Steering column drive assembly with an angular limit switch device

Abstract

The present invention relates to a steering column rotation drive assembly comprising a fixed support element (16), a steering shaft (14), and an angular limit stop device. This assembly includes a rotating front ring (26) rotationally connected to the steering shaft, a fixed rear angular stop ring (28), and at least one intermediate transmission ring (30i) axially interposed between the rotating front ring (26) and the fixed rear ring (28). The rotating front ring (26), the at least one intermediate ring (30i), and the fixed rear ring (28) comprise means for mutually rotating the assembly. The assembly is characterized in that each rotating front ring (26) and the fixed rear ring (28) comprises means for radially centering the intermediate ring (30i), which is traversed axially with radial clearance by the central steering shaft (14). Figure for the abstract: 3

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, comprising an angular stop device for limiting the angular travel, in both directions, of the drive assembly.

[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 comprising 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 is necessary to integrate into the drive assembly a stop device limiting the angular travel, in both directions, also called “Angular end Stop” or “Aes”.

[0009] An example of the general design of such an end-of-travel angular stop device is for example described and represented in patent application US2018 / 0105198A1.

[0010] The general design of a drive assembly incorporating such a stop device according to the state of the art is also illustrated schematically in [Fig.l] attached to this description.

[0011] According to this design, the end-of-travel angular stop device essentially comprises: - a rotating front movement input ring; - a fixed rear angular stop ring; - and possibly several adjacent rotating intermediate rings which are juxtaposed axially between the front ring and the rear ring, 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.

[0012] According to this design, the intermediate rings are guided in rotation on a central steering shaft which is capable of being connected in rotation to a steering member, in particular to a steering wheel, and which axially passes through the angular stop device.

[0013] Each intermediate ring thus ensures the transmission to the ring adjacent to it of the torque applied to it by the rotating front ring or by another adjacent ring.

[0014] This results in friction between each intermediate ring and the central steering shaft on which they are mounted rotating, which results in the creation of significant friction torques.

[0015] As a result, the average value of the torque to be applied to the steering wheel by the driver is high and, moreover, this average value increases as a function of the angular travel applied to the steering wheel by the driver.

[0016] The invention aims to reduce the impact of the angular stop device on the average value of the torque to be applied to the steering wheel and to have a stable average value of the friction torque throughout the angular travel applied to the steering wheel. Summary of the invention

[0017] The invention provides a rotation drive assembly for a column of vehicle steering, capable of being connected to a steering mechanism mechanically disconnected from the drive assembly, comprising: - a fixed support element; - a central steering shaft mounted to rotate relative to the fixed support element and capable of being connected in rotation to a steering member, in particular to a steering wheel; - and an end-of-travel angular stop device, limiting the angular travel, in both directions, of the central steering shaft relative to the fixed support element, which comprises: — a rotating front movement input ring linked in rotation to the central steering shaft; — and a fixed rear angular stop ring rotationally linked to the fixed support element; and in which the set of components comprising the rotating front ring and the fixed rear ring comprises means for mutually driving a component in rotation by the component adjacent to it and comprises means for limiting the angular movement of each component relative to each other component adjacent to it, characterized in that the rotating front ring and the fixed rear ring each comprise means for radially centering one ring relative to the other.

[0018] According to other characteristics of the invention: - the end-of-travel angular stop device comprises an 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, the assembly of components comprising the rotating front ring, the intermediate ring and the fixed rear ring comprises means for mutually driving a component in rotation by the component adjacent to it and comprises means for limiting the angular movement of each component relative to each other component adjacent to it, and in that the rotating front ring and the fixed rear ring each comprise means for radially centering the intermediate ring which is axially traversed with radial play by the central steering shaft; - the end-of-travel angular stop device comprises several adjacent intermediate transmission rings which are axially juxtaposed between the rotating front ring and the fixed rear ring; the set 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 adjacent to it and comprises means for radially centering each intermediate ring relative to each component axially adjacent to it; each intermediate ring is axially crossed with radial play by the central steering shaft; - said radial centering means between a component and another component adjacent to it comprise a convex, radially inner, cylindrical centering surface belonging to said one component and a complementary concave, radially outer, cylindrical centering surface belonging to said other component which cooperates with said convex cylindrical centering surface; - each intermediate ring comprises an annular central body; a radially inner, convex cylindrical centering bearing surface, which extends axially rearward from the annular central body; a radially outer, concave cylindrical centering bearing surface, which extends axially forward from the annular central body; - each convex cylindrical bearing surface is provided with a pair of radially external drive lugs, and each concave cylindrical bearing surface is provided with a pair of radially internal drive lugs capable of cooperating with said radially external drive lugs; - the end-of-travel angular stop device comprises an axial compression spring which is interposed between a support element which is axially secured to the central steering shaft and the rotating front ring which is mounted to slide axially on the central steering shaft; - the rotating front ring and each intermediate ring is provided with an element absorbing the angular shocks occurring between said components; - at one end, the assembly comprises a force feedback module which comprises an output shaft which extends axially inside the central steering shaft to which its free end is linked in rotation by splines complementary to splines of the central steering shaft. Brief descriptions of the figures

