Assembly, housing cover with assembly of this type and field device with housing cover of this type

Abstract

The invention relates to an assembly (100) comprising a circular disk (160), an annular body (110), and an elastomer ring (190). The annular body (110) has a disk receptacle (120) surrounded by a peripheral lateral surface, which lateral surface has an annular outer groove (130), which is delimited in a first axial direction by a first outer shoulder (132) and in an opposite second axial direction by a second outer shoulder (134). A guide surface adjoins the first outer shoulder in the first axial direction, the radius of which increases monotonically with increasing distance from the first shoulder, and in the case of which dr / dz < 2 / 3, in particular dr / dz < 1 / 3, where r is the radius and z is the axial coordinate of the guide surface in cylindrical coordinates. The circular disk (160) has an outer lateral surface, which has a peripheral inner groove (170) extending radially inwards, which is delimited in the first axial direction by a first inner shoulder (172) and in the second axial direction by a second inner shoulder (174). At least the two aforementioned inner shoulders have a convex profile when viewed in an axial longitudinal section, in which the rotational axis of the circular disk (160) extends. The elastomer ring (190) is clamped between the two aforementioned inner shoulders and the two aforementioned outer shoulders, thereby preventing, in particular, the circular disk from slipping out of the annular body up to a limit load.

Description

TECHNICAL FIELD

[0001] The invention relates to an assembly, to a housing cover having such an assembly and to a field device having such a housing cover. BACKGROUND

[0002] The assembly of the invention, in particular the housing cover, comprises a circular face plate and a ring-shaped body having a seat for the circular face plate. The seat for the circular face plate can for example have a stop against which the circular face plate is axially clamped, or the circular face plate can be held in the seat by a metal retaining ring, wherein additionally a sealing ring is provided which lies against the circular face plate in order to avoid an exchange of gas between two volumes separated from one another by the circular face plate through the circular face plate.

[0003] The assembly of the invention is used, among other possibilities, as a housing cover of a housing of a field device in order to close the housing, wherein it is usually required that the field device fulfils the ignition protection type Ex-d, i.e. "pressure- resistant encapsulation". The assembly described above therefore has a relatively complex design with high strength and strict production tolerances in order to achieve the required protection class. SUMMARY

[0004] It is an object of the invention to provide a simplified assembly without degrading the performance of the assembly. According to the invention, this object is achieved by the assembly, the housing cover and the field device according to the invention.

[0005] The assembly of the invention comprises a circular face plate, a ring-shaped body and an elastomer ring, wherein the ring-shaped body has a face plate seat surrounded by a lateral surface, wherein the lateral surface has an annularly encircling outer groove which is delimited in a first axial direction by a first outer shoulder and in an opposite second axial direction by a second outer shoulder, wherein a guide surface adjoins the first outer shoulder in the first axial direction, the radius of the guide surface monotonically increasing with the distance from the first shoulder, wherein dr / dz < 2 / 3, in particular dr / dz < 1 / 3, wherein the circular face plate has an outer lateral surface with a perimetrical inner groove extending radially inwards, the perimetrical inner groove being delimited in the first axial direction by a first inner shoulder and in the second axial direction by a second inner shoulder, wherein the at least two inner shoulders have a convex profile in an axial longitudinal cross section in which the rotation axis of the circular face plate extends, wherein the elastomer ring is clamped between the two inner shoulders and the two outer shoulders, thereby preventing in particular the circular face plate from moving out of the ring-shaped body up to a limit load.

[0006] In another development of the application, the limit load can comprise, for example, the load at which the elastomer ring breaks, or an energy impact of more than 7 Joule, or a positive pressure of more than 0.2 bar, for example more than 0.5 bar, in particular more than 1 bar.

[0007] In particular, the circular panel is held in the panel seat only by the elastomer ring.

[0008] According to a further development of the application, the elastomer ring additionally serves as a sealing ring, wherein in particular the second inner shoulder and the second outer shoulder serve as sealing surfaces.

[0009] Furthermore, the elastic suspension via the elastomer ring is able to absorb impact energy, whereby the panel is subjected to significantly less force in the event of an impact.

[0010] A profile is convex when a straight line connecting two points on the surface of the profile passes through or extends on the surface of the profile.

[0011] In an additional development of the application, the inner recess has a free release space which is delimited by the elastomer ring and whose cross-sectional area in a longitudinal section is not less than one fourth, for example not less than one third, of the cross-sectional area of the elastomer ring in a relaxed, unclamped state.

