Assembly for compensating for the temperature of a first component of a first part

Abstract

The invention relates to an assembly (1) for compensating for the temperature of a first component (2) of a first part (3), comprising: - the first part (3), which comprises the first component (2), said first component being designed to be mechanically vibratable and magnetoelectric, - an electronic unit (5), which is designed to excite the first component (2) using a first excitation signal so as to produce mechanical vibrations therein and receive the mechanical vibrations of the first component (2) and convert same into a first received signal, and - a compensation device (6), which is designed to compensate for the influence of a temperature on the first received signal.

Description

[0001] Arrangement for temperature compensation of a first component of a first component

[0002] The invention relates to an arrangement for temperature compensation of a first component of a first component.

[0003] Field devices for monitoring and / or determining at least one process variable, for example, a chemical or physical variable, of a medium are known in a wide variety of designs from the prior art. Within the scope of this application, in principle, all measuring devices or

[0004] Field devices are sensor arrangements that are used close to the process and that provide or process-relevant information, including remote I / Os, wireless adapters, and generally electronic components located at the field level. A large number of such field devices are manufactured and distributed by companies in the Endress + Hauser Group.

[0005] Many different field devices are based on the measurement of magnetic fields and the determination and / or identification of the respective process variable and / or parameter based on a variable related to the respective magnetic field. Different types of magnetic field sensors are generally used to detect the magnetic field. The accuracy of such field devices depends largely on the measurement accuracy of the magnetic field sensors. Field devices can also include actuators that exert forces under the influence of magnetic fields.

[0006] Magnetoelectric sensors are used to detect magnetic fields and can be based on the mechanical force coupling of magnetostrictive and piezoelectric materials. Magnetoelectric sensors based on multiferroics are also known. Magnetoelectric actuators, on the other hand, are used to exert a force under the influence of a magnetic field.

[0007] Magnetostrictive materials are characterized by the fact that a deformation of the material occurs as a result of an applied magnetic field. In this context, a distinction is made between Joule magnetostriction, which is understood to be a change in length due to a change in magnetization, the Villary effect, the inverse magnetostrictive effect, in which a change in the magnetic properties occurs as a result of mechanical stress, and the Delta-E effect, which describes a change in the modulus of elasticity due to a change in magnetization. Magnetostrictive materials are, for example, ferromagnetic transition metals such as iron, nickel, or cobalt, or their alloys, e.g., alloys of cobalt and iron, gallium and iron or galfenol, or terbium, dysprosium and iron orTerfenol, as well as various other compounds of transition metals with rare earths or various ferromagnetic glasses.

[0008] Piezoelectric materials are characterized by a change in electrical polarization and thus the occurrence of an electrical voltage as a result of elastic deformation. Examples of piezoelectric materials include lead zirconate titanate, polyvinylidene fluoride, or aluminum nitride.

[0009] In a magnetoelectric sensor, a magnetostrictive material is firmly coupled to a piezoelectric material. As a result of an applied magnetic field, the magnetostrictive material undergoes a change in length in the direction of the applied magnetic field and / or a change in its modulus of elasticity. This longitudinal expansion exerts a force on the piezoelectric material, which leads to a change in polarization and thus to the occurrence of a voltage that is electrically detectable. A change in the modulus of elasticity, in turn, leads to a change in the transmission behavior, which is also detectable. For example, it has become known in this context to use the piezoelectric material to excite mechanical vibrations in the magnetoelectric sensor.In this case, a change in the elastic modulus due to an applied magnetic field leads to a changed vibration behavior, which can be evaluated, for example, based on a frequency and / or amplitude of the mechanical vibrations.

[0010] Numerous different possible designs for the construction of a magnetoelectric sensor have been identified. In many cases, a multilayer structure is used, comprising at least one layer of magnetostrictive material, one layer of piezoelectric material, and, if necessary, an electrode for tapping the voltage. The layer structure often takes the form of a strip attached at one end. Applying a magnetic field causes the strip to bend, producing an electrical voltage signal as the received signal.

