Housing for a process automation field device, and field device

Abstract

The invention relates to a housing for a process automation field device. A fastening neck (1) has a fastening structure (11), and a cover has a corresponding fastening structure (21). The cover (2) has a base (22), a wall (23) that has the fastening structure (21), and an insert part (3). The insert part (3) has a securing structure (31) which, together with the fastening structure (21) of the cover (2), prevents the insert part (3) from falling out of the cover (2).

Description

[0001] Housing for a field device for process automation and field device

[0002] The invention relates to a housing for a field device for process automation. The invention further relates to a field device. The field device serves, for example, to determine and / or monitor process variables such as fill level, flow rate, mass flow rate, pressure, temperature, or pH value.

[0003] In modern technology, it is common practice to monitor and control processes in process plants using field devices. These field devices are therefore designed as either sensors or actuators. Sensor-type field devices typically have a housing containing electronics coupled to a suitable measuring unit. This measuring unit usually detects the process variable or a related measurement parameter. The housing is generally multi-part and can be opened multiple times. Access is typically provided via a cover.

[0004] The DE 10 2021 110 826 A1 features a housing for a field device, the two-part lid of which is connected to the housing body via a bayonet fitting. For sealing, a gasket is pressed by the lid against a stop surface on the housing.

[0005] EP 2 107 345 A1 shows a multi-part construction in which a clamping ring has recesses for insertion into a cover. During assembly, the clamping ring is twisted and, after the cover has been screwed onto a mounting neck, is subjected to an axial force to compress a spring ring and a silicone molded seal.

[0006] Covers that allow a view of, for example, a display unit located inside the housing are also known in the prior art. These so-called viewing covers have a viewing window made of glass or translucent plastic. If the cover is fitted with inserts—such as a gasket or electronic components—the sheer number of components increases the manufacturing effort. At the same time, it must be possible to open the housing during use and then securely close it again with all components in place. The inserts should therefore be secured against accidental loss. This securing can, for example, involve permanently bonding the inserts to the housing through additional processing steps. However, this can also be complex. In particular, certain material combinations of the cover and inserts can render some bonding methods unusable or only applicable with considerable effort.

[0007] The invention is based on the objective of proposing a housing with a removable lid, wherein an insert is secured against falling out of the lid.

[0008] The invention solves the problem by providing a housing for a field device for process automation, comprising a mounting neck and a lid, wherein the mounting neck has a mounting structure on an outer surface, wherein the lid has a mounting structure on an inner surface which corresponds to the mounting structure of the mounting neck and allows a reversible connection between the mounting neck and the lid, wherein the lid has a base and a wall, wherein the wall of the lid supports the mounting structure, wherein the lid has an insert, wherein the insert has a locking structure, and wherein the locking structure and the mounting structure of the lid are designed and coordinated in such a way as tothat the insert is prevented from falling out of the lid by an axial movement of the insert along a longitudinal axis of the lid in a direction away from the bottom that exceeds a predetermined dimension.

[0009] The housing features a lid that is connected to a mounting neck via corresponding fastening structures. The lid is essentially pot-shaped, comprising a base and surrounding walls. A locking mechanism on the lid prevents the insert from falling out. This locking mechanism and the lid's fastening structure interact in such a way that, beyond a certain range of motion, the axial movement of the insert is restricted. The specified maximum range of motion takes into account the possibility that a slight axial movement of the insert may be required, meaning that the insert does not necessarily have to be fixed and immobile within the lid.The insert and the lid are preferably designed to allow movement of the insert towards the bottom of the lid, at least during assembly – and thus into the lid.

[0010] The advantage of this housing is that the existing mounting structure for the lid, required to connect it to the rest of the housing, can be used to secure the insert without any modifications. Only the insert needs to be adapted so that it fulfills its intended function (e.g., sealing or securing other components) and is compatible with the lid's mounting structure.

[0011] One embodiment consists in the insert having at least one radially circumferential rim on its end face, and this radially circumferential rim is elastic with respect to a radially inward-acting force and forms the locking structure. In this embodiment, the insert has a rim that reacts elastically to radially inward-acting forces. Thus, if a lateral force is applied, the rim moves inward. If the force is removed, the rim moves back outward to its initial position. Preferably, the rim is inelastic with respect to an axially acting force, which is particularly the force acting in the direction of the bottom of the lid. In one embodiment, the rim is located on the side of the insert facing away from the bottom of the lid.

