Abstract:
An active vehicle front structure for energy management including a bumper movable from a retracted position during low speed maneuvering and parking to an extended position during operation of the vehicle over a pre-defined threshold speed. The bumper in the extended position serves to extend the crumple zone, reducing overall vehicle damage, and to increase the time over which the vehicle decelerates during a collision, reducing the likelihood and severity of injuries to occupants of the vehicle.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to systems for managing the energy transmitted to a vehicle body during a collision. In one of its aspects, the invention relates to an active vehicle front structure for energy management.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the event of a collision, it is preferred that the body of a vehicle absorb the energy of the collision and that it not be transmitted to the passenger compartment or to the passengers. It is also preferred that, in the instance of minor collision incidents, any damage to the vehicle structure be localized or limited to a pre-defined portion of the vehicle to minimize cost of and time to effect repairs. These desirable ends must be balanced against a reasonable cost of manufacture and the desires of the consumer for aesthetically pleasing vehicles.  
           [0003]    One means of providing a structure that absorbs energy and minimizes damage to other vehicle systems in the event of minor collisions is to provide an extensive bumper system that projects outwardly from the remainder of the vehicle. Another alternative only focused on minimizing intrusion into the passenger compartment is to extend the overall exterior dimensions of the vehicle. While effective in protecting the passengers, this alternative runs counter to the additional goals of keeping production and repair costs in check.  
           [0004]    The extended bumper alternative has a couple of disadvantages. It can present a design challenge in integrating it into an acceptable overall vehicle appearance for the consumer. It also presents the problem of making the vehicle unnecessarily long or unwieldy in close maneuvering situations, such as in a parking lot or garage.  
           [0005]    It would be advantageous to develop a system that would have the cost and protective advantages of an extended bumper system, while avoiding the disadvantages of a bumper that is difficult to integrate into the vehicle design, or that unnecessarily extends the overall length of the vehicle.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention provides an active vehicle front structure for energy management. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]    [0008]FIG. 1 is a perspective view of a vehicle front end incorporating an active vehicle front structure for energy management according to the invention.  
         [0009]    [0009]FIG. 2 is a perspective view of the frame of the vehicle front end of FIG. 1 with the active vehicle front structure in a retracted position.  
         [0010]    [0010]FIG. 3 is an exploded perspective view of the frame structure incorporating active vehicle front structure of the vehicle front end of FIGS.  1 - 2 .  
         [0011]    [0011]FIG. 4 is another exploded perspective view of the frame structure of FIGS.  1 - 3 .  
         [0012]    [0012]FIG. 5 is an enlarged exploded perspective view of the locking mechanism of the active vehicle front structure for energy management of FIGS.  1 - 4 .  
         [0013]    [0013]FIG. 6 is a perspective view of the active vehicle front structure for energy management of FIG. 5 in an extended position.  
         [0014]    [0014]FIG. 7 is a perspective view of the active vehicle front structure for energy management of FIGS.  1 - 6  in a retracted position.  
         [0015]    [0015]FIG. 8 is a flow chart showing the decision process of extending and retracting the active vehicle front structure for energy management of FIGS.  1 - 7 .  
         [0016]    [0016]FIG. 9 is a perspective view of a further embodiment of the active vehicle front structure for energy management according to the invention.  
         [0017]    [0017]FIG. 10 is an enlarged perspective view of the active vehicle front structure for energy management of FIG. 9.  
         [0018]    [0018]FIG. 11 is a plan view of the active vehicle front structure of FIGS.  9 - 10 .  
         [0019]    [0019]FIG. 12 is a perspective view of the active vehicle front structure of FIGS.  9 - 11 .  
         [0020]    [0020]FIG. 13 is an exploded perspective view of the locking mechanism of the active vehicle front structure of FIGS.  9 - 12 .  
         [0021]    [0021]FIG. 14 is an exploded rear perspective view of the active vehicle front structure of FIGS.  9 - 13 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    A vehicle  110  generally has a fixed front bumper  120 , as shown in FIG. 1. The fixed front bumper  120  is intended to provide a protective function, while still providing an aesthetically acceptable appearance.  
         [0023]    An active vehicle front structure for energy management  100  according to the invention is shown in FIGS.  1 - 7 . The active vehicle front structure  100  is contained substantially within the vehicle body and includes, broadly, a front impact beam  90  that in the retracted position conforms generally aesthetically to the vehicle fixed front bumper  120 , a pair of energy management sleeves  2  that extend longitudinally into the vehicle along rail members of the vehicle, and a drive mechanism for selectively extending and retracting the impact beam  90  forward of the vehicle fixed bumper  120 .  
