Steering column assembly with retractable arm and electromechanical actuator for controlling the arm

Abstract

The invention relates to a steering column assembly (10) of a steering system having a steering wheel for a vehicle, comprising: • a column body (14) which is intended to be mounted on a vehicle structure; • an arm (16) which is carried by the column body (14) and extends in a longitudinal direction (AX), wherein the arm (16) is mounted such that it is longitudinally translationally retractable with respect to the column body (14) in order to determine the position of the steering wheel of the steering system; • an electromechanical actuator (26) for translationally moving the arm (16) at different speeds, which has the following: • an electric motor (27) for driving in rotation; • a rotationally fixed nut (34) fastened to the arm; • a translationally fixed first rod (31) that is rotatable about its axis by being set in rotation by the electric motor (27), wherein the first rod (31) has a thread; • a second rod (32) that extends concentrically with the first rod (31), wherein the second rod (32) is rotatable about its axis and translationally movable, wherein the second rod (32) has a first thread which cooperates with the thread of the first rod (31), and a second thread which cooperates with the thread of the nut (34); • a system for selectively restricting the degree of freedom of the second rod, the system selectively allowing only rotation of the second rod (32) or translation of the second rod (32) depending on the position of the nut (34) along the second rod (32); wherein the cooperation of threads between the first and the second rod (31, 32) is defined by a thread pitch which is different from a defined thread pitch for the cooperation of threads between the second rod (32) and the nut (34).

Description

[0001] Description

[0002] Title with retractable arm and electromechanical actuator to control the arm

[0003] Technical field of the invention

[0004] The present invention relates to the general field of motor vehicles and, more particularly, to an electromechanical actuator for controlling the advancement of a retractable steering column arm which conditions the position of a vehicle steering wheel.

[0005] State of the art

[0006] The steering column is one of the components that make up a vehicle's steering system. It is present in all vehicles and enables communication between the steering wheel and the wheels.

[0007] In a known manner, the steering column comprises a fixed support rigidly mounted on a superstructure element of the vehicle, such as the chassis, and an arm which determines the position of the steering wheel by extending the fixed support into the passenger compartment of the vehicle in the direction of the seat on which the driver sits.

[0008] In practice, the distance between the steering wheel and the seat must be large enough to allow the driver to easily adjust their position without having to contort themselves. This characteristic is often at odds with the driving position, where the measured distance between the steering wheel and the seat is rather limited to allow the driver to comfortably and securely grip the steering wheel. To solve this problem, it has been proposed to make the arm retractable, giving it the ability to retract and extend.

[0009] This solution allows the steering wheel to be moved between a stowed position, where the steering wheel is far enough from the seat to not interfere with the driver's adjustment, and a forward position, where the seat-to-steering wheel space is reduced. It should be noted that this solution is particularly interesting for equipping an autonomous vehicle, where a retracted arm position can be adopted for comfort purposes in a driving situation that does not require manual trajectory control.

[0010] To control the arm's advancement, it is known to provide an electromechanical actuator that allows the steering wheel to be moved without manual intervention by the driver. Conventionally, the electromechanical actuator uses an electric motor and a screw-and-nut system, whose screw rotates to move the nut attached to the arm.

[0011] To meet the needs of users, it is desirable that the advance speed of the arm can be adjusted as needed:

[0012] - in the case of a functional adjustment of the steering wheel position, namely when the steering wheel is moved to adapt to the morphology of the driver who takes it in hand in the driving situation, the speed of movement must be moderate in order to ensure precise adjustment of the position;

[0013] - When the steering wheel is fully retracted for storage, or conversely, when returning it to its operating position, a higher arm advancement speed is desirable to limit the associated waiting time. To meet this dual requirement, the use of a sophisticated electric motor, such as a brushless type, has been proposed. This type of electric motor offers a wide range of operating speeds and thus allows the arm's extension / retraction speed to be modulated by varying the screw's rotational speed. Nevertheless, the integration of such a motor entails significant additional costs, particularly with regard to its control system.

[0014] Another solution considered is to make the arm telescopic, consisting of interlocking sections that move relative to each other in translation, and to provide multiple actuators, each dedicated to moving a specific section. Such an arrangement increases costs and creates complexity in distributing the actuator controls to assign the correct setpoint to each of them.

[0015] The aim of the invention is to propose an electromechanical actuating structure which makes it possible to avoid the above-mentioned disadvantages.

[0016] Description of the invention

[0017] For this purpose, the invention relates to a steering column assembly of a steering system with a steering wheel for a vehicle, for example a motor vehicle, comprising:

[0018] - a column body intended to be mounted on a vehicle structure;

[0019] - an arm carried by the column body and extending in a longitudinal direction, the arm being mounted retractably in longitudinal translation between a retracted and an extended advancement state with respect to the column body, the advancement state of the arm determining the position of the steering wheel of the steering system;

[0020] - an electromechanical actuator for moving the arm in translation at different speeds, the electromechanical actuator comprising:

[0021] -- an electric motor for rotational propulsion;

[0022] -- a motion converter assembly for converting a rotation provided by the electric motor into a translation of the arm, the motion converter comprising:

[0023] — a nut fixed to the arm in a rotationally fixed manner, the nut having a thread;

[0024] — a first rod extending along a rod axis of longitudinal extension, the first rod being fixed in translation along its axis and rotatable about its axis by being set in rotation by the electric motor, the first rod being threaded;

[0025] — a second rod extending longitudinally along a respective rod axis with longitudinal extension concentric with the first rod, the second rod being movable in rotation about its axis and in translation along its axis, the second rod having a first thread cooperating with the thread of the first rod and a second thread cooperating with the thread of the nut; — a system for selectively restricting the degree of freedom of the second rod, which system selectively and as a function of the position of the nut along the second rod:

[0026] — only allows rotation of the second rod about its axis in order to move the arm by screwing / unscrewing the nut along the second thread of the second rod when the first rod is rotated by the electric motor;

[0027] — only allows translation of the second rod along its axis to move the arm by translation of the second rod carrying the nut, by screwing / unscrewing the second rod along the first rod by threaded engagement; in which the threaded engagement between the first and second rods is defined with a thread pitch different from a defined thread pitch for the threaded engagement between the second rod and the nut

[0028] The invention also relates to a steering column assembly as defined, in which: - the thread of the nut is an internal thread;

[0029] - the thread of the first rod is an external thread, the first rod having a first rod body which is delimited by an outer wall on which the thread is formed;

[0030] - the second rod has a second hollow rod body, the thickness of which is also limited by:

[0031] -- an outer wall on which the second thread is formed, which is an external thread cooperating with the thread of the nut, the nut being carried by the second rod body;

[0032] -- an inner wall on which the first thread is formed, which is an internal thread cooperating with the thread of the first rod, wherein the second rod body at least partially radially encloses the first rod body

[0033] The invention also relates to a steering column assembly so defined, wherein the threaded engagement between the first and second rods is defined with a larger thread pitch value than the thread pitch defining the threaded engagement between the second rod and the nut.

[0034] The invention also relates to a steering column assembly as defined, in which the system for selectively restricting the degree of freedom comprises:

[0035] - radial openings formed continuously in the second rod in the region of a longitudinal section thereof, the openings connecting the outer and inner walls of the second shaft while extending at a distance from the second thread;

[0036] - balls each arranged in one of the individual radial openings, the balls having a diameter greater than the thickness of the second rod in order to project radially beyond the corresponding opening;

[0037] - a ring radially enclosing the second rod while being movable in longitudinal translation, the ring having a sufficient longitudinal extension to simultaneously radially enclose the openings and a part of the second thread of the second rod, the ring having an inner wall opposite the second rod which widens from a portion of smaller diameter arranged flush with the second rod;

[0038] - a spring that passively holds the ring in a blocking position for which:

[0039] -- the smaller diameter portion of the inner wall of the ring is flush with the radial openings, and

[0040] -- the inner wall radially encloses part of the external thread of the second rod;

[0041] - an end piece extending the first rod into the second rod and defining a longitudinal abutment surface against which the second rod bears in a distal position with respect to the first rod, the end piece being adapted to cooperate, in the distal position of the second rod, with the balls pressed against it by the ring in the blocking position; the nut being adapted to release the ring from its blocking position by pressing against the spring in translation in response to rotation of the second rod along the second threaded piece radially enclosed by the ring in the blocking position, the release of the ring causing an increase in the measured distance between the inner wall of the ring and the openings, so as to allow the balls to move radially away from the end piece.

