Device for detecting the direction of rotation of an electric motor and assembly method for assembling a drive system

Abstract

Device comprising for detecting the direction of rotation of an electric motor: - a first Hall sensor with a first trigger threshold and a second Hall sensor with a second trigger threshold for detecting a magnetic flux density generated during the operation of the electric motor, wherein a signal output of the first Hall sensor and a signal output of the second Hall sensor are connected in parallel and the two Hall sensors are arranged to be positioned at an angle to each other on the electric motor in a specified operating state of the device, and to have unequal trigger thresholds, and - a control unit coupled to the parallel signal output of the two Hall sensors for evaluating a common output signal of the two Hall sensors received via the common signal output, wherein the control unit is configured to detect the direction of rotation based on the common output signal. Furthermore, the proposed solution also concerns an assembly method for a drive system.

Description

[0001] The proposed solution relates to a device for detecting a direction of rotation and to an assembly method for assembling a drive system with such a device. Such devices and assembly methods are known in particular from drive systems in the automotive sector. In particular, they are known for monitoring the power-operated adjustment of vehicle elements, such as vehicle seats, doors, or windows. The direction of rotation can be detected, for example, based on motor drive values ​​from motor electronics or on the movement of an element driven by the motor. US Patent Specification US 5,486,759 A, for example, discloses a device for detecting the movement of a movable part, in which the position signals emitted by two position sensors are added together to form a signal and fed to an evaluation arrangement. Further devices for position orMotion detection systems are known from the publications JP 2004 - 219 162 A, US 2021 / 0 247 213 A1, DE 10 2014 111 053 A1, DE 10 2020 117 752 A1, US 2014 / 0 111 191 A1, and US 2014 / 0 046 625 A1. Such devices and methods can sometimes only inadequately detect motor malfunctions and / or are complex to install and maintain.

[0002] The proposed solution is therefore based on the task of improving devices and methods for detecting a direction of rotation of an electric motor.

[0003] This object is achieved with a device according to claim 1 and an assembly method according to claim 10. Accordingly, the proposed device for detecting a direction of rotation of an electric motor comprises at least: - a first Hall sensor with a first trigger threshold and a second Hall sensor with a second trigger threshold for detecting a magnetic flux density generated during operation of the electric motor, wherein a first signal output of the first Hall sensor and a second signal output of the second Hall sensor are connected in parallel and the two Hall sensors are configured to be arranged on the electric motor during normal operation of the device, to enclose an angle other than zero and to have unequal trigger thresholds, and - a control unit coupled to the parallel-connected signal outputs of the two Hall sensors for evaluating a common output signal of the two Hall sensors received from the parallel-connected signal outputs, wherein the control unit is configured to detect the direction of rotation based on the output signal, wherein the control unit is configured to determine, in the temporal profile of the output signal, a ratio between a first time period in which both Hall sensors are in the same state to a second time period comprising the first period and a further period in which both Hall sensors are in different states.

[0004] The proposed solution makes it possible to determine the direction of rotation by evaluating exactly one signal, namely the shared output signal of the two Hall sensors connected in parallel. The shared output signal contains information from the two Hall sensors spatially separated by the included angle. The Hall sensors enclose the angle with their respective connecting lines to a rotation axis of the electric motor. As a result, during normal operation, the two Hall sensors are passed one after the other from a fictitious point on the rotor of the electric motor. Since both Hall sensors have different trigger thresholds, a reversal of the direction of rotation also changes the temporal relationship between the output signals generated by the Hall sensors. Accordingly, the shared output signal of the Hall sensors, which can be evaluated by the control unit due to the parallel connection, also differs.Accordingly, the proposed device makes it possible to determine the direction of rotation directly on the motor through direct measurement. In particular, the direction of rotation is determined without the aid of predefined motor drive values. This can reduce the probability of incorrect determination of the direction of rotation.

[0005] In conjunction with motor revolution detection, this can improve the determination of the adjustment travel caused by the electric motor. This can reduce the frequency of necessary calibrations of the electronics used to determine the adjustment travel, thus reducing maintenance effort. The proposed solution can also reduce the contacting effort and make the device more robust against malfunctions.

[0006] The two Hall sensors can each have multiple contacts, in particular three contacts. Each of the Hall sensors can be connected to a voltage source and a reference potential (ground) via two of the contacts. A parallel connection of the two Hall sensors can therefore mean that a voltage source is connected to the first contact of each of the two Hall sensors, the second contacts of both Hall sensors are at the same potential level as ground, and the third contacts of both Hall sensors are connected to exactly one signal input of the control unit. It is also conceivable and possible for the second contacts of both Hall sensors to be electrically connected to each other. The output signal can be tapped as a voltage modulation at the parallel-connected ground contacts of both Hall sensors. For example, a measuring resistor can be placed between the ground potential and the parallel-connected ground contacts of the two Hall sensors, across which a falling voltage is measured and evaluated. Such an arrangement can be referred to as low-side detection.

