Customizable cam clamping assembly for steering column

Abstract

The invention relates to a customizable cam clamping assembly for a steering column. The cam clamping assembly includes a lever rotatable between a locked position and an unlocked position of the cam clamping assembly. The cam clamp assembly also includes a cam follower operatively coupled to and rotatable with the lever, the cam follower having an inner surface with at least one cam follower member extending therefrom. The cam clamp assembly further includes a cam having an outer surface in contact with the inner surface of the cam follower, where the outer surface of the cam includes at least one cam member extending from the outer surface and in contact with the cam follower member, the cam member is a ramped surface having a contact path portion and at least one concave-convex portion, the cam follower member being in contact only with the contact path portion of the cam member during relative movement between the cam follower and the cam.

Description

Technical Field

[0001] The following description relates to a locking member for an adjustable steering column and, more particularly, to a customizable cam clamping assembly for an adjustable steering column. Background Art

[0002] The steering column in a vehicle can be adjusted in the rake direction and the telescopic direction. The adjustable steering column can be unlocked to be adjusted to a desired position. Once the desired position is reached, the steering column can be locked in place to resist movement from the desired position.

[0003] Clamping mechanism cams are used on many manually adjustable rake and telescopic or rake steering columns. The cam profile interfaces with a contact follower connected to a lever. The vehicle driver rotates the lever from the unlocked position to the locked position to fix the steering wheel position. An increasing clamping force is generated throughout the locking movement, with the aim of generating a target clamping load in the locked position. Most OEMs have specifications that limit the maximum allowable lever locking force and the minimum allowable lever unlocking force. These specifications can challenge the ability to achieve the target clamping load in the locked position. Summary of the Invention

[0004] According to one aspect of the present disclosure, there is provided a cam clamping assembly for an adjustable steering column assembly. The steering column assembly is adjustable in the unlocked position of the cam clamping assembly and is in a fixed position in the locked position of the cam clamping assembly. The cam clamping assembly includes a lever that is rotatable between the locked and unlocked positions of the cam clamping assembly. The cam clamping assembly further includes a cam follower operatively coupled to the lever and rotatable with the lever, the cam follower having an inner surface with at least one cam follower member extending from the inner surface. The cam clamping assembly further includes a cam having an outer surface that contacts the inner surface of the cam follower, wherein the outer surface of the cam includes at least one cam member extending from the outer surface and contacting the cam follower member, wherein the cam member is a ramp surface having a contact path portion and at least one relief portion, and wherein the cam follower member contacts only the contact path portion of the cam member during relative movement between the cam follower and the cam.

[0005] According to another aspect of the present disclosure, there is provided a cam clamping assembly for an adjustable steering column assembly. The steering column assembly is adjustable in the unlocked position of the cam clamping assembly and is in a fixed position in the locked position of the cam clamping assembly. The cam clamping assembly includes a lever that is rotatable between the locked position and the unlocked position of the cam clamping assembly. The cam clamping assembly further includes a cam follower that is operatively coupled to the lever and is rotatable with the lever, the cam follower having an inner surface with at least one cam follower member extending from the inner surface. The cam clamping assembly further includes a cam having an outer surface that contacts the inner surface of the cam follower, wherein the outer surface of the cam includes at least one cam member extending from the outer surface and contacting the cam follower member, wherein the cam member is a ramp surface having a contact path portion and at least one undulating portion, and wherein the at least one undulating portion has at least one variation that varies from the contact path portion.

[0006] These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of this specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the drawings, in which:

[0008] Figure 1 is a side elevation view of a steering column assembly having a cam clamping assembly to selectively lock and unlock the position of the steering column assembly;

[0009] Figure 2 is a transverse cross-sectional view taken along line A-A of Figure 1 for illustrating the cam clamping assembly;

[0010] Figure 3 is a perspective view of the cam and cam follower of the cam clamping assembly in the locked position;

[0011] Figure 4 is a perspective view of the cam and cam follower of the cam clamping assembly in the unlocked position;

[0012] Figure 5 is a perspective view of the cam illustrating the locking undulating feature and the unlocking undulating feature;

[0013] Figure 6 is a perspective view of a portion of the cam illustrating the average contact radius path within the range of movement between the locked position and the unlocked position of the cam clamping assembly;

[0014] Figure 7 is a perspective view of a cam follower and a cam in a locked position;

