Steering column equipped with a device for detecting forces applied to the steering wheel

Abstract

The invention proposes a steering column (10), comprising: a support base, which is intended to be fixedly mounted relative to a vehicle chassis; a steering member (16), on which a vehicle steering wheel is mounted, the steering member (16) comprising a transmission shaft (20), which is mounted so as to rotate relative to the support base about a longitudinal main axis (A1), characterized in that the steering column has at least one force sensor (32), which is inserted between a first non-rotating element (34) of the steering column (10) and a second non-rotating element (36) belonging to the steering column (10) or to the chassis of the vehicle.

Description

Technical Field

[0001] The present invention relates to a vehicle steering column, in particular a vehicle steering column designed for use in a motor vehicle that can be operated in a manual driving or assisted driving mode and in a delegated driving or autonomous driving mode. Background Art

[0002] In a vehicle, the steering column transmits the rotation of the steering wheel to the wheels in order to modify their orientation, for example in the following order: steering wheel, steering column, intermediate shaft, rack and finally wheels.

[0003] Some motor vehicles may be equipped with a driving assistance system that allows the driver to delegate the driving of the vehicle, at least temporarily, to a central control unit. It is then a delegated driving mode, or an automatic or autonomous driving mode. In this case, it is important to know how to detect the driver's intention to return to driving in manual mode. This desire detection allows the vehicle to ensure that the driver is aware that he or she is again in charge of driving. The driver plays an active role in returning to manual driving mode after driving in delegated mode.

[0004] It is known practice to measure the force applied by the driver to the transmission shaft or the steering wheel in order to detect the driver's desire to pull the steering wheel closer and return it to a comfortable driving position.

[0005] However, this type of solution is not entirely satisfactory since it requires a sometimes complex and expensive detection system.For example, some of the known systems require that electrical connections be made on the rotating part. Summary of the invention

[0006] The present invention aims to overcome the above mentioned problems by proposing a simple and economical solution.

[0007] The present invention provides a steering column, which comprises:

[0008] a supporting base, which is intended to be fixedly mounted relative to the vehicle chassis,

[0009] a steering member on which the vehicle steering wheel is mounted, the steering member comprising a drive shaft mounted so as to rotate relative to the support base about a longitudinal main axis,

[0010] It is characterized in that the steering column has at least one force sensor which is inserted between a first non-rotating element of the steering column and a second non-rotating element belonging to the steering column or to the chassis of the vehicle.

[0011] The invention thus makes it possible to detect in a precise manner the forces exerted by the driver on the steering wheel and to trigger an operation, such as a movement of the steering wheel, depending on predetermined criteria in order to allow the driver to resume control in manual mode.

[0012] According to other favorable features:

[0013] - at least one force sensor is radially interposed between the first non-rotating element and the second non-rotating element;

[0014] - at least one force sensor is interposed axially between the first non-rotating element and the second non-rotating element;

[0015] - the first non-rotating element is an annular part with a longitudinal axis having a first inner recess designed to receive an outer ring of a rolling bearing of the transmission shaft;

[0016] - the second non-rotating element comprises an annular body having a longitudinal axis and a second inner recess is formed in the annular body for receiving the first non-rotating element;

[0017] - a second inner recess is delimited by: a first radial wall and an axial wall of the annular body and also by a second radial wall belonging to an end sleeve fastened to the annular body;

[0018] - a second non-rotating element is fastened to a tube mounted so as to slide longitudinally in the support base so as to be able to adjust the longitudinal position of the steering wheel, the transmission shaft being connected to the support base via this sliding tube;

[0019] - the first non-rotating element is fastened to a supporting base of the steering column and the force sensor is arranged on the supporting base of the steering column so as to be interposable between the supporting base and an element of the chassis of the vehicle;

[0020] - Each force sensor has a strain gauge;

[0021] - at least one force sensor is configured to detect shear forces;

[0022] - at least one force sensor is configured to detect a compressive force or a tensile force;

[0023] - the column has a plurality of force sensors which are distributed circumferentially around the transmission shaft;

[0024] - the column has an electronic control unit configured to use information provided by the one or more force sensors in order to detect a specific tactile sequence applied by the driver to the steering wheel and to trigger a determined operation depending on the detected tactile sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other characteristics and advantages of the invention will become more clearly apparent on reading the following detailed description of an embodiment of the invention, given by way of non-limiting example and illustrated by the accompanying drawings, in which:

[0026] [ Figure 1 ] is a diagram showing a motor vehicle equipped with a steering column in accordance with the teachings of the present invention;

[0027] [ Figure 2 ] is shown Figure 1 A view in longitudinal axial section of a steering column;

[0028] [ Figure 3 ] is a diagram showing a first embodiment according to the present invention Figure 2 A view in longitudinal axial section of a detail of a top portion of a steering column in FIG. 1 , which top portion shows the arrangement of the force sensors;

[0029] [ Figure 4 ] is a diagram showing the arrangement of a force sensor according to a first embodiment of the present invention. Figure 3 A cross-sectional view on plane 4-4 in FIG.

