Automation field device

Abstract

Automation field device for determining a filling level (L) of a filling material (2) in a container (3), the field device being suitable for being subjected to a direct high-pressure water or vapor jet for cleaning purposes, and comprising: – a fully welded metallic field device housing (12) enclosing an interior (13) and having an integrated operator control and / or inspection window; – a transceiver unit (14) designed to generate radar signals (SHF) according to a defined radar principle and to determine the filling level (L) on the basis of corresponding reception signals (RHF), – an antenna (11), by means of which the generated radar signals (SHF) are emittable and receivable after reflection, – an operator control and / or display element (19) arranged in the interior (13) of the field device housing (12) behind the operator control and / or inspection window and configured to detect the pressing of a button by an operator on the operator control and / or inspection window; – a radio unit for wireless data transmission arranged in the interior (13) of the field device housing (12) behind the operator control and / or inspection window.

Description

[0001] Field device in automation technology

[0002] The invention relates to a field device in automation technology for determining a filling level of a filling material in a container.

[0003] Field devices used in industrial plants are known from the state of the art. Field devices are widely used in process automation technology as well as in manufacturing automation technology. In principle, field devices are all devices that are used close to the process and that provide or process-relevant information. Field devices are used to record and / or influence process variables. Measuring devices or sensors are used to record process variables. These are used, for example, for pressure and temperature measurement, conductivity measurement, flow measurement, etc. and record the corresponding process variables pressure, temperature, conductivity, pH value, fill level, flow rate, etc. Actuators are used to influence process variables. These are, for example, pumps or valves that can influence the flow of a liquid in a pipe or the fill level in a container.In addition to the measuring devices and actuators mentioned above, field devices also include remote I / Os, radio adapters and, in general, devices that are arranged at the field level.

[0004] A large number of such field devices are produced and distributed by the Endress+Hauser Group.

[0005] Non-contact measurement methods have become established for measuring the fill level of products in containers because they are robust and low-maintenance. In the context of the invention, the term "container" also includes open containers, such as pools, lakes, or flowing waters. A further advantage of non-contact measurement methods is their ability to measure the fill level virtually continuously. Therefore, radar-based measurement methods are predominantly used for continuous fill level measurement (in the context of this patent application, the term "radar" refers to signals or electromagnetic waves with frequencies between 0.03 GHz and 300 GHz).

[0006] An established measuring principle is FMCW (Frequency Modulated Continuous Wave). The measuring principle of FMCW radar-based distance measuring methods is based on the transmission of a continuous radar signal with a modulated frequency. A characteristic of FMCW is that the transmission frequency is periodically changed within a defined frequency band. In consideration of regulatory requirements, higher frequency bands in the range of a standardized center frequency are becoming increasingly popular with advancing developments: In addition to the 6 GHz band, the 26 GHz band, and the 79 GHz band, frequencies above 100 GHz are now implemented. The advantage of high frequencies is that a larger absolute bandwidth (e.g., 4 GHz in the 100 GHz frequency band) can be used. This, in turn, achieves higher resolution and greater accuracy in level measurement.The FMCW-based level measurement method is described, for example, in the published patent application DE 10 2013 108 490 A1.

[0007] The radar signals are transmitted and received as standard via a waveguide that serves as an antenna and expands in the direction of radiation, similar to a horn antenna, for example.

[0008] Hygienic processes place particularly high demands on their processing and / or cleanliness. Examples of such hygienic processes include applications in the food industry, where there is a risk that deposits and / or contamination can impair the shelf life and / or lead to harmful contamination of food. Therefore, for hygienic reasons, it is important that the field device seals the container opening as free of gaps and edges as possible to prevent the buildup of product deposits.

[0009] Furthermore, the housings of field devices for level measurement are specially designed to meet these requirements. For example, they are made of a metallic material such as 316L stainless steel and / or designed to minimize the number of points where deposits and / or contaminants can accumulate.

