GB2397364A

GB2397364A - Adjustable steering column electrical clamping mechanism actuated with an operating lever

Info

Publication number: GB2397364A
Application number: GB0300945A
Authority: GB
Inventors: Magnus Cooper
Original assignee: NSK Steering Systems Europe Ltd
Current assignee: NSK Steering Systems Europe Ltd
Priority date: 2003-01-16
Filing date: 2003-01-16
Publication date: 2004-07-21
Anticipated expiration: 2023-01-16
Also published as: GB0300945D0; GB2397364B

Abstract

An electrically operated clamping mechanism for an adjustable steering column is actuated by a mechanical actuating lever or handle. The lever moves a slider 3 carrying ramped guide surfaces 10 which deflect a boss 9 of a resilient beam 6 to act on electric switches 4,5 also carried on the slider to momentarily operate a clamping motor (figs 4-8). A barb (13, fig 4) prevents returning the lever to the locked position without actuating the clamping switch 5. The slider is sprung to prevent burning out the motor, and is held in the unclamped position by a detent (15, fig 4). Thus a mechanical actuating lever system can be replicated with a very simple electrical mechanism.

Description

- 2397364

ELECTRICALLY OPERATED CLAMPING MECHANISM

FOR AN ADJUSTABLE STEERING COLUMN FOR A VEHICLE

This invention relates to an electrically operated clamping mechanism for an adjustable steering column for a vehicle.

Adjustable steering columns are normally provided with a clamping mechanism that retains the column in the required position until subsequent adjustment is required. The clamping mechanism may be manually or electrically operated.

A manual clamp is normally actuated by means of a handle or lever attached to the steering column. In most cases, the handle must be pulled towards the driver to open the clamping mechanism so as to allow for steering column adjustment. Once adjustment is complete, the handle or lever is pushed away from the driver to lock the clamping mechanism and thereby to secure the steering column position.

It is also well known that steering column adjustment can be made in the rake and/or reach directions to find the most suitable position of comfort for the driver at the steering wheel.

An electrically operated clamping mechanism is normally actuated by means of an electrical switch in the cabin of the vehicle.

It will be appreciated that the manual and electrical clamping systems are dissimilar in construction and that there will be inevitably other differences in the design and the assembly procedure of the respective vehicles.

According to the present invention, there is provided an electrically operated clamping mechanism for an adjustable steering column for a vehicle, the clamping mechanism being provided with a mechanical actuating lever to enable a driver to cause actuation of the electrically operated clamping mechanism.

The mechanical actuating lever may be arranged to act on at least one electrical switch to actuate the clamping mechanism. Preferably, two switches are provided. The or each switch may be of a single-pole, doublethrow type.

The or each electrical switch may be actuated by means of a slider arrangement linked with the mechanical actuating lever. The slider arrangement may be provided with one or more ramp surfaces of a guide that can cause a member selectively to contact and actuate the or each electrical switch.

In a development of the preferred embodiment, said member comprises a resilient beam which is attached at one end and has a free region at its other end or intermediate its ends and extends substantially parallel to the slider arrangement and is located such that its free region can interact with the ramp surface(s) of the slider arrangement; the arrangement being such that sliding movement of the slider arrangement will cause the resilient beam to deflect in one direction or another to contact and thereby to actuate said at least one electrical switch. In addition, the free region of the - 3 resilient beam may be provided with a guide boss that interacts with the ramp surface(s) of the slider arrangement.

The electrically operated clamping mechanism may be operated by a motor, which may be a D.C. motor. In such a case, two electrical switches are provided, one to cause the motor to rotate in one direction to cause the clamping mechanism to come into a clamped condition of the steering column and the other switch causing the motor to rotate in the other direction to cause the clamping mechanism to come into an unclamped condition of the steering column.

Means may be provided to ensure that, when the mechanical actuating lever is moved in a direction to actuate the switch to cause unclamping of the clamping mechanism, the lever is prevented from being returned towards the direction to operate the clamping switch until it has been moved a sufficient amount of travel for the associated ramp surface of the slider arrangement to be engaged to actuate the clamping switch, "hereafter the actuating lever in the opposite direction can be moved to proceed to engage the clamping switch.

The invention also extends to an adjustable steering column for a vehicle incorporating such a clamping mechanism.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: - 4 Fig. 1 is a diagrammatic perspective view of part of an inverted adjustable steering column for a vehicle incorporating an electrically operated clamping mechanism actuable by a mechanical actuating lever, Fig. 2 is a diagrammatic perspective view of part of the steering column shown in Fig. 1, still inverted but viewed from the other side, 10Fig. 3 is a detail perspective view of part of the steering column shown in Fig. 2, Fig. 4 is a schematic view illustrating a preferred switch and circuit arrangement in relation with ramp 15surfaces of a guide of a slider arrangement and an associated resilient switch actuating beam, and Figs. 5 to 8 are schematic views showing subsequent steps of actuation of the switch and circuit arrangement 20of Fig. 4.

