Inductive position measuring device

Abstract

The invention relates to an inductive position measuring device having a scanning element (1) and a scale element (2). The position of the scanning element relative to the scale element in a first direction (x) and in a second direction (z) can be determined by the position measuring device. The scale element comprises graduation structures (2.1) arranged one after the other in the first direction, which have a periodic course in the second direction with a second period length (Dz). The scanning element comprises a first receiver track (1.1), a second receiver track (1.2) and a third receiver track (1.3) and excitation conductors (1.4, 1.5, 1.6). One of the three receiver tracks (1.1, 1.2, 1.3) each has two receiver rails (1.11, 1.12, 1.21, 1.22, 1.31, 1.32). The receiver rails have a periodic course in the first direction with a first period length (Px), the receiver tracks (1.1, 1.2, 1.3) being offset from one another in the second direction.

Description

Technical Field

[0001] The present invention relates to an inductive position measuring device for determining the position of a scanning element relative to a scale element in a first direction and a second direction. Background Technology

[0002] Inductive position measuring devices are used, for example, as angle measuring devices to determine the angular position of two machine parts that can rotate relative to each other. In an inductive position measuring device, excitation leads and receiver tracks, typically in the form of printed wires, are applied to a common, generally multi-layered circuit board, which is fixedly connected, for example, to a fixture of the angle measuring device. A scale element is positioned opposite the circuit board, with an indexing structure applied to it, and the scale element is torsionally connected to a rotating part of the angle measuring device. If time-alternating excitation currents are applied to the excitation leads, a signal related to the angular position is generated in the receiver coil during relative rotation between the fixture and the rotating part. This signal is then further processed in evaluation electronics.

[0003] Such inductive position measuring devices are typically used as measuring equipment for electric drives to determine the relative motion or orientation of corresponding machine parts. In this case, the generated angular position value is transmitted via a corresponding interface device to subsequent electronics used to control the drive. In some applications, it is desirable not only to generate angular position values ​​but also position values ​​for displacement or for offset along the axial direction.

[0004] It is also known that a position measuring device can be used to perform two-dimensional measurements of a position in a plane.

[0005] An inductive position measuring device is described in the applicant's application DE 10 2012 223 037 A1, by means of which angular position and axial offset can be determined. The axial offset or axial orientation is obtained by means of a groove encircling between two indexing tracks. With this position measuring device, the axial offset can be determined only along a relatively small measurement path. Summary of the Invention

[0006] The basic objective of this invention is to provide a relatively accurate and inexpensive inductive position measuring device that enables position determination in two directions.

[0007] The inductive position measuring device has a scanning element and a scale element. The position of the scanning element relative to the scale element in a first direction and a second direction can be determined by the position measuring device. The scale element includes indexing structures arranged sequentially along the first direction. The indexing structures have a periodic orientation along the second direction, the periodic orientation having a second period length. The scanning element includes a first receiver track, a second receiver track, and a third receiver track, as well as at least one excitation wire. Each of the three receiver tracks has two receiver guides, the receiver guides having a periodic orientation along the first direction, the periodic orientation having a first period length Px. The three receiver tracks are offset from each other in the second direction.

[0008] The first direction can be, for example, a circumferential direction or a tangential direction. In this case, the angular position of the scale element relative to the scanning element about the (rotational) axis in terms of rotational or pivoting motion can be measured by determining the position in the first direction. Then, the second direction can be oriented particularly orthogonally to the first direction, for example, parallel to the (rotational) axis, about which the scale element can rotate relative to the scanning element.

[0009] Alternatively, the position measuring device can also be designed to determine two-dimensional position in a plane, wherein the first direction is preferably orthogonal to the second direction in the plane. In this case, the scale element can therefore be designed as a flat plate.

[0010] The scanning element and the scale element are typically positioned opposite each other and spaced apart by air gaps extending in, for example, in the axial or radial direction. The receiver rails are typically configured such that they have a phase offset relative to each other (e.g., a 90° phase offset).