[0042] The invention also relates to a steering column assembly so defined, in which the extension cooperates with the balls when the ring is in the blocking position and the second rod in distal position bears against the extension to block translation of the second rod.

[0043] The invention also relates to a steering column assembly so defined, in which the extension piece comprises a frustoconical part defined longitudinally by a large base and a small base, the large base being closer to the first rod than the small base, the frustoconical part being dimensioned such that:

[0044] - the diameter of the balls is greater than the measured radial distance between the large base and the smallest diameter portion of the inner wall of the ring; and - translation of the second rod from its distal position causes the openings to move into radial alignment with the large base; and wherein loosening of the ring by the nut causes the measured radial distance between the inner wall and the large base to increase until it is greater than the diameter of the balls.

[0045] The invention also relates to a steering column assembly so defined, in which the extension cooperates with the balls when the ring is in the blocking position and the second rod in distal position bears against the extension to force a rotational coupling of the first and second rods.

[0046] The invention also relates to a steering column assembly thus defined, in which the extension is delimited by an outer wall provided with notches extending longitudinally in a circular arc-shaped profile, the number of notches being equal to or greater than the number of openings and associated balls, the extension being dimensioned such that the balls are pressed into the notches in the blocking position of the ring and in the distal position of the second rod; and in which the loosening of the ring by means of the nut causes an increase in the measured radial distance between the inner wall and the extension until it is greater than the diameter of the balls to allow them to exit the notches.

[0047] The invention also relates to a steering column assembly as defined, in which the arm is telescopic in nature, being formed from a plurality of sections movable relative to one another in translation, including:

[0048] - a first longitudinally extending portion supported by the column body while being movable in longitudinal translation relative to the column body; and

[0049] - a second section inserted into the first section and longitudinally displaceable along the first section; wherein the electromechanical actuator further comprises a rotational guide bearing enclosing the second rod by being rigidly mounted in translation with the second rod; and wherein the bearing is rigidly connected to the first section and the nut is rigidly connected to the second section.

[0050] Short description of the drawings

[0051] Further features and advantages of the invention will become apparent upon reading the following detailed description, for the understanding of which reference is made to the accompanying drawings in which:

[0052] - [Fig.1] is a perspective view of a steering column assembly according to a first embodiment of the invention, comprising a steering column body, a telescopic arm carried by the steering column body and an electromechanical actuator for extending / retracting the telescopic arm.

[0053] - [Fig.2] is a cross-sectional view of the steering column assembly of Figure 1, comprising an electromechanical actuator according to a first embodiment;

[0054] - [Fig.3] is a partial view of Figure 2 illustrating the electromechanical actuator for extending / retracting the telescopic arm according to the first embodiment in an operating condition for adjusting the steering wheel comfort;

[0055] - [Fig.4] is a detailed view of a device for selectively restricting the degree of freedom in the operating state of the electromechanical actuator in the steering wheel comfort setting of Fig. 3;

[0056] - [Fig.5] is a view corresponding to Figure 3 in an operating condition for adjusting the steering wheel ergonomics;

[0057] - [Fig.6] is a detailed view of the device for selectively restricting the degree of freedom in the operating state of the electromechanical actuator for steering wheel ergonomics adjustment in Figure 5;

[0058] - [Fig.7] is a perspective and partially sectioned view of the electromechanical actuator for extending / retracting the telescopic arm according to a second embodiment;

[0059] - [Fig.8] is a perspective view of a cross-section of a steering column assembly according to a second embodiment of the invention, comprising a steering column body, a sliding arm carried by the steering column body and an electromechanical actuator for extending / retracting the arm according to the second embodiment, illustrating a fully extended state of the arm;

[0060] - [Fig. 9] is a perspective view of a cross-section of a steering column assembly according to Fig. 8, illustrating a fully retracted condition of the arm.

[0061] Detailed description of the invention

[0062] In the following description, identical, similar or analogous elements are designated by the same reference numerals.

[0063] As can be seen in Figures 1 and 2, a steering column assembly 10 according to a first embodiment of the invention for a vehicle steering system is shown. The assembly 10 comprises a frame 12 intended to be rigidly attached to an element of the superstructure of a vehicle, such as a chassis, a column body 14 supported by the frame 12, and an arm 16 supported by the column body 14.

[0064] The column assembly 10 further includes a steering shaft 18 extending longitudinally along an axis AX. The arm 16, also longitudinally extending, radially surrounds the steering shaft 18. The radial direction is understood to mean a direction extending along an axis AY, which is orthogonal to the axis AX.

[0065] The steering shaft 18 is intended to be connected in a rotationally fixed manner to a vehicle steering wheel (not shown) by a rigid coupling. More specifically, the steering shaft 18 includes a free end 18a that projects longitudinally beyond the arm 16 to accommodate the vehicle steering wheel by fitting.

[0066] Within the scope of the invention, the column assembly 10 is intended to allow adjustment of the longitudinal position of the steering wheel in the passenger compartment of the vehicle equipped therewith. In this regard, the arm 16 is provided with the ability to extend / retract longitudinally with respect to the column body 14, and the steering shaft 18 is rigidly mounted in translation to the arm 16. In particular, the arm 16 and the column body 14 are designed to allow relative longitudinal displacement, which in practice corresponds to a displacement of the shaft 16 with respect to the column body 14, since the column body 14 is rigidly connected longitudinally to the frame 12, which is fixed after installation in the vehicle. It should be noted that the column body 14 can be pivotally mounted with respect to the frame 12 by means of a mechanism designated 19, to further allow adjustment of the height of the steering wheel in the passenger compartment.In this case, the column body 14 always maintains a longitudinal connection with the frame 12.

[0067] In the case of the first embodiment, the arm 16 is telescopic in that it is in the form of a combination of:

[0068] - a first portion 20 which is carried by the column body 14 and is movable in longitudinal translation with respect to the column body 14; and

[0069] - a second section 22 which is inserted into the first section 20 and is longitudinally displaceable along the first section 20.

[0070] In detail, Figure 1 shows that the first section 20 radially encloses a hollow cylindrical part 14a with a longitudinal extension of the column body 14 in order to be able to slide along the outside of the part. In addition, the first section 20 has a bore 24 in the longitudinal direction, into which the second section 22 is installed with a sliding fit. The assembly is designed such that the second section 22 can extend within the hollow cylindrical part 14a of the column body. As can be seen, the first section 20 extends radially outside the hollow cylindrical part 14a of the column body, and the hollow cylindrical part 14a extends radially outside the second section 22.However, it should be noted that the invention is not limited to this particular arrangement as long as a sliding movement of the first section 20 with respect to the column body 14 and a sliding movement of the second section 22 with respect to the first section 20 is enabled.

[0071] The second section 22 is longitudinally displaceable along the bore 24 between a fully retracted position and a fully extended position. The fully retracted and fully extended positions of the second section 22 are defined such that in the fully retracted position, a greater extent of the second section 22 is accommodated in the bore 24 than in the fully extended position.

[0072] Analogously, the longitudinal displacement of the first section 20 is limited between a fully retracted position and a fully extended position. In the fully retracted position, the first section 20 covers the hollow cylindrical section 14a of the column body 14 more than in the extended position.

[0073] In addition, the steering shaft 18 is also telescopic in nature along its extension in the arm 16. In particular, the steering shaft 18 is connected in translation to the arm 16 in such a way that the extension or retraction of the arm 16 respectively entails the extension or retraction of the steering shaft 18. Since the steering shaft 18 also supports the steering wheel and is rigidly connected in translation to the displacement of the arm 16, it follows that the extended state of the arm 16 determines the position of the steering wheel in the passenger compartment. In practice, the arm 16 acts like a muscle: its actuation causes a variation in the longitudinal extension of the steering shaft 18 and thus consequently leads to the displacement of the steering wheel, which is rigidly connected to the steering shaft 18.

