Vibration sensor
By integrating the transducer device and temperature sensor into a single unit, the vibration sensor achieves accurate and durable temperature measurement, addressing the challenge of high-temperature environments.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ENDRESS & HAUSER GMBH & CO KG
- Filing Date
- 2025-10-02
- Publication Date
- 2026-05-15
AI Technical Summary
Existing vibration sensors face challenges in accurately measuring temperature, especially at high temperatures, which can damage transducer devices and affect the reliability of medium property measurements.
Integration of the transducer device and temperature sensor into a single cohesive unit, with the temperature sensor positioned in close proximity to the mechanically vibrating unit, allowing for optimal temperature measurement and enhanced durability.
Enables reliable temperature measurement at high temperatures, improving the accuracy and longevity of vibration sensor operations.
Smart Images
Figure EP2025078345_15052026_PF_FP_ABST
Abstract
Description
[0001] Vibration sensor
[0002] The invention relates to a vibration sensor having the features of the preamble of the first claim.
[0003] Vibration sensors are known in the art, for example, in the form of tuning forks or single rods. Such sensors have a mechanically vibrating unit that is excited to mechanical vibrations by a drive-receiver unit. The vibrations resulting from the interaction with a medium to be measured or monitored are received by the drive-receiver unit and processed. For measurement purposes, it is used, for example, that the vibration frequency or amplitude changes when the mechanically vibrating unit transitions from an uncovered to a state covered by the medium. This allows, for example, the monitoring of the fill level of the medium in a container.
[0004] The drive-receiver unit typically contains a transducer device that converts between electrical signals and mechanical vibrations. Piezoelectric elements are often used for this purpose; these elements have a polarized ceramic surface and at least one electrode on one end face for electrical contact. To increase the generated mechanical force, it is known to arrange several piezoelectric elements in a stack.
[0005] The properties of the medium in which the mechanically vibrating unit is embedded, and whose properties the vibration sensor is intended to monitor and determine, can be temperature-dependent. Therefore, determining the temperature of the medium is crucial for accurate parameter measurement. Furthermore, it should be noted that the transducer device typically contains multiple piezoelectric elements, which can be damaged by high temperatures, particularly above the Curie temperature. Therefore, it is known to use temperature sensors for determining and monitoring the temperature; see, for example, DE 102022 133 730 A1, the subsequently published DE 102023 118 851 A1, or the
[0006] DE 102009 029 490 A1 . The temperature sensor is part of the vibration sensor.
[0007] One problem is to accurately measure the temperature acting on the mechanically oscillating unit.
[0008] The object underlying the invention is therefore to propose a vibration sensor with a temperature sensor that allows for the most optimal and reliable temperature measurement possible over the period of application.
[0009] The problem is solved by combining the transducer device and the temperature sensor into a single component. The invention thus consists of integrating the transducer device and the temperature sensor into a cohesive unit. This also simplifies manufacturing. Furthermore, the transducer device is positioned in close proximity to the mechanically vibrating unit within the vibration sensor, which correspondingly influences the positioning of the temperature sensor. The transducer device and the temperature sensor therefore complement each other to form the complete component, or are at least partially complementary to one another, preferably with regard to their geometry. A temperature sensor is required, for example, when measurements are to be taken at high temperatures (e.g., between 150 °C and 230 °C).Temperature measurements are particularly helpful when the density of a medium needs to be measured or monitored at high temperatures.
[0010] One embodiment consists in the transducer device having a continuous recess, the temperature sensor being essentially mushroom-shaped, comprising an elongated base body and a support component arranged at its end face and designed as a partial sphere, the base body being at least partially arranged within the recess, and the support component being arranged outside the recess. In this embodiment, the transducer device has a continuous recess or hole in which the elongated base body of the temperature sensor, corresponding to the continuous recess, is located. The temperature sensor projects beyond the transducer device by means of a support component, which thus forms an end face of the temperature sensor and connects accordingly to the elongated base body.The mounting component thus also forms an end face of the combined component consisting of the transducer device and the temperature sensor. Depending on the design, the mounting component can be rounded or, for example, terminate in a flat surface. Essentially, the mounting component is characterized by its shape resembling a partial sphere. If the transducer device is positioned relative to the mechanically vibrating unit to transmit or receive the mechanical vibrations, the temperature sensor is also located near the vibrating unit to detect the temperature acting upon it.
