GB2575884A

GB2575884A - A steering column assembly

Info

Publication number: GB2575884A
Application number: GB1813001.3A
Authority: GB
Inventors: Wojtalik Artur; Ponikiewski Pawel
Original assignee: TRW Steering Systems Poland Sp zoo
Current assignee: TRW Steering Systems Poland Sp zoo
Priority date: 2018-07-25
Filing date: 2018-08-09
Publication date: 2020-01-29
Anticipated expiration: 2038-08-09
Also published as: GB201813001D0; DE102019210387A1; GB2575884B

Abstract

A steering column assembly for a vehicle is provided, comprising a shroud 102 supporting a steering shaft 104, a support bracket 108, a clamp pin 112 and a clamp mechanism. Support bracket 108 has a base 130 above shroud 102 and two depending arms 110a, 110b, each including a slot, so that clamp pin 112 extends through the slots and an opening in bracket 108. The clamp mechanism is movable between an unclamped position where shroud 102 is adjustable for rake and a clamped position where shroud 102 is fixed relative to support bracket 108 by squeezing arms 110a, 110b onto shroud 102. Each arm 110a, 110b defines one side of a respective closed section side portion which provides a fixing point 150 for securing the bracket to a fixed portion of the vehicle; these side portions preferably each have three sides formed by the bracket arm and upper and lower wings.

Description

A STEERING COLUMN ASSEMBLY

The present invention relates to improvements in steering column assemblies.

It is known to provide a collapsible steering column assembly comprising a steering shaft that is supported within a steering column shroud. To prevent significant injury to the driver in the event of a crash the steering column should be able to collapse as an axial load is applied through the steering wheel, for instance in a front impact where an unrestrained driver is thrown onto the steering wheel.

A typical collapsible steering column assembly comprises a telescopic shroud, having an outer shroud portion and an inner shroud portion, an end of the inner shroud portion extending into the outer shroud portion. The outer shroud portion may be located closer to the steering wheel, or further from the steering wheel than the inner shroud portion. A telescopic steering shaft, also having an upper and lower shaft part, is supported inside the shroud through one or more bearing assemblies. The steering wheel is fixed to the upper shaft portion. In some cases, the shroud will not include two portions and instead the shroud will simply move relative to the bracket.

The part of the shroud closest to the wheel must be able to move, or collapse, during a crash so as to allow the steering wheel to move forwards relative to the vehicle body but be prevented from moving during normal use. There is also a need to fix the shroud relative to the vehicle body to define the rake position of the steering wheel. This is typically achieved by a clamp mechanism that secures the shroud to a support bracket that is in turn fixed to the vehicle body, perhaps to a cross beam provided behind the dashboard of the vehicle. The clamp mechanism may be adjustable to permit reach adjustment, or rake adjustment, or both, of the steering wheel. In the event of a crash the shroud must be able to move, and this is achieved if it is able to break free of the clamp mechanism, or for the support bracket to be able to break free of the vehicle body, to allow the steering column assembly to collapse telescopically.

A lever may be provided on an end of the a clamp bolt that forms a part of the clamp mechanism that the driver can push or pull to rotate the clamp bolt and thereby operate the clamp mechanism.

Steering column assemblies are known which comprises a support bracket configured to be secured to a fixed part of the vehicle and including two arms that depend from a base portion to embrace the shroud, the shroud being located in the void defined between the two arms. The clamp mechanism includes a clamp pin that extends through an opening in each of the arms of the support bracket and a slot in the shroud, typically in a rail that is fixed to a top surface of the shroud. In use, the clamp mechanism may be moved between an unclamped position in which the shroud can be adjusted for rake relative to the support bracket and a clamped position in which the shroud is fixed relative to the support bracket. This can be effectively achieved if the clamp mechanism applies a pressure to the outside of each arm, pushing the arms onto the shroud to grip the shroud in position.

An object of the present invention is to improve on the aforementioned steering column assemblies.

According to a first aspect, there is provided a steering column assembly for a vehicle, the steering column assembly comprising:

a shroud;

a steering shaft, which is supported by the shroud;

a support bracket configured to be secured to a fixed part of the vehicle and comprises a base portion having a central part that is located above the shroud and two bracket arms that depend from the base portion on respective sides of the shroud, each bracket arm including a slot;

a clamp pin that extends through an opening in the support bracket and the slots in the bracket arms; and a clamp mechanism that is movable between an unclamped position in which the shroud can be adjusted for rake relative to the support bracket and a clamped position in which the shroud is fixed relative to the support bracket; and whereby the clamp mechanism in use secures the shroud to the two arms of the bracket by squeezing the two arms onto the shroud when in the clamped position;

characterised in that each bracket arm defines one side of a respective closed section side portion, the side portion providing a fixing point for securing the bracket to a fixed portion of the vehicle.

Each closed section side portion may have three sides, one vertical side defined by the bracket arm and two further sides defining respective upper and lower wings that extend out from the bracket arm away from the shroud to meet in the proximity of the respective fixing point by which the support bracket is secured to the vehicle body when in use.

