Method and apparatus for operating an electrical adjustment mechanism

Abstract

In order to achieve reliable position detection of the position of the adjustment mechanism (10) in an electrical adjustment mechanism (10) for an interior component of a motor vehicle and in particular for a vehicle seat (2), the adjustment mechanism (10) has an electric motor (18) designed as a brushless DC motor, with a rotor (16) and with a sensor system (14) for continuously detecting a current rotational position of the rotor (16), wherein the sensor system (14) has a magnet (24) mounted on the rotor (16) and at least one analogue Hall sensor (26A, 26B), the output signal (Ar, At) of which is evaluated to determine the current rotational position. The desired reliability and accuracy are achieved by using an analogue Hall sensor (26A, 26B).

Description

[0001] Page 1

[0002] Description of method and device for operating an electric adjustment mechanism

[0003] The invention relates to a method for operating an electric adjustment mechanism designed to adjust a component of a motor vehicle, and in particular a vehicle seat. The invention further relates to such an electric adjustment mechanism. The adjustment mechanism comprises an electric motor, in particular a brushless DC motor, with a rotor and with sensors for continuously detecting the instantaneous rotational position of the rotor.

[0004] In the case of an electric motor adjustment mechanism in the automotive sector, especially when adjusting a vehicle seat, it is often crucial to know the current position of the component to be adjusted, for example, the longitudinal position of the vehicle seat. This is frequently achieved by monitoring the rotations of the electric motor's rotor and its direction of rotation, and deriving the current position from this data.

[0005] Encoders are used, for example, to detect the number of revolutions and the direction of rotation. Digital Hall sensors can also be used to determine the direction and number of revolutions. However, using encoders is comparatively complex. Digital Hall sensors are prone to errors, for example, regarding the accurate detection of the rotor's number of revolutions, which can lead to miscounts and necessitate repeated calibration.

[0006] 2024 314 WO Page 2

[0007] Based on this, the invention aims to enable reliable detection of the current position of a component of a motor vehicle, in particular a vehicle seat, with minimal effort.

[0008] The problem is solved according to the invention by a method for operating an electric adjustment mechanism and by such an adjustment mechanism. The adjustment mechanism serves to adjust an interior component of a motor vehicle (automobile), in particular a vehicle seat. The adjustment mechanism includes an electric motor, which is preferably a brushless DC motor. This motor has a rotor. Furthermore, a (rotor position) sensor is provided for continuously detecting the instantaneous rotational position of the rotor. The sensor includes a magnet mounted on the rotor, specifically a multipole permanent magnet, and at least one analog magnetic field sensor, the output signal of which is continuously evaluated as at least one output signal for determining the instantaneous rotational position.

[0009] For evaluation, the sensor system has an evaluation unit which is connected to at least one analog magnetic field sensor and to which at least one output signal is transmitted.

[0010] Crucial to this method is the use of an analog magnetic field sensor to detect the rotor's rotation and thus continuously measure its instantaneous position. With such analog magnetic field sensors, the output signal varies continuously according to the instantaneously measured magnetic field strength. The output signal, specifically the output voltage of the analog Hall sensor, changes continuously in line with the magnetic field strength it detects, which changes continuously due to the rotation. The output signal of the analog magnetic field sensor is therefore typically a sine or cosine wave. The periodic rise and fall of the magnetic field, and thus also of the output signal, correlates directly with the rotor's rotation, allowing for precise determination of its position.

[0011] 2024 314 WO Page 3 of a given instantaneous signal value of the output voltage can be directly correlated to an instantaneous rotation angle. In alternative configurations, where the magnetic field sensor is equipped with an internal evaluation unit, for example, the analog measurement signal is already processed and an angle signal, which indicates the rotation angle, is directly output as the output signal.

[0012] The at least one analog magnetic field sensor is in particular an analog Hall sensor.

[0013] In principle, other analog magnetic field sensors can also be used, such as an AMR sensor (AMR: Anisotropic Magnetoresistive Effect), a GMR sensor (GMR: Giant Magnetoresistance), or a TMR sensor (TMR: Tunnel Magnetoresistive Effect).

[0014] The invention is described below, without limiting the generality, using the example of an analog Hall sensor as an analog magnetic field sensor.

