WO2021013542A1 - Rotation sensor and vehicle - Google Patents

Abstract

The invention relates to a rotation sensor for generating an electrical output signal (12) from which a rotational speed (14) of a mechanical component (16) can be deduced. The rotation sensor is shown in the drawings as a wheel speed sensor (20). The rotation sensor is provided with a sensor unit (12) which has a plurality of sensor elements for detecting a rotational movement of the mechanical component (19, 21). The rotation sensor contains an electronic evaluation unit (15) which is designed to evaluate the signals supplied by the sensor elements of the sensor unit (12) and to generate the electrical output signal. The electronic evaluation unit (15) is designed to perform a calibration of the rotation sensor when the rotation sensor (20) is switched on for the first time. Furthermore, the electronic evaluation unit (15) is designed to store the calibration information in a non-volatile memory (17) and, when the rotation sensor is switched on again, to read the information stored there in order to enable a quick start whilst avoiding a further calibration phase during switch-on. The rotation sensor can have three Hall effect elements which are arranged in the form of a triangle, so that no specific orientation about the sensor axis has to be maintained during the installation.

Description

Rotation sensor as well as vehicle

The present invention relates to a rotation sensor. The

The invention also relates to a correspondingly adapted vehicle.

Rotation sensors are used in vehicle technology in the form of

Wheel speed sensors are used to measure the rotational movement, in particular of the wheels of the vehicle. Such sensors were first developed for use in braking systems with anti-lock braking systems (ABS). Initially, the wheel speed sensors were passive sensors (inductive sensors) that were equipped with a coil and a magnet. The rotational movement of an incremental wheel passing close to the wheel speed sensor periodically resulted in a

Magnetic field change that induced a voltage in the coil. However, such inductive wheel speed sensors have the problem that they only emit an evaluable signal from a certain wheel speed. With them, the signal amplitude depends on the wheel speed (frequency) and the

Expansion of the air gap between the wheel speed sensor and the incremental wheel. These disadvantages led to the development of active sensors that record the rotary movement with Hall sensors, but whose signals have to be processed in their own evaluation electronics. The Flall sensor works according to the Hall principle and has the special feature that it is also possible to detect the direction of rotation. Formally it can be active and passive

Differentiate between wheel speed sensors as follows: If a sensor is only "activated" by applying a supply voltage and then generates a

Output signal, this sensor is referred to as "active". If a sensor works without an additional supply voltage, this sensor is referred to as "passive"

The wheel speed information is sent from the control unit (usually the brake control unit) to which the wheel speed sensors are connected directly are also via a vehicle bus, e.g. via CAN bus to others

Transfer control units, such as transmission and engine control units,

Navigation systems, tire pressure monitoring systems and chassis control systems.

The fall sensors typically generate a sinusoidal signal whose frequency 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, between the pulses (i.e. in the pulse pauses)

Additional information is transmitted. Thus, for example, WO 98/25148 A2 teaches transmitting 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 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 power source that has a

Rotational behavior representing, supplies impressed current, known. The

Arrangement also comprises a modulator, which controls the power source as a function of signals from the sensor element and signals that an external signal source supplies via an additional connection, and a

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.

A sensor arrangement for detecting movements is known from DE 199 1 1 774 A1, in which a sensor signal is generated in an active sensor by an encoder acted upon by the movement. The

The sensor arrangement has a first device with which the sensor signal, together with at least one piece of additional information, is transferred to a

Evaluation device transmittable output signal is converted, wherein a second device is provided with which one of an air gap between the active sensor and the encoder-dependent signal voltage is detected and fed to the first device for transmission as additional information.

Today's wheel speed sensors contain several Hall sensors that are arranged in different geometries. There are wheel speed sensors in which 3 Hall sensors are arranged in a straight line one after the other. The wheel speed sensors can work in different channel modes. Two Hall sensors are always selected, and their output signals are used to generate a differential signal. The channel modes differ in the output signals between which the difference signal is formed. Other wheel speed sensors include 3 Hall sensors in the form of a

equilateral triangle. The wheel speed sensors with the Hall sensors in a straight line must be mounted with a defined orientation to the increment wheel so that they work properly. This is not necessary for wheel speed sensors with a triangular arrangement of the Hall sensors. However, they also need a calibration phase in which they evaluate a number of pulses before determining which two Hall sensors they can work best with.

