Automation field device

Abstract

The invention relates to an automation field device (10) having: - a field device housing (12); - field device electronics (15) including at least one printed circuit board (15a); - a PCB holder (16), placed inside the field device housing, for securing the PCB (15a), said PCB holder (16) being provided with a latching mechanism (60a) for resistibly fastening the PCB (15a), the PCB (15a) being provided with at least one mating latching mechanism (60b) corresponding to the latching mechanism on the PCB holder; the latching mechanism (60a) is in the form of a latch which protrudes from or is introduced into the wall, the latch being resilient in such a way that in an unlatched state in which at least the portion of the PCB holder is not introduced into the field device housing, the latch projects beyond the actual outer contour of the wall of the PCB holder, while in a latched state in which at least the portion of the PCB holder is introduced into the field device housing, the latch moves in the direction of the at least one PCB to latch into the mating latching mechanism. )

Description

[0001] Field device in automation technology

[0002] The invention relates to a field device in automation technology and a method for producing such a field device in automation technology.

[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 factory automation technology. In principle, field devices are all devices that are used close to the process and 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] Such field devices have a sensor element which is in particular at least temporarily and / or at least partially in contact with a process medium and which serves to generate a signal which is dependent on the process variable. These field devices also have an electronics unit arranged in a housing, wherein the electronics unit serves to process and / or forward signals generated by the sensor unit, in particular electrical and / or electronic signals. Typically, the electronics unit comprises a plurality of circuit boards with components arranged thereon. The circuit boards are usually arranged in a circuit board holder and mechanically fixed. Fig. 1 shows such a circuit board holder as is known from the prior art. According to the prior art, it is currently common practice to use a detachable snap-in or snap-in device located on the base of the circuit board holder for the mechanical fixing of the circuit boards.A locking mechanism must be provided to ensure that the circuit board is secured to the circuit board holder. The arrangement of the locking or latching mechanism on the base of the circuit board holder is due to the fact that this is technically impossible during the production of the circuit board holder (demolition of the tool). The locking or latching mechanism is usually implemented in such a way that an elongated, flexible arm is prepared from a side wall of the circuit board holder. On a side facing the center axis of the circuit board holder, the arm has a lug that engages a corresponding notch in the inserted circuit board.

[0006] Due to the design and arrangement of the snap-in or locking mechanism on the base, the PCB holder is penetrated to the outside at its side wall and is therefore no longer leak-tight at these points. This leak means that in potting processes in which the PCBs inserted in the PCB holder are potted with a potting compound, e.g. Silgel, it is not possible to pot the PCB holder before inserting it into the housing of the field device (pre-assembly of the PCB holder) because the potting compound is not held in the PCB holder. For this reason, the PCB holder must first be inserted into the housing before potting, since the housing serves as the outer shell for the PCB holder and thus at least partially prevents or reduces the leakage of the potting compound.To prevent the potting compound from spreading into unwanted areas of the housing during the potting process of the PCB holder already inserted into the housing, additional sealing measures are required in the housing and / or the PCB holder. These additional measures, in turn, lead to increased costs and effort during manufacturing. Furthermore, the more potting compound is introduced into the housing, the longer the curing time for the potting compound.

[0007] The invention is therefore based on the object of remedying this situation.

[0008] The object is achieved according to the invention by the field device of automation technology according to patent claim 1 and the method according to patent claim 8.

