WO2008043421A2

WO2008043421A2 - Magnet-based rotary transducer

Info

Publication number: WO2008043421A2
Application number: PCT/EP2007/008046
Authority: WO
Inventors: Frank Wolff; Jochen Schmitt; Franz Jost
Original assignee: Sensitec Gmbh; Levitec Gmbh
Priority date: 2006-10-12
Filing date: 2007-09-15
Publication date: 2008-04-17
Also published as: WO2008043421A3; DE102006048771A1

Abstract

The invention relates to a magnet-based rotary transducer comprising a first disk-type or ring-type structure and a second disk-type or ring-type structure which are oriented along an axis, extend along or parallel to a common plane, in a radial direction relative to said axis, are disposed at a distance from one another, and can be rotated relative to each other. The first structure encompasses at least two magnet poles that are used for generating a magnetic field and run perpendicular to the axis. The second structure is composed of at least two segments which are placed on a common plane, perpendicular to the axis, are made of a ferromagnetic material, and are used for conducting and concentrating a magnetic field generated by the first structure. Said segments define at least two material gaps in such a way that the local magnetic fields extending there are out of phase with each other. One respective magnetic field-sensitive sensor is positioned inside or near at least one of said two material gaps in order to measure the local magnetic field.

Description

Encoders on a magnetic basis

description

The invention relates to a rotary encoder on a magnetic basis.

Such encoders are used, for example, to detect torsions of a steering column.

From DE 602 00 499 T2, for example, a rotary encoder, there position sensor called known, which assumes a construction which consists of a first magnetic structure having a plurality of radially magnetized magnet and a second magnetic structure, each with one of two relative mutually rotatable parts are firmly connected. The second magnetic structure comprises two ferromagnetic rings, each ring consisting of a substantially tubular member having a plurality of axially aligned teeth which intermesh. The teeth of each ring are interconnected by a transverse flux closure area, with between the two

An air gap is defined and delimited flow closure areas, in which at least one magnetically sensitive element is arranged.

According to disclosure of DE 602 00 499 T2, each of the structures is rotatable with respect to a stationary reference. With an applied torque between the first and second structures, a differential motion occurs close to or below 10 degrees, which results in a change in the flux of several hundred Gauss in the second structure rotating air gap between the two second wreaths leads. A signal emitted by the magnetic field sensitive element thus provides an electrical image of a torque applied between the two relatively rotatable parts, bearing on the one hand the first structure and, on the other hand, the other structure. However, the complex structure of the two structures, in particular the axially intermeshing teeth of the two rings of the second structure, inevitably leads to mechanical and magnetic inaccuracies that distort the measurement result.

If, in addition to the applied torque, an information of the position of the two structures relative to the stationary reference is also to be detected, this prior art provides that the two transverse, i. extending radially from the first structure, flow closure regions defining the air gap therebetween each additionally with a number of radial teeth over 360 degrees, so that the magnetic field fixedly arranged in the magnetic field sensitive element basically also detects an alternating magnetic field of one period. Such training, however, introduces further inaccuracies into the measurement system.

A task compared to this known rotary encoder is thus to be seen in mechanical and / or magnetic

Inaccuracies or irregularities that falsify measurement signals to reduce. A further object is to provide a substantially simplified encoder assembly, with which an absolute rotational positions can be precisely displayed, and preferably also ensures a precise indication of an applied torque.

Further, for example, from US 4,782,002 A a rotary encoder is known which consists of a part with a plurality of magnets which are axially aligned and with Radial teeth of a stator cooperate. However, this overall very complex structure, as stated in the first cited reference, leads to magnetic leaks and reduced efficiency, resulting in a mediocre "signal-to-noise" ratio.

An essential object of the invention is thus to provide an overall improved resolution of the rotation detected by a substantially simplified rotary encoder and / or to ensure the aforementioned improvements.

Solutions according to the invention are indicated in the appended claims.

According to the invention, therefore, a rotary encoder is proposed which has a first substantially disc or ring-like

Structure and a second substantially disc or ring-like structure, which are aligned along an axis, extending radially to this substantially along or parallel to common planes, spaced from each other and are rotatably arranged relative to each other, wherein the first structure for generating a magnetic field comprises at least two magnetic poles. The second structure is composed of at least two arcuate segments of a ferromagnetic material arranged in common planes perpendicular to the axis

Magnetic field guide and concentration of a magnetic field generated by the first structure, wherein the segments define at least two material clearances so that the there running local magnetic fields are not in phase with each other, and wherein in or near at least these two material clearances in each case a magnetic field-sensitive sensor for measuring the local magnetic field is arranged. It is thus expedient if, depending on the application-specific embodiment, the respectively mutually opposite magnetic poles are arranged axially or radially. Preferred embodiments further provide that the first structure in the form of a magnetic ring or a magnetic disk and the second ferromagnetic structure is formed in the form of a ring gear.

In a particularly preferred development, the outer diameter of the first structure is smaller than the inner diameter of the second structure, and the two structures are arranged substantially in common, radially extending planes.

Another advantage is that in principle also embodiments can be provided, in which the

Outer diameter of the second structure is smaller than the inner diameter of the first structure and the two structures are arranged substantially in common radially extending planes. Alternatively it is suggested the first and the second

To arrange structure with axial distance from each other in two parallel planes.

Furthermore, as an alternative or in addition, it is provided that the second structure has at least two segments arranged at an axial distance from one another in two parallel planes and / or at least two segments arranged at a radial distance from one another in a common plane.

In order to enable a further increase in the resolution, particularly preferred embodiments provide at least two material clearances, in or near which a respective magnetic-field-sensitive sensor for measuring the local magnetic field is arranged, in such a way Define segments that relative rotation of the first structure to the second structure, there have the local magnetic fields to each other have a phase difference that is equivalent to a quarter period of a sinusoidal sensor output signal.

The material clearances, in or near which a total of at least two magnetic field-sensitive sensors for measuring the local magnetic fields are arranged, are arranged in appropriate embodiments of the rotary encoder according to the invention in each case at an angle of 90 degrees about the axis in the second structure.

