DE102009000611A1 - Capacitive measuring probe for use in level sensor, has conductive contact partially exposed by outer coating and insulating jacket, where contact is formed as conductive connection between inner electrode and external volume of area - Google Patents

Abstract

The probe has an outer electrode (14) extending along a level measuring area (10) of the probe and partially surrounding an inner electrode (12). An electrically insulating outer coating (16) completely covers an outer surface of the outer electrode. The outer surface extends along the area. An insulating jacket is arranged between the electrodes. A conductive contact (26) is arranged on the inner electrode and is partially exposed by the outer coating and the jacket. The contact is formed as a conductive connection between the inner electrode and external volume of the area. Independent claims are also included for the following: (1) a level sensor comprising a capacitive measuring probe (2) a method for operating a capacitive measuring probe (3) a method for operating a level sensor with a capacitive measuring probe (4) a method for manufacturing a capacitive measuring probe (5) a method for manufacturing a level sensor.

Description

The The invention relates to a capacitive probe and a level sensor with a capacitive probe. In addition, the concerns Invention Method for operating a capacitive measuring probe and a level sensor with a capacitive probe. Furthermore, the invention relates to manufacturing method for a capacitive probe and a level sensor with a capacitive probe.

State of the art

To the Determining a level of a medium in a container often becomes a level sensor with a capacitive Probe used. A conventional capacitive probe a level sensor usually comprises two as measuring elements serving spaced electrodes. The capacity of the The capacitor formed on the two electrodes is dependent of the permittivity number of the at least one material, with which an intermediate volume between the two electrodes filled is. After immersing the probe in the container medium is thus dependent on the capacity from the permittivity number of the medium and the immersion depth the measuring probe. Based on the capacity of the capacitor is Therefore, the level of the medium detectable.

In general, the two electrodes are made of a metallic material. For a spaced fixation, the two electrodes are often encapsulated with a plastic. The encapsulation of the electrodes with the plastic can be carried out so that at least partial surfaces of the electrodes are not covered by the plastic. In this case, there is a direct contact between the medium and the uncovered sub-surfaces of the electrodes after immersion of the Messson de in the medium. Such a capacitive measuring probe is for example from the DE 195 11 556 C1 known.

It is often advantageous to know the level of a hot and / or chemically aggressive medium in a container. When in the DE 195 11 556 C1 However, measuring the level in such a medium is hardly possible because the direct contact between the partial surfaces of the electrodes and the hot and / or chemically aggressive medium can lead to damage of the electrodes, for example to corrosion, described capacitive probe.

The in the DE 195 11 556 C1 However, described capacitive probe can be developed only at the cost of significantly higher production costs so that the direct contact between the sub-surfaces of the electrodes and the hot and / or chemically aggressive medium is prevented. In particular, interfaces occur between a metal electrode and a plastic surrounding the metal electrode. These interfaces can only be insufficiently sealed against penetration of the liquid medium. In addition, the sealing of such an interface, for example by adhesive or potting compound, relatively laborious and costly.

It is therefore desirable over an easily executable or cost-effective way to determine a level of a hot and / or chemical aggressive medium in a container.

Disclosure of the invention

The The invention provides a capacitive measuring probe with the features of Anspruchs 1, a level sensor with the features of Claim 6, a method for operating a capacitive probe with the features of claim 7, a method for operating a Fill level sensor with the features of claim 8, a Manufacturing method for a capacitive probe with the Features of claim 9 and a manufacturing method for a level sensor having the features of the claim 11th

The The present invention is based on the finding that a direct Contact between a sub-surface of at least two Electrodes of the capacitive probe and the medium, its level is to be determined in a simpler manner preventable by refrained from designing the capacitive measuring probe that the medium into an intermediate volume between the outer electrode and the inner electrode can penetrate. This is executable is when instead of a capacity change of the from the two electrodes formed capacitor, which on a Penetration of the medium into the intermediate volume between the two Electrodes, a Kapizitätsänderung between the outer electrode and the outer volume the outer coating is determined. Both are over the intermediate insulation and the conductive connection formed between the inner electrode and the outer volume of the outer coating conductive contact feasible. Thus, the inventive Capacitive probe can be made and operated so that the risk of a direct contact of the medium with one of the two Electrodes is avoidable.

