MAGNETIC SIGNAL DEVICE FOR MEASURING THE MOVEMENT AND/OR THE POSITION OF A COMPONENT OF A DRIVE MACHINE

Abstract

A magnetic signal device for measuring the movement and/or the position of a component of a drive machine has a supporting structure and a hard-magnetic layer applied on the supporting structure, wherein the hard-magnetic layer is applied via hollow cathode flow sputtering and/or electroplating and/or PVD and/or CVD and/or plasma spraying and x % by mass of the hard-magnetic layer consist of NdFeB and/or Co.sub.5Sm and/or Co.sub.2Sm.sub.17 and/or Co.sub.5Sm and/or Co.sub.2Sm.sub.17 and the hard-magnetic layer has a magnetic remanence of 0.3 T to 1.3 T in its scanning region.

Claims

1. A magnetic signal device for measuring the position of a rotating component of a drive machine, the signal device being coupled in a rotationally fixed manner to the component of the drive machine and the signal device having a supporting element and a magnetizable, hard-magnetic layer deposited on the supporting element from a gas phase directly on the supporting element, wherein at least 75% by weight, preferably at least 85% by weight, particularly preferably at least 90% by weight, based on the composition of the hard-magnetic layer, of the hard-magnetic layer consist of one or more of the following compounds NdFeB and/or Co.sub.5Sm and/or Co.sub.2Sm.sub.17 and the hard-magnetic layer has a magnetic remanence of 0.3 T to 1.3 T in its scanning region and after magnetization the hard-magnetic layer has a magnetic structure in the direction of rotation, so that, depending on the angle of rotation of the component, the magnetic structure, for example the magnetic field strength at different heights and/or orientations, can be measured on the hard-magnetic layer via a sensor in order to enable conclusions to be drawn about the rotation and/or position of the component.

2. The magnetic signal device according to claim 1, wherein the hard-magnetic layer has an average thickness of between 10 and 100 m, preferably more than 15 m, particularly preferably between 25 and 60 m, in its scanning region.

3. The magnetic signal device according to claim 1, wherein the supporting structure comprises a non-magnetic, in particular ceramic, material.

4. The magnetic signal device according to claim 1, wherein the supporting structure comprises a metallic material.

5. The magnetic signal device according to claim 1, wherein a further layer, preferably with an average thickness of up to 10 m, is provided over the scanning region of the hard-magnetic layer as a protective layer for protecting the hard-magnetic layer.

6. The magnetic signal device according to claim 1, wherein the hard-magnetic layer contains further alloying elements from the series of transition metals in its scanning region, preferably Fe and/or Zr and/or Cu.

7. The magnetic signal device according to claim 1, wherein the magnetic signal device is configured as a rotationally symmetrical pole wheel.

8. The magnetic signal device according to claim 1, wherein an angular accuracy of less than or equal to 0.1 between the differently magnetized regions is achievable when the hard-magnetic layer is magnetized.

9. The magnetic signal device according to claim 1, wherein the supporting element is non-magnetic.

10. The magnetic signal device according to claim 1, wherein the hard-magnetic layer has been applied to the supporting element by at least one of the following methods: hollow cathode gas flow sputtering hollow cathode sputtering electroplating PVD method CVD method plasma spraying.

11. A magnetic detection device with the magnetic signal device according to claim 1 and a sensor unit with a sensor working with a XMR and/or Hall measuring method.

12. The magnetic detection device according to claim 11, wherein a distance of 0.1 mm to 3 mm is provided between the sensor and the magnetic signal device.

13. The magnetic detection device according to claim 11, wherein the sensor and the magnetic signal device have a resolution of 10 to 20 bits, in particular on one or more tracks.

14. A method for producing the magnetic signal device according to claim 1, wherein the hard-magnetic layer is applied directly from the gas phase to the supporting element by one of the following methods: hollow cathode gas flow sputtering hollow cathode sputtering electroplating PVD method CVD method plasma spraying.

Description

[0038] The invention is explained below with reference to several non-limiting schematic figures. In the drawings:

[0039] FIG. 1 is a schematic perspective view of a magnetic signal device,

[0040] FIG. 2 is a schematic view of a magnetic detection device according to the invention in a plan view,

[0041] FIG. 3 is a sectional view of a part of a magnetic signal device.