[0015] Unlike an analog magnetic field sensor, a digital magnetic field sensor, specifically a digital Hall sensor, outputs only a digital pulse sequence as a signal. A pulse is emitted only when the magnetic flux flowing through the Hall sensor exceeds or falls below a certain value. In other words, a pulse is only emitted when the magnetic poles of the magnet reverse.

[0016] Such digital Hall sensors have several disadvantages. By their very nature, they have a limited resolution unless a large number of differently positioned Hall sensors are used, which, however, leads to high costs. As mentioned at the beginning, miscounts can occur due to their inherent design. For example, miscounting is possible due to hysteresis during power-up. This can lead to consequential errors, such as the actual position of the component not being determined correctly, and consequently, a memory position not being reached correctly. Inaccurate detection of the

[0017] 2024 314 WO Page 4 The current position can also lead to errors in the motor's commutation, since the Hall signal is usually used to control the motor's commutation. Due to the limited angular resolution, for example, suboptimal commutation occurs, which can lead to efficiency losses and increased thermal stress.

[0018] These problems are avoided by using an analog magnetic field sensor, particularly an analog Hall sensor. The exact current position of the rotor, and therefore of the component, is thus recorded. Miscounting is therefore prevented. Consequently, no additional calibration measures, such as a reference run, are required during operation and are preferably not even planned. Such calibration measures typically result in a loss of user convenience.

[0019] Another significant advantage lies in the improved commutation control, as the high angular accuracy allows for better tuning and avoids commutation errors. Commutation is therefore generally controlled based on the output signal provided by at least one analog magnetic field sensor, particularly an analog Hall sensor. This has a positive effect on the overall acoustics of the motor and, in particular, on its efficiency, resulting in low energy consumption and, especially, low thermal losses.

[0020] The use of an analog magnetic field sensor, particularly an analog Hall sensor, offers the advantage – especially compared to a digital Hall sensor – that the correct angular information about the instantaneous rotor position is obtained immediately upon power-up. Furthermore, the analog magnetic field sensor, especially the analog Hall sensor, exhibits a high resolution, typically between 1° and 3°, meaning the angular accuracy of the output signal evaluation lies within this range.

[0021] 2024 314 WO Page 5

[0022] The evaluation unit is designed for suitable evaluation of the at least one output signal. In particular, an evaluation signal derived from the at least one detected output signal is determined. An evaluation signal is understood to be any signal obtained after processing the output signal provided by the at least one magnetic field sensor, especially the analog Hall sensor. This includes, for example, one or more of the following evaluation signals:

[0023] According to a first variant, the current rotation angle and thus the current rotational position of the rotor is output as an angle signal from the output signal, for example with an absolute angle specification or with a relative angle specification (e.g. with respect to a defined starting position).

[0024] Alternatively or additionally, a derivative is determined, in particular of the recorded output signal or the angle signal derived from it, which allows, for example, continuous detection of changes in rotational speed.

[0025] Finally, according to another option, a speed signal corresponding to the current speed is derived from the output signal and / or a count signal that counts the number of rotations.

[0026] The advantages and preferred configurations described below in connection with the method also apply analogously to the device and vice versa. The evaluation unit is generally designed to carry out the process steps described below.

[0027] In a preferred embodiment, two analog magnetic field sensors, in particular analog Hall sensors, are mounted in different orientations and / or different positions relative to the magnet in order to detect differently oriented field components of the magnetic field generated by the magnet, in particular to detect a radial field component and a tangential field component. Each analog magnetic field sensor is

[0028] 2024 314 WO page 6 therefore a corresponding output signal is provided and the two output signals are evaluated together.

[0029] Different orientation means that the two sensors are arranged in a twisted position relative to each other.

[0030] Different positioning refers to a spatial offset, especially with the same orientation. For example, the two sensors are arranged offset by a predetermined angle, particularly 90°, along an imaginary arc (circle, ellipse).

[0031] The two analog magnetic field sensors, in particular analog Hall sensors, are oriented at right angles to each other, i.e., rotated 90° relative to each other. They are oriented radially and tangentially with respect to the magnet and rotor, respectively.

