Housing for a field device for process automation and field device

Abstract

The invention relates to a housing. A cover (1) has a base (10) with a recess (11) and a circumferential groove (13) in an inner wall (12). A retaining ring (3) is partially disposed in the groove (13) and partially protrudes from it. The retaining ring (3) is rigid in the axial direction. A sealing component (4) is disposed between a sight glass (2) and the base (10) of the cover (1) and is subjected to an axial preload by the sight glass (2), which bears against the retaining ring (3).

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. The sensors typically have a housing containing electronics coupled to a measuring unit. The measuring unit usually detects a process parameter or a related measurement parameter. The housing is generally multi-part and can be opened multiple times. Access is usually provided via a cover.

[0004] Such housings, or at least the covers, consist, for example, partially or completely of sheet metal, plastic, or a cast material, such as...

[0005] Aluminum die-casting or stainless steel precision casting. Also known in the prior art are covers that allow a view of, for example, a display unit located inside the housing. For this purpose, the so-called viewing cover has a recess under which a viewing window made of glass or translucent plastic is positioned. A spring element and a retaining ring are typically used to secure the viewing window, with the spring element (e.g., a wave spring) bearing against the retaining ring. Thus, several components are required, and the manufacturing process is correspondingly complex.

[0006] The invention is based on the objective of proposing a housing with a viewing window that is characterized by as few components as possible and by the safest and easiest possible assembly.

[0007] The invention solves the problem by providing a housing for a field device for process automation, comprising a lid, a viewing window, a retaining ring, and a sealing component, wherein the lid has a base with a recess, wherein the lid has a circumferential groove in an inner wall, wherein the retaining ring and the groove are designed and aligned such that the retaining ring is partially located in the groove and partially protrudes from the groove, wherein the retaining ring is rigid in the axial direction, wherein the sealing component is arranged between the viewing window and the base of the lid, wherein the viewing window has direct contact with the retaining ring, wherein the viewing window has direct contact with the sealing component, and wherein the sealing component is subject to an axial preload by the viewing window, which is supported on the retaining ring.

[0008] The lid of the housing according to the invention has a recess in its base. The recess is closed by a viewing window.

[0009] Between the base and the viewing window is a sealing component that seals the transition between them. The viewing window rests on its side facing away from the base on a retaining ring, which is axially rigid and thus forms a solid support surface for the viewing window. The viewing window is therefore positioned between two rigid planes: the base of the lid and the retaining ring inserted into the lid. To ensure the necessary fixation of the viewing window and to compensate for component tolerances, the sealing component can be compressed by the viewing window. The sealing component is thus subjected to a desired axial preload. The retaining ring itself is supported in a groove in the inner wall of the housing. The viewing window is in direct contact with both the retaining ring and the sealing component.The viewing window thus serves as a spacer between the lid base and the retaining ring. Therefore, unlike in the prior art, no additional spring element is present. This simplifies manufacturing and reduces the number of components to be assembled.

[0010] The components of the lid are designed and coordinated to meet the requirements for the specific application of the housing. This includes, for example, ensuring that the viewing window cannot fall out up to a defined impact energy. Furthermore, the sealing component must meet requirements for water and / or dust tightness.

[0011] The manufacturing process thus proceeds as follows, for example:

[0012] The sealing component is inserted into the lid. Next, the viewing window is placed in the lid. Then, the retaining ring is inserted into the groove. This step also creates the axial preload, as the retaining ring presses against the viewing window, which in turn compresses the sealing component against the base of the lid. The sealing component thus creates a seal and compensates for component tolerances.

[0013] One embodiment of the housing includes the design and alignment of the viewing window and the base of the lid such that a receiving space is formed between the base and the viewing window, and the sealing component is at least partially located within this receiving space. In this embodiment, the viewing window and the base of the lid together form a well-defined space in which the sealing component is located and can be pressed into place by pressing the viewing window against the base.

[0014] One housing design uses a snap ring as the retaining ring. During manufacturing, the snap ring can be inserted into the groove relatively easily by reducing its circumference. The resulting elastic deformation then causes it to expand within the groove.

[0015] One embodiment of the housing includes a ring-shaped sealing component. In this embodiment, the sealing component is a ring with an arbitrarily defined cross-section, e.g., circular, rectangular, cuboid, D-shaped, or X-shaped, etc.

[0016] One design of the housing provides for the viewing window to be made of glass or plastic.

[0017] 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.

[0018] The invention is explained in more detail with reference to the following figures. They show:

[0019] Fig. 1: a spatial representation of the housing of a field device and

[0020] Fig. 2: a section through a cover of the housing according to one embodiment.

[0021] Fig. 1 shows a housing of a field device with a lower component that supports the housing neck 100 and a cover 1. The cover 1 has an opening 11 through which, for example, a display unit located under the viewing window 2 – not shown here – can be viewed. The cover 1 and its components are preferably rotationally symmetrical about the longitudinal axis.

[0022] The section in Fig. 2 shows the lid 1, which has a recess 11 in its base 10 and a circumferential groove 13 in its inner wall 12.

[0023] A snap ring, for example a retaining ring 3, is inserted in the groove 13. The retaining ring 3 forms the axially rigid base for the viewing window 2, which covers the recess 11 of the base 10. A circumferential receiving space 5 is located between the viewing window 2 and the base 10, in which a sealing component 4, here designed as an O-ring, is partially arranged. The sealing component 4 seals the transition between the viewing window 2 and the base 10. Furthermore, the sealing component 4 compensates for manufacturing-related variations in the height of the retaining ring 3, its position (which depends on the design of the groove 13), the position of the groove 13, and, for example, the height of the viewing window 2. For this purpose, the sealing component 4, which is axially compressible, is located between the viewing window 2 and the base 10.

[0024] Cover, viewing window, retaining ring, sealing component, receiving chamber, bottom

[0025] Recess in inner wall

[0026] Nut

[0027] case neck

Claims

Patent claims 1. Housing for a field device for process automation, with a lid (1), with a viewing window (2), with a retaining ring (3), and with a sealing component (4), wherein the lid (1) has a base (10) with a recess (11), wherein the lid (1) has a circumferential groove (13) in an inner wall (12), wherein the retaining ring (3) and the groove (13) are designed and aligned such that the retaining ring (3) is partially arranged in the groove (13) and partially protrudes from the groove (13), wherein the retaining ring (3) is rigid in the axial direction, wherein the sealing component (4) is arranged between the viewing window (2) and the base (10) of the cover (1), wherein the viewing window (2) has direct contact with the retaining ring (3), wherein the viewing window (2) has direct contact with the sealing component (4), and wherein the sealing component (4) is subject to an axial preload by the viewing window (2), which is supported on the retaining ring (3).

2. Housing according to claim 1 , wherein the viewing window (2) and the base (10) of the lid (1) are designed and coordinated such that a receiving space (5) is formed between the base (10) and the viewing window (2), and wherein the sealing component (4) is arranged at least partially in the receiving space (5).

3. Housing according to claim 1 or 2, wherein the retaining ring (3) is a snap ring.

4. Housing according to one of claims 1 to 3, wherein the sealing component (4) is designed in a ring shape.

5. Housing according to one of claims 1 to 4, wherein the viewing window (2) consists of glass or plastic.

6. Field device for determining and / or monitoring at least one process variable with a housing according to one of claims 1 to 5.

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