The present invention allows a complete sheathing of the two electrodes used as measuring elements with plastic, for example with at least one plastic sheath. Thus, the metallic electrodes are themselves at one Immersion in a hot and / or chemically aggressive solution, such as urea, protected against corrosion. In particular, the plastic casing is so executable that no interfaces between the metal of the electrodes and the plastic are formed, which are contacted directly after immersion of the capacitive probe from the medium. The risk of leakage, by means of which penetration of the liquid medium into the measuring probe, in particular into the electronics installation space along the two electrodes, is possible, is thus prevented. The danger of a short circuit through the conductive medium therefore does not exist during operation of the measuring probe.

In In an advantageous embodiment, the conductive comprises Contact a conductive plastic. In particular, can the conductive plastic a from the outer coating and the intermediate insulation outstanding end of the inner electrode cover. Making the conductive contact is thus in a simple way possible. In particular, is at a formed from the conductive plastic conductive Contact a good resistance to the hot and / or chemically aggressive medium guaranteed.

Preferably are the outer coating and / or the intermediate insulation adapted to an intermediate volume between the inner electrode and the outer electrode watertight and / or airtight seal. This is easily done by adding the intermediate volume completely filled with a suitable plastic becomes.

In a further advantageous embodiment comprises the capacitive probe a coaxial cable with a plunge end, wherein the immersion end is formed so that at the immersion end the Inner electrode made of an inner insulating serving as intermediate insulation Serving, the inner cladding from the outer electrode and the outer electrode from an outer Protruding cladding, and being an electrically insulating Plastic at least one of the outer sheath covers exposed end portion of the outer electrode and the Conductive plastic also has an end section covering the electrically insulating plastic. Such Capacitive probe is easy and inexpensive to produce.

Of Furthermore, the capacitive measuring probe can have a measuring device which is designed to provide a voltage between the inner electrode and the outer electrode and an information regarding a capacitance between the outer electrode and one extending along the measuring range of the capacitive probe Outside surface of the outer coating to determine. The electrically insulating outer coating thus acts as protection of the electrodes from the hot and / or chemically aggressive medium and as a virtual electrode whose electrode properties depending on the outside surface wetting substance is. Due to the multifunctionality The outer coating makes it possible to use the capacitive Measuring probe with a comparatively small number of components train. Furthermore, the one described here guarantees Capacitive probe a reliable determination of information in terms of capacity.

In an advantageous development comprises a level sensor the capacitive probe described above, wherein the measuring device the level sensor is designed, taking into account the information determined in terms of capaci ity an immersion depth of the measuring range of the capacitive probe in a medium and / or a level height of the medium set. Thus, the level sensor is particularly suitable good for determining a level of the medium in one Container.

The Benefits described in the paragraphs above are also in the corresponding methods for operating a capacitive Measuring probe and to operate a level sensor with a capacitive probe ensures.

Of Further are described in the paragraphs above Advantages realized by a manufacturing process for such a capacitive probe. In an advantageous development of the manufacturing process this includes the additional Steps: forming a dipping end on a coaxial cable, wherein the immersion end is formed so that at the immersion end the Inner electrode made of an inner insulating serving as intermediate insulation Serving, the inner cladding from the outer electrode and the outer electrode from an outer Protruding the envelope, covering at least one of the outer Envelope exposed end portion of the outer electrode with an electrically insulating plastic to form the electrical insulating outer coating, and covering one out the outer cladding and the inner cladding Encasing outstanding and electrically insulating ones Plastic exposed end of the inner electrode and an end portion of the electrically insulating plastic with a conductive Plastic for attaching the conductive contact to the Internal electrode. The manufacturing method described here is inexpensive to carry out using standard steps.

Appropriate Advantages are also in such a manufacturing method for ensures a level sensor.

