STEERING COLUMN DRIVE ASSEMBLY WITH AN ANGULAR END-OF-TRAVEL STOP DEVICE

Abstract

The present invention relates to a rotational drive assembly for a vehicle steering column connected to a steering mechanism comprising: - a fixed support element; - a central steering shaft (14) mounted for rotation relative to the fixed support element (16); - and an end-of-travel angular stop device, limiting the angular travel of the central steering shaft (14) relative to the fixed support element, which comprises: -- a rotating front ring (26) linked in rotation to the central steering shaft (14); -- a fixed rear ring linked in rotation to the fixed support element (16); characterized in that an elastically deformable member (32), interposed axially between the rotating front ring (26) and an axial support element linked to the central steering shaft (14), provides an elastic return function in rotation. Figure for the abstract: 5

Description

Title of the invention: STEERING COLUMN DRIVE ASSEMBLY WITH AN ANGULAR END-OF-TRAVEL STOP DEVICE Technical field of the invention

[0001] The present invention relates to a rotational drive assembly for a vehicle steering column, capable of 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 any mechanical connection between the upper part of the steering column comprising the steering shaft which carries the steering wheel and the lower part comprising the steering box and the steering rack.

[0004] Due to such a mechanical disconnection between the assembly for driving the steering in rotation by the driver and the steering mechanism including in particular the rack, it was necessary to design means making it possible to restore to the driver different sensations linked to driving and to the actuation of the steering such as for example a force feedback.

[0005] For this purpose, it is known to integrate into the steering column of the vehicle 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 conventional mechanical steering.

[0006] In addition to the arrangements linked to the restitution of driving sensations, it is necessary to provide means limiting, in both directions, the angular travel of the steering wheel which, in a conventional mechanical steering system, are generally arranged at the level of the steering rack.

[0007] Such means for limiting the angular travel are particularly necessary for safety reasons in order to avoid damaging various elements and equipment of the steering column such as, for example, electrical connectors and airbag wiring. This risk is particularly significant when the vehicle is stationary, the battery disconnected, and the steering wheel is then easy to turn.

[0008] Due to the absence of a mechanical connection between the steering rack and the drive assembly comprising the steering wheel, it was necessary to integrate into the drive assembly a stop device limiting the travel angular, in both directions, also called “Angular end Stop” or “AeS”.

[0009] According to this design, the end-of-travel angular stop device essentially comprises:

[0010] - a rotating front movement input ring;

[0011] - a fixed rear angular stop ring;

[0012] - and possibly several adjacent rotating intermediate rings which are axially juxtaposed between the front ring and the rear ring,

[0013] and the assembly of components comprising the rotating front ring, the adjacent intermediate rings and the fixed rear ring comprises means for mutually driving a component in rotation by the component which is axially adjacent to it, and comprises means for limiting the angular movement of each component relative to each other component which is adjacent to it.

[0014] In such an arrangement of the angular stop device, the rotating front ring is mounted in rotation around a central steering shaft connected to the steering wheel, such that it drives in rotation the intermediate ring which is adjacent to it as mentioned above when the steering wheel is moved.

[0015] However, for the assembly by axial sliding at least of the rotating front ring around the central steering shaft, radial and / or angular clearances are necessary between the parts. Such clearances between the two parts then cause noise pollution when the steering wheel is used by a user.

[0016] Indeed, the clearances between the rotating front ring and the central steering shaft generate impacts between the latter when the steering wheel is rotated, causing unpleasant noise nuisances for a user.

