MAGNETIC SIGNAL DEVICE AND COMPONENT EQUIPPED WITH IT

Description

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

[0002] Determining the angles of rotation and / or the rotational speeds of rotating parts is a crucial task in many technical fields. The most frequently used measuring principle for high-precision applications is optical or photoelectric scanning. However, this method is inherently sensitive to environmental influences such as shock and vibration, dirt, temperature fluctuations, and humidity. Special housing designs intended to compensate for these effects lead to certain limitations in mounting options, and with larger shaft diameters, costs increase disproportionately, making technically and economically viable solutions virtually impossible.

[0003] To measure the angle of rotation, resolvers, i.e., electrical transformers, are used. The inductive coupling between the transformer's windings varies depending on the angle. When an AC signal is applied, the measurement across the transformer's windings results in an AC electrical signal whose amplitude is proportional to the angle. Resolvers are frequently used in safety systems due to their reliability. However, the resolution is highly dependent on the quality of the analog-to-digital conversion, making resolver-based systems complex, and often heavy, bulky, and expensive.

[0004] As an alternative, rotary encoders with a magnetic measuring principle are available. Due to their insensitivity to shock and vibration, as well as to dirt, temperature fluctuations, and humidity, magnetic encoders can be used particularly where the service life of optical rotary encoders is limited despite elaborate protective housings. These are application areas where the rotary encoders are exposed to high temperatures, temperature fluctuations, dirt and dust, and / or exposure to chemicals and solvents.

[0005] For example, in the field of automotive engineering, wheel speed monitoring for controlling an anti-lock braking system (ABS) or traction control (TCS) is a common technique. For this and other speed monitoring applications, pole wheels with an adjacent sensor are typically used. When the pole wheel rotates relative to the sensor, this sensor outputs an oscillating signal. The frequency of this signal is a measure of the rotational speed of the pole wheel and thus also of the rotating part of the vehicle or other machine that is rigidly connected to it. At least one magnetic track is arranged on the circumference of the pole wheel, which is evaluated by coils or magnetic field sensors. The pole wheel functions like an incremental encoder as a speed or angle sensor; it is relatively insensitive to contamination and usually quite inexpensive to manufacture.

[0006] The magnetic division of a pole wheel and / or encoder mounted on the rotating shaft serves as the signal transmitter for a sensor. Such an encoder is known, for example, from EP1030181A2. The electronics are integrated into the highly ingress protection (HICP) reading head and can be completely encapsulated if required. Thanks to the two-part system design with pole wheel and reading head, magnetic encoders can be used without a complex protective housing or additional ball bearings – thus enabling a virtually wear-free solution with a very long service life. Furthermore, such systems do not require a free shaft end for installation and are therefore well-suited for integration into electric motors, for example, in electric vehicles. Publication DE102016218930A1 describes another such product. Alternatively, publication DE102018217274A1, for example, describes the production of a ring made of sintered partial magnets, each connected with polymer-based spacers.

[0007] Pole wheels exist in a wide variety of designs. For example, DE10210372A1 discloses a rotation angle sensor with high angular resolution, which has a magnetic track on a pole wheel in which magnetic north and south poles are arranged alternately and whose position relative to a rotationally fixed component is detected by a magnetic field sensor. As a possible embodiment, a pole wheel made of plastic or synthetic resin with embedded ferromagnetic components is described, which is easy and inexpensive to manufacture. According to DE10210372A1, the magnetic tracks can be formed, among other things, from magnetized ferrite foil, which is also easy and inexpensive to manufacture. Alternatively, magnetic tracks made of magnetized ferrites bonded in rubber, synthetic resin, or latex are also possible.Furthermore, EP0213732A1 discloses a sensor system for detecting the rotation of an object, comprising a magnetic ring made of a synthetic resin with embedded ferromagnetic materials. WO2017 / 092738A1 shows another known rotation angle sensor.

[0008] The object of the present invention was to overcome the disadvantages of the prior art and to provide a device that offers high precision in a safe manner, unaffected by disturbances of any kind, and is flexibly applicable in a wide variety of fields under many different operating conditions.

[0009] This technical problem is solved by a magnetic signaling device according to the claims. Further features can be found in the description and the drawings.