[0011] One embodiment provides that the transducer device and the temperature sensor are designed and coordinated such that the maximum radial extent of the support component is essentially equal to the maximum radial extent of the transducer device. Thus, if the support component projects axially beyond the transducer device, it also spans radially across an end face of the transducer device in this embodiment. Therefore, in this embodiment, the support component forms the entire end face of the transducer device.
[0012] One embodiment includes the transducer device having at least one lateral recess, the temperature sensor having at least one elongated base body and a support component arranged at its end face, the base body being at least partially arranged in the recess, and the support component forming an end face of the overall component consisting of the transducer device and the temperature sensor. In one of the aforementioned embodiments, the temperature sensor's base body extends through the transducer device. In this embodiment, the temperature sensor flanks the transducer device laterally and, together with its support component, forms an end face of the overall component. Mechanical cohesion is achieved by the elongated base body being located in the lateral recess of the transducer device.
[0013] In a supplementary embodiment, the temperature sensor has a second elongated base body. In one embodiment, this second base body contains an additional sensor. In another embodiment, the two base bodies are positioned diametrically opposite each other on the mounting component. In one variant, the transducer device is thus enclosed on two sides.
[0014] In one design, the base body is essentially designed as a rod or column. In one variant, the base body and the support component are either a single piece or, alternatively, multi-piece.
[0015] One embodiment includes a temperature sensor comprising at least one elongated base body and a mounting component arranged at its end face, where the base body at least partially encloses the transducer device, and the mounting component forms an end face of the overall component consisting of the transducer device and the temperature sensor. In this embodiment, the base body at least partially encloses the transducer device. The base body is therefore partially sleeve-like. Depending on the specific embodiment, the transducer device arranged within the base body is partially or completely enclosed laterally.
[0016] One embodiment of the transducer device consists of several piezoelectric rings arranged in a stack, each ring having an electrode on its end face that extends to the opposite end face. In this embodiment, the transducer device has piezoelectric rings with double contact. The piezoelectric elements have two end faces, with the polarization oriented from one end face to the other. Each end face has an electrode—preferably metallic—for electrical contact, i.e., for applying and / or receiving electrical signals. The electrodes extend to the opposite end face, for example, via the side surface. Therefore, both electrodes are present on each of the two end faces.The advantage of this re-contacting method is that a contact electrode, i.e., a so-called solder lug, can be omitted. This is particularly advantageous for applications at high temperatures – for example, between 150 °C and 230 °C.
[0017] Depending on the design, the piezo ring or piezo rings can have a circular, square or rectangular outer contour.
[0018] One embodiment provides that the transducer device has two contact lines, and that one of the two contact lines is routed within the recess and the other outside the stack of piezoelectric rings. In this embodiment, two contact lines are sufficient to supply the transducer device with electrical signals and / or to tap them. Therefore, the individual piezoelectric rings are preferably in contact with each other. To minimize the risk of a short circuit and to ensure the safest possible manufacturing process, the two contact lines are positioned as far apart as possible. Thus, one line is routed within the recess and the other line is routed outside the recess.
[0019] One embodiment of the temperature sensor comprises a sensor element and a ceramic body, with the sensor element located inside the ceramic body. The sensor element is, for example, an electrical resistance element whose electrical resistance allows the temperature to be determined. The sensor element is arranged within a ceramic body. The ceramic body preferably has the shape of the elongated base body and the mounting component. In one embodiment, the material of the ceramic body is essentially the same as that of the piezoelectric elements.
