Apparatus for measuring a mechanical load and method therefor

Abstract

The invention relates to an apparatus (1) for measuring a mechanical load in a body (6) by means of a magnetic field sensor (2) and a magnetic field generating device, which can be used to generate a magnetic field in the body (6), wherein the magnetic field sensor (2) is designed to detect a change in the magnetic field in the body (6) owing to a mechanical force acting on the body (6). In order to enable a measurement of the mechanical load with particularly high accuracy and without special requirements regarding a material for the body (6), the invention provides for a magnetic field to be detectable by means of the magnetic field sensor (2) in a magnetic measuring direction (4), with this measuring direction (4) being oriented at a measuring angle (a) with respect to a field direction (5) of the magnetic field which can be generated by the magnetic field generating device. The invention further relates to a method for determining a mechanical load on a body (6) by means of an apparatus (1), wherein a magnetic field is applied to the body (6) by means of a magnetic field generating device, and a change in a magnetic field in a magnetic measuring direction (4) caused by the mechanical load on the body (6) is measured by means of a magnetic field sensor (2).

Description

[0001] Device for measuring a mechanical load and method for doing so

[0002] The invention relates to a device for measuring a mechanical load in a body by means of a magnetic field sensor and a magnetic field generation device with which a magnetic field can be generated in the body, wherein the magnetic field sensor is designed to detect a change in the magnetic field in the body due to a mechanical force acting on the body.

[0003] The invention further relates to a method for determining a mechanical load on a body with a device, wherein a magnetic field is applied to the body by means of a magnetic field generating device and a change in a magnetic field caused by the mechanical load on the body is measured with a magnetic field sensor in a magnetic measuring direction.

[0004] From the prior art, in particular documents US 3,311,818, US 5,195,377 and WO 0179801 A2, it is known to measure forces acting on a body using magnetoelastic sensors. This utilizes the physical effect that a force acting on a body, especially in ferromagnetic materials, causes a change in the orientation or field direction of magnetic regions, which can be measured by means of a magnetic field sensor.

[0005] A disadvantage of methods and devices known from the prior art has been found to be that only an insufficiently high level of accuracy is achieved.

[0006] This is where the invention comes in. The object of the invention is to provide a device of the type mentioned above with which a mechanical load can be measured with particularly high accuracy.

[0007] Furthermore, a method of the type mentioned at the beginning will be specified, with which a particularly precise determination of a mechanical load is possible.

[0008] The first problem is solved according to the invention by a device of the aforementioned type.

[0009] A method in which a magnetic field can be detected with the magnetic field sensor in a magnetic measuring direction, which measuring direction is aligned at a measuring angle, in particular a measuring angle of 10 degrees to 170 degrees, to a field direction of the magnetic field which can be generated by the magnetic field generating device.

[0010] Preferably, the measuring direction is parallel to a surface of the body when the device is arranged on the body as intended. Of course, the magnetic field sensor can also be designed to detect magnetic fields in different measuring directions, for example, in two or three mutually orthogonal measuring directions.

[0011] Within the scope of the invention, it was discovered that particularly high accuracy can be achieved when the magnetic field sensor measures a magnetic field in a magnetic measuring direction that is not parallel to the field direction of the magnetic field generated by the magnetic field generation device. It has been found that when the magnetic field sensor is aligned to detect a magnetic field parallel to the field direction of the magnetic field generated by the magnetic field generation device, it quickly saturates, rendering the sensor insensitive to changes in the magnetic field due to mechanical loads, and these changes can no longer be detected. Within the scope of the invention, it was discovered that a change in the magnetic field due to mechanical load also occurs in a direction that is at a measuring angle used for orientation or...The direction of the magnetic field imposed by the magnetic field generating device is of much greater use for assessing a mechanical load acting on the body than a change in the magnetic field direction of the imposed magnetic field.

