Sensor unit and method for operating such a unit, and motor vehicle

Abstract

In a sensor unit with an analog signal generator for acquiring values ​​for a rotatable element (for the purpose of measuring distance and / or speed, etc.), a second analog signal generator in the form of a temperature sensor is additionally provided. A single interface, preferably a single analog-to-digital converter (8), is provided. By acquiring the measured values ​​from the temperature sensor (7) as a function of a signal waveform from the measurement signals of the other analog signal generator (5), the measurement of the latter is minimally or not at all affected. Valuable information can be obtained through the temperature measurement during long-term operation, particularly when the sensor unit is used in a motor vehicle (1).

Description

[0001] The invention relates to a sensor unit that can be used in particular in a motor vehicle. It also relates to a corresponding motor vehicle and a method for operating a sensor unit.

[0002] Sensors for measuring distance and / or speed are now widely used in various automotive applications, particularly in tachographs. These sensors are designed for more complex applications as small, embedded microcontroller systems consisting of a sensor element and a microcontroller. The focus of these systems is on their primary function: the precise acquisition of distance and speed data. The components are optimized for efficient signal processing, low cost, and low power consumption.

[0003] From DE 10 2017 103 873 A1, for example, a sensor circuit is known which is designed to receive two sensor signals responding to measurements of a first physical quantity and to receive sensor signals responding to measurements of a second physical quantity. A multiplexed sensor signal is generated from the measurement signals by means of a multiplexer.

[0004] From US 2017 / 032 87 88 A1 a sensor arrangement with a magnet of a coil, a power supply unit and a computing unit, which is used to detect a periodicity of a voltage applied to the coil as well as to determine a temperature-dependent characteristic of the coil.

[0005] DE 10 2004 029 065 A1 describes an engine control unit which generates a trigger signal based on the angular position of a crankshaft, which controls the acquisition and A / D conversion of an analog sensor signal.

[0006] US 9 374 102 B1 proposes an ADC circuit with a control unit, taking into account at least one conversion characteristic of the AD converter, such as a conversion rate or conversion resolution, to ensure that different parts of the bandwidth of the ADC circuit are available to receive a first and second analog signal.

[0007] Furthermore, for example, DE 10 2023 210 763 A1 describes a sensor system that operates on the principle of pulse detection. A sensor can detect changes in the magnetic field of an associated pulse wheel. The sensor can include a pulse generator and is electromagnetically coupled to the pulse wheel. The pulse wheel or flywheel is connected to or attached to a moving or rotating vehicle component. For example, the pulse wheel in the transmission can be connected to a drive shaft. Such a pulse wheel typically has a disc-shaped form with teeth on its outer edge. As the vehicle moves, the ferromagnetic pulse wheel rotates in front of the sensor, causing the teeth to slide past the sensor. The sensor incorporates, for example, a Hall-effect IC (integrated circuit), i.e., a Hall probe with a bias magnet.The sensor operates without contact, utilizing the fact that the detected magnetic field changes with the movement of the impulse wheel. Specifically, the magnetic field is stronger in front of a tooth than in front of a gap. The sensor detects the magnetic field as the teeth slide past it and converts it into impulses in real time. The resulting sensor signal is available, for example, as an analog electrical signal, such as a voltage signal and / or a current signal.

[0008] These types of sensors are frequently used in extreme environmental conditions, ranging from very low to very high temperatures. They are also subjected to mechanical stresses such as vibration and shock. Therefore, the sensors must be robust and function reliably.

[0009] The purpose of the invention is to contribute to permanently improving the performance and reliability of such systems.

[0010] The problem is solved by a sensor unit with the features according to claim 1, by a motor vehicle with the features according to claim 8, and by a method for operating a sensor unit with the features according to claim 11. Advantageous embodiments are found in the dependent claims.

