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) arranged in the field device housing and comprising at least one printed circuit board (15a); -a PCB holder (16) arranged inside the field device housing for fixing the at least one PCB (15a), said PCB holder (16) being provided with at least one engagement means (60a) for the resistant fastening of the PCB (15a), the at least one PCB (15a) being provided with a counter-engagement means (60b) corresponding to the engagement means on the PCB holder, the engagement means (60a) on the PCB holder (16) have a recess in a portion of the outer contour of the PCB holder (16), and the counter-engagement means (60b) on the at least one PCB (15a) have at least one engagement nose, the recess and the engagement nose being adapted to each other such that the engagement nose can engage in the recess, the engagement mechanism and the reverse engagement mechanism (60b, 60a) are formed above a potting level to which the PCB holder is potted with the potting compound such that the engagement mechanism and the reverse engagement mechanism (60a, 60b) are not potted.

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] Known from the prior art are field devices used in industrial plants. In process automation technology and in manufacturing automation technology, field devices are often applied. Field devices are in principle all devices that are applied near the process and deliver or process process-related information. Field devices are used to register and / or influence process variables. For registering 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, etc. For influencing process variables are actuators. This is, for example, a pump or a valve that can affect the flow of a liquid in a pipe or pipeline or the fill level in a container. In addition to the measuring devices and actuators mentioned above, also referred to as field devices are remote I / Os, radio adapters, and are generally devices arranged at the field level.

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

[0004] Such field devices are in particular at least sometimes and / or at least partially in contact with a process medium, a sensor element for generating a signal that is dependent on a process variable. In addition, these devices have an electronics unit arranged in a housing, wherein the electronics unit is used to process and / or forward the signals, in particular electrical and / or electronic signals, generated by the sensor unit. Typically, the electronics unit comprises a plurality of circuit boards on which components are arranged. The circuit boards are usually arranged and mechanically fastened in a circuit board holder. Figure 1 Such a circuit board holder is shown, such as known in the prior art. In the prior art, the current mechanical fastening of circuit boards usually provides a releasable engagement or fixing mechanism at the bottom of the circuit board holder for fastening the circuit board to the circuit board holder. The engagement or fixing mechanism is arranged at the bottom of the circuit board holder so that it can be removed from the mold. The engagement or fixing mechanism is usually implemented in such a way that an elongated flexible arm extends from the side wall of the circuit board holder and has a nose on the side facing the central axis of the circuit board holder, which nose engages in a corresponding recess of the installed circuit board.

[0005] By the embodiment of the engagement or fixing mechanism and the bottom close arrangement, the circuit board holder is penetrated at its side wall facing outward, and therefore it is no longer sealed there. The lack of this seal means that in the potting process, when the circuit board installed in the circuit board holder is cast with a potting compound (e.g., silicone gel), it is impossible to cast on the circuit board holder before being introduced into the housing of the field device (pre-assembly of the circuit board holder), because the potting compound is not retained in the circuit board holder. For this reason, before casting, the circuit board holder needs to be first introduced into the housing, because then the housing can be used as an outer mold of the circuit board holder, thereby at least partially preventing the escape of the potting compound. In order to ensure that the potting compound does not leak into the unexpected area of ​​the housing during its casting on the circuit board holder installed in the housing, additional sealing measures are required in the housing and / or around the circuit board holder for casting. These additional measures then lead to an increase in manufacturing costs and workload. In addition, the potting mixture requires more time to solidify, the more the amount of potting compound cast into the housing. 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 7 .

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

[0009] - Field device housing;

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

[0011] - A circuit board holder arranged in a field device housing, the circuit board holder being used to hold at least one circuit board of an electronic unit of the field device, wherein the circuit board holder having a surrounding outer contour 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 a subregion for resistively fastening the at least one circuit board, wherein the at least one circuit board has a counter-engagement mechanism corresponding to the engagement mechanism of the circuit board holder, wherein the engagement mechanism of the circuit board holder has a recess in a subregion of the outer contour of the circuit board holder , and the anti-engaging mechanism of at least one circuit board has at least one engaging nose, wherein the recess and the engaging nose are adapted to each other so that the engaging nose can engage in the recess, wherein at least one circuit board is installed in a circuit board holder, and due to the engagement of the engaging mechanism and the anti-engaging mechanism, 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 to reach a predetermined potting compound height, wherein the engaging mechanism and the anti-engaging mechanism are embodied in or on the circuit board holder and the at least one circuit board so that the engaging mechanism and the anti-engaging mechanism are located above the potting compound height so that the engaging mechanism and the anti-engaging mechanism are not potted.