[0017] Thus, the aim of the invention is to remedy the above problem by proposing a rotation drive assembly for a vehicle steering column which makes it possible to reduce noise pollution during its use. Summary of the invention

[0018] The invention provides a rotational drive assembly for a vehicle steering column, which extends along a longitudinal axis and which is capable of being connected to a steering mechanism mechanically disconnected from the drive assembly, comprising:

[0019] - a fixed support element;

[0020] - a central steering shaft rotatably mounted relative to the fixed support element and capable of being linked in rotation to a steering organ, in particular to a steering wheel;

[0021] - and an end-of-travel angular stop device, limiting the angular travel, in both directions, of the central steering shaft relative to the support element fixed, which includes:

[0022] — a rotating front movement input ring rotatably linked to the central shaft management;

[0023] — a fixed rear angular stop ring rotatably connected to the support element fixed ;

[0024] — and possibly at least one intermediate transmission ring which can rotate relative to the central steering shaft and which is interposed axially between the rotating front ring and the fixed rear ring,

[0025] characterized in that:

[0026] an elastically deformable member is interposed axially between the rotating front ring and an axial support element linked to the central steering shaft, the elastically deformable member being linked in rotation to the rotating front ring and the axial support element and in such a way that the elastically deformable member provides an elastic return function in rotation.

[0027] According to other characteristics of the invention:

[0028] - the elastic return member is mounted axially compressed between the front ring rotating and axial support element;

[0029] - the elastically deformable member comprises two ends and such that the ends apply torsional stress between the rotating front ring and the central steering shaft;

[0030] - the ends of the elastically deformable member extend axially by report to the central steering shaft;

[0031] - the ends of the elastically deformable member extend radially by report to the central steering shaft;

[0032] - the elastically deformable member is a helical spring;

[0033] - the axial support element is formed by a front spacer crossed by the shaft central management;

[0034] - the rotating front ring and the front spacer each comprise at least one housing for receiving one of the ends of the elastically deformable member;

[0035] - at least one of the receiving housings is formed on the external peripheral of the rotating front ring and / or front spacer;

[0036] - at least one of the receiving housings is formed on the internal peripheral of the rotating front ring and / or front spacer. Brief description of the figures

[0037] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0038] [Fig-1] is a schematic representation in section through an axial plane of an assembly training according to the state of the art;

[0039] [Fig.2] is a front three-quarter perspective view of a set training according to the invention;

[0040] [Fig.3] is a partial exploded perspective view of the components of a device end-of-travel angular position of the assembly shown in [Fig.2];

[0041] [Fig.4] is a close-up view of an elastically deformable member disposed between a rotating front ring of the end-of-stroke angular device of [Fig.2] and a front spacer;

[0042] [Fig.5] is a close-up exploded view of the elastically deformable member arranged between the rotating front ring of the angular end-of-travel device of [Fig.2] and the front spacer;

[0043] [Fig.6] is a perspective view of the elastically deformable member according to a another embodiment of the invention;

[0044] [Fig.7] is a perspective view of the elastically deformable member according to a another embodiment of the invention. Detailed description of the invention

[0045] In the following description, identical, similar or analogous elements will be designated by the same reference numbers.

[0046] [Fig.l] schematically shows a rotational drive assembly 10 for a vehicle steering column, capable of being connected to a steering mechanism (not shown) mechanically disconnected from the drive assembly 10.

[0047] This assembly extends along a longitudinal axis “L” which, by non-limiting convention, is oriented axially from the front to the rear of the assembly, from right to left when considering [Fig.l].

[0048] The assembly 10 comprises a central steering shaft 14 which is here a tubular shaft originating from a hollow cylinder, grooved internally and externally.

[0049] A front axial end of the central steering shaft 14 is rotatably connected to a steering wheel 12.

[0050] 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.

[0051] Within the meaning of the invention, the support element 16 is fixed relative to the central steering shaft 14 during the phases of rotation of the steering wheel. 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 retraction of the steering wheel.

[0052] At its rear free end, the assembly 10 comprises a force feedback module 18 or “FFU” which comprises an output shaft 20 which extends axially forward inside the central steering shaft 14 to which its free end 22 is linked in rotation by splines complementary to those located inside the central steering shaft 14.

[0053] The assembly 10 comprises an end-of-travel angular stop device 24 or “AeS” whose function is to limit the angular travel, in both directions, of the central steering shaft 14 relative to the steering tube 16.