[0074] Overall, the longitudinal extension of the arm 16 is adjustable between a fully retracted state of the arm and a fully extended state of the arm, these positions being determined by the fully extended / retracted state of the two basic sections 20, 22 of the arm 16. In practice, the fully extended state of the arm 16 corresponds to the case in which the first and second sections 20, 22 are each in the fully extended position, as opposed to the case in which the first and second sections 20, 22 are each in the fully retracted position, which characterizes the fully retracted state of the arm 16. Considering that the steering column assembly 10 is installed in the vehicle, namely with a fixed frame 12 and the arm 16 extending from the frame 12 to a driver's seat, then:

[0075] - the extension of the telescopic arm 16 corresponds to the translation of the first and second portions 20, 22 in a direction designated S1, which causes a displacement of the steering wheel carried by the steering shaft 18 towards the driver's seat; and consequently

[0076] - the retraction of the arm 16 corresponds to the translation of the first and second portions 20, 22 in the opposite direction to S1, which leads to the removal of the steering wheel from the driver's seat.

[0077] The extension and retraction of the arm 16 relative to the column body 14 is ensured by an electromechanical actuator 26 on the steering column assembly 10. The electromechanical actuator 26 comprises an electric motor 27 for driving it in rotation, which is advantageously attached to the column body 14, and a drive mechanism 28 that drives the sections 20, 22 in translation in response to a rotation provided by the electric motor 27.

[0078] The idea underlying the invention is to provide a control of the retraction / extension speed of the arm 16 by the electromechanical actuator 26 that is precisely tailored to the needs, namely providing different displacement speeds of the steering wheel according to the following cases:

[0079] - if the driver of the vehicle wishes to make a so-called comfort adjustment, which consists in changing the position of the steering wheel to ensure a good driving position, a low / moderate advance speed is required to ensure a precise adjustment; and

[0080] - When the vehicle driver wishes to perform a so-called ergonomic adjustment, which consists in either fully pushing the steering wheel into a stowed position when not in use or, conversely, restoring the steering wheel's use by returning it to the driver from its stowed position, a higher arm advance speed value is desirable to limit the associated waiting time. In this regard, the drive mechanism 28 of the electromechanical actuator 26 includes a motion converter assembly 30, whose particular structure ensures the conversion of a rotation provided by the electric motor 27 into an extension / retraction of the arm 16 at different speeds.Within the first embodiment of the column assembly 10, the motion converter 30 advantageously takes advantage of the telescopic nature of the arm 16 by imposing a first sliding speed on the second section 22 relative to the first section 20 and a second sliding speed on the first and second sections 20, 22 moving in an assembly motion relative to the column body 14. The result of this difference in sliding speeds produces overall different extension / retraction speeds of the arm 16.

[0081] According to the first embodiment, the motion converter assembly 30 results from the combination of:

[0082] - a first, merely rotatable rod 31 driven by the electric motor 27;

[0083] - a second rod 32 aligned with the first rod 31, which is both rotatable and translatory and which cooperates with the first rod 31 via a thread;

[0084] - a purely translational nut 34 which cooperates with the second rod via a thread;

[0085] - a rotation guide bearing 36 of the second rod 32; and

[0086] - a system 38 for selectively restricting a degree of freedom of the second threaded rod.

[0087] As can be seen in more detail in Figures 3 to 6, which illustrate the electromechanical actuator 26 equipping the steering column assembly 10 according to the first embodiment, the first rod 31 extends along a rod axis AX1 of longitudinal extension. The first rod 31 is driven in rotation by the electric motor 27 through a reduction gear 39 of the drive mechanism 28. The gear 39 and the electric motor 27 are housed in a housing 40 fixed to the column body 14 to jointly form a so-called geared motor module. The first threaded rod 31 is blocked in translation with respect to the column body 14, advantageously held in position in the region of the reduction gear 39.

[0088] It should be noted that a direct drive of the first threaded rod 31 by the electric motor 27, namely without a gearbox, can be considered without going beyond the scope of the invention.

[0089] From a structural point of view, the first rod has two ends, including a first end for coupling to the electric motor 31a, advantageously by means of the reduction gear 39, and a second free end 31b. The first rod 31 extends from its first end 31a to its second end 31b in the extension direction S1 of the arm 16.

[0090] In particular, the first rod 31 is in the form of a continuous cylindrical body comprising two parts, including a first part 40 with a smooth periphery extending from the first end 31a, and a second part 42 with an external thread extending from the second end 31b. The interface between the two parts, located between the two ends 31a, 31b of the first rod 31, defines a shoulder designated 44.

[0091] An external thread is understood to mean a thread that is formed in the outer peripheral wall of the rod body and projects outwards in the radial direction AY1 perpendicular to the rod longitudinal axis AX1.

[0092] The second rod 32 extends coaxially with the first rod 31 along a respective rod axis aligned with the rod axis AX1 of the first rod 31. The second rod 32 extends from a first end 32a to a second end 32b in the direction S1. The second rod 32 is in the form of a hollow cylindrical body, into which the first rod 31 partially extends.

[0093] As can be seen in detail in Figures 4 and 6, the body has three

[0094] Parts that form a material continuity and of which a first part 46 extends from the first end 32a, a second part 48 extends from the second end 32b, and a third part 50 extends as an interface between the first and second parts 46, 48. The third part 50 extends between the first and second ends 32a, 32b of the second rod 32.

[0095] The first part 46 is radially delimited by an outer wall and an inner wall. The outer wall of the first part 46 can be smooth, while its inner wall is provided with an internal thread, also called a threaded bore. An internal thread is understood to be a thread formed in the inner wall and extending beyond the rod's longitudinal axis AX1 in the radial direction AY1.

[0096] In particular, the first part 46 of the second rod 32 overlaps the outer wall of the second part 42 of the first rod 31 along its longitudinal extent. In the region of this overlap, the respective external and internal threads of the parts 42 and 46 of the rods 31, 32 interact.

[0097] The second part 48 of the second rod 46 is radially delimited by an outer wall and an inner wall. The outer wall of the second part 48 is provided with an external thread, while its inner wall may be smooth.

[0098] Finally, the third part 50 of the second rod 32 is radially delimited by an outer and inner wall, which may be smooth.

[0099] The second and third parts 48, 50 of the second rod 32 are each configured with an inner diameter, namely a diameter measured in the region of their respective inner wall, which is larger than the outer diameter of the second part 42 of the first rod 31.

[0100] In the previous description of the bodies of the first and second rods 31, 32, certain walls are described as being able to have a smooth surface. In practice, a smooth surface for the walls is preferred, as they are not the site of particular interactions during the operation of the motion converter 30. Nevertheless, smoothness is not limiting. The bearing 36 radially surrounds the first part 46 of the second rod 32 and is supported by a rigid clamp 54, visible in Figure 1, which is attached to the first section 20 of the arm 16. The bearing 36 radially surrounds the second rod 32, while also being rigidly connected to the second rod 32 in longitudinal translation. In the example of the figures, the rigid support of the bearing 36 in longitudinal translation with the second rod 32 is ensured by two abutment surfaces, including:

[0101] - a first stop surface represented by a radial projection 56 projecting outwardly beyond the outer wall of the first part 46 of the second rod; and

[0102] - a second stop surface formed by a clip 58 housed in a groove formed on the outer wall of the first part 46 of the second rod.

[0103] As for the nut 34, it radially encloses the second part 48 of the second rod while being rigidly secured to the second portion 22 of the arm 16. The nut 34 includes an internal thread, in other words a threaded bore, which cooperates with the external thread of the second part 48 of the second rod 32.

[0104] From a kinematic point of view, the second rod 32 is designed with two degrees of freedom, possessing both the ability to translate longitudinally and the ability to rotate around its axis. The second rod 32 is jointly supported by the first rod 31 and the nut 34, with which it interacts via threads, and by the rotation guide bearing 36.