[0019] 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:

[0020] [Fig-1] - [Fig.l] is a schematic representation in section through an axial plane of a training assembly according to the state of the art;

[0021] [Fig.2] - [Fig.2] is a front three-quarter perspective view of an exemplary embodiment of a drive assembly according to the invention;

[0022] [Fig.3] - [Fig.3] is a partial sectional view through an axial plane of the assembly shown in [Fig.2];

[0023] [Fig.4] - [Fig.4] is a partial exploded perspective view of the components of the end-of-travel angular stop device of the assembly shown in Figures 2 and 3 ;

[0024] [Fig.5A] - [Fig.5A] is a detail view in perspective and on a larger scale of a transmission ring belonging to the device shown in [Fig.4];

[0025] [Fig.5B] - [Fig.5B] is a view similar to that of [Fig.5A] in which the transmission ring is shown from another perspective angle;

[0026] [Fig.6] - [Fig.6] is a detail view in perspective and on a larger scale of a transmission ring belonging to the device shown in [Fig.4] which is equipped with its angular shock absorber element;

[0027] [Fig.7] - [Fig.7] is a detail view in perspective and on a larger scale of the rotating front ring belonging to the device shown in [Fig.4];

[0028] [Fig.8] - [Fig.8] is a detail view in perspective and on a larger scale of the fixed rear ring belonging to the device shown in [Fig.4];

[0029] [Fig.9] - [Fig.9] is a detail view on a larger scale and in section through a plan radial of the assembly represented in figures 2 and 3. Detailed description of the invention

[0030] In the following description, identical, similar or analogous elements will be designated by the same reference numbers.

[0031] Example of embodiment according to the state of the art - [Fig. 1] [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.

[0032] 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].

[0033] The assembly 10 comprises a central steering shaft 14 which is here a tubular shaft splined externally and internally, the front axial end of which is connected in rotation to a steering wheel 12.

[0034] 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.

[0035] 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.

[0036] 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 here linked in rotation by splines complementary to those of the central steering shaft 14.

[0037] 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, and thus to limit the angular travel of the steering wheel.

[0038] 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, and a fixed rear angular stop ring 28 which is rotationally connected to the fixed steering tube 16.

[0039] The fixed rear ring is here fixed axially and in rotation to the fixed steering tube 16, for example by means of a radial screw 29.

[0040] Between the rotating front ring 26 and the fixed rear ring 28, the angular stop device 24 here comprises a series of adjacent intermediate rings 30i which are axially juxtaposed.

[0041] Thus, the angular stop device 24 comprises a set of adjacent components juxtaposed axially comprising the rotating front ring 26, the intermediate rings 30i and the fixed rear ring 28.

[0042] Without limitation, the number of intermediate rings represented 30i is here equal to four.

[0043] The axial stacking of the components and the compensation of the clearances 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.

[0044] In a known manner, the function of the intermediate rings consists of transmitting to the ring adjacent to it the torque applied to it by the rotating front ring or by another adjacent ring.

[0045] 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.

[0046] 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.

[0047] According to the state-of-the-art design illustrated in [Fig. 1] each intermediate transmission ring 30i is centered and rotationally guided on the grooved outer cylindrical surface 15 of the central steering shaft 14.

[0048] The intermediate transmission rings 30i are in frictional contact, in particular with the steering shaft 14 on the inner diameter 252 of the transmission rings.

