PATENT DOCUMENT

Publication Number: US-10343634-B1
Application Number: US-201715418208-A
Country: US
Kind Code: B1

Title: Extendable bumpers for vehicles

Abstract:
An apparatus includes a vehicle structure, a bumper, an elongate structural member, and an extension portion. The elongate structural member is able to crush longitudinally in response to application of force in a longitudinal direction. The extension portion is able to crush longitudinally in response to application of force in the longitudinal direction, is connected to the elongate structural member such that the elongate structural member and the extension portion support the bumper with respect to the vehicle structure, and is operable to move the bumper between an extended position and a retracted position with respect to the vehicle structure to change a distance between the bumper and the vehicle structure.

Claims:
What is claimed is: 
     
       1. An apparatus, comprising:
 a vehicle structure; 
 a bumper; 
 an elongate structural member that is oriented in a longitudinal direction between the vehicle structure and the bumper and is able to crush longitudinally in response to application of force in the longitudinal direction; 
 an extension portion that is able to crush longitudinally in response to application of force in the longitudinal direction, is connected to the elongate structural member such that the elongate structural member and the extension portion support the bumper with respect to the vehicle structure, and is operable to move the bumper between an extended position and a retracted position with respect to the vehicle structure to change a distance between the bumper and the vehicle structure; and 
 a locking mechanism that engages an end portion of the elongate structural member and an end portion of the extension portion in the extended position to restrain relative movement of the elongate structural member and the extension portion. 
 
     
     
       2. The apparatus of  claim 1 , wherein the elongate structural member and the extension portion are longitudinally aligned in the extended position. 
     
     
       3. The apparatus of  claim 1 , wherein the extension portion pivots during movement between the extended position and the retracted position while the elongate structural member remains oriented in the longitudinal direction in the extended position and the retracted position. 
     
     
       4. The apparatus of  claim 1 , wherein the extension portion includes an extension block that is pivotally connected to the elongate structural member, the extension portion is longitudinally aligned with the elongate structural member in the extended position, and the elongate structural member remains oriented in the longitudinal direction in the extended position and the retracted position. 
     
     
       5. The apparatus of  claim 1 , wherein the extension portion is movable laterally relative to the elongate structural member. 
     
     
       6. The apparatus of  claim 1 , wherein the extension portion is laterally adjacent to the elongate structural member in the retracted position and the extension portion is longitudinally aligned with the elongate structural member in the extended position. 
     
     
       7. The apparatus of  claim 1 , wherein the locking mechanism includes a first locking structure, a second locking structure, and an actuator, wherein the first locking structure and the second locking structure are each connected to one of the end portion of the extension portion or the end portion of the elongate structural member, wherein the first locking structure includes radially outwardly extending projections, the second locking structure includes radially inwardly extending projections, and relative rotation of the first locking structure and the second locking structure by the actuator moves the locking mechanism between an unlocked position, in which the first locking structure is disengaged from the second locking structure and a locked position, first locking structure is engaged with the second locking structure. 
     
     
       8. The apparatus of  claim 1 , further comprising:
 a scissor mechanism connected to the elongate structural member and the extension portion, the scissor mechanism including a first beam and a second beam that are arranged in an X-shaped configuration and are connected by a pivot joint; and 
 an actuator connected to the scissor mechanism to cause movement of the bumper between the extended position and the retracted position. 
 
     
     
       9. The apparatus of  claim 1 , further comprising:
 a crank that causes the extension portion to pivot relative to the elongate structural member such that the extension portion is longitudinally aligned with the elongate structural member when the bumper is in the extended position while the elongate structural member remains oriented in the longitudinal direction in the extended position and the retracted position. 
 
     
     
       10. The apparatus of  claim 1 , further comprising:
 an actuator assembly that extends between the vehicle structure and the bumper along an axis that extends in the longitudinal direction, wherein the actuator assembly is operable to move the bumper longitudinally with respect to the vehicle structure between the extend position and the retracted positions and is operable to pivot the extension portion around the axis such that the extension portion is longitudinally aligned with the elongate structural member in the extended position. 
 
     
     
       11. An apparatus, comprising:
 a vehicle structure; 
 a bumper; 
 an elongate structural member that is oriented in a longitudinal direction between the vehicle structure and the bumper and is able to crush longitudinally in response to application of force in the longitudinal direction; and 
 an extension portion that is able to crush longitudinally in response to application of force in the longitudinal direction, is connected to the elongate structural member such that the elongate structural member and the extension portion support the bumper with respect to the vehicle structure, and is operable to move the bumper between an extended position and a retracted position with respect to the vehicle structure to change a distance between the bumper and the vehicle structure, 
 wherein the extension portion is longitudinally aligned with the elongate structural member in the extended position and the retracted position, the extension portion is disposed within a hollow interior of the elongate structural member in the retracted position, the extension portion is movable out of the hollow interior of the elongate structural member to define an intermediate position, and the extension portion is rotatable with respect to the elongate structural member to move from the intermediate position to the extended position, wherein rotation of the extension portion with respect to the elongate structural member allows engagement of end surfaces of the extension portion with end surfaces of the longitudinal structural member to restrain movement from the extended position toward the retracted position. 
 
     
     
       12. The apparatus of  claim 1 , wherein the extension portion includes a piston and a cylinder, wherein the cylinder is disposed within the elongate structural member and is operable to move the piston with respect to the cylinder to cause movement of the bumper between the extended position and the retracted position. 
     
     
       13. An apparatus, comprising:
 a vehicle structure; 
 a bumper; 
 an elongate structural member that is able to crush longitudinally in response to application of force in a longitudinal direction; and 
 an extension portion that is able to crush longitudinally in response to application of force in the longitudinal direction, is connected to the elongate structural member such that the elongate structural member and the extension portion support the bumper with respect to the vehicle structure, and is operable to move the bumper between an extended position and a retracted position with respect to the vehicle structure to change a distance between the bumper and the vehicle structure; 
 an extension assembly that includes a first plurality of cam discs that are connected to the elongate structural member and a second plurality of cam discs that are connected to the extension portion wherein relative rotation of the first plurality of cam discs and the second plurality of cam discs causes movement of the bumper between the extended position and the retracted position; and 
 an actuator for causing relative rotation of the first plurality of cam discs and the second plurality of cam discs. 
 
     
     
       14. The apparatus of  claim 13 , wherein the first plurality of cam discs and the second plurality of cam discs each include waved discs that define crests and troughs. 
     
     
       15. The apparatus of  claim 13 , wherein the first plurality of cam discs rotates in unison with the elongate structural member and the second plurality of cam discs rotates in unison with the extension portion. 
     
     
       16. The apparatus of  claim 13 , wherein the first plurality of cam discs and the second plurality of cam discs define an axial cam stack that expands and contracts an axial dimension in response to rotation of the second plurality of cam discs with respect to the first plurality of cam discs. 
     
     
       17. The apparatus of  claim 11 , wherein the elongate structural member has a rectangular cross-section and the extension portion has a rectangular cross-section. 
     
     
       18. The apparatus of  claim 11 , wherein the elongate structural member and the extension portion each extend in the longitudinal direction in the extended position and the retracted position. 
     
     
       19. An apparatus, comprising:
 a vehicle structure; 
 a bumper; 
 an elongate structural member that is oriented in a longitudinal direction between the vehicle structure and the bumper and is able to crush longitudinally in response to application of force in the longitudinal direction; and 
 an extension portion that is able to crush longitudinally in response to application of force in the longitudinal direction, is connected to the elongate structural member such that the elongate structural member and the extension portion support the bumper with respect to the vehicle structure, and is operable to move the bumper between an extended position and a retracted position with respect to the vehicle structure to change a distance between the bumper and the vehicle structure, 
 wherein the extension portion includes a first pivot arm that is pivotally connected to the elongate structural member, the extension portion includes a second pivot arm that is pivotally connected to the elongate structural member, and the extension portion moves the bumper between the extended position and the retracted position by pivoting of the first pivot arm and the second pivot arm relative to the elongate structure member while the elongate structural member remains oriented in the longitudinal direction. 
 
     
     
