Steering column assembly having a retractable arm and electromechanical actuator for controlling the arm

Abstract

The invention relates to a steering column assembly (10) for a steering system of a vehicle having a steering wheel, the steering column assembly comprising: a column body (14) arranged to be mounted on a vehicle structure; an arm (16) carried by the cylinder (14), the arm extending in a longitudinal direction (AX), the arm (16) being mounted in a longitudinally translatory, telescopically manner relative to the cylinder (14) in order to determine the position of the steering wheel of the steering system; an electromechanical actuator (26) in order to move the arm (16) in translation at different speeds, the electromechanical actuator having: an electric motor (27) for rotational drive; a nut (34) which is anti-torsion and is fixed on the arm; a first rod (31), which is anti-translation and can be moved in rotation about its axis, in that the first rod is placed in rotation by the electric motor (27), the first rod (31) having a thread; a second rod (32) extending concentrically with the first rod (31), the second rod being movable in rotation about its axis and movable in translation, the second rod (32) having a first thread interacting with a thread of the first rod (31) and a second thread interacting with a thread of the nut (34); a system for selectively limiting the degree of freedom of the second rod, said 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 thread interaction between the first and second rods (31, 32) is defined by a thread pitch which differs from the defined thread pitch for the thread interaction between the second rod (32) and the nut (34).

Description

Technical Field

[0001] The present invention relates to the general field of motor vehicles and in particular to an electromechanical actuator for controlling the forward movement of a telescopic steering column arm, which determines the position of the vehicle steering wheel. Background Art

[0002] The steering column is one of the components forming the vehicle's steering system. It is present in all vehicles and enables communication between the steering wheel and the wheels.

[0003] In a known manner, the steering column includes a fixed bracket rigidly mounted on an upper structural element of the vehicle, such as the chassis, and an arm that determines the position of the steering wheel by extending the fixed bracket into the passenger compartment of the vehicle in the direction of the seat on which the driver is sitting.

[0004] In practice, the distance between the steering wheel and the seat must be large enough to allow the driver to adjust easily on the seat without having to twist for this purpose. This feature mostly conflicts with the following driving positions in which the measured distance between the steering wheel and the seat is more easily restricted to allow the driver to hold the steering wheel comfortably and reliably.

[0005] To solve this problem, it has been proposed to make the arm telescopic, that is, to provide it with the ability to move in / out.

[0006] With this solution, the steering wheel can move between a stowed position and a forward position, where in the stowed position the steering wheel is far enough from the seat so as not to impede the driver's adjustment, and in the forward position the seat-steering wheel space is reduced. It should be noted that this solution is particularly meaningful for autonomous vehicle equipment, where in vehicle driving situations that do not require manual lane control, the retracted position of the arm can be adopted for comfort purposes.

[0007] To control the forward movement of the arm, it is known to provide an electromechanical actuation that allows the steering wheel to move without the driver's manual intervention. Traditionally, the electromechanical actuation is carried out with an electric motor and a screw-nut system, where the screw of the screw-nut system is put into rotation to move the nut fixed on the arm.

[0008] To meet the user's requirements, it is desirable to be able to adjust the forward movement speed of the arm as needed:

[0009] - In the case of functionally adjusting the steering wheel position, that is, when the steering wheel is moved to adapt to the driver's morphology holding the steering wheel in a driving situation, the movement speed should be moderate to ensure precise adjustment of the position;

[0010] - In the case of fully retracting the steering wheel for stowing it or, conversely, in the case of restoring the use of the steering wheel by returning it to the operating position, a higher forward movement speed value of the arm is desirable in order to limit the waiting time associated therewith.

[0011] To meet this dual condition, the use of a mature electric motor, for example a motor of the brushless type, has been proposed. This type of motor has a wide operating speed and can thus model the extension / retraction speed of the arm by changing the rotational speed of the screw. However, the integration of such a motor, especially in terms of its control system, incurs significant additional costs.

[0012] Another solution considered consists in designing the arm as telescopic, i.e. the arm is formed by segments that are inserted into one another and can move translationally relative to one another, and a plurality of actuators are provided, each of which is determined for the movement of a corresponding segment. Such an arrangement causes an increase in cost and creates complexity in distributing the control of the actuators in order to assign them the correct target values. Summary of the Invention

[0013] The object of the present invention is to provide an electromechanical actuating structure that can avoid the aforementioned drawbacks.

[0014] To this end, the subject of the present invention is a steering column assembly for a steering system of a vehicle, such as a motor vehicle, having a steering wheel, the steering column assembly comprising:

[0015] - a column that is arranged to be mounted on the vehicle structure;

[0016] - an arm carried by the column, the arm extending along a longitudinal direction, wherein the arm is mounted in a telescopic manner so as to be longitudinally translatable relative to the column between a retracted forward state and an extended forward state, wherein the forward state of the arm determines the position of the steering wheel of the steering system;

[0017] - an electromechanical actuator for translating the arm at different speeds, wherein the electromechanical actuator has the following components:

[0018] -- a motor for rotary drive;

[0019] -- a motion converter assembly for converting the rotation provided by the motor into translation of the arm, wherein the motion converter has the following components:

[0020] --- a nut that is torsionally fixed to the arm, wherein the nut has a thread;

[0021] ---A first rod, which extends along a rod axis with a longitudinal extent, wherein the first rod is translation-resistant along its axis and capable of rotational movement about its axis, by means of: the first rod being rotated by an electric motor, wherein the first rod has a thread;

[0022] ---A second rod, which extends longitudinally along a respective rod axis in a longitudinal direction concentrically with the first rod with a longitudinal extent, wherein the second rod is capable of rotational movement about its axis and capable of translational movement along its axis, wherein the second rod has a first thread that cooperates with the thread of the first rod and a second thread that cooperates with the thread of a nut;

[0023] --A system for selectively restricting the degrees of freedom of the second rod, which system selectively and depending on the position of the nut along the second rod:

[0024] ---Only allows the second rod to rotate about its axis, so that when the first rod is rotated by the electric motor, the arm is moved by screwing in / screwing out of the nut along the second thread of the second rod;

[0025] ---Only allows the second rod to translate along its axis, so that the arm is moved by the translation of the second rod carrying the nut and by screwing the second rod along the first rod in / screwing out by means of the thread cooperation;

[0026] wherein the thread cooperation between the first rod and the second rod is defined by a pitch that is different from the defined pitch for the thread cooperation between the second rod and the nut.

[0027] The invention also relates to a steering column assembly thus defined, wherein:

[0028] - The thread of the nut is an internal thread;

[0029] - The thread of the first rod is an external thread, wherein the first rod has a first rod body, which is defined by an outer wall, and the thread is constructed on the outer wall;

[0030] - The second rod has a second hollow rod body, the thickness of which is simultaneously defined by the following components:

[0031] -- An outer wall, on which the second thread is constructed, the second thread being an external thread that cooperates with the thread of the nut, wherein the nut is carried by the second rod body;

[0032] -- An inner wall, on which the first thread is constructed, the first thread being an internal thread that cooperates with the thread of the first rod, wherein the second rod body at least partially radially surrounds the first rod body.

[0033] The invention also relates to a steering column assembly thus defined, in which the thread cooperation between the first rod and the second rod is defined by a pitch value greater than the following pitch, which pitch defines the thread cooperation between the second rod and the nut.

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

[0035] - a radial opening that is continuously formed in the second rod in the region of a longitudinal section of the second rod, wherein the opening connects the outer wall and the inner wall of the second shaft and extends spaced apart from the second thread;

[0036] - balls, each of which is arranged in one of the respective radial openings, wherein the balls have a diameter greater than the thickness of the second rod so as to project radially beyond the respective openings;

[0037] - a ring that radially surrounds the second rod and is capable of longitudinal translational movement, wherein the ring has a sufficient longitudinal extent so as to simultaneously radially surround the opening and a part of the second thread of the second rod, and wherein the ring has an inner wall facing the second rod, and the inner wall expands starting from a section having a smaller diameter that is arranged flush with the second rod;

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

[0039] -- the section of the inner wall of the ring having a smaller diameter is flush with the radial opening, and

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

[0041] - an add-on that extends the first rod into the second rod and that defines a longitudinal contact surface against which the second rod abuts in a distal position relative to the first rod, wherein the add-on is adapted to cooperate with the balls in the distal position of the second rod, and the balls are pressed against the add-on by the ring in the locking position;

[0042] wherein the nut is adapted to release the ring from its locking position by translating towards the spring in response to a rotation of the second rod along the second threaded part that is radially surrounded by the ring in the locking position, and wherein the release of the ring causes an increase in the measured spacing between the inner wall of the ring and the opening so as to allow the balls to move radially away from the add-on.