Referring to Figs. 1 to 3, the steering column assembly illustrated is adjustable in both rake and reach directions but it will be appreciated that the present 25concept can be applied to a steering column that is only rake or reach adjustable.

The steering column assembly is equipped with an electrically operated clamping mechanism 1 that can 30retain the steering column in any desired position within an adjustment envelope.

The electrically operated clamping mechanism is actuated by means of a mechanical actuating handle or - 5 lever (not shown) that protrudes through a dashboard of the vehicle in a position to be comfortably operated by the driver. The handle drives a rod or bar 2 that moves a slider 3 of a sliding arrangement that is slidable relative to an underside of the steering column.

The slider 3 is thereby able to be moved in one direction as indicated by the arrow A when unclamping of the steering column is required and in the opposite direction as indicated by the arrow B when clamping is required.

The slider 3 carries two electrical switches 4 and 5. The switches 4 and 5 are also illustrated in Figs. 4 to 8. The switches are preferably of a single-pole, double-throw type and they are disposed in such a manner that each switch can be triggered by a force acting in a perpendicular direction to the direction of motion of the slider 3.

This is more clearly illustrated in Fig. 4 where the perpendicular direction to the direction of motion of the slider indicated by the arrow C of a force required to trigger one switch 4 is opposite to the direction indicated by the arrow D of a force required to trigger the other switch 5.

A resilient beam 6 is provided that is attached at one end 7 to part 8 of the steering column assembly that is unable to move in the main directions of motion A and B of the slider 3. The beam itself has a free (unstrained) position that may be at its other end, or intermediate its ends as shown, that lies generally parallel to the directions of motion of the slider 3. - 6 -

Fig. 3 illustrates in greater detail the relationship between the beam 6 and the slider 3 and it will be noted that the beam 6 is illustrated with part cut away, as is the slider 3.

The beam 6 incorporates a guide boss 9 and the slider 3 incorporates guide 10 forming a system of ramp surfaces. During motion of the slider 3 in the unclamping direction A, a nose 11 of the guide 10 collides with the boss 9 of the beam 6. Due to their relative shapes, the boss 9 is forced to move in a perpendicular direction C to the direction of motion A of the slider 3. This motion causes bending or deflection of the beam 6, which in turn triggers one switch 4 to complete the electrical circuit to drive the motor 16 and therefore to operate the clamping mechanism. The switch 4 remains triggered until the guide 10 has been dragged past the boss 9, whereupon the beam 6 springs back to its free position and the switch 4 resets itself.

The duration of time for the switch 4 is activated sends sufficient electrical energy to the clamp 1 for it to open. The steering column can now be adjusted.

During subsequent motion of the slider 3 in the clamping direction B. a further nose 12 of the guide 10 collides with the boss 9 of the beam 6. Due to their relative shapes, the boss 9 in this case is deflected in a direction D that is opposite to direction C. This motion causes bending of the beam, which in turn triggers the other switch 5. The switch 5 remains triggered until the guide 10 has been dragged past the boss 9, whereupon the beam 6 springs back to its free position and the switch resets itself.

The duration of time for which the switch 5 is activated sends sufficient electrical energy to the clamping mechanism 1 for it to lock the steering column in the required position.

It will be appreciated that, merely with the features described so far, the operator could potentially move the handle or lever, and therefore the slider 3, in the unclamping direction A until the unclamping switch 4 is activated and the column unclamped. The operator, instead of completing the full distance of the available stroke of the handle or lever, could then push the handle back to the locked position. However, doing this will not activate the clamping switch 5. This action will then lead to an unacceptable situation where the handle is in the "clamped" position but the steering column is, in reality, unclamped.

In order to overcome this condition, the guide 10 is equipped with a barb 13. During the unclamping motion, the guide 10 of the slider passes the barb at a point before the unclamping switch 4 can be activated. This prevents the unacceptable situation described above, because the barb 13 then prevents the operator from returning the handle or lever and slider 3 fully to the "clamped" position without first having completed the unclamping and then the clamping procedures.

It is also evident that the duration of the supply of electrical power to the clamping device is dependent upon the speed at which the operator moves the handle or lever. Indeed, with system merely comprising the features described so far, the operator could leave the handle in an intermediate position such that electricity continues to flow in the circuit. There would then be a potentially for the clamping motor to burn out.

In order to minimise the possibility of this situation, the slider 3 can be connected by resilient means such as a tension spring 14 to the part 8 of the steering column that is unable to move in the main directions of motion of A, B of the slider. The spring 14 acts to return the slider to the clamped position when the operator releases the handle. However, there should be the possibility of maintaining the slider in the unclamped position, while the operator adjusts the steering column. This can be achieved by means of a detent 15 on the guide 10. The operator can unclamp the steering column in the manner previously described, and then release the handle when the operator hears or feels the boss 9 click into the detent 15. At this point, the handle can be released and the detent 15 will prevent the spring 14 from pulling the slider 3 back in the direction of the clamped position. Furthermore, when the boss 9 clicks into the detent 15, the beam 6 returns partly to its free state, sufficiently far for the unclamping switch 4 to be released. Therefore, when the slider is in this detent position, electrical power is not being supplied to the clamping mechanism.