[0009] The field device of automation technology according to the invention comprises: a field device housing; field device electronics arranged in the field device housing with at least one printed circuit board; a printed circuit board holder arranged in the field device housing for holding the at least one printed circuit board, wherein the printed circuit board holder is adapted with a circumferential outer contour of a wall at least in a partial section to an inner contour of the field device housing such that the outer contour of the printed circuit board holder lies essentially flush with the inner contour of the field device housing, wherein the printed circuit board holder has at least one latching mechanism in the region of the partial section for the robust fastening of the at least one printed circuit board, wherein the at least one printed circuit board has at least one counter-latching mechanism corresponding to the latching mechanism of the printed circuit board holder, wherein the latching mechanism is in the form of ais formed with a locking lug introduced into the wall, wherein the locking lug is designed to be flexible in such a way that, in a non-latched state, in which the circuit board holder is not inserted into the field device housing at least with the partial section, it protrudes beyond the actual outer contour of the wall of the circuit board holder and, in a latched state, in which the circuit board holder is inserted into the field device housing at least with the partial section, it can be moved in the direction of the at least one circuit board.has moved in order to engage in the counter-locking mechanism, wherein the at least one circuit board is introduced into the circuit board holder and the circuit board holder is inserted at least with the partial section into the field device housing, so that the locking and counter-locking mechanisms lock into one another and the circuit board holder holds the at least one circuit board, wherein the at least one circuit board is potted with a potting compound in the circuit board holder up to a predetermined potting height, wherein the locking and counter-locking mechanisms are designed in or on the circuit board holder or the at least one circuit board in such a way that the locking and counter-locking mechanism is formed above the potting height, so that the locking and counter-locking mechanism is not potted.

[0010] An advantageous embodiment of the field device according to the invention for automation technology can provide that the locking lug has an elongated arm prepared from the wall of the circuit board holder and a locking hook located at one end of the elongated arm.

[0011] A further advantageous embodiment of the field device according to the invention for automation technology can provide that the at least one printed circuit board (15a) has at least one recess into which the locking lug can engage in the locked state.

[0012] Yet another advantageous embodiment of the field device according to the invention for automation technology can provide that the circuit board holder has at least two latching mechanisms for robustly fastening the at least one circuit board, and the at least one circuit board has at least two counter-latching mechanisms corresponding to the respective latching mechanism of the circuit board holder. In particular, the embodiment can provide that the at least two latching mechanisms of the circuit board holder are arranged diametrically opposite one another, and the at least two counter-latching mechanisms of the at least one circuit board are formed diametrically opposite one circuit board edge of the at least one circuit board, wherein the circuit board edge is located at an end of the circuit board opposite the end inserted into the circuit board holder.

[0013] A further advantageous embodiment of the field device according to the invention in automation technology can provide that the circuit board holder is designed in the form of a cup.

[0014] A further advantageous embodiment of the field device according to the invention in automation technology can provide that the circuit board holder is designed in such a way that it has no opening in the outer contour up to the predetermined potting height.

[0015] The invention further relates to a method for producing a field device of automation technology according to at least one of the previously described embodiments, comprising the following method steps:

[0016] Providing the field device housing;

[0017] Providing the field device electronics with the at least one circuit board;

[0018] Providing the circuit board holder for holding the at least one circuit board;

[0019] Inserting the at least one printed circuit board into the printed circuit board holder in the non-latched state, in which the printed circuit board holder, at least with the partial section, is not yet inserted into the field device housing; inserting the printed circuit board holder, at least with the partial section, into the field device housing such that the locking lug moves toward the at least one printed circuit board and, in the latched state, engages the counter-latching mechanism.

[0020] An advantageous embodiment of the method according to the invention can provide that the at least one circuit board in the circuit board holder is potted with a potting compound up to the predetermined potting height before the circuit board holder is inserted into the field device housing.

[0021] An alternative embodiment of the method according to the invention can provide for the at least one circuit board in the circuit board holder to be potted with a potting compound up to the predetermined potting height after the circuit board holder is inserted into the field device housing. The invention is explained in more detail with reference to the following drawings. It shows:

[0022] Fig. 1 : a circuit board holder known from the state of the art as it is commonly used today in a field device of automation technology,

[0023] Fig. 2: exemplary sectional view of a field device in automation technology,

[0024] Fig. 3: a sectional view through a printed circuit board holder intended for use in a field device of automation technology with a printed circuit board located therein, which is to be held in the printed circuit board holder by means of a locking and counter-locking mechanism, wherein in the position shown the locking mechanism does not yet engage in the counter-locking mechanism (non-locked state), and

[0025] Fig. 4: a sectional view through a circuit board holder intended for use in a field device of automation technology with a circuit board located therein, which is held in the circuit board holder by means of the snap-in and counter-snap-in mechanism (locked state).

