AXIALLY ADJUSTABLE STEERING COLUMN ASSEMBLY AND AXIAL POSITION DETECTION SYSTEM FOR A STEERING COLUMN ASSEMBLY

Abstract

Axially adjustable steering column assembly (44) comprising: an upper shell (48); a lower shell (50), the upper shell (48) being received in the lower shell (50) and being telescopically adjustable therein, the lower shell (50) defining a pair of slots (80) extending in an axial direction of the lower shell (50); a column mounting bracket (70), wherein the lower shell (50) slides and rotates relative to the column mounting bracket (70); a pair of bushings (84) disposed in the pair of slots (80); a rack (90) operatively coupled to one of the pair of bushings (80), the rack (90) being rotatable in accordance with the lower shell (50); and a sensor in operative contact with the rack (90) to detect the axial position of the axially adjustable steering column assembly (44).

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an axially adjustable steering column assembly and an axial position sensing system for a steering column assembly. The embodiments described herein relate to vehicle steering systems, and more particularly to a sliding, power-adjustable steering column with a rack for an absolute sensor.

[0002] US 2018 / 0 086 378 A1 discloses a steering column assembly with an upper casing, a lower casing, and a rack. Documents DE 10 2021 109 357 A1 and US 2020 / 0 156 692 A1 describe related steering column assemblies. BACKGROUND

[0003] A vehicle, such as a passenger car, truck, sport utility vehicle, crossover, minivan, watercraft, aircraft, off-road vehicle, recreational vehicle, or other suitable vehicle, includes various steering system schemes, such as steer-by-wire and driver interface steering. These steering system schemes typically include a steering column for translating a steering input into an output, which interacts with a steering linkage to ultimately cause the vehicle's wheels (or other elements) to turn the vehicle.

[0004] Some steering columns are axially adjustable between positions. In the past, one function of axially adjustable steering columns was to provide flexibility regarding the location of the handwheel, enabling a more comfortable driving position for drivers of different heights. However, there are now opportunities for a significantly greater degree of telescoping travel, which can also be referred to as stowage travel (i.e. when the handwheel is not required). For example, the handwheel could be repositioned well away from the driver to allow them to do things other than operate the vehicle, such as work on a laptop while the vehicle is parked. Other examples include vehicles with autonomous driving capability, where the handwheel can be stowed away when in an autonomous driving mode.

[0005] As the automotive industry increasingly moves to steer-by-wire technologies, more emphasis is being placed on redundancies in position sensing to ensure the position of comfort components in both functional and stowed modes. Therefore, some OEMs are requiring the use of direct, absolute sensing of the steering column telescoping position, as opposed to the previous reliance on encoders and Hall pulse analysis. Absolute position sensing requires the sensor to be able to physically read the position of the steering column's telescoping or telescopic position. With an externally sliding and internally telescoping column, the column assembly has two different interfaces that can move simultaneously during a stow phase. The first movement is a movement of the upper shell with respect to the lower shell (i.e.(typical of conventional motorized telescopic columns), but this movement is also paired with a second displacement interface between the lower shroud and a column mounting bracket. These two movements combined result in a high stowage speed and a large stowage displacement within the vehicle, driving the handwheel toward and into the dashboard.

[0006] Standard telescoping sensing systems with an absolute position sensor include a rack driven by the movement of the upper shroud. This rack rides alongside the absolute position sensor, which in turn drives toothed wheels on the sensor. The rotational movement of the toothed wheels is then used to determine the position of the upper shroud in its telescoping or telescopic movement. This externally sliding and internally telescoping or telescoping column presents a challenge when using an absolute position sensor to detect the displacement of the lower shroud relative to the column mounting bracket. The reason for this is that the stowing movement only occurs in one plane (i.e., forward / backward in the vehicle), whereas the lower shroud can also articulate vertically during a tilt function.This creates a unique situation that requires special considerations regarding how to implement a rack to interface with the absolute position sensor. The rack must have a fixed position relative to the column mounting bracket, but also be able to articulate with the tilting movements of the lower shell.