[0012] In contrast to devices known from the prior art, a higher level of accuracy is thus achieved, even without corresponding conditioning of the object being measured (e.g., hardening, shot peening, premagnetizing). Furthermore, in conjunction with a device according to the invention, bodies made of any ferromagnetic material, in particular ferromagnetic steels, can be used, whereas devices of the prior art often require a defined chemical composition of the body to be examined, for example, a specific nickel content, carbon content, etc. The device according to the invention therefore places no special requirements on the material of the body.

[0013] With a method according to the invention, high measurement accuracy is achieved on the one hand, but also high repeatability on the other hand, so that the device is also suitable for carrying out a large number of measurements at short intervals.

[0014] In principle, mechanical stress can also be measured with a magnetic field sensor without a magnetic field generation device, since a mechanical stress on a ferromagnetic body causes a change in the orientation of magnetic regions within the body, a change which can be detected by the magnetic field sensor. However, this change depends on the prior orientation of the magnetic regions and is therefore not suitable for accurately measuring mechanical stress without precise knowledge of this prior orientation. Using a magnetic field generation device, which can be an electromagnet or a permanent magnet, a so-called bias magnetic field is applied to the body, resulting in a uniform orientation of the magnetic regions and a known initial magnetic state before the mechanical stress is applied. By detecting a change in this orientation, or...By determining the field direction caused by a mechanical load, the mechanical load can be accurately measured, resulting in high sensitivity.

[0015] It is particularly preferred that the magnetic field sensor is arranged relative to the magnetic field generating device such that the magnetic measuring direction is aligned at a measuring angle of 70 degrees to 110 degrees, particularly normal or at a measuring angle of 90 degrees, with a field direction of the magnetic field generated by the magnetic field generating device, especially the magnetic field in the body, particularly when the device is arranged on the body. This achieves a particularly high sensitivity and effectively prevents the sensor from saturating prematurely. The device can be in direct contact with the body to perform a measurement. However, it can also be provided that an air gap remains between the device and the body, thus enabling the device to be used for non-contact force measurement. This makes it particularly possible to measure forces on moving objects or...to detect stresses acting on these, in particular mechanical loads on wheels, shafts, wheelsets and the like, without the need to instrument these bodies themselves, for example with strain gauges.

[0016] The magnetic measuring direction can, in principle, be oriented arbitrarily relative to a surface of the body or of the permanent magnet(s). Preferably, however, the magnetic field sensor is arranged such that the magnetic measuring direction is approximately parallel to a surface through which the magnetic field exits the magnetic field generating device and / or enters the body. Typically, field lines passing through this surface are oriented perpendicular to it. This surface can, for example, be a surface of the body against which the device is placed. The surface can also be a contact surface of the device, with which the device is placed against the body, optionally at a distance.

[0017] It is advantageous to include a distance sensor to detect the distance between the device and the body, particularly between the magnetic field sensor and the body, and / or between the distance sensor and the body. When the device is used for non-contact measurement of mechanical loads, the magnetic field strength measured by the magnetic field sensor depends on both the mechanical load and the distance between the body and the device, since a greater distance naturally results in a lower magnetic flux. By combining the magnetic field sensor with a distance sensor, a reduction in the measured magnetic field caused by a greater distance can be computationally compensated for, thus ensuring that changes in distance, such as those caused by unevenness or other factors, remain consistent.An out-of-roundness in a wheel that is to be analyzed can cause a highly accurate measurement to be carried out.

[0018] Particularly accurate measurements are possible when the distance sensor is positioned relative to the magnetic field sensor such that, when the device is mounted on a body, the magnetic field sensor is located between the distance sensor and the body. The distance sensor thus measures the distance to the body through the magnetic field sensor. This ensures that the distance sensor accurately detects the distance between the magnetic field sensor and the body. The distance sensor can be designed in various ways, for example, as a capacitive sensor. To achieve a particularly robust design while simultaneously ensuring accurate measurements, an inductive distance sensor has proven effective.

[0019] It is particularly preferred that the distance sensor has a coil which can generate a magnetic field normal to the magnetic measuring direction.

