Automated field device

Abstract

The invention relates to an automation field device (10), comprising: a field device housing (12); -a field device electronics unit (15) comprising at least one printed circuit board (15a); -a PCB holder (16) arranged inside the field device housing for fastening the PCB (15a), said PCB holder (16) being provided with engagement means (60a) for reactively fastening the PCB (15a), the PCB (15a) being provided with at least one counter-engagement means (60b) corresponding to the engagement means on the PCB holder, the engagement means (60a) being in the form of a latch protruding from or introduced into the wall, the latch being flexible, and the counter-engagement means (60b) being provided with at least one counter-engagement means (60b) corresponding to the engagement means on the PCB holder. The at least one PCB holder is configured such that, in a non-latched state in which at least a portion of the PCB holder is not introduced into the field device housing, the latch protrudes beyond the actual outer contour of the wall of the PCB holder, and, in a latched state in which at least a 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 engage with the reverse engagement mechanism.

Description

Technical Field

[0001] The invention relates to a field device for automation technology and to a method for producing such a field device for automation technology. Background Art

[0002] Field devices for industrial plants are known in the prior art. Field devices are commonly used in process automation technology and manufacturing automation technology. In principle, field devices are all devices that are used near the process and deliver or process process-related information. Field devices are used to record and / or influence process variables. The services used to record process variables are measuring devices or sensors. This is used, for example, for pressure and temperature measurement, conductivity measurement, flow measurement, etc., and records the corresponding process variables, pressure, temperature, conductivity, pH value, fill level, flow rate, etc. Actuators are used to influence process variables. For example, pumps or valves can influence the flow of liquid in a pipe or pipeline or the fill level in a container. In addition to the above-mentioned measuring devices and actuators, field devices are also called remote I / O, radio adapters and devices that are usually arranged at the field level.

[0003] A large number of such field devices are manufactured and sold by the company Endress+Hauser.

[0004] Such field devices, in particular, are in at least occasional and / or at least partial contact with a process medium—a sensor element—which generates a signal that is dependent on a process variable. Furthermore, these devices have an electronics unit arranged in a housing, which processes and / or forwards the signals, in particular electrical and / or electronic signals, generated by the sensor element. Typically, the electronics unit includes a plurality of circuit boards on which components are arranged. The circuit boards are typically arranged and mechanically secured in a circuit board holder. Figure 1 A circuit board holder such as that known in the prior art is shown. In the prior art, mechanical fastening of circuit boards typically involves providing a releasable engagement or securing mechanism located at the bottom of the circuit board holder for securing the circuit board to the circuit board holder. The placement of the engagement or securing mechanism at the bottom of the circuit board holder allows for removal from the mold. The engagement or securing mechanism is typically implemented as follows: an elongated, flexible arm extends from a side wall of the circuit board holder and has a nose on one side facing the central axis of the circuit board holder that engages a corresponding recess in the mounted circuit board.

[0005] Due to the embodiment of the engaging or securing mechanism and its arrangement near the bottom, the circuit board holder is penetrated at its outward-facing side wall and is therefore no longer sealed there. This lack of sealing means that during the potting process, when pouring potting compound (e.g., silicone gel) onto the circuit board mounted in the circuit board holder, it is impossible to pour the potting compound onto the circuit board holder before it is introduced into the housing (pre-assembled component of the circuit board holder) of the field device, because the potting compound is not retained within the circuit board holder. Therefore, before pouring, the circuit board holder must first be placed into the housing, as the housing then serves as an outer mold for the circuit board holder, at least partially preventing the potting compound from escaping. To ensure that the potting compound does not leak into unintended areas of the housing during pouring onto the circuit board holder mounted in the housing, additional sealing measures are required within the housing and / or around the circuit board holder used for pouring. These additional measures, in turn, lead to increased manufacturing costs and effort. Furthermore, the greater the amount of potting compound poured into the housing, the longer it takes to cure. Summary of the Invention

[0006] It is therefore an object of the present invention to overcome these problems.

[0007] This object is achieved according to the invention by a field device for automation technology according to claim 1 and a method according to claim 8 .

