Abstract:
An apparatus is disclosed for extending a bumper on a motor vehicle having driven wheels. The apparatus includes a drive to derive power from the rotating wheels, an actuator for extending the bumper, and a controller for connecting the actuator to the drive. When bumper extension is desired, drive power is transferred from the motor vehicle&#39;s rotating wheels to the actuator to effect deployment of the bumper.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Application No. 61/013,922 filed on Dec. 14, 2007 incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to extendable bumpers for motor vehicles. 
       DESCRIPTION OF THE PRIOR ART 
       [0003]    Extendable bumpers are known in the art as a way to minimize damage to a motor vehicle during a collision. The motor vehicle detects or anticipates an oncoming collision and triggers a mechanism to extend the bumper, thereby causing the bumper to absorb the initial impact of the collision. For example, U.S. Pat. No. 5,011,205 to Liu discloses a bumper mounted on two guide rods attached to driving pistons which move the bumper forward when the user applies a sudden and deep depression of the brake pedal. In this design the bumper is powered by the braking mechanism. 
         [0004]    In U.S. Pat. No. 4,518,183 to Lee a latch mechanism operated by a control console in the motor vehicle causes a spring to release thereby causing the bumper to move forward. An air bag also inflates upon extension of the bumper providing extra padding between the bumper and the body of the vehicle. A disadvantage of this design is that the extendable bumper is driven forward by an “explosive” discharge, which may be unsafe in situations where the control console mistakenly believes an impending collision is imminent. Moreover, mechanical failure or faulty control circuitry may cause the bumper to deploy and spring forward while the vehicle is stationary. 
         [0005]    It is an object of the present invention to address at least some of the above disadvantages. 
       SUMMARY OF THE INVENTION 
       [0006]    In general terms, the present invention provides a drive system for various types of extendable vehicle bumpers that harnesses the kinetic energy of the moving vehicle by using the drive power of one or more wheels to extend forward the bumper. The widespread adoption of anti-lock braking systems has effectively eliminated the locking of vehicle wheels during panic stops, thereby making it more practical to use the drive power of the wheels. 
         [0007]    In one aspect of the invention, a system is provided for extending a bumper on a motor vehicle having driven wheels, the system comprising: (a) a drive connected to the wheels to derive power from rotation of the wheels: (b) an actuator for extending the bumper; and (c) a controller for connecting the actuator to the drive, thereby transferring power from the motor vehicle&#39;s rotating wheels to the actuator to effect deployment of the bumper. 
         [0008]    In one embodiment, the transmission drives both a shaft connected to the wheels and a generator that produces electric power. When the bumper is in its default unextended position the generator is not connected to any load. However, when bumper extension is to occur, a switch connects the generator to an electric motor that extends the bumper outwards. Once the bumper is fully extended, a bumper brake becomes engaged and holds the bumper in its extended position. This acts to resist bumper retraction upon collision, thereby forcing the bumper to absorb the initial impact of the collision. To return the bumper to normal position after extension, the bumper brake is disengaged and power is removed from the electric motor. A spring then returns the bumper to its default position. This embodiment is particularly advantageous since hybrid cars that employ regenerative braking are already equipped with a generator powered by the drive shaft of the vehicle, making adaptation for driving a bumper more viable. 
         [0009]    In an alternative embodiment, the system does not employ a generator and electric motor configuration, but instead uses a direct mechanical connection between the drive shaft of the wheels and the mechanism that extends the bumper forward. When bumper extension is desired, a clutch engages a spinning set of gears attached to the drive shaft, thereby transferring rotational power along a shaft to a rack and pinion that extends the bumper forward as the pinion rotates. 
         [0010]    Bumper extension is triggered by a processing unit, such as a microprocessor or microcontroller, located in the automobile. The role of the microcontroller is to decide whether a collision is imminent and whether bumper extension is desired. This decision may be based on a number of factors. For example, the microcontroller may utilize a radar signal that measures the distance between the automobile and an oncoming object. If the radar measurements suggest a collision is imminent and the microcontroller detects the brake is fully depressed by the driver, bumper extension is triggered. It will be appreciated, however, that different input measurements may be used by the microcontroller to determine when to trigger bumper extension. For example, the microcontroller may monitor the speed of the vehicle and be configured to prevent bumper extension below a minimum vehicle speed in order to reduce potential injury in collisions with pedestrians. As another example, the microcontroller may additionally receive inputs from a camera and/or an infrared detector. Based on the object&#39;s shape and/or object&#39;s temperature, the microcontroller may determine that even though a collision is imminent, bumper extension should not be triggered because there is a high probability that the object of collision is a pedestrian. The microcontroller may also monitor whether the ABS is engaged instead of or in addition to monitoring whether the brake pedal is fully depressed by the driver. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: 
           [0012]      FIG. 1  is a perspective view of the front end of a vehicle; 
           [0013]      FIG. 2  is a top schematic view of a first embodiment of a drive system for extending a bumper; 
           [0014]      FIG. 3  is the top schematic view shown in  FIG. 2  after bumper extension; 
           [0015]      FIG. 4  is a top schematic view of a second embodiment of a drive system for extending a bumper; and 
           [0016]      FIG. 5  is the top schematic view shown in  FIG. 4  after bumper extension. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring to  FIG. 1 , a vehicle V has a motor that drives a transmission  1 . A drive shaft  2  extends from the transmission  1  and turns the wheels  3 . In a first embodiment, shown in  FIGS. 2 and 3 , a set of gears  4  is attached to the drive shaft  2  and drives a generator  5 . A switch  9  acts to connect electrically the generator  5  to an electric motor  10 . The switch  9  is opened and closed by a microcontroller  6 , which receives inputs from a radar system  7  and brake system  8  installed on the vehicle V. The electric motor  10  drives a pinion  11  which engages a rack  12  on an extender arm cylinder  13 . The extender arm cylinder  13  is connected to the bumper  14 . The electric motor  10  also drives a bumper brake  16 , which engages the extender arm cylinder  13  when the bumper  14  is fully extended. A spring  15  acts to keep the bumper  14  in its default position during normal operation and to return the bumper  14  to its default position once bumper extension is no longer desired. Two electric motors are shown in  FIGS. 2  or  3 . It will be appreciated that a single electric motor may be instead be used, but that if two electric motors are used, appropriate provisions would need to be in place to ensure that each electric motor  10  drives its respective pinion  11  at substantially the same speed. 