In a particularly expedient development, in particular for signal optimization, it is provided to arrange in each case one sensor in or near four material clearances provided in each case at an angle about the axis in the second structure, wherein the

Material clearances are defined by the segments so that the sensor output signals of the respective opposite sensors to be combined for evaluation, in particular to add or subtract.

In some embodiments, it is provided to use measuring sensors for detecting magnetic field strengths as magnetic-field-sensitive sensors.

In alternative embodiments, measuring sensors for detecting angles or directions of magnetic field lines are used as magnetic field-sensitive sensors.

In these alternative embodiments, the invention further provides that in the material clearances, in or near which the magnetic field-sensitive sensors are arranged, additional magnets, in particular ring magnets of the same material as the magnetic material of the first structure are arranged. In some particularly preferred developments of a rotary encoder according to the invention, the first structure comprises a multi-pole magnet and the second structure comprises teeth extending in the direction of the first structure. In other particularly preferred embodiments, the first structure comprises a multipole magnet and between the first structure and the second structure, a third structure is coaxially arranged, which comprises at least two segments arranged in common planes perpendicular to the axis of a ferromagnetic material for magnetic field guidance and concentration of the magnetic field generated by the first structure, wherein the third structure comprises in the direction of the first structure extending teeth.

The teeth and the poles expediently have mutually corresponding dimensions.

In expedient refinements for this purpose, the first structure and the structure having the teeth are connected to one another via a torsion element.

In a particularly advantageous development of the aforementioned embodiments, it is provided that further magnets are arranged between the teeth.

Advantageous embodiments further preferably provide that the second structure and / or a third structure arranged co-axially between the first structure and the second structure, the at least two segments arranged in common planes perpendicular to the axis of a ferromagnetic material for magnetic field guidance and concentration of the magnetic field generated by the first structure comprises at least one narrowed transition region in a segment which merges from a segment region arranged closer to the first structure into a segment region of this segment which is farther away from the first structure. Appropriately, it is further provided in practice that the magnetic field-sensitive sensors are arranged stationary relative to the second structure, wherein the second structure of a rotary encoder is fixedly arranged depending on the specific application of the invention or can be.

A measuring device for detecting the rotation of a steering column of a vehicle thus preferably comprises a rotary encoder according to the invention, wherein the first or second structure connected to the steering column and the corresponding other structure, e.g. is arranged stationary.

The invention will be described in more detail below with reference to some expedient or preferred embodiments with reference to the accompanying drawings.

1 shows a first embodiment according to the invention for detecting a rotation from rotor to stator by direct field strength measurement of a magnetic field influenced by the rotation,

Fig. 2 shows a variant of the first embodiment for the compensation of radial offset between the rotor and

Stator,

3 shows a second embodiment according to the invention for detecting a rotation from rotor to stator by field direction measurement of a magnetic field influenced by the rotation,

Fig. 4 shows an alternative mechanical arrangement with respect to the embodiments according to FIGS. 1 to 3,

5 is a highly schematic representation of a further alternative arrangement which forms narrowed regions for guiding and concentrating field lines,

FIG. 6 is a highly schematic representation of a further alternative arrangement with respect to FIG. 5 for guiding and concentrating Field lines constricted areas, wherein the first and the second structure are arranged at an axial distance from each other,

FIG. 7 is a highly schematic representation of a further alternative arrangement with respect to FIG. 5 with regions constricted for guiding and concentrating field lines, wherein the first structure is axially extended, FIG.

8 to 11 further embodiments of a rotary encoder according to the invention, which in modification to the embodiments according to FIGS. 1 to 7 are designed to sensitize the measuring area,

12 is an expedient development based on the embodiment according to FIG. 1, which is likewise designed to sensitize the measuring area; FIG. 13 is a functional development based on the embodiment according to FIG. 3, which is likewise designed to sensitize the measuring area;

14 shows an alternative mechanical arrangement with respect to the embodiments according to FIGS. 1 to 3, which is likewise designed to sensitize the measuring area,

15 is an embodiment similar to FIG. 14 with modified magnet arrangement, FIG.

16 shows two diagrams, each with a sketch of calculated measured curves, based on an embodiment according to FIG. 12, FIG.

17 shows a diagram in which, based on an embodiment according to FIG. 14, detected angle changes of a respectively resulting magnetic field are sketched, FIG.

FIG. 18 shows two sinusoidal profiles of two output sinusoidal measurement signals and a smoothed measurement signal obtained by subtraction, FIG. 19 shows a further embodiment of a rotary encoder according to the invention, in which, in a modification to the embodiments according to FIGS. 12 and 13 by a respective two, an inner magnetic structure substantially by 180 degrees surrounding ring gear segments a material space in or near which a local magnetic field is measured to be defined.

In the following, exemplary expedient or preferred embodiments outlined by way of example in the figures will be described in more detail.

A rotary encoder according to the invention comprises a first substantially disc or ring-like structure and a second substantially disc or ring-like structure which are aligned along an axis and extend radially thereto substantially along or parallel to common planes. Both structures are spaced from each other and rotatably disposed relative to each other. The first structure comprises at least 2 magnetic poles for generating a magnetic field, which are arranged perpendicular or radial to the axis depending on the specific structure, wherein the magnet is in particular diametrically magnetized. The second structure is composed of at least two arcuate segments of a ferromagnetic material for guiding the magnetic field, arranged perpendicular to the axis in at least one common plane

constructed in a concentration of a magnetic field generated by the first structure, wherein the segments define at least two material clearances such that the local magnetic fields extending there are not in phase and wherein in or near these two material clearances each arranged at least one magnetic field-sensitive sensor for measuring the local magnetic field is.

In a first embodiment according to FIG. 1, the rotary encoder according to the invention comprises a first magnetic structure in the form of a magnet ring 101 and a second ferromagnetic structure in the form of a ring collar 201.