[0020] The coil, which is commonly used in inductive distance sensors, can then, for example, be arranged directly below the magnetic field sensor, which can be designed as an integrated circuit or computer chip on a circuit board, so that the coil is located between the chip and the circuit board or within the circuit board itself. Preferably, the magnetic field generated by the distance sensor is perpendicular to the magnetic measuring direction, so that the magnetic field measured along the magnetic measuring direction is not influenced by the magnetic field of the distance sensor.

[0021] However, it is also possible to arrange the distance sensor and the magnetic field sensor in such a way that the magnetic field of the distance sensor has a component in the direction of measurement. It is understood that if the magnetic field of the distance sensor has a component in the direction of magnetic measurement, a magnetic field measured by the magnetic field sensor can then be corrected, if necessary, by a magnetic field generated by the coil in order to avoid any resulting measurement error.

[0022] It is advantageous if the magnetic field sensor is arranged on a substrate, particularly a circuit board, with a coil of the distance sensor being arranged in or on the substrate, especially between the substrate and the magnetic field sensor. Thus, the coil or the distance sensor is positioned directly behind the magnetic field sensor and measures the distance between the magnetic field sensor and the object, allowing for particularly accurate detection of changes in distance. Preferably, the distance sensor is arranged upstream or downstream of the magnetic field sensor in a distance measurement direction. In this way, a change in the distance between the magnetic field sensor and the object, which causes a change in the magnetic field measured by the magnetic field sensor, can be measured particularly well.

[0023] Preferably, the magnetic field generation device is designed to generate different magnetic fields within the body, with the field lines of the magnetic fields being aligned at a field angle of 10 degrees to 170 degrees to each other. In this way, mechanical loads in different directions can be accurately detected. Changes in the magnetic fields in the different directions can be detected, for example, with a magnetic field sensor capable of detecting magnetic fields in different measurement directions and / or with different magnetic field sensors. Preferably, the generated magnetic fields lie in a plane, this plane typically being approximately parallel to a surface of the body, on which surface the device is arranged with or without a gap.The magnetic fields can also be arranged along a curved path, which preferably lies in a plane, in particular in a plane parallel to a surface of the body.

[0024] It is also possible for the magnetic fields to be located in a non-planar surface, such as a cylindrical surface or a conical surface. Such an arrangement can be particularly advantageous when mechanical loads, especially forces and moments, are to be detected in a shaft. The device can then include magnetic field generating units and magnetic field sensors arranged in a non-planar surface, such as a cylindrical surface or a conical surface. The device can be designed to completely encircle the shaft to be analyzed.

[0025] It is advantageous if at least one, preferably each, of the magnetic fields, whose field lines have different field directions, is assigned a magnetic field sensor. In this way, forces in different directions or mechanical stresses can be detected with particular accuracy. The measuring directions of the magnetic field sensors are preferably approximately perpendicular to the field directions of the magnetic fields, which preferably lie in a plane. Typically, the measuring directions of the magnetic field sensors lie in a plane that is parallel to the plane in which the field directions of the generated magnetic fields lie.

[0026] It is advantageous if the magnetic field generation device is designed to generate magnetic fields within the body, with the field directions of the magnetic fields arranged at field angles of 10 to 90 degrees, particularly 60 degrees, to each other. Using three magnetic field sensors and three magnetic fields, each with field directions aligned at these angles, provides redundancy, especially since determining mechanical loads in a plane would already be possible with only two sensors and two differently oriented magnetic fields. This redundancy allows for the rapid identification of a potentially defective magnetic field sensor and enables the continuation of the measurement even if one sensor fails.

[0027] It is advantageous for the device to include a data processing unit, which is connected to the magnetic field sensor and used to calculate a value for a mechanical load, in particular a force, depending on a measured value for the magnetic field strength. A relationship between the measured magnetic field strength and the mechanical load can be determined computationally and / or empirically and stored in the data processing unit. The relationship between the measured magnetic field strength and the mechanical load can be linear or non-linear. The relationship can be positive, meaning that a higher magnetic field strength results in a greater mechanical load. Depending on the orientation of the measurement direction relative to the field direction, the relationship can also be negative.