[0012] In an additional development of the application, the height h of the release space is less than the cross-section of the elastomer ring.

[0013] In an additional development of the application, the height h of the release space monotonically increases with the radius, wherein for the slope dh / dr of the height h as a function of the radius r between the first inner shoulder and the second inner shoulder, over an area of at least 50% radially outside the inner shoulders, the elastomer ring is axially clamped between the first inner shoulder and the second inner shoulder: dh / dr > 1 / 2, in particular dh / dr > 2 / 3.

[0014] In an additional development of the application, the guide surface has a truncated conical shape.

[0015] In an additional development of the application, the circular panel comprises a transparent material, in particular glass or a transparent polymer, for example PMMA, PEEK or polycarbonate.

[0016] In an additional development of the application, the annular body comprises a metallic material, for example aluminum, or a polymer, for example PEEK or polycarbonate.

[0017] In an additional development of the application, the elastomer ring comprises an elastomer, for example VMQ, HNBR, FKM, EPDM.

[0018] In an additional development of the application, the maximum radial spacing between the lateral surface of the circular panel and the lateral surface of the panel seat, in particular over an axial length of not less than 10 mm, is not more than 0.15 mm.

[0019] In an additional development of the application, in an axial longitudinal section through the center of the circular panel, a first connecting line connects a first center of a first support surface of the elastomer ring on the first inner shoulder to a second center of a second support surface of the elastomer ring on the second outer shoulder, wherein a second connecting line connects a third center of a third support surface of the elastomer ring on the second inner shoulder to a fourth center of a fourth support surface of the elastomer ring on the first outer shoulder, wherein the first connecting line is inclined by not more than 45°, in particular by not more than 40°, with respect to the axis of rotation of the circular panel, wherein the second connecting line is inclined by not more than 45°, in particular by not more than 40°, with respect to the axis of rotation of the circular panel, wherein the first connecting line is inclined by not less than 15°, in particular by not less than 23°, with respect to the axis of rotation of the circular panel, wherein the second connecting line is inclined by not less than 15°, in particular by not less than 23°, with respect to the axis of rotation of the circular panel.

[0020] In an additional development of the application, the minimum spacing between the first inner shoulder and the second outer shoulder is not more than 90% of the cross section of the elastomer ring, wherein the minimum spacing between the second inner shoulder and the first outer shoulder is not more than 90% of the cross section of the elastomer ring.

[0021] In an additional development of the application, the minimum radius of the first outer shoulder is greater than the maximum radius of the second inner shoulder by not more than 0.5 mm, in particular by not more than 0.2 mm.

[0022] The housing cover for a field device of the application comprises the assembly of the application, wherein the annular body further has a cylindrical wall segment.

[0023] The cylindrical wall segment can have a thread, in particular an internal thread, in order to be able to fix the housing cover on the housing body. Other types of fixation are likewise possible, for example a screw or a bayonet connection.

[0024] The field device of the application comprises a housing and an operating circuit arranged in the housing, wherein the housing has a housing body and at least one housing cover of the application, wherein the thread of the housing cover is screwed onto the complementary thread of the housing body in order to enclose the operating circuit.

[0025] In an additional development of the application, the field device fulfils the ignition protection type, namely "pressure- resistant encapsulation" Ex-d.

[0026] Within the scope of the application, the field device comprises, for example, a measuring transmitter, such as, for example, a measuring transmitter used in industrial process measurement technology, in order to record process parameters, such as temperature, pressure, fill level, flow rate, density, viscosity, pH value, redox potential, conductivity, humidity, dissolved gas concentration, sludge level, turbidity, global parameters, such as TOC or composition of a multi-component medium. Furthermore, within the scope of the application, the field device can comprise an actuator, for example a pump, a valve, a stirrer or a temperature control device, for example a refrigeration unit or a heater. The field device usually comprises an operating circuit for operating the field device, in particular for providing a measurement signal to a control system or for receiving an actuating signal from a control system and for controlling an actuator in accordance with the actuating signal. BRIEF DESCRIPTION OF DRAWINGS

[0027] The application will now be explained in more detail on the basis of examples of embodiments shown in the drawings. The figures in the drawings show the following:

[0028] Figure 1 is a schematic longitudinal sectional view of an example of an embodiment of a field device of the application; and

[0029] Figure 2 is a detailed longitudinal sectional view of a component of an embodiment of an assembly of the application. DETAILED DESCRIPTION

[0030] Figure 1 The example of an embodiment of a field device 300 of the application shown comprises a field device housing 310 having an at least partially cylindrical housing body 312 and an assembly 100 of the application, which forms a housing cover. Imple- mented in the housing 300 is a chamber 314, in which an operating circuit 330 for operating the field device 300 is arranged. The field device 300 additionally comprises a sensor module 340, which is mechanically connected with and in particular carries the housing 310. The sensor module 340 can be, for example, a flow measurement sensor for recording a volumetric or mass flow rate. The sensor module 340 provides measured primary signals dependent on variables, which are conditioned by the operating circuit 330 for forwarding to a control system or for display in a display 332. Details in this respect are known and need not be explained here.

