Abstract:
An apparatus for absorbing energy includes first and second steering column members connected for sliding movement. A first anvil is associated with one of the first and second steering column members and an energy absorbing member is provided having a first portion that extends around and operable to be drawn over the first anvil in response to the sliding movement between the first and second steering column members. A dead loop is formed in the energy absorbing member between its mounting location and the first anvil and is operative to enable the dead loop to straighten in response to application of an applied force prior to movement of the energy absorbing member across the first anvil.

Description:
FIELD OF THE INVENTION 
     The invention relates to an energy absorber and more particularly to an energy absorbing apparatus for absorbing energy at different rates. 
     BACKGROUND OF THE INVENTION 
     Steering column assemblies for vehicles often include kinetic energy absorption devices that act to control the collapse of the column in the event of a crash to reduce the likelihood of injury to the driver. One form of an energy absorbing device comprises a metal strap that is bent and drawn over an anvil to absorb kinetic energy of a collapsing column. Examples of this type of energy absorbing device include U.S. Pat. Nos. 6,170,874; 6,189,929; 6,322,103; and 6,652,002. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     The invention provides an apparatus for absorbing energy and positionable in a collapsible steering column of a vehicle. The energy absorber is deformable in response to an excessive frontal impacting force to the steering column so that injury to the vehicle operator is reduced. The apparatus includes a first steering column member and a second steering column member connected to one another for sliding movement. The apparatus also includes a first anvil associated with one of said first and second steering column members and an energy absorbing member having a first portion that extends around and operable to be drawn over the first anvil in response to the sliding movement between the first and second steering column members. The energy absorbing member also includes a second portion connected to the other of the first and second steering column members and a third portion spaced from one of the first and second portions. The third portion is deformable in response to the sliding movement between the first and second steering column members before the first portion is drawn over the first anvil. 
     The invention also provides a second apparatus for absorbing energy and positionable in a collapsible steering column of a vehicle. The second energy absorber is deformable in response to an excessive frontal impacting force to the steering column so that injury to the vehicle operator is reduced. The second energy absorber also includes first and second steering column members connected to one another for sliding movement, a first anvil having a first axis and associated with the first steering column member, and a second anvil having a second axis and associated with said second steering column member. The second apparatus also includes an energy absorbing member having a first portion extending around and operable to be drawn over the first anvil about the first axis and a second portion extending around and operable to be drawn over the second anvil about the second axis wherein the first and second axis are transverse with respect to one another. 
     The present invention provides the advantage of broadening the spectrum of accident parameters that may be used to improve the crashworthiness response of an energy-absorbing column. Furthermore, the invention provides a structure that has heretofore been impossible to use to vary the amount of resistance force to various inputs. The structure to vary the resistance force is an enhancement to the performance of the deformable member. The enhancement, for example, can provide a smaller amount of resistance in the case of a less severe collision or a lower weight occupant and a greater amount of resistance in the case of a more severe collision of a larger weight occupant. Also, the present invention will be very useful in applications which had required two straps. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a top view of a first exemplary embodiment of the invention; 
         FIG. 2  is a cross-sectional view taken along section lines  2 — 2  in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of a second exemplary embodiment of the invention; 
         FIG. 4  is a perspective view of an energy absorbing member associated with a third exemplary embodiment of the invention; 
         FIG. 5  is a top view of the third exemplary embodiment; 
         FIG. 6  is a cross-sectional view taken along section lines  6 — 6  in  FIG. 5 ; 
         FIG. 7  is a cross-sectional view of the third exemplary embodiment of the invention wherein the energy absorbing member is drawn over a second anvil in response to a relatively low impacting force acting on the steering column; 
         FIG. 8  is a cross-sectional view of the third exemplary embodiment wherein the energy absorbing member is drawn over a first anvil in response to a relatively high impacting force acting on the steering column; 
         FIG. 9  is a perspective view of an energy absorbing member associated with a fourth exemplary embodiment of the invention; 
         FIG. 10  is a top view of the fourth exemplary embodiment; 
         FIG. 11  is a cross-sectional view taken along section lines  9 — 9  in  FIG. 8 ; 
         FIG. 12  is a cross-sectional view of the fourth exemplary embodiment in which the energy absorbing member is drawn over a second anvil in response to a relatively low impacting force acting upon the steering column; and 
         FIG. 13  is a cross-sectional view of the fourth embodiment wherein the energy absorbing member is drawn over a first anvil in response to a relatively high impacting force acting on the steering column. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIGS. 1 and 2 , in a first exemplary embodiment of the invention, an apparatus  10  absorbs energy in a collapsible steering column of a vehicle by being deformable in response to excessive frontal impacting force to the steering column so that injury to the vehicle operator is reduced. The apparatus  10  includes a first steering column member  12  and a second steering column member  14 . One of the first and second steering column members  12 ,  14  is fixedly connected to the vehicle. The first and second steering column members  12 ,  14  are connected to one another for sliding movement  16 . The first and second steering column members  12 ,  14  can be inner and outer steering column jackets, upper and lower steering column jackets, brackets, or capsules. 