[0007] It is an object of the invention to provide an improved axially adjustable steering column assembly and an improved axial position sensing system for a steering column assembly. SUMMARY

[0008] The aforementioned object is achieved by an axially adjustable steering column assembly according to claim 1 and an axial position detection system for a steering column assembly according to claim 10. Advantageous developments of the invention are specified in the subclaims.

[0009] According to one aspect of the disclosure, an axially adjustable steering column assembly includes an upper shell. The steering column assembly also includes a lower shell, the upper shell being received within and telescopically adjustable within the lower shell, the lower shell defining a pair of slots extending in an axial direction of the lower shell. The steering column assembly further includes a column mounting bracket, the lower shell translating and rotating relative to the column mounting bracket. The steering column assembly further includes a pair of bushings disposed in the pair of slots. The steering column assembly also includes a rack operatively coupled to one of the pair of bushings, the rack being correspondingly rotatable with the lower shell.The steering column assembly further includes a sensor in operative contact with the rack for sensing the axial position of the axially adjustable steering column assembly.

[0010] According to another aspect of the disclosure, an axial position sensing system for a steering column assembly includes a column mounting bracket. The axial position sensing system also includes a column structure operatively coupled to the column mounting bracket, the column structure being movable in an axial direction relative to the column mounting bracket and rotatable relative to the column mounting bracket, the column structure defining a pair of slots extending in an axial direction of the column structure. The axial position sensing system further includes a pair of splined bushings disposed within the pair of slots, the splined bushings having at least one tapered surface in contact with one or more walls defining the pair of slots. The axial position sensing system also includes a rack formed integrally with one of the pair of splined bushings.The axial position sensing system also includes a sensor in functional contact with the rack to detect the axial position of the column structure.

[0011] These and other advantages and features will become clearer from the following description taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The subject matter regarded as the invention is particularly pointed out and particularly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 schematically illustrates a vehicle steering system; Fig. Figure 2 is a plan view of a steering column assembly for the vehicle steering system in a first tilt position; Fig. 3 is a plan view of the steering column assembly in a second tilt position; Fig. Figure 4 is a plan view of the steering column assembly in an axially stowed position; Fig. 5 is a perspective view of the steering column assembly illustrating a rack; and Fig. Figure 6 is a perspective view of the steering column assembly illustrating the rack in contact with an absolute position sensor. DETAILED DESCRIPTION

[0013] The following discussion relates to various embodiments of the disclosure.

[0014] A vehicle, such as a passenger car, truck, sport utility vehicle, crossover, mini-van, watercraft, aircraft, off-road vehicle, recreational vehicle, or other suitable vehicle, includes, as described, various steering system schemes, such as steer-by-wire and driver interface steering. These steering system schemes typically include a steering column for translating a steering input into an output, which interacts with a steering linkage to ultimately cause the vehicle wheels (or other elements) to turn the vehicle. Some steering columns are axially adjustable between positions. In the past, one function of axially adjustable steering columns was to provide flexibility regarding the location of the handwheel and to enable a more comfortable driving position for different sized drivers. However, there are now options for significantly greater axial travel, which may also be referred to as stow travel (i.e.when the handwheel is not needed). For example, the handwheel could be repositioned significantly away from the driver to allow them to do things other than operate the vehicle, such as work on a laptop while the vehicle is parked. Other examples include vehicles with autonomous driving features, where the handwheel can be stowed away in autonomous driving mode.

[0015] Referring now to the drawings in which the various embodiments are shown and described, the figures illustrate embodiments of a steering column assembly that is axially adjustable and has improved packaging and other operating advantages. Axial adjustability results from relative movement between two or more steering column sections (e.g., sleeves, yokes, rails, and / or the like) that allow axial movement therebetween, in combination with relative movement between multiple steering shaft sections that allow axial movement therebetween. Axial movement refers to the movement resulting from relative pushing, sliding, or translating movement between components.

[0016] First, with reference to Fig. 1, a vehicle 20 is generally illustrated in accordance with the principles of the present disclosure. The vehicle 20 may include any suitable vehicle, such as a car, a truck, a sport utility vehicle, a minivan, a crossover, another passenger vehicle, a suitable commercial vehicle, or any other suitable vehicle. While the vehicle 20 may be a wheeled passenger vehicle intended for over-the-road travel, the principles of the present disclosure may also apply to other vehicles, such as aircraft, tractors, boats, or other vehicles. The vehicle 20 may include a propulsion system 30, such as an ignition system, an electronic system, or combinations thereof.

