Cover-securing means for a transmitter housing

Abstract

The present disclosure relates to a cover-securing mechanism for a transmitter housing closed by a screwed-on cover. The cover-securing mechanism includes a securement pin with a screw arranged at a first end region of the securement pin. A passageway, which is embodied to accommodate the securement pin, is integrated in the cover. A groove includes a circularly shaped section and is introduced into a cover facing region of the transmitter housing. The securement pin is securable at a transmitter housing far end of the cover in the passageway such that in a secured state a second end region of the securement pin protrudes inwardly into the groove and, as such, a twisting of the cover screwed onto the transmitter housing is constrained relative to the transmitter housing.

Claims

1. A cover-securing mechanism for a transmitter housing of a field device of automation technology, wherein the transmitter housing is closed by a screwed-on cover, including: a securement pin with a screw arranged at a first end region of the securement pin; a passageway, which is embodied to accommodate the securement pin, integrated in the cover; and a groove, which includes a circularly shaped section and which is introduced into a cover facing region of the transmitter housing; wherein the securement pin is securable at a transmitter housing far end of the cover in the passageway such that in a secured state a second end region of the securement pin opposite the first end region protrudes inwardly into the groove, whereby a twisting of the cover screwed onto the transmitter housing is constrained relative to the transmitter housing.

2. The cover-securing mechanism of claim 1, wherein the cover and the transmitter housing are cylindrical and the cover is screwed with a cylindrical region onto a cylindrical region of the transmitter housing.

3. The cover-securing mechanism of claim 2, wherein the circularly shaped section extends around an imaginary circle center of the cylindrical region of the transmitter housing such that the securement pin screwed into the passageway in the secured state constrains twisting of the screwed-on cover relative to the transmitter housing to a circularly shaped section having a segment angle, which matches the circularly shaped section around the imaginary circle center, wherein the segment angle is less than 120°.

4. The cover-securing mechanism of claim 3, wherein the segment angle is between 30° and 90°.

5. The cover-securing mechanism of claim 1, wherein the securement pin is formed of a ductile material.

6. The cover-securing mechanism of claim 1, wherein the securement pin is formed of a metal or a metal alloy.

7. The cover-securing mechanism of claim 1, wherein the screw enables the securement pin to be screwed into the passageway.

8. The cover-securing mechanism of claim 1, wherein the groove is adapted in such a manner to the securement pin that between the second end region of the securement pin inserted into the passageway and a groove bottom of the groove a gap is formed.

9. The cover-securing mechanism of claim 1, wherein the first end region of the securement pin inserted into the passageway extends in a transmitter housing far direction toward a transmitter housing far end of the cover.

10. The cover-securing mechanism of claim 9, wherein the screw of the securement pin inserted into the passageway is sunk by an offset of at least 2 mm from the transmitter housing far end of the cover.

11. The cover-securing mechanism of claim 1, wherein the passageway is drilled in the cover.

12. The cover-securing mechanism of claim 1, wherein the groove is drilled or milled in the transmitter housing.

13. The cover-securing mechanism of claim 1, wherein a sealing element sealing the passageway is positioned between the transmitter housing and the securement pin.

14. The cover-securing mechanism of claim 13, wherein the sealing element is an O-ring surrounding the securement pin at its first end region.

15. The cover-securing mechanism of claim 13, wherein the sealing element includes a synthetic material.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention will now be explained in greater detail based on the appended drawing. Equal reference characters refer to equal features; when perspicuity requires or it otherwise appears sensible, already presented reference characters are omitted in subsequent figures. The figures of the drawing show as follows:

(2) FIG. 1 shows a plan view of a transmitter housing with a groove in an embodiment of the cover-securing means of the invention;

(3) FIG. 2 shows a sectional view of a securement pin in an embodiment of the cover-securing means of the invention;

(4) FIG. 3a shows a perspective view of an embodiment of the cover-securing means of the invention;

(5) FIG. 3b shows a sectional view of the embodiment of the cover-securing means of the invention shown in FIG. 3a; and; and

(6) FIG. 4 shows a perspective view of an embodiment of the cover-securing means of the invention.

DETAILED DESCRIPTION

(7) FIG. 1 shows a plan view of the region of the transmitter housing 1 facing the cover 2 in an embodiment of the cover-securing means of the invention. Shown is the groove 4, which is introduced into a wall of the transmitter housing 1 facing the cover 2. Groove 4 comprises a circularly shaped section of segment angle α about an imaginary circle center of the transmitter housing 1. The securement pin 3 (not shown) screwed into the passageway 21 in the inserted state limits twisting of the screwed-on cover 2 (not shown) to the segment angle α relative to the transmitter housing 1.

