INDUCTIVE DISPLACEMENT AND/OR POSITION DETECTION

Abstract

The invention relates to a sensor arrangement (7) for detecting a position and/or a displacement of a flux element assembly (8) along a longitudinal direction, with a coil assembly (1) and the flux element assembly (8), wherein the coil assembly (1) comprises at least two flat coils (2a, b), wherein the flux element assembly (8) comprises at least two flux elements (9a, b), wherein the at least two flux elements (9a, b) are arranged adjacent to one another in the longitudinal direction and offset in transverse direction, wherein the flux element assembly (8) and the coil assembly (1) are movable and/or displaceable relative to one another in the longitudinal direction, wherein the flat coils (2a, b) are designed, such that an actual inductance (L.sub.1, L.sub.2) of each flat coil (2a, b) is dependent on the actual displacement of the flux element assembly (8) relative to the coil assembly (1), with an evaluation device, which is set up to determine the actual inductance (L.sub.1, L.sub.2) for each flat coil (2a, b) and determine the actual displacement based on the determined actual inductances (L.sub.1, L.sub.2).

Claims

1. A sensor arrangement (7) for detecting a position and/or a displacement of a flux element assembly (8) along a longitudinal direction, with a coil assembly (1) and the flux element assembly (8), wherein the coil assembly (1) comprises at least two flat coils (2a, b), wherein the at least two flat coils (2a, b) are arranged in a transverse direction transverse to the longitudinal direction, wherein the flux element assembly (8) comprises at least two flux elements (9a, b), wherein the at least two flux elements (9a, b) are arranged adjacent to one another in the longitudinal direction, and offset in the transverse direction, wherein the flux element assembly (8) defines a flux element plane (11) and the coil assembly (1) defines a coil plane (3), wherein the coil plane (3) is arranged at a distance from the flux element plane (11), wherein the flux element assembly (8) and the coil assembly (1) are movable and/or displaceable relative to one another in the longitudinal direction, wherein the flat coils (2a, b) are designed, such that an actual inductance (L.sub.1, L.sub.2) of each flat coil (2a,b) is dependent on the actual displacement of the flux element assembly (8) relative to the coil assembly (1), with an evaluation device, which is set up to determine the actual inductance (L.sub.1, L.sub.2) for each flat coil (2a, b) and determine the actual displacement based on the determined actual inductances (L.sub.1, L.sub.2).

2. The sensor arrangement (7) according to claim 1, wherein the flat coils (2a, b) each define a coil area and the flux elements (9a-d) each define a flux element area, wherein the flux element area and the coil area are formed congruently.

3. The sensor arrangement (7) according to claim 1, wherein the flux element assembly (8) has a plurality of flux elements (9a-d), wherein two adjacent flux elements (9a-d) are arranged offset in the longitudinal direction and in the transverse direction, wherein the flux elements (9a-d) are arranged spaced apart in the longitudinal direction relative to the flux element (9a-d) arranged adjacent thereto and without transverse offset.

4. The sensor arrangement (7) according to claim 1, wherein the flux elements (9a-d) in the flux element assembly (8) are arranged in a checkerboard fashion.

5. The sensor arrangement (7) according to claim 1, wherein the flux elements (9a-d) are designed as flat metal elements.

6. The sensor arrangement (7) according to claim 1, wherein the flux elements (9a-d) each have a measuring surface area, wherein the flux elements (9a-d) are arranged in the flux element assembly (8), such that the measuring surface areas do not overlap and are arranged without gaps in the longitudinal direction.

7. The sensor arrangement (7) according to claim 1, wherein the flux element assembly (8) has a support, wherein the flux elements (9a-d) is printed, glued, embossed, woven in and/or applied on the support.

8. The sensor arrangement (7) according to claim 7, wherein the support is designed to be flexible and/or pliable.

9. The sensor arrangement (7) according to claim 7, wherein the support forms a textile.

10. The sensor arrangement (7) according to claim 1, wherein the flat coils (2a, b) each have a winding plane, wherein the flat coils (2a, b) are arranged with their winding planes in the same direction as the flux element plane (11).

11. The sensor arrangement (7) according to claim 1, wherein the coil assembly (1) is designed to be stationary and the flux element assembly (8) is designed to be movable and/or displaceable.

