Patent ID: 12233973

DETAILED DESCRIPTION

As shown inFIG.4, a handwheel actuator10comprises a three-part telescopic shroud. The function of the shroud is to support a steering shaft11in a desired position relative to a vehicle body (not shown). By providing three shroud portions, the range of length adjustment of the shroud is large relative to its fully retracted position making it an excellent choice for a vehicle where the wheel may be presented to a user for use in a manual driving mode or retracted into a dashboard to free up space in a fully autonomous driving mode. Within these extremes the shroud also permits a choice or reach positions for the steering wheel to suit drivers of different shapes and sizes.

The three-part telescopic shroud comprises three tubular members, each an extrusion having a generally square outer cross section through its long axis. The three shroud portions having increasing sizes moving from the first one nearest the driver and the third one furthest from the driver. A first portion12supports the steering shaft11that in turn may be fixed to a steering wheel or yoke. This is telescopically received in a second portion13which is itself telescopically received in a third portion14. The third portion includes a fixing hole15that allows the shroud to be secured to a fixed part of the vehicle such as a cross member extending behind a vehicle dashboard by a pivot pin. The pivot pin allows for the whole shroud to rotate to provide rake adjustment of the steering wheel or yoke.

The first tubular member12is a sliding fit within an inner bore of the second tubular member13, the two being constrained to move telescopically relative to one another for adjustment of the reach position of the steering column assembly. The second tubular member13is in turn a sliding fit within a bore of the third tubular member14. A set of interengaged grooves and rails on the shroud portions facilitate accurate linear movement of the shroud portions during adjustment. Due to the size of the tubular portions12,13,14, and the range of reach adjustment, small deviations from the ideal sizes of each portion due to manufacturing tolerances can introduce unwanted free play and in turn cause the telescopic motion to become non-linear.

The relative axial position of the three shroud portions12,13,14is set by a linear actuator. The linear actuator comprises three main parts: a motor16, a reduction gearbox17a threaded rod18. The motor16is connected to the threaded rod18through the gearbox17so that operation of the motor causes the rod to rotate around its long axis. As will be explained, the motor16is secured to the intermediate, second, shroud portion13and each end of the rod18is secured to a support bracket assembly19,20that is secured to a respective one of the first and third shroud portions. Rotation of the rod18in one direction drives these support brackets19,20towards each other and rotation of the rod18in the other direction drives these support brackets19,20away from each other. The motor therefore controls the overall length of the telescopic shroud.

As shown inFIG.6, in this example the steering shaft11is connected to a pair of motors21,22through a gearbox assembly. The motors provide force feedback to the driver by acting upon the steering shaft in response to a demand signal.

FIGS.5A-5Cshow a first exemplary arrangements of a support bracket assembly as shown in the HWA ofFIG.4. The two support bracket assemblies19,20may be the same so only one is described here. An important feature of each of the support brackets19,20is to provide a degree of lost motion between the rod18of the linear actuator and the associated tubular shroud portion12,14to accommodate misalignment of the shroud portions during use of the steering column assembly that would otherwise apply a bending moment to the linear actuator.

The applicant has appreciated that it is important that the linear actuator does not present a significant variation in resistance of the whole column to a collapse. If the rod is bent then such a variation is very likely as the rod may bind within a simple support bracket assembly that cannot accommodate lost motion.

A first exemplary arrangement of a support bracket assembly20is shown inFIG.5and comprises a rigid mounting part23that is fixed to the associated shroud portion and a locating part24that is fixed to the mounting part23and that engages the elongate rod18.

The rigid mounting part23comprises a base plate that is secured to the associated shroud part through a bolt24that extends through an elongate slot25in the base plate. The slot allows the rigid mounting23part to move vertically relative to the shroud. The base plate sits upon a complimentary vertical receiving surface of the side of the associated shroud portion such that the base plate may slide relative to the receiving surface. This allows any unwanted vertical offset of the shrouds due to manufacturing tolerances to be accommodated without placing a bending load on the rod of the linear actuator.

