DE102019119445A1 - Device and method for speed measurement - Google Patents

Abstract

The invention relates to a data transmission protocol for rotary encoders. The device according to the invention for generating an electrical signal, from which a rotational speed of a mechanical component (16) can be derived, comprises: a measuring unit (22) set up to detect a rotational movement of the mechanical component (16); anda signal generation unit (22) configured to generate an output signal; wherein the output signal comprises a sequence of electrical pulses (28), the spacing of which changes with the speed of rotation, and wherein a digital signal (30) is arranged between two electrical pulses (28) wherein the digital signal (30) comprises a first digital value (34) and a second digital value (36), the first digital value (34) indicating which state variable the second digital value (36) relates to. Thus, in addition to the speed signal, the speed being determined by the distance between the electrical pulses (28), the device provides additional information with the digital signal (30). The invention also includes a corresponding method for generating an electrical signal and a vehicle.

Description

The present invention relates to a data transmission protocol that can be used when measuring the rotational speed of rotating elements in order to transmit additional information relating to the rotational speed measurement from the rotational speed sensor to an electronic device. The invention relates in one form to an apparatus for speed measurement and in another form to a method for speed measurement. In one embodiment, the invention also relates to a suitably equipped vehicle.

Speed sensors typically generate a sinusoidal signal, the frequency of which depends on the speed. A square-wave output signal can be derived from the sinusoidal signal, for example by generating an electrical pulse at each zero crossing of the sinusoidal signal. The speed can then be calculated from the (time) interval between the pulses. In addition, additional information can be transmitted between the pulses (ie in the pulse pauses). So teaches, for example WO 98/25148 A2 to transmit a data word with a width of several bits in the pulse pauses, the speed pulses and the data word bits differing in terms of different current levels.

From the WO 98/09173 A1 an arrangement for detecting the rotational behavior of a rotating body or encoder with a sensor module (comprising a sensor element) and a controllable current source which supplies an impressed current representing the rotational behavior is known. The arrangement also includes a modulator which controls the current source as a function of signals from the sensor element and signals which an external signal source supplies via an additional connection, and an evaluation circuit. The sensor module is magnetically coupled to the encoder and the output signal of the sensor module is a signal representing the rotational behavior, on which a status and / or additional signal is superimposed.

From the DE 199 11 774 A1 a sensor arrangement for detecting movements is known, in which a sensor signal is generated in an active sensor by an encoder acted upon by the movement. The sensor arrangement has a first device with which the sensor signal is converted, together with at least one piece of additional information, into an output signal that can be transmitted to an evaluation device, a second device being provided with which a signal voltage dependent on an air gap between the active sensor and the encoder is recorded and is supplied to the first device for transmission as additional information.

From the DE 196 34 714 A1 an arrangement for a motor vehicle control system with active sensors (z. B. wheel speed sensors) is known, the output signals of which are fed to an evaluation circuit located on the receiver side via sensor lines that form a transmission path. The arrangement can be used to transmit additional data over the transmission path in one or in both transmission directions.

From the WO 02/090999 A1 An arrangement of a wheel speed sensor and a control unit (ECU) is known, the wheel speed sensor being connected to the control unit via a data interface and having means for sending additional information in signal channels and each piece of information being assigned to a signal channel and / or a fixed number of signal channels. Furthermore, the wheel speed sensor comprises switching means with which the assignment of the additional information, which is transmitted in the pauses between the speed pulses, to the available channels can be made by switching the mode. The switching means can be an external device or a sensor-integrated device. The switchover takes place as a function of the driving mode, e.g. as a function of the wheel speed. 9 bits can be transmitted per data word, whereby the individual bits are viewed as individual channels with which status information is transmitted. In one mode, a digital value with a width of 4 bits can also be transmitted. This is the measured magnetic air gap field strength.

With the known solution, there is the problem that a status recognition has to take place on the receiving side in order to evaluate the transmitted data, e.g. by determining the wheel speed. In the known solution, status information and a single measured value are transmitted. With the known solution it is not possible to transfer different measured values with optional flexibility. The present invention discloses a data transmission protocol that can be used when measuring the rotational speed of rotating elements in order to efficiently transmit various types of additional information to an electronic device, which information can be easily evaluated by the receiving device.