[0043] The invention also relates to a steering column assembly thus defined, wherein when the ring is in the locked position and the second rod abuts against the additional part in the distal position, the additional part and the ball cooperate to lock the translation of the second rod.

[0044] The invention also relates to a steering column assembly thus defined, wherein the additional part has a frustoconical portion defined longitudinally by a large base and a small base, with the large base closer to the first rod than the small base, and the dimensions of the frustoconical portion are designed such that:

[0045] - the diameter of the ball is greater than the radial distance measured between the large base and the section of the inner wall of the ring with the smallest diameter; and

[0046] - the translation of the second rod out of its distal position causes a shift of the opening to be radially aligned with the large base;

[0047] and wherein loosening the ring by means of a nut causes an increase in the measured radial distance between the inner wall and the large base until the distance is greater than the diameter of the ball.

[0048] The invention also relates to a steering column assembly thus defined, wherein when the ring is in the locked position and the second rod abuts against the additional part in the distal position, the additional part and the ball cooperate to force the first rod and the second rod to be rotationally coupled.

[0049] The invention also relates to a steering column assembly thus defined, wherein the additional part is defined by an outer wall provided with incisions extending longitudinally in an arcuate profile, the number of incisions being equal to or greater than the number of the opening and the respective balls, and the dimensions of the additional part are designed such that the balls are pressed into the incisions in the locked position of the ring and in the distal position of the second rod;

[0050] and wherein loosening the ring by means of a nut causes an increase in the measured radial distance between the inner wall and the additional part until the distance is greater than the diameter of the ball to allow the balls to leave the incisions.

[0051] The invention also relates to a steering column assembly thus defined, wherein the arm is telescopic by being formed of a large number of segments movable relative to each other translationally, wherein:

[0052] - a first segment having a longitudinal extent, carried by the column and being longitudinally translatable relative to the column; and

[0053] - a second segment inserted into the first segment and longitudinally movable along the first segment;

[0054] The electromechanical actuator also has a rotary guide bearing which surrounds the second rod in that the rotary guide bearing is non-translatably mounted with the second rod; and

[0055] wherein the bearing is rigidly connected to the first section and the nut is rigidly connected to the second section. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Other features and advantages of the present invention will become apparent during the course of the following detailed description, which is to be read in conjunction with the accompanying drawings, in which:

[0057] - Figure 1 is a perspective view of a steering column assembly according to a first embodiment of the present invention, the steering column assembly having a steering column body, a telescopic arm carried by the steering column body, and an electromechanical actuator for moving the telescopic arm in / out.

[0058] - Figure 2 is Figure 1 a sectional view of the steering column assembly in, the steering column assembly having an electromechanical actuator according to a first embodiment variant;

[0059] - Figure 3 is Figure 2 a partial view of, showing the electromechanical actuator for moving the telescopic arm in / out according to the first embodiment variant in an operating state for performing a comfort adjustment of the steering wheel;

[0060] - Figure 4 is a detailed view of the device for selectively restricting degrees of freedom in the operating state of the electromechanical actuator in Figure 3 the steering wheel comfort adjustment;

[0061] - Figure 5 is Figure 3 a view corresponding to in an operating state for an ergonomic adjustment of the steering wheel;

[0062] - Figure 6 is a detailed view of the device for selectively restricting degrees of freedom in the operating state of the electromechanical actuator for performing Figure 5 the steering wheel ergonomic adjustment in;

[0063] - Figure 7 is a perspective and partially cut-away view of the electromechanical actuator for moving the telescopic arm in / out according to a second embodiment variant;

[0064] - Figure 8FIG. [0] is a perspective view of a cross-section of a steering column assembly according to a second embodiment of the present invention, the steering column assembly having a steering column body, a sliding arm carried by the steering column body, and an electromechanical actuator for moving the arm in / out according to a second implementation variant, the perspective view showing the fully extended state of the arm;

[0065] - Figure 9 is according to Figure 8 of the steering column assembly of the cross-sectional perspective view, which shows the fully retracted state of the arm. DETAILED DESCRIPTION

[0066] In the following description, the same, similar or analogous elements are denoted by the same reference numerals.

[0067] As can be seen in Figure 1 and 2 shows a steering column assembly 10 for a vehicle steering system according to a first embodiment of the present invention. The assembly 10 includes a frame 12, a column 14 carried by the frame 12, and an arm 16 carried by the column 14, wherein the frame is adapted to be rigidly fixed to an element of the vehicle superstructure, such as the chassis.

[0068] The column assembly 10 further includes a steering shaft 18 which extends longitudinally along an axis AX. The arm 16, which also has a longitudinal extent, radially surrounds the steering shaft 18. The "radial direction" means the direction extending along an axis AY which extends orthogonally to the axis AX.

[0069] The steering shaft 18 is arranged to be torsionally rigidly coupled to a vehicle steering wheel (not shown). More precisely, the steering shaft 18 includes a free end 18a which projects beyond the arm 16 in the longitudinal direction in order to receive the vehicle steering wheel by adjustment (Einpassen).

[0070] Within the scope of the present invention, the steering column assembly 10 is arranged to effect an adjustment of the longitudinal position of the steering wheel in the passenger compartment of a vehicle equipped with the steering column assembly. In this regard, the arm 16 is provided with the ability to move out / into the column 14 in the longitudinal direction, and the steering shaft 18 is mounted non-translatably together with the arm 16.

[0071] Specifically, the arm 16 and the column 14 are configured to allow relative movement along the longitudinal direction, which in practice corresponds to the movement of the shaft 16 relative to the column 14, since the column 14 is fixedly connected to the frame 12 along the longitudinal direction, and the frame is fixed after being installed in the vehicle. It should be noted that the column 14 can be rotatably mounted relative to the frame 12 by means of the mechanism denoted by 19, so as to additionally achieve the height adjustment of the steering wheel in the passenger compartment. In this case, the column 14 always maintains the longitudinal connection with the frame 12.

[0072] In the case of the first embodiment, the arm 16 is configured telescopically, in that: the arm is formed in a combined form by the following components:

[0073] - A first segment 20, which is carried by the column 14 and can move longitudinally translatably relative to the column 14; and

[0074] - A second segment 22, which is inserted into the first segment 20 and can move longitudinally along the first segment 20.

[0075] Specifically, as Figure 1 can be seen, the first segment 20 radially surrounds the hollow cylindrical part 14a with the longitudinal extension of the column 14, so as to be able to slide along the outer side of this part. Additionally, the first segment 20 has a bore 24 oriented longitudinally, and the second segment 22 is mounted in this bore in a sliding fit. The assembly is configured such that the second segment 22 can extend inside the hollow cylindrical part 14a of the column. As can be understood, the first segment 20 extends radially outside the hollow cylindrical part 14a of the column, and the hollow cylindrical part 14a extends radially outside the second segment 22. However, it should be noted that the present invention is not limited to this particular arrangement as long as the sliding movement of the first segment 20 relative to the column 14 and the sliding movement of the second segment 22 relative to the first segment 20 are allowed.

[0076] The second segment 22 can move longitudinally between a fully inserted position and a fully retracted position along the bore 24. The fully inserted position and the fully retracted position of the second segment 22 are defined such that a greater extension of the second segment 22 in the fully inserted position than in the fully retracted position is received in the bore 24.

[0077] Similarly, the longitudinal movement of the first segment 20 between the fully inserted position and the fully retracted position is restricted. In the fully inserted position, the first segment 20 covers the hollow cylindrical section 14a of the column 14 to a greater extent than in the retracted position.

