DE102020128013A1 - Coil arrangement for a sensor device for determining a position of an object along a sensitive axis of the sensor device - Google Patents

Abstract

A coil arrangement (10) for a sensor device (40) for determining a position (P) of an object (O) along a sensitive axis (S) of the sensor device (40) is described, the coil arrangement (10) having a flat excitation coil (12 ) and at least one receiving coil (14), the windings (18) of which are arranged around windings (16) of the excitation coil (12), essentially perpendicular to the windings (16) of the excitation coil (12) and symmetrically with respect to a center line (M) of the Excitation coil (12) are arranged, which runs along a sensitive axis (S) of the sensor device (10).

Description

The invention relates to a coil arrangement for a sensor device for determining a position of an object along a sensitive axis of the sensor device, such a sensor device and a method for operating the sensor device.

State of the art

It is known from practice that in the case of inductive position sensors, an alternating magnetic field from an excitation coil acts on an electrically conductive and/or magnetizable object in such a way that electrical eddy currents and alternating magnetic polarization are generated in the object, resulting in a magnetic field of the object that changes over time produce. This magnetic field in turn acts on one or more receiving coils of the position sensor and induces a voltage in them. The position of the object relative to the sensor device can be determined from the induced voltage or voltages.

The inductive position sensor device with the product designation BIP ED2-B133-03-S75 from Balluff GmbH, Neuhausen a.d.F., is designed as a serial sensor with a planar coil system manufactured using printed circuit board technology. The coil system has an excitation coil and a number of structured planar receiving coils. In order to determine the object's position with respect to the sensor device, the perpendicular component of the object's magnetic field acting on the coil plane is used. The amplitude and the phase of the induced voltage in each of the receiving coils is dependent on the object position. The measuring range is up to about 130 millimeters (mm).

Position sensor devices of the type, e.g. the product designations BIP CD2-B014-01-EP02 and BIP LD2-T040-02-S4 from Balluff GmbH, Neuhausen a.d.F., are implemented with coils that are wound in a row on a ferrite core. Each coil is successively oscillated by a common oscillator circuit, and a relative object position is determined from detected amplitudes of oscillation. A measuring range is about 14 to 40 mm and depends on the sensor type.

The position sensor devices based on the technologies described above have a blind zone at both end regions seen along the receiving coils, resulting in a limited measurement range-to-sensor size ratio. It is therefore difficult to miniaturize such types of sensor devices.

Furthermore, it can be difficult to install such types of sensor devices flush in an environment, since a metal-free zone around the sensor device must be provided when installing the sensor device in the environment.

There is consequently a need for a new concept and operation of a sensor device which is small in size and at the same time has a large measuring range, for example a size of about 15 mm long and about 10 mm wide with a measuring range of about 10 mm.

Disclosure of Invention

It is an object of the present invention to provide a small sensor device with a large measuring range at the same time, for example a size of about 15 mm in length and about 10 mm in width with a measuring range of about 10 mm.

According to a first aspect, a coil arrangement is provided for a sensor device for determining a position of an object along a sensitive axis of the sensor device, the coil arrangement having a flat excitation coil and at least one receiving coil, the turns of which are arranged around turns of the excitation coil, essentially perpendicular to the turns of the excitation coil and are arranged symmetrically with respect to a center line of the excitation coil which runs along the sensitive axis of the sensor device.

The coil arrangement can therefore have a coil plane which can be defined by the flat excitation coil. The center line of the excitation coil can run in the plane of the coil and extend along the sensitive axis. The at least one receiving coil can surround the excitation coil, since the turns of the at least one receiving coil can be arranged around the turns of the excitation coil. The windings of the at least one receiving coil can be arranged around the windings of the excitation coil and can be supported mechanically on them. Alternatively, the two coils can be arranged at a distance from one another (e.g. slightly) so that the excitation coil does not support the at least one receiving coil mechanically, but can only specify a position of a coil body of the at least one receiving coil with respect to the excitation coil. Furthermore, the windings of the at least one receiving coil can run essentially perpendicular to the windings of the excitation coil and thus essentially perpendicular to the center line of the excitation coil. The at least one Emp The capture coil can be arranged symmetrically around the center line of the excitation coil, so that the windings of the at least one receiving coil can extend the same distance from the center line on both sides of the center line or can be as far apart as possible when viewed from above on the at least one receiving coil.

When the sensor device is in operation, the coil arrangement can be arranged in the vicinity of an electrically conductive and/or magnetizable object in such a way that the center line of the excitation coil and thus the sensitive axis can be aligned parallel to the assumed line of movement of the object. The excitation coil can be excited with alternating current, with an oscillating current (for example a sinusoidal current), current pulses or a current with a different course over time. Due to this excitation of the excitation coil, the excitation coil can form a magnetic field, which in turn can induce eddy currents and/or magnetic polarization in the object. The object can consequently form a magnetic field that changes over time, which can also have a non-vanishing component in the direction of the center line of the excitation coil and thus the sensitive axis. Since the windings of the at least one receiving coil can be arranged essentially perpendicular to this direction, the voltage that can be induced in the receiving coil can occur in the receiving coil according to the longitudinal component of the object field lines.

