Abstract:
A position lock for a steering column assembly is provided. The position lock includes an outer cam. Also included is an inner cam defining a slotted aperture to receive a rake bolt operatively coupled to the outer cam, the slotted aperture facilitating shuttling movement of the rake bolt therein. Further included is a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. Yet further included is a pin extending through the inner cam and operatively coupled to the outer cam, and rotation of the outer cam facilitates movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application claims priority to U.S. Provisional Patent Application Ser. Nos. 62/018,264, filed Jun. 27, 2014, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The following description relates to steering columns for motor vehicles and, more specifically, to a rake lock mechanism 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 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. Other proposed solutions involve the use of frictions locks, which may provide more fine adjustments, but may sacrifice reliability, being susceptible to unintended releases (e.g., sliding adjustments, creep) under some loads. 
     Further, in a vehicle impact event, the steering column is configured to absorb energy of the impact to prevent or reduce injury to the operator due to collision with the steering wheel. In doing so, it is desired to further lock the rake position of the steering column to allow controlled energy absorption in such situations. In some steering column designs, during a collapse cycle, the column is designed to disengage the shaft and jacket assembly from the column mounting bracket. This allows the shaft and jacket assembly to shuttle forward in a vehicle, which allows the column to unclamp to facilitate internal collapse. At this point, rake lock needs to be maintained or re-established. 
     Accordingly, it is desirable to provide an energy absorbing rake lock assembly configured to establish rake lock during an impact event and to selectively fix and adjust 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 one exemplary embodiment of the present invention, a position lock for a steering column assembly is provided. The position lock includes an outer cam. Also included is an inner cam defining a slotted aperture to receive a rake bolt operatively coupled to the outer cam, the slotted aperture facilitating shuttling movement of the rake bolt therein. Further included is a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. Yet further included is a pin extending through the inner cam and operatively coupled to the outer cam, and rotation of the outer cam facilitates movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position. 
     In another exemplary embodiment of the present invention, a position lock for a steering column assembly is provided. The position lock includes an outer cam. Also included is an inner cam defining an aperture to receive a rake bolt operatively coupled to the outer cam, the aperture sized to correspond to an outer surface of the rake bolt. Further included is a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. Yet further included is a pin extending through the inner cam and operatively coupled to the outer cam, the outer cam causing movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked position. Also included is a lower jacket defining a slot to receive the rake bolt. 
     In yet another exemplary embodiment of the present invention, a steering column assembly is provided and includes a steering column. Also included is a rake lock bracket coupled to the steering column. Further included is a position lock. The position lock includes an outer cam. The position lock also includes an inner cam defining a slotted aperture to receive a rake bolt operatively coupled to the outer cam, the slotted aperture facilitating shuttling movement of the rake bolt therein. The position lock further includes a tooth lock operatively coupled to the inner cam, the tooth lock rotatable between an unlocked position and a locked position. The position lock yet further includes a pin extending through the inner cam and operatively coupled to the outer cam, and rotation of the outer cam causing movement of the tooth lock out of engagement with the rake lock tooth wall when rotating between the locked position and the unlocked 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. 1A  illustrates a steering column assembly according to an embodiment of the disclosure; 
         FIG. 1B  illustrates another aspect of the steering column assembly of  FIG. 1A ; 
         FIG. 2  illustrates another aspect of the steering column assembly of  FIGS. 1A and 1B ; 
         FIG. 3  illustrates an alternative embodiment of the steering column assembly shown in  FIGS. 1A-2 ; 
         FIG. 4A  illustrates another alternative embodiment of the steering column assembly shown in  FIGS. 1A-2 ; 
         FIG. 4B  illustrates another aspect of the embodiment of  FIG. 4A ; 
         FIG. 5  illustrates yet another alternative embodiment of the steering column assembly shown in  FIGS. 1 and 2 ; 
         FIG. 6  illustrates yet another alternative embodiment of the steering column assembly shown in  FIGS. 1 and 2 ; and 
         FIG. 7  illustrates yet another alternative embodiment of the steering column assembly shown in  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION 
     During typical usage, an eccentric cam is unlocked via feature(s) on a rake lever and or feature(s) on the rake bolt, to allow for rake adjustment of a steering column. Once the desired rake position of the steering column is achieved, the steering column may be relocked via the rake lever. If the lever is in the locked position, the eccentric cam rests against a column mounting tooth configuration, therefore maintaining a constant locked condition. 
