Conversion element and vibration sensor

Abstract

The invention relates to a conversion element and a vibration sensor. The conversion element (2) is used for converting between mechanical vibration and an electric signal. There are various piezoelectric elements (3) in a stacked arrangement and a connector (4) as a wire. Grooves (6) between adjacent piezoelectric elements (3) are located at an outer side (5) of the stack. And the connector (4) is positioned in the groove (6) filled with a conductive filling material (7). The connector (4) is connected to the stack via a sintering process. The connector (4) comprises an inner section (8) located inside the groove (6) and an outer section (9) located outside the groove (6). The outer section (9) is located at an outer side (5) of the stack. The invention also encompasses a vibration sensor having a conversion element (2).

Description

Conversion elements and vibration sensors Technical Field

[0001] This invention relates to a conversion element. It also relates to a vibration sensor having a conversion element. The vibration sensor is used to determine or monitor at least one process variable, such as the level, density, or viscosity of a medium. The medium may be, for example, a fluid, liquid, gas, or bulk solid. Background Technology

[0002] Vibration sensors are widely used in process and / or automation technologies. The sensor includes at least one mechanical oscillating unit (also called a vibrating element), such as, for example, a single fork, a fork, or a thin film. During operation, the vibrating element is excited by means of an exciter / receiver unit (also called a driver or conversion element), causing it to perform mechanical oscillations. The exciter / receiver unit is typically an electromechanical transducer unit, which in most cases includes a piezoelectric element. This piezoelectric element is typically a stacked arrangement of disks.

[0003] US 6,710,517 B2 provides a design particularly suitable for conversion elements operating at higher temperatures. It describes a stack of piezoelectric elements in the form of multiple disks, each disk having a groove on its respective front side. Connectors for electrical connections to the stack are arranged within these grooves and, due to their location within the stack. The production of such a stack is quite cumbersome, as it must be built layer by layer. Summary of the Invention

[0004] The object of the present invention is to provide a conversion element with a piezoelectric element that can be used at higher temperatures and also solves the problem of electrical connection.

[0005] The object of the present invention is achieved by a conversion element for converting between mechanical vibration and electrical signals, wherein the conversion element comprises various piezoelectric elements arranged in a stacked manner, wherein the conversion element further comprises at least one connector, wherein the connector is a wire, wherein the stack of piezoelectric elements includes a groove between adjacent piezoelectric elements on its outer side, wherein the connector is partially located within the groove, wherein at least the groove in which the connector is located is filled with a conductive filler material, wherein the connector is connected to the stack of piezoelectric elements, wherein the connector includes an inner segment located within the groove and an outer segment located outside the groove, and wherein the outer segment is located on the outer side of the stack of piezoelectric elements.

[0006] The piezoelectric elements are electrically connected via at least one connector. The connector is disposed within a recess on the outer side, and thus at the edge of the piezoelectric element. The recess is deep enough that the connector reaches at least one electrode, which is typically located on the front side of the piezoelectric element. Within the stack, the electrodes of adjacent piezoelectric elements face each other and have the same polarity. In one embodiment, each recess reaches two piezoelectric elements, the recess being located between the two piezoelectric elements. In one embodiment, the front side of the piezoelectric elements is completely covered by their respective electrodes. Therefore, the recess between adjacent piezoelectric elements allows the portion of the connector located within the recess to reach the electrodes of the two adjacent piezoelectric elements.

[0007] The connector is partially located within the groove and partially outside the stack of piezoelectric elements. Therefore, the connector only needs to contact the groove on the outer side. This is advantageous for manufacturing. To secure the connector to the stack of piezoelectric elements, a sintering or bonding process is performed, for example. Alternatively, a high-temperature adhesive is used to connect the connector to the stack, for example, in a bonding process. Preferably, a brazing or soldering process is unnecessary. Therefore, the connector, as a conductor, remains flexible. This is necessary, for example, for further processing of the conversion element.

[0008] In embodiments of the conversion element, the piezoelectric elements in the stack of piezoelectric elements are substantially identical in size and / or material. In this embodiment, ceramic components are polarized and thus used as piezoelectric elements, and these ceramic components are identical in size and / or material. This embodiment is advantageous for the production of the conversion element.