With the known wheel speed sensors, there is thus the problem that an immediate channel mode determination is not possible. At least 4 to 5 signal phases must be waited for before a definition is possible.

Even if it is the start-up phase, this can easily amount to 1 ms or, in terms of distance, for 19 “wheels a distance of approx. 15 cm. This can be problematic for driver warnings when the vehicle is parked close to an obstacle and the driver has engaged forward gear instead of reverse gear or vice versa and is driving off.

There is thus a need for improved wheel speed detection or for improved wheel speed sensors.

The object of the invention is therefore to specify a rotation sensor with improved starting properties. This object is achieved by a rotation sensor according to claim 1 and a vehicle according to claim 8.

The dependent claims contain advantageous developments and

Improvements of the invention as described below for these measures.

In one variant, the invention relates to a rotation sensor for generating an electrical output signal from which a rotational speed of a mechanical component can be derived. This rotation sensor comprises a sensor unit, with a number of sensor elements, which is set up to detect a rotational movement of the mechanical component, and evaluation electronics which are set up to evaluate the

Sensor elements of the sensor unit delivered signals and for generating the electrical output signal. The rotation sensor is characterized in that the evaluation electronics are set up to store the calibration information in a non-volatile memory and to read it out when the rotation sensor is switched on again in order to enable a quick start while avoiding another calibration phase when the rotation sensor is switched on. This solution offers the advantage that the rotation sensor can be started quickly. It does not have to be switched on every time

Calibration phase are waited until the rotation sensor the

Supplies output signals to the connected control units. This is for various applications where there is immediate control of the

Rotary motion detection is an advantage. It can

Output signal be designed so that it has a sequence of electrical pulses, the spacing of which changes with the speed of rotation.

An advantageous embodiment provides that the evaluation electronics are set up to detect the installation position of the rotation sensor in the calibration phase by evaluating the signals from the various sensor elements. This can be done by evaluating the position of the signals of the sensor elements to one another, in particular the phase position of the signals. Is the

If the installation position is known, the direction of rotation can be detected more quickly. It is also advantageous if the sensor unit has three sensor elements which are arranged in the form of a triangle on the sensor unit. This offers the advantage that the rotation sensor can be operated in different installation positions. Depending on the installation position, another sensor element or two other sensor elements can be used to detect the rotary movement.

A particularly advantageous variant provides that the triangle has the shape of an equilateral triangle. This achieves a rotational symmetry about the axis of the floch that is perpendicular to the surface of the triangle. If the rotation sensor is rotated along this axis of rotation, a good evaluation of the signals from the sensor elements can still take place.

It is also advantageous if the evaluation electronics of the rotation sensor are set up for the calibration phase during operation of the

Rotation sensor to perform again and to write the calibration information in the non-volatile memory, if it has been recognized that the newly determined calibration information deviates from the calibration information entered in the non-volatile memory. This measure ensures that, despite the fact that the recalibration is not carried out, each time the rotation sensor is restarted, a check is carried out to determine whether the installation position of the

Rotation sensor has changed. If a change is detected, it is saved and is taken into account at every restart by reading out this information.

A significant area of application for the improved rotation sensors are wheel speed sensors, which are intended to detect the rotational movement of the wheels of vehicles. For such a wheel speed sensor, it is advantageous if the sensor unit has, as sensor elements, fall sensors that respond to the changes in the magnetic field that arise when an incremental wheel or pole ring rotates that is rigidly connected to a wheel.

In this field of application, it is advantageous if the wheel speed sensor is connected to an electronic control unit to which the output signal is sent is transmitted via a signal line. It can be, for example

Acting brake control unit of a vehicle.

Another implementation of the invention consists in a vehicle, in particular a utility vehicle, which is equipped with an inventive

Wheel speed sensor. In particular be

Wheel speed sensors are used in vehicles for which there is even

It is relevant to safety that they are designed to be able to start quickly.

Embodiments of the invention are shown in the drawings and are explained in more detail below with reference to the figures. The rotation sensors described are shown in the form of wheel speed sensors.

