BE1031363B1 - steering column for a motor vehicle - Google Patents

Abstract

The present invention relates to a steering column (1) for a motor vehicle, comprising a casing tube (24) with a longitudinal axis (L) extending in the longitudinal direction, which is accommodated in a support unit (22) so as to be adjustable in the longitudinal direction over an adjustment path, wherein an electromotive adjustment drive (5) is provided for adjusting the casing tube (24) relative to the support unit (22), and a sensor device for detecting the position of the casing tube (24) relative to the support unit (22). In order to enable improved operation of the adjustment with less effort, the invention proposes that the sensor device has a force threshold device (6) which is operatively arranged between the casing tube (24) and the support unit (22) within the adjustment path and which is designed to generate a defined force threshold that can be overcome in the longitudinal direction when adjusting the casing tube (24) relative to the support unit (22).

Description

" BE2023/5131

steering column for a motor vehicle

State of the art

The invention relates to a steering column for a motor vehicle, comprising a casing tube with a longitudinal axis extending in the longitudinal direction, which is accommodated in a support unit so as to be adjustable in the longitudinal direction over an adjustment path, wherein an electromotive adjustment drive for

Adjustment of the jacket tube relative to the support unit is provided, and a sensor device for detecting the position of the jacket tube relative to the support unit. A method for measuring the adjustment state of a steering column is also the subject of the invention.

Such a steering column for a motor vehicle has a casing tube. In this, for example, a steering spindle can be mounted so as to be rotatable about its longitudinal axis, at the rear end of which, in the direction of travel and facing the driver, a manual steering input device, for example a

Steering wheel for manual steering commands by the driver. This

Arrangement is also referred to as an adjusting unit. The steering column is held by a support unit attached to the vehicle body, whereby the adjustment of the steering wheel position relative to the

vehicle body is made possible.

For longitudinal adjustment, it is known in the prior art to provide a motorized adjustment drive with an electric motor, which is mounted in the longitudinal direction on the support unit and the

jacket tube. This allows the jacket tube to be positioned within a predetermined adjustment range.

To determine the adjustment state, which corresponds to the position of the jacket tube relative to the support unit, a sensor device with a position detection device for absolute position detection can be provided, as described for example in DE 10 2020 202 536 A1 or DE 10 2020 205 731 A1. This has one or more in the course of the

Sensor elements arranged along the travel path can output an electrical position signal corresponding to the adjustment state. This can be used to control the adjustment drive, for example to automatically set a specified adjustment.

? BE2023/5131 can. Using such a sensor arrangement, reliable absolute position detection and adjustment is possible. However, the required electrical control and the structural integration of the electronic sensor elements is complex.

It is also possible to use a defined end position of the adjustment to determine the absolute adjustment position from the relative adjustment generated by the adjustment drive.

Ben. In order to avoid tolerances due to slippage and the like, a regular

Calibration of the adjustment drive is required, for example when commissioning the vehicle. The adjustment drive is moved to a defined reference point, namely against an end stop at the end of the adjustment path, or against both end stops one after the other. This allows reliable relative positioning to be achieved without additional electrical position detection devices. The disadvantage, however, is that

Calibration requires relatively long adjustment distances to the end stop, which can result in delays in operation and increased energy consumption.

A steering column of the type mentioned above is also known from DE 10 2019 108466 A1.

In view of the problems explained above, it is an object of the present invention to enable improved operation of the adjustment with less effort.

representation of the invention

This object is achieved according to the invention by the steering column with the features of claim 1 and the method according to claim 11. Advantageous further developments emerge from the subclaims.

In a steering column for a motor vehicle, comprising a casing tube with a longitudinal axis extending in the longitudinal direction, which is accommodated in a support unit so as to be adjustable in the longitudinal direction over an adjustment path, wherein an electromotive adjustment drive for adjusting the

casing pipe relative to the support unit is provided, and a sensor device for detecting the position of the casing pipe relative to the support unit, the invention provides that the

Sensor device has a force threshold device which is arranged within the adjustment path between the casing tube and the support unit and which is designed to

° BE2023/5131 defined force threshold that can be overcome in the longitudinal direction when adjusting the casing tube relative to the support unit.

The force threshold device according to the invention forms a mechanical threshold value transmitter (force threshold value transmitter) which is arranged within the possible adjustment path, i.e. between the ends. Preferably, mechanical end stops are provided at the ends in a manner known per se, which cannot be overcome by the adjustment drive and which limit the adjustment path. In contrast, the force threshold device generates

An increased mechanical resistance, which is opposite to the adjustment movement, is created over a relatively short section of the adjustment path that is limited in the longitudinal direction. This increases the adjustment force required for adjustment in the longitudinal direction in a defined section within the adjustment range to a defined force threshold value, which creates a so-called force threshold.

