Abstract:
An articulated, tiltable steering column and method for installing the same is provided. The steering column includes a locking mechanism for retaining upper and lower column members in selected positions of adjustment. The locking mechanism includes a rod received by and slidable along a longitudinal axis within a sleeve. A collar is journalled around the sleeve and includes diametrically opposed bores for receiving the shaft. A biasing member is secured on a first end to a mounting portion extending from the sleeve and is secured on a second end by the collar.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to tiltable steering column assemblies for motor vehicles, and more particularly to a rotary tilt mechanism having an improved locking mechanism.  
         BACKGROUND OF THE INVENTION  
         [0002]    Vehicle steering columns are often provided with a tiltable component that enables the steering wheel to be set at varying degrees of tilt, according to the desires and needs of different persons that might have occasion to drive a vehicle. Typically a manually operable lock mechanism is provided for retaining the steering wheel component in selected positions of tilt adjustment.  
           [0003]    In one conventional rotary tilt mechanism an externally threaded rod is provided including pivot connections incorporated on opposite ends. A sleeve encircles the rod and is biased into a locking relationship with the rod by a biasing member. A lever is incorporated on the steering column in which the driver may actuate to overcome the bias. Actuation of the lever allows the rod to move into an unlocked position whereby the rod may slidably translate within the sleeve toward a desired position of tilt. Once the steering wheel is pivoted into the desired position, the lever is disengaged and the sleeve is biased into a locked relationship with the rod.  
           [0004]    The biasing member conventionally is coupled on one end to an outer portion of the sleeve and on the other end to a pivot shaft. The pivot shaft transversely extends through passages incorporated on the sleeve and rod and operably connects to a lower stationary column member. In such a configuration wherein the biasing member is coupled to the pivot shaft, undesirable loads may be transferred to the passage walls formed on the sleeve and rod. Continued loads on the passage walls may encourage premature fatigue on the rod and sleeve.  
           [0005]    Generally, assembly of such a rotary tilt mechanism includes rotating the rod and sleeve against the bias to a position in which an axial slot formed on the rod is aligned with a transverse slot formed in the sleeve to create a mounting passage. Next, a shipping pin or “dummy pin” is disposed through the mounting passage to preclude the biasing member from rotating the rod and sleeve out of position. When the rotary tilt mechanism is prepared for installation in a vehicle, a pivot pin is inserted into the mounting passage thereby displacing the shipping pin from the mechanism.  
           [0006]    The rotary tilt mechanism of the present invention provides a configuration which minimizes loads transferred onto the passage walls while providing other improvements which increase the longevity and overall robustness of the mechanism.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides an articulated, tiltable steering column including an upper steering wheel column member, and a lower stationary steering column member, and a pivot connection between the upper and lower column members, whereby a steering wheel can be tiltably adjusted around the pivot connection to selected positions of adjustment. A locking mechanism retains the column members in selected positions of adjustment. The locking mechanism further includes a rod disposed between the column members. The rod is received by and slidable along a longitudinal axis within a sleeve. The rod and sleeve include a passage formed therein for receiving a shaft. A collar is journalled around the sleeve including diametrically opposed bores for receiving the shaft. A biasing member is secured on a first end to a mounting portion extending from the sleeve and secured on a second end by the collar. The biasing member provides a rotational bias on the sleeve.  
           [0008]    The present invention further provides a method of installing a rotary tilt mechanism in a motor vehicle. The rotary tilt mechanism includes a rod disposed within and selectively translatable along a longitudinal axis within a sleeve. The sleeve is rotatably biased around the rod by a biasing member. The tilt mechanism includes a first mounting shaft coupled to an upper steering wheel column member and a second mounting shaft coupled to a lower steering wheel column member. A collar is slid along the longitudinal axis of the sleeve to a predetermined location and engaged to a first end of the biasing member. The collar is then rotated in a direction of increased bias to a location allowing passages in the collar to align with passages on the sleeve and rod, thereby creating a mounting passage. A locking element is advanced along the sleeve to a position precluding the collar from rotating. One of the first and second mounting shafts is inserted through the mounting passage.  
           [0009]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limited the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0011]    [0011]FIG. 1 is a fragmentary side elevational view of a vehicle steering column having a tilt lock mechanism of the present invention installed thereon.  
         [0012]    [0012]FIG. 2 is a fragmentary sectional view taken along line  2 - 2  of FIG. 1.  
         [0013]    [0013]FIG. 3 is a sectional view taken along line  3 - 3  of FIG. 2.  
         [0014]    [0014]FIG. 4 is a transverse sectional view taken along line  4 - 4  of FIG. 3.  
