GB2575886A

GB2575886A - A steering column assembly

Info

Publication number: GB2575886A
Application number: GB1813003.9A
Authority: GB
Inventors: Wojtalik Artur
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: GB2575886B; GB201813003D0; DE102019210385A1

Abstract

A steering column assembly 100 for a vehicle has a shroud 102 supporting a steering shaft 104, a support bracket 108 securable to a fixed part of the vehicle with two arms depending from a base 130 to embrace shaft 104, a clamp pin 112 extending through an opening in each arm 110a, 110b of the bracket and through a slot in shroud 102, and a clamp mechanism moveable between an unclamped position, in which shroud 102 is adjustable for rake relative to bracket 108, and a clamped position, in which shroud 102 is fixed relative to bracket 108. The clamp mechanism in use secures shroud 102 by squeezing arms 110a, 110b of bracket 108 onto the shroud. At least one arm 110a, and preferably also the other arm 110b, comprises a plate connected at an upper end to the base which has a slot cut into it defining a flexible leaf (160, Figure 4) having an opening through which the clamp pin passes.

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 undamped 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 including two arms that depend from a base portion to embrace the shroud; a clamp pin that extends through an opening in each of the arms of the support bracket and a slot in the shroud; 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 at least one arm of the support bracket comprises a plate which is connected at an upper end to the base portion of and has a slot cut into it that defines a boundary of a flexible leaf, the leaf include an opening through which the clamp pin passes.

Both arms may be provided with a respective slot that defines a leaf, each leaf having an opening through which the clamp pin passes.

The or each slot may be substantially U-shaped to surround three sides of the leaf, the fourth side connecting the leaf to the remaining portion of the bracket arm. The leaf and remaining portion of the bracket arm may be formed as a single component.

Each leaf may lie substantially in the plane of the surround portion of the bracket arm. The region where the leaf joins the remaining portion of the bracket arm may lie within the plane of the remaining portion of the bracket arm. This may be achieved during manufacture by stamping out the bracket arm with the leaf from a single sheet of material. Other forming methods instead of stamping could, of course, be used such as cutting out the slot to form the leaf before or after further shaping steps.

The leaf, or where two leaves are provides at least one leaf, may be permanently deformed at rest and prior to assembly within the steering column assembly such that a portion of the leaf protrudes out of the plane of the surround bracket arm in a direction towards the other arm. The leaf may be otherwise resiliently flexible, so that it functions as a spring when deformed to store energy that may subsequently be released during unclamping of the assembly.

The deformation may be such that the leaf is curved from a point close to the root of the leaf where is joins the surrounding bracket to the free end of the leaf.

The leaf may in use deflect in the manner of a leaf spring to apply a load to the shroud.

The whole leaf may be curved, or only a portion close to the free end.

In addition to the leaf being permanently deformed out of the plane of the surrounding bracket, the bracket arm may also be curved such that the bracket arm also functions as a leaf spring. This means that both the leaf and the bracket are curved when the clamp mechanism is unclamped and flattened or partially flattened when the clamp mechanism is clamped.

The spacing between the two leaves, or between one leaf and the opposing arm of the bracket, when at rest prior to assembly into the steering column assembly, may be shorter than the width of the shroud that is located between the arms when assembled such that in use the leaf is provided with a bending load when the clamp mechanism is unclamped.

The provision of the curved spring or springs formed by the leaf and/or bracket is beneficial in preventing rattle of the shroud when the clamp mechanism is undamped.

Where only one leaf is provided, or only one is deformed out of the plane of the surrounding bracket, it will bias the shroud onto the other bracket arm helping to ensure the shroud does not rotate around its long axis during adjustment for rake or reach with the clamp mechanism unclamped.

The or each leaf may be bent along at least one fold line, the fold line being substantially vertical.