[0011] Under the influence of a periodic, time-varying magnetic field with a predefined frequency or another suitable excitation signal, magnetoelectric sensors perform forced oscillations. Resonant oscillations are particularly advantageous because, in this case, even comparatively small magnetic field changes cause comparatively large changes in the sensor behavior. Such a magnetoelectric sensor is described, for example, in DE 10 2021 109 408 A1. In addition to the magnetic field changes, temperature also influences the electrical voltage signal, since the physical properties of the magnetoelectric sensor are generally temperature-dependent. However, the effect of temperature on the electrical voltage signal is often undesirable, especially when the magnetoelectric sensor is used in process plants with sometimes widely varying temperatures.However, it is not possible to separate the influence of temperature from the influence of magnetic field changes using only the electrical voltage signal.

[0012] Based on this, the present invention is based on the object of providing an arrangement which enables compensation of the temperature effect in a simple manner.

[0013] According to the invention, the object is achieved by an arrangement for temperature compensation of a first component of a first component comprising the first component with the first component which is mechanically oscillatable and magnetoelectrically designed, an electronic unit which is designed to excite the first component to mechanical oscillations by means of a first excitation signal and to receive the mechanical oscillations of the first component and to convert them into a first received signal, a compensation device which is set up to compensate for an influence of a temperature on the first received signal.

[0014] The first component is designed to perform mechanical oscillations when excited by the first excitation signal and has magnetoelectric properties. In particular, the first component can be partially configured as a rod, strip, or bridge secured on one side.

[0015] The first excitation signal is preferably generated based on the first received signal, in particular a frequency of the first received signal. The first excitation signal can be generated such that the mode of the mechanical oscillations corresponds to a resonant frequency of the first component.

[0016] According to the invention, the arrangement comprises a compensation device which makes it possible to compensate for the influence of temperature on the first received signal. In particular, the compensation device is designed to compensate for the influence of temperature on the first received signal using a differential principle. In one embodiment, the first component comprises a first layer made of a piezoelectric material and a second layer made of a magnetostrictive material, or a multiferroic. The first component can be manufactured, for example, using conventional coating techniques with or without a predetermined substrate; for example, silicon technology processes can be used. In one embodiment, the first component is a MEMS element, i.e., a micro-electro-mechanical (MEMS) system.In particular, the first layer can be designed in sections in the form of a strip attached on one or both sides.

[0017] The arrangement preferably comprises a magnetic field unit configured to generate a first magnetic field at least in the region of the first component. The first magnetic field can serve as an offset magnetic field to determine changes in the first magnetic field by means of the first component.

[0018] In a further embodiment, the electronics unit is configured to use the first received signal to determine a change in the first magnetic field caused by the environment of the first component. The first magnetic field or the change in the first magnetic field is evaluated based on the first received signal, which is an electrical voltage signal. For example, the first component can be used as a magnetic field sensor, which serves to determine and / or monitor a process variable of a medium.

[0019] In a first embodiment, the compensation device is configured to influence the first component such that, within a defined period of time, a change in the first magnetic field does not cause a change in the first received signal. In the first embodiment, the first component is influenced such that, for a defined period of time, the first component acts as a duplicate of itself. During the defined period of time, the first component continues to be excited to mechanical oscillations using the first excitation signal, and a first received signal is received. By ensuring that the first component is not influenced by a change in the first magnetic field within the defined period of time, the influence of the temperature on the first received signal can be determined without the contribution of the change in the first magnetic field. The contribution of the first magnetic field to the first received signal is therefore constant.the contribution of the first magnetic field to the first received signal is known. Thus, the influence of the temperature on the first received signal can be compensated. Preferably, the compensation device is configured to repeatedly influence the first component such that, within a defined period of time, a change in the first magnetic field does not cause a change in the first received signal. In a further development of the first embodiment, the compensation device is configured to magnetically saturate the first component by means of the first magnetic field unit or a second magnetic field unit within a defined period of time. Due to the (temporary) magnetic saturation of the first component, a change in the first magnetic field does not cause a change in the first received signal within the defined period of time, so that the influence of the temperature on the first received signal can be determined without the influence of a change in the first magnetic field.

[0020] In an alternative development of the first embodiment, the compensation device is configured to generate a second magnetic field by means of a second magnetic field unit, which compensates for the first magnetic field within a defined period of time. By compensating for the first magnetic field within a defined period of time, the first received signal can be determined without the influence of the first magnetic field.

