Adjustment system for adjusting the resistance against relative translational movement between two telescopic elements

Abstract

The invention relates to a sleeve (103) for a steering column, comprising two elements consisting of an outer tube (101) and an inner tube (102), and an adjustment system (100) for adjusting the resistance against the relative translational movement between the two elements (101, 102), the adjustment system (100) comprising: at least one friction pad (20) supported by a first element (101) of the two elements (101, 102); a clamping surface (30) connected to a second element (102) of the two elements (101, 102), wherein the friction pad (20) is configured to contact and be supported on the clamping surface (30); and an adjustment mechanism (10) comprising a cam (11), the cam (11) is directly or indirectly supported on a support member so as to produce a pressure variation of the friction pad (20) on the clamping surface (30) parallel to a reference axis (X) fixed relative to the first element (101) of the two elements (101, 102) so as to change the pressure applied by the friction pad (20) on the clamping surface (30) of the second element (102) of the two elements (101) between the use position and the adjustment position, the sleeve (103) of the steering column being characterized in that the adjustment mechanism (10) of the adjustment system (100) is configured to produce the relative rotational movement between the cam (11) and the support member (12) about the reference axis (X).

Description

Technical Field

[0001] The present invention generally relates to the technical field of adjustment systems for adjusting the resistance against relative translational movement between two elements.

[0002] The invention relates more particularly to an adjustment system for adjusting the resistance against relative translational movement between two elements, in particular consisting of an outer tube and an inner tube of a sleeve of a steering column, in order to allow adjustment of the position (for example the depth) of a steering wheel of a vehicle (for example a motor vehicle). Background Art

[0003] The depth and height of the steering wheel of a motor vehicle are very often adjustable thanks to an adjustment system controlled by the vehicle user. Such an adjustment system generally comprises an adjustment mechanism situated on the steering column of the motor vehicle and can be manual or electrical. In the case of an electrical system, an assembly consisting of a worm reducer associated with a nut system converts the rotary motion of an electric motor into a translational motion, said electric motor then being dimensioned to achieve the desired adjustment speed, taking into account the friction forces present in the steering column and, more generally, in the drive train.

[0004] Depth adjustment is usually achieved through a telescoping system with two tubes: an outer tube and an inner tube configured to translate inside the outer tube, the outer tube including a pressure mechanism such as a screw that exerts a force on the inner tube. This force is necessary to mask the operating play and to guarantee a minimum rigidity of the connection. The electric motor is then dimensioned in order to achieve the desired setting speed, taking into account these forces.

[0005] This pressure mechanism generally comprises a screw screwed into the body and connected to the outer tube, the screw being provided with an interface allowing the application of a torque and / or an angle to the screw and a friction pad rubbing against the inner tube. Once the various components of the mechanism are in place in the body, a tightening step combining torque and angle makes it possible to obtain a compression force having the desired predetermined value, which determines the pressure applied by the friction pad to the inner tube. This adjustment step for adjusting this predetermined value is performed once at the factory during the manufacture of the sleeve of the steering column. Then, during the adjustment phase for adjusting the position of the steering wheel by the user, the force required for making this depth adjustment (whether manual or electrical) must overcome this predetermined force for the relative clamping of the two tubes (corresponding to the clamping of the friction pad against the inner tube) in order to be able to translate them relatively (one tube relative to the other).

[0006] For vehicles equipped with automated driving systems, manufacturers may have to increase the adjustment travel in order to be able to make more room for the vehicle driver during the driving phases in which the vehicle control is automatically ensured. These new adjustment travels can often be two to five times larger than in the case of conventional vehicles. With conventional adjustment mechanisms, this means that the adjustment time will increase in the same proportion. To avoid this, manufacturers are required to keep the adjustment time similar to that of conventional vehicles by increasing the adjustment speed. However, such a limitation leads to oversizing of the motors, which results in additional costs, mass and electrical energy consumption.

[0007] It is therefore necessary to find a solution that allows reducing the sliding forces of the two telescoping tubes during the adjustment phase. In order to overcome these limitations, those skilled in the art have developed several different and variant solutions for electrically controlling the displacement of the friction pad from a use position, in which a predetermined use pressure of the friction pad is exerted on the inner tube, to an adjustment position, in which a reduced adjustment pressure (i.e. lower than the use pressure) is exerted by the friction pad in order to reduce the resistance opposing the translation of the outer and inner tubes of the steering column sleeve in this adjustment position.

[0008] The solutions known today are bulky and their mechanisms are complex. The complexity of these mechanisms therefore also leads to the complexity of the implemented transmission chains, the multiplicity of the mechanical connections of which leads to greater friction and thus to high electrical energy consumption. This is particularly limiting in the constant quest to reduce the overall energy consumption of vehicles, in particular in the case of electric vehicles such as autonomous vehicles. Summary of the invention

[0009] The present invention aims to remedy all or part of the drawbacks of the prior art by proposing in particular a regulating system that is easy to use, not bulky and whose energy consumption for actuating it is not increased or even reduced.

