DE102019214647A1 - Sensor system for the quantitative measurement of a liquid, container and motor vehicle - Google Patents

Abstract

The invention relates to a sensor system (10) for the quantitative measurement of a liquid (F) with: (a) a capacitor (11) with at least two elongated sensor conductors (12) electrically isolated from one another, each of the at least two elongated sensor conductors (12) having an elongated Current conductor (14) and an electrical insulator (15) arranged around a circumference of the elongated current conductor (14), (b) a measuring circuit (18) which is connected to the capacitor (11) to measure the conduction capacitance of the capacitor (11) is, and (c) an evaluation unit (19) which is connected to the measuring circuit (18) for evaluating measurement results of the measurement of the measuring circuit (18), wherein (d) the elongated current conductors (14) are designed as wires and the at least two elongated sensor conductors (12) are twisted with one another, so that an air space (13) is formed at intervals between the electrical insulators (15) of the at least two elongated sensor conductors (12) i st, or (e) the elongated current conductors (14) are designed as flat conductors or round conductors and the at least two elongated sensor conductors (12) are connected to one another by at least one web (14) at a distance transverse to the longitudinal extension of the elongated sensor conductors (12), so that at least one air space (13) is formed in the distance between the electrical insulators (15) of the at least two elongated sensor conductors (12). The invention also relates to a container (20), in particular a motor vehicle (30), with such a sensor system (10) and a motor vehicle (30) with such a container (20).

Description

The invention relates to a sensor system for the quantitative measurement of a liquid, a container, in particular a motor vehicle, with such a sensor system and a motor vehicle with such a container.

DE 689 21 346 T2 describes an elongated sensor arrangement with two conductors of a configuration by means of which two events can be detected and differentiated from one another.

DE 198 41 717 A1 describes an electrical sensor cable for detecting the occurrence of fluid substances with electrical conductivity. The electrical sensor line has electrical sensor conductors which are surrounded by conductor insulation with insulation gaps. The electrical sensor lines are twisted around a filler. The bridging of the electrical sensor lines at the insulation gaps by means of a fluid substance with electrical conductivity can be determined by means of the electrical sensor conductors.

DE 38 73 968 T2 describes a liquid detection cable having an inner conductor and outer conductors coaxial therewith. A non-porous dielectric material is twisted around the inner conductor and defines an air space for containing liquid. The outer conductor consists of an open-braided structure that allows liquid to enter. A liquid can be detected by changing the impedance of the liquid detection cable.

The object of the invention is to provide a cost-effective, precise and easily usable sensor system by means of which liquids in a container can be detected and measured quantitatively.

The above object is achieved by the subjects of the claims, in particular by a sensor system according to claim 1, a container according to claim 5 and a motor vehicle according to claim 10. Further advantages and details of the invention emerge from the subclaims, the description and the drawings. Features and details that are described in connection with the sensor system according to the invention naturally also apply in connection with the container according to the invention and the motor vehicle according to the invention and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is or can always be made to each other.

According to a first aspect of the invention, the object set out at the beginning is achieved by a sensor system for the quantitative measurement of a liquid with: (a) a capacitor with at least two elongated sensor conductors electrically isolated from one another, each of the at least two elongated sensor conductors having an elongated current conductor and one around one The circumference of the elongated conductor has an electrical insulator arranged around it, (b) a measuring circuit which is connected to the capacitor for measuring the conduction capacitance of the capacitor, and (c) an evaluation unit which is connected to the measuring circuit for evaluating measurement results of the measurement of the measuring circuit , wherein (d) the elongated current conductors are designed as veins and the at least two elongated sensor conductors are twisted together so that an air space is formed at intervals between the electrical insulators of the at least two elongated sensor conductors, or (e) the elongated Current conductors are designed as flat conductors or round conductors and the at least two elongated sensor conductors are connected to one another by at least one web at a distance transverse to the longitudinal extension of the elongated sensor conductors, so that at least one air space is formed in the distance between the electrical insulators of the at least two elongated sensor conductors.

The two embodiments of the capacitor have in common that they are inexpensive to manufacture and can be flexibly arranged in a container without changing the distances between the sensor conductors and thus maintaining the size of the air spaces, so that the capacitors provide a precise and therefore reliable Measurement can also be carried out after it has been laid, for example in a container of a motor vehicle. In the embodiment of the capacitor with the wires as elongated current conductors, the stability of the capacitor is achieved with the continuity of the air spaces formed along its length by the twisting of the elongated sensor conductors. In the embodiment of the capacitor with the flat conductors or round conductors as an elongated current conductor, the stability of the capacitor comes about with the continuity of the at least one air space formed along its length through the webs. The round conductors can also be designed as veins. In this case, however, the wires or elongated sensor conductors are not twisted with one another.

