Abstract:
A steering column tilt adjusting system for releasably locking a steering column assembly. The pawl is pivotally coupled to the rack and may be pivotally and slidably moved between fully compressed and fully extended positions. The system includes a pawl, a rack, and a pair of side slide plates. Each of the pawl and the rack support a set of rack teeth. The pawl and rack, which are slidable relative to one another, permit adjustment of the system to a fully compressed locked position (teeth of the pawl engaging the teeth of the rack), a fully compressed unlocked position (the teeth of the pawl and those of the rack are not engaged), a fully extended unlocked position (the teeth are not engaged) or a fully extended locked position (the teeth of the pawl engaging the teeth of the rack). In operation, the length of the adjustment system is unlocked, adjusted and relocked to cause the steering column steering wheel to be repositioned as the driver wants.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a steering column tilt adjusting system. More particularly, the present invention relates to an apparatus for releasably locking and unlocking a tilt steering column.  
       BACKGROUND OF THE INVENTION  
       [0002]     Steering columns with tilt adjustments have been used on motor vehicles for many years. A variety of adjustment mechanisms have been used on the steering columns. U.S. Pat. Nos. 6,481,310 and 6,591,709 describe two such systems. Many prior art adjustment mechanisms are complex and require numerous parts. Thus, there is needed a simplified adjustment mechanism.  
       SUMMARY OF THE INVENTION  
       [0003]     The invention is a steering column tilt adjusting system that includes dual toothed racks that are locked and unlocked through profiled slots with pins or arms. These pins or arms are attached to sliding plates that contain the racks to create a self-contained tilt locking system. The length of the device is unlocked, adjusted and relocked to cause the steering column steering wheel to be repositioned as the driver wants. More specifically, steering column tilt adjusting system releasably locks a steering column assembly. The pawl is pivotally coupled to the rack and may be pivotally and slidably moved between fully compressed and fully extended positions. The system includes a pawl, a rack, and a pair of side slide plates. Each of the pawl and the rack support a set of rack teeth. The pawl and rack, which are slidable relative to one another, permit adjustment of the system to a fully compressed locked position (teeth of the pawl engaging the teeth of the rack), a fully compressed unlocked position (the teeth of the pawl and those of the rack are not engaged), a fully extended unlocked position (the teeth are not engaged) or a fully extended locked position (the teeth of the pawl engaging the teeth of the rack). In operation, the length of the adjustment system is unlocked, adjusted and relocked to cause the steering column steering wheel to be repositioned as the driver wants.  
         [0004]     In one embodiment, titling of the steering column may be achieved by moving an actuation lever by manually pushing or pulling a column tilt lever handle or other similar device. The tilting of the steering column may also be achieved by electrically activating an actuation device of the type described above. The actuation lever is held in the unlocked position, which drives a pair of side slide plates to move and disengage the pawl and rack teeth. The steering wheel is then free to be repositioned. For example, the steering wheel may be repositioned manually, electrically or using pyrotechnics. The steering column is then relocked by releasing the actuation lever and allowing a spring to slide the offset slide and the flat slide plate so as to re-engage the pawl and rack teeth. One of ordinary skill in the art will appreciate that the spring may be replaced by known devices capable of providing the locking force between the pawl and rack teeth. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]     Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, wherein:  
         [0006]      FIG. 1  is a perspective view of a steering column assembly having a tilt adjusting apparatus constructed in accordance with the teachings of the present invention;  
         [0007]      FIG. 2   a  is a side view of the steering column assembly of  FIG. 1 ;  
         [0008]      FIG. 2   b  is a plan view of the steering column assembly of  FIG. 1 ;  
         [0009]      FIG. 3  is an exploded view of the steering column tilt adjusting apparatus of  FIG. 1 ;  
         [0010]      FIG. 4  is a perspective view showing an assembly view of the steering column tilt adjusting apparatus of  FIG. 1 ;  
         [0011]      FIG. 5  is an assembly view of the steering column tilt adjusting apparatus shown in  FIG. 1 , illustrating the position of the flat slide;  
         [0012]      FIG. 6  is a plan view of the steering column tilt adjusting apparatus of  FIG. 1  illustrating the relationship between the offset slide and the flat slide;  
         [0013]      FIG. 7  is a perspective view of the steering column tilt adjusting apparatus of  FIG. 1  illustrating pawl teeth in meshing engagement with the rack teeth and the coupling of the pawl and the rack;  
         [0014]      FIG. 8  is an elevation view of the assembly shown in  FIG. 7 , illustrating the steering column tilt adjusting apparatus in the fully compressed and locked position.  