Brief description of the drawings

Further Features and advantages of the present invention will become apparent below explained with reference to the figures. Show it:

1A to C is a schematic cross section, a schematic circuit diagram and a coordinate system for illustrating an embodiment of the method for operating the capacitive probe;

2 a schematic representation of an embodiment of the capacitive measuring probe; and

3 a flowchart for illustrating an embodiment of the manufacturing method for a capacitive probe.

embodiments the invention

1A to C show a schematic cross section, a schematic circuit diagram and a coordinate system for illustrating an embodiment of the method for operating a capacitive measuring probe.

In the 1A a capacitive measuring probe shown as a schematic cross-section comprises a measuring range 10 (Level measuring range), through which an inner electrode 12 and an outer electrode 14 run. The two electrodes 12 and 14 extend over an entire length L of the measuring range 10 , In this case, the outer electrode surrounds 14 along the measuring range 10 the inner electrode 12 at least partially. Thus, at least a portion of the inner electrode extends 12 through one of the outer electrode 14 clamped, at least partially enclosed internal volume, the outer electrode 14 For example, it may have a cylindrical section with a round or ellipsoidal cross section through which the inner electrode 12 runs. Preferably, the cylindrical portion has a minimum length equal to the length L.

The outer electrode 14 is along the measuring range 10 from an electrically insulating outer coating 16 surrounded, which is adapted to the outer electrode 14 from an external volume of the measuring range 10 to isolate. Due to the arrangement of the inner electrode 12 in the from the outer electrode 14 at least partially enclosed internal volume surrounds the outer coating 16 also the inner electrode 12 along the measuring range 10 ,

The outer coating 16 serves as protection of the inner electrode 12 and the outer electrode 14 in front of a medium 18 inside a container 20 , in which the measuring range 10 is arranged. On the double protective function of the electrically insulating outer coating 16 will be discussed in more detail below.

An intermediate volume 22 between the inner electrode 12 and the outer electrode 14 is at least partially filled with an electrically insulating material. Preferably, the intermediate volume 22 completely filled with the electrically insulating material. In this way, there is a direct conductive contact between the electrodes 12 and 14 prevented.

At one of the inner volume of the outer electrode 14 protruding end 24 the inner electrode 12 is a conductive contact 26 educated. The conductive contact 26 is for example formed of a conductive plastic, which at least partially from the outer coating 16 and the intermediate insulation protrudes. About the conductive contact 24 is an electrical connection of the inner electrode 12 with the outer volume of the measuring range 10 realized.

In contrast to the inner electrode 12 has the outer electrode 14 no conductive contact with the external volume of the measuring range 10 on. Instead, the outer coating is 16 which has, for example, a plurality of insulating subcomponents, designed such that an outer surface of the outer electrode 14 , which extends along the measuring range 10 extends, is completely covered.

Furthermore, those of the electrically insulating material of the intermediate volume 22 formed intermediate insulation, the outer coating 16 and / or the conductive contact 26 be designed so that the intermediate volume 22 waterproof and / or airtight (hermetic) is sealed. In this way it is preventable that the medium 18 into the intermediate volume 22 penetrates and the electrodes 12 and 14 attacks.

The measuring range 10 with the two electrodes 12 and 14 , the electrically insulating outer coating 16 and in the intermediate volume 22 arranged electrically insulating material can be formed flexible. For example, the measuring range 10 designed as a probe cable. Due to the flexibility of the measuring range 10 can also be in a container 20 with a complex shape of the level of the medium 18 , as described in more detail below, are measured.

Below is the operation of the in 1A schematically illustrated capacitive probe explains:
The capacitive probe is so on the with the medium 18 filled containers 20 arranged that the measuring range 10 the probe with a length L in the interior of the container 20 protrudes. The medium 18 For example, it may be a highly heated and / or chemically aggressive liquid. In particular, the medium 18 be a conductive liquid. That of the medium 18 unfilled residual volume of the interior of the container 20 is filled with a filling gas, for example air or a non-reactive gas.