[0032] Alternatively, as mentioned above, they are arranged with the same orientation but offset by 90° from each other.

[0033] The two output signals obtained in this way are periodic signals, specifically a sine wave and a cosine wave, respectively, which have a predetermined phase shift of, in particular, 90°. This phase shift enables a reliable and unambiguous determination of the angle within a 360° rotation, as well as, in particular, a clear and reliable identification of the direction of rotation. Specifically, the use of the two analog magnetic field sensors allows for highly accurate and reliable detection of the rotor's instantaneous rotational position, and from this, the number of rotations and the direction of rotation can be derived.

[0034] In a preferred embodiment, the two output signals or the evaluation signals derived therefrom are jointly compared; in particular, the arctangent is calculated from the cosine and sine functions provided by the output signals. Specifically, in the case of a

[0035] 2024 314 WO Page 7 With uniform rotation, a sawtooth-like step function results, which rises continuously from a lower limit to an upper limit, and then falls back to the lower limit. The arctangent is therefore particularly suitable for counting the number of revolutions and is especially used for this purpose.

[0036] In a preferred embodiment, in addition to at least one analog magnetic field sensor, a digital magnetic field sensor, in particular a digital Hall sensor, is used, the digital output signal of which is additionally evaluated. In particular, only a single analog magnetic field sensor, in particular a single analog Hall sensor, is combined with a digital Hall sensor. A digital Hall sensor is typically less expensive than an analog Hall sensor. This combination combines the advantages of both sensor types.

[0037] In a preferred embodiment, the output signal of at least one analog magnetic field sensor, in particular at least one analog Hall sensor, is used to check whether a varying rotational speed occurs within a single revolution (i.e., within a 360° rotation) of the rotor. In other words, it is checked whether a fluctuation in rotational speed occurs within a single revolution. If a fluctuation occurs, the rotational speed both decreases and increases again within a revolution. For this check, a derivative of the output signal or the derived evaluation signal, specifically the angular signal, is performed. Such an evaluation within a single revolution allows, for example, conclusions to be drawn about the presence of imbalances and / or torque fluctuations, thereby enabling the detection of potential sources of error.Preferably, a warning signal is issued when impermissible variations in rotational speed are detected within a rotation.

[0038] To ensure the most reliable operation possible, the acquired output signals and / or the derived evaluation signals are calibrated in a suitable configuration. This calibration is preferably carried out

[0039] 2024 314 WO Page 8 before the initial use of the sensor, for example, following the initial installation of the interior component in the vehicle. Calibration is also performed after a certain operating period if necessary. Preferably, such calibration is omitted during normal use of the interior component. Calibration is optionally and preferably in combination understood to mean a) calibration of the sensor on the magnet (sensor calibration), so that the output signal correlates with the magnetic field, for example, by measuring the sine and cosine amplitudes with possible subsequent normalization, and / or b) an absolute position of the adjustment system as a whole (absolute position calibration), specifically in a block position (i.e., when the adjustment system moves against a block / stop).

[0040] Sensor calibration is preferably performed after pre-assembly of the drive unit consisting of (motor and magnet) and (sensor and electronics).

[0041] Absolute position calibration is preferably performed after pre-assembly of the adjustment mechanism, i.e., the drive unit with any gearbox and an adjustment mechanism, such as a seat rail.

[0042] Ideally, subsequent calibration – following an initial calibration – should only be performed by authorized personnel, for example, through appropriate access restrictions. Alternatively, such calibration can also be initiated by the user, guided through the calibration process by instructions. These instructions might be displayed, for example, on a monitor in the vehicle.

[0043] Calibration generally refers to the assignment of a signal value to a defined value of the rotor's rotation angle and / or a current actual position of the adjustment mechanism. In this context, calibration also includes normalization, where, for example, the

[0044] 2024 314 WO Page 9

[0045] Evaluation of two output signals from two analog Hall sensors - the two output signals are normalized to a common scale.

[0046] The following calibration measures are performed, for example, whereby the output signals and / or the derived evaluation signals are calibrated. For the calibration steps, an external sensor with an independent sensor to determine the current rotational position of the rotor is preferably used as a reference point:

[0047] - According to a first variant, the rotor is rotated for calibration, specifically by several revolutions, and the resulting output signals are compared with the actual rotational position. For multiple revolutions, the recorded values ​​are preferably averaged. The rotor is preferably rotated in both directions. The actual angular positions of the rotor are thus compared with the curve of at least one recorded output signal or a derived evaluation signal.

