Inductive angle measuring device

Abstract

To provide an inductive angle measuring device.SOLUTION: An inductive angle measuring device comprises a scanning element 1 and a scale element 2 having at least three scale tracks. First scale track and third scale track include an equal first number of scale structures, and a second scale track includes a second number of scale structures 2, different from the first number. The scale tracks are arranged circumferentially and concentrically about an axis A, such that the first scale track is arranged radially inward, the second scale track is arranged radially between the first scale track and the third scale track, and the third scale track is arranged radially outward. The scanning element 1 includes receiving conductor paths and can generate signals including a signal periods related to angle through the receiving conductor paths, and the first signal period is equal to the third signal period. An overall signal can be generated from the first signal and the third signal and can be combined with the second signal for determining absolute angle position information.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an inductive angle measuring device for determining absolute angle position information or an absolute angle position according to claim 1.

Background Art

[0002] Inductive angle measuring devices are used, for example, as angle measuring instruments for determining the angular positions of two machine parts that are rotatable relative to each other. In an inductive angle measuring device, in many cases, excitation windings and receiving conductor paths are applied to a generally multi-layer common conductor plate that is firmly connected, for example, to the stator of an angle measuring instrument. This conductor plate faces a scale element to which a graduation structure is applied, and the scale element is non-rotatably connected to the rotor of the angle measuring instrument. When a time-varying excitation current is applied to the excitation winding, signals that depend on the angular position are generated in the receiving conductor paths during the relative rotation of the rotor and the stator. These signals are then further processed by an evaluation electronic circuit. In order to generate absolute angle position information, the scale element often has two or more tracks with graduation structures, and these graduation structures have different graduation periods and are evaluated according to the vernier or beat principle.

[0003] Inductive angle measuring devices as described above are often used as measuring instruments for electric drive devices to determine the relative movement or relative position of corresponding machine parts. In this case, the generated angle position values are supplied to subsequent electronic devices for controlling the drive device via a corresponding interface configuration.

[0004] In the applicant's DE102013218768A1, an inductive position measuring device is described in which the inclination of a scanning unit relative to a reference about an axis parallel to the axis of rotation can be calculated using an additional graduation track. The Moiré angle calculated in this way can be used in an evaluation device to correct a scanning signal or an absolute position.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] DE102013218768A1 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide an inductive angle measuring device that enables the precise determination of the absolute angular position between two mechanical parts that are rotatable relative to each other. [Means for solving the problem]

[0007] This objective is achieved according to the features of claim 1 of the present invention. According to the above characteristics, the induction angle measuring device has a scanning element and a scale element. The scale element includes a first scale track having a first scale structure, a second scale track having a second scale structure, and a third scale track having a third scale structure, the scale structures being arranged regularly. Over a predetermined or given fixed angular range of the same size, the first scale track has a scale structure of a first number n1, and the third scale track has a scale structure of a third number n3, where the first number n1 is equal to the third number n3 (n1=n3). In contrast, the second scale track has a scale structure of a second number n2 over a predetermined angular range of the same size, which is different from the first number n1 or the third number n3 (n1=n3≠n2). Furthermore, scale tracks are arranged concentrically around the axis, with a first scale track positioned radially inward, a second scale track positioned radially between the first and third scale tracks, and a third scale track positioned radially outward. The scanning element has excitation lines. Furthermore, the scanning element has a first receiving conductor path, a second receiving conductor path, and a third receiving conductor path. The first scale track is scannable via the first receiving conductor path to generate a first signal having a first signal period with respect to an angle. The second scale track is scannable via the second receiving conductor path to generate a second signal having a second signal period with respect to an angle, and the third scale track is scannable via the third receiving conductor path to generate a third signal having a third signal period with respect to an angle. With respect to an angle, the first signal period is the same magnitude as the third signal period. A whole signal can be generated from the first and third signals, and the whole signal can be combined with the second signal to determine absolute angular position information.