[0010] The device according to the invention is based on a magnetic signaling device for measuring the movement and / or position of a rotating component, in particular a component of a drive machine, comprising a ring- or disk-shaped carrier for connecting to the component, and at least one magnetic track extending along the circumference in the form of a magnetizable, hard magnetic layer deposited directly onto the carrier from a gas phase, comprising 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, wherein the layer, after magnetization in the direction of rotation, has a magnetic structure that 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] To solve the stated problem, such a signaling device is characterized according to the invention in that the carrier consists of a material with higher ductility than that of the hard magnetic layer. The small thickness of the hard magnetic layer and its application to a ductile material mitigates the brittleness of the hard magnetic material. Despite the brittleness of the hard magnetic material, the particularly thin layer of the hard magnetic material on the ductile carrier enables the signaling device to be pressed directly onto a component, in particular onto a shaft of a machine.

[0012] Preferably, the support is made of a metallic material. Austenitic or ferritic stainless steel is particularly preferred.

[0013] According to a further preferred embodiment of the invention, the hard magnetic layer was applied to the substrate using a PVD process. This allows for the targeted optimization of the magnetic properties by modifying the layer structure under different process conditions. A constant layer thickness, as achievable with PVD processes, also ensures high concentricity of the signal device. This enables, for example, the use of pole wheels even at high speeds exceeding 30,000 revolutions per minute.

[0014] The embodiment of the magnetic signal device according to the invention as a rotationally symmetrical pole wheel in a rotation angle and / or speed measuring arrangement is particularly advantageous.

[0015] The solution to the problem posed at the outset is also possible for a rotating component, in particular a component of a drive machine, with a magnetic signaling device for measuring the movement and / or the position of the component. The starting point for this is a component comprising a ring- or disk-shaped carrier for connecting the component, as well as at least one magnetic track extending along the circumference in the form of a magnetizable, hard magnetic layer deposited directly onto the carrier from a gas phase, comprising at least 75 wt% of a rare-earth magnetic material, preferably one or more of the compounds NdFeB and / or Co5Sm and / or Co17Sm2, wherein, after magnetization in the direction of rotation, the layer has a magnetic structure that can be measured by a sensor. Again, the proportion of the respective rare-earth metal itself is preferably less than 75 wt% of the hard magnetic layer.

[0016] According to the invention, this component is characterized in that the carrier consists of a material with a higher ductility than that of the hard magnetic layer and is pressed onto the rotating component.

[0017] Preferably, the support for this component consists of a metallic material, preferably ferritic steel.

[0018] According to a preferred embodiment of the invention, the hard magnetic layer was preferably applied to the substrate using a PVD process.

[0019] To better understand the invention, it is explained in more detail with reference to the following illustrations.

[0020] They each show, in a highly simplified, schematic representation: Fig. 1 a schematic perspective view of a magnetic signaling device; Fig. 2 a schematic top view of an inventive magnetic detection device; and Fig. 3 a sectional view of part of a magnetic signaling device.

[0021] It should be noted at the outset that in the differently described embodiments, identical parts are provided with the same reference numerals or component designations, and the disclosures contained in the entire description can be applied analogously to identical parts with the same reference numerals or component designations. Furthermore, the positional designations chosen in the description, such as top, bottom, side, etc., refer to the figure directly described and illustrated, and these positional designations must be applied analogously to the new position if the position changes.

[0022] In Fig. 1 Figure 1 schematically depicts a magnetic signaling device 1, used in particular for measuring the movement and / or position of a rotating component, especially a component of a drive motor, in the automotive sector but also in industrial applications. The magnetic signaling device 1 is, for example, designed with a rotationally symmetrical pole wheel 2. This pole wheel 2 is fixedly connected to a shaft 3, which represents an example of a component whose rotational position or speed is to be determined. The shaft 3 rotates about an axis of rotation 4 and is, for example, connected to a gearbox or a drive motor (not shown). In this way, the rotation and / or position of the shaft 3, and subsequently of the gearbox or drive motor, can be measured using the pole wheel 2.

