STEERING COLUMN DRIVE ASSEMBLY

Abstract

The present invention relates to a steering column rotation drive assembly for a vehicle, adapted to be connected to a steering mechanism mechanically disconnected from the drive assembly, comprising: - a fixed support element; - a central steering shaft (14) mounted for rotation relative to the fixed support element; - and an angular stop device, limiting the angular travel of the central steering shaft (14) relative to the fixed support element (16), which comprises: -- a rotating front ring (26) rotationally linked to the central steering shaft (14); -- a fixed rear ring (28); characterized in that the rotating front ring (26) is axially slidable around a section of the central steering shaft (14) and such that it is rotationally linked to the section of the central steering shaft (14). Figure for the abstract: 2

Description

Title of the invention: STEERING COLUMN DRIVE ASSEMBLY Technical field of the invention

[0001] The present invention relates to a rotational drive assembly for a vehicle steering column, suitable for being connected to a mechanically disconnected steering mechanism.

[0002] The invention relates in particular to a drive assembly for a steering system of the so-called "Steer by Wire" or "SbW" type, or electrically controlled steering. Technical background

[0003] In a "SbW" type steering system, there is no longer a mechanical link between the upper part of the steering column containing the steering shaft which carries the steering wheel and the lower part containing the steering box and the steering rack.

[0004] Due to such a mechanical disconnection between the driver's steering rotation drive assembly and the steering mechanism including the rack, it was necessary to design means to provide the driver with different sensations related to driving and steering operation, such as, for example, force feedback.

[0005] For this purpose, it is known to integrate into the vehicle's steering column a force feedback module, also called "Force Feedback Unit" or "FFU", which provides the driver with force feedback giving him sensations similar to those he perceives with a conventional mechanical steering system.

[0006] Such a steering column comprising a force feedback module further comprises a central steering shaft linked to a steering wheel and ensuring the rotational link between the steering wheel and the force feedback module.

[0007] Also, the central steering shaft is rotationally linked to an angular end stop device, also called an "Angular End Stop" or "AeS," which limits the angular travel of the steering wheel in order to minimize damage to the various components and equipment of the steering column, such as electrical connectors and airbag wiring. This risk is particularly significant when the vehicle is stationary, the battery is disconnected, and the steering wheel is therefore easy to turn.

[0008] The rotational connection of the central steering shaft to the angular stop device is then achieved by means of a rotating front ring for movement input.

[0009] It is therefore necessary to obtain a reliable rotational connection between the central shaft of direction and the rotating front ring, regardless of the value of the torque applied to the central steering shaft, for the proper functioning of the angular stop device.

[0010] The invention therefore aims to provide an optimal rotational connection between the central steering shaft and the rotating front ring, independent of the value of the torque applied to the shaft. Summary of the invention

[0011] The invention proposes a rotational drive assembly for a vehicle steering column, extending along a longitudinal axis and capable of being connected to a steering mechanism mechanically disconnected from the drive assembly, comprising:

[0012] - a fixed support element;

[0013] - a central steering shaft mounted for rotation relative to the support element fixed, and capable of being linked in rotation to a steering component, in particular to a steering wheel;

[0014] - and an angular end-stop device, limiting the angular stroke, in both directions, of the central steering shaft relative to the fixed support element, which includes:

[0015] — a rotating front motion input ring rotationally linked to the central shaft of direction;

[0016] — a fixed rear angular stop ring rotationally linked to the support element fixed ;

[0017] — and possibly at least one intermediate transmission ring that can rotate relative to the central steering shaft and which is axially interposed between the rotating front ring and the fixed rear ring,

[0018] characterized in that:

[0019] the front rotating ring is mounted to slide axially around a section of the central steering shaft and in such a way that the front rotating ring is rotationally linked to the section of the central steering shaft.

[0020] According to other features of the invention:

[0021] - the section of the central steering shaft originates from a cylinder with a longitudinal axis which is delimited by an external peripheral edge comprising at least one radial projection and / or recess extending longitudinally along the central steering shaft, the rotating front ring comprising an internal peripheral wall having a complementary shape with the external peripheral edge of the central steering shaft and such that the rotating front ring is rotationally bound to the central steering shaft by angular stop of the at least one radial projection and / or recess of the outer peripheral edge against the inner peripheral wall of the rotating front ring;

[0022] - at least one radial projection and / or recess on the outer peripheral edge of the central steering shaft takes the form of a flat configured to cooperate with an overthickness of the internal peripheral wall of the rotating front ring in such a way that the rotating front ring is linked in rotation with the central steering shaft by angular stop;