[0010] Furthermore, the housings of the field devices are designed so that they can be cleaned from the outside. To achieve this, they must be waterproof or hermetically sealed. The International Electrotechnical Commission (IEC) has introduced the IP protection class (International Protection Codes), which classifies electrical devices and specifies the environmental conditions for which they are suitable and the environmental conditions they must withstand. Of the defined protection classes, two protection classes are particularly important for the development of housings for hygienic use: IP68 and IP69. Protection class IP68 offers protection against permanent submersion or permanent immersion in water, even at great depths. Protection class IP69 ensures that liquids cannot penetrate, even under high pressure and at high temperatures. This can be the case, for example, when using high-pressure or steam jet cleaners.In addition to the requirements for the housing of field devices used in hygienic processes, there has recently been an increased need to connect field devices to external tools, such as smartphones / cell phones, cloud services, etc., for wireless data transmission. For this purpose, radio modules are typically integrated into the housing of the field device to enable a radio interface for data transmission with the field device. However, for a wireless connection to be possible, the radio signal would either have to be transmitted through an additional "opening" in the housing or the housing would have to have a non-metallic area.However, this can be critical for use in hygienic processes, so that an additional radio interface is omitted for a field device with a fully welded metallic housing or a conscious compromise is made in the architecture of the housing with regard to the requirements necessary for use in hygienic processes.

[0011] Two variants have become established in the state of the art. The first variant provides for the housing to be realized with a cover with a thread or bayonet lock. A second variant provides for the housing to be realized with a non-metallic head, e.g., made of plastic, that can be plugged onto the housing body.

[0012] While a cover-based architecture allows for a display or buttons for on-site operation and IP68 and / or IP69 protection, the disadvantages are the larger design, the resulting dirt-retaining edges and / or joints, and the increased production costs.

[0013] A non-metallic head with an integrated display or only buttons for local operation on the field device does not meet protection class IP68 and / or IP69. In addition, larger dirt edges and / or dirt gaps are created at the transition from metal to plastic.

[0014] The invention is based on the object of remedying this situation.

[0015] The object is achieved according to the invention by the field device of automation technology according to patent claim 1.

[0016] The field device according to the invention in automation technology for determining the fill level of a filling material in a container, wherein the field device is suitable for being exposed to a direct high-pressure water or steam jet for cleaning purposes and / or for being permanently submerged in water, even at great depths, comprises: a fully welded metallic field device housing which encloses an interior, preferably in a hermetically sealed manner, and has an integrated operating and / or viewing window; a transmitting / receiving unit which is designed to generate radar signals according to a defined radar principle and to determine the fill level based on corresponding received signals; an antenna by means of which the generated radar signals can be transmitted or received.can be received after reflection, an operating and / or display element arranged in the interior of the field device housing behind the operating and / or viewing window, which is designed to detect a keystroke by an operator on the operating and / or viewing window; a radio unit for wireless data transmission arranged in the interior of the field device housing behind the operating and / or viewing window.

[0017] According to the invention, an automation technology field device for determining the fill level of a filling material in a container is proposed, which field device is designed such that it has a fully welded metallic housing and can nevertheless transmit or receive a further radio signal in addition to the radar radio signal in order to communicate data wirelessly. For this purpose, the invention provides that a radio unit for wireless data transmission is arranged behind an operating and / or viewing window, which is preferably joined, in particular glued, to the fully welded housing. A fully welded housing is understood here to be a housing which originally consists of at least two parts, e.g. a housing body and a cover, which are welded together during production of the field device in such a way that the housing is permanently closed and the cover cannot be detached from the housing body by turning or the like.In other words, this means that the housing can only be reopened by destructive means. The fully welded housing allows the interior space to be hermetically sealed, making the field device suitable for use in hygienic processes, as it can be cleaned using a high-pressure or steam jet and / or the housing offers protection against continuous immersion in water, even at great depths.

[0018] An advantageous embodiment of the field device according to the invention can provide that the fully welded metallic field device housing with the integrated viewing screen is designed in such a way that the housing meets the requirements of protection class IP68 with regard to permanent immersion in water even at greater depths and / or IP69 with regard to exposure to a direct high-pressure water or steam jet for cleaning, in particular protection class IP68 and / or IP69 according to the standard IEC 60529, Edition 2.2 of 2013-08.

[0019] A further advantageous embodiment of the field device according to the invention can provide that the operating and / or viewing window is joined, in particular glued, to the field device housing.