     During a collapse cycle event, the eccentric tooth maintains its locked position while allowing the rake lever and bolt, as well as the jacket assembly to shuttle forward, therefore releasing column clamp pressure. This described shuttling event is facilitated by means of a cylindrical boss feature on the eccentric mounting plate to which the eccentric cam pivots. The boss has a slot at or near center, of which, allows the rake bolt to pass through and allows for shuttling of the rake bolt during the collapse event. These components may also be configured so the boss resides on the eccentric cam, with a slot at or near center of the boss, and the mating plate would have a round hole in which the eccentric cam boss will mate. As a result, the eccentric toothed cam is configured to wind up and create binding/locking in the rake direction. In addition, reaction feature(s) may be added to existing component(s) and or additional component(s) to further provide added binding/locking. 
     Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same,  FIGS. 1A, 1B and 2  illustrate an exemplary steering column assembly  100 . As shown in  FIGS. 1A and 1B , 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. 
     Position lock  102  is configured for selectively resisting or facilitating raking adjustment of a steering column  116  of a vehicle and 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  FIGS. 1 and 2 , an exemplary rake lock bracket  104  has a rake lock tooth wall  108  that bounds a control slot  178  ( FIG. 1A ) 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 (e.g., a locking tooth  114 ) 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 or bolt  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  or an adjustment direction  170  (see  FIG. 1A ). 
     In an exemplary embodiment, an outer 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 . 
     An inner cam  176  may be used in connection with the outer cam  110  to limit the absolute range of rotation of the rake lock control shaft  136 . For example, a pin  150  may be pressed into a slot  152  formed in outer cam  110 , and pin  150  may then extend through a slot  154  formed in inner cam  176  to interact with tooth lock  114 . As illustrated, as lock arm  184  rotates in the adjustment direction, pin  150  engages a first tooth lock projection  156  to rotate tooth lock  114  away from engagement with tooth wall  108 . Similarly, as lock arm  184  rotates in the locking direction  134 , pin  150  is engageable with a second tooth lock projection  158  to rotate tooth lock  114  into engagement with tooth wall  108 . Alternatively, or in combination with engagement of the pin  150  and second tooth lock projection  158 , the pin may allow a spring load to rotate with the tooth lock  114 . Driver  122  may interact with the tooth lock projections  156 ,  158  in a similar manner. 
     In addition, the inner cam  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. 1B , the driver  122  is supported for translation with the tooth lock  114 . 
       FIG. 2  illustrates portions of an exemplary position lock  102  in both a locked mode and unlocked mode. As shown in  FIG. 2 , 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. 2  illustrates portions of an exemplary position lock  102  in the unlocked mode or adjustment mode. As shown in  FIG. 2 , 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 . In addition, a driver control arm  172  of driver  122  contacts first projection  156  on tooth lock  114 , thereby causing a toothed peripheral edge  140  on tooth lock  114  to disengage from the plurality of rake lock teeth  112  on rake lock bracket  104 . 