[0012] An advantageous embodiment of the automation field device of the invention can provide that the circuit board holder is embodied in the form of a cup.

[0013] A further advantageous embodiment of the inventive automation field device can provide that, in a field device as defined above, the circuit board holder is embodied such that up to a predetermined potting compound height, it has no openings in the outer contour.

[0014] Furthermore, another advantageous embodiment of the automation field device of the invention can provide that at least one circuit board has at least two engagement noses, which are preferably formed on opposite sides of the end of at least one circuit board mounted in the circuit board holder. In particular, an embodiment can provide that the at least two engagement noses are embodied such that the circuit board holder is deformed elliptically for mounting the circuit board in the circuit board holder.

[0015] A further advantageous embodiment of the inventive automation field device can provide that two engagement noses are formed diametrically opposite on a circuit board edge of at least one circuit board, wherein the circuit board edges are located at opposite ends of the circuit board mounted in the circuit board holder.

[0016] The invention also 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:

[0017] - Provide field equipment housing;

[0018] - providing the field device electronics unit with at least one circuit board;

[0019] - providing a circuit board holder for holding at least one circuit board;

[0020] - mounting at least one circuit board in the circuit board holder such that the engagement means and the counter-engagement means engage and thereby mechanically secure the circuit board in the circuit board holder; and

[0021] - Install the circuit board holder in the field device housing.

[0022] An advantageous form of embodiment of the method of the invention can provide that at least one circuit board is potted in the circuit board holder with a potting compound to a predetermined potting compound height before the circuit board holder is mounted in the field device housing.

[0023] 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, the at least one circuit board is potted in the circuit board holder with a potting compound to a predetermined potting compound height. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will now be explained in more detail based on the accompanying drawings, which are as follows:

[0025] Figure 1 A circuit board holder known from the prior art is shown, such as is usually used in field devices in automation technology.

[0026] Figure 2 A cross-sectional view of a field device of automation technology is shown as an example.

[0027] Figure 3 A 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 engagement mechanisms and counter-engagement mechanisms, wherein one set of engagement mechanisms and counter-engagement mechanisms is located in area B, and

[0028] Figure 4 A detailed view of a region B of the circuit board holder and the circuit board is shown, in which the engagement mechanism and the counter-engagement mechanism are formed. DETAILED DESCRIPTION

[0029] Figure 11 shows a circuit board holder 16 known from the prior art, such as is usually used in field devices of automation technology 10. The circuit board holder 16 comprises transversely arranged guide rails 16a for accommodating the circuit board. In addition, the circuit board holder 16 comprises, such as has already been described above, a releasable engagement or fixing mechanism 16b in the lower region, in which the circuit board (in the Figure 1 The circuit board holder 16 is a circuit board holder 16 having a central axis facing side. The circuit board holder 16 also includes a nose 16d, which engages a corresponding recess of an inserted circuit board, on the side facing the central axis of the circuit board holder of each arm 16c.

[0030] So far, this circuit board holder 16 is placed in the field device housing 12 and then filled with the potting compound 27. By placing the circuit board holder 16 in the housing 12, the "unsealed locations" (wall openings produced 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 inappropriate areas of the field device housing 12, for example, in the direction of an electronic unit which is arranged further below the housing 12 and serves to process and / or forward the signals generated by the sensor element 14, it may be necessary in given cases to implement further sealing measures in the housing 12.

[0031] Figure 2 The field device 10 comprises a field device housing 12 surrounding an interior space 13. The field device housing 12 comprises at least a cross-sectional rotationally symmetrical subregion 17 in which a circuit board holder 16 is located, as will be described in more detail below.

[0032] 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 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 screwable or clampable flange.

[0033] The sensor and / or actuator element 14 in the present example of embodiment comprises a fill level sensor element for recording the fill level as a process variable. However, the invention is not limited to the type or specific embodiment of the sensor and / or actuator element, but can in principle be applied to any kind of sensor or actuator.

[0034] 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 and / or actuator element 14 .

[0035] In this example of embodiment, the field device electronic unit comprises three circuit boards 15a, 15b, 15c. These circuit boards are electrically connected together via corresponding plug and reverse plug connectors 15d. These can be embodied as rigid as well as flexible connectors. Moreover, the positions of the plug and reverse plug connectors can be reversed.