[0048] - Alternatively or additionally, maximum values, preferably both positive (maxima) and negative (minima) in the at least one output signal or in an evaluation signal derived therefrom, are identified and, in particular, normalization is carried out on the basis of these maximum values ​​when processing multiple output signals, especially the two output signals of the two analog Hall sensors.

[0049] - Furthermore, any existing phase error between the two output signals of the two analog Hall sensors is preferably determined and later compensated for during operation in a suitable manner for subsequent evaluation.

[0050] - In preferred further training, a temperature dependence of the Hall sensors is recorded and a corresponding adjustment is made during operation.

[0051] 2024 314 WO Page 10

[0052] Temperature compensation is performed. This is done, for example, using a temperature-dependent correction factor.

[0053] In a further preferred embodiment, the complete sequence of the at least one output signal or a derived evaluation signal is taught during a complete rotor revolution or, in particular, during a complete adjustment movement of the interior component, specifically between two endpoints of the adjustment movement of the interior component. This allows a characteristic process sequence and a characteristic curve for the entire adjustment movement to be determined, from which, for example, position information can already be derived.

[0054] - In particular, magnetization errors can also be identified, which can lead to a lack of correlation between the different signals.

[0055] - In a suitable configuration, the system continuously learns and updates during operation as deviations are identified. The output signals and the determined trend are continuously recorded and updated. This allows the learned trend, against which, for example, a currently recorded trend is compared, to be continuously updated, particularly in the manner of a self-learning system. In this way, continuous learning is achieved, taking into account, for example, the effects of aging.

[0056] Alternatively or additionally to such relearning, a complete recalibration is performed. This is done, for example, in a workshop and / or via a corresponding message and prompt in the on-board computer, e.g., via a display on a monitor in the vehicle, as mentioned previously. Instructions on how to perform the recalibration are also provided. This can then be done by the user themselves.

[0057] 2024 314 WO page 11. This calibration preferably involves a so-called calibration run, in which, for example, the interior component is moved between its end positions.

[0058] In a preferred embodiment, the output signal is sampled at a predetermined sampling rate, specifically such that at a given nominal motor speed, typically several thousand revolutions per minute (rpm) and, for example, 6000 rpm, the sampling rate corresponds to a rotor rotation angle of 3°–10° and, for example, 6°. This high sampling rate ensures that signal values ​​are obtained at short angular intervals, resulting in high angular resolution for position determination.

[0059] The sampling rate is conveniently adapted to the commutation rate of the electric motor. Specifically, the sampling rate corresponds to a commutation rate. The commutation rate is understood to be the number of commutations per unit of time (at a given rated speed). For example, the time between two successive commutations in typical variable-speed motors is between 50 ps and 150 ps. The output signal is therefore sampled at the same time intervals as the motor's commutation.

[0060] In a preferred embodiment, the magnet is designed as a dipole magnet or, alternatively, as a magnet with more than two poles. In a preferred embodiment, the number of pole pairs of the magnet corresponds to the number of pole pairs of the electric motor. Due to the identical number of poles, a conversion of the rotor position for commutation is unnecessary and preferably not performed.

[0061] Preferably, the sensor is put into a sleep mode when the adjustment mechanism is not in use. From this sleep mode, the sensor is activated to monitor for unintended position changes, with activation occurring after a predetermined time interval. This time interval is selected, in particular, such that unintended position changes are detected for more than...

[0062] 2024 314 WO Page 12 one revolution, not to be expected. This ensures that a miscount is impossible. The time interval is, for example, a maximum of 30 seconds.

[0063] If, after such activation, a change in the rotational position is detected compared to the rotational position recorded before the sensor was switched off, the time interval is preferably shortened, at least temporarily, to ensure that unintentional adjustments are reliably detected.