[0010] To this end, according to one aspect of the invention, a sleeve for a steering column is proposed, which comprises two elements consisting of an outer tube and an inner tube, and an adjustment system for adjusting the resistance against the relative translational movement between the two elements, the adjustment system comprising:

[0011] - at least one friction pad supported by a first of the two elements;

[0012] - a clamping surface connected to the second of the two elements, the friction pad being configured to contact and bear against the clamping surface;

[0013] - an adjustment mechanism comprising a cam supported directly or indirectly on a support so as to produce a variation in the pressure of the friction pad against the clamping surface parallel to a reference axis fixed relative to a first of the two elements so as to vary the pressure of the friction pad against the clamping surface of the second of the two elements between the following two positions:

[0014] i. a use position in which a predetermined use pressure of the friction pad is applied to the clamping surface of the second of the two elements, and

[0015] ii. an adjustment position in which an adjustment pressure lower than the use pressure is applied by the friction pad on the clamping surface of the second of the two elements,

[0016] The bushing of the steering column is characterized in that the adjustment mechanism of the adjustment system is configured to bring about a relative rotational movement between the cam and the support about a reference axis.

[0017] This combination of features provides a solution which, on the one hand, allows the friction pad to exert a large force outside the adjustment phase (i.e. in the use position) to ensure high stiffness, and, on the other hand, allows the friction pad to exert a sufficiently low force during the adjustment phase to allow an energy source (e.g. a medium-power electric motor) to implement the adjustment. Another advantage of this system is that it has a reduced volume.

[0018] According to one embodiment, in the use position, the first of the two components consisting of the support and the cam of the adjustment mechanism engages with the first of the two elements consisting of the outer tube and the inner tube of the sleeve of the steering column and is adjustable in axial position relative to the first of the two elements.

[0019] In an advantageous configuration, the first of the two components consisting of the support and the cam comprises an annular body having an outer surface provided with radial threads extending coaxially with the reference axis and configured to cooperate with a threaded hole of the first of the two elements consisting of the outer tube and the inner tube. In this configuration, the first of the two components comprises a radial contact surface in the form of a screw which can be screwed into the first of the two elements, in particular into a threaded hole in the outer tube. Preferably, the dimensions of this first of the two components are selected so that it can cooperate with a threaded hole identical to that used by an already existing adjustment mechanism. This makes it possible in particular to adapt this adjustment system to the sleeve of an existing steering column.

[0020] According to one embodiment, the first of the two components constituted by the support and the cam comprises a contact surface configured to allow the application of a torque and / or an angle to the first component. In this way, once the adjustment system is in place and positioned on one of the tubes, a tightening step combining torque and angle makes it possible to obtain the desired value that determines the force exerted by the friction pad on the other tube. In other words, such an adjustment step aims to position the adjustment mechanism in the use position using a predetermined pressure exerted by the friction pad on the second of the two elements, which is carried out in a relatively precise manner because the adjustment mechanism is screwed into a threaded hole of the first of the two elements.

[0021] According to one embodiment, the second of the two components consisting of the support and the cam comprises a plate. Preferably, the plate is caused to rotate directly or indirectly by a transmission mechanism connected to at least one actuator, such as a motor. According to one embodiment, the plate is connected to a drive arm, which extends axially relative to the reference axis and is configured to drive the plate in rotation. The use of a drive arm makes it possible to move the drive mechanism out of the sleeve of the steering column, thereby simplifying design and manufacturing.

[0022] According to one embodiment, the movable plate of the second of the two members is supported directly or indirectly against the first of the two members consisting of a support and a cam, and the two members are configured so that rotation of the plate in a positive direction (sens direct) about a reference axis produces an axial displacement of the plate in a first direction, and rotation of the plate in a non-positive direction (sens indirect) about the reference axis produces an axial displacement of the plate in a second direction opposite to the first direction.

[0023] According to one embodiment, the regulating mechanism of the regulating system comprises rolling bodies arranged between two components constituted by a support and a cam, each of the two components comprising a rolling track for guiding at least one of the rolling bodies. This characteristic makes it possible to limit the friction inside the system and thus reduce the power and / or energy consumption of the actuators required for actuating the mechanism.

[0024] The rolling element acts as a follower rolling on the cam. Preferably, the rolling element is a ball. However, it can be noted that other embodiments are possible in which the shape of the rolling element differs from that of a spherical ball. For example, it can be a roller, such as a cylindrical or conical roller. A minimum number of three rolling elements placed between the support and the cam ensures the stability of the mechanical connection relative to the reference axis.

[0025] In a preferred configuration, the first of the two members is formed by a support and the second of the two members is formed by a cam containing a profile making it possible to control the displacement of the plate, said geometric profile preferably being contained by the plate itself. Thus, in this configuration, the relative rotation between the two members is ensured by the rotation of the plate, which in this case belongs to the cam, and the support is fixed relative to the tube into which it is screwed.

[0026] According to one embodiment, the support comprises an annular groove, continuous over its circumference and coaxial with the reference axis, thereby forming a rolling track for the rolling bodies, thereby guiding said rolling bodies in rotation about the reference axis.

[0027] According to one embodiment, the cam comprises separate rolling tracks, each extending over a preferably separate angular sector, having a first end and a second end, each track being configured so that the associated rolling body is displaced axially relative to the track when the rolling body changes position along the track between the associated first end and the second end. In this way, as the rolling body is displaced along the rolling track of the cam (for example a plate), the axial position of the rolling body changes concomitantly. The rolling body is axially fixed relative to the support and is constrained between the support and the cam, and the rotation of the cam causes a change in the axial distance separating the support from the cam. The rolling track or cam track of the cam thus makes it possible to control the axial displacement of the cam relative to the support, which is fixed, for example, relative to the first of the two elements, in particular formed by the outer tube of the steering column sleeve. The adjustment mechanism is configured so that: the axial movement of the cam relative to the support (and therefore relative to the first of the two elements) generates a translational movement of the plate, which itself generates a height change of the spring washer, which itself generates a pressure change of the friction pad against the clamping surface of the second of the two elements.