[0009] Preferably, the piezoelectric element is in the form of a disc with a diameter between 5 mm and 10 mm.

[0010] In one embodiment, the grounding area of ​​the piezoelectric element is circular or square. In another embodiment, the disk of the piezoelectric element has a closed surface or has a hole.

[0011] According to one embodiment of the conversion element, the groove has the form of a straight cut having a given length and / or a given depth. The size of the groove depends at least on the diameter of the wire forming the connector. In one embodiment, the length of the groove is between 5% and 50% of the diameter of the piezoelectric element. In one embodiment, the depth and length of the groove are the same for all grooves or at least for the groove containing the connector. In another embodiment, the depth is correspondingly defined by the length.

[0012] In one embodiment, there is a recess with the connector and a recess without the connector. In another embodiment, the recess with the connector has at least one dimension (i.e., length or depth) smaller than the recess without the connector. Therefore, an empty recess is larger than a non-empty recess. This embodiment helps to avoid short circuits between the outer segment of the connector and the electrodes of the piezoelectric element.

[0013] In one embodiment, the grooves are parallel to each other.

[0014] In one embodiment of the conversion element, the various piezoelectric elements are connected to each other via a sintering process, wherein at least one sintered layer is located between adjacent piezoelectric elements.

[0015] According to one embodiment of the conversion element, the sintering composition includes silver.

[0016] In one embodiment of the conversion element, the filler material comprises silver.

[0017] According to one embodiment of the conversion element, the filler material comprises low-temperature sintered silver. The sintering process at a lower temperature prevents oxidation of the connector.

[0018] According to one embodiment of the conversion element, only the recess where the connector is located is filled with conductive filler material. In this embodiment, the other recesses remain empty and serve as isolators.

[0019] In one embodiment, the outer segment of the connector is primarily disposed above the recess without the connector. In one embodiment, the outer segment includes a return point from one direction to another, or in other words, the tip of the loop they form. Preferably, the return point or tip is located above such an empty recess. This illustrates the effect of the empty recess as a separator to prevent short circuits. Such short circuits can occur due to the fact that the connector is a bare wire.

[0020] In one embodiment, the recesses with connectors and the recesses without connectors (i.e., empty in terms of the connector) are arranged alternately.

[0021] In one embodiment of the conversion element, the piezoelectric element is polarized, wherein the piezoelectric element is arranged such that those sides of the piezoelectric element having the same polarization are in contact with each other.

[0022] In one embodiment of the conversion element, the piezoelectric element is polarized, wherein the piezoelectric element is arranged within a stack of piezoelectric elements such that they form two sub-stacks, wherein in each of the two sub-stacks, the piezoelectric element is arranged such that those sides of the piezoelectric element having the same polarization are in contact with each other, wherein at least one insulating ceramic is located between the front sides of the two sub-stacks aligned with each other, and wherein the front sides of the two sub-stacks aligned with each other have the same polarization.

[0023] In this embodiment, the conversion element includes a driver unit for inducing mechanical vibration and a separate receiver unit for receiving the mechanical vibration. In corresponding sub-stackings, the piezoelectric elements are mechanically and electrically connected to each other. Each piezoelectric element includes a side with a positive electrode and a side with a negative electrode. In one embodiment, each sub-stacking includes an even number of piezoelectric elements, resulting in both ends of the two sub-stackings having the same electrode, preferably a negative electrode. The two sub-stackings are arranged such that they face each other with the same electrode. Between the sub-stackings is an insulating ceramic that electrically isolates the two sub-stackings from each other.

[0024] In another embodiment, the recess with connector and the recess without connector alternate within the same sub-stack. In this embodiment, within each sub-stack, the recess with connector is followed by the recess without connector, then the recess with connector, and so on.

[0025] According to one embodiment of the conversion element, the outer side of the stack of piezoelectric elements includes a groove located between the front side of each of two aligned sub-stacks and the insulating ceramic. In another embodiment, two connectors are present, and their respective final inner segments are located within a corresponding groove between the front side of the sub-stack and the intermediate insulating ceramic.