         [0015]      FIG. 9  is an elevation of the assembly shown in  FIG. 7 , illustrating the steering column tilt adjusting apparatus in the fully compressed unlocked position;  
         [0016]      FIG. 10  is an elevation of the assembly shown in  FIG. 7 , illustrating the steering column tilt adjusting apparatus in the fully extended unlocked position;  
         [0017]      FIG. 11  is an elevation of the assembly shown in  FIG. 7 , illustrating the steering column tilt adjusting apparatus in the fully extended locked position;  
         [0018]      FIG. 12  is a perspective view of the steering column having a tilt adjusting apparatus shown in  FIG. 1  illustrating the steering column in the “tilt-up” position;  
         [0019]      FIG. 13  is a perspective view of the steering column having a tilt adjusting apparatus shown in  FIG. 1  illustrating the steering column in the “tilt-down” position;  
         [0020]      FIG. 14  is an elevation view of another embodiment of a steering column tilt adjusting apparatus formed in accordance with the teachings of this invention;  
         [0021]      FIG. 15  is a top plan view of the steering column tilt adjusting apparatus shown in  FIG. 14 ; and  
         [0022]      FIG. 16  is a section view illustrating the contact points between meshing teeth. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     A detailed description of the present invention is described herein with reference to the accompanying drawing figures. Terms of reference such as “top,” “bottom,” “front,” “back,” or “side” are used to facilitate an understanding of the present invention in view of the accompanying figures. The identified reference terms or other similar terms are not intended to be limiting, and one of ordinary skill in the art will recognize that the present invention may be practiced in a variety of spatial orientations without departing from the spirit and scope of the invention.  
         [0024]     With reference to  FIGS. 1 and 2   a  of the drawings, a steering column tilt adjusting system constructed in accordance with the teachings of the present invention is generally indicated by reference numeral  100 . The steering column tilt adjusting system  100  is illustrated in operative association with a portion of a steering column assembly  10  having a steering wheel  16  coupled to the steering column shaft  12  using known techniques.  
         [0025]     For example, with reference to  FIGS. 1 and 2   a  of the drawings, the steering column tilt adjusting system constructed in accordance with the teachings of the present invention is generally indicated by reference numeral  100 . The steering column tilt adjusting system  100  is illustrated in operative association with a steering column assembly  10  having a steering column shaft  12  mounted in a housing  14 , with a steering wheel  16  on the upper end of the steering column shaft  12 . As shown in  FIG. 2   b,  the steering column housing  14  extends between a pair of trunnions  18  that are formed on a support structure  20  and is pivoted to the trunnions  18  by horizontal pivots  22  for vertical adjustment about an axis perpendicular to the longitudinal center line of the vehicle and of the steering column shaft  12 . The pivotal support for the housing  14  permits the steering column  12  to be adjusted vertically to a position desired by the vehicle operator, but within a range in which the steering column extends at an angle generally upwardly and downwardly from the motor vehicle. A coil spring  24  is secured at its ends to the support structure  20  and to the housing  14  and urges the housing  14  to swing upwardly to a limiting position making ingress to and egress from the vehicle easier for the vehicle operator. U.S. Pat. No. 6,591,709 describes a similar method for coupling a steering column tilt lock apparatus to a vehicle, the discussion of which is incorporated herein by reference.  
         [0026]      FIG. 3  shows an exploded view of the steering column tilt adjusting system  100  built in accordance with the teachings of this invention. As best seen in  FIG. 3 , the steering column tilt adjusting system  100  includes a rack  102 , a pawl  104 , an offset slide  106  and a flat slide  108 .  