[0028] When the rolling body is placed between the cam and the support, the cam indirectly supports the support against the adjustment mechanism. Other configurations are obviously possible, such as direct support. In this case, the cam has a surface with a slope, and the support has followers that are configured to slide on one of the slopes of the cam. It is understood that the geometry can also be reversed. However, such a contact between the sliding surfaces will cause significant friction.

[0029] The angular sectors of the rolling tracks of the cam are preferably identical and smaller than 120°. According to one embodiment, each angular sector of the rolling tracks of the cam is greater than 30°, preferably greater than 40° and smaller than 90°, preferably smaller than 60°. The circumferential length of the angular sectors is chosen to be sufficient so that the axial amplitude of the displacement of the friction pad relative to the clamping surface due to the relative rotation of the cam relative to the support covers the axial amplitude of the displacement of the friction pad between its use position and its adjustment position.

[0030] According to one embodiment, each rolling track of the cam extends along a portion of a helical curve inscribed on a cylindrical envelope surface coaxial with the reference axis. The pitch of the curve is determined to be sufficiently low so that the force required for rotating the cam is relatively small and can be achieved by a simple motor with a power compatible with that on the vehicle; and the pitch of the curve is determined to be sufficiently large so that an angular displacement of the cam (for example of the plate when the plate contains the cam track) preferably less than 120° produces an axial displacement of the friction pad that is at least equal to the distance separating its use position and its adjustment position.

[0031] It will be noted that in another configuration, each of the geometrical profiles or contact surfaces of the support and the plate can be interchanged so that the support comprises a plate mounted to rotate about a reference axis, the plate then preferably having an annular groove for guiding the rolling bodies. In this configuration, the cam is fixedly mounted relative to a first of the two elements, for example the outer tube of the steering column sleeve, in particular by screwing the cam into a threaded hole provided for this purpose.

[0032] However, as long as the threaded annular component is fixed relative to the outer tube of the steering column sleeve (for example), tightening the mechanism in the threaded hole can exert the prestress of the friction pad on the clamping surface of the inner tube. Such tightening usually results in a rotation of more than 360 degrees, while the rotation of the plate used to displace the friction pad between the use position and the adjustment position of the friction pad is less than 120 degrees. In order to make the tightening easy for the operator and not restrict the positioning of the rolling body relative to the cam track, it is advantageous for the support fixed by the first of the two elements relative to the steering column sleeve to contain a continuous annular groove. For this reason, it is preferred that the member to be rotated (in particular by the plate itself) is contained on the cam track, the support being screwed into the threaded hole for example and being fixed during use of the adjustment mechanism.

[0033] Therefore, when the geometric profile forming the cam is contained by the plate, this allows the system to have improved precision in controlling the displacement of the friction pad, especially because it is the plate that is rotated so as to generate the axial displacement of the friction pad by the axial displacement of the plate, while the support is fixed in this construction.

[0034] According to one embodiment, the adjustment mechanism comprises a spring arranged between the plate and the friction pad, the spring preferably being a spring washer arranged coaxially with respect to the reference axis.Such a spring can achieve a pressure according to its compression.

[0035] According to one embodiment, the adjustment mechanism comprises a ball disposed (preferably placed) between the plate and the spring washer. The ball is preferably unique and centered on the reference axis. In a particular configuration, the diameter of the ball is greater than the diameter of the central hole in the spring washer. Such a ball can transmit at least an axial movement of the plate to the spring washer. In addition, the small contact surface of the ball with the spring (in particular the spring washer) allows a reduced friction torque during rotation of the plate.

[0036] According to one embodiment, the adjustment mechanism comprises a preferably flat distribution washer arranged between the spring washer and the friction pad in order to distribute the force from the spring washer to the friction pad, the flat washer preferably being arranged coaxially with respect to the reference axis. Such a distribution washer is more advantageous in case the friction pad is made of a thermoplastic material. However, in case the friction pad is made of a metallic material such as bronze or sintered metal, such a distribution washer can be removed from the mechanism.

[0037] According to one embodiment, the regulating system comprises at least two regulating mechanisms controlled simultaneously by a single actuator, and they are preferably controlled simultaneously by a single transmission mechanism. Such a regulating system is particularly simple and inexpensive to implement. Furthermore, the low friction present in the case of rolling bodies makes it possible to control the displacement of the friction pads based on the same motor. This configuration also simplifies the implemented logic, since it eliminates the limitation of controlling multiple actuators in a perfectly synchronized manner.

[0038] According to one embodiment, the reference axis of the adjustment mechanism is arranged perpendicularly, preferably radially, relative to the translation axis of the two elements consisting of the outer tube and the inner tube of the sleeve of the steering column, which are translationally movable relative to each other.

[0039] According to one embodiment, the adjustment mechanism is configured to be able to produce, beyond its use position, a change in the pressure of the friction pad against the clamping surface in the direction of increasing the pressure exerted by the friction pad on the clamping surface of the second of the two elements. Increasing the pressure in the use position may indeed be advantageous in order to make the friction force not only the predetermined force necessary to ensure high rigidity, but also the force necessary to ensure energy absorption in the event of a crash.