[0011] The sensor unit according to the invention thus comprises: - A first analog signal generator for providing measurement signals generated by a rotating element (in particular the aforementioned pulse wheel or flywheel); - a second analog signal generator for providing measurement signals for a temperature, in particular a temperature related to the rotating element; - a data processing facility; and - an interface through which the data processing device is coupled to both the first analog signal generator and the second analog signal generator, wherein the data processing device is designed to query measurement signals provided by the first analog signal generator only via the interface in a basic state and to query measurement signals for temperature provided by the second analog signal generator via the interface at a fixed time, which is determined depending on a signal profile of the measurement signals that the data processing device has received from the first analog signal generator upon querying.

[0012] The invention introduces the idea of ​​measuring temperature using the same sensor unit and feeding the signals to the same data processing device. It further incorporates the idea of ​​using a common interface. By querying the temperature at a defined time, determined based on the signal profile of the measurement signals from the rotating element, a kind of pause in the query can be implemented at an optimal time, without negatively impacting the measurement. Thus, the common interface and the integration of the temperature sensor (second analog signal transmitter) allow for a compact and cost-effective sensor unit.

[0013] According to a preferred embodiment, the data processing device is designed to perform the query in the initial state multiple times over half a period of the period defined by the rotating element, in particular by a tooth sequence on the rotating element, and preferably also multiple times over a quarter of a period of the period defined by the rotating element. A correspondingly high clocking rate makes it particularly easy to "insert" the temperature measurement between these queries. In the case of the aforementioned unit, for example, frequencies of approximately 40 kHz may be suitable for the readout.

[0014] According to a further preferred embodiment of the invention, preferably in conjunction with the aforementioned preferred embodiment of obtaining the data values ​​(repeating the query) at high frequency, the data processing device is designed to make the query of the measurement signals from the second analog signal generator so short that a complete digital signal can nevertheless be obtained, in particular calculated, for the signals from the first analog signal generator.

[0015] According to a further preferred embodiment of the invention, it is further provided that, as with the sensor mentioned at the outset, the first analog signal transmitter comprises a magnetic sensor, preferably a magnetic sensor utilizing the Hall effect.

[0016] According to a further preferred embodiment of the invention, the sensor unit comprises a single analog-to-digital converter in or as an interface, which is controllable by the data processing unit and is configured and designed such that, depending on the control, it selectively supplies the measurement signals of either the first analog signal transmitter or the second analog signal transmitter to the data processing unit. The control can be related to a switch that is part of the analog-to-digital converter.

[0017] In this respect, another analog-to-digital converter can be saved by using the single analog-to-digital converter for both the signals for the rotation of the rotating element and for the temperature sensor (second analog signal transmitter).

[0018] According to a further preferred embodiment of the invention, the data processing device is designed to perform an analysis of those measurement signals from the first analog signal generator that have been received as a result of at least the last two queries, preferably also as a result of at least three, more preferably as a result of at least four, more preferably as a result of at least five, more preferably as a result of at least six, more preferably as a result of at least seven, more preferably as a result of at least eight, more preferably as a result of at least nine, more preferably as a result of at least ten, more preferably as a result of the last fifteen queries.

[0019] In this way, the shape of the analog signal can be predicted, so that, as already stated, a digital signal can be reconstructed (calculated) despite the intermediate temperature query.

[0020] According to another preferred embodiment, the data processing device is designed to perform a temperature query at the second analog signal transmitter after detecting the start of an edge in the signal waveform of the measurement signals from the first analog signal transmitter under predetermined conditions. With sufficient frequency (e.g., several times in a quarter period, as already mentioned), the remaining shape of the edge can be predicted, and then a limited number of subsequent measurements can be omitted.

[0021] The timing of the query of the measurement signals from the first analog signal generator can be regular, and the temperature query can be performed within the same timing, approximately over one to two, preferably no more than five, query cycles.

[0022] The temperature is measured under predetermined conditions: Naturally, it is not necessary to measure the temperature in every rotation period of the rotating element. In a moving vehicle, the temperature will hardly change, even if the rotating element rotates 1,000, 10,000, or 100,000 times. Therefore, the temperature measurement can be performed in units of approximately 10,000, 100,000, 1,000,000, or 10,000,000 rotation periods. Alternatively, in all the aforementioned embodiments of the sensor unit according to claim 1, the predetermined conditions for measuring the temperature can be met at fixed time intervals, such as every 15 minutes or the like. When the rotating element (the vehicle) is stationary, these time intervals could also be increased.