[0023] - at least one radial projection and / or recess on the outer peripheral edge of the central steering shaft takes the form of an external spline configured to cooperate with a complementary spline of the internal peripheral wall of the rotating front ring such that the rotating front ring is rotationally linked with the central steering shaft by angular stop;

[0024] - the external groove formed on the outer peripheral edge of the central shaft of direction is formed by a radial recess;

[0025] - the central steering shaft includes at least one internal spline formed at less by a radial overthickness, the recess forming the groove on the outer peripheral edge of the central steering shaft being radially aligned with the overthickness forming the inner groove of the central steering shaft;

[0026] - the central steering shaft section comprises eighteen external splines formed on its outer peripheral edge;

[0027] - the angular limit switch device includes at least one axial spring of com pressure interposed axially between a front spacer and the rotating front ring. Brief description of the figures

[0028] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0029] [Fig-1] is a schematic cross-sectional representation by an axial plane of an assembly training according to the state of the art;

[0030] [Fig.2] is a three-quarter front perspective view of an assembly training according to the invention;

[0031] [Fig.3] is a partial exploded perspective view of the components of a device angular end-of-stroke of the assembly shown in [Fig.2];

[0032] [Fig.4] is a radial plane cross-sectional view of a rotating front ring of the drive assembly of [Fig.2], mounted around a central steering shaft according to a first embodiment of the invention;

[0033] [Fig.5] is a radial plane cross-sectional view of the rotating front ring of the drive assembly of [Fig.2], mounted around the central steering shaft according to a second embodiment of the invention. Detailed description of the invention

[0034] In the description that follows, identical, similar or analogous elements will be designated by the same reference numerals.

[0035] Figure [Fig. 1] schematically represents a drive assembly 10 for rotating a vehicle steering column, suitable for being connected to a steering mechanism (not shown) mechanically disconnected from the drive assembly 10.

[0036] This assembly extends along a longitudinal axis "L" which, by non-limiting convention, is oriented axially from the front to the back of the assembly, from right to left considering [Fig.1].

[0037] The assembly 10 includes a central steering shaft 14 which is here a tubular shaft originating from a hollow cylinder, internally grooved.

[0038] A front axial end of the central steering shaft 14 is rotationally linked to a steering wheel 12.

[0039] The central steering shaft 14 is mounted to rotate in both directions relative to a fixed support element which is here a steering tube 16 through which the central steering shaft 14 passes coaxially.

[0040] According to the invention, the support element 16 is fixed relative to the central steering shaft 14 during the steering wheel rotation phases. However, during other phases of use, the fixed support element, here constituted by the steering tube 16, can move, in particular relative to surrounding structural elements of the vehicle, for example for adjusting the position of the steering wheel in the passenger compartment, or in the event of steering wheel retraction.

[0041] At its rear free end, the assembly 10 includes a force return module 18 or “FFU” which includes an output shaft 20 which extends axially forward inside the central steering shaft 14 to which its free end 22 is rotationally connected by splines complementary to those located inside the central steering shaft 14.

[0042] The assembly 10 includes an angular end-of-stroke stop device 24 or "AeS" whose function is to limit the angular stroke, in both directions, of the central steering shaft 14 relative to the steering tube 16.

[0043] The angular stop device 24 comprises a rotating front ring 26 and a fixed rear angular stop ring 28 which is rotationally linked to the fixed steering tube 16.

[0044] The fixed rear ring 28 is here fixed axially and rotationally to the fixed steering tube 16, for example by a radial screw 29.

[0045] Between the rotating front ring 26 and the fixed rear ring 28, the angular stop device 24 here comprises adjacent intermediate rings 30i which are axially juxtaposed.

[0046] Thus, the angular stop device 24 comprises a set of axially juxtaposed adjacent components including the rotating front ring 24, the intermediate rings 30i and the fixed rear ring 28.

[0047] The axial stacking of the components is ensured by means of an axial compression spring 32 which is interposed axially between a front spacer 34 and a front radial face opposite the rotating front ring 26.

[0048] The rotating front ring 26 is configured to be rotationally linked to a section of the central steering shaft 14 while being axially slidably mounted on said section of the central steering shaft 14.

[0049] It is then understood that the rotating front ring 26 is not press-fitted onto the section of the central steering shaft 14.

[0050] It should be considered that the term "section of the central steering shaft" means all or part of the central steering shaft along the longitudinal axis L.