[0064] This is based on the consideration that, for energy-saving reasons, the sensors are frequently switched off, and the corresponding electronic components of the sensors are not supplied with voltage / current. This occurs, for example, if the adjustment mechanism has not been operated for a certain period of time. At the same time, however, during normal ferry operation, for example due to vibrations, an unintended adjustment (i.e., not controlled by the electric motor) can occur, resulting in rotation of the rotor. This can subsequently lead to an incorrect position signal. Regularly checking and activating the sensors ensures that no such unintended position changes lead to a counting error.

[0065] Alternatively or additionally to such time-controlled activation from a sleep mode, in a preferred embodiment, activation occurs when the output signal of the digital Hall sensor is detected by the evaluation unit. A particular advantage of the digital signal is that it can be very easily identified and recognized by the evaluation unit due to the level change (from zero to one and vice versa). Thus, when such a digital output signal, i.e., a level change, is detected, the sensor, or at least one analog Hall sensor, is activated. In this variant, for example, the digital Hall sensor is continuously active.

[0066] Alternatively or additionally, the sensor is activated when the output signal of the analog magnetic field sensor exceeds a threshold value. For this purpose,

[0067] 2024 314 WO Page 13, in particular, provides that the output signal may additionally be applied to a special, wake-up-capable, especially digital, input of an evaluation unit (e.g., a microcontroller). If the analog output signal of the analog magnetic field sensor exceeds a voltage threshold, the digital input switches from high to low or vice versa, which is used as the wake-up signal. In such a configuration, activation from a sleep mode is preferably implemented without the use of a digital magnetic field sensor.

[0068] In a preferred embodiment, the current position of the interior component is generally determined based on at least one output signal, and a corresponding instantaneous position signal is output. This signal is then transmitted, for example, to another, particularly higher-level, control unit and used there for further actions. The position signal is generally an evaluation signal, i.e., a signal derived from the at least one output signal.

[0069] In particular, the instantaneous position signal is used to trigger an airbag. For this purpose, the position signal is transmitted to a control unit to activate the airbag. The airbag is triggered primarily based on the instantaneous position of the interior component. This enables demand-based control of the airbag. Especially with a safety-critical function like airbag deployment, the reliability of the position signal is crucial. This reliability is ensured here by the high accuracy resulting from the use of at least one analog Hall sensor.

[0070] In a further development, the sensor system is additionally designed to determine a weight signal corresponding to the instantaneous weight load on the vehicle seat, and this weight signal is used in conjunction with the position signal to control the airbag. The particular advantage here is that the sensor system can detect both the position signal and the weight signal.

[0071] 2024 314 WO page 14 also transmits the weight signal. An additional signal source, such as an additional weight sensor that communicates with the airbag control unit, is therefore not required and preferably not intended.

[0072] In a suitable configuration, the interior component is a vehicle seat whose longitudinal and / or tilt position is determined and output as a position signal. For airbag control, the longitudinal position of the vehicle seat and / or the tilt position of a seat backrest is therefore determined and transmitted as a position signal.

[0073] Exemplary embodiments of the invention are explained in more detail below with reference to the figures. These show schematic representations of:

[0074] FIG 1 a simplified representation of a vehicle seat,

[0075] FIG 2 shows a simplified representation of a drive unit for adjusting the vehicle seat,

[0076] FIG 3 shows a schematic representation of a rotating dipole magnet with magnetic field lines and Hall sensors.

[0077] FIG 4 shows the course of a radial field component and a tangential field component of the magnetic field,

[0078] FIG 5 shows a schematic representation of the rotating dipole magnet with magnetic field lines and Hall sensors according to FIG 3 after a 90° rotation.

[0079] FIG 6 shows the output voltage of the two Hall sensors, and FIG 7 shows a normalized output signal of the two Hall sensors.

[0080] A vehicle seat 2, shown in FIG. 1, is installed in a motor vehicle (automobile) which is not shown in detail. The vehicle seat 2 has a seat section 4 to which a backrest 6, adjustable in its inclination, is attached. A seat base is associated with the seat section 4 and is mounted on a longitudinal rail 8, which, in the installed state, is attached to the floor of the motor vehicle. A [feature] is included in the seat base (only schematically shown).

[0081] 2024 314 WO page 15 shows an integrated adjustment mechanism 10, which in the exemplary embodiment is designed for longitudinal adjustment of the vehicle seat 2.