     The apparatus  10  also includes a first anvil  18  associated with the first steering column member  12  and an energy absorbing member  20  having a first portion  22  extending around and operable to be drawn over the first anvil  18  in response to the sliding movement  16 . The energy absorbing member  20  also includes a second portion  24  connected to the steering column member  14 . For example, the apparatus  10  also includes a second anvil  34  associated with the second steering column member  14  and the second portion  24  of the energy absorbing member  20  extends around and is operable to be drawn over the second anvil  34 . 
     The energy absorbing member  20  also includes a third portion  26  spaced from the first portion  22 . The third portion  26  is deformable in response to the sliding movement  16  before the first portion  22  is drawn over the first anvil  18  and/or before the second portion  24  is drawn over the second anvil  34 . 
     The third portion  26  defines a crooked path between the first and second portions  22 ,  24 . For example, in the first exemplary embodiment of the invention, the third portion  26  defines a first semi-circular dead loop portion  28 . When the first and second steering column members  12 ,  14  move relative to one another in sliding movement  16 , the loop portion  28  is straightened before the first portion  22  is drawn over the first anvil  18  and/or before the second portion  24  is drawn over the second anvil  34 . 
     The third portion  26  also includes a second semi-circular dead loop portion  30  and a substantially straight portion  32  disposed between the first and second loop portions  26 ,  30 . The loop portions  26 ,  30  would be straightened in response to a sliding movement  16  before the second portion  24  is drawn over the anvil  34  and/or before the first portion  22  is drawn over the anvil  18 . 
     The third portion  26  can also define an elliptical loop  38  for dissipating energy before the energy absorbing member  20  is drawn over one of the anvils  18 ,  34 . For example, in the first exemplary embodiment, the second portion  24  defines the loop portion  38  and the loop portion  38  is deformed to a be a substantially cylindrical loop, similar to the first portion  22 , in response to the sliding movement  16  before the first portion  22  is drawn over the anvil  18  and before the second portion  24  is drawn over the anvil  34 . 
     The apparatus  10  also includes a locking device  36  associated with the energy absorbing member  20  to selectively lock the second portion  24  relative to the second anvil  34 . The locking device  36  includes a pin  40  that is selectively removable from an aperture  42  defined by the energy absorbing member  20 . The energy absorbing member  20  can be drawn over the first anvil  18  or the second anvil  34 . In the first exemplary embodiment of the invention, when the pin  40  is positioned in the aperture  42  and sliding movement  16  occurs, the first portion  22  is drawn over the first anvil  18 . If the pin  40  were removed and sliding movement  16  occurs, the second portion  24  would be drawn over the second anvil  34  before the first portion  22  would be drawn over the first anvil  18  because the radius of the second anvil  34  is greater than the radius of the first anvil  18 . 
     Referring now to  FIG. 3 , in a second exemplary embodiment of the invention, an apparatus  110  includes a first steering column member  112  and a second steering column member  114  connected for sliding movement  116 . A first anvil  118  is associated with the first steering column member  112  and a second anvil  134  is associated with the second steering column member  114 . An energy absorbing member  120  includes a first portion  122  extending around and operable to be drawn over the first anvil  118  in response to the sliding movement  116 . The energy absorbing member  120  also includes a second portion  124  extending around an operable to be drawn over the second anvil  134  in response to the sliding movement  116 . 
