Adjustable steering column assembly with compressive locking mechanism

An adjustable steering column assembly with a steering shaft extending through a jacket member. An elongate locking member extends through two opposed sidewalls and a compression member positioned between the sidewalls. One of either the sidewalls or the compression member is fixed relative to the jacket member while the other is fixed relative to the vehicle structure. Spacers are located on opposite sides of the compression member between the compression member and the two sidewalls. First and second abutment surfaces are engaged with outward facing surfaces of the sidewalls and are coupled to the elongate locking member. An actuator assembly moves the locking assembly between unlocked and locked positions. In the locked position, the abutment surfaces bias the sidewalls inwardly to firmly engage the compression member between the spacers.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to steering column assemblies and, more particularly, to steering column assemblies that may be repositioned by the vehicle operator.

2. Description of the Related Art

Steering columns for automobiles and other vehicles that can have the tilt or rake angle of the column and the axial length of the column adjusted by the vehicle operator are well known in the art. A wide variety of such axially and tiltably adjustable steering columns have been developed. An example of one such steering column is shown inFIGS. 1 and 2.

In the prior art steering column assembly depicted inFIGS. 1 and 2, the adjustable steering column assembly10includes an upper tubular steering jacket12and a lower jacket13. Upper and lower jackets12,13are telescopingly coupled so that the axial length of the column can be adjusted. A steering shaft14extends through the hollow interior of the steering jackets12,13. The steering shaft14has a steering wheel (not shown) mounted on its projecting end15and rotates within steering jackets12,13. Steering shaft14and steering jackets12,13are adjustably tiltable about pivot member16which defines tilt axis17.

A mounting bracket18is formed out of stamped sheet metal and is attached to the vehicle structure with fastener assemblies19. A compression bracket20is also formed out of stamped sheet metal and is attached to upper jacket12with welds21along opposite sides of jacket12. Compression bracket20fits closely within mounting bracket18. When steering jackets12,13and steering shaft14are tilted about axis17, mounting bracket18remains stationary while compression bracket20moves with upper steering jacket12within mounting bracket18. The compression bracket20is also displaced relative to mounting bracket18when the upper jacket12is axially repositioned relative to lower jacket13to adjust the overall axial length of the steering column assembly10.

A locking assembly22is provided to secure and release compression bracket20relative to mounting bracket18to thereby secure steering column10in a desired tilt angle at a desired axial length and release steering column10for adjustment of the tilt angle and/or axial length.

Locking assembly22includes a manually operated lever arm24. Movement of lever arm24between a first position, shown in solid lines inFIG. 1, close to upper jacket member12and a second position, shown in dashed lines inFIG. 1, extending outwardly relative to upper jacket12, operably engages camming member26. Bolt28extends through openings in the sidewalls of mounting bracket18and compression bracket20and has a nut30attached at one end.

Abutment members32,34are located on opposite sides mounting bracket18and are coupled with bolt28such that as lever24is moved from its second position to its first position (shown in solid lines inFIG. 1), camming member26moves along camming ramp27and biases abutment members32,34closer together to thereby cause abutment members32,34to compress the sidewalls of mounting bracket18to firmly engage the sidewalls of compression bracket20and thereby secure steering jackets12,13and steering shaft14in a desired position. Movement of lever arm to its second position (shown in dashed lines inFIG. 1) increases the distance between abutment members32,34sufficiently to allow compression bracket20to move within mounting bracket20to allow the operator of the vehicle to reposition compression bracket20relative to mounting bracket18and thereby adjust the tilt angle and/or axial length of steering column assembly10. After the operator has repositioned the steering column, the operator will return lever12into its first position and thereby secure the steering column at the desired position.

While the adjustable steering column assembly10described above performs adequately, the forces applied to the sidewalls of the mounting bracket18to inwardly compress the mounting bracket sidewalls also act on the sidewalls of the compression bracket20which are formed out of stamped metal sheet stock in the same manner as the sidewalls of the mounting bracket. To increase the resistance of the compression bracket sidewalls to inward compression and thereby provide a more firm engagement between the mounting bracket18and the compression bracket20when the assembly is in a locked condition, an optional stiffening plate36can be welded to the compression bracket20as shown inFIG. 2. While the use of such a stiffening plate36enhances the resistance of the compression bracket sidewalls to inward compression and thereby improves the performance of the assembly, it also increases the manufacturing complexity of the assembly while still leaving room for further improvement.