The central part of the base portion may comprise a generally flat plate and each of the upper wings may also comprise plates which lie out of the plane of the central part of the base portion, for example extending downwards with optionally an angle of between 10 degrees and 70 degrees from the vertical, and preferably around 50 degrees. These portions may be extensions of a single sheet or material that defines both the central portion and upper wings. The sheet may be shaped to include a plurality of stiffening ribs.

Each bracket arm and associated lower wing may comprise a single sheet of material, the sheet folded or otherwise bent at the interface between the bracket arm and lower wing.

The lower wing and upper wing may overlap in a region of the anchor point and in use may both be trapped between a fixing and the vehicle body.

Each lower wing may extend upwards from the base of the bracket arm at an angle of between 10 degrees and 70 degrees from the vertical (with the lower angle meaning the wing is closer to horizontal than a higher angle).

The two wings and the bracket arm may form a closed section having a triangular cross section when viewed along the axis of the shroud.

The sheets of material for the base portion and upper wings, and the bracket arm and lower wing, may comprise respective metal sheets.

Each closed section may include a webbing portion which spans the closed section to connect the bracket arm to the upper wing, and a further webbing portion which spans the closed section to connect the bracket arm and lower wing.

The webbing portions may be located at one end of the closed section, preferably at the end furthest from the portion of the steering shroud that is nearest the steering wheel when in use.

The webbing portions may be integral to the bracket arm, so that the bracket arm and webbing portions are formed of a single sheet of material. This allows the webbing portions to be formed by folding them out of the plane of the bracket arm during manufacture.

The webbing portions may be welded or otherwise secured at their ends furthest from the bracket arm to the respective upper or lower wings.

Providing a closed sections with the webbing portion(s) spanning the section gives great torsional rigidity to the closed section, providing excellent transfer of load from the clamp mechanism to the vehicle body.

The lower wing and wing of the base portion may overlap in a region where the bracket is secured to the vehicle body, so that they are both clamped to the vehicle body by a fastener that is used to the secure the bracket assembly. This means that the joint between the two parts does not need to be as secure as it would otherwise need to be because the fastener stops them being pulled or sheared apart when a load is applied to the bracket.

The base portion, upper wings, lower wings and bracket arms may be defined by only three sheets of material which are secured together. The three sheets may be simply manipulated during manufacture using stamping and folding processes to form the bracket.

In a preferred arrangement all three sheets may have the same gauge, i.e. same material thickness, for the stock material from which they are produced. This reduces costs as the whole bracket can be manufactured from a single stock material.

The clamp mechanism may include a cam mechanism located at one end of the clamp pin on the opposite side of a bracket arm to the shroud. This may vary in length between the clamped and unclamped position to squeeze the bracket arms onto the shroud. An end stop may be provided at each end of the clamp pin, such as a head or nut.

The cam mechanism may include a fixed cam part and a moving cam part. Movement of the lever may act to rotate the moving cam part relative to the fixed cam part. Cam surfaces of the moving cam part and fixed cam part may result in a length of the cam mechanism changing due to this rotation.

The cam mechanism may include a part that fits within the opening in a leaf formed in one of the arms of the support bracket. This part may prevent the rotation of a fixed cam part of the cam mechanism and may take the form of a block or a pair of locating pins.

In the clamped position, the two bracket arms may be compressed between the cam mechanism and opposing sides of the shroud

An embodiment of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a cross section view of an embodiment of a steering column assembly in accordance with the invention looking along the length of the steering shaft;

Figures 2 to 5 show the support bracket from different angles with the shroud and clamp mechanism removed for clarity; and

Figure 6 shows the three components that form the bracket in an exploded view.

Referring firstly to Figure 1, there is shown a steering column assembly 100 comprising a shroud 102 that houses a shaft 104. The shaft 104 is configured to be attached to a steering wheel (not shown). The shaft 104 is supported by a bearing assembly (not shown) that allows rotation of the shaft 104 relative to the shroud 102.

A support bracket 108 includes two arms 110a and 110b that depend in a substantially vertical direction and provide support and stability to the shroud 102.

A clamp pin 112 passes through vertical slots 114 in the support bracket 108 and a horizontal slot 116 in a clamp rail 118 of the shroud 102. The clamp pin 112 has a stop 120 at one end that prevents the clamp pin 112 being drawn through the support bracket 108. At the other end, a cam mechanism 122 that is rotated by use of a lever 124 enables an effective length of the clamp pin 112, i.e. the length of the clamp pin 112 between the cam mechanism 122 and the stop 120, to be varied. The cam mechanism 122 comprises a fixed cam part 126 and a moving cam part 128, the moving cam part 128 being rotated by the rotation of the lever 124, pushing against the fixed cam part 126 and extending the length of the cam mechanism 122. The clamp pin and the cam and end stops together with the bracket arms and rail define a clamp mechanism.

In the unclamped position of the clamp mechanism, there is sufficient freedom of movement of the arms to allow adjustment of the reach and rake position of the steering column assembly 100 without undue exertion from a user. The clamp mechanism is shown in the clamped position in Figure 1.