The U-shape slot may extend along a substantially horizontal top edge of the leaf, a substantially horizontal bottom edge of the leaf, and a substantially vertical edge of the leaf to leave a connection between the leaf and surrounding bracket arm that connects the terminal ends of the slot.

The substantially vertical edge of the leaf may be at a side of the leaf closest to the steering wheel end of the shroud, i.e the end that is nearest to the steering wheel when is use.

The leaf may include a cut-out portion on the side of the opening that receives the clamp pin that faces away from the steering wheel.

The leaf may include a secondary slot which defines a further leaf within the leaf. In this arrangement there may be a first slot in the bracket arm defining the leaf which may be generally U-shaped and a secondary slot within the leaf which may also be generally U-shaped with the open end of the secondary slot facing away from the open end of the first slot. This means that the innermost leaf and the main length when deformed out of the plane of the remaining bracket portion form a Z-shape when viewed in cross section.

The opening through which the clamp pin passes may comprise an elongate slot to permit the clamp pin to move up and down along the slot when the clamp mechanism is unclamped to enable rake adjustment of the steering column assembly.

The bracket may comprise a base portion having a central part that is located above the shroud and two side wings that extend out to define anchor points for fixing the bracket to the vehicle body. The central part of the base portion may comprise a generally flat plate and each of the wings may 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. The ends Each arm may define, at the lowermost end furthest from the base portion, and outwardly extending lower wing that connects to each wing of the base portion. Each lower wing may extend upwards 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 side wing of the base portion, arm and lower wing portion may together form a triangular shape when viewed in cross section looking along the long axis of the shroud.

The lower wing and the plate forming the arm may comprise a single dement joining at a fold line. The arm may be connected to the base portion by one or more welds or other fastening means such as rivets or adhesive.

The arm may consist of a single layer, defined by the plate, with the leaf formed in it.

The leaf may also be a single layer, perhaps including a leaf within the leaf.

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 clamp mechanism may include a cam mechanism located at one end of the clamp pin on the opposite side of an 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. Can 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 the leaf 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 I is a cross section view of an embodiment of a steering column assembly in accordance with the first aspect looking along the length of the steering shaft; Figure 2 is a perspective view of the embodiment of Figure 1 with the shroud and shaft and clamp mechanism removed, for clarity; Figure 3 is a plan view of one bracket arm of the assembly of figure 1 showing the leaf and surrounding slot Figure 4 is an enlarged perspective view of the bracket arm of Figure 3 in a first embodiment showing the bending of the leaf slightly out of the plane of the remaining portion of the bracket arm when in a free state; Figure 5 shows the leaf of Figure 4 when viewed in cross section looking along the length of the steering shaft; Figure 6(a) is a schematic plan view of an alternative bracket and (b) is a view is cross section looking along the length of the steering shaft for the alternative bracket; and Figure 7(a) and (b) arc views corresponding to those of Figure 6(a) and (b) for a still further alternative arrangement of bracket am.

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 undamped position of the clamping 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 clamping mechanism is shown in the clamped position in all of the accompanying Figures.

To move from the undamped 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 comprises a base portion 130 that is generally planar and extends across the top of the shroud 102. Each end of the base portion 130 projects outwards to define an upper wing 132,134 portion. The wings define outboard fixing points 150 for securing the bracket to the body of the vehicle. In the example shown bolts (not shown) may pass through holes 136,138 in the wings The bracket also includes, associated with each arm 110a and 110b a respective lower wing 140,142 that is connected 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 slopes downwards and the lower wing slopes upwards when moving away from the shroud so they meet approximately at a mid height point of the bracket arm. The two wings provide two load paths from forces to pass from the bracket arm to the fixed portion of the vehicle.