[0105] When the electric motor 27 is activated to rotate the first rod 31, the interaction of threads simultaneously between the first and second rods 31, 32 and between the second rod 32 and the nut 34 is capable of producing two results, namely:

[0106] - a mere rotation of the second rod 32 about its axis, resulting in a displacement of the nut 34 along the second part 48 of the second rod 32 by screwing / unscrewing the nut. This results in a translation of the second portion 22 relative to the first portion 20 by the nut 34;

[0107] - a pure longitudinal translation of the second rod 22 by screwing / unscrewing the second rod 32 on the first rod 31 and in particular by screwing / unscrewing the first part 46 of the second rod 32 on the second part 42 of the first rod 31.

[0108] Such a longitudinal translation of the second rod 32 along the first rod 31 is made possible by the fact that the measured inner diameter in the region of the second and third parts 48, 50 of the second rod is larger than the outer diameter of the second part 42 of the first rod.

[0109] The translation of the second rod 32 simultaneously drives the nut 34 and the bearing 36, resulting in simultaneous sliding of the first and second sections 20, 22 of the arm 16. Indeed, the interaction of threads, namely the complementary shape of the internal thread of the nut 34 with the external thread of the second part 48 of the second rod 32, creates a hook effect in this case, forcing the nut 34 to move in translation with the second rod 32. The translation of the bearing 36, which drives the first section 20 of the arm 16 in translation, is enforced by its rigid translational mounting with the second rod 32.

[0110] As can be understood, the described arrangement of the rods 31, 32, the nut 34 and the bearing 36 with respect to the column body 14 and the sections 20, 22 makes it possible to differentiate a first kinematic actuation of the arm 16 by sole sliding of the second section 22 through the nut 34 from a second kinematic actuation of the arm 16 by continuous sliding of the first and second sections 20, 22 through the nut 34 and the bearing 36.

[0111] The creation of a difference in the extension / retraction speed of the arm 16 is thus made possible by forming the threads with different pitches. More specifically, by differentiating the thread pitch defined in the interaction between the first and second rods 31, 32 from the thread pitch defined in the interaction between the second rod 32 and the nut 34, the displacement speed of the nut 34 along the second rod is now different from the displacement speed of the second rod 32 along the first rod 31. This results in a sliding speed of the second section 22 with respect to the first section 20 of the shaft, which is different from the joint sliding of the first and second sections 20, 22 with respect to the column body 14.

[0112] According to this first embodiment, the thread pitches of the first and second rods 31, 32 and the nut 34 are advantageously defined such that the translational speed of the second section 22 relative to the first section 20 is smaller than the translational speed of the second section 22, which entails the translation of the first section 20 relative to the column body 14. As can be understood, the aim of this arrangement is that:

[0113] - the so-called comfort adjustment of the steering wheel is brought about by the displacement of the second part 22 with respect to the second part 20; and

[0114] - the so-called ergonomic adjustment of the steering wheel is caused by the displacement in one piece of the first and second portions 20, 22 with respect to the column body 14.

[0115] In general, the longitudinal translation speed, denoted by V, of either the second rod 32 along the first rod 31 or the nut 34 along the second rod 32 is expressed as the product of the corresponding thread pitch p with the rotational speed N of the first rod 31:

[0116] V = N * p

[0117] Thus, in order to achieve a translational speed of the second section 22 relative to the first section 20 that is lower than the combined translational speed of the first and second sections 20, 22 with respect to the column body 14, the thread pitch defining the interaction between the first and second rods 31, 32 is set greater than the thread pitch defining the interaction between the second rod 32 and the nut 34. In this regard, the invention preferably, but not restrictively, provides for the following:

[0118] - 6 mm, the value of the pitch defining the interaction between the first and second rods 31, 32; and

[0119] - to 2 mm the value of the pitch defining the interaction between the nut 34 and the second rod 32.

[0120] In view of the above, the translation of the second section 22 relative to the first section 20 with pure rotation of the second rod 32 can take place at a speed different from the continuous translation of the first and second sections 20, 22 relative to the column body 14 with pure translation of the second rod 32.

[0121] In order to ensure control over the speed of movement of the steering wheel, the invention therefore involves making the behavior of the second rod 32, either in pure translation or in pure rotation, dependent on the type of adjustment desired, comfort or ergonomics.

[0122] In the context of the invention, the behavior of the second rod 32 is enforced by the system 38 for selectively restricting a degree of freedom.

[0123] Referring to Figures 2 to 6, the first embodiment of the column body 10 is equipped with a first variant of the selective restriction system 38. In this first variant, the selective restriction system 38 is a system that blocks or allows translation of the second rod 32 depending on the position of the nut 34 along the second rod 32.

[0124] From a structural point of view, this selective restriction system 38, in its first variant, results from the merger:

[0125] - by radial openings 60 formed continuously in the second rod 32; - by balls 62, each arranged in a corresponding radial opening 60;

[0126] - by a ring 64 which radially surrounds the second rod 32;

[0127] - by a spring 66 arranged between the ring 64 and the radial projection 56 of the second rod 32; and

[0128] - by an extension piece 68 which extends the first rod 31 in the region of its second end 31b.

[0129] Specifically, the openings 60 are formed in the region of the third part 50 of the body of the second rod 32. They are formed continuously, namely across the thickness of the second rod 32, connecting the smooth outer and inner walls of the third part 50. The openings 60 are formed in the same longitudinal plane and evenly distributed over the circumference of the second rod.

[0130] The balls 62 each have a diameter that is greater than the thickness of the second rod 32, measured in the region of the third part 50 where the openings 60 are formed. This particular feature results in the balls 62 projecting radially beyond the openings 60 in which they are arranged.

[0131] Advantageously, the openings 60 are formed with a point-like reduction in cross-section flush with the inner wall of the second rod 32 to prevent the balls 62 from coming into contact with the thread of the first rod 31 during translation of the second rod 32. This feature prevents the balls from vibrating, following the profile of the thread, which can generate a noticeable knocking noise. As can be understood, this aspect makes it possible to maintain the acoustic atmosphere in the interior and, in particular, to avoid giving the user the impression that the actuator 26 is defective.

[0132] The ring 64 surrounds the second rod 32 and is mounted between the radial projection 56 and the nut 34 for longitudinal translation. It is defined by two side walls 70, including a first side wall 70a oriented relative to the radial projection 56 and a second side wall 70b oriented relative to the nut 34. The ring 64 is dimensioned such that its longitudinal extent, measured between its first and second side walls 70a, 70b, is sufficient to radially enclose the openings 60 and part of the external thread of the second rod 32.

[0133] In addition, the ring has two radial walls connecting the side walls 70, including an inner wall 72i and an outer wall 72e. The inner wall 72i of the ring 64 is oriented toward the second rod 32 and has a diameter in longitudinal section that is evolving. More specifically, the ring 64 is both oriented and designed to form an internal flare in the direction S1, namely from the first side wall 70a to the second side wall 70b. In practice, the measured distance between the inner wall 72i of the ring 64 and the outer wall of the second rod 32 is thus greater the further one moves away from the first side wall 70a in the direction S1 of extension of the arm 16. It should be noted that the inner wall 72i is flush with the second rod 32 in the region of the first side wall 70a, that is, in the region of its smallest diameter section.

[0134] The spring 66 arranged between the ring 64 and the radial projection 56 radially encloses the second rod 32. It is in the form of a compression coil spring whose unloaded length corresponds to the measured distance between the radial projection 56 and the longitudinal plane in which the radial openings 60 are accommodated.

[0135] Advantageously, the spring 66 is connected at its ends to the ring 64 and the radial projection 56 in order to passively hold the ring 64 in a so-called blocking position in which:

[0136] - the section with the smallest diameter of the inner wall 72i is flush with the radial openings 60; and

[0137] - the inner wall 72i radially encloses part of the external thread of the second rod 32, formed in the second part 48 of the second rod. As for the end piece 68, it is in the form of a closing element fixed to the second end 31b of the first rod 31 in the example of Figures 2 to 6. It will be described below as a plug-in element on the first rod, but it can be made integral with it without going beyond the scope of the invention.