       20. The apparatus of  claim 19 , further comprising:
 an actuator; and 
 a lead screw that is driven by the actuator and connected to the first pivot arm and the second pivot arm to cause pivoting of the first pivot arm and the second pivot arm.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/287,499, filed on Jan. 27, 2016, the content of which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     FIELD 
     The disclosure relates generally to the field of vehicle body structures. 
     BACKGROUND 
     In the automotive field, bumpers are vehicle structures that are typically positioned at the front and rear of the vehicle. Functions performed by bumpers include preventing damage to other portions of the vehicle during a low-speed collision, absorbing energy during higher speed collisions, and reducing the extent of height mismatch between vehicles of different sizes. 
     Bumpers often protrude longitudinally forward with respect to other vehicle structures such as body panels, or longitudinally rearward of other vehicle structures. In the event of a collision at the front or rear of a vehicle, the bumper is often the first part of the vehicle that is struck. A number of vehicle bumper structures have been utilized. A simple design includes a laterally extending metal beam that is supported forward of other vehicle structures by two or more support structures. Many modern designs include a plastic bumper cover that conceals an underlying bumper structure that is designed to absorb impact by crushing, such as a cellular structure formed from plastic. 
     SUMMARY 
     One aspect of the disclosure is an apparatus that includes a vehicle structure, a bumper, an elongate structural member, and an extension portion. The elongate structural member is able to crush longitudinally in response to application of force in a longitudinal direction. The extension portion is able to crush longitudinally in response to application of force in the longitudinal direction, is connected to the elongate structural member such that the elongate structural member and the extension portion support the bumper with respect to the vehicle structure, and is operable to move the bumper between an extended position and a retracted position with respect to the vehicle structure to change a distance between the bumper and the vehicle structure. 
     Another aspect of the disclosed embodiments is an apparatus that includes a vehicle structure, a bumper, a first side rail, and an extension assembly. The first side rail extends longitudinally and is located between the vehicle structure and the bumper. The extension assembly is connected to the first side rail to support the bumper with respect to the vehicle structure and is operable to move the bumper between an extended position and a retracted position with respect to the vehicle structure to change a distance between the bumper and the vehicle structure. The extension assembly includes a piston and a cylinder, and the cylinder is operable to move the piston with respect to the cylinder to cause movement of the bumper between the extended position and the retracted position. 
     Another aspect of the disclosed embodiments is an apparatus that includes a bumper, a vehicle structure that supports the bumper, a crush member that is configured to resist movement of the bumper toward the vehicle structure and absorb energy by crushing, and a connecting portion that connects the bumper to the crush member to allow transmission of force from the bumper to the crush member. 
     Another aspect of the disclosed embodiments is an apparatus that includes a vehicle structure, a bumper that is supported by the vehicle structure, and a crush member that is configured to absorb energy that is applied to the bumper by expelling a crush material from inside the crush member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view illustration showing an extendable bumper system according to a first example in a retracted position. 
         FIG. 2  is a top view illustration showing the extendable bumper system according to the first example in the retracted position. 
         FIG. 3  is a side view illustration showing the extendable bumper system according to the first example in an extended position. 
         FIG. 4  is a top view illustration showing the extendable bumper system according to the first example in the extended position. 
         FIG. 5  is a top view illustration showing an extendable bumper system according to a second example in a retracted position. 
         FIG. 6  is a top view illustration showing the extendable bumper system according to the second example in an extended position. 
         FIG. 7  is a top view illustration showing the extendable bumper system according to the second example in a crushed condition. 
         FIG. 8  is a perspective view illustration showing the extendable bumper system according to the second example in a retracted condition. 
         FIG. 9  is a top view illustration showing an extendable bumper system according to a third example in a retracted position. 
         FIG. 10  is a top view illustration showing the extendable bumper system according to the third example in an intermediate position. 
         FIG. 11  is a top view illustration showing the extendable bumper system according to the third example in an extended position. 
         FIG. 12  is a perspective view illustration showing the extendable bumper system according to the third example including a locking mechanism in an unlocked position. 
         FIG. 13  is a perspective view illustration showing the extendable bumper system according to the third example including a locking mechanism in a locked position. 
         FIG. 14  is a perspective view illustration showing an extendable bumper system according to a fourth example. 
         FIG. 15  is a top cross-sectional view illustration showing the extendable bumper system according to the fourth example in a retracted position. 
         FIG. 16  is a top cross-sectional view illustration showing the extendable bumper system according to the fourth example in an extended position. 
         FIG. 17  is a perspective view illustration showing the extendable bumper system according to the fourth example in the extended position. 
         FIG. 18  is a top view illustration showing an extendable bumper system according to a fifth example in a retracted position. 
         FIG. 19  is a top view illustration showing the extendable bumper system according to the fifth example in an intermediate position. 
         FIG. 20  is a top view illustration showing the extendable bumper system according to the fifth example in an extended position prior to engagement of a locking mechanism. 
         FIG. 21  is a top view illustration showing the extendable bumper system according to the fifth example in the extended position subsequent to engagement of the locking mechanism. 
         FIG. 22  is a perspective view illustration showing a portion of the extendable bumper system according to the fifth example. 
         FIG. 23  is a perspective view illustration showing a portion of the extendable bumper system according to the fifth example. 
         FIG. 24  is a top view illustration showing an extendable bumper system according to a sixth example in a retracted position. 
         FIG. 25  is a top view illustration showing the extendable bumper system according to the sixth example in an extended position prior to engagement of a locking mechanism. 
         FIG. 26  is a top view illustration showing the extendable bumper system according to the sixth example in the extended position subsequent to engagement of the locking mechanism. 
         FIG. 27A  is a perspective view illustration showing a locking mechanism in an unlocked position. 
         FIG. 27B  is a perspective view illustration showing a locking mechanism in a locked position. 
         FIG. 28  is a top cross-sectional view illustration showing a collapsible beam structure for an extendable bumper system. 
         FIG. 29  is a top view illustration showing an extendable bumper system according to a seventh example in a retracted position. 
         FIG. 30  is a top view illustration showing the extendable bumper system according to the seventh example in a first intermediate position. 
         FIG. 31  is a top view illustration showing the extendable bumper system according to the seventh example in a second intermediate position. 
         FIG. 32  is a top view illustration showing the extendable bumper system according to the seventh example in an extended position. 
         FIG. 33  is a top view illustration showing an extendable bumper system according to an eighth example in a retracted position. 
         FIG. 34  is a top view illustration showing the extendable bumper system according to the eighth example in an extended position. 
         FIG. 35  is a perspective view illustration showing an extendable bumper system according to a ninth example in a retracted position. 
         FIG. 36  is a perspective view illustration showing the extendable bumper system according to the ninth example in an intermediate position. 
         FIG. 37  is a perspective view illustration showing the extendable bumper system according to the ninth example in an extended position. 
         FIG. 38  is a top view illustration showing an extendable bumper system according to a tenth example in a retracted position. 
         FIG. 39  is a top view illustration showing the extendable bumper system according to the tenth example in an extended position. 
         FIG. 40  is a top view illustration showing the extendable bumper system according to the tenth example in a collapsed condition. 
         FIG. 41  is a top view illustration showing an extendable bumper system according to an eleventh example in a retracted position. 
         FIG. 42  is a top view illustration showing the extendable bumper system according to the eleventh example in an extended position. 
         FIG. 43  is a top cross-sectional view illustration showing an extendable bumper system according to a twelfth example in a retracted position. 
         FIG. 44  is a top cross-sectional view illustration showing the extendable bumper system according to the twelfth example in an extended position. 
         FIG. 45  is a top view illustration showing an extendable bumper system according to a thirteenth example in a retracted position. 
         FIG. 46  is a top view illustration showing the extendable bumper system according to the thirteenth example in an extended position. 
         FIG. 47  is a top view illustration showing the extendable bumper system according to the thirteenth example in a collapsed condition. 
         FIG. 48  is a side view illustration showing a bumper system according to a fourteenth example in a non-collapsed condition. 
         FIG. 49  is a side view illustration showing the bumper system according to the fourteenth example in a collapsed condition. 
         FIG. 50  is a side view illustration showing a bumper system according to a fifteenth example in a non-collapsed condition. 
         FIG. 51  is a side view illustration showing the bumper system according to the fifteenth example in a collapsed condition. 
         FIG. 52  is a top view illustration showing an extendable bumper system according to a sixteenth example in a retracted position. 
         FIG. 53  is a top view illustration showing the extendable bumper system according to the sixteenth example in an extended position. 
         FIG. 54  is a top view illustration showing an extendable bumper system according to a seventeenth example in a retracted position. 
         FIG. 55  is a top view illustration showing the extendable bumper system according to the seventeenth example in an extended position. 
         FIG. 56  is a top view illustration showing an extendable bumper system according to an eighteenth example in a retracted position. 
         FIG. 57  is a top view illustration showing the extendable bumper system according to the eighteenth example in an extended position. 
         FIG. 58  is a side view illustration showing an extendable bumper system according to a nineteenth example in a retracted position. 
         FIG. 59  is a side view illustration showing the extendable bumper system according to the nineteenth example in an extended position. 
         FIG. 60  is a side view illustration showing an extendable bumper system according to a twentieth example in an extended position. 
         FIG. 61  is a side view illustration showing the extendable bumper system according to the eighteenth example in a retracted position. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to extendable bumper systems for vehicles. The extendable bumper systems described herein are configured to move one or both of the front and rear bumpers of a vehicle between a retracted position and an extended position, with the overall length of the vehicle being increased when the bumpers are in the extended position as compared to the retracted position. In some implementations, the extendable bumper systems also include crushable members that absorb energy during an impact. 
       FIGS. 1-4  show an extendable bumper system  1000  for a vehicle that includes a vehicle structure  1002  and a body portion  1004 . The vehicle structure  1002  in this example can be an internal structural member of the vehicle that supports the body portion  1004  and can support other portions of the vehicle such as suspension components and drivetrain components. As examples, the vehicle structure  1002  can be all of or a portion of a frame, a subframe, a unibody, or a monocoque. The body portion  1004  can be an external panel of the vehicle. The body portion  1004  can be a unitary part or can be an assembly of multiple parts. In the illustrated example, the body portion  1004  is positioned at the longitudinal front of the vehicle. 