[0008] Typically, a scale element has a scale track that covers the entire 360°, and therefore, in most cases, a given angular range extends to 360°. However, angle measuring devices are also known that are used to measure only limited rotational positions. In this case, the given angular range that fits the rotational range may be less than 360°. The first, second, and third numbers n1, n2, and n3 of the scale structure can be considered as numbers n1, n2, and n3 normalized to angular ranges.

[0009] The receiving conductor path preferably has a spatially regular sinusoidal curve along a circular arc and has a period that matches the period length of the scale structure to be scanned. Conventionally, scanning elements and scaling elements are positioned opposite each other in the axial direction, separated by an axial gap.

[0010] Advantageously, the first scale track has a first radial extension region H1, and the third scale track has a third radial extension region H3, where the first radial extension region H1 is greater than the third radial extension region H3 (H1 > H3). The radial extension region H3 is, for example, the radial length measured in millimeters.

[0011] Advantageously, the first scale track is positioned with a phase offset in the circumferential direction greater than 150° and less than 210° relative to the third scale track. In particular, the phase offset may be in the range of 170° to 190°. In other words, with respect to the circumferential or measurement direction, the first and third scale tracks (in particular their scale structures) are positioned relative to each other such that the first and third signals have an electrical phase offset between 150° and 210°, preferably between 170° and 190°.

[0012] In a further embodiment of the present invention, the angle measuring device has an analog electrical circuit, which is capable of generating an overall signal by calculation or interconnection of first and third signals.

[0013] The first signal and the third signal are processed together to obtain the overall signal. The overall signal is generated, in particular, by subtraction or addition operations. Advantageously, the angle measuring device may have further circuitry, which allows for the generation of absolute angular position information from the overall signal and a second signal by the caliper method. In particular, the further circuitry may be configured as a digital circuit.

[0014] In a further embodiment of the present invention, the scanning element includes a first scanning track located radially inward and a third scanning track located radially outward, wherein the first scanning track includes a first receiving conductor path and at least one section of an excitation wire positioned at a first effective radial distance from the first receiving conductor path. Thus, at least one section extends radially offset with respect to the first receiving conductor path at the first effective radial distance. The third scanning track includes a third receiving conductor path and at least one further section of an excitation wire positioned at a third effective radial distance from the third receiving conductor path, where the first radial distance is greater than the third radial distance. Preferably, the excitation wire can extend in the measurement direction or in a section along the measurement direction.

[0015] Advantageously, the second signal period is greater than the first signal period and greater than the third signal period. In many cases, the scanning track is configured to have multiple receiving conductor paths, and advantageously, two of the scanning track's receiving conductor paths have a phase offset of 90° relative to each other.

[0016] The angle measuring device also includes an electronic circuit, which can generate an excitation current in the excitation line. Advantageously, at a given point in time, the excitation current extends in the same direction in the section immediately adjacent to the excitation line.

[0017] In a further embodiment of the present invention, the scale element is configured such that a first scale track extends along a first arc and has a first radial centerline having a first radius r1'. Furthermore, a second scale track extends along a second arc and has a second radial centerline having a second radius r2'. Finally, a third scale track extends along a third arc and has a third radial centerline having a third radius r3'. Here, the scale element is formed such that the distance between the first radial centerline and the second radial centerline is not equal to the distance between the third radial centerline and the second radial centerline, i.e., (r2'-r1')≠(r3'-r2'). In particular, the distance between the first radial centerline and the second radial centerline is smaller than the distance between the third radial centerline and the second radial centerline. That is, (r2'-r1')<(r3'-r2').

[0018] The scanning element is configured such that the scale element can be scanned not by the scanning element over the entire 360°, but only over one segment, or over multiple such segments that are offset circumferentially.

[0019] Here, each segment or any combination of segments extends over an angle less than 180°, particularly less than 120°, and favorably less than 90°. In particular, the first receiving conductor path, the second receiving conductor path, and the third receiving conductor path extend over an angle less than 180°, particularly less than 120°, and favorably less than 90°.

[0020] In a further embodiment of the present invention, the first receiving conductor path has a first period with respect to an angle, the second receiving conductor path has a second period with respect to an angle, and the third receiving conductor path has a third period with respect to an angle. The first period is equal to or the same magnitude as the third period with respect to an angle.