         [0015]    [0015]FIG. 5 is a transverse sectional view taken along line  5 - 5  of FIG. 3.  
         [0016]    [0016]FIG. 6 is the sectional view of FIG. 5, showing the locking components in a different position of adjustment.  
         [0017]    [0017]FIG. 7 is an exploded perspective view of the rotary tilt mechanism of the present invention.  
         [0018]    [0018]FIG. 8 is a perspective view of the rotary tilt mechanism of the present invention.  
         [0019]    [0019]FIG. 9 is a bottom perspective view of the rotary tilt mechanism shown installed within a tilt lock vehicle steering column according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0021]    Referring to FIG. 1, there is shown a vehicle steering column assembly that includes a lower stationary column member  10  and an upper tiltable steering column member  12  connected together by a pivot connection  14 , whereby column member  12  is capable of tilting adjustment around the pivot connection axis. A steering wheel  16  is located at the upper end of column member  12 . The interior spaces within column members  10  and  12  are occupied by rotary shafts that are connected by a universal joint centered on the axis of pivot connection  14 . Steering wheel  16  is attached to the shaft located within column member  12 .  
         [0022]    The present invention is concerned with a locking mechanism for retaining column member  12  in selected positions of tilt adjustment. In FIG. 1, dashed lines show the downward limit of tilt adjustment for column member  12 . Column member  12  can be tilted upwardly from the full line position to a similar extent. Typically, column member  12  can be tiltably adjusted downwardly from its full line position by approximately thirteen degrees, and upwardly from its full line position by a similar number of degrees.  
         [0023]    The locking mechanism for retaining column member  12  in selected positions of tilt adjustment (up or down) includes an externally threaded rod  18  having a first pivot connection  20  to column member  12  and a second pivot connection  22  to column member  10 . By adjusting the location of the pivot connection  22  on the longitudinal axis  26  of rod  18  it is possible to vary the effective length of the rod  18  and the tilt angle of column member  12  around the axis of pivot connection  14 .  
         [0024]    Pivot connection  20  includes two parallel ears  21  extending downwardly from column member  12 , and a pivot shaft  23  extending transversely through ears  21  and the upper end of rod  18 . Pivot connection  22  includes a pivot shaft  24  extending between two parallel ears  25  depending from column member  10 . Pivot connection  22  further includes an axial slot  27  formed in rod  18 , such that shaft  24  extends transversely through the slot. Rod  18  can rotate on shaft  24 , and also slide longitudinally on the shaft  24  to vary the effective length of the rod, i.e. the distance between pivot connections  22  and  20 .  
         [0025]    Rod  18  is longitudinally stabilized on shaft  24  by means of a sleeve  29  that encircles the rod  18 . The sleeve  29  has two arcuate circumferential slots  31  engage shaft  24 , whereby the sleeve  29  can be rotated on rod  18  a limited distance around rod axis  26 . In the illustrated apparatus, slots  31  permit sleeve  29  to rotate approximately ninety degrees around rod axis  26 . FIG. 5 shows sleeve  29  at one limit of the sleeve rotational movement. FIG. 6 shows sleeve  29  at the other limit of the rotational movement.  
         [0026]    Rod  18  has two parallel flat side surfaces  33  extending the full length of the rod  18 , and two arcuate serrated surfaces  35  connecting flat surfaces  33 . The serrations form diametrically opposed external teeth on the rod  18 . The serrated arcuate surfaces  35  are centered on rod axis  24 . Flat surfaces  33  span through the serrated surfaces  35  such that serrated surfaces  35  do not overhang at an angle with respect to flat surfaces  33 .  
         [0027]    Sleeve  29  has two internal arcuate serrated surfaces  37  separated by two arcuate smooth surfaces  39 . The internal teeth formed by serrated surfaces  37  have the same pitch as the external teeth  35  on rod  18 , so that when sleeve  29  is rotated to the position depicted in FIGS. 4 and 5 the internal teeth on the sleeve mesh with the external teeth on rod  18 .  
         [0028]    When sleeve  29  is rotated to the position depicted in FIG. 4, the meshed teeth prevent axial movement of rod  18  within sleeve  29 . Slots  31  in the sleeve are in a circumferential plane that intersects the axial plane of slot  27  in rod  18 , whereby sleeve  29  prevents the rod from movement relative to pivot shaft  24 .  