The excitation coil can preferably be excited during operation with a harmonically oscillating sinusoidal current. The magnetic field that can be induced around the object can be similar to a magnetic dipole, which can oscillate harmonically at the same frequency and have a phase that can be determined primarily by the electrical and magnetic properties of the object. If, in the case of a receiving coil, the object moves at a substantially constant distance from the coil plane or from an end face of a housing of the sensor device accommodating the coil arrangement, which faces the object, into an overlapping area of the receiving coil, the sinusoidal amplitude of the induced Voltage in this receiving coil will first increase and then fall to zero as the object moves towards a center point of the receiving coil. If the object moves further beyond a center point of the receiving coil, the amplitude of the voltage with the opposite sign or phase can increase again. If the object moves further away from the receiving coil, the induced voltage can drop again. By evaluating the induced voltage between the two extreme values of its amplitude, the position of the object relative to the coil arrangement and thus to the sensor device that the coil arrangement can have can be determined. If the length of the sub-area of the excitation coil that includes the receiving coil is relatively small in relation to the distance between the two extreme values, the previously described anti-symmetrical course of the signed amplitude is called the "single characteristic" of the narrow receiving coil. If there is more than one receiving coil, the distance between the object and the front face of the sensor device does not necessarily have to be constant along the line of movement of the object, but the distance can vary.

An axial or longitudinal position of the object viewed along the center line of the excitation coil with respect to the sensor device can be determined by means of sensor electronics of the sensor device, for example by using techniques according to FIG EP 3 108 211 B1 or CN 106104210B , in which a determination of the position from the induced voltage(s) demodulated with the correct sign is performed in the receiving coil(s) by means of multi-phase quadrature demodulation, and/or techniques according to FIG U.S. 2017/344878 A1 be applied in which a joint evaluation of at least two signals is carried out by means of an artificial neural network.

Due to the simultaneous continuous demodulation of the voltage induced in the receiving coil or the voltages induced in the receiving coil, the sensor device can have a short response time, which is also used to determine a position of a rotating object (e.g. a spindle) with a rotational speed of, for example, more than 40,000 revolutions per minute (e.g. a rotating rotating spindle) may be appropriate.

Furthermore, the sensor device, which can have a shield in particular, can be installed flush in a metallic environment, for example a machine wall, with little or no metal-free zone, while the sensor device can be designed to be particularly small.

The coil arrangement with an excitation coil and one or more receiving coils can also be realized in a small size and with a favorable measurement range-to-sensor size ratio. In particular, it may be possible to use a sensor device with a size of about 15 mm in length and about 10 mm wide with a measuring range of about 10 mm.

In one embodiment, the excitation coil can have an elongated cross section, in particular a substantially rectangular cross section, and the center line can run along a longitudinal extension of the excitation coil. In other words, the turns of the excitation coil can run along its length. The line of motion along which the object can move can run along the longitudinal direction and parallel to the center line of the excitation coil.

In one embodiment, the excitation coil can be bent or curved when viewed along its longitudinal extension (in particular semicircular or with another monotonous curvature characteristic). The line of movement or the trajectory of the object can then also be curved in order to follow the curved center line of the excitation coil. In such an embodiment, for example, an angular offset of a rotatable object can be detected.

Consequently, the coil arrangement according to the two aforementioned embodiments and thus the sensor device can be used for a large number of different object arrangements.

In one embodiment, a winding density of the at least one receiving coil viewed along the center line of the excitation coil can be constant in at least a partial area of the at least one receiving coil or in the entire at least one receiving coil. As a result, the coil arrangement can be of very simple construction. The length of the sub-area or the length of the receiving coil, seen along the center line of the excitation coil, should in particular be smaller than the distance between the two extreme values of the individual characteristic curve of the receiving coil, so that an exact position determination can be made possible.

In one embodiment, the winding density of the at least one receiving coil can vary or change as seen along the center line of the excitation coil. The variation of the winding density along the centerline can, for example, follow a periodic, position-dependent function (e.g. a binary function).

In one embodiment, the winding density of the at least one receiving coil can alternate between a first winding density, in particular a high winding density, and a second, different winding density, in particular a low winding density, viewed along the center line of the excitation coil.

In one embodiment, a winding direction of the at least one receiving coil seen along the center line of the excitation coil can be the same in at least a partial area of the at least one receiving coil or in the entire at least one receiving coil. As a result, the coil arrangement can be of very simple construction,

In one embodiment, the winding direction of the at least one receiving coil can vary or change as seen along the center line of the excitation coil. In other words, the winding direction along the center line can be in opposite directions in different partial areas of the receiving coil or coil areas. The voltage induced in such a receiving coil can be understood as a sum of the spatially offset individual characteristic curves of the coil parts, each with a sign according to the winding direction. As a result, the induced voltage can have a further characteristic that can be used to determine the position.