12. A seatbelt arrangement for a vehicle, comprising a seatbelt and a coil assembly (1), wherein the coil assembly (1) comprises at least two flat coils (2a, 2b), wherein the flat coils are arranged transversely to the longitudinal direction, wherein the seatbelt comprises a flux element assembly (8) with at least two flux elements (9a, b), wherein the at least two flux elements (9a, b) are arranged adjacent to one another in the longitudinal direction and offset in the transverse direction, wherein the flux element assembly (8) defines a flux element plane (11) and the coil assembly (1) defines a coil plane (3), wherein the coil plane (3) is arranged spaced apart from the flux element plane (11), wherein the flux element assembly (8) and the coil assembly (1) are movable and/or displaceable relative to one another in the longitudinal direction, wherein the flat coils (2a, b) are designed, such that an actual inductance (L.sub.1, L.sub.2) of each flat coil (2a, b) is dependent on the actual displacement of the flux element assembly (8) relative to the coil assembly (1) with an evaluation device, which is set up to determine the actual inductance (L.sub.1, L.sub.2) for each flat coil (2a, b) and determine the actual displacement and/or an extraction length of the seatbelt based on the determined actual inductances (L.sub.1, L.sub.2).

13. A method for determining a displacement and/or position by means of the sensor arrangement (7) according to claim 1, wherein for each of the flat coils (2a, 2b), the actual inductance (L.sub.1, L.sub.2) is determined, and the displacement and/or position is determined based on the determined actual inductances (L.sub.1, L.sub.2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further advantages, effects and embodiments result from the attached drawings and their description. In the drawings:

[0029] FIG. 1 shows a coil assembly;

[0030] FIG. 2 shows a sensor arrangement as an embodiment of the invention;

[0031] FIG. 3 shows an inductance curve of the flat coils in FIG. 2;

[0032] FIG. 4 shows a sensor arrangement as an exemplary embodiment of the invention;

[0033] FIG. 5 shows an inductance curve for the sensor arrangement in FIG. 4.

DESCRIPTION

[0034] FIG. 1 shows an exemplary embodiment of a coil assembly 1. Coil assembly 1 comprises two flat coils 2a and 2b. The coil assembly 1 and the flat coils 2a, 2b are flat, and define a coil plane 3, wherein the windings of the flat coils 2a, 2b are situated in the coil plane 3.

[0035] Directional vectors 4a and 4b are penned in as an alternative in order to explain the sensor arrangement shown later. The longitudinal direction is oriented along the direction vector 4a, while the transverse direction is perpendicular to the longitudinal direction and is represented by the direction vector 4b. The coil plane 3 is parallel to the plane spanned by the direction vectors 4a and 4b. This plane spanned by the direction vectors 4a and 4b is also referred to as the longitudinal-transverse plane.

[0036] The flat coils 2a, 2b are arranged adjacently. In particular, the flat coils 2a, 2b are arranged immediately adjacent to one another in the transverse direction. The flat coils 2a, 2b divide the coil plane 3 in the transverse direction into two parts, also called lines 5a and 5b. In particular, the division in the transverse direction through the flat coils 2a, 2b is a half division. The flat coils 2a, 2b thus have the same surface area, in particular as regards both surface area and shape.

[0037] The flat coils 2a, 2b each have a contact 6, wherein the contact 6 is used to make contact with an evaluation device. The evaluation device is designed to determine the respective inductances L, in particular actual inductances L of the two flat coils 2a, 2b. For example, the physics and/or mathematics of an oscillating circuit are used to measure the interactivity L. For example, the flat coil 2a, 2b is supplied with AC voltage of certain frequencies by means of the evaluation device via the contact 6, and the inductance L is determined based on the reaction thereto.

[0038] FIG. 2 shows an exemplary embodiment of a sensor arrangement 7. The sensor arrangement 7 comprises the coil assembly 1 of FIG. 1. Furthermore, the sensor arrangement 7 comprises a flux element assembly 8. The flux element assembly 8 comprises two flux elements 9a and 9b. The flux elements 9a and 9b are designed as metallic flat elements. For example, the flux elements 9a and 9b are designed as copper plates. The flux elements 9a and 9b are arranged adjacent to one another, in particular they make contact in a contact area 10. Contacting in the contact area 10 takes place at corner areas of the flux elements 9a and 9b. The flux elements 9a and 9b are arranged in a common plane, i.e., the flux element plane 11. The flux element plane 11 is arranged parallel to the coil plane 3. In particular, coil plane 3 and flux element plane 11 are arranged parallel to one another. Within the flux element plane 11, the flux elements 9a and 9b are offset from one another in both the longitudinal and transverse directions. The arrangement of the flux elements 9a and 9b is in particular checkerboard-like. In other words, the arrangement of the flux elements 9a and 9b can be viewed in particular as opposing windmill blades.

[0039] The flux element assembly 8 and the flux elements 9a and 9b are displaceable in the longitudinal direction. In particular, the displacement takes place within the flux element plane and/or parallel to the coil plane 3. Moving the coil assembly 8 changes the capping and/or covering by the flux elements 9a and 9b of the flat coils 2a, 2b. Capping and/or covering refer in particular to the enclosure in a plan view from above, in particular perpendicular to the coil plane 3, of the flat coils 2a, 2b by the flux elements 9a, 9b. For example, in the embodiment shown, the flat coil 2a is completely covered and/or capped by the flux element 9a. In the embodiment shown, the flat coil 2b is not covered by either the flux element 9a or the flux element 9b. By moving the flux element assembly 8, in this example to the right, the capping of the flat coil 2a is reduced and the flat coil 2b is increasingly covered by the flux element 9b.