[0015] Figure 8 is a schematic representation of the contact location between the cam follower and the cam; and

[0016] Figure 9 is a graphical illustration of the torque required to move a cam clamping assembly over the entire travel range between a locked position and an unlocked position. DETAILED DESCRIPTION

[0017] Referring now to the drawings, in which the present disclosure will be described with reference to specific embodiments and not to limit the present disclosure, it should be understood that the disclosed embodiments are merely illustrative of the invention which may be embodied in various forms and alternative forms. The drawings are not necessarily to scale; some features may be enlarged or reduced to show details of particular components. Accordingly, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching one skilled in the art to employ the invention in various ways.

[0018] Referring Figure 1 and Figure 2 , a steering column assembly for a vehicle is shown and generally designated by the numeral 10. The steering column assembly 10 includes one or more sheaths (such as an upper sheath 12 and a lower sheath 14). The upper sheath 12 houses a portion of a steering shaft 16 which is operatively coupled to a steering wheel (not shown). The lower sheath 14 is operatively coupled to a mounting bracket 18 which assists in mounting the steering column assembly 10 to the vehicle structure. It should be understood that, as an alternative to the double-sheath assembly shown and described above, a single sheath may be present in some embodiments and more than two sheaths may be present in other embodiments.

[0019] The steering column assembly 10 may be used in any suitable vehicle (such as a sedan, truck, sport utility vehicle, minivan, crossover vehicle, any other passenger vehicle, any suitable commercial vehicle or any other suitable vehicle). Additionally, the principles of the present disclosure may be applied to other vehicles (such as an aircraft, a ship, a train, an unmanned aerial vehicle or other vehicles). The steering column assembly 10 may be configured as a driver interface steering system, an autonomous driving system, or a system that allows both a driver interface and autonomous steering.

[0020] The steering column assembly 10 includes a cam clamping assembly 20 to selectively place the steering column assembly 10 in a locked state and an unlocked state based on the locked position and the unlocked position of the cam clamping assembly 20. Specifically, the rotatable rod 22 is configured to actuate the cam clamping assembly 20 between the locked position and the unlocked position, and vice versa. The rotatable rod 22 is an extension of the cam clamping assembly (clamping device) 20 into the cab (not shown) of the vehicle, and the driver (not shown) can access the rod 22. The driver can engage the rod 22 to transition (convert) the steering column assembly 10 from the locked position to the unlocked position, or vice versa. In the unlocked position of the cam clamping assembly 20, the position of the steering column assembly 10 is adjustable, and when rotated to the locked position, the position of the steering column assembly 10 is fixed.

[0021] The cam clamping assembly 20 includes: a cam follower 24 that can be partially or fully disposed within the recessed portion 26 of the rod 22; a cam 28 that is operatively engaged with the cam follower 24; and a rake bolt 30. The rake bolt 30 extends through the rod 22, the cam follower 24, and the cam 28. The cam follower 24 is a component that is used to convert the rotation of the rod 22 into a linear force provided by the cam 28 to clamp the steering column assembly 10. The rake bolt 30 extends through the entire cam clamping assembly 20 and through at least a portion of the steering column assembly 10 to hold the two assemblies in place relative to each other.

[0022] Reference Figure 3 and Figure 4 Referring again to, the cam follower 24 has an outer surface 32 that contacts the rod 22. The cam follower 24 also has an inner surface 34 on which there is at least one member 36 that is arranged to engage the cam 28. The cam 28 has an outer surface 38 and an inner surface 40. There is at least one member 42 on the outer surface 38 of the cam 28 that is arranged to engage the member 36 of the inner surface 34 of the cam follower 24. The inner surface 40 of the cam 28 is positioned to engage components (such as the lower sheath 14, the mounting bracket 18, etc.) of the steering column assembly 10 to generate a clamping pressure.