The receiving coil can, for example, have periodically alternating sub-areas with turns and sub-areas without turns. It is also possible for the winding direction to be in the opposite direction in the successively wound partial areas (or coil parts). The characteristic of such a receiving coil, i.e. the object position dependence or in other words the location dependence of the voltage induced in the receiving coil, demodulated with the correct sign, can then be a sum of the spatially offset individual characteristic curves of the coil parts, depending on the sign according to the winding direction. For example, a receiving coil with periodically arranged essentially identical coil parts (except for the coil ends) can have an essentially periodic characteristic.

In one embodiment, the sensor device may have a plurality of receiving coils, wherein turns of the plurality of receiving coils may be arranged around the turns of the excitation coil, substantially perpendicular to the turns of the excitation coil and symmetrically with respect to the centerline of the excitation coil. In this case, each of the plurality of receiving coils can be designed as described above and optionally arranged with respect to the excitation coil and/or the object. As a result, a wide area of the excitation coil can be covered with a receiving coil along its center line and each receiving coil can have a clear individual characteristic, so that overall a good position determination tuning can be possible over a large area.

In one embodiment, receiving coils of the plurality of receiving coils may be spaced from each other as viewed along the centerline of the excitation coil and may be disposed around different portions of the turns of the excitation coil. If the multiple receiving coils are arranged with sufficiently overlapping individual characteristic curves relative to one another, an approximately equally good position determination for the object can be carried out with reduced construction costs by evaluating the induced voltage of two or more adjacent receiving coils. For example, if to determine the longitudinal position of the object the polyphase quadrature demodulation algorithm as described in CN 106104210B is applied, the individual characteristic curves can sufficiently overlap if the distance between centers of the adjacent receiving coils can definitely be less than the longitudinal distance between the extreme value points of the individual characteristic curves.

In one embodiment, a first receiving coil (or multiple first receiving coils) of the plurality of receiving coils may be arranged around a second receiving coil (or multiple second receiving coils) of the plurality of receiving coils, and one or more portions of the first receiving coil(s) having a first turn density , for example a high turn density or a low turn density, may cover one or more sections of the second receiving coil(s) with a second turn density, for example a low turn density or a high turn density. A high-resolution incremental position determination can be carried out with a coil arrangement with an excitation coil and two similar receiving coils, which are offset by a quarter period as seen along the center line of the excitation coil and have periodic sub-regions as described above (with or without changing the winding direction).

One or more receiving coils of the plurality of receiving coils can be designed with the same or varying winding density, as described above for the at least one receiving coil. In this case, one or more other receiving coils of the plurality of receiving coils can be designed with a varying or the same winding density as described above for the at least one receiving coil.

Additionally or alternatively, one or more receiving coils of the plurality of receiving coils can have an identical or varying winding direction, as described above for the at least one receiving coil. In this case, one or more other receiving coils of the plurality of receiving coils can have a varying or the same winding direction as described above for the at least one receiving coil.

It is also possible for all receiving coils of the plurality of receiving coils to have the same winding density and/or the same winding direction.

The receiving coils of the plurality of receiving coils can also be arranged in opposite directions along the center line, so that the winding density of the two receiving coils is point-symmetrical with respect to the center point of the excitation coil and/or the winding direction of the two receiving coils is opposite when viewed along the center line.

In one embodiment, the excitation coil can be formed as a (wound) wire coil or the excitation coil can be formed in and/or on one or more layers of a printed circuit board.

In one embodiment, the at least one receiving coil (or the or all receiving coils of the plurality of receiving coils) can be embodied as a (wound) wire coil, or the at least one receiving coil (or the or all receiving coils of the plurality of receiving coils) can be in and/or on be formed several layers of a printed circuit board.

While a wire coil can enable a particularly high number of turns and thus a large amplitude of the induced voltage, coils manufactured using printed circuit board technology, which can have a limited maximum number of turns in terms of manufacturing technology, can be produced particularly inexpensively. Due to the limited number of turns of the receiver coil, which is manufactured using printed circuit board technology, this coil can also have a low signal-to-noise ratio.

Using multiple layers of circuit board for the excitation coil can increase the technically manufacturable number of turns of the excitation coil. One half of the coil can be realized in a first layer and another half of the coil can be realized in a directly adjacent second layer. In the case of excitation coils with many turns, these can also be manufactured in three or more layers of the printed circuit board.

In one configuration, the excitation coil can be manufactured using printed circuit board technology (i.e. in or on one or more layers of a printed circuit board), while the receiving coil or coils can be designed as a wire coil, which can be arranged around the printed circuit board . On the one hand, this hybrid implementation of the coil arrangement can be particularly cost-effective and, at the same time, enable a large voltage amplitude for determining the position.

According to a second aspect, a sensor device is provided for determining a position of an object along a sensitive axis of the sensor device, the sensor device having a coil arrangement according to the first aspect.

