GB1567263A

GB1567263A - Safety steering column assembly for motor vehicles

Info

Publication number: GB1567263A
Application number: GB447477A
Authority: GB
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 1976-02-04
Filing date: 1977-02-03
Publication date: 1980-05-14
Also published as: IT1086202B; FR2340235A1; FR2340235B1; DE2604214C3; DE2604214A1; DE2604214B2

Description

(54) A SAFETY STEERING COLUMN ASSEMBLY FOR MOTOR VEHICLES (71) We, BAYERIscHE MOTOREN WERKE AKTIENGsELLscHAFT, a German Body Corporate, of BMW-Haus, Petuelring 1130, 8 München 40, German Federal Republic, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a safety steering column assembly mounted in a motor vehicle, having at least one pivoted link member and a bearing bracket for connecting a column supportingly surrounding a steering shaft with a vehicle body, the bearing bracket being fitted with clamping means for axially adjusting the position of the steering column.

A safety steering column assembly of the above construction is described in U.K.

Patent Specification No. 1,365,965 the bearing bracket of the said assembly being designed to absorb the energy of an impact by its own deformation. Experience has shown that, in accidents, the forces of reaction of the steering column and the steering wheel to the impact of a body thrown against the steering wheel may, under certain conditions in this existing form of construction, still be rather high.

It is therefore an aim of the present invention to provide a safety steering column assembly which is of simple design, but which, in the event of the driver's body being thrown against the steering wheel, will nevertheless be capable of yielding a considerable distance without generating reactive forces that include peaks.

With this aim in view, the invention is directed to a safety steering column asassembly of the construction described in the opening paragraph of this Specification, in which means of attachment of the bearing bracket to the vehicle body are provided which are adapted to release when a specified shock load acts substantially parallel to the axis of the steering shaft on the steer ing column, and a roll-back metal strip bent approximately into the shape of a "U" is provided to absorb the shock by its rollback deformation, the two limbs of the metal strip extending substantially parallel to the steering shaft with one limb being attached to the vehicle body and the other limb being secured to the bearing bracket.

The above-described assembly permits the energy-absorbing capacity of the metal strip to be readily controlled, for instance by variation of the thickness of the metal strip, the width of the strip or its cross-sectional shape. By increasing the length of the limbs of the U-shaped roll-back metal strip, it is possible to provide for a displacement of considerable length in the event of an impact, and the energy of the impact to be absorbed throughout the length of the displacement.

In a preferred form of the invention, the pivoted link member has pivoted ends one of which is adapted to release when a specified tensile load in the link is exceeded. This has the advantage that the link member which, when the steering column is fitted in a motor vehicle, forms one of the elements connecting the steering column to the vehicle body, will not hinder the displacement of the steering column towards the steering mechanism following an impact when the link in the course of this motion assumes a position that is more nearly parallel to the steering shaft. Although at the instant of impact the longitudinal forces acting on the link member may not at first be very con- siderable, they rapidly rise as the steering column continues to move. Hence, when the link has pulled away from one of its pivots, the only resistance to the continued displacement of the steering column and wheel will be that due to the force required to deform the rollback metal strip and, as already mentioned, this can be very satisfactorily controlled throughout the process of deformation.

By way of example, two embodiments of the invention are shown in the accompanying drawings, in which: Figure 1 is a side view of the principal parts of one safety steering column assembly according to the invention Figure 2 is a view in the direction of arrow II in Figure 1; Figure 3 is a fragmentary view corres ponding to that in Figure I of a slightly modified form of construction, and Figure 4 is a detail of the drop link suspension.

The safety steering column assembly of a passenger motor vehicle illustrated in Figure 1 comprises a steering shaft 1 which cooperates with the steering mechanism, not shown, in such a way that it is capable of yielding axially in relation thereto. In the illustrated embodiment, the steering shaft 1 is surroundingly supported by a jacket tube which itself is mounted inside a steering column 3 which is connected to the vehicle body 4 by a pair of pivoted link members 12 and a bearing bracket 2. The bearing bracket is fitted with clamping means K which, when released, permit the jacket tube associated with the steering column 3 to be moved to and fro for adjusting the length of the steering column to the driver's needs.

When the clamping lever has been pulled tight, the clamping means K locates the steering column and hence the steering wheel 11 in the desired position.

