WO2003035451A1

WO2003035451A1 - Steering column clamping mechanism locking device

Info

Publication number: WO2003035451A1
Application number: PCT/GB2002/004839
Authority: WO
Inventors: Seiichi Moriyama
Original assignee: Nsk Steering Systems Europe Limited
Priority date: 2001-10-25
Filing date: 2002-10-25
Publication date: 2003-05-01
Also published as: GB2396591B; GB2396591A; GB0402054D0; GB0125673D0

Abstract

An apparatus to provide additional locking effort, in the event of vehicle crash, of a clamping mechanism of an adjustable steering column (1) for a vehicle, the apparatus having a lock device including a cam (22, 23) actuable on a first tapering lock part (15), there being a second lock body part (14) provided with a reaction surface (16) against which a taper (17) of the first part can react in the event of vehicle crash. A third part (12) engages with the first part in order to hold the first, second and third parts in locking relationship in the event of vehicle crash. When the mechanism is in its clamped condition, the cam acts on the first part to hold it against the third part and, upon crash, the first and second parts interreact by means of their tapering surfaces to firmly wedge these components together.

Description

Steering Column Clamping Mechanism Locking Device

This invention relates to an apparatus to provide additional locking effort, in the event of vehicle crash, of a clamping mechanism of an adjustable steering column for a vehicle .

A vehicle steering column can be rake and/or reach adjustable so as to provide an optimum position of its steering wheel as regards the comfort of the driver.

A clamping mechanism is provided to hold the steering column in its adjusted position. However, in the event of vehicle crash, an air bag, for example, may be activated in the vehicle and the force of any impact of the driver on the air bag will be transmitted to the steering wheel and this can generate a force that will cause the adjustment system of the clamping mechanism to slip through its adjustment range. In some steering column applications, it is indeed intended to be a requirement that the adjustment system does not slip in either the rake or reach or both directions of adjustment in the event of vehicle crash. It is known, for example, that the force required to initiate such slippage in a conventional steering clamping mechanism can be of the order of between 1-2 kN.

According to the present invention, there is provided an apparatus to provide additional locking effort, in the event of vehicle crash, of a clamping mechanism of an adjustable steering column for a vehicle, the apparatus being characterised by a lock device comprising a cam actuable on a first tapering part, a second part provided with a reaction surface against which a taper of said first part can react in the event of vehicle crash and a third part, against which said first part can engage to hold said first, second and third parts in locking relationship in the event of vehicle crash when said first and second parts react against one another; the cam being arranged to act, when the clamping mechanism is in a clamped condition, on said first part normally to engage and hold said first part against said third part, ready to react against said second part in the event of vehicle crash.

The cam may be provided on an actuating member for the clamping mechanism, so as to operate with actuation of the clamping mechanism.

The actuating member may be a rotatable shaft.

The rotatable shaft may be the same shaft as a shaft or bolt upon which an operating handle of the steering column clamping mechanism may be mounted.

The second part may be a tapered block provided with a camming surface to engage the cam and an engagement surface, remote from the camming surface, to engage the third part.

The reaction surface of the second part may be a tapered surface corresponding with and opposed to the taper of the first part to react with it upon relative movement between the first and second parts during vehicle crash.

The third part may be provided with a surface with serrations to engage the first part. The first part may be provided with serrations on a surface thereof that is to engage the third part.

The second part may be such as to be mountable within a vehicle steering column support bracket and be provided with an aperture to receive the actuating member for the clamping mechanism.

The third part may form part of the steering column support bracket itself.

The first part may be provided with resilient means biased so as normally to maintain a clearance between the first and third parts when the cam is not acting to engage and hold the first part against the third part.

The resilient means may be opposed wings or arms with tips that are caused to bear resiliently against surfaces of the second part, so that, when the cam is moved to engage the first part with the third part, this is achieved by overcoming the resilience of the resilient means .

The first part may be made of a rubber or plastics material.