[0049] Thus, by way of non-limiting example, along the angular travel applied to the steering wheel 12 in one direction of rotation: - From 0 to 60 degrees of angle there is friction between the rotating front ring 26 and the ring 30-1 until they come into mutual angular abutment; From 60 to 120 degrees of angle there is friction between rings 30-1 and 30-2 and friction between ring 30-1 and the central steering shaft 14-15; From 120 to 180 degrees of angle there is friction between rings 30-2 and 30-3 and friction between rings 30-1 and 30-2 and the central steering shaft 14-15; From 180 to 240 degrees of angle there is friction between rings 30-3 and 30-4 and friction between rings 30-1, 30-2 and 30-3 and the central steering shaft 14-15; From 240 to 300 degrees of angle there is friction between the ring 30-4 and the fixed rear ring 28 and friction between all four rings 30i and the central steering shaft 14-15.

[0050] Example of embodiment according to the invention - Figures 2 to 9 By way of non-limiting example, the main components of the end-of-travel angular stop device 24 are the rotating front ring 26, the fixed rear ring 28 and here a series of adjacent and axially juxtaposed intermediate rings 30i which are all identical.

[0051] The intermediate transmission rings 30i are here eight in number (30-1 to 30-8).

[0052] The central steering shaft 14 is externally splined as is the rotating front ring 26 which is internally splined.

[0053] As can be seen in Figures 4 and 7, 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 44 comprises a radially internal, convex cylindrical centering bearing surface 46, which extends axially rearward from the annular central body 40.

[0054] The convex cylindrical bearing surface 46 comprises a pair of drive lugs 48 which are diametrically opposed and which extend axially rearwardly, over a portion of the axial width of the convex cylindrical centering bearing surface 46.

[0055] As can be seen in Figures 2 and 8, the fixed rear ring 28 comprises a hollow cylindrical body 140 which, in its front annular face 144, comprises a concave cylindrical centering surface 150, radially external, which is open axially towards the front.

[0056] 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 a portion of the axial width of the concave cylindrical centering bearing surface 150.

[0057] As can be seen in Figures 5A and 5B, each intermediate ring 30i comprises a plate-shaped annular central body 240 whose rear annular radial face 244 comprises a radially inner convex cylindrical centering bearing surface 246, which extends axially rearward from the annular central body 240.

[0058] 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 a portion of the axial width of the convex cylindrical centering bearing surface 246.

[0059] In its front annular face 244, the central body 240 comprises a concave cylindrical centering surface 250, radially external, which is open axially towards the front.

[0060] 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 a portion of the axial width of the concave cylindrical centering bearing surface 250.

[0061] 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.

[0062] Thus, each intermediate ring 30i - which is interposed between two adjacent intermediate rings 30i-1 and 30i+1 - is centered radially between these two adjacent intermediate rings.

[0063] Each intermediate ring 30i rotates relative to the central steering shaft 14 and, as can be seen in particular in [Fig.9], is axially traversed by the central steering shaft 14 with a radial clearance “J” between the outer peripheral surface 15 of the outer splines and the inner peripheral surface 252 of its central bore.

[0064] 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.

[0065] 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.

[0066] The angular movement of the intermediate ring 30-1 relative to the front ring rotating 26 which is adjacent to it is delimited by the cooperation of the legs 249 and the legs 48 which are intercalated.

[0067] 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.

[0068] The angular movement of the intermediate ring 30-8 relative to the fixed rear ring 28 which is adjacent to it is delimited by the cooperation of the lugs 149 with the lugs 248 which are angularly interposed.

[0069] As a variant, when the device 24 does not include an intermediate ring interposed between the rotating front ring 26 and the fixed rear ring, these two rings 26 and 28 are centered radially relative to each other and drive each other in rotation with a limited capacity for angular movement.

[0070] The cooperation of the different legs 48, 249, 248 and 149 is likely to generate impact noises when they come into circumferential contact with each other.

[0071] Due to the arrangement of the end-of-travel angular stop device 24 in the upper part of the steering column and therefore of the passenger compartment of the vehicle, such noises are likely to harm the comfort of the occupants of the vehicle.

[0072] As a supplement, but not obligatory, the end-of-travel angular stop device 24 is here equipped with a series of nine annular angular or circumferential shock-absorbing elements 54 which are here all identical.

[0073] As can be seen in [Fig.6], an annular shock-absorbing element 54 is in the form of an annular ring which is made of an elastically compressible material such as, for example, natural or synthetic rubber.