[0026] In one embodiment of the switching element, the insulating ceramic is made of piezoelectric ceramic, wherein the piezoelectric ceramic is preferably the material of the piezoelectric elements in a stack of piezoelectric elements. In this embodiment, the switching element comprises a set of various disks made of the same material. Some are polarized and are piezoelectric elements. Another disk (or in another embodiment: multiple other disks) is not polarized and serves as the insulating ceramic for isolation.

[0027] According to one embodiment of the conversion element, at least one region on the outer side of the stack of piezoelectric elements includes at least a groove between the front sides of the two sub-stacks aligned with each other, and the insulating ceramic is covered by a barrier. In this embodiment, the barrier serves as an electrical isolator between the front sides of the two sub-stacks facing each other.

[0028] In one embodiment, the entire outer side of the stack of piezoelectric elements is covered by a barrier. In an alternative embodiment, the barrier is limited to a specific area.

[0029] In one embodiment of the switching element, the barrier comprises a glass layer.

[0030] According to one embodiment of the conversion element, the conversion element includes two connectors.

[0031] In one embodiment of the conversion element, each of the two connectors is associated with one of the two sub-stackings.

[0032] According to one embodiment of the conversion element, the stack of piezoelectric elements includes a groove located between each pair of adjacent piezoelectric elements on its outer side.

[0033] In one embodiment of the conversion element, the number of stacked recesses of the piezoelectric element is greater than the number of recesses where the connector is located. In this embodiment, not all recesses accommodate the connector. Some of the plurality of recesses remain empty, without a connector, and without filler material.

[0034] According to one embodiment of the switching element, the outer side of the stack of piezoelectric elements is covered by an electrical isolation protection member. The electrical isolation protection member serves as an electrical isolator between different components of the switching element and as a strain relief member for the outer segment of the connector or the plurality of connectors.

[0035] In one embodiment of the switching element, the electrical isolation element is a resin, preferably epoxy resin. In an alternative embodiment, the electrical isolation element is glass, a high-temperature varnish or coating, or a polytetrafluoroethylene (PTFE) layer.

[0036] According to one embodiment of the conversion element, at least one isolation line is located on top of at least a portion of the outer segment of the connector, such that the isolation line acts as a strain relief element for the connector. This embodiment contacts forces that may act on the outer segments of the connector or the plurality of connectors.

[0037] In one embodiment of the conversion element, the at least one isolation line extends substantially along the longitudinal axis of the stack of piezoelectric elements.

[0038] According to one embodiment of the conversion element, two isolation lines are located on top of at least a portion of the outer segment of the connector, wherein the two isolation lines extend substantially parallel to each other.

[0039] In one embodiment of the conversion element, the two isolation lines and the barrier form a capital letter H. This particular form is associated with embodiments having two sub-stacks, wherein the two sub-stacks are specifically separated by insulating ceramic.

[0040] According to one embodiment of the conversion element, the isolation line includes a glass layer.

[0041] In one embodiment of the conversion element, at least one insulating ceramic is located on the front side of the stack of the piezoelectric elements.

[0042] According to one embodiment of the conversion element, at least one insulating ceramic is located on each of the two front sides of the stack of piezoelectric elements. In another embodiment, both front sides of the stack of piezoelectric elements have subsequent insulating ceramics.

[0043] According to another embodiment of the conversion element, the conversion element includes a first side and a second side, wherein the conversion element includes at least two connectors, wherein the first side and the second side include grooves, and wherein one of the at least two connectors is partially located within the groove on the first side, and the other of the at least two connectors is partially located within the groove on the second side. In this embodiment, there are two connectors located within grooves on different sides of the conversion element. The term "side" here refers to, for example, the front and back sides of a stack of piezoelectric elements. This is particularly distinct from the front side of the stack. In this context, these front sides of the stack can also be referred to as the top and bottom sides of the stack. The connectors are, for example, part of a vibration sensor connected to the positive and negative terminals of a voltage source, respectively.