The means of attaching the bearing bracket carrying the clamping means K to the vehicle body 4 are so designed that they will release from the vehicle body 4 when a given impact load on the steering column vl'a the steering wheel 11 is exceeded. For this purpose, and as will be understood from Figure 2, a transverse edge of the bearing bracket 2 is provided with slots which open in the direction towards the steering wheel. Bolts 8 are received into these slots, and nuts 9 on the bolts serve for securing the bearing bracket 2 to the vehicle body 4.

When a specified load acting substantially parallel to the axis of the steering shaft 1 in the direction ;towards the steering mechanism is exceeded, the frictional force holding the bracket 2 on vehicle body 4 will be overcome and the bolts 8 which are retained by the body 4 of the vehicle will slip out of the slots 10. The bolt 8 on the side where teh link members 12 are situated will be pushed by the bracket 2 out of a slot 10t formed in the vehicle body with its open end facing the steering mechanism. For the purpose of consuming the energy of the impact, an approximately U-shaped roll-back metal strip 5 is provided with its limbs 6 and 7 extending substantially parallel to the axis of the steering shaft 1. One end portion of limb 6 is welded to the vehicle body 4, while the end portion of the other limb 7 is secured to the bearing bracket 2 by the bolt 8 which is on the left in Figure 2. It will also be understood from Figure 2 that the roll-back strip 5 is initially an ordinary flat metal stamping of elongated rectangular shape which may contain punchedout openings of different widths for controlling the manner in which the deforming force is absorbed. Alternatively, the same purpose of control can be achieved by the provision of arbitrarily-shaped indentations or by variations in width and possibly even of the thickness of the metal stamping.

In the slightly modified version shown in Figure 3, a roll-back metal strip 51 is provided in which the limb 71 attached to the bearing bracket 21, as indicated by broken lines, has an extension which bends back towards the vehicle body 4 to which its end is attached. Dot-dash outlines indicate the shape assumed by the roll-back strip 51 in the course of its roll-back deformation.

In the embodiment of Figure 3, bearing block 21 is released in the same manner or similar manner as in the example of Figures 1 and 2-i.e., the vehicle structure is formed with slots open in the yield direction of the bearing block 2, whereas the rear screws extend through open slots in block 21 against the yield direction.

The two link members 17 are designed to give way at their pivots 19 when a specifield tensile load on the links is exceeded.

This enables the steering column 3, as has already been mentioned, to yield a considerable distance towards the steering mechanism without being substantially impeded by the link members 17. To enable the link members 17 to pull away, an open slot 21 may be cut into their ends, extending from the bearing hole 20 for the pivot pin of the link member 17 to the edge at the top end of the member. At a given tensile load, this slot in the link member 17 will widen out and allow the link to be pulled off the pin. The force at which the link member 17 will be released can he more precisely defined if the sides of the slot 211, as shown in Figure 3, are arranged to merge into the hole 20t tangentially and to converge towards the open upper end of the slot. With advantage, a preferably synthetic plastics bush 23 having an extension which fills the convergent slot 211 may be inserted between the pivot pin 22 and its hole 201 in the link member 17. This causes the link members 17 to detach themselves from their pins 19 with a particularly smooth action, thereby preventing the steering column when yielding to impact from having to overcome pronounced reactive peak loads when releasing the link members.

WHAT WE CLAIM IS:- 1. A safety steering column assembly mounted in a motor vehicle, having at least one pivoted link member and a bearing bracket for connecting a column supportingly surrounding a steering shaft with a vehicle Ibody, the bearing bracket being fitted with clamping means for axially adjusting the position of the steering column, in which

