DE102017109531B3 - Sensor arrangement and method for generating a position change signal sequence - Google Patents

Abstract

The invention relates to a sensor arrangement and a method for generating a position change signal sequence comprising such a sensor arrangement, comprising: a multipole encoder (02) comprising a plurality of mutually adjacent pole pairs (03) providing a scanning plane (04) with magnetic poles alternating in a scanning direction, and a Magnetic field sensor (01), which generates a first output voltage in response to a vertical component of an external magnetic field, a second output voltage in response to a horizontal component of the external magnetic field and a third output voltage in response to a horizontal component of the magnetic field. In order to generate a higher number of pulses without having to increase the number of pole pairs on Multipole encoder (02) to the same extent, the magnetic pole pairs (03) of the Multipolencoders (02) and the magnetic field sensor (01) are rotated to each other that the horizontal field strength x 'output voltage (08) and a y' output voltage (09) are generated, which have a substantially equal amplitude. At each zero crossing of the first output voltage z '(07), the x'-output voltage (08) and the y'-output voltage (09), and at each equality of the first output voltage (07) and x'-output voltage (08) or y 'output voltage (09), a switching signal pulse of the position change signal sequence (10) is output.

Description

The present invention relates to a sensor arrangement for generating a position change signal sequence, which comprises a Multipolencoder and a magnetic field sensor, and a method for generating a position change signal sequence.

The multipole encoder provides a scanning plane formed of a plurality of magnetic poles consecutive in a scanning direction. The Multipolencoder consists of several mutually adjacent pole pairs, wherein the magnetic field alignment of each successive pole pairs alternates. The magnetic field sensor, hereinafter also referred to as a sensor, has a sensor surface which is e.g. shows an anisotropic magnetoresistive effect. The sensor surface, or more specifically the sensitive surface, usually consists of a Wheatstone bridge with several magnetic field sensor elements. The person skilled in such magnetic field sensors and suitable materials are known. A preferred type of magnetic field sensor is an xMR (magnetoresistive) sensor. However, this is only an example, and the invention described below is not limited to this type of magnetic field sensor. Other suitable magnetic field sensors are Hall sensors, as well as combinations of several.

In order to be able to detect rotational or linear movements with the sensor arrangement, the multipole encoder is movable relative to the sensor in the scanning direction, during which movement the desired sensor signal is generated. During the relative movement, a magnetic field of alternating polarity, which is variable in the scanning direction and which is generated by the successive magnetic poles, passes through the sensor surface. The strength of this variable magnetic field in the scanning direction therefore shows a zero crossing at the transition between adjacent poles or pole centers. The position of the zero crossing depends on the scanning direction; In the y-direction, the zero crossing of the magnetic field is in Polmitte, in the z-direction is the zero crossing between the adjacent poles.

Numerous sensor arrangements are known from the prior art, which serve the non-contact detection of a relative movement between two machine parts. Such sensor arrangements are used, for example, in rotary bearings for detecting the rotational speed. At wheel bearings with such sensor arrangements, the rotational speeds of the vehicle wheels and therefrom the respective rotational speeds are determined. Magnetic sensing based sensor assemblies use magnetic encoded components, so-called multipole encoders, which have uniformly distributed magnetic poles along a scan plane with adjacent poles alternating in their magnetic field orientation such that a south pole follows a north pole in the scan plane followed by another in the scan direction North pole follows, etc. The field strength curve in the scanning direction thus has a zero crossing at the boundary lines between the adjacent poles or in Polmitte. The magnetic field of the Multipolencoders can be detected or scanned using different sensors. For example, Hall sensors are used. Likewise, the use of sensors is known that exploit the magnetoresistive effect. At each zero crossing in the magnetic field or in the electrical signal derived therefrom, a switching signal pulse or switching signal is generated at the output of the sensor, which has a digital (rectangular) shape, i. H. between two levels "High" and "Low" for a set period of time - pulse duration - changes. The resolution of such sensor / encoder arrangements is i.a. limited by the fact that the number of pole pairs of the Multipolencoders can not be increased arbitrarily, since the pole width and the magnetic signal strength that can be achieved thereby decreases in proportion to the number of pole pairs. Thus, only a limited number of pole pairs can be arranged along a given distance in the scanning direction, taking into account the desired magnetic signal strength. In conventional sensor arrangements, the number of pulses of the output signal of the sensor is thus limited by the possible number of pole pairs.

