MOUNTING DEVICE FOR A FIELD DEVICE

Description

[0001] The present invention relates to a fastening device for a field device of process automation according to the preamble of patent claim 1.

[0002] Various mounting devices for field devices are known from the state of the art. In many cases, the field device is mounted in a measurement environment using a standardized process connection.

[0003] A process connection is the mechanical interface for arranging a field device, such as a sensor, in a process environment. Common process connections include various screw threads and flanges by means of which the field device can be arranged in the process environment. For this purpose, the field device is screwed into the wall of a container, such as a tank, silo, or pipeline, or connected to an attached flange.

[0004] The term field device encompasses various technical devices that are directly related to a production process. "Field" refers to the area outside of control rooms. Field devices can therefore include, in particular, actuators, sensors, and measuring transducers.

[0005] In process automation technology, field devices are often used to measure and / or influence process variables. Examples of such field devices include level measuring devices, point level measuring devices, and pressure measuring devices with sensors that measure the corresponding process variables (level, limit level, or pressure).

[0006] Self-contained field devices are characterized by particularly simple installation without the need for a communication or power supply line, thus offering particularly flexible configuration options, particularly their installation in the process environment. A self-contained field device according to the present application comprises at least one sensor for detecting a process variable, as well as sensor electronics, a radio module, and a power supply.

[0007] The measured values ​​​​obtained by these field devices are typically transmitted to a cloud, i.e., a server on the World Wide Web, using narrowband radio technology (LoRa, Sigfox, NB-IOT). Typical application scenarios for such field devices include areas such as flood forecasting, inventory management, or other decentralized measurement tasks.

[0008] Field devices for process automation with a metal housing and a radio module with an antenna are also known from the state of the art.

[0009] Such field devices are often connected to higher-level units, such as control systems or control units. These higher-level units are used for process control, process visualization, and / or process monitoring.

[0010] Field devices with metal housings are often used due to their mechanical stability and resistance to environmental influences. When field devices are used in potentially explosive environments, they must meet certain requirements that also require the use of metal housings. For example, with the explosion protection type flameproof enclosure (Exd), the housing of a field device must not burst when an explosion pressure occurs within the housing, which is usually achieved with metal housings. With the ignition protection type flameproof enclosure, the components that can trigger an ignition, e.g., of a flammable gas, are installed in an enclosure that can withstand the explosion pressure. The openings in the enclosure are designed to prevent the explosion from spreading to the outside.All closures and penetrations of the housing must be designed in accordance with this type of ignition protection and are therefore sometimes very complex to design.

[0011] For example, it is known from the state of the art to use radio modules to facilitate operation and parameterization of field devices. Operation and parameterization via radio modules facilitates the work of operating personnel on-site, as the field device does not have to be opened for parameterization, for example, and in potentially explosive environments, it may even have to be completely shut down.

[0012] However, the use of radio modules is incompatible with metal housings. If a radio transmitter / receiver is located inside the sensor housing along with the remaining sensor electronics of a field device, such as a level sensor, the metal housing walls prevent the propagation of electromagnetic waves and thus the desired radio connection.

[0013] It is therefore known from the prior art to equip metal housings with a glass window, which is used to provide readability for a built-in display and simultaneously allows a wireless connection through the glass window. However, it is considered disadvantageous that such a wireless connection is subject to strong directional effects and thus has limited usability.

[0014] Furthermore, it is known to route a communication signal via a coaxial cable through a separate cable feedthrough through the housing and to feed this signal to an external antenna mounted there. A disadvantage of this approach is that the field device housing requires an additional cable feedthrough and must be designed accordingly to be explosion-proof.

[0015] There are increasingly more measurement tasks that require a stand-alone field device to be installed directly in the process environment without the need for a complex process connection. This creates problems for wireless communication, particularly with metal process vessels, as the metal of the process vessel prevents the propagation of electromagnetic waves for the wireless connection. Currently, if a field device with a wireless module, particularly a sensor, is mounted inside a metal tank, an antenna lead-out is required to transmit the sensor data. Therefore, the use of stand-alone field devices is not possible in such situations, or it is necessary to provide an antenna cable through a cable lead-through from the process vessel. Mounts for the sensor, which require a cable lead-through and the antenna itself, are required. Furthermore, the antenna must be connected to the sensor via a cable.However, corresponding antenna connections are often not provided for autonomous field devices.

[0016] Further prior art is known from DE 10 2004 041 857 A1, US 2019 / 0056258 A1 and US 6 062 095.

[0017] It is the object of the present invention to further develop a fastening arrangement for a self-contained field device in such a way that a flexible arrangement of the field device is still possible.