[0040] This offers two important advantages: the first one relates to the possibility of eliminating energy absorbing elements (usually plastically deformed steel parts) and thus generating cost and quality benefits; the second one relates to the possibility of implementing different crash forces with the same components and in a very simple way, since the configuration is achieved by simple adjustments at the actuator (e.g. control motor). This is useful in the case of differentiated markets where different crash forces are mandated by local regulations. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Other features and advantages of the present invention will become apparent upon reading the following description and referring to the accompanying drawings, which show:

[0042] [ Figure 1 ]: A perspective view of a portion of a steering column according to the invention;

[0043] [ Figure 2 ]: Figure 1 A cross-sectional view of

[0044] [ Figure 3 ]: Figure 2 Details;

[0045] [ Figure 4A ]: An exploded perspective view of an adjustment mechanism according to a first embodiment of the present invention, generally viewed from above;

[0046] [ Figure 4B ]:from Figure 4A An exploded perspective view of the adjustment mechanism of the device as viewed generally from below;

[0047] [ Figure 5 ]: A perspective view of a portion of the adjustment system according to the embodiment;

[0048] [ Figure 6 ]: A perspective view of a portion of an adjustment system according to a second embodiment;

[0049] [ Fig. 7A ]: side view of the adjustment mechanism according to the first embodiment in the use position;

[0050] [ Figure 7B ]: A side view of the adjustment mechanism according to the first embodiment in the adjustment position;

[0051] [ Figure 8 ]: A cross-sectional view of an adjustment mechanism according to a second embodiment of the present invention.

[0052] For greater clarity, the same or similar elements are denoted by the same reference numerals throughout the drawings. DETAILED DESCRIPTION

[0053] Figure 1 and Figure 2 A portion of a steering column of a motor vehicle, such as a passenger car, is shown in perspective and in section, the steering column being provided with a sleeve 103. The sleeve 103 of the steering column is of the type comprising a telescopic system having two tubes 101, 102, namely an outer tube 101 and an inner tube 102 configured to translate inside the outer tube 101. The steering column comprises a shaft, such as a steering shaft, which is guided in the sleeve 103 and has a distal end 102' and an opposite other end, which is configured to be connected directly or indirectly to a steering wheel (not shown), and which has a contact surface such as a cardan acting as a bevel gear (renvoi d'angle) towards another shaft or lower shaft to rotate a pinion meshing with a steering rack (not shown). The depth adjustment of the steering wheel by the user is achieved in particular by the translation of the inner tube 102 relative to the outer tube 101 of the sleeve 103.

[0054] In order to mask the operating play and to ensure a minimum rigidity of the connection of the two tubes 101, 102 relative to each other in the use position, the sleeve 103 of the steering column is provided with at least one friction pad 20 supported by the outer tube 101 and configured to be in contact with and bear against the clamping surface 30 of the inner tube 102. In the use position, the system is configured so that a predetermined use pressure of the friction pad 20 carried by the outer tube 101 is exerted on the clamping surface 30 of the inner tube 102. This pressure of the pad 20 is intended to increase the resistance against the relative translational movement between the two elements constituted by the outer tube 101 and the inner tube 102.

[0055] The invention proposes an adjustment system 100 for adjusting the resistance against this relative translational movement between the outer tube 101 and the inner tube 102 of the steering column sleeve 103, so as to be able to allow in particular adjustment of the depth of the steering wheel over a relatively large adjustment stroke without increasing the adjustment time due to the reduction of the pressure exerted by the pad 20 on the clamping surface 30.

[0056] To this end, the adjustment system 100 comprises, in addition to the pad 20 and the clamping surface 30, an adjustment mechanism 10 for generating a translational movement of the friction pad 20 relative to the clamping surface 30 along a reference axis X (the reference axis X being stationary relative to the outer tube 101) in order to vary the pressure of the friction pad 20 on the clamping surface 30 of the outer tube 102. The reference axis X is arranged perpendicularly, in particular radially here, relative to the translation axis W of the two elements 101, 102 constituted by the outer tube 101 and the inner tube 102 of the steering column sleeve 103 in order to increase the efficiency of the system 100.

[0057] The adjustment system 100 allows a pressure variation of the friction pad 20 at least between its use position, in which a predetermined use pressure of the friction pad 20 is applied to the clamping surface 30 of the outer tube 102, and an adjustment position, in which the pressure of the friction pad 20 against the clamping surface 30 is reduced compared to the use position. It is thus possible to achieve higher adjustment speeds between the two tubes 101, 102, thereby avoiding oversizing of the motor that generates the relative movement of the two tubes 101, 102.

[0058] It will be noted that, according to an embodiment, it may be chosen to compress the friction pad 20 relative to the clamping surface 30 beyond its use position, in the direction of increasing pressure exerted by the friction pad 20 on the clamping surface 30 of the inner tube 102. For example, in the event of a crash, it may be provided that the pressure is increased relative to the pressure exerted in the use position, so that the friction force is not only the predetermined force required to ensure high rigidity, but also the force required to ensure energy absorption during a crash.

[0059] Figure 3 Shows Figure 1 and Figure 2 As shown, the adjustment system 100 comprises two adjustment mechanisms 10 operating in parallel so as to be able to act together and simultaneously on a sleeve 103 of the steering column and distribute the friction forces on separate clamping surfaces 30 .