[0020] A further advantageous embodiment of the field device according to the invention can provide that the field device housing has an integrated recess for receiving a front foil, and wherein the front foil is inserted into the recess.

[0021] A further advantageous embodiment of the field device according to the invention can provide that the recess is designed such that a depth of the recess corresponds at least to a material thickness of the front foil.

[0022] A further advantageous embodiment of the field device according to the invention can provide that the recess is designed and matched to the front foil in such a way that a circumferential gap is formed around the front foil introduced into the recess. In particular, the embodiment can provide that the circumferential gap has a maximum width of 0.2 mm, in particular of 0.15 mm.

[0023] The invention is explained in more detail with reference to the following drawings. It shows:

[0024] Fig. 1 : an example of a radar-based field device in automation technology for determining the level of a filling material in a container,

[0025] Fig. 2: a schematic sectional view of an automation field device designed for use in hygienic applications, and

[0026] Fig. 3: a detailed view of the area of ​​the field device housing in which the operating and / or display element is located behind a front foil.

[0027] To understand the invention, Fig. 1 shows a container 3 with a filling material 2, the fill level L of which is to be determined. Depending on the type of filling material 2 and the area of ​​application, the container 3 can be up to more than 100 m high. In order to be able to determine the fill level L, a radar-based field device of automation technology 1 for determining a fill level 1 above the filling material 2 is attached to the container s at a known installation height h above the brine. The field device 1 is attached to a standardized container opening 3 in such a way that radar signals SHF, RHF can be transmitted into the container 3 via an antenna 23 or can be received after they have been reflected from the surface of the filling material. As is illustrated in Fig. 1, the container opening orthe field device 1 is designed such that the antenna 23 radiates the radar signal SHF along a defined beam axis a vertically downwards towards the filling material 2, wherein the beam axis a in the embodiment shown simultaneously runs orthogonally to the container ceiling due to the installation situation.

[0028] After reflection of the emitted radar signals SHF at the product surface, the field device 1 receives the reflected radar signals RHF. The resulting signal propagation time t between emission and reception of the respective radar signal SHF, RHF is accordingly proportional to the distance d between field device 1 and medium 2. In this context, "c" is the media-dependent radar propagation velocity. To determine the signal propagation time t, the FMCW or pulse transit time method can be implemented in field device 1.

[0029] Accordingly, the generation of the transmitted radar signals (SHF) and the reception of the corresponding received signals (RHF) within the field device 1 are carried out by a correspondingly designed transmit / receive unit 14, which couples to an end region of the antenna 23 facing away from the container interior. In the case of the FMCW method, the transmit / receive unit 14 can be designed, for example, based on a phase-locked loop. In the case of the pulse transit time method, the transmit / receive unit can be based on the principle of pulse subsampling.

[0030] For example, after appropriate calibration, field device 1 can again assign the measured signal propagation time t to the respective distance d. This allows field device 1 to determine the fill level L at least at a specific point according to d = h — L, provided the installation height h is stored in field device 1.

[0031] Figure 2 shows a schematic sectional view through an inventive

[0032] Field device of automation technology 10 for determining the fill level of a

[0033] Filling material in the container. The field device 10 comprises a field device housing 12 that encloses an interior space 13. The field device housing is a metallic housing. In particular, it can be a stainless steel housing. Furthermore, the housing is a fully welded housing, i.e., a housing that can only be opened by a destructive method. This can be achieved, for example, by the housing being constructed from two parts, e.g., a housing body and a housing cover, which are welded together during production.

[0034] The field device housing 12 can have an at least partially rotationally symmetrical region 17 into which the field contact plug 21 is to be or is integrated. The field device 10 further comprises a transmit / receive unit 14, which, as described above, is configured to generate radar signals SHF ZU according to a defined radar principle and to determine the fill level L based on corresponding receive signals RHF.

[0035] An electronic circuit 15, which is installed in an interior space 13 of the field device housing and is designed, among other things, to operate the transmitting / receiving unit, serves to provide and / or process a sensor signal.