[0011] Advantageously, the first receiver track is positioned relative to the adjacent second receiver track in a second direction by an offset of the first track offset Pz12, where the track offset Pz12 is not equal to n times the second period length Dz, where n is a natural number, i.e., Pz12 ≠ n·Dz. This eliminates the possibility of the two receiver tracks being offset from each other in the second direction by the second period length or several times the second period length.

[0012] Another advantage is that the second receiver track is set relative to the third receiver track along the second direction z by an offset of the second track offset Pz23, where the second track offset Pz23 is not equal to n times the second period length Dz, where n is a natural number, i.e., Pz23≠n·Dz.

[0013] The consideration of the corresponding orbital offsets Pz12 and Pz23 involves referring only to the center distance from the corresponding receiver orbit in the second direction.

[0014] In addition to at least three receiver tracks, one or more additional receiver tracks may be provided. This is for example, in cases involving the detection of rotation of the scanning element relative to a scale element (Moire defect detection). In this case, the additional receiver tracks can therefore be spaced apart from one of the at least three receiver tracks by a distance n times the second cycle length.

[0015] Advantageously, the first orbital offset Pz12 or the second orbital offset Pz23 is equal to n times the second period length Dz divided by another natural number m, i.e.

[0016] Pz12=n·Dz / m, where n≠m, or

[0017] Pz23=n·Dz / m, where n≠m.

[0018] In another design of the present invention, the other natural number m is equal to 3, that is...

[0019] Pz12=n·Dz / 3, where n≠3, or

[0020] Pz23=n·Dz / 3,n≠3。

[0021] The first orbital offset Pz12 is advantageously equal to the second orbital offset Pz23, that is...

[0022] Pz12=Pz23.

[0023] Advantageously, the indexing structures are arranged periodically along a first direction with an indexing period Dx, wherein the length of the indexing period Dx is approximately the size of the first period length Px. Particularly suitable for:

[0024] 0.75·Dx≤Px≤1.25·Dx, or

[0025] 0.9·Dx≤Px≤1.1·Dx, or

[0026] Dx = Px.

[0027] The periodic orientation of the indexing structure or the receiver guide can be understood as a pattern that repeats in space at fixed intervals (spatial periodicity). The indexing structure or receiver guide is advantageously designed to have a curved or bent orientation and, in particular, no straight sections.

[0028] According to an improved embodiment of the invention, the indexing structure has a sinusoidal or sinusoidal orientation along the second direction. Therefore, the imaginary abscissa of the sinusoidal line to which the indexing structure belongs extends parallel to the second direction.

[0029] In another embodiment of the invention, the indexing structure is designed as a tab and a gap or slot. The lengths of the tab and the gap along a first direction are added together to form the indexing period Dx or the length of the indexing structure. Advantageously, within the indexing period Dx, the length of the tab can be greater than the length of the gap.

[0030] The receiver rails advantageously have a sinusoidal or sinusoidal orientation along the first direction.

[0031] The scale element is advantageously designed as a particularly rotationally symmetric body with a curved surface (outer side, convex outer surface, or concave inner surface), at which the indexing structure is located. The scale element is rotatable relative to the scanning element about an axis extending parallel to a second direction, wherein the first direction also extends or is oriented in a circumferential direction. However, the axis may optionally also extend parallel to the first direction, while the second direction extends in a circumferential direction.

[0032] In another design of the invention, the scale element is designed as a cylindrical body, especially a hollow cylindrical body.

[0033] The indexing structure can have different spacing from the axis along the second direction. For example, the scale element can be designed as a cone or a sphere (with a barrel-shaped outer profile), and the indexing structure is located on the cone or sphere face. In this configuration, the change in the relative position between the scanning element and the scale element also produces a change in signal amplitude, which can therefore also be used as information about the position in the second direction. Attached Figure Description

[0034] Further details and advantages of the inductive position measuring device of the present invention will become apparent from the following description of embodiments, based on the accompanying drawings.

