Magnetic signaling device and component equipped therewith

Abstract

The invention relates to a magnetic signaling device (1) for measuring the movement and / or position of a rotating component (3) and the rotating component (3). According to the invention, at least one track is applied to an annular or disc-shaped carrier (13) for connection to the component (3), said track extending along the circumference, in the form of a hard magnetic layer (5-12) of a magnetizable rare earth magnetic material deposited directly in the gas phase on the carrier. The carrier (13) is made of a material having higher toughness than the material of the hard magnetic layers (5-12).

Description

Technical Field

[0001] The invention relates to a magnetic signal device for measuring a movement and / or a position of a component of a drive device, in particular a magnetic pole wheel for use in a rotational angle or rotational speed monitoring system. Background Art

[0002] Determining the angle of rotation and / or the rotational speed of rotating parts is an important task in many technical fields. The most frequently used measuring principle for high-precision applications is optical or photoelectric sensing. However, this is generally sensitive to environmental influences such as shock or vibration loads, dirt, temperature fluctuations and humidity. Special housing designs that are considered for compensation lead to certain restrictions in the installation possibilities, and the costs increase disproportionately with larger shaft diameters, so that technically and economically sensible solutions are almost no longer possible.

[0003] For measuring the rotation angle, for example, a rotary transformer, i.e. an electrical transformer, is used. The inductive coupling between the windings of the transformer varies in a manner dependent on the angle. When an alternating current signal is applied, the measurement on the windings of the transformer generates an alternating current signal, the amplitude of which is proportional to the angle. Due to their reliability, rotary transformers are often used in safety systems. However, the resolution is very strongly determined by the quality of the analog-digital conversion, so that systems based on rotary transformers are complex, often also bulky, large and expensive.

[0004] Rotary encoders with a magnetic measuring principle are suitable as an alternative. Since magnetic encoders are insensitive to shocks and vibrations as well as to dirt, temperature fluctuations and humidity, they can be used in particular in applications where the service life of optical rotary encoders is limited despite complex protective housings. These are areas of use in which rotary encoders are exposed to high temperatures, temperature fluctuations, dirt and dust loads and / or are exposed to / contaminated by chemicals and solvents.

[0005] For example, in the field of automotive technology, speed monitoring on wheels for controlling anti-lock braking systems or anti-slip control is a common technology. For this and other speed monitoring, a pole wheel and an adjacently arranged sensor are usually used, which output an oscillating signal when the pole wheel rotates relative to the sensor, and the frequency of the oscillating signal is a measure for the rotational speed of the pole wheel and therefore also for the rotational speed of the rotating parts of the vehicle or other machinery that are fixedly connected to the pole wheel. At least one magnetic track is arranged on the circumference of the pole wheel, which is evaluated by a coil or a magnetic field sensor. The pole wheel is used as a speed or angle sensor like an incremental transmitter, which is relatively insensitive to contamination and can usually be manufactured quite advantageously.

[0006] The magnetic indexing of the pole wheel and / or encoder fixed on the rotating shaft is a signal transmitter for the sensor. Such an encoder is known, for example, from EP1030181A2. The electronics are integrated in a highly protected probe head and can be completely cast if necessary. Due to the two-piece system structure with the pole wheel and the probe head, the magnetic transmitter can be used without a complex protective housing and additional ball bearings, so that a nearly wear-free solution with a very long service life can be achieved. In addition, this system does not require a free shaft end for installation and is therefore well suited for integration into an electric motor, such as an electric motor in an electric car. Publication DE102016218930A1 shows another such product. Alternatively, for example, publication DE102018217274A1 shows the manufacture of a ring comprising sintered partial magnets, which are each connected by a polymer-based intermediate piece.