[0018] This object is achieved by a field device having the features of patent claim 1.

[0019] A self-contained field device for process automation according to the invention, comprising a sensor, a radio module and a fastening device for fastening the field device to a wall, is characterized in that the fastening device is designed in at least two parts and is configured such that a first, sensor-side part of the fastening device can be arranged from a first side of the wall and a second part of the fastening device can be arranged from a second side of the wall, wherein the parts of the fastening device form a mechanical first interface penetrating the wall and the field device can thus be fastened to the wall.

[0020] The self-contained field device according to the invention can thus be attached with its fastening device through an opening in a wall, for example, of a container on which the field device is to be arranged. For attachment, the first part of the fastening arrangement is arranged on one side of the wall, for example, inside the container, and the second part of the fastening arrangement is arranged on an opposite side of the wall, for example, on the outside of the container. The two parts of the fastening device are connected to one another by the mechanical interface formed by the parts of the fastening device, so that the field device is attached to the wall.

[0021] Through the opening in the wall, radio signals can pass from one side of the wall to the other side of the wall, enabling radio communication of the field device.

[0022] At least one part of the fastening device is designed to at least partially penetrate the wall. This means that, in a sectional view, this part of the fastening device, in the assembled state of the field device, overlaps the wall at least partially. Preferably, the part penetrating the wall extends to the opposite side of the wall; for example, the first part of the fastening device, which is arranged on the sensor side, extends to the side of the wall on which the second part of the fastening device is arranged.

[0023] For example, if the field device's sensor is located inside a metal container, such as a metal tank, the present embodiment makes it possible to arrange an antenna of the field device's radio module in the part of the fastening device that penetrates the wall. This way, the antenna for the field device's radio communication is located outside the metal container, enabling radio communication.

[0024] A particularly clever design can be achieved if a portion of the sensor-side part of the fastening device is at least partially designed as the housing of the field device. In this way, the fastening device can be integrated, configured, preferably formed integrally with the housing.

[0025] In this way, in addition to simple manufacturing, it is also possible to ensure that no additional seals are necessary to ensure the tightness of the field device.

[0026] The parts of the fastening device also form a second interface for signal and / or energy transmission. This allows for signal and / or energy transmission in addition to a mechanical connection between the two parts of the fastening device.

[0027] For example, a display and / or control module of the field device can be arranged on the side of the wall facing away from the sensor, i.e., in particular, outside a container. Furthermore, it is possible to arrange a power supply in the form of a battery, an energy harvesting module, or other suitable means for providing energy to the field device outside the container.

[0028] An interface for signal transmission also makes it possible to arrange the antenna or the antenna and radio module of the field device on the side of the wall facing away from the sensor, i.e., particularly outside the container. This also makes it possible to design the second part of the fastening device as interchangeable, thus providing interchangeable radio modules and corresponding antennas.

[0029] For this purpose, the second part of the fastening device can preferably have one or more antennas. The one or more antennas can provide the prerequisites for radio communication according to one or more radio standards.

[0030] Additionally or alternatively, the second part of the fastening device may comprise a display and / or operating unit.

[0031] The part of the fastening device that penetrates the wall is preferably circularly cylindrical. A circular cylindrical design of this part facilitates both the creation and sealing of the opening. For example, the opening can easily be created by drilling a hole. A circular cylindrical opening can be sealed particularly easily using commercially available seals, such as O-rings.

[0032] To enable easy assembly and disassembly of the field device, the first mechanical interface can be designed as a screw, snap-in, bayonet, or plug-in connection. The mechanical interface can preferably be operated without tools, which can be achieved particularly easily with the aforementioned connection types.

[0033] If increased security against unauthorized access is desired, the first mechanical interface can alternatively be designed to be operable exclusively with special tools. This can be achieved by using special screw connections with proprietary tool engagements or by securing the aforementioned connection types with a locking device that can only be removed with a special tool.

[0034] Preferably, the sensor-side first part of the fastening device has a seal which is compressed by fastening the field device to the wall in such a way that it is brought into sealing contact with the wall.

[0035] In this way, it can be achieved that the opening required for the installation of the field device in question is sealed by the installation of the field device.

[0036] In various applications it can be useful if the second part of the fastening device is designed to be traversable.

[0037] A drive-over design of the second part of the fastening device enables the field device to be used, for example, in floor tanks, whereby the second part of the fastening device can be arranged outside the floor tank. A drive-over design also allows the second part of the fastening device to be arranged, for example, in manhole covers or manhole covers that are located in vehicle travel paths.

[0038] The field device may have an activation device which is designed such that the field device can only be activated when mounted on a wall; preferably, the activation device is designed such that the field device is automatically activated when mounted.

