Abstract:
A steering column rotary tilt locking mechanism. The mechanism includes a rod pivotally interconnecting upper and lower column members and a sleeve supported about the rod. The rod and sleeve have selectively engageable surfaces. The sleeve has opposed slots with one end of each slot having axis offset from the other slot. Upon rotation of the sleeve, the sleeve moves out of perpendicularity relative to the shaft such that the slots bind against the shaft and the sleeve moves off center relative to the rod and binds thereagainst.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/365,340 filed on Mar. 18, 2002. 

   BACKGROUND 
   The present invention relates to tiltable steering column assemblies for automotive vehicles, and particularly to a lock mechanism for retaining the tilting component of the steering column in selected positions of adjustment. 
   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 the vehicle. Typically a manually operable lock mechanism is provided for retaining the steering wheel component in selected positions of tilt adjustment. 
   One such lock mechanism uses an elongated rod between the steering column components, in combination with a locking sleeve that encircles the rod to retain the rod in selected positions of adjustment. The rod and sleeve have mating teeth that are discontinuous in the circumferential plane, whereby the sleeve can be rotated around the rod axis to move the teeth into or out of mesh. 
   The sleeve grips the external surface of the rod, such that when the teeth are in mesh, the teeth are precluded from separation, even under high impact accident conditions when high forces might be imposed on the steering column components. 
   SUMMARY 
   The present invention relates to a steering column rotary tilt locking mechanism. The mechanism includes a rod pivotally interconnected upper and lower column members. A sleeve is supported about the rod for selective locking thereof. The rod and sleeve have selectively engageable surfaces. The sleeve has opposed slots through which a pivot shaft is received. The slots have offset linear axes such that upon rotation of the sleeve, the sleeve moves out of perpendicularity relative to the shaft such that the slots bind against the shaft and the sleeve moves off center relative to the rod and binds thereagainst. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a fragmentary side elevational view of a vehicle steering column having a tilt lock mechanism of the present invention installed thereon. 
       FIG. 2  is a side elevational view of a prior art sleeve. 
       FIG. 3  is a side elevational view of a first embodiment of the sleeve of the present invention. 
       FIG. 4  is a side elevational view of the sleeve of  FIG. 3  with a pin positioned in an unlocked position. 
       FIG. 5  is a sectional view taken along the line  5 – 5  in  FIG. 4 . 
       FIG. 6  is a side elevational view of the sleeve of  FIG. 3  with the pin positioned in a lock position. 
       FIG. 7  is a sectional view taken along the line  7 — 7  in  FIG. 6 . 
       FIG. 8  is a sectional view taken along the line  8 — 8  in  FIG. 1 . 
       FIG. 9  is a side elevational view of a second embodiment of the sleeve of the present invention. 
       FIG. 10  is a side elevational view of a third embodiment of the sleeve of the present invention. 
       FIG. 11  is a side elevational view of the slots of the sleeve of  FIG. 10  with the pin positioned in a lock position. 
       FIG. 12  is a cross-sectional view similar to  FIG. 8 . 
   

   The sleeve as illustrated in  FIGS. 3 ,  4 ,  6 ,  9 ,  10 , and  11  is not a three-dimensional representation, but instead is shown as a simplified flat structure to graphically present the slots. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will be described with reference to the accompanying drawing figures wherein like numbers represent like elements throughout. Certain terminology, for example, “top”, “bottom”, “right”, “left”, “front”, “frontward”, “forward”, “back”, “rear” and “rearward”, is used in the following description for relative descriptive clarity only and is not intended to be limiting. 
   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 locking mechanism for retaining column member  12  in selected positions of tilt adjustment (up or down) comprises 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 and the tilt angle of column member  12  around the axis of pivot connection  14 . 
   Pivot connection  20  comprises 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  comprises 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, to vary the effective length of the rod, i.e. the distance between pivot connections  22  and  20 . 
   Rod  18  has two parallel flat side surfaces  33  extending the full length of the rod, and two arcuate serrated surfaces  35  connecting flat surfaces  33 . The serrations form diametrically opposed external teeth on the rod. The serrated arcuate surfaces  35  are centered on rod axis  26 . 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   a  and  31   b  embracing shaft  24 , whereby the sleeve can be rotated on rod  18  a limited distance around rod axis  26 . In the illustrated apparatus, slots  31   a  and  31   b  permit sleeve  29  to rotate approximately ninety degrees around rod axis  26 . 
   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 on rod  18 , so that when sleeve  29  is rotated to a lock position, the internal teeth on the sleeve mesh with the external teeth on rod  18 . When sleeve  29  is rotated to the position with the internal teeth in sleeve  29  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 can be used to move pivot shaft  20  around pivot connection  14 , thereby adjusting the tilt angle of column member  12 . 
   When sleeve  29  is rotated, the meshed teeth and retention of the pivot shaft  24  generally prevent substantial axial movement of rod  18  within sleeve  29 . However, in prior art systems there is an undesirable amount of axial play or lash when the sleeve  29  is rotated to the locked position. Referring to  FIG. 2 , the slot  31  of the prior art assembly generally has parallel or tapered sides  50 . With parallel sides, not shown, the sides  50  must be spaced a distance greater than the circumference of the shaft  24  to provide a clearance to allow movement of the shaft  24  therethrough. Such clearance allows axial lash of the interlocked rod  18  and sleeve  29 . To address such, it had been proposed to taper the sides  50  as illustrated in  FIG. 2  such that the shaft  24  is rotated from a larger area X to a small area Y to prevent the axial lash relative to the shaft  24 . However, to facilitate sufficient rotation of the sleeve  29  such that the shaft  24  is received in the small area Y, there must be sufficient clearance between the rod teeth and the sleeve teeth. The clearance between the teeth again allows for axial lash of the interlocked rod  18  and sleeve  29 . 
   The slots  31   a  and  31   b  of a first embodiment of the present invention will be described with reference to  FIGS. 3–8 . As shown in  FIG. 3 , each slot  31   a ,  31   b  has substantially parallel side walls  51  spaced a distance slightly greater than the diameter of the shaft  24  to provide a slight clearance therefore. The slots  31   a  and  31   b  are offset relative to one another. That is, slot  31   a  has a linear axis A that is angled relative to the linear axis B of slot  31   b . The angular offset results in the first ends of the slots  31   a ,  31   b  having axes a 1  and b 1  that are co-axial and the opposite ends of the slots  31   a ,  31   b  having axes a 2  and b 2  that are axially offset from one another. 
   Referring to  FIGS. 4 and 5 , the first ends of the slots  31   a  and  31   b  are aligned on opposite sides of the sleeve  29 . The shaft  24  extends through the aligned portions axes a 1  and b 1  of the slots  31   a  and  31   b  when the sleeve is in the unlocked position and the sleeve  29  remains parallel to the shaft  24 . In this unlocked position, the rod  18  is extendable relative to the sleeve  29 . 
   Referring to  FIGS. 6 and 7 , as the sleeve  29  is rotated, the shaft  24  rides along the non-parallel slots  31   a  and  31   b  to the offset positions a 2  and b 2 , causing the sleeve  29  to move out of perpendicularity with the shaft  24 . The shaft  24  remains perpendicular with the rod  18 . This causes the shaft  24  to bind against opposed points  60  of the sleeve  29 , thereby preventing axial lash at the pivot location. Additionally, as illustrated in  FIG. 8 , since the sleeve  29  is forced out of perpendicularity relative to the shaft  24 , it is also forced off center relative to the rod  18 , thereby causing the threads of the rod  18  and sleeve  29  to bind at points  62 . As such, the binding action of the slots  31   a  and  31   b  causes simultaneous binding at the threads. 
   Sleeve  29  is rotated to the locked position by a torsion coil spring  42  encircling the sleeve. As shown in  FIG. 1 , end  43  of the torsion spring is anchored to shaft  24 . The other end  45  of the torsion spring extends into a small hole in an externally grooved flange  47  formed on sleeve  29 . The torsion coil spring  42  is wound so as to exert a biasing force on sleeve  29  toward the locked position. Sleeve  29  is rotated to the unlocked position by a handle, cable means, or the like, referenced generally by numeral  49 . 
     FIGS. 5–7  depict the normal position of sleeve  29 , wherein the sleeve  29  is out of perpendicular relative to the shaft  24  such that the external teeth on rod  18  are in mesh with and locked against the internal teeth on sleeve  29 . The sleeve is locked to rod  18  so that the rod 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 relation to column member  10 . 
   Referring to  FIG. 9 , a sleeve  29  that is a second embodiment of the present invention is shown. The sleeve  29  includes a pair of slots  31   a ′ and  31   b ′ on opposite sides of the sleeve  29 . Each slot  31   a ′,  31   b ′ includes a portion  34   a ,  34   b , respectively, that extends perpendicular to the axis of the sleeve  29  and an angled portion  36   a ,  36   b , respectively, extending therefrom. The perpendicular portions  34   a  and  34   b  overlap such that the slots  31   a ′ and  31   b ′ have co-axial axes a 1  and b 1  within the perpendicular portions  34   a ,  34   b . The angled portions  36   a  and  36   b  are angled in opposite directions along the sleeve  29 . Angled portion  36   a  angles upward along the sleeve  29  while angled portion  36   b  angles downward along the sleeve  29 . As such, the slots  31   a ′ and  31   b ′ have axes a 2  and b 2  that are axially offset from one another. With the axes a 1  and b 1  co-axial and the axes a 2  and b 2  offset, a shaft (not shown) extending through the slots  31   a ′ and  31   b ′ locks and unlocks in a manner similar to that described above with respect to the first embodiment. 
   Referring to  FIGS. 10 and 11 , a sleeve  29  that is a third embodiment of the present invention is shown. The sleeve  29  includes a pair of slots  31   a ″ and  31   b ″ on opposite sides of the sleeve  29 . Each slot  31   a ″,  31   b ″ includes a portion  38   a ,  38   b , respectively, that extends perpendicular to the axis of the sleeve  29  and a tapered portion  40   a ,  40   b , respectively, extending therefrom. The perpendicular portions  38   a  and  38   b  overlap such that the slots  31   a ″ and  31   b ″ have co-axial axes a 1  and b 1  within the perpendicular portions  38   a ,  38   b . Each perpendicular portion  38   a ,  38   b  has a width D that is greater than the diameter of the shaft  24 . When the shaft  24  is positioned in the perpendicular portions  38   a ,  38   b  of the slots  31   a ″,  31   b ″, it will have a loose fit, however, since this is the unlocked position, such freedom is not detrimental. The tapered portions  40   a  and  40   b  are tapered in opposite directions along the sleeve  29  such that the slots  31   a ″ and  31   b ″ have axes a 2  and b 2  that are axially offset from one another. With the axes a 1  and b 1  co-axial and the axes a 2  and b 2  offset,  24  shaft extends through the slots  31   a ″ and  31   b ″ and is moveable between locked and unlocked positions in a manner similar to that described above with respect to the first embodiment. However, as shown in  FIG. 11 , as the shaft  24  moves toward the locked position, the sleeve  29  tilts, causing the perpendicular portions  38   a ,  38   b  out of alignment. The perpendicular portions  38   a ,  38   b  are preferably sized such that an overlap distance d that is equal to or greater than the shaft diameter remains. Such an overlap allows an easier movement of the shaft  24  from the locked position to the unlocked position.