To move from the unclamped to the clamped condition the user rotates the level 124. Rotation of the lever 124 leads to extension of the cam mechanism 122 along the clamp pin 112 and thus the cam mechanism 122 extends through the slot 114 in the support bracket 108 and presses on the outside of one of the arms 110a. This arm is pressed into contact with the shroud 102. The shroud 102 is thus pushed over towards the right side of the support bracket 108 and presses the other arm 110b onto the end stop 120 on the clamp pin thus locking the shroud 102 in a desired position relative to the support bracket 108.

The bracket 108 comprises a central part that forms a base portion 130 that is generally planar and extends across the top of the shroud 102. Each end of the base portion 130 is connected to one of the substantially vertical bracket arms 110a,110b that depend from the base portion on respective sides of the shroud. Each bracket arm 110a, 110b forms one side of a closed section side portion and includes a slot through which the clamp pin passes. These box sections define outboard fixing points 150 for securing the bracket 108 to the body of the vehicle.

As shown each box section comprises also an upper wing 132,134 and a lower wing 140,142, the two wings and the vertical bracket arm forming a closed box section that has a triangular cross section when viewed along the axis of the steering shaft 104. In the example shown bolts (not shown) may pass through holes 136,138 in the wings where they overlap. Each closed section side portion therefore has three sides, one vertical side defined by the bracket arm and two further sides defining the respective upper wings 132,134 and lower wings 140,142 that extend out from the bracket arm away from the shroud to meet in the proximity of an anchor point by which the support bracket is secured to the vehicle body when in use.

The central part of the base portion 130 is a generally flat plate and each of the upper wings 132, 134 also comprise plates which lie out of the plane of the central part of the base portion, extending downwards at an angle of between 10 degrees and 70 degrees from the vertical, and preferably around 50 degrees. These portions as shown are extensions of a single sheet or material that defines both the central base portion and upper wings. The sheet may be shaped to include a plurality of stiffening ribs.

Each bracket arm 110am 110b and associated lower wing 140,142 also comprises a single sheet of material, the sheet folded or otherwise bent to form a continuous interface between the bracket arm and lower wing 140,142. Also, as shown, parts 144,146 of the bracket arm are folded around to form end plates 152,154,156,158 that partially close an end face of the box section, giving strength to the box section by bridging between two sides. These also provide additional load paths for forces.

The respective lower wing connect at one end to an upper wing 132,134 of the base portion so that it is outboard from the region where the arm 110a, 110b depends from the base portion and is connected at the opposite end to the bracket arm 110a, 110b at a position spaced from the base portion. The upper wing 132,134 slopes downwards and the lower wing 140, 142 slopes upwards when moving away from the shroud so they meet approximately at a mid height point of the bracket arm 108. The wings provide a variety of load paths for forces to pass from the vertical bracket arm to the fixed portion of the vehicle.

Figure 6 shows the bracket 108 during assembly, where there are three components that are fixed together to form the completed brackets 108. Each section comprises a pressed or otherwise shaped metal sheet, and each sheet as shown has the same gauge.

This reduces the material costs and simplifies manufacture. The largest part forms the base portion and the two upper wings. The two smaller parts each form one bracket arm and lower wing, as well as the end portions that fold round to strengthen the box sections and provide alternative load paths.

Claims

1. A steering column assembly for a vehicle, the steering column assembly comprising:

a shroud;

a steering shaft, which is supported by the shroud;

2. A steering column assembly according to claim 1 in which each closed section side portion has three sides, one vertical side defined by the bracket arm and two further sides defining respective upper and lower wings that extend out from the bracket arm away from the shroud to meet in the proximity of the respective fixing point by which the support bracket is secured to the vehicle body when in use.

3. A steering column assembly according to claim 1 or claim 2 in which the central part of the base portion comprises a generally flat plate and each of the upper wings also comprise plates which lie out of the plane of the central part of the base portion.

4. A steering column assembly according to claim 3 in which a single sheet of material defines both the central portion and upper wings.

5. A steering column assembly according to any one of claims 2 to 5 in which each bracket arm and associated lower wing comprises a single sheet of material, the sheet folded or otherwise bent at the interface between the bracket arm and lower wing.

6. A steering column assembly according to any one of claims 2 to 5 in which the lower wing and upper wings overlap in a region of the anchor point and in use are both trapped between a fixing and the vehicle body.

7. A steering column assembly according to any one of claims 2 to 6 in which each upper wing and respective lower wing and bracket arm form a closed section having a triangular cross section when viewed along the axis of the shroud.

8. A steering column assembly according to any one of claims 2 to 7 in which each closed section includes a webbing portion which spans the closed section to connect the bracket arm to the upper wing, and a further webbing portion which spans the closed section to connect the bracket arm and lower wing.

9. A steering column assembly according to any one of claims 2 to 8 in which the lower wing and respective lower wing overlap in a region where the bracket is secured to the vehicle body, so that they are both clamped to the vehicle body by a fastener that is used to the secure the bracket assembly.