GB2579375A

GB2579375A - Steering column assembly

Info

Publication number: GB2579375A
Application number: GB1819464.7A
Authority: GB
Inventors: Anthony Wilkes Mark
Original assignee: TRW Ltd
Current assignee: TRW Ltd
Priority date: 2018-11-29
Filing date: 2018-11-29
Publication date: 2020-06-24
Anticipated expiration: 2038-11-29
Also published as: GB2579375B; GB201819464D0

Abstract

A vehicle steering column assembly 12 for a vehicle has an elongate housing 14 in which is rotatably mounted a shaft 16 to which a steering wheel is attachable at one end. Housing 14 is releasably mounted to a support 26 so that housing 14 is constrained to be moveable along an adjustment axis parallel to the longitudinal axis of the housing. A motor 20 is provided for moving housing along the adjustment axis through a linkage (42, Figure 6), for example a crank or a Cardan gear, connected to housing 14 and driven by an output (54, Figure 6) of motor 20. The assembly is particularly suitable for an autonomous vehicle and may collapse in the event of a serious impact to the vehicle; for example a flexible wire may be secured to housing 14 to absorb energy from a collision, and the connection between the linkage and housing 14 may be shearable.

Description

Steering Column Assembly The present invention relates to retractable steering columns for motor vehicles and in particular, but not exclusively, to retractable steering columns for autonomous vehicles.

Autonomous vehicles are intended to be used primarily in autonomous mode, in which control of the vehicle is carried out without manual intervention.

However, it is desirable for autonomous vehicles to be controllable manually if necessary or desired, and for that reason vehicle controls such as a steering wheel (typically having a "steer-by-wire" operation) must be provided. It is desirable for the steering wheel of such autonomous vehicles to be moved into a stowed condition during autonomous control of the vehicle in order to maximise the space available within the vehicle and the for steering wheel to be moved to an extended, deployed condition for manual control.

It is also desirable for such arrangements to be collapsible in the event of a serious impact to the vehicle to which the steering column assembly is fitted.

In accordance with the present invention, a steering column assembly for a vehicle comprises an elongate housing, a shaft rotatably mounted within the housing and being configured for attachment of a steering wheel at a first end, a housing support to which the housing is releasably mounted, the housing being constrained by the housing support to be displaceable along an adjustment axis parallel to the longitudinal axis of the housing, and displacement means for displacing the housing along the adjustment axis, the displacement means comprising a motor having a rotary output and linkage means driven by the motor output and connected to the housing, which displaces the housing along an axis parallel to the adjustment axis in response to operation of the motor.

The above arrangement eliminates the need for a long and relatively slow lead screw for adjustment of the longitudinal position of the steering column, and replaces it with a compact drive that can react quickly and smoothly.

Preferably, the linkage means converts the rotary output of the motor into a linear motion.

The linkage means may comprise a crank mechanism.

In one embodiment, the linkage means comprises a first gear driven by the output of the motor and wherein the linkage means is engaged with the first gear.

In a preferred embodiment, the linkage means comprises a Cardan gear mechanism.

The linkage means may comprise a carrier pivotally mounted coaxially with the first gear, a second, idler gear rotatably mounted on the carrier and engaged with the first gear, a third gear rotatably mounted on the carrier and engaged with the second idler gear and a crank arm mounted to rotate with the third gear and being pivotally connected to the elongate housing.

The crank arm may be pivotally connected to an intermediate member which is in turn connected to the housing.

In one embodiment, the motor drives a worm screw engaged with a worm gear which is rotatably mounted on a pivot which is fixed with respect to the housing support, the first gear being mounted on the worm gear.

Preferably, when the first gear is mounted coaxially with the worm gear and is constrained to rotate with it.

The steering column assembly may further comprise means for absorbing energy in the event of an impact of sufficient magnitude to break the connection between the linkage and the housing.

The means for absorbing an impact may comprise a flexible wire at its first end secured to the housing and being configured to have a tension applied to it in the event of an impact sufficient to break the connection between the linkage and the housing.