[0078] Additionally, the steering shaft 18 is also telescopic along its extent within the arm 16. The steering shaft 18 is in particular connected to the arm 16 in such a way that a retraction or extension of the arm respectively causes a retraction or extension of the steering shaft 18. Since the steering shaft 18 simultaneously bears the steering wheel and is connected anti-translationally with the movement of the arm 16, the extended state of the arm 16 determines the position of the steering wheel in the passenger compartment. In fact, the arm 16 acts like a muscle: its actuation causes a change in the longitudinal extent of the steering shaft 18 and thus the movement of the steering wheel fixedly connected to the steering shaft 18.

[0079] Overall, the longitudinal extent of the arm 16 can be adjusted between the state of complete retraction of the arm and the state of complete extension of the arm, where these positions are determined by the completely extended / retracted states of two basic segments 20, 22 of the arm 16. In fact, the completely extended state of the arm 16 corresponds to the case where the first and second segments 20, 22 are respectively in the completely extended positions, rather than corresponding to the case where the first and second segments 20, 22 are respectively in the completely retracted positions, which represents the completely retracted state of the arm 16.

[0080] Taking into account that the steering column assembly 10 is installed in the vehicle, i.e., there is a fixed frame 12 and an arm 16 extending from the frame 12 to the driver's seat, then:

[0081] - The extension of the telescopic arm 16 corresponds to the translation of the first and second segments 20, 22 along the direction denoted by S1, which causes the movement of the steering wheel borne by the steering shaft 18 towards the driver's seat; and thus

[0082] - The retraction of the arm 16 corresponds to the translation of the first and second segments 20, 22 along the direction opposite to S1, which causes the steering wheel to move away from the driver's seat.

[0083] The extension and retraction of the arm 16 relative to the column 14 are ensured by an electromechanical actuator 26 on the steering column assembly 10. The electromechanical actuator 26 has an electric motor 27 for driving rotation and a drive mechanism 28, where the electric motor is advantageously fixed to the column 14, and the drive mechanism drives the segments 20, 22 translationally in response to the rotation provided by the electric motor 27.

[0084] The concept on which the present invention is based is to provide precisely demand-coordinated control of the extension / retraction speed of the arm 16 by means of the electromechanical actuator 26, which control provides different movement speeds of the steering wheel according to the following situations:

[0085] - If the driver of the vehicle wishes to perform a so-called comfort adjustment, which consists in changing the position of the steering wheel in order to provide a good driving position, a low / moderate forward movement speed is required in order to provide precise adjustment; and

[0086] - If the driver of the vehicle wishes to perform a so-called ergonomic adjustment, which consists in either squeezing the steering wheel completely into the rest position when not in use or, conversely, restoring the use of the steering wheel by returning it from its rest position to the driver, a higher forward movement speed of the arm is desirable in order to limit the waiting time associated therewith.

[0087] In this regard, the drive mechanism 28 of the electromechanical actuator 26 includes a motion converter assembly 30, the particular structure of which ensures the conversion of the rotation provided by the electric motor 27 into an out / in movement of the arm 16 at various speeds. Within the scope of a first embodiment of the column assembly 10, the motion converter 30 advantageously takes advantage of the telescopic nature of the arm 16 by virtue of the fact that it applies a first sliding speed of the second section 22 relative to the first section 20 and a second sliding speed of the first section 20 and the second section 22 moving in the assembly movement relative to the column 14. The result of this difference in movement speeds generally gives rise to different out / in movement speeds of the arm 16.

[0088] According to the first embodiment, the motion converter assembly 30 results from the combination of:

[0089] - A first rod 31 that is only rotatable and is driven by the electric motor 27;

[0090] - A second rod 32 aligned with the first rod 31, which can rotate and translate simultaneously and which co-operates with the first rod 31 by means of a thread;

[0091] - A nut 34 that only translates and that co-operates with the second rod by means of a thread;

[0092] - A rotary guide bearing 36 for the second rod 32; and

[0093] - A system 38 for selectively restricting the degrees of freedom of the second threaded rod.

[0094] As shown in the Figures 3 to 6As can be seen in more detail, the first rod 31 extends along the rod axis AX1 with a longitudinal extent. The first rod 31 is rotated by the electric motor 27 by means of the reduction gearing 39 of the drive mechanism 28. The gearing 39 and the electric motor 27 are arranged in a housing 40 fixed to the column 14 so as to jointly form a so-called gearing motor-module. The first threaded rod 31 is prevented from translating relative to the column 14 and is advantageously held in place in the region of the reduction gearing 39.

[0095] It should be noted that, without going beyond the scope of the invention, it is possible to consider directly driving the first threaded rod 31 by the electric motor 27, that is, without a gearing.

[0096] From a structural point of view, the first rod has two ends, namely a first end and a second free end 31b, where the first end is advantageously coupled to the electric motor 31a by means of the reduction gearing 39. The first rod 31 extends from its first end 31a to its second end 31b along the removal direction S1 of the arm 16.

[0097] In particular, the first rod 31 is presented in the form of a continuous cylindrical body, which body comprises two parts, namely a first part 40 extending from the first end 31a and having a smooth periphery and a second part 42 extending from the second end 31b and provided with an external thread. The interface between the two parts, between the two ends 31a, 31b of the first rod 31, defines a shoulder denoted by 44.

[0098] "External thread" means a thread which is constructed in the outer circumferential wall of the rod body and projects outwards in a radial direction AY1 perpendicular to the rod longitudinal axis AX1.

[0099] The second rod 32 extends coaxially with the first rod 31 along a corresponding rod axis aligned with the rod axis AX1 of the first rod 31. The second rod 32 extends from the first end 32a to the second end 32b in the direction S1. The second rod 32 is presented in the form of a hollow cylindrical body, in which the first rod 31 partially extends.

[0100] As can be seen in Figure 4 and 6 in more detail, the body has three parts, which three parts form a material continuity and where the first part 46 extends from the first end 32a, the second part 48 extends from the second end 32b and the third part 50 extends as an interface between the first and second parts 46, 48. The third part 50 extends between the first end 32a and the second end 32b of the second rod 32.

[0101] 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 known as a threaded hole. An "internal thread" means a thread that is constructed in the inner wall and projects beyond the rod longitudinal axis AX1 along the radial direction AY1.

[0102] In particular, the first part 46 of the second rod 32 overlaps along its longitudinal extent with the outer wall of the second part 42 of the first rod 31. In this overlapping region, the corresponding external and internal threads of the parts 42 and 46 of the rods 31, 32 cooperate.

[0103] 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 can be smooth.

[0104] Finally, the third part 50 of the second rod 32 is radially delimited by an outer wall and an inner wall that can be smooth.

[0105] The second and third parts 48, 50 of the second rod 32 are respectively constructed with an inner diameter, i.e., a diameter measured in the region of their respective inner walls, that is greater than the outer diameter of the second part 42 of the first rod 31.

[0106] In the previous description of the bodies of the first and second rods 31, 32, the specific walls have been described such that they can be smooth. In fact, smooth surfaces are preferred for the walls because they are not positions of special interaction during the operation of the motion converter 30. However, smoothness is not restrictive.

[0107] The bearing 36 radially surrounds the first part 46 of the second rod 32 and is carried by a rigid snap ring 54 visible in Figure 1 which is fixed to the first section 20 of the arm 16. The bearing 36 radially surrounds the second rod 32, while it is also connected to the second rod 32 against longitudinal translation. In the example of the drawing, the anti-longitudinal translation retention of the bearing 36 with the second rod 32 is ensured by two contact surfaces, namely:

[0108] - A first contact surface, which is shown by a radial projection 56 that projects outward beyond the outer wall of the first part 46 of the second rod; and

[0109] - A second contact surface, which is formed by a clip 58 that is placed in a groove that is constructed in the outer wall of the first part 46 of the second rod.

[0110] As for the nut 34, it radially surrounds the second part 48 of the second rod, while it is rigidly fixed to the second section 22 of the arm 16. The nut 34 includes an internal thread, in other words a threaded hole, that cooperates with the external thread of the second part 48 of the second rod 32.

[0111] From a kinematic point of view, the second rod 32 is itself mounted with two degrees of freedom in such a way that it simultaneously has the ability to translate longitudinally and to rotate about its axis. The second rod 32 is jointly carried by the first rod 31 and the nut 34 and by the rotary guide bearing 36, where the second rod acts in concert with the first rod and the nut by means of a thread.