[0020] One embodiment provides that the vibration sensor has a diaphragm, that the mechanically vibrating unit is arranged on the diaphragm, and that the mounting component of the temperature sensor rests on the diaphragm. In this embodiment, the temperature sensor is located in optimal proximity to the mechanically vibrating unit. Furthermore, the temperature sensor is located at the point of force transmission between the diaphragm and the transducer device. The mounting component also helps to transmit the force of the transducer device as efficiently as possible.
[0021] One embodiment consists of the mechanically oscillating unit being a rocker fork.
[0022] In one embodiment, the invention relates to a vibration sensor with any sensor, which forms a complete component with a transducer device. The embodiments then apply accordingly.
[0023] The invention is explained in more detail with reference to the following figures.
[0024] Fig. 1 shows a schematic cross-sectional view of a vibration sensor.
[0025] Fig. 2 shows the two end faces (Fig. 2 a) and Fig. 2 b)) of a piezo ring,
[0026] Fig. 3 shows a schematic section through a temperature sensor and a transducer device according to a first variant.
[0027] Fig. 4 shows the unit consisting of the temperature sensor and converter device of Fig. 3,
[0028] Fig. 5 shows a complete component according to a second variant,
[0029] Fig. 6 shows a top view of the overall component of Fig. 5,
[0030] Fig. 7 shows a section through a schematic overall component according to a third variant and
[0031] Fig. 8 shows a top view of the third variant of the overall component of Fig. 7.
[0032] Figure 1 shows a so-called rocker fork as an example of a
[0033] Design of the vibration sensor. The mechanically oscillating unit 1 has two so-called fork tines connected to a diaphragm 4. On the opposite, and therefore inner, side of the diaphragm 4, a transducer device 2 is located in a housing 5 (indicated here). This transducer device has several disc-shaped piezoelectric elements 21 arranged in a stack (see Fig. 2). The transducer device 2 rests on the diaphragm 4 with the temperature sensor 3 and is pressed against the diaphragm 4 by a pressure screw 6. An electronic unit (not shown here) is provided for exciting the vibrations and for evaluating the vibrations and the measurement signals from the temperature sensor 3.
[0034] Figures 2 a) and b) show the two end faces 210 of a disk-shaped piezoelectric ring 21 with double re-contacting. This means that the two electrodes 211 located on the end faces 210 are each connected via the outer surface to the opposite end face 210. The outer and inner circular rings thus each belong to the electrode 211 of the other end face 210. In the exemplary embodiment of the piezoelectric ring 21, the re-contacting extends over the entire inner and outer surface of the disk. Alternatively, the re-contacting – not shown here – occurs over a significantly limited section.
[0035] The example of the piezo ring 21 in Fig. 2 has a circular outer shape, whereas the piezo rings can alternatively be, for example, square.
[0036] Figures 3 and 4 each show a unit consisting of a converter device 2 and a temperature sensor 3 – once in a separate state (Fig. 3) and once as an assembled unit (Fig. 4). Both figures are discussed together.
[0037] The mushroom-shaped form of the temperature sensor 3 is visible, resulting from the elongated base body 30 and the end-face mounting component 31. A sensor element 32, a temperature-dependent resistance element, is located within the single-piece ceramic body 33. Two leads 34 are provided for acquiring the temperature-dependent measured value. The transducer device 2 consists of several piezoelectric rings 21, which are arranged in a stack and electrically connected to each other by the double re-contact described in relation to Fig. 2. Therefore, two contact leads 22 are sufficient for energizing the stack of piezoelectric rings 21, one of which leads out of the recess 20 and the other extends laterally.
[0038] Figure 4 clearly shows how the base body 30 of the temperature sensor 3 is located in the recess 20. It can also be seen that the support component 31 spans one end face of the transducer device 2 due to its maximum outer circumference. Furthermore, it can be seen that the temperature element 32 is located in close proximity to the diaphragm 4 (see Figure 1).