[0023] The motor vehicle according to the invention comprises a shaft, typically the drive shaft being the central element, to which a rotatable element, in particular an impulse wheel, is attached, and it comprises the sensor unit of the type according to the invention, also in all preferred embodiments, wherein the first analog signal generator detects measurement signals for the rotation of this rotatable element on the shaft.

[0024] In the motor vehicle according to the invention, the compact and inexpensive sensor unit of the type according to the invention is thus used in practice.

[0025] According to a preferred embodiment, the sensor unit in the motor vehicle is designed to also regularly measure the temperature when the shaft is not rotating (i.e., when the motor vehicle is stationary). Information about the temperature can also be helpful in this situation; possibly even for purposes completely different from measuring the rotational speed of the shaft and the like.

[0026] According to a preferred embodiment of the motor vehicle, the sensor unit includes a memory in which temperature measurements are stored. In particular, the data processing unit is designed to store the temperature measurements in the memory, and optionally also derived data values ​​and, optionally, further measurements, such as those from the first analog signal transmitter. In this way, a long-term, possibly even multi-year, profile of the temperature trend can be obtained and subsequently read from the memory, enabling long-term monitoring of the motor vehicle components, especially the sensor unit itself, and allowing these components to be optimized.

[0027] The inventive method for operating a sensor unit, in which, on the one hand, an analog signal generator for providing measurement signals to a rotating element and, on the other hand, a temperature sensor as a second analog signal generator share a common interface to a data processing device, the data processing device first queries measurement signals to this rotating element from the first analog signal generator and, depending on the signal profile of these measurement signals, provides a pause in which the data processing device queries measurement signals from the temperature sensor, in order to preferably then return to querying the measurement signals to the rotating element from the first analog signal generator.

[0028] According to a preferred embodiment of the method, it is further provided that measurement signals from the temperature sensor are repeatedly queried, preferably even when the rotating element is stationary (i.e., in the example case, when the vehicle is stationary), and that corresponding data are stored in a memory. Preferably, the temperature measurements are stored directly, but optionally these are stored in combination with the rotational speeds of the rotating element to optimize analysis, and so on.

[0029] To perform the described steps, a processor circuit can be provided that includes programming or software comprising program instructions which, upon execution of the program instructions, cause the processor circuit to carry out an embodiment of the method. The processor circuit can include at least one microprocessor and / or microcontroller. The program instructions can be stored in a data memory of the processor circuit.

[0030] The invention also includes further developments of the method according to the invention, which have features already described in connection with the further developments of the sensor unit and the motor vehicle according to the invention. For this reason, the corresponding further developments of the method according to the invention are not described again here.

[0031] For use cases or application situations that may arise during the procedure and are not explicitly described here, it may be provided that, according to the procedure, an error message and / or a request for user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0032] The invention also includes combinations of the features of the described embodiments.

[0033] An embodiment of the invention is described below. The following is shown: Fig. 1 a motor vehicle according to an embodiment of the invention with a sensor unit according to an embodiment of the invention in perspective view in partial view through; Fig. 2 the signals obtained from the first analog signal generator above and the digital signals derived from them below; Fig. 3. Above, a curve of the analog signals of the first analog signal generator with an interruption for temperature measurement, and below, the digital signal corresponding to the first analog signal generator; and Fig. 4. A temperature profile in the form of a bar chart, which assigns a number of hours to temperature ranges.

[0034] The embodiment described below is a preferred embodiment of the invention. In this embodiment, the described components each represent individual features of the invention that can be considered independently of one another. Each of these features further develops the invention independently and can therefore be considered part of the invention individually or in a combination other than that shown. Furthermore, the described embodiment can also be supplemented by other features of the invention already described.

[0035] In the figures, functionally identical elements are each provided with the same reference symbols.