The sensor device can also have sensor electronics with which the position can be determined.

In one embodiment, a separate circuit of the sensor electronics can be available for each separate receiving coil. As a result, the position determination can be simplified since the signals of the different reception coils can be detected.

In one embodiment, the sensor device can have a lateral, electrically conductive shielding element, which laterally surrounds the coil arrangement continuously and symmetrically. The coil assembly may be located entirely behind the top surface of the side shield. The shielding element can be arranged essentially perpendicular to the end face of the sensor device. An opening of the shielding element, which can point towards the object during operation of the sensor device, can be arranged parallel to the end face of the sensor device.

In one embodiment, the sensor device can have a planar, electrically conductive shielding element that is arranged on a side of the coil arrangement that faces away from the object. This shielding element can be designed as a rear shielding plate. The lateral shielding element and the planar shielding element can be made in one piece. The planar shielding element can be arranged essentially parallel to the end face of the sensor device.

Due to the lateral shielding element and/or the planar shielding element, the coil arrangement can be integrated in a magnetic environment, for example in a machine wall, without an interfering background signal being able to be induced in the receiving coil by the metallic environment.

According to a third aspect, a method for operating a sensor device for determining a position of an object along a sensitive axis of the sensor device is provided, the sensor device having a coil arrangement which has a flat excitation coil and at least one receiving coil, the turns of which are around turns of the excitation coil. are arranged essentially perpendicular to the windings of the excitation coil and symmetrically with respect to a center line of the excitation coil that runs along the sensitive axis of the sensor device, the object being moved at a distance from the sensor device along a line of movement that is essentially perpendicular to the windings of the at least one receiving coil runs.

If the excitation coil is excited with an oscillating current, the phase of the oscillation of the object's magnetic field can define a phase in which the voltage induced in the receiving coil(s) oscillates with the greatest amplitude. In a position determination, this phase of the induced voltage can be defined as the "sense phase" and the sensed voltage amplitude can be defined as a signed quantity having the same amplitude as the amplitude of the induced voltage in the sense phase and a sign according to the polarity of the induced voltage tension in the acquisition phase.

character list

• 1 zeigt schematisch eine Spulenanordnung gemäß einem ersten Ausführungsbeispiel für eine Sensorvorrichtung zum Ermitteln einer Position eines Objekts relativ zur Sensorvorrichtung in perspektivischer Ansicht;
• 2 zeigt schematisch eine Spulenanordnung gemäß einem zweiten Ausführungsbeispiel in perspektivischer Ansicht;
• 3 zeigt schematisch eine Spulenanordnung gemäß einem dritten Ausführungsbeispiel in perspektivischer Ansicht;
• 4A, 4B und 4C zeigen schematisch eine Anregungsspule und eine erste und zweite Empfangsspule für eine Spulenanordnung gemäß einem vierten Ausführungsbeispiel in Draufsicht auf verschiedene Leiterplattenschichten und im Querschnitt;
• 5 zeigt schematisch eine Spulenanordnung gemäß einem fünften Ausführungsbeispiel in Draufsicht;
• 6A, 6B, 6C zeigen schematisch eine Spulenanordnung gemäß einem sechsten Ausführungsbeispiel in Draufsicht;
• 7 zeigt schematisch eine alternative Realisierung der Empfangsspule der in 6B, 6C gezeigten Spulenanordnung in Draufsicht;
• 8 zeigt schematisch eine Spulenanordnung gemäß einem siebten Ausführungsbeispiel in Draufsicht;
• 9 zeigt schematisch die Sensorvorrichtung gemäß einem Ausführungsbeispiel mit einer zu 3 ähnlichen Spulenanordnung mit drei Empfangsspulen und einer Sensorelektronik;
• 10 zeigt schematisch ein Abschirmelement und die Spulenanordnung der Sensorvorrichtung in 9;
• 11A, 11B, 11C zeigen schematische Diagramme, die Quadratur-Phase-Amplituden von erfassten Spannungen in Empfangsspulen der Spulenanordnung in 9, die in einer Maschinenwand bzw. alleinstehend ist, in Abhängigkeit einer Objektposition zeigen; und
• 12 zeigt ein schematisches Diagramm, das die ermittelte longitudinale Position des Objekts in Abhängigkeit der reellen Objektposition zeigt.