     At least a portion of the extendable bumper system  1000  is able to move between a retracted position ( FIGS. 1-2 ) and an extended position ( FIGS. 3-4 ). For example, the extendable bumper system  1000  includes a bumper  1006 . The bumper  1006  is an elongate structure that extends laterally across a majority of a width of the vehicle. In the illustrated example, the body portion has a front surface  1005 , and the bumper has a front surface  1007 . In the retracted position, the front surface  1007  of the bumper  1006  is substantially aligned with the front surface  1005  of the body portion  1004 . In the extended position, the bumper  1006  has moved longitudinally forward with respect to the body portion  1004  such that the front surface  1007  of the bumper  1006  is disposed longitudinally forward of the front surface  1005  of the body portion  1004 , and the front surface  1007  of the bumper  1006  is no longer aligned with the front surface  1005  of the body portion  1004 . 
     To support the bumper  1006 , the extendable bumper system  1000  includes a first side rail  1008  and a second side rail  1010  that are spaced laterally with respect to one another. The first side rail  1008  and the second side rail  1010  are each elongate structural members that are able to crush longitudinally in response to application of force in the longitudinal direction, such as in response to an impact. For example, the first side rail and the second side rail may be elongate beams or frame rails that extend in the longitudinal direction of the vehicle from the vehicle structure  1002  toward the bumper  1006 . The first side rail  1008  and the second side rail  1010  can be made of any suitable material. As one example, the first side rail  1008  and the second side rail  1010  may each be fabricated from steel. As another example, the first side rail  1008  and the second side rail  1010  may each be fabricated from aluminum. In some implementations the first side rail  1008  and the second side rail  1010  are hollow members, such as tubular structures or extruded structures with one or more internal cavities that extend longitudinally through them. The first side rail  1008  and the second side rail  1010  may be configured to absorb energy during an impact, such as by crushing such that their respective longitudinal lengths are decreased during the impact. 
     To move the bumper  1006  between the retracted position and the extended position, the extendable bumper system  1000  includes a first extension portion  1012  and a second extension portion  1014 . The first extension portion  1012  is connected to the first side rail  1008  and to the bumper  1006 . The second extension portion  1014  is connected to the second side rail  1010  and to the bumper  1006 . The first extension portion  1012  and the second extension portion  1014  are connected to the bumper  1006  at laterally spaced locations, such as by being positioned adjacent to respective lateral ends of the bumper  1006 . 
     In the illustrated example, the first extension portion  1012  and the second extension portion  1014  each have a lengthwise (i.e., longitudinal) overlap with respect to the first side rail  1008  and the second side rail  1010 , respectively, in the retracted position. The first extension portion  1012  and the second extension portion  1014  move with respect to the first side rail  1008  and the second side rail  1010  toward the extended position in a manner that reduces the extent of the lengthwise overlap of the first and second extension portions  1012 ,  1014  with respect to the first and second side rails  1008 ,  1010 . This causes an increase in the overall effective length of the extendable bumper system  1000 . 
     To allow for lengthwise overlap and longitudinal motion, the first extension portion  1012  and the second extension portion  1014  can be mounted to the first side rail  1008  and the second side rail  1010  such that they are longitudinally slidable. Suitable structures include, as examples, telescopically-related beams and side-by-side beams that are connected by sliding bearings. Additional examples of suitable structures will be discussed herein. 
     In order to cause movement of the bumper  1006  between the retracted position and the extended position, the first extension portion  1012  and the second extension portion  1014  can each include an actuator. Suitable actuators include electric motors, pneumatic piston-cylinder devices, and hydraulic piston-cylinder devices. Operation of such actuators can be performed by incorporating the extendable bumper system  1000  in a system that includes an electronic control unit (not shown). The electronic control unit can control operation of the extendable bumper system  1000  using one or more operating methods. In such implementations, for example, the electronic control unit can cause movement of the bumper  1006  between the retracted and extended positions in response to a predetermined criterion being satisfied. As one example, the electronic control unit can cause the bumper  1006  to be moved from the retracted position to the extended position when the vehicle is started and can cause the bumper  1006  to return to the retracted position when the vehicle is stopped. As another example, the electronic control unit can cause the bumper  1006  to move from the retracted position to the extended position when a speed of the vehicle exceeds a threshold speed and can cause the bumper  1006  to return to the retracted position when the speed of the vehicle drops below the threshold speed. As another example, the electronic control unit can cause the bumper  1006  to move from the retracted position to the extended position in response to detecting an imminent collision. 
     The extendable bumper system  1000  may include a locking mechanism that is operable, when engaged, to prevent movement of first and second extension portions  1012 ,  1014  relative to the first and second side rails  1008 ,  1010  from the extended position to the retracted position. As one example, mechanical means such as a pin that is associated with an actuator can be incorporated in the first and second extension portions  1012 ,  1014 . As another example, the locking mechanism can be incorporated in the actuator that is included in or associated with the first and second extension portions  1012 ,  1014 , such as structures or configurations that prevent back-driving of the actuator. 
     Additional implementations will be described herein that are similar to the extendable bumper system  1000  in structure and operation, except as otherwise noted. 
       FIGS. 5-8  show an extendable bumper system  5000  in which a bumper  5006  is supported with respect to a vehicle structure  5002  by a first side rail  5008 , a second side rail  5010 , a first extension portion  5012 , and a second extension portion  5014 . The extendable bumper system  5000  is movable between a retracted position ( FIG. 5 ) and an extended position ( FIG. 6 ). During an impact, portions of the first side rail  5008 , the second side rail  5010 , the first extension portion  5012 , and the second extension portion  5014  are crushable such that they collapse the overall length of the extendable bumper system  5000  relative to the extended position to define a collapsed condition ( FIG. 7 ) for the extendable bumper system  5000 . 
     The first extension portion  5012  and the second extension portion  5014  are similar to one another and will be described together with reference to the second extension portion  5014 . As best seen in  FIG. 8 , the second extension portion  5014  includes a first pivot arm  5016  and a second pivot arm  5018 . The first pivot arm  5016  extends from a first pivot joint  5020  to a second pivot joint  5021 . The second pivot arm  5018  extends from a third pivot joint  5022  to a fourth pivot joint  5023 . The first pivot arm  5016  and the second pivot arm  5018  are each pivotally connected to the second side rail  5010  by the first pivot joint  5020  and the third pivot joint  5022 , respectively. The first pivot joint  5020  and the third pivot joint  5022  may be disposed on opposite sides of the second side rail  5010 , such as on an inboard side and an outboard side of the second side rail  5010 , respectively. 
     The first pivot joint  5020  and the second pivot joint  5021  can each be connected, either directly or indirectly, to an actuator. In the illustrated example, an actuator is provided in the form of an electric motor  5024  that is operable to rotate a lead screw  5026  in both clockwise and counter-clockwise directions. To connect the first pivot arm  5016  and the second pivot arm  5018  to the lead screw  5026 , the second pivot joint  5021  and the fourth pivot joint  5023  can each incorporate a threaded connection to the lead screw  5026 . The directions of movement of the second pivot joint  5021  and the fourth pivot joint  5023  in response to rotation of the lead screw  5026  will drive the second pivot joint  5021  and the fourth pivot joint  5023  either toward one another or away from one another instead of in the same direction. This can be accomplished, for example, by forming two different threaded areas on the lead screw  5026 , the first area having left-handed threads, and the second area having right-handed threads. Thus, when the electric motor  5024  rotates the lead screw  5026  in a first rotational direction, the second pivot joint  5021  and the fourth pivot joint  5023  are driven apart, which increases an angle formed between each of the first pivot arm  5016  and the second pivot arm  5018  with respect to the second side rail  5010  and moves the bumper  5006  toward the second side rail  5010  and into the retracted position. Conversely, when the electric motor  5024  drives the lead screw  5026  in a second rotational direction, the second pivot joint  5021  and the fourth pivot joint  5023  are driven together until the first pivot arm  5106  and the second pivot arm  5018  reach an orientation in which they are substantially parallel to the second side rail  5010 . This places the bumper  5006  in maximum extension relative to the second side rail  5010 , thereby defining the extended position for the extendable bumper system  5000 . 
     The first side rail  5008  and the second side rail  5010 , and the first pivot arm  5016  and the second pivot arm  5018 , can each be formed by structural members that are adapted to crush and shorten longitudinally during an impact. This allows the extendable bumper system  5000  to crush relative to the extended position of  FIG. 6  to the crushed condition of  FIG. 7  in response to an impact. By forming the first pivot arm  5016  and the second pivot arm  5018  from crushable structures in addition to forming the first and second side rails  5008 ,  5010  from crushable structures, the extent to which the extendable bumper system  5000  can be collapsed is increased. 
       FIGS. 9-13  show an extendable bumper system  9000 . The extendable bumper system  9000  includes a bumper  9006  that is supported with respect to a vehicle structure  9002  by a first side rail  9008  and a second side rail  9010 . In order to move the extendable bumper system  9000  between a retracted position ( FIG. 9 ), an intermediate position ( FIG. 10 ), and an extended position ( FIG. 11 ), the extendable bumper system  9000  includes a first extension portion  9012  and a second extension portion  9014 . 
     The first extension portion  9012  and the second extension portion  9014  are similar and will be described with reference to the first extension portion  9012 . The first extension portion  9012  includes an extension block  9028  that is connected to the first side rail  9008  by a pivot joint  9030 . When the extendable bumper system  9000  is in the retracted position, the extension block  9028  is positioned in a side-by-side relationship with respect to the first side rail  9008 . During movement of the extendable bumper system from the retracted position to the extended position, the extension block  9028  pivots with respect to the first side rail  9008  about the pivot joint  9030  until it is longitudinally aligned with the first side rail  9008 . In the illustrated example, movement from the retracted position to the extended position involves pivoting of the extension block  9028  through an angle of approximately 180 degrees about the pivot joint  9030 . 
     The extension block  9028  can be connected to the bumper  9006  by a bracket structure that includes an upper bracket portion  9032  and a lower bracket portion  9034 . The upper bracket portion  9032  is located above the extension block  9028 , and the lower bracket portion  9034  is located below the extension block  9028 . In order to connect the extension block  9028  to the upper and lower bracket portions  9032 ,  9034 , pins  9036  are formed on upper and lower surfaces of the extension block  9028 . The pins  9036  are received in tracks or slots  9038  that are formed in the upper and lower bracket portions  9032 ,  9034 . The geometric configuration of the slots  9038  is configured such that rotation of the extension block  9028  causes the first side rail  9008  to move longitudinally away from the bumper  9006  while the extension block  9028  rotates and the pins  9036  travel from a first end of the slot  9038  to a second end of the slot  9038 . In order to drive rotation of the extension block  9028 , an actuator can be connected to the extension block  9028 , such as an electric motor (not shown) that is directly or indirectly connected to the pins  9036  of the extension block  9028 . 