The magnet ring 101 and the annular ring 201 are aligned coaxially about an axis "A", wherein the outer diameter of the magnet ring 101 is smaller than the inner diameter of the

Ring wreath 201 is. The magnet ring 101 is disposed entirely inside the ring gear 201 and spaced from them, so that the magnet ring 101 and the ring gear 201 are arranged substantially in a common radially extending plane. The magnetic ring 101 is only polarized twice, wherein the magnetic poles "N" and "S" are disposed on the magnetic ring substantially radially opposite and the magnetic ring is diametrically magnetized. Ring ring 201 is made up of four substantially equal arcuate ring gear segments 211, 221, 231 and 241, e.g. are formed from a simple sheet metal.

The annular ring 201 has between the annular ring segments 211 and 221, 221 and 231, 231 and 241 and 241 and 211 each have a material recess in the form of an air gap. These material recesses can e.g. be provided by punching or free cutting in a separate production of ring ring segments by appropriate dimensioning and in the production of ring ring segments in one piece. It should be noted, however, that in principle a type of webs between the annular ring segments 211 and 221, 221 and 231, 231 and 241 and 241 and 211 may be left standing, so that the Materialauspaarung does not occur consistently in the radial direction.

The material clearances are each arranged at an angle of approximately 90 degrees offset in the annular ring 201, wherein in two offset by 90 degrees to each other free spaces each have a magnetic field-sensitive sensor 311 and 321, respectively. The embodiment according to FIG. 1 is thus essentially one of the simplest conceivable variants of the invention, free spaces, in or near each of which a magnetic-field-sensitive sensor for measuring the local magnetic field is arranged to be defined by the segments such that the local magnetic fields extending there do not are in phase with each other. The magnetic field lines of the inner magnet 101 are, as it were, collected by the outer flux guiding and concentrating segments 211, 221, 231 and 241 and inserted into the

Material clearances of ring gear 201 between segments 211 and 221 as well as 231 and 241 will cause magnetic field strengths, i. Amplitudes of the local magnetic fields measured. As the magnetic field sensitive sensor 311 or 321, therefore, e.g. an MR (magnetoresistive) sensor can be used.

A basic course of prevailing magnetic field lines in this embodiment, as well as in some embodiments discussed below, respectively in the figures sketchy by corresponding

Lines indicated, was omitted for reasons of clarity on a special labeling.

In the position of the magnet ring 101 and ring ring 201 shown in FIG. 1, the magnetic field is thus collected via the segments 221 and 231 over half the pole width of the north pole and over the adjacent half pole width of the south pole for the local magnetic field between the segments 221 and 231 while the segments 211 and 221 for providing the local magnetic field between the segments 211 and 221 cover the full pole width of the north pole. The two free spaces in which the magnetic field-sensitive sensors are arranged for the measurement of local magnetic fields are consequently always offset by approximately 90 degrees with respect to the magnetic ring 101 Axis "A" arranged. To start from the in FIG. 1 position shown upon rotation of the magnetic ring 101 to get back to the same local magnetic fields of the position shown in FIG. 1, it requires a rotation through 360 degrees, which in the example of FIG. 1 thus correspond to a full period. In the clearances between the segments 221 and 231 as well as between the segments 211 and 221 extending local magnetic fields thus always have in the example shown a phase difference to each other, which is equivalent to a quarter period of the output signals of the sensors 311 and 321.

At each sensor 311 or 321, at least to a first approximation, a sinusoidal function is thus output as a measurement signal which describes the rotation of the magnet ring 101 to the annular ring 201 between 0 and 360 degrees. With this arrangement, therefore, a rotation angle measurement can be performed which typically provides between 0 and 360 degrees of information, e.g. to determine the rotation of a steering wheel. The annular ring 201 is preferably stationary in this case and the magnetic ring 101 is e.g. connected to the steering column.

In practice, the magnetic field-sensitive sensors are further arranged stationary relative to the second structure, so that the measuring or output signals always on a sum of the over the constant area of the outer

Flow guiding and concentration segments 211, 221, 231 and 241 are based on collected field lines. Possible mechanical, location-dependent inaccuracies of the second structure are thus compensated. Thus, when the local magnetic fields differ by a quarter of a period, which corresponds to sensors 311 and 321 arranged at 90 degrees in FIG. 1, one sensor generates a sine curve as a measurement signal and the other generates a cosine curve as Measurement signal. Depending on the underlying angle of rotation to be measured, only the value of the sine or cosine changes at the point to be measured. In all embodiments, the invention always uses at least two at a certain angle with respect to that through the first

Structure generated magnetic field offset sensors for measuring respective local magnetic fields, so that in the further evaluation of both output measuring signals a smoothing and thus higher precision is effected and which is thus an essential basic principle of the invention.

In the embodiment of Fig. 1, which allows a pure rotational angle measurement or rotational position measurement, the magnetic field is thus generated largely homogeneous by the inner magnet 101, collected by the four flux guiding and -konzentrationssegmente 211, 221, 231 and 241 and in the free spaces between the ring gear segments 211 and 221 and 231 and 241 orthogonal or evaluated as orthogonal components. Although precise magnetic field measurements can be carried out with the embodiment according to FIG. 1 already with an extremely simple design of the rotary encoder according to the invention, since only field strength measurements are carried out, problems of a certain temperature dependence, which are known per se, can still occur. In an already advantageous compared to the first embodiment of FIG. 1 training variant, as seen in Fig. 2, in each of the outer annular ring 202 is offset in each case by 90 degrees with respect to the magnetic field generated by the magnetic ring 102 between the annular ring Segments 212 and 222, 222 and 232, 232 and 242 and 242 and 212 arranged a magnetic field-sensitive sensor for measuring the corresponding local magnetic fields arranged. The signals of the respectively opposite sensors 312 and 332 or 322 and 342 are for evaluation combined, ie added or subtracted depending on the application, to compensate or tolerate a possible radial offset between the outer annular ring 202 and the magnetic ring 102 and / or tumbling in particular of the magnetic ring 102 acting as a rotor.

An alternative to the embodiment of FIG. 1, second embodiment of an inventive based on a magnetic field measurement encoder is shown for example in Fig. 3. This embodiment offers the advantage over the embodiment according to FIG. 1 or also according to FIG. 2 that the magnetic field measurement can be carried out independently of the temperature, since not direct field strength measurements are carried out but angle changes of resulting local magnetic fields are detected.