         [0027]     As best seen in  FIG. 3 , the rack  102  includes a first trunnion  110 , a plurality of teeth  112  and a locking cam  114 . The first trunnion  110  defines a first pivot aperture  116 . In the particular example provided, the rack  102  has a gooseneck configuration, wherein the teeth  112  are spaced axially apart from the first trunnion  110 . The locking cam  114  is defined by a portion of the rack  102 . As illustrated, the locking cam  114  defines slots  122  and  124 , as best seen in  FIG. 3 . Rack  102  also includes a slot  120  that supports a mounting pin  143  such that the mounting pin  143  couples the steering column tilt adjusting system  100  to the steering column assembly  10 .  
         [0028]     As best seen in  FIG. 3 , the pawl  104  includes a body  126 , and the body  126  is illustrated to include a U-shaped portion  128 . As best seen in  FIG. 3 , the U-shaped portion  128  defines a pair of trunnions  130 ,  132  that are positioned on opposite sides  134 ,  136  of the body  126 . The trunnions  130 ,  132  include an aperture  138  that is configured to receive a bushing  140 ,  142 , respectively. When assembled, the bushings  140 ,  142  will receive and support a mounting pin  143 , as best seen in  FIGS. 1 and 2 . The mounting pin  143  couples the pawl  104  to the rack  102  in a manner that permits pivotal and sliding motion between the pawl  104  and the rack  102 .  
         [0029]     The body  126  also includes an elongated member  144  that extends outwardly in a direction opposite the trunnions  130 ,  132 . The elongated member  144  supports a plurality of teeth  146 . The body  126  also defines a slot  148 , as best seen in  FIGS. 3, 4  and  8 - 11 , that is offset from and below the teeth  146 .  
         [0030]     As best seen in  FIGS. 3 and 4 , the offset slide  106  includes a body portion  152  that includes a flat plate portion  154  and an offset flanged-shaped portion  156  joined to the flat shaped portion by an outwardly projecting wall  158 . As illustrated, the body portion  152  may be integrally formed.  
         [0031]     The flat plate portion  154  defines openings  160 ,  162 , and  164 , which receive, respectively, coupling pins  150 ,  153  and  155 , as best seen in  FIG. 6 . The offset flanged-shaped portion  156  also defines an opening  166 . As best seen in  FIGS. 3, 4  and  8 - 11 , this arrangement slidably couples the pawl  104  and the rack  102 .  
         [0032]     As best seen in  FIGS. 3 and 5 , the flat slide  108  includes a body  176 . As illustrated the body  176  is a rectangular plate. The body  176  defines three openings  178 ,  180  and  182 , wherein openings  178  and  182  align, respectively, with the openings  122  and  124  defined by the rack  102 . As best seen in  FIG. 6 , the openings  178 ,  180  and  182  receive mounting pins  153 ,  155  and  150  such that the joined parts are permitted sliding and pivotal movement relative to one another.  
         [0033]     The components of the steering column tilt adjusting system  100  can be formed for example of plastic, powered metal, stamped or machine steel materials. Non-ferrous or plastic materials can be used for low load applications. However, it will be appreciated by one of ordinary skill in the art that the material requirements may vary depending on the application and the environment in which the steering column tilt adjusting system  100  may be used.  
       Assembly and Operation  
       [0034]     The steering column tilt adjusting apparatus  100  may be installed in a steering column using two pivot pins or bolts or pivot sockets that support tensile and compressive loads. As best seen in  FIGS. 1, 2   a  and  2   b,  the steering column tilt adjusting apparatus  100  may be coupled to the steering column assembly  10  by inserting a mounting pin  145  in the first coupling aperture  116  ( FIG. 3 ) defined by the rack  102  so as to couple the rack  102  to the steering column assembly  10 . As previously discussed, the mounting pin  143  couples the pawl  104  to the rack  102  in a manner that permits pivotal and sliding motion between the pawl  104  and the rack  102 . The mounting pin  143  also couples the steering column tilt adjusting apparatus  100  to the steering column assembly  10 .  
         [0035]     Turning to  FIG. 3 , the steering column tilt adjusting apparatus  100  may be operated by coupling an actuation lever (not shown), cable or other known actuation means or device to the offset slide  106 . More specifically, the actuation lever may be supported in an aperture  166  formed in the offset slide  106  using techniques known to one of ordinary skill in the art. The actuation lever pushes against the inner surface of aperture  166 , causing movement of the offset side plate  106  and the flat slide plate  108  along the axis of the rack  102  and pawl  104 . In one embodiment, the connection point for the actuation lever is concentric with the pivot point in the tilt head.  