The sensor system according to the invention can be used in many different systems and environments such as, for example, in components of buildings, machines, ships, aircraft, motor vehicles and the like.

When the air spaces fill with a liquid, the liquid acts as a dielectric between the elongated conductors of the capacitor. By having the liquid as a If the dielectric has a different permittivity than the dielectric air, the conduction capacitance of the capacitor changes. From the change in the line capacitance of the condenser, conclusions can be drawn about the amount of liquid in the air spaces of the condenser or, in other words, a quantitative determination can be made.

By means of the measuring circuit, the line capacitance of the capacitor can be converted into a measurable variable, such as, for example, a frequency, a voltage or a current. The measuring circuit can also be designed to charge the capacitor. The measuring circuit can be arranged in the evaluation unit. The evaluation unit is used to interpret the measurable variable output by the measuring circuit. The evaluation unit can in particular be evaluation electronics. The evaluation unit can be set up, for example, to determine an amount of liquid in a container on the basis of the measured, measurable variable. The evaluation unit can be calibrated manually or automatically to the permittivity of a liquid to be measured. This makes it possible to provide a particularly precise quantitative level detection in a container.

Copper, aluminum and other conductive metals, for example, can be used as electrical current conductors. For example, PVC, PTFE and the like can be used as electrical insulators. The electrical current conductors can be completely electrically isolated from one another. The ends of the electrical current conductors are therefore not connected to one another. Furthermore, first longitudinal ends of the conductors can be connected to the measuring circuit and second longitudinal ends of the conductors can have sealing elements for sealing or electrical insulation from the environment in order to avoid a short circuit due to contact with liquid.

The at least two elongated sensor conductors are preferably twisted together at a contactless distance transversely to the longitudinal extension of the elongated sensor conductors, so that an air space is formed between each two contact points at which the electrical insulators of the at least two elongated sensor conductors make contact.

The measuring circuit is preferably an astable trigger circuit. The astable multivibrator makes it possible to convert the line capacitance of the capacitor into a frequency that can be evaluated by means of the evaluation unit.

It is also preferred that one of the at least two elongated current conductors is connected to a ground. As a result, the line capacitance of another of the at least two elongated current conductors can be measured to ground.

It is also preferred that at least one elongated heating current conductor is arranged on the at least two elongated sensor conductors. In particular, the heating current conductor cannot be electrically insulated. This makes it possible to detect condensation on the condenser. The sensor system can be set up to supply the heating current conductor with current at predetermined times or at times at which the line capacitance of the capacitor increases, for example by a defined value. If the increased line capacity was caused by condensation water on the condenser, this can be determined in a simple manner by heating up the heating current conductor, since the condensation water evaporates and the change in the line capacity of the condenser based on the condensation water is reversed. This means that incorrect evaluations by the evaluation unit can be ruled out. The heating current conductor can, for example, be twisted together with the elongated sensor conductors.

According to a second aspect of the invention, the object set out at the beginning is achieved by a container, in particular for a motor vehicle, with a sensor system according to the invention. The container can be, for example, a fuel tank, a washer fluid container, a brake fluid container or the like.

The container is preferably a battery housing. The battery housing can be a battery module housing with a plurality of battery cells. In this way, liquid, in particular water, that reaches the battery cells directly can be measured. Alternatively, the battery housing can be a battery housing with a plurality of battery modules in which battery cells are arranged. As a result, the liquid in the battery modules can be inferred indirectly by measuring the liquid in the battery housing. The measurement of liquid, in particular water, penetrating into the battery of the motor vehicle, in particular a traction battery of the motor vehicle, is indicated for safety reasons. Despite the sealing of the battery cells from the environment, the ingress of liquid into the battery housing or into the battery cells cannot be completely prevented. However, if too much liquid gets to the battery cells, the battery may be defective, and in the worst case, the battery may even catch fire. With the system according to the invention, such a dangerous situation can be recognized at an early stage in order to initiate appropriate countermeasures in good time.

It is also preferred that the at least two elongated sensor conductors are arranged in the form of a loop on a bottom of the container. Thanks to the high flexibility with constant distance or constant air spaces between the elongated sensor conductors, the arrangement can be achieved in the form of a loop. A large area of the bottom of the container can be recorded in a structured manner in the form of a loop in order to ensure precise measurement of the liquid. A plurality of capacitors in the form of loops can also be arranged on the bottom of the container in order to cover a larger area on the bottom or to measure different liquid levels. In another application example, in which the condenser is not laid on the floor, the condenser can, for example, weighed down with a weight, be hung in a container in order to measure the liquid level.