[0008] The automation field device of the present invention comprises:

[0009] - Field device housing;

[0010] a field device electronics unit arranged in the field device housing and having at least one printed circuit board;

[0011] - A circuit board holder arranged in a field device housing, for holding at least one circuit board, wherein the circuit board holder having a surrounding outer contour of the wall is adapted to the inner contour of the field device housing at least in a subregion so that the outer contour of the circuit board holder rests essentially flush against the inner contour of the field device housing, wherein the circuit board holder has at least one engagement mechanism in the subregion for resistively fastening the at least one circuit board, wherein the at least one circuit board has at least one counter-engagement mechanism corresponding to the engagement mechanism of the circuit board holder, wherein the engagement mechanism is embodied in the form of a latch formed by or arranged in the wall, wherein the latch is embodied flexibly so that: in a non-engaged state, the latch extends out from the outer contour of the wall of the circuit board holder, and in the non-engaged state the circuit board holder is not fully mounted in the field device housing at least with respect to the subregion. The invention relates to a field device housing, and in an engaged state, the latch has been moved in the direction of the at least one circuit board so as to engage with the counter-engagement mechanism, in which the circuit board holder is mounted in the field device housing at least with respect to a sub-area, wherein the at least one circuit board is mounted in the circuit board holder, and the circuit board holder is mounted in the field device housing at least with respect to a sub-area, so that the engagement mechanism and the counter-engagement mechanism engage with each other and the circuit board holder holds the at least one circuit board, wherein the at least one circuit board is potted in the circuit board holder with a potting compound to a predetermined potting compound height, wherein the engagement mechanism and the counter-engagement mechanism are embodied in or on the circuit board holder and the at least one circuit board in such a way that the engagement mechanism and the counter-engagement mechanism are located above the potting compound height so that the engagement mechanism and the counter-engagement mechanism are not potted.

[0012] An advantageous embodiment of the inventive automation field device can provide that the latch comprises an elongated arm prepared from a wall of the circuit board holder and an engaging catch at the end of the elongated arm.

[0013] Another advantageous embodiment of the automation field device according to the invention can provide that the at least one circuit board (15a) has at least one recess in which the latch can engage in the engaged state.

[0014] Furthermore, another advantageous embodiment of the automation field device of the present invention can provide that the circuit board holder has at least two engagement mechanisms for resistively fastening at least one circuit board, and the at least one circuit board has at least two counter-engagement mechanisms corresponding to the engagement mechanisms of the circuit board holder. In particular, this embodiment can provide that the at least two engagement mechanisms of the circuit board holder are arranged diametrically opposite one another, and the at least two counter-engagement mechanisms of the at least one circuit board are formed diametrically opposite one another on a circuit board edge of the at least one circuit board, wherein the circuit board edge is located at the rear end of the circuit board mounted in the circuit board holder.

[0015] A further advantageous embodiment of the inventive automation field device can provide that the circuit board holder has the form of a cup.

[0016] A further advantageous embodiment of the inventive automation field device can provide that the circuit board holder is embodied such that up to a predetermined potting compound height the circuit board holder has no openings in its outer contour.

[0017] The present invention further relates to a method for producing an automation field device according to at least one of the above-described embodiments, comprising the following method steps:

[0018] - Provide field device housing;

[0019] - providing the field device electronics unit with at least one circuit board;

[0020] - providing a circuit board holder for holding at least one circuit board;

[0021] - mounting the at least one circuit board in the circuit board holder in a non-engaged state, in which the circuit board holder has not yet been mounted in the field device housing at least with respect to a subregion; and

[0022] The circuit board holder is mounted in the field device housing at least with respect to a subregion, so that the latch moves in the direction of the at least one circuit board and engages the counter-engagement mechanism in the engaged state.

[0023] An advantageous form of embodiment of the method of the invention can provide that, before the circuit board holder is mounted in the field device housing, at least one circuit board is potted with potting compound in the circuit board holder to a predetermined potting compound height.