Show it:

1 shows a vehicle which is equipped with wheel speed sensors according to the proposal;

2 shows the use of the improved speed sensor in combination with an incremental wheel;

3 shows the use of the improved speed sensor in combination with a multipole ring; and

4 is a block diagram of the improved wheel speed sensor.

The present description illustrates the principles of

disclosure according to the invention. It is therefore understood that those skilled in the art will be able to design various arrangements which, although not explicitly described here, embody principles of the disclosure according to the invention and are also intended to be protected in their scope.

Fig. 1 shows a vehicle 10 with a proposed device. The vehicle shown is a passenger car with a regulated brake system in the manner of an ABS brake system. Such braking systems are also used for other vehicles, such as commercial vehicles, trailers, buses, camping vehicles, Construction vehicles, motorcycles, etc. are used. The wheel speed sensors for the wheels of the vehicle 10 are designated by the reference number 20. One wheel speed sensor 20 is mounted per wheel. Numeral 40 is a

Brake control unit called. It regulates the brake pressure in the individual wheel brake cylinders in order to prevent the wheels from locking during the braking process. The wheel brake cylinders and the corresponding lines (hydraulic or pneumatic in commercial vehicles) are not shown separately. Each wheel speed sensor 20 is connected to control unit 40 via its own signal line 25.

2 shows the basic mode of operation of the wheel speed sensor 20. In the case shown, it works together with an incremental wheel 19, which is rigidly connected to the wheel or its drive shaft whose rotational movement is to be detected. The wheel speed sensor 20 is directly above the

Increment wheel 19 attached. The wheel speed sensor 20 is designed as an active wheel speed sensor 20 and consists essentially of FIG

Components. A sensor unit in which one or more

Sensor elements are arranged. Examples of such sensor elements are magnetic field sensors, in particular fall sensors or magnetoresistive resistors. However, other sensor elements could also be used, such as inductive sensors or optical sensors. The other

the essential component relates to evaluation electronics. This is then also connected to the signal line 25. In the simplest case there is

Signal line from a two-wire line which on the one hand transmits the generated pulses to the connected brake control device 40 and on the other hand is also responsible for the supply of the supply voltage V _C c and derivation to ground GND. In an expanded embodiment, a third line can also be added, via which data can also be transmitted to the wheel speed sensor. This can be used to configure the

Wheel speed sensor 20 be interesting. The increment wheel 19 is preferably made of metal and has a number of teeth. For example, 100 teeth could be formed on the outer circumference. A permanent magnet is attached to the sensor unit, whose magnetic effect extends to the incremental wheel 19 reaches. The rotary movement of the incremental wheel 19 and the associated change of tooth and tooth gap causes a change in the magnetic flux through the sensor unit. This changing

Magnetic field generates a measurable alternating voltage in the sensor elements. The frequency and amplitude of this alternating voltage are related to the wheel speed.

3 shows a second embodiment in which a wheel speed sensor 20 is used, which works together with a pole ring 21 instead of with the incremental wheel 19. The pole ring 21 is also rigidly connected to the wheel or its drive shaft. The pole ring 21 is typically used in a sealing ring of a wheel bearing. The alternating magnetized zones are marked with the magnetic poles N, S. The fall sensors arranged in the sensor unit detect a changing magnetic field when the multi-pole ring is rotated. This sinusoidal signal is converted into a digital signal by the evaluation electronics in the sensor. The transfer to

The control unit takes the form of a current signal using the pulse width modulation method. The sensor signal is transmitted simultaneously via the power supply line

transmitted. The other line serves as a sensor ground. The Flall sensors have the advantage that they allow larger air gaps and the smallest

Changes in the magnetic field respond. It is not with this variant

it is necessary to attach a permanent magnet to the sensor unit.