• eine Messeinheit, eingerichtet zur Erfassung einer Rotationsbewegung des mechanischen Bauteils; und
• eine Signalerzeugungseinheit, eingerichtet zur Erzeugung eines Ausgangssignals;
• wobei das Ausgangssignal eine Folge elektrischer Pulse, deren Abstand sich mit der Rotationsgeschwindigkeit ändert, umfasst, und wobei zwischen zwei elektrischen Pulsen ein digitales Signal angeordnet ist, wobei das digitale Signal einen ersten Digitalwert und einen zweiten Digitalwert umfasst, wobei der erste Digitalwert anzeigt, auf welche Zustandsgröße sich der zweite Digitalwert bezieht. Somit stellt die Vorrichtung neben dem Drehzahlsignal, wobei die Drehzahl durch den Abstand der elektrischen Pulse bestimmt wird, mit dem digitalen Signal eine Zusatzinformation bereit. Das digitale Signal umfasst einen ersten Digitalwert und einen zweiten Digitalwert, wobei der erste Digitalwert anzeigt, auf welche Zustandsgröße sich der zweite Digitalwert bezieht.

In one variant, the invention relates to a device according to the invention for generating an electrical signal from which a speed of a mechanical component can be derived, comprising:

• a measuring unit set up to detect a rotational movement of the mechanical component; and
• a signal generation unit configured to generate an output signal;
• wherein the output signal comprises a sequence of electrical pulses, the spacing of which changes with the speed of rotation, and wherein a digital signal is arranged between two electrical pulses, the digital signal comprising a first digital value and a second digital value, the first digital value indicating which state variable the second digital value relates to. Thus, in addition to the speed signal, the speed being determined by the distance between the electrical pulses, the device provides additional information with the digital signal. The digital signal comprises a first digital value and a second digital value, the first digital value indicating which state variable the second digital value relates to.

The digital signal can for example consist of a data word, the data word in particular having a word length of 9 bits. The data word has a first digital value and a second digital value, the first digital value indicating which state variable the second digital value relates to. In particular, bits 1 and 2 of the data word can be used to indicate which information or state variable is transmitted in the second digital value. For example, bits 5 to 7 of the data word can be used to transfer the status variable or information. Temperature information, mode information or air gap information can be named as an example of state variables or information. The electronic device that receives the data word can evaluate the transmitted data at any time without being restricted to certain states. For this it is only necessary to know the first digital value. This then indicates which type of data is contained in the second digital value. The first digital value contains the measurement type identification, so to speak. This makes it possible to change the rhythm of the transmission of the various data types as required and independently of the wheel speed.

The measuring unit can include an ambient condition measuring unit, in particular a temperature measuring unit, which is set up to measure an ambient condition to which one or more elements of the first measuring unit are exposed, and a signal generating unit which is set up to convert measured ambient condition measuring values into digital values and to generate an output signal . The output signal comprises a sequence of electrical pulses, the spacing of which changes with the speed of rotation, and digital signals arranged between the electrical pulses, which correspond to the digital values.

The term "measuring unit, set up to detect a rotational movement of a mechanical component", as used in the description and the claims, is to be understood in particular as sensors that are set up on the basis of a change in the magnetic flux (Hall effect) Measure the movement of (ferromagnetic) structures, such as gear wheels, gear rings, perforated disks, pole rings, etc. without contact. Furthermore, the term temperature measuring unit, as used in the description and the claims, is to be understood in particular as sensors that are set up to measure the temperature, for example on the basis of a change in the electrical resistance.

Furthermore, the term “digital value”, as used in the description and the claims, is to be understood as a digitally (for example binary) coded value or value range. Furthermore, the term “output signal”, as used in the description and the claims, is to be understood in particular as an electrical voltage and / or an electrical current that is impressed on a line, thereby providing information represented by the output signal a receiver or a control device that measures the voltage applied to the line and / or the current flowing through the line (and evaluates it in accordance with a transmission protocol).