[0042] FIG. 1 shows a schematic representation of a magnetic signal device 1. The magnetic signal device 1 has a rotationally symmetrical pole wheel 2. This pole wheel 2 is non-rotatably connected to a shaft 3. The shaft 3 rotates around an axis of rotation 4 and is connected, for example, to a gearbox or a drive machine (not shown). Thus, the rotation and/or position of the shaft 3 can be measured with the pole wheel 2.

[0043] As can be further seen in FIG. 1, the pole wheel has corresponding sections 5, 6, 7, 8, 9, 10, 11, 12, which are provided with a hard-magnetic layer with alternating magnetisation as magnetic poles. The hard-magnetic layer is magnetised via a suitable magnetisation device. As shown in FIG. 1 and FIG. 2, the hard-magnetic layer is arranged on the front surface of the pole wheel as well as on the radial circumferential surface. In FIG. 2, the individual poles 8, 9, 10, 11 are shown on a part of the radial circumferential surface. In addition, a detector 12 is shown, which is arranged at a predetermined distance to the pole wheel 2. The detector 12 is, for example, a detector/sensor based on the XMR and/or Hall measurement method and measures the rotation and/or position of the pole wheel 2 in high resolution.

[0044] FIG. 3 shows a detailed schematic of the structure of the pole wheel 2. The pole wheel 2 has a supporting structure 13, for example a ceramic and metallic disc. The hard-metallic layer according to the invention is applied to this supporting structure 13. In the case shown, the hard-metallic layer is applied to the entire radial circumferential surface and to one of the two end faces of the pole wheel. According to a particular embodiment of the invention, the hard-magnetic layer is provided only in the scanning region of the sensor 12. According to a further preferred embodiment of the invention, a protective layer 15 is provided over the hard-magnetic layer to protect the scanned hard-magnetic layer from damage and/or environmental influences.

[0045] According to a particular embodiment of the invention, the system-immanent disadvantages of magnetic rotary encoders can be compensated for with the use of pole wheels that use a hard-magnetic layer, in particular a cobalt samarium layer (CoSm), instead of a polymer-based composite layer, preferably without application of a polymer matrix.

[0046] CoSm has an excellent temperature resistance with a Curie temperature of more than 700 C. Furthermore, the very homogeneous microcrystalline structure of the layer in combination with a well controllable layer thickness allows very precise magnetisation with an angular accuracy of less than 0.1. If such pole wheels are combined with the appropriate sensors, resolutions of up to 18 bits can be achieved. This not only makes it possible to achieve accuracies that could previously only be covered by optical systems, but also to achieve a known robustness. The accuracy that can be achieved also meets the criteria for use in electric motors to control the rotors as a replacement for resolvers.

[0047] Hollow cathode gas flow sputtering, PVD, PECVD, CVD or plasma spraying, preferably hollow cathode gas flow or PVD method, is used for high-precision application to the substrates. The layer thicknesses range between 1 and 150 m. Suitable substrates are metallic materials such as steel, stainless steel, copper, brass or aluminium, although non-ferromagnetic materials are preferred.

[0048] Another advantage over the state of the art is the insensitivity to organic solvents, oils as well as greases, since in particular no carbon-based polymers are used. Especially in environments with oil mist, which are found in the field of high-performance electric motors and drive trains of e-vehicles, among other things, this innovation represents a decisive added value for increasing efficiency.

[0049] Furthermore, it is possible to dispense with the housing and use a combination of a pole wheel that is placed directly on the shaft and a separate analyser unit (bearingless encoders). On the one hand, this makes it possible to integrate the measuring unit directly, e.g. in an electric motor, and on the other hand, no free end of the shaft is required for mounting.

[0050] If higher rotation speeds are required, conventional systems either require a support ring on the outside of the pole wheel or gears must be used as signal generators (back-biased arrangement). However, this is at the expense of accuracy; in addition, such a configuration requires a very small distance between the sensor and the wheel, which often cannot be guaranteed due to real-world tolerances.