The force threshold device can be overcome by the adjustment drive. When the force threshold is passed during adjustment, a characteristic force peak occurs, also known as a force peak, in which, at an approximately constant adjustment speed, the adjustment force required for adjustment initially increases significantly compared to the normal adjustment force that must be used for adjustment within the remaining adjustment range outside the force threshold device, and then drops back to the normal adjustment force. The occurrence of the force peak indicates that the steering column is in the position clearly defined by the

The absolute adjustment position defined by the force threshold device is thus enabled. This enables calibration of the adjustment.

An advantage of the invention is that for calibration it is no longer necessary, as in the prior art, to move the adjustment drive over the entire adjustment range up to an end stop, but only up to the force threshold within the adjustment range.

This allows calibration to be faster and more energy efficient.

Another significant advantage is that the force threshold device according to the invention can be designed purely mechanically. The detection of the characteristic force peak can be carried out by means of the motor drive of the actuator, for example by evaluating operating parameters such as the electrical operating current of the motor, the number of revolutions of the motor, the adjustment speed or the like.

° BE2023/5131

It is also conceivable and possible to measure the applied adjustment force via a force sensor, which can, for example, be integrated into the actuator or inserted between the actuator and the casing tube or the support unit.

A steering spindle can preferably be mounted in the casing tube so as to be rotatable about the longitudinal axis.

At the rear end facing the driver's position, in relation to the direction of travel,

A steering handle, such as a steering wheel or the like, must be attached for entering manual steering commands. This arrangement is also referred to as an actuating unit.

The steering spindle can be rotated by turning the steering wheel. In a steer-by-wire steering system, the rotation can be detected by means of rotation sensors and converted into electrical steering commands, which can be used to control electrical steering actuators to generate a steering stop of the steerable

wheels can be controlled.

It is preferably provided that the sensor device has at least one sensor element which is designed to detect the force threshold generated by the force threshold device. The sensor element comprises a force sensor by means of which the adjustment force exerted by the adjustment drive in the longitudinal direction between the casing tube and the support unit during adjustment can be measured directly or indirectly. The force sensor can, for example, have an electrical current sensor which measures and monitors the operating current of the motor of the actuator. When the force threshold is passed, a corresponding force peak occurs.

current peak, which can be electronically evaluated and used for calibration. The

The advantage is that the position can be determined using an electrical motor control unit, whereby no further electrical components are required outside of the adjustment drive.

An advantageous embodiment provides that the force threshold device has at least one cam element protruding from the casing tube transversely to the longitudinal axis, with which a touch element protruding on the support unit transversely to the longitudinal axis cooperates. The cam element has a profile cross-section protruding outwards from the casing tube in a cam-like manner over a limited longitudinal section, which during adjustment in the longitudinal direction in a

The probe element protrudes from the outside, radially into

In the direction of the longitudinal axis. This allows the probe element to come into mechanical contact with the cam element during adjustment, whereby the adjustment force is increased over a short section of the adjustment path to generate a force peak.

> BE2023/5131

So that the cam element can be moved past the touch element in the longitudinal direction, it can preferably be provided that the touch element can move outwards transversely to the longitudinal direction when passing the cam element. This can be achieved, for example, by the touch element being designed to be flexible in itself, for example with a spring element, or additionally or alternatively being held displaceably on the support element transversely to the longitudinal axis.

It is advantageous that the touch element is pre-tensioned against the cam element. The touch element is loaded transversely to the longitudinal axis, in the direction of the cam element, spring-loaded or elastically. This can be done by means of a pre-tensioning device which has a spring element supported on the support unit and which elastically supports the touch element transversely to the longitudinal axis in the direction of the casing tube, as seen from the support unit. Alternatively, the touch element can be designed to be spring-loaded. Outside the cam element, the touch element can be spaced apart from the casing tube. Accordingly, mechanical contact only occurs when the protruding cam element presses the touch element into the casing tube when adjusting it.

The sensing element is moved by the cam element against the direction of

Preload is forced outwards. The force required for this is introduced by the adjustment force, which increases accordingly and then decreases again when it has passed the cam element. This creates a force peak of the adjustment force.

It is preferably provided that the cam element and the probe element are in

Have contact surfaces that can be brought into contact. These contact surfaces correspond to one another and extend longitudinally and transversely to it. The length of the force threshold can be determined by the longitudinal extension of the contact surfaces, and the height of the force peak can be determined by their height transversely to the longitudinal axis. The cam element and the probe element can slide along one another longitudinally and transversely to it on the contact surfaces.