[0054] The angular stop device 24 comprises a rotating front ring 26 which is internally grooved to be rotationally connected to the central steering shaft 14 which comprises a grooved external cylindrical surface 15 and a fixed rear angular stop ring 28 which is rotationally connected to the fixed steering tube 16.

[0055] The fixed rear ring 28 is here fixed axially and in rotation to the fixed steering tube 16, for example by a radial screw 29.

[0056] It should also be considered that the rotating front ring 26 and the central steering shaft 14 may have complementarities of different shapes of the splines, as long as these ensure their rotational coupling by angular stop.

[0057] In other words, the central steering shaft 14 can take any shape derived from a cylinder as long as it allows angular stops to be generated with the complementary shape of the rotating front ring, so as to link them in rotation to each other.

[0058] Furthermore, the rotating front ring 26 is mounted to slide axially around a section of the central steering shaft 14. Thus, radial and / or angular clearances are necessary between the rotating front ring 26 and the central steering shaft 14 in order to allow the rotating front ring 26 to be mounted in axial sliding manner on the central steering shaft 14.

[0059] It should also be considered that manufacturing tolerances of the rotating front ring 26 and of the central steering shaft 14 contribute to forming radial and / or angular clearances between the two parts.

[0060] Such radial and / or angular clearances are however not such as to prevent the rotational connection of the rotating front ring 26 with the central steering shaft 14 as mentioned above.

[0061] 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.

[0062] Thus, the angular stop device 24 comprises a set of adjacent components juxtaposed axially, comprising the rotating front ring 24, the intermediate rings 30i and the fixed rear ring 28.

[0063] The axial stacking of the components and the compensation of the clearances is ensured by means of an elastically deformable member 32 which is interposed axially between an axial support element linked to the shaft and a front radial face opposite the rotating front ring 26.

[0064] According to a non-limiting example of the invention, the axial support element is a shoulder formed on the shaft.

[0065] According to another non-limiting example of the invention, the axial support element is a spacer 34.

[0066] It is understood that the elastically deformable member 32 exerts axial pressure on the components of the angular stop device 24.

[0067] Furthermore, the elastically deformable member 32 is configured to provide an elastic return function in rotation between the rotating front ring 26 and the front spacer 34.

[0068] In the illustrated and non-limiting example of the invention, the elastically deformable member 32 is a spring which has a helical shape.

[0069] A main helical direction of the elastically deformable member 32 is then defined.

[0070] According to a characteristic of the invention, the elastically deformable member 32 comprises at least one straight end 33 relative to the main helical direction of the elastically deformable member 32.

[0071] In other words, the elastic deformable member 32 according to the example of the invention illustrated is presented as a spring with helical winding and the straight ends 33 of which form rectilinear branches parallel to the longitudinal axis L.

[0072] According to the illustrated example of the invention visible in Figures 4 to 7, each of the two ends 33 of the elastically deformable member has a rectilinear profile relative to the main helical direction of the elastically deformable member 32.

[0073] More precisely, the two free ends 33 of the elastically deformable member 32, here the spring, extend axially along the central steering shaft 14 and opposite each other.

[0074] The free ends 33 of the elastically deformable member 32 are defined as end portions of the latter with dimensions between 1 mm and 10 mm.

[0075] Thus, it is understood that the elastically deformable member 32 extends here, mainly in a helical manner around the central steering shaft 14, being coaxial with the latter, and comprises two free ends 33 which extend in a rectilinear manner, here axially along the central steering shaft 14.

[0076] Alternatively and visible in [Fig.6], it can be provided that the free ends 33 of the elastically deformable member 32 extend radially in the direction of the central steering shaft or radially opposite the central steering shaft as visible in [Fig.7] relative to the longitudinal axis L.

[0077] According to a characteristic of the invention visible in figures 4 and 5, the rotating front ring 26 and the front spacer 34 each comprise a receiving housing 60 for the end 33 of the free elastically deformable member 32 intended to cooperate with the latter.