[0021] Advantageous developments of the present invention can be seen in the dependent claims. Further details and advantages of the inductive angle measuring device according to the invention will become apparent from the following description of two exemplary embodiments based on the accompanying drawings.

Brief Description of the Drawings

[0022] [Figure 1] It is an exploded perspective view of the angle measuring device. [Figure 2] It is a plan view of the scanning element. [Figure 3] It is a detailed view of the scanning element. [Figure 4] It is a plan view of the scale element according to the first exemplary embodiment. [Figure 5] It is a detailed view of the scale element according to the first exemplary embodiment. [Figure 6] It is a perspective view of the angle measuring device in the assembled state. [Figure 7] It is a graph including the profiles of the first and third signals and the overall signal. [Figure 8] It is a graph including the profile of the second signal. [Figure 9] It is a plan view of the scale element according to the second exemplary embodiment. [Figure 10] It is a detailed view of the scale element according to the second embodiment.

Mode for Carrying Out the Invention

[0023] The present invention will be described based on the angle measuring device according to FIG. 1. The angle measuring device includes a scanning element 1 that can be fixed to a housing 3 and a scale element 2 or a scale. The scale element 2 may be non-rotatably connected to a shaft 4 that is rotatable about an axis A with respect to the housing. The angle measuring device is for detecting an absolute angular position in the circumferential direction corresponding to the measuring direction U, which is determined between the scanning element 1 and the scale element 2.

[0024] Scanning element 1 is implemented as a conductive plate having several layers and is used to scan scale element 2. Scanning element 1 shown in Figure 2 has, among other things, an excitation line 1.4, which in the exemplary embodiment presented is configured as a circumferential conductive path having multiple windings. Furthermore, scanning element 1 has a first scanning track TA1 located radially inward. This scanning track TA1 includes a first receiving conductive path 1.1 and two sections 1.41 and 1.42 of the excitation line 1.4. The two sections 1.41 and 1.42 extend radially on both sides of the first receiving conductive path 1.1. Furthermore, scanning element 1 has a second scanning track TA2 and two sections 1.42 and 1.44 of the excitation line 1.4, which extend radially on both sides of the second receiving conductive path 1.2. Finally, the scanning element 1 has a third scanning track TA3 located radially outward, the third scanning track TA3 comprising a third receiving conductor path 1.3 and two sections 1.43 and 1.44 of an excitation line 1.4, the two sections 1.43 and 1.44 extending radially on both sides of the third receiving conductor path 1.3. The receiving conductor paths 1.1, 1.2, and 1.3 of each scanning track TA1, TA2, and TA3 extend in different planes with interlayer connections to avoid undesirable short circuits at intersections. In the illustrated exemplary embodiment, several layers are provided in the conductor plate structure. The receiving conductor paths 1.1, 1.2, and 1.3 of each scanning track TA1, TA2, and TA3 have a spatially regular profile that is essentially sinusoidal or sinusoidally configured. Herein, the transverse coordinate of the relevant sinusoidal curve extends along a circular line centered on axis A. Below, the length quantities in the circumferential or measurement direction U are given in angular dimensions. Accordingly, the first receiving conductor path 1.1 has a first period Π1 with respect to angle, and in the exemplary embodiment presented, in accordance with the conditions of the scale element 2, the following equation holds:

[0025] Π1 = 9.00° The second receiving conductor path 1.2 has a second period Π2 with respect to angle, and unlike the first period Π1, the following equation holds true for period Π2.

[0026] Π² = 9.23° ≠ Π1 π2 > π1 In contrast, the third receiving conductor path 1.3 has a period Π3 with respect to the angle, and this period Π3 corresponds to the first period Π1.