Preferably, the outer coating comprises 16 a material with a good resistance to the medium 18 , This ensures that the electrodes 12 and 14 through them along the measuring range 10 surrounding outer coating 16 reliable in front of the medium 18 are protected. As will be explained in more detail below, this is the end 24 the inner electrode 12 and the adjacent end portions of the outer electrode 14 and the outer coating 16 completely from the material of the conductive contact 26 covered. Thus, a reliable protection of the in the medium 18 protruding end of the capacitive probe ensures.

The one with the length L in the interior of the container 20 protruding measuring range 10 dives into the medium with an immersion depth h 18 one. Will a voltage not equal to 0 V between the electrodes 12 and 14 created, so loads over the conductive contact 26 also an outer surface 28 the electrically insulating outer coating 16 , which extend along the measuring range 10 extends, at least partially. The outer surface of the electrically insulating outer coating 16 thus acts as a (virtual) counter electrode to the outer electrode 14 , whose electrode properties of the at least one material of an outer volume of the measuring range 10 which is the outer surface 28 wets, depends.

1B FIG. 12 is a schematic circuit diagram for explaining a total capacitance Cges of the outer surface. FIG 28 the electrically insulating outer coating 16 and the outer electrode 14 formed (virtual) capacitor.

The Total capacity Cges is deductible over one Parallel connection of a cable-specific basic capacity C0K with a first series connection and with a second series circuit. The first series connection comprises an outer coating specific Basic capacity C0A and a medium-related capacity CM. The second series connection comprises the outer coating-specific basic capacity C0A and a filling gas-related capacity CF.

The medium-dependent capacity CM is the capacity of a first (virtual) partial capacitor of one with the medium 18 wetted partial surface of the outer surface 28 the electrically insulating outer coating 16 and an associated portion of the outer electrode 14 , The medium-related capacity CM is thus proportional to the immersion depth h.

Accordingly, the filling gas-related capacity CF is the capacity of a second (virtual) partial condenser of one of the filling gas contacted, with the medium 18 non-wetted residual surface of the outer surface 28 the electrically insulating outer coating 16 and an associated portion of the outer electrode 14 , As a result, the fill gas-related capacity CF is proportional to the difference of the length L of the measurement range 10 and the immersion depth is h. Thus, the total capacity Cges is dependent on the immersion depth h.

The (schematic) electrical circuit diagram of 1B is an equivalent circuit diagram. Due to their parallel arrangement, the basic capacitance C0K and C0A can be easily calibrated out by means of an offset adjustment.

1C shows a coordinate system for representing a dependence of the cable-specific basic capacity C0K, the medium-related capacity CM and the total capacity Cges of the immersion depth h. The abscissa corresponds to the immersion depth h. The ordinate indicates the associated capacities C0K, CM and Cges. Since the fill gas-related capacity CF and the outer coating-specific basic capacity C0A are usually negligibly small, they are not discussed.

The Cable-specific basic capacity C0K is independent from the immersion depth h and runs constantly. The medium-conditioned Capacitance CM goes to zero at an immersion depth h against zero. Its maximum value reaches the medium-related capacity CM at a maximum immersion depth h equal to the length L of the measuring range. As h increases, the medium-related capacity increases CM steadily on.

Consequently the total capacity Cges has a significant dependence from the immersion depth h. The total capacity is Cges equal to the cable-specific basic capacity C0K at a Immersion depth h is equal to zero. The same as the immersion depth h Zero and the immersion depth h is equal to the length L of the measuring range the total capacity Cges increases steadily. At the maximum Immersion depth h equal to the length L of the measuring range the total capacity Cges their maximum value. The total capacity Cges can therefore for a reliable setting of the Immersion depth h are evaluated.

Procedural steps for setting the On Diving depth h taking into account the total capacity Cges and a measuring device which is designed to set the immersion depth h taking into account the total capacity Cges, or on the basis of the immersion depth h, the filling level of the medium 18 to determine are for a specialist on the basis of 1C suggested. Subsequently, therefore, such process steps and a corresponding measuring device will not be discussed in more detail.