[0007] It is also conceivable and possible to place the measuring resistor between a voltage source and the two parallel-connected power supply contacts. Such an arrangement can be referred to as high-side detection.

[0008] Furthermore, each of the Hall sensors is configured to generate an output signal depending on the magnetic flux density and transmit it via the respective signal output. Since the output signal depends on the magnetic flux density, the two Hall sensors exhibit different trigger thresholds.

[0009] This means that the Hall sensors, which are intended to be mounted on the electric motor, exhibit different temporal behavior of their respective output signals in response to the magnetic field generated during operation of the electric motor. In relation to a time-varying magnetic field, the two Hall sensors are therefore configured to switch at different times due to their different trigger thresholds.

[0010] For example, the different trigger thresholds can be realized by different threshold values ​​or sensitivities of the two Hall sensors. For example, the first Hall sensor can generate a specific output signal at a magnetic flux density at which the second Hall sensor does not yet generate a corresponding output signal.

[0011] Alternatively or additionally, during normal operation of the device, the two Hall sensors can be arranged on an electric motor in such a way that a maximum magnetic flux density generated during operation of the electric motor at the location of the first Hall sensor differs from a maximum magnetic flux density at the location of the second Hall sensor. This also makes it possible to implement different trigger thresholds for the two Hall sensors.

[0012] In a further embodiment of the proposed solution, the first Hall sensor and the second Hall sensor can be positioned at different distances from the electric motor when the Hall sensors are arranged on an electric motor as intended. This also makes it possible to implement different trigger thresholds for the two Hall sensors.

[0013] For example, the distance of each of the Hall sensors can be defined as the minimum distance of all points of a surface of the respective Hall sensor to a rotation axis of the motor.

[0014] It is also conceivable and possible to realize different trigger thresholds by means of a targeted magnetic shielding of one of the Hall sensors or two different shieldings of the two Hall sensors.

[0015] In another conceivable and possible embodiment of the proposed solution, different trigger thresholds can be realized by varying the orientation of the two Hall sensors relative to the electric motor. This allows different trigger thresholds to be realized using standard components. This can reduce component costs.

[0016] In principle, a Hall sensor can have a detection direction, whereby a detection sensitivity of a Hall sensor for magnetic fields is maximum along the detection direction.

[0017] In an exemplary embodiment of the differently aligned Hall sensors, these can have different angles between the detection directions of the two Hall sensors and a connecting line between the Hall sensor and the rotational axis of the electric motor. For example, one of the two Hall sensors can be aligned such that the detection direction of one Hall sensor is orthogonal to the connecting line between one Hall sensor and the rotational axis of the electric motor. The other of the two Hall sensors can be aligned such that the detection direction of the other Hall sensor encloses an angle other than 90° to the connecting line between the other Hall sensor and the rotational axis of the electric motor. In particular, the included angle can be 45°.

[0018] In a further embodiment of the proposed solution, the two differently aligned Hall sensors can be configured with a single 2D Hall sensor. This can reduce the installation space. In principle, the control unit of the proposed device, which is intended to be mounted on an electric motor, can be configured to generate a further output signal containing information about the detected direction of rotation. The control unit can be connected to the engine electronics and / or the on-board electronics of a car and / or another device configured to monitor the direction of rotation in order to send the output signal to them. Thus, the proposed device can enable robust monitoring of the direction of rotation.

[0019] It is also conceivable and possible for the control unit to be configured to derive a further output signal from the output signal and to determine the direction of rotation based on the derived output signal. Accordingly, the control unit can be configured to determine the direction of rotation indirectly via the output signal.

[0020] For example, the additional output signal can be embodied as a binary signal. It is conceivable in this case that the additional output signal switches between the two possible values ​​with each voltage change of the output signal. As a result, each change in the value in the binary additional output signal can correspond to a switching operation in one of the Hall sensors. Thus, the temporal profile of the additional output signal as well as the temporal profile of the output signal can have a temporal pattern that depends on the direction of rotation. Thus, the control unit of the device intended to be arranged on an electric motor can be configured to detect the direction of rotation of the electric motor by analyzing the additional output signal. A dependence of the temporal pattern in the additional output signal on the direction of rotation can be more pronounced than the dependence of the temporal pattern in the output signal.Thus, determining the direction of rotation by evaluating the additional output signal can increase detection reliability.

[0021] It is also conceivable and possible that the control unit of the proposed device could be a component of the motor electronics for controlling the motor. For example, the control unit could be part of an integrated circuit of the motor electronics. This could reduce the installation space for a motor with a device for detecting the direction of rotation and its assembly effort.

[0022] In a further embodiment of the proposed solution, the control unit can be configured to compare a temporal profile of the common output signal with a stored temporal profile for a clockwise rotation and with a stored temporal profile for a counterclockwise rotation. This can reduce the time required to detect the direction of rotation. Furthermore, the probability of an incorrect determination of the direction of rotation can be reduced.