     The energy absorbing member  120  also includes a third portion  126  spaced from the first portion  122 . The third portion  126  is deformable in response to the sliding movement  116  before the first portion  122  is drawn over the first anvil  118 . The third portion  126  defines a crooked path such as a first semi-circular dead loop portion  128  between the first and second portions  122 ,  124 . The semi-circular loop portion  128  is straightened before the first portion  122  is drawn over the first anvil  118 . 
     The third portion  126  also includes a second semi-circular dead loop portion  130  and a substantially straight portion  126  disposed between the first and second semi-circular loop portions  128 ,  130 . The second semi-circular loop portion  130  is straightened before the second portion  124  is drawn over the second anvil  134 . 
     The locking device  136  includes a pin  140  selectively insertable in an aperture  142 . The pin  140  includes a cam follower portion  54  which is moveable by a cam  56 . The cam  56  is moved by an actuator  58  controlled by a controller  60 . The controller  60  can communicate with sensors (not shown) disposed in the vehicle to selectively withdraw the pin  140  from the aperture  142  by engaging the actuator  58  to move the cam  56  and urge the cam follower portion  54  downward with respect to the orientation of  FIG. 3 . The sensors communicating with the controller  60  can sense one or more factors including, but not limited to, the speed of the vehicle, the rate of deceleration of the vehicle, a frontal impact of the vehicle, the weight of the driver, the proximity of the driver to the steering wheel, and whether the driver is restrained by a seat belt. The controller  60  can receive communications from the sensors corresponding to sensed conditions and, based on programmable and executable logic stored in memory of the controller  60 , selectively engage the actuator  58 . 
     Referring now to  FIGS. 4–8 , in a third exemplary embodiment of the invention, an apparatus  210  absorbs energy in a collapsible steering column of a vehicle by being deformable in response to an excessive frontal impacting force to the steering column so that injury to the vehicle operator is reduced. The apparatus  210  includes a first steering column member  212  and a second steering column member  214  connected to one another for sliding movement  216 . The apparatus  210  also includes a first anvil  218  having a first axis  238  and associated with first steering column member  212 . The apparatus  210  also includes a second anvil  234  having a second axis  240  and associated with a second steering column member  214 . 
     The apparatus  210  also includes an energy absorbing member  220  having a first portion  222  extending around and operable to be drawn over the first anvil  218  about the first axis  238  and also includes a second portion  224  extending around and operable to be drawn over the second anvil  234  about the second axis  240 . The first and second axes  238 ,  240  are transverse with respect to one another. For example, in the third exemplary embodiment, the axes  238 ,  240  are perpendicular to one another. In alternative embodiments of the invention, the axes  238 ,  240  could extend at a non-perpendicular angle relative to one another. 
     The energy absorbing member  220  defines a rectangular cross section. A shorter edge  44  of the rectangular cross section contacts the anvil  218  and a longer edge  46  of the rectangular cross section contacts the anvil  234 . Because of the rectangular cross-section of the energy absorbing member  220 , the energy absorption characteristics associated with drawing the energy absorbing member  220  over the first anvil  218  are different than the energy absorption characteristics associated with drawing the energy absorbing member  220  over the second anvil  234 . For example, more energy will be dissipated when the first portion  222  is drawn over the first anvil  218  because the shorter edge  44  faces the first anvil  218 . The energy absorption characteristics can be further differentiated by sizing the anvils  218 ,  234  differently with respect to one another. 
     The apparatus  210  also includes a locking device  236  to selectively lock the second portion  224  with respect to the anvil  234 . The locking device  236  includes a pin  48  supporting the anvil  234 . The locking device  236  also includes a pin releasing device  50  engaged with the pin  48 . The pin releasing device  50  can retract the pin  48  from the anvil  234  and allow the anvil  234  to move relative to the second steering column member  214 . As best seen in  FIG. 8 , the energy absorbing member  220  will be pinched between the anvil  234  and the second steering column member  214  when the pin  48  is released. 
