Patent Publication Number: US-9428210-B2

Title: Position lock for steering column

Description:
BACKGROUND OF THE INVENTION 
     This patent application claims priority to U.S. Pat. No. 8,888,131 issued Nov. 18, 2014 filed as application Ser. No. 13/537,436, Jun. 29, 2012 which is incorporated herein by reference in its entirety. 
     The present invention relates generally to locking adjustment mechanisms for steering columns and more specifically to systems and methods for selectively fixing a position of a steering column assembly or facilitating adjustment of a steering column assembly in at least a raking direction. 
     Traditional locks for steering columns often provide inadequate load handling capabilities for preventing upward steering column displacements in the event of a vehicle collision. Some prior attempts to address this issue have sought use of interlocking teeth to provide the required vertical stability. Unfortunately, however, many configurations that employ interlocking teeth to provide for a positive lock, while providing for selective engagement and disengagement of the teeth for alternating adjustment and locking of the steering column, encounter practical difficulties. For example, one source of dissatisfaction with such locking mechanisms is that the need to interlock the teeth of one component with the teeth of another may limit the available lock positions to a predefined finite set of positions. This issue provides a motivation toward decreasing the size of each of the teeth so as to decrease the incremental difference from one position to the next, providing for finer adjustments. Unfortunately, smaller teeth can result in decreased position assurance and loss of tactile sensations normally associated with the failure to securely seat the interlocking teeth. 
     Accordingly, it is desirable to have a system and method for selectively fixing and adjusting a position of a steering column with improved fineness in the availability of adjustment positions and with improved reliability and security. 
     SUMMARY OF THE INVENTION 
     In a first aspect, an exemplary position lock for selectively resisting or facilitating raking movement of an adjustable steering column assembly of a vehicle comprises a rake lock bracket, a tooth lock and a driver. The rake lock bracket is fixed to the vehicle and disposed adjacent to the steering column assembly along a direction of raking movement of the steering column. The rake lock bracket has a rake lock tooth wall that bounds a control slot and that defines a plurality of rake lock teeth. The tooth lock is coupled to the steering column for movement with the steering column in a raking direction. The tooth lock is also supported for rotation about a tooth lock rotation axis. 
     The driver, which is supported for translation with the tooth lock and for rotation about a driver rotation axis, is configured and positioned for contacting an actuation feature of the tooth lock within an active range of rotation of the driver so as to cause the tooth lock to rotate with the driver as the driver rotates within the active range of rotation of the driver. In one embodiment, a spring is configured and arranged so as to apply a biasing moment tending to cause the tooth lock to rotate in a locking direction. The tooth lock is configured for engaging, upon rotation in the locking direction, at least one tooth of the plurality of rake lock teeth so as to selectively resist translation of the tooth lock and the steering column in the raking direction. The tooth lock is also configured for disengaging, upon rotation in an adjustment direction, from the at least one tooth of the plurality of rake lock teeth so as to selectively facilitate translation of the tooth lock and the steering column in the raking direction. 
     In a second aspect, an exemplary method for selectively resisting or facilitating raking movement of an adjustable steering column assembly of a vehicle comprises fixing a rake lock bracket to the vehicle, adjacent to the steering column assembly and along a direction of raking movement of the steering column. The rake lock bracket has a rake lock tooth wall that bounds a control slot and that defines a plurality of rake lock teeth. A tooth lock is coupled to the steering column for movement with the steering column in a raking direction and supported for rotation about a tooth lock rotation axis. 
     A driver is supported for translation with the tooth lock and for rotation about a driver rotation axis. The driver is configured and positioned the for contacting an actuation feature of the tooth lock within an active range of rotation of the driver so as to cause the tooth lock to rotate with the driver as the driver rotates within the active range of rotation of the driver. The tooth lock is rotated in the locking direction so as to engage at least one tooth of the plurality of rake lock teeth and thereby selectively resist translation of the tooth lock and the steering column in the raking direction. The tooth lock is rotated in an adjustment direction so as to disengage from the at least one tooth of the plurality of rake lock teeth and hereby selectively facilitate translation of the tooth lock and the steering column in the raking direction. 