[0023] Referring again to Figure 2, the angled bolt 30 includes a bolt shank 44 and a bolt head 46. The outer diameter of the bolt head 46 can be, for example, circular or square in shape. The outer diameter of the bolt head 46 is used to hold the angled bolt 30 in place relative to the rod member 22, which in some embodiments allows the angled bolt 30 to rotate with the rod member 22 during operation. The bolt shank 44 passes through the rod member 22, through openings in the cam follower 24 and the cam 28, and exits from the opposite side of the steering column assembly 10. During operation, rotation of the rod member 22 causes the angled bolt 30 and the cam follower 24 to rotate between a locked position ( Figure 3 ) and an unlocked position ( Figure 4 ). As shown in Figure 3 and Figure 4 , the member 36 of the cam follower 24 interacts with the member 42 of the cam 28 to clamp or release the steering column assembly 10. In the illustrated embodiment, the cam follower 24 and the cam 28 each include four lobes as members 36, 42, but it should be understood that more or fewer members 36, 42 may be present in other embodiments.

[0024] Now referring to Figure 5 , the member 42 of the cam 28 generally has a ramp profile. Each member 42 includes a contact path portion 50 and one or more undulating portions 52, which provide the designer with customizable variables to meet the locking and unlocking force load requirements of the cam clamping assembly 20. The term "undulating portion" refers to one or more variations in the ramp surface of the member 42 of the cam 28. For example, these variations can be recessed from the contact path portion 50 and / or can have different surface textures. In terms of different surface textures, the coefficient of friction of the surface texture of the undulating portion 52 is less than the coefficient of friction of the contact path portion 50. In the illustrated embodiment, the cam 28 includes a locking undulating portion 54 and an unlocking undulating portion 56 on each of the members 42. However, it should be understood that the member 42 can include only the locking undulating portion 54 or can include only the unlocking undulating portion 56, rather than having both types of undulating portions. Additionally, although all of the members 42 of the cam are shown as having undulating portions 52, it should be understood that in some embodiments, some of the members 42 may not have undulating portions 52, and any combination of the locking undulating portion 54 and the unlocking undulating portion 56 can be envisioned. The undulating portions 54, 56 can transition abruptly from the contact path portion 50 in a stepped manner or can transition gradually in a smooth manner.

[0025] Now referring to Figure 6, an average contact radius path 60 is shown on one of the members 42 of the cam 28. The average contact radius path 60 represents the radial length 62 from the axis of rotation 64 of the cam 28 to the midpoint of the total surface contact between the cam follower 24 and the cam 28. The presence of the concave and convex portions 54, 56 adjusts the average contact radius path 60 by moving the radial length 62. Specifically, since the locking concave and convex portion 54 is located on the radially outer portion of the cam 28, the radial length 62 is shortened along the path adjacent to the locking concave and convex portion 54. Conversely, since the unlocking concave and convex portion 56 is located on the radially inner portion of the cam 28, the radial length 62 is lengthened along the path adjacent to the unlocking concave and convex portion 56. The radial length 62 affects the rod locking and unlocking loads required to lock and unlock the cam clamping assembly 20. Specifically, reducing the average contact radius reduces the maximum rod locking and unlocking loads, while increasing the average contact radius increases the maximum rod locking and unlocking loads. By strategically positioning the locking concave and convex portion 54 and the unlocking concave and convex portion 56 in the manner shown in the exemplary embodiment, the clamping bolt tension at the locking position can be maximized, the unlocking rod torque can be maximized, and the locking rod torque can be reduced to obtain the same clamping load. The size and positioning of the concave and convex portion 52 can be customized to meet the design specifications.

[0026] Now referring to Figure 7 , the member 36 of the cam follower 24 is shown in the locked position of the cam clamping assembly 20. Specifically, the member 36 is disposed within the recessed portion 70 of the member 42 of the cam 28. This arrangement of the cam follower 24 and the cam 28 allows the operator to manually sense the achievement of the locked position based on the fact that the locking load force required after the member 36 of the cam follower 24 passes the maximum height of the ramp profile will decrease. Figure 8 An embodiment of the member 42 of the cam 28 is also shown, where the maximum height of the ramp profile is shown. In other words, since the slope of the ramp is steeper at this position compared to the maximum ramp profile position, the maximum rod force occurs before the maximum ramp profile position. Then, the slope steepness decreases to allow the operator to sense the full achievement of the locked position. Figure 9 The rod forces required over the entire stroke range (i.e., from the unlocked position to the locked position and vice versa) are graphically illustrated.

[0027] Although the present invention has been described in detail only in connection with a limited number of embodiments, it should be readily understood that the present invention is not limited to such disclosed embodiments. On the contrary, the present invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements that have not been previously described but are commensurate with the spirit and scope of the present invention. Additionally, although various embodiments of the present invention have been described, it should be understood that aspects of the present invention may include only some of the described embodiments. Accordingly, the present invention should not be regarded as being limited by the foregoing description.