[0112] When the electric motor 27 is activated so as to put the first rod 31 into rotation, the interaction of the threads between the first rod 31 and the second rod 32 and between the second rod 32 and the nut 34 simultaneously serves to produce two results, namely:

[0113] - a pure rotation of the second rod 32 about its axis, which results in the nut 34 moving along the second part 48 of the second rod 32 by screwing in / screwing out of the nut. From this results the translation of the second segment 22 relative to the first segment 20 by means of the nut 34;

[0114] - a pure longitudinal translation of the second rod 22 by screwing in / screwing out of the second rod 32 onto the first rod 31 and in particular by screwing in / screwing out of the first part 46 of the second rod 32 onto the second part 42 of the first rod 31.

[0115] Such a longitudinal translation of the second rod 32 along the first rod 31 is achieved in such a way that the measured inner diameter in the region of the second and third parts 48, 50 of the second rod is greater than the outer diameter of the second part 42 of the first rod.

[0116] The translation of the second rod 32 simultaneously drives the nut 34 and the bearing 36 during its translational movement, which results in the simultaneous sliding of the first and second segments 20, 22 of the arm 16. In fact, the interaction of the threads, i.e. the shape complementarity of the internal thread of the nut 34 and the external thread of the second part 48 of the second rod 32, produces in this case a hook effect, which forces the nut 34 to translate with the second rod 32. The translation of the bearing 36 drives the translation of the first segment 20 of the arm 16, the translation of which is imposed by the fact that it is mounted anti-translationally with the second rod 32.

[0117] As can be understood, the said arrangement of the rods 31, 32, the nut 34 and the bearing 36 relative to the column 14 and the segments 20, 22 allows the first kinematic manipulation of the arm 16 caused by sliding only the second section 22 by means of the nut 34 to be distinguished from the second kinematic manipulation of the arm 16 caused by the successive sliding of the first and second segments 20, 22 by means of the nut 34 and the bearing 36.

[0118] Thus, by constructing threads with different pitches, a difference in the retracting / extending speed of the arm 16 can be generated. More precisely, by differentiating the pitch defined when the first and second rods 31, 32 act together from the pitch defined when the second rod 32 and the nut 34 act together, the moving speed of the nut 34 along the second rod now becomes different from the moving speed of the second rod 32 along the first rod 31. As a result, the sliding speed of the second segment 22 relative to the first segment 20 of the shaft is different from the common sliding of the first and second segments 20, 22 relative to the cylinder 14.

[0119] According to the first embodiment, the pitches of the first and second rods 31, 32 and the nut 34 are meaningfully defined such that the translational speed of the second segment 22 relative to the first segment 20 is less than the translational speed of the second segment 22, which in turn brings about the translation of the first segment 20 relative to the cylinder 14. As can be understood, this arrangement aims to:

[0120] - cause a so-called comfort adjustment of the steering wheel by the movement of the second segment 22 relative to the first segment 20; and

[0121] - cause a so-called ergonomic adjustment of the steering wheel by the movement of the first and second segments 20, 22 relative to the cylinder 14.

[0122] Generally, the longitudinal translational speed V, either of the second rod 32 along the first rod 31 or of the nut 34 along the second rod 32, is expressed as the product of the corresponding pitch p and the rotational speed N of the first rod 31:

[0123] V = N * p

[0124] Therefore, in order to cause a translational speed of the second segment 22 relative to the first segment 20 that is smaller than the continuous translational speed of the first and second segments 20, 22 relative to the cylinder 14, it is stipulated that the pitch defining the interaction between the first and second rods 31, 32 is greater than the pitch defining the interaction between the second rod 32 and the nut 34. In this regard, the present invention preferably, but in a non-limiting manner, stipulates that:

[0125] - the value of the pitch defining the interaction between the first and second rods 31, 32 is stipulated to be 6 mm; and

[0126] - the value of the pitch defining the interaction between the nut 34 and the second rod 32 is stipulated to be 2 mm.

[0127] In view of the foregoing, when the second rod 32 rotates purely, the translation of the second segment 22 relative to the first segment 20 can occur at a speed different from the successive translations of the first and second segments 20, 22 relative to the cylinder 14 when the second rod 32 translates purely.

[0128] Therefore, in order to ensure control of the movement speed of the steering wheel, according to the present invention, the characteristics of the second rod 32, either in pure translation or in pure rotation, are made to depend on the type of adjustment desired, i.e., comfort or ergonomics.

[0129] Within the scope of the present invention, the characteristics of the second rod 32 are obtained by forcing a system 38 for selectively restricting degrees of freedom.

[0130] Reference Figures 2 to 6 , a first embodiment of the cylinder 10 is equipped with a first variant embodiment of the system 38 for selective restriction. In the first variant, the system 38 for selective restriction is presented as a system that blocks or allows the translation of the second rod 32 depending on the position of the nut 34 along the second rod 32.

[0131] From a structural point of view, this system 38 for selective restriction, according to its first variant embodiment, results from the combination of the following components:

[0132] - Radial openings 60 formed continuously in the second rod 32;

[0133] - Balls 62, which are respectively arranged in the corresponding radial openings 60;

[0134] - A ring 64 that radially surrounds the second rod 32;

[0135] - A spring 66 arranged between the ring 64 and the radial projection 56 of the second rod 32; and

[0136] - An add-on 68 that extends the first rod in the region of the second end 31b of the first rod.

[0137] 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, i.e., transversely through the thickness of the second rod 32, by connecting the smooth outer and inner walls of the third part 50. The openings 60 are constructed in the same longitudinal plane and are evenly distributed within the circumference of the second rod.

[0138] The balls 62 each have a diameter greater than the thickness of the second rod 32, which thickness is measured in the region of the third part 50 where the opening 60 is formed. As a result of this feature, the balls 62 project radially beyond the opening 60, and the balls are arranged in the opening.

[0139] Advantageously, the opening 60 with a pointwise cross-sectional reduction is formed flush with the inner wall of the second rod 32 in order to prevent the balls 62 from coming into contact with the thread of the first rod 31 during the translation of the second rod 32. This feature makes it possible to prevent the balls from having a vibrating characteristic by following the contour of the thread, which contour may generate a perceptible knocking noise. As can be understood, this aspect allows maintaining an acoustic atmosphere in the internal space and in particular avoiding giving the user the feeling that the actuator 26 is malfunctioning.

[0140] The ring 64 surrounds the second rod 32 and is mounted in such a way that it can translate longitudinally between the radial projection 56 and the nut 34. It is delimited by two side walls 70, namely a first side wall 70a oriented opposite to the radial projection 56 and a second side wall 70b oriented opposite to the nut 34. The dimensions of the ring 64 are designed in such a way that its longitudinal extent measured between its first and second side walls 70a, 70b is sufficient to radially surround the opening 60 and a part of the external thread of the second rod 32.

[0141] Additionally, the ring has two radial walls connecting the side walls 70, namely an inner wall 72i and an outer wall 72e. The inner wall 72i of the ring 64 is oriented towards the second rod 32 and has an involute diameter in the longitudinal section. More precisely, the ring 64 is simultaneously oriented and configured to form an internal expansion along the direction S1, that is, from the first side wall 70a to the second side wall 70b. In fact, the greater the distance from the first side wall 70a along the direction S1 of the removal of the arm 16, the greater the measured spacing between the inner wall 72i of the ring 64 and the outer wall of the second rod 32. It should be noted that the inner wall 72i is flush with the second rod part 32 in the region of the first side wall 70a, that is, in the region of its section with the smallest diameter.

[0142] The spring 66 arranged between the ring 64 and the radial projection 56 radially surrounds the second rod 32. The spring is in the form of a compression coil spring, and the unloaded length of the compression coil spring corresponds to the measured spacing between the radial projection 56 and the longitudinal plane receiving the radial opening 60.

[0143] Advantageously, the spring 66 is connected to the ring 64 and the radial projection 56 in the region of its ends in order to passively hold the ring 64 in a so-called locking position, in which:

[0144] - the section of the inner wall 72i with the smallest diameter is flush with the radial opening 60; and

[0145] - The inner wall 72i radially surrounds a part of the external thread formed in the second part 48 of the second rod 32.