In addition, the term “electrical pulse” as used in the description and the claims is to be understood in particular as a square-wave signal with a voltage and / or a current flow that is kept constant over a certain time interval, the voltage and / or the current level of the pulse typically differs from the voltage and / or current levels of the digital signals. Furthermore, the phrase “a sequence of electrical pulses, the spacing of which changes with the speed of rotation”, as used in the description and the claims, is to be understood in particular as a sequence of electrical pulses, the spacing between the pulses decreasing when the the rotation speed increases. For example, the speed can correspond to a value that results from dividing the pulses generated per unit of time by a fixed (integer) factor.

The ambient condition measured values, in particular temperature values, humidity values, electric field strength, magnetic field strength, etc. can be used on the receiver side to correct the speed and / or used to diagnose faulty operation.

The output signal preferably comprises digital signals which are arranged between two successive electrical pulses and which embody a first digital value and a second digital value, the first digital value indicating that the second digital value transports an ambient condition signal, in particular a temperature signal.

This makes it possible to send the ambient condition signals, in particular temperature signals, alternately with other signals or to activate and deactivate the transmission of the ambient condition signals (during the runtime).

The signal generation unit is preferably set up to check whether the ambient condition measured values are in an intended operating range or whether the ambient condition is outside or above the intended operating range.

If so, the signal generation unit can be set up in such a way that it displays a special event with the first digital value and communicates the type of special event in the second digital value. If, for example, the temperature value has reached a critical temperature, a temperature alarm can be displayed in the first digital value and the level of the measured temperature in the second digital value. The output signal preferably has a constant number of data bits between two consecutive electrical pulses, a first part of the data bits indicating which information is transmitted in a second part of the data bits and the signal generating unit is preferably set up to have the information to be transmitted during operation Based on the state of the device.

For example, the signal generating unit can alternately (and / or as required) provide ambient condition information in the pulse pauses, in particular temperature information or air gap information or sensor mode information and / or (possibly freely programmable) additional information, the information e.g. using a bit sequence consisting of 3 bits is transmitted and a bit sequence consisting of 2 bits indicates which information (in the respective data word) is transmitted. Examples of sensor mode information or mode information are the mode of faultless sensor or faulty sensor.

The signal generation unit is preferably set up to transmit ambient condition measurement values in the second part of the data bits or to increase a frequency at which ambient condition measurement values are transmitted in the second part of the data bits if the ambient condition is outside or above the intended operating range.

For example, the signal generating unit can be set up to send the temperature data only when the temperature measurement is above a certain value, or to send the temperature measurement more frequently when the temperature measurement is above a certain value, for example to show the temperature profile in finer resolution or above to provide a longer period.

• Erfassen einer Rotationsbewegung des mechanischen Bauteils mittels eines Sensors;
• Erzeugen einer Folge elektrischer Pulse, deren Abstand von der Rotationsgeschwindigkeit abhängt; und
• Anordnen eines digitalen Signals zwischen zwei aufeinanderfolgenden elektrischen Pulsen, wobei das digitale Signal einen ersten Digitalwert und einen zweiten Digitalwert umfasst, wobei der erste Digitalwert anzeigt, auf welche Zustandsgröße sich der zweite Digitalwert bezieht.

Furthermore, the invention comprises a method for generating an electrical signal from which a speed of a mechanical component can be derived, comprising:

• Detecting a rotational movement of the mechanical component by means of a sensor;
• Generating a series of electrical pulses, the spacing of which depends on the speed of rotation; and
• Arranging a digital signal between two successive electrical pulses, the digital signal comprising a first digital value and a second digital value, the first digital value indicating the state variable to which the second digital value relates.

As described above, the second digital value can relate to an ambient condition measurement value that is used on the receiver side to correct the rotational speed and / or to collect diagnostic data with regard to the sensor.

Preferably, digital signals are arranged between the two successive electrical pulses which embody a first digital value and a second digital value, the first digital value indicating that the second digital value transports an ambient condition signal, for example a temperature signal.

As described above, this enables the environmental condition signals to be sent alternately with other signals and to indicate which measured variables are transmitted with the second digital value or to activate and deactivate the transmission of the environmental condition signals (during operation).

The method preferably further comprises comparing the ambient condition measured values with a provided operating range, the second digital value indicating whether and / or how much the ambient conditions are outside or above the intended operating range.

As described above, the second digital value can, for example, indicate that the temperature has reached a maximum intended operating temperature or has exceeded this by 10 ° C. or 30 ° C.