[0036] In the present exemplary embodiment, the electronic circuit has three printed circuit boards, two of which are arranged in the longitudinal direction of the housing and one printed circuit board 15c is arranged transversely to the housing. The invention is independent of the number of printed circuit boards arranged longitudinally and / or transversely to the housing. For example, only one or three printed circuit boards can be arranged longitudinally. The printed circuit boards 15a, 15b, 15c are plugged into one another via corresponding plug connectors and mating plug connectors 15d and thus electrically contacted. Plug connectors and mating plug connectors can be designed as either rigid or flexible connectors. Plug and mating plug connectors can also be interchanged.

[0037] The electronic circuit further comprises connection electronics 20 with at least one first printed circuit board 25 with a field contact connector 21, which is arranged along a longitudinal axis of the printed circuit board 25 and soldered to a printed circuit board edge. Data, in particular measured values, and / or energy are transmitted from the field device 10 to an external unit, e.g., a higher-level unit or another field device, via the field contact connector 21.

[0038] The field contact connector 21 can, in particular, be a circular connector, e.g., an M12 circular connector. However, it can also be other common connectors suitable for transmitting data and / or power. For example, it can also be an Ethernet connector. Furthermore, the field contact connector 21 can also be a cable gland through which a cable for electrical contact is routed into the interior of the field device.

[0039] The connection electronics 20 further comprises at least one mating connector 22, which can be arranged and attached on the first circuit board 25 such that a plug-in axis 23 is inclined or tilted relative to a main plane in which the first circuit board 25 is formed. The connection electronics is connected to one of the circuit boards of the electronic circuit via the mating connector 22 of the connection electronics via a matching plug-in connector 15e present there. The plug-in connector and mating connector can be designed as either rigid or flexible connectors. Likewise, the plug-in and mating connectors can be interchanged. Furthermore, electronic components for EMC and / or explosion protection measures 24 can be mounted on the first circuit board 25.

[0040] The electronic circuit 15 located in the field device 10 can be arranged at least partially in an electronics housing 16, which has a secure fit in the field device housing and, if necessary, also serves to secure the circuit boards of the electronic circuit. The electronics housing 16 is essentially adapted to an outer contour of the field device housing. Furthermore, the electronic circuit components located in the electronics housing 16 can be encapsulated using a potting compound 27.

[0041] The field device housing 12 further has a housing opening 18 through which the field contact plug is led to the outside. For mechanical fixing and / or alignment or positioning, a precisely fitting plug sleeve is pushed over the field contact plug and attached in or to the field device housing. The plug sleeve 26 is welded to the outside of the field device housing. In order to fix the plug sleeve during the welding process, it can be fastened to the electronics cup 16 by means of a fastening device. This can be done, for example, via a locking mechanism on the electronics cup 16 arranged in the field device housing. For example, a first fastening element can be realized by a locking geometry molded onto the electronics cup 16, e.g. in the form of a locking lug. To enable locking or clipping in, a circumferential groove is implemented on the plug sleeve 26 as a second fastening element.The interaction of the two fastening elements prevents the field contact plug from being influenced during the welding process, e.g. by the dynamics of the welding system or the influence of shielding gas flows, since the plug sleeve 26 is attached to the.

[0042] Electronics cup 16 is fixed. Furthermore, a laser beam has free access to the welding point.

[0043] At an upper end of the field device 10, the field device housing 12 has an operating and / or display element 19 for display and / or operation. The operating and / or display element 19 can, for example, be a display for visualizing information. For operation, the operating and / or display element 19 can also have capacitive buttons. These can, for example, be implemented using a corresponding capacitive foil. It is also possible for the operating and / or display element 19 to have only one or more LEDs, via which a status or other information of the field device is signaled. Furthermore, the operating and / or display element 19 can also have optical buttons for operation.

[0044] To meet the requirements of protection class IP68 and / or IP69, in particular protection class IP68 and / or IP69 according to the IEC 60529 standard, Edition 2.2 of 2013-08, the operating and / or display element 19 is arranged behind an operating and / or viewing window 11 incorporated into the field device housing. The operating and / or viewing window 11 can be joined, in particular glued, to the housing 12, for example, using a joining process, in particular an adhesive process.