It is further preferred that end sections of the at least two elongated sensor conductors extend from a bottom of the container in the direction of a height of the container and that longitudinal ends of the end sections of the at least two elongate sensor conductors are not electrically insulated. For this purpose, the end sections or the longitudinal ends of the end sections of the elongated sensor conductors can be attached to a container wall, for example. Until the liquid reaches the electrically non-insulated longitudinal ends, the liquid level of the container can be measured by means of the change in the conduction capacitance of the capacitor. As soon as the liquid reaches the electrically non-insulated longitudinal ends, there is also a conduction of electrical current between the current conductors. In this way, a critical liquid level can be reliably determined.

In addition, it is preferred that two capacitors are connected to the measuring circuit, the two capacitors extending with elongated sensor conductors of different lengths within the container from an upper side of the container in the direction of the bottom of the container and being spaced from the bottom, and that the Evaluation unit for automatic calibration of a quantitative level detection by means of the resulting difference in length between the elongated sensor conductors of one of the two capacitors and the elongated sensor conductors of the other of the two capacitors, a length difference is formed. The length difference can be stored in a memory unit of the evaluation unit. In addition, a conveying means, for example a mechanical elevator, can be provided, by means of which the capacitors can be lowered in the direction of the floor and / or raised in the direction of the top. The evaluation unit can be set up to control the conveying means. By providing two capacitors with the difference in length, automatic calibration can be carried out and manual calibration can be dispensed with.

According to a third aspect, the invention achieves the object set out at the beginning by means of a motor vehicle with a container according to the invention.

• 1 eine schematische Ansicht einer ersten Ausführungsform eines erfindungsgemäßen Sensorsystems,
• 2 einen Querschnitt durch den Kondensator der ersten Ausführungsform des erfindungsgemäßen Sensorsystems aus 1,
• 3 eine schematische Ansicht einer zweiten Ausführungsform eines erfindungsgemäßen Sensorsystems,
• 4A eine Schnittansicht entlang des Schnittes X-X durch die länglichen Sensorleiter aus der 3,
• 4B eine alternative Ausführungsform der länglichen Sensorleiter aus 4A,
• 5 eine schematische Ansicht einer Ausführungsform eines erfindungsgemäßen Behältnisses, und
• 6 eine schematische Ansicht einer Ausführungsform eines erfindungsgemäßen Kraftfahrzeuges.

The invention is explained in more detail below with reference to the accompanying drawing. All of the features emerging from the claims, the description or the figure, including structural details, can be essential to the invention both individually and in any various combinations. It shows:

• 1 a schematic view of a first embodiment of a sensor system according to the invention,
• 2 a cross section through the capacitor of the first embodiment of the sensor system according to the invention 1 ,
• 3rd a schematic view of a second embodiment of a sensor system according to the invention,
• 4A a sectional view along the section XX through the elongated sensor conductor from FIG 3rd ,
• 4B an alternative embodiment of the elongated sensor conductor 4A ,
• 5 a schematic view of an embodiment of a container according to the invention, and
• 6th a schematic view of an embodiment of a motor vehicle according to the invention.

1 shows a schematic view of a first embodiment of a sensor system according to the invention 10 . The sensor system according to the invention 10 exhibits as a capacitor 11 two elongated sensor conductors arranged parallel to one another 12th , 12.2 on. The elongated sensor conductors 12th , 12.2 each have elongated conductors 14th , 14.2 on, each by an electrical insulator 15th , 15.2 (please refer 2 ) are surrounded. The elongated conductor 14th , 14.2 are designed as flat cables in this first embodiment and aligned parallel to each other. Alternatively, the elongated conductor 14th , 14.2 be designed as a round conductor, for example as veins.

Between the elongated sensor conductors 12th , 12.2 is a plurality of webs 17th , 17.2 , 17.3 , 17.4 arranged that a uniform distance between the elongated sensor conductors 12th , 12.2 produce. Alternatively, one can be the length of the elongated Sensor conductor 12th , 12.2 after a continuous web between the elongated sensor conductors 12th , 12.2 be arranged. The bridges 17th , 17.2 , 17.3 , 17.4 or the continuous web can, for example, be integral with the electrical insulators 15th , 15.2 be. The web can for example be made of the insulating material of the electrical insulators 15th , 15.2 consist.