[0030] [ Figure 5 ] is related to Figure 3 A view similar to the view in FIG. 1 , which shows a second embodiment of the present invention;

[0031] [ Figure 6 ] is related to Figure 4 The view in is similar to Figure 5 A view on plane 6-6 in FIG. 1 , which shows a second embodiment;

[0032] [ Figure 7 ] is a block diagram according to one of the embodiments of the present invention, which shows Figure 1 A steering column 10 of a vehicle is provided with a force sensor. DETAILED DESCRIPTION

[0033] Figure 1 A motor vehicle 11 is shown which is equipped with a steering column 10 . Figure 2 The steering column 10 shown in more detail in FIG. 1 comprises a support base 12 intended to be fixedly mounted relative to a chassis of a vehicle 11, for example fastened to a crossbeam 14. The steering column 10 comprises a steering member 16 on which a steering wheel 18 is mounted, which steering member rotates about a longitudinal main axis A1.

[0034] The steering column 10 may also be mounted so as to pivot about the transverse axis B1 , so as to allow adjustment of its inclination.

[0035] In the remainder of this description, by way of non-limiting example, a bottom-up orientation along the longitudinal axis A1 will be used, with the top corresponding to the axial end where the steering wheel 18 is located.

[0036] The steering member 16 comprises a drive shaft 20 mounted so as to rotate about the longitudinal main axis A1 relative to the support base 12. According to the embodiment shown here, the drive shaft 20 supports the steering wheel 18 at its upper axial end and is guided in rotation inside a tube 22 mounted so as to slide longitudinally in the support base 12, so as to be able to adjust the depth of the steering column 10.

[0037] like Figure 3 As shown in , in this case the transmission shaft 20 is guided in rotation by means of a column top rolling bearing 24 which is arranged in the top part of the tube 22 between the tube 22 and an outer axial surface 26 of the transmission shaft 20 .

[0038] In this case, the column top rolling bearing 24 has an outer rolling bearing ring 28 on the side of the tube 22 and an inner rolling bearing ring 30 on the side of the drive shaft 20 .

[0039] according to Figure 3 and Figure 4 In the first embodiment shown in FIG. 1 , the steering column 10 has three force sensors 32 which are inserted between a first non-rotating element 34 of the steering column 10 and a second non-rotating element 36 of the steering column 10 .

[0040] Advantageously, the three force sensors 32 are distributed circumferentially around the drive shaft 20 in a regular manner, with a space of approximately 120 degrees between each force sensor 32 .

[0041] Alternatively, there may be only a single force sensor 32 , or only two force sensors 32 diametrically opposite each other with respect to the longitudinal axis A1 , or else four force sensors 32 distributed every 90 degrees.

[0042] According to this first embodiment, each force sensor 32 is radially interposed between a first non-rotating element 34 and a second non-rotating element 36. The force sensors 32 preferably have strain gauges 38 designed to detect shear forces, i.e., in this case, relative movements of the first non-rotating element 34 in the longitudinal direction with respect to the second non-rotating element 36. This allows the force sensors 32 to measure the longitudinal component of the force exerted by the driver on the steering wheel 18.

[0043] The strain gauge 38 is, for example, of the resistive type or of the piezoelectric type. In the case of a strain gauge 38 of the piezoelectric type, it is mounted under preload, in this case radially between the first non-rotating element 34 and the second non-rotating element 36. Other types of strain gauges 38 may also be used, in particular strain gauges 38 that do not need to be mounted under preload.

[0044] According to a first embodiment, the first non-rotating element 34 is an annular part with a longitudinal axis having a first inner recess 40 designed to receive the outer ring 28 of the cylindrical rolling bearing 24. In this case, the first inner recess 40 has the form of a groove whose longitudinal dimension is substantially equal to the longitudinal dimension of the outer ring 28, so that the outer ring is longitudinally retained in the first inner recess 40. In this case, the first non-rotating element 34 has an outer axial surface 42.

[0045] The second non-rotating element 36 has a second inner recess 44 formed in an annular body 46 with a longitudinal axis in order to receive the first non-rotating element 34. The second inner recess 44 is delimited on the lower side by a first radial wall 48 and an axial wall 50 forming a shoulder in which the first non-rotating element 34 is axially housed. The upper axial end of the second inner recess 44 is delimited by a second radial wall 52 which, in this case, belongs to an end sleeve 54 which is fastened to the annular body 46 by any suitable means.