[0017] The vehicle 20 also includes a steering system 40. The steering system 40 may be configured as a driver interface steering system, an autonomous driving system, or a system enabling both a driver interface and autonomous steering. The steering system 40 may include an input device 42, such as a steering wheel, wherein a driver can mechanically provide steering input by turning the steering wheel. A steering column assembly 44 includes a steering column 45 extending along an axis from the input device 42 to an output assembly 46. The output assembly 46 may include a pinion shaft assembly, an I-shaft, a universal joint, steer-by-wire components, or any feature conventionally disposed opposite the input device 42.

[0018] The steering column 45 may include at least two axially adjustable sections, e.g., an upper shell 48 and a lower shell 50, which are axially adjustable relative to each other. The at least two axially adjustable sections may further include at least a third section 49, which in some embodiments is disposed between the upper shell 48 and the lower shell 50. It should be noted that other structural features of the steering column 45 may be part of the upper shell 48 and the lower shell 50, such as brackets, rails, other devices, or combinations thereof.

[0019] The steering column 45 is movable through a range of positions from a fully extended to a fully retracted position. In the fully extended position, the upper shell 48 and the lower shell 50 are moved axially such that the input device 42 is located near an operator. In the retracted position, the upper shell 48 and the lower shell 50 are moved axially such that the input device 42 is farther from an operator than in the extended position. In some embodiments, the retracted position may correspond to the stowing of the input device 42. For example, it may be advantageous to arrange the input device 42 in a stowed position during autonomous driving. In operation, the axial movement of the upper shell 48 and the lower shell 50 may be effected by manual movement by an operator or electromechanically by a telescoping actuator.This axial movement provides adjustment between the extended position, the retracted position and all intermediate positions.

[0020] A steering gear assembly 54 may be connected to the output assembly 46 via a steering gear input shaft 56. The steering gear assembly 54 may be configured as a rack and pinion, a recirculating ball steering assembly, or other types of steering gears associated with autonomous and driver interface steering systems. The steering gear assembly 54 may then be connected to a drive axle 58 via an output shaft 60. The output shaft 60 may include a pitman arm and a sector gear and / or various conventional components. The output shaft 60 is operatively connected to the steering gear assembly 54 such that rotation of the steering gear input shaft 56 causes a reactive movement of the output shaft 60, causing the drive axle to turn the wheels 62.It should be noted that the steering components described here may be part of a steer-by-wire system or a system that includes a direct mechanical linkage across the span of the components.

[0021] Now with reference to the Fig. 2 and Fig. 3, the steering column assembly 44 is shown in more detail. The upper shell 48 is shown projecting from the lower shell 50. The lower shell 50 is operatively coupled to and axially slidable relative to a column mounting bracket 70. The column mounting bracket 70 is fixed relative to a vehicle structure to secure the steering column assembly 44 to the vehicle 20. The upper shell 48 is axially adjustable relative to the lower shell 50 over a first range of axial positions, which may be referred to as a "comfort range." The comfort range is a range of axial positions useful for manual driving during operation of the vehicle for differently sized operators. The axial movement of the upper shell 48 relative to the lower shell 50 is accomplished in a telescoping or telescoping manner by movement of the upper shell 48 within the lower shell 50. The comfort range includes the entire comfort range and, if applicable,a portion of the stowage range. The lower shroud 50 is axially adjustable relative to the column mounting bracket 70 over a second range of axial positions, which may be referred to as the "stowage range." The stowage range is a range of axial positions in which the entire steering column assembly 44 is farther from the operator compared to the comfort range. In some embodiments, the fully retracted position is a stowed position that may result in the steering input device (e.g., the steering wheel) being flush with an instrument panel, firewall, or other vehicle structure. The axial movement of the lower shroud 50 relative to the column mounting bracket 70 is accomplished in a translational manner through the cooperative movement of the upper and lower shrouds adjacent the column mounting bracket 70. Fig. 4 illustrates the axial adjustability of the steering column assembly 44 with the first portion 48 fully retracted into the second portion 50 and the second portion 50 fully retracted relative to the column mounting bracket 70.