SUMMARY OF THE INVENTION

The present invention provides an adjustable steering column assembly wherein when the assembly is placed in a locked condition, inward compressive forces exerted by the sidewalls of a mounting bracket are transferred to a compression member by spacers which firmly engage the compression member to thereby hold the steering column in place.

The invention comprises, in one form thereof, an adjustable steering column assembly securable to a support structure within a vehicle and having a steering shaft. The steering column assembly includes a jacket member defining a jacket axis wherein the steering shaft extends through the jacket member. The jacket member and the steering shaft are adjustably pivotal together about a tilt axis wherein pivotal movement of the jacket axis defines a central plane positioned substantially perpendicular to the tilt axis. A compression member is provided and has an opening extending through the compression member in a direction substantially transverse to the central plane. First and second opposing sidewalls are positioned on opposite sides of the compression member wherein one of the compression member and the first and second opposing sidewalls is fixed relative to the vehicle structure and the other of the compression member and the first and second opposing sidewalls is fixed relative to the jacket member. The first and second sidewalls each have an inward facing surface and an outward facing surface and respectively define first and second passages extending between the inward and outward facing surfaces. The steering column assembly also includes first and second spacers. Each of the first and second spacers defines a channel extending therethrough. An elongate locking member extends through the first and second passages, the channels defined by the first and second spacers and the opening defined by the compression member wherein the first and second spacers are located on opposite sides of the compression member between the compression member and a respective one of the first and second opposing sidewalls. The steering column assembly also includes first and second abutment surfaces. The first abutment surface is engageable with the outwardly facing surface of the first sidewall and the second abutment surface is engageable with the outwardly facing surface of the second sidewall. The elongate locking member is operably coupled with the first and second abutment surfaces wherein forces biasing the first and second abutment surfaces apart place the elongate locking member in tension. An actuator assembly is operably coupled with the abutment surfaces wherein movement of the actuator assembly moves the steering column assembly between an unlocked position wherein the first and second abutment surfaces define a first distance therebetween, and a locked position wherein the first and second abutment surfaces define a second distance therebetween wherein the first distance is greater than the second distance. In the locked position, the first and second abutment surfaces exert a compressive force on the first and second opposing sidewalls whereby the first and second sidewalls deflect inwardly and compressively secure the compression member between the first and second spacers and thereby inhibit relative movement of the compressive member and the first and second sidewalls. In the unlocked position, the compressive force exerted by the first and second abutment surfaces is reduced to thereby permit relative movement of the compressive member and the first and second sidewalls. A combined length of the first and second spacers between the first and second abutment surfaces defines a third length wherein the third length is at least an approximate majority of the second distance between the abutment surfaces.

The invention comprises, in another form thereof, an adjustable steering column assembly securable to a support structure within a vehicle and having a steering shaft. The adjustable steering column assembly includes a jacket member defining a jacket axis. The steering shaft extends through the jacket member and the steering shaft and jacket member are adjustably pivotal together about a tilt axis wherein the tilt axis extends substantially perpendicular to the jacket axis. A compression member is secured to the jacket member wherein the compression member defines a first thickness in a direction substantially transverse to the jacket axis. The compression member further defines an opening extending through the compression member in direction substantially transverse to the jacket axis. A bracket having a substantially U-shaped portion with first and second opposing sidewalls and an interconnecting portion extending between said first and second sidewalls is provided. The bracket member is adapted for non-moveable securement to the support structure within the vehicle. The jacket member is operably coupled with the bracket member wherein the tilt axis extends substantially transversely relative to the first and second opposing sidewalls and the jacket member is selectively pivotal relative to the bracket member within the U-shaped portion of the bracket member. The first and second sidewalls each have an inward facing surface and an outward facing surface and respectively define first and second passages extending between said inward and outward facing surfaces. First and second spacers are provided and each of the first and second spacers define a channel extending therethrough. An elongate locking member extends through the first and second passages, the channels defined by the first and second spacers and the opening defined by the compression member wherein the first and second spacers are located on opposite sides of the compression member between the compression member and a respective one of the first and second opposing sidewalls. The elongate locking member is repositioned relative to at least one of the jacket member and the bracket member as the jacket member is pivoted relative to the bracket member. First and second abutment surfaces are also provided. The first abutment surface is engageable with the outwardly facing surface of the first sidewall and the second abutment surface is engageable with the outwardly facing surface of the second sidewall. The elongate locking member is operably coupled with the first and second abutment surfaces wherein forces biasing the first and second abutment surfaces apart place the elongate locking member in tension. An actuator assembly is operably coupled with the first and second abutment surfaces wherein movement of the actuator assembly moves the locking assembly between an unlocked position wherein the first and second abutment surfaces define a first distance therebetween, and a locked position wherein the first and second abutment surfaces define a second distance therebetween and wherein the first distance is greater than the second distance. In the locked position, the first and second abutment surfaces exert a compressive force on the first and second opposing sidewalls whereby the first and second sidewalls deflect inwardly and compressively secure the compression member between the first and second spacers and thereby inhibit relative movement of the compressive member and the bracket member. In the unlocked position, the compressive force exerted by the first and second abutment surfaces is reduced to thereby permit relative movement of the compressive member and the bracket member.

