Steering assemblies

Details Steering assemblies Steering assemblies

1999-08-19

2001-11-13

Bucci, David A. (Department: 3682)

Machine element or mechanism

Control lever and linkage systems

Hand operated

C074S492000, C074S3880PS, C280S775000, C280S779000

Reexamination Certificate

active

06314829

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to column-mounted electrically actuated steering assemblies for vehicles and in particular, to assemblies of the kind in which the column is adapted to tilt about a pivot relative to the body of a vehicle so that the relative position of a steering wheel can be adjusted to meet the requirements of a driver.
BACKGROUND OF THE INVENTION
It is known to provide an electrically actuated steering assembly which employs an electric motor as a source of assistance torque for the driver. This is connected to a steering column via a gearbox. The electric motor, its associated drive and control circuit, and the gearbox, can be mounted upon the steering column shaft so that the shaft supports the weight of the assembly. The steering column and gearbox may form a single steering column assembly.
It is also known that the steering column can be fixed to the vehicle body by means of a substantially horizontal pivot which has its axis of rotation substantially perpendicular to the axis of the steering column shaft. The steering column can thus be tilted about the pivot so as simultaneously to enable height and rake adjustments of the steering wheel to be achieved. The use of such a simple pivoting steering column is well known in the art.
A problem arises when the use of a tiltable steering column is combined with an electrically actuated steering assembly. The motor applies an assistance torque to the steering column via the gearbox as required but, in doing so, generates a reaction torque which must be absorbed through the pivot into the vehicle body. Due to cost restraints during design, there is often a degree of free play in the pivot, and the effect of the reaction torque is to cause the steering column to move slightly about the pivot pin. This movement can produce unwanted noise and vibration in the steering column, for example whenever the torque of the motor varies.
One solution to the problem of reacting the torque generated by the motor would be the use of high precision bushings or by ensuring that there is no clearance at the pivot. However, this use of “over-engineering” to remove the symptoms of vibration does not effectively remove the source of the problem, and the problem would re-appear with wear of the pivot bushes.
SUMMARY OF THE INVENTION
According to our invention, in a steering apparatus comprising an adjustable steering column assembly adapted to pivot about a point along its length relative to a mounting bracket, said column assembly comprising at least a steering column and a gearbox fixed relative to said column, said gearbox being adapted to transfer a torque generated by an electric motor to said steering column, biasing means are provided between said steering column assembly and said mounting bracket, said biasing means being adapted to apply a twisting force between the mounting bracket and the steering assembly sufficient to take up any radial play in the pivot.
Most preferably, the twisting force (or torque) applied to the steering column assembly by the biasing means is greater than the maximum reactional twisting force which can be applied to the pivot due to operation of the motor. In this manner, the biasing force always exceeds the reaction force of the motor so that the free play in the pivot remains taken up under all conditions.
The biasing means may comprise a spring assembly which is attached to the steering assembly at a point laterally offset from the axis of the steering column about which the reaction torque is generated by the motor. The spring assembly may be attached to the gearbox. The spring assembly may comprise a single spring which exerts a torsional force on the pivot pin via the steering column assembly. The spring may be a helical spring.
In a modification, the biasing means may further be adapted to counter-balance all or at least part of the unbalanced weight of the steering column assembly, making it easier to adjust the height of the steering wheel. Preferably, this is achieved by providing a mounting point for the biasing means on the steering assembly which is offset radially from the axis of the pivot in a direction parallel to the steering column axis as well as being offset laterally from the axis of the steering column.
Preferably, the pivot comprises a pivot pin which is adapted to engage at each end with the mounting bracket and support the steering assembly by passing through a portion of the gearbox housing at a point around the center of the pivot pin. Alternatively, the pivot pin may comprise a spaced apart first and second pivot pins, with each pivot pin supporting the steering assembly on a respective side of the axis of the steering column assembly. The pivot pins may work in bushes in openings in the mounting.
A clamping device may also be adapted to be operable to fix the steering assembly in a predetermined position once adjustment of the angle of tilt has been made. The clamping device is preferably adapted so that the majority of the reaction torque is transferred to the mounting bracket through the pivot and not through the clamp due to the pivot means being comprised of very stiff components.
Therefore, by providing a biasing means, it is possible to overcome any undesirable vibration effects which may arise due to radial clearances present between the pivot pin(s) and the respective opening(s) or bushing(s) in the mounting bracket and steering column assembly.


REFERENCES:
patent: 4774851 (1988-10-01), Iwanami et al.
patent: 5090730 (1992-02-01), DeRoucher et al.
patent: 5498032 (1996-03-01), Thomas
patent: 6044723 (2000-04-01), Eda et al.
patent: 2226285 (1990-06-01), None
patent: 2-102807 (1990-04-01), None
XP 000635471 548/Research Disclosure, “Column Mounted Electric Power Steering Rake and Telescope Steering Column Assembly”.

Affiliated with

Also associated with

Rating

Steering assemblies does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Steering assemblies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Steering assemblies will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2605914