[0022] The steering column assembly 44 includes a first actuator 72, which may be referred to as a comfort actuator. The first actuator 72 is operatively coupled to the upper shell 48 to control the telescoping movement of the upper shell 48 relative to the lower shell 50 over the first range of axial positions. In the illustrated embodiment, the first actuator 72 is attached to a specific portion of the steering column assembly 44, however, other attachment locations are also contemplated.

[0023] The steering column assembly 44 also includes a second actuator 74, which may be referred to as a stowage actuator. The second actuator 74 is operatively coupled to the lower shroud 50 to control the translational movement of the lower shroud 50 relative to the column mounting bracket 70 over the second range of axial positions. In the illustrated embodiment, the second actuator 74 is attached to a specific portion of the steering column assembly 44, but other attachment locations are also contemplated.

[0024] Both the first and second actuators 72, 74 are located near a forward position of the steering column assembly 44 to enable axial movement during a stowage operation. The two actuators 72, 74 are responsible for the entire stowage movement of the column, however, only the first actuator 72 operates within the first range of axial adjustment positions during comfort adjustment.

[0025] With continued reference to the Fig. 2 and Fig. 3, in addition to the axial adjustability of the steering column assembly 44, the steering column assembly 44 is adjustable in a tilt direction, which allows angular articulation of the entire steering column assembly 44 about a rotational axis about which the lower shell 50 rotates. This effectively allows upward or downward movement of the steering input device 42 depending on the user's preference. A tilt actuator assembly 76 is attached to the lower shell 50. As shown, the lower shell 50, and thus the steering column assembly 44, moves between various tilt positions, including a first tilt position ( Fig. 2) and a lowered, second tilt position ( Fig. 3). It should be understood that different tilt adjustment ranges are used for different applications of the steering column.

[0026] As in Fig. 5, the embodiments disclosed herein include tapered rail slots 80 defined in the lower shell 50 and forming a pair of tracks. Specifically, a first track is defined on one side of the lower shell 50 by one of the slots and a second track is defined on a second side of the lower shell 50. At least one sliding key bushing 84 is disposed in each of the tapered rail slots 80. The sliding key bushings 84 have a tapered shape that substantially conforms to the angled orientation of the tapered rail slots 80. The tapered rail slots 80 in each component serve as a receiving interface for taking up slack from the sliding key bushings 84 and provide guidance for the translation of the lower shell 50 relative to the column mounting bracket 70 during the stowage operation.

[0027] A rack 90 is coupled to one or more splined bushings 84 and engages the absolute position sensor 92. The rack 90 includes a surface with a plurality of teeth 91 formed along at least a portion of the length of the surface. Each rack 90 is coupled to one or more of the splined bushings 84 or is integrally formed with the splined bushings 84 to form a single, unitary component. The rack 90 and splined bushings 84 are operatively coupled to the column mounting bracket 70. Therefore, the rack 90 and splined bushings 84 remain stationary during translation of the lower shell relative to the lower shell 50. However, the rack 90 and splined bushings 84 are pivotally connected to the column mounting bracket 70.Thus, the wedge bushings 84 remain aligned with their respective paths of the lower shell 50 during the tilt articulation movement of the lower shell 50 to enable guided displacement of the lower shell 50.

[0028] For the displacement function of the stowage movement, an absolute position sensor 92 is attached to the lower casing 50 ( Fig. 6). As the lower shell 50 undergoes its tilt articulation movements, the splined bushings 84 follow the tilt movements and maintain the rack 90 in alignment with an absolute position sensor 92 fixed to the lower shell 50. However, when the steering column assembly 44 moves into the stow function, the splined bushings 84—which are positionally fixed to the lower shell 50—remain in place with the column mounting bracket 70 as the lower shell 50 translates relative to the column mounting bracket 70 and the rack 90.

[0029] With reference to Fig.6, the plurality of teeth 91 of the rack 90 slide along the teeth 93 of the absolute position sensor 92 as the lower shell 50 slides, which ensures accurate detection of the axial position of the steering column assembly 44 without being distorted by different inclination positions of the lower shell 50.