[0031] The assembly 100, which serves as a housing cover, comprises an annular body 110 having a panel seat 120, in which a panel 160 is arranged and held with an elastomer ring 190. The panel seat 120 extends as a circular opening between a first end face and a second end face of the annular body 110, wherein the lateral surface 122 delimiting the panel seat has a contour on which the elastomer ring 190 is held, which will be explained in the following in connection withFigure 2 To explain in more detail. Furthermore, the annular body 110 includes a sleeve-shaped protrusion 116 with threads 118 formed on its inner lateral surface. These threads 118 engage with complementary external threads 316 in the housing body 312 to close the chamber 314. The circular panel 160 optionally includes a coaxial circular protrusion 180 on its surface near the chamber 314. This protrusion 180 has a height of 10 mm on its outer lateral surface, wherein an annular gap 182 is maintained between the outer lateral surface of the protrusion and the opposing lateral surface of the annular body 110. This annular gap 182 meets the requirements of a flame penetration barrier, specifically having a gap width of no more than 0.15 mm. With the corresponding dimensions of the material thicknesses of the housing body 312, the annular body 110, the circular panel 160, and the elastomeric ring 190 set, the field device 300 thus meets the requirements of the ignition protection type "pressure-resistant encapsulation," or "Ex-d."

[0032] Now based on Figure 2 Details of component 100 of the present invention are explained, which in this case forms a housing cover. Figure 2 A longitudinal section including the Z-axis is shown, which is therefore the axis of rotational symmetry of the assembly. Assembly 100 includes a generally rotationally symmetric annular body 110 having a first end face 112 and a second end face 114 spaced apart from the first end face 112. A through circular opening extends between the first end face 112 and the second end face 114, forming a panel seat 120. The panel seat is defined by a lateral surface 122, into which an outer annular groove 130 extends radially outward. The outer annular groove 130 is defined in a first axial direction by a first outer shoulder 132 and in a second axial direction by a second outer shoulder 134. In the first axial direction, a first guide surface 124 is connected to the first outer shoulder 132, the first guide surface 124 being implemented as a frustoconical shape and inclined, for example, at 30° relative to the Z-axis. The first outer shoulder 132 is generally planar except for a rounded convex chamfer in its inner end section. Conversely, the second outer shoulder 134 is inclined relative to the plane Z = constant (const) for example, 40° to 50°.

[0033] A circular faceplate 160 is introduced into the faceplate seat 120, the circular faceplate 160 having a first end face 162 which is substantially axially aligned with the first end face 112 of the annular body 110. Furthermore, the end face 162 has a radial protrusion 164 from the volume of the circular faceplate 160 in order to limit the annular gap between the circular faceplate 160 and the faceplate seat to no more than 0.15 mm. An inner ring groove 170 extends radially inward into the circular faceplate 160 from a lateral surface 166 of the circular faceplate 160, the inner ring groove 170 being substantially aligned with the outer ring groove 130 in the axial direction. The inner ring groove 170 is delimited in the first axial direction by a first inner shoulder 172 and in the second axial direction by a second inner shoulder 174. The two inner shoulders 172, 174 have a convex shape in a cross-sectional view of Figure 2 The axial spacing between the two inner shoulders 172, 174 defines a height h of the groove 170 which increases with increasing radius and a peripheral space 176 which lies in the groove delimited by the elastomer ring 190. The elastomer ring 190 is clamped between the two outer shoulders 132, 134 and the two inner shoulders 172, 174. This holds the circular faceplate 160 in the faceplate seat 120. Furthermore, the radial protrusion 164 serves as a safeguard against the circular faceplate 160 being pressed out of the faceplate seat, since when the radial protrusion 164 is placed against the elastomer ring 190 by displacement of the circular faceplate 160, further movement is prevented until the elastomer ring 190 is destroyed.