         [0029]    When sleeve  29  is rotated in the direction of arrow A from the position depicted in FIG. 5 to the position depicted in FIG. 6, the internal teeth in sleeve  29  are out of mesh with the external teeth on rod  18 . Rod  18  can thereby be moved longitudinally (on rod axis  26 ) along shaft  24  a limited distance dictated by the length of slot  27 . Such movement of the rod  18  can be used to move pivot shaft  23  around pivot connection  14 , thereby adjusting the tilt angle of column member  12 .  
         [0030]    Referring to FIG. 1, pivot connection  20  is shown in two limit positions, i.e., a limit position  20 a, wherein rod  18  is advanced upwardly to tilt column member  12  upwardly; and a second limit position  20   b,  wherein rod  18  is retracted downwardly to tilt column member downwardly. Slot  27  limits the rod  18  movement. Rod  18  can have various adjusted positions between limiting positions  20   a  and  20   b.  The number of discrete rod positions is determined by the pitch distance for the teeth on rod  18  and sleeve  29 .  
         [0031]    During longitudinal movement of rod  18  within sleeve  29 , internal arcuate surfaces  39  on the sleeve act as bearings to maintain the rod in a centered position relative to the sleeve. For manufacturing reasons, each smooth arcuate surface  39  is formed by an arcuate insert member  40  installed within sleeve  29  after the sleeve has been machined to form the diametrically opposed serrated surfaces  37 . The exposed arcuate surfaces  39 , formed by inserts  40 , have a diameter that is the same as the diameter of the arcuate toothed surfaces  35  on rod  18 . When sleeve  29  is in the position depicted in FIG. 6, the arcuate smooth surfaces will function as bearing surfaces to maintain the sleeve  29  in a centered position on rod  18 ; i.e., the axis of sleeve  29  is coincident with the rod axis  26 . This is beneficial in that the rod  18  can be moved axially within the sleeve  29  without binding or cocking in the sleeve.  
         [0032]    Each arcuate insert  40  extends from the right end of sleeve  29  about one half the sleeve length. Inserts  40  are not visible in FIGS. 5 and 6 because the viewing plane for FIG. 5 is beyond the ends of the inserts.  
         [0033]    Sleeve  29  is rotated to the position depicted in FIG. 5 by a torsion coil spring  42 . As shown in FIGS. 1 and 2, end  43  of the torsion spring is anchored to collar or trunion  70 . The other end  45  of the torsion spring extends into a small hole  100  formed in an externally mounted snap ring  72 . Snap ring  72  is bounded on a first side circumferential wall  74 . A notch (not specifically shown) is incorporated in circumferential wall  76  to allow end  45  of torsion spring to gain access to snap ring  72 . The torsion coil spring  42  is wound so as to exert a counterclockwise biasing force on sleeve  29 , as the sleeve is viewed in FIG. 4.  
         [0034]    With continued reference to FIGS. 1, 2 and  7 , trunion  70  will be explained in greater detail. Trunion  70  is bounded on a first end by thrust wall  78  and on a second end by castle nut  80 . Trunion  70  includes diametrically opposed bores  82  incorporated therein. The diameter of the bores  82  is preferably generally equal to the width of pivot shaft  24 , whereby an interference fit is provided therebetween. Trunion  70  further includes an ear or dog  84  having a wall portion  86  tangentially extending from an outer wall  88  and forming a groove portion  90  between the outer wall  88  and the tangentially extending wall  86 . The groove portion  90  anchors the first end of the torsion spring  43  onto trunion  70 . The rotational force transmitted by torsion spring  42  onto trunion  70  is translated to pivot shaft  24 . In this manner, the interface fit between pivot shaft  24  and the diametrically opposed bores  82 , precludes any rotational biasing force to be absorbed by the walls of slot  27 . For additional support, the wall thickness of the trunion  70  near bores  82  is increased.  
         [0035]    During assembly, trunion  70  is advanced onto sleeve  29  until contacting thrust wall  92 . Upon engaging ear  84  of trunion  70  with second end  43  of torsion spring  42 , the trunion  70  is influenced in a clockwise direction as viewed in FIG. 5. Castle nut  80  is threadably advanced onto threads  94  of sleeve  29  to secure trunion  70  in a location revealing a continuous passage through the diametrically opposed bores  82  and the slot  27 . An adhesive, such as LOCTITE™, is applied to the contact wall of castle nut  80  to encourage a sound bond. Pivot shaft  24  is suitably inserted through the passage and castle nut  80  is backed off to allow for lash adjustment.  
         [0036]    The cooperation of castle nut  80  and thrust wall  92  secure trunion  70  in a position aligning bores  82 , slot  27  and slot  31  to allow pivot shaft  24  to be readily inserted during assembly through the passage without the need to remove a “dummy pin”, which would otherwise provide necessary alignment.  