[0023] To compare the temporal profile of the common output signal with the stored profile, the control unit can be designed with a memory and configured to retrieve data from the memory. The memory can contain information regarding the temporal profile for clockwise and counterclockwise rotation. For example, the memory can be a temporary memory, in particular a random access memory. This can reduce access times to the temporal profiles stored in the memory and thus further improve rapid determination of the direction of rotation.

[0024] In a further embodiment of the proposed device, the temporal profile of the output signal over a fraction of a complete revolution of a rotor of an electric motor can be used to detect the direction of rotation. In particular, the direction of rotation can be detected as soon as a magnetic flux density induced during operation of the electric motor has completed a complete period at the location of both Hall sensors.

[0025] In an exemplary embodiment of the proposed solution, the two Hall sensors are digital Hall sensors. This can simplify the signal processing of the output signal.

[0026] In a further embodiment of the proposed solution, the digital Hall sensors are latching Hall sensors. This can further simplify the signal processing of the common output signal.

[0027] A latching Hall sensor can be switched between two states. The Hall sensor stores its result and can only be switched again by a magnetic field of a different polarity and a predetermined strength. The upper switching point, for switching from a first to a second state, can be referred to as the upper operating point (BOP). The lower switching point, for switching from the second to the first state, can be referred to as the release point (BRP).

[0028] Due to the spatial separation of the Hall sensors by the angle, the rotating magnetic field generated by the electric motor during operation causes the Hall sensors to switch at different times. Due to the different trigger thresholds, the switching can also occur at different switching points.

[0029] According to the proposed solution, the control unit is configured to determine, in a temporal profile of the output signal, a ratio between a first time period in which both Hall sensors are in the same state and a second time period comprising the first period and a further period in which both Hall sensors are in different states. This can reduce the probability of erroneous detections and reduce the time required to detect the direction of rotation.

[0030] By way of example, the first time period can relate to the time in which both Hall sensors are in their first state, i.e., they have been switched to the first state by the magnetic field generated during operation of the electric motor with a magnetic flux density corresponding to the BRP of the two Hall sensors, and neither of the two Hall sensors has yet switched from the magnetic field to the second state. By way of example, the second time period can begin at a point in time at which the second Hall sensor is switched to the first state by the magnetic field, but the first Hall sensor is still in the second state. Accordingly, the second time period can end at the point in time at which the first Hall sensor is switched to the second state, while the second Hall sensor is already in the second state.

[0031] The aforementioned ratio of the time durations can have different values ​​depending on the direction of rotation due to the different trigger thresholds. Thus, detection of the direction of rotation is possible by comparing the aforementioned ratio of the time durations with a known value for the direction of rotation.

[0032] By way of example, the control unit can be configured to detect the direction of rotation for which the stored ratio of the first time period to the second time period has the smaller deviation from the measured ratio.

[0033] According to a further embodiment of the proposed device, the first Hall sensor and the second Hall sensor can be components of a common integrated circuit of the device. This allows the spatial separation of both Hall sensors to be fixed and more robust against mechanical influences. This can increase reliability. Furthermore, the number of individual components of the proposed device can be reduced. This can reduce assembly time, space requirements, and costs. Furthermore, by arranging the two Hall sensors on a common circuit, joint contacting is conceivable and possible. This can further reduce assembly effort.

[0034] The aforementioned object is also achieved by a drive system comprising an electric motor and the proposed device for detecting the direction of rotation of the electric motor. The two Hall sensors of the device are arranged on the electric motor at an angle to each other. This can enable the detection of the direction of rotation using the output signals of the two Hall sensors.

[0035] In a further embodiment of the proposed drive system, the two Hall sensors can be arranged on the electric motor in such a way that the maximum magnetic flux density acting on the first Hall sensor during motor operation is different from the maximum flux density acting on the second Hall sensor. This makes it possible to implement a different trigger threshold for the two Hall sensors.

[0036] In a further embodiment of the proposed drive system, the first Hall sensor and the second Hall sensor can be positioned at different distances from the electric motor. This also makes it possible to implement different trigger thresholds for the two Hall sensors.

[0037] In a further embodiment of the proposed drive system, the first Hall sensor and the second Hall sensor can have different orientations to the electric motor.

[0038] For example, the electric motor of the proposed drive system could be a brushless DC motor. This can increase the service life of the drive system and simplify operation.

[0039] For example, the electric motor can also be designed as an external rotor with a ring magnet. This can simplify the direction of rotation.

[0040] Furthermore, the proposed drive system can be configured to be contactable and operable with a four-wire wiring harness. The electric motor can be configured to be operated with two of the wires of the wiring harness. Furthermore, the proposed device for detecting the direction of rotation of the electric motor can be configured to be operated with the two remaining wires of the wiring harness. This can reduce the costs of the proposed drive system and assembly effort.