[0024] An alternative form of embodiment of the method of the invention can provide that, after the circuit board holder has been mounted in the field device housing, at least one circuit board is potted in the circuit board holder with potting compound to a predetermined potting compound height. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will now be explained in more detail based on the accompanying drawings, which are shown below:

[0026] Figure 1 A circuit board holder known from the prior art, such as is typically used in field devices in automation technology, is shown.

[0027] Figure 2 shows, by way of example, a sectional view of a field device of automation technology,

[0028] Figure 3A cross-sectional view of a circuit board holder provided for use in a field device in automation technology is shown, wherein a circuit board is held in the circuit board holder by means of an engagement mechanism and a counter mechanism, wherein in the position shown the engagement mechanism is not yet engaged in the counter-engagement mechanism (non-engaged state), and

[0029] Figure 4 A sectional view of a circuit board holder provided for use in a field device in automation technology is shown, wherein a circuit board located in the circuit board holder is held in the circuit board holder by means of engagement mechanisms and counter-engagement mechanisms (engaged state). DETAILED DESCRIPTION

[0030] Figure 1 A circuit board holder 16 known from the prior art is shown, such as is currently commonly used in field devices 10 for automation technology. The circuit board holder 16 comprises guide rails 16a for receiving a laterally positioned circuit board. In addition, the circuit board holder 16 comprises a releasable engagement mechanism or fixing mechanism 16b in the lower region, such as has already been described above. Figure 1 The circuit board holder 16 (not separately shown) can be mechanically fastened in the circuit board holder 16 via this releasable engagement or fixing mechanism. In this case, the engagement or fixing mechanism 16b is implemented by fabricating two mutually opposing elongated arms 16c from the side walls of the circuit board holder 16 during production, so that the arms 16c have a certain degree of flexibility. On the side of each arm 16c facing the central axis of the circuit board holder, the circuit board holder 16 further includes a nose 16d that engages a corresponding recess of an inserted circuit board.

[0031] This circuit board holder 16 has now been placed in the field device housing 12 and then filled with potting compound 27. By placing the circuit board holder 16 in the housing 12, the "unsealed areas" (the wall openings created by the preparation arms) are at least partially sealed by the closely adjoining housing walls, so that the potting compound 27 is retained in the circuit board holder 16. In order to prevent the potting compound 27 from escaping into unsuitable areas of the field device housing 12, for example in the direction of the electronics unit, which is further arranged below the housing 12 and serves to process and / or forward the signals generated by the sensor element 14, further sealing measures may be necessary in certain cases.

[0032] Figure 2 By way of example, a cross-section of an automation technology field device 10 is shown. The field device 10 comprises a field device housing 12 surrounding an interior space 13. The field device housing 12 comprises an at least partially rotationally symmetrical subregion 17, in which a circuit board holder 16 is positioned, as will be described in more detail below.

[0033] Furthermore, the field device 10 comprises a sensor assembly, which is arranged at the end of the field device housing 12 and has a sensor element and / or actuator element 14 for setting and / or recording a process variable, and a process connection 28. The process connection 28 can be of the threaded type or a screw-on or clampable flange.

[0034] The sensor element and / or actuator element 14 in this example of an embodiment comprises a fill level sensor element for recording the fill level as a process variable. However, the invention is not limited to this type or specific embodiment of a sensor element and / or actuator element, but can in principle be applied to any kind of sensor or actuator.

[0035] In the interior 13 of the field device housing, for providing and / or conditioning sensor and / or actuator signals, there is a field device electronics unit 15 . The field device electronics unit 15 thus operates the sensor element and / or actuator element 14 .

[0036] In this example of an embodiment, the field device electronics unit comprises three circuit boards 15a, 15b, 15c. These are electrically connected via corresponding plug connectors and counter-plug connectors 15d. These can be embodied as rigid as well as flexible connectors. Moreover, the positions of the plug connectors and counter-plug connectors can be reversed.