[0044] The objective is further achieved by a vibration sensor for determining and / or monitoring at least one process variable, the vibration sensor having at least one vibration element and a conversion element for converting between mechanical vibration and electrical signals, wherein the conversion element is implemented according to one embodiment of the preceding and following embodiments. Embodiments of the conversion element are also applicable to the vibration sensor. Therefore, the advantages of the embodiments and their corresponding discussions are also valid for the sensor and will not be repeated here.

[0045] According to one embodiment of the vibration sensor, the vibration element is bifurcated.

[0046] According to one embodiment of the vibration sensor, the vibration sensor further includes an electronic unit configured to receive and submit electrical signals to the conversion element, wherein the conversion element is configured such that the piezoelectric elements form two sub-stacks, wherein the conversion element includes a first side and a second side, wherein the conversion element includes four connectors, wherein two connectors are associated with each sub-stack and located on different sides of the conversion element, and wherein the electronic unit receives electrical signals from the conversion element and submits signals to the conversion element via the four connectors, such that connectors located on the same side of the conversion element transmit electrical signals of different polarities. In this embodiment, the conversion element comprises two sub-stacks made of piezoelectric elements. One sub-stack serves as a transmitter of the mechanical vibration, and the other sub-stack serves as a receiver of the mechanical vibration. Both sub-stacks have two connectors for the positive and negative terminals of the electrical signals. The conversion element, and therefore the two sub-stacks, have a first side and a second side, which may be referred to, for example, as a front side and a back side. In this embodiment, the connectors located on the same side transmit signals of different polarities. Therefore, on the first side are the positive electrode of the first sub-stack and the negative electrode of the second sub-stack. The situation is correspondingly the same on the second side. This relates to the front sides of two adjacent sub-stacks within the stack of piezoelectric elements. Because the connectors are associated with different poles that change during the operation of the vibration sensor (all signals are alternating current), the risk of component migration (e.g., silver atoms) of the sintered composition occurring between the piezoelectric elements is low. Such migration is possible if both connectors are connected to the same pole but at different values. Attached Figure Description

[0047] The invention will be discussed with reference to the following figures. The figures show:

[0048] Figure 1: A cross-sectional view of a schematic diagram passing through a vibration sensor.

[0049] Figure 2: A view of a first embodiment of the switching element.

[0050] Figure 3: A view of a second embodiment of the switching element.

[0051] Figure 4: A view of a third embodiment of the conversion element, and

[0052] Figure 5: Top view of conversion element 2. Detailed Implementation

[0053] Figure 1 illustrates an exemplary embodiment of the vibration sensor.

[0054] The vibrating element 1 is provided by a so-called bifurcation, which includes two forked teeth connected to a diaphragm. The diaphragm is one side of the housing. The conversion element 2 is located within the housing, between the screw and the diaphragm. In the illustrated embodiment, a hemispherical element is arranged between the inner side of the conversion element 2 and the diaphragm to improve force transmission between the diaphragm and the conversion element 2.

[0055] The conversion element 2 includes various piezoelectric elements 3, which will be discussed in conjunction with Figures 2 and 3.

[0056] Conversion element 2 is connected to an electronic unit (compare Figure 3), which generates excitation signals and submits them to conversion element 2, and receives and evaluates the received signals generated by conversion element 2. Based on the electrical excitation signal, the conversion element causes the vibrating element 1 to perform mechanical vibration. When the vibrating element 1 interacts with a medium (not shown here), the vibration depends on the contact with the medium or on the properties of the medium, such as viscosity. Therefore, a process variable can be derived from the mechanical vibration performed by the vibrating element, or its change can be monitored. For this purpose, conversion element 2 receives the mechanical vibration of the vibrating element 1 and converts it into an electrical received signal, which is transmitted to the electronic unit. Based on the amplitude, frequency, or phase of the received signal, the value of the process variable can be evaluated.

[0057] Figures 2 and 3 below illustrate two embodiments of the conversion element 2, which can be used at high temperatures, up to 230°C, and which consist of a stack of piezoelectric elements 3. The temperature range in which the conversion element 2 can be used depends on the materials used and can be even higher.