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ponding to that in Figure I of a slightly modified form of construction, and Figure 4 is a detail of the drop link suspension. The safety steering column assembly of a passenger motor vehicle illustrated in Figure 1 comprises a steering shaft 1 which cooperates with the steering mechanism, not shown, in such a way that it is capable of yielding axially in relation thereto. In the illustrated embodiment, the steering shaft 1 is surroundingly supported by a jacket tube which itself is mounted inside a steering column 3 which is connected to the vehicle body 4 by a pair of pivoted link members 12 and a bearing bracket 2. The bearing bracket is fitted with clamping means K which, when released, permit the jacket tube associated with the steering column 3 to be moved to and fro for adjusting the length of the steering column to the driver's needs. When the clamping lever has been pulled tight, the clamping means K locates the steering column and hence the steering wheel 11 in the desired position. The means of attaching the bearing bracket carrying the clamping means K to the vehicle body 4 are so designed that they will release from the vehicle body 4 when a given impact load on the steering column vl'a the steering wheel 11 is exceeded. For this purpose, and as will be understood from Figure 2, a transverse edge of the bearing bracket 2 is provided with slots which open in the direction towards the steering wheel. Bolts 8 are received into these slots, and nuts 9 on the bolts serve for securing the bearing bracket 2 to the vehicle body 4. When a specified load acting substantially parallel to the axis of the steering shaft 1 in the direction ;towards the steering mechanism is exceeded, the frictional force holding the bracket 2 on vehicle body 4 will be overcome and the bolts 8 which are retained by the body 4 of the vehicle will slip out of the slots 10. The bolt 8 on the side where teh link members 12 are situated will be pushed by the bracket 2 out of a slot 10t formed in the vehicle body with its open end facing the steering mechanism. For the purpose of consuming the energy of the impact, an approximately U-shaped roll-back metal strip 5 is provided with its limbs 6 and 7 extending substantially parallel to the axis of the steering shaft 1. One end portion of limb 6 is welded to the vehicle body 4, while the end portion of the other limb 7 is secured to the bearing bracket 2 by the bolt 8 which is on the left in Figure 2. It will also be understood from Figure 2 that the roll-back strip 5 is initially an ordinary flat metal stamping of elongated rectangular shape which may contain punchedout openings of different widths for controlling the manner in which the deforming force is absorbed. Alternatively, the same purpose of control can be achieved by the provision of arbitrarily-shaped indentations or by variations in width and possibly even of the thickness of the metal stamping. In the slightly modified version shown in Figure 3, a roll-back metal strip 51 is provided in which the limb 71 attached to the bearing bracket 21, as indicated by broken lines, has an extension which bends back towards the vehicle body 4 to which its end is attached. Dot-dash outlines indicate the shape assumed by the roll-back strip 51 in the course of its roll-back deformation. In the embodiment of Figure 3, bearing block 21 is released in the same manner or similar manner as in the example of Figures 1 and 2-i.e., the vehicle structure is formed with slots open in the yield direction of the bearing block 2, whereas the rear screws extend through open slots in block 21 against the yield direction. The two link members 17 are designed to give way at their pivots 19 when a specifield tensile load on the links is exceeded. This enables the steering column 3, as has already been mentioned, to yield a considerable distance towards the steering mechanism without being substantially impeded by the link members 17. To enable the link members 17 to pull away, an open slot 21 may be cut into their ends, extending from the bearing hole 20 for the pivot pin of the link member 17 to the edge at the top end of the member. At a given tensile load, this slot in the link member 17 will widen out and allow the link to be pulled off the pin. The force at which the link member 17 will be released can he more precisely defined if the sides of the slot 211, as shown in Figure 3, are arranged to merge into the hole 20t tangentially and to converge towards the open upper end of the slot. With advantage, a preferably synthetic plastics bush 23 having an extension which fills the convergent slot 211 may be inserted between the pivot pin 22 and its hole 201 in the link member 17. This causes the link members 17 to detach themselves from their pins 19 with a particularly smooth action, thereby preventing the steering column when yielding to impact from having to overcome pronounced reactive peak loads when releasing the link members. WHAT WE CLAIM IS:-

1. A safety steering column assembly mounted in a motor vehicle, having at least one pivoted link member and a bearing bracket for connecting a column supportingly surrounding a steering shaft with a vehicle Ibody, the bearing bracket being fitted with clamping means for axially adjusting the position of the steering column, in which

means of attachment of the bearing bracket to the vehicle body are provided which are adapted to release when a specified shock load acts substantially parallel to the axis of the steering shaft on the steering column, and a roll-back metal strip bent approximately into the shape of a "U" is provided to absorb the shock by its roll-back deformation, the two limbs of the metal strip extending substantially parallel to the axis of the steering shaft with one limb being attached to the vehicle body and the other limb being secured to the bearing bracket.

2. A safety steering column assembly ac cording to claim 1, in which the pivoted link member has pivoted ends one of which is adapted to release when a specified tensile load in the link is exceeded.

3. A safety steering column assembly ac cording to claim 2, in which an open-ended slot extends from a bearing hole for a pivot pin in the link to the adjacent end of the link.

4. A safety steering column assembly according to claim 3, in which the slot merges substantially tangentially into the hole and converges towards its open end.

5. A safety steering column assembly according to claim 4, in which, interposed between the pivot pin and its bearing hole in the drop link, is a bush provided with an extension which fills the convergent slot.

6. A safety steering column assembly according to claim 5, in which the bush is made of a synthetic plastics material.

7. A safety steering column assembly substantially as described herein and as illustrated in the accompanying drawings.