With the embodiment of FIG. 3, angle measurements of magnetic field lines for detecting a rotation angle between the magnetic ring 103 rotatable about an axis "A" relative to the annular ring 203 are performed. Again, between the annular segments 213 and 223, 223 and 233, 233 and 243 and 243 and 213 of the ring gear 203 each with respect to the generated magnetic field of the magnet ring 103 by about 90 degrees offset material clearances exist, in or close to two offset by 90 degrees to each other open spaces each have an additional magnet 413 or 423 is arranged. These magnets, in turn, form a magnetic field which lies substantially in the same plane as the magnetic field generated by the inner magnetic ring 103. In Fig. 3 ring magnets 413 and 423 are used to generate a homogeneous magnetic field as additional magnets in the material clearances. Accordingly, these material clearances between the ring gear segments 213 and 223, 223 and 233, 233 and 243 and 243 and 213 are expedient circular shaped. For complete temperature compensation, the material of the magnets 413 and 423 suitably corresponds to the material of the magnetic ring 103.

The field lines of each magnetic field generated by an additional magnet 413 or 423 are superimposed by the magnetic field generated by the inner large magnetized magnetic ring 103. Depending on how much the internal magnetic field ultimately imprints in outer ring flux and concentration annulus segments 213 and 223 or 223 and 233 and overlays an outer magnetic field, this superposition results in an angle-dependent resulting local magnetic field in the corresponding circular magnetic field Section between the ring gear segments 213 and 223 or 223 and 233 is generated, wherein the field line course of the resulting local magnetic field describes a different angle than the field line course of an original external magnetic field. If the field generated by the inner magnetized ring 103 is weaker over the flux carrying and concentrating segments involved, the change in the external magnetic field generated by the magnet 413 or 423 will also be less, i. the direction of the resulting local magnetic field then deviates much less from the original direction of the original external magnetic field. Consequently, a measurement or detection of the angle of rotation over the direction of the resulting local magnetic fields in the interior of the circular Ausladungen is guaranteed.

In or near the measuring point for magnetic field measurement defining circular mating is thus the

Direction of a resulting magnetic field or the angle of the associated field lines by a in Fig. 2 ^" not shown for reasons of clarity magnetic field-sensitive sensor, such as by an MR Detected sensor, which then transmits a signal proportional to the direction or the angle to an evaluation, which calculates this according to the rotation angle in the interior. Since in FIG. 3 the material clearances provided in the annular ring 203 are expediently offset again by 90 degrees with respect to the magnetic field of the magnetic ring 103, the output measuring signals of the sensors again describe at least approximately a sine curve or a cosine curve.

Of course, the embodiment of FIG. 3 by one of FIG. 2 further variant, that is arranged in each of the four in the annular ring 203 each offset by 90 degrees arranged material clearances each have an additional magnet and each associated with a magnetic field-sensitive sensor and the measurement signals are added by respective opposing sensors.

In Fig. 4 is an alternative mechanical arrangement over the above to Figs. 1 to 3 discussed

Embodiments shown. In this arrangement, a first magnetized disc 104 comprising two magnetic poles and a ring collar made up of four ferromagnetic ring gear segments 214, 224, 234 and 244 are interposed between the segments in FIG

Material clearances of the ring gear arranged sensors 314, 324, 334 and 344 are not arranged at a radial distance from each other, but arranged at an axial distance from each other. Both relatively rotatably arranged structures are thus aligned along an axis and extend radially to this parallel to a common plane. This allows encoder arrangements in which the measuring device at a shaft end, eg a motor is mounted, and no additional space is required radially around the shaft.

In Figs. 5, 6 and 7 further alternative arrangements are shown in highly schematic form, which in particular in relation to the measurement accuracy in operation, i. at relative

Twisting the first to the second structure, a further improved structural design over the above to the Fign. 1-4 discussed embodiments include. In the arrangement according to FIG. 5, an inner, 2-pole magnetic ring 105 and an outer annular ring constructed from four ferromagnetic annular ring segments 215, 225, 235 and 245 are again shown in principle, wherein at least two are again formed by the segments 215, 225, 235 and 245 Material clearances 315, 325 are defined such that local magnetic fields extending there are not in phase with each other. In order to measure these local magnetic fields in or near these two material clearances, a magnetic-field-sensitive sensor (not shown in FIG. 5) is again arranged in each case.

However, as seen in FIG. 5, as modified from embodiments discussed above, each ring gear segment 215, 225, 235, and 245 has a narrowed transition region 615, 625, 635, and 645 that extends from a segment region closer to the first structure into a first structure transitions more distant segment area and consequently constricts the corresponding segment in some areas. These transition or constricting regions of the segments in each case represent a bottleneck with respect to the field line profile of the magnetic field generated by the first structure, through which the field lines respectively collected by a segment 215, 225, 235 and 245 and led outwards must pass. The material clearances defined by the segments 215, 225 and 245 315, 325, in or near which running local magnetic fields are measured, are therefore expediently defined by the segment regions of the segments 215, 225, 235 and 245 farther from the first structure. Since a rotation of the first structure 105 relative to the outer annular ring initially leads to a distortion of the field collected by the segment regions of the segments 215, 225, 235 and 245 arranged closer to the first structure, the transition regions 615, 625, 635 and 645 bring about a renewed concentration and alignment of the field lines before they are fed to the material clearances 315, 325 as local magnetic fields for measurement.

In the arrangement according to FIG. 6, first of all, similar to the arrangement according to FIG. 4, a first magnetized disk 106, which comprises two magnetic poles, and four ferromagnetic ring gear segments 216, 226, 236 and 246 are arranged at an axial distance from one another.