[0051] According to a feature of the invention visible in figures 2, 4 and 5, the central steering shaft 14, originating from a hollow cylinder, is delimited by an external peripheral edge 140 which includes on the section, a projection and / or a recess in radial section, suitable for cooperating by complementarity of form with an internal peripheral wall 260 of the rotating front ring 26, visible in figures 4 to 5.

[0052] It is then understood that the projection and / or the recess in radial section of the external peripheral edge is formed longitudinally on the section of the central steering shaft 14 receiving the rotating front ring 26.

[0053] The complementary shape between the outer peripheral edge 140 of the central steering shaft 14 and the inner peripheral wall 260 of the rotating front ring 26 forms at least one angular stop allowing the rotational coupling of the rotating front ring 26 with the central steering shaft 14.

[0054] According to a first non-limiting embodiment of the invention visible in [Fig.4], the outer peripheral edge 140 of the central steering shaft 14 comprises radially sectioned flats 142 which extend longitudinally along the section of the central steering shaft 14.

[0055] In the illustrated example of [Fig.4], the central steering shaft 14 comprises four flats 142 which extend longitudinally over its outer peripheral edge 140.

[0056] Here, the four flats 142 extend over the outer peripheral edge 140 in such a way that each flat 142 is diametrically opposite another flat 142.

[0057] It should also be considered that the number of flats, at least equal to one, is not limiting and that it can vary depending on the value of the torque applied to the central steering shaft 14.

[0058] For example, it can be provided that the section of the central steering shaft comprises six flats such that the section of the central steering shaft forms a hexagon in radial section.

[0059] In other words, by increasing the number of flats, we increase the number of angular stops formed between the central steering shaft and the rotating front ring.

[0060] According to this example of the invention in [Fig.4], the rotating front ring 26 includes overthicknesses 262 formed on its internal peripheral wall 260 and such that each of the overthicknesses 262 cooperate with one of the flats 142 of the central steering shaft 14.

[0061] It is also understood that the overthicknesses 262 here form flat surfaces in radial section so as to present a complementarity of form with the flats 142 of the central steering shaft 14.

[0062] In other words, the concave profile of the inner peripheral wall 260 of the rotating front ring 26 includes overthicknesses forming flat portions in radial section such that the space delimited by the inner peripheral wall 260 does not take the form of a cylinder of revolution.

[0063] Thus, the contact between the flats 142 and the overthicknesses 262 respectively of the central steering shaft 14 and the rotating front ring 26 makes it possible to form the angular stops, ensuring the rotation of the rotating front ring 26 by the central steering shaft 14 as mentioned above.

[0064] It should also be considered that a radial play, for example due to manufacturing tolerances and for the mounting constraints in axial sliding of the angular stop device on the central steering shaft, may remain between the external peripheral edge 140 and the internal peripheral wall 260, it being considered that this radial play does not prevent the formation of the angular stops as just described.

[0065] For example, and without limitation, the radial gap between the outer peripheral edge 140 and the inner peripheral wall 260 can be between 0.01mm and 0.5mm.

[0066] According to another example of the invention illustrated in figures 2, 3 and 5, the outer peripheral edge 140 of the central steering shaft 14 comprises external grooves 144 in radial section.

[0067] More specifically, in this non-limiting example of the invention, the splines 144 extend longitudinally over the outer circumference of the central steering shaft section 14.

[0068] The splines 144 are here splines formed in a complementary manner with the internal splines of the central steering shaft 14 mentioned previously.

[0069] In other words, the radial recesses of material forming the grooves 144 of the outer peripheral edge 140 are formed in the radial alignment of the overthicknesses forming the internal grooves of the central steering shaft 14.

[0070] Such an arrangement between the external splines 144 and the internal splines of the central steering shaft 14 makes it possible to maintain a sufficient radial thickness of the central steering shaft 14 for the formation of the internal and external splines while maintaining a sufficient level of robustness of the central steering shaft 14.

[0071] In this embodiment of the invention, the internal peripheral wall 260 of the rotating front ring 26 includes complementary splines 264 to the external splines 144 formed on the central steering shaft 14.

[0072] It is understood that such a complementarity of form between the splines 144, 264 formed on the central steering shaft 14 and the rotating front ring 26 as described above, makes it possible to form angular stops ensuring the rotational connection of these two parts with each other.

[0073] In other words, the configuration of the central steering shaft 14 as described and of the rotating front ring 26 according to this example of the invention ensures the rotational drive of the rotating front ring 26 by the central steering shaft 14.