From the DE 10 2008 059 401 A1 a method is known in which the number of edges or pulses is increased by detection and evaluation of a plurality of phase-shifted components of the time-varying magnetic field. To achieve this, either one of the detected signals must be inverted or an additional magnetic field component must be detected. Inverting creates a dead time. The detection of a third magnetic field component is conceivable, but this is much too small compared to the other two components in conventional magnetization, so that the practical implementation fails.

Sensor arrangements with Multipolencodern and corresponding signal processing circuits are, for example, in DE 10 2013 000 432 A1 . DE 10 2013 000 430 A1 . DE 10 2012 201 348 A1 . DE 10 2012 202 404 A1 . DE 10 2015 115 247 A1 . DE 10 2007 000 440 A1 or US Pat. No. 7,140,258 B2 shown.

A method for increasing the number of switching signal pulses for improving the resolution is, for example, in DE 36 39 208 A1 shown.

Magnetic field sensors which can detect magnetic field components in three spatial directions are described, for example, in the data sheet TLV493D-A1B6 3D Magnetic Sensor, Infineon, 29.01.2016, URL: https://www.infineon.com/dgdl/Infineon-TLV493D-A1B6-DS- v01_00-EN.pdf? fileId = 5546d462525dbac40152a6b85c760e80 or the 3D Magnetic Sensor for Angle Measurement Application Note, Infineon, June 2016, URL: https://www.infineon.com/dgdl/Infineon-3D_AppNote_AngleMeasurement-AN-v01_00-EN.pdf? fileId = 5546d4625607bd13015607dbd576002b shown.

The present invention has for its object, based on the known non-contact detection of relative movements to provide a sensor array and to provide a method, which can achieve a higher pulse count, so that a higher spatial resolution of the sensor arrangement results, without the number of pole pairs at Multipolencoder in same degree must be increased. This should be achieved while maintaining the quality of the output signal.

This object is achieved by a sensor arrangement for generating a position change signal sequence according to claim 1 and a method for generating a position change signal sequence according to claim 9. Preferred embodiments of the invention are the subject of the respective subclaims.

The sensor arrangement comprises a multipole encoder with a scanning plane of a plurality of magnetic poles successive in a scanning direction. The successive poles are provided by juxtaposed pole pairs, which have alternating magnetic field alignments, so that in the scanning plane next to a north pole of a first Polpaares a south pole, which in turn is followed by a north pole of an adjacent pole pair, etc. Furthermore, the sensor arrangement comprises a magnetic field sensor. The multipole encoder is movable in the scanning direction relative to the sensor, so that in the relative movement of the sensor is exposed to a variable magnetic field with alternating polarity. The magnetic field sensor is designed such that it can detect all three spatial components of the magnetic field penetrating it and convert these into electrical signals for subsequent processing.

The number of usable pulses can be increased by including all three field components of the magnetic field and not just the major components in a horizontal and in a vertical direction. In order to achieve a usable signal strength in the sensor in all three directions, either the interfaces of the magnetization in the multipole encoder are rotated by 45 °, or the sensor or the sensitive measuring elements in the sensor are rotated by 45 °. This produces in the x and y direction of the sensor two magnitude equal magnetic field signals x ', y', which are calculated in conjunction with the z-component or the resulting third magnetic field signal z 'accordingly. The strength of the z 'component remains unchanged in this rotated arrangement.

The position change signal sequence in the output signal of the sensor is composed of switching signal pulses, which are generated at each zero crossing of the x'-output voltage, the y'-output voltage and the z'-output voltage, and switching signal pulses, which are generated when the x'- Output voltage is equal to the z'-output voltage and when the y'-output voltage is equal to the z'-output voltage.

The splitting of the horizontal magnetic field components into an x 'component and a y' component is achieved by turning the boundary lines between adjacent pole pairs of the multipole encoder to the scanning direction at an angle of 45 °. In this case, the sensor surface is aligned substantially parallel to the scanning plane of the multipole encoder, while the scanning direction y is perpendicular to the y-direction of the sensor.

Alternatively, the relative rotation between sensor and encoder can be achieved in that the magnetic field sensor or the sensitive measuring elements in the sensor housing to the scanning direction at an angle of 45 °, with rotation about the z-axis of the sensor is rotated. Analogous to the first alternative of relative rotation, the boundary lines between adjacent pole pairs of the multipole encoder with respect to the scanning direction y are aligned substantially vertically in this second possibility.