[0060] In this configuration, for each of the two adjustment mechanisms 10 equipped with a steering column sleeve 103, the support 12 of the adjustment mechanism 10 is immobile in the use position relative to the outer tube 101 and is detachable relative to this outer tube 101. This fixation of the adjustment mechanism 10 is ensured by an annular body 120 of the support 12, which has a radial outer surface 121 provided with a radial thread 122 extending coaxially with the reference axis and configured to cooperate with a threaded hole 111 of the outer tube 101. In this way, the support 12 can be fixed to the outer tube 101 by simply screwing the mechanism into the threaded hole 111 of the outer tube 101 provided for this purpose. This threaded connection allows the adjustment mechanism 10 to be fixed in the use position relative to the clamping surface 30. This adjustment of the use position with a predetermined pressure is usually made in the factory by an operator acting on a contact surface configured so that a torque and / or angle is applied.

[0061] Since the adjustment mechanism 10 (in Figure 4A and 4B), in order to generate a pressure variation of the friction pad 20 in a relatively small volume, the adjustment mechanism 10 is provided with a cam 11 which contacts and rests on a support 12. The pressure variation of the pad 20 is caused by an axial translation movement of the cam 11, which itself is caused by a relative rotation movement about a reference axis X between the cam 11 and the support 12.

[0062] The cam 11 comprises a plate 13 connected to a drive arm 14 extending axially relative to the reference axis X. The drive arm 14 is mounted in sliding pivot connection with a member connected to the outer tube 101, here the support 12. The plate 13 of the cam 11 also comprises an annular body having radial dimensions less than or equal to, preferably strictly less than, the radial dimensions of the annular body 120 of the member fixedly mounted relative to the outer tube 101, here the support 12. This confers improved compactness to the adjustment mechanism 10 and ensures that the adjustment mechanism 10 can be at least partially housed in the threaded hole 111 for an operator to mount it in place from the outside of the outer tube 101.

[0063] In this configuration, the support 12 is fixed relative to the outer tube 101 , and the cam 11 is driven to rotate directly or indirectly via a transmission mechanism 40 connected to at least one actuator 50 , such as a motor.

[0064] The transmission mechanism 40 may comprise a lever, a connecting rod, a rack or a cable system. The actuator 50 comprises an electric motor coupled to a reducer, which makes it possible to obtain the stroke and force required for the movement of the adjustment mechanism 10. It may also be a solenoid.

[0065] The electric motor 50 can also directly drive one of the two adjusting mechanisms 10, while the other adjusting mechanism is connected to the first adjusting mechanism via an intermediate transmission mechanism similar to the transmission mechanism 40. The motor can also act on only one of the adjusting mechanisms 10.

[0066] In order to reduce the force required by the electric motor 50, a compensation spring can be added to the transmission mechanism 40. This spring compensates the compression force of the spring washer 16 during the rotation of the plate 13 of the cam from the adjustment position to the use position. The motor 50 then only has to overcome the force due to the friction of the adjustment mechanism 10 and can therefore be smaller in size.

[0067] like Figure 5As can be seen in the figure, the motor 50 drives a worm 51 which in turn drives a first gear 41 which in turn drives a second gear 42 which meshes with a rack 43. The first gear 41 and the second gear 42 are arranged coaxially with each other along an axis parallel to the reference axis X of the adjustment mechanism 10. The transmission chain of the transmission mechanism 40 thus makes it possible to drive the translation of a rack 43 based on the motor 50, which rack 43 extends over a length greater than the space separating the two adjustment mechanisms 10, so that the rack 43 drives in rotation two pinions 45, each of which engages with one of the guide shafts 14 of each of the plates 13 of the adjustment mechanism 10. In particular, the drive arm 14 has a contact surface which is partially connected in sliding fashion with one of the pinions 45, so as to be able to allow the drive arm 14 to move axially relative to the associated pinion 45, while allowing the rotational movement to be transmitted from one component to the other, for example by the cooperation of the substantially square section of the drive arm 14 in the complementary square hole of the pinion 45 (or any other non-axisymmetric section). In this way, two parallel adjustment mechanisms 10 can be controlled simultaneously based on the same transmission mechanism 40 driven by a single motor 50 .

[0068] Alternatively, if Figure 6 As shown, the rack 43 can directly engage the toothed periphery 44 of the plate 13, thereby causing relative rotation of the cam 11 relative to the support 12. A cross-sectional view of such a system 100 is shown in FIG. Figure 1 . The outer tube 101 is arranged in such a way as to allow the rack 43 to pass through. In this configuration, since the plate 13 is guided to rotate about the reference axis X by its assembly with the annular body of the screw 12, the drive arm 14 can be eliminated, as described in more detail below. Therefore, the design of the adjustment mechanism 10 is simplified, the number of parts is reduced, and the manufacturing cost of the adjustment mechanism 10 is also reduced.

[0069] Whatever the embodiment of the transmission 40 , the plate 13 is driven in rotation about the reference axis X, either directly (for example via teeth 44 of the plate 13 ) or indirectly (via an intermediate component such as a pinion 45 meshing with the cam 11 ). Accompanying this angular displacement, the plate 13 is displaced axially by the cam 11 , whether the cam is formed by a rotary movable plate or, alternatively, is carried by a component forming a screw in the outer tube 101 .

[0070] The plate 13 of the cam 11 is caused to rotate about a reference axis X coaxial with the annular body of the screw 12 and driven in rotation by a drive arm 14 which is itself driven in rotation by a pinion 45. The movable plate 13 of the cam 11 bears against the support 12, the adjustment mechanism 10 being configured so that a relative rotation of the two members 11, 12 relative to each other causes a translation of the plate parallel to the reference axis. In particular, a rotation of the plate 13 about the reference axis X in a positive direction generates an axial displacement of the plate 13 in a first direction, and a rotation of the plate 13 about the reference axis X in a non-positive direction opposite to the positive direction generates an axial displacement of the plate 13 in a second direction opposite to the first direction.