[0082] The adjustment mechanism 10 includes a drive unit 12, as explained in more detail, for example, in FIG. 2.

[0083] In the exemplary embodiment, the drive unit 12 is designed as an integrated drive unit 12, which also has integrated electronics within a common housing with a sensor system 14 for detecting the instantaneous rotational position of a rotor 16 of an electric motor 18 specially designed as a brushless DC motor (see FIG 2).

[0084] In addition to detecting the current rotational position, the sensor 14 is preferably also designed to detect a weight located on the seat part 4. The sensor 14 is configured to output a position signal P and a weight signal G. The position signal P is determined from the currently detected rotational position.

[0085] The current position of the adjustment mechanism 8 is determined using the position signal P. For this purpose, for example, a count signal for the number of revolutions of the rotor 16 is derived from the data of the current rotational position, and the current position of the adjustment mechanism 8 is determined based on this count signal.

[0086] In the embodiment shown in FIG. 1, an airbag 20 and an associated airbag control unit 22 are also shown. In this exemplary embodiment, the airbag is integrated into the armrest 6 and is designed, for example, as a side airbag. Alternatively, it is located in side body panels or in the steering wheel, as is known in the art.

[0087] The airbag control unit 22 is preferably designed such that, in the event of a triggering event, for example in an accident, the airbag 20 is triggered depending on the current position of the adjustment mechanism 10. This means that

[0088] 2024 314 WO page 16 that the triggering occurs differently depending on the position of the adjustment mechanism 10 and thus the vehicle seat 2.

[0089] The triggering of the airbag 20 depends primarily on the longitudinal position of the vehicle seat 2. Alternatively or additionally, the triggering and activation of the airbag 20 also depends on the tilt position of the backrest 6. The vehicle seat 2 generally has a suitable backrest adjustment mechanism (not shown) with an electric motor for adjustment. The tilt position of the backrest is again determined based on the instantaneous rotational position of the rotor of this electric motor, as is also described for longitudinal adjustment. The instantaneous tilt position is preferably transmitted as a further position signal to the airbag control unit 22.

[0090] The detection of the current rotational position of the rotor 16 is explained in more detail below in connection with Figures 2-7:

[0091] The drive unit 12 shown in FIG. 2 shows that a ring-shaped magnet 24, preferably a dipole magnet, is arranged on the rotor 16 as a permanent magnet. A Hall sensor unit 26 is associated with the magnet 24, which has two integrated Hall sensors 26A, 26B within a single unit, as shown schematically in FIG. 3 and FIG. 5.

[0092] The magnet 24 and the Hall sensor unit 26 are part of the sensor system 14. This also includes an evaluation unit 28, which is designed to evaluate output signals that are output by the two Hall sensors 26A, 26B.

[0093] The Hall sensor unit 26 and the evaluation unit 28, along with other components, are arranged on a circuit board 30 of the integrated drive unit 12. In FIG. 2, a section of the housing of the drive unit 12 is not shown, so that the circuit board 30, the rotor 16, and the magnet 24 are visible.

[0094] 2024 314 WO Page 17

[0095] In the exemplary embodiment, a gear unit 32 is also connected to the electric motor 18. The adjustment mechanism 10 is driven via a drive shaft which is not shown in detail here.

[0096] The two Hall sensors 26A and 26B are analog Hall sensors which, in the exemplary embodiment, are oriented differently within the Hall sensor unit 26. Alternatively, they can also be positioned differently. They are designed to detect differently oriented magnetic fields. One Hall sensor 26A is designed to detect a radial field component R, and the other Hall sensor 26B is designed to detect a tangential field component T. Accordingly, one sensor 26A is also referred to as a radial Hall sensor and the other sensor 26B as a tangential Hall sensor.

[0097] FIG 3 shows a field line path of the magnet 24 designed as a dipole magnet in an initial rotational position, together with the schematically illustrated Hall sensor unit 26 with the two Hall sensors 26A, 26B.

[0098] The two field components R and T of the magnetic field are additionally indicated by two arrows, which simultaneously define a radial and a tangential direction. Furthermore, FIG. 3 indicates a direction of rotation D of the magnet 24 and thus also of the rotor 16 (not shown here).