[0041] In particular, the proposed drive system can be configured to adjust an element of a motor vehicle by external power. For example, the element of the motor vehicle can be a vehicle seat, a door, a tailgate, a window, or a roof. Likewise, the proposed drive system can be a primary drive motor of a car.

[0042] The above statements on advantages and possible embodiments of the proposed device for detecting a direction of rotation of an electric motor also apply analogously to the proposed drive system.

[0043] The aforementioned problem is also solved by a vehicle seat with two components that can be adjusted relative to each other using the proposed drive system. This can improve user comfort and safety.

[0044] In addition, the object mentioned at the outset is also achieved by a vehicle having at least one adjustable vehicle part and a drive system coupled to the adjustable vehicle part for externally powered adjustment.

[0045] The above statements regarding advantages and possible configurations of the proposed drive system and the device for detecting a direction of rotation of an electric motor also apply analogously to the proposed vehicle seat and the proposed vehicle.

[0046] Furthermore, the aforementioned problem is also solved by an assembly method for assembling a drive system. The proposed assembly method comprises at least the following steps: - an electric motor, a first Hall sensor with a first trigger threshold and a second Hall sensor with a second trigger threshold for detecting a magnetic flux density generated during operation of the electric motor and a control unit are provided, - the two Hall sensors are arranged at an angle to each other on the electric motor, whereby the two Hall sensors have unequal trigger thresholds, - a signal output of the first Hall sensor and a signal output of the second Hall sensor are connected in parallel, and - the control unit is coupled to the parallel-connected signal outputs of the two Hall sensors for evaluating a common output signal received from the parallel-connected signal outputs of the two Hall sensors, wherein the control unit is configured to determine, in the temporal profile of the output signal, a ratio between a first time period in which both Hall sensors are in the same state, to a second time period comprising the first period and a further period in which both Hall sensors are in different states.

[0047] The proposed assembly method provides a drive system in which the direction of rotation can be determined by evaluating exactly one signal, namely the shared output signal of the two Hall sensors connected in parallel. The shared output signal contains information from the two Hall sensors spatially separated by an angle. This can reduce the probability of incorrect determinations of the direction of rotation. In conjunction with the detection of motor revolutions, this can improve the determination of an adjustment path caused by the electric motor. This can reduce the frequency of necessary calibrations of the electronics for determining the adjustment path and thus reduce maintenance effort. Likewise, the proposed solution can reduce the contacting effort and make the device more robust against malfunctions.

[0048] In an exemplary embodiment of the proposed assembly method, the proposed drive system can be provided.

[0049] All the above-mentioned statements regarding advantages and possible configurations of the proposed device for detecting a direction of rotation of an electric motor and of the proposed drive system therefore also apply analogously to the proposed assembly method.

[0050] Furthermore, the aforementioned object is also achieved by a method for detecting the rotational direction of an electric motor using the proposed device. The control unit of the device receives the combined output signal of the two Hall sensors and detects the rotational direction based on the combined output signal.

[0051] In a further embodiment of the proposed method, the control unit can compare a temporal profile of the output signal with a stored temporal profile for a clockwise and counterclockwise rotation. This can enable faster and more precise detection of the rotation direction.

[0052] The aforementioned problem is also solved by a computer program product for execution on a processor of the control unit of the proposed device. Such a computer program product contains instructions that, when executed, cause the processor to execute the proposed method.

[0053] All the above statements regarding advantages and possible embodiments of the proposed device for detecting a direction of rotation of an electric motor and the proposed drive system apply analogously to the proposed method and computer program product.

[0054] In principle, individual aspects of individual embodiments of the proposed solution can be combined with each other.

[0055] Individual embodiments of the proposed solution are explained in more detail using the figures shown below.

[0056] Here we show: Fig. 1 a schematic representation of a first embodiment of the proposed device with two Hall sensors and a control device in the intended state arranged on an electric motor, Fig. 2 an exemplary temporal course of a magnetic flux density at the location of the Hall sensors from Fig. 1 and a generated output signal from the Hall sensors, Fig. 3 a time course of a signal derived from the output signal of Fig. 1 derived further output signal, Fig. 4 a schematic representation of a second embodiment of the proposed device with two Hall sensors positioned differently from the electric motor, Fig. 5 is a circuit diagram of a third embodiment of the proposed device with two Hall sensors arranged on an integrated circuit, Fig. 6 a schematic representation of the third embodiment, Fig. 7 exemplary process flow of the proposed assembly process, and Fig. 8 exemplary procedure of the proposed method for detecting the direction of rotation.