[0012] The elasticity allows the insert to be placed into the lid, especially if the lid's fastening structure is raised, meaning it projects from the lid's inner wall into the interior. When the insert is moved towards the bottom, the fastening structure generates an inward force to which the edge reacts elastically. This allows the edge to move behind the fastening structure towards the bottom of the lid. Movement of the insert out of the lid is limited to axial movement. The ring abuts the fastening structure and therefore cannot be moved further.

[0013] A further embodiment provides that the radially circumferential edge is curved at its end face in the direction of the longitudinal axis. In this embodiment, the edge has an inward curvature at its upper end, the end facing away from the insert. This also corresponds to the elastic behavior, insofar as this end moves inwards when a lateral force is applied.

[0014] One embodiment includes a radially circumferential edge having at least one interruption – and preferably several interruptions. The at least one interruption provides the elastic deformability.

[0015] In one embodiment, several breaks are present, so that the edge resembles a series of crenellations. When the insert is placed into the lid with the side opposite the edge facing forward, the crenellations spring inwards upon contact with the lid's fastening structure. Conversely, after assembly, when the insert is moved away from the base, the crenellations rest against the fastening structure, thus preventing further movement out of the lid. Therefore, a preferred embodiment consists of a radially circumferential edge designed in a crenellated manner.

[0016] One embodiment provides that the lid's fastening structure projects radially inwards. Thus, when the insert is placed into the lid, a radially inward force acts on the insert and, in particular, on its radially circumferential edge. Once the insert has axially passed the fastening structure, it is subsequently held axially out of the lid and, in particular, cannot fall out. Another embodiment relates to an alternative or supplementary variant of the implementation of the securing structure.

[0017] The design provides that an outer surface of the insert has a movement contour, and that the movement contour and the fastening structure of the lid are designed and coordinated in such a way that at least one relative locking position results between the movement contour and the fastening structure, which limits and preferably prevents at least a purely axial movement of the insert along the longitudinal axis of the lid relative to the lid.

[0018] In the aforementioned embodiment, the insert has a movement contour on its preferably radially outer surface – e.g., in the form of recesses – for the controlled movement of the insert relative to the lid. The insert is thus guided, for example, by rotational and / or axial movements, with the fastening structure engaging in the movement contour. This occurs until a locking position is reached, in which the axial movement of the insert is either completely prevented or severely restricted. This is a position created during manufacturing that then prevents the insert from falling out.

[0019] The lid's fastening structure preferably consists of a finite number of sub-structure components, which are, for example, spatially separated from one another. Thus, the fastening structure is, for instance, part of a bayonet fitting.

[0020] A supplementary embodiment provides that the movement contour and the mounting structure of the lid are designed and coordinated such that the locking position allows a rotational movement of the insert about its longitudinal axis. In this embodiment, a rotation between the insert and the lid can thus be effected to release the insert. Following this rotation, axial movement is then also possible, for example, due to the type of mounting structure. A further embodiment is such that the movement contour and the mounting structure of the lid are designed and coordinated such that the locking position allows rotational movement of the insert about its longitudinal axis with a limited axial movement of the insert along its longitudinal axis.In this design, the insert is held in the axial direction during rotation around the longitudinal axis and therefore cannot fall out of the lid.

[0021] One embodiment provides that the lid further comprises a sliding ring and a viewing window, that the bottom of the lid has an opening, that the viewing window is arranged in a receiving chamber for the insert, and that, in the case that the mounting neck and the lid are connected, the mounting neck presses against the insert via the sealing element, and the insert—preferably via the viewing window—presses the sliding ring against the bottom of the lid. In this embodiment, the lid is a so-called viewing lid, which has an opening through which it is possible to see into the housing and, preferably, of an electronic component located within the housing. The gap in the housing created by the opening is closed again by the viewing window, which is made, for example, of glass or a transparent plastic.The sliding ring is the component that, when assembled, presses the mounting neck – at least via the sealing element and the insert, and possibly also via the viewing window – against the base of the lid. Furthermore, this is a design in which the insert also secures at least one other component – ​​in this case, even two components – within the lid.

[0022] In one embodiment, the lid and the mounting neck are connected by a rotational movement. In another embodiment of the housing, the mounting structure of the lid and the mounting neck form a bayonet fitting. In an alternative embodiment, the mounting structures consist of an internal thread and a corresponding external thread.