[0099] FIG 4 shows the course of the two magnetic field components R, T relative to a rotation angle a during a rotation of the rotor 16.

[0100] The rotation angle 0 corresponds to the initial rotation position shown in FIG. 3. In this position – at the location of the Hall sensor unit 26 – the radial field component R has its maximum and the tangential field component T has its zero crossing. During rotation in the direction of rotation D, the radial field component R then follows a cosine curve and the tangential field component T follows a sine curve.

[0101] 2024 314 WO Page 18

[0102] The two curves are therefore 90° out of phase with each other.

[0103] The two Hall sensors 26A and 26B provide output signals, namely a radial output signal Ar and a tangential output signal At, which, corresponding to the field profiles, are also offset from each other by 90° and are also cosinusoidal and sinusoidal, respectively. The output signals Ar and At are shown in FIG. 6.

[0104] FIG 5 shows the field line image according to FIG 3 after a 90° rotation of the magnet 24.

[0105] In FIG. 6, a dotted vertical line is additionally shown, which illustrates the situation – starting from the initial rotation position in FIG. 3 – after the 90° rotation. It can be seen that the tangential output signal At, representing the tangential field component T, has reached its maximum value.

[0106] After another 90° rotation, i.e., at 180°, the radial component R and with it the radial output signal Ar reach their minimum. In contrast, the tangential field component T and with it the tangential output signal At reach their minimum at 270°.

[0107] Figure 6 further shows that the two signals have different maxima and minima. The evaluation preferably involves normalization to identical maximum and minimum amplitudes.

[0108] This is illustrated in FIG. 7, which shows normalized output signals Nr, Nt. These normalized output signals Nr, Nt are therefore processed output signals and thus also constitute evaluation signals.

[0109] The output signals Ar, At from the two Hall sensors 26A, 26B are read out at a predetermined sampling rate of, for example, 6°, resulting in a (finely) stepped waveform for the processed signal, here the normalized output signal Nr, Nt, as can be seen in FIG. 7. At such a sampling rate, high positional accuracy is achieved.

[0110] 2024 314 WO Page 19

[0111] Reference symbol list

[0112] 2 vehicle seats

[0113] 4 seat section

[0114] 6 Backrest

[0115] 8 Longitudinal rail

[0116] 10 Adjustment mechanism

[0117] 12 Drive unit

[0118] 14 Sensors

[0119] 16 Rotor

[0120] 18 Electric motor

[0121] 20 airbags

[0122] 22 Airbag control unit

[0123] 24 Magnet

[0124] 26 Hall sensor unit

[0125] 26A radial Hall sensor

[0126] 26B tangential Hall sensor

[0127] 28 evaluation units

[0128] 30 circuit boards

[0129] 32 Gear unit

[0130] P Position signal

[0131] G weight signal

[0132] Direction of rotation

[0133] R radial field component

[0134] T tangential field component

[0135] Ar radial output signal

[0136] At tangential output signal

[0137] No. normalized radial output signal

[0138] Nt normalized tangential output signal

[0139] 2024 314 WO

Claims

Page 20 Claims 1. Method for operating an electric adjustment mechanism (10) designed for adjusting an interior component of a motor vehicle and in particular a vehicle seat (2), wherein the adjustment mechanism (10) comprises an electric motor (18) designed as a brushless DC motor with a rotor (16) and with a sensor system (14) for continuously detecting an instantaneous rotational position of the rotor (16), wherein the sensor system (14) comprises a magnet (24) mounted on the rotor (16) and at least one analog magnetic field sensor (26A, 26B), the output signal (Ar, At) of which is evaluated as at least one output signal (Ar, At) for determining the instantaneous rotational position.

2. Method according to the preceding claim, wherein two analog magnetic field sensors (26A, 26B) are mounted in different orientations or different positions relative to the magnet (24) in order to detect differently oriented field components of the magnetic field generated by the magnet (24), in particular to detect a radial field component (R) and a tangential field component (T), wherein the output signals (Ar, At) of the two Hall sensors (26A, 26B) are evaluated together to determine the instantaneous rotation position.