[0036] The field device electronics unit 15 also includes a fourth circuit board 25 serving as an interface electronics unit 20 and having a field contact plug 21, which is arranged on the edge of the circuit board on the longitudinal axis of the circuit board 25 and is soldered to the circuit board 25. Through the field contact plug 21, data (especially measured values) and / or energy can be transmitted between the field device 10 and an external unit (e.g., a superordinate unit or other field device). The field contact plug 21 can be a plug / socket connector, for example, an M12 connector. In order 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. In addition, electronic components 24 for EMC- and / or explosion protection measures can be applied on the circuit board.

[0037] At the upper end of the field device 10, the field device housing 12 has a display 19 for displaying the field device 10 and / or interacting with the field device 10. The display may have a capacitive key for interaction. This can be achieved, for example, by a corresponding capacitive film. In order to meet hygiene requirements, the display may be arranged behind the viewing and touch screen 11 in the housing 12 integrated in the internal 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 and touch screen 11 as flatly and / or evenly as possible. For this, it can be, for example, a display frame 30, which accommodates the display on the one hand and is correspondingly placed behind the viewing and touch screen 11 on the other hand.

[0038] The circuit boards 15a, 15b, 15c, 25 of the field device electronics unit 15 are at least partially arranged in the circuit board holder 16 and mechanically secured thereby. The circuit board holder and its outer contour are embodied in such a way that it lies at least partially substantially flush on the inner surface of the rotationally symmetrical region of the housing.

[0039] exist Figure 2In the example of the 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 opposite guide rails 16a can be provided for accommodating the circuit board. In addition, the circuit board holder 16 includes an engagement mechanism 60a for resisting the fastening of the circuit board 15a. In turn, the circuit board 15a includes a corresponding counter-engagement mechanism 60b for this purpose. For each circuit board to be installed in the circuit board holder, there is a matching engagement mechanism and counter-engagement mechanism. Figure 2 In the example of embodiment shown, the positions of the engagement and counter-engagement mechanisms are shown only by way of example by means of the boxes with the reference numerals 60a, 60b. The engagement and counter-engagement mechanisms are arranged in the upper region of the circuit board holder and the circuit board, i.e. at the end facing away from the sensor and / or actuator element 14. Furthermore, the circuit boards 15a, 15b and 15c are potted in the circuit board holder with a potting compound 27.

[0040] Figure 3 A cross-sectional view of a circuit board holder 16 is shown by way of example for describing the engaging mechanisms 60a and the counter-engaging mechanisms 60b in more detail, wherein one set of the engaging mechanisms 60a and the counter-engaging mechanisms 60b is located in area B. Thus, by way of example, a circuit board 15a is arranged in the circuit board holder, which circuit board 15a is releasably retained in the circuit board holder 16 by means of the engaging mechanisms and the counter-engaging mechanisms 60a, 60b. The circuit board 15a is potted in the circuit board holder 16 by means of a potting compound 27 to reach a predetermined potting compound height 27a. The potting compound used may be, for example, SILGel silicone gel. Typically, the potting compound height 27a is determined in such a way that the potting compound fills approximately half to two-thirds of the volume of the circuit board holder 16. The engaging mechanisms 60a and the counter-engaging mechanisms 60b are then arranged in non-potted areas of the circuit board holder 16 and the circuit board 15a. In Figure 3 In the example of embodiment shown, the anti-engagement mechanism 60b is arranged at a circuit board edge 60c located on the trailing end of the circuit board 15a.

[0041] To this end, Figure 4 Shows Figure 3Detailed view of area "B" of the circuit board holder 16, which includes a set of engagement mechanisms 60a and counter-engagement mechanisms 60b located therein and a circuit board 15a. The counter-engagement mechanism 60b includes two engagement noses 60d, which are preferably formed on opposite ends of the circuit board edge 60c. The engagement nose 60d can be made, for example, by milling the corresponding outer contour of the circuit board 15a. The engagement mechanism 60a of the circuit board holder 16 includes a corresponding recess 60e, in which the engagement nose 60d can be engaged when the circuit board 15a is introduced or inserted. The recess 60e can be made, for example, by milling a cavity in the circuit board holder 16, or using a corresponding injection mold when the circuit board holder is produced by injection molding. In this case, the recess 60e can pass through the lateral wall of the circuit board holder 16 at this position, or alternatively, it is only a recess that does not pass through the entire lateral wall at this position. The recess 60e and the engagement nose 60d are adapted to one another so that the engagement nose of the circuit board 60d engages the recess of the circuit board holder 16 and is fastened there. Preferably, the engagement nose 60d is embodied in such a way that, in order to introduce the circuit board 15a, the circuit board holder 16 has to be slightly compressed in an oval shape until the engagement nose 60d engages the recess 60e. After the engagement nose 60d is engaged in the recess 60e, there is no longer any stress on the circuit board holder, so that, for example, in the case of a snap connection, fatigue failure of the engagement can be excluded. As a result of the engagement mechanism 60a and the counter-engagement mechanism 60b formed according to the invention, the circuit board 15a can be potted with the potting compound 27 before the circuit board holder 16 is introduced into the field device housing 12. In this way, costs and complexity can be reduced, because it is not necessary to prepare filigree arms in the side walls of the circuit board holder, such as is common in the prior art.