[0027] Π3 = Π1 = 9.00° In the exemplary embodiments presented, each of the receiving conductors 1.1, 1.2, and 1.3 extends over four complete (sine) periods PI1, PI2, and PI3. The receiving conductors 1.1, 1.2, and 1.3 are each offset from one another along the measurement direction U within their respective scanning tracks TA1, TA2, and TA3. Here, adjacent receiving conductors 1.1, 1.2, and 1.3 in the circumferential direction U are offset from one another by 1 / 8 of the period PI1, PI2, and PI3 within their respective scanning tracks TA1, TA2, and TA3. The receiving conductors 1.1, 1.2, and 1.3 for each scanning track TA1, TA2, and TA3 are electrically connected so that they can ultimately deliver signals that are each 90° phase-shifted with respect to each scanning track TA1, TA2, and TA3. In the exemplary embodiments presented, the receiving conductors 1.1, 1.2, and 1.3 are each interrupted by a gap. As is known, this configuration can contribute to a decrease in sensitivity to relative inclination (pitch inclination) around an axis having a radial orientation.

[0028] The scanning element is configured such that the scaling element can be scanned by this scanning element over a segment that extends only over an angle α, which in the exemplary embodiment presented is approximately 45°.

[0029] In Figure 3, scanning element 1 can be seen in enlarged detail. The dashed lines represent the transverse coordinates of the corresponding sinusoidal curves around the radial centers, i.e., axis A, of the receiving conductor paths 1.1, 1.2, and 1.3, and the transverse coordinates extend along the circular lines. Sections 1.41, 1.42, 1.43, and 1.44 of the excitation line 1.4 may have one conductor path or multiple conductor paths, as in the exemplary embodiments presented.

[0030] Figure 4 shows a plan view of scale element 2. In the illustrated exemplary embodiment, scale element 2 consists of a substrate made of epoxy resin, on which three scale tracks TS1, TS2, and TS3 are arranged. The scale tracks TS1, TS2, and TS3 are circular in shape and are arranged on the substrate around the entire circumference, extending in the measurement direction U with different radii with respect to the axis of rotation A. Here, the first scale track TS1 is positioned radially inward, the second scale track TS2 is positioned radially between the first scale track TS1 and the third scale track TS3, and the third scale track TS3 is positioned radially outward.

[0031] The scale tracks TS1, TS2, and TS3 consist of a regular sequence of scale structures 2.1, 2.2, and 2.3, respectively, which in the presented exemplary embodiment are configured as conductive scale regions 2.11, 2.21, and 2.31, with non-conductive scale regions 2.12, 2.22, and 2.32 positioned between them. As the material for the conductive scale regions 2.11, 2.21, and 2.31, copper was applied to the substrate in the illustrated example. In contrast, the substrate was not coated in the non-conductive scale regions 2.12, 2.22, and 2.32 between the conductive scale regions 2.11, 2.21, and 2.31.

[0032] Overall, the first scale track TS1 includes a first number n1 (40) regularly arranged first scale structures 2.1 over an angular range of 360° or 2π, and the same number of non-conductive regions placed between them. The third scale track TS3 includes a third number n3 regularly arranged third scale structures 2.3. Thus, the following equation holds:

[0033] n1=n3=40 In contrast, the second scale track TS2 has a second scale structure 2.2 consisting of a second number n2 (39) regularly arranged over 360°.

[0034] n2=39 Therefore, the second scale track TS2 also has a scale structure 2.2 of a second number n2 that is different from the first number n1 or the third number n3 over an angular range of 360°, and in particular the following equation also holds:

[0035] n2 <n1およびn2<n3 Figure 5 shows a detailed view of the scale element 2. Here, it can be seen that the first radial centerline M1 of the first scale track TS1 extends along an arc with radius r1. Correspondingly, the radial centerlines M2 and M3 of the second scale track TS2 and the third scale track TS3 extend along arcs with radii r2 and r3, respectively. In the exemplary embodiment presented, the scale tracks TS1, TS2, and TS3 are arranged equidistant from each other.

[0036] As can be seen from Figure 5, each of the first scale structures 2.1 extends over a first angular range Φ1, which is 9.00° (360° / n1) in the exemplary embodiment presented. Correspondingly, each of the second scale structures 2.2 extends over a second angular range Φ2, which is 9.23° (360° / n2). Finally, the third angular range Φ3, to which each of the third scale structures 2.3 extends, is also 9.00° (360° / n3). However, since the first radius r1 is smaller than the third radius r3, the scale period measured in millimeters is shorter on the first scale track TS1 than on the third scale track TS3.