2 shows a schematic representation of an embodiment of the capacitive probe.

The schematically illustrated capacitive probe comprises a coaxial cable 30 , which at least along a (only partially sketched) measuring range 10 extends. The coaxial cable has an inner electrode 12 , a first insulating (inner) cladding 32 the inner electrode 12 , one of the first insulating cladding 32 surrounding outer electrode 14 and a second insulating (outer) sheath 34 the outer electrode 14 on.

The embodiment of the capacitive probe described here is not on an external electrode 14 limited to a round perimeter. Instead, the circumference of the outer electrode may also be ellipsoidal and / or formed with at least one gap.

The first insulating cladding 32 and the second insulating sheath 34 are formed of an electrically insulating material. The insulating sheaths 32 and 34 may be made of the same material or of at least two different materials. In particular, the second insulating sheath 34 comprise a material which has good resistance to a chemically aggressive medium. For example, an outer surface of the second insulating sheath 34 be coated with the resistant material. Likewise, the second insulating sheath 34 completely formed from the resistant material. The second electrically insulating sheath 34 the outer electrode is, for example, a cable jacket of the coaxial cable.

The second insulating cladding 34 surrounds the outer electrode 14 at least along the measuring range 10 Completely. A direct conductive contact between the outer electrode 14 and an outer volume of the measuring range 10 is thus separated from the second insulating cladding 34 prevented.

A direct electrical contact between the two electrodes 12 and 14 is through the first insulating cladding 32 prevented. Preferably, an intermediate volume between the inner electrode 12 and the outer electrode 14 completely from the first insulating cladding 32 the inner electrode 12 filled.

One end of the coaxial cable 30 , which in the following as immersion 36 is designated, is shaped so that one end 24 the inner electrode 12 from one of the outer electrode 14 protruding internal volume protrudes. The end 24 the inner electrode 12 is also of the material of the first insulating sheath 32 and the material of the second insulating sheath 34 exposed.

Likewise, an end section protrudes 38 the first insulating cladding 32 from the outside of the electrode 14 spanned inside volume. The end section 38 stands thereby at a dipping side surface 40 the outer electrode 14 out. As immersion side surface 40 becomes that of the two annular or ellipsoidal side surfaces of the outer electrode 14 designated which at the immersion end 36 of the coaxial cable 30 lies.

Preferably, one may also be to the immersion side surface 40 adjacent end section 42 the outer electrode 14 of the material of the second insulating sheath 34 be exposed. The immersion end 36 can thus in addition to the end 24 the inner electrode and the end portion 38 the first insulating cladding 32 also the end section 42 the outer electrode 14 include.

On the dive 36 is an electrically insulating plastic 44 so applied that at least one to the immersion side surface 40 adjacent partial area 46 of the end section 38 the first insulating cladding 32 and one to the immersion side surface 40 adjacent end section 48 the second insulating cladding 34 from the insulating plastic 44 are covered. This ensures that the immersion side surface 40 completely from the insulating plastic 44 is covered. If the end section 42 the outer electrode 14 of the material of the second insulating sheath 34 is exposed, also becomes the end section 42 from the insulating plastic 44 completely covered.

The insulating plastic 44 thus forms together with the second electrically insulating sheath 34 an electrically insulating outer coating, which along the measuring range 10 extending outer surfaces and the immersion side surface 40 the outer electrode 14 completely envelop. In this way, it is ensured that during operation of the capacitive probe no conductive contact between the outer electrode 14 and an outer volume of the measuring range 10 is present.

The end 24 the inner electrode 12 is made of the insulating plastic 44 not covered. At least a portion of the end 24 thus protrudes from the insulating plastic 44 out. To have a direct contact of the end 24 with a medium whose level is to be measured in the operation of the capacitive probe, to prevent, which is made of the insulating plastic 44 protruding end 24 from a conductive plastic 50 completely covered. About the conductive plastic 50 is thus a conductive connection between the end 24 and an outer volume of the measuring range 10 guaranteed.