[0146] Regarding the add-on 68, which is presented in the form of a terminal element that is fixed at the second end 31b of the first rod 31 in the Figures 2 to 6 example. The terminal element described below is described as an element inserted onto the first rod, but it can be manufactured integrally with the first rod without going beyond the scope of the present invention.

[0147] In the Figures 2 to 6 example, the add-on 68 includes a functional part 74 and a fixing part 76 that are fixedly connected to each other. The fixing part 76 is presented in the form of a bolt 78 that is embedded in a threaded blind hole 79 that is constructed in the first rod 31 and opens into the region of the second end 31b. However, it should be noted that the present invention is not limited to this form of the fixing part 76 and the first rod 31, as long as the coupling of these elements can be achieved.

[0148] The functional part 74 extends the first rod 31 along the longitudinal direction in the direction S1. The functional part 74 is a rotating part having a longitudinal axis centered on the axis AX1, and this rotating part is formed by the composition of two frustums with a common large base, and these two frustums are:

[0149] - The first frustum 80, which extends along the direction S1 from the small base 74a that extends the fixing part 76 to the large base 81 marked by a dashed line;

[0150] - The second frustum 82, which extends along the direction S1 from the large base 81 shared with the first frustum 80 to the small base 74b.

[0151] The corresponding small bases 74a, 74b of the first and second frustums 80, 82 correspond to the lateral defining surfaces of the functional part 74 of the add-on 68.

[0152] Regarding the dimensions of the add-on 68, it is configured radially so as to be able to extend inside the second rod 32 without friction on the inner walls of the second and third parts 48, 50. This aspect allows the translation of the second rod 32 along the first rod 31 to be unaffected. In fact, the cross-section of the functional part 74 of the add-on is the largest in the region of the large base 81, and the large base 81 has a diameter smaller than the inner diameters of the second and third parts 48, 50 of the second rod 32 in order to meet this condition.

[0153] Furthermore, the small base 74a oriented in the direction of the second end portion 31b of the first rod 31 has a diameter larger than the diameter of the so-called "head" circle, which is measured at the top of the thread line of the internal thread formed in the region of the first part 46 of the second rod 32. In this arrangement, the add-on 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 specific forward movement level. Since the position of the second rod 32 causes the relative position of the first segment 20 of the arm 16 with respect to the cylinder 14, it is understandable that the add-on 68 meaningfully ensures the function of blocking in the longitudinal direction of the first segment 20 in the direction S1 and prevents movement beyond the allowed stroke length. In other words, the fully extended state of the first segment 20 of the arm 16 corresponds to the abutment of the add-on 68, more precisely its functional part 74, on the internal thread of the second rod 32.

[0154] The size of the add-on 68 also depends on the position of the opening 60 and the size of the ball 62.

[0155] On the one hand, the functional part 74 has a defined longitudinal extent such that in the fully extended state of the first segment 20, as shown in Figure 3 and 4 :

[0156] - the large base 8 is upstream of the opening 60 in the direction S1; and

[0157] - the opening 60 is radially aligned with the second frustum 82.

[0158] On the other hand, the functional part 74 has a defined radial extent such that:

[0159] - the diameter of the ball 62 is larger than the radial spacing measured between the large base 81 and the section of the inner wall 72i of the ring 64 having the smallest diameter; and

[0160] - in the fully extended state of the first section 20 of the arm 16, the ball 62 can be contained in the radial space defined between the second frustum 82 and the section of the inner wall 72i of the ring 64 having the smallest diameter. In other words, the so-called opening angle of the second frustum 82 is small enough to allow it to move away from the ball 62 in the radial orientation of the ball when the ring is in the locked position, so that the normal function of the system 68 is not affected.

[0161] In view of the above, when the first segment 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:

[0162] - The ring 64 is held in position by a spring 66 such that the section thereof having the smallest diameter is oriented radially through the radial opening 60; and

[0163] - The diameter of the ball is greater than the radial spacing measured between the large base 81 and the section of the inner wall 72i of the ring 64 having the smallest diameter.

[0164] As can be understood, in the locked position the ring 64 prevents radial movement of the ball 62, but such radial translation is required to allow translation of the second rod 32, which requires the large base 81 to turn into radial alignment with the opening 60.

[0165] Since kinematically the second rod 32 cannot move translationally when the first section 20 is fully retracted, a pure rotation of the second rod 32 is imposed by the degree-of-freedom limiting system 38 when the first rod 31 is driven by the electric motor 27.

[0166] Thus, by changing the position of the nut 34 along the second rod 32, a comfort adjustment of the steering wheel can be made so that when the first section 20 is retracted, only the second section 22 of the arm 16 is driven to move longitudinally.

[0167] During this comfort adjustment, the travel of the nut 34 along the second rod 32, denoted by C in Figure 3 is limited between the following two positions:

[0168] - A limit position denoted by D, which corresponds to the position where the nut 34 has moved forward farthest along the direction S1 and represents the fully retracted state of the arm 16, i.e., the fully retracted state of the first and second sections 20, 22;

[0169] - An intermediate position denoted by I, which corresponds to the state of the arm 16 in which the first section 20 is fully retracted while the second section 22 is fully retracted.

[0170] The second rod 32 is meaningfully configured such that the nut 34 cannot translate beyond the intermediate position I in the direction opposite to S1. Advantageously, for this purpose a free space notch 86 is formed on the second rod 32 between its external thread and the opening 60 such that the nut 34 abuts against the side edge of the notch 86 in the intermediate position I.

[0171] Refer to Figure 5 and 6 to explain the kinematics of the transition from the comfort adjustment of the arm 16 to the ergonomic adjustment when the nut 64 is retracted.

[0172] When the steering wheel is moved in during comfort adjustment, the nut 34 translates in the direction towards the intermediate position I along the second rod 32 in a direction opposite to S1 in response to the pure rotation of the second rod 32. Before the nut 34 reaches its intermediate position I, the nut abuts against the ring 64, which is held in the locked position by a spring 66. Since the first rod 31 is always still driven in rotation by the motor, the nut 34 continues to move in the direction towards the intermediate position I, where it drives the ring 64 in its movement, which compresses the spring 66 here.

[0173] By the movement of the ring 64 in a direction opposite to the loading of the spring 66, the measured radial clearance between the outer wall of the second rod 32 and the inner wall 70i of the ring 64 increases to the extent that the nut 34 approaches the intermediate position I. Due to the expansion characteristics of the ring at the radial inner wall 70i, the balls 62 can move radially outwards until they no longer form an obstacle to the attachment 68: the second rod 32 becomes free to translate on the first rod 31.

[0174] Thus, when the steering wheel is moved in, the arrival of the nut 34 at the intermediate position I results in:

[0175] - Since the nut 34 is at the end of its travel along the second rod 32, rotation of the second rod 32 is no longer possible; and

[0176] - Translation of the second rod 32 is permitted by the system 38 for selective restriction.

[0177] The transition between pure rotation and pure translation of the second rod 32 has been explained as being related to a point-like event, which is characterized by the arrival of the nut 34 at the intermediate position I when the arm 16 is moved in. In fact, the transition is gradual: when the ring 64 is moved by the nut 34 in a direction opposite to the removal direction S1, the second rod 32 takes on a characteristic of combining small rotational movements and translational movements. For better understanding, consider the sequential division of the movement. When the ring 64 is moved by the nut 34 in response to the rotation of the second rod 32, it radially releases space for the balls 62. The released space for the balls allows the second rod 32 to translate in a direction opposite to the direction S1, which results in the balls being pressed radially back outwards by the second frustum 82 that forms a ramp. Once the balls 62 are clamped between the second frustum 82 and the inner wall 70i of the ring, the translation ends. The sequence of movement of the ring 64 caused by the rotation of the second rod 32 and the subsequent translation of the second rod occur in a periodic and continuous manner until the moment when the nut 34 reaches the intermediate position I. In Figure 5 In the position shown in detail, the inner wall 70i of the ring 64 is quite far from the second rod 32, such that the large base 81 of the attachment 68 can remain radially aligned with the balls 62.

[0178] Once the nut 34 is in the intermediate position I, the translation of the second rod 32 as a reaction to the rotation of the first rod 31 caused by the electric motor 27 causes the inward movement of the steering wheel to continue in the direction opposite to S1. The second rod 32 translationally drives the nut 34 from the intermediate position I to the limit position denoted by R, which corresponds to the position of the nut 34 furthest to the rear along the 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 remains in a compressed state by the nut 34.