[0078] The receiving housings 60 are here formed in a non-limiting manner on the outer perimeter of the rotating front ring 26 so as to take the form of a slot and in the thickness of the front spacer 34 so as to form an axial hole.

[0079] Alternatively and not shown, the receiving housing may be formed on the inner perimeter of the rotating front ring and / or the front spacer.

[0080] The receiving housings 60 take the form of a clearance of material from the rotating front ring 26 and the front spacer 34 which here extend along the longitudinal axis L.

[0081] Furthermore, the receiving housings 60 are configured to form an angular stop of the ends 33 of the elastically deformable member 32 relative to the rotating front ring 26 and the front spacer 34.

[0082] It should also be considered that the shape of the receiving housing 60 of one and the other of the rotating front ring and the front spacer may be interchanged, different or identical between the two parts.

[0083] Furthermore and in a manner not shown, it may be provided that the rotating front ring and / or the front spacer each comprise several angularly adjacent receiving housings so as to allow optimal adjustment of the free ends of the elastically deformable member as a function of the expected torsional load.

[0084] According to a characteristic of the invention, the receiving housings formed on the rotating front ring 26 and on the front spacer 34 are angularly offset relative to each other.

[0085] Such a configuration of the elastically deformable member 32 as just described then makes it possible to overcome the presence of radial and / or angular clearances between the rotating front ring 26 and the central steering shaft 14 described previously by the application of a torsional stress applied to the rotating front ring by the elastically deformable member, thus making it possible to avoid jolts of the rotating front ring on the central steering shaft.

[0086] Thus, the elastically deformable member 32 according to the invention, and in particular its ex free ends 33 allow torsional stresses to be generated between the rotating front ring 26 and the central steering shaft 14, eliminating impact noises during contact between these two parts while the steering wheel is being moved by a user.

[0087] Indeed, the torsional stress applied between the rotating front ring 26 and the central steering shaft 14 makes it possible to reduce the consequences of play, for example between the complementary splines of the rotating front ring 26 and the central steering shaft 14, by eliminating the noise generated by the contact of these two parts during the rotational drive of the rotating front ring 26 by the central steering shaft 14 when the steering wheel is moved by a user.

[0088] Furthermore, the angular offset of the receiving housings formed on the rotating front ring 26 and on the front spacer 34 makes it possible to optimize the elastic return function in rotation of the elastically deformable member 32, between the rotating front ring 26 and the front spacer 34.

[0089] In relation to [Fig. 1], the rotating front ring 26 allows, by its rotation via the central rotation shaft 14 as described previously, to transmit the torque from the central rotation shaft 14 to the intermediate rings 30-i.

[0090] 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.

[0091] The intermediate ring 30-4 which is adjacent to the fixed rear ring 28 cooperates with the latter to come into angular abutment in one or the other direction.

[0092] In the illustrated example of the invention in Figures 2 and 3 and in a non-limiting manner, the end-of-travel angular stop device 24 comprises a series of eight adjacent and axially juxtaposed intermediate rings 30i.

[0093] As can be seen in [Fig.3], the rotating front ring 26 comprises a plate-shaped annular central body 40 whose front annular radial face 42 is smooth, while its rear annular radial face comprises a radially inner convex cylindrical centering bearing surface 46, which extends axially rearward from the annular central body 40.

[0094] The convex cylindrical bearing surface 46 comprises 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 surface 46.

[0095] As can be seen in [Fig.3], the fixed rear ring 28 comprises a hollow cylindrical body 140 which, in its front annular face, comprises a concave cylindrical centering surface 150, radially external, which is open axially towards the front.

[0096] The concave cylindrical bearing surface 150 here comprises a pair of stop tabs 149 which are diametrically opposed and which extend axially forward here over the entire axial width of the concave cylindrical centering surface 150.