[0138] In the example of Figures 2 to 6, the extension piece 68 comprises a functional part 74 and a fastening part 76, which are rigidly connected to one another. The fastening part 76 is in the form of a screw 78 that engages a threaded blind hole 79 formed in the first rod 31 and opening in the region of the second end 31b. However, it should be noted that the invention is not limited to this morphology of the fastening part 76 and the first rod 31, as long as coupling of these elements is possible.

[0139] The functional part 74 extends longitudinally the first rod 31 in the direction S1. The functional part 74 is a rotary part with a longitudinal axis centered on the axis AX1, formed by the assembly of two truncated cones with a large common base, including:

[0140] - a first truncated cone 80 extending in the direction S1 from a small base 74a, which extends the fastening part 76, to a large base 81, which is marked with dots;

[0141] - a second truncated cone 82 extending in the direction S1 from the large base 81, which is common to the first truncated cone 80, to a small base 74b.

[0142] The respective small bases 74a, 74b of the first and second truncated cones 80, 82 correspond to lateral boundary surfaces of the functional part 74 of the extension piece 68.

[0143] As for the dimensioning of the extension piece 68, it is radially designed to extend inside the second rod 32 without friction against the inner walls of the second and third parts 48, 50. This aspect makes it possible not to impede the translation of the second rod 32 along the first rod 31. In practice, the large base 81, in the region of which the cross-section of the functional part 74 of the extension piece is largest, has a smaller diameter than the inner diameter of the second and third parts 48, 50 of the second rod 32, in order to meet this requirement.

[0144] Furthermore, the small base 74a, which is oriented toward the second end 31b of the first rod 31, has a diameter larger than the diameter of the so-called "head" circle, measured at the apex of the threads of the internal thread formed in the region of the first part 46 of the second rod 32. In this arrangement, the extension piece 68 thus forms a longitudinal stop that prevents the second rod 32 from translating along the first rod 31 in the direction S1 beyond a certain advance level. Since the position of the second rod 32 determines the relative position of the first section 20 of the arm 16 with respect to the column body 14, it can be understood that the extension piece 68 advantageously provides a longitudinal retention function for the first section 20 in the direction S1 and prevents it from extending beyond a permissible stroke length.In other words, the fully extended state of the first portion 20 of the arm 16 corresponds to engagement of the extension piece 68, more precisely its functional part 74, with the internal thread of the second rod 32.

[0145] The dimensioning of the extension piece 68 is also determined by the position of the openings 60 and the size of the balls 62.

[0146] On the one hand, the functional part 74 has a defined longitudinal extension, so that in the fully extended state of the first section 20, as shown in Figures 3 and 4:

[0147] - the large base 8 is located upstream of the openings 60 in the direction S1; and

[0148] - the openings 60 are radially aligned with the second truncated cone 82.

[0149] On the other hand, the functional part 74 has a defined radial extension so that:

[0150] - the diameter of the balls 62 is greater than the measured radial distance between the large base 81 and the portion with the smallest diameter of the inner wall 72i of the ring 64; and

[0151] - the balls 62 can be contained in the radial space defined between the second truncated cone 82 and the portion of smallest diameter of the inner wall 72i of the ring 64 in the fully extended state of the first portion 20 of the arm 16. In other words, the so-called opening angle of the second truncated cone 82 is small enough to allow it to stay away from the balls 62 in their radial alignment when the ring is in the blocking position, thus not compromising the proper functioning of the system 68.

[0152] In view of the above, when the first section 20 is in the fully extended state and the spring 66 is not loaded, translation of the second rod 32 in the direction opposite to the direction S1 is not possible because:

[0153] - the ring 64 is held by the spring 66 in a position in which its smallest diameter portion is radially aligned over the radial openings 60; while

[0154] - the diameter of the balls is greater than the measured radial distance between the large base 81 and the portion with the smallest diameter of the inner wall 72i of the ring 64.

[0155] As can be understood, in the blocking position, the ring 64 counteracts the radial displacement of the balls 62, which is necessary to allow a translation of the second rod 32, which requires a transition of the large base 81 into the radial alignment of the openings 60.

[0156] Since, from a kinematic point of view, the second rod 32 cannot move in translation in the situation in which the first section 20 is fully extended, it follows that a pure rotation of the second rod 32 is imposed by the degree of freedom restriction system 38 when the first rod 31 is driven by the electric motor 27.

[0157] Thus, a comfort adjustment of the steering wheel can be made by changing the position of the nut 34 along the second rod 32 in order to drive only the second section 22 of the arm 16 in longitudinal displacement when the first section 20 is extended.

[0158] During this comfort setting, the stroke of the nut 34 along the second rod 32, designated C in Figure 3, is limited between two positions:

[0159] - an extreme position denoted by D, which corresponds to the position of the nut 34 advanced furthest in the direction S1 and characterises the fully extended state of the arm 16, namely a fully extended state of the first and second sections 20, 22;

[0160] - an intermediate position designated I, corresponding to a state of the arm 16 in which the first section 20 is fully extended while the second section 22 is fully retracted.

[0161] The second rod 32 is expediently designed such that the nut 34 cannot translate beyond the intermediate position I in the direction opposite to S1. For this purpose, a clearance groove 86 is advantageously formed on the second rod 32 between its external thread and the openings 60, so that the nut 34 rests against the flank of the groove 86 in the intermediate position I.

[0162] With reference to Figures 5 and 6, the kinematics of the transition from a comfort setting to an ergonomic setting of the arm 16 when retracting the nut 64 is explained.

[0163] When the steering wheel is retracted during the comfort setting, the nut 34 translates along the second rod 32 toward the intermediate position I in the direction opposite to S1 in response to pure rotation of the second rod 32. Before the nut 34 reaches its intermediate position I, it comes into contact with the ring 64, which is held in the blocking position by the spring 66. Since the first rod 31 is still driven in rotation by the motor, the nut 34 continues to move toward the intermediate position I, driving the ring 64 with it in its movement, which in the process compresses the spring 66. By displacing the ring 64 in the direction opposite to the stress on the spring 66, the measured radial gap between the outer wall of the second rod 32 and the inner wall 70i of the ring 64 increases as the nut 34 approaches the intermediate position I.Due to the expanded nature of the ring on the radial inner wall 70i, the balls 62 are able to move radially outwards until they no longer form an obstacle to the extension piece 68: the second rod 32 is free to translate on the first rod 31.

[0164] When the steering wheel is retracted, the nut 34 reaching the intermediate position I results in:

[0165] - rotation of the second rod 32 is no longer possible since the nut 34 is at the end of the displacement stroke along the second rod 32; and

[0166] - a translation of the second rod 32 is permitted by the selective restriction system 38.

[0167] The transition between pure rotation and pure translation of the second rod 32 has been explained as being relevant to a punctual event characterized by the nut 34 reaching the intermediate position I during retraction of the arm 16. In practice, the transition is progressive: when the ring 64 is displaced by the nut 34 in the direction opposite to the extension direction S1, the second rod 32 assumes a behavior that combines small rotational and translational displacements. For a better understanding, a sequential division of the movement is considered. When the ring 64 is displaced by the nut 34 in response to a rotation of the second rod 32, it radially frees up space for the balls 62.The space freed up for the balls allows the second rod 32 to move in translation in a direction opposite to direction S1, causing the balls to be pushed radially outward by the second truncated cone 82, which forms a ramp. The translation ends as soon as the balls 62 are clamped between the second truncated cone 82 and the inner wall 70i of the ring. The sequence of displacement of the ring 64 by rotation of the second rod 32, followed by translation of the second rod, occurs in a cyclical and continuous manner until the nut 34 reaches the intermediate position I. In the position illustrated in detail in Figure 5, the inner wall 70i of the ring 64 is quite far from the second rod 32, so that the large base 81 of the end piece 68 can maintain radial alignment of the balls 62.

[0168] Once the nut 34 is in the intermediate position I, the steering wheel continues to retract due to the translation of the second rod 32 in response to the rotation of the first rod 31 by the electric motor 27 in the direction opposite to S1. The second rod 32 drives the nut 34 in translation from the intermediate position I to an extreme position designated R, which corresponds to the position of the nut 34 furthest back in direction S1. It should be noted that the spring 66 and the ring 64 follow the translational movement of the second rod 32 along the first rod 31. In particular, the spring 66 is kept compressed by the nut 34.