[0045] Additionally, the operating and / or display element 19 can be arranged behind a front foil 60 inserted into a recess 12a of the field device housing. Such front foils 60 are now used in almost all branches of industry. As a rule, these front foils 60 are made of polyester or polycarbonate foils. The front foil 60 can be arranged in a corresponding recess 12a provided in the field device housing 12. Figure 3 shows in detail the area of ​​the field device housing 12 in which the operating and / or display element 19 is arranged. The front foil 60 can be designed as a self-adhesive foil. Furthermore, the front foil 60 can be printed on the back so that the printing is protected from dust, moisture, chemical influences, scratches, heat, cold, wear and tear due to transport or constant use.

[0046] With regard to the recess 12a, this can be designed such that the housing 12 has an enforced contour as a recessed pocket for receiving the front film 60. The recess 12a can be created, for example, by means of an embossing die during the manufacture of the housing 12. The recess 12a can also be designed such that a circumferential gap 12b necessary for assembly is present or results. This means that the recess can be designed somewhat higher and / or wider than the height and / or width of the front film 60 to be placed in the recess. Ideally, the gap has a maximum width of 2 mm, in particular a maximum of 0.15 mm. Alternatively or additionally, the recess can also be designed such that a depth of the recess corresponds to at least one material thickness of the front film, thus ensuring that a high-pressure water or steam jet applied from the side cannot attack the rear of the front film.In order to protect the operating and / or display element 19, which is otherwise only protected by the front foil, from the high-pressure water or steam jet, it can be arranged behind a viewing or operating window 11 integrated in the housing 12 in the interior 13 of the field device.

[0047] In order to ensure the best possible representation and readability of the information on or from the operating and / or display element, it may be necessary for the operating and / or display element 19 to rest as flat and / or evenly as possible against the back of the viewing or operating window 11. For this purpose, a display frame 30 can be used, which on the one hand accommodates the operating and / or display element 19 and on the other hand places it accordingly behind the viewing or operating window 11. For this purpose, the display frame 30 can be fastened to a carrier plate 50 appropriately positioned in the interior 13, so that the operating and / or display element 19, which is arranged in a receiving surface 37 and optionally fixed there, is pressed against the viewing window 11 by the display frame 30. The carrier plate can be a printed circuit board 50, which can be configured, for example, to enable the evaluation and / or control or operation of the operating and / or display element 19.The display frame 30 can be axially aligned via the guide pins 35, which are inserted into corresponding holes on the circuit board 50. The display frame 30 is secured via two locking hooks 36, which engage on a side of the circuit board 50 facing away from the display frame 30 for fixing.

[0048] Additionally, the previously described display frame 30, including the carrier or circuit board, can be integrated into a display holder 40. The display holder 40 can preferably be designed such that it also has its own locking elements, in particular in the form of locking hooks, with which it is also attached to the carrier or circuit board 50. In this way, the display frame 30 with the operating and / or display element 19, the circuit board 50, and the display holder 40 form a unit or assembly. Furthermore, the display holder 30 can also have the operating or viewing panel 11.

[0049] According to the invention, a radio unit 51 for wireless data transmission is further provided in the interior 13 of the field device housing 12 behind the operating and / or viewing window. The radio unit 51 is configured to transmit and / or receive data wirelessly. The radio unit 51 can, for example, be arranged on the carrier plate 50 serving as a circuit board in the area behind the operating and / or viewing window 11. The radio unit 51 can, for example, be a Bluetooth radio unit for wirelessly transmitting data using the Bluetooth standard or a variant modified therefrom, e.g., Bluetooth Low Energy. Alternatively, the radio module can also be a WLAN, ZigBee, NFC, IoT, 5G, or WirelessHART radio module. The data can, for example, be configuration and / or parameterization data for the field device.