[0026] Figure 1 shows a circuit board holder 16 known from the prior art, as is commonly used today in a field device of automation technology 10. The circuit board holder 16 has lateral guide rails 16a, which serve to hold the circuit boards. Furthermore, the circuit board holder 16, as already described above, has a releasable snap-in or locking mechanism 16b in the lower area, via which a circuit board (not separately shown in Fig. 1) can be mechanically fixed in the circuit board holder 16. The snap-in or locking mechanism 16b is implemented in such a way that two opposing elongated arms 16c were prepared from a side wall of the circuit board holder 16 during its manufacture, so that the arms 16c have a certain degree of flexibility.On a side of each arm 16c located towards the central axis of the circuit board holder 16, the circuit board holder 16 further comprises a nose 16d which is intended to engage a corresponding notch of the inserted circuit board.

[0027] This circuit board holder 16 was previously inserted into the field device housing 12 and then filled with a potting compound 27. By inserting the circuit board holder 16 into the housing 12, the “leaking

[0028] The "points" (wall openings for removing the arms) were at least partially sealed by the tightly fitting housing wall, so that the potting compound 27 remained in the circuit board holder 16. In order to prevent the potting compound 27 from penetrating an unwanted area of ​​the field device housing 12, e.g., in the direction of the electronics unit used to process and / or transmit signals generated by the sensor element 14, which electronics unit is arranged further down in the housing 12, it may be necessary to implement further sealing measures in the housing 12.

[0029] Fig. 2 shows an exemplary cross-sectional view of a field device used in automation technology. The field device 10 comprises a field device housing 12 enclosing an interior space 13. The field device housing 12 has a region 17 that is at least partially rotationally symmetrical, into which a printed circuit board holder 16, to be described in more detail below, is inserted.

[0030] Furthermore, the field device 10 comprises a sensor assembly arranged at the end of the field device housing 12 with a sensor and / or actuator element 14 for setting and / or detecting a process variable and a process connection 28. The process connection 18 can be a threaded design or a screw- or clampable flange.

[0031] In the present embodiment, the sensor and / or actuator element 14 comprises a fill level sensor element for detecting a fill level as a process variable. Nevertheless, the invention is not limited to the type or specific design of the sensor and / or actuator element as a fill level sensor element, but can in principle be applied to any other sensor or actuator principle.

[0032] Field device electronics 15, which is installed in an interior space 13 of the field device housing and is designed to operate the sensor and / or actuator element 14, serves to provide and / or process a sensor and / or actuator signal.

[0033] In the present embodiment, the field device electronics comprises three circuit boards 15a, 15b, and 15c. The circuit boards 15a, 15b, and 15c are electrically connected to one another via corresponding connectors and mating connectors 15d.

[0034] Connectors and mating connectors can be designed as either rigid or flexible connectors. Plug and mating connectors can also be interchanged.

[0035] The field device electronics 15 further comprises a fourth circuit board 25 serving as connection electronics 20 with a field contact connector 21 arranged along a longitudinal axis of the circuit board 25 on a circuit board edge and soldered thereto. Data, in particular measured values, and / or energy can be 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. The field contact connector 21 can, in particular, be a circular connector, e.g., an M12 circular connector. To route the field contact connector to the outside, the field device housing 12 has a correspondingly designed housing opening 18. The fourth circuit board 25 can also be electrically connected to one of the other circuit boards via a plug-in and mating connector 15e, 22.Furthermore, electronic components for EMC and / or explosion protection measures 24 can be applied to the circuit boards.