[0169] The position R of the nut 34 indicates the fully retracted state of the arm 16, namely a fully retracted state of the first and second sections 20, 22. As can be understood, the translation of the second rod 32 from the intermediate position I to the position R corresponds to a retraction of the arm 16 by the electromechanical actuator 28 in ergonomic setting, designated by E.

[0170] Advantageously, the fully retracted state of the arm 16 corresponds to a stop of the first end 32a of the second rod 32 against the shoulder 44 that delimits the external thread of the first rod 31, as shown in Figure 6. It should be noted that the invention is not limited to the formation of such a shoulder 44, and the fully retracted state of the arm 16 can be characterized by the stop of the second rod 32 against another surface provided for this purpose. In other words, the formation of the shoulder 44 on the first rod 31 is not mandatory and can be replaced by another element forming a stop along the stroke of the second rod 32.

[0171] The kinematics of the actuation of the arm 16 in the case of retraction have been described on the basis of Figures 3 to 6. Considering the arm 16 in the fully retracted state, its extension consists in rotating the first rod 31 by the electric motor 27 in the opposite direction to that used for retraction.

[0172] It is desirable that the extension of the arm 16 begins with a displacement in one piece of the first and second sections 20, 22 with respect to the column body 14, as defined for the ergonomic setting E, until it ends in the fully extended state of the second section 22.

[0173] However, as long as the first section 20 is not fully extended, the second rod 32 is free to simultaneously translate along the first rod 31 and rotate along its axis in response to rotation of the electric motor 27. In fact, the second rod 32 is:

[0174] - free to rotate about its axis, since a translation of the nut 34 in direction S1 along the second rod 32 from its intermediate position I to its extended position D is permitted; and

[0175] - free to translate according to S1 along the first rod 31 as long as the small base 74a of the extension piece 68 does not rest on the second rod 32.

[0176] As can be understood, as long as the first section 20 of the arm 16 is not in the fully extended position, the selective restriction system 38, as described in its first variant, does not interact with the second rod 32 to impose a particular behavior on it.

[0177] However, this particular feature is ineffective within the context of this first embodiment. Indeed, when arm 16 is extended, the invention takes advantage of the difference in the diameters of the rods 31, 32 and the differentiation of the thread pitches, which naturally prioritize pure translation of the second rod 32 over pure rotation of the second rod 32. In practice, to displace a driven element in translation in response to rotation of a driving element by thread complementarity, it is necessary to exert a sufficient torque to overcome a frictional moment present at their interface.

[0178] In general, the frictional moment is inversely proportional to a so-called lead angle, denoted by a, which is a function of the diameter d and the thread pitch p according to the expression:

[0179] Considering the above, the larger the pitch and the smaller the diameter, the larger the pitch angle α. In other words, the larger the diameter and the smaller the thread pitch, the higher the frictional torque.

[0180] Since the interface between the second rod 32 and the nut 34 is characterized by a larger diameter and a smaller thread pitch than at the interface between the first and second rods 31, 32, the frictional moment to be overcome is greater at the interface between the second rod 32 and the nut 34. This means that the displacement of the second rod 32 along the first rod requires less torque to be exerted than the displacement of the nut 34 along the second rod 32.

[0181] As a result, driving the first rod 31 by the electric motor 27 naturally causes the second rod 32 to translate first according to S1 in the event of extension of the arm 16.

[0182] In view of the above, the extension of the arm 16 from its fully retracted state begins with a pure translation of the second rod 32 in the direction S1. The balls 62, the ring 64, and the spring 66 of the system are also driven by the second rod 32 in translation in a single overall movement.

[0183] At the end of the stroke of the second rod 32 along the first rod 31, which is characterized by a stop of the extension piece 68 against the second rod 32, the nut 34 is arranged in its intermediate position I. The rotation of the first rod 31 by the electric motor 27 results in a translation of the nut 34 in the direction S1 and thus an extension of the second section 22 of the arm 16.

[0184] During its translation, the nut 34 moves away from its intermediate position I. The spring 66, attempting to regain its unloaded shape, simultaneously pushes the ring 64 against the nut 34 until it reaches the blocking position, namely the position where its smallest diameter portion is radially aligned with the radial openings 60. This causes the translation of the second rod 32 to be locked by the interaction of the balls 62 with the end piece 68 until the next retraction of the arm 16 during ergonomic adjustment of the steering wheel E.

[0185] With reference to Figures 3 to 6, the system 38 for selectively restricting a degree of freedom has been described. This system ensures translational locking of the second rod 32, thereby causing a rotational coupling of the first and second rods 31, 32 to move the second portion 22 in isolation when the steering wheel is in a comfort position. As can be understood, the system 38 makes it possible to indirectly force pure rotation of the second rod 32 by inhibiting its pure translation.

[0186] However, the system 38 for selectively restricting a degree of freedom is not restricted in its form to achieve the same result.

[0187] Alternatively, this system 38 can directly restrict the second rod 32 to rotating only about its axis, i.e., without requiring any locking of its translation. This feature is made possible by the second embodiment of the system shown in Figure 7, which forces a direct rotational coupling of the first and second rods 31, 32.

[0188] In this second variant, the system 38 has essentially the same elements as in the first variant, namely:

[0189] - radial openings 60 formed continuously in the second rod 32;

[0190] - balls 62, each arranged in a corresponding radial opening 60;

[0191] - a ring 64 radially surrounding the second rod 32;

[0192] - a spring 66 arranged between the ring 64 and the radial projection 56 of the second rod 32; and

[0193] - an extension piece 68.

[0194] The locations of the components of the system 38, as defined with respect to the rods 31, 32 and the nut 34, of the motion converter assembly 30 described on the basis of Figures 3 to 6 remain unchanged in this second variant.

[0195] The difference between the first and second embodiments of the system 38 lies in the shape of the end piece 68, which is designed to connect the first and second rods in a rotationally fixed manner when it interacts with the balls 62 blocked by the ring 64 in the blocking position.

[0196] As can be seen in detail in Figure 7, the end piece 68 of the system 38 according to this second variant is in the form of a bushing which is rigidly mounted around the first rod 31 in the region of its second end 31b.

[0197] Notches 88 are formed on the circumference of the extension piece 68. The notches 88 extend longitudinally along part of the extension piece 68 and are designed to be radially aligned with an opening 60 when the ring 64 is in the locked position by the spring 66. The aim is to have a number of notches 88 that is at least equal to or greater than the number of openings 60 and the associated balls 62. In fact, it is a question of providing at least one notch per ball 62, since otherwise it will not work, while providing more notches than balls 62 allows several angular positions of the extension piece 68, allowing the balls to engage in the notches 88. It is understood that increasing the number of notches 88 thus adds a functional safety component.

[0198] In detail, the endpiece corresponds to a longitudinal tube whose outer surface, with an initial completely circular cross-section designated c1, is hollowed out inwardly according to a circular arc profile to form the notches 88. In longitudinal section, the notches 88 can be connected tangentially to form an inscribed circle, designated c2, centered on the axis AX1.

[0199] The dimensioning of the extension piece 68 and the actuation kinematics of the arm 16 by the electromechanical actuator 26 equipped with the system 38 according to the second variant are described below with respect to the positioning of the nut 34 and thus its interaction with the ring 64 and the spring 66, as illustrated in Figures 3 to 6.

[0200] The extension piece 68 is dimensioned radially such that:

[0201] - in the blocking position of the ring 64, the distance defined between the inscribed circle c2 and the inner wall 70i is substantially of the same dimension as the balls 62;

[0202] - in the intermediate position I of the nut, the distance radially defined between the circular cross-section c1 and the inner wall 70i of the ring 64 is at least equal to or greater than the dimension of the balls 62.

[0203] On this basis, it is understandable that the system 38:

[0204] - creates a coupling effect in rotation of the first and second rods 31, 32 when the ring 64 is in the blocking position, since the balls 62 are not allowed by the ring 64 to come out of the notches 88;

[0205] - allows a rotational decoupling of the first and second rods 31, provided that the balls 62 can be released from the notches 88, which occurs in the intermediate position of the nut 34.

