STEER-BY-WIRE-DREHWEGBEGRENZUNG

Abstract

A travel limiting assembly for a vehicle steer-by-wire steering system includes a shaft defining a spiral track extending from a first track end to a second track end. The travel limiting assembly also includes a nut extending radially from an inner radial surface to an outer radial surface, the nut extending circumferentially from a first circumferential end to a second circumferential end, the inner radial surface being disposed within the spiral track, the nut being rotatably fixed such that rotation of the shaft translates the nut axially along the spiral track, the first track end, the second track end, the first circumferential end, and the second circumferential end being positioned to limit axial movement of the nut and rotation of the shaft to a predetermined axial distance of the nut and a predetermined angle of rotation of the shaft.

Description

FIELD OF THE INVENTION

[0001] The disclosure relates generally to vehicle steering systems and, more particularly, to a steer-by-wire rotation limiter. BACKGROUND

[0002] With advances in vehicle technology, handwheel actuators and roadwheel actuators are increasingly being used to control a vehicle's path, replacing direct mechanical connections between the steering wheel and a vehicle's tires. While the vehicle is moving, the handwheel actuator and roadwheel actuator work together through electrical communication (e.g., wires, sensors, and a central processing unit) to directionally control the vehicle's travel. Specifically, the sensed movement of the respective handwheel and / or tires is electrically relayed to the respective handwheel actuator or roadwheel actuator to cause movement of the handwheel and / or tires. However, such advances in vehicle technology and their complexity present unique challenges.For example, a direct mechanical connection between the handwheel and the tires can limit rotation of the handwheel, which can prevent damage to components of the handwheel / steering column assembly or can simply be used to limit a range of travel of the handwheel / steering column.

[0003] A handwheel coupled to a handwheel actuator is subject to over-rotation because there is no mechanical connection / component to limit rotation. Components of the handwheel actuator, such as a clock spring, airbag coil, etc., are in turn subject to damage from over-rotation of the handwheel. SUMMARY

[0004] According to one aspect of the disclosure, a travel limiting assembly for a vehicle steer-by-wire steering system includes a shaft extending along an axis and rotatable about the axis, the shaft defining a spiral track extending from a first track end to a second track end.The travel limiting assembly also includes a nut extending radially from an inner radial surface to an outer radial surface, the nut extending circumferentially from a first circumferential end to a second circumferential end, the inner radial surface being disposed within the spiral track, the nut being rotatably fixed such that rotation of the shaft translates the nut axially along the spiral track, the first track end, the second track end, the first circumferential end, and the second circumferential end being positioned to limit axial movement of the nut and rotation of the shaft to a predetermined axial distance of the nut and a predetermined angle of rotation of the shaft, respectively, based on contact between the first circumferential end and the first track end and contact between the second circumferential end and the second track end.

[0005] According to another aspect of the disclosure, a steer-by-wire vehicle steering system includes a steering shaft configured to be rotated during steering maneuvers of a vehicle. The steering system also includes a handwheel actuator operatively coupled to the steering shaft. The steering system further includes a shaft operatively coupled to or integral with the steering shaft, the shaft limited to a predetermined angle of rotation by a travel limiting assembly. The travel limiting assembly includes a spiral track defined along an axial portion of the shaft, the spiral track extending from a first track end to a second track end.The travel limiting assembly also includes a nut extending radially from an inner radial surface to an outer radial surface, the nut extending circumferentially from a first circumferential end to a second circumferential end, the inner radial surface being disposed within the spiral track. The travel limiting assembly further includes a housing radially surrounding the nut, the outer radial surface of the nut including a radially extending tab disposed within an axially extending groove defined by the inner surface of the housing for rotatably retaining the nut.The nut is rotatably fixed such that rotation of the shaft translates the nut axially along the spiral track, wherein the first track end, the second track end, the first circumferential end, and the second circumferential end are positioned to limit the axial movement of the nut and the rotation of the shaft to a predetermined axial distance of the nut or a predetermined angle of rotation of the shaft, respectively, based on the contact between the first circumferential end and the first track end and the contact between the second circumferential end and the second track end.