     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  illustrates a perspective view of an exemplary steering column assembly; 
         FIG. 2  illustrates an exploded perspective view of an exemplary position lock for a steering column; 
         FIG. 3  illustrates a side view of an exemplary position lock for a steering column; 
         FIG. 4  illustrates a side view of an exemplary position lock for a steering column in a locked mode; 
         FIG. 5  illustrates a side view of an exemplary position lock for a steering column in an adjustment mode; and 
         FIG. 6  illustrates an exploded perspective view of an exemplary position lock together with an adjustable steering column. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same,  FIG. 1  illustrates an exemplary steering column assembly  100 . As shown in  FIG. 1 , an exemplary steering column assembly  100  of a vehicle (not shown) comprises a steering column lock arm  184  for selectively resisting or facilitating raking movement of a steering column  116  within an adjustment range defined by a position lock  102 . When the steering column lock arm  184  is positioned so as to place the position lock  102  in a locking mode, the steering column  116  is inhibited from being adjusted. Accordingly, the steering column  116  is relatively fixed, positionally, with respect to the vehicle. When the steering column lock arm  184  is positioned so as to place the position lock  102  in an adjustment mode, adjustments to the positioning of the steering column  116  are facilitated. Accordingly, the steering column  116  is relatively may be positionally adjusted relative to the vehicle. Once the steering column  116  occupies a desirable position, the steering column lock arm  184  may be re-positioned so as to return the position lock  102  to the locking mode. 
       FIG. 2  and  FIG. 6  show exploded views of an exemplary position lock  102 . As shown in  FIG. 2  and  FIG. 6 , in an exemplary embodiment, a position lock  102  for selectively resisting or facilitating raking adjustment of a steering column  116  of a vehicle includes a rake lock bracket  104 . In an exemplary embodiment, the rake lock bracket  104  is fixed to a structure of the vehicle (not shown) and disposed adjacent to the steering column  116 , along a raking direction  118  of the steering column  116 . As shown in  FIG. 2 , an exemplary rake lock bracket  104  has a rake lock tooth wall  108  that bounds a control slot  178  ( FIG. 4 ) and that defines a plurality of rake lock teeth  112 . The rake lock tooth wall  108  with its plurality of rake lock teeth  112  provides a stationary structure against which a cooperating member 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. 
     A tooth lock  114  is supported for rotation about a tooth lock rotation axis  120 , and a driver  122  is supported for rotation about a driver rotation axis  124 . In an exemplary embodiment, both the tooth lock rotation axis  120  and the driver rotation axis  124  correspond to the longitudinal axis of a rake lock control shaft  136 , which is coupled to the steering column lock arm  184 . The steering column lock arm  184  is coupled to the rake lock control shaft  136  such that steering column lock arm  184  facilitates application of a torque upon the rake lock control shaft  136  in either a locking direction  134  ( FIG. 3 ) or an adjustment direction  170  ( FIG. 3 ). In an exemplary embodiment, a cam  110  operates in conjunction with the steering column lock arm  184  so as to limit the absolute range of rotation of the rake lock control shaft  136  so as to prevent application of excessive loads upon the tooth lock  114  or other components of the position lock  102 . 
     A tooth lock cartridge  176  may be used in connection with the cam  110  to limit the absolute range of rotation of the rake lock control shaft  136 . In addition, the tooth lock cartridge  176  may be used along with the rake lock bracket  104  to define the range of translational motion of the rake lock control shaft  136  as well as that of the tooth lock  114  and the driver  122 . A spring  130  is arranged so as to aid in control of the tooth lock  114 . The tooth lock  114  is configured for selectively engaging and disengaging from the rake lock tooth wall  108  and the plurality of rake lock teeth  112 , in response to rotation of the rake lock control shaft  136 , so as to selectively resist or facilitate translation of the tooth lock  114  in the raking direction  118 . 
     In an exemplary embodiment, the rake lock control shaft  136  is translationally fixed to both the steering column  116  and the tooth lock  114  such that when the steering column  116  undergoes raking movement, the rake lock control shaft  136  and the tooth lock  114  also undergo raking movement. Accordingly, when the tooth lock  114  is prevented from undergoing raking movement, the rake lock control shaft  136  and the steering column  116  are also prevented from undergoing raking movement. In an exemplary embodiment, the tooth lock  114  is coupled to the steering column  116  for movement with the steering column  116  in a raking direction  118 , and, as shown in  FIG. 2 , the driver  122  is supported for translation with the tooth lock  114 . 