[0097] As can be seen in [Fig.2], each intermediate ring 30i comprises a plate-shaped annular central body 240 whose rear annular radial face comprises a radially inner, convex cylindrical centering bearing surface 246 which extends axially rearward from the annular central body 240.

[0098] The convex cylindrical bearing surface 246 here comprises a pair of radially external drive lugs 248 which are diametrically opposed and which extend axially rearward here over the entire axial width of the convex cylindrical centering bearing surface 246.

[0099] In its front annular face, the central body 240 comprises a concave cylindrical centering surface 250, radially external, which is open axially towards the front.

[0100] The concave cylindrical bearing surface 250 here comprises 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 centering bearing surface 250.

[0101] Thus, an intermediate ring is centered radially relative to another ring which is axially adjacent to it due to the cooperation of a convex centering surface 246 which is received axially in a complementary concave cylindrical surface 250 of the other adjacent ring.

[0102] Each intermediate ring 30i is rotatable relative to the central steering shaft 14 and is axially traversed by the central steering shaft 14 with a radial clearance between the external peripheral edge of the central rotation shaft and the internal peripheral surface of its central bore.

[0103] The angular movement of an intermediate ring 30i relative to another intermediate ring adjacent to it is delimited by the cooperation of the legs 249 and the legs 248 which are angularly interposed.

[0104] 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 surface 250 with the complementary convex cylindrical centering surface 46.

[0105] The angular movement of the intermediate ring 30-1 relative to the rotating front ring 26 which is adjacent to it is delimited by the cooperation of the lugs 249 and the lugs 48 which are interposed.

[0106] 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 surface 246 with the complementary concave cylindrical centering surface 150.

[0107] The angular movement of the intermediate ring 30-8 relative to the ring fixed rear 28 which is adjacent to it is delimited by the cooperation of the legs 149 with the legs 248 which are angularly intercalated.

[0108] Without departing from the scope of the invention, as a variant by mechanical inversion, the end-of-travel angular stop device can for example be on the shaft 20, with the fixed ring linked to the element 16 and the rotating ring linked to the 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 for 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) connected in rotation to the central steering shaft (14); - a fixed rear angular stop ring (28) connected in rotation to the fixed support element (16);— and optionally 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: an elastically deformable member (32) is interposed axially between the rotating front ring (26) and an axial support element linked to the central steering shaft (14), the elastically deformable member (32) being linked in rotation to the rotating front ring (26) and the axial support element and in such a way that the elastically deformable member (32) provides an elastic return function in rotation.;

2. Assembly (10) according to the preceding claim, in which the elastic return member (32) is mounted axially compressed between the rotating front ring (26) and the axial support element.

3. An assembly (10) according to any preceding claim, wherein the elastically deformable member (32) comprises two ends (33) and such that the ends (33) apply a torsional stress between the rotating front ring (26) and the central steering shaft (14).

4. Assembly (10) according to the preceding claim, in which the ends (33) of the elastically deformable member (32) extend axially relative to the central steering shaft (14).

5. An assembly (10) according to claim 3, wherein the ends (33) of the elastically deformable member (32) extend radially relative to the central steering shaft (14).

6. An assembly (10) according to any preceding claim, wherein the elastically deformable member (32) is a helical spring.

7. Assembly (10) according to any one of the preceding claims, in which the axial support element is formed by a front spacer (34) crossed by the central steering shaft (14).

8. Assembly (10) according to any one of claims 3 to 6 in combination with claim 7, in which the rotating front ring (26) and the front spacer (34) each comprise at least one receiving housing (60) of one of the ends (33) of the elastically deformable member (32).

9. Assembly (10) according to the preceding claim, in which at least one of the receiving housings (60) is formed on the outer periphery of the rotating front ring (26) and / or the front spacer (34).

10. An assembly (10) according to claim 8, wherein at least one of the receiving housings (60) is formed on the inner periphery of the rotating front ring (26) and / or the front spacer (34).

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