An advantage of the present invention is that it facilitates the efficient manufacture of an adjustable steering column assembly and allows the vehicle operator to firmly secure the steering column in a desired position.

DETAILED DESCRIPTION OF THE INVENTION

An adjustable steering column assembly40in accordance with the present invention is illustrated inFIGS. 3 and 4. Steering column assembly40includes an upper elongate jacket member42and a lower elongate jacket member44. The upper and lower jacket members42,44are telescopingly coupled together so that the axial length of steering column assembly40can be adjusted. The use of telescoping jacket members to form a steering column having an adjustable axial length is well-known in the art.

Steering shaft46extends through jacket members42,44along jacket axis48. Steering shaft46is rotatable within jackets42,44and has a steering wheel (not shown) mounted on its projecting end50while the opposite end of shaft46is coupled to the steered wheels of the vehicle. Jacket members42,44are pivotally mounted on pivot member52. The position of pivot member52is fixed relative to the vehicle structure and defines tilt axis54. Vehicle structure53to which steering column40is pivotally mounted is symbolically represented inFIG. 3. Steering shaft46is pivotal relative to the vehicle structure about tilt axis54together with jacket members42,44. When the axial length of column assembly40is adjusted, lower jacket member44remains fixed relative to the vehicle structure while upper jacket42and projecting end50of shaft46are axially repositioned relative to lower jacket44and the vehicle structure. The ability to pivot steering column assembly40about tilt axis54and adjust its axial length allows the operator of the vehicle to reposition the steering wheel of the vehicle. When column assembly40is adjustably tilted, jacket axis48moves through an arc47(FIG. 3) and defines a central plane49(FIG. 4) of assembly40.

Steering jacket and shaft assemblies which are pivotally mounted on a vehicle structure and have an axial length that is adjustable are well known to those having ordinary skill in the art and various other configurations of such jacket and shaft assemblies may also be used with the present invention.

Steering column assembly40also includes a mounting bracket56. Mounting bracket56has a U-shaped portion58that is formed by opposing sidewalls60and an interconnecting portion62. Bracket56also includes upper flanges66that extend outwardly from sidewalls60. Upper flanges66include fastener assemblies68for securing mounting bracket56to the vehicle structure. Stiffening flanges67are located along one edge of upper flange66and the top portion of sidewalls60. The securement of mounting bracket56to the vehicle structure with fastener assemblies68non-moveably secures, i.e., fixes, mounting bracket56relative to the vehicle structure. Thus, as upper jacket member42and steering shaft46are pivoted about tilt axis54they move relative to bracket56within U-shaped portion58.

Each of the sidewalls60has an inward facing surface70and an outward facing surface72. Sidewalls60also each include a passage64that extends through the sidewall from outer surface72to inner surface70. Passages64allow elongate locking members96to be inserted through passages64at a substantially transverse angle to central plane49. Passages64take the form of slots that are elongate in a direction65positioned at an angle to jacket axis48as can be seen inFIG. 3. The elongate nature of passages64allow elongate locking member96to be repositioned within passages64as steering jackets42,44and steering shaft46are pivoted about tilt axis54. For example, locking member96is shown in position65ainFIGS. 3 and 4but could be repositioned in position65bby the downward tilting of jackets42,44about axis54. Arc47also shown inFIG. 3is representative of upward tilting of the column assembly.

