STEERING SYSTEM WITH A GUIDE OF A SHOCK ABSORPTION BLADE

Abstract

A steering system for a motor vehicle, including a steering casing, having a hollow guide conduit extending along a longitudinal axis, a steering column including an upper tube, disposed in the guide conduit and displaceable in translation relative to the steering casing along the longitudinal axis mounted on the steering casing and driving a drive member in displacement parallel to the longitudinal axis, an absorption blade including a first portion, secured to the upper tube, and a second portion, secured to the drive member, the first portion and the second portion extending parallel to the longitudinal axis opposite to each other and being connected by a bent portion, the second portion has at least one stop in contact with the first portion, so as to prevent a relative approaching between the second portion and the first portion.

Claims

1. A steering system for a motor vehicle, said steering system including: a steering casing, having a hollow guide conduit extending along a longitudinal axis, a steering column comprising an upper tube coupled to a steering wheel, disposed in the guide conduit and displaceable in translation relative to the steering casing along the longitudinal axis thanks to motorized actuating means, mounted on said steering casing and driving a drive member in displacement parallel to the longitudinal axis, an absorption blade, provided to undergo a deformation under the effect of a shock exerted on the steering wheel along the longitudinal axis, said absorption blade including a first portion, secured to the upper tube, and a second portion, secured to the drive member, said first portion and said second portion extending parallel to the longitudinal axis opposite to each other and being connected by a bent portion, said steering system wherein said second portion has at least one stop in contact with said first portion, so as to prevent a relative approaching between said second portion and said first portion.

2. The steering system according to claim 1, wherein the first portion and the second portion each have an upper end and a lower end, the bent portion of the absorption blade joining said upper ends to each other, and wherein the stop(s) of the second portion is/are disposed in the vicinity of the lower end of said second portion.

3. The steering system according to claim 1, wherein the stop(s) is/are linear and extend parallel to the longitudinal axis.

4. The steering system according to claim 1, wherein the second portion has a strip provided with two opposite longitudinal sides, and two lateral wings, folded along said respective longitudinal sides towards the first portion, said lateral wings having longitudinal edges forming the stops.

5. The steering system system according to claim 4, wherein the lateral wings of the second portion are parallel to each other and orthogonal to the first portion.

6. The steering system according to claim 4, wherein the first portion has a strip provided with two opposite longitudinal sides, and two lateral protrusions protruding from said respective longitudinal sides and extending coplanar with said strip, and wherein the longitudinal edges of the lateral wings of the second portion are in contact with the respective lateral protrusions of the first portion.

7. The steering system according to claim 1, including a guide rail secured to the upper tube and the first portion, said guide rail extending parallel to the longitudinal axis and being adapted to: guide the absorption blade in its deformation under the effect of a shock exerted on the upper tube along the longitudinal axis, and prevent a relative distance between the second portion and the first portion.

8. The steering system according to claim 7, wherein the second portion has opposite inner face and outer face, where said inner face faces the first portion, and wherein the guide rail has at least one stopper in contact with said outer face of the second portion.

9. The steering system according to claim 8, wherein the guide rail has a U-shaped section, by comprising: a central portion secured to the upper tube and on which the first portion is fastened, and two opposite branches between which the absorption blade is disposed, wherein said branches are provided with respective folded longitudinal flanges, each of said folded longitudinal flanges extending parallel to the first portion and forming a stopper in contact with the outer face of the second portion.

10. The steering system according to claim 4, wherein the branches of the guide rail are in contact with the respective lateral wings of the second portion.

11. The steering system according to claim 6, wherein the lateral protrusions of the first portion are positioned in abutment against the respective branches of the guide rail.

12. The steering system according to claim 1, wherein the first portion and the second portion of the absorption blade define an empty interstitial space therebetween, devoid of element in simultaneous contact with the first portion and the second portion.

13. The steering system according to claim 1, wherein the motorized actuating means comprise a geared motor, mounted on the steering casing and allowing driving in rotation a worm screw about a direction parallel to the longitudinal axis, said worm screw cooperating with the drive member, fastened on the second portion of the absorption blade, so as to drive said second portion in a translational movement in a direction parallel to the longitudinal axis.

Description

[0071] Other features and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:

[0072] FIG. 1 is an exploded view of a steering system according to the invention;

[0073] FIG. 2 is a perspective view of an upper tube, a guide rail and an absorption blade according to the invention;

[0074] FIGS. 3a and 3b are detailed views of an absorption blade according to the invention;

[0075] FIGS. 4a and 4b are detailed views of a guide rail according to the invention.

[0076] With reference to FIG. 1, a steering system 1 according to the invention includes a steering casing 2 having a hollow guide conduit 21, this guide conduit 21 extending along a longitudinal axis D and having a circular section.

[0077] An upper tube 3 is disposed in these guide conduits 21, such that this upper tube 3 is displaceable in translation, in the guide conduit 21, relative to the steering casing 2 along the longitudinal axis D.

[0078] On this upper tube 3 a guide rail 4 is fastened, inside which an absorption blade 5 is positioned.

[0079] The particular features of this guide rail 4 and of this absorption blade 5 will be described further below.

[0080] The absorption blade 5 includes a first portion 51 and a second portion 52 connected by a bent portion 53, the first portion 51 and the second portion 52 being parallel to each other and parallel to the longitudinal axis D.

[0081] The first portion 51 is fastened on a central portion 41 of the guide rail 4, while the second portion 52 is fastened, thanks to screws 6, to a drive member 7 at a lower end 521.

[0082] A perspective view of the upper tube 3, the guide rail 4 and the absorption blade 5 is shown in FIG. 2.

[0083] The drive member 7 cooperates with actuating means (not represented), mounted on the steering casing 2 and adapted to displace the drive member 7 in a drive direction D parallel to the longitudinal axis D.