In other words, the operation of the invention can also be explained as follows: The sensor "sees" two magnetic field components x ', y' parallel to the scanning plane, either because the encoder generates them, in the case where the boundary lines of the Magnetization tilted, or because the encoder is designed conventionally and the sensor itself is arranged rotated relative to the scanning direction. In the latter case, therefore, no second magnetic field component x is generated by the encoder itself, this arises only in the sensor, since it is arranged rotated.

From the electrical signals of the sensor, a zero crossing or a comparable event is filtered out, based on which a switching signal for a counter o. The like. Derived. For this purpose, it is provided in one embodiment that the magnetic field sensor has a Signal processing circuit which generates a switching signal in response to a zero crossing of the z'-output voltage, a zero crossing of the x'-output voltage, a zero crossing of the y'-output voltage, a zero crossing of the difference of the x'-output voltage and the z'-output voltage and a zero crossing of the difference of the y 'output voltage and the z' output voltage. This results in a complete pole change of the Multipolencoder magnetic field eight switching signals.

The described sequence of switching signals can be evaluated in different ways. In a preferred embodiment, the evaluation consists in the signal processing circuit outputting a speed signal that depends on the speed of the relative movement between the magnetic field sensor and the multipole encoder. The speed signal consists of a sequence of digital (two-level) signal pulses whose time interval from each other (edge distance) is representative of the speed, ie the shorter the times, the greater the speed.

The selection of magnetic field sensors is not limited. Both Hall and xMR (magnetoresistive) sensors or a combination thereof can be used. Other sensor principles are also conceivable (for example, fluxgate). The decisive factor is the possibility of being able to record the three spatial components of the magnetic field simultaneously.

With the sensor arrangement can thus generate a position change signal sequence by switching signal pulses are generated at each zero crossing of the x'-output voltage or the y'-output voltage and the z'-output voltage, and switching signal pulses are generated when the x'-output voltage is equal to the z 'output voltage and when the y' output voltage is equal to the z 'output voltage. This results in a field reversal of the magnetic field, d. H. Passing through a pole pair on the sensor, a position change signal sequence of a total of eight switching signal pulses.

In order to recognize that the x'- or y'-output voltage is equal to the z'-output voltage, a first difference voltage between the z'-output voltage and the x'-output voltage and a second differential voltage between the z'- Output voltage and the y 'output voltage formed. The zero crossing of the first and the second differential voltage is detected and used to output a switching signal pulse.

• 1 eine vereinfachte perspektivische Ansicht einer ersten Ausführungsform der erfindungsgemäßen Sensoranordnung;
• 2 eine schematische Darstellung einer zweiten Ausführungsform der Sensoranordnung;
• 3 den Verlauf der einzelnen Ausgangssignale eines Magnetfeldsensors und die daraus abgeleiteten Schaltpunkte;
• 4 eine Signalverarbeitungsschaltung für die Sensoranordnung.

Further advantages, details and developments of the invention will become apparent from the following description of preferred embodiments, with reference to the drawing. Show it:

• 1 a simplified perspective view of a first embodiment of the sensor arrangement according to the invention;
• 2 a schematic representation of a second embodiment of the sensor arrangement;
• 3 the course of the individual output signals of a magnetic field sensor and the switching points derived therefrom;
• 4 a signal processing circuit for the sensor arrangement.

The drawing is not to scale. Identical or equivalent elements are provided with the same reference numerals, unless otherwise stated.

As far as is spoken in the following description of xMR sensors, this means no limitation to this sensor type, but only an example of a suitable magnetic field sensor. Other types of sensors can also be used.

1 shows in a highly simplified perspective view of the basic basic structure of a sensor arrangement. The sensor arrangement comprises a sensor 01 with integrated therein sensor elements that extend in a sensor surface. Furthermore, the sensor arrangement comprises a multipole encoder 02 , which is shown here in the form of an elongated band for the sake of simplicity. The multipole encoder 02 has numerous magnetic pole pairs 03 , which are arranged side by side with alternating magnetic field alignment. The resulting chain from the pole pairs 03 extends in a scanning direction y which shows the relative direction of movement between the sensor 01 and the multipole encoder 02 equivalent. The travel direction of the Multipolencoders 02 is by a dot-dashed center line along the juxtaposed pole pairs 03 clarified. For better classification of the respective directions also a coordinate system with the coordinates x, y, z is shown. A scanning plane 04 passing through the sensor facing surfaces of the pole pairs 03 is formed extends in the xy plane of the coordinate system. The forming between the adjacent pole pairs magnetic fields are characterized by the magnetic field lines 05 symbolizes.

