The invention relates to an antitheft device for a steering column of a vehicle.

These devices generally include a latch of an ignition key of the vehicle, as well as a bolt adapted to lock the movement of the steering column of a car. The main function of such devices is to lock the movement of the steering column whenever this movement is not authorized.

Generally, the unlocking of the antitheft device is done by turning the key into the latch. However, such movement requires a certain force that must be applied by a human hand. Depending on the vehicle user, the force to apply can prove difficult for certain person, such as old or arm/wrist injured people.

Additionally, under certain conditions, a worn out key forced upon the latch to unlock the steering column can snap under the heavy torque applied. This can prove bothersome as well as painful for the vehicle user.

One object of the invention is to provide an antitheft device for a steering column of a vehicle, in particular a bolt designed such as the antitheft device does not present the drawbacks mentioned hereinabove.

To this end. the invention proposes an antitheft device for a steering column of a vehicle, the device comprising:

- a locking bolt able to occupy a position for locking a steering column,

■· a slider for maneuvering the locking bolt between a lock and an unlocked position,

- a latch able to receive a key,

- a rotor coupled to the latch.

- a camshaft coupled to the rotor and dragged in rotation by the movement of the rotor said camshaft comprises a ramp,

the slider and the camshaft being arranged to that the slider has a translating movement when sliding along the ramp of the camshaft upon rotation of said camshaft,

wherein the ramp of the camshaft comprises a convex curve shape section, designed such as the translating movement of the slider induced by the rotation of the camshaft permits the completion of the unlocking of the steering column. Advantageously, the antitheft device according to the invention provides a locking bolt rotation with a low key torque. The unlocking of the antitheft device is smoother, providing a safest movement for the user.

According to further embodiments which can be considered alone or in combination:

- the ramp of the camshaft comprises in addition to the convex curve shape section at least one linear section located at an end of said ramp; and/or

- the convex curve shape section of the ramp comprises at least one change of slope; and/or

- the convex curve shape section of the ramp comprises at least one linear sub-section; and/or

- the rotation axis of the camshaft is substantially the same as the rotation axis of the rotor; and/or

- the rotation axis of the camshaft is substantially parallel to the axis of translation of the slider; and/or

- the convex curve shape section of the ramp is arranged such as a rotation of an angle a of the camshaft causes a translating movement of the slider that permits the complete unlocking of the steering column, with a greater than or equal to 40° and smaller than or equal to 1 10°; and/or

- the angle β between the tangents taken at any of two distinct points having distinct tangent slopes on the convex curve shape section is obtuse, the angle β taken orientated inwards of said convex curve shape section; and/or

- the camshaft has a cylindrical shape.

Non limiting embodiments of the invention will now be described with reference to the accompanying drawing wherein:

Figure 1 is an isometric overview of an antitheft device according to the invention, Figure 2 is a partial cut-away view of an antitheft device according to the invention,

Figure 3 shows the main parts of one embodiment of the antitheft device interacting with each other, without the housing,

Figures 4a and 4b represents a camshaft according to a prior art antitheft device, Figures 5a to 5c represents a camshaft according to the invention,

Figures 6a to 6c show the translation of the locking bolt according to the invention when the slider is actuated by a camshaft according to the invention.

Figure 1 represents an isometric overview of an antitheft device 10 as isolated from a vehicle. The device comprises a latch 30 for a key, which, when turned, permits the ignition of the motor and actuate a locking bolt 12 to occupy a position to lock the steering column 20 (not shown in figure 1 ) of the vehicle. The antitheft mechanism is enclosed in a housing 40. The housing 40 is then embedded in a vehicle. Figure 2 shows a partial cut-away view of the antitheft device wherein the main elements of the invention are visible. When the key is inserted into the latch 30 and turned, the rotor 18 rotates, dragging along the camshaft 16 on the same axis of rotation. The camshaft 16 comprises a uniform slope that permits, when rotating, to induce a uniform translating movement to the slider 14. The slider 14 translates within a slide in the housing 40 to enable a unilateral movement, the translation direction being parallel to the axis of rotation of the camshaft 16.

The slider 14 then drags along the locking bolt 12, which is located in a bolt housing 42, the bolt housing 42 embedded in the housing 40. The bolt housing 42 allows the bolt 12 to slide in only one axis and to interact with the steering column. The actuation of the rotor 1 8 using the key controls the position of the locking bolt 12, thus blocking or unblocking the steering column.

The steering column 20 shown on figure 3 comprises a slot 22 adapted to receive the bolt 12 which permits the locking in position of the steering column 20 about its axis of rotation. Whenever the steering column 20 is in its locked position, and if a torque is applied to the column axis, the steering column 20 applies a force on the bolt 12. This force, depending on its intensity, is a source of the difficulty (or impossibility) to unlock the steering column 20 by solely turning the key in the latch 30.

The camshaft 16 on figure 4a and 4b shows a prior art camshaft 16. The camshaft 16 is of cylindrical shape, and is secured to the rotor 18 so as to rotate along with a movement of a key in the latch 30. The camshaft 16 then interacts with the slider 14 to induce a translating movement to said slider 14. This translating movement depends on the shape of the ramp 24 present on the side of the camshaft 16. In this embodiment, the ramp 24 is defined by a linear slope, which induces a steady and linear movement to the slider 14, itself inducing a steady and linear movement to the locking bolt 12.