Alternatively, the first part may be provided with metal springs or the like to provide the required resilient bias. The whole of the first part may be made of metal.

The first and second parts may both be provided with two opposed tapering faces that can engage each other in the event of vehicle crash, the cam acting on a nose of the first part forming the camming surface thereof to depress the first part into engagement with the third part .

The second part may be slidably located within the third part.

The apparatus may be provided for a rake and/or reach adjustable steering column for a vehicle.

The invention also extends to a clamping mechanism for an adjustable steering column for a vehicle incorporating at least one apparatus essentially as defined above.

In the case where both rake and reach adjustment is catered for, two sets of the apparatus are provided, one for the rake adjustment clamping mechanism and the other for the reach adjustment clamping mechanism. In such a case, two cams are provided on the actuating member for the clamping mechanism.

The invention further 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: -

Fig. 1 is a diagrammatic perspective view of part of a steering column for a vehicle and incorporating a steering column adjustment system with associated clamping mechanism,

Fig. 2 is a diagrammatic end sectional view showing part of a steering column clamping mechanism incorporating an apparatus to provide additional locking effort, in the event of vehicle crash, of the clamping mechanism,

Fig. 3 is a sectional view, taken along the line A-A in Fig. 2, to show the apparatus in a first, released condition to allow adjustment of the steering column,

Fig. 4 is a view similar to Fig. 3, but showing the apparatus in an engaged condition when the steering column clamping mechanism is locked,

Fig. 5A is a diagrammatic, perspective view of one form of a component part of the apparatus,

Fig. 5B is a view similar to Fig. 5A of another form of that part,

Fig. 6 is a diagrammatic perspective view of another component part of the apparatus,

Fig. 7 is a diagrammatic perspective view of a clamping shaft or bolt of the clamping mechanism of the adjustment steering column, the clamping bolt including two cams to actuate two sets of apparatus, one for a rake adjustment steering column clamping mechanism and the other for a reach adjustment steering column clamping mechanism, and Figs. 8 and 9 are schematic views, each to show the basic principle of operation of the apparatus .

When referring to the drawings, it should be appreciated that they are only diagrammatic and that certain clearances shown have been exaggerated simply for the purpose of a clearer understanding of the operation of the apparatus .

Fig. 1 shows a typical steering column arrangement with a steering column 1 having an outer tube 2 incorporating a steering column adjustment system 3. An intermediate end of the steering column 1 is supported within a lower, fixed bracket 4, whilst the adjustment system 3 is supported within an upper bracket 5 that is arranged to break away from its mounting in the event of vehicle crash. Breakaway capsules 6 to achieve this effect are diagrammatically illustrated.

A clamping handle 7 is attached to a clamping bolt 8 and the adjustment mechanism includes an adjustment slot 9 to allow for rake adjustment of the steering column, the steering column being able to pivot about a rake pivot 10, and an adjustment slot 11 to allow for reach adjustment of the steering column.

Fig. 2 shows the upper, breakaway support bracket 5 in which the steering column outer tube 2 is slidably mounted by means of the clamping bolt 8 which passes through two flanges 12 on opposite sides of the outer tube 2 and, in known fashion, is provided with a cam arrangement 13 to provide the means whereby the clamping mechanism 3 can be clamped and undamped. Also visible in Fig. 2 are parts of two sets of apparatus to provide additional locking effort, in the event of vehicle crash, of the clamping mechanism. The parts visible are tapered lock body parts 14A and 14B, to be described in greater detail later. Suffice it to say that the taper lock body part 14A is associated with rake adjustment of the steering column clamping mechanism, whilst the tapered lock body part 14B is associated with reach adjustment of the steering column clamping mechanism.

Figs. 3 and 4 show in greater detail the apparatus to provide additional locking effort of the clamping mechanism in the event of vehicle crash. A separate set of such apparatus is provided for the reach adjustment aspect and the rake adjustment aspect of the steering column. Of course, the steering column need not be provided with facility for both rake and reach adjustment, in which case only one set of apparatus will be provided.