         [0036]     In one embodiment, titling of the steering column may be achieved by pushing or pulling the actuation lever. The lever is held in the unlock position, which drives the offset slide and the flat slide to move and disengage meshed rack and pawl teeth  146 ,  112 , respectively. The steering wheel  16  is then free to be repositioned. For example, the steering wheel  16  may be repositioned in either the tilt-up or tilt-down positions shown in  FIGS. 12 and 13  or any desirable position therebetween.  
         [0037]     The travel of the steering column assembly  10  may be limited by the configuration of the slot  120  defined by the rack  102  and the size of a mounting pin 143 . For example, when the steering column assembly  10  is repositioned, the pin  143  will strike against the end of the slot  120 , thus acting as a stop in either direction of travel along the slot  120 . The steering column assembly  10  is then relocked by releasing the tilt lever and allowing a spring  24  ( FIG. 2   a,    2   b ) to slide the offset slide plate  106  so as to re-engage the teeth  146 ,  112 .  
       Alternative Embodiment  
       [0038]      FIG. 14  illustrates another embodiment of a steering column tilt adjusting system  200  formed in accordance with the teachings of the present invention. The function and operation of the steering column tilt adjusting system  200  are identical to that described for the steering column tilt adjusting system  100 . However, the physical configuration of the components comprising the steering column tilt adjusting system  200  is slightly different. As best seen in  FIG. 14 , the steering column tilt adjusting system  200  includes a pawl  202 , a rack  204  and a pair of side slide plates  230 ,  232 .  
         [0039]     As best seen in  FIG. 14 , the pawl  202  includes an elongated body  220 . The pawl body  220  defines a trunnion mount  222 , a plurality of pawl teeth  212 , and a slot  218 . The trunnion  222  defines an opening  225  for receiving a bushing. In one embodiment, the trunnion  222  may be coupled to the steering column so as to permit rotation of the pawl relative to the steering column.  
         [0040]     As shown in  FIG. 14 , the rack  204  includes an elongated body  210 . The rack body  210  includes a distal end that defines a trunnion mount  224 , a slot  226  and a C-shaped end  216  formed at the distal end of the body  210 . The trunnion mount  224  defines an opening  227  for receiving a bushing. The C-shaped end defines an inner surface  228 .  
         [0041]     The steering column tilt adjusting system  200  also include side slide plates  230 ,  232 , as best seen in  FIGS. 14 and 15 . The side slide plates  230 ,  232  are virtually mirror images, except, as best seen in  FIG. 14 , that the plate  230  includes an opening  248  for receiving an end of an actuation lever (not shown). Each plate  230 ,  232  defines openings  234 ,  236 ,  238 . When the side slide plates  230 ,  232  are assembled, the openings  234 ,  236 ,  238  in each plate are aligned axially. Each opening  234 ,  236 ,  238  supports a pin  240 ,  242 ,  244 , respectively, for coupling the respective side slide plate  230 ,  232  to the pawl  202  and rack  204  as best seen in  FIG. 14 . For example, in one embodiment, the pins  240  and  242  are received in openings  234  and  236  formed in plate  230 , the slot  226 ,  231 , respectively, formed in the rack  204  and finally the respective openings  234  and  236  of the plate  232 . The pin  244  is received in opening  238  formed in plate  230 , the slot  218  formed in the pawl  202  and in the opening  238  of the plate  232 . The pins  240 ,  244 ,  246  are received in the respective slots  218 ,  226  and the openings  234 ,  236 ,  238  so as to permit the plates  230 ,  232  to slide along the slots  218 ,  226 .  
         [0042]     In the illustrated embodiment, when the side slide plates  230 ,  232  are assembled as described, the pawl teeth  212  releasably engage the rack teeth  214 . The trunnion mount  222  also nests in the C-shaped end  216  at the inner surface  228 .  