In the illustrated embodiment, the elongate slots formed by passages64are substantially rectilinear and have a width that is sufficiently large to accommodate the lateral movement within the slot of locking member96. If desired, however, an elongate and arcuate slot that extends at an angle to jacket axis48and tracks the arcuate path of locking member96could be used.

In the illustrated embodiment, mounting brackets56are formed by stamping a steel sheet stock material. As discussed below, sidewalls60are resilient and are deflected slightly inwardly when locking steering column assembly40in a desired position. The use of a steel sheet material having a thickness of between approximately 3 mm and 3.5 mm provides sidewalls60with the ability to be resiliently deflected inwardly for such locking purposes while also providing bracket56with suitable strength. In the illustrated embodiment, sidewalls60have a thickness71of approximately 3.42 mm. Other embodiments of the present invention, however, may use sidewalls and/or mounting brackets formed out of other materials and/or other dimensions.

A compression member74is attached to upper jacket member42and has an opening76that extends through compression member74in a direction substantially transverse to central plane49with locking member96passing therethrough. Opening76takes the form of an axially elongate slot to thereby allow locking member96to be repositioned within opening76when upper jacket member42is axially repositioned relative to the vehicle structure. As discussed above, the position of mounting bracket56is fixed relative to the vehicle structure. Elongate locking member96is moveable relative to mounting bracket56but this relative movement is substantially constrained to movement along directional line65which allows for the relative tilting movement of adjustable steering column40.

In the embodiment illustrated inFIGS. 3-5, opening76forms a slot that is elongated in a direction78that allows locking member96to be axially repositioned within slot76, e.g., between position78aand78b(FIG. 5), as upper jacket member42and steering shaft46are axially repositioned relative to the vehicle structure. In the embodiment ofFIGS. 3-5, compression member74is formed of metal bar stock that is secured to upper jacket member42with welds75at a 6 o'clock position with compression member74being centered on central plane49and slot directional line78being positioned parallel with jacket axis48. The illustrated compression member74defines a thickness82between its opposite side surfaces80that is between approximately 8 mm and 10 mm. For example, the illustrated compression member74may be formed out of a low carbon steel having a thickness of 8 mm.

Two spacers86are located on opposite sides of compression member76. In the embodiment ofFIGS. 3-5, spacers86have a cylindrical shape with cylindrical channels87extending therethrough for allowing passage of elongate locking member96. Spacers86have inward facing end surface88that engage opposite side surfaces80of compression member74and outward facing ends surfaces90that engage inward facing surfaces70of sidewalls60. As further discussed below, when sidewalls60are deflected inwardly to lock steering column40in a desired position, sidewalls60compress spacers86into engagement with both side surfaces80of compression member74and inward facing surfaces70of sidewalls60. This compressive engagement of spacer surfaces90with sidewall surfaces70and spacer surfaces88with compressive member surfaces80frictionally resists relative movement at these surface engagements to secure compressive member74relative to mounting bracket56. Compressive member74is attached to upper jacket42while mounting bracket56is attached to the vehicle structure, thus, the compressive engagement of these surfaces secures upper jacket member42, and steering shaft46mounted therein, in a selected position relative to the vehicle structure.

The use of spacers86and compressive member74provides a robust locking mechanism by providing a substantially void-free solid material bridge through which at least some of the inwardly directed compressive forces exerted by sidewalls60can be linearly transmitted between opposing sidewalls60, see, e.g., force line94inFIG. 4. This arrangement allows for relatively high compressive forces to be generated in the locking action to thereby firmly secure steering column assembly40in a desired configuration. Spacers86have a wall thickness (in a direction transverse to the compressive forces transmitted by spacers86) that is sufficiently great to withstand the compressive loads placed thereon. In the illustrated embodiment, spacers86are formed of metal material, e.g., steel, and have a wall thickness92(FIG. 5) which extends substantially transverse to the linearly transmitted compressive forces94and which is approximately 6 mm.