[0028] The data processing device is therefore preferably configured to calculate a value for the mechanical load, which is positively or negatively dependent on the measured strength of the magnetic field and positively or negatively dependent on a measured distance. The data processing device is preferably connected to the distance sensor and configured to calculate a value for a mechanical load, in particular a force, depending on a measured value for the strength of the magnetic field and a distance measured by means of the distance sensor.

[0029] Preferably, the data processing device is set up to calculate a value for the mechanical load, which value depends on a vector sum of the measured strength of the magnetic field and the measured distance.

[0030] It is further preferably provided that the data processing device is connected to the magnetic field generation device and configured to control the magnetic field generation device. If the magnetic field generation device is designed as an electromagnet or includes an electromagnet, it may be provided that the strength and / or direction of the magnetic field generated by the magnetic field generation device can be changed by means of the data processing device. This allows, for example, forces in different directions and / or forces of different strengths to be detected particularly well, or prevents saturation of a magnetic field sensor.

[0031] It is advantageous to have multiple magnetic field generation devices and multiple magnetic field sensors, with the data processing unit configured to calculate mechanical loads in different directions. The data processing unit is thus connected to the individual magnetic field sensors and configured to calculate forces in different directions based on the measurement results and the geometric arrangement of the individual sensors.

[0032] Particularly when the device is used to detect mechanical loads on a rotating body, it is preferred that the data processing unit is configured to detect a rotational speed based on measured cyclic values ​​with respect to the magnetic field and / or distance. This eliminates the need for a separate speed sensor. In this case, the data processing unit is thus configured to detect the periodicity of a measurement signal, for example, a distance, and to calculate a rotational speed based on this periodicity. Such detectable periodic changes in distance along a circumference can be caused by manufacturing tolerances or protrusions or depressions in the body, such as screw heads or bores.

[0033] The magnetic field generation device can be designed with either electromagnets or permanent magnets. To achieve particularly low energy consumption, it is preferred that the magnetic field generation device incorporates one or more permanent magnets. The permanent magnets are typically arranged such that, when the device is positioned against a body under investigation—that is, with or without a gap between the device and the body—they generate one or more magnetic fields within the body, aligning magnetic regions in a body made of a ferromagnetic material in one or more directions.For example, the magnetic field generating device can be arranged relative to the magnetic field sensor in such a way that a magnetic north pole is located on one side of the magnetic field sensor and a magnetic south pole is located on the other side of the magnetic field sensor, resulting in a magnetic field in the body with a field direction that is normal or orthogonal to a measuring direction of the magnetic field sensor.

[0034] It is particularly preferred that at least three permanent magnets are provided, which form vertices of a triangle, in particular an isosceles triangle, and especially preferably an equilateral triangle.

[0035] The further problem is solved according to the invention by a method of the type mentioned at the outset, wherein a magnetic field is measured with the magnetic field sensor at a measuring angle to a field direction of the magnetic field generated by means of the magnetic field generation device in order to determine the mechanical load, wherein the determination is preferably carried out with a device according to the invention.

[0036] It is advantageous to also consider the distance between the magnetic field sensor and the body when determining the mechanical load. This allows for the computational compensation of a lower magnetic field strength measured by the sensor, which would result from an increased distance. Preferably, both the distance and the measured magnetic field strength are incorporated into the determination of the mechanical load. The distance can be used to compensate for a decrease in the measured magnetic field strength with increasing distance from the body due to the larger air gap, and also to determine the mechanical load as a function of body deformation.

[0037] It is advantageous if, first, a mechanical load is calculated as a function of deformation in the area of ​​the distance sensor using a model and / or a relationship between deformation and load is empirically determined, and then the deformation in this area is measured using the distance sensor, after which the mechanical load is determined based on the measured deformation.