[0206] It should be noted that the section c1 on the circumference of the extension piece 68 has a diameter that is larger than the diameter of the tip circle measured at the tip of the threads of the internal thread of the second rod 32. Analogously to the side wall of the functional part 74 of the extension piece 68 according to the first embodiment, the extension piece according to the second embodiment thus ensures the longitudinal retention of the first section 20 of the arm 16 in the direction S1. The fully extended state of the first section 20 of the arm 20 corresponds to the longitudinal section of the extension piece 68 being in contact with the internal thread of the second rod 32.

[0207] Starting from an extended state of the arm 16, a rotation of the first rod 31 by the electric motor 27 in order to retract it necessarily leads to a pure rotation of the second rod 32, as long as the nut 34 is not in the intermediate position I.

[0208] As a result, retraction of the arm 16 begins with retraction of the second section 22 of the arm by the nut 34 in the direction opposite to the direction S1 in response to the rotation of the second rod 32 connected to the first rod 31 by the restriction system 38. In the same way as in the first embodiment of the system 38, the nut 34 comes into contact with the ring 64, which is held in the blocking position by the spring 66. Since the first rod 31 is still driven in rotation by the electric motor 27, the nut 34 continues to move toward the intermediate position I, driving the ring 64 along in its movement.

[0209] By displacing the ring 64, the measured radial gap between the outer wall of the second rod 32 and the inner wall 70i of the ring 64 increases as the nut 34 approaches the intermediate position I. Due to the expanded nature of the ring 64 at the radial inner wall 70i, a radial outward displacement of the balls 62 is enabled. In practice, the balls 62 slide along the profile of the notches 88 until they leave the notches 88 once the nut 34 has reached the intermediate position I.

[0210] At this stage, translation of the second rod 32 is thus possible, while the nut 34 has reached the end of its stroke along the second rod 32, indicating the fully retracted state of the second section 22. Pure translation of the second rod 32 is initiated by screwing it along the first rod 31 in the opposite direction S1. The nut 34 and the clamp 54 are carried in translation by the second rod 32, which results in the first and second sections 20, 22, which are firmly connected to the clamp 54 and the nut 34, being displaced together in translation. The second rod 32 continues to translate along the first rod 31 until it rests against the shoulder 44, indicating the fully retracted state of the first section 20 of the arm. The nut 34 is then in the position designated R.

[0211] The extension of the arm 16 by the electromechanical actuator equipped with the system 38 according to the second variant follows the same logic as in the case where the electromechanical actuator is equipped with the system 38 according to the first variant. The difference in the diameters of the rods 31, 32 and the differentiation of the thread pitches naturally prioritize pure translation of the second rod 32 over pure rotation of the second rod 32.

[0212] From a fully retracted state, the extension of the arm 16 thus begins with a joint extension of the first and second sections 20, 22 in the direction S1 by the pure translation of the second rod 32, which drives the clamp 54 and the nut 34. Reaching the first section 20 of its fully extended state with respect to the column body 14 corresponds to the transition of the nut to the intermediate position I.

[0213] In the intermediate position of the nut 34, the extension piece 68 rests against the internal thread of the second rod 32, establishing a stopping point for the translation of the second rod 32: the first section 20 is in the fully extended state. Then, a behavioral transition of the second rod 32 occurs, which begins to rotate about its axis in response to the continuous rotation of the first rod 31 by the electric motor 27.

[0214] During its translation along the second rod 32 in direction S1, the nut 34 allows the longitudinal displacement of the ring 64, which is gradually returned to its locking position by the spring 66, resulting in the balls being returned to the corresponding notches 88 of the end piece 68. This results in the second rod 32 being restricted to assume pure rotation until the next retraction of the arm 16 during ergonomic adjustment of the steering wheel E.

[0215] In view of the above, the degree of freedom restriction system 38 allows to restrict the movement of the second rod 32 to pure rotation:

[0216] - indirectly by blocking the translation according to the first embodiment; or

[0217] - directly by forcing a rotary coupling with the first rod 31 in the second variant.

[0218] It should be noted that the invention is not limited to the shape of the extension piece 68 of the different described variants of the restriction system 38 equipping the steering column assembly according to the first embodiment, provided that it:

[0219] - allows a connection to the first pole;

[0220] - defines a longitudinal stop surface of the second rod; and

[0221] - a translational blocking of the second rod or a rotational coupling of the rods is ensured by cooperation with the balls 62.

[0222] By way of example, the end piece 68 according to the second variant is not limited to a socket shape allowing engagement of the first rod 31 within its interior. An arrangement in which the end piece 68 according to the second variant is a solid body comprising a fastening part 76 as described in the first variant for cooperating with a threaded blind hole 79 formed in the first rod 31 can be envisaged. Conversely, the end piece 68 according to the first variant can be a hollow body allowing engagement of the first rod 31 within its interior to ensure their assembly. Nor is the end piece 68 limited to an element attached to the first rod 31, which can be an integral part of the first rod 31.Whether the extension piece 68 is joined to the first rod 31 or whether they are manufactured as a single piece depends on the challenges of assembling the elements of the electromechanical actuator 26. The invention is also not limited to the use of balls 62. In practice, they can be replaced by any element radially displaceable within the openings 60 to interact with the extension piece 68. As a non-limiting example, the balls can be replaced by pins.

[0223] Furthermore, the extension of the telescopic arm 16 according to the first embodiment by the electromechanical actuator 26 has been described on the basis of Figures 3 to 7 in such a way that no intervention of the restriction system 38 is required. Indeed, this arrangement benefits from a pure translation of the second rod 32, which, due to the dimensioning of the rods 31, 32 and the differentiation of the thread pitches, naturally takes precedence over its pure rotation.

[0224] However, it may be proposed to extend the constraint system 38 to force translation of the second rod 32 as long as the first section is not fully extended during an arm extension phase. This feature makes it possible to increase the reliability of the electromechanical actuator 26.

[0225] The motion converter 30 has been described as including the nut 34 and the bearing 36, which are respectively connected to the second section 22 and the first section 20 to condition their longitudinal advancement state.

[0226] In practice, the motion converter 30 can be dispensed with such a bearing 36. For example, the bearing 36 can be replaced by a system that connects the first and second sections 20, 22 in translational ergonomic settings. In this regard, a system can be considered that consists of a first element mounted on the first section 20 and a second element mounted on the second section 22, these elements:

[0227] - lockable in ergonomic setting; and

[0228] - can be separated into comfort settings.

[0229] Finally, it should be noted that the electromechanical actuator 26 according to the invention is not limited to the actuation of a telescopic arm 16 formed from several sections as in the example of Figures 1 and 2.

[0230] With reference to Figures 8 and 9, the steering column assembly 10 according to a second embodiment differs from the first form in that it is provided with a unitary arm 16, namely formed from a single section, which is retractable between fully retracted and extended positions with respect to the column body 14

[0231] In this example, the shaft 16 is slidably mounted in a bore formed in the column body 14. Furthermore, the column assembly 10 is equipped with the electromechanical actuator 26, whose restriction system 38 corresponds to its second variant described with reference to Figure 7. It should be noted that the use of the restriction system 38 according to its first variant is also possible.

[0232] In this embodiment, the nut 34 is attached to the arm 16 and forms the only interface element between the motion converter 30 and the arm 16. As a result, the position of the nut 34 completely determines the relative position of the arm 16 with respect to the column body 14.

[0233] In this example, the extension / retraction kinematics of the arm 16 follows the same logic as that described on the basis of Figure 7, with the difference that it is the same section that is displaced at two different speeds, and not two sections that are displaced at different speeds as in the first form.

[0234] In general, the idea underlying the invention is to enable the extension / retraction of an arm 16 of a vehicle steering column at different speeds by means of a single actuator 26. In the above description, the electromechanical actuator 26 and, in particular, its motion converter 30 have been defined to control the arm 16 in such a way that:

[0235] - the so-called comfort adjustment of the steering wheel is caused by the displacement of the nut 34 along the second rod 32; and

[0236] - the so-called ergonomic adjustment of the steering wheel is caused by a translation of the second rod 32 along the first rod 31.

