Patent Publication Number: US-2016221598-A1

Title: Steering column clamp mechanism

Description:
FIELD OF THE INVENTION 
     The following description relates to steering columns for motor vehicles and, more specifically, to a clamping mechanism lock for a steering column. 
     BACKGROUND 
     Some known steering columns for motor vehicles are provided with mechanisms for adjusting the steering column position by an operator of the motor vehicle. Available adjustments typically include a telescoping adjustment in which the steering column is extended toward the operator or retracted away from the operator, and a tilt or rake adjustment in which an angular position of the steering column is changed relative to the operator. 
     In some known systems, rake is adjusted by releasing an adjustment lever from a secured position, which then allows for rotation of the steering column about a pivot, typically located at an end of the steering column opposite that of the of the steering wheel. Returning the adjustment lever to the secured position retains the steering column in a desired set position about the pivot. 
     However, some traditional locks for steering columns may provide inadequate load handling capabilities for preventing steering column displacements in the event of a vehicle collision. For example, some known systems may allow unlocking direction motion of a steering column clamp mechanism during or after a crash event. Various conditions may cause or allow rotation of the clamp mechanism such as contact with moving and/or deformed components (e.g., shrouds and closeouts), reduced clamp tension in post-crash positions, inertial loading, and post-crash settling of components. 
     Accordingly, it is desirable to provide a steering column clamp mechanism to prevent unlock direction motion during a collapse event and to prevent damage induced by excessive impact loading. 
     SUMMARY OF THE INVENTION 
     In one exemplary embodiment of the present invention, a clamping mechanism for a steering column assembly is provided. The clamping mechanism includes an outboard cam configured to rotate about an axis between a first position and a second position, an inboard cam having a travel limiter portion configured to limit rotation of the outboard cam about the axis between the first position and the second position, and an intermediate stop disposed along a portion of the travel limiter portion. At least a portion of the outboard cam is shifted to a position adjacent the intermediate stop during an impact event of the steering column assembly, the intermediate stop preventing movement of the outboard cam from the first position to the second position. 
     In another exemplary embodiment of the present invention, a steering column assembly is provided. The steering column assembly includes a steering column, a rake bracket coupled to the steering column, and a clamping mechanism configured to selectively enable raking movement of the steering column relative to the rake bracket. The clamping mechanism includes an outboard cam configured to rotate about an axis between a first position and a second position, an inboard cam having a travel limiter portion configured to limit rotation of the outboard cam about the axis between the first position and the second position, and an intermediate stop disposed along a portion of the travel limiter portion. At least a portion of the outboard cam is shifted to a position adjacent the intermediate stop during an impact event of the steering column assembly, the intermediate stop preventing movement of the outboard cam from the first position to the second position. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a side view of an exemplary steering column assembly; 
         FIG. 2  is an exploded view of a portion of the steering column assembly shown in  FIG. 1 ; 
         FIG. 3  is another exploded view of a portion of the steering column assembly shown in  FIG. 1 ; 
         FIG. 4  is a side view of a clamping mechanism of the steering column assembly shown in  FIG. 1  in an unlocked position; 
         FIG. 5  is a side view of the clamping mechanism shown in  FIG. 4  in a locked position; 
         FIG. 6  is a side view of the clamping mechanism shown in  FIG. 4  in a post-impact event position; 
         FIG. 7  is a perspective view of another clamping mechanism in an unlocked position; 
         FIG. 8  is a perspective view of the clamping mechanism shown in  FIG. 7  in a locked position; and 
         FIG. 9  is a perspective view of the clamping mechanism shown in  FIG. 7  in a post-impact event position. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same,  FIGS. 1-3  illustrate an exemplary steering column assembly  10 . As shown in  FIG. 1 , an exemplary steering column assembly  10  of a vehicle (not shown) generally includes a steering column  12 , a mounting or rake bracket  14 , a locking or clamping mechanism  16 , and a lever or lock arm  18 . 
     Steering column lock arm  18  is utilized to selectively resist or facilitate raking movement of a steering column  12  within an adjustment range defined by clamping mechanism  16 . When steering column lock arm  18  is positioned so as to place clamping mechanism  16  in a locking mode ( FIGS. 1 and 5 ), steering column  12  is inhibited from being adjusted. Accordingly, steering column  12  is relatively fixed, positionally, with respect to the vehicle. When steering column lock arm  18  is positioned so as to place clamping mechanism  16  in an adjustment mode ( FIG. 4 ), adjustments to the positioning of steering column  12  are facilitated. Accordingly, steering column  12  may be positionally adjusted relative to the vehicle. Once steering column  12  occupies a desirable position, steering column lock arm  18  may be re-positioned so as to return clamping mechanism  16  to the locking mode. 