[0036] At an upper end of the field device 10, the field device housing 12 has a display 19 for display and / or operation. The display can have capacitive buttons for operation. These can be implemented, for example, using a suitable capacitive film. To meet hygiene requirements, the display can be arranged behind a viewing or operating panel 11 integrated into the housing 12 in the interior 13 of the field device. To ensure the best possible representation and readability of the information on the display 19 located behind the viewing panel 11 and / or to ensure smooth operation of capacitive buttons, the display 19 should rest as flat and / or evenly as possible on the back of the viewing or operating panel 11. This can be achieved, for example, by a display frame 30 that accommodates the display on the one hand and places it accordingly behind the viewing or operating panel 11 on the other.

[0037] The printed circuit boards 15a, 15b, 15c, 25 of the field device electronics 15 are at least partially arranged in a printed circuit board holder 16 and are mechanically secured by it. The outer contour of the printed circuit board holder is designed such that, at least in sections, it rests essentially flush against an inner wall of the rotationally symmetrical area.

[0038] In the exemplary embodiment shown in Fig. 2, the circuit board holder 16 has a cup-like shape. To accommodate the circuit boards, the circuit board holder 16 can have lateral guide rails 16a on an inner side, as is also shown in Fig. 1. In this case, two guide rails 16a, preferably arranged diametrically to one another, can be provided to accommodate a circuit board. Furthermore, the circuit board holder 16 has a latching mechanism 60a for the robust fastening of the circuit board 15a. The circuit board 15a itself, in turn, comprises a corresponding counter-latching mechanism 60b for this purpose. It goes without saying that a further latching and counter-latching mechanism is present for each circuit board that is to be held in the circuit board holder. In the exemplary embodiment shown in Fig. 2, the position orThe position of the latching and counter-latching mechanism is shown merely by way of example by a box with the reference numerals 60a, 60b. The latching and counter-latching mechanism is arranged in the upper region of the circuit board holder or the circuit board, i.e. on the side facing away from the sensor and / or actuator element 14. A circuit board 15a is arranged in the circuit board holder, for example, and is releasably held in the circuit board holder 16 by means of a latching and counter-latching mechanism 60a, 60b. The circuit board 15a is potted in the circuit board holder 16 up to a predetermined potting height 27a using potting compound 27. A Silgel, for example, can serve as the potting compound. The potting height 27a is usually set such that the potting compound occupies approximately half to two-thirds of the volume of the circuit board holder 16. The locking and counter-locking mechanism 60a, 60b is then in the area of ​​the circuit board holder 16 orthe circuit board 15a, which is not potted. Preferably, the circuit board holder (16) is designed such that it has no opening in the outer contour up to the predetermined potting height 27a, so that the potting compound does not leak out of the circuit board holder during potting. Furthermore, the circuit boards 15b and 15c are potted with the potting compound 27 in the circuit board holder.

[0039] Potting can be performed before the PCB holder is inserted into the field device housing, allowing the PCB holder and the PCB inside to be manufactured as a pre-assembled unit. Alternatively, the PCB holder can also be potted with the potting compound after it has been inserted into the field device housing.

[0040] For a more detailed description of the latching and counter-latching mechanism 60a, 60b, Fig. 3 shows an exemplary sectional view through a circuit board holder 16 intended for use in a field device of the automation technology 10, with a circuit board 15a located therein, which is to be held in the circuit board holder 16 by means of the latching and counter-latching mechanism 60a, 60b. Fig. 3 shows the unlocked state, in which the circuit board holder 16 is at least not inserted into the field device housing 12 with the partial section and the latching and counter-latching mechanisms 60a, 60b are not engaged with one another. Fig. 4, on the other hand, shows the engaged state, in which the circuit board holder 16 is at least inserted into the field device housing 12 with the partial section and the latching and counter-latching mechanisms 60a, 60b are engaged with one another.

[0041] As can be seen from Fig. 3, the locking mechanism 60a is designed in the form of a locking lug formed in or from the wall of the circuit board 15a, and the counter-locking mechanism 60b of the at least one circuit board 15a is designed in the form of a recess into which the locking lug can engage when locked. The locking mechanism 60a can be produced, for example, during the manufacture of the circuit board holder 16, e.g., by means of a corresponding injection-molding process. The counter-locking mechanism 60b can be produced, for example, by milling a corresponding outer contour of the circuit board 15a.