[0007] Pole wheels exist in various different embodiments. Thus, for example, DE 10210372 A1 discloses a rotation angle sensor with high angular resolution, which has a magnetic track on the pole wheel, in which magnetic north poles and magnetic south poles are alternately arranged, and the position of the magnetic track relative to the torsion-resistant component is detected by a magnetic field sensor. As a possible embodiment, a pole wheel composed of plastic or synthetic resin and mixed ferromagnetic components is described, which can be easily and cheaply manufactured. The magnetic track can be composed of a magnetic ferrite film according to DE 10210372 A1, which can be easily and also cheaply manufactured. Alternatively, the magnetic track can also be made of a magnetic ferrite combined in rubber, synthetic resin or natural rubber. In addition, EP 0213732 A1 discloses a sensor system for detecting the rotation of an object, which includes a magnetic ring, which is composed of a synthetic resin and a mixed ferromagnetic material. Summary of the invention

[0008] The object of the present invention is to overcome the disadvantages of the prior art and to provide a device which offers high accuracy in a safe manner and is not susceptible to any interference and which can be used flexibly in a wide variety of areas under a wide range of conditions of use.

[0009] This technical task is achieved by the magnetic signaling device according to the claims, further features of which can be seen from the description and the drawings.

[0010] The device according to the invention is based on a magnetic signal device for measuring the movement and / or position of a rotating component, in particular a component of a drive device, which comprises an annular or disk-shaped carrier for connection to the component and at least one magnetic track, which extends along the circumference, in the form of a magnetizable hard magnetic layer deposited directly on the carrier from the gas phase, the hard magnetic layer having at least 75% by weight of a rare earth magnetic material, preferably one or more of the compounds NdFeB and / or Co5Sm and / or Co17Sm2, the layer having a magnetic structure in the direction of rotation after magnetization, which can be measured by a sensor. The proportion of the respective rare earth metal itself is preferably less than 75% by weight of the hard magnetic layer.

[0011] In order to achieve the stated object, the signaling device is characterized according to the invention in that the carrier is made of a material that has a higher toughness than the material of the hard-magnetic layer. The small layer thickness of the hard-magnetic layer and the fact that the hard-magnetic layer is applied to a tough material limit the brittleness of the hard-magnetic material. Despite the brittleness of the hard-magnetic material, a particularly thin layer of hard-magnetic material on a carrier made of tough material allows the signaling device to be pressed directly onto a component, in particular onto a shaft of a machine.

[0012] Preferably, the carrier is made of a metallic material, particularly preferably an austenitic or ferritic high-grade steel.

[0013] According to a further preferred embodiment of the invention, the hard magnetic layer is applied to the carrier by means of a PVD method. This allows the magnetic properties to be optimized in a targeted manner by varying the layer structure, which occurs under different process conditions. By means of a constant layer thickness, such as can be achieved in a PVD method, a high cycle accuracy of the signaling device can also be ensured. This allows, for example, the use of a pole wheel also in a high speed range of more than 30,000 rpm.

[0014] It is particularly advantageous if the magnetic signal device according to the invention is designed as a rotationally symmetrical pole wheel in a rotational angle and / or rotational speed measuring arrangement.

[0015] The object mentioned at the outset can also be achieved for a rotating component, in particular a component of a drive, which comprises a magnetic signal device for measuring the movement and / or position of the component. The starting point for this is a component which comprises an annular or disk-shaped carrier for connection to the component and at least one magnetic track, which extends along the circumference, in the form of a magnetizable hard magnetic layer deposited directly on the carrier from the gas phase, the hard magnetic layer having at least 75% by weight of a rare earth magnetic material, preferably one or more of the compounds NdFeB and / or Co5Sm and / or Co17Sm2, the layer having a magnetic structure in the direction of rotation after magnetization, which can be measured by a sensor. Again preferably, the proportion of the respective rare earth metal is less than 75% by weight of the hard magnetic layer.

[0016] According to the invention, the component is characterized in that the carrier is made of a material having a higher toughness than the material of the hard magnetic layer and is press-fitted to the rotating component.

[0017] Preferably, in the case of this component, the carrier is produced from a metallic material, preferably from ferritic steel.

[0018] According to a preferred embodiment of the invention, the hard magnetic layer is applied to the carrier, preferably by means of a PVD method. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a better understanding of the invention, the invention is explained in more detail with the aid of the following drawings.