[0058] The embodiments of Figures 2 and 3 include two sub-stacks 11 and 12 of the piezoelectric element 3.

[0059] In the embodiment of Figure 4, there is only a single stack. Therefore, the details regarding the individual sub-stacks 11, 12 can also be applied to a single stack, i.e., a sub-stack without another sub-stack.

[0060] Figure 2 illustrates an embodiment with six piezoelectric elements 3 and three insulating ceramics 18, all in the form of disks. The piezoelectric elements 3 are polarized such that one front side is the positive electrode and the other front side is the negative electrode. For electrical contact, the piezoelectric elements 3 are covered with metal electrodes (not shown here as being within a stack) on their front sides.

[0061] The piezoelectric elements 3 are arranged in a stacked manner to increase their mechanical strength and simultaneously increase their mechanical sensitivity. For this purpose, they are arranged such that their front sides with the same polarity sign are in contact.

[0062] Here, the stack is divided into two sub-stacks 11 and 12, with one sub-stack 11 serving as a receiving unit with two piezoelectric elements 3 and the other sub-stack 12 serving as a driving unit with four piezoelectric elements 3. The front sides of the two sub-stacks 11 and 12, which are aligned with each other, have the same polarity.

[0063] With the top piezoelectric element shown having a negative polarity (-), the polarity sequence in the illustrated embodiment is: "-, +, -, isolation, -, +, -, +, -, -". The first three polarities "-, +, -" belong to receiver sub-stack 11, while the other five polarities "-, +, -, +, -" belong to drive sub-stack 12. The "isolator" is located between the two sub-stacks 11 and 12.

[0064] The insulating ceramic 18 is located on the outer front side of the stack of piezoelectric elements 3 and between the front sides of two sub-stacks 11, 12 that are aligned with each other. This intermediate insulating ceramic 18 electrically separates the sub-stacks 11, 12 from each other. In addition, the insulating ceramic 18 at least reduces the mechanical connection between the two sub-stacks 11, 12.

[0065] The piezoelectric element 3 and the insulating ceramic 18 are connected to each other by a sintering process. For this step, a sintered component 10 is present between each disc of the piezoelectric ceramic (i.e., the polarized piezoelectric element 3 and the unpolarized insulating ceramic 18).

[0066] On the outer side 5 of the stack of piezoelectric elements 3, there is a groove 6 located between each piezoelectric element 3, so that the groove 6 reaches two adjacent piezoelectric elements 3 and is also part of the space between them. Therefore, in the illustrated embodiment, the groove 6 also contacts the electrodes of the two piezoelectric elements 3.

[0067] In the illustrated embodiment, grooves 6 are located between all the disks forming the stack. This means that grooves are also present between the piezoelectric elements 3 and the insulating ceramics 18 at the top, middle, and bottom of the stack. Some, but not all, grooves are filled with a filler material 7, which in this embodiment comprises silver suitable for sintering processes at lower temperatures. Lower temperatures, as stated herein, refer to temperatures below 600°C, preferably about 550°C.

[0068] For electrical contact, there are two connectors 4 in the form of wires. Each connector 4 is used for electrical connection of a sub-stack 11, 12. The connector 4 has a portion or segment (referred to as the inner segment) 8 located within a recess 6 and a portion or segment (referred to as the outer segment) 9 located outside the recess 6 and between the inner segments 8. The outer segment 9 is located at the outer side 5 of the stack, and the inner segment 8 is located at the edge of the stack. The inner segment 9 is fixed to the recess 6 via a sintering process, for which a filler material 7 is required. The filler material 7 is conductive. In the illustrated embodiment, the filler material 7 is only located within the recess 6 that receives the connector 4. The outer segment 9 forms a loop. The tip or return point of the corresponding loop is located above the empty recess 6, which reduces the risk of the connector 4 short-circuiting with the piezoelectric element 3 as a bare wire. For this purpose, the empty recess is larger than the recess that receives the inner segment 8 of the connector 4.

[0069] The conversion element 2 is covered by an electrical isolation protection element 13, which is, for example, a resin used as an electrical isolator, and it also secures the connector 4, especially the outer segment 9 of the connector 4.

