Steering column including electrically powered device for blocking rotation

Abstract

The invention relates to a steering column for a motor vehicle comprising two telescopically connected drive shafts (8, 16) to allow axial sliding of the front shaft (16) supporting the steering wheel, in succession, over a first depth adjustment range for depth adjustment of the steering wheel position starting from the most forward position, and over a second buffer range for absorbing the impact of the driver on the steering wheel in the event of an accident, the column comprising an electric motor (30) for controlling the sliding and anti-theft blocking means blocking the rotation of one of the shafts (16), which automatically engage to achieve an axial blocking position of the front shaft (16) provided by the electric motor (30) located in the second buffer range.

Description

Technical Field

[0001] The present invention relates to a steering column of a motor vehicle including an anti-theft system for preventing rotation, and a method for controlling the steering column. Background Technology

[0002] Motor vehicles include a steering column, which typically includes a front upper axle that receives a steering wheel at its front end. The steering wheel is rotatably connected to a lower axle that drives a steering box that performs the pivoting of the vehicle's front steering wheels.

[0003] Two telescopic shafts can slide axially between them to ensure depth adjustment of the steering wheel position within a first adjustment range, which forms the axial stroke of the steering wheel starting from its foremost position.

[0004] This slippage also ensures the possibility that the upper axle is pressed within a second buffer zone after the first zone during a collision at the front of the vehicle, thus achieving a buffer that absorbs and limits the energy of the force exerted by the driver on the airbag at the steering wheel.

[0005] As is well known, in order to perform the adjustment of the steering wheel depth position in an assisted or automatic manner, the electromechanical device performs longitudinal sliding of the guide duct that houses the front axle to guide the guide duct.

[0006] Furthermore, the steering column includes an anti-theft system for locking rotation. This system locks the steering column shaft, which is automatically actuated when the ignition key is removed. The steering column includes bolts connected to a support member of the column. These bolts slide into openings formed in a retaining ring fastened around the shaft of the column, ensuring that rotation is blocked. Specifically, the bolts can be actuated by disabling the electromechanical mechanism of the ignition control.

[0007] A known blocking system, specifically proposed in documents FR-A1-2861673 and EP-A1-0918000, includes a friction device mounted between the housing of the bolt and the shaft of the first document, or a friction device mounted between the column support and a sliding sleeve, the sliding sleeve accommodating an axially fixed rib disposed on the shaft of the second document, thereby providing the possibility of rotational sliding about the shaft above a predetermined torque. Specifically, the predetermined sliding torque includes a range of 100 Nm to 200 Nm, preferably 150 Nm.

[0008] In this way, in the event of an attempt to steal the vehicle, the operator applies high torque to the steering wheel in an attempt to break its obstruction. The obstruction ring stops rotating on the shaft before deformation or breakage of the mechanical components is achieved. In this way, by limiting the force, damage to the lock that would allow theft is avoided, and without such damage, deformation of the components would make driving dangerous and require replacement.

[0009] It should be noted that the high torque required to allow the blocking ring to slip requires excessive force on the steering wheel, which makes the vehicle unable to move while the blocking ring is in place.

[0010] However, by using an electromechanical device in this blocking system, the components are large in both diameter and axial length, and have high mass and cost. Furthermore, the engagement control of the motor provided by the vehicle's onboard network, and the operation of that motor, must be completely safe to avoid unintentional obstruction while driving, which complicates the system. Summary of the Invention

[0011] The purpose of this invention is, in particular, to avoid these disadvantages of the prior art.

[0012] Therefore, the present invention proposes a steering column for a motor vehicle, the steering column comprising two retractable drive shafts rotatably connected to allow axial sliding of the front axle supporting the steering wheel, sequentially from a foremost position, within a first depth adjustment range of the steering wheel position, and within a second buffer range for cushioning the impact of the driver on the steering wheel in the event of an accident. The column includes an electromechanical device for controlling the sliding and an anti-theft blocking device for preventing rotation of one of the shafts. Notably, the rotation blocking device automatically engages with the axial position for blocking the front axle provided by the electromechanical device located within the second buffer range.