[0039] The section of Fig. 5 and the top view of Fig. 6 show another variant of the overall component consisting of converter device 2 and temperature sensor 3 and illustrate the positioning of the elongated base body 30 laterally to the converter device 2.
[0040] In the example shown in Figures 5 and 6, the base body 30 is designed in a column- or rod-like form, as in the example shown in Figures 3 and 4. Here, the base body 30 is located in a lateral recess 20 of the piezoelectric discs that form the transducer device 2. The sensor element 32 is located within the base body 30. The support component 31 is also semicircular in shape and is integrally integrated into the base body 30.
[0041] In the variant of the overall component shown in Figures 7 and 8, the transducer device 2 is flanked laterally by two base bodies 30, each located in a lateral recess 20 of the piezoelectric discs of the transducer device 2. The temperature sensor thus also partially surrounds the outer surface of the transducer device 2. In another variant—not shown here—this is extended to a partially sleeve-shaped temperature sensor. In the variant shown in Figures 7 and 8—as in the variant shown in Figures 5 and 6—the piezoelectric discs of the transducer device 2 are flat discs without an inner hole, unlike the rings in the variant shown in Figures 3 and 4. The two column-like base bodies 30 are diametrically opposed to each other and have—as can be seen particularly in Figure 8—differently sized base areas. Figure 7 indicates that each of the two base bodies 30 contains a sensor element 32.In one embodiment, this involves two temperature sensors. In an alternative embodiment, a temperature sensor and another sensor element, e.g., a humidity sensor, are combined.
[0042] Reference symbol: mechanically oscillating unit
[0043] Converter device
[0044] temperature sensor
[0045] membrane
[0046] Housing
[0047] pressure screw
[0048] recess
[0049] Piezo ring
[0050] Contact line
[0051] basic body
[0052] On position component
[0053] Sensor element
[0054] ceramic body
[0055] Line
[0056] Front
[0057] electrode
Claims
Patent claims 1. Vibration sensor, comprising a mechanically oscillating unit (1), a transducer device (2) which excites the mechanically oscillating unit (1) to mechanical vibrations and / or receives mechanical vibrations from the mechanically oscillating unit (1), and a temperature sensor (3), characterized in that the transducer device (2) and the temperature sensor (3) form a single component.
2. Vibration sensor according to claim 1, wherein the transducer device (2) has at least one lateral recess (20), wherein the temperature sensor (3) has at least one elongated base body (30) and an end-face arranged support component (31), wherein the base body (30) is at least partially arranged in the recess (20), and wherein the support component (31) forms an end face of the overall component consisting of the transducer device (2) and the temperature sensor (3).
3. Vibration sensor according to claim 1, wherein the temperature sensor (3) has at least one elongated base body (30) and a support component (31) arranged at the end face, wherein the base body (30) at least partially encloses the transducer device (2), and wherein the support component (31) forms an end face of the overall component consisting of the transducer device (2) and the temperature sensor (3).
4. Vibration sensor according to claim 1, wherein the transducer device (2) has a continuous recess (20), wherein the temperature sensor (3) is essentially mushroom-shaped, the temperature sensor (3) has an elongated base body (30) and a support component (31) arranged at the end face and designed as a partial sphere, wherein the base body (30) is arranged at least partially in the recess (20), wherein the support component (31) is arranged outside the recess (20), and wherein the transducer device (2) and the temperature sensor (3) are designed and coordinated such that a maximum radial extent of the support component (31) is essentially equal to a maximum radial extent of the transducer device (2).
5. Vibration sensor according to one of claims 1 to 4, wherein the vibration sensor has a membrane (4), wherein the mechanically oscillating unit (1 ) is arranged on the membrane (4), and wherein the support component (31 ) of the temperature sensor (3) sits on the membrane (4).