[0039] This prevents the field device from being activated and consuming energy while unmounted. This reduces energy consumption and prevents the field device from transmitting invalid measured values ​​because it is not correctly mounted.

[0040] With the present invention, dependence on the material properties of the container is no longer relevant, as the antenna or radio module can be arranged outside the container. Complex fastenings and cable feedthroughs, as required in the prior art, are no longer required.

[0041] The present invention now makes it possible to easily and quickly install level sensors at a measuring point, e.g., preferably in a metal container, and to enable an uninterrupted wireless connection. The dependence on special mounting devices such as flanges or threads at the measuring point is eliminated. A simple hole is sufficient for installation.

[0042] The fastening device, in particular the second part of the fastening device, can be designed to be very flat and thus still allows containers to be stacked.

[0043] The present invention will be explained in detail below using exemplary embodiments with reference to the accompanying figures. They show: Figure 1 shows a measuring arrangement for level measurement in a metal tank, Figure 2 shows an enlarged view of a first embodiment of a measuring arrangement according to the present application, Figure 3 shows an enlarged view of a second embodiment of a measuring arrangement according to the present application, Figure 4 shows an enlarged view of a third embodiment of a measuring arrangement according to the present application, Figure 5 shows an enlarged view of a fourth embodiment of a measuring arrangement according to the present application,

[0044] In the figures, unless otherwise stated, the same reference symbols designate the same or corresponding components with the same function.

[0045] Figure 1 shows a measuring arrangement 1 for level measurement in a metal tank with an autonomous field device 3, which is designed as a level measuring device, according to the present application.

[0046] In the present embodiment, the autonomous level measuring device 3 is designed as a radar level measuring device and measures the level of a medium 22 in a container 20. A bore is formed in a wall 21 of the container 20, in which bore the autonomous level measuring device 3 is held by means of a fastening device 5. For this purpose, the fastening device 5 has a first, sensor-side part 51, which is arranged together with at least the radar sensor for level measurement in the container 20.

[0047] The fill level sensor is arranged in a circular-cylindrical housing 7, which is formed integrally with the first part 51 of the fastening device 5. To form a mechanical interface, the first part 51 of the fastening device has a circular-cylindrical, bolt-shaped extension, which is arranged in the bore in the wall 21 and thus protrudes through the wall 21. On the side of the wall 21 opposite the first part 51 of the fastening device 5, the second part 52 of the fastening device 5 is arranged and mechanically connected to the bolt-shaped extension of the first part 51. The mechanical connection of the first part 51 and the second part 52 can be realized by various connection mechanisms, wherein in the present embodiment, a thread 53 serves to mechanically connect the two parts 51, 52.For this purpose, the bolt-shaped extension of the first part 51 has an external thread and the second part 52 has a corresponding internal thread.

[0048] Figure 2 shows an enlarged view of the measuring arrangement 1 from Figure 1 .

[0049] In the Figure 2 In the illustrated embodiment, a radio module 4 of the autonomous field device 3 is arranged in the sensor-side part of the field device. An antenna 9 for the radio communication of the autonomous field device 3 is located in the bolt-shaped extension of the first part 51 of the fastening device 5 and is thus arranged at least partially outside the container 20 and thus outside the metallic wall 21. In this way, radio communication of the autonomous field device 3, which would not be possible within the metallic container 20, is ensured.

[0050] In Figure 2Furthermore, the first interface between the first part 51 and the second part 52 of the fastening device 5, formed as a thread 53, can be clearly seen. It should be noted at this point that this mechanical interface can be formed not only as a thread 53 but also by various other mechanical interfaces, for example, plug connections, bayonet connections, various screw connections, or other quick couplings.

[0051] For the sake of clarity, further components of the autonomous field device 3, such as a sensor, sensor electronics, a power supply and possible further components, are not shown separately in the exemplary embodiment shown here, but are regarded as part of an autonomous field device 3 within the meaning of the present application.

[0052] Figure 3 shows a second embodiment of a measuring arrangement according to the present application.

[0053] The Figure 3 The embodiment shown differs from the embodiment of the Figure 2in that, in addition to the first, mechanical interface between the first part 51 and the second part 52, which is also realized here by a thread 53, a second, electronic interface for signal transmission is formed between the radio module 4 of the autonomous field device 3 and the antenna 9, which in the present embodiment is arranged in the second part 52 of the fastening device 5. The second interface for signal transmission is combined with the mechanical interface in such a way that a simple and preferably tool-free connection of the first part 51 and the second part 52 can still be realized. At the same time, however, signal transmission between the radio module 4 and the antenna 9 is ensured, so that radio communication of the autonomous field device 3 is ensured by the antenna 9 arranged outside the container 20.