[0042] The locking lug 60a itself, in turn, has a flexible, elongated arm 60d, which is connected at one end to the wall of the circuit board holder 16 and at the other end of which a locking hook 60e is arranged. The locking lug 60a is designed such that, in the non-locked state shown in Fig. 3, it protrudes beyond the actual outer contour of the wall of the circuit board holder 16. In particular, the locking lug 60a is designed such that, in this state, the locking hook 60e of the locking lug protrudes beyond the outer contour, so that the locking hook 60e does not yet engage the counter-locking mechanism 60b of the already inserted circuit board 15a. From this position, the flexible locking lug 60a can be brought into the locked state by inserting the circuit board holder 16 into the field device housing 12.In this case, the locking lug 60a is pressed inwards, ie in the direction of the at least one printed circuit board 15a, by the inner contour of the field device housing, which closely fits the actual outer contour of the printed circuit board holder 16, so that the locking hook 60e engages in a corresponding recess as a counter-locking mechanism 60b of the printed circuit board, as shown in Fig. 4.

[0043] In the embodiments shown in Figs. 3 and 4, only one latching and one counter-latching mechanism 60a, 60b is shown. Nevertheless, both the circuit board holder 16 and the circuit board 15a can have multiple latching and counter-latching mechanisms.

[0044] Counter-locking mechanisms 60a, 60b. In particular, the illustrated circuit board holder 16 can have two locking mechanisms 60a per circuit board 15a, 15b, which are preferably arranged diametrically opposite one another. The circuit board 15a can accordingly have two counter-locking mechanisms 60b, which are located on a circuit board edge 60c located opposite the inserted end of the circuit board. Furthermore, several circuit boards 15a, 15b can also be held in the circuit board holder by appropriately designed locking or

[0045] Counter-locking mechanisms 60a, 60b are held.

[0046] List of reference symbols

[0047] 10 Field device in automation technology

[0048] 11 Viewing window

[0049] 12 field device housings

[0050] 13 Interior

[0051] 14 Sensor and / or actuator element

[0052] 15 Field device electronics

[0053] 15a-15c circuit boards

[0054] 15d plug and mating connectors

[0055] 15e connector

[0056] 16 PCB holders

[0057] 16a Side guide rails of the PCB holder

[0058] 16b Snap-in or locking mechanism according to the state of the art

[0059] 16c Arm of the circuit board holder according to the prior art

[0060] 16d Nose of the PCB holder according to the prior art

[0061] 17 Rotationally symmetrical sub-area

[0062] 18 Housing opening

[0063] 19 Display

[0064] 20 Connection electronics

[0065] 21 field contact plugs

[0066] 22 mating connectors of the connection electronics

[0067] 24 Electronic components, e.g. for EMC and / or explosion protection measures

[0068] 25 Additional circuit board

[0069] 26 Plug sleeve for field contact plug

[0070] 27 Potting compound

[0071] 27a Predetermined potting height up to which the circuit board in the circuit board holder is potted with the potting compound

[0072] 28 Process connection

[0073] 30 display frames

[0074] 40 display holders

[0075] 50 carrier board or circuit board

[0076] B Detailed view of the locking and counter-locking mechanism

[0077] 60a Snap-in mechanism of the circuit board holder, especially the locking lug