[0038] For example, when applying the method to determine a mechanical load on a wheel or shaft, a defined mechanical load can be applied and a change in the measured magnetic field can be measured in order to determine a relationship between the measured magnetic field or its strength and the mechanical load. This relationship can be linear or non-linear.

[0039] Preferably, the body is moved during the measurement. When using the inventive method to measure a mechanical load on a moving body, it is possible to determine mechanical loads without instrumenting the body, which would not be possible, in particular, when using strain gauges.

[0040] It is advantageous if the body rotates during the measurement, particularly around an axis of rotation approximately perpendicular to the measurement direction, and if the rotational speed is detected by means of the magnetic field sensor and / or the distance sensor. In this way, mechanical loads, such as those related to the rotational speed, like loads due to imbalance, can also be easily determined. It can be provided that the body is spaced away from the device, particularly from the magnetic field sensor and the magnetic field generation device, during the measurement, for example by a distance of 0.1 mm to 20 mm, preferably 0.5 mm to 10 mm.In this way, non-contact measurement of mechanical stress in the body is easily possible, so that, for example, mechanical stresses in wheelsets of rail vehicles can be continuously measured during operation without having to attach devices such as strain gauges to the body itself.

[0041] The device can be used to measure the mechanical load on any body, in particular a rotating body such as a wheel of a motor vehicle.

[0042] Preferably, the body is a wheel or axle of a rail vehicle, and the load is determined contactlessly during operation. Wheelsets of rail vehicles often have identical dimensions and frequently similar material properties, so that a once-determined relationship between magnetic field strength and / or distance and mechanical load can be reused many times to determine mechanical loads based on measured magnetic field strengths and distances.

[0043] Further features, advantages, and effects of the invention will become apparent from the exemplary embodiments described below. The drawings referenced therein show:

[0044] Figs. 1a to 3b show different devices;

[0045] Fig. 4 shows another device according to the invention;

[0046] Fig. 5 shows another device according to the invention;

[0047] Fig. 6 shows a measuring setup;

[0048] Fig. 7 shows a wheel with three devices.

[0049] Figures 1a and 1b show a first embodiment of a device 1 according to the invention, with Figure 1a showing a side view and Figure 1b a top view. As shown, the device 1 comprises a magnetic field generation device formed by two permanent magnets 3 and a magnetic field sensor 2. As can be seen, the permanent magnets 3 are arranged on both sides of the magnetic field sensor 2 and are oriented such that one north pole and the other south pole face the body 6. Accordingly, a magnetic field in the body 6 is oriented along a field direction 5 from north pole to south pole. The magnetic field sensor 2 has a measuring direction 4 which is parallel to the surface 11 of the body 6 shown in Figure 1b and is at a measuring angle α of 90 degrees, i.e., normal or orthogonal, to the field direction 5 of the magnetic field in the body 6, so that changes in the magnetic field caused by a mechanical load can be detected effectively.In Fig. 1a, the measuring direction 4 is therefore normal to the image plane and is not shown.

[0050] As can be seen in Fig. 1a, the device 1 is arranged relative to the body 6 such that a contact surface 12 of the device 1 is located on a surface 11 of the body 6, so that magnetic field lines emerge from the device 1 along the field direction 5 via the contact surface 12 and enter the body 6 via the surface 11. The surface 11 and the contact surface 12 are arranged approximately parallel to each other and at a distance of approximately 0.5 mm to 10 mm relative to each other. As can be seen by comparing Fig. 1a with Fig. 1b, the measuring direction 4 lies in a plane that is parallel to both the contact surface 12 and the surface 11.

[0051] Figures 2a and 2b show another variant of a device 1 according to the invention, comprising a body 6 in which a mechanical load is to be detected. Again, Figure 2a shows a side view and Figure 2b a top view of the body and the device. Here, the permanent magnets 3 are oriented at a different angle than the device 1 shown in Figure 1; however, this arrangement also produces a magnetic field in the body 6 with a field direction 5 corresponding to the field direction 5 of the magnetic field in Figure 1. Thus, a measuring angle α of 90 degrees between the measuring direction 4 and the field direction 5 in the body 6 is also obtained here.