(8) FIG. 2 shows a sectional view of the securement pin 3. The securement pin 3 is manufactured as one piece or alternatively by means of material bonding, for example, welding, of a prefabricated pin and a prefabricated screw 31. Securement pin 3 includes a first end region ER1, where the screw 31 is arranged, as well as a second end region ER2, which lies opposite the first end region ER1. The second end region ER2 of the securement pin 3 protrudes in the inserted state into the groove 4.

(9) Such can be seen in FIG. 3a, which is a perspective view of an embodiment of the cover-securing means of the invention. Securement pin 3 is here screwed into the passageway 21, which extends in the cover 2. In this regard, passageway 21 includes at an end region far from the transmitter housing 1 a screw thread, into which the screw 31 of the securement pin 3 is screwed in.

(10) The screwed in securement pin 3 limits twisting of the cover 2 relative to the transmitter housing 1 to a segment angle α (compare FIG. 1), which in this example of an embodiment amounts to 60°. This twisting of the cover 2, relative to the transmitter housing 1 is not sufficient for an unscrewing of the cover 2. The segment angle α enables a certain variation of the angular position of the securement pin 3 in the groove 4, this being necessary, for example, as a result of tolerances in the manufacturing.

(11) In order to be able to screw the cover 2 completely off, first, such as required in the Ex-d protection class, screw 31 must be unscrewed and the securement pin shifted in the direction in the cover 2 away from the transmitter housing 1. Thus, the screwed-in securement pin 3 secures the cover 2 screwed onto the transmitter housing 1.

(12) The securement pin 3 of FIG. 3a inserted into the passageway 21 is shown in greater detail in the sectional view of FIG. 3b. In such case, the gap between the second end region ER2 of the securement pin 3 and the groove bottom 41 of the groove 4 can be seen. In this way, the securement pin 3 does not in the state inserted into the passageway 21 contact the groove bottom 41 of the groove 4, whereby the risk of damage of the lacquer, with which the transmitter housing 1 is coated, is reduced. Such is important, since this lacquer serves, among other things, as a corrosion protection layer for the transmitter housing. Only in the case of an attempt to unscrew the cover 2 secured by the cover-securing means does the securement pin 3 hit laterally on the end regions of the groove 4. In this way, further twisting of the cover relative to the transmitter housing 1 beyond the segment angle α (compare FIG. 1) is prevented. In this way, an unscrewing of the cover 2 secured with the cover-securing means of the invention is excluded.

(13) In this embodiment, a sealing element 5 is supplementally provided. Sealing element 5 is an O-ring of an elastomer. Sealing element 5 is located preferably at the first end region ER1 between the screw 31 and the transmitter housing 1. In this way, the passageway 21 is supplementally sealed against incursion of moisture.

(14) A further advantage of the cover-securing means of the invention provides that the securement pin 3 in the unscrewed state does not have to be completely removed from the passageway 21. After unscrewing, the securement pin 3 only needs to be shifted in the direction toward the transmitter housing 1 far end of the cover 2 sufficiently far that the second end region ER2 of the securement pin 3 no longer engages in the groove 4. This shifting of the unscrewed cover-securing means enables the unscrewing of the cover 3. Since the securement pin 3 is only shifted, the probability of the securement pin 3 falling out is significantly reduced. Such a falling out could otherwise lead to a complete loss of the securement pin 3 and therewith the cover-securing means, for example, in the case, in which the field device is operated in difficultly accessible areas.

(15) FIG. 4 shows a perspective view of a transmitter housing 1 of a field device having two cover-securing means of the invention for two covers 2 closing the transmitter housing 1 at two different end regions. Visible in the view is only the screw head of the screw 31 of the securement pin 3, which secures a first of the two covers 2. The screw head of the securement pin is sunk by a small offset of 3 mm from the transmitter housing 1 far end of the cover 2 in the direction of the transmitter housing 1. The screw head of the screw 31 of the securement pin 3 can, in such case, (independently of the embodiment shown here) supplementally be coated with an additional corrosion protection layer, for example, of gold.

REFERENCE CHARACTERS AND SYMBOLS

(16) 1 transmitter housing

(17) 2 cover

(18) 21 passageway

(19) 3 securement pin

(20) 31 screw

(21) 4 groove

(22) 41 groove bottom

(23) 5 sealing element

(24) ER1 first end region

(25) ER2 second end region

(26) α segment angle