[0237] As can be understood, the invention is not limited to the definition of the rods 31, 32 and the nut 34, in particular their thread, or even of the restriction system 38 to achieve this particular task.

[0238] In practice, a reverse arrangement can be considered, in which the comfort adjustment is caused by the translation of the second rod 32 along the first rod 31, while the ergonomic adjustment is caused by the displacement of the nut 34 along the second rod 32.

[0239] In this regard, it is a matter of defining the thread pitch ratio of the rods 31, 32 and the nut 34, as well as conditioning the constraint system 38 to constrain the behavior of the second rod 32 according to a logic that is inverse to that described on the basis of Figures 1 to 9.

[0240] In particular, the thread pitch defining the interaction between the first and second rods 31, 32 must in this case be made smaller than the thread pitch defining the interaction between the second rod 32 and the nut 34.

[0241] On the other hand, the restriction system 38 can be conversely conditioned to restrict the movement of the second rod 32 to:

[0242] - a pure translation along the first rod 31 in case of a comfort setting; and

[0243] - a pure rotation causing an independent displacement of the nut 34 along the second rod 32 in an ergonomic adjustment.

Claims

Patent claims 1 . Steering column assembly (10) of a steering system with steering wheel for a vehicle, for example a motor vehicle, comprising: - a column body (14) intended to be mounted on a vehicle structure; - an arm (16) carried by the column body (14) and extending in a longitudinal direction (AX), the arm (16) being mounted retractably in longitudinal translation between a retracted and an extended advance state with respect to the column body (14), the advance state of the arm determining the position of the steering wheel of the steering system; - an electromechanical actuator (26) for translating the arm (16) at different speeds, the electromechanical actuator (26) comprising: -- an electric motor (27) for driving in rotation; -- a motion converter assembly (30) for converting a rotation provided by the electric motor (27) into a translation of the arm (16), the motion converter (30) comprising: — a nut (34) which is non-rotatably attached to the arm (16), the nut (34) having a thread; — a first rod (31) extending along a rod axis (AX1) of longitudinal extension, the first rod (31) being fixed in translation along its axis and rotatable about its axis by being set in rotation by the electric motor (27), the first rod (31) being threaded; — a second rod (32) extending longitudinally along a respective rod axis with longitudinal extension concentric with the first rod (31), the second rod (32) being rotatable about its axis and movable in translation along its axis, the second rod (32) having a first thread which is compatible with the thread of the first rod (31) and has a second thread which cooperates with the thread of the nut (34); -- a system (38) for selectively restricting the degree of freedom of the second rod (32), which selectively and depending on the position of the nut (36) along the second rod (32): - only allows rotation of the second rod (32) about its axis in order to move the arm by screwing / unscrewing the nut (34) along the second thread of the second rod (32) when the first rod is rotated by the electric motor (27); - only allows translation of the second rod (32) along its axis to displace the arm (16) by translation of the second rod (32) carrying the nut (34), by screwing / unscrewing the second rod (32) along the first rod (31) by threaded engagement; wherein the threaded engagement between the first and second rods (31, 32) is defined with a thread pitch that is different from a defined thread pitch for the threaded engagement between the second rod (32) and the nut (34). Steering column assembly (10) according to claim 1, wherein: - the thread of the nut (34) is an internal thread; - the thread of the first rod (31) is an external thread, the first rod (31) having a first rod body which is delimited by an outer wall on which the thread is formed; - the second rod (32) has a second hollow rod body, the thickness of which is simultaneously limited by: -- an outer wall on which the second thread is formed, which is an external thread cooperating with the thread of the nut (34), the nut being carried by the second rod body; -- an inner wall on which the first thread is formed, which is an internal thread cooperating with the thread of the first rod (31), wherein the second rod body at least partially radially encloses the first rod body The steering column assembly (10) according to claim 2, wherein the threaded engagement between the first and second rods (31, 32) is defined with a larger thread pitch value than the thread pitch defining the threaded engagement between the second rod (32) and the nut (34). The steering column assembly (10) according to claim 2 or 3, wherein the system (38) for selectively restricting the degree of freedom comprises: - radial openings (60) formed continuously in the second rod (32) in the region of a longitudinal section thereof, the openings (60) connecting the outer and inner walls of the second rod (32) while extending at a distance from the second thread; - balls (62) each arranged in one of the individual radial openings (60), the balls (60) having a diameter greater than the thickness of the second rod (32) in order to project radially beyond the corresponding opening (60); - a ring (64) radially surrounding the second rod (32) while being movable in longitudinal translation, the ring (64) having a sufficient longitudinal extent to simultaneously radially surround the openings (60) and a part of the second thread of the second rod (32), the ring having an inner wall (72i) opposite the second rod (32) which widens from a portion of smaller diameter arranged flush with the second rod; - a spring (66) which passively holds the ring (64) in a blocking position for which: - the smaller diameter portion of the inner wall (72i) of the ring (60) is flush with the radial openings (60), and - the inner wall (72i) radially encloses part of the external thread of the second rod (32); - an end piece (68) which extends the first rod (31) into the second rod (32) and which defines a longitudinal stop surface against which the second rod (32) bears in a distal position with respect to the first rod (31), the end piece (68) being adapted to cooperate, in the distal position of the second rod (32), with the balls (62) which are pressed against it by the ring (60) in the blocking position; wherein the nut (34) is adapted to release the ring (60) from its locking position by pressing against the spring (66) in translation in response to rotation of the second rod (32) along the second threaded portion radially enclosed by the ring (64) in the locking position, the release of the ring (64) causing an increase in the measured distance between the inner wall (72i) of the ring (64) and the openings (60) to allow the balls (62) to move radially away from the extension (38). Steering column assembly (10) according to claim 4, wherein the extension (68) cooperates with the balls (62) when the ring (64) is in the locking position and the second rod (62) bears against the extension (68) in the distal position to block translation of the second rod (68).A steering column assembly (10) according to claim 5, wherein the extension piece (68) comprises a frusto-conical portion (82) defined longitudinally by a large base (81) and a small base (74b), the large base (81) being closer to the first rod (31) than the small base (74b), the frusto-conical portion (82) being sized such that:. - the diameter of the balls (62) is greater than the measured radial distance between the large base (81) and the smallest diameter portion of the inner wall (72i) of the ring (64); and - a translation of the second rod (32) from its distal position causes a transition of the openings (60) into radial alignment of the large base (81); and wherein the loosening of the ring (64) by the nut (64) causes an increase in the measured radial distance between the inner wall (72i) and the large base (81) until it is greater than the diameter of the balls (62). Steering column assembly (10) according to claim 4, wherein the extension piece (68) cooperates with the balls (62) when the ring (64) is in the blocking position and the second rod (32) is in the distal position on the extension piece (68) to force a rotational coupling of the first and second rods (31, 32). Steering column assembly (10) according to claim 7, wherein the extension piece (68) is defined by an outer wall provided with notches (88) extending longitudinally in a circular arc-shaped profile, the number of notches (88) being equal to or greater than the number of openings (60) and associated balls (62), the extension piece (68) being dimensioned such that the balls (62) are pressed into the notches (88) in the blocking position of the ring (64) and in the distal position of the second rod (62); and in which the loosening of the ring (64) by the nut (34) causes an increase in the measured radial distance between the inner wall (72i) and the extension piece (68) until it is greater than the diameter of the balls (62) to allow them to leave the notches (88).A steering column assembly (10) according to any preceding claim, wherein the arm (16) is telescopic in nature being formed from a plurality of sections movable relative to one another in translation, including:. - a first longitudinally extending portion (20) supported by the column body (14) while being movable in longitudinal translation relative to the column body (14); and - a second section (22) inserted into the first section (20) and longitudinally displaceable along the first section (20); in which the electromechanical actuator (26) further comprises a rotation guide bearing (36) enclosing the second rod (32) by being rigidly mounted in translation with the second rod (32); and wherein the bearing (36) is rigidly connected to the first section (20) and the nut (64) is rigidly connected to the second section (22).