[0034] The following geometrical aspects of the assembly facilitate the retention of the circular faceplate:

[0035] If, in a longitudinal cross-sectional view of Figure 2 the radially outermost bearing point of the elastomer ring 190 on the first inner shoulder 172 is connected with the radially innermost bearing point of the elastomer ring 190 on the second outer shoulder 134 and if the radially innermost bearing point of the elastomer ring 190 on the first inner shoulder 172 is connected with the radially outermost bearing point of the elastomer ring 190 on the second outer shoulder 134, two dashed lines are obtained, wherein an angle bisector which runs through their intersection point and between the first inner shoulder 172 and the second outer shoulder 134 defines a first connection line VL1 between the center points of the bearing surfaces 172A, 134A of the elastomer ring 190 on the first inner shoulder 172 and the second outer shoulder 134.

[0036] If, respectively, in a longitudinal cross-sectional view of Figure 2In the longitudinal cross-sectional view, if the radially outermost support point of the elastomeric ring 190 on the second inner shoulder 174 is connected to the radially innermost support point of the elastomeric ring 190 on the first outer shoulder 132, and if the radially innermost support point of the elastomeric ring 190 on the second inner shoulder 174 is connected to the radially outermost support point of the elastomeric ring 190 on the first outer shoulder 132, then two solid lines are obtained, wherein the angle bisector passing through their intersection and extending between the second inner shoulder 174 and the first outer shoulder defines the second connecting line VL2 between the center points of the support surfaces 174A, 132A of the elastomeric ring 190 on the second inner shoulder 174 and the second outer shoulder 132.

[0037] Two connecting lines, VL1 and VL2, extend relatively steeply for radial sealing. Therefore, the first connecting line is inclined, for example, at 35° relative to the axis of rotation Z, and the second connecting line is inclined, for example, at 29° relative to the axis of rotation. Thus, in each case, the axial component of the connecting line exceeds 80% of its length. The length of this axial component is an indicator of the effectiveness of the elastomer ring 190 in resisting axial displacement of the circular panel 160. A value of 80% is considered very good.

[0038] To assemble assembly 100, the elastomeric ring 190 is pushed onto the lateral surface 166 of the circular panel 160, such that the elastomeric ring is positioned against the two inner shoulders 172, 174. Then, with end face 162 facing forward, the circular panel is inserted into the panel holder 120 from the second end face 114 of the annular body. In this case, the elastomeric ring 190 slides on the guide surface 124 and is radially pressed inward into the release space 176 of the inner annular groove 170, thereby compressing the elastomeric ring 190 axially between the inner shoulders, resulting in considerable axial stress. Once the periphery of the elastomeric ring 190 has passed the end of the guide surface, the axial stress in the elastomeric ring 190 begins to decay as the elastomeric ring 190 then expands into the available free volume of the outer annular groove 130, allowing the elastomeric ring to reach its final position, which, in a given case, can be optimized by a small axial relative movement between the annular body 110 and the circular panel 160.

Claims

1. Components, including: Circular panel (160); Ring-shaped main body (110); and Elastomer ring (190); The annular body (110) has a panel seat (120) surrounded by a lateral surface, wherein the lateral surface has an annular surrounding outer groove (130), the outer groove being defined by a first outer shoulder (132) in a first axial direction and by a second outer shoulder (134) in the opposite second axial direction; The guide surface is adjacent to the first outer shoulder in the first axial direction, and the radius of the guide surface increases monotonically with the interval between it and the first outer shoulder, where dr / dz < 2 / 3, where r is the radius and z is the axial coordinate of the guide surface in cylindrical coordinates; The circular panel (160) has an outer surface with a radially inwardly extending peripheral groove (170) defined by a first inner shoulder (172) in the first axial direction and by a second inner shoulder (174) in the second axial direction. At least two of the inner shoulders have a convex profile in the axial longitudinal section, and the axis of rotation of the circular panel (160) extends in the axial longitudinal section. The elastomeric ring (190) is clamped between the two inner shoulders and the two outer shoulders, thereby preventing the circular panel from moving out of the annular body until the ultimate load. The elastomeric ring (190) is further used as a sealing ring, wherein the second inner shoulder and the second outer shoulder are used as sealing surfaces.

2. The component according to claim 1, wherein, The peripheral inner groove has an empty release space defined by the elastomer ring, and the cross-sectional area of ​​the empty release space in the axial longitudinal section is not less than one-quarter of the cross-sectional area of ​​the elastomer ring in the relaxed, unclamped state.

3. The component according to claim 2, wherein, The height h of the empty release space is less than the cross-section of the elastomer ring.