[0071] Given that the ball-type rolling elements 15 are placed in the space axially delimited by the support 12 and the cam 11, the plate 13 is indirectly in contact with and supported on the support 12. Such rolling elements 15 make it possible to ensure the relative rotation of the cam 11 with respect to the support 12 while reducing the friction between these components. Each of the two components 11, 12 comprises a respective rolling track 110, 120 to guide each ball 15. A minimum of three balls regularly distributed around the reference axis allows a good distribution of forces without being restricted by the reference axis X. These rolling elements 15 can be kept spaced apart from each other by a rolling cage 19 in the shape of a ring 191, 191 provided with a groove 192 to accommodate each ball 15 therein (see Figure 4A ).

[0072] In order to resist the pressure generated by the contact with the balls 15, the screw forming the support 12 here is made of hardened steel. Powder sintering is the most suitable method, but this part can also be produced by cold stamping deformation and / or machining or a combination of these methods. For the same reason, the plate 13 and its shaft 14, which are formed in one piece here and form the cam 11 here, are made by a method similar to the screw.

[0073] The rolling track 120 of the support 12 comprises an annular groove 121 which is continuous over its circumference and coaxial with the reference axis X. The groove 121 comprises a bottom having a cross section in the shape of an arc of a circle, the radius of curvature of which is substantially equal to the radius of the spherical balls 15, so that the groove locally matches the shape of the balls 15, making it possible to ensure their circular guidance around the reference axis X without play.

[0074] The rolling track 110 of the cam 11, in particular the plate 13, is configured to ensure the function of controlling the axial displacement of the cam 11 relative to the support 12. In practice, the plate 13 comprises three separate rolling tracks 110 extending over separate angular sectors and having the same radial dimensions relative to one another, i.e. following an arc inscribed on a cylindrical envelope having the same radius of curvature relative to the reference axis X. Each cam track 110 extends along an angular sector of approximately 45 degrees. Each cam track 110 extends along a portion of a helical curve inscribed on a cylindrical envelope coaxial with the reference axis X, so that each of these rolling tracks 110 has a first end 110A and a second end 110B placed at different or offset axial positions, which results in a slope of the rolling tracks relative to the reference axis X. For example, if a force of 1500 N is selected in the use position and a force of 300 N is selected in the adjustment position, using a spring 16 with a stiffness of 4000 N / mm, the axial stroke of 0.3 mm between the use position and the adjustment position and the adjustment of the adjustment mechanism 10 can be controlled, which corresponds to a slope of approximately 5% for a 45° displacement of the cam 11.

[0075] When the ball 15 changes position along the rolling track 110 from one end 110A, 110B to the other end, the slope of these rolling tracks 110 allows the associated ball 15 to be axially displaced relative to the reference axis. More precisely, each rolling track 110 of the cam 11 extends along a portion of a spiral curve inscribed on a cylindrical envelope surface coaxial with the reference axis X. Other shapes of cam paths 110 can be used, such as following a curved portion inscribed on a spiral line rotating around the reference axis. However, such a construction results in radial displacement of the ball 15, thereby requiring a larger useful volume. In order to ensure the stability of the system, in the use position, each rolling track 110 of the cam has a curved profile (on which the ball 15 changes position along the slope) and ends with a flat portion or a portion with an opposite slope. This is particularly advantageous in environments subject to vibration (such as motor vehicles). Preferably, each cam track 110 extends along an angular sector equal to the angle of rotation of the plate (ie here 45 degrees) configured to drive a ball 15 from one end of its rolling track 110 to the other.

[0076] It will be noted that the cam 11 support 12 construction can be reversed. In this case, the plate 13 carries an annular groove 121, which is continuous over its circumference and coaxial with the reference axis X, and the plate 13 forms the support 12. Similarly, in such a construction, the cam track 110 is contained by one face of an annular body screwed into the threaded hole 111 and is fixedly connected to the outer tube 101 in the position of use. In this case, the support 12 is driven in rotation and, by the friction of the balls 15 in the associated rolling tracks 110, 120, these so-called balls roll along the axial component of the cam track 110 fixed relative to the outer tube 101.

[0077] In another configuration, the support 12 can also have, together with the cam 11, a geometric profile that facilitates the axial displacement of the rolling elements 15. This may be the case in which the amplitude of the axial displacement is increased without increasing the angular sector of the cam track.

[0078] Whatever configuration of cam 11 and support 12 is chosen, the pressure exerted by friction pad 20 on clamping surface 30 is controlled by the displacement of plate 13 which is indirectly supported on friction pad 20 .

[0079] Furthermore, whatever the chosen configuration of cam 11 and support 12, rolling bodies 15, such as balls, are interposed between the assembly of cam 11 and support 12, forming a bearing. The rolling tracks formed here by the annular groove 121 on the one hand and by the cam track 110 on the other hand are configured to participate in the relative guidance of cam 11 and support 12. In other words, rolling bodies 15, in particular balls, make it possible to keep plate 13 coaxial with reference axis X. A minimum number of three balls also ensures this guidance.