[0046] In the first embodiment, the second non-rotating element 36 is secured inside the tube 22 .

[0047] In this case, each force sensor 32 is interposed directly between the outer axial surface 42 of the first non-rotating element 34 and the axial wall 50 of the second inner recess 44 of the second non-rotating element 36 .

[0048] The first non-rotating element 34 and the second non-rotating element 36 allow the force sensor 32 to be placed under radial preload, if necessary, in order to ensure optimal detection of the shear forces when the forces exerted by the driver on the steering wheel 18 are transmitted to the outer rolling bearing ring 28. Thus, the force sensor 32 measures the longitudinal component of the force exerted by the driver.

[0049] according to Figure 5 and Figure 6 In the second embodiment shown in FIG. , the first additional force sensor 56 is arranged between the first radial wall 48 of the second inner recess 44 and the lower radial wall 58 of the first non-rotating element 34 , and the second additional force sensor 60 is arranged between the upper radial wall 62 of the first non-rotating element 34 and the second radial wall 52 of the second inner recess 44 .

[0050] The additional force sensors 56, 60 are designed, for example, to each detect a longitudinal compressive force. Alternatively, one of the additional sensors 56, 60 can be designed to detect a radial shear force.

[0051] In this second embodiment, the force sensor 32 disposed between the outer axial surface 42 of the first non-rotating element 34 and the axial wall 50 of the second inner recess 44 may be designed to detect radial compressive forces instead of shear forces.

[0052] exist Figure 5 and Figure 6 In the exemplary embodiment shown in , there are several groups G1, G2, G3, G4 of force sensors 32, 56, 60, which are distributed circumferentially around the transmission shaft 20 (in this case, every 90 degrees). In this case, each group G1, G2, G3, G4 of force sensors 32, 56, 60 has a force sensor 32 (which is mounted in radial compression between the outer axial surface 42 of the first non-rotating element 34 and the axial wall 50 of the second inner recess 44), a first additional force sensor 56 and a second additional force sensor 60. Figure 6 In the view in , only the radially compressed force sensor 32 is visible.

[0053] By means of these additional force sensors 56, 60, in combination with the force sensor 32, it is possible to detect all components of the force applied by the driver to the steering wheel 18 and transmitted via the transmission shaft 20 to the column top rolling bearing 24, i.e. longitudinal axial forces, forces in radial direction upwards or downwards, and forces in radial direction towards the sides (i.e. taking into account the longitudinal axial forces, the forces in radial direction upwards or downwards, and the forces in radial direction towards the sides). Figure 1 vehicle 11, along a horizontal lateral direction corresponding to the lateral axis B1).

[0054] It will be noted that in the presence of two additional groups of force sensors 56 , 60 configured to detect shear forces and not diametrically opposed to each other, such as, for example, a first group G1 and a second group G2 , it is possible to determine both the vertical and lateral components.

[0055] According to a variant of the second embodiment, it is possible to omit one of the additional force sensors 56 , 60 in each group G1 , G2 , G3 , G4 .

[0056] According to a third embodiment (not shown), the first non-rotating element 34 is fastened to the supporting base 12 of the steering column 10 and the second non-rotating element 36 is arranged on an element of the chassis of the vehicle 11 , for example on the cross member 14 .

[0057] Figure 7In block diagram form, a steering column 10 and its electronic control unit 64 are shown, which is designed to control an adjustment motor 66 for positioning the steering column 10 in a suitable manner. The electronic control unit 64 is configured to control the inclination of the steering column 10 about a transverse axis B1, which allows the height of the steering wheel 18 to be adjusted for the driver. The electronic control unit 64 can also control the depth of the steering wheel 18 by adjusting the longitudinal position of the steering wheel 18 along the axis A1 with the help of the adjustment motor 66.

[0058] Advantageously, the electronic control unit 64 is configured to control the steering wheel 18 so that it assumes a retracted state corresponding to a delegated driving mode (in which the driver does not need to manipulate the steering wheel 18), and so that it assumes a standard state corresponding to a manual driving mode (in which the driver controls the steering of the vehicle 11 with the help of the steering wheel 18).

[0059] The force sensors 32, 56, 60 are connected to the electronic control unit 64, which allows the electronic control unit 64 to measure the value of the force applied by the driver on the steering wheel 18. Thus, the electronic control unit 64 can detect a longitudinal force (e.g., a tensile force) exceeding a predetermined threshold, which indicates that the driver wants to regain control of the steering by pulling the steering wheel 18 from the retracted position to the standard position. To this end, the electronic control unit 64 can use a combination of the following parameters: value and direction of the force, duration and axial position of the steering wheel 18.