[0037] With respect to the measurement direction U, the first scale track TS1 is positioned such that the center of the conductive scale region 2.11 of the first scale track TS1 and the center of the non-conductive scale region of the third scale track TS3 coincide on radially aligned lines Q and S, where lines Q and S are offset from each other by a first angular range Φ1. Furthermore, the centers of the non-conductive scale region 2.12 and the conductive scale region 2.31 of the first scale track TS1 coincide on radially aligned line R. Line R is positioned midway between lines Q and S, i.e., at a distance of 1 / 2·Φ1 from each. As a result, the first scale track TS1 is positioned with a circumferential phase offset of 180° relative to the third scale track TS3.

[0038] Furthermore, the first scale track TS1 or its conductive scale region 2.11 has a first radially extending region H1 which is 4.8 mm in the exemplary embodiment presented. The third scale track TS3 or its conductive scale region 2.31 has a third radially extending region H3, which is 4.09 mm. Thus, the first radially extending region H1 is larger than the third radially extending region H3, and the following equation holds:

[0039] H1>H3 In the assembled state shown in Figure 6, the scanning element 1 and the scale element 2 face each other axially, with axis A extending through the midpoint of both elements. During relative rotation between the scale element 2 and the scanning element 1, the receiving conductor paths 1.1, 1.2, and 1.3 can generate first, second, and third signals S1, S2, and S3, respectively, which depend on their angular positions, through inductive effects. The prerequisite for shaping the corresponding signals S1, S2, and S3 is that the excitation line 1.4 generates a time-varying electromagnetic excitation field within the region of the scanned scale tracks TS1, TS2, and TS3. In the illustrated exemplary embodiment, the excitation line 1.4 is formed as an energized, planar parallel conductor path comprising multiple windings. The scanning element 1 has an electronic circuit including, for example, an ASIC module 1.5 (Figures 1 and 6). This electronic circuit of the scanning element 1 acts not only as an evaluation element but also as an excitation control element, under which an excitation current is generated, which then flows through the excitation line 1.4.

[0040] When an excitation current flows through excitation wire 1.4, it forms a tubular or cylindrical directional electromagnetic field around excitation wire 1.4. The magnetic field lines of the electromagnetic field thus generated extend concentrically around excitation wire 1.4, and the direction of the magnetic field lines depends on the direction of the current in excitation wire 1.4 in a known manner. Here, the current directions of sections 1.41, 1.42, 1.43, and 1.44 of excitation wire 1.4 adjacent to common receiving conductor paths 1.1, 1.2, and 1.3 can be selected such that the magnetic field lines within the regions of receiving conductor paths 1.1, 1.2, and 1.3 each have a desired orientation. When several sections 1.41, 1.42, 1.43, and 1.44 of excitation wire 1.4 extend in parallel, as in the exemplary embodiment presented, this has the same effect as when a larger current flows through a single excitation wire having a correspondingly larger cross-sectional area.

[0041] Regarding the function of the angle measuring device, particularly with respect to the height of the received levels of the first and third signals S1 and S3, it is important how large the first effective radial distance G1 or the third effective radial distance G3 is within the first scanning track TA1 or the third scanning track TA3 (Figure 3). The first radial distance G1 with respect to the first scanning track TA1 is the distance between the radial center of the first receiving conductor path 1.1 and the radial center of section 1.42 (or section 1.41) of the excitation line 1.4. In the special case where the excitation line 1.4 consists of only one conductor path in the relevant section, the radial center of that conductor path becomes important. In the exemplary embodiments presented, sections 1.41, 1.42, 1.43, and 1.44 always include multiple parallel conducting paths, and therefore the centers of the multiple parallel conducting paths can be considered as the radial centers of sections 1.41, 1.42, 1.43, and 1.44. In any case, the local effectiveness of the excitation line 1.4 is important for determining the effective radial distances G1 and G3. In this regard, it is necessary to take into account that multiple conducting paths combine according to the principle of superposition to generate a magnetic field. Thus, the effective radial distances G1 and G3 are the distance between the radial centers of the receiving conducting paths 1.1 and 1.3 and the centers of virtual conducting paths that generate the same magnetic field as the conducting path bundles of the same scanning tracks TA1 and TA3. Similarly, a third effective radial distance G3 with respect to a third scanning track TA3 can also be set.

