GB2353768A

GB2353768A - Collapsible vehicle steering column

Info

Publication number: GB2353768A
Application number: GB9920387A
Authority: GB
Inventors: Graham Stephen John Bambrook
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-08-28
Filing date: 1999-08-28
Publication date: 2001-03-07
Also published as: GB9920387D0

Abstract

A collapsible vehicle steering column has an upper column section (10) and a lower column section (12) and is supported by two bearings (22, 30) in an outer casing (20) which is attached to the body of a vehicle. In the event of an impact, the upper column section (10) is forced downwards bringing a locating ring (38) at the lower end of the upper column section (10) into contact with a tapered aperture (37) in the outer casing (20) to provide radial location and maintain alignment of the steering column during collapse.

Description

2353768 Vehicle SteerinLy Columns The present invention relates to

steering columns for vehicles, and in particular to improvements in their ability to absorb energy during frontal impact.

It is known to provide a vehicle steering column formed in two sections which can slide longitudinally relative to each other allowing the column to collapse when the vehicle is in a frontal impact to reduce injury to the driver. In order to ensure that the column can collapse and does not bind up on impact it is desirable to support the column at the point of overlap between the upper and lower sections. However, for best functioning during normal operation it is desirable to support the column by bearings only at each end.

Accordingly the present invention provides a steering column assembly comprising an upper column section and a lower column section arranged to move longitudinally relative to one another to allow collapse of the column, and supporting means for supporting the column in a vehicle wherein aligning means are provided and arranged so that, in the event of an impact of the vehicle, the aligning means is brought into operation to locate one of the sections radially relative to the supporting means so as to maintain alignment of the two sections during collapse of the column.

Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a section through a steering column assembly according to a first embodiment of the invention, and Figure 2 is a section through a steering column assembly according to a second embodiment of the invention.

Referring to Figure 1, in a first embodiment of the invention, the steering column assembly comprises an upper column section 10 arranged to have a steering wheel connected to its upper end 11 and a lower column section 12 arranged to have its lower end 13 connected to a steering gear such as the pinion of a rack and pinion steering system. The upper column 10 is hollow and has internal splines 14 at its lower end 16 which cooperate with splines 17 on the upper end 18 of the lower section 12 to transmit torque during normal operation, and allow relative axial movement of the two sections 10, 12 during collapse of the column.

An outer casing 20, which is rigidly mounted on the vehicle body, houses the upper column section 10, and supports it at its upper end by means of a bearing 22. The upper column section 10 is located longitudinally against the bearing 22 by means of a star washer 24 on one side and a Belleville washer 26 and circlip 28 on the other side. The lower end of the lower column section 12 is supported in a second bearing 30 which is supported in the vehicle body. The outer casing 22 extends down the column to the region 32 of overlap between the two column sections 10, 12 and has a seat member 34 screwed into its lower end 36. The seat member has an aperture 37 through it through which the steering column extends. The upper portion of the aperture is flared outwards towards the upper end of the column. A locating ring 38 is fixed around the lower end 16 of the upper column section 10 and has an outer surface 40 which tapers inwards towards the lower end of the column. The tapered surface 40 on the locating ring 38 and the flared surface of the aperture 37 are of the same diameter so that they can fit together, but are located so that, under normal conditions, the locating ring 38 is spaced slightly upwards from the seat member 34 so that there is a small gap 42 between the two. Therefore, under normal operating conditions the steering column 10, 12 is supported relative to the vehicle body solely by the two bearings 22, 30, there being no contact between the lower end 36 of the outer casing 20 and the column.

In the event of a frontal impact of the vehicle the driver will be thrown against the steering wheel producing a downwards force on the upper steering column section 10 which can be resolved into a longitudinal component A which tends to push the upper column section 10 downwards, and a radial component B which produces a moment about the upper bearing 22 urging the lower end of the upper column section 10 downwards in the direction of the arrow C. This moment tends to cause the two column sections 10, 12 to bind together preventing effective axial collapse of the column. However, the component A of the driver's impact force pushes the upper column section downwards, compressing the Belleville washer 26 and pushing the locating ring 38 into contact with the seat member 34 which brings it into operation to support and locate the lower end of the upper column section 10 radially. This maintains alignment of the two column sections and allows the column to collapse axially in the desired manner.

Referring to Figure 2, in a second embodiment of the invention parts corresponding to those in the first embodiment are given the same reference numerals preceded by a 1. In most respects the system is the same as that of Figure 1. However, the Belleville washer 26 and circlip 28 are replaced solely by a single circlip 128 which prevents any downward movement of the upper column section 110. Also the locating ring 38 is replaced by a locating wedge 138 which is also in the form of a ring and fits around the upper column section 10 just below the seat member 134. The aperture 137 through the seat member flares outwards towards the lower end of the column, and therefore towards the locating wedge 138, and the locating wedge tapers inwards towards the upper end of the column. An actuator mechanism 129 is also provided on the upper column section 10 for moving the locating wedge 138 into the aperture 137 in the seat member 134. The actuator mechanism 129 can be hydraulic or electrical or use an explosive device. It is connected to a control unit 131 which uses sensors 133, generally in the form of accelerometers, to determine when the vehicle is involved in a frontal impact. The control unit 131 and sensors 133 can be those used to activate an airbag 5 mounted on the steering wheel.

As with the first embodiment, under normal circumstances the column is only supported by the two bearings 122 130 at its top and bottom ends. However, in the event of a frontal impact the control unit 131 causes the actuator 129 to push the locating ring 138 into the aperture 137 where it provides radial location for the overlapping region of the steering column thereby maintaining alignment during collapse.

Claims

-5CLAIMS

1. A steering column assembly comprising an upper column section and a lower column section arranged to move longitudinally relative to one another to allow collapse of the column, and supporting means for supporting the column in a vehicle wherein aligning means are provided and arranged so that, in the event of an impact of the vehicle, the aligning means is brought into operation to locate one of the sections radially relative to the supporting means so as to maintain alignment of the two sections during collapse of the column.

2. An assembly according to claim 1 wherein said one section is the upper section.

i

3. An assembly according to either foregoing claim wherein said one section is hollow and the other section is arranged to slide inside it on collapse of the column.

4. An assembly according to any foregoing claim wherein the column is supported during normal operation by two bearings, one near each end of the column, and the aligning means is situated between the two bearings.

5. An assembly according to any foregoing claim wherein the aligning means is situated, during normal operation, in an area of overlap between the two sections.

6. An assembly according to any foregoing claim wherein the alignment means is arranged to come into operation on longitudinal displacement of said one section relative to the supporting means.

7. An assembly according to claim 6 wherein the aligning means comprises a tapered member arranged to be urged into a tapered aperture in the supporting means by said longitudinal movement.

8. -An assembly according to claim 7 wherein said one section is arranged to be displaced longitudinally as a result of driver impact.

9. An assembly according to any one of claims 1 to 7 wherein the alignment means includes an actuator and control means arranged to operate the actuator to bring the alignment means into operation in response to detection of a vehicle impact.

10. An assembly according to claim 9 wherein the control means is further arranged to activate an airbag of the vehicle.

11. An assembly substantially as hereinbefore described with reference to the accompanying drawings.