[0179] The position R of the nut 34 represents the fully inward movement state of the arm 16, i.e., the fully inward movement state of the first and second segments 20, 22. As can be understood, the translation of the second rod 32 from the intermediate position I to the position R corresponds to the case where the arm 16 is moved into the ergonomic adjustment denoted by E by the electromechanical actuator 28.

[0180] Advantageously, the fully inward movement state of the arm 16 corresponds to the abutment of the first end 32a of the second rod 32 against the shoulder 44, which delimits the external thread of the first rod 31, as shown in Figure 6 . It should be noted that the present invention is not limited to the formation of such a shoulder 44, and the characteristic of the fully inward movement state of the arm 16 can lie in the abutment 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 this can be replaced by another element forming a stop along the travel of the second rod 32.

[0181] The kinematics of the manipulation of the arm 16 in the case of inward movement has already been described based on Figures 3 to 6 .

[0182] Considering that the arm 16 is in the fully inward movement state, the outward movement of the arm consists in rotating the first rod 31 by the electric motor 27 in the rotational direction opposite to the rotational direction for inward movement.

[0183] It is desirable that the outward movement of the arm 16 starts with the movement of one of the first and second segments 20, 22 relative to the cylinder 14, as defined for the ergonomic adjustment E, until the outward movement ends in the fully outward movement state of the second segment 22.

[0184] However, as long as the first segment 20 is not fully moved out, the second rod 32 freely translates along the first rod 31 simultaneously and rotates about its axis as a reaction to the rotation of the electric motor 27. In fact, the second rod 32:

[0185] - freely rotates about its axis because the nut 34 is allowed to translate along the second rod 32 from its intermediate position I to its outward movement position D in the direction S1; and

[0186] - It can freely translate along the first rod 31 in accordance with S1 as long as the small base 74a of the attachment 68 does not abut against the second rod 32.

[0187] As can be understood, as long as the first segment 20 of the arm 16 is not in the fully extended position, the system 38 for selective restriction, as described in its first variant, does not interact with the second rod 32 to force it to have specific characteristics.

[0188] However, this feature is ineffective within the scope of the first embodiment. In fact, in the case where the arm 16 is extended, the present invention obtains the advantages of the arm from the difference in the diameters of the rods 31, 32 and the pitch differentiation performed, which gives priority to the pure translation of the second rod 32 over the pure rotation of the second rod 32.

[0189] In order to move the translationally driven element by means of thread complementarity in response to the rotation of the drive element, in fact, sufficient torque is applied to overcome the frictional torque present at its interface.

[0190] Generally, the frictional torque is inversely proportional to the so-called helix angle α, which is a function of the diameter d and the pitch p according to the following expression:

[0191]

[0192] Taking the foregoing into account, the larger the pitch and the smaller the diameter, the larger the helix angle α. In other words, the larger the diameter and the smaller the pitch, the larger the frictional torque.

[0193] Now, since the interface between the second rod 32 and the nut 34 is characterized by a larger diameter and a smaller pitch than the diameter and pitch at the interface between the first rod 31 and the second rod 32, the following result is produced, namely: the frictional torque to be overcome at the interface between the second rod 32 and the nut 34 is larger. Therefore, the movement of the second rod 32 along the first rod requires less torque to be applied compared to when the nut 34 moves along the second rod 32.

[0194] Therefore, in the case where the arm 16 is extended, the driving of the first rod 31 by the electric motor 27 of course causes the second rod 32 to translate first in accordance with S1.

[0195] Taking the foregoing into account, the extension of the arm 16 from its fully retracted state starts with the 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 translated by the second rod 32 throughout the movement.

[0196] At the end of the stroke of the second rod 32 along the first rod 31 (the end being characterized by the abutment of the add-on 68 against the second rod 32), the nut 34 is arranged in its intermediate position I. The rotation of the first rod 31 caused by the electric motor 27 causes the translation of the nut 34 in the direction S1 and thus the movement out of the second segment 22 of the arm 16.

[0197] During the translation of the nut 34, the nut 34 moves away from its intermediate position I. The spring 66, which tries to regain its unloaded shape, simultaneously presses the ring 64 against the nut 34 until the ring reaches the locking position, i.e., the position where the section of it with the smallest diameter is radially aligned with the radial opening 60. This locks the translation of the second rod 32 by the combined action of the balls 62 and the add-on 68 until the next movement in of the arm 16 during the ergonomic adjustment of the steering wheel E.

[0198] Reference Figures 3 to 6 has already described a system 38 for the selective restriction of degrees of freedom, which system ensures the locking of the translation of the second rod 32, thereby causing the rotational coupling of the first and second rods 31, 32 in order to move the second segment 22 independently during the comfort adjustment of the steering wheel. As can be understood, the system 38 allows the pure rotation of the second rod 32 to be indirectly forced by preventing the pure translation of the second rod 32.

[0199] However, the system 38 for the selective restriction of degrees of freedom is not restricted in its shape in order to achieve the same result.

[0200] As an alternative, this system 38 can directly restrict the second rod 32 to only rotation about its axis, i.e., without locking its translation. This feature is achieved by the second implementation variant of the system shown in Figure 7 which system forces the direct rotational coupling of the first and second rods 31, 32.

[0201] In the second variant, the system 38 basically has the same elements as in the first variant, namely:

[0202] - a radial opening 60 continuously formed in the second rod 32;

[0203] - balls 62, which are respectively arranged in the corresponding radial openings 60;

[0204] - a ring 64, which radially surrounds the second rod 32;

[0205] - a spring 66, which is arranged between the ring 64 and the radial projection 56 of the second rod 32; and

[0206] - an add-on 68.

[0207] In a second variant, based on Figures 3 to 6 the position of the system 38 relative to the components defined by the rods 31, 32 and the nut 34 of the described motion converter assembly 30 remains unchanged.

[0208] The difference between the first and second implementation variants of the system 38 lies in the form of the add-on 68, which is configured to torsionally connect the first and second rods to each other when acting together with the balls 62 locked in the locking position by the ring 64.

[0209] As can be seen in detail in Figure 7 the add-on 68 of the system 38 according to the second variant is in the form of a bushing, which is fixedly mounted around the first rod in the region of the second end 31b of the first rod 31.

[0210] On the periphery of the add-on 68, a notch 88 is formed. The notch 88 extends in the longitudinal direction along a part of the add-on 68 and is provided to be able to be radially aligned with the opening 60 by the spring 66 respectively in the locking position of the ring 64. It is desired that the number of notches 88 is at least equal to or greater than the number of openings 60 and the associated balls 62. In fact, this involves providing at least one notch for each ball 62, because otherwise it does not work, and the setting of more notches than balls 62 allows multiple angular positions of the add-on 68, which allows the balls to be inserted into the notches 88. It goes without saying that the increase in the number of notches 88 thus requires adding functional safety components.

[0211] In detail, the add-on corresponds to a longitudinal tube, the outer surface of which having an initial, completely circular cross-section denoted by c1 is hollowed inwards according to a circular arc profile to form the notch 88. In the longitudinal section, the notch 88 can be tangentially connected to the inscribed circle denoted by c2 centered on the axis AX1.

[0212] Hereinafter, regarding the positioning of the nut 34 and thus its interaction with the ring 64 and the spring 66, the dimensions of the add-on 68 and the kinematics of the manipulation of the arm 16 are described by means of an electromechanical actuator 26 equipped with the system 38 according to the second variant, as shown in Figures 3 to 6 shown in.

[0213] The radial dimension of the add-on 68 is designed such that:

[0214] - in the locking position of the ring 64, the spacing defined between the inscribed circle c2 and the inner wall 70i is substantially the same as the dimension of the ball 62;

[0215] - in the intermediate position I of the nut, the spacing 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 ball 62.

[0216] On this basis, it can be understood that the system 38:

[0217] - When the ring 64 is in the locked position, since the ring 64 does not allow the balls 62 to escape from the cutout 88, a coupling effect is generated during the rotation of the first and second levers 31, 32;

[0218] - Decoupling is allowed during the rotation of the first and second levers 31 as long as the balls 62 can be released from the cutout 88, which occurs in the intermediate position of the nut 34.