In a first modification to FIG. 4, however, ring-ring segments 216 and 226 as well as 236 and 246 are designed such that for each material clearance 316 or 326, in or near which a local magnetic field is to be measured, the arcuate segments 216 and 226 respectively 236 and 246, a substantially larger peripheral area of the magnetic disk 106 is detected, which leads to a further signal optimization of the measured field strength of a detected local magnetic field. For this purpose, annular ring segments 216 and 226 are arranged with radial spacing in the interior of the annular ring segments 236 and 246 in common planes. In a further modification to Fig. 4 has the

Embodiment of FIG. 6, similar to FIG. 5, in each annular ring segment 216, 226, 236 and 246 a narrowed transition region, wherein in Fig. 6 such Transition area is marked 626. Each transition region of a specific segment is in turn arranged between a segment region of the segment arranged closer to the first structure and a segment region of this segment which is more remote from the first structure. The material clearances 316, 326 defined by the segments 216, 226, 236 and 245 in or near which running local magnetic fields are thus measured are in turn defined by the segment regions of the segments 216, 226, 236 and 246 farther from the first structure 106.

In the arrangement according to FIG. 7, a magnetized ring 107 and four ferromagnetic annular ring segments 217, 227, 237 and 247 are arranged at a radial distance from the magnetized ring 107 in a modification of the arrangement according to FIG. 6. 6, for each material clearance 317 or 327, in or near which in the embodiment of FIG. 7 a local magnetic field is to be measured in each case, by the segments 217 and 227 or 237 and 247 a substantially larger one However, in addition, the ring gear segments 217 and 227 are arranged at an axial distance from the annular ring segments 237 and 247 to detect peripheral portion of the magnetized ring 107. Further, the magnetized ring 107 is axially elongated in this case so that the first structure and the second structure again extend substantially along or parallel to common planes.

Further, the magnetized ring 107 in the illustrated example of Fig. 7 has four magnetic poles, which are arranged axially or radially depending on the manner of providing the magnetic poles. However, in order to get back to the same local magnetic fields starting from the position shown in FIG. 7 when the magnetized ring 107 rotates, a rotation of 360 is still required Degree such that with respect to each material clearance 317 or 327, in or near which in the embodiment of Fig. 7, a local magnetic field is to be measured, again, only 2 poles influence the measurement range. In addition, each annular segment 217, 227, 237 and 247 has a narrowed transition region, wherein in Fig. 7, three such transition regions with 617, 627 and 637 is characterized. Each transition region of a particular segment is in turn arranged between a segment region of the segment arranged closer to the first structure and a segment region of this segment which is more remote from the first structure. The material clearances 317, 327 defined by the segments 217, 227, 237 and 247, in or near which running local magnetic fields are measured, are in turn defined by the segment regions of the segments 217, 227, 237 and 247 farther from the first structure 107.

While the embodiments described above according to FIGS. 1 to 7 enable pure rotational angle measurements, rotary encoders according to the invention for carrying out a

Torque measurement and a combination of rotation angle and torque measurement based on further figures discussed below.

To carry out a torque measurement, for example by means of a torsion bar, an additional boundary condition must first be taken into account. In the case of a pure torque measurement, of course, the angle between the first, in particular acting as a rotor, and the second, acting in particular as a stator, structure by which the relative positioning of the two structures changed to each other is very small, usually less than 10 degrees. Accordingly, the measuring functionality of the rotary encoder must be optimized in principle so that even with a small angle a reasonable situation can be precisely derived is.

If also or only small angles are to be measured, this becomes evident, as can be seen from the embodiments described below, e.g. realized by the fact that the first, magnetized structure with respect to each material space, in or near which each a local magnetic field is to be measured, is significantly increased in the magnetic pole number and thus, of course, gets a better resolution, as is obvious to a person skilled in the art. In a modification to the embodiments according to FIGS. 1 to 7, in which the first magnetized structure 101, 102, 103, 104, 105, 106 and 107, respectively, is only doubly polarized, in the particularly preferred embodiments described below is a first magnetic structure 108, 109, 1010, 1011, 1012 , 1013, 1014 and 1015, respectively, which comprises a plurality of polarizations exceeding twice the polarization for each local magnetic field to be detected and consequently forms a multipole magnet.

Fig. 8 shows a first embodiment which is remarkably increased in magnetic pole number with respect to each material clearance in or near which a local magnetic field is to be measured. The rotary encoder shown schematically has an inner multi-pole magnetic ring 108 and an outer annular ring, which is composed of eight annular segments.

In the illustrated example, each annular ring segment again has a narrowed transition region 618, which transitions from a segment region arranged closer to the first structure into a segment region which is more remote from the first structure. The material clearances defined by the outer annular ring segments, in or near which local magnetic fields are measured, are in turn defined by the segment regions of the segments which are more remote from the first structure. In total, four such Materialfreiräurae are each offset by 90 degrees with respect to the generated magnetic field of the magnetic ring 108, wherein a total of four sensors 318, 328, 338 and 348, are arranged in the material clearances of the ring gear segments. The signals of the respectively opposite sensors 318 and 338 or 328 and 348 are thus combined again with each other for evaluation in order to compensate or tolerate a possible radial offset between the outer annular ring and the inner magnetic ring 108 and / or a tumbling.

Depending on the material space for measuring a local magnetic field, the magnetic ring 108 no longer has only two poles, but is provided as a multipole magnet. The flux guidance and concentration of the magnetic field generated by the plurality of magnets of the magnetic ring 108 additionally takes place via teeth 500 extending radially in the plane of the magnetic ring 108 in the direction of the magnet ring, which teeth are provided on each segment region arranged closer to the first structure. In the position shown in FIG. 8, the teeth 500 of the annular ring segments, which lead a magnetic field to the more distant segment areas to the sensors 318 and 338 disposed opposite each other in the outer annular ring, are exactly centered over adjacent north and south poles, so that the entire field of these adjacent north and south poles closes over this tooth and no resulting field is collected to the outer ring of rings.

On the other hand, the teeth 500 of the annular ring segments, which guide a magnetic field to the more distant segment regions on the sensors 328 and 348 arranged opposite one another in the outer annular ring, respectively cover exactly the pole width of a north pole. Thus, in this embodiment as well, a phase difference of the local magnetic fields detected by the sensors 318 and 328 is ensured. Since a full period in turn corresponds to the twisting of the inner structure relative to the outer structure by two adjacent, oppositely magnetized magnetic poles, it does not require a full rotation of 360 degrees more, which consequently further increases the resolution.

It will also be apparent to one skilled in the art that the above-described embodiments are thus also advantageously suitable for measuring a torque, in which case the first structure and the second structure are suitably connected to one another via a torsion element.