[0042] The excitation current induces voltages in the receiving conductor paths 1.1, 1.2, and 1.3, depending on the angular position of the scale element 2. These voltages are referred to here as the first, second, and third signals S1, S2, and S3. Figures 7 and 8 show graphs in which the angle φ (see Figure 6) is plotted on the horizontal axis and the signal level u is plotted on the vertical axis. The graphs in Figures 7 and 8 represent conditions where the slope or moiré angle is equal to zero, i.e., ideal mounting conditions.

[0043] In Figure 7, the dashed line represents the profile of the first signal S1 generated by the first receiving conductor path 1.1 of the first scanning track TA1 when scanning the first scale track TS1. Correspondingly, the dashed line represents the profile of the third signal S3 generated by the third receiving conductor path 1.3 of the third scanning track TA3 when scanning the third scale track TS3. Due to the configuration of the first scale track TS1 and the third scale track TS3 and their relative arrangement (particularly the scale structures 2.1 and 2.3), the first signal S1 has a phase offset of 180° relative to the third signal S3. Furthermore, the first signal S1 has a first signal period Σ1 with respect to the angle φ. Similarly, the third signal S3 has a third signal period Σ3 with respect to the angle that can be generated by the third receiving conductor path 1.3. The first signal period Σ1 is exactly the same as the third signal period Σ3.

[0044] Σ1=Σ3 From the first signal S1 and the third signal S3, a whole signal SM (SM = S3 - S1) can be generated. For this purpose, the first signal S1 of the first scanning track TA1, in particular the first receiving conductor path 1.1, is connected to the third signal S3 of the third scanning track TA3, in particular the third receiving conductor path 1.3, and the whole signal SM is obtained by such calculation. In the exemplary embodiment presented, this is realized by a simple analog circuit on the scanning element 1, where difference generation is performed by calculation, and thus the whole signal SM can also be called the difference signal. With a 180° phase offset, interference components, for example, due to crosstalk effects or signal harmonics, have opposite signs and are therefore canceled out or at least reduced. In any case, it is important that the first and third signals S1 and S3 are coupled in phase, in particular subtracted. The whole signal SM has a signal period ΣM of the same magnitude as the first signal period Σ1 or the third signal period Σ3.

[0045] ΣM=Σ1=Σ3 Moiré error arises from the tilt of scanning element 1 relative to scale element 2 around a tilt axis having a component parallel to the A-axis. In the case of the tilt of scanning element 1 relative to scale element 2 in the sense of moiré motion, the profile of the first signal S1 shifts along the transverse coordinate, and the profile of the third signal S3 shifts in the opposite direction in a corresponding manner. Despite this geometric deviation from the ideal configuration, the overall signal SM hardly changes. Therefore, the overall signal SM thus generated, in particular its phase position, is largely unrelated to the moiré error caused by tolerances. Such tilting results in a phase difference between the fine track signal and the coarse track signal in conventional angle measuring devices, leading to inaccurate coupling or misconnection of the two signals. This ultimately results in incorrect angular position information.

[0046] Avoiding moiré errors is particularly important in the exemplary embodiments presented, because the scanning element 1 is configured to scan the scale element 2 only over a limited angle, i.e., over a single segment, rather than over the entire circumference. In full-circumference scanning, moiré errors are naturally and significantly compensated for.

[0047] If the axial gap between scanning element 1 and scale element 2 changes, for example due to heating of shaft 4, without special measures, the distance behavior of the first scanning track TA1 will differ from that of the third scanning track TA3. This effect hinders the reduction of moiré errors. To minimize this undesirable effect, the first effective radial distance G1 is greater than the third effective radial distance G3.

[0048] G1>G3 This configuration harmonizes the effects of distance changes on each amplitude or signal level. In this regard, the aforementioned configuration also acts in a supporting role, so that on the scale element 2 side, the first radial extension region H1 is larger than the second radial extension region H3.