[0006] According to another aspect of the disclosure, a travel limiting assembly for a steer-by-wire vehicle steering system includes a shaft extending along an axis and rotatable about the axis, the shaft defining a spiral track extending from a first track end to a second track end. The travel limiting assembly also includes a nut extending radially from an inner radial surface to an outer radial surface, the nut extending circumferentially from a first circumferential end to a second circumferential end, the inner radial surface being disposed within the spiral track.The travel limiting assembly further includes a housing radially surrounding the nut, wherein the outer radial surface of the nut includes a radially extending tab disposed within an axially extending groove defined by the inner surface of the housing to rotationally secure the nut, wherein the nut is rotationally secured such that rotation of the shaft translates the nut axially along the spiral track, wherein the first track end, the second track end, the first circumferential end, and the second circumferential end are positioned to limit axial movement of the nut and rotation of the shaft to a predetermined axial distance of the nut and a predetermined angle of rotation of the shaft, respectively, based on contact between the first circumferential end and the first track end and contact between the second circumferential end and the second track end.The travel limiting assembly further includes a ball recirculation circuit disposed between the nut and the spiral track.

[0007] These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the present disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. Fig. 1 generally illustrates a steering system; Fig. 2 is a perspective, disassembled view of a rotation limiting assembly for the steering system; Fig. 3 is a disassembled elevation view of the rotation limiting assembly; Fig. 4 is a perspective view of the rotation limiting assembly in an assembled state; Fig. 5 is a perspective, partially transparent view of the rotation limiting assembly in the assembled state; Fig. 6 is an end view of a portion of the rotation limiting assembly; Fig. 7 is a perspective view of a portion of the rotation limiting assembly illustrating two different axial positions of a nut of the rotation limiting assembly; Fig. 8 is an elevational view of a portion of the rotation limiting assembly illustrating two different axial positions of the rotation limiting assembly nut; Fig. 9 is a perspective view of the nut in a first rotation limiting position; Fig. 10 is a perspective view of the nut in a second rotation limiting position; Fig. 11 is a perspective, disassembled view of the rotation limiting assembly according to another aspect of the disclosure; Fig. 12 is a cross-sectional view of the rotation limiting assembly according to Fig. 11; Fig. 13 is a perspective, disassembled view of the rotation limiting assembly according to another aspect of the disclosure; Fig. 14 is an end view of the rotation limiting assembly of Fig. 13; Fig. 15 is a perspective view of the rotation limiting assembly of Fig. 13; Fig. 16 is a perspective view of the rotation limiting assembly according to another aspect of the disclosure; and Fig. 17 is a perspective, disassembled view of the rotation limiting assembly according to another aspect of the disclosure. DETAILED DESCRIPTION

[0009] Referring now to the figures, in which the present disclosure is described with reference to specific embodiments, but not by way of limitation, it is to be understood that the disclosed embodiments are merely illustrative of the present disclosure, which may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

[0010] With reference first to Fig. 1, vehicles such as cars, trucks, sport utility vehicles (SUVs), crossovers, minivans, watercraft, aircraft, off-road vehicles, recreational vehicles, or other suitable vehicles include a steering system. The steering system disclosed herein is generally designated by the numeral 10 and is a steer-by-wire steering system. The steering system 10 includes a handwheel 12 that can be grasped and rotated by a user to provide steering input commands for performing vehicle steering maneuvers. The handwheel 12 is operatively coupled to a steering column assembly 14. The steering column assembly 14 includes a steering shaft 16 that rotates with the handwheel 12. The steering shaft 16 and the steering column assembly 14 extend from near the handwheel 12.Steer-by-wire steering systems typically include one or more controllers that control various aspects of the steering system, including, but not limited to, controlling one or more electric motors and / or one or more actuators of the steering system. The steer-by-wire steering system 10 does not include a continuous mechanical coupling between the handwheel 12 and a rack 18. The steer-by-wire steering system 10 includes a handwheel actuator 20 and a roadwheel actuator 22, as generally illustrated.

[0011] As disclosed above, the steering system 10 does not include a continuous mechanical connection between the handwheel 12 and the rack 18. Based on the disclosed configuration of the steering system 10, the embodiments disclosed herein provide an assembly that defines the rotational limits of the steering shaft 16 and thus the handwheel 12.

[0012] Now with reference to Fig. 2 and Fig. 3, a travel limiter assembly 30 is shown in a disassembled state. The travel limiter assembly 30 includes a shaft 32 that is operatively coupled to the steering shaft 16. As used herein, the term "operatively coupled" refers to the direct or indirect coupling of components. Alternatively, in some embodiments, the shaft 32 may be integrally formed with the steering shaft 16. Regardless of the particular connection to the steering shaft 16, the shaft 32 rotates with the steering shaft 16 about an axis A upon rotation of the handwheel 12. In addition to the shaft 32, the travel limiter assembly also includes a housing 34, a bearing 36, a nut 38, and an end cover 40.