[0013] The advantage of this type of steering column is that, after the ignition is turned off, the axial sliding of the front axle is performed using the existing motor to place it in an axially blocked position outside the first adjustment range used to drive the vehicle, avoiding the need to install a second electric device to actuate the locking system. This allows for a reduction in the size, weight, and cost of the steering column.

[0014] The steering column according to the invention may further include one or more of the following features, which may be combined with each other.

[0015] Advantageously, the axial position for blocking the front axle is set before the end of the stroke of the second buffer range. In this way, in the event of an accident that causes the front axle to be completely crushed, upon reaching the end of the second range, the locking system has passed through the axial blocking position and is not held therein, which maintains the steering of operation to continue maneuvering the vehicle as required by specific rules.

[0016] Advantageously, the rotation blocking device includes an inner ring having axial teeth on its outer contour, the axial teeth engaging between teeth disposed in the outer ring. This blocking system is easy to implement.

[0017] In this case, it is advantageous that the axial teeth of the inner and outer rings have axial tips on the mating side of the other ring.

[0018] Furthermore, it is advantageous that the inner and outer rings have axially pointed tips that protrude axially from other tips on the engagement side of the other ring.

[0019] Advantageously, the rotation blocking device includes a rotational sliding system that limits the torque transmitted by the device.

[0020] In this case, the sliding system advantageously includes an elastic ring forming a slot, the elastic ring being disposed between one of the rings and a part supporting the elastic ring.

[0021] Advantageously, the rotation stop device includes an axial safety system that, in the event of an accident, can be disengaged under axial force when the two parts of the rotation stop device come into contact during front axle displacement within the second buffer range.

[0022] In this case, the axial locking system may include an elastic clip made of a plastic material that axially retains at least one ring.

[0023] Specifically, the rotation blocking device may include an inner ring fastened to the rear axle and an outer ring fastened to a guide tube that performs the guidance of the front axle.

[0024] The present invention also relates to a method for controlling a steering column, the steering column including any of the foregoing features, the method systematically controlling the electric motor after the vehicle's ignition is turned off to bring the front axle into its axial position, thereby preventing rotation. Attached Figure Description

[0025] Referring to the accompanying drawings, the invention will be better understood by reading the following description given by way of example, and other features and advantages will become more apparent, wherein:

[0026] Figure 1 and Figure 2 The steering column according to the invention is shown in a partially cut-out perspective view and an axial section along a vertical plane, respectively.

[0027] Figure 3 This is a partially enlarged view of the axial section;

[0028] Figure 4 This is a magnified view of a portion of the perspective view;

[0029] Figure 5 This is an exploded view of the rear axle with an internal retaining ring;

[0030] Figure 6 The inner and outer retaining rings are described in detail; and

[0031] Figure 7a , 7b Figures 7c and 7d show the steering column in axial sections, which is positioned sequentially in the front adjustment position, rear adjustment position, locked position, and fully depressed position after an accident. Detailed Implementation

[0032] Figure 1 and Figure 2 A fixed support 4 for the steering column is shown, equipped with an upper pull ring configured for fastening beneath a crossbeam member of the vehicle's dashboard. This upper pull ring is connected to a movable support 2 via a transverse pivot 26 to allow for steering wheel height adjustment. The movable support 2 forms a closed housing that includes a rear ball bearing 6 on the rear side indicated by arrow AR. This rear ball bearing guides a rear axle 8 positioned along a main shaft forming the longitudinal direction.

[0033] The rear axle 8, which is axially wedged into the movable support 2 by the rear ball bearing 6, includes a turntable 10 at its rear end for connecting to the steering column, thereby connecting it to the vehicle's steering box.

[0034] The front sliding tube 12, guided in the hole of the movable support 2 that allows axial sliding, includes a front guide bearing 14 at its front end for receiving a front axle 16 of the steering column, which is axially wedged into the sliding tube by the front bearing.

[0035] In this way, the front axle 16 rotates freely in the sliding tube 12, but drives the tube as it slides along its axis.

[0036] The front axle 16 is formed of a tube that includes an external spline 18 at its front end for securing the steering wheel and an internal spline 20 along its rear length that engages with an external spline 22 formed around the rear axle 8 to ensure a rotatable connection.