[0084] For example, the actuating means may comprise a geared motor shown on a platform 22 of the steering casing 2, this geared motor allowing driving in rotation, about the drive direction D, a worm screw cooperating with a tapped hole 71 of the drive member 7, so as to drive the latter in translation along the drive direction D.

[0085] Thus, the actuating means allow, via the drive member 7 and the absorption blade 5, driving the upper tube 3 in translation along the longitudinal axis D.

[0086] This first operating mode of the steering system 1 according to the invention corresponds to a normal adjustment mode of the axial position of the steering wheel of a motor vehicle, for example when switching from a manual driving mode to an autonomous driving mode for an autonomous type motor vehicle.

[0087] In this first mode of operation, the translational movement of the upper tube 3 is triggered by a low intensity force exerted on the second portion 52 of the absorption blade 5 by the actuating means 7 (via the drive member).

[0088] Under the effect of this low intensity force, the absorption blade 5 remains rigid and retains its initial shape without undergoing a deformation, transmitting this force to the guide rail 4 then to the upper tube 3.

[0089] In a second accidental operating mode of the steering system 1 according to the invention, following a frontal shock undergone by the motor vehicle, a high intensity force is exerted on the upper tube 3 along the longitudinal axis D, due to an impact of the driver against the steering wheel mounted on the upper tube 3.

[0090] This force is transmitted, via the guide rail 4, to the first portion 51 of the absorption blade 5.

[0091] Under the effect of this significant effort, the absorption blade 5 undergoes a deformation inside the guide rail 4, in order to allow a translational movement of the upper tube 3 along the longitudinal axis D: this translational movement allows absorbing a portion of the shock undergone by the driver of the motor vehicle during his impact against the steering wheel.

[0092] More specifically, during this deformation, the first portion 51 is driven in translation parallel to the longitudinal axis by the upper tube 3, while the upper end 521 of the second portion 52, secured to the drive member 7 itself connected to the actuating means, remains stationary: the first portion 51 is thus forced to advance parallel to the longitudinal axis D and in the direction of the lower end 521 of the second portion 52, thus causing a displacement of the bent portion 53 along the absorption blade 5, also in the direction of the lower end 521.

[0093] Thus, the first portion 51 undergoes an elongation and the second portion 52 undergoes a shortening during the deformation of the absorption blade 5, this first portion 51 and this second portion 52 remaining parallel to the longitudinal axis D.

[0094] It is important to note that this specific deformation of the absorption blade 5 is made possible by the particular structure of the absorption blade 5 and the guide rail 4, which allows forcing the particular displacement of the first portion 51, from the second portion 52 and the bent portion 53.

[0095] Indeed, as shown in FIG. 3, the second portion 52 includes a strip 522 provided with two folded lateral wings 523 along two opposite longitudinal sides 524: these longitudinal wings 523 are parallel to each other and extend towards the first portion 51, orthogonally to the same first portion 51.

[0096] Moreover, the first portion 51 has a strip 511 provided with two opposite longitudinal sides 512, each of these longitudinal sides 512 including a lateral protrusion 513 coplanar with the first portion 51.

[0097] The absorption blade 5 is configured so that each of the lateral wings 523 has a longitudinal edge 526 in contact with one of the lateral protrusions 513, these lateral wings 523 thus forming a stop between the second portion 52 and the first portion 51.

[0098] Due to the contact between the lateral wings 523 and the first portion 51, the first portion 51 and the second portion 52 cannot be brought closer to each other during the deformation of the absorption blade 5, the presence of the lateral wings 523 between the second portion 52 and the first portion 51 physically blocking such an approaching.

[0099] On the other hand, as shown in FIG. 4, the guide rail 4 has a central portion 41 (on which the first portion 51 is fastened) and two branches 42 parallel to each other and orthogonal to the central portion 41.

[0100] Each of these branches 42 includes a folded longitudinal flange 43 extending parallel to the central portion 41 (and therefore, parallel to the first portion 51): this guide rail 4 is shaped so that the longitudinal flanges 43 are in contact with an upper face 525 of the second portion 52.

[0101] The longitudinal flanges 43 thus form a stopper allowing preventing a relative distance between the second portion 52 and the first portion 51.

[0102] In addition, as shown in FIG. 2, the lateral wings 523 of the absorption blade 5 are in contact with the branches 42 of the guide rail 4.

[0103] Thus, the deformation of the absorption blade is guided by the combination of three constraints: [0104] the contact between the lateral wings 523 of the absorption blade 5 and the branches 42 of the guide rail 4 prevents any lateral displacement of the second portion 52 and of the first portion 51, which can be displaced in translation only parallel to the longitudinal axis D, [0105] the contact between the lateral wings 523 and the protrusions 513 prevents any approaching between the first portion 51 and the second portion 52, and [0106] the contact between the longitudinal flanges 43 and the outer face 525 of the second portion 52 prevents any relative distance between the first portion 51 and the second portion 52.

[0107] When a significant force is exerted on the upper tube 3 along the longitudinal axis D, the absorption blade 5 is then forced to be deformed in the previously described manner due to these three constraints.

[0108] In particular, the first portion 51 and the second portion 52 remain permanently parallel to each other during this deformation, and the bent portion 53 maintains a constant radius of curvature: this feature allows a regular absorption of the shock undergone by the driver of the motor vehicle during his impact against the steering wheel, leading to better protection of the latter.

[0109] The steering system 1, according to the invention, therefore allows ensuring that the deformation of the absorption blade 5 in the case of an accident is carried out so that the first portion 51 and the second portion 52 remain parallel to each other, using only one guide rail 4 and a specific shape secured to the absorption blade 5.