         [0018]    In normal operation, when bumper extension is not desired, the switch  9  is open and the generator  5  has no load. The set of gears  4  turn with the drive shaft  2  and drive the generator  5 ; however, no electric current is drawn. The microcontroller  6  continually receives inputs from the vehicle&#39;s radar system  7  and brake system  8 . The microcontroller  6  processes this information and determines if a collision is imminent. For example, a collision is deemed imminent if the sensor information from the radar system  7  suggests collision with an approaching object, and the information from the brake system  8  indicates the driver has fully depressed the brake pedal. It will be appreciated that other collision sensing algorithms may instead be employed. For example, additional microcontroller inputs (not shown), such as vehicle speed, external camera, and infrared detector may also or instead be used to determine whether bumper extension is desired. Bumper extension may not be desired, for example, if the oncoming object is a pedestrian. The microcontroller may also monitor whether the ABS is engaged instead or in addition to monitoring whether the brake pedal is fully depressed by the driver. 
         [0019]    Once the microcontroller  6  has deemed bumper extension is desired, it closes the switch  9  which connects electrically the generator  5  to the electric motor  10 . The electric motor  10  draws current from the generator  5  to turn the pinion  11  which engages the rack  12  in the extender arm cylinder  13 . As the pinion  11  turns, the bumper  14  moves forward. 
         [0020]    A spring  15  biases the bumper  14  to its default non-extended position, it will be appreciated that the motor  10  must have enough torque to overcome the force of the spring  15 , and that the generator  5  must be able to accommodate the current drawn by the motor  10  while extending the extender arm cylinder  13 . In particular, the generator/motor configuration must be selected such that the speed of the rotating drive shaft  2  will allow the generator  5  to generate enough power to ensure the motor  10  is able to fully extend the bumper before the rotating drive shaft  2  drops to too low of a rotation speed. 
         [0021]    Once the bumper is fully extended, the bumper brake  16  becomes engaged and holds the bumper  14  in its extended position. If a collision occurs, the bumper brake  16  acts to resist and control the speed of bumper refraction, thereby forcing the bumper  14  to absorb the initial impact of the collision. If a collision is avoided, the microcontroller  6  opens the switch  9 , and the motor  10  and bumper brake  16  are no longer powered. The force of the extended return spring  15  returns the bumper to its normal position. 
         [0022]    Advantageously, even if the microcontroller  6  were to malfunction and not open the switch  9 , once the vehicle V was close to a complete stop, the drive shaft  2  would no longer be turning fast enough to provide the current required to accommodate the motor  10  and bumper brake  16 . The motor  10  and bumper brake  16  would lose power, and the bumper would return to its normal position. Similarly, if the vehicle V were stationary, the bumper  14  could never accidentally extend since the generator  5  would not be powered. 
         [0023]    It will be appreciated that alternate configurations may be utilized. For example, the brake  16  may be normally engaged with the arm  13  and be released during deployment of the bumper  14 . Similarly, the rack and pinion drive may be replaced with another mechanical linear drive, and the drive may be reversible to effect retraction, thereby supplementing or replacing the return spring  15 . 
         [0024]    Referring now to  FIGS. 4 and 5 , an alternative embodiment of the invention is shown in which like components are denoted by like reference numerals with a suffix ‘a’ added for clarity. Instead of the generator and electric motor configuration described above in this embodiment there is a direct mechanical connection between the drive shaft of the wheels and the mechanism that extends the bumper forward. A clutch  17  is used to engage the rotating gears  4   a  and transfer power via a shaft  18  to turn the pinion  11   a.    
         [0025]    In normal operation, when bumper extension is not desired, the set of gears  4   a  rotate with the drive shaft  2   a , but do not engage shaft  18 . Once bumper extension is triggered by the microcontroller  6   a , the clutch  17  engages the rotating gears  4   a  attached to the drive shaft  2   a  thereby transferring power via the shaft  18  to turn the pinion  11   a,  which engages the rack  12   a  in the extender arm cylinder  13   a . As the pinion  11   a  turns, the bumper  14   a  moves forward. Additionally, a transmission  19  may also be used to adjust the gear ratios between the gears  4   a  attached to the drive shaft  2   a  and the pinion  11   a  engaging the rack  12   a . Once the bumper  14   a  is fully extended, the microcontroller  6   a  causes the bumper brake  16   a  to become engaged and hold the bumper  14   a  in its extended position. The bumper brake  16   a  can be powered by any means, but preferably also uses power derived from the drive shaft  2   a . All other aspects of this embodiment are the same as that described in the embodiment of  FIGS. 2 and 3  described above. 
         [0026]    As a further alternative, a hydraulic drive system may be used to harness the power of drive shaft  2   a  and to drive bumper  14   a  forward. For example, a hydraulic link may be established between a pump driven by the gears  4   a  and the pinion  11   a  to drive the pinion  11   a  or drive the arm  13   a  directly. 
         [0027]    Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as identified in the claims appended hereto.