The following description relates to a lock for an adjustable steering column, and in particular, a rake and/or telescope lock in an adjustable steering column.
Steering columns in vehicles may be adjustable in a rake direction and a telescope direction. The adjustable steering column may be unlocked in order to be adjusted to a desired position. Once the desired position is reached, the steering column may be locked in place to resist movement from the desired position.
A traditional adjustable steering column may include a column jacket, a compression bracket fixed to and movable with the column jacket and a mounting bracket fixed to the vehicle. The column jacket and compression bracket are movable relative to the mounting bracket. The adjustable steering column may further include a locking lever, a rake lock and a telescope lock.
The locking lever is rotatable between a locked position where adjustment of the steering column is resisted and an unlocked position where adjustment of the steering column is permitted. The locking lever rotates a lock bolt that extends through the mounting bracket and compression bracket. Rotation of the lock bolt may actuate the rake lock and telescope lock between respective locked and unlocked positions.
The rake lock typically includes a rake lock body and a rake slot formed in one of the compression bracket or mounting bracket. The rake lock body includes a plurality of rake lock teeth formed thereon and the rake slot includes a corresponding plurality of rake slot teeth. In the unlocked position the rake lock teeth are disengaged from the rake slot teeth with a clearance between peaks of the rake lock teeth and peaks of the rake slot teeth. In this position, the steering column may be adjusted in the rake direction. When a desired position of the steering column is reached, the locking lever may be rotated from the unlocked position to the locked position. During rotation of the locking lever from the unlocked position to the locked position, the rake lock body moves toward the rake slot such that the rake lock teeth move toward engagement with the rake slot teeth. In the locked position, the rake lock teeth and the rake slot teeth are engaged such that adjustment of the steering column in the rake direction is resisted.
The telescope lock may include a telescope lock body and a telescope slot formed in one of the compression bracket or mounting bracket. The telescope lock body includes a plurality of telescope lock teeth and the telescope slot includes a corresponding plurality of telescope slot teeth. Similar to the rake lock arrangement described above, the telescope lock teeth and disengaged and separated from the telescope slot teeth when in the unlocked position. Accordingly, the steering column may be adjusted in the telescope direction with the telescope lock in the unlocked position. Rotation of the locking lever toward the locked position moves the telescope lock body with the telescope lock teeth toward engagement with the telescope slot teeth. In the locked position, the telescope lock teeth and the telescope slot teeth are engaged such that adjustment of the steering column in the telescope direction is limited.
One drawback to the arrangement above is that when the locking lever is rotated from an unlocked position to a locked position, peak areas of the lock teeth on the rake body and/or telescope body may come into contact with peak areas of the lock teeth within the respective rake and/or telescope slot. The peak-to-peak contact between the respective teeth prevents the rake and telescope locks from becoming engaged. Thus, adjustment in the rake and/or telescope direction is not resisted, even with the locking lever in a locked position. That is, peak-to-peak contact between the lock teeth of the rake lock body and/or telescope lock body and the lock teeth of the respective rake slot and/or telescope slot prevent the lock teeth of the rake body and/or telescope body from engaging between the lock teeth of the respective rake slot and/or telescope slot. Further, there are only a finite number of adjustment positions available in the rake and telescope directions, limited by the number of corresponding lock teeth between the rake body and telescope body and the respective slots.
In another typical adjustable steering column, in a locked condition, a force may be applied to a plurality of friction plates, which in turn apply a compressive force to at least one of the mounting bracket, compression bracket and column jacket. The force may be applied from a cam mechanism connected to a rotatable locking lever that is configured to apply an axial compressive force in response to rotation of the locking lever in one direction. The compressive force applied to the column jacket acts to hold the adjustable steering column against adjustment.
The steering column may be unlocked by rotating the locking lever in an opposite direction. Rotation of the locking lever in the opposite direction causes the cam to release the axial compressive force from the friction plates. Accordingly, the compressive force is released from the column jacket and the steering column may be adjusted. Drawbacks to the friction plate configuration include complexity of design and the associated costs.
Accordingly, it is desirable to provide an adjustable steering column lock which may ensure engagement between oppositely positioned locking teeth.