[0060] According to a variant embodiment, the electronic control unit 64 can also use the information provided by the force sensors 32, 56, 60 in order to detect a specific tactile sequence applied by the driver to the steering wheel 18 with a view to triggering the determined operation. For example, three repeated longitudinal presses within a period of three seconds can allow the driver to control the steering wheel 18 so that it adopts the retracted position. It is also possible to decompose the tactile control along three main axes, which makes it possible to quantify the forces necessary for the tactile control in a very precise way in space.

[0061] In this case, the electronic control unit 64 determines the maximum value of the axial force, the duration between the peaks, the number of peaks and the direction of the peaks when force peaks occur, in order to detect a control intention on the part of the driver.

[0062] Measuring the forces along multiple axes makes it possible to know the values ​​of the forces applied to the steering wheel 18 in multiple planes. This is advantageous, in particular, because a driver positioned facing the steering wheel 18 does not always know the angle at which he or she applies the forces to the steering wheel 18, nor the precision of the way in which he or she applies the forces. It is therefore possible to measure the absolute value of the forces applied by the driver along each axis, independently of the direction in which the driver applies the forces to the steering wheel 18. The direction for applying the forces is not imposed on the driver.

[0063] One advantage of using multiple force sensors 32 , 56 , 60 distributed around the drive shaft 20 is that it is possible to accurately detect any type of force applied by the driver to the steering wheel 18 regardless of the orientation of the steering wheel 18 and regardless of the driver's position relative to the steering wheel 18 .

Claims

1. A steering column (10), comprising: a support base (12) intended to be fixedly mounted relative to the vehicle chassis, a steering member (16) on which a vehicle steering wheel (18) is mounted, the steering member (16) comprising a transmission shaft (20) mounted so as to rotate relative to the support base (12) about a longitudinal main axis (A1), The invention is characterized in that the steering column (10) has at least one force sensor (32, 56, 60), which is inserted between a first non-rotating element (34) of the steering column (10) and a second non-rotating element (36) belonging to the steering column (10) or to the chassis of the vehicle (11), And wherein the first non-rotating element (34) is an annular component with a longitudinal axis (A1) having a first inner recess (40) designed to receive an outer ring (28) of a rolling bearing (24) of the transmission shaft (20).

2. Steering column (10) according to the preceding claim, characterized in that At least one force sensor (32, 56, 60) is radially interposed between the first non-rotating element (34) and the second non-rotating element (36).

3. A steering column (10) according to any one of the preceding claims, characterised in that At least one force sensor (32, 56, 60) is interposed axially between the first non-rotating element (34) and the second non-rotating element (36).

4. A steering column (10) according to any one of the preceding claims, characterised in that The second non-rotating element (36) comprises an annular body (46) having a longitudinal axis (A1), and wherein a second inner recess (44) is formed in the annular body (46) for receiving the first non-rotating element (34).

5. The steering column (10) according to claim 4, characterized in that The second inner recess (44) is delimited by a first radial wall (48) and an axial wall (50) of the annular body (46), and also by a second radial wall (52) belonging to an end sleeve (54) fastened to the annular body (46).

6. A steering column (10) according to any one of the preceding claims, characterised in that The second non-rotating element (36) is fastened to a tube (22) which is mounted so as to slide longitudinally in the support base (12) so as to be able to adjust the longitudinal position of the steering wheel (18), the transmission shaft (20) being connected to the support base (12) via the sliding tube (22).

7. The steering column (10) according to any one of claims 1 to 3, characterized in that The first non-rotating element (34) is fastened to the support base (12) of the steering column (10), and wherein the force sensor (32, 56, 60) is arranged on the support base (12) of the steering column (10) so as to be insertable between the support base (12) and an element of the chassis of the vehicle (11).

8. A steering column (10) according to any one of the preceding claims, characterised in that Each force sensor (32, 56, 60) has a strain gauge (38).

9. A steering column (10) according to any one of the preceding claims, characterised in that At least one force sensor (32, 56, 60) is configured to detect shear forces.

10. A steering column (10) according to any one of the preceding claims, characterised in that At least one force sensor (32, 56, 60) is configured to detect a compressive force or a tensile force.

11. A steering column (10) according to any one of the preceding claims, characterised in that It has a plurality of force sensors (32, 56, 60) distributed circumferentially around the transmission shaft (20).

12. A steering column (10) according to any one of the preceding claims, characterised in that It has an electronic control unit (64) configured to use information provided by the one or more force sensors (32, 56, 60) in order to detect a specific tactile sequence applied to the steering wheel (18) by the driver and to trigger a determined operation dependent on the detected tactile sequence.

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