[0013] Fig. 4 and Fig. 5 illustrate the travel limiting assembly 30 in an assembled state. In Fig. In Figure 5, the housing 34 is shown transparent to illustrate the other components of the travel limiting assembly 30 in their respective assembly positions. As shown, the shaft 32 includes a cylindrical portion 42 and a track portion 44. The bearing 36 is disposed between an outer surface of the cylindrical portion 42 of the shaft 32 and an inner surface of the housing 34 to support controlled rotation of the shaft 32 during operation.

[0014] Now with reference to Fig. 5 and Fig. 6, the nut 38 is a plate structure having a first side 46 and a second side 48 that define the axial thickness of the nut 38. The nut 38 extends radially from an inner radial surface 50 to an outer radial surface 52. The nut 38 extends circumferentially from a first end 54 to a second end 56. The angle between the first circumferential end 54 and the second circumferential end 56 can vary depending on the specific application. In the illustrated example, the angle between the first circumferential end 54 and the second circumferential end 56 is approximately 180 degrees to define a semicircular arc.It should be noted, however, that the specific angle between the first circumferential end 54 and the second circumferential end 56 may vary due to manufacturing tolerances and / or different custom angles used to achieve different travel limit angles as described herein.

[0015] The inner radial surface 50 of the nut 38 is disposed within the spiral track 58 recessed into the track portion 44 of the shaft 32. The spiral track 58 may be formed by recesses defined by protruding segments extending radially outward from the shaft 32, or it may be defined as a recessed portion within the track portion 44 of the shaft 32. The spiral track 58 extends helically along the shaft 32 over a partial axial length of the shaft 32.

[0016] The outer radial surface 52 of the nut 38 includes a plurality of tabs 60 that extend radially outward from the outer radial surface 52. The plurality of tabs 60 are circumferentially spaced from one another. The number of tabs, the circumferential spacing between the tabs, and the radial length of the tabs may vary depending on the particular application. For example, in the illustrated embodiment, the plurality of tabs 60 includes seven (7) tabs, but it should be understood that this number of tabs is only an example of the number of tabs that may be present. Each of the plurality of tabs 60 is at least partially seated in a corresponding one of a plurality of grooves 62 defined by the inner surface of the housing 34. The plurality of grooves 62 extend axially in a direction substantially parallel to the longitudinal axis A of the shaft 32.

[0017] The end cover 40 is operatively coupled to the housing 34 at one end thereof. As shown in Fig. 3, the end cover 40 includes a plurality of projections 64 that extend toward the nut 38 when assembled. The plurality of projections 64 extend axially of the nut 38, but not over a common axial extent. In particular, at least some of the plurality of projections 64 extend over a different axial length. The axial distance variation of the projections 64 defines an orientation of the nut 38 when the nut 38 is disposed at the end of the spiral track 58 closest to the end cover 40. In particular, the plane of the nut 38 is not oriented perpendicular to the longitudinal axis A of the shaft 32 because the nut 38 must seat within the spiral track 58.

[0018] Fig. 7 and Fig. 8 illustrate two different positions of the nut 38 within the spiral track 58. During operation, the rotation of the shaft 32 corresponds to the rotation of the steering shaft 16 and the handwheel 12. The nut 38 is restricted in its rotational movement due to the plurality of tabs 60 arranged in the grooves 62 of the housing 34, since the housing 34 is stationary relative to the shaft 32. The rotational restriction of the nut 38 results in an axial path of the nut 38 along the spiral track 58. The axial path of the nut 38 is freely possible over the entire length of the spiral track 58, so that the rotation of the shaft 32 and thus of the steering shaft 16 and the handwheel 12 is not impeded. However, after a predetermined angle of rotation of the shaft 32 in a first direction, axial displacement of the nut 38 causes one of the circumferential ends 54, 56 of the nut 38 to engage a first end 70 of the spiral track 58 to prevent further rotation of the shaft 32 in the first direction ( Fig. 9). The rotation of the handwheel 12 is also stopped in the first direction at this position due to the structural connection of the shaft 32 to the steering shaft 16 and the handwheel 12. In the first axial position of the nut 38, which is defined by the end of the spiral track 58, rotation in an opposite direction, the second direction, is possible. However, after a predetermined angle of rotation of the shaft 32 in the second direction, axial displacement of the nut 38 causes one of the circumferential ends 54, 56 of the nut 38 to engage a second end 72 of the spiral track 58 to prevent further rotation of the shaft 32 in the second direction ( Fig. 10). The rotation of the handwheel 12 is also stopped in the second direction at this position due to the structural connection of the shaft 32 to the steering shaft 16 and the handwheel 12.