FIG. 9 shows an alternative to FIG. 8

Embodiment, however, is also significantly increased in the magnetic pole number with respect to each material space in or near which each a local magnetic field is to be measured. An inner multi-pole magnetic ring 109 is radially surrounded by an outer annular ring composed of two ring-ring segments 219 and 229 each having a narrowed transition region 618.

A first sensor 319 is disposed in a material space defined by the more remote segment areas of the outer ring gear for measuring a local magnetic field. A second sensor 329 is arranged in a material space defined by the segment regions of the outer annular ring closer to the first structure for measuring a local magnetic field. The annular ring segments 219 and 229, which lead a magnetic field to the sensor 319, in turn, have in the direction of the magnet ring 109 extending teeth 500, which in the position shown in each case exactly the pole width of a Cover the North Pole. Since the annular segments 219 and 229 span an arc of approximately 180 degrees, this leads, compared to FIG. 8, to more accurate measurement signals of the sensor 319. The second sensor 329 is located in the position shown exactly centered on adjacent north and south poles. Consequently, also in this embodiment, a phase difference of the local magnetic fields detected by the sensors 319 and 329 is ensured.

FIG. 10 shows in highly schematic form an embodiment modified from FIG. 9, in which an outer annular ring constructed from two ring rim segments 2110 and 2210, each with a narrowed transition region 618, essentially completely leads the collected magnetic field to the material clearance 3110 for the local local measurement. The flux of the magnetic field generated by the magnetic structure 1010 is quasi symmetrically decoupled.

Is omitted in the embodiments of FIGS. 9 and 10 to a second sensor as shown in FIG. 9, similar to the arrangement of FIG. 7, a second pair of outer ring gear segments with axial

Distance and with respect to the magnetic field detection twisted to the ring gear segments 219 and 229 or 2110 and 2210 are arranged, in which case the magnetized ring 109 and 1010 expediently again axially extended. Depending on the axial spacing of the two pairs of

Ring rim segments to each other is further proposed to close each pair of outer ring gear segments on the radially opposite side of the sensor by appropriate merger or extension of the first structure more distant segment areas to collect an optionally axially evoked Magnetstreufeldeld. FIG. 11 is a highly schematic representation of an embodiment modified from FIGS. 9 and 10, in which two annular segments 2111 and 2211 without inner transition region surround an inner magnetic ring 1011 and a magnetic field collected from magnetic ring 1011

Material clearance 3111 lead to local local measurement. In this case, for a second sensor, in turn, a second pair of outer ring gear segments with axial spacing and with respect to the magnetic field detection twisted to the ring gear segments 2111 and 2211 is arranged.

The embodiments of FIGS. FIGS. 12 and 13 each show further developments which are expedient to the embodiments according to FIGS. 1 to 11. First, in the embodiment of Fig. 12, similar to Fig. 1, in the ring gear 2012 again four material clearances each offset at an angle of 90 degrees between the segments 2112, 2212, 2312 and 2412, wherein in. Two offset by 90 degrees to each other open spaces in each case a magnetic field-sensitive sensor 3112 or 3212 is arranged to measure the field strength. In the embodiment according to. Fig. 13, similar to Fig. 3, between the ring gear segments 2113 and 2213, 2213 and 2313, 2313 and 2413 and 2413 and 2113 of the ring gear 2013 each 90 degrees mutually offset material clearances exist, with two offset by 90 degrees to each other Freiräumen in each case an additional ring magnet 4113 or 4213 is arranged. In or near this space provided with ring magnets free space thus again the direction of a resulting magnetic field or the angle of the associated field lines is detected by a not shown in Fig. 6 for reasons of clarity magnetic field-sensitive sensor whose signal is calculated back to the rotation angle in the interior.

In a modification or development to Fig. 1 and Fig. 3, however, and similar to the embodiments of FIGS. 8 to 11 For example, the magnet ring 1012 (FIG. 12) or 1013 (FIG. 13) no longer has only two poles, but is provided as a multipole magnet. The flow guidance and concentration of the magnetic field generated by the plurality of magnets of the magnet ring 1012 or 1013 is effected via teeth 500 extending radially in the plane of the magnet ring 1012 or 1013 in the direction of the magnet ring. According to FIGS. 12 and 13, however, in a modification to FIGS. 8 to 11, these teeth 500 are provided on a further third structure arranged between the first and second structures, which comprises at least two segments, arranged in a common plane perpendicular to the axis, of a ferromagnetic material for guiding the magnetic field and concentration is built up. In FIGS. 12 and 13, this third structure is made up of two further ferromagnetic sheet metal segments 5112 and

5212 and 5113 and 5213, respectively, for flux guidance and concentration, which are co-axially disposed between the magnetic ring 1012 or 1013 and the ring gear 2012 and 2013, respectively, in the common plane. In these embodiments, the magnet ring 1012 or 1013 and the segments 5112 and 5212 or 5113 and 5213 are rotatably arranged relative to the ring gear 2012 and 2013, respectively. The magnet ring 1012 or 1013 and the segments 5112 and 5212 or 5113 and

5213 are connected to each other via a torsion element, so that they can also rotate relative to one another with torque applied between the magnetic ring 1012 or 1013 and the segments 5112 and 5212 or 5113 and 5213.

If now there is the situation that the magnetic ring 1012 or 1013 and the segments 5112 and 5212 or 5113 and 5213 are not rotated relative to one another, ie they remain "fixed" to one another and are only twisted together to ring ring 2012 or 2013, as in the above-described embodiments, in particular according to FIGS. 1 to 7, only the angle of rotation between the annular ring 2012 or 2013 and this system of magnetic ring 1012 or 1013 and the segments 5112 and 5212 or 5113 and 5213 detected.

If the situation exists that the inner magnet ring 1012 or 1013 and the middle tooth segments 5112 and 5212 or 5113 and 5213 are also rotated relative to each other, then a torque measurement is additionally performed.