[0050] List of reference symbols

[0051] Filling material

[0052] container

[0053] Superior unit

[0054] Field device in automation technology

[0055] Viewing or operating window

[0056] Field device housing a Recess for the front foil b Circumferential gap

[0057] Interior

[0058] Transmitting / receiving unit

[0059] Electronic circuit a-15c Printed circuit boards d Plug and mating connectors e Connectors

[0060] Electronics cup a locking lug

[0061] Rotationally symmetric area

[0062] Housing opening

[0063] Control and / or display element, e.g. in the form of a display

[0064] Connection electronics

[0065] Field contact plug

[0066] Mating connector of the connection electronics

[0067] antenna

[0068] Electronic components, e.g. for EMC and / or explosion protection measures

[0069] First circuit board of the connection electronics

[0070] Plug sleeve for field contact plug

[0071] Potting compound

[0072] Display frame

[0073] Guide pins

[0074] Display holder

[0075] Carrier plate, e.g. in the form of a circuit board

[0076] radio unit

[0077] Front film

Claims

Patent claims 1 . A field device in automation technology for determining a fill level (L) of a filling material (2) in a container (3), which is suitable for being exposed to a direct high-pressure water or steam jet for cleaning and / or for being permanently submerged in water, even at great depths, comprising: a fully welded metallic field device housing (12) which encloses an interior space (13), preferably in a hermetically sealed manner, and has an integrated operating and / or viewing window; a transmitting / receiving unit (14) which is designed to generate radar signals (SHF) according to a defined radar principle and to determine the fill level (L) on the basis of corresponding received signals (RHF), an antenna (11) by means of which the generated radar signals (SHF) can be transmitted orcan be received after reflection, an operating and / or display element (19) arranged in the interior (13) of the field device housing (12) behind the operating and / or viewing window, which is designed to detect a keystroke by an operator on the operating and / or viewing window; a radio unit (51) for wireless data transmission arranged in the interior (13) of the field device housing (12) behind the operating and / or viewing window (11).

2. Field device of automation technology according to the preceding claim, wherein a display frame (30) is provided which is arranged in the interior (13) of the fully welded metallic field device housing (12) and is designed to receive the operating and / or display element (19) and to place it essentially flat and / or evenly on a rear side of the operating and / or viewing window (11).

3. Field device of automation technology according to the preceding claim, wherein the display frame (30) is fastened to a support plate (50) arranged accordingly in the interior (13), so that the operating and / or display element (19) arranged and preferably fixed in a receiving surface (37) is pressed against the viewing window (11) by the display frame (30).

4. Field device of automation technology according to the preceding claim, wherein the carrier plate (50) has a printed circuit board which is preferably designed to implement the evaluation, control and / or operation of the operating and / or display element (19).

5. Field device of automation technology according to the preceding claim, wherein the radio unit (51) is arranged on the carrier plate serving as a printed circuit board (50) in the area behind the operating and / or viewing window (11).

6. Field device of automation technology according to one or more of the preceding claims, wherein the radio unit (51) is configured for wireless data transmission by means of the Bluetooth standard, a variant modified therefrom, in particular Bluetooth Low Energy.

7. Field device of automation technology according to one of claims 1 to 5, wherein the radio unit (51) is configured for wireless data transmission by means of WLAN, ZigBee, NFC, lloT, 5G or WirelessHART.

8. Field device of automation technology according to one or more of the preceding claims, wherein the fully welded metallic field device housing (12) with the integrated viewing screen is designed such that the housing meets the requirements of protection class IP68 with regard to permanent immersion in water even at greater depths and / or IP69 with regard to exposure to a direct high-pressure water or steam jet for cleaning, in particular protection class IP68 and / or IP69 according to the standard IEC 60529, Edition 2.2 of 2013-08.

9. Field device of automation technology according to one or more of the preceding claims, wherein the operating and / or viewing window (11) is joined, in particular glued, to the field device housing (12).

10. Field device of automation technology according to one or more of the preceding claims, wherein the field device housing has an integrated recess (12a) for receiving a front foil (60), and wherein the front foil (60) is introduced into the recess (12a).

11. Field device of automation technology according to one or more of the preceding claims, wherein the recess (12a) is designed such that a depth of the recess corresponds at least to a material thickness of the front foil (60).

12. Field device of automation technology according to one or more of the preceding claims, wherein the recess (12a) is designed and matched to the front foil (60) in such a way that a circumferential gap (12b) is formed around the front foil (60) introduced into the recess (12a).

13. Field device of automation technology according to the preceding claim, wherein the circumferential gap (12b) has a maximum width of 0.2 mm, in particular of 0.15 mm.

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