[0023] Furthermore, the invention relates to a field device with a housing according to one of the preceding or following embodiments. The explanations apply accordingly to the field device, so repetition is omitted. The field device serves, for example, to measure or monitor fill level, temperature, pressure, flow rate, or pH value.

[0024] The invention is explained in more detail with reference to the following figures. They show:

[0025] Fig. 1: a spatial representation of part of a first embodiment of the housing,

[0026] Fig. 2: an enlarged section of a cross-section through the housing of the first embodiment,

[0027] Fig. 3: a view into a sectioned part of the housing of the first embodiment,

[0028] Fig. 4: a spatial representation of part of a second embodiment of the housing,

[0029] Fig. 5: an enlarged section of a cross-section through the housing of the second embodiment and

[0030] Fig. 6: a view into a sectioned part of the housing of the second embodiment.

[0031] Figures 1 to 3 show a first embodiment of the housing and are described together.

[0032] The housing of the field device is shown here, consisting of a base body with the mounting neck 1 and a cover 2, which is detachably screwed onto the mounting neck 1 (see Fig. 2).

[0033] The insert 3 is located in the lid 2. Its securing structure 30 is clearly visible; in the first variant, this is formed by the crenellated outer edge 31 (see Fig. 1 and Fig. 3). The edge 31 is located on the side of the insert 3 facing away from the base 22 of the lid 2 and, in the installed state, facing the fastening structure 21 on the inside 20 of the lid 2 (see Fig. 3). The crenellated structure of the edge 31 results from the numerous axially extending recesses, which act as interruptions 32 (see Fig. 1 and Fig. 3). This, along with the choice of material for the insert 3, provides elasticity with respect to laterally and radially inwardly acting forces. Here, the edge 31 is inclined radially inward at its end face.

[0034] The fastening structure 11 on the outer surface 10 of the fastening neck 1 and the fastening structure 21 on the inner surface 20 of the wall 23 of the cover 2 are designed to form a bayonet fitting. This means that the fastening structures 11 and 21 consist of individual, separate sub-areas.

[0035] When the insert 3 is placed into the lid during manufacturing (see Fig. 3), the sections of the fastening structure 21 each exert a lateral force on the rim 31. This causes the rim 31 to deform inwards. At the very least, the affected crenellations, as part of the rim 31, move inwards. This allows the insert 3 to move further towards the base 22 of the lid 2. No radial force acts axially behind the sections, so the crenellations move outwards again. The rim 31 thus engages behind the fastening structure 21.

[0036] Conversely, if the insert 3 moves away from the base 22 and thus towards the fastening structure 21, the edge 31 rests on the structure 21. Since the edge 31 is not elastic in a purely axial direction, i.e., it is stiff or inelastic, the insert 3 is held in place and cannot fall out.

[0037] The insert 3 has a radially circumferential receptacle 33 on its side facing away from the base 22, which is laterally bounded by two edges 31. The radially outer edge 31 is the locking structure 30 under discussion. A sealing element 4, designed here as a molded seal, is located in the receptacle 33 and is slightly covered by the end face of the outer edge. The insert 3 is designed on its side facing the base 22 such that it has only a locally confined contact surface 35, designed here as a circumferential ring. During the screwing of the housing, only the contact surface 35 is in contact with the base 22 of the housing 2. In the screwed-in state, the sealing element 4 seals the transition between the mounting neck 1 and the insert 3 by pressing the mounting neck 1 into the sealing element 4.The sealing element 4 presses against the insert 3, which in turn is pressed against the base 22 only via the contact surface 35. Thus, there is a decoupling between the axial movement and the rotational movement about the longitudinal axis 100 of the base 22.

[0038] Figures 4 to 6 show a second variant of the housing. These figures will also be discussed together, focusing solely on the differences compared to the first variant shown in Figures 1 to 3.

[0039] In the second variant, the securing structure 30 is a movement contour 340 on the outer surface 34 of the insert 3 (see Fig. 4). The outer surface 34 is the radially outer area between the two end faces of the insert 3. The movement structure 340 is coordinated with the fastening structure 21 of the cover 2 such that, through a specific sequence of axial and radial movements, the insert 3 can be moved down to the base 22 of the cover 2.

[0040] After insertion, the insert 3 is in a locking position, from which at least one radial movement about the longitudinal axis 100 is required. This secures the insert 3 against falling out. Assembly requires a sequence of rotations and axial movements. An entry area into the movement structure 340 can be seen in Fig. 6.