     In an exemplary embodiment, clamping mechanism  16  generally includes a stack-up beginning at the outermost portion of clamping mechanism  16  from steering column  12 . It includes an outboard cam  20 , one or more pins  22 , an inboard cam  24 , a locking tooth  26 , and a lock tooth bracket  28 . Clamping mechanism  16  is configured for selectively resisting or facilitating raking adjustment of steering column  12  and is operably associated with rake bracket  14 . In an exemplary embodiment, rake bracket  14  is fixed to a structure of the vehicle (not shown) and disposed adjacent to steering column  12 . 
     As shown in  FIGS. 2 and 3 , rake bracket  14  includes a rake lock tooth wall  30  that bounds a control slot  32  and that defines a plurality of rake lock teeth  34 . The rake lock tooth wall  30  with its plurality of rake lock teeth  34  provides a stationary structure against which a cooperating member (e.g., locking tooth  26  having teeth  36 ) may be engaged so as to lock the cooperating member to the stationary structure. It should be appreciated that locking surface features other than teeth (e.g., a rough or tacky surface) may be employed so as to provide a stationary structure against which a cooperating member may be engaged so as to lock the cooperating member to the stationary structure. Alternatively, assembly  10  may not include rake lock features  26 ,  30 ,  34 , and/or  36 . 
     A rake bolt  38  extends through lock arm  18 , clamping mechanism  16 , and rake bracket  14  and is configured for rotation about an axis  40 . Steering column lock arm  18  is coupled to rake bolt  38  through outboard cam  20  such that steering column lock arm  18  facilitates application of a torque upon rake bolt  38  in either a locking direction  42  or an adjustment direction  44  (see  FIG. 1 ). 
     In an exemplary embodiment, outboard cam  20  operates in conjunction with the steering column lock arm  18  so as to limit the absolute range of rotation of rake bolt  38  so as to prevent application of excessive loads upon tooth lock  26  or other components of clamping mechanism  16 . 
     Inboard cam  24  may be utilized in connection with outboard cam  20  selectively clamp or lock steering column  12  to prevent raking movement. For example, one or more pins  22  may be pressed into a ramped slot  46  formed in outboard cam  20 , and pins  22  may then extend through a slot  48  formed in inboard cam  24 . As illustrated, as lock arm  18  rotates in the adjustment directions  42 ,  44 , pins  22  move along ramped slot  46  to move outboard cam  20  toward or away from inboard cam  24 . As such, in the unlocked position, pins  22  are oriented generally parallel to rotation axis  40  and outboard cam  20  is spaced apart from inboard cam  24 . As lock arm  18  is rotated to the locked position, pins  22  are angled relative to rotation axis  40  and outboard cam  20  is pressed or clamped against inboard cam  24  and rake bracket  14  to facilitate preventing raking movement of steering column  12  relative thereto. 
     In addition, inboard cam  24  may be used along with rake bracket  14  to define the range of translational motion of rake bolt  38  and tooth lock  26 . The tooth lock  26  is configured for selectively engaging and disengaging from the rake lock tooth wall  30  and the plurality of rake lock teeth  34 , in response to forward movement or shuttling of rake bolt  38 , so as to selectively resist or enable translation of tooth lock  26  in a raking direction  50 . 
     In an exemplary embodiment, rake bolt  38  is translationally fixed to steering column  12 , inboard cam  24 , and tooth lock  26  such that when steering column  12  undergoes raking movement, rake bolt  38 , inboard cam  24 , and tooth lock  26  also undergo raking movement. Accordingly, when tooth lock  26  is prevented from undergoing raking movement, rake bolt  38 , inboard cam  24 , and steering column  12  are also prevented from undergoing raking movement. 
       FIGS. 4-6  illustrate the locking movement of clamping mechanism  16 , which facilitates selective locking of steering column  12  and preventing unlocking motion of lock arm  18  during/after a crash event. Specifically,  FIG. 4  illustrates lock arm  18  and clamping mechanism  16  in an unlocked position,  FIG. 5  illustrates lock arm  18  and clamping mechanism  16  in a locked position, and  FIG. 6  illustrates lock arm  18  and clamping mechanism  16  in a post-impact locked position. 
     With further reference to  FIGS. 2 and 3 , outboard cam  20  includes a main body  60  and an insertion portion  62  and a post  64  extending therefrom. Insertion portion  62  is oriented within a receiving aperture  66  ( FIG. 2 ) of lock arm  18  such that rotational movement of lock arm  18  imparts rotational movement on outboard cam  20 . Main body  60  and insertion portion  62  include a bolt aperture  68  to receive rake bolt  38  therethrough. Post  64  is configured to selectively engage inboard cam  24 , as described herein in more detail. 