Embodiments of the invention are shown in the drawings and explained in more detail in the following description. Show it:

• 1 shows schematically a coil arrangement according to a first embodiment for a sensor device for determining a position of an object relative to the sensor device in a perspective view;
• 2 shows schematically a coil arrangement according to a second embodiment in a perspective view;
• 3 shows schematically a coil arrangement according to a third embodiment in a perspective view;
• 4A , 4B and 4C 12 schematically show an excitation coil and a first and second receiving coil for a coil arrangement according to a fourth exemplary embodiment in top view of different circuit board layers and in cross section;
• 5 shows schematically a coil arrangement according to a fifth embodiment in plan view;
• 6A , 6B , 6C show schematically a coil arrangement according to a sixth embodiment in plan view;
• 7 shows schematically an alternative realization of the receiving coil of FIG 6B , 6C shown coil arrangement in plan view;
• 8th shows schematically a coil arrangement according to a seventh embodiment in plan view;
• 9 shows schematically the sensor device according to an embodiment with a to 3 similar coil arrangement with three receiver coils and sensor electronics;
• 10 shows schematically a shielding element and the coil arrangement of the sensor device in FIG 9 ;
• 11A , 11B , 11C show schematic diagrams showing the quadrature phase amplitudes of detected voltages in receiving coils of the coil arrangement in FIG 9 , which is in a machine wall or stand alone, depending on an object position; and
• 12 shows a schematic diagram showing the determined longitudinal position of the object as a function of the real object position.

Embodiments of the invention

Identical or similar components or elements are provided with the same reference symbols.

one inside 1 The coil arrangement shown and provided with the reference numeral 10 according to a first exemplary embodiment for a sensor device for determining a position of an object O relative to the sensor device has a flat excitation coil 12 and a receiving coil 14 . The excitation coil 12 is designed as a wound wire coil with an essentially rectangular cross-section, viewed in a coil plane, viewed along its longitudinal extension. Windings 16 of the excitation coil 12 run in the direction of the longitudinal extent of the excitation coil 12. A center line M of the excitation coil 12 in the coil plane corresponds to a longitudinal axis L of the excitation coil 12 and thus of the coil arrangement 10. The receiving coil 14 also has a substantially rectangular cross section perpendicular to the coil plane . Windings 18 of the receiving coil 14 embodied as a wound wire coil are arranged around the windings 16 of the excitation coil 12 such that the windings 16 run perpendicularly to the elongate windings 18 when viewed along the center line M. The windings 18 are also arranged symmetrically with respect to the center line M of the excitation coil 12, so that the windings 18 are centered around the center line M when viewed from the plane of the coil, and short winding end sections provided on both sides of the center line M, on which the respective windings bend, have an equal width distance from the center line. The receiving coil 14 only covers a narrow longitudinal region of the excitation coil 12 viewed along the center line M. A turn density of the receiving coil 14 is constant as seen along center line M. FIG. Alternatively, the turn density along the centerline M of the excitation coil 12 may vary. Furthermore, a winding direction of the windings 18 of the receiving coil 14 seen along the center line M is constantly the same. Sensor electronics of the sensor device can be connected to connections 20a, 20b of the excitation coil 12 or 22a, 22b of the receiving coil 14, which are designed as soldering contacts on an end area of the coils 12, 14.

The object O can be arranged at a fixed distance D from a plane of the coil arrangement 10 on one side of the coil arrangement. It goes without saying that if the sensor device has a housing in which the coil arrangement 10 is accommodated, the distance D between an end face of the housing pointing towards the object O and the object can be dimensioned. The object O is movable along a fixed line of motion parallel to the center line M corresponding to a sensitive axis S of the sensor device. The sensor device is set up to determine an axial position P of the object O along the sensitive axis S, for example starting from the center point MP of the excitation coil 12 .

This in 2 The embodiment shown is similar to the embodiment in FIG 1 educated. However, instead of a single, narrow receiving coil 14, two narrow receiving coils 14a, 14b are provided, which are arranged at a distance from one another. The receiving coils 14a, 14b are provided in different partial areas 24 of the windings 16 of the excitation coil 12. While partial areas 24a, 24c and 24e are not covered by the reception coils 14a, 14b, the reception coils 14a, 14b cover the partial areas 24b, 24d. A winding density of the two receiving coils 14a, 14b is constant when viewed along the longitudinal extension.

In the 3 The coil arrangement 10 shown according to the third exemplary embodiment is similar to the coil arrangement 10 in FIG 1 educated. However, the excitation coil 14 is not designed as a wire coil, but as conductor tracks (shown in broken lines) in a printed circuit board 26 . The printed circuit board 26 is designed in one layer, so that the windings 16 are structured in a surface 27 of the printed circuit board 26, which can be arranged adjacent to the object O. Alternatively or additionally, conductor tracks of the excitation coil 12 can be arranged on the surface 27 . Connections 20a, 20b are not designed as solder contacts but as contact areas in and/or on the printed circuit board 26. Instead of a receiving coil 14, three narrow receiving coils 14a, 14b, 14c spaced apart from one another are provided, which are wound around the printed circuit board 26. Windings 18a, 18b and 18c of the receiving coils 14a, 14b and 14c are implemented in partial areas 24b, 24d, 24f of windings 16 of the excitation coil 12, while partial areas 24a, 24c, 24e, 24g of the windings 16 of the excitation coil 12 are uncovered. A winding density of the three receiving coils 14a-14c is constant as viewed along the center line M in each case.