[0074] It should also be considered that the number of external splines 144 formed on the outer peripheral edge 140 of the central steering shaft 14 is not fixed and varies according to the value of the torque applied to the central steering shaft 14.

[0075] Thus, the higher the value of the torque applied to the central steering shaft 14, the higher the number of external splines 144 of the central steering shaft 14.

[0076] According to a preferred embodiment, the number of external splines formed on the central steering shaft 14 and, complementaryly, on the rotating front ring 26, is equal to eighteen.

[0077] Furthermore, the external splines 144 formed on the central steering shaft 14 and, complementaryly, on the rotating front ring 26 can have a straight or involutive shape.

[0078] Furthermore, according to an example of the invention not shown, the number of splines formed on the central steering shaft 14 and complementaryly on the rotating front ring 26 may be different.

[0079] Without limitation, the radial depth of the recess forming the external grooves 144 of the external peripheral edge 140 is between 0.5mm and 5mm.

[0080] The additional depth of the overthickness forming the grooves 264 on the internal peripheral wall 260 is thus substantially identical to the radial depth of the recess forming the grooves 144.

[0081] It should also be considered that a radial play, for example due to manufacturing tolerances and assembly constraints mentioned above, may remain between the grooves 144 of the outer peripheral edge 140 and those formed on the inner peripheral wall 260 of the rotating front ring 26, as long as this radial play does not prevent the formation of angular stops as just described.

[0082] For example, and without limitation, the radial gap between the grooves 144 of the outer peripheral edge 140 and those formed on the inner peripheral wall 260 can be between 0.01mm and 0.5mm.

[0083] In relation to [Fig. 1], the rotating front ring 26 allows, by its rotation via the central steering shaft 14 as described previously, the transmission of the torque from the central steering shaft 14 to the intermediate rings 30-i.

[0084] Thus, the rotating front ring 26 transmits its rotation to the ring 30-1 which is adjacent to it, which can itself transmit its rotation to the axially following intermediate ring 30-2 which is adjacent to it, etc.

[0085] The intermediate ring 30-4 which is adjacent to the fixed rear ring 28 cooperates with the latter to come angularly into contact in one or the other direction.

[0086] In the illustrated example of the invention in Figures 2 and 3 and without limitation, the angular end stop device 24 comprises a series of eight adjacent and axially juxtaposed intermediate rings 30i.

[0087] As can be seen in [Fig.3], the rotating front ring 26 has a central annular body 40 in the form of a plate whose front annular radial face 42 is smooth, while its rear annular radial face has a radially internal convex cylindrical centering surface 46 which extends axially backwards from the central annular body 40.

[0088] The convex cylindrical bearing 46 has a pair of drive lugs 48 which are diametrically opposed and which extend axially towards the rear, here over the entire axial width of the convex cylindrical centering bearing 46.

[0089] As can be seen in figures 2 and 3, the fixed rear ring 28 comprises a hollow cylindrical body which, in its front annular face, comprises a radially external concave cylindrical centering surface 150, which is axially open towards the front.

[0090] The concave cylindrical bearing 150 here includes a pair of stop lugs 149 which are diametrically opposed and which extend axially forward here over the entire axial width of the concave cylindrical centering bearing 150.

[0091] As can be seen in [Fig. 3], each intermediate ring 30i comprises a central annular body 240 in the shape of a plate, the rear annular radial face includes a convex cylindrical centering bearing 246, radially internal, which extends axially backwards from the annular central body 240.

[0092] The convex cylindrical bearing 246 here includes a pair of radially external drive lugs 248 which are diametrically opposed and which extend axially backwards here over the entire axial width of the convex cylindrical centering bearing 246.

[0093] In its front annular face 244, the central body 240 has a radially external concave cylindrical centering bearing 250, which is axially open towards the front.

[0094] The concave cylindrical bearing 250 here includes a pair of radially internal drive lugs 249 which are diametrically opposed and which extend axially forward here over the entire axial width of the concave cylindrical bearing of centering 250.

[0095] Thus, an intermediate ring is radially centered with respect to another ring which is axially adjacent to it due to the cooperation of a convex centering bearing 246 which is received axially in a complementary concave cylindrical bearing 250 of the other adjacent ring.

[0096] Each intermediate ring 30i is rotatable relative to the central steering shaft 14 and is traversed axially by the central steering shaft 14 with a radial clearance between the outer peripheral edge of the central rotating shaft and the inner peripheral surface of its central bore.