[0020] The greatly simplified schematic diagrams are as follows:

[0021] Figure 1 A schematic perspective view showing a magnetic signaling device;

[0022] Figure 2 A schematic diagram showing a magnetic detection device according to the present invention in a top view; and

[0023] Figure 3 A cross-sectional view showing a portion of a magnetic signaling device. DETAILED DESCRIPTION

[0024] First of all, it should be pointed out that in the various embodiments described, the same components are provided with the same reference numerals or the same component names, and the disclosure contained in the entire description can be applied to the same components with the same reference numerals or the same component names in a meaningful manner. The orientation descriptions selected in the description, such as top, bottom, side, etc., also refer to the directly described and described drawings, and such orientation descriptions can be applied to the new orientation in a meaningful manner when the orientation changes.

[0025] exist Figure 1Schematically depicted in the figure is a magnetic signal device 1, which is used in particular for measuring the movement and / or position of rotating components, in particular components of drive devices, in the automotive field and in the industrial field. In this case, the magnetic signal device 1 is configured, for example, with a rotationally symmetrical pole wheel 2. The pole wheel 2 is connected to a shaft 3 in a rotationally fixed manner, which represents an example for a component whose rotational position or rotational speed is to be determined. The shaft 3 rotates about an axis of rotation 4 and is connected, for example, to a transmission or a drive device (not shown). In this way, the rotation and / or position of the shaft 3 and thus the rotation and / or position of the transmission or the drive device can be measured by the pole wheel 2.

[0026] As in Figure 1 As can also be seen in the figure, the pole wheel has corresponding segments 5, 6, 7, 8, 9, 10, 11, 12, which have hard magnetic pure metal layers with alternating magnetization without polymer content as magnetic poles. According to a special embodiment of the invention, maximum operating temperatures below 250° C. are therefore possible (also over a long period of time). The hard magnetic layer is magnetized by a suitable magnetizing device. As shown by Figure 1 and Figure 2 It can be seen that the hard magnetic layer is arranged on the front surface of the pole wheel and on the radial circumferential surface. Figure 2 , several magnetic poles 8, 9, 10, 11 are shown on a part of the radial circumferential surface. A detector 12 of the rotational angle and / or rotational speed measuring arrangement is also described, which is arranged at a predetermined distance from the pole wheel 2. The detector 12 is, for example, a detector / sensor based on the XMR measurement principle and / or the Hall measurement principle and measures the rotation and / or position of the pole wheel 2 with high resolution. XMR sensors are sensors that work magnetoresistively, that is, the sensors change their impedance under the influence of a magnetic flux. So-called AMR (anisotropic magnetoresistance), GMR (giant magnetoresistance) and TMR (tunnel magnetoresistance) sensors are known from the prior art, which are subdivided under XMR sensors. According to a special embodiment of the invention, the sensor and the magnetic signal device have a resolution of 10 to 20 bits, in particular on one or more tracks. According to a special embodiment, a distance between 0.1 mm and 3 mm is arranged between the sensor and the magnetic signal device.

[0027] exist Figure 3The structure of the pole wheel 2 is schematically described in detail in FIG. The pole wheel 2 has a support structure 13, for example in the form of a disk or ring. The hard magnetic layer according to the invention is applied to this support structure 13, which is made of a material with higher toughness than the hard magnetic layers 5 to 12. Preferably, the carrier 13 is made of a metallic material, such as steel, high-quality steel, copper, brass or aluminum. Austenitic or ferritic high-quality steels are particularly preferred here, which are known for their excellent toughness. Their advantages generally also lie in their high chromium content and low carbon content, as well as in their excellent weldability and other positive technical properties.

[0028] The particularly thin layers of hard-magnetic material of the layers 5 to 12 of between 1 and 150 μm on the carrier 13 made of ductile material allow the signaling device 1 to be pressed directly onto the shaft 3 despite the brittleness of the hard-magnetic material.