In the 4 The coil assembly 10 shown is similar to the coil assembly 10 in FIG 3 educated. The printed circuit board 26 is formed by means of four layers 28a-28d lying one on top of the other. The excitation coil 12 is formed in two parts. One half 12a of the excitation coil 12 (solid lines in 4A ) is in the inner circuit board layer 28c and a second half 12b of the excitation coil 12 (dashed lines in 4A ) in the inner circuit board layer 28b, which is directly adjacent to the circuit board layer 28c. The two coil halves 12a, 12b are connected to one another via a corresponding plated-through hole or via 29. In addition to the contact surfaces 20a, 20b, the excitation coil 12 has external connections 30a, 30b at its winding ends, which are designed as cables with associated soldering contacts. Furthermore, the coil arrangement 10 has only two receiving coils 14a-14b instead of three receiving coils 14a-14c. Turns 18a, 18b of the first and second receiver coils 14a, 14b, respectively, extend in the circuit board layer 28a (solid lines in 4B ) or in the circuit board layer 28d (dashed lines in 4B ), which surround the two circuit board layers 28b, 28c on both sides. The conductor tracks of the receiving coils 14a, 14b also break through the layers 28b, 28c by means of plated-through holes or vias 31a-31d. Seen along the longitudinal axis L, a winding density of the two receiving coils is constant. External connections 32a-32d, which are in the form of cables with end solder contacts, are connected to the contact surfaces 22a-22d of the receiving coils 14a, 14b.

In the 5 The coil arrangement 10 shown according to the fifth exemplary embodiment is similar to the coil arrangement 10 in FIG 2 educated. However, the excitation coil 12 does not have a rectangular cross section, but rather a semicircular cross section in the plane of the coil. Instead of two spaced-apart receiving coils 14a, 14b, three spaced-apart receiving coils 14a-14c are provided with a constant winding density of receiving coils 14a, 14b, 14c, which can each be connected to a different circuit of sensor electronics via their respective connections 22a-22f. The object O can be moved parallel to the center line M at a fixed distance D from the coil plane. The object O can also be movable at a variable distance D since more than one receiving coil 14a-14c is provided.

one inside 6 The coil assembly 10 shown is similar to the coil assembly 10 in FIG 1 educated. However, the coil arrangement has a first and second receiving coil on 14a, 14b. The first receiving coil 14a is wound around the excitation coil 12, while the second receiving coil 14b is wound around the excitation coil 12 and the first receiving coil 14a. Windings 18a, 18b of the two receiving coils 14a, 14b extend along the entire length of an excitation coil 12. A winding density of the first receiving coil 14a alternates between a large winding density and a small winding density viewed along a center line M of the excitation coil 12, so that the winding density is large in partial areas 34a, 34c, 34e, 34g, 34i, 34k, 34m, 340, 34q of the first receiving coil 14a that are spaced apart from one another and the winding density in partial areas 34b, 34d, 34f, 34h, 34j, 341, 34n, 34p that are spaced apart from one another, 34r of the first receiving coil 14a is small. The second receiving coil 14b is wound around the first receiving coil 14a and is constructed and arranged similarly to the first receiving coil 14a. However, a winding density of the second receiving coil 14b seen along the center line M is small in partial areas 36a, 36c, 36e, 36g, 36i, 36k, 36m, 36o, 36q, 36s of the second receiving coil 18b and a winding density in partial areas 36b, 36d, 36f, 36h, 36j, 36I, 36n, 36p, 36r of the second receiving coil 14b is large. The first and second receiving coils 14a, 14b are offset from one another along the center line M by a quarter period which is determined by the change in winding density. A sensor device with such a coil arrangement 10 is particularly advantageous if the period corresponds approximately twice to the distance between the two extreme values of the individual characteristic curve of a tightly wound coil part, so that the spatial profile of the signed amplitudes of the two receive coils resembles a sine-cosine functional pair common in high-resolution incremental encoder technology.

the inside 7 The section of the coil arrangement 10 shown represents an alternative type of winding for realizing the receiving coil 14a and/or 14b of the coil arrangement 10 in 6 The winding density of the receiving coil 14a and/or 14b seen along the center line M follows a binary function. In other words, partial areas 34b, 34d with a high winding density and partial areas 34a, 34c, 34e with only one winding 18 alternate.

one inside 8th The coil arrangement 10 shown according to a seventh exemplary embodiment is similar to the coil arrangement 10 in FIG 1 educated. The excitation coil 12 is shown schematically. However, the coil arrangement 10 has two receiving coils 14a, 14b which, viewed along the center line M, are arranged in opposite directions. Both receiving coils 14a, 14b have a varying winding density viewed along the center line M, so that an outer partial area 34a or 36a of the first receiving coil 14a or the second receiving coil 14b has a higher winding density than an inner partial area 34b or 36b of the first receiving coil 14a and the second receiving coil 14b. Both receiving coils 18a, 18b additionally have a winding direction that changes as seen along the center line M. In other words, the winding direction is reversed, so that the partial area 34a, 36a of the receiving coils 14a, 14b have an opposite winding direction to the partial areas 34b, 36b. In addition, the winding direction of portion 34a is opposite to the winding direction of portion 36a, and the winding direction of portion 34b is opposite to the winding direction of portion 36b. The first receiving coil 14a and the second receiving coil 14b are also partially plugged into one another, so that a line piece 39a of the first receiving coil between the partial areas 34a, 34b through an interior of the partial area 36b of the second receiving coil 14b and a line piece 39b of the second receiving coil 14b between the partial areas 36a, 36b runs through an interior of the partial area 34b of the first receiving coil 14b.