[0037] The field device electronics unit 15 also includes a fourth circuit board 25, which serves as the interface electronics unit 20 and has a field contact plug 21, which is arranged on the longitudinal axis of the circuit board 25 on an edge of the circuit board and soldered to the edge. Data, particularly measured values, and / or energy can be transferred between the field device 10 and external units (e.g., a superordinated unit or other field devices) via the field contact plug 21. The field contact plug 21 can particularly be a plug / socket connector, such as an M12 connector. To guide the field contact plug outward, the field device housing 12 includes a correspondingly formed housing opening 18. The fourth circuit board 25 can also be electrically connected to one of the other circuit boards via the plug connector 15e and the counter-plug connector 22. Furthermore, electronic components 24 for EMC and / or explosion protection measures can be incorporated into the circuit board.

[0038] At the upper end of the field device 10, the field device housing 12 has a display 19 for displaying and / or interacting with the field device 10. The display can have capacitive keys for interaction. This can be achieved, for example, by corresponding capacitive membranes. To meet hygiene requirements, the display can be arranged within the field of view, and the touch screen 11 is integrated into the housing 12 in the interior space 13 of the field device. In order to have the best possible view and readability of the information on the display 19 placed behind the viewing screen 11 and / or frictionless operation of the capacitive keys, the display 19 should contact the rear side of the viewing screen and touch screen 11 as much as possible and / or evenly. For example, a display frame 30 can be used for this, which on the one hand receives the display and on the other hand is placed accordingly behind the viewing screen and touch screen 11.

[0039] The circuit boards 15a, 15b, 15c, 25 of the field device electronics unit 15 are at least partially arranged and mechanically secured in the circuit board holder 16. The circuit board holder is embodied with its outer contour such that it lies at least partially flush on the inner surface of the rotationally symmetrical region of the housing.

[0040] exist Figure 2 In the example of embodiment shown, the circuit board holder 16 has a cup-like shape. In order to place the circuit board, the circuit board holder 16 can have an inner transverse guide 16a, also as shown in FIG. Figure 1 As shown. In this case, two, preferably diametrically arranged, guide rails 16a can be provided for receiving the circuit board. In addition, the circuit board holder 16 comprises an engagement mechanism 60a for resistively fastening the circuit board 15a. The circuit board 15a in turn comprises a corresponding counter-engagement mechanism 60b. For each circuit board to be mounted in the circuit board holder, there is a matching engagement mechanism and a counter-engagement mechanism. Figure 2In the example of the embodiment shown, the positions of the engagement and counter-engagement mechanisms are shown by way of example only as boxes with reference numerals 60a and 60b. The engagement and counter-engagement mechanisms are arranged in the upper region of the circuit board holder and circuit board, i.e., at the end facing away from the sensor element and / or actuator element 14. Thus, by way of example, circuit board 15a is arranged in the circuit board holder, which is releasably retained in circuit board holder 16 by means of engagement mechanism 60a and counter-engagement mechanism 60b. Circuit board 15a is potted in circuit board holder 16 with potting compound 27 to a predetermined potting compound height 27a. The potting compound used can be, for example, SILGel silicone gel. Typically, potting compound height 27a is determined so that the potting compound fills approximately half to two-thirds of the volume of circuit board holder 16. Engagement mechanism 60a and counter-engagement mechanism 60b are then arranged in the non-potted region of circuit board holder 16 and circuit board 15a. Preferably, the circuit board holder (16) is formed in such a way that up to a predetermined potting compound height 27a, it has no openings in the outer contour so that when potted with potting compound, the potting compound cannot leak from the circuit board holder. In addition, the circuit boards 15b and 15c are potted in the circuit board holder with the potting compound 27.

[0041] In this case, the potting can be done before the circuit board holder is installed in the field device housing, so that the circuit board holder with the circuit board located therein can be manufactured as a preassembled module. Alternatively, the circuit board holder can also be potted with a potting compound after being installed in the field device housing.

[0042] To describe the engaging mechanism 60a and the anti-engaging mechanism 60b in more detail, Figure 3 By way of example, a cross-sectional view of a circuit board holder 16 is shown which is provided for use in an automation field device 10 and has a circuit board 15 a located therein and which is to be held in the circuit board holder 16 by means of an engagement mechanism 60 a and a counter-engagement mechanism 60 b . Figure 3 1 shows a non-engaged state in which the circuit board holder 16 is not completely mounted in the field device housing 12 at least with respect to a subregion and the engagement mechanism 60a and the counter-engagement mechanism 60b are not yet engaged with one another. Figure 4 The engaged state is shown, in which the circuit board holder 16 is mounted in the field device housing 12 at least with respect to a subregion, and the engagement mechanism 60 a and the counter-engagement mechanism 60 b are engaged with one another.