[0097] The angular deflection of an intermediate ring 30i with respect to another intermediate ring which is adjacent to it is delimited by the cooperation of the legs 249 and the legs 248 which are angularly intercalated.

[0098] The intermediate ring 30-1 adjacent to the rotating front ring 26 is centered relative to the latter due to the cooperation of its concave cylindrical centering bearing 250 with the complementary convex cylindrical centering bearing 46.

[0099] The angular deflection of the intermediate ring 30-1 relative to the adjacent rotating front ring 26 is delimited by the cooperation of the legs 249 and the legs 48 which are interposed.

[0100] The intermediate ring 30-8 adjacent to the fixed rear ring 28 is centered relative to the latter due to the cooperation of its convex cylindrical centering bearing 246 with the complementary concave cylindrical centering bearing 150.

[0101] The angular deflection of the intermediate ring 30-8 relative to the fixed rear ring 28 adjacent to it is delimited by the cooperation of the lugs 149 with the lugs 248 which are angularly intercalated.

[0102] Without departing from the scope of the invention, as a variant by mechanical inversion, the angular limit stop device can, for example, be on the shaft 20, with the fixed ring linked to element 16 and the rotating ring linked to shaft 20.

Claims

Claims

1. Assembly (10) for driving a vehicle steering column in rotation, which extends along a longitudinal axis (L) and which is capable of being connected to a steering mechanism mechanically disconnected from the drive assembly, comprising: - a fixed support element (16); - a central steering shaft (14) mounted in rotation relative to the fixed support element (16), and capable of being connected in rotation to a steering member (12), in particular to a steering wheel; - and an end-of-travel angular stop device (24), limiting the angular travel, in both directions, of the central steering shaft (14) relative to the fixed support element (16), which comprises: — a rotating front movement input ring (26) linked in rotation to the central steering shaft (14); — a fixed rear ring (28) of angular stop linked in rotation to the fixed support element (16); — and possibly at least one intermediate transmission ring (30i) which can rotate relative to the central steering shaft (14) and which is interposed axially between the rotating front ring (26) and the fixed rear ring (28), characterized in that: the rotating front ring (26) is mounted to slide axially around a section of the central steering shaft (14) and in such a way that the rotating front ring (26) is rotationally linked to the section of the central steering shaft (14).

2. Assembly (10) according to the preceding claim, in which the section of the central steering shaft (14) comes from a cylinder of longitudinal axis (L) which is delimited by an external peripheral edge (140) comprising at least one projection and / or one radial recess which extends longitudinally on the central steering shaft (14), the rotating front ring (26) comprising an internal peripheral wall (260) having a complementary shape with the external peripheral edge (140) of the central steering shaft (14) and such that the rotating front ring (26) is linked in rotation with the central steering shaft (14) by angular abutment of the at least one projection and / or one radial recess of the external peripheral edge (140) against the internal peripheral wall (260) of the rotating front ring (26).

3. Assembly (10) according to the preceding claim, in which the at least one projection and / or a radial recess of the external peripheral edge (140) of the central steering shaft (14) takes the form of a flat (142) configured to cooperate with an excess thickness (262) of the internal peripheral wall (260) of the rotating front ring (26) such that the rotating front ring (26) is linked in rotation with the central steering shaft (14) by angular stop.

4. Assembly (10) according to claim 2, in which the at least one projection and / or a radial recess of the external peripheral edge (140) of the central steering shaft (14) takes the form of an external groove (144) configured to cooperate with a complementary groove (264) of the internal peripheral wall (260) of the rotating front ring (26) such that the rotating front ring (26) is linked in rotation with the central steering shaft (14) by angular stop.

5. Assembly (10) according to the preceding claim, in which the external groove (144) formed on the external peripheral edge (140) of the central steering shaft (14) is formed by a radial recess.

6. An assembly (10) according to any one of claims 4 or 5, wherein the central steering shaft (14) comprises at least one internal spline formed by at least one radial overthickness, the recess forming the spline (144) on the outer peripheral edge (140) of the central steering shaft (14) being radially aligned with the overthickness forming the internal spline of the central steering shaft (14).

7. An assembly (10) according to any one of claims 4 to 6, wherein the section of the central steering shaft (14) comprises eighteen external splines (144) formed on its outer peripheral edge (140).

8. Assembly (10) according to any one of the preceding claims, in which the angular end-of-travel device (24) comprises at least one axial compression spring (32) interposed axially between a front spacer (34) and the rotating front ring (26).

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