It can preferably be provided that the contact surfaces are designed to be ramp-like, rising and falling at an angle to the longitudinal axis, at least in sections, in the course of the longitudinal direction. The ramp-like design provides that a contact surface is inclined at an angle to the longitudinal direction, at least in sections. This forms a type of wedge-shaped ramp. A straight or curved slope can be designed. For example, the cam element can have an ascending and a descending ramp, and the probe element can have a conical or spherical tip, which when passing the

Cam element is first moved outwards by one ramp, and the other

° BE2023/5131

Following the ramp, it slides back inwards into the starting position. In a possible further development, a plateau section can be formed between the ramps, the course of which is parallel to the longitudinal direction. The length, height and shape of the force peak can be specified with little structural effort through the geometric design of the contact surfaces.

It is possible for the cam element to have an insert part connected to the casing tube. An insert part can be designed as an insert that is subsequently attached to the casing tube. This has the advantage that the position of the cam element can be easily changed and the geometry of the cam element can be adjusted independently of the casing tube, for example to optimize the profile of the force peak. Another

The advantage is that the material of the cam element can be selected independently of the material of the casing tube in order to optimize its functionality. For example, the cam element can be designed as a hard and wear-resistant sintered part, and/or the sliding properties can be optimized, or the like.

It can preferably be provided that the sensor device has a current sensor of the adjustment drive. The operating current of the electric motor of the adjustment drive is measured by means of the current sensor. The force peak generated when passing the force threshold device according to the invention causes the adjustment force required for further adjustment to initially increase significantly. The operating current of the motor increases accordingly. This

The increase in current can be recorded and evaluated. After passing the force threshold device, the adjustment force falls back to the normal value as before the force threshold device, and the current curve follows the shape of the force peak. This makes it possible to reliably detect that the steering column has reached and passed the adjustment position clearly defined by the position of the force threshold device. An advantage of the arrangement according to the invention is that the sensor device does not require any additional electrical sensors between the casing tube and the support unit, but only the force threshold, which can be represented purely mechanically according to the invention. This saves effort and costs.

It is also conceivable that the sensor device has a displacement sensor that interacts with the probe element. The displacement sensor is designed to detect a displacement of the probe element caused by the cam element, for example by means of a switching contact, or an inductive or capacitive measurement or the like. A

Displacement sensor means increased effort, but can be provided additionally

/ BE2023/5131 to enable redundant measurement.

It is possible to provide a plurality of force threshold devices. These can, for example, be arranged at a distance from one another in the longitudinal direction. This makes it possible to provide additional reference points for calibrating the stall drive with little effort.

The invention further relates to a method for measuring the adjustment state of a steering column for a motor vehicle, comprising a casing tube in which a steering spindle is mounted so as to be rotatable about a longitudinal axis extending in the longitudinal direction, and which is accommodated in a support unit so as to be adjustable in the longitudinal direction over an adjustment path, wherein an electromotive adjustment drive is provided for adjusting the casing tube relative to the support unit, and a sensor device for detecting the position of the casing tube relative to the support unit, in which it is provided according to the invention that the sensor device detects a change in the adjustment force when the casing tube is adjusted relative to the support unit, which change is generated when passing a force threshold device effectively arranged between the casing tube and the support unit within the adjustment path.

The force threshold device can be designed as described above for the reading column. All of the features mentioned in this context can be used individually or in combination for the method according to the invention.

The method according to the invention is based on generating at least one defined force peak of the adjustment force over the course of the adjustment path. This means that additional external electrical position detection can be omitted.

The defined force peak can be easily generated purely mechanically using the force threshold device, as described above.

It is advantageous that the change in the actuating force is converted into an electrical control signal to define a fixed reference position. The signal generated by the change in the adjusting force when passing the force threshold device can be used to calibrate the steering column. The current adjustment state is equated with a specified reference value within the available adjustment range, which is known as

The initial value can be used for further adjustments. An advantage over the

State of the art, which only has an end stop at the end of the adjustment path to generate

© BE2023/5131 of a reference value is that it enables the steering column to be calibrated with shorter adjustment paths. In contrast to the state of the art, the steering column does not have to be moved to the end stop by the adjustment drive, but only to the adjustment position defined by the force threshold device within the adjustment range.

The electrical control signal can be derived from the operating current of the adjustment drive motor with little effort. The force peak generates a corresponding current peak, which can be detected in the electrical control unit and used for calibration.

A steering spindle can preferably be mounted in the casing tube so as to be rotatable about the longitudinal axis.