The apparatus includes a lock device comprising a cam (22, 23 - see Fig. 7) formed by part of the clamping bolt 8, actuable on a first, tapering, lock part 15 set within a cavity provided in a second part constituted by a tapered lock body part 14. As can be seen, the lock body part 14 is provided with at least one surface 16

(two in the example shown) which is tapered to provide a reaction surface against which a taper 7 of the tapering lock part 15, can react in the event of vehicle crash.

The second part forming the tapering lock body part 14 is provided with an aperture through which the cam section (22, 23) of the clamping bolt 8 passes and in which the bolt 8 can rotate.

The lock body part 14 is slidably mounted within the slot 9 or 11 of a third part constituted in the example shown by one of the flanges 12 of the breakaway upper steering column support bracket 5.

The tapering lock part 15 is provided with resilient section including a nose 18 to engage a camming surface of the cam (22, 23) of the clamping bolt 8 and a surface 19, remote from the nose 18, that is intended to come into engagement and lock with a facing surface 20 of the edge of the slot 9, 11 of the bracket flange 12.

Fig. 3 shows the case where the apparatus is in its released position, which corresponds to an undamped condition of the steering column clamping mechanism.

Fig. 4 shows the apparatus in its locked condition, which is achieved by rotating the clamping handle 7 and thus the clamping bolt 8 to bring the steering column clamping mechanism into its clamped condition, the cam of the bolt 8 acting on the nose 18 to depress the part 15 to engage the surface 20 of the side of the slot 9, 11 of the bracket flange 12.

To hold the part 15 clear of the surface 20 when the apparatus is in its unlocked condition, the part 15 is provided with two resilient wings 21 with tips that are caused to bear against adjacent surfaces 22 of the taper lock body part 14 to draw the part 15 clear of the part 12. To provide additional interlocking reliability between the parts 12 and 15, the surface 19 of the part 15 may be provided with serrations 19A as shown in Fig. 5B.

Instead or in addition, the facing surface 20 may be provided with serrations 20A, as shown in the broken-away section of Fig. 3.

The arrows B-B in Fig. 4 illustrate the lift of the cam, whilst the arrows C-C in Fig. 3 illustrate the clearance afforded between the parts 12 and 15 when the apparatus is in its unlocked condition.

As shown in Fig. 7, two cams are shown, the cam 22 being part of the apparatus for working with the rake adjustment mechanism of the steering column, whilst the cam 23 is part of the apparatus for the reach adjustment mechanism of the steering column.

When the apparatus is locked, i.e. takes the condition shown in Fig. 4, the steering column clamping mechanism is, of course, also locked. However, as explained, excess force, perhaps generated by impact of the driver on the air bag, may transmit through the steering column to cause the adjustment system clamped by the clamping mechanism to slip through the adjustment range in the direction of the arrow D in Fig. 4. The drive of this force acts through the clamping bolt 8.

The advantage of the ^■ present apparatus is that it supplements the primary clamping mechanism system to prevent such slippage and it perhaps is best illustrated by the schematics of Figs. 8 and 9, both of which illustrate the apparatus in its locked condition, with zero clearance between the surfaces indicated by reference numeral 24 in Fig. 8. There is, effectively zero clearance between the reaction surfaces 16 and 17 in Fig. 8 but these are shown separated for the purposes of explanation.

As shown in Fig. 9, once slippage of the clamping mechanism does occur, the tapering surfaces 16 and 17 are forced together with ever-increasing frictional resistance, causing the part 15 to jam in the tapering face of the part 14 and thereby further movement is prevented.

As well as the resilient and flexible wings 21, the whole of the nose section 18 of the part 15 can also flex which in itself generates the locking force but also allows for tolerances .

Finally, when the clamping handle 7 is moved to the undamped condition of the clamping mechanism, the resilient wings 21 cause the part 15 to return to the unlocked condition to facilitate normal adjustment of the steering column.

