Magnetic signal device and component equipped with the device

Abstract

The present invention relates to a magnetic signal device 1 for measuring the movement and / or position of a rotating part 3, and to the rotating part 3. At least one magnetic track extending along the periphery in the form of magnetizable hard magnetic layers 5 to 12 of a rare earth magnet material deposited directly from the gas phase is applied onto a ring-shaped or disk-shaped carrier 13 for connecting to the rotating part 3. The carrier 13 is made of a material having a higher ductility than the hard magnetic layers 5 to 12.

Description

Technical Field

[0001] The present invention relates to a magnetic signal device for measuring the movement and / or position of a component of a drive machine, in particular a magnet wheel, for use in a rotation angle or speed monitoring system.

Background Art

[0002] The determination of the rotation angle and / or speed of a rotating component is an essential operation in many technical fields. The measurement principle most commonly used for high-precision applications is optical or optoelectronic scanning. However, this is basically sensitive to environmental influences such as shock, vibration, dirt, temperature fluctuations, and moisture. A special housing design aimed at compensating for this imposes certain limitations on the installation options, and for larger shaft diameters, the cost increases disproportionately, so a technically and economically feasible solution is almost no longer possible.

[0003] A resolver, i.e., a transformer, is used to measure the rotation angle. The inductive connection between the windings of the transformer varies with the angle. When an alternating current signal is applied, a measurement in the windings of the transformer generates an electrical alternating current signal whose amplitude is proportional to the angle. Since resolvers are highly reliable, they are often used in safety systems. However, since the resolution mainly depends on the quality of the analog-to-digital conversion, resolver-based systems are complex, often heavy, bulky, and expensive.

[0004] As an alternative, there is a rotary encoder with a magnetic measurement principle. Since it is less sensitive to shock, vibration, in addition to dirt, temperature fluctuations, and moisture, magnetic encoders can be particularly used when the service life of an optical encoder is limited despite its complex protective housing. These are areas of application where the encoder is exposed to high temperatures, temperature fluctuations, dirt, dust, exposure / staining by chemicals or solvents.

[0005] For example, in the field of automotive engineering, it is common practice to monitor the speed of wheels in order to control an anti-lock braking system or an anti-skid control system. For this and other speed monitoring purposes, magnetic pole wheels with adjacent sensors are commonly used, which emit a vibration signal when the magnetic pole wheel rotates relative to the sensor, and the frequency of which is a measure of the rotational speed of the magnetic pole wheel and thus also a measure of the rotating part of a vehicle or other machine firmly connected to the magnetic pole wheel. At least one magnetic track is arranged on the periphery of the magnetic pole wheel and this magnetic track is evaluated by a coil or a magnetic field sensor. The magnetic pole wheel is used as a speed or angle sensor, such as an incremental encoder, is relatively insensitive to dirt and can usually be manufactured quite inexpensively.

[0006] The magnetic pitch of a magnetic pole wheel and / or encoder attached to a rotating shaft is a signal generator for a sensor. Such an encoder is known, for example, from Patent Document 1 (European Patent Application Publication No. 1030181). The electronic device is integrated into the scanning head with high protection and can be completely encapsulated if necessary. Thanks to the two-component system design with a magnet wheel and a scanning head, a magnetic encoder can be used without a complex protective housing or additional ball bearings, thus enabling a solution with a very long service life and virtually no wear. Furthermore, such a system does not require a free shaft end for mounting and is thus well suited for integration into an electric motor, for example, in an electric vehicle. Patent Document 2 (German Patent Application Publication No. 102016218930) shows another such product. Alternatively, for example, Patent Document 3 (German Patent Application Publication No. 102018217274) shows the production of a ring consisting of sintered partial magnets, each connected to a polymer-based intermediate piece.