[0036] Fig. Figure 1 shows a schematic representation of vehicle 1. In this example, vehicle 1 is designed as a passenger car. Fig. Figure 1 shows vehicle 1 from a side perspective view. The vehicle includes a drive shaft 2, which serves to transmit power between a gearbox and the respective driven wheel of vehicle 1. To obtain motion information about vehicle 1, vehicle 1 also includes a sensor unit 4. The motion information can, for example, relate to or contain speed information v and / or distance information w. The motion information thus provides information about the speed of vehicle 1 and / or the distance / path that vehicle 1 has already traveled.

[0037] The sensor unit 4 comprises a first analog signal generator 5 and a processing unit 6 as a data processing device. The processing unit 6 comprises, for example, one or more microprocessors or microcontrollers and is designed to perform arithmetic operations. This includes, for example, processing a sensor signal S1 to determine the desired motion information provided by the first analog signal generator 5. To determine the motion information, the first analog signal generator 5 is electromagnetically coupled to a pulse wheel 3. In the present embodiment, the pulse wheel is attached to the drive shaft 2. It is attached in such a way that the pulse wheel 3 moves along with the drive shaft 2. The movement of the pulse wheel 3, and thus indirectly also the movement of the vehicle 1 via the drive shaft 2, can be detected by the first analog signal generator 5 in the form of pulses.The impulses are output as a sensor signal by the first analog signal generator 5.

[0038] The sensor unit 4 provides a pulse generator for producing a representative position and / or speed signal (sensor signal) based on dynamically adaptive pulse detection. The first analog signal generator 5 can be installed or mounted at various locations in the vehicle, such as in a vehicle transmission, on the drive shaft, or on the axles. The sensor signal is representative because the detected position and / or speed information is only proportional to the vehicle's position or speed information, as in the present embodiment on the drive shaft.

[0039] The following is a brief summary of the operating principle of sensor unit 4: For example, the pulse wheel is attached to the drive shaft 2 in the gearbox to acquire position and / or speed information. As shown in the exemplary embodiment in Fig. Figure 1 shows a disc-shaped element with teeth on its outer edge. As the vehicle 1 moves, the ferromagnetic pulse wheel 3 rotates in front of the first analog signal generator 5. The first analog signal generator contains, for example, a Hall-effect IC with a bias magnet. The first analog signal generator thus operates without contact. Specifically, the first analog signal generator reacts to changes in the magnetic field that occur when the pulse wheel 3, and especially its teeth, move past the first analog signal generator. This is achieved by exploiting the fact that the magnetic field is stronger in front of a tooth than in front of a gap. The magnetic field is detected by the first analog signal generator as the teeth slide past it and converted into pulses in real time via dynamic adaptive pulse detection and output as a real-time signal.This real-time signal is the sensor signal S1, which is present, for example, as an electrical signal such as a voltage signal. The shape of the sensor signal S1, i.e., the pulses generated by the movement of the pulse wheel, is representative of the vehicle's movement. For example, the distance traveled by the vehicle can be determined from the number of teeth that have passed the first analog signal generator. The pulses per unit of time contained in the sensor signal provide, for example, a measure of the vehicle's speed. By evaluating the sensor signal S1, for example, in the processing unit, the desired motion information can be determined.

[0040] In the present case, in addition to the first analog signal generator 5, there is also a second analog signal generator 7, which is configured as a temperature sensor, i.e., it provides measurement signals for a temperature, in particular a temperature related to the rotating element. The question is what temperature prevails in the area of ​​the pulse wheel 3.

[0041] The second analog signal generator 7 also supplies a signal S2 to the processing unit 6, which is intended to be a data processing device according to the invention. An analog-to-digital converter 8 serves as the interface between the analog signal generators 5 and 7 on the one hand and the data processing device (processing unit) 6 on the other. The data processing device 6 is further equipped with a memory 9 in which some of the measured values ​​can be stored. This is done primarily for the temperature measurement signals from the second analog signal generator 7.

[0042] The temperature no longer needs to be measured constantly; however, by sharing a single interface (the analog-to-digital converter 8), it is necessary to interrupt the querying of signals S1 from the first analog signal generator 5 in order to obtain signals S2 from the second analog signal generator 7.

[0043] First, the following illustrates this: Fig. 2 a typical signal S1, as emitted by the first analog signal generator. Since the analog-to-digital converter 8 converts this signal sequence S1, the data processing unit 6 ultimately receives the digital signal D1, which, however, may also have been further processed by the data processing unit into its final form D1 shown here.