[0054] In the Figure 4In the third exemplary embodiment shown, both the radio module 4 and the antenna 9 are arranged in the second part 52 of the fastening device 5. In this exemplary embodiment, too, both a mechanical interface and an electronic interface for signal transmission are formed between the first part 51 and the second part 52. However, since in the present exemplary embodiment the radio module 4 and the antenna 9 are both arranged in the second part 52 of the fastening device 5, the underlying radio technology can be achieved by simply replacing the second part 52 with another part having a radio module with a correspondingly adapted antenna for a different radio standard.

[0055] In this way, it is possible to adapt an existing field device to different radio standards depending on local conditions or, in the case of further developments of the underlying radio standards, to equip an installed field device 3 with a new radio module.

[0056] In Figure 5 a fourth embodiment of a measuring arrangement 1 according to the present application is shown.

[0057] In the Figure 5In the illustrated embodiment, radio modules 4, 12 and two associated antennas 9, 10 are arranged in the second part 52 of the fastening device 5. In this way, a field device 3 can also be equipped with different radio standards, one of which can be used, for example, for communication with a mobile operating device and the other for transmitting measured values ​​to a cloud. For example, the field device 3 can communicate with the mobile operating device according to the Bluetooth Low Energy standard, and the measured value transmission can take place using a narrowband radio technology, for example LoRa, Sigfox, or NB-IoT.

[0058] It should be noted at this point that various other components of a standalone field device 3 can also be arranged in the second part 52 of the field device 3. In particular, the power supply as well as display and / or control elements are mentioned here. For a power supply, it is advantageous that the second part 52 of the fastening device 5 is generally accessible from the outside without opening the container 20, so that, for example, a battery change can be carried out without disassembling the field device 3. Furthermore, various other energy sources outside the container can also be used to supply the field device 3. Examples of this include energy harvesting modules. Reference symbol

[0059] 1Measuring arrangement 3Autonomous field device 4Radio module 5Mounting device 7Housing 9Antenna 10second antenna 12second radio module 20Container 21Wall 22Medium 51first part 52second part 53thread

Claims

1. Autonomous field device (3) for process automation having a sensor, a wireless module (4) and a fastening device (5) for fastening the field device on a wall (21), characterized in that the fastening device (5) has at least a two-part design and is formed such that a first, sensor-side part (51) of the fastening device (5) can be installed from a first side of the wall (21) and a second part (52) of the fastening device (5) can be installed from a second side of the wall (21), wherein the parts (51, 52) of the fastening device (5) form a mechanical first interface penetrating the wall (21) in order to fasten the field device (3) on the wall (21) in this manner, wherein at least one part of the fastening device (5) is designed to penetrate the wall (21), wherein the first part (51) has a bolt-shaped extension of circular cylindrical design to form the mechanical interface, wherein the second part (52) of the fastening device (5) is arranged on the side of the wall (21) opposite the first part (51) of the fastening device (5) and can be mechanically connected to the bolt-shaped extension of the first part (51), wherein the parts (51, 52) of the fastening device (5) form a second interface for signal and / or energy transmission.

2. Autonomous field device (3) according to claim 1, characterized in that a part of the first part (51) of the fastening device (5) is ) is at least sectionally formed as a housing of the field device (3).

3. Autonomous field device (3) according to one of the preceding claims, characterized in that the second part (52) of the attachment device (5) has an antenna (9).

4. Autonomous field device (3) according to one of the preceding claims, characterized in that the second part (52) of the fastening device (5) comprises a display and / or operator unit.

5. Autonomous field device (3) according to one of the preceding claims, characterized in the first interface (51) is formed as a threaded, snap, bayonet, or socket connection.

6. Autonomous field device (3) according to one of the preceding claims, characterized in that the first interface (51) can be operated without tools.

7. Autonomous field device (3) according to one of claims 1 to 5, characterized in that the first interface (51) can be exclusively operated with special-purpose tools.

8. Autonomous field device (3) according to one of the preceding claims, characterized in that the first part (51) of the fastening device (5) comprises a gasket that is compressed against the wall (21) by fastening the field device (3) such that said gasket is brought into contact with the wall (21) to form a seal.

9. Autonomous field device (3) according to one of the preceding claims, characterized by an activation device which is designed such that the field device (3) can only be activated in a state installed on a wall (21).

10. Autonomous field device (3) according to claim 9, characterized in that the activation device is designed in such a way that the field device (3) is automatically activated in the installed state.

11. Modular set consisting of a first part (51) and several second parts (52), each with different radio modules (4) for implementing different wireless standards.