Biasing sidewalls60inwardly reduces the distance124between inward facing surfaces70of sidewalls60. As best understood with reference toFIGS. 4 and 5, the use of a compression member74having a thickness of approximately 8 mm, and sidewalls60having a thickness71of between approximately 3 mm and 3.5 mm with spacers86that span the full distance between compression member74and sidewalls60to provide a solid material bridge between the two sidewalls results in spacers having lengths126which, when combined together, form greater than 50% of the total length124between sidewalls60when locking assembly84is in its locked condition.

Various spacer configurations and materials can be used to transmit compressive loads between opposing sidewalls60in other embodiments of the invention. For example, an alternative spacer86ais illustrated inFIG. 6. Alternative spacer86aincludes a frustroconical-end89that defines an end surface90ahaving a larger surface area for bearing engagement with the inward facing surface70of sidewalls60. The configuration of end surface90asubstantially corresponds to the configuration of abutment surfaces106and112to thereby reduce stresses within sidewalls60created by the transmission of compression forces from abutment surfaces106,112to the spacer end surfaces in engagement with the inward facing surfaces70of sidewalls60. The minimum wall thickness92aof this alternative spacer86is comparable to the wall thickness92of spacer86. In still other embodiments, washers or other intermediate bearing members may be placed between sidewalls60and spacers86and/or between compressive member74and spacers86. Such washers or other intermediate bearing members can be employed to provide a desired bearing surface area or frictional coefficient at the interfaces with sidewalls60and/or compressive member74.

Elongate locking member96extends through passages64in both sidewalls60, through channels87in both spacers86, and through opening76in compression member74with each of the spacers86being located on an opposite side of compression member74between compression member74and one of sidewalls60as best seen inFIG. 4. In the embodiment ofFIGS. 3-5, locking member96takes the form of a bolt with one end being formed by a hexagonal bolt head98and the other end being a threaded shaft100and an elongate shaft99therebetween. A threaded nut102is secured on threaded end100of bolt96and secures abutment member104against sidewall60with abutment surface106being engaged with outward facing surface70of sidewall60. Another abutment member108is secured against the opposite sidewall60with abutment surface112being engaged with outward facing surface70. Both abutment members104and108have central apertures through which bolt96extends.

A locking assembly84is formed by abutment surfaces106,108, sidewalls60, spacers86, compression member74and locking member96to secure compression member74relative to sidewalls60. When locking assembly84is in an unlocked condition, abutment surfaces106,108are positioned apart by a sufficiently great distance such that sidewalls60are not deflected inwardly or are deflected inwardly to such a small distance that compressive member74can slide relative to spacers86and locking member96(to provide for axial adjustment of column assembly40) and sidewalls60can slide relative to spacers86and locking member96(to provide for tilting adjustment of column assembly40).

When locking assembly is in a locked condition, abutment surfaces106and112are biased inwardly against outer surfaces72of sidewalls60to thereby deflect sidewalls60inwardly and compress surfaces70of sidewalls60against surfaces90of spacers86and surfaces88of spacers86against opposite side surfaces80of compression member74. These compressive forces create frictional resistance to relative sliding movement between these surfaces and thereby secure compressive member74relative to sidewalls60and, thus, secure column assembly40in a selected axial and tilt angle position.

Washers or other intermediate bearing members, such as those discussed above with reference to the spacer interfaces, may also be used between abutment surfaces106,112and outer surfaces72of sidewalls60to provide a desired bearing surface area or frictional coefficient. The illustrated abutment members104,108are mounted on locking member96and move with locking member96relative to sidewalls60when steering jacket42is tilted about axis54.

Elongate member96is coupled with abutment surfaces106,112such that biasing abutment surfaces106,112together to compress sidewalls60inwardly that biases surfaces106,112apart) places elongate member96in tension. In other words, applying a force to surfaces106,112that biases surfaces106,112apart places elongate member96in tension. On threaded end100of member96, nut102is used to couple member96with abutment member104and abutment surface106to provide for the transmission of such forces. A washer, e.g., a locking washer, may be positioned between nut102and abutment member104. Alternatively, abutment member104may take the form of either a nut or washer. Forces are transmitted between abutment surface112and bolt head98through actuator assembly114.