In one embodiment, the flexible wire passes partially around a guide means fixed with respect to the housing support.

In this way, in the event of an impact which breaks the connection between the linkage and the housing, the passage of the flexible wire around the guide means as the housing moves with respect to the housing support will absorb a proportion of the energy of the impact.

Preferably, the flexible wire is guided in an arcuate path around the guide means.

In one embodiment, the flexible wire passes partially around one or more further guide means fixed with respect to the housing.

Preferably, the flexible wire is guided in an arcuate path around the or each further guide means.

Preferably, the connection with the linkage and the housing is configured to be shearable.

For example, the connection may comprise one or more shearable projections.

The housing support is preferably pivotally mounted on a further support, the further support being configured for attachment to a vehicle, and the steering column assembly further comprising means for pivoting the housing support with respect to the further support.

Preferably, a second motor is provided for pivoting the housing support with respect to the further support.

In one embodiment, the further support is connected to a gear member driven by the second motor.

The gear member may comprise a worm gear engageable with a worm screw driven by the second motor.

The worm gear is conveniently a sector gear.

The steering column may further comprise a means for limiting the rotational travel of the steering wheel, the said means being connected to the second end of the shaft.

By way of example only, a specific embodiment of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view from the rear which is the steering wheel end of the column, one side and above of an embodiment of a steer-by-wire hand wheel actuator in accordance with the present invention; Figure 2 is a perspective view from the rear, the other side and above of the actuator of Figure 1; Figure 3 is a plan view of the actuator of Figure 1; Figure 4 is a side view of the actuator of Figure 1; Figure 5 is a rear end view of the actuator of Figure 1; Figure 6 is a perspective view from the rear, one side and above of a reach adjustment and crash energy absorption mechanism which forms part of the actuator of Figure 1; Figure 7 is a perspective view from the rear, the other side and above of the reach adjustment and crash energy absorption mechanism of Figure 6; Figure 8 is a perspective view of a rake adjust mechanism which forms part of the actuator of Figure 1; and Figure 9 is a perspective view of a portion of the rake adjust mechanism of Figure 8.

Figure 10 is a perspective view from the rear, one side and below of the embodiment with the reach adjustment bracket removed for clarity.

Figure 11 is a perspective view of the flexible wire and its guide means and its further guide means.

A steer-by-wire hand wheel actuator 10 comprises a steering column 12 having an elongate housing 14 in which a steering shaft 16 is rotatably mounted and projects from a first end. In use, the first end of the shaft 16 is connected to a vehicle steering wheel which can be used by a driver to control the steering of the vehicle when driven in a "manual" mode. In response to the angular displacement of the steering wheel and of the shaft 16, the steer-bywire actuator 10 generates a signal which is used to control the orientation of the steering wheels of the vehicle. The actuator 10 is also provided with an electric motor arrangement shown generally at 18 whose output is connected to the shaft 16 via gearing in order to provide a sensation of road feel to the driver.

As will be explained in more detail, the steering column 12 is displaceable in the fore and aft direction, parallel to the rotational axis of the shaft 16, by actuation of a reach adjust motor 20. The steering column is constrained to move in that direction by means of three front guide rollers 22 and three rear guide rollers 24 rotatably mounted in a reach adjustment bracket 26 which act on three longitudinally extending reach guide rails 28 on the outer surface of the housing 14. The reach adjustment bracket 26 itself is pivotally mounted at pivot bolts 30, 31 to a static mounting bracket 32 which is anchored to the vehicle at three anchor points 34. As will also be explained, the angular orientation of the reach adjustment bracket with respect to the axis of the pivot bolts 30, 31 can be adjusted by actuation of a rake adjust motor 36 in order to adjust the inclination (or "rake") of the steering column 12.

Figures 6 and 7 illustrate the construction and operation of the reach adjust mechanism 40 and correspond to Figures 2 and 1 respectively with the steering column 12, the reach adjustment bracket 26, the static mounting bracket 32 and the rake adjust motor 36 omitted, for clarity. The reach adjust mechanism 40 is essentially a Cardan gear assembly 42 which is actuated by the reach adjust motor 20 and whose output is connected to the steering column 12.