At the rear end facing the driver's position, in relation to the direction of travel,

A steering handle, such as a steering wheel or the like, must be attached for entering manual steering commands. This arrangement is also referred to as an actuating unit.

The steering spindle can be rotated by turning the steering wheel. In a steer-by-wire steering system, the rotation can be detected by means of rotation sensors and converted into electrical steering commands, which can be used to control electrical steering actuators to generate a steering stop of the steerable

wheels can be controlled.

Description of the drawings

Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail:

Figure 1 is a schematic representation of a steer-by-wire steering system,

Figure 2 is a perspective view of the steering column according to Figure 1,

Figure 3 is a schematic, partially isolated view according to Figure 2,

Figure 4 is an enlarged detail view of Figure 3,

Figure 5 is a schematic side view of a force threshold device according to the invention of the steering column according to Figures 2 to 4 in a first adjustment state,

Figure 6 is a representation as in Figure 5 in a second adjustment state,

Figure 7 is a representation as in Figure 6 in a third adjustment state.

embodiments of the invention

In the various figures, identical parts are always provided with the same reference symbols and are therefore usually only named or mentioned once.

Fig. 1 shows a steering system 1, which is designed as a steer-by-wire steering system for a motor vehicle and comprises a steering column 2 according to the invention.

The steering column 2 has a steering spindle 21 which is mounted so as to be rotatable about its longitudinal axis L relative to a support unit 22. At the end of the steering spindle 21 which is at the rear in relation to the direction of travel and faces the driver's position, a

Steering wheel 23 is attached.

To adjust the steering wheel position in the longitudinal direction, as indicated in Figure 1 with a double arrow, the steering spindle 21 is mounted in a casing tube 24, which is accommodated in the support unit 22 in a telescopically adjustable manner in the longitudinal direction. This can be attached to a motor vehicle body (not shown here) via connecting means (not designated in more detail).

A manually entered into the steering spindle 21 is transmitted via rotation sensors not shown here.

Steering command is converted into electrical control signals that can control an electromotor steering actuator 3 via a control line 31. This can generate a mechanical steering angle of steerable wheels 4 depending on the control signals.

Figures 2, 3 and 4 show schematic perspective partial representations of the steering column 2.

The steering spindle 21 has a fastening section 231 at the rear end, to which the

Steering wheel 23 can be attached, which is omitted here.

In the example shown, an electromotive adjustment drive 5 is designed in a manner known per se as

Spindle drive with a threaded spindle 51, which is linearly adjustable in the direction of the longitudinal axis L relative to a spindle nut 52 that can be driven by a motor to rotate relative thereto. The

Adjustment drive 5 is attached to the support unit 22 and engages the casing tube 24, which is thereby adjustable in the longitudinal direction as indicated by the double arrow.

A force threshold device 6 according to the invention is attached to the support unit 22 and the casing tube 24, which is explained in more detail with reference to the following figures 3 to 7. In figure 3, in the same view as in figure 3, the support unit 22 is omitted in order to provide a view of the casing tube 24. Figure 4 shows an enlarged detailed view of the force threshold device 6 from figure 3.

The force threshold device 6 comprises a probe element 61 which is directed radially from the outside against the casing tube 24 transversely to the longitudinal axis L and cooperates with a cam element 62 attached to the casing tube 24 to generate a force threshold.

The probe element 61 protrudes radially inwards like a pin and is elastically supported against a retaining bolt 64 via a spring element 63, for example a helical spring as in the example, which can be displaced radially outwards. The retaining bolt 64 is fixed to the support unit 22, for example by screwing it into a corresponding radial threaded hole.

Figures 5 to 7 schematically show a side view transverse to the longitudinal direction, wherein different adjustment states in the region of the force threshold device 6 are shown.

As can be seen in Figure 5, the cam element 62 has a projection 65 that projects radially outward from the casing tube 24. This is tapered towards the outside and, viewed in the longitudinal direction towards the projection 65, has a ramp-like incline towards the

Longitudinal axis L rising contact surfaces 66.

In the spring-loaded resting state, the touch element 61 projects radially closer to the outside of the casing tube 24 than the cam element 62 projects radially outward from it with its projection, as can be seen in Figure 5. In other words, the touch element 61 projects into the movement space of the cam element 62 when the latter is adjusted in the longitudinal direction together with the casing tube 24.

If the jacket tube 24 is adjusted longitudinally by the adjustment drive 5, as in

Figure 5 with the arrow pointing to the left, it reaches the position shown in Figure 6, in which it passes the probe element 61. This comes into contact with the one contact surface 66 - on the left in the drawing - and is pushed radially outwards by its ramp-like design when the casing tube 24 is further adjusted, as is indicated in Figure 6 with the arrow pointing upwards (radially outwards).

