LEVEL GAUGE

Description

[0001] The invention relates to an electrical level measuring device in which a probe is immersed in a medium contained in a container and the level of the medium is derived via its electrical properties. A generic measuring device is described in DE 30 46 915 A1.

[0002] Such level gauges are known, for example, from patent EP 1 544 585 B1. To achieve sufficient tightness in such level gauges, conically shaped sealing elements are used, which, however, in the prior art can only be reliably positioned using complicated devices. Level gauges similar to those of German patent DE 30 46 915 A1 are disclosed in EP 2 381 228 B1 and US 5,975,102 A. Probes for gauges that have sealing elements are disclosed in US 10,072,960 B2, EP 1 825 231 B1, EP 1 597 544 B1, and US 2014 / 125512 A1.

[0003] The object of the invention is to propose a level measuring device with a simple and safe device for attaching and holding a sealing element.

[0004] The problem is solved by an electrical assembly according to independent claim 1, an electrical level measuring device according to independent claim 7, and by a method according to independent claim 10.

[0005] An electrical assembly according to the invention for an electrical level measuring device for measuring the level of a medium in a container comprises: an electrically conductive probe configured for transmitting an electrical signal, wherein the probe is configured to be immersed in the medium, the probe having a central region and two end regions in the axial direction, the probe having a plastic coating in the central region; a process connection configured to support the probe radially, the probe projecting section by section through an open end of the process connection into a lumen of the process connection; wherein the probe is radial to the process connection by means of a rotationally symmetrical, in particular ring-shaped or tube-shaped, sealing element, wherein the sealing element is materially bonded to the plastic coating by means of a welding process, in particular a mechanical friction welding process such as rotary friction welding, rotary vibration welding or ultrasonic welding.

[0006] In one embodiment, the probe is mounted radially opposite the process connection by means of the sealing molding.

[0007] In one embodiment, the sealing component has a stop which is designed to act against a stop of the process connection.

[0008] In one embodiment, the probe is radially and / or axially mounted in an end region to be turned away from the medium by a bearing device that is rotatably fixed in at least one direction of rotation.

[0009] An axial bearing can additionally or alternatively be provided by a spring device, which acts, for example, against a radial projection or engagement of the probe.

[0010] In one embodiment, the sealing molded part is made of a thermoplastic or manufactured from a thermoplastic.

[0011] In one embodiment, the plastic coating is applied to an electrically conductive probe core by extrusion.

[0012] An electrical level measuring device according to the invention for measuring the level of a medium in a container comprises an electrically conductive probe configured for transmitting an electrical signal, wherein the probe is configured to be immersed in the medium, the probe having a central region and two end regions in the axial direction, the probe having a plastic coating in the central region; an electronic measuring / operating circuit configured for generating and evaluating electrical signals and for providing level measurements; a housing in which, for example, the electronic measuring / operating circuit is arranged; a process connection attached to the housing, which is configured to support the probe radially, the probe projecting section by section through an open end of the process connection into a lumen of the process connection; wherein the probe is clamped radially relative to the process connection by means of a sealing element, in particular annular or tubular, wherein the sealing element is materially bonded to the plastic coating by means of a welding process, in particular a mechanical friction welding process such as rotary friction welding, rotary vibration welding or ultrasonic welding.

[0013] In one embodiment, the electronic measuring / operating circuit is configured to derive the fill level of the medium from a measuring current, or a measuring capacitance, or a signal transit time of an electrical pulse.

[0014] In one embodiment, the electronic measuring / operating circuit is connected to an end area of ​​the probe facing the housing by means of an electrically conductive clamping device.

[0015] In an inventive method for manufacturing a level measuring device according to the invention, wherein a probe has a central region with a plastic coating in the axial direction, wherein in a first process step a rotationally symmetrical, for example ring-shaped or tube-shaped sealing element is guided over one end of the probe to the central region, wherein the sealing element and the plastic coating form an interference fit with each other, wherein in a second process step a relative movement such as a rotational movement is established between the sealing element and the probe, wherein the sealing element and the plastic coating are joined together section by section by friction in a materially bonded manner.

[0016] The invention will be described below using exemplary embodiments. Fig. 1 outlines two exemplary level measuring devices according to the invention; Fig. 2outlines an exemplary electrical assembly according to the invention with a bearing device for the probe. Fig. 3 outlines an exemplary application of a level measuring device according to the invention; Fig. 4 outlines an exemplary procedure for manufacturing a level measuring device.

[0017] Fig. 1 Figure 1 shows two longitudinal sections through exemplary level measuring devices 1 according to the invention, comprising a housing 30, an electronic measuring / operating circuit 20 arranged in the housing, and an exemplary assembly 1.1 according to the invention with an electrically conductive probe 10 and a process connection 40. Alternatively, the electronic measuring / operating circuit can also be arranged outside the housing and is electrically connected to the probe via an interface. The electronic measuring / operating circuit is configured to generate and evaluate electrical signals and to provide level measurements.

[0018] The process connection is attached to the housing and designed to radially clamp or support the probe 10. The probe can also be axially and / or rotationally supported in at least one direction of rotation via the process connection. A further radial support point is provided by the bearing device 70, as shown here; see also [reference]. Fig. 2 The probe extends through an open end 41 of the process connection into a lumen 42 of the process connection, the process connection is sealed against a medium by means of a sealing molded part 50.

[0019] According to the invention, the probe has a plastic coating 13 which is applied to an electrically conductive probe core 10.1 in a central region 11. Furthermore, according to the invention, the sealing element 50 and the plastic connection 13 are metallurgically bonded to the plastic coating by means of a mechanical friction welding process such as rotary friction welding, rotary vibration welding, or ultrasonic welding.