[0052] Figures 3a and 3b show another example of a device 1 according to the invention with a body 6. Here, the permanent magnets s are oriented in the same direction and their north poles are oriented towards the body 6, resulting in a magnetic field with field lines oriented normal to a surface 11 of the body 6 in the area of ​​the magnetic field sensor 2. Here too, the measuring direction 4 is normal to the field direction 5, or rather, the measuring direction 4 is oriented at a measuring angle α of 90 degrees to the field direction 5, so that this arrangement of the magnets also results in high sensitivity and repeatability.

[0053] Fig. 4 shows another example of a device 1 according to the invention. Here, a magnetic field sensor 2 and a distance sensor 7 are arranged to enable particularly precise detection of the distance between the magnetic field sensor 2 and the body 6. The magnetic field generating device, which is again formed by two permanent magnets 3, as well as the distance sensor 7, which is preferably designed as an inductive distance sensor 7, and the magnetic field sensor 2 are fixed on a circuit board 9. As can be seen, the distance sensor 7 is arranged directly between the magnetic field sensor 2 and the circuit board 9, so that a distance between the magnetic field sensor 2 and the body 6 can be precisely detected in the direction normal to the measuring direction 4 or normal to the surface 11 of the body 6, so that the distance sensor 7 generally measures the normal distance.The distance sensor 7 is thus arranged downstream of the magnetic field sensor 2 in a distance measurement direction 13, in which the distance can be measured, so that a distance between the magnetic field sensor 2 and the body 6 can be precisely determined. This distance can be used to compensate for a measured strength of the magnetic field, which decreases with increasing distance from the body 6 due to the larger air gap, as well as to determine a mechanical load depending on a deformation of the body 6.

[0054] Body 6 can be used. Depending on the structure of body 6 and the direction of the load, an increasing mechanical load can cause an increase or a decrease in the distance between the device 1 and body 6. A relationship between distance and mechanical load can be determined computationally and / or empirically.

[0055] Fig. 5 shows a device 1 according to the invention with five permanent magnets 3 and six magnetic field sensors 2, wherein the sensors are arranged on connecting lines between the permanent magnets 3. Due to this arrangement, different magnetic fields with different field directions 5 result in the body 6, i.e., directions along which these magnetic fields are aligned. The permanent magnets 3 can, for example, be oriented according to one of the arrangements shown in Figs. 1a to 3b. The magnetic fields are thus at field angles β to each other, so that it is possible to determine forces in correspondingly different directions or to detect force components of the forces in different coordinate directions. By measuring magnetic fields normal to the correspondingly oriented magnetic fields, forces in the body 6 can be detected in different directions.Typically, measurement signals from the individual magnetic field sensors 2, which each represent detected forces or voltages in specific directions, are added vectorially to determine the magnitude and direction of an acting mechanical load.

[0056] Fig. 5 shows the arrangement of permanent magnets 3 and magnetic field sensors 2 in a plane. It is understood that arrangements not in a plane are also possible. Fig. 5 can therefore also be understood as a development of permanent magnets 3 and magnetic field sensors 2 arranged on the lateral surface of a cylinder.

[0057] Fig. 6 shows a measuring arrangement with magnetic field lines, field directions 5, and measuring directions 4. As can be seen, magnetic fields with field directions 5 are generated in the body 6 by the magnetic field generating devices, while the body 6 has randomly oriented magnetic regions away from these magnetic field generating devices. The measuring directions 4 of the two magnetic field sensors 2 are also oriented approximately perpendicular to the field directions 5 generated by the magnetic field generating devices, so that changes in these magnetic fields caused by forces can be detected particularly well.