[0044] Now, the temperature measurement should also be performed at some point, for example, hourly. It may be that the vehicle 1 is currently stationary; in this case, the data processing unit 6 with the analog-to-digital converter 8 and, naturally, the second analog signal generator 7 simply need to be powered on (if not left switched on) in order to operate. A measurement can then be carried out without any problems. However, if the vehicle 1 is not stationary, the temperature measurement must somehow be implemented in a signal sequence as shown in... Fig. The insertion process is shown above as S1. How exactly this happens is explained using the following: Fig. 3 explained:

[0045] The data processing unit (computing unit) 6 receives a sequence of measurement signals M1, M2, M3, M4 from the first analog signal generator. Based on the signal waveform, it recognizes this sequence as a rising edge. The digital signal D1 is already reaching its upper level. This is considered a suitable moment to pause the acquisition of signals from the first analog signal generator, and instead, two temperature signals T1, T2 are acquired from the second analog signal generator 7. This is sufficient to perform the temperature measurement redundantly, so that subsequently, signals M7, M8, M9 detect that the maximum is reached in the period, resulting in a falling edge at M10, M11, M12, and the digital signal D1 falls back to its lower value at time M12. Measurement values ​​M13, M14 to M25 are then acquired at regular intervals without pause.

[0046] A period like in signal D1 from Fig. 2 below and also in Fig. As shown in Figure 3, this is typically characterized by the passage of a tooth followed by a tooth gap of the pulse wheel 3 past the Hall IC in the first analog signal generator 5. It is therefore preferable that, in the initial state, the measurement points are taken multiple times over a partial period of the rotation of the rotating element, relative to one tooth. For example, if the goal is to take 15 to 16 measurements, then the number 16 must be multiplied by the number of teeth to determine the number of measurements per revolution of the pulse wheel 3. The timing of the measurements at points M1, M2, M3, and also T1, T2, etc., can be constant and based on a maximum rotational speed of the pulse wheel 3, or it can be adjusted repeatedly.

[0047] The acquired temperature values ​​T1, T2, or an average of the two, or the more plausible value, are now stored in memory 9 of sensor unit 4. By measuring the temperature over the lifetime of the vehicle, or at least of sensor unit 4, a profile can subsequently be obtained as shown in Fig. 4 shown: The bar chart shows, for example, 10 hours for temperature ranges of -40°C, 30 hours for around -35°C, 50 hours for around -25°C, and so on. A maximum of 1,500 hours is recorded in the range around +95°C. It should be noted that the temperature inside a vehicle is higher than the ambient temperature due to the operation of the engine and friction in the drivetrain.

[0048] Such information can then be used to optimize the mechanics and / or, if necessary, the electronics in the motor vehicle, especially the sensor unit 4 itself.

[0049] The advantages of the measures according to the invention include the following: 1. Integrated temperature monitoring: By synchronizing temperature monitoring with displacement and / or velocity measurement, an additional sensor is integrated that operates without affecting the primary function. This enables continuous monitoring of the ambient temperature. 2. Optimal resource utilization: The invention efficiently utilizes the existing computing unit / data processing device 6, which is typically designed as a microcontroller, as well as the built-in analog-to-digital converter 8, without requiring additional hardware. This saves costs and space and reduces energy consumption. 3. Recording of environmental conditions: Systematic recording of temperature data over the lifespan of the sensor unit provides valuable information for analyzing and optimizing the overall system. This is particularly useful in extreme environments where the sensor unit with its two analog signal transmitters is exposed to high temperatures and mechanical stresses. 4. Improved system reliability: By recording and analyzing temperature profiles, such as in Fig. As shown in Figure 4, the reliability and lifespan of the sensor unit can be increased. Early signs of overheating and other environmental problems can be detected, and appropriate measures can be taken. 5. No impairment of the primary function: The temperature measurement is performed in such a way that the primary function of the displacement and / or velocity measurement is not impaired. This is achieved by the strategic placement of the temperature measurements (T1, T2) in the sampling cycles (M1 - M4, M7 ff.). 6. Cost efficiency, as there are no additional hardware costs, except possibly for the temperature sensor. 7.

