     The third member may be connected across the top edge of the second connection portion.  
         [0081]     The third connection portion may be connected symmetrically across the top edge of the second connection portion.  
         [0082]     It is preferred that a rear end of the third member is connected to a rear end of the second connection portion.  
         [0083]     According to one embodiment the first member has a buckled portion or fold.  
         [0084]     It is preferred that the first member is bent approximately at its mid section.  
         [0085]     Preferably the first member has an apex at its buckled portion which is above the hollow section.  
         [0086]     Preferably the apex is located approximately above the mid point of the hollow section.  
         [0087]     Preferably the first member interconnects the second and third members.  
         [0088]     The strengthening means may include an insert located in an upper end of the hollow section.  
         [0089]     It is preferred that the hollow section and strengthening means form a T-shaped configuration.  
         [0090]     The strengthening means is preferably adapted to resist a predetermined impact force applied to the front end of the first connection portion.  
         [0091]     It is preferred that the strengthening means is adapted to resist a predetermined impact force applied at an angle upwardly with respect to the axial direction of the system.  
         [0092]     Preferably the strengthening means is adapted to oppose a rotational force applied to the hollow section.  
         [0093]     According to one embodiment the strengthening means is adapted to resist a predetermined impact force before absorbing impact energy.  
         [0094]     Preferably the strengthening means is adapted to resist a predetermined impact force applied to the first connection portion before deformation of the energy absorbing means.  
         [0095]     It is preferred that the upper end of the hollow section is configured to resist a first predetermined impact force applied axially before deforming/absorbing energy.  
         [0096]     It is preferred that the lower end of the hollow section is configured to resist a second predetermined impact force applied axially before deforming/absorbing energy.  
         [0097]     Preferably the first predetermined impact force is greater than the second predetermined impact force.  
         [0098]     The weakening means may comprise one or more weaknesses provided in the lower end of the first and/or second wall portions.  
         [0099]     The weakening means may include perforations in one or more walls.  
         [0100]     The weakening means may include openings in one or more walls.  
         [0101]     Preferably the weakening means includes a sloping lower edge of lower end wall portions of the hollow section.  
         [0102]     Weakening means may include a device for assisting deformation of the lower end of the hollow section before the upper end thereof.  
         [0103]     It is preferred that the weakening means includes a slope from the front to the rear end of the first and second wall portions.  
         [0104]     Preferably the weakening means includes a length difference between the front ends compared to the rear ends of the first and second wall portions.  
         [0105]     The slope from the front lower end to the rear lower end may be greater than 45° with respect to vertical.  
         [0106]     The slope of the front lower edge wall portion may be less than the slope of the rear lower edge wall portion.  
         [0107]     It is preferred that the vertical length of the front wall portion(s) is less than the vertical length of the rear wall portion(s).  
         [0108]     Preferably the vertical length of the front wall portions approaches two thirds of the length of the rear wall portion length.  
         [0109]     The first connection portion preferably has substantially parallel upper and lower edges.  
         [0110]     The second connection portion preferably has upper and lower edges which slightly converge from the rear end of the rear wall portions.  
         [0111]     It is preferred that the front of the front wall portions has a greater vertical length than the end of the end wall portions.  
         [0112]     The first and second connection portions may be angled with respect to each other.  
         [0113]     It is preferred that the first connection portion, second connection portion and energy absorbing means are adapted to be inclined upwardly from the second supporting structure, e.g. chassis of a vehicle.  
         [0114]     The combined first and second connection portions and energy absorbing means are preferably oriented at 45° or less with respect to the horizontal.  
         [0115]     It is preferred that the first structure is adapted to be connected to the first connection portion substantially vertically.  
         [0116]     It is preferred that the first structure is connected to the first connection portion square on to the front of the first connection portion.  
         [0117]     It is preferred that the first structure is aligned in parallel vertically with the front of a vehicle of the second structure.  
         [0118]     It is preferred that the connection portion includes a coupling portion for coupling a protective bar to the first coupling portion.  
         [0119]     It is preferred that the first and second walls include a plurality of deformations.  
         [0120]     It is preferred that the hollow section includes a plurality of vertical deformations.  
         [0121]     The strengthening means may include a plurality of deformable members.  
         [0122]     Preferably the hollow section is adapted to be oriented at approximately 45° angle with respect to the vertical.  
         [0123]     Preferably the energy absorbing system includes an assembly including the first connection, the second connection portion, the energy absorbing means and the control means.  
         [0124]     It is preferred that the energy absorbing system is in the form of a mounting means for interconnecting a protective bar and a chassis of a vehicle.  
         [0125]     According to one embodiment the system is adapted to transmit a predetermined impact force to the chassis of a vehicle whereby a triggering means is able to trigger an air bag safety system of the vehicle.  
         [0126]     According to another aspect of the present invention there is provided an assembly incorporating first and second energy absorbing systems spaced apart and axially aligned in parallel.  
         [0127]     According to another embodiment the energy absorbing system includes a mounting system for mounting a protective bar to a chassis of the vehicle including a plurality of energy absorbing systems.  