[0020] The sealing element 50 has a stop 51 which acts against a stop 43 of the process connection.

[0021] In the case of a capacitive level sensor as shown on the left, the level sensor can have an electrical insulator 60 at an end 12.1 facing away from the housing, which electrically isolates the medium from the probe. In the case of a conductive level sensor as shown on the right, the end 12.1 facing away from the housing remains free of an electrically insulating material, so that it can come into electrical contact with the medium.

[0022] The electronic measuring / operating circuit can be connected to an end area of ​​the probe facing the housing by means of an electrically conductive clamping device, as shown here.

[0023] Fig. 2Figure 1 shows an exemplary embodiment of a probe 10 bearing arrangement, wherein a bearing device 70 is provided in the process connection 40, which radially and / or axially supports the probe at an end of the probe 12.2 facing the housing. The bearing device itself is rotationally fixed in the process connection in at least one direction of rotation, but as shown here, it can also be rotationally fixed in both directions. An axial support of the probe can additionally or alternatively be provided by a spring device, which acts, for example, against a radial projection or engagement of the probe.

[0024] Fig. 3This outlines an application of an exemplary level gauge 1, which is attached to a container B and extends into a lumen of the container, so that it is partially immersed in a medium located in the container. The level of the medium can then be determined, for example, by conductivity or capacitance measurements.

[0025] Fig. 4 outlines a method 100 for manufacturing a level measuring device according to the invention, wherein a probe 10 is provided with a plastic coating 13 in an axial direction at a central region 11, wherein in a first process step 101 a rotationally symmetrical, for example ring-shaped or tube-shaped sealing element 50 is guided over one end of the probe to the central region, wherein the sealing element and the plastic coating form an interference fit with each other, wherein in a second process step 102 a relative movement such as a rotational movement is established between the sealing element and the probe, wherein the sealing element and the plastic coating are joined together section by section by friction in a materially bonded manner. Reference symbol list

[0026] 1 Level gauge 10 Probe 10.1 Probe core 11 Center section 12 End section 12.1 End away from housing 12.2 End towards housing 13 Plastic coating 20 Electronic measuring / operating circuit 30 Housing 40 Process connection 41 Open end 42 Lumen 43 Stop 50 Sealing part 51 Stop 60 Electrical insulation 70 Bearing device 80 Electrically conductive clamping device 100 Process 101 First process step 102 Second process step B Container M Medium

Claims

1. An electrical assembly (1.1) for an electrical fill level measuring device (1) for measuring a fill level of a medium (M) in a container (B), comprising: - An electrically conductive probe (10) configured to conduct an electrical signal, wherein the probe (10) is designed to be immersed in the medium (M), wherein the probe (10) has a center area (11) and two end areas (12) in the axial direction, and wherein the probe (10) has a plastic coating (13) in the center area; - a process connection (40) which is configured to radially mount the probe (10), wherein sections of the probe (10) protrude beyond an open end (41) of the process connection (40) into a lumen (42) of the process connection (40); and - a rotationally symmetrical molded sealing part (50) which has a permanent material bond with the plastic coating (13) through a welding process, characterized in that the probe (10) is arranged radially opposite the process connection (40) using the molded sealing part (50).

2. The electrical assembly (1.1) as claimed in claim 1, wherein the probe (10) is mounted radially opposite the process connection (40) using the molded sealing part (50).

3. The electrical assembly (1.1) as claimed in claim 1 or 2, wherein the molded sealing part (50) has a limit stop (51) which is configured to act against a limit stop (43) of the process connection (40).

4. The electrical assembly (1.1) as claimed in one of claims 1 to 3, wherein the probe (10) is radially and / or axially mounted in an end area (12.2) facing away from the medium (M) using a mounting device (70) which is rotationally fixed at least in one direction of rotation.

5. The electrical assembly (1.1) as claimed in one of claims 1 to 4, wherein the molded sealing part (50) has a thermoplastic or is made from thermoplastic.

6. The electrical assembly (1.1) as claimed in one of claims 1 to 5, wherein the plastic coating (13) is applied to an electrically conductive probe core (10.1) of the probe (10) by means of extrusion.

7. An electrical fill level measuring device (1) for measuring a fill level of a medium (M) in a container (B), comprising: - An electrical assembly (1.1) as claimed in one of claims 1 to 6, - an electronic measuring / operating circuit (20) configured to generate and analyze electrical signals and to provide values related to the fill level; - a housing (30) in which the electronic measuring / operating circuit (20) or a connection for the electronic measuring / operating circuit (1.1) is arranged.

8. The fill level measuring device (1) as claimed in claim 7, wherein the electronic measuring / operating circuit (20) is configured to deduce the fill level of the medium (M) from a measurement current or from a measurement capacity or from a signal duration of an electrical pulse.

9. The fill level measuring device (1) as claimed in claim 7 or 8, wherein the electronic measuring / operating circuit (20) is connected to an end area (12.2) of the probe (10) facing toward the housing (30) by means of an electrically conductive clamping device (80).

10. A method (100) for producing a fill level measuring device (1) as claimed in one of claims 7 to 9, wherein a probe (10) has a center section (11) with a plastic coating (13) in the axial direction, wherein in a first process step (101), a rotationally symmetrical molded sealing part (50) is guided over an end of the probe (10) to the center area (11), wherein the molded sealing part (50) and the plastic coating (13) create a press fit with each other, and wherein in a second process step (102), a relative movement is initiated between the molded sealing part (50) and the probe (10), wherein a permanent material bond is formed between sections of the molded sealing part (50) and the plastic coating (13) through friction.