A constant number of data bits is preferably arranged between each two consecutive electrical pulses, a first part of the data bits indicating which information is transmitted in a second part of the data bits.

As described above, the signal generation unit can alternately and / or as required provide environmental condition information such as temperature information, air gap information or sensor mode information and / or (possibly freely definable) additional information in the pulse pauses, the transmitted information being output, for example, by predefined bit sequences.

Preferably, the method further comprises increasing a frequency or duration with which environmental condition measured values are transmitted in the second part of the data bits if the environmental condition is outside or above the intended operating range.

For example, you can start sending temperature data when the temperature reading is above a certain value, or the temperature reading can be sent more frequently when the temperature reading is above a certain value, for example, to provide the temperature profile in a finer resolution / smaller time intervals.

Furthermore, it goes without saying that all features and advantages (preferred embodiments) of the device according to the invention can also be features and advantages (preferred embodiments) of the method according to the invention, which relates to a (possible) use of the device according to the invention.

• 1 ein Blockschaltbild einer erfindungsgemäßen Vorrichtung;
• 2 eine mögliche Ausgestaltung des Datensignals; und
• 3 ein Flussdiagramm eines erfindungsgemäßen Verfahrens zeigt.

The invention is explained below in the detailed description using exemplary embodiments, reference being made to drawing figures in which:

• 1 a block diagram of a device according to the invention;
• 2 a possible embodiment of the data signal; and
• 3 shows a flow diagram of a method according to the invention.

The same and functionally similar elements are identified by the same reference symbols in the drawing figures. However, it should be understood that not necessarily all elements are shown in all drawing figures and that the elements shown are only intended to illustrate aspects of the invention.

1 shows a device 10 for generating an electrical signal 12 from which a speed 14th of a mechanical component 16 (For example, a shaft or a wheel coupled to the shaft) can be derived. The device 10 includes a measuring unit 18th that are used to detect the rotational movement of the mechanical component 16 is set up. This is the mechanical component 16 with a pole ring 20th coupled, whose poles are in 1 are indicated schematically by the letters N and S. When the component rotates 16 the differently magnetized poles alternately pass through a Hall-effect sensor 22nd , which detects the alternating magnetic field generated by the pole movement and a sinusoidal signal corresponding to the alternating field 24 generated.

The sinusoidal signal 24 is from a signal generation unit 26th , which can be designed, for example, as an electronic control unit (ECU), scanned and the signal generation unit 26th generated at every zero crossing of the sinusoidal signal 24 a current pulse 28 so that during one full revolution of the pole ring 20th Current pulses 28 be generated. The speed can thus be determined by the fact that the between two current pulses 28 The elapsing time period Δt is multiplied by the number of current pulses that occur during a full revolution and the reverse fraction of the result is formed. It goes without saying that the signal generation unit 26th also less or (especially with a pole ring 20th with more poles) more current pulses 28 generate per revolution and the present disclosure in no way refers to the in 1 Shown embodiment is limited.

The signal generation unit generates in the pulse pause 26th a digital signal 30th , where in 1 between two current pulses 28 the digital signal, which is formed by a data word with a word length of 9 bits (which are identified by the numbers 0-8), is arranged or transmitted. As in 2 shown, the high level of the digital signal 30th be lower (e.g. half as large) than the level of the current pulses 28 . This enables the digital signal 30th (or the level of the digital signal 30th ) from the levels of the current pulses 28 to distinguish. It goes without saying, however, that a distinction is made between the current pulses 28 and the digital signal 30th can also take place by means of pulse durations of different lengths or by means of other mechanisms and the present disclosure does not apply in this regard to the in 2 embodiment shown is limited.