[0070] In the embodiment shown in Figure 3, there is also a stack of piezoelectric elements 3.

[0071] In summary, there are nine disks made of piezoelectric ceramic. In this embodiment, the disks have the same dimensions, i.e., the same diameter and the same height. Six of the disks are polarized and serve as piezoelectric elements 3 for switching between electrical signals and mechanical vibrations, and vice versa. The other three disks are not polarized and serve as insulating ceramics 18 on the two front sides of the stack of piezoelectric elements 3 and between the two sub-stacks 11, 12 of piezoelectric elements 3. In different embodiments, the insulating ceramics 18 have a greater height than the piezoelectric elements 3 (e.g., up to 50% greater).

[0072] A sub-stack 11 with four piezoelectric elements 3 is a driver (or transmitter), and the other two piezoelectric elements 3 of another sub-stack 12 are receivers. The piezoelectric elements 3 in the sub-stacks 11 and 12 are arranged such that directly adjacent piezoelectric elements 3 have the same polarity. The front sides of the sub-stacks 11 and 12, which face each other and are separated by an intermediate insulating ceramic 18, also have the same polarity.

[0073] All piezoelectric disks 3, 18 are fixed by a sintering process. For this purpose, a sintered composition 10 is located between each pair of adjacent disks. In this embodiment, the sintered composition includes silver. The layer 10 also attaches electrodes (not shown here) to the surface of the piezoelectric element 3. Thus, due to the layer 10, the piezoelectric elements 3, 18 are mechanically and electrically connected to each other.

[0074] For electrical connection, each sub-stack 11, 12 is provided with its own connector 4 in the form of a wire. For electrical connection and mechanical fixation of the connector 4, the outer surface 5 of the stack of piezoelectric elements 3 has eight grooves 6 located between each pair of adjacent piezoelectric disks 3, 18. The grooves 6 are in the form of straight grooves with a given length and depth. The grooves 6 extend downwards from the outer side 5 to the secant line of the disks 3, 18. These grooves are parallel to each other because they are located at the edges of the piezoelectric disks. In this embodiment, the groove 6 accommodating the connector 4 is shorter and has a smaller depth than the other grooves 6 without the connector 4. The length of the groove 6 is approximately one-third of the diameter of the piezoelectric disks 3, 18.

[0075] The connectors 4 are arranged in a zigzag manner relative to the grooves 6 of the corresponding sub-stacks 11, 12. Each connector 4 has an alternating sequence of segments 8, 9 located inside and outside the grooves 6. The outer segments 9 form loops between the inner segments 8. A filler material 7 comprising silver is inserted into the grooves 6 within the inner segments 8 of the connector 4. The filler material 7 comprises silver suitable for a low-temperature sintering process used to fix the inner segments 8 to the corresponding piezoelectric disks 3, 18.

[0076] On the outer 5 of the stack of piezoelectric elements 3, three distinct components form the capital letter H: two insulating lines 16 are located on one side of the letter H, which rests on top of the outer segment 9 of the connector 4 and serves as a strain relief element. The insulating lines 16 are non-conductive. The horizontal portion of the letter H is provided by a barrier 15 that covers the region 14 of the outer 5 between two recesses 6 located between the insulating ceramic 18 in the middle between the two sub-stacks 11 and 12 and the corresponding piezoelectric elements at the ends of the sub-stacks 11 and 12.

[0077] The polarization of the piezoelectric element 3 extends along the longitudinal axis 17 of the stack of piezoelectric elements 3. Two isolation lines 16 extend parallel to each other and parallel to the longitudinal axis 17. The barrier 15 extends perpendicular to the longitudinal axis 17.

[0078] The conversion element 2 of the embodiment shown in Figure 4 comprises only a single stack of piezoelectric elements 3, each having an insulating ceramic disk 18 at both ends. In this embodiment, the connector 4 is not shown to highlight the different dimensions of the recess 6 on the outer side 5 of the stack.