4 shows a more detailed structure of the wheel speed sensor 20. As mentioned, the wheel speed sensor 20 comprises a sensor unit 12 which is set up to detect the rotational movement of the incremental wheel 19 or the pole ring 21. In the example shown there are 3 fall sensors 12A, 12B,

12C arranged in a triangular shape on the sensor unit 12. The signals from the fall sensors 12A, 12B, 12C are processed separately and sent to the

Evaluation electronics 15 out. Each signal is first amplified in an amplifier 13 and sampled and digitized in an A / D converter 14. The evaluation electronics 15 process the digitized sinusoidal signal. The evaluation electronics 15 can, for example, as a microchip with digital controller and Be formed memory. Reference number 17 denotes a non-volatile memory, which is preferably implemented as an EEPROM memory. Alternatively, the evaluation electronics 15 can also be designed as an FPGA or ASIC circuit. Numeral 16 denotes a temperature sensor. The ambient temperature of the wheel speed sensor 20 is thus recorded. The evaluation electronics 15 evaluate the signals from the individual Hall sensors 12A,

12B, 12C off. The type of evaluation will be explained in more detail later. Finally, a PWM signal is generated on a digital level, in which digital codes according to the AK protocol are nested between two speed pulses. This digital signal goes to a signal generator 18, which generates currents according to the AK protocol, via the two

Supply lines V _C c and GND to the connected

Brake control device 40 are transmitted. The AK protocol provides that a quiescent current of 7 mA flows on these lines. For one

According to the AK protocol, a current of 28 mA is provided for the speed pulse, a current of 14 mA is defined for the transmission of the digital code. The signal generator 18 generates an electrical pulse at each zero crossing of the sinusoidal signal, so that during one full revolution of the

Increment wheel 19 or the pole ring 21 a large number of electrical pulses is generated. In a variant, which was designed for commercial vehicles, the pole ring 21 can, for example, generate 200 electrical pulses per wheel rotation. The speed can thus be determined by multiplying the time period At between two electrical pulses 32 by the number of electrical pulses that occur during a full wheel revolution and forming the reversal fraction of the result.

It goes without saying that less or (especially with a

Pole ring 21 with more poles) more electrical pulses can be generated per revolution and the present disclosure is in no way limited in this regard to the exemplary embodiments shown in FIGS. 2 and 3.

The three Hall sensors 12A, 12B, 12C are in the form of an equilateral

Arranged in a triangle. The sensor unit 12 is flat and the The wheel speed sensor 20 is mounted on the respective wheel in such a way that when the incremental wheel 19 or the pole ring 21 rotates, the sensor unit 12 is flooded with the changing magnetic field as much as possible. When the pole ring 21 rotates, the differently magnetized poles alternately pass the Hall sensors 12A, 12B, 12C, which detect the alternating magnetic field generated by the pole movement and generate a sinusoidal signal 23 corresponding to the alternating field. This principle also applies when the incremental wheel 19 is used. An air gap remains between the pole ring 21 and the sensor unit 12. The air gap between

Sensor unit 12 and pole ring 19, or incremental wheel 21, is not necessarily permanently set. In a preferred variant, the wheel speed sensor 20 is plugged into a clamping socket. The wheel speed sensor 20 is then from the pole ring 19 by the wobble during the rotational movement in the

The clamping sleeve is pushed back and the air gap is set automatically.

The triangular arrangement of the Hall sensors 12A, 12B, 12C on the sensor unit 12 offers the advantage that they can be inserted into the clamping sleeve of the wheel bearing housing without any specific orientation. An evaluation algorithm runs in the evaluation electronics 15, which determines which two Hall sensors 12A, 12B, 12C have the best signals for the

Deliver evaluation. A difference signal is then formed between these, so that any interference signals are canceled out. It takes up to 5 pulses to find out the installation position of the wheel speed sensor 20. Only then is the direction of rotation known in which the wheel is turning. Because this evaluation must take place each time the wheel speed sensor 20 is switched on, the direction of rotation cannot easily be determined earlier.

In order to solve this problem, according to the invention the installation position of the wheel speed sensor 20 recognized after the first switch-on is stored in the non-volatile memory 17. In the following

This information is then directly in the switch-on processes

Evaluation electronics 15 available. When the wheel speed sensor 20 with When voltage is supplied, the information is read out from the non-volatile memory 17 and the first pulses are sent as

Speed pulses output with correct direction of rotation. The

The direction of rotation can be recognized by the shape of the pulses that are generated. The signals from the wheel speed sensors 20 can thus be taken into account earlier by the various control units. The algorithm for determining the installation position of the

Wheel speed sensor 20 is often repeated to determine any changes in the installation position. If a change is detected, the new installation position is written into the non-volatile memory 17. This ensures that the correct installation position is always saved when the ignition is switched on. Experience has shown that the installation position is typically changed during ongoing operation, due to vibration or the wobble of the incremental wheel 19 or of the pole ring 21.