Additional information on the speed pulses can be provided by means of the data word 28 be transmitted. For example, bit number 0 can be used to indicate an error or an air gap reserve. Bit number 4 can also be used to determine the direction of rotation (positive, negative) of the pole ring 20th and bit number 3 can be used to indicate whether the direction of rotation is valid. Bits numbers 5, 6 and 7 can also be used to provide temperature and air gap information, information about a channel mode and information about special events. Bit number 8 can also be used as a parity bit. It goes without saying, however, that this assignment represents only one possible embodiment and the aforementioned information / data can also be assigned to other bits. The information about a channel mode can relate to information about an installation position of the rotation rate sensor. This information is stored in an electronic control unit after the rotation rate sensor has been installed. If the installation position changes due to vibration, shock or temperature effects, which can also cause the rotation rate sensor to rotate, the electronic control unit, which receives the transmitted data words from the rotation rate sensor, immediately recognizes that the installation position has and can be changed compared to the delivery state react accordingly. Exceeding a critical temperature value, eg 210 ° C or 220 ° C, is mentioned as an example of a special event. Several different special events can be specified by bit coding. The data word that is between the current pulses 28 is preferably Manchester encoded. A "high" signal is marked with a rising signal edge and a "low" signal is marked accordingly with a falling edge. This Manchester coding has the advantage that the signal can be evaluated exactly without an external synchronization signal. It is therefore self-synchronizing. The data word is preferably even coded with a differential Manchester code.

To determine the temperature information, the device includes 10 a temperature measuring unit 32 that are used to measure the temperature, which is the unit of measurement 18th is exposed, is set up. The temperature measuring unit 32 can, for example, have a temperature sensor which, as in 1 shown schematically on the housing of the measuring unit 18th or in the measuring unit 18th is integrated. From the through the temperature measuring unit 32 determined temperature value can from the signal generation unit 26th a temperature level can be derived which indicates the range in which the temperature value lies. For example, a first temperature level can indicate that the temperature value is in the operating range, that is to say, in particular, does not exceed a predetermined maximum temperature value. In addition, other temperature levels can show how much the temperature value is above the specified maximum temperature value. It should be noted that the temperature can also be measured indirectly. Here it would be possible to measure the voltage on a diode path, which is temperature-dependent. It is then not necessary to provide a separate temperature sensor.

The signal generation unit 26th can also be set up to select the information that is transmitted by means of the data word according to a configuration data record and possibly during the runtime (ie during the device 10 in productive operation). For example, the signal generation unit 26th by means of the digital value 34 indicate what information is provided by the digital value 36 is embodied. This means that different information can be transmitted in successive data words. For example, information derived from the measured temperature can be transmitted in a data word and other additional information can be transmitted in a subsequent data word (instead of the information derived from the temperature).

In addition, the frequency with which certain additional information is generated by the signal generation unit 26th is transmitted, can be adjusted according to the expected relevance of the additional information during the runtime. For example, the signal generation unit 26th be set up to transmit only the values that lie outside an expected range or to increase the frequency with which these values are provided in order to enable or simplify tracking of the values, for example for diagnostic purposes.

For example, it can be provided that certain information is not provided in normal operation. If, on the other hand, a deviation from normal operation is detected during operation (the reason for which can possibly be derived from the information), the information can be provided with a first frequency which is greater than zero. In addition, it can be provided that the information is provided at a second frequency, which is higher than the first frequency, when the relevance of the information increases.

In one embodiment it can be provided that the temperature information is not provided as long as the temperature value is below a permissible maximum value. If the temperature value exceeds the maximum value, can started to provide the temperature information. If the temperature rises further, the frequency with which the temperature information is provided can be increased further in order to increase the resolution / the time intervals of the temperature profile information.

Event information can be output when a critical temperature value is reached. This is done in such a way that the first digital value signals the temperature warning message. The second digital value can indicate the measured temperature or the exceeded temperature limit.

3 illustrates the operation of the device 10 . This starts with step 38 with the detection of the rotational movement of the mechanical component 16 by means of the sensor 22nd . For example, the component can 16 be a shaft coupled to a wheel of a vehicle and the device can be configured to provide a wheel speed. After in step 40 the temperature which the sensor 22nd is exposed, is measured, is in step 42 the rotational movement is converted into a series of electrical pulses, the distance between which depends on the speed of rotation, and at step 44 a digital signal derived from the measured temperature between two consecutive electrical pulses 28 arranged. The digital signal derived from the temperature can be arranged according to a (configurable) pattern or as a function of a state of the device 10 so that the available data word width is dynamically assigned to the additional information to be transmitted. If the program loop has been run through once from start to finish, it can start again at start.

In the simplest case, the bit rate with which the data bits are transmitted between the current pulses can be fixed. E.g. each bit can be transmitted every 50 µs. Then the evaluation of the data word on the receiver side is not dependent on the speed.