[0029] In the case described, the hard magnetic layer is applied as at least one track with a very small layer thickness, which extends along the circumference of the pole wheel 2, in particular along the entire radial circumferential surface and / or on one of the two end faces. According to a special embodiment of the invention, the hard magnetic layer is arranged only in the detection area of ​​the sensor 12. According to a further preferred embodiment of the invention, a protective layer 15 is arranged on the hard magnetic layer, which protects the hard magnetic layer to be detected from damage and / or environmental influences.

[0030] The hard magnetic layers 5 to 12 are preferably applied to the carrier 13 by means of a PVD method in order to thereby allow targeted optimization of the magnetic properties. In the context of the PVD method, it is possible, for example, to generate ions by hollow cathode glow discharge and to apply or sputter the ions thus generated onto the surface.

[0031] By controlling the PVD process in a targeted manner, the layer morphology can be adjusted from amorphous to partially crystalline and finally to crystalline. The process also allows the deposition of crystalline single-phase layers such as Co17Sm2, Co5Sm. This can be achieved by adapting the coating parameters. The layer structure can also be optimized for different magnetization methods (e.g. in-plane or out-of-plane).

[0032] Alternatively, the hard magnetic layer can also be applied by at least one of the following methods: hollow cathode-gas flow sputtering and / or hollow cathode sputtering and / or electroplating and / or CVD and / or plasma spraying. At least 75% (by weight) of the layers 5 to 12 are made of one or more of the following compounds, such as NdFeB and / or Co5Sm and / or Co17Sm2, in particular with or without doping or alloying with other elements such as Fe, Cu, Zr. Regarding the composition of the hard magnetic layer, less than 10% (by weight) of alloying elements may be present. Other rare earth materials, in particular neodymium, praseodymium, terbium and dysprosium, may also be used. Here, the corresponding rare earth metals, such as neodymium or samarium, are preferably present in layers 5 to 12 in an amount of less than 75% (by weight).

[0033] CoSm has excellent temperature resistance with a Curie temperature of over 700° C. In addition, the very homogeneous microcrystalline structure of the layer combined with the well-controllable layer thickness allows very precise magnetization with an angular accuracy of less than 0.1°. If such a pole wheel is combined with a suitable sensor, a resolution of less than 18 bits can be achieved. The signal device according to the invention is therefore optimally suitable for purely digital signal processing and can achieve accuracies that were previously only possible with optical systems, while achieving known robustness. The achievable accuracy also meets the standards for use in electric motors for controlling the rotor as an alternative to resolvers.

[0034] Another advantage over the prior art is the insensitivity to organic solvents, oils and greases, since in particular no carbon-based polymers are used. In particular in environments with oil mist, which occur in particular in the context of high-performance electric motors and drive trains in electric vehicles, the present invention represents a decisive added value for increasing efficiency.

[0035] In addition, the following possibility is offered: to dispense with the housing and to use a combination of a pole wheel mounted directly on the shaft and a separate evaluation unit (bearingless encoder). Thus, on the one hand, it is possible to directly integrate the measuring unit, for example in the electric motor, and furthermore no free end of the shaft is required for assembly.

[0036] Furthermore, a very high stability against demagnetization or alternating magnetization is achieved with a hard magnetic layer, thus significantly increasing the stability against (also very strong) interfering magnetic fields. Thus, for example, a Co5Sm compound has a coercive field strength of less than 750 kA / m.

[0037] If higher rotational speeds are required, then in conventional systems either a support ring on the outside of the pole wheel is required or a gear wheel is used as a signal transmitter (feedback bias arrangement). However, this leads to a burden on accuracy and, moreover, such a configuration requires a very small spacing between the sensor and the pole wheel, which spacing is often not guaranteed due to practical errors.

[0038] Preferably, the hard magnetic layer has a remanence of 0.1 T to 1.3 T in the detection region thereof.

[0039] In an advantageous embodiment of the invention, the hard magnetic layer has an average thickness in its detection region of between 10 μm and 100 μm, preferably greater than 15 μm, particularly preferably greater than 25 μm or between 25 μm and 60 μm. This can significantly reduce the material consumption of expensive rare earths.