Between the bridges 17th , 17.2 , 17.3 , 17.4 is a multitude of airspaces 13th formed, the air spaces 13th , 13.2 , 13.3 are designated by way of example. The distance between the bars 17th , 17.3 is larger than that between the other closest webs, so that the capacitor 11 with greater flexibility in this area along a corner of a floor 21 a container 20th is relocated. The floor 21 For example, a housing bottom, in particular a metallic housing bottom, of a container designed as a battery housing 20th be.

First longitudinal ends of the elongated sensor conductor 12th , 12.2 are with a measuring circuit 18th an evaluation unit 19th connected. One of the first longitudinal ends can also be connected to ground. By means of the measuring circuit 18th , which in the present case is designed as an astable multivibrator circuit, a line capacitance of the capacitor can 11 converted into a frequency and sent to the evaluation unit 19th be transmitted. A change in the line capacitance can suggest that it is on the ground 21 Fluid has accumulated. Because the liquid gets into the air spaces 13th , 13.2 , 13.3 and has a different permittivity than the air displaced by the moisture. The evaluation unit can be calibrated to the liquid 19th make a quantitative evaluation of the moisture.

Second longitudinal ends of the elongated sensor conductor 12th , 12.2 are each with a sealing element 16 , 16.2 sealed or electrically isolated. Because the elongated sensor conductor 12th , 12.2 in the present embodiment directly on a floor 21 are arranged on which the liquid to be measured collects, this creates a parasitic resistance between the elongated sensor conductor 12th , 12.2 avoided.

The condenser 11 can be in particular in the form of a loop on the floor 21 be arranged around much of the floor 21 to cover in a metrologically structured manner. Furthermore, the capacitor 11 in this first embodiment with the elongated current conductors designed as flat conductors 14th , 14.2 parallel to the ground 21 be arranged or with one of these on the floor 21 (spaced by one of the electrical insulators 15th ) rest. This is in the cross section of the capacitor 11 in 2 shown.

2 shows a cross section through the capacitor of the first embodiment of the sensor system according to the invention 10 out 1 , the capacitor 11 with its elongated current conductors designed as flat conductors 14th , 14.2 parallel to the ground 21 is arranged or with the elongated conductor 14th on the floor 21 (spaced by the electrical insulator 15th ) rests.

3rd shows a schematic view of a second embodiment of a sensor system according to the invention 10 . The electric current conductors are different from the first embodiment 14th , 14.2 (which are not shown in this illustration) designed as wires. The electric current conductors 14th , 14.2 are also electrical insulators of this 15th , 15.2 (not shown in this illustration). The electrical sensor conductors 12th , 12.2 are with their electrical conductors 14th , 14.2 twisted at a defined and equal distance from one another. This same distance advantageously also changes when the capacitor is laid 11 Not. Between every two contact points where the electrical insulators are 15th , 15.2 the elongated sensor conductor 12th , 12.2 contact are airspaces 13th of what the air spaces 13th , 13.2 , 13.3 are designated, formed. The second embodiment of the sensor system is opposite to the first embodiment 10 particularly flexible for laying on the floor 21 . The functional principle of the measurement otherwise corresponds to that already with reference to 1 described principle.

4A shows a sectional view along the section XX through the elongated sensor conductor 12th , 12.2 from the 3rd . The sensor conductors can be seen here 12th , 12.2 with their conductors designed as cores 14th , 14.2 and electrical insulators 15th , 15.2 . The elongated sensor conductors 12th , 12.2 are, with the exception of points of contact at the contact points of the twist, twisted with one another at a contactless distance transversely to their longitudinal extent, so that an air space between them 13th is trained. The electric field of the capacitor is due to a limitation of the air space 13th with dashed lines in the electrical insulators 15th , 15.2 at the level of the conductor 14th , 14.2 indicated. In general, the airspace lies 13th or are the air spaces 13th in the electric field of the capacitor 11 or between the conductors 14th , 14.2 .

4B Figure 3 shows an alternative embodiment of the elongated sensor conductors 12th , 12.2 out 4A . Unlike in 4A need the sensor wire 12th , 12.2 namely not to be twisted together at a contactless distance to form an air space 13th to train. As in 4B shown, the sensor conductors 12th , 12.2 also touch one another, in particular lie predominantly or completely against one another, and due to the geometry of the round sensor conductors 12th , 12.2 Clearances between the electrical insulators 15th , 15.2 exhibit. The in 4B Airspaces 13th , 13.2 in the indicated electric field of the capacitor 11 at distances between the electrical insulators 15th , 15.2 . As soon as a liquid enters one of these air spaces 13th , 13.2 reaches, the line capacitance of the capacitor changes here too 11 . Incidentally, such air spaces are 13th , 13.2 also at the contact points of the twisted sensor cables 12th , 12.2 out 4A formed, since they also bear against one another there at the contact point.