[0021] In a second embodiment, the arrangement has a second component which is designed as an identical duplicate of the first component, wherein the electronics unit is further designed to excite the second component to mechanical oscillations by means of a second excitation signal and to receive the mechanical oscillations of the second component and to convert them into a second received signal, wherein the second component is arranged such that a change in the first magnetic field does not cause a change in the second received signal, wherein the compensation device is set up to compensate for an influence of a temperature on the first received signal by means of the first component and the second component.

[0022] The second component is designed as an identical duplicate of the first component, thus having the same mechanically oscillating structure and the same magnetostrictive properties as the first component. However, the second component is arranged such that a change in the first magnetic field does not cause a change in the second received signal of the second component. The influence of a change in the first magnetic field on the first received signal is constant, while the influence of temperature on the first received signal varies depending on the temperature. In this way, the influence of temperature on the first received signal can be compensated for by the first component and the second component.

[0023] In a further development of the second embodiment, the second component is arranged at an angle to the first magnetic field such that the second received signal is substantially independent of the first magnetic field. Typically, the second received signal of the second component depends on the angle between the second component and the first magnetic field. Preferably, an angle between the second component and the first magnetic field is selected such that the contribution of the first magnetic field to the second received signal is negligible or zero.

[0024] In an alternative development of the second embodiment, the second component is arranged adjacent to a magnetic shield, which is designed and / or arranged such that the second component is completely shielded from the first magnetic field. The magnetic shield ensures that the second received signal has no or only a negligible contribution from the first magnetic field.

[0025] In a further alternative development of the second embodiment, the second component is arranged relative to the first magnetic field such that the second component is permanently magnetically saturated. Since the second component is permanently magnetically saturated, the second received signal has no or a constant contribution from the first magnetic field. The second received signal thus changes only due to the contribution of the temperature.

[0026] In a third embodiment, the arrangement comprises a third non-magnetic component which has substantially the same thermomechanical properties as the first component, wherein the electronics unit is further configured to excite the third component to mechanical oscillations by means of a third excitation signal and to receive the mechanical oscillations of the third component and to convert them into a third received signal, wherein the compensation device is configured to compensate for an influence of a temperature on the first received signal by means of the first component and the third component.

[0027] The third component is non-magnetic and has essentially the same thermomechanical properties as the first component. The term "essentially the same thermomechanical properties" in the context of this application means that the differences in the thermomechanical properties of the first component and the third component are negligible or small but known for compensating for the influence of temperature on the first received signal. Since the third component is non-magnetic, the third received signal does not include any contribution from the first magnetic field. Since the third component has essentially the same thermomechanical properties as the first component, the third received signal can be used to compensate for the influence of temperature on the first received signal.

[0028] The invention is explained in more detail below with reference to the following figures 1-5. They show:

[0029] Fig. 1a,b: two designs of the first component.

[0030] Fig. 2: a first embodiment of the arrangement according to the invention.

[0031] Fig. 3: a second embodiment of the arrangement according to the invention.

[0032] Fig. 4: a third embodiment of the arrangement according to the invention.

[0033] Fig. 5: a fifth embodiment of the arrangement according to the invention.

[0034] Fig. 1 a, b show two preferred embodiments for the first component 3. The first component 3 from Fig. 1 a has a first layer 12 made of a piezoelectric material and a second layer 13 made of a magnetostrictive material, which are arranged one above the other and mechanically coupled to one another. The first component 3 is constructed in the form of a layered structure, for example in the form of a MEMS component. In other embodiments, further layers or additionally a substrate can be present. The first layer 12 made of the piezoelectric material can be configured in sections as a strip. Instead of the first layer 12 and the second layer 13, the first component 2 can also have a multiferroic material which has magnetoelectric properties.

[0035] The first component 3 preferably has at least one electrode 4. At least one electrode 4 can be applied to the first layer 12 made of the piezoelectric material as a first electrode 4a made of an electrically conductive material, which serves to detect a received signal from the first component 2 in the form of an electrical voltage. The at least one electrode 4 preferably extends over a large part or substantially completely along a surface of the first component 2 or a piezoelectric layer 12 of the component 2. The first component 3 can be designed such that it has multiple electrodes. A second electrode can be provided either by the second layer 13 made of the magnetostrictive material, since magnetostrictive materials are typically electrically conductive. The electrical voltage between the first electrode 4a and the second layer 13 can then be tapped.However, it is also conceivable to provide a separate second electrode 4b, as shown in Fig. 1 a, and to tap the electrical voltage between the two electrodes 4a and 4b.