[0080] The adjustment mechanism 10 comprises a spring washer 16, which is arranged between the plate 13 and the friction pad 20 and is coaxially positioned relative to the reference axis X. The spring washer 16 generates a pressure according to its compression. The spring washer 16 has a stiffness that allows it to generate a force when it is compressed in the use position (so that a minimum stiffness of the connection between the two tubes, the outer tube 101 and the inner tube 102, can be guaranteed) and that allows it to generate a low but non-zero force corresponding to the adjustment force when it is compressed in the adjustment position.

[0081] This spring washer 16 has, in its center, a central bore 160, the diameter of which is smaller than the diameter of the ball 17 placed between the plate 13 and the spring washer 16. This ball 17 is housed, centered on the reference axis, in a spherical cap 170 formed in the material of the plate 13, on the face opposite to the face containing the rolling track. In order to limit the clearance of the ball 17 in the spherical cap 170, the radius of the spherical cap 170 is substantially equal to the radius of the ball 17 it receives. Given that the diameter of the ball 17 is greater than the diameter of the bore 160, the spring washer 16 is positioned so that its central bore 160 receives the ball 17 in its center and bears against it based on a substantially circular linear contact. The ball 17 thus transmits the movement of the plate 13 to the spring washer 16. The small contact surface of the ball 17 allows a reduced friction torque during the rotation of the plate 13, where the cam 11 is formed. In the case of a plate 13 without a drive arm 14, the plate 13 can be locally reinforced by a material protrusion 14', such as Figure 8 As shown, this material protuberance 14 ′ is intended to reinforce the structure of a spherical cap 170 formed in the material of the plate 13 .

[0082] This series of axisymmetric parts supporting one another makes it possible to distribute the pressure evenly on the spring washer 16, which itself bears against the rear surface of the friction pad 20. This support of the spring washer 16 against the friction pad is indirect here, given that the adjustment mechanism 10 comprises a flat distribution washer 18 centered on the reference axis X and placed between the spring washer 16 and the friction pad 20. This flat washer 18 has the function of distributing the force coming from the spring washer 16 over the surface of the friction pad 20.

[0083] The friction pad 20 that contacts the washer 18 and rubs on the clamping surface 30 of the inner tube is made of a thermoplastic material, and a lubricating filler may be added thereto. For example, the friction pad 20 may also be made of a metal material such as sintered bronze.

[0084] Once these various components are in place in the body, a tightening step combining torque and angle makes it possible to obtain a compression of the spring washer 16 up to the desired value which determines the force applied by the friction pad 20 to the inner tube 102. During this step, the cam 11 is kept in the use position (see Fig. 7A ). In this position, the cam 11 and the support 12 are spaced apart by a distance d U .

[0085] During the adjustment phase (see Figure 7B), the external transmission mechanism 40 displaces the plate 13 (here the cam 11) from the use position to the adjustment position, which produces an axial movement of the cam 11. This movement increases the height of the spring washer 16, which reduces the force exerted on the friction pad 20 and thus reduces the adjustment force. In this position, the cam 11 and the support 12 are spaced apart by a distance d R . Thus, the adjustment is carried out with little force. Once the adjustment has been carried out, the actuator 50 and the external transmission mechanism 40 return the plate 13 of the cam 11 to the use position, which displaces the plate 13 and compresses the spring washer 16, thus returning to the situation before the adjustment. The adjustment mechanism is configured so that the axial displacement preferably varies between 0.1 and 0.5 mm, depending on the stiffness of the spring washer 16 and the required force.

[0086] In conclusion, one of the main advantages of the invention is the possibility of increasing the adjustment speed while maintaining a power adjustment motor similar to the motors currently used. Another advantage of the invention is the possibility of providing an adjustment mechanism that makes it possible to adapt a steering column sleeve with conventional electric adjustment without having to modify its structure. This makes it possible to have a large number of components in common with conventional steering columns and to use the same assembly means. These two advantages make it possible to produce a steering column with increased adjustment speed at low additional cost.

[0087] Naturally, the present invention has been described above by way of example. It should be appreciated that those skilled in the art can implement various embodiment variations of the present invention without departing from the scope of the present invention.

[0088] For example, the cam can be formed by any axial transmission cam. The cam can be formed by a nut mechanism. In this case, the second of the two components consisting of the support and the cam (for example, the cam 11) includes a threaded rod forming a screw, which cooperates with the internal thread contained by the first of the two components (for example, the support 12). The screw thus replaces the plate 13 in the example shown.

[0089] In an alternative configuration, the cam 11 could have a contact surface in the manner of a dog clutch, but with teeth having surfaces inclined relative to the reference axis X and configured to slide in rotation relative to a complementary surface axially facing the cam 11 and comprised by the support 12. However, a cam provided with rolling bodies 15 has the advantage of significantly reducing friction.

[0090] Furthermore, the figures show an embodiment in which the cam 11 is located below the support 12. Of course, the cam could be located axially above the support relative to the reference axis, even if driven in rotation, that is to say the support 12 would be positioned axially between the friction pad 20 and the cam 11. This embodiment is, however, more bulky externally but allows adaptation to tube sets of smaller dimensions for which it is necessary to maintain the structural integrity of the inner and outer tubes to the greatest extent possible.

[0091] It should also be noted that the cam may be a component that is screwed into the threaded hole 111 of the outer tube 101 and then fixedly installed, and a support formed by the plate 13 that is driven to rotate directly or indirectly by the transmission mechanism 40 .