All examples mentioned herein as well as conditional formulations are to be understood without restriction to such specifically cited examples. For example, it is recognized by those skilled in the art that what is presented here

Block diagram is a conceptual view of an exemplary

Represents circuit arrangement. In a similar way, it can be seen that a depicted flowchart, state transition diagram, pseudocode and the like represent different variants for the representation of processes that can essentially be stored in computer-readable media and thus executed by a computer or processor.

It should be understood that the proposed method and associated devices can be implemented in various forms of flardware, software, firmware, special purpose processors, or a combination thereof. Specialty processors can include application-specific integrated circuits (ASICs), reduced instruction set computers (RISC), and / or field programmable gate arrays (FPGAs). The proposed method and the device are preferably used as a combination of Hardware and software implemented. The software is preferably installed as an application program on a program storage device.

Typically it is a machine based on a

A computer platform comprising hardware such as one or more central processing units (CPU), random access memory (RAM), and one or more input / output (I / O) interfaces. On the

An operating system is typically also installed on the computer platform. The various processes and functions described here can be part of the application program or a part that is executed by the operating system.

The disclosure is not restricted to the exemplary embodiments described here. There is room for various adaptations and modifications which those skilled in the art, based on their expert knowledge as well as belonging to the disclosure, would consider. The described

Wheel speed sensors can also be used on various other rotating parts to detect speed.

List of reference symbols (part of the description)

10 vehicle

12 sensor unit

12A 1. Hall sensor

12B 2nd Hall sensor

12C 3. Hall sensor

13 amplifier

14 analog / digital converter

15 Evaluation electronics

16 temperature sensor

17 EEPROM

18 signal generator

19 increment wheel

20 wheel speed sensor

21 pole ring

25 signal line

40 brake control unit

Claims

Expectations 1. Rotation sensor for generating an electrical output signal (12), from which a speed (14) and a direction of rotation of a mechanical component (19, 21) can be derived, comprising: a sensor unit (12), with a number of sensor elements, set up to detect a rotational movement of the mechanical component (19, 21); an evaluation electronics (15), set up to evaluate the from the Signals supplied to sensor elements of the sensor unit (12) and for generating the electrical output signal; the evaluation electronics (15) being designed to calibrate the rotation sensor when the Make rotation sensor, characterized in that the evaluation electronics (15) are set up to store the calibration information in a non-volatile memory (17) and to read it out when the rotation sensor is switched on again in order to enable a quick start while avoiding another calibration phase when switching on. 2. Rotation sensor according to claim 1, wherein the evaluation electronics (15) are set up to detect the installation position of the rotation sensor in the calibration phase by evaluating the signals from the sensor elements. 3. Rotation sensor according to claim 2, wherein the sensor unit (12) has three sensor elements which are arranged in the form of a triangle on the sensor unit (12). 4. The rotation sensor according to claim 3, wherein the triangle has the shape of an equilateral triangle. 5. Rotation sensor according to one of the preceding claims, wherein the evaluation electronics (15) is set up the calibration phase on the fly Operation of the rotation sensor again and the To write calibration information in the non-volatile memory (17) when it has been recognized that the newly determined calibration information deviates from the calibration information entered in the non-volatile memory (17). 6. Rotation sensor according to one of the preceding claims, wherein the rotation sensor is set up as a wheel speed sensor (20) with a Sensor unit (12) which has Hall sensors (12A, 12B, 12C) as sensor elements that respond to the changes in the magnetic field that arise when an incremental wheel (19) or pole ring (21) that is rigidly connected to a wheel rotates. 7. wheel speed sensor (20) according to claim 6, wherein an electronic control unit (40) is connected to the device (20), to which the Output signal is transmitted via a signal line (25). 8. The vehicle (10), in particular a commercial vehicle, equipped with at least one wheel speed sensor (20) according to claim 6 or 7.