         [0128]     It should be understood that for convenience terms such as a front, rear, upper and lower have been used to provide a frame of reference for describing various optional features of the invention in a typical application where an assembly is used for mounting a bull bar to a vehicle. However, the energy absorbing system may be considered in different orientations including an orientation in which front becomes rear and upper becomes lower.  
         [0129]     It should also be understood that where terms are referred to in the singular they also include more than one unless preceded by the word “only”.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0130]     Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which:  
         [0131]      FIG. 1  shows a right side angled view of an energy absorbing assembly in accordance with a preferred embodiment of the present invention;  
         [0132]      FIG. 2  shows an angled view of the left hand side of the assembly shown in  FIG. 1 ;  
         [0133]      FIG. 3  shows an angled view of the left hand side of the assembly viewed from above;  
         [0134]      FIG. 4  shows a front angled view of a mounting assembly including the assembly of the preferred embodiment of the present invention; and  
         [0135]      FIG. 5  shows a rear angled view of a mounting assembly for a protective bar according to a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0136]     According to the preferred embodiment of the invention a mounting assembly for a protective bar incorporates a mounting frame structure  10  shown most clearly in  FIGS. 4 and 5 . In the example shown this structure  10  has a horizontal base surface  11  with mounting holes to allow a winch to be attached thereto. On left and right hand sides of this structure, upright mounting brackets  12  and  13  are provided extending around the left and right side rear corners of the structure  10 . The brackets  12  and  13  are provided with appropriately located holes to allow the structure  10  to be bolted to the front chassis of a vehicle.  
         [0137]     Support arms  14  and  15  are provided at the right and left hand ends of the structure  10  and extend from the back of the structure  10  to the front of the structure  10  at an angle which may be 45° approximately with respect to the horizontal base surface  11 .  
         [0138]     The front end of the support arms  14 ,  15  is provided with mounting holes to allow a mounting bracket to attach left and right sides of a protective bar thereto.  
         [0139]     The front parts  16 ,  17  as shown in  FIG. 4  have an upper horizontal edge and front vertical edge and mounting holes which make it easy to orient the protective bar in a vertical orientation with respect to the vehicle and the base horizontal surface  11  of the mounting structure  10 .  
         [0140]     Each of the support arms  14 ,  15  incorporate a primary energy absorbing section  18  and a secondary energy absorbing section  19  shown in greater detail in FIGS.  1  to  3 .  
         [0141]     As the left and right side support arms are substantially identical features described in relation to the left hand side of the mounting structure shown in  FIGS. 1 and 2  are the same as those for the right hand side of the structure shown in  FIG. 3 .  
         [0142]     As shown in  FIG. 1  the support arm  14  is generally planar with a rear plate section  20  oriented perpendicular to the horizontal base  11  and extending forward from the rear wall  21  of left side bracket  12 .  
         [0143]     The lower edge  23  of rear section  20  extends to the front edge of base surface  11  and is spaced inwardly and in parallel with the outer side wall of bracket  12 .  
         [0144]     The top edge of rear section  20  slopes upwardly at approximately 45° and has a rearward section  24  of the secondary energy absorbing section  19  welded perpendicular thereto.  
         [0145]     A front section  25  of rearward section  20  extends from the front lower edge to the top edge and is oriented at substantially 90° to the top edge.  
         [0146]     This section extends into the primary energy absorbing section  18 .  
         [0147]     The primary energy absorbing section  18  is integrally formed or connected to the front section  21  and is thus oriented at around 45° in a rearward direction from the front edge of the horizontal base surface  11 .  
         [0148]     The primary energy absorbing section  18 ,  19  consists of a trapezoidal tubular structure with a trapezoidal passage extending from the lower end  27  to the upper end  28 . The edges  29  of the top end  28  are generally flush with the top edge of the rear section  20  and front section  29 . The lower edges  27  however incline steeply upwardly from the front of the horizontal base surface  11  to the lower edge  30  of front section  29 .  
         [0149]     The primary energy absorbing section  18 ,  19  is configured to have front and rear edges  31 ,  32  aligned with the front edge  25  and rearward edge  33  of the rear and front sections  20  and  29  respectively. It follows that the other two edges of the section  18 , 19 ,  33 ,  34  are symmetrically arranged on either side of the general plane in which the arms  14  and  15  extend.  
         [0150]     The front section  29  extends in the same general direction at approximately 45° from the horizontal base surface from the front edge  32  of section  18 ,  19 . As previously described at its outer end the front section  29  is configured to have a head or nose section incorporating a horizontal top surface  35  and vertical front surface  36 .  
         [0151]     Three mounting slots  37  are provided to allow a bull bar to be connected thereto through a mounting plate.  
         [0152]     The secondary energy absorbing section  19  consists of rear plate section  24 , front section  37  and mid section  38 .  
         [0153]     The rear section  24  extends from the top edge of rear wall  21  of bracket  12  to a region close to but before the front edge of the primary energy absorbing section  31 .  