[0023] As in Fig. 1 As can be further seen, the pole wheel has corresponding sections 5, 6, 7, 8, 9, 10, 11, and 12, which comprise a hard magnetic, purely metallic layer without any polymer content, with alternating magnetization as magnetic poles. According to a particular embodiment of the invention, a maximum operating temperature (even for extended periods) of up to 250°C is thus possible. The hard magnetic layer is magnetized by a suitable magnetization device. As shown in the figures, the magnetic field is oriented as follows: Fig. 1 und Fig. 2 The hard magnetic layer is visibly arranged on the front surface of the pole wheel as well as on the radial circumferential surface. Fig. 2 The individual poles 8, 9, 10, 11 are shown on a portion of the radial circumferential surface. Additionally, a detector 12 of a rotation angle and / or rotational speed measurement arrangement is shown, 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 and / or Hall measurement principle and measures the rotation and / or position of the pole wheel 2 with high resolution. An XMR sensor is defined as a sensor that operates magnetoresistically, meaning that the sensor changes its resistance under the influence of the magnetic flux. So-called AMR, GMR, and TMR sensors, which are subsumed under XMR sensors, are known from the prior art. According to a particular embodiment of the invention, the sensor and the magnetic signaling device have a resolution of 10 to 20 bits, particularly on one or more tracks.According to a particular embodiment, a distance of between 0.1 mm and 3 mm is provided between the sensor and the magnetic signaling device.

[0024] In Fig. 3 The detailed structure of the pole wheel 2 is shown schematically. The pole wheel 2 has a support structure 13, for example in the form of a disc or ring. The hard magnetic layer according to the invention is applied to this support structure 13, which is made of a material with a higher ductility than the hard magnetic layer 5 to 12. Preferably, the support 13 consists of a metallic material such as steel, stainless steel, copper, brass, or aluminum. Austenitic or ferritic stainless steel, known for its excellent ductility, is particularly preferred. These materials are generally also characterized by a high chromium and low carbon content, as well as by their excellent weldability and other positive technical properties.

[0025] The particularly thin layer - between 1 and 150 µm - of the hard magnetic material of layer 5 to 12 on the carrier 13 made of ductile material enables the signal device 1 to be pressed directly onto the shaft 3 despite the brittleness of the hard magnetic material.

[0026] In the illustrated case, the hard magnetic layer is applied as at least one magnetic track of very low thickness extending along the circumference, i.e., the entire radial circumferential surface and / or on one of the two end faces of the 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 over the hard magnetic layer, which protects the scanned hard magnetic layer from damage and / or environmental influences.

[0027] The hard magnetic layer 5 to 12 is preferably applied to the substrate 13 using PVD technology in order to allow for targeted optimization of the magnetic properties. In the field of PVD technology, it is possible, for example, to generate ions via a glow discharge of a hollow cathode and to deposit or sputter the ions thus generated onto a surface.

[0028] Through precise control of the PVD process, the layer morphology can be adjusted from amorphous to semi-crystalline to crystalline. The process also enables the deposition of crystalline, single-phase layers such as Co17Sm2 and Co5Sm. This can be achieved by adjusting the coating parameters. Furthermore, the layer structure can be optimized for various magnetization methods, such as in-plane or out-of-plane.

[0029] Alternatively, the hard magnetic layer could also be applied using at least one of the following processes: hollow cathode gas flow sputtering, hollow cathode sputtering, electroplating, CVD, and / or plasma spraying. Layers 5 to 12 consist of at least 75 wt% of one or more of the following compounds, such as NdFeB, Co5Sm, and / or Co17Sm2, particularly with or without doping or alloying with other elements such as Fe, Cu, or Zr. Up to 10 wt% of alloying elements may be present in relation to the composition of the hard magnetic layer. Other rare earth materials may also be used, in particular neodymium, praseodymium, terbium, and dysprosium. The respective rare earth metal, e.g., neodymium or samarium, is preferably present in layers 5 to 12 at a concentration of less than 75 wt%.