       FIG. 3 ,  FIG. 4 , and  FIG. 5  show side views of a portion of an exemplary position lock  102  in various stages of operation. As shown in  FIG. 3 , the driver  122  is configured and positioned for contacting an actuation feature  126  of the tooth lock  114  within an active range of rotation  128  of the driver  122  so as to cause the tooth lock  114  to rotate with the driver  122  as the driver  122  rotates within the active range of rotation  128 . The spring  130  is configured and arranged so as to apply a biasing moment  132  tending to cause the tooth lock  114  to rotate in a locking direction  134 . The tooth lock  114  is disposed on the rake lock control shaft  136  for rotation about the rake lock control shaft  136 . The driver  122  is also disposed on the rake lock control shaft  136 , but, unlike the tooth lock  114 , the driver  122  is coupled to the rake lock control shaft  136  for rotation with the rake lock control shaft  136 . 
     In an exemplary embodiment, the tooth lock  114  is disposed so as to define a tooth lock working distance  138  between the rake lock tooth wall  108  and the tooth lock rotation axis  120 . The tooth lock  114  defines a toothed peripheral edge  140  proximate the rake lock tooth wall  108 . A first tooth  142  on the toothed peripheral edge  140  is disposed at a first tooth distance  144  from the tooth lock rotation axis  120 . The first tooth distance  144  is greater than the tooth lock working distance  138 . A second tooth  146  on the toothed peripheral edge  140  is disposed at a second tooth distance  148  from the tooth lock rotation axis  120 . The second tooth distance  148  is greater than the first tooth distance  144 . A third tooth  150  on the toothed peripheral edge  140  is disposed at a third tooth distance  152  from the tooth lock rotation axis  120 . The third tooth distance  152  is greater than the second tooth distance  148 . 
     Once the first tooth  142  is engaged with a mating tooth of the plurality of rake lock teeth  112  on the tooth lock wall  108 , further urging of the center of the tooth lock  114  in the raking direction coupled with the interlocking engagement of the first tooth  142  with the mating tooth, imposes a moment on the tooth lock  114  in the locking direction. This moment, coupled with the increasing tooth distances  148 ,  152  associated with the second and third teeth  146 ,  150 , relative to the tooth distance  144 , tends to force the tooth lock  114  into further, and more secure, engagement with the rake lock tooth wall  108 . 
     It should be appreciated that, as the tooth lock  114  is urged toward further engagement with the rake lock tooth wall  108 , the tooth lock rotation axis  120  may be urged to reside at a position that is further from the rake lock tooth wall  108  than when only the first tooth  142  is in engagement. Accordingly, the rotation of the tooth lock  114  may tend to urge an increase in the tooth lock working distance  138 . To oppose such movements to the tooth lock rotation axis  120  or to the tooth lock working distance  138 , a stabilizer may be implemented in the static structure adjacent to the tooth lock  114  so as to cooperate with the tooth lock  114  in resisting or limiting such movements. For example, in an exemplary embodiment, a tooth lock cartridge  176  may be configured to provide one or more abutments positioned so as to resist or limit such movements of the tooth lock  114 . Similarly, an abutment may be positioned adjacent to the rake lock control shaft  136  so as to resist or limit excessive deflection in the rake lock control shaft  136 . In configurations wherein the rake lock  114  is coupled to the rake lock control shaft  136 , movements in the rake lock  114  can be resisted. 
     Still further, the rake lock bracket  104  may provide a back-stopping mechanism to resist or limit such movements of the tooth lock  114 . In an exemplary embodiment, the rake lock bracket  104  has a stabilizing wall  154  disposed substantially parallel to the rake lock tooth wall  108 . The stabilizing wall  154  (or other abutment feature) is configured to facilitate sliding contact with a substantially smooth peripheral edge  156  of the tooth lock  114 . The tooth lock rotation axis  120  is disposed a distance from the stabilizing wall  154  so as to define a stabilizing distance  158 . The tooth lock  114  is configured for engaging the stabilizing wall  154  so as to resist or prevent undesirable changes in the tooth lock working distance  138 , and this may be accomplished by maintaining a desirable stabilizing distance  158 . The tooth lock  114  defines the substantially smooth peripheral edge  156  proximate the stabilizing wall  154  or other abutment feature. The peripheral edge  156  is disposed at a desirable (e.g., substantially constant, varying in a manner that is complementary to the profile of the toothed peripheral edge) radial distance  160  from the tooth lock rotation axis  120 . By setting an appropriate profile for the radial distance  160  (e.g., being approximately equal to the stabilizing distance  158 , etc.), the interaction of the peripheral edge  156  and the stabilizing wall  154  or other abutment feature (or the interaction of the rake lock control shaft  136  with an abutment feature may assist in resisting or limiting undesirable movements of the tooth lock  114  and the rake lock control shaft  136 . 