This torque measurement is then proportional to the rotation of the inner magnet ring 1012 or 1013 and the middle tooth segments 5112 and 5212 or 5113 and 5213, which are detected with the same sensors. The sensors thus provide information about the angle of rotation of the ring gear system 2012 or 2013 consisting of the magnetic ring 1012 or 1013 and the segments 5112 and 5212 or 5113 and 5213 and information about the ring gear

Torque on the offset between the magnet ring 1012 or 1013 and the segments 5112 and 5212 or 5113 and 5213.

The measuring range in relation to the torque here extends over a "half tooth" per pole width. If, starting from a value shown in Figs. 12 and 13 illustrated relative position of the teeth 500 to the magnetic poles of the magnetic ring 1012 and 1013 so this relative position changes so that each adjacent north and south poles are effectively centered over a tooth 500, and this thus each half a pole width of the north - and superimposed on the immediately adjacent south pole, then the entire field of these adjacent north and south poles closes over this tooth and no resulting field is collected to the outer ring ring 2012 or 2013, which is therefore an unfavorable constellation. If you want to capture the maximum signals at a torque of "0", so should the Basic structure be arranged such that in this case, as shown, a tooth each covers a pole width of the magnet.

In other words, the worst case test signal occurs in the moment when all

Completely close magnetic field lines already over the teeth, because adjacent north and south poles are each uniformly covered, so that in operation no resulting field would be more outside out, which comes for a rotary measurement into consideration.

In the embodiment according to FIG. 14, in further development of the embodiment according to FIG. 13, additional magnets 700 are arranged between the teeth 500 on the additional tooth segments 5113 and 5213, which effect a basic magnetization of these segments. The individual magnetic fields of the

Magnetic rings 1013 and the tooth segments 5113 and 5213 are thus added or subtracted from each other depending on the position, which leads to a further improved accuracy. Further, in this case, the measuring range with respect to the torque extends over a complete pole width per tooth.

Since, in the embodiments according to FIGS. 12, 13 and 14, the sensors arranged on the rotary sensors, for example, in turn MR sensors, output substantially sinusoidal waveforms, one sinusoidal and one set in each case due to the offset by 90 degrees use of two sensors to cosinusoidal waveform.

FIG. 15 shows an embodiment similar to FIG. 14, but in which the arrangement of the further magnets 700, ie substantially the polarization of these magnets, is opposite to the magnetization of the inner magnetic structure 1013, which in the present case leads to a reduction of the collected field lines and therefore too a reduction in the amplitude of the local magnetic fields to be measured leads.

As can be seen, in all of the embodiments discussed above with respect to FIGS. 12 to 15, a narrowed transition region is also provided in each segment of the intermediate third structure comprising the teeth. Each transition region, in turn, connects a segment region located closer to the first structure and a segment region more distant from the first structure, and thus presents in a manner similar to that of FIGS

Embodiments according to FIGS. 5 to 10 are discussed, with respect to the field line profile of the magnetic field generated by the first structure, in each case a bottleneck, through which the respectively collected field lines must pass.

FIG. 16 shows two diagrams, each with a sketch of calculated measured curves, which are based on an embodiment according to FIG. 12.

Shown in each case successively or independently calculated field strengths Bl and B2 via a

Angle of rotation between the system consisting of the magnet ring 1012 and the segments 5112 and 5212 to the annular ring 2012 from 0 degrees to 180 degrees. The calculation of the field strength Bl or B2 is carried out in each case on the magnetic field measurement of first and second sensors, which are arranged offset by 90 degrees in or near a respective measuring point, as described above.

Shown with Bl is a moment where the magnetic ring 1012 and the segments 5112 and 5212 are fixed to each other and so there is no external torque. The curves in this sketched example thus represent a change in the angle of rotation between the system consisting of the magnetic ring 1012 and the segments 5112 and 5212, and FIG Ring wreath 2012 between 0 degrees and 180 degrees again. The information about the angle of rotation is based on the curves in that, starting from the respective amplitudes, the sine and cosine functions determined with the sensor elements are recalculated to an Argus tangent function in order to obtain a pure angle.

If the magnet ring 1012 and the segments 5112 and 5212 are rotated relative to one another, then, as can be seen by curve B2, the amplitude of the resulting sine or cosine function is thereby changed. That is, when an argastangle calculation is performed again, the information also contains the absolute information of the amplitude variation. In other words, for the rotation angle measurement, the consideration of the argus tangent is the essential quantity, and for the torque measurement, the amplitude of this recalculated sine or cosine function is the relevant quantity. In a measurement signal, therefore, both information is included.

At the sensors, whereby always at least two sensors offset by a certain angle with respect to the generated magnetic field are used, a sinusoidal function is thus detected in each case at least to a first approximation, which, when the magnet ring 1012 and the segments 5112 and 5212 fix to each other, the rotation to the ring gear 2012 describes between 0 and 180 degrees. With sensors offset by 90 degrees, one sensor thus generates a sine curve and the other generates a cosine curve. The amplitudes of these curves are in turn dependent on the rotation between the magnetic ring 1012 and the segments 5112 and 5212. Consequently, if magnetic ring 1012 and segments 5112 and 5212 are considered in fixed relation to one another, then only the value of the sine or cosine changes at a measuring point. FIG. 17 shows a diagram in which, based on an embodiment according to FIG. 14, corresponding to the calculated field strengths discussed above are sketched correspondingly detected angular displacements of a respectively resulting magnetic field.

FIG. 18 shows two sinusoidal profiles of two output sinusoidal measurement signals, a measurement signal "signal a" output at a first measurement location and a measurement signal "signal b" output at a second measurement location, and a smoothed measurement signal "signal" obtained by subtraction Obviously provides a very precise measurement signal.

FIG. 19 shows in a highly schematic manner the principle of a further rotary encoder according to the invention, which is modified from FIGS. 12 and 13. In Fig. 19, two outer annular segments 2119 and 2219 are shown, which are arranged substantially symmetrically about a first magnetic structure 1019 radially around and each defining an arc of about 180 degrees. Both annular ring segments 2119 and 2219 also each have a narrowed one

Transition region, as with respect to Figs. 5 to 10 described on. Further, the embodiment illustrated in FIG. 19 includes teeth 500 at another third structure disposed between the first and second structures, which, as described with reference to FIGS. 12 and 13 described, from at least two arranged in a common plane perpendicular to the axis segments 5119 and 5219 of a ferromagnetic material for magnetic field guidance and concentration is constructed. These two segments 5119 and 5219 also have a narrow transition region.