[0030] Additionally, although various embodiments of the invention have been described, it should be understood that aspects of the invention may include only some of the described embodiments. Furthermore, any feature, element, component, or advantage of any embodiment may be used in conjunction with any of the other embodiments.

Claims

[1] Axially adjustable steering column assembly (44) comprising: an upper shell (48); a lower shell (50), the upper shell (48) being received in the lower shell (50) and being telescopically adjustable therein, the lower shell (50) defining a pair of slots (80) extending in an axial direction of the lower shell (50); a column mounting bracket (70), wherein the lower shell (50) slides and rotates relative to the column mounting bracket (70); a pair of bushings (84) disposed in the pair of slots (80); a rack (90) operatively coupled to one of the pair of bushings (80), the rack (90) being rotatable in accordance with the lower shell (50); and a sensor in operative contact with the rack (90) to detect the axial position of the axially adjustable steering column assembly (44). [2] The axially adjustable steering column assembly (44) of claim 1, wherein each of the pair of bushings (84) has at least one chamfered surface in contact with one or more walls defining the pair of slots (80). [3] The axially adjustable steering column assembly (44) of claim 2, wherein the one or more walls of the pair of slots (80) are chamfered to correspond to the at least one chamfered surface of the pair of bushings (84). [4] An axially adjustable steering column assembly (44) as claimed in claim 1, wherein the rack (90) is formed integrally with one of the pair of bushings (84). [5] An axially adjustable steering column assembly (44) as claimed in claim 4, wherein the rack (90) is operatively coupled to the column mounting bracket (70) and is pivotable relative to the column mounting bracket (70). [6] The axially adjustable steering column assembly (44) of claim 1, wherein the rack (90) has a plurality of rack teeth (91) and the sensor comprises an absolute position sensor (92) having a toothed wheel in contact with the plurality of rack teeth (91). [7] An axially adjustable steering column assembly (44) as claimed in claim 6, wherein the toothed wheel is one of a plurality of toothed wheels of the absolute position sensor (92). [8] An axially adjustable steering column assembly (44) according to claim 1, wherein the rack (90) does not move relative to the column mounting bracket (70). [9] An axially adjustable steering column assembly (44) according to claim 1, further comprising: a first actuator (72) operatively coupled to the upper shell (48) to control axial displacement of the upper shell (48) relative to the lower shell (50); a second actuator (74) operatively coupled to the lower shell (50) to control the axial displacement of the lower shell (50) relative to the column mounting bracket (70); and a tilt actuator (76) operatively coupled to the lower shell (50) to control the tilt adjustment of the lower shell (50). [10] An axial position sensing system for a steering column assembly (44), comprising: a column mounting bracket (70); a column structure operatively coupled to the column mounting bracket (70), the column structure being movable in an axial direction relative to the column mounting bracket (70) and rotatable relative to the column mounting bracket (70), the column structure defining a pair of slots (80) extending in an axial direction of the column structure; a pair of wedge bushings (84) disposed in the pair of slots (80), the wedge bushings (84) having at least one beveled surface in contact with one or more walls defining the pair of slots (80); a rack (90) formed integrally with one of the pair of splined bushings (84); and a sensor in functional contact with the rack (90) to detect the axial position of the column structure. [11] The axial position sensing system of claim 10, wherein the one or more walls of the pair of slots (80) are chamfered to correspond to the at least one chamfered surface of the pair of splined bushings (84). [12] The axial position sensing system of claim 10, wherein the rack (90) is operatively coupled to the column mounting bracket (70) and is pivotable relative to the column mounting bracket (70). [13] The axial position sensing system of claim 10, wherein the rack (90) has a plurality of rack teeth (91) and the sensor comprises an absolute position sensor (92) having a toothed wheel in contact with the plurality of rack teeth (91). [14] The axial position sensing system of claim 13, wherein the toothed wheel is one of a plurality of toothed wheels of the absolute position sensor (92). [15] The axial position detection system of claim 10, wherein the rack (90) does not move relative to the column mounting bracket (70).

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