[0043] from Figure 3It is clear that the engagement mechanism 60a is embodied in the form of a latch formed by or arranged in a wall, and the counter-engagement mechanism 60b of the at least one circuit board 15a is embodied in the form of a recess in which the latch can engage in the engaged state. The engagement mechanism 60a can be manufactured, for example, by a corresponding injection molding method during the production of the circuit board holder 16. The counter-engagement mechanism 60b can be formed, for example, by milling a corresponding outer contour of the circuit board 15a.

[0044] The latch 60a in turn comprises a flexible elongated arm 60d connected at one end to the wall of the circuit board holder 16 and an engaging catch 60e arranged at the other end of the elongated arm. Figure 3 In the non-engaged state shown, it protrudes outwards from the outer contour of the wall of the circuit board holder 16. In particular, the latch 60a is embodied such that the engaging catch 60e of the latch in this state is outside the outer contour, so that the engaging catch 60e is still not engaged in the counter-engagement mechanism 60b of the already installed circuit board 15a. Starting from this state, the flexible latch 60a can be brought into the engaged state by completely introducing the circuit board holder 16 into the field device housing 12. In this case, the latch 60a is pressed inwards (i.e. in the direction of the at least one circuit board 15a) by the inner contour of the field device housing, which is closely adjacent to the outer contour of the circuit board holder 16, so that the engaging catch 60e engages in a corresponding recess of the counter-engagement mechanism 60b serving as the circuit board. This Figure 4 Shown in.

[0045] exist Figure 3 and Figure 4 In the example of the illustrated embodiment, only one pair of engagement mechanisms 60a and counter-engagement mechanisms 60b is shown in each case. In practice, the circuit board holder 16 and the circuit board 15a can have multiple engagement mechanisms 60a and counter-engagement mechanisms 60b. In particular, the circuit board holder 16 shown can have two engagement mechanisms 60a for each circuit board 15a, 15b, which are preferably arranged opposite each other. The circuit board 15a can correspondingly have two counter-engagement mechanisms 60b, which are located at the rear circuit board edge 60c of the installed circuit board. In addition, multiple circuit boards 15a, 15b can also be held in the circuit board holder by correspondingly embodied engagement mechanisms 60a and counter-engagement mechanisms 60b.

[0046] Reference Signs List

[0047] 10 Field devices for automation technology

[0048] 11 Viewing screen

[0049] 12 Field device housing

[0050] 13 Interior Space

[0051] 14 sensor element and / or actuator element

[0052] 15 Field device electronics unit

[0053] 15a-15c circuit boards

[0054] 15d plug connector and reverse plug connector

[0055] 15e plug connector

[0056] 16 Circuit board holder

[0057] 16a Lateral guides for circuit board holder

[0058] 16b Jointing mechanism or fixing mechanism according to the prior art

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

[0060] 16d Nose of a circuit board holder according to the prior art

[0061] 17 Rotationally symmetric subregions

[0062] 18 Shell opening

[0063] 19 Display

[0064] 20 Interface electronics unit

[0065] 21 Field contact plug

[0066] 22 Reverse plug connector for interface electronics unit

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

[0068] 25 Other circuit boards

[0069] 26 Plug guide for field access plugs

[0070] 27 Potting compound

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

[0072] 28 Process connections

[0073] 30 Display Frame

[0074] 40 Monitor Holder

[0075] 50 Support plate or circuit board

[0076] B Detailed view of the engagement and anti-engagement mechanisms

[0077] 60a Engagement mechanism of circuit board holder, particularly latch

[0078] 60b The anti-engagement mechanism of the circuit board, especially the recess