It goes without saying that the winding direction in at least one or all of the receiving coils 14 in 1 until 7 coil assemblies 10 shown can change.

one inside 9 Sensor device 40 shown has a coil arrangement 10 according to 1 until 8th and the sensor electronics, now provided with the reference numeral 42, are electrically coupled to the respective coils 12, 14 via the terminals 20, 22 and 30, 32, respectively. For illustration, the coil assembly is 10 in 3 shown. However, the excitation coil 12 is designed as a wire coil. The excitation coil 12 is connected to a circuit 43a of the sensor electronics 42 via its connections 20a, 20b. Each of the receiving coils 14a, 14b and 14c is connected to a separate circuit 43b, 43c, 43d of the sensor electronics 42 for determining the position of the object O via corresponding connections 22a, 22b, 22c, 22d, 22e, 22f. The circuits 43b-43d are designed as demodulators. Alternatively, the three receiving coils 14a-14c can be connected to only one circuit, which is designed as a demodulator and which is operable in a time-division multiplexed manner.

As in 10 shown, the coil arrangement 10 is optionally arranged in a first electrically conductive shielding element 44 of the sensor device 40, which laterally and continuously surrounds the coil arrangement 10 such that the coil arrangement 10 extends centrally in side walls 46a-46d of the shielding element 44. An open top surface 48a of the first shielding element 44 faces the object. Sensor device 10 also has a second planar, electrically conductive shielding element 50, which is designed as a shielding plate and covers an opening in a further top surface 48b of first shielding element 44, which faces away from object O, as completely as possible. The first and second shielding element 44, 50 are formed in one piece, but can alternatively also be provided as two components. The first and second shielding element 44 can, for. B. be made of copper or low magnetizable stainless steel. In an installation situation, the sensor device 40 is installed in a machine wall 52 of a machine that is made of copper or steel, for example. The sensor device 40 can be used as in 10 be built directly into the machine wall 52 as shown. It is also possible for the sensor device 40 to be accommodated in a sensor housing, the end face of which points towards the object O and is aligned parallel to the cover surface 48a of the first shielding element 44 .

When the sensor device 40 is in operation, the object O is arranged at a distance D from the coil plane of the excitation coil 12 on the side of the open top surface 48a of the shielding element 44 and, if present, the front surface of the sensor housing. An axial position P of the object O with respect to the sensor device 40 is determined by means of the sensor electronics 42, for example by using techniques according to FIG EP 3 108 211 B1 or CN 106104210B , in which the position P is determined from an amplitude of the voltage in the receiving coils 14, demodulated with the correct sign, by means of multi-phase quadrature demodulation, and/or U.S. 2017/344878 A1 be used in which a joint evaluation of two signals is carried out using an artificial neural network.

In 11A , 11B is the signed amplitude of the quadrature-phase component of the induced voltage in the receiving coils 14a, 14b, 14c of the coil arrangement 10 in 10 shown as a function of the object position P. An x-axis 70 indicates the position P in millimeters and a y-axis 72 indicates the amplitude of the voltage in arbitrary units. Curves 74a1-74a3, 74b1-74b3, 74c1-74c3 in 11A denote the amplitude of the voltages in the three receiving coils 14a-14c for a sensor device 40 without shielding element 44 in a state not integrated in the machine wall 60 (solid line), in a steel machine wall (dashed line) and in a copper machine wall installed state (dotted line). In 11B Corresponding curves 76a1-76a3, 76b1-76b3, 76c1-76c3 are shown for the sensor device 40 with shielding element in the uninstalled state, in a steel and in a copper machine wall 60 installed state. It can be seen that the object-related signal component decreases significantly due to the shielding element 44, while apart from an insignificant object signal reduction in the case of the copper machine wall 60, the signal size is no longer influenced by the installation situation. There is also an offset for the first and third receiving coils 14a, 14c. However, this offset is deterministic and independent of the presence or type of machine wall 60. After the subtraction of the offset, which is typical for the non-installed situation without an object for each coil, an object position-dependent and independent of the installation situation, only the object position get characterizing signal group ( 11C )