Preferably, the conductive plastic covers 50 the end 24 , one of the insulating plastic 44 uncovered residual area of the end portion 38 the first insulating cladding 32 and one to the end 24 aligned end portion 52 of the insulating plastic 44 from. In this way it is ensured that the inner electrode 12 at the end 24 good in front of a hot and / or chemically aggressive medium of the outer volume of the measuring range 10 is protected.

In particular, at the in 2 illustrated embodiment of the immersion end 36 ensures that no interfaces between the metal of the electrodes and the plastic are formed, which are contacted directly after immersion of the capacitive probe from the medium. Thus, penetration of a liquid medium into the probe can be easily prevented. The risk that penetration of the liquid medium into the electronic installation space damages the electronics is thus eliminated. Furthermore, the measuring arrangement of the medium can also be moved after the adjustment.

3 FIG. 10 is a flow chart illustrating one embodiment of the manufacturing method for a capacitive probe. FIG.

In a step S1, an inner electrode and an outer electrode, which forms the inner electrode at least partially formed. The two electrodes extend at least along a measuring range the capacitive probe produced in further process steps. In a step S2, a between the inner electrode and the Outside electrode disposed electrically insulating intermediate insulation educated.

The For example, steps S1 and S2 may be performed simultaneously Be made by placing contacts on the two electrodes of a coaxial cable be formed, and in this way the two electrodes of the coaxial cable the function of the inner electrode and the outer electrode and an inner wrapper interposed therebetween Function of the intermediate insulation.

Instead of the coaxial cable, a shell structure with the two electrodes and their sheaths can also be produced by means of an extrusion or injection molding process. Subsequently, the shell structure can be used for the further manufacturing process. Such a shell construction ensures the advantage that its individual components in their dimensions and shapes are freely designable. Since the steps for producing a suitable shell structure for a person skilled in the art on the basis of 2 are not further discussed here.

In another step S3 becomes a dipping end on a coaxial cable formed so that at the immersion end of the inner electrode of the inner serving, the inner serving the outer electrode and the outer electrode sticking out of an outer covering.

Subsequently is at least one of the outer wrapping exposed end portion of the outer electrode with a electrically insulating plastic for forming an electrically insulating outer coating covered (step S4). For example, a first injection process the electrically insulating plastic is applied so that the electric insulating plastic, leaving a protruding end the inner electrode has an uncovered outer surface and / or covering a freestanding edge of the outer electrode. The electrically insulating outer coating thus covers an outer surface extending along the measuring area the outer electrode completely off.

Becomes when applying the electrically insulating plastic in the first Injection covered the end of the inner electrode, so can in a subsequent process step, the end of the inner electrode be exposed from the electrically insulating plastic. there will ensure that the outer surfaces and the outer edges of the outer electrode are not from be covered the electrically insulating plastic.

Thereafter, an end of the inner electrode protruding from the outer casing and the inner casing and exposed by the electrically insulating plastic and an end portion of the electrically insulating plastic are covered with a conductive plastic (step S5). In this way, a conductive contact which is at least partially exposed by the outer coating and the intermediate insulation is arranged on the inner electrode, which serves as a conductive connection between the inner electrode and an outer volume of the measuring element area is formed.

Of the Step S5 may be performed by a second Inject the end of the coaxial cable with the conductive one Plastic is covered. This is the conductive plastic directly on the exposed areas of the end of the inner electrode applied.

The Designations of steps S1 to S5 do not specify a chronological order for executing steps S1 to S5. For example For example, steps S1 and S2 after steps S3 to S5 be executed.