[0058] Here too, it is possible to determine the magnitude and direction of acting mechanical loads or stresses in body 6 in a plane, since the magnetic field sensors 2 allow loads to be determined in different directions. In simplified terms, the components of an applied mechanical load in the x-direction and y-direction can be determined as follows:

[0059] Fx = k1x * B1 - k2x * B2 + dx

[0060] Fy = k1y * B1 + k2y * B2 + dy where

[0061] B1 and B2 are the field strengths detected by the magnetic field sensors 2 along the individual measurement directions 4, k1x to k2y are material- and direction-dependent factors which are determined empirically and / or computationally, and dx, dy are constants which can also take the value zero.

[0062] Fig. 7 shows a wheel 8 with three devices 1 for measuring mechanical loads. These devices can be arranged at different positions relative to and at different distances from the wheel 8 to enable contactless measurement of mechanical loads on the wheel 8, even during operation. Simulations and / or empirical methods can be used to determine in advance which stresses at the individual positions of the devices 1 lead to which measurement results from the magnetic field sensors 2. This allows constants to be determined according to the equations above, enabling the determination of stresses in the wheel 8 during operation based on the measured field strengths and, if applicable, distances. The measuring directions 4 of the devices 1, along which magnetic field strengths can be measured, are in this case approximately perpendicular to a rotational axis 10 of the wheel 8.

[0063] Using a method according to the invention and a device 1 for this purpose, the determination of mechanical loads in a body 6 is possible with high accuracy, even at a distance or without contact. Applications are possible for moving bodies 6 as well as for stationary bodies 6, in particular also for the assessment of

[0064] Residual stresses, for example in welds and the like.

Claims

Patent claims 1. Device (1) for measuring a mechanical load in a body (6) by means of a magnetic field sensor (2) and a magnetic field generation device with which a magnetic field can be generated in the body (6), wherein the magnetic field sensor (2) is designed to detect a change in the magnetic field in the body (6) due to a mechanical force acting on the body (6), characterized in that a magnetic field can be detected with the magnetic field sensor (2) in a magnetic measuring direction (4), which measuring direction (4) is aligned at a measuring angle (a) to a field direction (5) of the magnetic field which can be generated by the magnetic field generation device.

2. Device (1) according to claim 1 , characterized in that the magnetic field sensor (2) is arranged relative to the magnetic field generating device such that the magnetic measuring direction (4) is normal to a field direction (5) of the magnetic field generated by the magnetic field generating device, in particular when the device (1) is arranged on the body (6).

3. Device (1) according to claim 1 or 2, characterized in that the magnetic field sensor (2) is arranged such that the magnetic measuring direction (4) is approximately parallel to a surface over which the magnetic field exits from the magnetic field generating device and / or enters the body (6), in particular parallel to a surface (11) of the body.

4. Device (1) according to one of claims 1 to 3, characterized in that a distance sensor (7) is provided to detect a distance between the device (1) and the body (6), in particular between the magnetic field sensor (2) and the body (6) and / or between the distance sensor (7) and the body (6).

5. Device (1) according to claim 4, characterized in that the distance sensor (7) is arranged relative to the magnetic field sensor (2) such that, when the device (1) is arranged on a body (6), the magnetic field sensor (2) is positioned between the distance sensor (7) and the body (6).

6. Device (1) according to claim 5, characterized in that the distance sensor (7) is designed as an inductive distance sensor (7).

7. Device (1) according to claim 6, characterized in that the distance sensor (7) has a coil which can generate a magnetic field normal to the magnetic measuring direction (4).

8. Device (1) according to one of claims 4 to 7, characterized in that the magnetic field sensor (2) is arranged on a substrate, in particular a circuit board (9), wherein a coil of the distance sensor (7) is arranged in or on the substrate, in particular between the substrate and the magnetic field sensor (2).

9. Device (1) according to one of claims 4 to 8, characterized in that the distance sensor (7) is arranged upstream or downstream of the magnetic field sensor (2) in a distance measuring direction (13).

10. Device (1) according to one of claims 1 to 9, characterized in that the magnetic field generation device is designed to generate different magnetic fields in the body (6), wherein the field lines of the magnetic fields are aligned to each other at a field angle (β) of 10 degrees to 170 degrees.

11. Device (1) according to claim 10, characterized in that at least one, preferably each, of the magnetic fields which have field lines of different field directions (5) is assigned a magnetic field sensor (2).

12. Device (1) according to claim 10 or 11, characterized in that the magnetic field generating device is designed to generate magnetic fields in the body (6), wherein field directions (5) of the magnetic fields are arranged at a field angle (β) of 10 degrees to 90 degrees, in particular 60 degrees each, to each other.

13. Device (1) according to one of claims 1 to 12, characterized in that the device (1) has a data processing unit, wherein the data processing unit is connected to the magnetic field sensor (2) and is used for Calculation of a value for a mechanical load, in particular a force, depending on a measured value for the strength of the magnetic field.

14. Device (1) according to claim 13, characterized in that the data processing device is connected to the magnetic field generation device and is configured to control the magnetic field generation device.

15. Device (1) according to claim 13 or 14, characterized in that a distance sensor (7) is provided and the data processing device is connected to the distance sensor (7) and is used to calculate a value for a mechanical load, in particular a force, depending on a measured value for the strength of the magnetic field and a distance measured by means of the distance sensor (7).

16. Device (1) according to claim 15, characterized in that the data processing device is configured to calculate a value for the mechanical load, which value depends on a vector sum of measured strength of the magnetic field and measured distance.

17. Device (1) according to one of claims 13 to 16, characterized in that several magnetic field generating devices and several magnetic field sensors (2) are provided, wherein the data processing device is set up to calculate mechanical loads in different directions.

18. Device (1) according to one of claims 13 to 17, characterized in that the data processing device is configured to detect a rotational speed depending on measured cyclic values ​​with respect to magnetic field and / or distance.

19. Device (1) according to one of claims 1 to 18, characterized in that the magnetic field generating device has one or more permanent magnets (3).

20. Device (1) according to claim 19, characterized in that at least three permanent magnets (3) are provided, which form the vertices of a triangle, in particular an isosceles triangle, especially preferably an equilateral triangle.

21. Method for determining a mechanical load on a body (6) using a device (1), wherein a magnetic field is applied to the body (6) by means of a magnetic field generating device and a change in a magnetic field caused by the mechanical load on the body (6) is measured in a magnetic measuring direction (4) using a magnetic field sensor (2), characterized in that a magnetic field is measured with the magnetic field sensor (2) at a measuring angle (a) to a field direction (5) of the magnetic field generated by means of the magnetic field generating device in order to determine the mechanical load, wherein the determination is carried out in particular using a device (1) according to one of claims 1 to 20.

22. Method according to claim 21, characterized in that, in order to determine the mechanical load, a distance between the device (1), in particular between the magnetic field sensor (2), and the body (6) is further taken into account.

23. Method according to claim 22, characterized in that the distance and the measured strength of the magnetic field are incorporated into a determination of the mechanical load.

24. Method according to claim 22 or 23, characterized in that, first, a mechanical load is calculated as a function of a deformation in the area of ​​the distance sensor (7) using a model and / or a relationship between deformation and load is empirically determined, and subsequently the deformation in this area is measured using the distance sensor (7), after which the mechanical load is determined on the basis of the measured deformation.

25. Method according to one of claims 21 to 24, characterized in that the body (6) is moved during the measurement.

26. A method according to any one of claims 21 to 25, characterized in that the body (6) is spaced apart from the device (1), in particular from the magnetic field sensor (2) and from the magnetic field generating device, during the measurement.

27. A method according to any one of claims 21 to 26, characterized in that the body (6) rotates during the measurement, in particular about an axis of rotation (10) approximately orthogonal to the measurement direction (4), and a rotational speed is detected by means of the magnetic field sensor (2) and / or the distance sensor (7).

28. A method according to any one of claims 21 to 27, characterized in that the body (6) is a wheel (8) or an axle of a vehicle, in particular a rail vehicle, wherein the load is determined without contact during operation.

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