     As best seen in  FIGS. 12-13 , the extendable bumper system  9000  includes a locking mechanism  9040  that is movable between an unlocked position ( FIG. 12 ) and a locked position ( FIG. 13 ). 
     The locking mechanism  9040  includes one or more first dovetail blocks  9042  that are formed on the extension block  9028 , such as by extending outward from a side surface of the extension block  9028 . The locking mechanism  9040  also includes one or more second dovetail blocks  9044  that are formed on the first side rail  9008 . A slide block  9046  is connected to the second dovetail blocks  9044  with the second dovetail blocks  9044  disposed within a dovetail channel  9048  that is formed by the slide block  9046 . The dovetail channel  9048  extends in a first direction, and one more entry openings  9050  extend in a second direction that is transverse to the first direction, such that the entry openings  9050  provide access to the dovetail channel  9048 . The entry openings  9050  are aligned with the first dovetail blocks  9042  in the unlocked position, such that the first dovetail blocks  9042  are able to enter the dovetail channel  9048  through the entry openings  9050  when the extension block  9028  is pivoted toward the extended position. Thus, the slide block  9046  does not restrain the extension block  9028  from pivoting with respect to the first side rail  9008  when the locking mechanism  9040  is in the unlocked position. 
     In order to move the locking mechanism  9040  between the unlocked position and the locked position, an actuator  9052  is operatively connected to the slide block  9046 . The actuator  9052  may be, for example, a solenoid. The actuator is operable to move the slide block  9046  linearly, such that the second dovetail blocks  9044  move along the dovetail channel  9048  of the slide block  9046 . When the extension block  9028  is pivoted between the first side rail  9008  such that the first dovetail blocks  9042  enter the dovetail channel  9048 , the slide block  9046  can be moved by the actuator  9052  to move the locking mechanism  9040  to the locked position. As an example, movement from the unlocked position to the locked position can include moving linearly in the direction of the dovetail channel  9048 , such as downward. By moving the slide block  9046  linearly with respect to the first dovetail blocks  9042  and the second dovetail blocks  9044 , the entry openings  9050  are no longer in alignment with the first dovetail blocks  9042  when the locking mechanism  9040  is in the locked position. This prevents the extension block  9028  from pivoting with respect to the first side rail  9008  by engagement of the first dovetail blocks  9042  and the second dovetail blocks  9044  with the interior of the dovetail channel  9048  of the slide block  9046 . 
     When the slide block  9046  is in the locked position, a locking member  9054  can be in engagement with the lower bracket portion  9034 , such as being disposed in a slot or aperture. Engagement of the locking member  9054  with the lower bracket portion  9034  further restrains pivoting of the extension block  9028  with respect to the first side rail  9008 . As an example, the locking member  9054  can be a structure such as a protrusion, a pin, or a tab that extends downward from the remainder of the slide block  9046 . As another example, the locking member  9054  can be an end portion of the slide block  9046 . 
       FIGS. 14-17  show an extendable bumper system  14000  that includes a bumper  14006  that is movable between a retracted position ( FIG. 15 ) and an extended position ( FIG. 16 ) with respect to a vehicle structure (not shown). The description herein is made with respect to a first side rail  14008  and a first extension portion  14012 , but it should be understood that additional side rails and extension portions can be included to further support the bumper  14006 , such as a second side rail and a second extension portion. 
     The first side rail  14008  can be an elongate member that has a hollow interior  14060  that extends longitudinally through it. A first end of the first side rail  14008  can be in engagement with the first extension portion  14012 . As will be explained herein, one or more engaging members, such as radially-extending pins  14062 , can be formed on the first side rail  14008  for engagement with the first extension portion  14012  to allow movement of the first extension portion  14012  with respect to the first side rail  14008 . To support the bumper  14006  with respect to the first side rail  14008  during movement between the extended and retracted positions, a support structure  14064 , such as an elongate tube, can be formed on or connected to the bumper  14006  and disposed within the hollow interior  14060  of the first side rail  14008 , such that the first side rail  14008  engages and supports the support member  14064  and allows it to slide with respect to the first side rail  14008 . 
     The first extension portion  14012  includes a housing  14066 . The housing  14066  is connected to the bumper  14006  by a bearing ring  14068 . The bearing ring  14068  allows the housing  14066  to rotate on its longitudinal axis with respect to the bumper  14006 . The bearing ring  14068  can be rigidly connected to or formed integrally with the bumper  14006 . 
     In order to cause motion of the bumper  14006  in response to rotation of the housing  14066 , a helical track  14070  is defined inside the housing  14066 . As one example, the helical track  14070  could be formed as part of the housing  14066 . As another example, the helical track  14070  could be defined by an insert that is disposed within the housing  14066 . Because the first side rail  14008  and the bumper  14066  are restrained from rotating, rotation of the housing  14066  causes the bumper  14066  and the first extension portion  14012  to move longitudinally with respect to the first side rail  14008  as a result of engagement of the radially-extending pins  14062  of the first side rail  14008  with the helical track  14070 . 
     To drive rotation of the housing  14066  during movement of the bumper  14006  between the retracted position and the extended position, an actuator such as an electric motor  14072  can be provided as part of the extendable bumper system  14000 . For example, the electric motor  14072  could be mounted to the bumper  14006  with rotational force transferred from a rotational output of the electric motor  14072  to the housing  14066  by a pair of corresponding gears, such as a worm gear  14074  connected to the electric motor  14072  and a gear ring  14076  disposed on an exterior surface of the housing  14066 . 
     To resist inadvertent movement of the extendable bumper system  14000 , such as in response to an impact, corresponding sets of engagement features can be formed on the first side rail  14008  and the housing  14066 . As an example, slots  14078  are arrayed radially around one end of the first side rail  14088 . In the retracted position, the first side rail  14008  is disposed within the housing  14066  to a maximum extent, and the slots  14078  come into engagement with a first set of engagement structures, such as projections  14080  that are formed on or connected to the housing  14066 , and restrain axial motion of the housing  14066  with respect to the first side rail  14008 . In the extended position, the first side rail  14008  is at a minimum degree of insertion relative to the housing  14006 , and the slots  14078  are engaged by a second set of engaging structures, such as projections  14082  that are disposed at an outer end of the housing  14066  opposite the bumper  14006  and restrain axial motion of the housing  14066  with respect to the first side rail  14008 . 
       FIGS. 18-23  show an extendable bumper system  18000 . The extendable bumper system  18000  includes a bumper  18006  that is supported with respect to a vehicle structure  18002  for movement between a retracted position ( FIG. 18 ) and an extended position ( FIG. 21 ). The extendable bumper system  18000  includes one or more side rails, such as a first side rail  18008  and one or more extension portions, such as a first extension portion  18012 . In order to cause movement of the bumper  18006  between the retracted position and the extended position, the extendable bumper system  18000  can include one or more linear actuators, such as a first linear actuator  18090 . 
     In the retracted position, the first extension portion  18012  is disposed laterally adjacent to the first side rail  18088  in a side-by-side relationship, such that the first side rail  18008  occupies a majority of the distance between the vehicle structure  18002  and the bumper  18006 . In order to move the extendable bumper system  18000  toward the extended position, the bumper  18006  is moved longitudinally away from the vehicle structure  18002  by the linear actuator  18090  ( FIG. 19 ). In this position, there is no longer a lengthwise overlap of the first extension portion  18012  with respect to the first side rail  18008 . In addition, the distance between the vehicle structure  18002  and the bumper  18006  is greater than the distance between them in the extended position, as will be explained further herein. 
     In the extended position, the first extension portion  18012  is longitudinally aligned with the first side rail  18008 . Thus, in the event of an impact while the extendable bumper system  18000  is in the extended position, force from the impact is received at the bumper  18006  and transmitted through the first extension portion  18012  to the first side rail  18008 . During such an impact, both the first extension portion  18012  and the first side rail  18008  are able to crush to absorb energy from the impact. 
     In order to move the first extension portion  18012  into longitudinal alignment with the first side rail  18008 , the first extension portion  18012  is connected to the bumper  18006  by a sliding mount  18092  that is supported by the bumper  18006  and configured to slide laterally with respect to the bumper  18006  into and out of longitudinal alignment with the first side rail  18008 . The sliding mount  18092  can be disposed within tracks  18094  that are formed on the bumper  18006  or are connected to the bumper  18006 . Lateral movement of the sliding mount  18092  can be caused by an actuator assembly, such as an electric motor  18096  and a lead screw  18098  that are connected to the sliding mount  18092 . The actuator assembly may also provide a rotational input to the linear actuator  18090  to drive extension and retraction of the linear actuator  18090  using rotation of the lead screw  18098 . 
     Once the first extension portion  18012  is longitudinal alignment with the first side rail  18008  ( FIG. 20 ), the linear actuator  18090  retracts slightly to bring the first extension portion  18012  into engagement with the first side rail  18008  ( FIG. 21 ). In order to retain the engagement between the first side rail  18008  and the first extension portion  18012 , the extendable bumper system  18000  includes a locking assembly defined by a first locking structure  18100  that is provided on the first extension portion  18012  and a second locking structure  18102  that is provided on the first side rail  18008 . In the illustrated example, the first locking structure  18100  is a round plate-like member that has a plurality of outwardly-extending radial projections  18104 . The second locking structure  18102  is a round ring-like member that has a plurality of inwardly-extending radial projections  18106 . When the first extension portion  18102  moves into engagement with the first side rail  18008 , the first locking structure  18100  passes into the second locking structure  18102 , such that the outwardly-extending radial projections  18104  of the first locking structure  18100  move past the inwardly-extending radial projections  18106  of the second locking structure  18102 , for example, into an annular channel defined in the second locking structure  18102 . The inwardly-extending radial projections  18106  are then interlocked with the outwardly-extending radial projections  18104 , by relative rotation of the inwardly-extending radial projections  18106  and the outwardly-extending radial projections  18104 . For example, interlocking the inwardly-extending radial projections  18106  and the outwardly-extending radial projections  18104  can include rotating the inwardly-extending radial projections  18106  using a rotational actuator  18108 , which is operably connected to the second locking structure  18102  and may be disposed within the first side rail  18008 . This places the second locking structure  18102  in a locked condition with respect to the first locking structure  18100 , which prevents movement of the first extension portion  18012  toward the retracted position from the extended position. 