After adjustment is completed, the operator pulls the handle once more in the unclamping direction A for a short distance until the entire guide 10 has moved clear of the boss 9 of the beam 6. The beam then returns fully to its free state. The operator can then release the handle, whereupon the spring 14 returns the slider 3 to the clamped position, and in the process operates the clamping switch 5 in the manner previously described. 9 -

It will be appreciated that the present construction can be used in a situation where a manually-operated steering column clamping mechanism has been upgraded to an electrical type.

The clamping mechanism can be operated by means of a handle or lever that is similar in appearance, location, fitting procedure and operation to the handle used to operate a manually-driven clamping mechanism.

There is no requirement for a separate switch on the dashboard of the vehicle.

Furthermore, the electrical system of the clamping mechanism itself can be very simple. If the device is constructed in the manner described, using a pair of single-pole, double-throw switches and the circuit illustrated, then the clamping mechanism can be driven by a simple DC motor that rotates in one direction to clamp the steering column and in the opposite direction to unclamp.

If, in normal use, the switches 4, 5 are activated for long enough for the motor to complete the clamping and unclamping actions fully, then there is no need to provide any electronic timer or additional switch to ensure that the clamping/unclamping actions are completed. Furthermore, if a mechanical safeguard against prolonged running of the clamp motor is provided, then no electronic devices are required to prevent this. -

Claims

Claims 1. An electrically operated clamping mechanism for an adjustable

steering column for a vehicle, the clamping mechanism being provided with a mechanical actuating lever to enable a driver to cause actuation of the electrically operated clamping mechanism.
2. A clamping mechanism according to claim 1, wherein the mechanical actuating lever is arranged to act on at least one electrical switch to actuate the clamping mechanism.
3. A clamping mechanism according to claim 2, wherein the mechanical actuating lever acts through a mechanical linkage that acts on said at least one electrical switch.
4. A clamping mechanism according to claim 2 or 3, wherein there are two of said electrical switches.
5. A clamping mechanism according to claim 2, 3 or 4, wherein the or each switch is of a single-pole, double-throw type.
6. A clamping mechanism according to claim 3, 4, 5 or 6, wherein the or each electrical switch is actuated by means of a slider arrangement forming part of the mechanical linkage linked with the mechanical actuating lever. !
7. A clamping mechanism according to claim 6, wherein the slider arrangement is provided with one or more ramp surfaces of a guide that can cause a member selectively to contact and actuate the or each electrical switch.
8. A clamping mechanism according to claim 7, wherein said member comprises a resilient beam which is attached at one end and has a free region at its other end or intermediate its ends and extends substantially parallel to the slider arrangement and is located such that its free region can interact with the ramp surface(s) of the slider arrangement; the arrangement being such that sliding movement of the slider arrangement will cause the resilient beam to deflect in one direction or another to contact and thereby to actuate said at least one electrical switch.
9. A clamping mechanism according to claim 8, wherein the free region of the resilient beam is provided with a guide boss that interacts with the ramp surface(s) of the slider arrangement.
10. A clamping mechanism according to any one of the preceding claims, and being operated by a motor.
11. A clamping mechanism according to claim 10 as appendant to claim 2, wherein the motor is a D.C. motor and wherein two of said electrical switches are provided, one to cause the motor to rotate in one direction to cause the clamping mechanism to come into a clamped condition of the steering column and the other switch causing the motor to rotate in another direction to cause - 12 the clamping mechanism to come into an unclamped condition of the steering column.
12. A clamping mechanism according to claim 11, as appendant to claim 6, wherein means are provided to ensure that, when the mechanical actuating lever is moved in a direction to actuate one switch to cause unclamping of the clamping mechanism, the lever is prevented from being returned towards the direction to operate the other switch to cause clamping of the clamping mechanism until the mechanical actuating lever has been moved a sufficient amount of travel for the associated ramp surface of the slider arrangement to be engaged in such a way to actuate the clamping switch, "hereafter the actuating lever can be moved in the opposite direction to proceed to engage the clamping switch.
13. A clamping mechanism according to any one of the preceding claims, wherein the mechanical actuating lever is adapted to be located on an adjustable steering column assembly in a position that would otherwise be occupied by an actuating lever of a known, purely mechanically operated, steering column clamping mechanism.
14. An electrically operated clamping mechanism for an adjustable steering column for a vehicle, substantially as hereinbefore described, with reference to the accompanying drawings.
15. An adjustable steering column for a vehicle incorporating an electrically operated clamping mechanism according to any one of the preceding claims.