     As illustrated in  FIGS. 2 and 3 , inboard cam  24  includes a main body  70 , a translating projection  72 , and a travel limiter portion  74 . Main body  70  includes slots  48  and a slotted aperture  76  formed therein. Slotted aperture  76  is configured to receive rake bolt  38  therethrough and enables forward shuttling movement of rake bolt  38  during a crash or impact event due to the elongated shape of slotted aperture  76 . Translating projection  72  is oriented within a channel or slot  78  ( FIG. 3 ) formed in rake bracket  14 , which enables inboard cam  24  to move in the raking direction  50 , but prevents forward/aft movement of inboard cam  24 . Travel limiter portion  74  includes an upper stop  80 , a lower stop  82 , and an intermediate stop or shoulder  84  disposed therebetween. 
     In the unlocked position ( FIG. 4 ), cam post  64  is adjacent to lower stop  82  and prevented from further movement toward stop  82 . In this position, cam post  64  is disposed radially outward of shoulder  84 . As such, shoulder  84  prevents forward movement of outboard cam  20  (and other connected components) to facilitate preventing damage to shearable retaining features that hold clamp mechanism  16  in place during normal adjustment of steering column assembly  10 . 
     When lock arm  18  is moved to the locked position ( FIG. 5 ), cam post  64  travels along travel limiter  74  to contact upper stop  80 , where post  64  is prevented from further movement toward stop  80 . In this position, cam post  64  is also disposed radially outward of shoulder  84 . Thus, during normal operation between the locked and unlocked positions, cam post  64  is rotated between stops  80  and  82  radially outward of shoulder  84 . 
     In a crash or impact event, steering column assembly  10  transitions from the locked position ( FIG. 5 ) to the post-impact locked position ( FIG. 6 ). During the impact event, steering column  12  collapses forward, which causes forward shuttling in the direction of arrow  100 , of rake bolt  38 , lock arm  18 , outboard cam  20 , and locking tooth  26 . The forward shuttling causes teeth  36  of locking tooth  26  to engage teeth  34  of rake lock tooth wall  30 . As shown in  FIG. 6 , cam post  64  is shifted or shuttled toward inboard cam slotted aperture  76  such that cam post  64  is now disposed between upper stop  80  and shoulder  84 . As such, shoulder  84  prevents downward movement of cam post  64  toward lower stop  82 , which facilitates preventing movement of lock arm  18  to the unlocked position. 
       FIGS. 7-9  illustrate an alternate clamping mechanism  116  that may be used with steering column assembly  10  when inboard cam  24  does not include an integral intermediate stop or shoulder  84  to prevent downward movement of cam post  64  after a crash or impact event. In the illustrated embodiment, clamping mechanism  116  includes a plate member  120  generally having a bolt slot  122 , a pin aperture  124 , and an intermediate stop or shoulder  184 . Clamping mechanism  116  is disposed between outboard cam  20  and inboard cam  24  and operates in a manner similar to clamping mechanism  16 , except that plate member shoulder  184  provides structure and function similar to shoulder  84  in the embodiment shown in  FIGS. 4-6 . 
       FIG. 7  illustrates clamping mechanism  116  and plate member  120  in an unlocked position. In this position, cam post  64  is disposed radially outward of shoulder  184 , which prevents forward movement of outboard cam  20  (and other connected components) to facilitate preventing damage to shearable retaining features that hold clamp mechanism  116  in place during normal adjustment of steering column assembly. 
     When lock arm  18  is moved to the locked position ( FIG. 8 ), cam post  64  is disposed radially outward of shoulder  184 . Thus, during normal operation between the locked and unlocked positions, cam post  64  is rotated between stops  80  and  82  (not shown in  FIGS. 7-9 ) radially outward of shoulder  184 . 
     In a crash or impact event, steering column assembly  10  transitions from the locked position ( FIG. 8 ) to the post-impact locked position ( FIG. 9 ). During the impact event, steering column  12  collapses forward, which causes forward shuttling of rake bolt  38  and outboard cam  20 . Bolt slot  122  allows shuttling of rake bolt  38 , but pin  22  extending through pin aperture  124  prevents or reduces shuttling movement of plate member  120 . As such, cam post  64  is shifted or shuttled toward inboard cam slotted aperture  76  such that cam post  64  is now disposed between upper stop  80  and shoulder  184 . In this position, shoulder  184  prevents downward movement of cam post  64  toward lower stop  82 , which facilitates preventing movement of lock arm  18  to the unlocked position. 
     Described herein are systems and methods that facilitate preventing unlocking motion of a clamp mechanism during or after a crash event. The clamp mechanism includes an outboard cam having a cam post that translates within a travel limiter of an associated inboard cam. The travel limiter includes opposed travel stops that enable the cam post to move between a locked and unlocked position. A projecting shoulder is disposed in a portion of the space between the travel stops. In normal operation between the locked and unlocked positions, the shoulder does not interfere with movement of the cam post. However, during a crash event, the cam post is shuttled forward into an area between one travel stop and the shoulder, which subsequently prevents movement of the cam post into the unlocked position. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description.