[0040] The inductances of the flat coils 2a, 2b depend on the coverage and/or capping by the flux elements 9a and 9b. In the example described here, the capping of a flat coil 2a, 2b increases the actual inductance L of the flat coil 2a, 2b. Accordingly, in the state shown, the measured actual inductance L1 of the flat coil 2a is greater than the actual inductance L2 of the flat coil 2b. By determining both actual inductances L1, L2, the position of the flux element 9a, 9b or the flux element assembly 8 can be determined by the evaluation device. In particular, the evaluation device is designed to determine the displacement based on this determination, e.g., as a displacement of the flux element assembly 8 relative to the coil assembly 1.

[0041] FIG. 3 shows a measured and/or expected inductance curve for the two flat coils 2a, 2b for the sensor arrangement 7 shown in FIG. 2. In the diagram, the longitudinal displacement x of the flux element assembly 8 relative to the coil assembly 1 is plotted in millimeters along the abscissa. In particular, this represents the displacement, which is measured and/or is to be determined. The inductances in nanohenry are plotted on the ordinate.

[0042] The diagram shows the inductances L1 and L2. The inductance L1 corresponds to the inductance of the flat coil 2a shown in FIG. 2. This is fully capped by the flux element 9a for a displacement of 0, such that the actual inductance L1 for x=0 is at a maximum. In this case, the maximum inductance L1 for the flat coil 2a is roughly 800 nanohenries. The inductance L2 represents the actual inductance of the flat coil 2b shown in FIG. 2. For a displacement of 0, the latter is fully uncovered and/or fully uncapped. The actual measured inductance L2 is thus minimal for x=0, since it can only increase due to increased covering. This minimum inductance for L2 is roughly 270 nanohenry. By a displacement of the flux element assembly 8, e.g., here the displacement of the flux element assembly 8 to the right in FIG. 2, the capping of the flat coil 2a decreases, such that the actual inductance L1 of the flat coil 2a decreases with increasing displacement, whereas the flat coil 2b is increasingly capped by the flux element 9b due to increasing displacement, such that increasing inductance L2 is recorded. Thus, the inductances L1 and L2 are in opposite directions, so that by measuring the actual inductances L1, L2 of both flat coils 9a, 9b, the positioning of the flux element assembly relative to the coil assembly 1 can be determined by the evaluation device.

[0043] FIG. 4 shows an exemplary embodiment of a sensor arrangement 7, which in turn comprises two flat coils 2a, 2b in a coil group 1. The coil assembly 1 is designed like the coil assembly of FIG. 1.

[0044] Unlike the sensor arrangement 7 in FIG. 2, the flux element assembly 8 here includes four flux elements 9a, 9b, 9c and 9d. The flux elements 9a, 9b, 9c and 9d are arranged in a checkerboard fashion in the flux element plane, i.e., a plane parallel to the coil plane 3. Within a line 5a, 5b, flux elements 9a, 9b, 9c and 9d each alternate with a gap. A gap in one line 5a, 5b corresponds to a flux element 9a, 9b, 9c and 9d in the other line 5b, 5a in the transverse direction.

[0045] By displacing the flux element assembly 8 longitudinally, each flat coil 2a, 2b is fully capped and fully released several times, in this case twice. The inductances L1, L2 are passed through several minima and maxima by this displacement, which are used for position determination and/or displacement determination by the evaluation device.

[0046] FIG. 5 shows the corresponding induction curve in the flat coils 2a, 2b for the sensor arrangement 7 shown in FIG. 4. The inductance L1, of the coil 2a starts at a maximum due to maximum covering at x=0 by the flux element 9a, where the inductance L1 for increasing displacement are at a minimum, i.e., when the flux element 9b completely covers the coil 2b, the next inductance L1 maximum is reached for the displacement, when the flux element 9c completely covers the coil 2a. An analogous curve is obtained for the inductance L2 of coil 2b, where it starts at a minimum for x=0, since the coil is completely uncapped by flux elements here. Based on this curve, the evaluation device determines the displacement and/or position in the longitudinal direction.

REFERENCE NUMERALS

[0047] 1 Coil assembly [0048] 2a,b Flat coils [0049] 3 Coil plane [0050] 4a,b Direction vectors [0051] 5a,b Lines [0052] 6 Contact [0053] 7 Sensor arrangement [0054] 8 flux element assembly [0055] 9a-d Flux elements [0056] 10 Contact area [0057] 11 Flux element plane [0058] L.sub.1, L.sub.2, Inductivities [0059] x Longitudinal displacement