       Assembly and Operation  
       [0043]     The steering column tilt adjusting system  200  is coupled to the steering column assembly  10  in the manner previously described herein and as described in U.S. Pat. No. 6,591,709, incorporated herein by reference, and using techniques known to one of ordinary skill in the art. With reference to  FIGS. 1, 2   a,    2   b  and  14  for example, in an alternative method of coupling the steering column tilt adjusting system  200  to a steering column, the pawl trunnion mount  222  may receive a pin  143  through opening  225  that couples the pawl trunnion mount  222  to the steering column assembly  10 . The rack trunnion mount  224  may receive a pin  145  through opening  227  that pivotably couples the rack trunnion mount  224  to the steering column assembly  10 . One of ordinary skill in the art will appreciate that the pawl  202  and rack  204  may be assembled in the steering column such that the pawl  202  is pivotably coupled to the steering column assembly  10 , and the rack  204  is coupled to the fixed portion of the steering column assembly  10 .  
         [0044]     In the embodiment shown in  FIGS. 14 and 15 , the steering column tilt adjusting system  200  is operated by applying a force to the actuation lever (not shown). One of skill in the art will appreciate that the actuation lever (not shown) may be replaced by an actuation cable, hydraulic piston assembly or other devices for applying a forces on the side slide plates  230 ,  232  so as to permit movement of the side slide plates  230 ,  232  to slide along the axis of the slots  218 ,  226 .  
         [0045]     The actuation lever may be supported in an aperture  248  formed in the side slide plate  230  using techniques known to one of ordinary skill in the art. The actuation lever pushes against the inner surface of  248 , causing the side slide plates  230 ,  232  to move along the axis of the rack  204  and pawl  202 .  
         [0046]     By applying pressure to the actuation lever, the side slide plates  230 ,  232  are permitted to slide along the axis of slots  218  and  226  to the unlocked position. This action permits the pawl teeth  212  and the rack teeth  214  to disengage (unlock). Once the side slide plates  230 ,  232  are slid to the unlocked position, the rack  204  may slide along the axis of the pawl  202 . Once the steering column assembly  10  is in the desired position, a force is applied the lever causing the side slide plates  230 ,  232  to be slid to the locked position. This action results in the meshing engagement of the pawl and rack teeth,  212 ,  214 .  
         [0047]     Finally, the steering column tilt adjusting system  200  may be shipped with a shipping pin  246  inserted in opening  250  to prevent movement of the side slide plates  230 ,  232  during shipping.  
         [0048]     The present invention as illustrated herein as exemplary embodiments  100  and  200  provides several advantages over prior art steering column tilt adjusting systems. For example, one advantage is that the opposing pawl and rack teeth geometry is set up such that the teeth surfaces that support the high deceleration loads created in a crash event are adjusted towards or are perpendicular to the load path in the rack and pawl. Another illustrative advantage is that the rack and pawl teeth surfaces may be designed such that the deceleration loads are intended to force the steering column tilt adjusting system into locking engagement during a crash event. A further illustrative advantage is that the locking loads applied to lock the rack and pawl teeth may be tunable by adjusting the angle and/or configuration of the slots  122 ,  124 ,  148  ( FIG. 3 ) in the first embodiment and  218 ,  226 ,  231  ( FIG. 14 ) in the second embodiment. An additional advantage is that the profiled slots ( 122 ,  124 ,  148  in the first embodiment ( FIG. 3 ) and  218 ,  226 ,  321  in the second embodiment ( FIG. 14 )) in the pawl and rack may be tunable to allow the locking and unlocking lever efforts to be adjusted. As shown in  FIG. 16 , another advantage is that the rack and pawl teeth,  214 ,  212  may be configured to account for wear between contact points  252 . As the contact points  252  wear, the root  254  of the teeth moves closer to the tip  256  of opposing teeth. Therefore the teeth  214 ,  212  further engage to compensate for wear. In addition to self correcting for tooth wear, the present invention also permits the slots  226 ,  231  ( FIG. 14 ) to be configured to allow additional travel of the slide plates  230 ,  232  to accommodate wear in the teeth  212 ,  214 , pins  240 ,  242 ,  244 , and slots  218 ,  226 ,  231 . One of skill in the art will appreciate that the disclosed invention includes additional advantages that are not set forth above.  
         [0049]     Although a detailed description of the present invention has been disclosed, a person of ordinary skill in the art would realize, however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention.