DE102021120522A1 - sensor arrangement - Google Patents

Abstract

The invention relates to a sensor arrangement (1), comprising a first magnetic core (4) extending along a first longitudinal axis (3), a second magnetic core (6) extending along a second longitudinal axis (5), and a third magnetic core (6) extending along a third longitudinal axis (7 ) extending magnetic core (8), wherein the first longitudinal axis (3), the second longitudinal axis (5) and the third longitudinal axis (7) run parallel to one another, wherein the first magnetic core (4) and the second magnetic core (6) have a flux-guiding element ( 9) are spaced apart from one another, and the third magnetic core (8) has a second flux-guiding element (10) running orthogonally thereto, the first flux-guiding element (9) and the second flux-guiding element (10) crossing over one another without contact at a common star point (12), A first transmitting coil (13) is wound around the first magnetic core (4), a first receiving coil (14) is wound around the second magnetic core (6), and a second E receiving coil (15) is wrapped, and the longitudinal axes (3,5,7) of the magnetic cores (4,6,8) are offset by 90 ° to each other, wherein the sensor arrangement (1) has a control unit (21) which with is connected to the first transmission coil (13) so that it can be charged with alternating current and is electrically connected to the receiver coils (14, 15), the control unit (21) being set up to carry out a first measurement cycle in which the first transmission coil (13) is charged with alternating current.

Description

The present invention relates to a sensor arrangement for the contactless measurement of normal and shear stresses in a component, comprising a first magnetic core extending along a first longitudinal axis, around which a first transmitting coil is wound, a second magnetic core extending along a second longitudinal axis, and a third magnetic core extending along a third longitudinal axis, around which a second receiving coil is wound, the first magnetic core and the second magnetic core being spaced apart from one another via a first flux-guiding element, and in the magnetic flux path between the first magnetic core and the second magnetic core, this flux path from a first receiving coil is wound around and the third magnet core is connected to a second flux-guiding element, wherein the first flux-guiding element and the second flux-guiding element intersect without contact at a common star point, the sensor arrangement having a control unit, which is connected to the first transmitting coil so that it can be subjected to alternating current and is electrically connected to the receiving coils.

Magnetostrictive measurement methods for the non-contact determination of normal or shear stresses in a component are basically known from the prior art. For example, "passive" magnetostrictive measuring methods are known in which a component is permanently magnetized and the load-dependent external magnetic field is then measured. A major disadvantage of this method is that special materials with special heat treatment are required, which makes the measurement setup comparatively expensive.

In addition, so-called "active" magnetostrictive measuring arrangements are also known, with which normal or shear stresses in a component can be determined. These used the effect that the magnetic permeability of a material changes depending on the load. Measuring magnetic permeability, or more specifically susceptibility, does not require the device to be permanently magnetized, allowing the use of less expensive materials and heat treatment.

In the active process, magnetic cores are placed outside the component in such a way that they form a magnetic circuit together with the component. Coils are wound on the magnetic cores. A current i through a so-called transmitter coil causes an alternating magnetic field in the component, which induces a permeability- and thus load-dependent electrical voltage U in one or more receiver coils. Other variables influencing the voltage induced in the receiving coil are, for example, properties of the other components of the magnetic circuit, in particular air gaps. During a measurement, either the voltage or the current is fixed while the other variable is measured.

Various magnetostrictive measuring methods are already known for measuring the torques acting on a component, which are briefly explained below.

DE102018221206 shows, for example, an active magnetostrictive measuring arrangement in a so-called branch design. With the help of a transmitter coil and a branched magnetic core, magnetic fields are generated in a ±45° direction and the induced voltage is measured in two or four receiver coils.

As a further configuration option for a magnetostrictive measuring arrangement, the so-called cross design is known, as is the case, for example, in U.S. 4,939,937 is revealed. Two separate magnetic cores are used here in 0° and 90° directions. The transmitting coil is on one core and the receiving coil is on the other. In the unloaded case, the induced voltage in the receiving coil is zero. However, if there is a shear stress, the magnetic field in the component is "bent" in such a way that a voltage is induced in the receiving coil.

Finally, a magnetostrictive measuring arrangement in a so-called Solenodial design is also known, as is also the case in DE 39 40 220 is described. Here, the shaft on which a torque measurement is to take place has elements that steer the magnetic field in a ±45° direction. This can be, for example, grooves in the material or coatings on or on the shaft. As a result of the principal normal stresses present in the ±45° direction, the permeability changes in these directions, causing a change in the amplitudes of the voltages induced in the receiving coils.

Methods and devices are also known from the prior art which allow tensile and compressive forces to be measured on or in components using magnetostrictive sensors and methods.

For example, A. Bienkowski, R. Szewczyk, "The possibility of utilizing the high permeability magnetic materials in construction of magnetoelastic stress and force sensors", Sensors and Actuators A 113 (2004) page 270-276, describes a magnetostrictive method in which the permeability change of the one subjected to normal stresses component is determined with transmitting and receiving coils that are wound around the loaded component.

Also known is a magnetostrictive sensor marketed by ABB under the brand name “Pressductor”, in which a transmitting coil and a receiving coil are arranged in a ±45° direction to the force to be measured.

The object of the invention is to provide an active magnetostrictive sensor arrangement that determines a measurement of the normal and shear stresses within a component with the most compact and cost-effective design possible.

This object is achieved by a sensor arrangement for contactless measurement of normal and shear stresses in a component, sensor arrangement for contactless measurement of normal and shear stresses in a component, comprising a first magnetic core extending along a first longitudinal axis, around which a first transmitting coil is wound , a second magnetic core extending along a second longitudinal axis, and a third magnetic core extending along a third longitudinal axis, around which a second receiving coil is wound, the first magnetic core and the second magnetic core being spaced apart from one another via a first flux-guiding element, and in the magnetic flux path between the first magnetic core and the second magnetic core, this flux path is wrapped by a first receiving coil, and the third magnetic core is connected to a second flux-guiding element, the first flux-guiding element and the second flux-guiding element being in a common Ste Cross over at a point without contact, the sensor arrangement having a control unit which is connected to the first transmission coil in a manner that can be subjected to alternating current and is electrically connected to the receiver coils, the control unit being set up to carry out a first measurement cycle in which the first transmission coil is subjected to alternating current.

With the help of the sensor arrangement according to the invention, both normal and shear stresses of a plane stress state in a component can be determined. By using only three coils, the sensor arrangement according to the invention can be manufactured particularly inexpensively. Furthermore, a higher number of possible identical parts can be provided by the non-contact intersecting flux guide elements, which also has a positive effect on the production costs.

The sensor arrangement according to the invention can be used, for example, to determine a torsional and bending load on a shaft, for example within a drive train of a motor vehicle.

A control unit, as used in the present invention, is used, in particular, for the electronic control and/or regulation of one or more sensor arrangements according to the invention.

A control unit has in particular a wired or wireless signal input for receiving electrical signals, in particular, such as sensor signals. Furthermore, a control unit likewise preferably has a wired or wireless signal output for the transmission of, in particular, electrical signals, for example to electrical actuators or electrical consumers of a motor vehicle.

Control operations and/or regulation operations can be carried out within the control unit. It is particularly preferred that the control unit includes hardware that is designed to run software. The control unit preferably comprises at least one electronic processor for executing program sequences defined in software.

The control unit can also have one or more electronic memories in which the data contained in the signals transmitted to the control unit can be stored and read out again. Furthermore, the control unit can have one or more electronic memories in which data can be stored in a changeable and/or unchangeable manner.

A control unit can include a plurality of control devices, which are arranged in particular spatially separated from one another in the motor vehicle. Control units are also referred to as electronic control units (ECU) or electronic control modules (ECM) and preferably have electronic microcontrollers for carrying out computing operations for processing data, particularly preferably using software. The control devices can preferably be networked with one another, so that a wired and/or wireless data exchange between control devices is made possible. In particular, it is also possible to network the control units with one another via bus systems present in the motor vehicle, such as a CAN bus or LIN bus.

und eine in dem Bauteil vorliegende Schubspannung entsprechend der Funktion $$\tau =\frac{U_y}{\alpha \cdot U_x}$$

ermittelt und jeweils ein die ermittelte Normalspannung und die ermittelte Schubspannung repräsentierendes Ausgangssignal bereitstellt. In der oben genannten Gleichung zur Ermittlung von σ_x gilt der vorangestellte Faktor 2, wenn das magnetische Feld und Sigma parallel verlaufen. Wenn Sigma und das magnetische Feld senkrecht aufeinander stehen, muss der Faktor 2 durch 1 ersetzt werden.According to an advantageous embodiment of the invention it can be provided that within the first measurement cycle, a voltage amplitude U _x0 in the unloaded state of the component at the first receiving coil, a voltage amplitude U _x im loaded state of the component at the first receiver coil and a voltage amplitude U _y in the loaded state of the component at the second receiver coil are determined, the control unit present in the component normal voltage according to the function $${\sigma }_x=\frac{2}{a}\cdot \left(\frac{u_x}{u_{x0}}-1\right)$$

and a shear stress present in the component according to the function $$\tau =\frac{u_y}{a\cdot u_x}$$

determined and in each case provides an output signal representing the determined normal stress and the determined shear stress. In the above equation for determining σ _x , the preceding factor 2 applies if the magnetic field and sigma are parallel. If sigma and the magnetic field are perpendicular to each other, the factor 2 must be replaced by 1.

In this way, in particular, a torsional moment and a bending moment can be determined in a known direction in a component. Since the calculation is simple, it can also be carried out in real time without too great a demand on processor performance, which also enables a particularly cost-effective design of the sensor arrangement.

eine in dem Bauteil vorliegende zweite Normalspannung entsprechend der Funktion $${\sigma }_y=\frac{1}{\alpha }\cdot \left(2\cdot \frac{U_{yy}}{U_{y0}}+\frac{U_{xx}}{U_{x0}}-3\right)$$

und eine in dem Bauteil vorliegende Schubspannung entsprechend der Funktion $$\tau =\frac{U_{xy}}{\alpha \cdot U_{xx}}=\frac{U_{yx}}{\alpha \cdot U_{yy}}$$

ermittelt und jeweils ein die ermittelte erste Normalspannung, die ermittelte zweite Normalspannung und die ermittelte Schubspannung repräsentierendes Ausgangssignal bereitstellt.According to a further preferred further development of the invention, it can also be provided that the sensor arrangement has a fourth magnetic core along a fourth longitudinal axis, the fourth magnetic core being wound by a second transmission coil which is electrically connected to the control unit and connected to the second flux-conducting element. and the first longitudinal axis and the fourth longitudinal axis run parallel to one another, with the control unit being set up to carry out a first measurement cycle in which the first transmitting coil is charged with alternating current and a voltage U _x0 in the unloaded state of the component at the first receiving coil, a voltage U _xx in the loaded state State of the component at the first receiver coil and a voltage U _xy in the loaded state of the component at the second receiver coil are determined, and carry out a second measurement cycle by the second transmitter coil is acted upon by alternating current and a voltage U _y0 in the unloaded state d of the component at the second receiving coil, a voltage U _yx in the loaded state of the component at the first receiving coil and a voltage U _yy in the loaded state of the component at the second receiving coil are determined, with the control unit determining a first normal voltage present in the component in accordance with the function $${\sigma }_x=\frac{1}{a}\cdot \left(2\cdot \frac{u_{xx}}{u_{x0}}+\frac{u_{yy}}{u_{y0}}-3\right)$$

a second normal stress present in the component according to the function $${\sigma }_y=\frac{1}{a}\cdot \left(2\cdot \frac{u_{yy}}{u_{y0}}+\frac{u_{xx}}{u_{x0}}-3\right)$$

and a shear stress present in the component according to the function $$\tau =\frac{u_{xy}}{a\cdot u_{xx}}=\frac{u_{yx}}{a\cdot u_{yy}}$$

determined and in each case provides an output signal representing the determined first normal stress, the determined second normal stress and the determined shear stress.

With the help of this preferred embodiment of a magnetostrictive sensor arrangement in cross design and the two measurement cycles carried out one after the other, normal and shear stresses of a plane stress state in a component can be determined in a cost-effective and reliable manner.

Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the control unit comprises a signal output via which a signal representing the first normal stress and/or the second normal stress and/or the shear stress − signal can be picked up. For this purpose, for example, one or more plugs or sockets can be provided, which provide a simple and secure electrical connection for signal transmission from the control unit.

According to a further particularly preferred embodiment of the invention, provision can be made for the component to be a shaft, for which the sensor arrangement has proven to be particularly suitable, in particular for rapidly rotating shafts.

Furthermore, the invention can also be further developed such that the sensor arrangement is accommodated in a housing, so that the sensor arrangement can be arranged as a modular component on a component.

The invention will be explained in more detail below with reference to figures without restricting the general inventive idea.

• 1 eine erste Ausführungsform einer Sensoranordnung in einem schematischen Blockschaltbild,
• 2 eine zweite Ausführungsform einer Sensoranordnung in einem schematischen Blockschaltbild,
• 3 einen ersten Messzyklus der zweiten Ausführungsform der Sensoranordnung in einem schematischen Blockschaltbild, und
• 4 einen zweiten Messzyklus der zweiten Ausführungsform der Sensoranordnung in einem schematischen Blockschaltbild.

It shows:

• 1 a first embodiment of a sensor arrangement in a schematic block diagram,
• 2 a second embodiment of a sensor arrangement in a schematic block diagram,
• 3 a first measurement cycle of the second embodiment of the sensor arrangement in a schematic block diagram, and
• 4 a second measurement cycle of the second embodiment of the sensor arrangement in a schematic block diagram.

The 1 shows a first embodiment of a sensor arrangement 1 for the contactless measurement of normal and shear stresses in a component 2, which is a shaft in the examples shown.

The sensor assembly 1 has a first magnetic core 4 extending along a first longitudinal axis 3, a second magnetic core 6 extending along a second longitudinal axis 5, and a third magnetic core 8 extending along a third longitudinal axis 7, with the first longitudinal axis 3, the second longitudinal axis 5 and the third longitudinal axis 7 run parallel to one another.

The first magnet core 4 and the second magnet core 6 are spaced apart from one another by a linearly extending flux guide element 9 and form a U-shaped component. The third magnetic core 8 has a second flux-guiding element 10 that runs orthogonally to it and is configured in one piece with it, with the first flux-guiding element 9 and the second flux-guiding element 10 crossing in a common star point 12 without contact.

A first transmitting coil 13 is wound around the first magnetic core 4 , a first receiving coil 14 is wound around the second magnetic core 6 , and a second receiving coil 15 is wound around the third magnetic core 8 . The longitudinal axes 3,5,7 of the magnetic cores 4,6,8 are each offset by 90° to one another.

The sensor arrangement 1 has a control unit 21, which is connected to the first transmission coil 13 and is electrically connected to the receiver coils 14,15, which can be subjected to alternating current 1 indicated by the dotted connecting lines.

The control unit 21 is set up to carry out a first measurement cycle in that the first transmission coil 13 is charged with alternating current. Within this first measurement cycle, a voltage U _x0 in the unloaded state of component 2 at the first receiving coil 14, a voltage U _x in the loaded state of component 2 at the first receiving coil 14 and a voltage U _y in the loaded state of the component at the second receiving coil 15 determined.

und eine in dem Bauteil 2 vorliegende Schubspannung entsprechend der Funktion $$\tau =\frac{U_y}{\alpha \cdot U_x}$$

ermittelt und jeweils ein die ermittelte Normalspannung und die ermittelte Schubspannung repräsentierendes Ausgangssignal bereitstellt.With these variables, a normal voltage present in the component 2 is determined by the control unit 21 in accordance with the function $${\sigma }_x=\frac{2}{a}\cdot \left(\frac{u_x}{u_{xO}}-1\right)$$

and a shear stress present in the component 2 according to the function $$\tau =\frac{u_y}{a\cdot u_x}$$

determined and in each case provides an output signal representing the determined normal stress and the determined shear stress.

In the 2 a second embodiment of a sensor arrangement 1 is shown, which has a fourth magnetic core 41 along a fourth longitudinal axis 40, wherein the fourth magnetic core 41 is wound by a second transmission coil 42, which is electrically connected to the control unit 21, and is connected to the second flux-guiding element 10. The first longitudinal axis 3 and the fourth longitudinal axis 40 run parallel to one another. The flux-guiding element 10, the fourth magnetic core 41 and the third magnetic core 8 form a U-shaped component.

The control unit 21 of the second embodiment is set up to carry out a first measurement cycle in which the first transmitting coil 13 is supplied with alternating current and a voltage U _x0 in the unloaded state of the component 2 at the first receiving coil 14, a voltage U _xx in the loaded state of the component 2 at the first receiving coil 14 and a voltage U _xy in the loaded state of the component at the second receiving coil 15 can be determined. The energization and interconnection in the first measurement cycle is also in the 3 shown.

In addition, the control unit 21 is set up to carry out a second measurement cycle in that the second transmitting coil 42 is charged with alternating current and a voltage U _y0 in the unloaded state of the component 2 at the second receiving coil 15, a voltage U _yx in the loaded state State of the component 2 at the first receiver coil 14 and a voltage U _yy in the loaded state of the component at the second receiver coil 15 are determined. The interconnection and energization of the second measurement cycle is in the 4 shown.

eine in dem Bauteil 2 vorliegende zweite Normalspannung entsprechend der Funktion $${\sigma }_y=\frac{1}{\alpha }\cdot \left(2\cdot \frac{U_{yy}}{U_{yo}}+\frac{U_{xx}}{U_{xo}}-3\right),$$

und eine in dem Bauteil 2 vorliegende Schubspannung entsprechend der Funktion $$\tau =\frac{U_{xy}}{\alpha \cdot U_{xx}}=\frac{U_{yx}}{\alpha \cdot U_{yy}}$$

ermitteln und jeweils ein die ermittelte erste Normalspannung, die ermittelte zweite Normalspannung und die ermittelte Schubspannung repräsentierendes Ausgangssignal bereitstellen.After the two measurement cycles have been carried out, the control unit 21 can calculate a second normal voltage present in the component 2 in accordance with the function $${\sigma }_x=\frac{1}{a}\cdot \left(2\cdot \frac{u_{xx}}{u_{xO}}+\frac{u_{yy}}{u_{yO}}-3\right),$$

a second normal voltage present in the component 2 according to the function $${\sigma }_y=\frac{1}{a}\cdot \left(2\cdot \frac{u_{yy}}{u_{yO}}+\frac{u_{xx}}{u_{xO}}-3\right),$$

and a shear stress present in the component 2 according to the function $$\tau =\frac{u_{xy}}{a\cdot u_{xx}}=\frac{u_{yx}}{a\cdot u_{yy}}$$

determine and in each case provide an output signal representing the determined first normal stress, the determined second normal stress and the determined shear stress.

Like in the 2 is shown, the control unit 21 has a signal output 25, via which a signal representing the first normal stress and/or the second normal stress representing signal and/or the shear stress τ representing signal can be tapped.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a ranking.

Reference List

1

sensor arrangement

2

component

3

longitudinal axis

4

magnetic core

5

longitudinal axis

6

magnetic core

7

longitudinal axis

8th

magnetic core

9

flow guide

10

flow guide

12

star point

13

transmitter coil

14

receiving coil

15

receiving coil

21

control unit

25

signal output

40

longitudinal axis

41

magnetic core

42

transmitter coil

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102018221206 [0006]
• US4939937 [0007]
• DE 3940220 [0008]

Claims (6)

Sensor arrangement (1) for contactless measurement of normal and shear stresses in a component (2), comprising • a first along a first longitudinal axis (3) extending magnetic core (4), which is wrapped by a first transmitting coil (13), • a second magnetic core (6) extending along a second longitudinal axis (5), and • a third magnetic core (8) extending along a third longitudinal axis (7), around which a second receiver coil (15) is wound, • the first magnetic core ( 4) and the second magnetic core (6) are spaced apart from each other by a first flux-guiding element (9), • and in the magnetic flux path between the first magnetic core (4) and the second magnetic core (5), this flux path is wrapped by a first receiving coil (14). , and • the third magnet core (8) is connected to a second flux-guiding element (10), • wherein the first flux-guiding element (9) and the second flux-guiding element (10) are in a common neutral point (12) without contact kreuzen, wherein • the sensor arrangement (1) has a control unit (21) which is connected to the first transmission coil (13) so that it can be charged with alternating current and is electrically connected to the receiver coils (14, 15), characterized in that the control unit (21) is set up is to carry out a first measurement cycle in that the first transmission coil (13) is subjected to alternating current. Sensor arrangement (1) after claim 1 , characterized in that within the first measurement cycle a voltage U _x0 in the unloaded state of the component (2) at the first receiving coil (14), a voltage U _x in the loaded state of the component (2) at the first receiving coil (14) and a Voltage U _y are determined in the loaded state of the component at the second receiving coil (15), the control unit (21) in the component (2) present normal voltage according to the function $${\sigma }_x=\frac{2}{a}\cdot \left(\frac{u_x}{u_{xO}}-1\right)$$

and a shear stress present in the component (2) according to the function $$\tau =\frac{u_y}{a\cdot u_x}$$

determined and in each case provides an output signal representing the determined normal stress and the determined shear stress. Sensor arrangement (1) after claim 1 , characterized in that the sensor arrangement (1) has a fourth magnetic core (41) extending along a fourth longitudinal axis (40), the fourth magnetic core (41) being controlled by a second transmitting coil (42 ) is wrapped around and connected to the second flux-guiding element (10), the control unit (21) being set up to carry out a first measurement cycle in that the first transmission coil (13) is charged with alternating current and a voltage U _x0 in the unloaded state of the component (2). the first receiving coil (14), a voltage U _xx in the loaded state of the component (2) at the first receiving coil (14) and a voltage U _xy in the loaded state of the component at the second receiving coil (15), and a second measurement cycle carried out by the second transmitting coil (42) is acted upon by alternating current and a voltage U _y0 in the unloaded state of the component (2) at the second receiving coil (15), a span ung U _yx in the loaded state of the component (2) at the first receiving coil (14) and a voltage U _yy in the loaded state of the component at the second receiving coil (15), the control unit (21) having a built-in component (2 ) existing first normal stress according to the function $${\sigma }_x=\frac{1}{a}\cdot \left(2\cdot \frac{u_{xx}}{u_{xO}}+\frac{u_{yy}}{u_{yO}}-3\right)$$

a second normal voltage present in the component (2) according to the function $${\sigma }_y=\frac{1}{a}\cdot \left(2\cdot \frac{u_{yy}}{u_{yO}}+\frac{u_{xx}}{u_{xO}}-3\right)$$

and a shear stress present in the component (2) according to the function $$\tau =\frac{u_{xy}}{a\cdot u_{xx}}=\frac{u_{yx}}{a\cdot u_{yy}}$$

determined and in each case provides an output signal representing the determined first normal stress, the determined second normal stress and the determined shear stress. Sensor arrangement (1) according to one of the preceding claims, characterized in that the control unit (21) comprises a signal output (25) via which a signal representing the first normal stress and/or the second normal stress representing signal and/or the shear stress τ signal representing can be picked up. Sensor arrangement (1) according to one of the preceding claims, characterized in that the component (2) is a shaft. Sensor arrangement (1) according to one of the preceding claims, characterized in that the sensor arrangement (1) is accommodated in a housing.

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