[0007] Flywheels exist in various designs. For example, Patent Document 4 (German Patent Application Publication No. 10210372) discloses a rotational angle sensor with high angular resolution. This sensor has magnetic tracks on a magnetic pole wheel, with magnetic north and south poles arranged alternately, and the position relative to a component fixed in the rotational direction is detected by a magnetic field sensor. As a possible embodiment, a magnetic pole wheel made of plastic or synthetic resin and mixed with ferromagnetic components is described, which is easy and inexpensive to manufacture. According to Patent Document 4, in particular, magnetic tracks can be formed from magnetized ferrite foil, which can be manufactured easily and inexpensively. Alternatively, magnetic tracks made of magnetized ferrite bonded to rubber, synthetic resin, or natural rubber are also possible. Furthermore, Patent Document 5 (European Patent Application Publication No. 213732) discloses a sensor system for detecting the rotation of an object, which includes a magnetic ring composed of synthetic resin containing a mixed ferromagnetic material.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0009] The object of the present invention is to overcome the drawbacks of the prior art, provide a high level of accuracy in a safe manner, be free from the influence of any kind of interference, and be flexibly usable in a wide range of areas under a wide range of operating conditions.

Means for Solving the Problems

[0010] This technical problem is solved by the magnetic signal device according to the claims. Further features can be found in the specification and the drawings.

[0011] The device according to the present invention is a magnetic signal device for measuring the movement and / or position of a rotating component, in particular a component of a drive machine. The magnetic signal device includes a ring-shaped or disk-shaped carrier for connecting the component, and a layer directly deposited from the gas phase on the carrier, which is in the form of a magnetizable hard magnetic layer composed of at least one of compounds of rare earth magnet materials with at least 75% by weight, preferably NdFeB and / or Co5Sm and / or Co17Sm2, and includes at least one magnetic track extending along the periphery. The hard magnetic layer is based on a magnetic signal device having a magnetic structure after magnetization in the rotational direction that can be measured via a sensor. The proportion of each rare earth metal itself is preferably less than 75% by weight ratio of the hard magnetic layer.

[0012] In order to achieve the above object, in the present invention, the signal transmission device is characterized in that the carrier is made of a material having higher ductility than the hard magnetic layer. Due to the low layer thickness of the hard magnetic layer and its application to a ductile material, the brittleness of the hard magnetic material is evaluated relativistically. The particularly thin layer of the hard magnetic material on the carrier made of a ductile material enables the signal device to be directly pressed onto the component, particularly onto a machine shaft, despite the brittleness of the hard magnetic material.

[0013] The carrier is preferably made of a metal material. Austenitic or ferritic stainless steel is particularly preferred.

[0014] According to a further preferred embodiment of the present invention, the hard magnetic layer is applied to the carrier by a PVD process. This enables optimization of the magnetic properties through changes in the layer structure occurring under different process conditions. Also, the constant layer thickness achievable in the PVD process ensures high concentricity of the signal transmission device. This allows, for example, the use of the magnetic pole wheel even in a high-speed range of more than 30,000 revolutions per minute.

[0015] Particularly advantageous is the design of the magnetic signal device according to the invention as a rotationally symmetric magnetic pole wheel in the rotational angle and / or speed measurement arrangement.

[0016] The solution to the problem initially posed is also possible for rotating components, in particular for components of a drive machine, by means of a magnetic signal device for measuring the movement and / or position of the rotating component. The starting point for this is a ring or disc-shaped carrier for connecting the components, and a layer deposited directly from the gas phase onto the carrier, in the form of a magnetizable hard magnetic layer consisting of at least 75% by weight of a rare earth magnet material, preferably one or more of the compounds NdFeB and / or Co5Sm and / or Co17Sm2, with at least one magnetic track extending along the circumference, this layer having a magnetic structure after magnetization in the rotational direction that can be measured by a sensor. Here too, the proportion of each rare earth metal itself is preferably less than 75% by weight of the hard magnetic layer.

[0017] According to the present invention, this component is characterized in that the carrier consists of a material having higher ductility than the hard magnetic layer and is pressed together with the rotating component.