[0057] Fig. 1 shows a schematic representation of a first embodiment of the proposed device 100 for detecting a direction of rotation RD of an electric motor 400 in a state in which it is intended to be arranged on an electric motor 400. The device 100 comprises a first Hall sensor 111, which is arranged outside the electric motor 400 at a first distance d1 from a rotation axis RA of the electric motor 400. The device 100 further comprises a second Hall sensor 112, which is connected in parallel to the first Hall sensor 111 and is also arranged outside the electric motor 400 at a second distance d2 from the rotation axis RA of the electric motor 400. The distances d1, d2 between the two Hall sensors 111, 112 are equal in the illustrated embodiment. The connecting lines between each of the Hall sensors 111, 112 and the rotation axis RA enclose an angle α1.A trigger threshold of the first Hall sensor 111 is different from the trigger threshold of the second Hall sensor 112. Both Hall sensors 111, 112 are connected in parallel and to an input of a control unit 113 of the device 100 in order to send a common output signal S1 to the control unit during operation of the electric motor 400. The control unit 113 is configured to read the output signal S1 generated by the Hall sensors and sent to the control unit 113 and to evaluate it to detect the direction of rotation RD of the electric motor 400. The parallel contacting of the two Hall sensors 111, 112 with a voltage supply and a ground potential, which is known to those skilled in the art, is described in . Fig. 1 not shown for reasons of clarity.

[0058] In the Fig. In the embodiment shown in Figure 1, the electric motor 400 is designed as an external rotor with a two-pole rotor 410. However, other designs of electric motors 400 are also conceivable and possible.

[0059] Fig. 2 shows a time course of a magnetic flux density B (left y-axis) in arbitrary units (au) at the location of the two Hall sensors 111, 112 from Fig. 1 and a time course of the common output signal S1 (right y-axis) in arbitrary units (au) of both Hall sensors 111, 112. The magnetic flux density B is shown in the upper part of the diagram. The output signal S1 is shown in the lower part of the diagram. The time axis (t [au]) is divided into two intervals. The first interval, t0 to t5, relates to a clockwise rotation of the electric motor 400 (CW). The second interval, from t5 to t10, relates to a counterclockwise rotation of the electric motor 400 (CCW).

[0060] Over the entire time period t0 to t10, the magnetic flux density B varies sinusoidally. Due to the angle α1, the magnetic flux density at the location of the first Hall sensor B(111) (dashed curve) is phase-shifted compared to the magnetic flux density at the location of the second Hall sensor B(112) (solid curve). Furthermore, the B-axis on the left in the diagram marks the lower switching point of the first Hall sensor BRP(111) (dashed line), the lower switching point of the second Hall sensor BRP(112) (solid line), the upper switching point of the first Hall sensor BOP(111) (dashed line), and the upper switching point of the second Hall sensor BOP(112) (solid line).

[0061] At the times t1, t2, t3, t4, t6, t7, t8 and t9 marked with vertical lines, a state switching of one of the two Hall sensors 111, 112 takes place. The times t1, t2, t3, and t4 lie in the time interval relating to the clockwise rotation CW of the electric motor 400. At t1, the magnetic flux density at the location of the second Hall sensor B(112) passes the lower switching point of the second Hall sensor BRP(112), whereby the second Hall sensor 112 is switched from the second to the first state. At time t2, the magnetic flux density at the location of the first Hall sensor B(111) passes the lower switching point of the first Hall sensor BRP(111), whereby the first Hall sensor 111 is switched from the second to the first state.At time t3, the magnetic flux density at the location of the second Hall sensor B(112) passes the upper switching point of the second Hall sensor BOP(112), thereby switching the second Hall sensor 112 from the first to the second state. At time t4, the magnetic flux density at the location of the first Hall sensor B(111) passes the upper switching point of the first Hall sensor BOP(111), thereby switching the first Hall sensor 111 from the first to the second state.

[0062] Times t6, t7, t8, and t9, on the other hand, lie in the interval relating to the counterclockwise rotation (CCW) of the electric motor 400. At time t6, the magnetic flux density at the location of the first Hall sensor B(111) passes the lower switching point of the first Hall sensor BRP(111), thereby switching the first Hall sensor 111 from the second to the first state. At time t7, the magnetic flux density at the location of the second Hall sensor B(112) passes the lower switching point of the second Hall sensor BRP(112), thereby switching the second Hall sensor 112 from the second to the first state. At time t8, the magnetic flux density at the location of the first Hall sensor B(111) passes the upper switching point of the first Hall sensor BOP(111), thereby switching the first Hall sensor 111 from the first to the second state.At time t9, the magnetic flux density at the location of the second Hall sensor B(112) passes the upper switching point of the second Hall sensor BOP(112), whereby the second Hall sensor 112 is switched from the first to the second state.

[0063] This results in the lower part of the diagram in Fig. 2 shows the common output signal S1 of the parallel-connected Hall sensors 111, 112. The switching of the Hall sensors 111, 112 leads to a modulation of the voltage of the output signal S1. This modulation can be measured as an example as a time-resolved voltage drop across a measuring resistor connected to the output signal S1 and ground. In the Fig. In the exemplary curve shown in Figure 2, the voltage of the output signal S1 varies between the three voltage values ​​U1, U2, U3. With each switching operation of one of the two Hall sensors 111, 112, the measurable voltage changes. According to the above explanations regarding the switching points BOP, BRP, the duration between t3 and t2 defines a first time period Δt1, in which both Hall sensors 111, 112 are in the same state. The duration from t1 to t4, on the other hand, defines a second time period Δt2, comprising the intervals t1 to t2 and t3 to t4, in which both Hall sensors 111, 112 are in different states, as well as the aforementioned first time period Δt1.