[0037] An electromechanical device 30, having an axis perpendicular to the longitudinal axis, drives a gear reducer 32 forming an angular transmission. This gear reducer, in turn, drives a screw 34 arranged parallel to the main shaft below the movable support 2. A bracket 36, including a nut engaged in the screw 34, drives a sliding tube 12 via a curved metal blade 28, the sliding tube being fastened to the blade by a screw 24.

[0038] The curved metal blade 28, arranged parallel to the longitudinal axis, has a curvature of 180° so that its two ends are positioned below each other, one end connected to the bracket 36 and the other to the sliding tube 12. Thus, a rigid axial connection is achieved between the bracket 36 and the sliding tube 12 to perform steering wheel depth adjustment.

[0039] Specifically, the screw-nut connection between the screw 34 and the nut of the bracket 36 has irreversible kinematic characteristics. Due to the sufficiently small pitch of the screw, axial thrust on the nut will not cause rotation of the screw, thus avoiding misalignment of the steering wheel's depth position if the driver applies axial force to the steering wheel. For this purpose, an inclination of the thread relative to the axis of the screw 34 is advantageously achieved, ranging from 8 degrees to 20 degrees, preferably 12 degrees.

[0040] However, in the event of a frontal collision causing the steering wheel airbag to inflate, the driver's torso exerts a significant force on the steering wheel, which is transmitted from the front axle 18 to the sliding tube 12 held by the metal blade 28. For a sufficiently large force, the metal blade 28 gradually bends by absorbing energy and moving rearward through the sliding tube 12, reaching the bottom of the movable support 2 at the end of the stroke. Figure 7d As shown.

[0041] The rear axle 8 is supported by an inner retaining ring 40 with axial teeth on its contour, and the sliding tube 12 is supported by an outer retaining ring 50 with corresponding axial teeth inside. Figure 7c In the defined axial position of the tube shown, the inner and outer retaining rings engage with each other to achieve anti-theft rotational blocking for steering.

[0042] Figure 3 , 4 Figures 5 and 6 show an outer ring 50 rigidly fastened in the rear of the sliding tube 12, which includes a series of axial teeth, each axial tooth terminating at a rearward-facing tip 48.

[0043] The inner ring 40, which is flexibly fastened to the rear axle 8, includes a series of axial teeth on its outer side, each axial tooth terminating at a forward-facing tip 48, thereby enabling it to engage axially in the teeth of the outer ring 50.

[0044] The elastic ring 42, made of an elastomer, has a profile forming a series of slots, including a groove on the inner side receiving a corresponding axial tooth 60 formed around the rear axle 8, and a groove on the outer side receiving a corresponding axial tooth 46 formed in the inner ring 40. The inner diameter of the teeth of the outer ring 50 is larger than the outer diameter of the teeth of the inner ring 40.

[0045] In this way, a component is obtained that is blocked when the inner ring 40 on the shaft 8 rotates, and the component has a small degree of flexibility that allows noise to be avoided when stress is applied to the inner ring.

[0046] Advantageously, the elastic ring 42 is made of an elastomer having a glass transition temperature between -80°C and +30°C, preferably close to -40°C. For this purpose, materials of the thermoplastic elastomer type, EPDM, NBR, hydrogenated nitrile butadiene rubber (HBNR), or silicone resin can be used.

[0047] When the current shaft 8 moves backward, the rear tip 48 on the axial teeth of the outer ring 50 and the front tip of the inner ring 40 facilitate the insertion of the outer ring teeth into the inner ring teeth.

[0048] Furthermore, advantageously, longer teeth are formed on each ring 40, 50, having an extension of approximately 0.5 to 3 mm, preferably 1 mm, facing the other ring. This extension is slightly angled to prepare for engagement of the remaining teeth by small-angle rotation if necessary. The deformable nature of the elastic ring 42 makes this small rotation possible, allowing the inner ring 40 to rotate slightly about the rear axle 8, so that the teeth of the two rings 40, 50 can cooperate together without obstructing each other.

[0049] An open, resilient clip 44 is fastened in grooves on each side of the inner ring 40 of the rear axle 8 to maintain the axial position of the ring and the resilient ring member 42.

[0050] Figure 7a and 7b The maximum forward position A and maximum rearward position B for steering wheel depth adjustment are shown respectively, which are performed by the motor 30 within the framework of normal driving of the vehicle, wherein the adjustment range PR is included between these two maximum values, typically 30 to 50 mm.