[0018] Preferably, the carrier of this component consists of a metallic material, preferably ferrite steel.

[0019] According to a preferred embodiment of the present invention, the hard magnetic layer is preferably applied to the carrier by a PVD process.

[0020] To better understand the present invention, it will be described in more detail with reference to the following figures.

[0021] In the figures, it is shown in a very simplified schematic representation.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0023] It should be noted that, by introduction, in the various embodiments described, the same reference numerals or the same component names are given to the same components, so that the disclosure included in the entire description can be applied mutatis mutandis to the same components having the same reference numerals or the same component names. Also, the following selected position information in the description, for example, the top, bottom, side, etc., is directly described with reference to the drawn figures, and when the position changes, the details of these positions should be transferred to the new position accordingly.

[0024] FIG. 1 schematically shows a magnetic signal device 1, which is used in particular in the automotive field and in the industrial field for measuring the movement and / or position of rotating parts, in particular components of a drive machine. The magnetic signal device 1 is designed, for example, to include a rotationally symmetric magnetic pole wheel 2. This magnetic pole wheel 2 is connected in a rotationally fixed state to a shaft 3, which is an example of a component for determining its rotational position or rotational speed. The shaft 3 rotates about a rotational axis 4 and is connected, for example, to a gearbox or a drive machine (not shown). In this way, the further rotation and / or position of the shaft 3 and the gearbox or the drive machine can be measured using the magnetic pole wheel 2.

[0025] As can be further seen from FIG. 1, the magnetic pole wheel has corresponding sections 5, 6, 7, 8, 9, 10, 11, 12 with hard pure metal layers without polymer content having alternating magnetization as magnetic poles. According to a special embodiment of the present invention, a maximum operating temperature of up to 250° C. (again, for a long period) is possible. The hard magnetic layer is magnetized using a suitable magnetization device. As can be seen from FIGS. 1 and 2, the hard magnetic layer is arranged not only on the radial peripheral surface but also on the front surface of the magnetic pole wheel. In FIG. 2, the individual poles 8, 9, 10, 11 are shown as part of the radial peripheral surface. Further, a detector 12 of the rotation angle and / or speed measurement arrangement is shown, which is arranged at a predetermined distance from the magnetic pole wheel 2. The detector 12 is, for example, a detector / sensor based on the XMR and / or Hall measurement principle and measures the rotation and / or position of the magnetic pole wheel 2 with high resolution. The XMR sensor is a magnetoresistive sensor, which means that the sensor changes its resistance under the influence of the magnetic flux. The so-called AMR, GMR and TMR sensors are known from state-of-the-art technology and are incorporated into the XMR sensor. According to a particular embodiment of the present invention, the sensor and the magnetic signal device have a resolution of 10 bits to 20 bits, especially with one or more tracks. According to a special embodiment, a distance of 0.1 mm to 3 mm is provided between the sensor and the magnetic signal device.

[0026] FIG. 3 schematically shows in detail the structure of the magnetic pole wheel 2. The magnetic pole wheel 2 has a support structure 13 in the form of, for example, a disk or a ring. The hard magnetic layer according to the present invention is applied to this support structure 13 made of a material that is more ductile than the hard magnetic layers 5 - 12. Preferably, the carrier 13 is made of a metallic material such as steel, stainless steel, copper, brass or aluminum. Particularly preferred is austenitic or ferritic stainless steel, which is known for its excellent ductility. Also, they are generally characterized by a high chromium and low carbon content, as well as excellent weldability and other beneficial technical properties.

[0027] Due to the particularly thin layers of hard magnetic material, 1 to 150 μm, of layers 5 to 12 on the carrier 13 made of a ductile material, it is possible to press the signal device 1 directly onto the shaft 3 despite the brittleness of the hard magnetic material.