     In the exemplary embodiment, the inner cam  176  includes a cylindrical boss  160  and a slotted bolt opening  162  to facilitate forward translation of rake bolt  136  therein. Tooth lock  114  is positioned over and rotates about the cylindrical boss  160  such that tooth lock  114  may engage tooth wall  108  and maintain engagement therewith as rake bolt  136  shuttles or translates forward in slotted bolt opening  162 . For example, during a crash event, lever  184 , bolt  136 , outer cam  110 , and pin  150  move forward in the direction of arrow  164  ( FIG. 1B ), which allows shuttling thereof and release of the column clamping device  104  to release so an energy absorption mechanism (e.g., a roll strap) may take effect. As such, slotted opening  162  enables rake bolt  136  to shuttle without interrupting the engagement between tooth lock  114  and tooth wall  108 . 
     The clamping device  104  surfaces that engage the steering column  116  may be angled along the clamp path. Such angling may be employed to facilitate the start of collapse, provide clamp pressure relief, and/or cushion impact loads at a travel stop. It is to be appreciated that all or fewer of the clamp surfaces may be angled. 
       FIG. 3  illustrates an alternate position lock  202  that is similar to the position lock  102  except inner cam  176  includes a post  204  to receive the spring  130 . In addition, the inner cam  176  and tooth lock  114  include respective apertures  206  and  208  to receive a portion of the spring  130 , as shown in  FIG. 3 . 
       FIG. 4  illustrates an alternate position lock  302  that is similar to the position lock  102  except inner cam  176  includes a post  304  to receive the spring  130 . In addition, the inner cam  176  and tooth lock  114  include respective apertures  306  and  308  to receive a portion of the spring  130 , as shown in  FIGS. 4A and 4B . 
       FIG. 5  illustrates an alternate position lock  402  that is similar to the position lock  102  except it includes an inner cam  476 , a tooth lock  414 , and a pin  450 . Inner cam  476  includes a cylindrical boss  460  that receives a flange  480  of tooth lock  414  to facilitate rotation of tooth lock  414  therein. Pin  450  includes a first projection  452  and a second projection  454 . First projection  452  is positioned within a slot  456  formed in outer cam  110 , and second projection  454  is positioned within a slot  458  formed in tooth lock  414 . As such, rotation of outer cam  110  engages first projection  452 , which rotates pin  450  and causes rotation of tooth lock  414  into and out of engagement with tooth wall  108 . 
       FIG. 6  illustrates an alternate position lock  502  that is similar to the position lock  102  except it includes an inner cam  576 , a tooth lock  514 , and a pin  550 . Inner cam  576  includes a cylindrical bore  560  that receives the spring  130  and a flange  580  of tooth lock  514  to facilitate rotation of tooth lock  514  therein. Pin  550  includes a first projection  552  and a second projection  554 . First projection  552  is positioned within a slot  556  formed in outer cam  110 , and second projection  554  is positioned within a slot  558  formed in tooth lock  514 . As such, rotation of outer cam  110  engages first projection  552 , which rotates pin  550  and causes rotation of tooth lock  514  into and out of engagement with tooth wall  108 . 
       FIG. 7  illustrates an alternate position lock  602  that is similar to the position lock  102  and similar reference numerals are employed for corresponding elements. The inner cam  176  of position lock  602  includes a slot bolt opening  662  that is not slotted as is the case with position lock  102 . Rather, the slot bolt opening  662  is dimensioned to correspond to the outer dimension of rake bolt  136 . Such dimensioning results in a tight, fitted relationship between the inner cam  176  and the rake bolt  136 . Rather than having the rake bolt  136  move forward relative to the jacket during shuttling of the jacket, the rake bolt does not move forward relative to the jacket. In the illustrated embodiment, the rake bolt moves with the jacket due to at least one slot  650  defined by the lower jacket, the rake bolt  136  extending through the slot(s)  650 . This assembly allows forward motion of the lower jacket during an energy absorption event, without requiring the rake bolt  136  to move forward. In this embodiment, the rake bolt  136  remains stationary in the fore-aft direction and is fully piloted by the inner cam  176 . 
     The systems and methods described herein may function within small package environments with a limited number of engaged teeth. Further, design options also exist with a stationary bolt axis among other moving components to engage (e.g., lower jacket  199 ). 
     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.