         [0154]     The middle section  38  extends upwardly at an angle from the front edge of rear section  24  to an apex  39  extending laterally across the passage  26  approximately above edges  33  and  34  and slopes downwardly again at approximately the same angle to the rearward edge of front section  37 . Front section  27  then extends forward approximately halfway along the top edge before the horizontal edge  35  of front section  29 .  
         [0155]     The function of the primary and secondary energy absorbing sections will now be described as follows.  
         [0156]     When the mounting structure is in use it is attached to the chassis of a vehicle through mounting brackets  12  and  13 . A protective bar such as a bull bar is connected to the mounting arms  14 , 15  so that the protective bar is generally oriented vertically so as to encounter any impact forces before the vehicle chassis.  
         [0157]     If a vehicle with the assembly described above mounted to it hits a structure while travelling at speed, for a front on collision, impact forces are initially experienced by the protective bar. These forces pass through the bar to the mounting arms  14 ,  15  and are ultimately transmitted through to the chassis of the vehicle. However impact forces experienced by the mounting arms  14 ,  15  tend to force each front section rearwardly. These forces are then transmitted to the primary energy absorbing section  18  which is designed to deform or crumple, absorbing energy associated with the impact forces in the process. The primary energy absorbing section works more efficiently if impact forces are directed axially so as to strike the front edge  34 . In reality this would be unlikely to occur as impact forces are more likely to have at least some component which is not aligned with the axis of each arm. This would result in the primary energy absorbing section not necessarily absorbing energy in the most efficient manner. Ultimately this could result in ineffective operation of the primary energy absorbing section  18 ,  19 .  
         [0158]     In some embodiments it may be preferable that the mounting arms are oriented so that the primary energy absorbing section is oriented vertically.  
         [0159]     To provide some control over the operation of the primary energy absorbing section, the secondary energy absorbing section provides a predetermined amount of strengthening to the upper end of the primary energy absorbing section  18 ,  19 . In addition the lower end of the primary energy absorbing section is weakened by having a lower sloping edge from the rear edge  31  to the front edge  34 . Thus as a significant amount of the front walls and to a lesser extent the rear walls have been eliminated or cut away, there is less strength to resist any impact forces at the lower end of the primary energy absorbing section  18 ,  19 . The combined effect of both of these strengthening and weakening features results in a tendency of any impact forces received by the primary energy absorbing section to deform the lower end of this section before the upper end. Therefore initially impact forces are able to pass more easily to the chassis of the vehicle through the lower regions of each mounting arm. This can enable enough forces to be transmitted initially during a collision for any anti-collision systems of the vehicle to operate. For example an airbag may be able to operate from the initially transmitted forces.  
         [0160]     Another benefit with the above configuration may be a slight reorientation of the primary energy absorbing section so that it is slightly more upright and facing impact forces head on.  
         [0161]     Once a predetermined amount of impact force has been transmitted the primary and secondary energy absorbing sections are able to absorb much more of the impact forces. This is achieved by crumpling of the primary energy absorbing section so that the front and rear edges move closer together and the lateral edges  33 ,  34  move further apart. In addition the secondary energy absorbing section absorbs energy through the mid section  38  which is able to bend further as the front section  37  is pushed towards the rear section  24 . It is preferred that each of the front, middle and rear sections are metal plates which are welded together and welded to the top edges of the rear and front sections  20 ,  29 .  
         [0162]     By having the mid section  38  not connected to the upper edges  28  of the primary energy absorbing section this allows both sections to operate independently.  
         [0163]     It is noted however that other options may be used to strengthen the upper end of the primary energy absorbing section such as having a strengthening plate, tube, or other structure located inside the top end of the passage  26 . Alternatively gussets or strengthening members may be added to the outer walls at the upper end of the primary energy absorbing section to provide a predetermined amount of resistance to deformation but to ultimately allow energy absorption.  
         [0164]     Weakening of the lower end of the primary energy absorbing section may also be provided by providing holes, openings or perforations in the lower end of the primary energy absorbing section.  
         [0165]     The trapezoidal shape of the tubular section may also be changed to a different geometrical shape whereby walls of the primary energy absorbing section are able to deform to absorb energy.  
         [0166]     It is preferred that the lower end of the tubular structure is inclined at an acute angle wherein at least one quarter of the front walls are at least partially removed.  
         [0167]     It is noted that a greater amount of the front walls of the tubular section is removed at the lower ends compared to the rear two walls. As shown in  FIG. 3  the right hand side of the mounting structure is provided with a similar mounting arm  17 . For convenience the mid section of the secondary energy absorbing section has been removed to show the trapezoidal cross-section of the primary energy absorbing section.  
         [0168]     It is also easier to see the mounting bracket  13  which has a U-shaped configuration with the rear vertical wall  21  and spaced apart side walls  40 ,  41  extending at right angles forwardly with the mounting arm rear section located closer to the inner side wall  41 .  
         [0169]     It is preferred that the energy absorbing system allows the ability to tune the design of the vehicle air bag trigger system associated with the vehicle to which the energy absorbing system is mounted.  
         [0170]     According to another embodiment it may be desirable to have the primary energy absorbing section oriented more to the vertical.  
         [0171]     It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or in any other country.  
         [0172]     In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.