[0028] When shown, the hard magnetic layer is applied as at least one magnetic track of very small layer thickness extending along the periphery, i.e., over the entire radial peripheral surface and / or along one of the two end faces of the magnetic pole wheel 2. According to a particular embodiment of the invention, the hard magnetic layer is provided only in the scanning area of the sensor 12. According to a further preferred embodiment of the invention, a protective layer 15 is provided on the hard magnetic layer, thereby protecting the scanned hard magnetic layer from damage and / or the influence of the environment.

[0029] The hard magnetic layers 5 to 12 are preferably applied to the carrier 13 by a PVD process in order to enable the optimization of the magnetic properties. In the field of PVD processes, for example, ions can be generated via a glow discharge of a hollow cathode and the ions thus generated can be applied or sputtered onto the surface.

[0030] By carefully controlling the PVD process, the layer morphology can be adjusted from amorphous via semi-crystalline to crystalline. Also, this process enables the deposition of crystalline single-phase layers such as Co17Sm2, Co5Sm. This can be done by adjusting the coating parameters. The layer structure can also be used for different magnetization processes such as in-plane or out-of-plane optimization.

[0031] Alternatively, the hard magnetic layer can also be applied by at least one of the processes following hollow cathode gas flow sputtering and / or hollow cathode sputtering and / or electroplating and / or CVD and / or plasma spraying. Layers 5 to 12 consist of at least 75% by weight of one or more of compounds such as NdFeB and / or Co5Sm and / or Co17Sm2, regardless of the presence or absence of doping or alloying with other elements such as Fe, Cu, Zr, etc. Based on the composition of the hard magnetic layer, alloying elements up to 10% by weight may be present. Other rare earth materials, especially neodymium, praseodymium, terbium and dysprosium can also be used. Each rare earth metal, for example, neodymium or samarium, is preferably present in layers 5 to 12 at less than 75% by weight.

[0032] CoSm has excellent temperature stability at a Curie temperature of 700 °C or higher. Furthermore, the very homogeneous microcrystalline structure of the layer combined with an easily controllable layer thickness enables very precise magnetization with an angular accuracy of less than 0.1°. When such a magnetic pole wheel is combined with a suitable sensor, a resolution of up to 18 bits can be achieved. As a result, the signal transmission device according to the present invention is optimal for purely digital signal processing and can achieve the accuracy previously covered only by optical systems while maintaining the known robustness. Also, the achievable accuracy meets the criteria for use in an electric motor for controlling a rotor as a replacement for a resolver.

[0033] A further advantage over the state of the art is the insensitivity to organic solvents, oils and greases. This is because in particular carbon-based polymers are not used. In particular, in an environment affected by oil mist generated in the field of high-performance electric motors and drive systems of electric vehicles, this innovation represents a decisive added value for increasing efficiency.

[0034] It is also possible to operate without a housing and to use a combination of a magnetic pole wheel arranged directly on the shaft and an individual evaluation unit (bearingless encoder). Thereby, for example, in an electric motor, a measuring unit or the like can be used directly, and the free end of the shaft is unnecessary for assembly.

[0035] Furthermore, the use of a hard magnetic layer provides very high stability against demagnetization or remagnetization, which significantly increases the stability even against (very strong) interference fields. For example, the Co5Sm compound has a coercive field strength up to 750 kA / m.

[0036] When higher rotational speeds are required, conventional systems either require a support ring outside the magnetic pole wheel or require the use of a gear as a signal transmitter (back-biased arrangement). However, this sacrifices accuracy, and such a configuration requires a very small distance between the sensor and the wheel, which often cannot be guaranteed due to actual tolerances.

[0037] Preferably, the hard magnetic layer has a residual magnetism of 0.1 T to 1.3 T in its scanning region.

[0038] In an advantageous embodiment of the present invention, the hard magnetic layer within its scanning region has an average thickness of 10 μm to 100 μm, preferably greater than 15 μm, particularly preferably greater than 25 μm, or 25 μm to 60 μm. This means that the consumption of expensive rare earth materials can be significantly reduced.