4. The component according to claim 3, wherein, The height h increases monotonically with the radius between the two inner shoulders. Wherein, for the slope dh / dr of the height h as a function of the radius r between the first inner shoulder and the second inner shoulder, the elastomeric ring is axially clamped between the first inner shoulder and the second inner shoulder over at least 50% of the radially outer area of ​​the two inner shoulders: dh / dr > 1 / 2.

5. The component according to claim 1 or 2, wherein, The guiding surface is a truncated cone shape.

6. The component according to claim 1 or 2, wherein, The circular panel comprises a transparent material.

7. The component according to claim 1 or 2, wherein, The annular body may be made of a metallic material or a polymer.

8. The component according to claim 1 or 2, wherein, The elastomeric ring comprises an elastomeric material.

9. The component according to claim 1 or 2, in, The maximum radial distance between the outer surface of the circular panel and the lateral surface of the panel base does not exceed 0.15 mm.

10. The component according to claim 1 or 2, wherein, In an axial longitudinal section passing through the center of the circular panel, a first connecting line (VL1) connects the first center of the first support surface of the elastomeric ring on the first inner shoulder to the second center of the second support surface of the elastomeric ring on the second outer shoulder, wherein a second connecting line (VL2) connects the third center of the third support surface of the elastomeric ring on the second inner shoulder to the fourth center of the fourth support surface of the elastomeric ring on the first outer shoulder. The first connecting line is inclined at no more than 45° relative to the rotation axis of the circular panel, and the second connecting line is inclined at no more than 45° relative to the rotation axis of the circular panel. The first connecting line is inclined at a rate of not less than 15° relative to the rotation axis of the circular panel, and the second connecting line is inclined at a rate of not less than 15° relative to the rotation axis of the circular panel.

11. The component according to claim 1 or 2, wherein, The minimum distance between the first inner shoulder and the second outer shoulder does not exceed 90% of the cross-section of the elastomer ring, and the minimum distance between the second inner shoulder and the first outer shoulder does not exceed 90% of the cross-section of the elastomer ring.

12. The component according to claim 1 or 2, wherein, The minimum radius of the first outer shoulder is no more than 0.5 mm larger than the maximum radius of the second inner shoulder.

13. The component according to claim 1 or 2, wherein, The ultimate load includes the load at which the elastomer ring breaks, or an impact with energy greater than 7 joules, or a pressure greater than 0.2 bar on the circular panel.

14. The component according to claim 1 or 2, wherein, dr / dz < 1 / 3.

15. The component according to claim 2, wherein, The cross-sectional area of ​​the empty release space in the axial longitudinal section is not less than one-third of the cross-sectional area of ​​the elastomer ring in the relaxed, unclamped state.

16. The component of claim 4, wherein, dh / dr>2 / 3.

17. The component of claim 6, wherein, The transparent material is glass or a transparent polymer.

18. The component of claim 17, wherein, The polymer is PMMA, PEEK or polycarbonate.

19. The component according to claim 7, wherein, The metal material is aluminum, and the polymer is PEEK or polycarbonate.

20. The component of claim 8, wherein, The elastomer is VMQ, HNBR, FKM, or EPDM.

21. The component according to claim 9, wherein, The maximum radial distance between the outer surface of the circular panel and the lateral surface of the panel base in an axial length of not less than 10 mm shall not exceed 0.15 mm.

22. The component of claim 10, wherein, The first connecting line is inclined at no more than 40° relative to the rotation axis of the circular panel, wherein the second connecting line is inclined at no more than 40° relative to the rotation axis of the circular panel. The first connecting line is inclined at a rate of not less than 23° relative to the rotation axis of the circular panel, and the second connecting line is inclined at a rate of not less than 23° relative to the rotation axis of the circular panel.

23. The component of claim 12, wherein, The minimum radius of the first outer shoulder is no more than 0.2 mm larger than the maximum radius of the second inner shoulder.

24. The component of claim 13, wherein, The ultimate load includes a pressure greater than 0.5 bar on the circular panel.

25. The component of claim 13, wherein, The ultimate load includes a pressure greater than 1 bar on the circular panel.

26. A housing cover for a field device, comprising the component according to any one of the preceding claims, wherein, The annular body also has cylindrical wall sections.

27. A field device comprising a housing and operating circuitry disposed within the housing, wherein, The housing has a housing body and at least one housing cover as claimed in claim 26, wherein the threads of the housing cover are screwed onto complementary threads of the housing body to close the operating circuit.

28. The field device according to claim 27, wherein, The field equipment meets the ignition protection type Ex-d.

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