5 shows a schematic view of an embodiment of a container according to the invention 20th with a bottom 21 . The sensor system 10 has two capacitors 11 , 11.2 with twisted electrical sensor conductors 12th on, these having a different length. The capacitors 11 , 11.2 hang towards a top 22nd of the container 20th to the floor 21 down, taking the sensor ladder 12th of the first capacitor 11 longer than that of the second capacitor 11 are, so that there is a difference in length L. results. Both capacitors 11 , 11.2 are each with a measuring circuit 18th , 18.2 the evaluation unit 19th connected.

On the floor 21 has liquid F. accumulated. The liquid F. can from the evaluation unit 19th by means of the measuring circuit 18th and the first capacitor 11 be registered as the capacitor 11 partially within the liquid F. is located. As soon as the liquid also the second capacitor 11 can be achieved by means of the known difference in length L. an automatic calibration on the part of the evaluation unit 19th for the quantitative determination of the liquid F. respectively.

6th shows a schematic view of an embodiment of a motor vehicle according to the invention 30th with a container according to the invention 20th , here as the battery housing of a traction battery of the motor vehicle 30th is trained.

List of reference symbols

10

Sensor system

11

capacitor

12th

elongated sensor conductor

13th

airspace

14th

elongated conductor

15th

electrical insulator

16

Sealing element

17th

web

18th

Measuring circuit

19th

Evaluation unit

20th

container

21st

ground

22nd

Top

30th

Motor vehicle

F.

liquid

L.

Length difference

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 68921346 T2 [0002]
• DE 19841717 A1 [0003]
• DE 3873968 T2 [0004]

Claims (10)

Sensor system (10) for the quantitative measurement of a liquid (F) with: (a) a capacitor (11) with at least two elongated sensor conductors (12) electrically insulated from one another, each of the at least two elongated sensor conductors (12) having an elongated current conductor (14) and an electrical insulator (15) arranged around a circumference of the elongated current conductor (14), (b) a measuring circuit (18) which is connected to the capacitor (11) for measuring the conduction capacitance of the capacitor (11), and ( c) an evaluation unit (19) which is connected to the measuring circuit (18) for evaluating measurement results of the measurement of the measuring circuit (18), characterized in that (d) the elongated current conductors (14) are designed as wires and the at least two elongated sensor conductors (12) are twisted with one another, so that an air space (13) is formed in each case between the electrical insulators (15) of the at least two elongated sensor conductors (12) , or (e) the elongated current conductors (14) are designed as flat conductors or round conductors and the at least two elongated sensor conductors (12) are connected to one another by at least one web (14) at a distance transverse to the longitudinal extension of the elongated sensor conductors (12), so that in the distance between the electrical insulators (15) of the at least two elongated sensor conductors (12) at least one air space (13) is formed. Sensor system (10) Claim 1 , characterized in that the measuring circuit (18) is designed as an astable trigger circuit. Sensor system (10) Claim 1 or 2 , characterized in that one of the at least two elongated current conductors (14) is connected to a ground. Sensor system (10) according to one of the preceding claims, characterized in that at least one elongated heating current conductor is arranged on the at least two elongated sensor conductors (12). Container (20), in particular of a motor vehicle (30), with a sensor system (10) according to one of the preceding claims. Container (20) after Claim 5 , characterized in that the container (20) is a battery housing. Container (20) after Claim 5 or 6th , characterized in that the at least two elongated sensor conductors (12) are arranged in the form of a loop on a base (21) of the container (20). Container (20) according to one of the Claims 5 to 7th , characterized in that end sections of the at least two elongated sensor conductors (12) extend from a bottom (21) of the container (20) in the direction of a height of the container (20) and longitudinal ends of the end sections of the at least two elongated sensor conductors (12) are non-electrical are isolated. Container (20) according to one of the Claims 5 to 8th , characterized in that two capacitors (11) are connected to at least one measuring circuit (18), the two capacitors (11) with elongated sensor conductors (12) of different lengths within the container (20) from an upper side (22) of the container (20) extend in the direction of the bottom (21) of the container (20) and are spaced from the bottom (20), and that the evaluation unit (19) for automatic calibration of a quantitative level detection by means of the resulting difference in length (L) between the elongated sensor conductors (12) of one of the two capacitors (11) and the elongated sensor conductors (12) of the other of the two capacitors (11) is formed. Motor vehicle (30) with a container (20) according to one of the Claims 5 to 9 .

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