[0064] Analogously, in the case of counterclockwise rotation CCW, the first time period Δt1 is defined as the duration from t7 to t8 and the second time period Δt2 is defined as the duration from t6 to t9.

[0065] The numerical ratio of the first time period Δt1 to the second time period Δt2 is approximately 48% for clockwise rotation (CW) and approximately 21% for counterclockwise rotation (CCW). Thus, the rotation direction RD can be determined by determining the ratio of the first time period Δt1 to the second time period Δt2 and comparing a stored ratio for the two directions.

[0066] It is also conceivable and possible to derive a further output signal S2 from the output signal S1 and to determine the rotation direction RD based on the derived output signal S2. Since such an output signal S2 is derived from the output signal S1, the rotation direction RD is determined indirectly via the output signal S1.

[0067] This shows Fig. 3 shows an exemplary embodiment of a further output signal S2 derived from the output signal S1. In this case, the further output signal S2 is a binary signal that can assume the voltage values ​​U4 or U5. With each voltage change of the output signal S1, the further output signal S2 is switched from the previously existing voltage value U4, U5 to the other voltage value U4, U5. As a result, each voltage change of the further output signal S2 also corresponds to a switching operation of one of the Hall sensors 111, 112. In this case, the further output signal S2 always has the one voltage value U5 when the two Hall sensors 111, 112 are switched to different states. The one voltage value U5 of the further output signal S2 therefore correlates with the average voltage value U2 of the first output signal S1. If both Hall sensors 111, 112 are switched to the same states, the further output signal S2 has the other voltage value U6.As in . Fig. 3, the time periods during which the two Hall sensors 111, 112 are in the same or different states vary depending on the direction of rotation RD. Thus, the time course of the further output signal S2, as well as the time course of the output signal S1, shows a pattern that depends on the direction of rotation RD. In particular, the further output signal S2 depends on the direction of rotation RD by determining the ratio of a duration Δt3 during which one voltage value U5 is present to a duration Δt4 during which one voltage value U4 is present. In the present example, the ratio Δt3 / Δt4 during the time of rotation in the clockwise direction CW is approximately 200%. The ratio Δt3 / Δt4 during the time of rotation in the counterclockwise direction CCW is approximately 50%.Thus, the ratios Δt3 / Δt4 differ more significantly for different rotation directions RD than the ratios Δt1 / Δt2 in the output signal S1. Therefore, determining the rotation direction RD via the additional output signal S2 can be more robust than determining the rotation direction RD via the additional output signal S1.

[0068] In other conceivable and possible embodiments of the proposed device 100, 200, 300, the temporal behavior of the Fig. 2 and Fig. 3, the temporal behavior of the magnetic flux density B and the output signals S1, S2 may differ. For example, the magnetic flux density at the location of the first and second Hall sensors B(111, 112, 211, 212, 311, 312) may differ from each other in more aspects than just a phase shift. This may be the case, in particular, if the amplitude of the magnetic flux density at the location of one of the Hall sensors B(111, 112, 211, 212, 311, 312) is smaller in magnitude than the amplitude at the location of the other Hall sensor.

[0069] For example, this can be realized by magnetic shielding of one of the Hall sensors 111, 112, 211, 212, 311, 312 or by different distances d1, d2 of the Hall sensors 111, 112, 211, 212, 311, 312 to the electric motor 400.

[0070] This shows Fig. 4 shows a schematic representation of a second embodiment of the proposed device 200. Here, the distance d2 of the second Hall sensor 212 is greater than the distance d1 of the first Hall sensor 211 by a distance difference Δd. Due to the distance dependence of the magnetic flux density B generated by the electric motor 400 during operation, the magnetic flux density B(212) acting over time at the location of the second Hall sensor 212 not only corresponds to a phase-shifted flux density at the location of the first Hall sensor B(211). Rather, the amplitude of the temporal variation of the magnetic flux density at the location of the second Hall sensor B(212) is also reduced compared to the flux density at the first Hall sensor (B211). This allows a different trigger threshold to be realized even when using identical Hall sensors 211, 212.

[0071] In further conceivable and possible embodiments of the proposed device 100, 200, 300, the angle α1, α2 can assume significantly smaller or larger values. In particular, it is conceivable to combine the two Hall sensors in one component and thus operate with a significantly smaller angle α1, α2 than that in Fig. 4 to form the angle α1 shown.