Claims

1. A cam clamp assembly for an adjustable steering column assembly, the steering column assembly being adjustable in an unlocked position of the cam clamp assembly and being in a fixed position in a locked position of the cam clamp assembly, the cam clamp assembly comprising: a lever member rotatable between the locked position and the unlocked position of the cam clamp assembly; a cam follower operatively coupled to the lever and rotatable therewith, the cam follower having an inner surface with at least one cam follower member extending therefrom; as well as A cam having an outer surface which contacts the inner surface of the cam follower, wherein the outer surface of the cam includes at least one cam member extending from the outer surface and contacting the cam follower member, wherein the cam member is a slope surface having a contact path portion and at least one concave-convex portion, wherein during relative movement between the cam follower and the cam, the cam follower member contacts only the contact path portion of the cam member.

2. The cam clamp assembly according to claim 1, wherein: The at least one relief portion includes a locking relief portion.

3. The cam clamp assembly according to claim 2, wherein: The locking concave-convex portion is located on a radially outer portion of the cam member with respect to a rotation axis of the cam.

4. The cam clamp assembly according to claim 1, wherein: The at least one concave-convex portion includes an unlocking concave-convex portion.

5. The cam clamp assembly according to claim 4, wherein: The unlocking concave-convex portion is located on a radially inner portion of the cam member relative to a rotation axis of the cam.

6. The cam clamp assembly according to claim 1, wherein: The at least one concave-convex portion includes a locking concave-convex portion and an unlocking concave-convex portion.

7. The cam clamp assembly according to claim 1, wherein: The at least one concave-convex portion includes a stepped drop adjacent to the contact path portion.

8. The cam clamp assembly according to claim 1, wherein: The at least one relief portion includes an inclined transition portion leading from the contact path portion.

9. A cam clamp assembly for an adjustable steering column assembly, the steering column assembly being adjustable in an unlocked position of the cam clamp assembly and being in a fixed position in a locked position of the cam clamp assembly, the cam clamp assembly comprising: a lever member rotatable between the locked position and the unlocked position of the cam clamp assembly; a cam follower operatively coupled to the lever and rotatable therewith, the cam follower having an inner surface with at least one cam follower member extending therefrom; as well as A cam having an outer surface which contacts the inner surface of the cam follower, wherein the outer surface of the cam includes at least one cam member extending from the outer surface and contacting the cam follower member, wherein the cam member is a slope surface having a contact path portion and at least one concave-convex portion, wherein the at least one concave-convex portion has at least one deformation portion that changes from the contact path portion.

10. The cam clamp assembly according to claim 9, wherein: The at least one deformation portion is defined by the at least one concave-convex portion as a recessed portion relative to the contact path portion, wherein the cam follower member contacts only the contact path portion of the cam member during relative movement between the cam follower and the cam.

11. The cam clamp assembly according to claim 10, wherein: The at least one concave-convex portion includes a stepped drop adjacent to the contact path portion.

12. The cam clamp assembly according to claim 10, wherein: The at least one relief portion includes an inclined transition portion leading from the contact path portion.

13. The cam clamp assembly according to claim 9, wherein: The at least one deformation portion is defined by the at least one concavo-convex portion to have a surface texture different from that of the contact path portion.

14. The cam clamp assembly according to claim 13, wherein: The coefficient of friction of the surface texture of the at least one concavo-convex portion is smaller than the coefficient of friction of the contact path portion.

15. The cam clamp assembly according to claim 9, wherein: The at least one relief portion includes a locking relief portion.

16. The cam clamp assembly according to claim 15, wherein: The locking concave-convex portion is located on a radially outer portion of the cam member with respect to a rotation axis of the cam.

17. The cam clamp assembly according to claim 9, wherein: The at least one concave-convex portion includes an unlocking concave-convex portion.

18. The cam clamp assembly of claim 17, wherein: The unlocking concave-convex portion is located on a radially inner portion of the cam member relative to a rotation axis of the cam.

19. The cam clamp assembly according to claim 9, wherein: The at least one concave-convex portion includes a locking concave-convex portion and an unlocking concave-convex portion.

Images