[0030] CoSm exhibits excellent temperature resistance with a Curie temperature exceeding 700°C. Furthermore, the highly homogeneous microcrystalline structure of the layer, combined with a well-controlled layer thickness, allows for very precise magnetization with an angular accuracy of less than 0.1°. When such pole wheels are combined with suitable sensors, resolutions of up to 18 bits can be achieved. This makes a signal device according to the invention ideally suited for purely digital signal processing and capable of achieving accuracies previously only attainable by optical systems, while maintaining known robustness. The achievable accuracy also meets the criteria for use in electric motors for rotor control as a replacement for resolvers.

[0031] A further advantage over the prior art is its insensitivity to organic solvents, oils, and greases, as it does not use carbon-based polymers. Especially in oil mist-laden environments, such as those found in high-performance electric motors and electric vehicle powertrains, this innovation represents a significant added value for increasing efficiency.

[0032] Furthermore, it is possible to dispense with the housing and use a combination of a pole wheel that is mounted directly on the shaft and a separate evaluation unit (bearingless encoders). This makes it possible to integrate the measuring unit directly, e.g., into an electric motor, and also eliminates the need for a free end of the shaft for mounting.

[0033] Furthermore, the use of hard magnetic layers results in very high stability against demagnetization or remagnetization, which significantly increases stability against (even very strong) interference fields. For example, Co5Sm compounds exhibit coercive field strengths of up to 750 kA / m.

[0034] If higher rotational speeds are required, conventional systems either need a support ring on the outside of the pole wheel or must resort to gears as signal transmitters (back-bias configuration). However, this comes at the expense of accuracy, and such a configuration also requires a very small distance between the sensor and the wheel, which is often not achievable due to real-world tolerances.

[0035] Preferably, the hard magnetic layer has a magnetic remanence of 0.1 T to 1.3 T in its scanning area.

[0036] In an advantageous embodiment of the invention, the hard magnetic layer has an average thickness of between 10 µm and 100 µm, preferably more than 15 µm, and particularly preferably more than 25 µm or between 25 µm and 60 µm, in its scanning area. This significantly reduces the amount of expensive rare earth elements required.

[0037] The layer thickness can be adjusted with a precision of less than or equal to + / - 0.2 µm, and in particular less than or equal to + / - 0.1 µm, which significantly improves precision. In particular, a precision advantage can be achieved with in-plane magnetization due to the exceptionally high aspect ratio between layer thickness and magnetic pole width.

[0038] Advantageously, a further layer, preferably with a mean thickness of up to 10µm, can be provided above the hard magnetic layer in the scanning area to protect the hard magnetic layer 5 to 12.

[0039] In addition to the previously described design of the magnetic signal device 1 with a pole wheel 2, a rotationally symmetric encoder could also be provided.

[0040] According to a particular embodiment of the invention, an angular accuracy of less than or equal to ±0.1° between the differently magnetizable areas can be achieved when magnetizing the hard magnetic layer. This means that the magnetization structure can be realized very finely.

[0041] The exemplary embodiments show possible embodiment variants, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiment variants thereof, but rather various combinations of the individual embodiment variants are also possible, insofar as they fall within the scope of protection of the attached claims which define the invention.

Claims

1. A magnetic signaling device (1) for measuring the movement and / or the position of a rotating component (3), in particular a component of a driving machine, comprising an annular or disc-shaped carrier (13) for connection to the component (3), and at least one magnetic track extending along the circumference in the form of a magnetizable, hard-magnetic layer (5 to 12) deposited directly on the carrier from a gas phase and consists of at least 75% by weight of a rare-earth magnetic material, preferably from one or more of the compounds NdFeB and / or Co5Sm and / or Co17Sm2, wherein the layer (5 to 12), after magnetization along the circumference, has a magnetic structure which can be measured by a sensor (12), characterized in that the carrier (13) consists of a material with higher ductility than that of the hard magnetic layer (5 to 12).

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

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

4. The magnetic signaling device according to claim 3, characterized in that the hard magnetic layer (5 to 12) is adjusted from amorphous to semi-crystalline to crystalline by selective control of the PVD process.

5. The magnetic signaling device according to claim 1, in an embodiment as a rotationally symmetrical pole wheel (2) for a rotational angle and / or rotational speed measuring arrangement.

6. A rotating component (3), in particular a component of a drive machine, with a magnetic signaling device (1) according to one of the preceding claims, wherein the carrier (13) is pressed with the rotating component (3).