[0019] Now with reference to Fig. 11 and Fig. 12, a second embodiment of the travel limiting assembly is shown in a disassembled state and is generally designated by the number 130. The travel limiting assembly 130 includes a shaft 132, a housing 134, a bearing 136, and a nut 138. The shaft 132, the housing 134, and the bearing 136 are constructed similarly or identically to the shaft 32, the housing 34, and the bearing 36 of the travel limiting assembly 30, which is used in conjunction with Fig. 2 to 10 are described in detail. Therefore, their respective structure and functionality will not be discussed twice here.

[0020] The nut 138 includes the same features as the nut 38, but additionally includes an axially extending body portion 140 with a window 142 formed therein. The window 142 facilitates the loading of a plurality of balls 144 for a recirculating ball assembly 146. The plurality of balls 144 are disposed within the spiral track 58 of the shaft 32 and are retained by the axially extending portion 140 of the nut 138. The recirculating ball assembly 146 provides frictionless relative axial movement between the nut 138 and the shaft 32.

[0021] Now with reference to Fig. 13 to 15, other embodiments of the travel limit assembly are shown and generally designated by the numeral 200. The travel limit assembly 200 is shown with pins 202 inserted through holes 204 of the shaft 32 within the track portion 44. In such an embodiment, a plurality of tabs 206 extend radially inwardly away from an inner diameter 208 of the nut 38. This allows the tabs 206 to move across the path of the spiral track 58 while the remainder of the nut 38 can be stamped flat. In the illustrated embodiments, the pins 202 are disposed within the shaft 32 to define both travel limit restrictions, but it is conceivable that the shaft 32 itself includes integrally formed projections that define one or both ends of the travel limit limit. Furthermore, as shown in Fig. 16, an end cover 240 may include a projection or spiral portion 242 defining one end of the travel limit boundary.

[0022] Now with reference to Fig.17, another embodiment of the travel limit assembly is shown and generally designated by the numeral 300. The travel limit assembly 300 includes a shaft 332 having a splined region 334 that mates with a sleeve 336. The sleeve 336, in some embodiments, may be formed of plastic and includes an inner diameter with splines that mate with the splined region 334 of the shaft 332. The outer surface of the sleeve 336 includes a spiral track 338 within which the nut 38 moves. As described above in connection with other embodiments, the nut 38 may include an inner diameter that moves within the spiral track 338, or it may include offset tabs 306 that do so. The travel limit limits may be defined by pins 302 or retaining rings 310.

[0023] While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure may be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not described herein that are within the scope of the present disclosure. Furthermore, it should be understood that while various embodiments of the present disclosure have been described, aspects of the present disclosure may include only some of the described embodiments or combinations of the various embodiments. Accordingly, the present disclosure is not to be considered limited by the foregoing description.