Figure 2 shows the bracket assembly 108 in perspective with the shroud and clamp mechanism removed, and Figure 3 shows one bracket arm 110a in plan. These clearly show the provision of a leaf 160 cut into the surrounding portion of the bracket arm. This leaf is defined by a generally U-shaped slot 161, with the open end of the u-shaped slot facing away from the end of the shroud that is closest to the steering wheel. This defines a hinge line (represented by a dashed line 162) by which the leaf may flex relative to the remaining portion of the bracket arm. Within the leaf is the substantially vertical elongate slot 114 that the clamp pin 112 passes through.

The leaf 160 being formed from as a single component, in this case in a plate that forms the bracket arm, thereby integral to the bracket arm, means that there is no need for an additional fixture to secure the leaf 160 to the bracket arm 110a. The leaf 160 also lies generally in the plane of the surrounding bracket arm, reducing the overall thickness of the bracket arm and leaf The leaf 160 may be deformed when at rest in a number of ways, as shown in the examples of Figures 4 and 5, Figure 6(a) and (b) and Figures 7(a) and (b).

In the example of Figures 4 and 5, the leaf 160 is a single plate that is curved along its length from the root where it joins the surrounding bracket to the opposing free edge of the leaf 160. This curvature is removed as the clamp mechanism is clamped, placing a load into the leaf 160. When the clamp mechanism is unclamped, the leaf 160 moves back towards the relaxed curved state and in doing so applies a light preload to the shroud. This helps prevent the shroud from moving excessively between the bracket arms.

in the example of Figures 6(a) and (b) an alternative leaf 260 is provided with a single curve but instead of curving away from the plane of the bracket arm 110a by an increasing amount with distance from the root, it initially curves out before then curving back towards the plan of the remaining bracket arm. The curve in this example presents a convex surface where it contacts with the shroud whereas the embodiment of Figure 5 presents a concave surface. As with the example of Figures 4 and 5, this applies a pre-load to the shroud.

Figures 7(a) and (b) show a more complex arrangement in which a secondary leaf 360a is defined within the leaf 360 by a second u-shaped slot. This presents a Z-shaped bracket arm and leaves when viewed in cross section looking along the length of the shaft as shown in Figure 7(b).

Claims

CLAIMS1 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 including two arms that depend from a base portion to embrace the shroud; a clamp pin that extends through an opening in each of the arms of the support bracket and a slot in the shroud; and a clamp mechanism that is movable between an undamped 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 at least one arm of the support bracket comprises a plate which is connected at an upper end to the base portion of and has a slot cut into it that defines a boundary of a flexible leaf, the leaf include an opening through which the clamp pin passes.
2 A steering column assembly according to claim 1 in which both arms are provided with a respective slot that defines a leaf, each leaf having an opening through which the clamp pin passes.
3. A steering column assembly according to claim 1 or claim 2 in which the or each leaf and respective remaining portion of the bracket arm are formed as a single component.
4. A steering column assembly according to any preceding claim in which the region where the leaf joins the remaining portion of the bracket arm lies within the plane of the remaining portion of the bracket arm.
5. A steering column assembly according to any preceding claim in which the leaf is permanently deformed at rest and prior to assembly within the steering column assembly such that a portion of the leaf protrudes out of the plane of the surround bracket arm in a direction towards the other arm.
6. A steering column assembly according to any preceding claim in which the leaf includes a cut-out portion on the side of the opening that receives the damp pin that faces away from the steering wheel.
7. A steering column assembly according to any preceding claim in which the bracket comprises a base portion having a central part that is located above the shroud and two side wings that extend out to define anchor points for fixing the bracket to the vehicle body, the central part of the base portion comprising a generally flat plate and each of the wings also comprising plates which lie out of the plane of the central part of the base portion, and in which each ann defines, at the lowermost end furthest from the base portion, an outwardly extending lower wing that connects to each wing of the base portion.
8. A steering column assembly according to claim 7 in which the lower wing and the plate forming the arm comprise a single element joining at a fold line.
9. A steering column assembly according to claim 7 or claim 8 in which each arm may consists of a single layer, defined by the plate, with the leaf formed in it.