[0041] In this second variant, an additional, but independent, feature is shown. The cover 2 is a so-called viewing cover, in that its base 22 has an opening 220. Below the cover 2 is a viewing window 6, which rests in a receiving chamber 36 of the insert 3. The sliding ring 5 is the component that rests on the base 22 when installed.

[0042] As can be seen (see Fig. 5), in the assembled state shown, the mounting neck 1 presses against the insert 3 via the sealing element 4. The insert 3, in turn, presses the sliding ring 5 against the cover 2 via the viewing window 6.

[0043] In the second variant, the interaction of securing structure 30 and fastening structure 21 not only results in – as in the first variant – the

[0044] The insert 3 is not only secured, but its primary function is to ensure that the insert 3 holds further components in the lid 2. These are the viewing window 6 and the sliding ring 5. However, the first variant can also be used for this effect.

[0045] Reference symbol

[0046] Mounting neck

[0047] Lid

[0048] insert

[0049] Sealing element

[0050] sliding ring

[0051] Viewing window

[0052] Outside of the mounting neck

[0053] Mounting structure on the outside of the mounting neck

[0054] Inside of the lid

[0055] Lid mounting structure

[0056] bottom of the lid

[0057] Wall of the lid

[0058] Securing structure of the insert

[0059] edge of the insert

[0060] Interruption of the edge of the insert

[0061] Insertion of the insert

[0062] Outside of the insert

[0063] Support surface of the insert

[0064] Insert compartment

[0065] Longitudinal axis

[0066] Opening at the bottom of the lid

[0067] Movement contour of the outer side of the insert

Claims

Patent claims 1. Housing for a field device for process automation, comprising a mounting neck (1) and a cover (2), wherein the mounting neck (1) has a mounting structure (11) on an outer surface (10), wherein the cover (2) has a mounting structure (21) on an inner surface (20) which corresponds to the mounting structure (11) of the mounting neck (1) and allows a reversible connection between the mounting neck (1) and the cover (2), wherein the cover (2) has a base (22) and a wall (23), wherein the wall (23) of the cover (2) supports the mounting structure (21), wherein the cover (2) has an insert (3), wherein the insert (3) has a locking structure (30), and wherein the locking structure (30) and the mounting structure (21) of the cover (2) are designed and aligned in such a way as tothat the insert (3) is prevented from falling out of the lid (2) by an axial movement of the insert (3) along a longitudinal axis (100) of the lid (2) in a direction away from the base (22) that exceeds a predetermined dimension.

2. Housing according to claim 1, wherein the insert (3) has at least one end face, radially circumferential rim (31), and wherein the radially circumferential rim (31) is designed to be elastic with respect to a radially inwardly acting force and forms the locking structure (30).

3. Housing according to claim 2, wherein the radially circumferential edge (31) is curved at the end face in the direction of the longitudinal axis (100).

4. Housing according to claim 2 or 3, wherein the radially circumferential rim (31) has at least one interruption (32) - and preferably several interruptions (32).

5. Housing according to one of claims 2 to 4, wherein the fastening structure (21) of the cover (2) is designed to project radially inwards.

6. Housing according to one of claims 2 to 5, wherein the radially circumferential rim (31) is designed in a crenellated manner.

7. Housing according to claim 1, wherein an outer surface (34) of the insert (3) has a movement contour (340), wherein the movement contour (340) and the fastening structure (21) of the lid (2) are designed and coordinated such that at least one relative locking position is obtained between the movement contour (340) and the fastening structure (21), which limits and preferably prevents at least a purely axial movement of the insert (3) along the longitudinal axis (100) of the lid (2) relative to the lid (2).

8. Housing according to claim 7, wherein the movement contour (340) and the fastening structure (21) of the cover (2) are designed and coordinated such that the locking position allows a rotational movement of the insert (3) about the longitudinal axis (100).

9. Housing according to claim 8, wherein the movement contour (340) and the fastening structure (21) of the cover (2) are designed and coordinated such that the locking position allows the rotational movement of the insert (3) about the longitudinal axis (100) with a limited axial movement of the insert (3) along the longitudinal axis (100).

10. Housing according to any one of claims 1 to 9, wherein the fastening structure (20) of the cover (2) and the fastening structure (10) of the fastening neck (1) implement a bayonet closure.

11. Field device for determining and / or monitoring at least one Process size with a housing according to one of claims 1 to 10.

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