[0049] The first receiving conductor path 1.1 and the third receiving conductor path 1.3 can generate angular position values ​​with higher resolution regarding relative angular position, while the second receiving conductor path 1.2 can generate angular position values ​​with lower resolution. Therefore, the second signal period Σ2 of the second signal S2 (see Figure 8) is greater than the first signal period Σ1 or the third signal period Σ3.

[0050] Σ2 > Σ1, Σ2 > Σ3 Therefore, the overall signal SM, which is virtually free of moiré error, can be considered a virtual fine-grained track signal that can be coupled with an angularly coarser second signal S2 to determine absolute angular position information. In the exemplary embodiment presented, digital calculations for this purpose are performed in ASIC1.5 using the caliper method or the beat method.

[0051] Therefore, with an angle measuring device configured in this way, even when the scanning element 1 scans the scale element 2 only over relatively short segments and relatively large design tolerances are permitted, it is possible to generate absolute angular position information that has little moiré error and thus guarantees higher measurement accuracy.

[0052] Further embodiments of the present invention (a second exemplary embodiment) are described based on Figures 9 and 10. The second exemplary embodiment differs in essence from the first exemplary embodiment in that the scale element 2' is configured such that the innermost first scale track TS1' is positioned closer to the second scale track TS2' than the outermost third scale track TS3'. Correspondingly, the first scale track TS1' has a first radial centerline M1' extending along a first arc and having a first radius r1'. The second scale track TS2' has a second radial centerline M2' extending along a second arc and having a second radius r2'. Finally, the third scale track TS3' has a third radial centerline M3' extending along a third arc and having a third radius r3'. Thus, the following equation holds:

[0053] (r2'-r1')≠(r3'-r2') In particular, the following equation holds true. (r2'-r1')<(r3'-r2') In other respects, the scale element 2' in the second exemplary embodiment is configured substantially identically to the scale element 2 in the first exemplary embodiment. In the second exemplary embodiment, the radius of the scanning track of the scanning element is adapted to the profile of radii r1', r2', r3', or the scale tracks TS1', TS2', TS3'. [Explanation of symbols]

[0054] 1 scanning element 1.1 First receiving conductor path 1.2 Second receiving conductor path 1.3 Third receiving conductor path 1.4 Excitation lines 2 Scale elements 2.1 First scale structure 2.2 Second scale structure 2.3 Third scale structure A-axis G1 First radial distance G3 Third radial distance H1 First radial extension area H3 Third radial extension area n1, n3 The first number n2 is the second number S1 First signal S2 Second signal S3 Third signal SM overall signal TS1 First scale track TS2 Second scale track TS3 Third scale track Σ1 First signal period Σ2 Second signal period Σ3 Third signal period