     In order to move the extendable bumper system  18000  from the extended position to the retracted position, the first locking structure  18100  and the second locking structure  18102  are moved to the unlocked condition, such as by rotating the second locking structure  18102  to disengage the inwardly-extending radial projections  18106  of the second locking structure  18102  from the outwardly-extending radial projections  18104  of the first locking structure  18100 . The linear actuator  18090  is then used to move the bumper  18006  away from the vehicle structure  18002 . The extension portion  18012  is then shifted laterally with respect to the bumper  18006  using the sliding mount  18092 , the electric motor  18096 , and the lead screw  18098 , until the first extension portion  18012  is no longer longitudinally aligned with the first side rail  18008 , and the bumper  18006  can be moved toward the retracted position without interference between the first side rail  18008  and the first extension portion  18012 . The linear actuator  18090  is then used to move the bumper  18006  toward the vehicle structure  18002  until the bumper  18006  is fully retracted, thereby establishing the retracted position of the extendable bumper system  18000 . 
       FIGS. 24-26  show an extendable bumper system  24000 . The extendable bumper system  24000  includes a bumper  24006  that is movable between a retracted position ( FIG. 24 ) and an extended position ( FIG. 25 ) with respect to a vehicle structure  24002 . The extendable bumper system  24000  includes a first side rail  24008  that is slidably connectable to a first extension portion  24012 . The extendable bumper system  24000  also includes a second side rail  24010  that is slidably connected to a second extension portion  24014 . The bumper  24006  is connected to the first extension portion  24012  and the second extension portion  24014  to allow movement of the bumper  24006  between the retracted and extended positions. 
     The extendable bumper system  24000  includes a scissor mechanism  24110  that is operable to cause movement of the bumper  24006  between the retracted and extended positions. The scissor mechanism  24110  includes a first beam  24112  and a second beam  24114 . The first beam  24112  and the second beam  24114  are arranged in an X-shaped configuration. The first beam  24112  is connected to the first extension portion by a first pivot joint  24116  and is connected to the second side rail  24010  by a first pivotable sliding joint  24118 . The second beam  24114  is connected to the first side rail  24008  by a first pivot joint  24120  and is connected to the second extension portion  24014  by a second pivotable sliding joint  24122 . 
     To cause motion of the scissor mechanism  24110 , a linear actuator  24122  is pivotally connected to each of the bumper  24006  and the first beam  24112 . Alternatively, the linear actuator  24122  could be connected to the vehicle structure  24002  instead of the bumper  24006 . Alternatively, the linear actuator  24122  could be connected to the second beam  24114  instead of to the first beam  24112 . Extension of the linear actuator  24122  causes the scissor mechanism  24110  to move the extendable bumper system  24000  from the retracted position toward the extended position. Retraction of the linear actuator  24122  causes the scissor mechanism  24110  to move the extendable bumper system  24000  from the extended position toward the retracted position. In one example, the linear actuator  24122  is a pneumatic or hydraulic piston-cylinder device. In another implementation, the actuator  24122  is an electrical actuator, such as an electric motor and lead screw combination. 
     In order to restrain the extendable bumper system  24000  from moving out of the extended position, the extendable bumper system  24000  can include one or more locking mechanisms. The illustrated example includes locking mechanisms that each include a lock pin  24124  and an actuator  24126 . As an example, the actuator  24126  can be a solenoid. In an unlocked position, the lock pins  24124  are connected to a respective one of the first extension portion  24012  and the second extension portion  24014 . 
     To establish the locked position ( FIG. 26 ), the actuators  24126  cause the lock pins to move into engagement with the first side rail  24008  and the second side rail  24010 , such as by passing through apertures formed in each of the first side rail  24008  and the second side rail  24010 . This places the lock pins  24124  into simultaneously engagement with a respective one of the first and second extension portions  24012 ,  24014 , as well as a respective one of the first and second side rails  24008 ,  24010 , which locks the position of the bumper  24006  with respect to the vehicle structure  24002 . 
       FIGS. 27A-27B  show an alternative implementation of the extendable bumper system  24000  in which the lock pin  24124  and the actuator  24126  are replaced by a locking assembly  27130 . The locking assembly  27130  is movable between an unlocked position ( FIG. 27A ) in which the second extension portion  24014  is not restrained from sliding with respect to the first extension portion  24010 , and a locked position ( FIG. 27B ) in which the second extension portion  24014  is restrained from moving with respect to the second side rail  24010 . 
     An end portion  27015  of the second extension portion  24014  has a circular outer periphery and a square inner periphery in which an end portion  27011  of the second side rail  24010  is disposed. A plurality of cylindrical apertures  27132  are formed through the end portion  27015  of the first extension portion  24014 . A corresponding plurality of cylindrical apertures  27134  are formed through the end portion  27011  of the first side rail  24010 . The apertures  27132 ,  27134  extend radially through the end portions  27015 ,  27011 , respectively. In the extended position of the extendable bumper system  24000 , the pluralities of apertures  27132 ,  27134  are aligned with each other. 
     In order to lock the second side rail  24010  with respect to the second extension portion  24014 , the locking assembly  27130  includes a plurality of pins  27136  that are each disposed within a respective one of the cylindrical apertures  27132  that are formed in the end portion  27015  of the second extension portion  24014 . The pins  27136  are able to move from a first position in which they are disposed within the cylindrical apertures  27132  of the end portion  27015  of the first extension portion and not in the cylindrical apertures  27134  of the end portion  27011  of the second side rail  24010 , to a second position in which the pins  27132  are disposed within the apertures  27132  and the apertures  27134 . When the pins  27136  are disposed in the second position, the pins  27136  engage both the second side rail  24010  and the second extension portion  24014   20104  prevent relative motion. 
     The locking assembly  27130  includes a collar  27138  that extends around the end portion  27015  of the second extension portion  24014  adjacent to the pins  27136 . An inner periphery of the collar  27138  includes pockets  27140  that deviate from a circular cross-section in order to allow the pins  27138  to extend outward from an outer periphery of the end portion  27015  of the second extension portion  24014 . Each of the pockets  27140  includes a ramp surface  27142 . The collar  27140  is rotatable such that the ramp surface  27142  of each of the pockets  27140  engages a respective one of the pins  27136  to cause it to slide inward toward the end portion  27011  of the second side rail  24010  until each of the pins  27136  is disposed at least partially within one of the apertures  27134  formed in the end portion  27011  of the second side rail  24010 . This places the locking assembly  27130  in the locked position. To locking assembly  27130  back to the unlocked position, the collar  27138  is located in the opposite direction, and the pins  27136  move radially outward under the influence of means such as a spring-biased until they are disposed within the pockets  27140  to a maximum extent and no longer partially disposed within the cylindrical apertures  27134  of the end portion  27011  of the second side rail  24010 . 
       FIG. 28  shows an extendable bumper system  28000  in which a bumper  28006  is supported by a first side rail  28008  and the first extension portion  28012 . The first extension portion  28012  includes an outer tube  28150  and an inner tube  28152 . At least part of the first side rail  28008  is receivable within the space between the outer tube  28150  and the inner tube  28152  during extension and is able to slide within this space with respect to the first extension portion  28008  toward and away from the bumper  28006  during extension and retraction of the extendable bumper system  28000 . In order to cause extension and retraction of the extendable bumper system  28000 , any type of actuator or actuator assembly can be used with the extendable bumper system  28000 , such as the actuators and actuator assemblies described herein with respect to other implementations. 
     The bumper  28006  is supported with respect to the first side rail  28008  by engagement of the outer tube  28150  and the inner tube  28152  with the first side rail  28008 . The bumper  28006  is further supported by a central support  28154  that is connected to the inner tube  28152  and extends into an interior space defined within the first side rail  28008  such that it engages internal surfaces of the first side rail  28008 . 
     The central support  28154  is configured to collapse into the inner tube  28152  during an impact. This prevents the central support  28154  from impeding full crushing of the first side rail  28008 . An end portion  28156  of the central support  28154  is disposed within a hollow interior  28158  of the inner tube  28152 . The end portion  28156  of the central support  28154  is connected to an interior surface of the inner tube  28152  by a plurality of welded fuses  28160  are configured to rigidly connect the central support  28154  to the inner tube  28152  during normal conditions, but to break during an impact. When the welded fuses  28160  break, the end portion  28156  of the central support  28154  is able to slide inward along the hollow interior  28158  of the inner tube  28152  toward the bumper  28006 . Since the central support  28154  is nested within the inner tube  28152  during an impact, it does not restrain crushing of the first side rail  28008 . 
     In addition to the central support  28154 , additional support can be provided, such as an outer support tube  28162  that is connected to an exterior surface of the outer tube  28150  of the first extension portion  28012  by welded fuses  28164 . During normal operation, the outer support  28162  engages an exterior surface of the first side rail  28008  to support the first side rail  28008 . During an impact, the welded fuses  28164  break and the outer support tube  28162  collapses by sliding onto the exterior of the outer tube  28152  toward the bumper  28006  and in the manner described with respect to the central support  28154 . 
       FIGS. 29-32  show an extendable bumper system  29000  that includes a bumper  29006  that is movable between a retracted position ( FIG. 29 ) and an extended position ( FIG. 32 ) with respect to a vehicle structure  29002 . To move the bumper  29006  between the retracted position and the extended position, the extendable bumper system  29000  can include a linear actuator assembly  29170  that is operable to move the bumper  29006  away from and toward the vehicle structure  29002 . 
     The extendable bumper system  29000  includes a first side rail  29008  and a first extension portion  29012 . The first side rail  29008  extends a majority of the distance between the bumper  29006  and the vehicle structure  29002  in the retracted position. In the retracted position, the first extension portion  29012  is disposed laterally adjacent to the first side rail  29008  and is not disposed between the first side rail  29008  and the bumper  29006 . As the extendable bumper system moves from the retract position to the extended position, the first extension portion  29012  is moved into longitudinal alignment with the first side rail  29008  by a crank  29172 . The crank  29172  is connected to the first extension portion  29012  by a pivotable sliding joint  29174 . The crank  29172  is connected to the first side rail  29008  by a pivot joint  29176 . The crank  29172  can also include an end portion  29178  that is opposite the pivotable sliding joint  29174  and is connectable to an actuator (not shown) that drives movement of the crank  29172  as the extendable bumper system  29000  moves between the retracted and extended positions. 
     The first extension portion  29012  is connected to the bumper  29006  by a pivot joint  29180  that allows the first extension portion  29012  to pivot through an angle of approximately 90 degrees between the retracted and extended positions. In the retracted position, a longitudinal axis of the first extension portion  29012  is disposed at a generally perpendicular angle with respect to the longitudinal axis of the first side rail  29008 . In the extended position, the first extension portion  29012  is rotated with respect to the bumper  29006  and the first side rail  29008 , such that the longitudinal axis of the first extension portion  29012  is substantially aligned with the longitudinal axis of the first side rail  29008 . 
     Moving the extendable bumper system  29000  from the retracted position toward the extended position can commence by moving the bumper  29006  away from the body structure  29002  using the linear actuator assembly  29170 . During movement to a first intermediate position ( FIG. 30 ), the crank  29172  pivots and slides with respect to the first extension portion  29012  at the pivotable sliding joint  29174 . During movement to the first intermediate position, the first extension portion  29012  does not rotate. During movement from the first intermediate position to the second intermediate position, the crank  29172  induces rotation of the first extension portion  29012  about the pivot joint  29180 . This pivots the first extension portion  29012  toward longitudinal alignment with the first side rail  29008 . 