List of reference symbols

10

contraption

12

signal

14th

rotational speed

16

Component

18th

Measuring unit (rotational movement)

20th

Pole ring

22nd

sensor

24

signal

26th

Signal generation unit

28

Pulse

30th

digital signal (data word)

32

Temperature measuring unit

34

Digital value

36

Digital value

38

Process step

40

Process step

42

Process step

44

Process step

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 9825148 A2 [0002]
• WO 9809173 A1 [0003]
• DE 19911774 A1 [0004]
• DE 19634714 A1 [0005]
• WO 02/090999 A1 [0006]

Claims (12)

Device (10) for generating an electrical signal (12) from which a speed (14) of a mechanical component (16) can be derived, comprising: a measuring unit (18), set up to detect a rotational movement of the mechanical component (16); and a signal generation unit (26) configured to generate an output signal (12); wherein the output signal (12) comprises a sequence of electrical pulses (28), the spacing (Δt) of which changes with the speed of rotation, and wherein the signal generating unit (26) is set up to generate a digital signal (30) between two electrical pulses (28) to be arranged, characterized in that the signal generation unit (26) is set up to insert a first digital value (34) and a second digital value (36) in the digital signal (30), the first digital value (34) indicating which state variable the second digital value (36) relates. Device (10) after Claim 1 , wherein the first digital value (34) indicates that the state variable of the second digital value (36) relates to an environmental condition measured value information, in particular temperature information or air gap information, mode information or a special event. Device (10) after Claim 2 , wherein the signal generation unit or a control device (26) is set up to check whether an environmental condition measured value is in an intended operating range and the second digital value (36) represents the environmental condition measured value or whether and / or how strong the environmental condition measured value is is outside or above the intended operating range. Device (10) according to one of the Claims 1 to 3 , wherein the output signal (12) between two consecutive electrical pulses (28) has a constant number of data bits (0-8), a first part (1, 2) of the data bits (0-8) indicating which information is in a second part (5-7) of the data bits (0-8) is transmitted, and the signal generation unit (26) is preferably set up to select the information to be transmitted during operation on the basis of the state of the device (10). Device (10) after Claim 4 , wherein the signal generation unit (26) is set up to increase a frequency with which the environmental condition measured values are transmitted in the second part (5-7) of the data bits (0-8) when an environmental condition to which the measuring unit is exposed, is outside or above the intended operating range. A method for generating an electrical signal (12) from which a speed (14) of a mechanical component (16) can be derived, comprising: detecting (38) a rotational movement of the mechanical component (16) by means of a sensor (22); Generating a series of electrical pulses (28), the spacing (Δt) of which depends on the speed of rotation; and placing (44) a digital signal (30) between two successive electrical pulses (28); characterized in that the step of arranging (44) the digital signal (30) comprises arranging a first digital value (34) and a second digital value (36) in the digital signal, the first digital value (34) indicating which state variable the second digital value (36) relates. Procedure according to Claim 6 , wherein the first digital value (34) indicates that the second digital value (36) relates to an ambient condition measured value information, in particular temperature information, air gap information, mode information or a special event. Procedure according to Claim 6 or 7th , further comprising: matching of ambient condition measured values, in particular temperature measured values or air gap measured values, with an intended operating range; wherein the second digital value (36) represents the environmental condition measurement value or indicates whether and / or how much an environmental condition measurement value to which the sensor (22) is exposed is outside or above the intended operating range. Method according to one of the Claims 6 to 8th , a constant number of data bits (0-8) being arranged between two consecutive electrical pulses (28), a first part (1, 2) of the data bits (0-8) indicating which information is in a second part (5 -7) of the data bits (0-8) is transmitted. Procedure according to Claim 9 , further comprising: increasing a frequency at which the environmental condition measurements are transmitted when the environmental condition is outside or above the intended operating range. Method according to one of the Claims 6 to 10 , further comprising: storing the second digital value (36) in an error memory when the second digital value (36) indicates that a temperature to which the sensor is exposed is outside or above its intended operating range. Vehicle, in particular a commercial vehicle, with a device (10) according to one of the Claims 1 to 5 , particularly suitable for performing a method according to one of the Claims 6 to 10 .

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