Claims

1. An inductive angle measuring device having a scanning element (1) and a scale element (2; 2'), wherein the scale element (2; 2') comprises a first scale track (TS1; TS1') having a first scale structure (2.1) arranged regularly, a second scale track (TS2; TS2') having a second scale structure (2.2) arranged regularly, and a third scale track (TS3; TS3') having a third scale structure (2.3) arranged regularly, over a predetermined angular range, the first scale track (TS1; TS1') and the third scale track (TS3; TS3') have the same first number (n1, n3) of scale structures (2.1, 2.3), the second scale track (TS2; TS2') has a second number (n2) of scale structures (2.2) different from the first number (n1, n3), the first scale track (TS1; TS1') is radially inside, the second scale track (TS2; TS2') is between the first scale track (TS1; TS1') and the third scale track (TS3; TS3') radially, and the third scale track (TS3; TS3') is radially outside, so that the scale tracks (TS1, TS2, TS3; TS1', TS2', TS3') are arranged concentrically around the axis (A) over the entire circumference, the scanning element (1) comprises an excitation wire (1.4), a first receiving conductor path (1.1), a second receiving conductor path (1.2), and a third receiving conductor path (1.3), the first scale track (TS1; TS1') is scanable via the first receiving conductor path (1.1) to generate a first signal (S1) having a first signal period (Σ1) related to the angle, the second scale track (TS2; TS2') is scanable via the second receiving conductor path (1.2) to generate a second signal (S2) having a second signal period (Σ2) related to the angle, the third scale track (TS2; TS3') is scanable via the third receiving conductor path (1.3) to generate a third signal (S3) having a third signal period (Σ3) related to the angle, The first signal period (Σ1) is equal to the third signal period (Σ3), and an overall signal (SM) can be generated from the first signal (S1) and the third signal (S3), and the overall signal (SM) can be combined with the second signal (S2) to determine absolute angular position information. Inductive angle measuring device. **Claim 2** The inductive angle measuring device according to claim 1, wherein the first scale track (TS1; TS1') has a first radially extending region (H1), the third scale track (TS3; TS3') has a third radially extending region (H3), and the first radially extending region (H1) is larger than the third radially extending region (H3). **Claim 3** The inductive angle measuring device according to claim 1, wherein the first scale track (TS1; TS1') is arranged with a phase offset that is greater than 150° and less than 210° with respect to the third scale track (TS3; TS3') in the circumferential direction. **Claim 4** The inductive angle measuring device according to any one of claims 1 to 3, having an analog circuit, wherein the overall signal (SM) can be generated by the analog circuit through the operation of the first and third signals (S1, S3). **Claim 5** The inductive angle measuring device according to any one of claims 1 to 3, wherein the first signal (S1) and the third signal (S3) are arithmetically operated on each other by an addition or subtraction operation to form the overall signal (SM). **Claim 6** The inductive angle measuring device according to any one of claims 1 to 3, further having a further circuit, wherein the further circuit can generate absolute angular position information from the overall signal (SM) and the second signal (S2) by the caliper method. **Claim 7** The inductive angle measuring device according to claim 6, wherein the further circuit is configured as a digital circuit. **Claim 8** The scanning element (1) includes a first scanning track (TA1) on the radially inner side and a third scanning track (TA3) on the radially outer side. The first scanning track (TA1) the first receiving conductor path (1.1) and at least one section (1.41, 1.42) of the exciting wire (1.4) arranged at a first effective radial distance (G1) from the first receiving conductor path (1.1). The third scanning track (TA3) the third receiving conductor path (1.3) including at least one section (1.43, 1.44) of the exciting wire (1.4) arranged at a third effective radial distance (G3) from the third receiving conductor path (1.3), and the first effective radial distance (G1) being greater than the third effective radial distance (G3). The inductive angle measuring device according to any one of claims 1 to 3.

9. The inductive angle measuring device according to any one of claims 1 to 3, wherein the second signal period (Σ2) is greater than the first signal period (Σ1) or the third signal period (Σ3).

10. The scale element (2') The first scale track (TS1') extends along a first arc and has a first radial center line (M1') with a first radius (r1'). The second scale track (TS2') extends along a second arc and has a second radial center line (M2') with a second radius (r2'). The third scale track (TS3') extends along a third arc and has a third radial center line (M3') with a first radius (r3'). where (r2' - r1') ≠ (r3' - r2') holds The inductive angle measuring device according to any one of claims 1 to 3, configured as such.

11. where (r2' - r1') < (r3' - r2') holds, the inductive angle measuring device according to claim 10.

12. The scanning element (1) is configured such that the scale element (2; 2') can be scanned only over at least one segment by the scanning element (1). The inductive angle measuring device according to any one of claims 1 to 3.

13. The inductive angle measuring device according to claim 12, wherein the at least one segment extends over an angle (α) of less than 180°, in particular less than 120°.

14. The first receiving conductor path (1.1) has a first period (Π1) with respect to the angle, the third receiving conductor path (1.3) has a third period (Π3) with respect to the angle, and the scanning element (1) is configured such that the first period (Π1) is equal to the third period (Π3). The inductive angle measuring device according to any one of claims 1 to 3.

15. The inductive angle measuring device according to claim 14, wherein the second receiving conductor path (1.2) has a second period (Π2) with respect to an angle, and the scanning element (1) is configured such that the second period (Π2) is larger than the first period (Π1).

Images