[0079] Smaller and larger recesses 6 are arranged alternately. The smaller recess 6 is used to accommodate the inner segment of the connector. The larger recess 6 is used to prevent short circuits between the outer segment of the connector and those sides of the piezoelectric element 3 that the connector should not contact. The smaller recess 6 for the inner segment of the connector is filled with a conductive filler material.

[0080] Outside the smaller recess 6 and thus covering the larger portion of the outer segment of the connector, there are two parallel isolation lines 16.

[0081] Figure 5 shows a top view of the conversion element 2.

[0082] As can be seen, the stack of piezoelectric elements 3 has a circular base region. (Possibly, but not shown, a piezoelectric element with a rectangular or square base region.) The conversion element 2 includes a first side 21 and a second side 22, and includes two sub-stacks 11, 12 (compare Figure 1) that serve as a transmitter and receiver for vibration elements. Each sub-stack 11, 12 is connected to the electronic unit 23 via two connectors 4 located on different sides 21, 22 of the stack.

[0083] In the illustrated embodiment, at each side 21, 22, the inner wire belongs to one sub-stack connector 4, and the outer wire belongs to another sub-stack connector 4. The positive and negative signs refer to the positive and negative terminals of the electrical signal.

[0084] Clearly, the two connectors 4 belonging to the same sub-stack are connected to different poles, and the two connectors 4 belonging to the same side 21 and 22 are also connected to different poles.

[0085] In different embodiments not shown here, the poles of the connector 4 on the same sides 21, 22 of the conversion element 2 are the same.

[0086] List of reference features

[0087] 1 Vibration element

[0088] 2 conversion elements

[0089] 3 piezoelectric elements

[0090] 4 connectors

[0091] 5. The outer side of the piezoelectric element stack

[0092] 6 grooves

[0093] 7. Filling material

[0094] 8 connector internal section

[0095] 9. External segment of connector

[0096] 10 Sintering Layered

[0097] 11 Sub-stacks of piezoelectric element stacks

[0098] Sub-stacks of 12 piezoelectric elements

[0099] 13 Electrical isolation protection components

[0100] 14. The outer region of the stack of piezoelectric elements

[0101] 15 barriers

[0102] 16 isolation lines

[0103] 17. Longitudinal axis of the stack of piezoelectric elements

[0104] 18 Insulating Ceramic

[0105] 21 The first side of the conversion element

[0106] 22 The second side of the conversion element

[0107] 23 electronic units.

Claims

1. A conversion element (2) for converting between mechanical vibration and electrical signals, wherein, The conversion element (2) includes various piezoelectric elements (3) arranged in a stacked manner, wherein the conversion element (2) further includes at least one connector (4), wherein the connector (4) is a wire, wherein the stack of piezoelectric elements (3) includes a groove (6) between adjacent piezoelectric elements (3) at its outer side (5), wherein the connector (4) is partially located in the groove (6), wherein at least the groove (6) where the connector (4) is located is filled with a conductive filler material (7), wherein the connector (4) is connected to the stack of piezoelectric elements (3), wherein the connector (4) includes an inner segment (8) located in the groove (6) and an outer segment (9) located outside the groove (6), and wherein the outer segment (9) is located at the outer side (5) of the stack of piezoelectric elements (3).

2. The conversion element (2) according to claim 1, wherein, The piezoelectric elements (3) in the stack of the piezoelectric elements (3) are substantially the same in size and / or material.

3. The conversion element (2) according to claim 1 or 2, wherein, The groove (6) has a straight cut with a given length and / or a given depth.

4. The conversion element (2) according to any one of claims 1-3, wherein, The various piezoelectric elements (3) are connected to each other via a sintering process, wherein at least one sintered component (10) is located between adjacent piezoelectric elements (3), and the at least one sintered component preferably includes silver.

5. The conversion element (2) according to any one of claims 1-4, wherein, The filler material (7) includes low-temperature sintered silver.