The adjustment force exerted by the adjustment drive in the adjustment direction is redirected against the spring force of the spring element 63. As a result, the adjustment is counteracted by a reaction force F, which is shown in Figure 6.

After the cam element 62 has passed the sensing element, as shown in Figure 7, the reaction force F disappears again and the casing tube 24 can again be adjusted further without hindrance.

Due to its height and its course, the reaction force F creates a force threshold which

Adjustment must be overcome by the adjustment drive 5. The height, length and

The shape of this force threshold, which generates a force peak or force tip opposite to the adjusting force, is determined by the shape, relative height and length of the cam element 62 and the projection 65.

The force that occurs during adjustment when the cam element 62 is moved past the sensing element 61 can be detected by means of a suitable electrical sensor, for example by means of an electrical current sensor that measures the current peak caused by the force threshold and supplies it for further evaluation. This allows the adjustment drive 5 to be calibrated within the possible adjustment path, and in particular no end position as in the

state of the art technology.

The cam element 62 can, for example, be designed as a separately formed insert part, for example as a wear-resistant sintered part which is connected to the casing tube 24.

List of reference symbols 1 Steering system 2 Steering column 21 Steering spindle 22 Support unit 23 Steering wheel 231 Fastening section 24 Cover tube 3 Steering actuator 31 Control line 4 Wheel 5 Adjustment drive 51 Threaded spindle 52 Spindle nut 6 Force threshold device 61 Probe element 62 Cam element 63 Spring element 64 Retaining bolt 65 Projection 66 Contact surface

L longitudinal axis

F reaction force

Claims (12)

PATENT CLAIMS 1. Steering column (1) for a motor vehicle, comprising a casing tube (24) with a longitudinal axis (L) extending in the longitudinal direction, which is accommodated in a support unit (22) so as to be adjustable in the longitudinal direction over an adjustment path, wherein an electromotive adjustment drive (5) is provided for adjusting the casing tube (24) relative to the support unit (22), and a sensor device for detecting the position of the casing tube (24) relative to the support unit (22), characterized in that the sensor device has a force threshold device (6) which is operatively arranged between the casing tube (24) and the support unit (22) within the adjustment path, and which is designed to generate a defined force threshold that can be overcome in the longitudinal direction when adjusting the casing tube (24) relative to the support unit (22). 2. Steering column according to claim 1, characterized in that the sensor device has at least one sensor element which is designed to detect the force threshold generated by the force threshold device (6). 3. Steering column according to one of the preceding claims, characterized in that the force threshold device (6) has at least one cam element (62) protruding from the casing tube (24) transversely to the longitudinal axis (L), with which a touch element (61) protruding on the support unit (22) transversely to the longitudinal axis (L) cooperates. 4. Steering column according to claim 3, characterized in that the pushbutton element (61) is prestressed against the cam element (62). 5. Steering column according to one of claims 3 to 4, characterized in that the cam element (62) and the touch element (61) have contact surfaces (66) that can be brought into contact with one another. 6. Steering column according to claim 5, characterized in that the contact surfaces (66) are designed to rise and fall in a ramp-like manner at an angle to the longitudinal axis (L) at least in sections in the course of the longitudinal direction. 7. Steering column according to one of the preceding claims, characterized in that the cam element (62) has an insert part connected to the casing tube (24). 8. Steering column according to one of the preceding claims, characterized in that the sensor device has a current sensor of the adjustment drive (5). 9. Steering column according to one of the preceding claims, characterized in that the sensor device has a displacement sensor cooperating with the probe element (61). 10. Steering column according to one of the preceding claims, characterized in that a plurality of force threshold devices (6) are provided. 11. Method for measuring the adjustment state of a steering column (1) for a motor vehicle, comprising a casing tube (24) in which a steering spindle (21) is mounted so as to be rotatable about a longitudinal axis (L) extending in the longitudinal direction, and which is accommodated in a support unit (22) so as to be adjustable in the longitudinal direction over an adjustment path, wherein an electromotive adjustment drive (5) is provided for adjusting the casing tube (24) relative to the support unit (22), and a sensor device for detecting the position of the casing tube (24) relative to the support unit (22), characterized in that when the casing tube (24) is adjusted relative to the support unit (22), the sensor device detects a change in the adjustment force which is generated when passing a force threshold device (6) which is operatively arranged between the casing tube (24) and the support unit (22) within the adjustment path. 12. Method according to claim 11, characterized in that the change in the actuating force is converted into an electrical control signal to define a fixed reference position.