12 shows the determined longitudinal position of the object depending on the real object position P in an application of the multi-phase quadrature demodulation algorithm EP 3 108 211 B1 . An x-axis 76 indicates the object position in millimeters and a y-axis 78 indicates the determined longitudinal position in arbitrary units. Curves 80a-80c show the determined longitudinal position for object distances of 0.25 mm, 0.5 mm and 1 mm measured perpendicularly from the end face of a sensor housing. It can be seen that the measuring range is linear and extends approximately 10 mm centered around a midpoint of the receiving coils 14 . The coil arrangement 10 is arranged behind the end face and parallel to the end face.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 3108211 B1 [0013, 0060, 0062]
• CN 106104210B [0013, 0027, 0060]
• US2017344878 A1 [0013, 0060]

Claims (18)

Coil arrangement (10) for a sensor device (40) for determining a position (P) of an object (O) along a sensitive axis (S) of the sensor device (40), the coil arrangement (10) having: - a flat excitation coil (12) and - at least one receiving coil (14) whose windings (18) around windings (16) of the excitation coil (12), substantially perpendicular to the windings (16) of the excitation coil (12) and symmetrically with respect to a center line (M) of the excitation coil ( 12) are arranged, which runs along the sensitive axis (S) of the sensor device (10). Coil arrangement (10) after claim 1 wherein the excitation coil (12) has an elongate cross section and the center line (M) runs along a longitudinal extension of the excitation coil (12). Coil arrangement (10) after claim 2 , wherein the excitation coil (12) seen along the center line (M) is curved. Coil arrangement (10) according to one of the preceding claims, wherein a winding density of the at least one receiving coil (14) seen along the center line (M) of the excitation coil (12) in at least a partial region (34) of the at least one receiving coil (14) or along the entire seen at least one receiving coil (14) is constant. Coil arrangement (10) according to one of Claims 1 until 4 , wherein a winding density of the at least one receiving coil (14) varies along the center line (M) of the excitation coil (12). Coil arrangement (10) after claim 5 , wherein the winding density of the at least one receiving coil (14) along the center line (M) of the excitation coil (12) alternates between a first winding density and a second, different winding density. Coil arrangement (10) according to one of Claims 1 until 6 , wherein a winding direction of the at least one receiving coil (14) along the center line (M) of the excitation coil (12) is the same in at least a partial area (34) of the at least one receiving coil (14) or in the entire at least one receiving coil (14). Coil arrangement (10) according to one of Claims 1 until 7 , wherein a direction of winding of the at least one receiving coil (14) varies as seen along the center line (M) of the excitation coil (12). Coil arrangement (10) according to one of the preceding claims, wherein the sensor device (40) has a plurality of receiving coils (14), wherein turns (18) of the plurality of receiving coils (14) around the turns of the excitation coil (12) around, substantially perpendicular to the windings (16) of the excitation coil (12) and symmetrically with respect to the center line (M) of the excitation coil (12). Coil arrangement (10) after claim 9 , wherein receiving coils (14) of the plurality of receiving coils (14) are arranged spaced apart from one another as seen along the center line (M) of the excitation coil (12) and are arranged around different partial regions (24) of the turns (16) of the excitation coil (12). Coil arrangement (10) after claim 9 or 10 , wherein a first receiving coil (14) of the plurality of receiving coils (14) is arranged around a second receiving coil (14) of the plurality of receiving coils (14), wherein a section (34) of the first receiving coil (14) having a first turn density has a Section (36) of the second receiving coil (14) covered with a second, different winding density. Coil arrangement (10) according to one of the preceding claims, wherein the excitation coil (12) is designed as a wire coil or wherein the excitation coil (12) is in and/or on a layer (28b, 28c) or several layers (28b 28c) of a printed circuit board (26 ) is trained. Coil arrangement (10) according to one of the preceding claims, wherein the at least one receiving coil (14) is designed as a wire coil or wherein the at least one receiving coil (14) is designed in and/or on several layers (28a-28d) of a printed circuit board (26). . Sensor device (40) for determining a position (P) of an object (O) along a sensitive axis (S) of the sensor device (40), wherein the sensor device (40) has a coil arrangement (10) according to one of Claims 1 until 13 having. Sensor device (40) after Claim 14 , wherein the sensor device (40) has a separate circuit (43a, 43b) for each receiving coil (14). Sensor device (40) after Claim 14 or 15 , wherein the sensor device (40) has a lateral, electrically conductive shielding element (44) has, which surrounds the coil arrangement (10) laterally continuously and symmetrically. Sensor device (40) according to one of Claims 14 until 16 , wherein the sensor device (40) has a planar, electrically conductive shielding element (50) which is arranged on a side of the coil arrangement (10) which faces away from the object (O). Method for operating a sensor device (40) to determine a position (P) of an object (O) along a sensitive axis (S) of the sensor device (40), the sensor device (40) having a coil arrangement (10) which has a flat excitation coil (12) and at least one receiving coil (14), the windings (18) of which surround windings (16) of the excitation coil (12), essentially perpendicular to the windings (16) of the excitation coil (12) and symmetrically with respect to a center line (M ) of the excitation coil (12) which runs along the sensitive axis (S) of the sensor device (10), the object (O) being moved at a distance from the sensor device along a line of movement along the sensitive axis (S).

Images