In or near a material clearance 3119 for measuring a local magnetic field defined by the more distant segment regions of the outer annular ring is not represented sensor arranged. Due to the elongated arc-shaped segments 2119 and 2219, a substantially larger peripheral area of the magnetic structure 1019 is in turn detected, which in turn leads to an improved amplification of the maximum field strength of a locally detected magnetic field and thus to a more accurate measurement signal.

To provide a second material clearance, in or near which another local magnetic field with phase difference to be measured is similar to the arrangement of FIG. 7, a second pair of outer ring gear segments and additionally a second pair of middle segments with axial distance and with respect to Magnetic field detection rotated to segments 2119, 2219 and 5119 and 5219 arranged, in which case the magnetic structure 1019 expediently again axially extended.

Consequently, a fully integrated rotary encoder based on FIG. 19 also has a second structure of axially spaced-apart segments arranged in two parallel planes.

One skilled in the art will appreciate that the invention basically also includes embodiments in which the outer diameter of the second structure is smaller than the inner diameter of the first structure and the two structures are arranged in substantially common, radially extending planes.

Claims

claims

A magnetic-based rotary encoder comprising - a first substantially disc-like or ring-like structure and a second substantially disc-like or ring-like structure aligned along a common axis, extending substantially along or radially along said axis extend parallel to common planes, spaced from each other and are rotatably arranged relative to each other, - wherein the first structure for generating a magnetic field comprises at least two magnetic poles, - wherein the second structure of at least two arranged in common planes perpendicular to the axis segments of a ferromagnetic material for magnetic field guidance and concentration of a magnetic field generated by the first structure, and the segments define at least two material clearances such that the local magnetic fields extending there are not in phase with each other and wherein at least two of these two material f A magnetic field-sensitive sensor for measuring the local magnetic field is arranged in each case.

2. Rotary encoder according to the preceding claim, wherein the magnetic poles are arranged perpendicular or radial to the axis.

3. Encoder according to claim 1 or 2, wherein the first structure in the form of a magnetic ring or a Magnet disc and the second ferromagnetic structure is formed in the form of a ring gear.

4. A rotary encoder according to one of the preceding claims, wherein the outer diameter of the first structure is smaller than the inner diameter of the second

Structure and the two structures are arranged substantially in a common radially extending plane.

5. Encoder according to one of the preceding claims 1 to 3, wherein the outer diameter of the second

Structure is smaller than the inner diameter of the first structure and the two structures are arranged substantially in a common radially extending plane.

6. Rotary encoder according to one of the preceding claims, wherein the first and the second structure are arranged at an axial distance from each other in two parallel planes.

7. Rotary encoder according to one of the preceding claims, wherein the second structure has at least two axially spaced apart in two parallel planes arranged segments.

8. Rotary encoder according to one of the preceding claims, wherein the second structure has at least two radially spaced-apart in a common plane arranged segments.

9. Rotary encoder according to one of the preceding claims, wherein at least two material clearances, in or near which in each case a magnetic field-sensitive sensor for measuring the local magnetic field is so defined by the segments that at relative rotation of the first structure to the second structure extending there local magnetic fields to each other have a phase difference which is equivalent to a quarter period of a sinusoidal sensor output signal.

10. Rotary encoder according to one of the preceding claims, wherein the material clearances are arranged in or near which a total of at least two magnetic field sensitive sensors for measuring the local magnetic fields, each offset at 90 degrees about the axis in the second structure.

11. Rotary encoder according to one of the preceding claims, wherein in each case a sensor is arranged in or near four provided by an angle offset about the axis in the second structure material clearances, the material clearances are defined by the segments that the sensor signals of each opposite sensors to be combined for evaluation, in particular to add or subtract.

12. Rotary encoder according to one of the preceding claims, wherein measuring sensors for detecting magnetic field strengths are used as magnetic field-sensitive sensors.

13. Rotary encoder according to one of the preceding claims 1 to 6, wherein as magnetic field-sensitive sensors

Measuring sensors are used to detect angles or directions of magnetic field lines.

14. Rotary encoder according to the preceding claim, wherein in or near the material clearances, in or near which the magnetic field-sensitive sensors are arranged, additional magnets, in particular ring magnets, are arranged.

15. The rotary encoder of claim 1, wherein the first structure comprises a multipole magnet and the second structure comprises teeth extending in the direction of the first structure.

16. The rotary encoder according to claim 1, wherein the first structure comprises a multipole magnet and, between the first structure and the second structure, a third structure is arranged coaxially, the at least two segments arranged in common planes perpendicular to the axis of a ferromagnetic material for magnetic field guidance and concentration of the magnetic field generated by the first structure, wherein the third extending in the direction of the first structure comprises teeth.

17. Rotary encoder according to one of the two preceding

Claims, wherein the first structure and the structure comprising the teeth via a torsion element communicate with each other.

18. Rotary encoder according to one of the three preceding

Claims, wherein between the teeth further magnets are arranged.

19. The rotary encoder according to claim 1, wherein the second structure and / or a third structure arranged coaxially between the first structure and the second structure comprise at least two segments arranged in common planes perpendicular to the axis made of a ferromagnetic material for magnetic field guidance and Concentration of the magnetic field generated by the first structure comprises at least one narrowed transition region in a segment, which from a closer to the first structure arranged segment region in one of first structure remoter segment area of this segment passes.

20. Rotary encoder according to one of the preceding claims, wherein the magnetosensitive sensors are arranged stationary relative to the second structure.

21. Rotary encoder according to one of the preceding claims, wherein the second structure is arranged stationary.

22. Measuring device for detecting the rotation of a steering column of a vehicle, characterized by a rotary encoder according to one of the preceding

Claims, wherein the first or second structure is connected to the steering column and the corresponding other structure is arranged stationary.

23. Rotary encoder or measuring device according to one of the preceding claims, wherein sensors are used as magnetoresistive sensors.