[0219] It should be noted that the diameter of the section c1 at the periphery of the add-on 68 is greater than the diameter of the top circle measured at the tip of the thread line of the internal thread of the second lever 32. Therefore, in a manner similar to the side wall of the functional part 74 of the add-on 68 according to the first embodiment variant, the add-on according to the second variant ensures blocking along the longitudinal direction of the first segment 20 of the arm 16 in the direction S1. The fully retracted state of the first segment 20 of the arm 20 corresponds to the abutment of the longitudinal section of the add-on 68 on the internal thread of the second lever 32.

[0220] Starting from the retracted state of the arm 16, as long as the nut 34 is not in the intermediate position I, the rotation of the first lever 31 caused by the motor 27 (for moving the arm 16 in) will necessarily result in the pure rotation of the second lever 32.

[0221] As a result, in response to restricting the rotation of the second lever 32 connected to the first lever 31 by the system 38, the movement of the arm 16 in starts with the movement of the second segment 22 of the arm caused by the nut 34 in the direction opposite to the direction S1. In the same way as in the first embodiment variant of the system 38, the nut 34 abuts against the ring 64, which is held in the locked position by the spring 66. Since the first lever 31 is always still rotationally driven by the motor 27, the nut 34 continues to move in the direction of the intermediate position I, and the nut drives the ring 64 during its movement.

[0222] The result of the movement of the ring 64 is that the measured radial clearance between the outer wall of the second lever 32 and the inner wall 70i of the ring 64 increases to the extent that the nut 34 approaches the intermediate position I. Due to the expansion characteristic of the ring 64 at the radial inner wall 70i, the balls 62 can move radially outwards. In fact, once the nut 34 reaches the intermediate position I, the balls 62 slide along the contour of the cutout 88 until they leave the cutout 88.

[0223] Thus, at this stage, when the nut 34 has reached the end of its travel along the second rod 32 and represents the state of full insertion of the second segment 22, the second rod 32 can be translated. The pure translation of the second rod 32 is initiated by screwing the first rod 31 in the direction opposite to the direction S1. The nut 34 and the snap ring 54 are translationally driven by the second rod 32, which causes the first and second segments 20, 22, which are fixedly connected to the snap ring 54 and the nut 34 respectively, to move translationally together. The second rod 32 continues to translate along the first rod 31 until it abuts against the shoulder 44, which represents the state of full insertion of the first segment 20 of the arm. The nut 34 is then in the position denoted by R.

[0224] The arm 16 is retracted by means of an electromechanical actuator equipped with the system 38 according to the second variant, which 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 pitch carried out naturally gives priority to the pure translation of the second rod 32 with respect to the pure rotation of the second rod 32.

[0225] Thus, from the state of full insertion, the retraction of the arm 16 is initiated by the common retraction of the first and second sections 20, 22 in the direction S1 due to the pure translation of the second rod 32, which drives the snap ring 54 and the nut 34. The first segment 20 reaches its state of full retraction with respect to the cylinder 14, which corresponds to the transition of the nut to the intermediate position I.

[0226] In the intermediate position of the nut 34, the add-on 68 abuts against the internal thread of the second rod 32, which provides a support point for the translation of the second rod 32: the first segment 20 is in the state of full retraction. Then, a characteristic change of the second rod 32 occurs, which starts to rotate about its axis in response to the continuous rotation of the first rod 31 caused by the electric motor 27.

[0227] When the nut 34 translates along the second rod 32 in the direction S1, this nut allows the longitudinal movement of the ring 64, which gradually returns to its locking position by means of the spring 66, which causes the balls to return to the corresponding notches 88 of the add-on 68. As a result, this restricts the second rod 32 from performing a pure rotation until the next insertion of the arm 16 during the ergonomic adjustment of the steering wheel E.

[0228] Taking into account the foregoing, the system 38 for restricting the degrees of freedom allows the movement of the second rod 32 to be limited to a pure rotation in the following ways:

[0229] - Indirectly by translational locking according to the first implementation variant; or

[0230] - Directly by forced rotational coupling with the first rod 31 in the second variant.

[0231] It should be noted that the present invention is not limited to the form of the add-on 68 of the described different variants of the restraint system 38 equipped with the steering column assembly according to the first embodiment, as long as it:

[0232] - is capable of achieving a connection with the first rod;

[0233] - defines a longitudinal contact surface of the second rod; and

[0234] - ensures the locking of the translation of the second rod or the rotational coupling of the rods through a common action with the balls 62.

[0235] As an example, the add-on 68 according to the second variant is not limited to the form of a bushing that allows the fitting of the first rod 31 inside it. It is possible to consider an arrangement where the add-on 68 according to the second variant is a solid body that includes a fixing part 76 as described in the first variant, in order to act in common with the threaded blind hole 79 constructed in the first rod 31. Conversely, the add-on 68 according to the first variant can be a hollow body that allows the fitting of the first rod 31 inside it in order to ensure its joining. The add-on 68 is also not limited to an element arranged on the first rod 31, which can be an essential integral part of the first rod 31. Whether the add-on 68 is joined to the first rod 31 or the two components are manufactured integrally depends on the challenges in joining the elements of the electromechanical actuator 26.

[0236] The present invention is also not limited to the use of the balls 62. In fact, the balls can be replaced by each element that can move radially in the opening 60 in order to interact with the add-on 68. As a non-limiting example, the balls can be replaced by pins.

[0237] Furthermore, it has been described based on Figures 3 to 7 the case of retracting the telescopic arm 16 according to the first embodiment by means of the electromechanical actuator 26, so that there is no need for the fitting of the restraint system 38. In fact, this arrangement benefits from the pure translation of the second rod 32, which naturally prevails over its pure rotation due to the difference in the dimensions and pitch of the rods 31, 32.

[0238] However, it is possible to propose such an extension of the restraint system 38 in order to force the second rod 32 to translate, as long as the first segment is not completely retracted during the retraction phase of the arm. This feature can improve the reliability of the electromechanical actuator 26.

[0239] The motion converter 30 has been described in such a way that it includes a nut 34 and a bearing 36, which are respectively connected to the second segment 22 and the first segment 20 in order to cause their longitudinal forward movement state.

[0240] In fact, the movement converter 30 can be sufficient without such a bearing 36. For example, the bearing 36 can be replaced by a system that translationally connects the first and second segments 20, 22 during ergonomic adjustment. In this regard, a system can be considered that is formed by a first element mounted at the first segment 20 and a second element mounted at the second segment 22, where these elements:

[0241] - can engage during ergonomic adjustment; and

[0242] - can separate during comfort adjustment.

[0243] Finally, it should be noted that the electromechanical actuator 26 according to the present invention is not limited to the manipulation of the telescopic arm 16, which is formed by a plurality of segments as in the examples of Figure 1 and 2 respectively.

[0244] Reference Figure 8 and 9 shows that the steering column assembly 10 according to the second embodiment differs from the first form in that it is provided with a unified arm 16, i.e., formed by a single segment, which can telescopically move relative to the column 14 between a fully retracted and an extended position.

[0245] In this example, the shaft 16 is slidably mounted in a bore formed in the column 14. In addition, the column assembly 10 is equipped with an electromechanical actuator 26, and the limiting system 38 of this electromechanical actuator corresponds to the second variant described based on Figure 7 . It should be noted that the limiting system can also be used according to the first variant of the limiting system 38.

[0246] In this embodiment, the nut 34 is fixed to the arm 16 and forms the only interface element between the movement 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 14.

[0247] In this example, the retraction / extension kinematic structure of the arm 16 follows the same logic as that described based on Figure 7 , with the difference that it is the same segment moving at two different speeds, rather than two segments moving at different speeds as in the first form.

[0248] Generally, the concept on which the present invention is based is to achieve the retraction / extension of the arm 16 of the vehicle steering column at different speeds by means of a single actuator 26.

[0249] In the above description, the electromechanical actuator 26 and in particular its motion converter 30 have been defined for controlling the arm 16 in such a way that:

[0250] - the so-called comfort adjustment of the steering wheel is caused by the movement of the nut 34 along the second rod 32; and

[0251] - the so-called ergonomic adjustment of the steering wheel is caused by the translation of the second rod 32 along the first rod 31.