[0072] This shows Fig. 5 shows a circuit diagram of an exemplary embodiment of the proposed device 300, in which both Hall sensors 311, 312 are arranged and contacted on a common integrated circuit IC. The installation space can thus be reduced compared to the embodiments of Fig. 1-4 can be reduced. Each of the Hall sensors 311, 312 has three contacts. One contact is for the supply voltage, one contact is for connection to a ground potential, and one connection is for outputting an output signal. On the internal circuit IC, the contacts for the supply voltage are connected in parallel with a first contact C1 of the internal circuit. The contacts for the output signal are also connected in parallel with a second contact C2 of the internal circuit. The contacts of the two Hall sensors 311, 312 are electrically connected on the internal circuit IS. For operation of the Fig. 5, the device 300 is connected via the contacts C1, C2 of the integrated circuit IC to a voltage source P and the control unit 313 of the device 300. Here, the voltage source P is connected to C1 and, as shown, the control unit 313 is connected to C2. Fig. In the embodiment shown in Figure 5, the control unit 313 is configured to measure a voltage drop across a measuring resistor in order to determine the rotational direction RD of an electric motor via the output signal S1. For this purpose, the measuring resistor is connected both to the second contact C2 and to a ground potential. This arrangement of the control unit 313 corresponds to low-side detection.

[0073] In further embodiments, an arrangement of the control unit 313 for measuring a voltage modulation on the supply side between the voltage source P and the first contact C1 is also conceivable and possible. Such an arrangement of the control unit 313 corresponds to high-side detection. Fig. 6 showed the embodiment of Fig. 5 in a state in which it is mounted as intended on an electric motor 400. The Hall sensors 311, 312, arranged on a common integrated circuit IC, have essentially the same distances d1, d2 from the rotational axis RA of the electric motor 400 and enclose the angle α2. The control unit 313 is connected to contact C2 to evaluate the output signal S1 of the two Hall sensors 311, 312.

[0074] Fig. Figure 7 shows a first possible sequence of the proposed assembly method for assembling a work system. Accordingly, in a first step, an electric motor 400, a first Hall sensor 111, 211, 311 with a first trigger threshold, and a second Hall sensor 112, 212, 312 with a second trigger threshold for detecting a magnetic flux density B generated during operation of the electric motor 400, as well as a control unit 113, 213, 313, are provided. Furthermore, the two Hall sensors 111, 112, 211, 212, 311, 312 are arranged on the electric motor 400 at an angle α1, α2 to each other, wherein the two Hall sensors 111, 112, 211, 212, 311, 312 have unequal trigger thresholds. In a third step, a signal output of the first Hall sensor 111, 211, 311 and a signal output of the second Hall sensor 112, 212, 312 are connected in parallel.In a fourth step, the control unit 113, 213, 313 is coupled to the parallel-connected signal outputs of the two Hall sensors 111, 112, 211, 212, 311, 312 for evaluating a common output signal S1 received from the parallel-connected signal outputs of the two Hall sensors 111, 112, 211, 212, 311, 312.

[0075] In principle, the sequence of process steps shown here does not imply a necessary order, so it is also conceivable to carry out the assembly steps in a different order than the one shown.

[0076] Fig. Figure 8 shows a possible embodiment of the proposed method for detecting a direction of rotation. The control unit first receives the common output signal S1 and then evaluates it as follows. In a first step, the first time period Δt1 and the second time period Δt2 in the temporal progression of the output signal S1 are determined according to the explanations for Fig.2. Accordingly, the first time period Δt1 refers to the time during which both Hall sensors 111, 112, 211, 212, 311, 312 are in their first state, i.e., they have been switched to the first state by the magnetic field generated during operation of the electric motor 400 with a magnetic flux density B corresponding to the BRP, and neither of the two Hall sensors 111, 112, 211, 212, 311, 312 has yet been switched to the second state by the magnetic field. The second time period Δt2 begins as soon as the second Hall sensor 112, 212, 312 is switched to the first state by the magnetic field, but the first Hall sensor 111, 211, 311 is still in the second state. The second time period Δt2 ends as soon as the first Hall sensor 111, 211, 311 is switched to the second state, while the second Hall sensor 112, 212, 312 is already in the second state.

[0077] Furthermore, the evaluation of the output signal S1 includes comparing the ratio of the first time period Δt1 to the second time period Δt2 with stored values ​​of the ratio for a clockwise CW and counterclockwise CCW rotation. Based on the comparison, in a final sub-step of the evaluation, the rotation direction RD of the electric motor 400 is determined as clockwise CW or counterclockwise CCW.