         [0037]    With continued reference to FIG. 7 and additional reference to FIGS. 8 and 9, sleeve  29  is rotated to the position depicted in FIG. 6 by a manual cable means, referenced generally by numeral  49 . Cable means includes a flexible wire (small diameter cable)  50  having one end anchored at  52  to hook sleeve  102 . Hook sleeve  102  has a tooth engaging a retaining channel  110  formed on sleeve  29  to prevent relative rotation between the hook sleeve  102  and sleeve  29 . An end collar  108  is disposed on the ends of sleeve  29 . The flexible wire  50  extends partially around the grooved flange on sleeve  29 , and then around an arcuate guide  54  that is suitably attached to the undersurface of column member  10 .  
         [0038]    As shown in FIG. 1, cable means  49  extends rightwardly from hook collar  102  to an anchored connection  56  with an arm  57 . Arm  57  has a hub portion  58  that is rotatable on a shaft  60  extending laterally from column member  12 . The outer end of shaft  60  mounts a manually depressible handle  62 .  
         [0039]    Manual depression of handle  62  around the shaft  60  axis moves wire  50  in the arrow  61  direction (FIG. 1), such that the wire  50  rotates sleeve  29  in a clockwise direction as viewed in FIG. 5. When handle  62  is manually depressed, sleeve  29  is rotated from the position depicted in FIG. 5 to the position depicted in FIG. 6. When the manual pressure on handle  62  is removed, torsion spring  42  rotates sleeve  29  from the position shown in FIG. 6 to the position shown in FIG. 5.  
         [0040]    [0040]FIG. 5 depicts the normal position of sleeve  29 , wherein the external teeth on rod  18  are in mesh with the internal teeth on sleeve  29 . The sleeve is locked to rod  18  so that the rod  18  forms a rigid connection between shaft  23  on column member  12  and shaft  24  on column member  10 . Column member  12  is thereby retained in a fixed position relative to column member  10 .  
         [0041]    In order to change the tilt setting of column member  12  (up or down around pivot connection  14 ) handle  62  is manually depressed to rotate sleeve  29  from the position depicted in FIG. 5 to the position depicted in FIG. 6. The internal teeth on sleeve  29  are thereby moved out of mesh with the external teeth on rod  18 , as shown in FIG. 7. Column member  12  can then be freely rotated around the axis of pivot connection  14  to any desired tilted position within limits.  
         [0042]    When column member  12  is moved around the axis of pivot connection  14 , rod  18  slides freely along rod axis  26  to establish a new relation between slot  27  and shaft  24 . The effective length of rod  18  between shafts  23  and  24  is changed in accordance with the movement of column member  12 . With column member  12  in the new (desired) position, manual pressure on handle  62  is released, such that torsion coil spring  42  returns sleeve  29  to the position depicted in FIGS. 4 and 5. The internal teeth on sleeve  29  move into mesh with the external teeth on rod  18 , such that rod  28  is prevented from longitudinal axial movement along rod axis  26 . Sleeve  29  serves as a rigid connector between rod  18  and shaft  24 .  
         [0043]    When in the locked position, the internal teeth on sleeve  29  cannot inadvertently disengage from the external teeth on rod  18 . As shown in FIG. 4, rod  18  completely fills the vertical space within sleeve  29 . The sleeve  29  cannot vibrate in the vertical plane so as to disengage the meshed teeth.  
         [0044]    In any locked position, a relatively large number of teeth are in mesh. Rod  18  has teeth on both its upper surface and its lower surface. Also, the rod  18  and sleeve  29  have large cross section walls presented to the expected load forces (acting primarily parallel to rod axis  26 ). This arrangement also provides a high degree of adjustment with many tilt positions. In one embodiment, this design provides thirteen positions of adjustment.  
         [0045]    The illustrated locking mechanism can be constructed as a relatively small size assembly without greatly reducing its strength or ability to handle the expected load forces. As shown in the drawings, the locking mechanism is located externally relative to column members  10  and  12 , such that the locking mechanism can be modularized as a separate assembly capable of interchangeable use with a range of different steering columns without extensive tooling changes or structural modifications in the locking mechanism or steering column.  
         [0046]    The drawings show rod  18  as having an adjustment slot  27  and sleeve  29  cooperable with shaft  24  on the stationary column member  10 . However, the adjustment slot  27  and sleeve  29  could be relocated so as to interact with shaft  23  on movable column member  12 .  
         [0047]    Within the broader scope of the invention, it is believed that the illustrated locking mechanism could be used with movable and stationary members other than the steering column members.  
         [0048]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.