[0035] Figure 1 A three-dimensional diagram of the scale element is shown.

[0036] Figure 2 A top view of the scanning element is shown.

[0037] Figure 3 A detailed diagram of the scale element is shown.

[0038] Figure 4 Detailed diagrams of the scale element and the scanning element are shown. Detailed Implementation

[0039] The present invention is described according to a position measuring device, which is configured to detect the position of the scanning element 1 ( Figure 2 The position of the scale element 2 or scale relative to axis A in the first direction x (corresponding to the angular position) between the scale element 2 and the scale that can rotate relative to axis A. And its position in the second direction z. The axis A is oriented parallel to the second direction z. Therefore, the first direction x can also be defined as the circumferential direction.

[0040] Figure 1 Show scale element 2 and Figure 3 A magnified partial view of the scale element 2 is shown. The scale element 2 is made of aluminum. In this embodiment, the scale element 2 is designed as a hollow cylinder or ring with an axis A, and an indexing structure 2.1 is provided on the outer side of the hollow cylinder or ring. In the example shown, the indexing structure 2.1 includes tabs 2.11 and gaps 2.12 or grooves located between the tabs. Therefore, the indexing structure 2.1 is composed of a periodic sequence of alternating tabs 2.11 and gaps 2.12 about a first direction x or a circumferential direction. The indexing period Dx of the indexing structure 2.1 is... Figure 3 The length T of one of the tabs 2.11 and the length G of one of the gaps 2.12 are obtained, wherein the lengths T and G extend in the first direction x or the circumferential direction.

[0041] Dx = G + T.

[0042] The length T is the same for all tabs 2.11, and the length G is the same for all gaps 2.12. Additionally, in the illustrated embodiment, within the indexing period Dx, the length T of tab 2.11 is greater than the length G of the gap (T > G).

[0043] The indexing structure 2.1, i.e., the tab 2.11 and the gap 2.12 located between the tabs, have a spatially periodic orientation, which is designed to be substantially sinusoidal or sinusoidal with respect to the second direction z. Here, the abscissa of the associated sine line extends along a line parallel to axis A or along the second direction z. In the illustrated embodiment, each indexing structure 2 passes through multiple complete sinusoidal cycles, wherein each indexing structure 2 has a second cycle length Dz.

[0044] according to Figure 2The scanning element 1 is designed as a multi-layered circuit board and is used to scan the scale element 2. The scanning element 1 shown has a first receiver track 1.1, a second receiver track 1.2, and a third receiver track 1.3. Each of the three receiver tracks 1.1, 1.2, and 1.3 includes two receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32. Furthermore, the scanning element 1 includes excitation wires 1.4, 1.5, and 1.6, which surround the receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32. Moreover, the receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32 extend on different planes using vias, thereby avoiding unwanted short circuits at intersections. In the illustrated embodiment, at least two layers are provided in the circuit board structure. Receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32 have a generally sinusoidal or sinusoidal spatial periodic orientation. Here, the abscissa of the corresponding sinusoid extends along a line parallel to the first direction x. The rail offsets Pz12 and Pz23 between adjacent receiver rails 1.1, 1.2, and 1.3 correspond to the spacing of their respective abscissas, i.e., the center-to-center spacing. In the illustrated embodiment, each receiver rail 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32 traverses a complete sinusoidal cycle having a first cycle length Px. In this embodiment, the first cycle length Px is equal to the indexing period Dx.

[0045] Px = Dx = T + G.

[0046] Receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32 belonging to the same receiver tracks 1.1, 1.2, and 1.3 are staggered from each other along the first direction x. In the illustrated embodiment, receiver rails 1.11, 1.12; 1.21, 1.22; 1.31, and 1.32 in the same receiver tracks 1.1, 1.2, and 1.3 (i.e., receiver rails 1.11 and 1.12 of the first receiver track 1.1, receiver rails 1.21 and 1.22 of the second receiver track 1.2, and receiver rails 1.31 and 1.32 of the third receiver track 1.3) are set off from each other by 1 / 4 of a full sine cycle (offset by π / 2 or 90° along the first direction x). Receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32 are electrically connected so that they can ultimately provide a signal phase-shifted by 90° in the first direction x in terms of positioning.