Extending from the base plate23is a cylindrical cage26which forms a part of the mounting part. As shown the base plate and cage26form a single unitary component. The cage26has a cylindrical inner bore27and two opposed cut outs28,29in the side wall of the cylinder that the elongate rod18passes through. The cage26receives a connector block in the form of a spherical ball30having a threaded through bore31that is threaded onto the rod18so that the ball30is held captive in the cage26. The diameter of the ball30is complimentary to the inner diameter of the bore27of the cylindrical cage26so that the ball30can be freely slid into the cage.

A pin32is located at one end in the base plate and at the other in a complimentary bore33in the ball. This pin prevents rotation of the ball30around the axis of the threaded rod18but permits the ball30to translate horizontally within the cage26. The range of horizontal motion is limited by the rod striking the cage so that the ball cannot slide out of the cage. The bore in the ball is elongated to allow some rotation of the ball around a vertical axis before the ball and pin bind with each other.

The support bracket assembly20therefore permits lost motion along the horizontal and vertical directions so that the rod will not become bent, and also rotation around the vertical and horizontal axes. The cage may restrain the connector block such that it cannot rotate around the axis of rotation of the rod.

FIGS.6and7show how the shroud portions can be placed in different positions by operation of the motor of the linear actuator.FIGS.8A and8Bshow how the support bracket assemblies20can move to provide some lost motion as the rod18deviates for an ideal linear motion due to manufacturing tolerances in the shroud portions.

The arrangement of components allows movement in abovementioned directions, that may be big enough to compensate imperfections resulting from tolerance stack-up. Thanks to the presented disclosure, there is no over constraint, so the reach actuator shaft and transmission do not bend, even if the actuator axis is in offset to the column centreline.

FIGS.9A-9Cshow a second exemplary support bracket assembly40which again has the rigid mounting part in the form of a base plate41, a cage42, and a ball shaped connector block43located in the cage42. The cage42has two opposed openings44through which the elongate rod18passes and the ball has a through bore45with an internal thread that allows it to be threaded onto the rod. The rod therefore prevents the ball coming out of the cage.

The cage42is connected to the base portion through two serially connected parallelogram linkages that permits vertical movement and horizontal movement of the cage relative to the base portion. This allows the base plate to be secured rigidly to the shroud portion as it no longer needs to slide vertically. The linkages are formed from six link arms46-51and six interconnecting pivot pins52-57.

One of the linkages is defined by two upper links46,47and two lower links48,49, one end of each upper link fixed to the same end of the other by a pivot pin52, and the other end of each upper link fixed to the cage42by a second pivot pin53. The two lower links48,49are fixed in the same way by third and fourth pivot pins54,55.

The two pins52,55nearest the base plate41are not connected to the base plate directly but pass through openings in an end of a respective fifth link50and sixth link51. These two links50,51are connected at their opposite ends to the base plate41through two further pivot pins56,57. Together these additional two links and pins form a second linkage.

To understand the lost motion provided by the two serial linkages consider first that the two pins52,55that connect the first linkage to the second linkage are fixed and cannot move but the two pins53,54at the other ends of the first linkage are free to move restrained by the pivoting of the links around the fixed pins. The cage interconnects both free ends of the links that are furthest from the base plate. Thus, the cage can move up and down constrained by the first linkage.

If we next allow the pins52,55that connect the first linkage to the second linkage to move in space constrained by the first and second linkages, it will be appreciated that the cage42can also move horizontally relative to the base plate as the orientation of all eight linkages changes.

Of course, the skilled person will appreciate that other linkages are possible within the scope of the present disclosure to provide the required degree of horizontal lost motion and vertical lost motion, or provide only for vertical or only horizontal lost motion.

The ball shaped connector block43can rotate around vertical and horizontal axes within the cage42as well as move through a limited range of horizontal motion orthogonal to the axis of the threaded rod18by a pin58that is part of the cage that engages an oversized bore59in the ball.