The produced by the manufacturing method described here capacitive Measuring probe can be used for the method described above for Operate the capacitive probe can be used. Preferably is doing a level of a medium in a container measured.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19511556 C1 [0003, 0004, 0005]

Claims (11)

Capacitive measuring probe with: an inner electrode ( 12 ); an outer electrode ( 14 ), which extend at least along a measuring range ( 10 ) of the capacitive probe extends and the inner electrode ( 12 ) at least partially surrounds; and an electrically insulating outer coating ( 16 . 34 . 44 ), which extends along the measuring area extending outer surface of the outer electrode ( 14 ) completely covers; characterized by a between the inner electrode ( 12 ) and the outer electrode ( 14 ) arranged electrically insulating intermediate insulation ( 32 ); and one on the inner electrode ( 12 ), from the outer coating ( 16 . 34 . 44 ) and the intermediate insulation ( 32 ) at least partially exposed conductive contact ( 26 ), which serves as a conductive connection between the inner electrode ( 12 ) and an outer volume of the measuring range ( 10 ) is trained. A capacitive probe according to claim 1, wherein the conductive contact ( 26 ) a conductive plastic ( 50 ), and wherein the conductive plastic ( 50 ) one of the outer coating ( 16 . 34 . 44 ) and the intermediate insulation ( 32 ) outstanding end ( 24 ) of the inner electrode ( 12 ) covers. Capacitive probe according to claim 1 or 2, wherein the outer coating ( 16 . 34 . 44 ) and / or the intermediate insulation ( 32 ) are designed to have an intermediate volume ( 22 ) between the inner electrode ( 12 ) and the outer electrode ( 14 ) watertight and / or airtight seal. Capacitive measuring probe according to one of the preceding claims, wherein the capacitive measuring probe is a coaxial cable ( 30 ) with a dipping end ( 36 ), wherein the immersion end ( 36 ) is formed so that at the immersion end ( 36 ) the inner electrode ( 12 ) from an intermediate insulation ( 32 ) serving inner envelope ( 32 ), the inner envelope ( 32 ) from the outer electrode ( 14 ) and the outer electrode ( 14 ) from an outer envelope ( 34 protrude) and wherein an electrically insulating plastic ( 44 ) at least one of the outer envelope ( 34 ) exposed end portion ( 42 ) of the outer electrode ( 14 ) and the conductive plastic ( 50 ) additionally an end section ( 52 ) of the electrically insulating plastic ( 44 ) covers. Capacitive measuring probe according to one of the preceding claims, wherein the capacitive measuring probe has a measuring device, which is designed, a voltage between the inner electrode ( 12 ) and the outer electrode ( 14 ) and an information regarding a capacitance (Cges, CM) between the outer electrode ( 14 ) and an outer surface extending along the measuring range of the capacitive measuring probe ( 28 ) of the outer coating ( 16 . 34 . 44 ) to investigate. Level sensor with a capacitive measuring probe according to claim 5, wherein the measuring device of the filling level sensor is designed, taking into account the determined information regarding the capacitance (Cges, CM) an immersion depth (h) of the measuring range ( 10 ) of the capacitive probe into a medium ( 18 ) and / or a fill level of the medium ( 18 ). Method for operating a capacitive measuring probe with an inner electrode ( 12 ), an outer electrode ( 14 ), which extend at least along a measuring range ( 10 ) of the capacitive probe extends and the inner electrode ( 12 ) at least partially surrounds an electrically insulating outer coating ( 16 . 34 . 44 ), which extends along the measuring range ( 10 ) extending outer surface of the outer electrode ( 14 ), one between the inner electrode ( 12 ) and the outer electrode ( 14 ) arranged electrically insulating inter mediate insulation ( 32 ) and one on the inner electrode ( 12 ), from the outer coating ( 16 . 34 . 44 ) and the intermediate insulation ( 32 ) at least partially exposed conductive contact ( 26 ), which serves as a conductive connection between the inner electrode ( 12 ) and an outer volume of the measuring range ( 10 ), comprising the step of: applying a voltage between the inner electrode ( 12 ) and the outer electrode ( 14 ); characterized by determining information regarding a capacitance (Cges, CM) between the outer electrode ( 14 ) and one along the measuring range ( 10 ) of the capacitive probe extending outer surface ( 28 ) of the outer coating ( 16 . 