[0039] The thickness of the layer can be adjusted with an accuracy of ±0.2 μm or less, particularly ±0.1 μm or less, thereby significantly improving the accuracy. In particular, in-plane magnetization can achieve precise advantages due to a particularly high aspect ratio between the layer thickness and the magnetic pole width.

[0040] On the hard magnetic layer, a further layer having an average thickness of up to 10 μm can preferably be provided in the scanning region as a protective layer, advantageously to protect the hard magnetic layer 5 to 12.

[0041] In addition to the design of the magnetic signal device 1 provided with the aforementioned magnetic pole wheel 2, a rotationally symmetric encoder can also be provided.

[0042] According to a specific embodiment of the present invention, when magnetizing the hard magnetic layer, an angular accuracy of ±0.1° or less between different magnetizable regions can be achieved. This means that the structure of magnetization can be realized very finely.

[0043] The embodiments show variations of possible embodiments, whereby, in this regard, the invention is not limited to the variations of the specifically illustrated embodiments, but rather, it is also possible to combine the variant embodiments of the individual embodiments with each other in various ways, and this possibility of variation is within the scope of those skilled in the art of this technical field by the teaching of the technical acts according to the objective invention.

Claims

1. A magnetic signal device (1) for measuring the movement and / or position of a rotating part (3), in particular a component of a drive machine, comprising: The magnetic signal device (1) comprises: A ring-shaped or disk-shaped carrier (13) for connecting the component (3); A layer directly deposited from the gas phase on the carrier, in the form of at least one magnetizable hard magnetic layer (5-12) extending along the periphery, consisting of at least 75% by weight of a rare earth magnet material, preferably one or more of the compounds of NdFeB and / or Co5Sm and / or Co17Sm2, and having at least one magnetic track; In the magnetic signal device (1), the hard magnetic layer (5-12) has a magnetic structure after magnetization in the rotational direction, which can be measured via a sensor (12). The carrier (13) of the magnetic signal device (1) is made of a material having higher ductility than the hard magnetic layer (5-12).

2. The signal device according to claim 1, characterized in that the carrier (13) is made of a metallic material, preferably austenitic or ferritic stainless steel.

3. The signal device according to claim 1 or 2, characterized in that the hard magnetic layer (5-12) is preferably applied to the carrier (13) by a PVD process.

4. The signal device according to any one of claims 1 to 3, characterized in that the hard magnetic layer (5-12) can be adjusted from amorphous, through semi-crystallization, to crystallization by target control of the PVD process.

5. In one embodiment, the magnetic signal device according to claim 1, as a rotationally symmetric magnetic pole wheel (2) in a rotation angle and / or speed measurement arrangement.

6. A rotating part (3), in particular a component of a drive machine, comprising a magnetic signal device (1) for measuring the movement and / or position of the rotating part, comprising: The rotating part (3) comprises: A ring-shaped or disk-shaped carrier (13) for connecting to the rotating part (3); A layer directly deposited from the gas phase on the carrier, in the form of at least one magnetizable hard magnetic layer (5-12) extending along the periphery, consisting of at least 75% by weight of a rare earth magnet material, preferably one or more of the compounds of NdFeB and / or Co5Sm and / or Co17Sm2, and having at least one magnetic track. In the rotating component (3), the hard magnetic layer (5-12) has a magnetic structure after magnetization in the rotational direction, which can be measured via the sensor (12). The carrier (13) is made of a material having higher ductility than the hard magnetic layer (5-12), and the rotating component (3) is pressed together with the rotating component (3). **Claim 7** The rotating component according to claim 6, wherein the carrier (13) is made of a metal material, preferably austenitic or ferritic stainless steel. **Claim 8** The rotating component according to claim 6 or 7, wherein the hard magnetic layer (5-12) is preferably applied to the carrier (13) by a PVD process. **Claim 9** The rotating component according to any one of claims 6 to 8, wherein the hard magnetic layer (5-12) can be adjusted from amorphous, through semi-crystallization, to crystallization by target control of the PVD process.

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