     Once the first extension portion  29012  reaches longitudinal alignment with the first side rail  29008 , the linear actuator assembly  29170  can move the bumper  29006  slightly toward the vehicle structure  29002  in order to bring the first extension portion  29012  into engagement with the first side rail  29008 . This allows force to be transferred from the bumper  29006  through the first extension portion  29012  to the first side rail  29008  in the event of an impact. 
     Movement of the extendable bumper system  29000  back to the retracted position from the extended position is performed by reversing the process described for movement of the extendable bumper system  29000  from the retracted position to the extended position. 
       FIGS. 33-34  show an extendable bumper system  33000  that is movable between a retracted position ( FIG. 33 ) and an extended position ( FIG. 34 ). The extendable bumper system  33000  includes a bumper  33006  that is supported for movement with respect to a vehicle structure  33002 . In the retracted position, the first and second side rails  33008 ,  33010  extend between the vehicle structure  33002  and the bumper  33006 . In the extended position, the bumper  33006  is moved away from the vehicle structure  33002  and a first extension portion  33012  and a second extension portion  33014  are disposed between the first and second side rails  33008 ,  33010 , respectively. The first extension portion  33012  is connected to a first actuator assembly  33190 . The second extension portion  33014  is connected to a second actuator assembly  33192 . The first and second actuator assemblies  33190 ,  33192  are operable to move the bumper  33006  away from and toward the vehicle structure  33002 , as well as to move the first and second extension portions  33012 ,  33014  into and out of longitudinal alignment with the first side rail  33008  and the second side rail  33010 , respectively. 
     The first and second actuator assemblies  33190 ,  33192  each include a first portion  33194  and a second portion  33196 , with the first portions  33194  being connected to the vehicle structure  33002  and the second portions  33196  being connected to the bumper  33006 . The second portions  33196  are mounted to the bumper  33006  in a manner that permits rotation of the second portions  33196  around their respective longitudinal axes. The first portions  33194  are connected to the second portions  33196  by respective helical tracks  33198  such that rotation of the second portions  33196  with respect to the first portions  33194  causes longitudinal movement of the second portions  33196  with respect to the first portions  33194  to thereby cause longitudinal movement of the bumper  33006  with respect to the vehicle structure  33002  between the retracted and extended positions. To cause rotation of the second portions  33196 , each of the first and second actuator assemblies  33190 ,  33192  includes a respective rotary actuator  33200 , such as an electric motor. 
     The first actuator assembly  33190  and the second actuator assembly  33192  each include a radially-extending portion  33202  that is connected to their respective second portion  33196  adjacent to the bumper  33006 . The radially-extending portions  33202  of the first actuator assembly  33190  and the second actuator assembly  33192  are connected to the first extension portion  33012  and the second extension portion  33014 , respectively. Thus, as the second portions  33196  are rotated by the rotary actuators  33200  to extend and retract the extendable bumper  33006 , the first and second extension portions  33012 ,  33014  are moved along circular arcs that extend around the respective longitudinal axes of the second portions  33196  of the first actuator assembly  33190  and the second actuator assembly  33192 . Thus, when the extendable bumper system  33000  is in the retracted position, the first and second extension portions  33012 ,  33014  are disposed inboard of the first and second side rails  33008 ,  33010 . 
     As the extendable bumper system  33000  moves from the retracted position to the extended position, the first and second actuator assemblies  33190 ,  33192  cause the bumper  33006  to move longitudinally away from the vehicle structure  33002 , which creates a space between the first and second side rails  33008 ,  33010 , and the bumper  33006 . Simultaneously, the first and second extension portions  33012 ,  33014  rotate around the second portions  33196  until they reach the space that has been defined between the first and second side rails  33008 ,  33010  until the first and second extension portions  33012 ,  33014  are longitudinally aligned with the first and second side rails  33008 ,  33010  and thereby disposed between the first and second side rails  33008 ,  33010  and the bumper  33006 . 
     Moving the extendable bumper system  33000  from the extended position to the retracted position is performed by reversing the operations described for movement from the retracted position to the extended position. 
       FIGS. 35-37  show an extendable bumper system  35000 . The extendable bumper system  35000  includes a bumper  35006  that is supported for movement with respect to a vehicle structure  35002  by a first side rail  35008  and a first extension portion  35012 . The extendable bumper system  35000  is movable between a retracted position ( FIG. 35 ), and intermediate position ( FIG. 36 ), and an extended position ( FIG. 37 ). 
     The first side rail  35008  includes an end portion  35210  that is disposed within a hollow interior of the first extension portion  35012  in the retracted position. Extension of the extendable bumper system  35000  from the retracted position to the extended position is caused by a linear actuator  35212 . As an example, the linear actuator  35212  can be disposed within the hollow interiors of the first side rail  35008  and the first extension portion  35012 . As an alternative, the linear actuator  35212  could be disposed outside of the first side rail  35008  and the first extension portion  35012 . The linear actuator  35212  moves the bumper  35006  away from the vehicle structure  35002  until the end portion  35201  of the first side rail  35008  has moved out of the first extension portion  35012 , which places the extendable bumper system  35000  in the intermediate position. 
     In the intermediate position, the end portion  35210  of the first side rail  35008  is longitudinally spaced from a first pair of end surfaces  35214  and a second pair of end surfaces  35216  of the first extension portion  35012 . Since the first extension  35012  is not in engagement with the first side rail  35008  in the intermediate position, the first extension portion  35012  is free to rotate with respect to the first side rail  35008  and the bumper  35006  in response to a rotational force supplied by a rotational actuator  35218 . As an example, the rotational actuator  35218  can be supported by the bumper  35006  and operably connected to the first extension portion  35012 . 
     To move the extendable bumper system  35000  from the intermediate position to the extended position, the rotational actuator  35218  is utilized to rotate the first extension portion  35012  by approximately 90 degrees with respect to the bumper  35006  and the first side rail  35008 . In the illustrated implementation, the first side rail  35008  and the first extension portion  35012  have rectangular cross-sections that are complementary in size to one another, for example, such that the exterior surfaces of the first side rail  35008  fit closely with respect to the interior surfaces of the first extension portion  35012  when the first side rail  35008  is disposed within the first extension portion  35012  in the retracted position. Due to the rectangular cross-sections of the first side rail  35008  and the first extension portion  35012 , when the first extension portion  35012  is rotated by approximately 90 degrees, mechanical interference between the misaligned rectangular cross-sections of the first side rail  35008  and the first extension portion  35012  restrains the first side rail  35008  from retracting into the interior of the first extension portion  35012 . Thus, in the extended position, with the first extension portion  35012  rotated with respect to the first side rail  35008 , engagement of the first extension portion  35012  with the first side rail  35008  prevents movement from the extended position toward the retracted position. 
     To lock the first extension portion  35012  against rotation with respect to the first side rail  35008  in the extended position, the linear actuator  35212  is used to move the first extension portion  35012  toward the first side rail  35008 , such that they are engaged with one another, subsequent to rotation of the first extension portion  35012 . Rotation of the first extension portion  35012  with respect to the first side rail  35008  is restrained by engagement of the first pair of end surfaces  35214  with the exterior of the first side rail  35008 . The first pair of end surfaces  35214  extend longitudinally outward from the second pair of end surfaces  35216 . The first pair of end surfaces  35214  are defined on a pair of opposing sides of the rectangular cross-section of the first extension portion  35012 , while the second pair of end surfaces  35216  are formed on the other opposing sides of the rectangular cross-section of the first extension portion  35012 . Thus, longitudinal motion of the first extension portion  35012  with respect to the first side rail  35008  is restrained by engagement of the second pair of end surfaces  35216  with the end portion  35210  of the first side rail  35008 . At the same time, rotational motion of the first extension portion  35012  with respect to the first die rail  35008  is restrained by engagement of the first pair of end surfaces  35214  with the exterior of the end portion  35210  of the first side rail  35008 . 
     Movement of the extendable bumper system  35000  from the extended position toward the retracted position is performed in a manner opposite that described for movement from the retracted position to the extended position. 
       FIGS. 38-40  show an extendable bumper system  38000 . The extendable bumper system  38000  includes a bumper  38006  that is supported for movement with respect to a vehicle structure  38002  by a first extension portion  38012  and a second extension portion  38014 , as well as a first side rail  38008  and a second side rail  38010 . 
     The first extension portion  38012  and the second extension portion  38014  each include a cylinder  38220  and an associated piston  38222 . The cylinders  38220  can be, as examples, hydraulically actuated or pneumatically actuated cylinders. Actuation of the cylinders  38220  by fluid pressure is operable to move the pistons  38222  into and out of the cylinders  38220 . Thus, the extendable bumper system  38000  is movable from the retracted position to the extended position by applying fluid pressure to the cylinders  38220  to extend the pistons  38222  out of the cylinders  38220 , which moves the bumper  38006  away from the vehicle structure  38002 . 
     In the illustrated example, the cylinders  38220  are disposed within a hollow interior of the first side rail  38008  and the second side rail  38010 . The pistons  38222  are partially disposed and supported by the cylinders  38220  and are also connected to the bumper  38006 . In this manner, extension of the pistons  38222  out of the cylinders  38220  moves the bumper  38006  longitudinally away from the first side rail  38008  and the second side rail  38010 . 
     The cylinders  38220  are configured such that they do not interfere with crushing of the first side rail  38008  and the second side rail  38010  during an impact. To prevent interference, the longitudinal length of each of the cylinders  38220  is equal to or less than the expected length of the first side rail  38008  and the second side rail  38010  in a crushed condition ( FIG. 40 ). As an example, the cylinders  38220  can be sized such that their longitudinal length is approximately equal to the expected longitudinal length of each of the first side rail  38008  and a second side rail  38010  in the crushed condition. 
       FIGS. 41-42  show an extendable bumper system  41000 . The extendable bumper system  41000  includes a bumper  41006  that is supported for movement with respect to a vehicle structure  41002  between a retracted position ( FIG. 41 ) and an extended position ( FIG. 41 ). 
     The bumper  41006  is supported for movement with respect to the vehicle structure  41002  by the first side rail  41008  and the second side rail  41010  by a first X-shaped scissor assembly  41230  and a second X-shaped scissor assembly  41232 . The first X-shaped scissor assembly  41230  is positioned adjacent to the first side rail  41008  and the second X-shaped scissor assembly  41232  is positioned adjacent to the second side rail  41010 . Each of the first and second X-shaped scissor assemblies  41230 ,  41232  includes a first member  41234  and a second member  41236  that are connected to each other in an X-shaped configuration. The first members  41234  are each connected to the bumper  41006  by pivotable sliding joints  41238  and are connected to a cross member  41240  that extends between the first and second side rails  41008 ,  41010 , by pivot joints  41242 . The second members  41236  are connected to the bumper  41006  by pivot joints  41246  and are connected to the cross member  41240  by pivotable sliding joints  41244 . 