[0078] 60b Counter-locking mechanism of the circuit board, especially recess

[0079] 60c PCB edge where the locking mechanism is formed

[0080] 60d Flexible arm of the PCB locking tab

[0081] 60e locking hook of the locking lug of the circuit board

Claims

A device for automation technology (10), comprising: a field device housing (12); field device electronics (15) arranged in the field device housing with at least one printed circuit board (15a); a printed circuit board holder (16) arranged in the field device housing (12) for holding the at least one printed circuit board (15a), wherein the printed circuit board holder (16) is adapted with a circumferential outer contour of a wall at least in a partial section (17) to an inner contour of the field device housing (12) such that the outer contour of the printed circuit board holder (16) lies substantially flush with the inner contour of the field device housing (12), wherein the printed circuit board holder (16) has at least one latching mechanism (60a) in the region of the partial section (17) for robustly fastening the at least one printed circuit board (15a),wherein the at least one printed circuit board (15a) has at least one counter-locking mechanism (60b) corresponding to the locking mechanism of the printed circuit board holder (60a), wherein the locking mechanism (60a) is designed in the form of a locking lug introduced from the wall or into the wall, wherein the locking lug is designed to be flexible such that, in a non-locked state, in which the printed circuit board holder (16) is not inserted into the field device housing (12) at least with the partial section, it protrudes beyond the actual outer contour of the wall of the printed circuit board holder (16) and, in a locked state, in which the printed circuit board holder (16) is inserted into the field device housing (12) at least with the partial section, it can be or has moved in the direction of the at least one printed circuit board (15a) in order to lock into the counter-locking mechanism (60b),wherein the at least one circuit board (15a) is inserted into the circuit board holder (16) and the circuit board holder (16) is inserted at least with the partial section into the field device housing (12), so that the latching and counter-latching mechanisms (60a, 60b) latch into one another and the circuit board holder (16) holds the at least one circuit board, wherein the at least one circuit board (15a) is potted in the circuit board holder (16) up to a predetermined potting height (27a) with a potting compound (27), wherein the latching and counter-latching mechanisms (60a, 60b) are designed in or on the circuit board holder (16) or the at least one circuit board (15a) in such a way that the latching and counter-latching mechanisms (60b, 60a) are formed above the potting height, so that the latching and counter-latching mechanisms (60a, 60b) are not potted is., 2. Field device of automation technology according to claim 1, wherein the locking lug has an elongated arm (60d) prepared from the wall of the circuit board holder (16) and a locking hook (60e) located at one end of the elongated arm.

3. Field device according to one or more of the preceding claims, wherein the at least one printed circuit board (15a) has at least one recess into which the locking lug can engage in the locked state.

4. Field device according to one or more of the preceding claims, wherein the circuit board holder (16) has at least two latching mechanisms (60a) for the robust fastening of the at least one circuit board (15a) and the at least one circuit board (15a) has at least two counter-latching mechanisms (60b) corresponding to the respective latching mechanism of the circuit board holder (60a).

5. Field device according to the preceding claim, wherein the at least two latching mechanisms (60a) of the circuit board holder (16) are arranged diametrically to one another and the at least two counter-latching mechanisms (60b) of the at least one circuit board (15a) are formed diametrically on a circuit board edge (60c) of the at least one circuit board (15a), wherein the circuit board edge is located at an end of the circuit board (15a) opposite the end inserted into the circuit board holder (60c).

6. Field device according to one or more of the preceding claims, wherein the circuit board holder (16) is designed in the form of a cup.

7. Field device according to one or more of the preceding claims, wherein the circuit board holder (16) is designed such that it has no opening in the outer contour up to the predetermined potting height (27a).

8. A method for producing a field device of automation technology according to at least one of the preceding claims, comprising the following method steps: Providing the field device housing (12); Providing the field device electronics (15) with the at least one circuit board (15a); Providing the circuit board holder (16) for holding the at least one circuit board (15a); Inserting the at least one printed circuit board (15a) into the printed circuit board holder (16) in the non-latched state, in which the printed circuit board holder (16) at least with the partial section is not yet inserted into the field device housing (12); Inserting the circuit board holder (16) at least with the partial section into the field device housing (12) so that the locking lug moves in the direction of the at least one circuit board and, in the locked state, engages in the counter-locking mechanism.

9. Method according to the preceding claim, wherein the at least one circuit board (15a) is potted in the circuit board holder (16) up to the predetermined potting height with a potting compound (27) before the circuit board holder (16) is inserted into the field device housing (12).

10. The method according to claim 8, wherein the at least one circuit board (15a) is potted with a potting compound (27) in the circuit board holder (16) up to the predetermined potting height (27a) after the circuit board holder (16) is inserted into the field device housing (12).

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