The Cardan gear assembly 42 comprises a worm gear wheel 44 which is rotatably mounted with respect to the reach adjustment bracket 26 on a stub axle 46 which is itself mounted in a bracket 48 secured to the reach adjustment bracket 26 (see Figure 1) by two securing bolts 50. The upper periphery of the worm gear wheel 44 is engaged with a worm screw 52 which is rotatable by means of a flexible drive shaft 54 connected to the output of the reach adjust motor 20, whereby the worm gear wheel 44 can be rotated in both directions by controlling the direction of output of the reach adjustment motor 20.

A spur gear 56 is fixedly mounted to the inner face of the worm gear wheel 44, coaxially with the worm gear wheel 44, by means of two securing bolts 58 and forms one component of a Cardan gear mechanism. A gear carrier in the form of two identical triangular crank plates 60, 61 are rotatable is pivotally mounted on stub axle 46. An idler spur gear 62 is rotatably mounted between the plates 60, 61 and meshes with the fixed spur gear 56 and with a further spur gear 64 which is also rotatably mounted between the crank plates 60, 61. A further crank arm 66 is rotatably mounted at one end to the axle of the further spur gear 64 and the opposite end of the further crank arm 66 is pivotally connected to an arm anchor 68 which is constrained to move in a direction parallel to the movement axis of the steering column 12 as it is ultimately connected to it. The diameter of the spur gear 56 is twice the diameter of the idler spur gear 62 and the further spur gear 64, and they together form a Cardan gear mechanism, whereby rotation of the spur gear 56, by actuation of the reach adjust motor 20, causing rotation of the worm gear wheel 44, results in displacement of the arm anchor 68, which is connected to the steering column 12. Therefore, by actuation of the reach adjust motor 20, the longitudinal position of the steering column can be adjusted.

The arm anchor 68 is secured to the housing 14 of the steering column 12 by means of two location pegs 70 which are received in complementarily-shaped recesses (not shown) in the housing 14, and which are designed to shear when subjected to a predetermined load corresponding to a vehicle crash.

It will also be noted that a flexible crash energy absorption wire 74 is provided. A first cranked end 76 of the wire is received into a complementarily-shaped hole provided in the housing 14 of the steering column 12. The wire then passes around a semicircular guide portion 78 located between the further crank arm 66 and the arm anchor 68, then passes round first and second crash energy wire anvils 80, 82 attached to the housing 14 of the steering column and having their axes arranged parallel to, and perpendicular to, respectively the rotational axis of the worm gear wheel 44.

In the event of a crash, the location pegs 70 of the arm anchor shear off, as mentioned previously, and the arm anchor 68 therefore remains static. However, since one end of the crash energy wire 74 is secured to the steering column 12, movement of the steering column causes the crash wire to be pulled through the semi-circular guide 78 which is attached to the arm anchor 68 and the two anvils 80, 82 thereby absorbing some of the energy of the crash.

As mentioned previously, the reach adjustment bracket 26 is pivotally mounted at pivot bolt 30, 31 to a static mounting bracket 32 which is anchored to the vehicle at three anchor points 34, whereby the rake of the steering column 12 can be adjusted by actuation of a rake adjust motor 36. The rake adjust mechanism is shown in more detail in Figures 8 and 9 and comprises a sector worm gear 88 connected to a mounting bracket 90 which is in turn secured to the reach adjustment bracket 26. The sector worm gear 88 meshes with a worm screw 92 at one end of a shaft 94. The other end of the connecting shaft 94 carries a further worm gear spur 96 which engages with a further worm screw 98 connected to the output of the rake adjustment motor 36.

Therefore, by actuation of the rake adjustment motor 36, the inclination of the reach adjustment bracket 26 with respect to the static mounting bracket 32 can be adjusted, in order to adjust the inclination or "rake" of the steering column 12.