6. The conversion element (2) according to any one of claims 1-5, wherein, The piezoelectric element (3) is polarized, wherein the piezoelectric element (3) is arranged in a stack of the piezoelectric elements (3) such that they form two sub-stacks (11, 12), wherein in each of the two sub-stacks (11, 12), the piezoelectric element (3) is arranged such that those sides of the piezoelectric element (3) having the same polarization are in contact with each other, wherein at least one insulating ceramic (18) is located between the front sides of the two sub-stacks (11, 12) aligned with each other, and wherein the front sides of the two sub-stacks (11, 12) aligned with each other have the same polarization.

7. The conversion element (2) according to claim 6, wherein, The insulating ceramic (18) is made of piezoelectric ceramic, and wherein the piezoelectric ceramic is preferably the material of the piezoelectric element (3) in the stack of the piezoelectric element (3).

8. The conversion element (2) according to claim 6 or 7, wherein, At least one region (14) of the outer side (5) of the stack of the piezoelectric element (3) includes at least the groove (6) located between the front sides of the two sub-stacks (11, 12) aligned with each other, and the insulating ceramic (18) is covered by a barrier (15), preferably the barrier (15) comprising a glass layer.

9. The conversion element (2) according to any one of claims 6-8, wherein, The conversion element (2) includes two connectors (4), wherein each of the two connectors (4) is associated with one of the two sub-stacks (11, 12).

10. The conversion element (2) according to any one of claims 1-9, wherein, The stack of the piezoelectric elements (3) includes a groove (6) located between each pair of adjacent piezoelectric elements (3) on its outer side (5).

11. The conversion element (2) according to any one of claims 1-10, wherein, The number of grooves (6) in the stack (3) of the piezoelectric elements is greater than the number of grooves (6) in which the connector (4) is located.

12. The conversion element (2) according to any one of claims 1-11, wherein, The outer side (5) of the stack of the piezoelectric elements (3) is covered by an electrical isolation protection element (13) preferably made of resin.

13. The conversion element (2) according to any one of claims 1-12, wherein, At least one isolation line (16) is located on top of at least a portion of the outer segment (9) of the connector (4), such that the isolation line (16) acts as a strain relief element of the connector (4).

14. The conversion element (2) according to claim 13, wherein, The at least one isolation line (16) preferably comprises a glass layer, and the at least one isolation line (16) extends substantially along the longitudinal axis (17) of the stack of the piezoelectric elements (3).

15. The conversion element (2) according to claim 13 or 14, wherein, Two isolation lines (16) are located on top of at least a portion of the outer segment (9) of the connector (4), and wherein the two isolation lines (16) extend substantially parallel to each other.

16. The conversion element (2) according to claim 14 or 15 and claim 8, wherein, The two isolation lines (16) and the barrier (15) form a capital letter H.

17. The conversion element (2) according to any one of claims 1-16, wherein, At least one insulating ceramic (18) is located on each of the two front sides of the stack of the piezoelectric element (3).

18. The conversion element (2) according to any one of claims 1-17, wherein, The conversion element (2) includes a first side (21) and a second side (22), wherein the conversion element (2) includes at least two connectors (4), wherein the first side (21) and the second side (22) include a groove (6), and wherein one of the at least two connectors (4) is partially located in the groove (6) of the first side, and the other of the at least two connectors (4) is partially located in the groove (6) of the second side (22).

19. A vibration sensor for determining and / or monitoring at least one process variable, the vibration sensor having at least one vibration element (1) and a conversion element (2) for converting between mechanical vibration and electrical signals, wherein, The conversion element (2) is implemented according to any one of claims 1 to 18.

20. The vibration sensor according to claim 19, wherein, The vibration sensor further includes an electronic unit (23) configured to receive and submit electrical signals to the conversion element (2), wherein the conversion element (2) is configured such that the piezoelectric element (3) forms two sub-stacks (11, 12), wherein the conversion element (2) includes a first side (21) and a second side (22), wherein the conversion element (2) includes four connectors (4), wherein two connectors (4) are associated with each sub-stack (11, 12) and located on different sides (21, 22) of the conversion element (2), and wherein the electronic unit (23) receives the electrical signals from the conversion element (2) and submits signals to the conversion element (2) via the four connectors (4), such that the connectors (4) located on the same side (21, 22) of the conversion element (2) transmit electrical signals of different polarities.

Images