Process measurement technology sensor

Abstract

Process measurement technology sensor, comprising a sensor housing having a sensor head, wherein the sensor head has at least one sensor element for determining a measurand of a measured medium which is arranged inside the sensor housing, and wherein the sensor has electronic measuring equipment which is arranged inside the sensor housing, wherein the sensor housing has, at a distance from the electronic measuring equipment and from the sensor element, a condensation trap in the form of a local region of a wall of the sensor housing with reduced wall thickness.

Claims

1. A process measurement technology sensor, comprising: a sensor housing having a sensor head; a sensor element for determining a measurand of a measured medium, wherein the sensor element is disposed in the sensor head and is arranged inside the sensor housing; and electronic measuring equipment which is arranged inside the sensor housing, wherein the sensor housing has, at a distance from the electronic measuring equipment and from the sensor element, a condensation trap in the form of a local region of a wall of the sensor housing having reduced wall thickness.

2. The process measurement technology sensor according to claim 1, wherein the wall thickness of the condensation trap is at least 20% less than a wall thickness of adjacent regions of the sensor housing.

3. The process measurement technology sensor according to claim 1, the wall of the sensor housing has a grooved or corrugated surface in the local region of the condensation trap.

4. The process measurement technology sensor according to claim 1, wherein the sensor housing includes a tubular sensor shaft which is connected to the sensor head, wherein the condensation trap is designed as a local region running circumferentially along an inner wall of the sensor shaft.

5. The process measurement technology sensor according to claim 1, wherein the sensor head has an end face, and wherein the condensation trap is arranged in the region of the end face.

6. The process measurement technology sensor according to claim 1, wherein the condensation trap is designed as an indentation which is arranged along an inner side of the wall of the sensor housing.

7. The process measurement technology sensor according to claim 6, wherein the sensor housing is locally hardened, including surface-hardened, in the region of the indentation.

8. The process measurement technology sensor according to claim 1, further comprising: a humidity sensor, wherein the condensation trap includes the humidity sensor, or wherein the humidity sensor is arranged adjacent to the condensation trap.

9. The process measurement technology sensor according to claim 1, further comprising: a heating unit, wherein the condensation trap has the heating unit, or wherein the heating unit is arranged adjacent to the condensation trap.

10. The process measurement technology sensor according to claim 1, wherein the electronic measuring equipment and the sensor element are arranged at least 8 mm from the condensation trap.

11. The process measurement technology sensor according to claim 1, further comprising: a moisture-binding material, wherein the condensation trap has this material, or wherein this material is arranged adjacent to the condensation trap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, features, and details of the present disclosure will become apparent from the following description, in which an exemplary embodiment of the present disclosure is explained in more detail with reference to the drawings. The person skilled in the art will expediently also individually consider the features disclosed in combination in the drawings, the description, and the claims, and combine them into reasonable further combinations.

(2) In the drawings:

(3) FIG. 1 shows a perspective view of a sensor according to the present disclosure in the embodiment as an absorption sensor for turbidity and solid measurements;

(4) FIG. 2 shows a side view of the sensor of FIG. 1 in partial section;

(5) FIG. 3 shows a perspective view of the sensor head of the sensor of FIGS. 1 and 2;

(6) FIG. 4 shows a side sectional view of the sensor head of FIG. 3; and

(7) FIG. 5 shows a sectional view from the front of the sensor head of FIG. 3.

DETAILED DESCRIPTION

(8) FIGS. 1 and 2 show a sensor 1 according to the present disclosure in the embodiment as an absorption sensor for turbidity and solid measurements. This sensor operates according to the principle of light attenuation according to ISO7027 in the version prevailing at the time of the application of the present disclosure.

(9) Sensor 1 has a sensor housing 2 comprising a tubular sensor shaft 18 and a sensor head 3 arranged at the end thereof, which sensor head 3, in the present embodiment variant, is arranged on the sensor shaft 18 so as to be detachable. However, variants are also possible in which the sensor head 3 is connected, e.g., welded, to the sensor shaft 18 so as to be undetachable.

(10) The sensor head has a measuring gap 4 which is introduced as an indentation into the end face of the sensor head. The measuring gap is designed in such a way that a medium stream may flow through the measuring gap 4.

(11) Electronic measuring equipment 5 is arranged within the sensor housing 2. Said equipment may have, inter alia, one or more circuit boards and/or electronic components, e.g. for signal processing of a measurement signal.

(12) Since the electronic measuring equipment 5 is susceptible to moisture, the sensor housing has a condensation trap 6. In the embodiment variant of FIG. 2, this is a groove, preferably circumferential, arranged along the inner wall of the sensor housing 2, which groove represents a reduction in wall thickness relative to the adjacent sections of the sensor housing 2, especially of the sensor shaft 18. This groove is unfilled and, compared to the surface of the adjacent segments of the sensor housing 2, may have a greater surface roughness so that condensed liquid remains in the groove.

(13) The groove may advantageously occupy only less than 10%, especially preferably less than 5%, of the surface of the inner wall of the sensor housing 2.

(14) The sensor housing 2 may optionally be surface-hardened in the region of the condensation trap. The loss of stability due to the reduction in wall thickness in the region of the condensation trap may thus be compensated.

(15) The sensor head 3 is shown in more detail in FIG. 3-5. The measuring gap 4 subdivides the sensor head 3 into two terminal projections 11 and 12 between which the measuring gap 4 is arranged. These projections 11 and 12 are especially arranged symmetrically to one another.

(16) The measuring gap 4 has a gap axis A and is subdivided into at least two regions in which the measuring gap 4 has a different gap width b1 and b2. The gap axis A may preferably run perpendicular to a sensor axis defined by the sensor housing 2. In a first of the two regions, a first light source 7 is arranged on a wall 10 of the first projection 11, and a first light receiver 8 is arranged on an opposite wall 10 of the second projection 12. The light source 7 and the light receiver 8 form a first signal path which runs perpendicular to the gap axis A. Accordingly, these two elements are to be understood as sensor elements within the meaning of the present disclosure.

(17) In a second of the two regions, a second light source 9 is arranged on a wall of the first projection 11, and a second light receiver 8 is arranged on an opposite wall of the second projection 12. These form a second signal path which runs perpendicular to the gap axis A.

(18) The length of the first signal path is longer than the length of the second signal path, preferably at least 30% longer, especially is twice as long.

(19) The projections 11 and 12 form an end face which is subdivided by the measuring gap 4 into the end face regions 15a and 15b.

(20) Within the sensor head 3, the wall of the sensor head 3 in the region of the end face regions 15a and 15b has a respective condensation trap 13 and 14 in the form of a wall thickness reduction.

(21) A sensor for humidity detection 16, for example a conductivity sensor, may be arranged in the region of at least one of the condensation traps 13 and/or 14.

(22) As an alternative or in addition to the humidity detection sensor 16, a heating unit may be arranged which heats the condensation traps 13 and 14 for the measuring operation during measurement.

(23) The principle of the arrangement of a condensation trap by reducing the wall thickness may be used not only in an absorption sensor but also in a plurality of further sensors. The exemplary embodiment illustrated in FIG. 1-6 therefore serves to explain the inventive idea, but is in no way to be considered a limitation to this type of sensor.

(24) Arranged along the condensation trap 13 and/or on the edge side thereof is a binding material 17 which prevents any formed condensate from running off. This binding material may analogously also be arranged in the condensation trap 6.