[0042] Reference numerals list

[0043] 10 Automation technology field equipment

[0044] 11 Watch Screen

[0045] 12 Field device housing

[0046] 13. Internal Space

[0047] 14 Sensor and / or actuator elements

[0048] 15 Field device electronics unit

[0049] 15a-15c circuit board

[0050] 15d plug connector and reverse plug connector

[0051] 15e plug connector

[0052] 16 Circuit board holder

[0053] 16a Lateral guides for circuit board holder

[0054] 16b Joining or fixing mechanism according to the prior art

[0055] 16c Arm of a circuit board holder according to the prior art

[0056] 16d Nose of a circuit board holder according to the prior art

[0057] 17 Rotationally symmetric sub-regions

[0058] 18 Shell opening

[0059] 19 Display

[0060] 20 Interface electronics unit

[0061] 21 Field contact plug

[0062] 22 Interface electronic unit reverse plug connector

[0063] 24 Electronic components, e.g. for EMC and / or Ex protection measures

[0064] 25 Another circuit board

[0065] 26 Plug and socket for field contact plug

[0066] 27 Potting compound

[0067] 27a Predetermined potting compound height of potting compound on circuit board in circuit board holder

[0068] 28 Process connection

[0069] 30 Display frame

[0070] 40 Display Holder

[0071] 50 Support plate or circuit board

[0072] B Detailed view of the engagement and anti-engagement mechanisms

[0073] 60a Engagement mechanism of the circuit board holder, in particular the engagement nose

[0074] 60b Anti-engagement mechanism of circuit board, especially recess

[0075] 60c The edge of the circuit board where the engagement mechanism is formed

[0076] 60d Circuit board joint nose

[0077] 60e Recess of circuit board holder

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, the circuit board holder being used to hold the at least one circuit board (15a) of the field device electronic unit (15), wherein the circuit board holder (16) having a surrounding outer contour 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 rests substantially flush against the inner contour of the field device housing (12), wherein the circuit board holder (16) has in the sub-region (17) at least one engagement mechanism (60a) for resistively fastening the at least one circuit board (15a), wherein the at least one circuit board (15a) has a counter-engagement mechanism (60b) corresponding to the engagement mechanism of the circuit board holder, wherein the engagement mechanism (60a) of the circuit board holder (16) has a recess in the sub-region of the outer contour of the circuit board holder (16), and the at least The anti-engaging mechanism (60b) of a circuit board (15a) has at least one engaging nose, wherein the recess and the engaging nose are adapted to each other so that the engaging nose can engage in the recess, wherein the at least one circuit board is mounted in the circuit board holder, and due to the engagement of the engaging mechanism and the anti-engaging mechanism (60a, 60b), the circuit board holder holds the at least one circuit board (15a), 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) so 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 circuit board holder (16) is embodied in the form of a cup.

3. The 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, the circuit board holder has no openings in the outer contour.

4. The field device according to one or more of the preceding claims, wherein: The at least one circuit board (15a) has at least two engaging noses, which are preferably formed on opposite sides of an end of the at least one circuit board mounted in the circuit board holder (16).

5. Field device according to the preceding claim, wherein The at least two engaging noses are embodied to deform the circuit board holder into an elliptical shape to mount the circuit board (15a) in the circuit board holder (16).

6. Field device according to one or more of the preceding claims, wherein: The two engagement noses are formed diametrically opposite each other on a circuit board edge (60c) of the at least one circuit board, wherein the circuit board edge is located at opposite ends of the circuit board mounted in the circuit board holder.

7. 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; - providing said circuit board holder (16) for holding said at least one circuit board (15a); - mounting the at least one circuit board (15a) in the circuit board holder (16) such that the engagement means and the counter-engagement means (60a, 60b) engage and thereby mechanically secure the circuit board (15a) in the circuit board holder (16); as well as - Installing the circuit board holder (16) in the field device housing (12).

8. A method according to the preceding claim, wherein: 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 before the circuit board holder is installed in the field device housing (12).

9. The method according to claim 7, wherein: After the circuit board holder (16) is mounted 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.

Images