[0074] Each intermediate ring 30i is provided with a shock-absorbing annular element 54 which is mounted on an axial extension 247 of reduced diameter of its convex cylindrical centering surface 246.

[0075] In the same way, the rotating front ring 26 is provided with an annular shock element 54 which is mounted on an axial extension 47 of reduced diameter of its convex cylindrical centering surface 46.

[0076] Each annular shock-absorbing element 54 also comprises two diametrically opposed portions 56, each of which follows the contour of an associated tab 248 or 48.

[0077] Each portion 56 is circumferentially “overthick” and is compressible between two opposite tabs (48-249, 248-249, or 248-149) to absorb contact shocks between these tabs.

[0078] 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. 10

Claims

Claims

1. Assembly (10) for driving a vehicle steering column in rotation, 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 to rotate 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); — and a fixed rear ring (28) of angular stop linked in rotation to the fixed support element (16); and in which the assembly of components comprising the rotating front ring (26) and the fixed rear ring (28) comprises means (48, 249, 248) for mutually driving a component in rotation by the component adjacent to it and comprises means (48, 149) for limiting the angular movement of each component relative to each other component adjacent to it, characterized in that the rotating front ring (26) and the fixed rear ring (28) each comprises means (46, 150) for radially centering one ring relative to the other.

2. Assembly according to claim 1, characterized in that the end-of-travel angular stop device (24) comprises an 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), in that the assembly of components comprising the rotating front ring (26), the intermediate ring (30i) and the fixed rear ring (28) comprises means (48, 249, 248) for mutually driving a component in rotation by the component adjacent to it and comprises means (48, 249, 248, 149) for limiting the angular movement of each component relative to each other component adjacent to it, and in that the rotating front ring (26) and the fixed rear ring (28) each comprise means (46, 250, 150) for radially centering the ring intermediate (30i) which is axially crossed with a radial clearance (J) by the central steering shaft (14).

3. Assembly (10) according to claim 2, characterized in that: - the end-of-travel angular stop device (24) comprises several adjacent intermediate transmission rings (30i) which are axially juxtaposed between the rotating front ring (26) and the fixed rear ring (28); - the assembly of components comprising the rotating front ring (26), the adjacent intermediate rings (30i) and the fixed rear ring (28) comprises means (48, 249, 248) for mutually driving a component in rotation by the component adjacent to it and comprises means (46, 250, 150) for radially centering each intermediate ring (30i) relative to each component axially adjacent to it; - each intermediate ring (30i) is axially traversed with a radial clearance (J) by the central steering shaft (14).

4. Assembly (10) according to any one of the preceding claims, characterized in that said radial centering means between a component and another component adjacent thereto comprise a convex cylindrical centering surface (46, 246), radially inner, belonging to said one component (26, 30i) and a complementary concave cylindrical centering surface (250, 150), radially outer, belonging to said other component (30i, 28) which cooperates with said convex cylindrical centering surface (46, 246).

5. Assembly (10) according to claim 4 taken in combination with claim 3, characterized in that each intermediate ring (30i) comprises: - an annular central body (240); - a convex cylindrical centering surface (246), radially inner, which extends axially towards the rear from the annular central body (240); - a concave cylindrical centering surface (250), radially outer, which extends axially towards the front from the annular central body (240).

6. Assembly (10) according to the preceding claim, characterized in that each convex cylindrical bearing surface (246) is provided with a pair of radially external drive lugs (248), and in that each concave cylindrical bearing surface (250) is provided with a pair of radially internal drive lugs (249) capable of cooperating with said radially external drive legs (248).

7. Assembly according to any one of the preceding claims, characterized in that the end-of-travel angular stop device (24) comprises an axial compression spring which is interposed between a support element (34) which is axially secured to the central steering shaft (14) and the rotating front ring (26) which is mounted to slide axially on the central steering shaft (14).

8. Assembly (10) according to one of claims 3 or 4, characterized in that the rotating front ring and each intermediate ring (30i) is provided with an element (54) absorbing the angular shocks occurring between said components.

9. Assembly according to any one of the preceding claims, characterized in that, at one end, it comprises a force feedback module (18) which comprises an output shaft (20) which extends axially inside the central steering shaft (14) to which its free end (22) is linked in rotation by splines complementary to splines of the central steering shaft (14).

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