[0036] In the embodiment shown in Fig. 1a, the second electrode is designed as a return electrode, which is arranged in an end region of the first component 3 opposite the first electrode 4a. Alternatively, both electrodes 4a and 4b can be applied in different areas of the surface of the first layer 12 made of the piezoelectric material, as shown in Fig. 1b. The first electrode 4a is an excitation electrode, and the third electrode 4b is a receiving electrode. The two electrodes 4a and 4b are electrically insulated from each other.

[0037] Fig. 2 shows a first embodiment of the arrangement 1 according to the invention, which, in addition to the first component 3, has an electronics unit 5 and a compensation device 6. The electronics unit 5 is designed to excite the first component 2 to mechanical oscillations by means of a first excitation signal and to receive the mechanical oscillations of the first component 2 and convert them into a first received signal. In particular, the electronics unit 5 is electrically connected to the at least one electrode 4. The first received signal is dependent on a magnetic field applied to the component 2 and a temperature. For temperature compensation, the compensation device 6 is provided, which is configured to compensate for the influence of a temperature on the first received signal.

[0038] Optionally, the arrangement 1 can have a first magnetic field unit 7, which generates a first magnetic field B1 at least in the region of the first component 2. The magnetic field B1 can serve as an offset magnetic field, changes in which can be detected by means of the first received signal. A change in the first magnetic field B1 can be caused by the environment of the first component 3. For example, the first component 3 can be attached to a container containing a medium. Based on the first received signal, a process variable, in particular a fill level or limit level, of the medium can be determined and / or monitored.

[0039] To compensate for the influence of temperature on the first received signal, three alternative embodiments are proposed.

[0040] Thus, in the first embodiment, the compensation device 6 can be configured to influence the first component 2 such that, within a defined period of time, a change in the first magnetic field B1 does not cause a change in the first received signal, as shown in Fig. 2. For example, the compensation device 6 can be configured to magnetically saturate the first component 2 by means of the first magnetic field unit 7 or a second magnetic field unit 8 within a defined period of time. Alternatively, the compensation device 6 can be configured to generate a second magnetic field B2 by means of the second magnetic field unit 8, which compensates for the first magnetic field B1 within a defined period of time.

[0041] During the defined period in which the first component 2 is magnetically saturated or the first magnetic field B1 is compensated, the first component 2 is excited to mechanical vibrations by means of the electronic unit and the first excitation signal. The electronic unit can be configured to receive the mechanical vibrations of the first component 2 and convert them into a fourth or fifth received signal. The compensation device 6 can be configured to compensate for the influence of a temperature on the first received signal based on the first received signal and the fourth or fifth received signal.

[0042] In the second embodiment, the arrangement 1 has a second component 9, which is designed as an identical duplicate of the first component 2. In particular, the second component 9 is designed identically to the first component 2. The electronics unit is designed to excite the second component 9 to mechanical oscillations using a second excitation signal and to receive the mechanical oscillations of the second component 9 and convert them into a second received signal. Based on the first component 2 and the second component 9, in particular based on the first received signal and the second received signal, the compensation device 6 compensates for the influence of the temperature on the first received signal. The second component 9 is arranged such that a change in the first magnetic field B1 does not cause a change in the second received signal.

[0043] One possible arrangement of the second component 9 is shown in Fig. 3. The second component 9 is arranged adjacent to a magnetic shield 10, which is designed to shield the second component 9 from the first magnetic field B1. Further possible arrangements are shown in Fig. 4. For example, the second component 9 can be arranged at such an angle to the first magnetic field B1 that the second received signal is substantially independent of the first magnetic field B1, or can be arranged relative to the first magnetic field B1 such that the second component 9 is permanently magnetically saturated. The second component 9 can be arranged separately from the first component 3, as shown by way of example in Fig. 3, or it can be arranged together with the first component 2 on a common substrate 15 of the component 3, as illustrated in Fig. 4. A third embodiment is shown in Fig. 5.In this case, the arrangement 1 has a third component 11. The third component 11 is non-magnetic, i.e. its properties are not influenced by the first magnetic field. Furthermore, the third component 11 has substantially the same thermomechanical properties as the first component 2. The third component 11 can be comprised of the first component 3 together with the first component 2, or it can be arranged separately from the first component 3. By means of a third excitation signal, the third component 11 is excited to mechanical oscillations, wherein a third received signal is generated. The compensation device 6 is configured to compensate for an influence of a temperature on the first received signal by means of the first component 2 and the third component 11, in particular based on the first received signal and the third received signal.