Actuator assembly114is coupled with locking assembly84to move the locking assembly84between its locked and unlocked positions. Actuator assembly114includes manually operable lever arm116which can be moved between a first position118(indicated by phantom lines inFIG. 3) and a second position120by the driver of the vehicle. Bolt head98is captured within lever arm116. Actuator assembly114also includes a camming finger122located on lever arm116and an inclined camming surface110located on abutment member108. When lever arm116is in position118, locking assembly84is in its unlocked position with abutment surfaces106,112being spaced apart by a distance that allows for relative movement of compressive member74and sidewalls60. When lever arm116is rotated into position120, the interaction of camming fingers122and inclined camming surfaces110(advantageously, three such fingers and surfaces are distributed circumferentially around locking member96) biases abutment surfaces106,112toward each other. Bolt head98is captured within lever arm116and thus abutment member108is biased away from bolt head98toward nut102by the movement of lever arm116into position120.

After moving lever arm116into position120, abutment surfaces106,112are spaced apart by a distance lesser distance than when lever arm116was in position118, thereby deflecting sidewalls60inwardly and placing locking assembly84in its locked condition. There are a variety of camming and biasing arrangements that can be used in an adjustable steering column assembly with an elongate locking member to bias a pair of sidewalls inwardly for locking and unlocking the steering column assembly. Examples of such camming and biasing arrangements that can be adapted for use with the present invention are disclosed by Riefe et al. in U.S. Pat. No. 6,659,504 B2; by Manwaring et al. in U.S. Pat. No. 6,616,185 B2; Cymbal in U.S. Pat. No. 5,570,610; and Hancock in U.S. Pat. No. 5,377,555 the disclosures of which are all hereby incorporated herein by reference.

The present invention may also take various other forms. One example of an alternative embodiment of the invention is illustrated inFIGS. 7 and 8and provides an assembly wherein the compression member is fixed relative to the vehicle structure with opposing sidewalls being coupled to, and moving with, a steering jacket member. Adjustable steering column assembly130depicted inFIGS. 7 and 8includes a T-shaped compression member132. Compression member132has an upper flange134and a compression rib136and is formed by bending metal sheet stock material. Welds135join the two outwardly extending portions of upper flange134.FIG. 8provides an enlarged view of one end of compression member132.FIG. 9illustrates an extruded compression member164having a T-shaped cross-section that can be used with assembly130instead of compression member132.

An elongate slot138is located in compression rib136and spacers86are located on opposite sides of rib136to grip rib136in the same manner spacers86grip compression member74. Although not shown inFIG. 7, assembly130utilizes an elongate locking member and actuating assembly similar to that described above with reference to assembly40.

The opposite ends of compression member132are connected to mounting plates140,142by seating rib136in slots139and upper flange member134in recessed areas141and welding member132to plates140,142. Mounting plates or brackets140,142are then secured to the vehicle structure so that compression member132is fixed relative to the vehicle structure. Rear mounting plate142also includes a slot144for receiving a pivot pin. Upper steering jacket146and lower steering jacket148are joined together and define a jacket axis150. A steering shaft (not shown) would extend through jacket members146,148a long jacket axis150. Jacket members146,148are pivotal about tilt axis163defined by pivot mount162. Pivot mount162is adapted to engage a pivot pin and is located on lower jacket member148. Slot144allows for the repositioning of the pivot pin and tilt axis163relative to the vehicle structure.

A U-shaped support bracket152is attached to upper jacket member146and forms opposite sidewalls154. Sidewalls154each have an elongate slot156, inward facing surfaces158and outward facing surfaces160. An elongate locking member is inserted through slots156of sidewalls154, spacers86and compression member slot138in a manner similar to that described above for assembly40. Abutment surfaces are engaged with outward facing surfaces160of sidewalls154and an actuating mechanism for biasing the abutment surfaces into a locked position similar to that discussed above with reference to assembly40is also provided.

Slot138is an axially elongate slot (with respect to axis150) but it will generally not be positioned parallel with axis150. Thus, the axial repositioning of upper jacket member146will result in both the axial repositioning of the elongate locking member within slot138of compression member134as well as the repositioning of the elongate locking member in slots156formed in sidewalls154.

Another alternative embodiment170is depicted inFIG. 10. Assembly170is similar to assembly130but utilizes a compression member172having an elongate slot174that is formed out of bar stock and does not include an upper flange like compression members132,164. Like the compression members illustrated inFIGS. 8 and 9, compression member172would be welded or otherwise joined to mounting plates140,142for securement relative to the vehicle structure.