[0252] As can be understood, the invention is not limited to the definition of the rods 31, 32 and the nut 34, in particular their threads or also the definition of the limiting system 38, in order to perform this particular task.

[0253] In fact, the opposite 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 movement of the nut 34 along the second rod 32.

[0254] In this regard, it is a matter of defining the pitch ratio of the rods 31, 32 and the nut 34 and conditioning the limiting system 38 to limit the characteristics of the second rod 32 according to a logic opposite to the logic based on Figures 1 to 9 the logic described.

[0255] Specifically, in this case, the pitch defining the interaction between the first rod 31 and the second rod 32 must be made smaller than the pitch defining the interaction between the second rod 32 and the nut 34.

[0256] On the other hand, the limiting system 38 can be conditioned conversely in the following way in order to limit the movement of the second rod 32:

[0257] - a pure translation along the first rod 31 in the case of comfort adjustment; and

[0258] - a pure rotation which causes an independent movement of the nut 34 along the second rod 32 during ergonomic adjustment.

Claims

1. A steering column assembly (10) for a steering system of a vehicle, in particular a motor vehicle, having a steering wheel, said steering column assembly comprising: - a column body (14) which is arranged to be mounted on the vehicle structure; - an arm (16) carried by the column body (14), said arm extending along a longitudinal direction (AX), wherein the arm (16) is mounted in a telescopable manner so as to be longitudinally translatable relative to the column body (14) between a retracted forward position and an extended forward position, wherein the forward position of the arm determines the position of the steering wheel of the steering system; - an electromechanical actuator (26) for translating the arm (16) at different speeds, wherein the electromechanical actuator (26) has the following components: -- a motor (27) for rotary drive; -- a motion converter assembly (30) for converting the rotation provided by the motor (27) into translation of the arm (16), wherein the motion converter (30) has the following components: --- a nut (34) which is torsionally fixed to the arm (16), wherein the nut (34) has a thread; --- a first rod (31) which extends along a rod axis (AX1) with a longitudinal extension, wherein the first rod (31) is translationally resistant along its axis and is capable of rotational movement about its axis, in that: the first rod is rotated by the motor (27), wherein the first rod (31) has a thread; --- a second rod (32) which extends longitudinally along a respective rod axis in a concentric manner with the first rod (31) in the longitudinal direction with a longitudinal extension, wherein the second rod (32) is capable of rotational movement about its axis and is capable of translational movement along its axis, 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 (38) for selectively restricting the degrees of freedom of the second rod (32), said system selectively and depending on the position of the nut (36) along the second rod (32): --- only allows the second rod (32) to rotate about its axis so as to move the arm by screwing in / screwing out of the nut (34) along the second thread of the second rod (32) when the first rod is rotated by the motor (27); --- only allows the second rod (32) to translate along its axis so as to move the arm (16) by translation of the second rod (32) carrying the nut (34) and by screwing in / screwing out of the second rod (32) along the first rod (31) by means of thread cooperation; wherein the thread cooperation between the first and second rods (31, 32) is defined by a pitch which is different from the defined pitch for the thread cooperation between the second rod (32) and the nut (34).

2. The 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, wherein the first rod (31) has a first rod body defined by an outer wall, and the thread is configured on the outer wall; - The second rod (32) has a second hollow rod body, and the thickness of the second hollow rod body is simultaneously defined by the following components: -- An outer wall, on which the second thread is configured, and the second thread is an external thread that cooperates with the thread of the nut (34), wherein the nut is carried by the second rod body; -- An inner wall, on which the first thread is configured, and the first thread is an internal thread that cooperates with the thread of the first rod (31), wherein the second rod body at least partially radially surrounds the first rod body.

3. The steering column assembly (10) according to claim 2, wherein the thread cooperation between the first and second rods (31, 32) is defined by a pitch value larger than the pitch that defines the thread cooperation between the second rod (32) and the nut (34).

4. The steering column assembly (10) according to claim 2 or 3, wherein the system (38) for selectively restricting degrees of freedom includes the following components: - A radial opening (60) that is continuously formed in the second rod (32) in the region of a longitudinal section of the second rod, wherein the opening (60) connects the outer wall and the inner wall of the second rod (32), and extends spaced apart from the second thread; - A ball (62) that is respectively arranged in one of the respective radial openings (60), wherein the ball (60) has a diameter larger than the thickness of the second rod (32) so as to respectively project radially beyond the corresponding opening (60); - A ring (64) that radially surrounds the second rod (32), and the ring is capable of longitudinal translational movement, wherein the ring (64) has a sufficient longitudinal extent so as to simultaneously radially surround the opening (60) and a part of the second thread of the second rod (32), and the ring has an inner wall (72i) facing the second rod (32), and the inner wall expands starting from a section with a smaller diameter arranged flush with the second rod; - A spring (66) that passively holds the ring (64) in a locking position, and for the locking position: -- The section with a smaller diameter of the inner wall (72i) of the ring (60) is flush with the radial opening (60), and -- The inner wall (72i) radially surrounds a part of the external thread of the second rod (32); - An add-on part (68) that extends the first rod (31) into the second rod (32) and that defines a longitudinal contact surface against which the second rod (32) abuts in a position distal relative to the first rod (31), wherein the add-on part (68) is adapted to cooperate with the ball (62) in the distal position of the second rod (32), the ball being pressed towards the add-on part by the ring (60) in the locked position; wherein the nut (34) is adapted to release the ring (60) from its locked position by translating the nut towards the spring (66) in response to rotation of the second rod (32) along a second threaded part radially surrounded by the ring (64) in the locked position, wherein the release of the ring (64) causes an increase in the measured spacing between the inner wall (72i) of the ring (64) and the opening (60) so as to allow the ball (62) to move radially away from the add-on part (38).

5. The steering column assembly (10) according to claim 4, wherein when the ring (64) is in the locked position and the second rod (62) abuts against the add-on part (68) in the distal position, the add-on part (68) cooperates with the ball (62) to lock the translation of the second rod (68).

6. The steering column assembly (10) according to claim 5, wherein the add-on part (68) includes a frustoconical portion (82) defined along the longitudinal direction by a large base (81) and a small base (74b), wherein the large base (81) is closer to the first rod (31) than the small base (74b), and wherein the dimensions of the frustoconical portion (82) are designed such that: - the diameter of the ball (62) is greater than the radial spacing measured between the large base (81) and the section of the inner wall (72i) of the ring (64) having the smallest diameter; and - the translation of the second rod (32) out of its distal position causes a shift of the opening (60) to be radially aligned with the large base (81); and wherein the release of the ring (64) by the nut (64) causes an increase in the measured radial spacing between the inner wall (72i) and the large base (81) until the spacing is greater than the diameter of the ball (62).

7. The steering column assembly (10) according to claim 4, wherein when the ring (64) is in the locked position and the second rod (32) abuts against the add-on part (68) in the distal position, the add-on part (68) cooperates with the ball (62) to force the first and second rods (31, 32) to be rotationally coupled.

8. The steering column assembly (10) according to claim 7, wherein the additional part (68) is defined by an outer wall provided with incisions (88) extending along the longitudinal direction with an arcuate profile, wherein the number of the incisions (88) is equal to or greater than the number of the openings (60) and the respective balls (62), and wherein the additional part (68) is dimensioned such that the balls (62) are pressed into the incisions (88) in the locking position of the ring (64) and in the position distal to the second rod (62); and wherein loosening of the ring (64) by the nut (34) causes an increase in the measured radial spacing between the inner wall (72i) and the additional part (68) until the spacing is greater than the diameter of the balls (62) to allow the balls to leave the incisions (88).

9. The steering column assembly (10) according to any one of the preceding claims, wherein the arm (16) is telescopic by being formed of a plurality of segments movable translationally relative to one another, wherein: - a first segment (20) having a longitudinal extent, the first segment being carried by the column (14) and being movable longitudinally translationally relative to the column (14); and - a second segment (22) inserted into the first segment (20) and movable longitudinally along the first segment (20); wherein the electromechanical actuator (26) further has a rotary guide bearing (36) surrounding the second rod (32) by being mounted anti-translationally with the second rod (32); and wherein the bearing (36) is rigidly connected to the first segment (20) and the nut (64) is rigidly connected to the second segment (22).

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