3. Method according to one of the preceding claims, wherein the at least one analog magnetic field sensor (26A, 26B) is an analog Hall sensor.

4. Method according to one of the preceding claims, wherein, in addition to the at least one analog magnetic field sensor (26A, 26B), a digital magnetic field sensor, in particular a Hall sensor, is used which outputs a digital output signal which is additionally evaluated.

5. Method according to one of the preceding claims, wherein the output signal (Ar, At) of the at least one analog magnetic field sensor is used to determine the 2024 314 WO Page 21 (26A, 26B) checks whether there is a varying rotational speed within one revolution of the rotor (16).

6. Method according to one of the preceding claims, wherein a calibration is carried out prior to the use of the sensor (14) or also during operation, in which one or more of the following steps are performed: - Rotating the rotor (16) by, in particular, several revolutions and preferably in both directions of rotation and comparing it with the course of the at least one detected output signal (Ar, At) or an evaluation signal derived therefrom, - Identifying maximum values ​​in at least one output signal (Ar, At) or a derived evaluation signal and, if necessary, normalization when processing multiple output signals, - Detection of temperature dependency and implementation of temperature compensation during operation, - Learning a complete sequence of at least one output signal (Ar, At) or a derived evaluation signal during an adjustment movement of the interior component, - Comparison of the position of the interior component with the at least one detected output signal (Ar, At) or with an evaluation signal derived from it.

7. Method according to one of the preceding claims, wherein the output signal (Ar, At) is sampled at a predetermined sampling rate, in particular such that at a nominal speed of the motor, sampling is performed at a sampling rate corresponding to a rotation angle of the rotor (16) of 3° to 10°.

8. Method according to the preceding claim, wherein the sampling rate is adapted to a commutation of the electric motor (18).

9. Method according to one of the preceding claims, wherein the magnet (24) is a dipole magnet or alternatively a more than two-pole magnet (24) 2024 314 WO page 22 is formed, and the number of pole pairs of the magnet (24) corresponds to a number of pole pairs of the electric motor (18).

10. Method according to one of the preceding claims, wherein the sensor (14) is put into a sleep mode when the adjustment mechanism (10) is not in use, wherein, starting from the sleep mode, the sensor (14) is activated after a predetermined time interval in order to monitor the adjustment mechanism (10) for unintended position changes during the sleep mode, wherein, in the event of a detected position change, the predetermined time interval is preferably reduced.

11. Method according to one of the preceding claims and according to claim 4, wherein the sensor (14) is put into a sleep mode when the adjustment mechanism (10) is not in use, wherein, starting from the sleep mode, the sensor (14) is activated when a digital output signal from the digital Hall sensor or an exceedance of a threshold of the output signal (Ar, At) of the analog magnetic field sensor 26A, 26B is detected in order to monitor the adjustment mechanism (10) for unintended position changes during the sleep mode.

12. Method according to one of the preceding claims, wherein a current position of the interior component is determined on the basis of the at least one output signal (Ar, At) and a corresponding instantaneous position signal (P) is output.

13. Method according to the preceding claim, wherein the instantaneous position signal (P) is used for controlling an airbag (20).

14. Method according to the preceding claim, wherein the sensor (14) is simultaneously configured to determine a weight signal (G) corresponding to an instantaneous weight load on the vehicle seat (2) and the weight signal (G) is output with the position signal (P) and used to control the airbag (20). 2024 314 WO Page 23 15. Method according to one of claims 11 to 13, wherein the component is a vehicle seat (2) whose longitudinal position and / or tilt position is determined and output as a position signal (P).

16. Electric adjustment mechanism (10) for adjusting an interior component of a motor vehicle, in particular a vehicle seat (2), comprising an electric motor (18) designed as a brushless DC motor with a rotor (16) and further comprising a sensor system (14) and an evaluation unit (28) for continuously detecting an instantaneous rotational position of the rotor (16), wherein the sensor system (14) comprises a magnet (24) mounted on the rotor (16) and at least one analog magnetic field sensor (26A, 26B) which is connected to the evaluation unit (28), wherein the latter is designed to evaluate an output signal (Ar, At) of the at least one analog magnetic field sensor (26A, 26B) for determining the instantaneous rotational position. 2024 314 WO

Images