[0047] The first receiver track 1.1 is positioned relative to the adjacent second receiver track 1.2 in the second direction z by an offset of the first track offset Pz12. Similarly, the second receiver track 1.2 is positioned relative to the adjacent third receiver track 1.3 in the second direction z by an offset of the second track offset Pz23. In the illustrated embodiment, the first track offset Pz12 between the first receiver track 1.1 and the second receiver track 1.2 is equal to the second track offset Pz23 between the second receiver track 1.2 and the third receiver track 1.3 (Pz12 = Pz23). Figure 2 and Figure 4 As shown, the first track offset Pz12 and the second track offset Pz23 also correspond to the spacing (center spacing) between the multiple centers of the receiver tracks 1.1, 1.2, and 1.3 in the second direction z.

[0048] Therefore, adjacent receiver tracks 1.1, 1.2, and 1.3 are positioned in the second direction z by offsets of track offsets Pz12 and Pz23 from each other, respectively. In the illustrated embodiment, the first track offset Pz12 and the second track offset Pz23 are one-third of the second period length Dz, that is:

[0049] Pz12=Dz / 3=Pz23.

[0050] According to Figure 4 In their assembled state, scanning element 1 and scale element 2 are positioned opposite each other with a radial spacing or radial air gap, such that even with relative rotation between scale element 2 and scanning element 2, signals related to the corresponding angular positions can be generated in the receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32 through induction. The formation of these signals requires that excitation wires 1.4, 1.5, and 1.6 generate time-alternating electromagnetic excitation fields in the region of the scanning indexing structure. In the illustrated embodiment, excitation wires 1.4, 1.5, and 1.6 are designed as multiple individually printed wires parallel to each other in a plane and carrying current. Scanning element 1 has electronic circuitry, which may include, for example, an ASIC (Application-Specific Integrated Circuit) module. The electronic circuitry of scanning element 1 functions not only as an evaluation element but also as an excitation control element, generating an excitation current under its control. This excitation current then flows through the excitation wires 1.4, 1.5, and 1.6 or through the individually printed wires. Excitation leads 1.4, 1.5, and 1.6 are therefore energized by the same excitation control element.

[0051] If excitation wires 1.4, 1.5, and 1.6 are energized, a flexible or cylindrical electromagnetic field is formed around the corresponding excitation wires 1.4, 1.5, and 1.6. The field lines of the generated electromagnetic field extend in the form of concentric circles around the excitation wires 1.4, 1.5, and 1.6, with the direction of the field lines related to the direction of the current in the excitation wires 1.4, 1.5, and 1.6 in a known manner and method. Eddy currents are induced in the region of the contact 2.11, thereby achieving angular positioning. Related field modulation. Accordingly, the relative angular position can be measured via receiver tracks 1.1, 1.2, and 1.3, respectively. The receiver rails 1.11, 1.12, 1.21, 1.22, 1.31, and 1.32 are arranged in pairs within their respective receiver rails 1.1, 1.2, and 1.3, so that they each provide signals with a 90° phase shift, thereby enabling the determination of the rotation direction. However, the angular position thus derived from a single receiver rail 1.1, 1.2, or 1.3... It typically has an undesirable large error, which is corrected or eliminated by means of measurements from other receiver tracks 1.1, 1.2, 1.3, for example by averaging.

[0052] However, the receiver tracks 1.1, 1.2, and 1.3 detect not only the relative position or angular position in the first direction x. It also detects the relative position between the scale element 2 and the scanning element 1 in the second direction z. For this purpose, the corresponding individual measurements of receiver tracks 1.1, 1.2, and 1.3 are compared with the (corrected) angular positions determined from all three receiver tracks 1.1, 1.2, and 1.3. Related.