[0050] Overall, this example shows how a sensor for measuring distance and / or speed with integrated temperature profiling can be provided with limited resources. Reference symbol list 1 vehicle 2 Drive shaft 3 Impulse wheel 4 sensor units 5 first analog signal generator 6 Calculation unit 7 second analog signal generator, temperature sensor 8 Analog-to-Digital Converters 9 storage D1 Digitalsignal M1-M4 Messsignal M7-M25 Messsignal S1 Signal S2 Signal T1 Temperatursignal T2 Temperatursignal

Claims

[1] Sensor unit (4), comprising: - a first analog signal generator (5) for providing measurement signals (S1) generated by a rotating element (3); - a second analog signal generator (7) for providing measurement signals (S2) to a temperature, in particular a temperature related to the rotating element (3); - a data processing device, in particular a microcontroller (6); and - an interface (8) via which the data processing device (6) is coupled to both the first analog signal generator (5) and the second analog signal generator (7), wherein the data processing device (6) is designed to query measurement signals (S1) provided by the first analog signal generator (5) only via the interface (8) and to query measurement signals (S2) for temperature provided by the second analog signal generator via the interface at a fixed time, which is determined depending on a signal profile of the measurement signals which the data processing device (6) has received from the first analog signal generator (5) upon querying. [2] Sensor unit (4) according to claim 1, wherein the data processing device (6) is designed to perform the query in the ground state multiple times over half a period of the period defined by the rotating element, in particular by a tooth sequence on the rotating element, preferably over a quarter period of this defined period. [3] Sensor unit (4) according to claim 1 or 2, wherein the data processing device (6) is designed to make the query of the measurement signals from the second analog signal generator (7) so short that nevertheless a complete digital signal (D1) can be calculated from the signals (S1) from the first analog signal generator (5). [4] Sensor unit according to one of claims 1 to 3, wherein the first analog signal transmitter comprises a magnetic sensor, preferably a magnetic sensor utilizing the Hall effect. [5] Sensor unit (4) according to one of claims 1 to 4, comprising a single analog-to-digital converter (8) in the interface or as the interface, which is controllable by the data processing device (6) and is switched and designed such that, depending on the control, it selectively supplies the measurement signals of the first analog signal generator (5) or of the second analog signal generator (7) to the data processing device (6). [6] Sensor unit (4) according to one of claims 1 to 5, wherein the data processing device is designed to perform an analysis of those measurement signals from the first analog signal transmitter that have been received as a result of the at least two most recent queries from it. [7] Sensor unit (4) according to one of claims 1 to 6, wherein the data processing device is designed to perform a temperature query at the second analog signal transmitter (7) after detecting an edge start in the signal progression of the measurement signals from the first analog signal transmitter (5) under predetermined conditions. [8] Motor vehicle (1) with a shaft, in particular drive shaft (2), to which a rotatable element, in particular impulse wheel (3), is attached, and with the sensor unit (4) according to one of claims 1 to 7, wherein the first analog signal generator (5) detects measurement signals for the rotation of this rotating element on the shaft. [9] Motor vehicle (1) according to claim 8, wherein the sensor unit (4) is designed to also regularly detect the temperature when the shaft is not rotating. [10] Motor vehicle (1) according to claim 8 or 9, with a memory (9) in the sensor unit (4) in which temperature measurements are stored. [11] Method for operating a sensor unit (4) in which, on the one hand, a first analog signal generator (5) for providing measurement signals to a rotating element (3) and, on the other hand, a temperature sensor as a second analog signal generator (7) share a common interface (8) to a data processing device (6), wherein the data processing device (6) first queries measurement signals to this rotating element (3) from the first analog signal generator (5) and, depending on the signal profile of these measurement signals, provides a pause in which the data processing device (6) queries measurement signals from the temperature sensor (7). [12] Method according to claim 11, wherein the measurement signal from the temperature sensor (7) is repeatedly queried and corresponding data are stored in a memory (9).

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