Claims

1. A sleeve (103) for a steering column, the sleeve (103) for a steering column comprising two elements consisting of an outer tube (101) and an inner tube (102), and an adjustment system (100) for adjusting a resistance against a relative translational movement between the two elements (101, 102), the adjustment system (100) comprising: - at least one friction pad (20) supported by a first of the two elements (101, 102); - a clamping surface (30) connected to the second of the two elements (101, 102), the friction pad (20) being configured to contact and bear against the clamping surface (30); - an adjustment mechanism (10) comprising a cam (11) supported directly or indirectly on a support so as to produce a variation in the pressure of the friction pad (20) against the clamping surface (30) parallel to a reference axis (X) fixed relative to the first of the two elements (101, 102) so as to vary the pressure of the friction pad (20) against the clamping surface (30) of the second of the two elements (101, 102) between the following two positions: i. a use position in which a predetermined use pressure of the friction pad (20) is applied to the clamping surface (30) of the second of the two elements (101, 102), and ii an adjustment position in which an adjustment pressure lower than the use pressure is applied by the friction pad (20) to the clamping surface (30) of the second of the two elements (101, 102), The sleeve (103) of the steering column is characterized in that the adjustment mechanism (10) of the adjustment system (100) is configured to cause a relative rotational movement between the cam (11) and the support (12) about the reference axis (X); Therein, the reference axis (X) extends through the friction pad, the clamping surface, the cam and the support member.

2. The sleeve (103) of the steering column according to claim 1, characterized in that: In the use position, the first of the two components consisting of the support (12) and the cam (11) of the adjustment mechanism (10) engages with the first of the two elements (101, 102) and is adjustable in axial position relative to the first of the two elements (101, 102).

3. The sleeve (103) of the steering column according to claim 2, characterized in that: The first of the two components formed by the support (12) and the cam (11) includes an annular body (123) having an outer surface provided with radial threads (122) extending coaxially with the reference axis and configured to cooperate with a threaded hole (111) of the first of the two elements (101, 102).

4. The sleeve (103) of the steering column according to claim 2 or 3, characterized in that: The second of the two components formed by the support (12) and the cam (11) comprises a plate (13) which is caused to rotate by a transmission mechanism (40) connected to at least one actuator (50).

5. The sleeve (103) of the steering column according to claim 4, characterized in that: A movable plate (13) of the second one of the two components (11, 12) is directly or indirectly supported against the first one of the two components (11, 12), and the two components (11, 12) are configured so that rotation of the plate (13) in a positive direction around the reference axis (X) produces an axial displacement of the plate (13) in a first direction, and rotation of the plate (13) in a non-positive direction around the reference axis (X) produces an axial displacement of the plate (13) in a second direction opposite to the first direction.

6. The sleeve (103) of the steering column according to claim 5, characterized in that: The adjustment mechanism (10) of the adjustment system (100) comprises a rolling body (15) arranged between two components consisting of the support (12) and the cam (11), and each of the two components (11, 12) comprises a rolling track (110, 120) for guiding at least one of the rolling bodies (15).

7. The sleeve (103) of the steering column according to claim 6, characterized in that: The rolling body (15) is a ball.

8. The sleeve (103) of the steering column according to claim 4, characterized in that: The first of the two components (11, 12) is a support (12), and the second of the two components (11, 12) is a cam (11).

9. The sleeve (103) of a steering column according to claim 6, characterized in that: The support member (12) includes an annular groove (121) which is continuous on its circumference and coaxial with the reference axis (X), thereby forming a rolling track (120) for the rolling body (15), thereby guiding the rolling body (15) to rotate around the reference axis (X).

10. The sleeve (103) of the steering column according to claim 9, characterized in that: The plate (13) is a plate of the cam (11) and comprises separate rolling tracks (110), each rolling track (110) extending over an angular sector, having a first end (110A) and a second end (110B), each track (110) being configured so that the associated rolling body (15) is axially displaced when the rolling body (15) changes position along the track (110) between the associated first end (110A) and the second end (110B).

11. The sleeve (103) of a steering column according to claim 10, characterized in that: Each rolling track (110) of the plate (13) of the cam (11) extends along a portion of a helical curve inscribed on a cylindrical envelope surface coaxial with the reference axis (X).

12. The sleeve (103) of a steering column according to claim 4, characterized in that: The adjustment mechanism (10) comprises a spring (16) arranged between the plate (13) and the friction pad (20).

13. The sleeve (103) of a steering column according to any one of claims 1 to 3, characterized in that: The adjustment system (100) comprises at least two adjustment mechanisms (10) which are simultaneously controlled by a single actuator (50).

14. The sleeve (103) of a steering column according to any one of claims 1 to 3, characterized in that: The reference axis (X) is arranged radially relative to the translation axis (W) of the two elements (101, 102) constituted by the outer tube (101) and the inner tube (102) of the sleeve (103) of the steering column.

15. The sleeve (103) of a steering column according to claim 4, characterized in that: The actuator is a motor.

16. The sleeve (103) of a steering column according to claim 10, characterized in that: Each rolling track (110) extends over a separate angular sector.

17. The sleeve (103) of a steering column according to claim 12, characterized in that: The spring (16) is a spring washer arranged coaxially with respect to the reference axis (X), and the adjustment mechanism (10) of the adjustment system (100) comprises a ball (17) arranged between the plate (13) and the spring washer (16).

18. The sleeve (103) of the steering column according to claim 17, characterized in that: The ball (17) is unique and centered on the reference axis (X).

19. The sleeve (103) of a steering column according to claim 13, characterized in that: The at least two adjusting mechanisms are simultaneously controlled by a single transmission mechanism (40).

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