[0079] 60c Circuit board edge forming the engagement mechanism

[0080] 60d Flexible arm of the latch

[0081] 60e latch engagement tab

Claims

1. An automated field device (10), comprising: - Field device housing (12); - a field device electronics unit (15) arranged in the field device housing, the field device electronics unit having at least one printed circuit board (15a); - a circuit board holder (16) arranged in the field device housing (12), the circuit board holder being used to hold the at least one circuit board (15a), wherein the circuit board holder (16) having a peripheral outer contour of the wall is adapted to the inner contour of the field device housing (12) at least in a sub-region (17) so that the outer contour of the circuit board holder (16) rests substantially flush against the inner contour of the field device housing (12), wherein the circuit board holder (16) has at least one engagement mechanism (60a) in the sub-region (17) for resistively fastening the circuit board to the field device housing (12). The at least one circuit board (15a), wherein the at least one circuit board (15a) has at least one counter-engagement mechanism (60b) corresponding to the engagement mechanism (60a) of the circuit board holder, wherein the engagement mechanism (60a) is embodied in the form of a latch formed by the wall or arranged in the wall, wherein the latch is embodied flexibly so that: in a non-engaged state, the latch extends out from the outer contour of the wall of the circuit board holder (16), in which case the circuit board holder (16) is not completely mounted on the field device housing (16) at least with respect to the sub-region. 2), and in an engaged state, the latch has moved in the direction of the at least one circuit board (15a) so as to engage with the counter-engagement mechanism (60b), in which case the circuit board holder (16) is mounted in the field device housing (12) at least with respect to the sub-area, wherein the at least one circuit board (15a) is mounted in the circuit board holder (16) and the circuit board holder (16) is mounted in the field device housing (12) at least with respect to the sub-area, so that the engagement mechanism and the counter-engagement mechanism (60a, 60b) engage with each other and the 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) with a potting compound (27) to reach a predetermined potting compound height (27a), wherein the engaging mechanism and the anti-engaging mechanism (60a, 60b) are embodied in or on the circuit board holder (16) and the at least one circuit board (15a) in such a manner that the engaging mechanism and the anti-engaging mechanism (60b, 60a) are located above the potting compound height, so that the engaging mechanism and the anti-engaging mechanism (60a, 60b) are not potted.

2. The automation field device according to claim 1, wherein: The latch comprises an elongated arm (60d) prepared from the wall of the circuit board holder (16) and an engaging catch (60e) at the end of the elongated arm.

3. The field device according to one or more of the preceding claims, wherein: The at least one circuit board (15a) has at least one recess, in which the latch can engage in the engaged state.

4. The field device according to one or more of the preceding claims, wherein: The circuit board holder (16) has at least two engagement mechanisms (60a) for resistively fastening the at least one circuit board (15a), and the at least one circuit board (15a) has at least two counter-engagement mechanisms (60b) corresponding to the engagement mechanisms (60a) of the circuit board holder.

5. Field device according to the preceding claim, wherein The at least two engagement mechanisms (60a) of the circuit board holder (16) are arranged diametrically opposite to each other, and the at least two counter-engagement mechanisms (60b) of the at least one circuit board (15a) are formed diametrically opposite to each other on a circuit board edge (60c) of the at least one circuit board (15a), wherein the circuit board edge (60c) is located at the rear end of the circuit board (15a) mounted in the circuit board holder.

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

7. Field device according to one or more of the preceding claims, wherein: The circuit board holder (16) is embodied such that up to the predetermined potting compound height (27a) the circuit board holder has no openings in its outer contour.

8. A method for producing an automation field device 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 unit (15) with the at least one circuit board (15a); - providing said circuit board holder (16) for holding said at least one circuit board (15a); - installing the at least one circuit board (15a) in the circuit board holder (16) in the non-engaged state, in which the circuit board holder (16) has not yet been installed in the field device housing (12) at least with respect to the sub-region; as well as - The circuit board holder (16) is mounted in the field device housing (12) at least with respect to the sub-region, so that the latch moves in the direction of the at least one circuit board and engages the counter-engagement mechanism in the engaged state.

9. The method according to the preceding claim, wherein: Prior to installing the circuit board holder (16) in the field device housing (12), the at least one circuit board (15a) is potted in the circuit board holder (16) with a potting compound (27) to the predetermined potting compound height.

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

Images