The invention is not restricted to the details of the foregoing embodiment.

Claims

CLAIMS1. A steering column assembly for a vehicle, comprising an elongate housing, a shaft rotatably mounted within the housing and being configured for attachment of a steering wheel at one end, a housing support to which the housing is releasably mounted, the housing being constrained by the housing support to be displaceable along an adjustment axis parallel to the longitudinal axis of the housing, and displacement means for displacing the housing along the adjustment axis, the displacement means comprising a motor having a rotary output and linkage means driven by the motor output and connected to the housing, which displaces the housing along an axis parallel to the adjustment axis in response to operation of the motor.
2. A steering column assembly as claimed in claim 1, wherein the linkage means converts the rotary output of the motor into a linear motion.
3. A steering column assembly as claimed in claim 1 or claim 2, wherein the linkage means comprises a crank mechanism.
4. A steering column assembly as claimed in any of the preceding claims, comprising a first gear driven by the output of the motor and wherein the linkage means is engaged with the first gear.
5. A steering column assembly as claimed in claim 4, wherein the linkage means comprises a Cardan gear mechanism.
6. A steering column assembly as claimed in claim 5, comprising a carrier pivotally mounted coaxially with the first gear, a second, idler gear rotatably mounted on the carrier and engaged with the first gear, a third gear rotatably mounted on the carrier and engaged with the second, idler gear and a crank arm mounted to rotate with the third gear and being pivotally connected to the elongate housing.
7. A steering column assembly as claimed in claim 6, wherein the crank arm is pivotally connected to an intermediate member which is connected to the housing.
8. A steering column assembly as claimed in claim 6 or claim 7, wherein the motor drives a 5 worm screw engaged with a worm gear which is rotatably mounted on a pivot which is fixed with respect to the housing support, the first gear being mounted on the worm gear.
9. A steering column assembly as claimed in any of claims 6 to 8, wherein the first gear is mounted coaxially with the worm gear and constrained to rotate with it.
10. A steering column assembly as claimed in any of the preceding claims, further comprising means for absorbing energy in the event of an impact of sufficient magnitude to break the connection between the linkage and the housing.
11. A steering column assembly as claimed in claim 10, wherein the means for absorbing an impact comprises a flexible wire secured to the housing and being configured to have a tension applied to it in the event of an impact sufficient to break the connection between the linkage and the housing.
12. A steering column assembly as claimed in claim 11, wherein the flexible wire passes partially around a guide means fixed with respect to the housing support.
13. A steering column assembly as claimed in claim 12, wherein the flexible wire is guided in an arcuate path around the guide means.
14. A steering column assembly as claimed in any of claims 11 to 13, wherein the flexible wire passes partially around one or more guide means fixed with respect to the housing.
15. A steering column assembly as claimed in claim 14, wherein the flexible wire is guided in an arcuate path around the guide means fixed with respect to the housing.
16. A steering column assembly as claimed in any of the preceding claims, wherein the connection between the linkage and the housing is configured to be shearable.
17. A steering column assembly as claimed in claim 16, wherein the connection between the linkage and the housing comprises one or more shearable projections.
18. A steering column assembly as claimed in any of the preceding claims, wherein the housing support is pivotally mounted on a further support, the further support being configured for attachment to a vehicle, and means for pivoting the housing support with respect to the further support.
19. A steering column assembly as claimed in claim 18, comprising a second motor for pivoting the housing support with respect to the further support.
20. A steering column assembly as claimed in claim 18 or claim 19, wherein the further support is connected to a gear member driven by the second motor.
21. A steering column assembly as claimed in claim 20, wherein the gear member comprises worm gear engageable with a worm screw driven by the second motor.
22. A steering column assembly as claimed in claim 21, wherein the worm gear is a sector gear.
23. A steering column assembly as claimed in any of the preceding claims, further comprising a means for limiting the rotational travel of the steering wheel, the said means being connected to the second end of the shaft.G:\440-445\zo9\445701\GBWastercloc