     To move the extendable bumper system  41000  between the retracted and extended positions, a linear actuator  41250  is positioned between the first and second X-shaped scissor assemblies  41230 ,  41232 . A first end of the linear actuator  41250  is connected to a central pivot joint  41252  at which the first and second members  41234 ,  41236  of the first X-shaped scissor assembly  41230  are pivotally connected. A second end of the linear actuator  41250  is connected to the second X-shaped scissor assembly  41232  at a central pivot joint  41254  at which the first and second members  41234 ,  41236  of the second X-shaped scissor assembly  41232  are pivotally connected. 
     In order to move the extendable bumper assembly  41000  from the retracted position to the extended position, the linear actuator  41250  is cause to extend its overall length, which increases the distance between the central pivot joint  41252  of the first X-shaped scissor assembly  41230  and the second central pivot joint  41254  of the second X-shaped scissor assembly  41232 . This causes the ends of the first and second members,  41234  of the first and second X-shaped scissor assemblies  41230 ,  41232  to move closer together, which causes corresponding longitudinal movement of the bumper  41006  with respect to the vehicle structure  41002 . In addition to being supported by the first and second X-shaped scissor assemblies  41230 ,  41232 , the bumper  41006  can be further supported by telescopic supports  41256  that are connected to the bumper  41006  and telescopically related to each of the first side rail  41008  and the second side rail  41010 . 
     In the illustrated example, the linear actuator  41250  is a fluid operated cylinder, such as a hydraulically operated cylinder. In this implementation, the linear actuator  41250  is operable to resist movement of the bumper  41006  from the extended position toward the retracted position in the event of an impact at a controlled rate, such as by expelling fluid from the linear actuator  41250  using, for example, a bleeder valve. 
       FIGS. 43-44  show an extendable bumper system  43000 . The extendable bumper system  43000  includes a bumper  43006  that is supported for movement with respect to a vehicle structure  43002  between a retracted position ( FIG. 43 ) and an extended position ( FIG. 44 ). The extendable bumper system  43000  includes a first side rail  43008  that is connected to the vehicle structure  43002 , as well as a first extension portion  43012  that is connected to the bumper  43006 . The first side rail  43008  and the first extension portion  43012  can each be tubular structures that are related to one another to allow extension and retraction by longitudinal sliding, such as by a telescopic relationship between the first side rail  43008  and the first extension portion  43012 . In the illustrated example, the first side rail  43008  and the first extension portion  43012  is telescopically disposed within the first side rail  43008 . 
     To cause movement of the extendable bumper system  43000  between the retracted and extended positions, the extendable bumper system  43000  includes an extension assembly  43260 . The extension assembly  43260  includes a support portion  43262 . The support portion  43262  can be a cylindrical member that is disposed within the first side rail  43008  and the first extension portion  43012 . The support portion  43262  can be rotatably connected to the vehicle structure  43002 , as well as to a rotational actuator  43264 , such as an electric motor that rotates the support portion  43262  around its longitudinal axis in order to cause extension and retraction of the extendable bumper system  43000 , as will be explained further herein. 
     The extension assembly  43260  includes an axial cam stack defined by a first plurality of cam discs  43266  and a second plurality of cam discs  43268 . The first plurality of cam discs  43266  and the second plurality of cam discs  43268  each include waved discs that define crests and troughs. The first plurality of cam discs  43266  is restrained from rotating, such as by a splined connection with respect to the first side rail  43008 . The second plurality of cam discs is connected to the support portion  43262 , such as by a splined connection, for rotation in unison with the support portion  43262  in response to rotational force supplied by the rotational actuator  43264 . 
     The first plurality of cam discs  43266  and the second plurality of cam discs  43268  define an axial cam stack that expands and contracts its axial dimension in response to rotation of the second plurality of cam discs  43268  with respect to the first plurality of cam discs  43266 . The first and second pluralities of cam discs  43266 ,  43268  are captured between an end portion  43270  of the first extension portion  43012  and an end portion  43272  of the first side rail  43008 . Thus, extension of the axial cam stack defined by the first and second pluralities of cam discs  43266 ,  43268  causes corresponding extension of the bumper  43006 , as the first and second pluralities of cam discs  43266 ,  43268  engage the end portions  43270 ,  43272  of the first extension portion  43012  and the first side rail  43008 . Extension of the axial cam stack is caused by alignment of the crests of the first pluralities of cam discs  43266  with the troughs of the second pluralities of cam discs  43268 . Retraction of the axial dimension of the axial cam stack is caused by alignment of the crests of the first pluralities of cam discs  43266  with the crests of the second pluralities of cam discs  43268 . 
     The extendable bumper system  43000  is moved from the retracted position to the extended position using the rotational actuator  43264  to rotate the support portion  43262 , which misaligns the crests and troughs of the first and second pluralities of cam discs  43266 ,  43268  with respect to one another to lengthen the axial cam stack and thereby force the first extension portion  43012  away from the first side rail  43008 . Movement of the extendable bumper system  43000  from the extended position to the retracted position is caused by an opposite rotation of the rotational actuator  43264  to shorten the axial cam stack defined by the first and second pluralities of cam discs  43266 ,  43268  and is assisted by a biasing means such as a tension spring  43276 . In the illustrated implementation, the tension spring  43276  is connected to the first extension portion  43012  and to the support portion  43262 , which urges the bumper  43006  toward the retracted position when the axial cam stack defined by the first and second pluralities of cam discs  43266 ,  43268  is shortened. 
       FIGS. 45-47  show an extendable bumper system  45000 . The extendable bumper system  45000  includes a bumper  45006  that is supported with respect to vehicle structure  45002  for movement between a retracted position ( FIG. 45 ) and an extended position ( FIG. 46 ). 
     The bumper  45006  is supported with respect to the vehicle structure  45002  by an extension assembly  45280 . The extension assembly  45280  includes a linear actuator  45282 . As an example, the linear actuator  45282  may be a fluid operated piston-cylinder combination, such as a hydraulic piston-cylinder combination or a pneumatic piston-cylinder combination. In the illustrated example, the linear actuator  45282  includes a first portion  45284  and a second portion  45286 . For example, the first portion  45284  can be a piston rod, and the second portion  45286  can be a body portion of the cylinder. The first portion  45284  is connected to a first pivot arm  45288  and a second pivot arm  45290  at a first pivot joint  45292 . The first pivot arm  45288  is connected to the vehicle structure by a second pivot joint  45294 . The second pivot arm  45290  is connected to the bumper  45006  by a third pivot joint  45296 . The second portion  45286  of the linear actuator  45282  is connected to a third pivot arm  45310  and a fourth pivot arm  45312  at a fourth pivot joint  45298 . The third pivot arm  45310  is connected to the vehicle structure  45002  at a fifth pivot joint  45300 . The fourth pivot arm  45312  is connected to the bumper  45006  at a sixth pivot joint  45302 . The second portion  45286  of the linear actuator  45282  is also connected to a fifth pivot arm  45314  and a sixth pivot arm  45316  at a seventh pivot joint  45304 . The fifth pivot arm  45314  is connected to the vehicle structure  45002  by an eighth pivot joint  45306 . The sixth pivot arm  45316  is connected to the bumper  45006  by a ninth pivot joint  45308 . 
     To move the extendable bumper system  45000  from the retracted position to the extended position, the linear actuator  45282  is lengthened by lateral extension of the first portion  45284  with respect to the second portion  45286 . This causes a corresponding increase in the longitudinal extension of the pivot arms  45288 ,  45290 ,  45310 ,  45312 ,  45314 ,  45316 . Movement from the extended position to the retracted position is caused by retracting the first portion  45284  of the linear actuator  45282  into the second portion  45286  in the transverse direction. 
     In the event of an impact, further longitudinal shortening of the pivot arms  45288 ,  45290 ,  45310 ,  45312 ,  45314 ,  45316  can be caused by further retracting the first portion  45284  of the linear actuator  45282  into the second portion  45286  relative to the retracted position. This further retraction of the second portion  45286  in the event of an impact can be performed at a controlled rate, such as by controlling the rate at which fluid is expelled from the linear actuator  45282  using means such as a bleeder valve in implementations where the linear actuator  45282  is a fluid operated piston-cylinder arrangement. Subsequent to an impact, the extendable bumper system  45000  is disposed in a crushed condition ( FIG. 47 ). 
       FIGS. 48-49  show a bumper system  48000 . The bumper system  48000  includes a bumper  48006  that is supported with respect to a vehicle structure  48002 . The bumper system  48000  includes a crush member  48320  that resists movement of the bumper  48006  from a non-collapsed condition ( FIG. 48 ) to a collapsed condition ( FIG. 49 ) in response to an impact, to allow absorption of energy by the crush member  48320 . In particular, the crush member  48320  is disposed internal to the vehicle structure  48002 , such as by location of the crush member  48320  in an internal space that is located inside the vehicle structure  48002 . The crush member  48320  is connected to the bumper  48006  in a manner that allows transmission of force from the bumper  48006  to the crush member  48320 . For example, the crush member  48320  may be connected to the bumper  48006  by a longitudinally extending connecting portion  48322 , such as a rod or a beam. During an impact, the crushable member  48320  is able to crush by a distance that is similar to a distance between a front face of the bumper  48006  and the vehicle structure  48002 . Thus, the bumper  48006  is able to collapse in a manner that allows it to travel the majority of the distance to the vehicle structure  48002 , without being restrained from doing so by presence of an element, such as the crushable member  48320  in between the bumper  48006  and the vehicle structure  48002 . 
       FIGS. 50-51  show a bumper system  50000  that includes a bumper  50006  that is supported with respect to a vehicle structure  50002 . The bumper  50006  includes a crushable member  50330  that has a crush material  50332  disposed inside of it. The crushable member  50330  may be, for example, disposed inside the bumper  50006 . The crush material  50332  is a material that can be expelled from the crushable member  50330 . As examples, the crush material  50332  could be a powder, a liquid, a gas, or a granular material. Prior to an impact, the crushable member  50330  may be sealed. Initially, the bumper system  50000  is disposed in a non-collapsed condition ( FIG. 50 ) in the event of an impact, the crushable member  50330  allows the crush material  50332  to be expelled from the interior of the crushable member  50330  such as by rupturing or by passing the material through a valve in response to the pressure applied to the crushable member  50330 . The crush material  50332  can be expelled in a controlled manner to allow energy to be absorbed by the crushable member  50330 , as it collapses as a result of the impact, and as a result of the impact and as the crush material  50332  is expelled from the crushable member  50330 . Subsequent to the impact, the crushable member  50330  is collapsed to a minimum longitudinal length, which places the bumper system  50000  in a collapsed condition. 
       FIGS. 52-53  show an extendable bumper system  52000 . The extendable bumper system  52000  includes a bumper  52006  that is supported for movement with respect to a vehicle structure  52002  between a retracted position ( FIG. 52 ) and an extended position ( FIG. 35 ). The extendable bumper system  52000  includes a first slide rail  52008 , a second side rail  52010 , a first extension portion  52012 , and a second extension portion  52014 . The first extension portion  52012  is movably connected to and supported by the first side rail  52008 . The second extension portion  52014  is movably connected to and supported by the second side rail  52010 . The first extension portion  52012  and the second extension portion  52014  are each connected to the bumper  52006 . 