Claims

[1] A travel limiting assembly for a vehicle steer-by-wire steering system, comprising: a shaft extending along an axis and rotatable about the axis, the shaft defining a spiral path extending from a first path end to a second path end; and a nut extending radially from an inner radial surface to an outer radial surface, the nut extending circumferentially from a first circumferential end to a second circumferential end, the inner radial surface being disposed within the spiral track, the nut being rotatably fixed such that rotation of the shaft translates the nut axially along the spiral track, the first track end, the second track end, the first circumferential end, and the second circumferential end being positioned to limit axial movement of the nut and rotation of the shaft to a predetermined axial distance of the nut and a predetermined angle of rotation of the shaft, respectively, based on contact between the first circumferential end and the first track end and contact between the second circumferential end and the second track end. [2] The travel limiting assembly of claim 1, further comprising a housing radially surrounding the nut, the outer radial surface of the nut including a radially extending tab disposed in an axially extending groove defined by the inner surface of the housing for rotatably retaining the nut. [3] The travel limiting assembly of claim 2, wherein the radially extending tab is one of a plurality of tabs, wherein the axially extending groove is one of a plurality of grooves, each of the tabs being disposed within one of the grooves. [4] The travel limiting assembly of claim 1, wherein the angle between the first circumferential end and the second circumferential end is 180 degrees. [5] The travel limiting assembly of claim 2, further comprising an end cover operatively coupled to one end of the housing to axially retain the nut within the housing. [6] The travel limiting assembly of claim 5, wherein the end cover includes a plurality of projections positioned to contact the nut when the nut is at either the first track end or the second track end, at least two of the plurality of projections extending axially to different lengths to position the nut in a desired position within the spiral track of the shaft. [7] The travel limiting assembly of claim 1, wherein the shaft includes a track portion and a cylindrical portion, the nut being disposed on the track portion and a bearing being disposed on the cylindrical portion. [8] The travel limiting assembly of claim 1, wherein the shaft is operatively coupled to a steering shaft. [9] A travel limiting assembly according to claim 1, wherein the shaft is formed integrally with a steering shaft. [10] Steer-by-wire vehicle steering system, comprising: a steering shaft configured to be rotated during steering maneuvers of a vehicle; a handwheel actuator operatively coupled to the steering shaft; and a shaft operatively coupled to or integral with the steering shaft, the shaft being limited to a predetermined angle of rotation by a travel limiting assembly, comprising: a spiral path defined along an axial portion of the shaft, the spiral path extending from a first path end to a second path end; a nut extending radially from an inner radial surface to an outer radial surface, the nut extending circumferentially from a first circumferential end to a second circumferential end, the inner radial surface being disposed within the spiral track; and a housing radially surrounding the nut, the outer radial surface of the nut including a radially extending tab disposed in an axially extending groove defined by the inner surface of the housing for rotatably securing the nut, wherein the nut is rotatably fixed such that rotation of the shaft translates the nut axially along the spiral track, wherein the first track end, the second track end, the first circumferential end, and the second circumferential end are positioned to limit the axial movement of the nut and the rotation of the shaft to a predetermined axial distance of the nut and a predetermined angle of rotation of the shaft, respectively, based on the contact between the first circumferential end and the first track end and the contact between the second circumferential end and the second track end. [11] The vehicle steering system of claim 10, wherein the radially extending tab is one of a plurality of tabs, the axially extending groove being one of a plurality of grooves, each of the tabs being disposed within one of the grooves. [12] A vehicle steering system according to claim 10, wherein the angle between the first circumferential end and the second circumferential end is 180 degrees. [13] The vehicle steering system of claim 10, further comprising an end cover operatively coupled to one end of the housing to axially retain the nut within the housing. [14] The vehicle steering system of claim 13, wherein the end cover includes a plurality of projections positioned to contact the nut when the nut is at the first track end or the second track end, at least two of the plurality of projections extending axially to different lengths to position the nut in a desired position within the spiral track of the shaft. [15] A vehicle steering system according to claim 10, wherein the shaft includes a track portion and a cylindrical portion, the nut being located on the track portion and a bearing being located on the cylindrical portion. [16] A travel limiting assembly for a steer-by-wire vehicle steering system, comprising: a shaft extending along an axis and rotatable about the axis, the shaft defining a spiral path extending from a first path end to a second path end; a nut extending radially from an inner radial surface to an outer radial surface, the nut extending circumferentially from a first circumferential end to a second circumferential end, the inner radial surface being disposed within the spiral track; a housing radially surrounding the nut, the outer radial surface of the nut including a radially extending tab disposed in an axially extending groove defined by the inner surface of the housing for rotationally securing the nut, wherein the nut is rotationally fixed such that rotation of the shaft axially displaces the nut along the spiral track, wherein the first track end, the second track end, the first circumferential end, and the second circumferential end are positioned to limit the axial movement of the nut and the rotation of the shaft to a predetermined axial distance of the nut and a predetermined angle of rotation of the shaft, respectively, based on the contact between the first circumferential end and the first track end and the contact between the second circumferential end and the second track end; and a ball orbit arranged between the nut and the spiral track. [17] The vehicle steering system of claim 16, wherein the radially extending tab is one of a plurality of tabs, the axially extending groove being one of a plurality of grooves, each of the tabs being disposed within one of the grooves. [18] The vehicle steering system of claim 16, further comprising an end cover operatively coupled to one end of the housing to retain the nut axially within the housing, the end cover including a plurality of projections positioned to contact the nut when the nut is at the first track end or the second track end, at least two of the plurality of projections extending axially to different lengths to position the nut in a desired position within the spiral track of the shaft.

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