A peculiarity of in 1 illustrated embodiment is that the borderlines 06 between each adjacent pole pairs 03 not perpendicular to the scanning direction y but at an angle of in this case preferred 45 °. This angle can be chosen differently in other embodiments.

2 shows an alternative constellation of the sensor 01 with respect to the encoder 02. In this constellation is the multipole encoder 02 with several pole pairs 03 whose boundary lines are parallel to each other and perpendicular to the scanning direction y are arranged. On the other hand, the sensor 01 with respect to the encoder 02 positioned at an angle of about 45 °. This ensures that the sensor 01 referred to its inner coordinate system, which was drawn for orientation in the vicinity of the sensor, is penetrated by a vertical component of the encoder magnetic field and also by two horizontal components of the external magnetic field, namely an x 'component and a y' component. Due to the orientation of the sensor at a 45 ° angle with respect to the encoder 02 , it is ensured that the two horizontal components of the magnetic field in the sensor are substantially equal, so that the x'- and y'-output voltages have a substantially equal large amplitude.

3 schematically shows the three output voltages of the sensor 01 , which are each generated by the three components of the encoder magnetic field in the sensor. A z 'output voltage 07 is generated in the diagram by the vertical z component of the external magnetic field, an x' output voltage 08 is generated by an x component of the external magnetic field, and a y 'output voltage 09 is represented by a y Component of the external magnetic field generated. Both by a corresponding sensor arrangement with respect to the Multipolencoder as well as by design of input amplifiers 11 ( 4 ) the amplitudes of the voltages are normalized to an equal value.

As a trigger for a switching signal are at the output voltages 07 . 08 . 09 each used the zero crossings. These zero crossings are shown as open circles on the zero line in the diagram. In addition, those events are also used as triggers for a switching signal in which the output voltage of one of the two horizontal components x ', y' is equal to the z 'output voltage generated by the vertical field strength component. These events are also shown as open circles off the zero line in the diagram. In each of these events, a switching signal is generated, so that a total of a position change signal sequence 10 of switching signals. For a complete pole change of the Multipolencoders 02 ie a complete pass of a pole pair 03 This results in eight switching signals compared to only two or four in the prior art.

A strictly periodic sequence of switching signal pulses results only when the amplitudes of the three output voltages are equal. Only then do the zero crossings or the events in which the x'- and y'-output voltages 08, 09 of one of the two horizontal components have the same size as the z'-output voltage 07 have the same distance from one another on the time axis. For this reason, as mentioned above, the three voltages are normalized to a same maximum value.

4 shows an embodiment of a signal processing circuit to select from the in 3 output voltages shown to produce the desired position change signal sequence 10. The evaluation circuit comprises an amplifier stage for signal processing 11 with three amplifier modules for the three output voltages 07, 08, 09. These amplifier modules ensure that the generated switching points occur at the same angular distance by the corresponding output voltages of the sensor 01 be brought to equal amplitudes. The output voltages processed in this way are compared with three comparators / Schmitt triggers 12 the respective zero crossing is determined. Furthermore, by means of two differential amplifier / subtractor 13 in each case a first differential voltage from the output voltage 07 and the output voltage 08 , ie z'-component minus x'-component, and a second differential voltage from the output voltage 07 and the output voltage 09 formed, ie z 'component minus y' component. For these two differential voltages, two other comparators / Schmitt triggers are used 12 likewise determines the respective zero crossing. Overall, this gives five zero crossing events, namely three zero crossings of the three output voltages and two zero crossings with equality of one of the horizontal output voltages 08 . 09 with the vertical output voltage 07 , These five zero crossing events will be in an XOR gate 14 merged and each trigger a switching signal. The resulting sequence 10 of switching signals is in 4 shown again right.

In the 4 Signal processing shown schematically is preferably integrated together with the measuring elements for the conversion of the three magnetic field components into electrical signals in the same housing of the magnetic field sensor in semiconductor construction.

The device according to the invention and the method according to the invention can both be applied to position change signal sequences which are generated by a rotation angle change of magnetic field encoder with respect to the magnetic field sensor, ie with rotating components, as well as position change signal sequences which are generated by moving magnetic field encoder with respect to magnetic field sensor over a distance, ie with linearly moving components.