Claims

[1] Device (100, 200, 300) for detecting a direction of rotation (RD) of an electric motor (400), comprising: - a first Hall sensor (111, 211, 311) with a first trigger threshold and a second Hall sensor (112, 212, 312) with a second trigger threshold for detecting a magnetic flux density (B) generated during operation of the electric motor (400), wherein a signal output of the first Hall sensor (111, 211, 311) and a signal output of the second Hall sensor (112, 212, 312) are connected in parallel, and the two Hall sensors (111, 112, 211, 212, 311, 312) are configured to be arranged on the electric motor (400) at an angle (α1, α2) to one another during normal operation of the device (100, 200, 300) and to have unequal trigger thresholds, and - a control unit (113, 213, 313) coupled to the parallel-connected signal outputs of the two Hall sensors (111, 112, 211, 212, 311, 312) for evaluating a common output signal (S1) of the two Hall sensors (111, 112, 211, 212, 311, 312) received from the parallel-connected signal outputs, wherein the control unit (113, 213, 313) is designed to detect the direction of rotation (RD) based on the common output signal (S1), wherein the control unit (113, 213, 313) is designed to determine, in the time profile of the output signal (S1), a relationship between a first time period (Δt1), in which both Hall sensors (111, 112, 211, 212, 311, 312) are in the same state, to a second time period (Δt2), comprising the first period and a further period in which both Hall sensors (111, 112, 211, 212, 311, 312) are in different states. [2] Device (100, 200, 300) according to claim 1, characterized bythat the control unit (113, 213, 313) is configured to compare a time profile of the output signal (S1) with a stored time profile for a clockwise (CW) and counterclockwise (CW) rotation. [3] Device (100, 200, 300) according to claim 1 or 2, characterized by that the Hall sensors (111, 112, 211, 212, 311, 312) are latching Hall sensors. [4] Device (100, 200, 300) according to one of the preceding claims, characterized by that the first Hall sensor (311) and the second Hall sensor (312) are components on a common integrated circuit (IC). [5] Drive system comprising an electric motor (400) and a device (100, 200, 300) for detecting a direction of rotation (RD) of the electric motor (400) according to one of claims 1 to 4, wherein the two Hall sensors (111, 112, 211, 212, 311, 312) of the device (100, 200, 300) are arranged at an angle (α1, α2) to one another on the electric motor (400). [6] Drive system according to claim 5, characterized by that the two Hall sensors (211, 212) are arranged on the electric motor (400) in such a way that a maximum magnetic flux density (B) acting on the first Hall sensor (211) during operation of the motor is not equal to a maximum flux density on the second Hall sensor (212). [7] Drive system according to claim 5 or 6, characterized by that the first Hall sensor (211) and the second Hall sensor (212) have different distances from the electric motor (400). [8] Drive system according to one of claims 5 to 7, characterized bythat the first Hall sensor (211) and the second Hall sensor (212) have different orientations to the electric motor (400). [9] Vehicle seat with two components which are adjustable relative to each other by a drive system according to one of claims 5 to 8. [10] Assembly method for assembling a drive system, wherein: - an electric motor (400), a first Hall sensor (111, 211, 311) with a first trigger threshold and a second Hall sensor (112, 212, 312) with a second trigger threshold for detecting a magnetic flux density (B) generated during operation of the electric motor (400), and a control unit (113, 213, 313) are provided, - the two Hall sensors (111, 112, 211, 212, 311, 312) are arranged at an angle (α1, α2) to each other on the electric motor (400), wherein the two Hall sensors (111, 112, 211, 212, 311, 312) have unequal trigger thresholds, - a signal output of the first Hall sensor (111, 211, 311) and a signal output of the second Hall sensor (112, 212, 312) are connected in parallel, and - the control unit (113, 213, 313) is coupled to the parallel-connected signal outputs of the two Hall sensors (111, 112, 211, 212, 311, 312) for evaluating a common output signal (S1) received from the parallel-connected signal outputs of the two Hall sensors (111, 112, 211, 212, 311, 312), wherein the control unit (113, 213, 313) is configured to determine, in the temporal profile of the output signal (S1), a ratio between a first time period (Δt1), in which both Hall sensors (111, 112, 211, 212, 311, 312) are in the same state, to a second time period (Δt2), comprising the first period and a further period, in which both Hall sensors (111, 112, 211, 212, 311, 312) in different states. [11] Assembly method according to claim 10, characterized bythat the mounted drive system is a drive system according to one of claims 5 to 7. [12] Method for detecting a direction of rotation (RD) of an electric motor (400), with a device (100, 200, 300) according to one of claims 1 to 4, wherein the control unit (113, 213, 313) of the device (100, 200, 300) receives the common output signal (S1) of the two Hall sensors (111, 112, 211, 212, 311, 312) and detects the direction of rotation (RD) based on the common output signal (S1). [13] Method according to claim 12, characterized by that the control unit (113, 213, 313) compares a time profile of the output signal (S1) with a stored time profile for a clockwise (CW) and counterclockwise (CW) rotation. [14] Computer program product for execution on a processor of the control unit (113, 213, 313) of the device (100, 200, 300) according to one of claims 1 to 4, wherein the computer program product contains instructions which, when executed, cause the processor to carry out a method according to one of claims 12 or 13.

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