         [0024]    The vehicle frame includes at a forward portion thereof a rear outer frame  4  and a rear inner frame  5 . In a conventional configuration, the vehicle bumper is secured to the rear outer and rear inner frame  4 ,  5 . Referring to FIGS.  2 - 4 , a hollow tubular rail extension  50  is formed from a rail extension inner  6  and a rail extension outer  3 , and is adapted to fasten to the forward portion of the vehicle frame. In the depicted configuration, the rail extension  50  is substantially octagonal in cross-section, but this is not strictly necessary and should not be considered a limitation of the invention.  
         [0025]    The rail extension  50  has a rear portion  52  adapted to attach to the vehicle frame and a forward portion  54  adapted to receive the energy management structure  100  according to the invention. The forward portion  54  of the rail extension  50  is open and tubular, and includes a number of apertures  56  spaced about its outer circumference. The apertures  56  are adapted to cooperate with a similar number of locking links  16  that are arranged to selectively pass through the apertures  56  to lock the energy management structure  100  in an operative position.  
         [0026]    Referring to FIG. 5, a locking mechanism  70  comprises a front rail extension end cap  12 . The end cap  12  is adapted to be fixed in the open forward portion  54  of the rail extension  50 . The end cap  12  includes an outer perimeter for being received in the rail extension  50 , and a central aperture  72  having outwardly extending slots  74  for receiving the locking links  16 .  
         [0027]    Each locking link  16  is substantially J-shaped, having a first end  76  adapted to be received in one of the slots  74  of the end cap central aperture  72 . A locking link pivot pin  13  cooperates with the edges of each slot  76  to pivotally connect each locking link  16  to the end cap  12 . Each locking link  16  also has a second end  78  having a flat, square plate  80 , much the ‘hat’ on a ‘J’. As shown in FIG. 3, each of the four locking links  16  extend radially from the central aperture  72  of the end cap  12 , with the ‘hat’  80  of each J-shaped locking link  16  substantially parallel to and proximate the circumference of the tubular rail extension  50 . With the end cap  12  in place on the end of the rail extension  50 , the locking links  16  are confined within the tube of the rail extension  50 , and aligned with the apertures  56  of the rail extension  50 . The first end  76  of the locking links  16  back onto a central axis of the rail extension  50  and end cap  12 . Each of the locking links  16  are biased toward the central axis by a spring or other resilient member (not shown).  
         [0028]    A drive nut mounting bracket  11  is mounted across the opening of the end cap  12  opposite the locking links  16  and includes a central opening  82 . A ball screw drive nut  17  is fixed to the drive nut mounting bracket  11  on the central axis of the end cap  12 . A ball screw  15  having a ball screw cam  14  is threaded through the ball screw drive nut  17  so that the shaft  84  of the ball screw  15  lies on the central axis of the end cap  12 , passing between the first ends  76  of the locking links  16 . The ball screw cam  14  is positioned opposite the drive screw mounting bracket  11  so that it resides within the rail extension  50 . A bushing end  86  of the ball screw  15  extends beyond the drive nut  11  opposite the ball screw cam  14 . One each of the locking mechanism  70  is fixedly mounted in a rail extension  50  on each end of the impact beam  90 .  
         [0029]    Impact beam  90  is tubular in nature, including a front impact beam portion  1  and a rear impact beam portion  8 . An impact beam movement mechanism  92  is mounted within the tubular impact beam  90 . The impact beam movement mechanism  92  housed within the impact beam  90  includes a drive motor  7 , worm gear assemblies  19 , and associated drive cable assemblies  18 . Each of the worm gear assemblies  19  is driven by the drive motor  7  via the associated drive cable assembly  18 . Each worm gear assembly  19  is adapted to drive one of the ball screws  15 .  
         [0030]    The impact beam  90  is mounted on each end to a rail energy management sleeve  2 . Each rail energy management sleeve  2  is aligned with a rail extension  50  and is adapted to slide over the associated rail extension  50 . A ball screw bushing  20  is mounted in an end of the energy management sleeve  2  adjacent the impact beam  90  and worm gear assembly  19 . At the opposite end, each energy management sleeve  2  includes a number of apertures  96  complementary to and adaptable to align with the apertures  56  of each rail extension  50 .  