     In an exemplary embodiment, the driver  122  is configured and positioned for rotating through a passive range of rotation  162  of the driver  122  that differs from the active range of rotation  164  of the driver  122 . The driver  122  is configured and positioned for avoiding contact with the actuation feature  126  of the tooth lock  114  within the passive range of rotation  162  of the driver  122  so as to avoid causing the tooth lock  114  to rotate with the driver  122  within the passive range of rotation  162  of the driver  122 . In an exemplary embodiment, the driver  122  is in engagement with a spring  130  such that as the driver rotates in the adjustment direction  170 , the biasing force decreases. In an exemplary embodiment, the driver  122  is in engagement with a spring  130  such that as the driver  122  rotates in the locking direction  134 , the biasing force increases. 
     In an exemplary embodiment, the rake lock control shaft  136  is arranged substantially transversely to the raking direction  118 , each tooth of the plurality of rake lock teeth  112  is oriented substantially transversely to the raking direction  118 , and each tooth of the plurality of rake lock teeth  112  is disposed substantially transversely to a longitudinal axis  166  defined by the steering column  116 . In an exemplary embodiment, the raking direction  118  is substantially transverse to a longitudinal axis  166  defined by the steering column  116 . In an exemplary embodiment, the rake lock control shaft  136  is arranged substantially transversely to a longitudinal axis  166  of the steering column  116 , and the raking direction  118  is substantially vertical. 
     In an exemplary embodiment, the rake lock bracket  104  provides a guide structure on which a tooth lock cartridge  176  may ride. The tooth lock cartridge  176  has a guide pocket  174  that cooperates with the guide structure so as to maintain the position of the tooth lock rotation axis  120 , the driver rotation axis  124 , and the longitudinal axis of the rake lock control shaft  136 . In an exemplary embodiment, the driver  122  is configured to key to one or more flats or eccentricities of the rake lock control shaft  136 . Accordingly, the driver  122  may be configured so as to define an eccentric hole  168  through which the rake lock control shaft  136  is disposed. The driver  122  may define a driver control arm  172  configured to contact and cooperate with actuation feature  126  of the tooth lock  114  so as to cause the toothed peripheral edge  140  on tooth lock  114  to disengage from the plurality of rake lock teeth  112  on rake lock bracket  104 . Accordingly, whenever the rake lock control shaft  136  is rotated in an adjustment direction  170  sufficiently to cause driver  122  to contact actuation feature  126  of tooth lock  114 , the position lock  102  may facilitate adjustment of the steering column  116 . 
     It should be noted that the tooth lock  114  is configured to rotate freely about the rake lock control shaft  136 . In an exemplary embodiment, the spring  130  engages the driver  122  at a recess  180  in the driver control arm  172 . The spring  130  also engages the tooth lock  114  by a biasing hole  106 . When the toothed peripheral edge  140  on the tooth lock  114  contact the plurality of rake lock teeth  112  on the rake lock bracket  104 , tension develops in the spring  130 , tending to bias the tooth lock  114  toward engagement of additional teeth, however, further rotation of the driver  122  and its driver control arm  172  are not inhibited. It should be appreciated that a position lock  102  such as described herein may be implemented on one or both sides of a steering column  116 . 
       FIG. 4  illustrates portions of an exemplary position lock  102  in a locked mode. As shown in  FIG. 4 , the tooth lock  114  is configured for engaging, upon rotation in the locking direction  134 , at least one tooth of the plurality of rake lock teeth  112  so as to selectively resist translation of the tooth lock  114  and the steering column  116  in the raking direction  118 . 
       FIG. 5  illustrates portions of an exemplary position lock  102  in an adjustment mode. As shown in  FIG. 5 , the tooth lock  114  is configured for disengaging, upon rotation in an adjustment direction  170 , from the at least one tooth of the plurality of rake lock teeth  112  so as to selectively facilitate translation of the tooth lock  114  and the steering column  116  in the raking direction  118 . More specifically, as shown in  FIG. 5 , driver control arm  172  of driver  122  contacts actuation feature  126  on tooth lock  114 , thereby causing toothed peripheral edge  140  on tooth lock  114  to disengage from the plurality of rake lock teeth  112  on rake lock bracket  104 . 
     Thus, the present invention provides a locking mechanism that avoids many of the problems inherent in existing systems. In accordance with an exemplary embodiment of the invention locking teeth are configured so as to roll or rotate into engagement such that the locking engagement of the teeth becomes tighter and more secure as forces to overcome the locking engagement are applied. The disclosed driver configuration enables decoupling of the actuation lever from the locking device. 
     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.