[0051] Figure 7c The locking position C is shown. This locking position is systematically set after the driver turns off the ignition and each time the vehicle stops by the motor 30, by moving the guide 12 backward so that the outer ring 50 is aligned with the inner ring 40 after the teeth of the outer and inner rings engage with each other.

[0052] By using the existing steering wheel depth adjustment mechanism 30 and its control circuit, steering locking is achieved in a simple and cost-effective manner with very few additional components.

[0053] It should be noted that the locking position C is significantly moved backward relative to the steering wheel depth adjustment range PR, creating space in front of the steering wheel, which makes it easier for the driver to enter or exit the vehicle.

[0054] Figure 7d The following position D after the accident is shown, obtained from the position within the adjustment range PR, where the driver has applied significant force to the steering wheel, deforming the steering wheel by fully unfolding the bent metal blade 28, so as to place the conduit 12 in the rear stop after passing the buffer range PA after the adjustment range.

[0055] In this configuration, the outer ring 50 passes over the inner ring 40 so as to be behind the inner ring without being obstructed by it. This allows for complete steering freedom, enabling compliance with certain regulatory requirements that may require steering via the steering wheel in this configuration.

[0056] Optionally, the inner ring 40 assembly may include an axial force fuse, including, for example, an elastic clip 44 made of a plastic material, to allow the front axle 16 to move fully rearward by breaking under impact in the event of an accident, where the teeth of the two rings 40, 50 are abutting each other and cannot be angularly aligned to release the passage.

[0057] Alternatively, any other arrangement of rings 40 and 50 can be used. In particular, a system can be provided that allows the outer ring 50 to slide rotatably relative to the guide 12 at a sufficiently high torque threshold, preferably in the range of 150 Nm, to prevent damage to the steering column in the event that a malicious person applies high torque to the steering wheel in an attempt to break its lock. Rings 40 and 50 can also be axially positioned in other locations within the movable support 2.

Claims

1. A steering column for a motor vehicle, comprising a rotatably connected front axle and a rear axle to allow axial sliding of the front axle, which supports a steering wheel, sequentially from a foremost position, within a first depth adjustment range of the steering wheel position, and then within a second buffering range for cushioning impacts on the steering wheel in an accident, the steering column comprising a motor mechanism for controlling the sliding and a blocking device, the blocking device being configured to block rotation of the front axle when engaged, wherein: The blocking device is automatically engaged to block the front axle. When the blocking device is engaged to block the front axle, the front axle is positioned in an axial position provided by the motor mechanism, which is within the second buffer range. The blocking device includes an inner ring having axial teeth on its outer contour, the axial teeth engaging with axial teeth disposed in the outer ring. The axial teeth of each of the inner ring and the outer ring have axially pointed tips on the axial meshing side between the axial teeth of the other of the inner ring and the outer ring, and Each of the inner ring and the outer ring has a tip that protrudes axially beyond the other tip on the axial tooth engagement side between the axial teeth of the other of the inner ring and the outer ring.

2. The steering column according to claim 1, wherein, The axial position used to stop the front axle is set before the end of the stroke in the second buffer range.

3. The steering column according to any one of claims 1-2, wherein, The blocking device includes a rotational sliding system that limits the torque transmitted by the blocking device.

4. The steering column according to claim 3, wherein, The rotary sliding system includes an elastic annular member forming a slot, the elastic annular member being disposed between one of the inner ring and the outer ring and a component supporting the elastic annular member.

5. The steering column according to any one of claims 1-2, wherein, The blocking device includes an axial safety system that, in the event of an accident, can be disengaged under axial force when two parts of the blocking device come into contact with each other while the front axle is moving within the second buffer range.

6. The steering column according to claim 5, wherein, The axial locking system includes a resilient clip made of a plastic material that axially holds at least one of the inner ring and the outer ring.

7. The steering column according to claim 1, wherein, The inner ring is fastened to the rear axle, and the outer ring is fastened inside the conduit, which guides the front axle.

8. A method for controlling a steering column for a motor vehicle according to any one of the preceding claims, comprising systematically controlling the motor mechanism after the ignition of the motor vehicle is turned off to position the front axle in its axial position to resist rotation.

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