         [0031]    The bushing end  86  of the ball screw  15  is rotatably received and axially fixed in the ball screw bushing  20 . The ball screw  15  is linked to the worm gear assembly  19  for rotation by the drive motor  7  and worm gear assembly  19 .  
         [0032]    Referring now to FIGS. 2 and 6, the impact beam  90  has a retracted position and an extended position. In the retracted position, the impact beam  90  is closely associated against the front of the vehicle as the energy management sleeves  2  fully cover the rail extensions  50 , and the ball screw  15  of each assembly has been threaded all the way toward the rear of the vehicle.  
         [0033]    The impact beam  90  is moved from the retracted position to the extended position by the drive motor  7 . The drive motor  7  simultaneously spins each drive cable assembly  18  in a conventional manner to drive each worm gear assembly  19 . Each worm gear assembly  19  rotates a respective ball screw  15  in its drive nut  17 , forcing the ball screw  15  forward. Each ball screw  15  is axially fixed to the ball screw bushing  20 , which is in turn fixed to the impact beam  90 , causing the impact beam  90  to move forward relative to the rail extensions  50 . As the ball screw  15  reaches its forwardmost position, the ball screw cam  14  reaches the curved first ends  76  of the locking links  16 , forcing them radially outward toward the walls of the rail extensions  50 . As this is occurring, the complementary apertures  96  of the energy management sleeves  2  come into alignment with the apertures  56  of the rail extensions  50 . As the impact beam  90  reaches the fully extended position, the locking links  16  extend through the aligned apertures  56 ,  96  of the rail extensions  50  and energy management sleeves  2 .  
         [0034]    In the case of an impact, the ball screw bushing  20  and worm gear assembly  19  will not dislodge the locking assembly  70 . Specifically, the locking links  16  will not disengage the complementary apertures  56 ,  96  of the rail extensions  50  and energy management sleeves  2 . The impact beam  90  is thus maintained at the fully extended position during an impact, thus increasing the available crush zone of the vehicle.  
         [0035]    During normal operations, when there has been no impact, the impact beam  90  can be retracted in the reverse order as it was extended. As the drive motor  7 , through the drive cable and worm gear assemblies  18 ,  19 , rotates the ball screws  15 , each ball screw cam  14  retreats from the locking links  16 . The ball screw/locking link arrangement ensures that the locking links  16  retract quickly so that the energy management sleeves  2  are not obstructed from sliding over the rail extensions  50 . The drive motor  7  stops when the impact beam  90  is in the fully retracted position.  
         [0036]    The active vehicle structure for energy management is provided with a control system for selectively extending and retracting the impact beam  90 . In the sample flowchart shown in FIG. 8, the impact beam  90  is extended only when the vehicle speed exceeds a first threshold, and is retracted only when the vehicle speed drops below a second threshold. A partial extension may be implemented in the speed range between the first and second thresholds. The impact beam  90  can conceivably be manually controllable, or the speed thresholds be selectable.  
         [0037]    A further embodiment of the front structure for energy management  200  is shown in FIGS.  9 - 14 . The impact beam assembly and drive motor, cable and worm gear assemblies are substantially as described above.  
         [0038]    A pair of L-shaped locking links  216  are pivotally mounted within an energy management sleeve  202  and are spring-biased outwardly. The energy management sleeve  202  includes a pair of slots  296  aligned with the locking links  216 . As the impact beam  90  is extended by the drive motor/drive cable/worm gear/screw combination, the slots  296  of the energy management sleeve  202  align with an opening into a pocket  256  in the rail extension  250 . One leg of the ‘L’ of each spring-biased locking link  216  passes through the slot  296  and into the pocket  256  in the rail extension  250 . The other leg of the ‘L’ of each locking link  216  comes to rest against the inside surface of the rail extension  250 , in alignment with the front edge of the slot  296  in the energy management sleeve  202 . The energy management sleeve  202  is rigidly attached to the impact beam  90 . In the event of an impact, each L-shaped locking link  216  forms a block to transfer the force of the impact from the front edge of the slot  296  in the energy management sleeve  202  to the pocket  256  in the rail extension  250 . Under the controlled withdrawal of the energy management sleeve  202  by the drive mechanism, the L-shaped locking links  216  can rotate about the central pivot pin  213  and withdraw from the pocket  256  in the rail extension  250 , allowing the impact beam  90  to return to the retracted position.  
         [0039]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.