34 . 44 ). Method for operating a filling level sensor with a capacitive measuring probe with an inner electrode ( 12 ), an outer electrode ( 14 ), which extend at least along a measuring range ( 10 ) of the capacitive probe extends and the inner electrode ( 12 ) at least partially surrounds an electrically insulating outer coating ( 16 . 34 . 44 ), which extends along the measuring range ( 10 ) extending outer surface of the outer electrode ( 14 ), one between the inner electrode ( 12 ) and the outer electrode ( 14 ) arranged electrically insulating intermediate insulation ( 32 ) and one on the inner electrode ( 12 ), from the outer coating ( 16 . 34 . 44 ) and the intermediate insulation ( 32 ) at least partially exposed conductive contact ( 26 ), which serves as a conductive connection between the inner electrode ( 12 ) and an outer volume of the measuring range ( 10 ) is formed, with the steps: Determining information regarding a capacitance (Cges, CM) between the outer electrode ( 14 ) and one along the measuring range ( 10 ) of the capacitive probe extending outer surface ( 28 ) of the outer coating ( 16 . 34 . 44 ) according to the method of claim 7; and determining an immersion depth (h) of the measuring range ( 10 ) of the capacitive probe into a medium ( 18 ) and / or a fill level of the medium ( 18 ) taking into account the determined information regarding the capacity (Cges, CM). Manufacturing method for a capacitive measuring probe with the steps: forming an inner electrode ( 12 ) and an outer electrode ( 14 ), wherein the outer electrode ( 14 ) at least along a measuring range ( 10 ) of the capacitive probe extends and the inner electrode ( 12 ) at least partially surrounds (S1); and forming an electrically insulating outer coating ( 16 . 34 . 44 ), which extends along the measuring range ( 10 ) extending outer surface of the outer electrode ( 14 ) completely covers (S4); characterized by forming a between the inner electrode ( 12 ) and the outer electrode ( 14 ) arranged electrically insulating intermediate insulation ( 32 ) (S2); and attaching one of the outer coating ( 16 . 34 . 44 ) and the intermediate insulation ( 32 ) at least partially exposed conductive contact ( 26 ) on the inner electrode ( 12 ), which serves as a conductive connection between the inner electrode ( 12 ) and an outer volume of the measuring range ( 10 ) is formed (S5). A manufacturing method according to claim 9, comprising the additional steps of: forming a dip ( 36 ) on a coaxial cable ( 30 ), with the immersion end ( 36 ) is formed so that at the immersion end ( 36 ) the inner electrode ( 12 ) from an intermediate insulation ( 32 ) serving inner envelope ( 32 ), the inner envelope ( 32 ) from the outer electrode ( 14 ) and the outer electrode ( 14 ) from an outer envelope ( 34 protrude (S3); Covering at least one of the outer cover ( 34 ) exposed end portion ( 42 ) of the outer electrode ( 14 ) with an electrically insulating plastic ( 44 ) for forming the electrically insulating outer coating ( 16 . 34 . 44 ); and covering one of the outer sheath ( 34 ) and the inner envelope ( 32 ) and of the electrically insulating plastic ( 44 ) exposed end ( 24 ) of the inner electrode ( 12 ) and an end section ( 52 ) of the electrically insulating plastic ( 44 ) with a conductive plastic ( 50 ) for attaching the conductive contact ( 26 ) on the inner electrode ( 12 ). A manufacturing method of a liquid level sensor, comprising the steps of: forming a capacitive measuring probe according to one of claims 9 or 10; and forming a measuring device, which is designed to generate a voltage between the inner electrode ( 12 ) and the outer electrode ( 14 ), an information regarding a capacitance (Cges, CM) between the outer electrode ( 14 ) and one along the measuring range ( 10 ) of the capacitive probe extending outer surface ( 28 ) of the outer coating ( 16 . 34 . 44 ) and taking into account the determined information regarding the capacitance (Cges, CM) an immersion depth (h) of the measuring range ( 10 ) of the capacitive probe into a medium ( 18 ) and / or a fill level of the medium ( 18 ).