[0040] The layer thickness can be adjusted with an accuracy of ±0.2 μm or less, in particular ±0.1 μm or less, so that the accuracy is significantly improved. In particular, in the case of in-plane oriented magnetization, an accuracy advantage can be achieved by a particularly high aspect ratio between layer thickness and pole width.

[0041] Advantageously, a further layer can be arranged above the hard magnetic layer in the detection region as a protective layer for protecting the hard magnetic layers 5 to 12 , the further layer preferably having an average thickness of less than 10 μm.

[0042] In addition to the embodiments of the magnetic signaling device 1 described so far with a pole wheel 2 , a rotationally symmetrical encoder can also be provided.

[0043] According to a special embodiment of the invention, when magnetizing the hard magnetic layer, an angular accuracy of less than or equal to ±0.1° between the differently magnetizable regions can be achieved, which means that the magnetization structure can be realized very finely.

[0044] The various embodiments show possible implementation schemes. It should be noted that the present invention is not limited to the specifically described implementation schemes of the present invention. More precisely, different combinations of the various implementation schemes with each other are also possible, and this possibility of variation is within the capabilities of technicians working in this technical field based on the teachings of the technical processing of the present invention.

Claims

1. A magnetic signal device (1) for measuring the movement and / or position of a rotating component (3), in particular a component of a drive device, comprising an annular or disk-shaped carrier (13) for connecting to the component (3) and at least one magnetic track, the magnetic track extending along the circumference, the magnetic track being in the form of a magnetizable hard magnetic layer (5-12) deposited directly on the carrier from the gas phase, the hard magnetic layer having at least 75% (by weight) of rare earth magnetic material, preferably one or more of the compounds NdFeB and / or Co5Sm and / or Co17Sm2, the layer (5-12) having a magnetic structure in the direction of rotation after magnetization, the magnetic structure being measurable by a sensor (12), characterized in that The carrier (13) is made of a material having higher toughness than the material of the hard magnetic layers (5-12).

2. The signaling device according to claim 1, characterized in that The carrier (13) is made of a metallic material, preferably of austenitic or ferritic high-quality steel.

3. The signaling device according to claim 1 or 2, characterized in that: The hard magnetic layers (5-12) are preferably applied to the carrier (13) by means of a PVD method.

4. The signaling device according to any one of claims 1 to 3, characterized in that The hard magnetic layers (5-12) are adjusted from an amorphous state through a partially crystalline state to a crystalline state through targeted control of the PVD process. 5 . The magnetic signal device according to claim 1 , which is designed as a rotationally symmetrical pole wheel ( 2 ) in a rotational angle and / or rotational speed measuring arrangement.

6. A rotating component (3), in particular a component of a drive device, comprising a magnetic signal device (1) for measuring the movement and / or position of the component, the rotating component comprising an annular or disc-shaped carrier (13) for connecting to the component (3) and at least one magnetic track, the magnetic track extending along the circumference, the magnetic track being in the form of a magnetizable hard magnetic layer (5-12) directly deposited on the carrier (13) from the gas phase, the hard magnetic layer having at least 75% (by weight) of rare earth magnetic material, preferably one or more of the compounds NdFeB and / or Co5Sm and / or Co17Sm2, the layer having a magnetic structure in the direction of rotation after magnetization, the magnetic structure being measurable by a sensor, characterized in that The carrier (13) is made of a material having higher toughness than the material of the hard magnetic layers (5-12) and is press-fitted to the rotating member (3).

7. The component according to claim 6, characterized in that The carrier (13) is made of a metallic material, preferably an austenitic or ferritic high-grade steel.

8. The component according to claim 6 or 7, characterized in that The hard magnetic layers (5-12) are preferably applied to the carrier (13) by means of a PVD method.

9. A component according to any one of claims 6 to 8, characterized in that The hard magnetic layers (5-12) are adjusted from an amorphous state through a partially crystalline state to a crystalline state through targeted control of the PVD process.

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