As a consequence of the design of the ramp 24 of the camshaft 16 on figures 4a and 4b, and because of the force applied to the locking bolt 12 by the steering column 20. the force needed to rotate the camshaft 16 is higher than the force needed to move the locking bolt 12. Consequently, the torque that has to be applied to the key in the latch 30 is high and it often proves difficult for a human hand to actuate the key in the latch 30.

The present invention aims at easing the unlocking of the steering column 20 by improving the design of the camshaft 16 in order to reduce the torque that the vehicle user needs to apply to the key to unlock the steering column 20.

Figures 5a to 5c shows a design for a camshaft 16 according to one embodiment of the invention. The camshaft 16 has a cylindrical shape and comprises a ramp 24. The ramp 24, compared to the embodiment previously described, has two sections 23 and 25, wherein section 23 is separated in two sub-sections 26 and 27.

The first section 25, located at the bottom of the ramp 24 according to the orientation of the camshaft 16 as shown on figures 5a and 5b, is a linear ramp characterized by a steep slope. In this embodiment, the first section 25 permits the camshaft 16 to induce a stroke to ensure that the slider 14 is correctly engaged with said camshaft 16. The first section 25 therefore permits to disregard any clearance that can appear between the locking bolt 12 and the slider 14, or between the slider 14 and the camshaft 16. The first section 25 also ensures that the locking bolt 12 correctly starts its movement when the slider 14 interacts with the camshaft 16 through the beginning of the second section 26.

In one embodiment from the invention as presented in figures 5a to 5c, the second section 23 is separated in two distinct sub-sections 26 and 27. The first sub-section is a linear ramp with a slope angle smaller than the slope angle of the first section 25. The interface between the two sub-sections 26 and 27 comprises an abrupt change of slope, considering that the slope angle of second sub-section 27 is bigger than the slope angle of the first sub-section 26. The second sub-section 27 is a linear ramp as well. The second section 23 is a ramp with a convex curve shape. As represented on figure

5c, the angle β between the tangents taken at two distinct points, one on the first sub-section 26 and one on the second sub-section 27 in this case, having distinct tangent slopes on the convex curve shape section 23 is obtuse, for example the angle β is greater than 90°, for example greater than or equal to 1 10°, and smaller than or equal to 170°, for example smaller than or equal to 150° . It is noted that the angle β is always taken orientated inwards of the convex curve shape section 23.

It must be noted that in this description, we define a convex curve shape as a curve wherein any segment formed by any two points belonging on the curve lies above the curve.

Also, the lengths of the different ramps section are adapted such as a rotation of an angle a of the camshaft causes a translating movement of the slider that permits the complete unlocking of the steering column, with a greater than or equal to 40°. for example greater than or equal to 50° and smaller than or equal to 1 10°, for example smaller than or equal to 70°.

In the embodiment represented on figures 5a to 5c, a is substantially equal to 60°.

Figures 6a to 6c represent the different positions of the camshaft 16 according to one embodiment of the invention in regard to the slider 14, and the position of the bolt 12 in interaction with the steering column 20 relating to the corresponding positions of the camshaft 16 as represented in the figures. Also, the figures 6a to 6c illustrate the unlocking of the steering column after the camshaft 16 has interacted with the slider 14 through the first section 25 of the ramp 24, hence at the beginning of the second section 23, when the locking bolt 12 properly starts its movement. On figure 6a, the steering column 20 is blocked in position with the bolt 12 located in the slot 22 of the steering column 20. In this position, a pre-load is generally applied on the steering column 20. Therefore, the steering column 20 exerts a force on the bolt 12 that prevents the bolt 12 to be easily removed from the slot 22 of the steering column 20. In this embodiment, the design of the second sub-section 26 enables the slider 14 to drag the locking bolt 12 with a low force applied on the key. During the sliding of the slider 14 on the second sub-section 26 of the ramp 24. the stroke evolution of the locking bolt 12 is slow, but allows the locking bolt 12 to begin its course to unlock the steering column 20 without requiring an important force from the user.

On figure 6b, the steering column 20 is close to the unlocked position. The bolt 12 is still in contact with the steering column 20 but the torque applied by the steering column 20 to the bolt 12 is negligible. The slider 14 contact area with the ramp 24 of the camshaft 16 gets closer to the interface between the two sub-sections 26 and 27. situated on the second section 23. At this point, the locking bolt 12 gets slowly closer to its unlocked position, while the force needed to be applied to the key remains low.

As the slider 14 transfers to the second sub-section 27, the steering column 20 should be unlocked. However, the locking bolt 12 needs to finish completely its course, in order to ensure that the locking bolt 12 do not get caught in the slot 22 of the steering column 20. Then, at this point, the steering column 20 does not exert any force on the bolt 12. Thus, the force needed to translate the bolt 12 is very low. The slider 14 moves along the second subsection 27 of the ramp 24 to finish the stroke of the bolt 12 and to finalize the unlocking action. The design of the second-subsection 27 of the ramp 24 permits to quickly finish the stroke of the locking bolt 12 with low force from the vehicle user.

The invention has been described above with the aid of embodiments without limitation of the general inventive concept.

Many further modifications and variations will suggest themselves to those skilled in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims.

In the claims, the word "comprising ^" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used. Any reference signs in the claims should not be construed as limiting the scope of the invention.