     The first and second extension portions  52012 ,  52014  each include a fluid operated cylinder  52340  such as hydraulic cylinder or a pneumatic cylinder. Each fluid operated cylinder  52340  is connected to a respective piston  52342 , which is disposed therein. Each piston  52342  is connected to a respective piston rod  52344 , which extends out of the respective cylinder  52340  and connects the respective piston rod  52344  to the bumper  52006 . 
     In the retracted position, the pistons  52342  and piston rods  52344  of the first and second extension portions  52012 ,  52014  can be disposed within the respective cylinders  52340  to a maximum extent of retraction. The pistons  52342  can be held in place by locking mechanisms  52346 . The locking mechanisms  52346  can be disposed, for example, within the first and second side rails  52008 ,  52010 . As one example, the locking mechanisms  52346  can include mechanical structures that selectively engage the pistons  52342  to restrain motion of the pistons  52342 . In one implementation, the locking mechanisms  52346  may be solenoid actuated pins that engage a portion of each of the cylinders  52340 . In another implementation, locking mechanisms  52346  can include selectively operable electromagnets that can be activated to produce a magnetic attraction force that attracts the piston  52342  toward the locking mechanisms  52346 . 
     The locking mechanisms  52346  hold the pistons  52342  in place against a biasing force applied by means such as compression springs  52348 . Compression springs  52348  are examples of elements that can be used to urge the pistons  52342  toward the extended position. When the locking mechanisms  52346  are disengaged, the compression springs may urge the pistons  52342  and the piston rods  52344  toward the extended position, thereby moving the bumper  52006  with respect to the vehicle structure  52002  from the retracted position toward the extended position. 
     In order to move the bumper  52006  from the extended position toward the retracted position, the extendable bumper system  52006  includes a pressurized fluid source  52350 . The pressurized fluid source  53250  is operable to supply pressurized fluid such as hydraulic fluid or air to the interior of the cylinders  52340  at a front area of the cylinders  52340  adjacent to where the piston rods  52344  exit in order to urge the pistons  52342  toward the locking mechanisms  52346  against the force applied by the compression springs  52348 . Thus, by supplying fluid pressure to the interior of the cylinders  52340  using the pressurized fluid source  52350 , the bumper  52006  is moved from the extended position toward the retracted position. When the bumper  52006  reaches the retracted position, the locking mechanisms  52346  are engaged to lock the position of the pistons  52342  and thereby maintain the bumper  52006  in the retracted position. 
       FIGS. 54-55  show an extendable bumper system  54000 . The extendable bumper system  54000  includes a bumper  54006  that is movable between a retracted position ( FIG. 54 ) and an extended position ( FIG. 55 ) with respect to a vehicle structure  54002 . The extendable bumper system  54000  includes a first side rail  54008 , a second side rail  54010 , a first extension portion  54012 , and a second extension portion  54014 . The first and second side rails  54008 ,  54010  are each rigidly connected to the vehicle structure  54002 . The first extension portion  54012  is movably connected to the first side rail  54008  and the bumper  54006 . The second extension portion  54014  is movably connected to the second side rail  54010  and to the bumper  54006 . 
     The first extension portion  54012  is pivotally connected to the first side rail  54008  by a first pivot joint  54360 . The first pivot joint  54360  can be located on an inboard side of the first side rail  54008 . The first extension portion  54012  is connected to the bumper  54006  in a manner that allows the first extension portion  54012  to pivot and translate with respect to the bumper  54006 . In the illustrated example, a second pivot joint  54362  pivotally connects the first extension portion  54012  to a sliding mount  54364 . The sliding mount  54364  is able to translate laterally across the bumper  54006  during movement of the extendable bumper system  54000  between the retracted and extended positions. The sliding mount  54364  can be connected to the bumper  54006  by a mechanism that causes movement of the sliding mount  54364  with respect to the bumper  54006 , such as a linear actuator  54366 . For example, the linear actuator  54366  may include an electric motor and lead screw that is connected to the sliding mount  54364  in order to cause motion of the sliding mount  54364  in response to rotation of the lead screw by the electric motor. 
     The second extension portion  54014  can be pivotally mounted to the second side rail  54010  by a third pivot joint  54368 . The second extension portion  54014  may be mounted to the bumper  54006  in a manner that allows pivoting and translation of the second extension portion  54014  with respect to the bumper  54006 . In the illustrated example, the second extension portion  54014  is connected to the bumper by a sliding mount  54370  that is pivotally connected to the second extension portion  54014  by a fourth pivot joint  54372 . The sliding mount  54370  is movably in a transverse direction of the bumper  54006  by the linear actuator  54366 . 
     In the retracted position, the first and second extension portions  54012 ,  54014  are pivoted at angles with respect to the first and second side rails  54008 ,  54010 . In the illustrated example, the first and second extension portions  54012 ,  54014  are each pivoted inboard with respect to the first and second side rails  54008 ,  54010  at an angle of approximately 90 degrees. To move from the retracted position to the extended position, the sliding mounts  54364 ,  54370  are moved laterally outward by the linear actuator  54366 . As the sliding mounts  54364 ,  54370  move outward, the first and second extension portions  54012 ,  54014  pivot with respect to the bumper  54006  and the first and second side rails  54008 ,  54010 . The extendable bumper system  54000  is disposed in the extended position when the first and second extension portions  54012 ,  54014  reach longitudinal alignment with respect to the first and second side rails  54008 ,  54010 , respectively. 
     Movement of the extendable bumper system  54000  from the extended position to the retracted position is performed in a manner opposite that described for movement from the retracted position to the extended position. 
       FIGS. 56-57  show an extendable bumper system  56000 . The extendable bumper system  56000  includes a bumper  56006  that is movable between a retracted position ( FIG. 56 ) and an extended position ( FIG. 57 ) with respect to a vehicle structure  56002 . The extendable bumper system  56000  includes a first side rail  56008 , a second side rail  56010 , a first extension portion  56012 , and a second extension portion  56014 . The first and second side rails  56008 ,  56010  are each rigidly connected to the vehicle structure  56002 . The first extension portion  56012  is movably connected to the first side rail  56008  and the bumper  56006 . The second extension portion  56014  is movably connected to the second side rail  56010  and to the bumper  56006 . 
     The first extension portion  56012  and the second extension portion  56104  may be identical, as in the illustrated example, and will both be described with reference to the first extension portion  56012 . 
     The first extension portion  56012  includes a pair of linkages that connect the first side rail  56008  to the bumper  56006 . The linkages each include a first pivot joint  56380  that connects a first link  56382  to the first side rail  56012 , a second pivot joint  56384  that connects the first link  56382  to a second link  56386 , and a third pivot joint  56388  that connects the second link  56386  to the bumper  56006 . A linear actuator such as a pneumatic or hydraulic cylinder  56390  extends between the linkages to cause extension and retraction, such as by being connected to the second pivot joints  56384 . In the retracted position, the linkages are in a V-shaped configuration with the first links  56382  at angles with respect to the second links  56386 . In the extended position, the linkages are substantially straight, with the first links  56382  in substantial longitudinal alignment with the second links  56386 . In an impact, the cylinder  56390  can resist motion from the extended position to the retracted position to absorb some of the energy of the impact. 
       FIGS. 58-59  show an extendable bumper system  58000 . The extendable bumper system  58000  includes a bumper  58006  that is movable between a retracted position ( FIG. 58 ) and an extended position ( FIG. 59 ) with respect to a vehicle structure  58002 . The extendable bumper system  58000  includes a first side rail  58008  and a first extension portion  58012 . The extendable bumper system  58000  may also include additional side rails and extension portions (not shown). The first side rail  58008  is rigidly connected to the vehicle structure  58002 . The first extension portion  58012  is movably connected to the first side rail  58008 . 
     In the illustrated implementation, the first extension portion  58012  is a beam that is telescopically related to the first side rail  58008  for movement between the retracted and extended positions. The bumper  58006  and the vehicle structure  58002  are also connected to an assembly that includes a cylinder  58400  and an associated piston  58402 . A micro gas generator  58404  is operable to rapidly supply gas to the interior of the piston  58400  to cause movement from the retracted position to the extended position rapidly, such as over a time frame of less than 100 milliseconds and in some implementations over a time from of 5-15 milliseconds. This allows movement of the bumper  58006  to the extended position upon detection of an imminent impact. As an example, the micro gas generator may be a pyrotechnic device that generates gas by combustion. The extendable bumper system  58000  may also include a separate means for extension and retraction for situations other than an imminent impact. 
       FIGS. 60-61  show an extendable bumper system  60000 . The extendable bumper system  60000  includes a bumper  60006  that is movable between an extended position ( FIG. 60 ) and a retracted position ( FIG. 61 ) with respect to a vehicle structure  60002 . The extendable bumper system  60000  includes a first side rail  60008  and a first extension portion  60012 . The extendable bumper system  60000  may also include additional side rails and extension portions (not shown). The first side rail  60008  is rigidly connected to the vehicle structure  60002 . The first extension portion  60012  is movably connected to the first side rail  60008 . 
     An assembly that includes a cylinder  60410  and a piston  60412  is operable to resist movement of the bumper  60006  from the extended position toward the retracted position. The cylinder  60410  may be fixed with respect to the vehicle structure  60002 . In the illustrated implementation, the piston  60412  is connected to the extension portion  60012  by a wire  60414  and a pulley  60416 . 
     The piston  60412  may be configured to allow motion of the bumper  60006  from the extended position to the retracted position with a predetermined degree of resistance in a first mode of operation. In a second mode of operation, means such as locking balls  60418  engage the cylinder  60410  to restrain motion of the piston  60412  with respect to the cylinder  60410  toward the retracted position, thereby allowing the first extension portion  60012  and the first side rail  60008  to crush without first moving to the retracted position, while deformation of the cylinder  60410  absorbs a portion of the impact. 
     The extendable bumper system  60000  may include an actuator to move the bumper  60006  from the retracted position to the extended position. As an example, a micro gas generator  60404  may be disposed within or fluidly connected to the cylinder  60410  in order to provide pressurized gas to the interior of the cylinder  60410  in response to a signal. The pressurized gas from the micro gas generator is operable to move the piston  60412  such that the bumper  60006  moves toward the extended position from the retracted position. The signal may be generated, as an example, in response to sensing a possible collision. Other types of actuators may be incorporated in the extendable bumper system  60000  including those described with respect to other implementations.

Metadata:
Filing Date: 20170127
Publication Date: 20190709
Grant Date: 20190709
Priority Date: 20160127
Inventors: FERMER, ERIK MIKAEL
WATTS, ALICE C.
JENSEN, JOEL FREDERIC
SMITH, RONALD JACK
ROBER, MARK B.
KIM, SUNG HOON
DOSTAL, DAVID JENNINGS
Mead, Jr., Russell Cranstoun
LEWIS, TODD ELLIOT
BUEHLER, JESSE T.
DENNIS, NATHANIEL J.
RIVELLINI, TOMMASO P.
MAYER, ROBERT R.
MONTEVIRGEN, ANTHONY S.
PARR, DONALD J.
WOOLLARD, BRYCE A.
GOLMAN, ADAM J.
MAKOWSKI, KEVIN P.
RIVERA, DANIEL E.
Assignee: APPLE INC
CPC Classifications: [{"code": "B60R19/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60R19/34", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60R19/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60R19/34", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 67106517