LIST OF REFERENCE NUMBERS

01

magnetic field sensor

02

multipole

03

pole pairs

04

scan

05

magnetic field

06

boundary line

07

first output voltage

08

x output voltage

09

y output voltage

10

Position change signal sequence

11

amplifier stage

12

Comparator / Schmitt Trigger

13

Differential amplifier / subtractor

14

XOR gate

y

scan

Claims (8)

Sensor arrangement for generating a position change signal sequence, comprising: - A multipole encoder (02) of a plurality of mutually adjacent pole pairs (03), which provides a scanning plane (04) with in a scanning direction (y) alternating magnetic poles; a magnetic field sensor (01) which generates a z 'output voltage (07) as a function of a component of the magnetic field generated by the multipole encoder (02), which is perpendicular to the scanning plane (04), an x' output voltage (08) as a function of a first generated in parallel to the scanning plane (04) component and a y 'output voltage (09) in response to a second parallel to the scanning plane (04) acting component of the Multipolencoder (02) generated magnetic field; in which: - The magnetic pole pairs (03) of the Multipolencoders (02) and the magnetic field sensor (01) are rotated relative to each other, that of the magnetic field sensor (01) generated x'-output voltage (08) and y'-output voltage (09) have equal amplitudes , and a signal processing circuit is provided for: Outputting a switching signal pulse of the position change signal sequence (10) at each zero crossing of the x'-output voltage (08), the y'-output voltage (09) and the z'-output voltage (07), Outputting a switching signal pulse of the position change signal sequence (10) when the x'-output voltage (08) is equal to the z'-output voltage (07), and Outputting a switching signal pulse of the position change signal sequence (10) if the y 'output voltage (09) is the same as the z' output voltage (07). Sensor arrangement after Claim 1 , characterized in that the boundary lines (06) between adjacent pole pairs (03) of the Multipolencoders (02) to the scanning direction (y) are rotated at an angle of 45 °, and that the measuring elements of the magnetic field sensor (01) substantially parallel to the scanning plane ( 04) of the multipole encoder (02) are aligned, and that the scanning direction (y) is perpendicular to the y-direction of the measuring elements of the magnetic field sensor (01). Sensor arrangement after Claim 1 , characterized in that the measuring elements of the magnetic field sensor (01) are aligned substantially parallel to the scanning plane (04) of the Multipolencoders (02), and that the y-direction of the measuring elements of the magnetic field sensor (01) to the scanning direction (y) at an angle of 45 °, when rotated about the z-axis, are rotated, and that the boundary lines (06) between adjacent pole pairs (03) of the Multipolencoders (02) are aligned substantially perpendicular to the scanning direction (y). Sensor arrangement according to one of Claims 1 to 3 , characterized in that the magnetic field sensor (01) comprises the signal processing circuit which generates a switching signal in response to a zero crossing of the z 'output voltage (07), from a zero crossing of the x'-output voltage (08), a zero crossing of the y'- Output voltage (09), a zero crossing of the difference of the x'-output voltage (08) and the z'-output voltage (07) and a zero crossing of the difference of the y'-output voltage (09) and the z'-output voltage (07). Sensor arrangement according to one of Claims 1 to 4 , characterized in that the signal processing circuit outputs a speed signal which depends on the speed of the relative movement between the magnetic field sensor (01) and the multipole encoder (02). Sensor arrangement according to one of Claims 1 to 5 , characterized in that the magnetic field sensor (01) is designed in semiconductor construction and uses the magnetoresistive effect or the Hall effect. A method for generating a position change signal sequence with a sensor arrangement according to one of Claims 1 to 6 comprising the following steps: - outputting a switching signal pulse of the position change signal sequence (10) at each zero crossing of the x'-output voltage (08), the y'-output voltage (09) and the z'-output voltage (07), - outputting a switching signal pulse of the position change signal sequence (10) when the x'-output voltage (08) is equal to the z'-output voltage (07), and - outputting a switching signal pulse of the position change signal sequence (10) when the y'-output voltage (09) is the same as the z 'output voltage (07). Method according to Claim 7 in which a first differential voltage between the z'-output voltage (07) and the x'-output voltage (08) and a second differential voltage between the z'-output voltage (07) and the y'-output voltage (09) is formed and the Zero crossing of the first and the second differential voltage is detected to output a switching signal pulse.

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