It will be appreciated that the present apparatus provides a self-locking facility over and above the action of the clamping mechanism with the result that the greater the crash force or effort applied, the higher the locking force. The apparatus starts to work even during the initial slip stage of the clamping mechanism.

Claims

1. An apparatus to provide additional locking effort, in the event of vehicle crash, of a clamping mechanism of an adjustable steering column (1) for a vehicle, the apparatus being characterised by a lock device comprising a cam (22, 23) actuable on a first tapering part (15), a second part (14) provided with a reaction surface (16) against which a taper (17) of said first part (15) can react in the event of vehicle crash and a third part (12) , against which said first part can engage to hold said first, second and third parts in locking relationship in the event of vehicle crash when said first and second parts react against one another; the cam (22, 23) being arranged to act, when the clamping mechanism is in a clamped condition, on said first part

(15) normally to engage and hold said first part against said third part (12), ready to react against said second part (14) in the event of vehicle crash.

2. An apparatus according to claim 1, wherein the cam (22, 23) is provided on an actuating member (8) for the clamping mechanism, so as to operate with actuation of the clamping mechanism.

3. An apparatus according to claim 2, wherein the actuating member is a rotatable shaft (8) .

4. An apparatus according to claim 3, wherein the rotatable shaft (8) carries an operating handle (7) of the steering column clamping mechanism.

5. An apparatus according to any one of the preceding claims, wherein the second part (14) is a tapered block provided with a camming surface (18) to engage the cam (22, 23) and an engagement surface (19) remote from the camming surface, to engage the third part (12) .

6. An apparatus according to any one of the preceding claims, wherein the reaction surface of the second part (14) is a tapered surface (16) corresponding with and opposed to the taper (17) of the first part (15) to react with the first part upon relative movement between the first and second parts during vehicle crash.

7. An apparatus according to any one of the preceding claims, wherein the third part (12) is provided with a surface (20) with serrations (20A) to engage the first part (15) .

8. An apparatus according to any one of the preceding claims, wherein the first part (15) is provided with serrations (19A) on a surface (19) thereof that is to engage the third part (12) .

9. An apparatus according to any one of the preceding claims, wherein the second part (14) is such as to be mountable within a vehicle steering column support bracket (5) and is provided with an aperture to receive the actuating member (8) for the clamping mechanism.

10. An apparatus according to any one of the preceding claims, wherein the third part (12) forms part of the steering column support bracket (5) .

11. An apparatus according to any one of the preceding claims, wherein the first part (15) is provided with the resilient means (21) biased normally to maintain a clearance between the first and third parts (15, 12) when the cam (22, 23) is not acting to engage and hold the first part against the third part.

12. An apparatus according to claim 11, wherein the resilient means are opposed wings (21) with tips that are caused to bear resiliently against surfaces (22) of the second part (14), so that, when the cam (22, 23) is moved to engage the first part (15) with the third part (12), this is achieved by overcoming the resilience of the resilient means (21) .

13. An apparatus according to any one of the preceding claims, wherein the first part (15) is made of a rubber or plastics material.

14. An apparatus according to claim 11 or 12, wherein the first part is provided with metal springs or the like to provide the required resilient bias.

15. An apparatus according to claim 14, wherein the first part (15) is made wholly of metal.

16. An apparatus according to any one of the preceding claims, wherein the second part (15) is slidably located within the third part (12) .

17. A clamping mechanism for an adjustable steering column for a vehicle, the steering column being rake and/or reach adjustable and incorporating at least one apparatus according to any one of the preceding claims .

18. A clamping mechanism according to claim 17 and acting to clamp both rake and reach adjustment means, there being a respective apparatus according to any one of claims 1 to 16 for each of said rake and reach adjustment means.

19. An adjustable steering column for a vehicle, incorporating a clamping mechanism according to claim 17 or 18.