[0044] List of reference symbols

[0045] 1 arrangement

[0046] 2 first component

[0047] 3 first component

[0048] 4 Electrode

[0049] 4a first electrode

[0050] 4b second electrode

[0051] 5 Electronic unit

[0052] 6 Compensation device

[0053] 7 first magnetic field unit

[0054] 8 second magnetic field unit

[0055] 9 second component

[0056] 10 magnetic shielding

[0057] 11 third component

[0058] 12 first layer

[0059] 13 second layer

[0060] 14 Substrat

[0061] 15 second component

[0062] B1 first magnetic field

[0063] B2 second magnetic field

Claims

Patent claims 1. Arrangement (1) for temperature compensation of a first component (2) of a first part (3), comprising the first part (3) with the first component (2), which is mechanically oscillatable and magnetoelectrically designed, an electronics unit (5) which is designed to excite the first component (2) to mechanical oscillations by means of a first excitation signal and to receive the mechanical oscillations of the first component (2) and to convert them into a first received signal, a compensation device (6) which is set up to compensate for an influence of a temperature on the first received signal.

2. Arrangement (1) according to claim 1, wherein the first component (2) comprises a first layer of a piezoelectric material and a second layer of a magnetostrictive material or a multiferroic.

3. Arrangement (1) according to one of claims 1-2, wherein the arrangement (1) has a first magnetic field unit (7) which is designed to generate a first magnetic field (B1) at least in the region of the first component (2).

4. Arrangement (1) according to one of claims 1-3, wherein the electronic unit (5) is designed to determine, on the basis of the first received signal, a change in the first magnetic field (B1) caused by an environment of the first component (3).

5. Arrangement (1) according to one of claims 1-4, wherein the compensation device (6) is configured to influence the first component (2) such that within a defined period of time, a change in the first magnetic field (B1) does not cause a change in the first received signal.

6. Arrangement (1) according to claim 5, wherein the compensation device (6) is configured to magnetically saturate the first component (2) by means of the first magnetic field unit (7) or a second magnetic field unit (8) within a defined period of time.

7. Arrangement (1) according to claim 5, wherein the compensation device (6) is configured to generate a second magnetic field (B2) by means of a second magnetic field unit (8), which second magnetic field (B1) compensates for the first magnetic field (B1) within a defined period of time.

8. Arrangement (1) according to one of claims 1-4, wherein the arrangement (1) has a second component (9) which is designed as an identical duplicate of the first component (2), wherein the electronics unit (5) is further designed to excite the second component (9) to mechanical oscillations by means of a second excitation signal and to receive the mechanical oscillations of the second component (9) and to convert them into a second received signal, wherein the second component (9) is arranged such that a change in the first magnetic field (B1) does not cause a change in the second received signal, wherein the compensation device (6) is set up to compensate for an influence of a temperature on the first received signal by means of the first component (2) and the second component (9).

9. Arrangement (1) according to claim 8, wherein the second component (9) is arranged at such an angle to the first magnetic field (B1) that the second received signal is substantially independent of the first magnetic field (B1).

10. Arrangement (1) according to claim 8, wherein the second component (9) is arranged adjacent to a magnetic shield (10) which is designed and / or arranged such that the second component (9) is completely shielded from the first magnetic field (B1).

11. Arrangement (1) according to claim 8, wherein the second component (9) is arranged relative to the first magnetic field (B1) such that the second component (9) is permanently magnetically saturated.

12. Arrangement (1) according to one of claims 1-4, wherein the arrangement (1) comprises a third non-magnetic component (11) which has substantially the same thermomechanical properties as the first component (2), wherein the electronic unit (5) is further configured to cause the third component (11) to mechanical oscillations by means of a third excitation signal to excite and receive the mechanical vibrations of the third component (11) and to convert them into a third received signal, wherein the compensation device (6) is designed to compensate for an influence of a temperature on the first received signal by means of the first component (2) and the third component (11).

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