In a third exemplary support bracket assembly60shown inFIGS.10A-10C, the support bracket assembly comprises a base plate61that can be rigidly fixed to a shroud portion through a pair of cut outs62. The base plate61has a pair of arms63,64that extend from a top and a bottom edge of the base plate61respectively horizontally away from the shroud portion. The free end of the two arms63,64support a cage65in the form of a cylindrical band. Within the band65is a connector block in the form of a ball66that has a through bore that is threaded onto the rod18of the linear actuator. The cage65also includes two pins67that engage elongate slots in the ball65from opposite sides and an annular elastomeric damper68that fills the space between the outer surface of the ball66and the inner wall of the band65.

The damper68controls movement of the ball66vertically and horizontally. The pins prevent rotation of the ball around the axis of the threaded rod by allow the ball to rotate around axes orthogonal to the rod. A small amount of horizontal movement is possible by making the pins67a loose fit in the slots in the ball66.

A fourth exemplary support bracket assembly70is shown inFIGS.11A-11D. The support bracket assembly70comprises a base plate71and a cylindrical cage72that extends from the base plate71. The axis of the cylindrical cage72is orthogonal to the axis of the threaded rod18of the linear actuator when the base plate is fixed to a shroud portion. Opposing sides of the cage72have openings73through with the rod18can pass and these are elongated horizontally to allow the rod18to move horizontally relative to the support bracket.

The cage72locates a cylindrical connector block73that has a threaded through bore74that engages the rod18. This connector block73has a smaller diameter than the inside of the cylindrical cage and comprises an inner solid cylindrical member74surrounded by a cylindrical metal sleeve75is in the annular space between the member74and the cage72. Between the sleeves75and the member74is a resilient annular spacer block76that is keyed to both the connector block and the sleeve75. To prevent rotation of the connector block73around the axis of the rod18the block73is retained at one end by a locating lug77formed into the base plate71and a locating lug78formed into an end cap79that is fixed to the end of the cage72furthest from the base plate.

As shown inFIGS.12A-12D, a fifth exemplary support bracket assembly80comprises a base plate81and four orthogonal walls82,83,84,85that extend away from the base81plate to define a cubic volume of space between the walls. Two of the walls83,84are vertical and have openings through which the elongate rod passes. The other two walls are horizontal and define a top wall and a bottom wall of the cubic volume of space.

Each of the vertical walls83,84supports a respective annular bearing86,87and these in turn surround the rod18, the bearings86,87also providing a support for a ball shaped connector block88. The walls and bearings together form a cage and the base plate a rigid mounting portion. The bearings86,87permit the ball to rotate around a vertical and a horizontal axis and can each slide relative to the vertical walls to provide for horizontal or vertical translation of the ball. A pin89located in a slot not shown in the base plate81connects the ball88to the base plate81to prevent the ball rotating around the axis of the threaded rod18.

As shown inFIGS.13A-13D, a sixth exemplary support bracket assembly90comprises a base plate91and four orthogonal walls92,93,94,95that extend away from the base plate to define a cubic volume of space between the walls. Two of the walls are vertical and have openings through which the elongate rod passes. The other two walls are horizontal and define a top wall and a bottom wall of the cubic volume of space.

Each of the vertical walls supports an annular bearing96,97that surrounds the rod18, the bearings providing a support for a cylindrical shaped connector block98. The walls and bearings together form a cage and the base plate91a rigid mounting portion. The bearings permit the cylinder to slide relative to the vertical walls to provide for horizontal or vertical translation of the cylinder. Rotational movement can be permitted by making the annular bearings from a resilient material, such as an elastomer. A pin99connects the connector to the base plate to prevent the ball rotating around the axis of the threaded rod.

This example is similar to that ofFIGS.12A-12D. As shown inFIGS.13A-13Dit differs in the use of a cylinder shape connector block rather than a ball shaped connector block. As such the connector block cannot rotate around the horizontal and vertical axes like the ball inFIGS.12A-12D, but the horizontal and vertical translation is still accommodated.