[0053] Therefore, it can also be used to detect angular position. With excitation wires 1.4, 1.5, 1.6 and receiver tracks 1.1, 1.2, 1.3, the position measuring device can detect the relative position of the scale element 2 in a second direction z parallel to axis A.

Claims

1. An inductive position measuring device, the inductive position measuring device having a scanning element (1) and a scale element (2), wherein, The position of the scanning element (1) relative to the scale element (2) in the first direction (x) and the second direction (z) can be determined by the inductive position measuring device, wherein, The scale element (2) includes indexing structures (2.1) arranged sequentially along the first direction (x), wherein the indexing structures (2.1) have a periodic orientation along the second direction (z), the periodic orientation having a second period length (Dz), and The scanning element (1) includes a first receiver track (1.1), a second receiver track (1.2), and a third receiver track (1.3), as well as excitation wires (1.4, 1.5, 1.6), wherein, Each of the first receiver track (1.1), the second receiver track (1.2), and the third receiver track (1.3) has two receiver rails (1.11, 1.12, 1.21, 1.22, 1.31, 1.32), which have a periodic orientation along the first direction (x) with a first period length (Px). The first receiver track (1.1), the second receiver track (1.2), and the third receiver track (1.3) are staggered from each other in the second direction (z). The first receiver track (1.1) is offset from the second receiver track (1.2) in the second direction (z) by a first track offset (Pz12), and the first track offset (Pz12) is not equal to n times the second period length (Dz), where n is a natural number, i.e., Pz12 ≠ n·Dz.

2. The inductive position measuring device according to claim 1, wherein, The second receiver track (1.2) is offset by a second track offset (Pz23) relative to the third receiver track (1.3) in the second direction (z), and the second track offset (Pz23) is not equal to n times the second period length (Dz), where n is a natural number, i.e., Pz23≠n·Dz.

3. The inductive position measuring device according to claim 2, wherein, The first orbital offset (Pz12) or the second orbital offset (Pz23) is equal to n times the second period length (Dz) divided by another natural number m, i.e. Pz12 = n·Dz / m, where n≠m, or Pz23 = n·Dz / m, where n≠m.

4. The inductive position measuring device according to claim 3, wherein, The other natural number m is equal to 3, that is Pz12 = n·Dz / 3, where n≠3, or Pz23 = n·Dz / 3, n≠3.

5. The inductive position measuring device according to claim 1 or 2, wherein, The first receiver track (1.1) is offset by a first track offset (Pz12) in the second direction (z) relative to the second receiver track (1.2), and the second receiver track (1.2) is offset by a second track offset (Pz23) in the second direction (z) relative to the third receiver track (1.3), wherein the first track offset (Pz12) and the second track offset (Pz23) are equal, i.e., Pz12 = Pz23.

6. The inductive position measuring device according to claim 1 or 2, wherein, The indexing structure (2.1) is arranged periodically along the first direction (x) with an indexing period (Dx), wherein the length of the indexing period (Dx) is similar to or exactly equal to the length of the first period (Px), thus making it suitable for: 0.75·Dx≤Px≤1.25·Dx.

7. The inductive position measuring device according to claim 1 or 2, wherein, The indexing structure (2.1) has a sinusoidal orientation along the second direction (z).

8. The inductive position measuring device according to claim 1 or 2, wherein, The indexing structure (2.1) is designed as a tab (2.11) and a gap (2.12).

9. The inductive position measuring device according to claim 1 or 2, wherein, The receiver rails (1.11, 1.12, 1.21, 1.22, 1.31, 1.32) have a sinusoidal orientation along the first direction (x).

10. The inductive position measuring device according to claim 1 or 2, wherein, The scale element (2) is rotatable relative to the scanning element (1) about an axis (A) that extends parallel to the second direction (z) and the first direction (x) extends in a circumferential direction.

11. The inductive position measuring device according to claim 10, wherein, The scale element (2) is designed as a cylindrical shape.

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