       FIG. 7  shows the first and second steering column members  212 ,  214  moving relative to one another in sliding movement  216  in response to a relatively low impacting force. The pin  48  is maintained in position and the second portion  224  is drawn over the anvil  234 . In  FIG. 8 , the first and second steering column members  212 ,  214  are moving relative to one another in sliding movement  216  in response to a relatively high impacting force. The pin  48  has been retracted and the anvil  234  is urged toward the second steering column member  214 . As a result, the first portion  222  is being drawn over the first anvil  218 . 
     Referring now to  FIGS. 9–13 , in a fourth exemplary embodiment of the invention, an apparatus  310  includes a first steering column member  312  and a second steering column member  314  connected to one another for sliding movement  316 . The first and second steering column members  312 ,  314  can be inner and outer steering column jackets, upper and lower steering column jackets, or can be defined as brackets or capsules. 
     The apparatus  310  also includes a first anvil  318  associated with the first steering column member  312  and having a first axis  338 . The apparatus  310  also includes a second anvil  334  associated with the second steering column member  314  and having a second axis  340 . The apparatus  310  also includes an energy absorbing member  320  having a first portion  322  extending around and operable to be drawn over the first anvil  318  about the first axis  338  in response to the sliding movement  316 . The energy absorbing member  320  also includes a second portion  324  extending around and operable to be drawn over the second anvil  334  about the second axis  340  in response to the sliding movement  316 . 
     The first and second axes  338 ,  340  are transverse with respect to one another. In the fourth exemplary embodiment of the invention, the axes  338 ,  340  are substantially perpendicular to one another. However, in alternative embodiments of the invention, an angle of less than 90 degrees can be defined between the first and second axes  338 ,  340 . 
     The energy absorbing member  320  defines a rectangular cross-section. The rectangular cross-section includes a shorter edge  344  and a longer edge  346 . The shorter edge  344  contacts the first anvil  318  and the longer edge  346  contacts the second anvil  334 . As a result, the rate of energy absorption associated with drawing the first portion  322  over the anvil  318  is greater than the rate of energy absorption associated with drawing the second portion  324  over the anvil  334  when the anvils  318 ,  334  are sized similarly. The rate of energy absorption can be further differentiated by sizing the anvils  318 ,  334  differently. 
     The apparatus  310  also includes a locking device  336  associated with the energy absorbing member  320  to lock the second portion  324  relative to the second anvil  334 . The second anvil  334  is supported on a pin  348 . The locking device  336  includes a pin retracting device  350 . As best shown in  FIG. 12 , in response to a relatively low impacting force, the pin  348  is maintained in place to support the second anvil  334  and the second portion  324  is drawn over the anvil  334  to absorb energy. As best shown in  FIG. 13 , in response to a relatively high impacting force, the pin retracting device  350  retracts the pin  348  and, in response to the sliding movement  316 , the second anvil  334  is moved in a direction  52  by the energy absorbing member  320  and the first portion  322  is drawn over the first anvil  318 . 
     The energy absorbing member  320  also includes a third portion  326  spaced from the first portion  322 . The third portion  326  is deformable in response to the sliding movement  316  before the first portion  322  is drawn over the first anvil  318  and before the second portion  324  is drawn over the second anvil  334 . The third portion  326  defines a crooked path, such as a first semi-circular dead loop portion  328 , between the first and second portions  322 ,  324 . As best shown in  FIGS. 12 and 13 , the loop portion  328  is straightened in response to the sliding movement  316 . 
     The size of the loop portion  328  corresponds to the distance along the path of sliding movement  316  associated with the release of the steering column from the vehicle. For example, steering columns are often connected to vehicles with capsules. The capsules provide a rigid connection to the vehicle during normal vehicle handling but will break in response to an impacting force. In current steering columns, the energy absorbing member is not engaged until the capsules have been broken. The present invention provides the third portion  326  of the energy absorbing member  320  to absorb energy during the breaking of the capsule. In other words, the loop portion  328  can be sized such that it defines a crooked path before the impacting force is applied to the steering column but is substantially straight once the capsules that connect the steering column to the vehicle have been broken. 
     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.