SYSTEM FOR MEASURING A FILLING LEVEL

Abstract

A system for measuring a filling level in a container for liquids that can be installed in a vehicle, which comprises a sound conductor, a vibration sensor for measuring a natural frequency of the sound conductor, a sound transmitter, in particular an ultrasound transmitter, for subjecting the sound conductor to sound, a sound receiver for receiving sound from the sound conductor, and an evaluation unit, which has a data connection to the sound transmitter and the sound receiver, wherein the evaluation unit is configured to determine a distance between the sound transmitter and a boundary surface of the liquid, and to evaluate the distance with regard to a filling level of the container, and to evaluate the natural frequency of the sound conductor with regard to a density of the liquid.

Claims

1. A system for measuring a fillinging level in a container for liquids that is to be installed in a vehicle, comprising a sound conductor, a vibration sensor for measuring a natural frequency of the sound conductor, a sound transmitter, comprising an ultrasound transmitter for subjecting the sound conductor to sound, a sound receiver for receiving sound from the sound conductor, and an evaluation unit, which has a data connection to the sound transmitter, the vibration sensor, and the sound receiver, wherein the evaluation unit is configured to determine a distance between the sound transmitter and a boundary surface of the liquid, and to evaluate the distance with regard to a filling level of the container, and to evaluate the natural frequency of the sound conductor with respect to a density of the liquid.

2. The system for measuring a filling level according to claim 1, wherein the evaluation unit is configured to detect a runtime between when the sound conductor is subjected to the sound, and the reception of the sound from the sound conductor, and to evaluate the runtime with respect to the filling level of the container.

3. The system for measuring a filling level according to claim 1, wherein the sound conductor, the sound transmitter and the sound receiver can be placed in the container such that the sound is reflected on a boundary surface of the liquid to the sound receiver.

4. The system for measuring a filling level according to claim 1, wherein the sound transmitter is configured to subject the sound conductor to sounds of various frequencies, and the evaluation unit is configured to detect a change in the natural frequency of the sound conductor.

5. The system for measuring a filling level according to claim 1, wherein the evaluation unit is configured to evaluate the natural frequency, in particular the change in the natural frequency, with regard to a quality of a boundary surface of the liquid.

6. The system for measuring a filling level according to claim 1, wherein the sound conductor is in the form of a hollow conductor and/or is made from a solid material.

7. The system for measuring a filling level according to claim 6, wherein the sound conductor is in the form of a hose and/or a tube, and can be placed in a container such that the sound conductor is in contact with the liquid inside and/or outside the sound conductor, when the container is fillinged with the liquid.

8. The system for measuring a filling level according to claim 1, wherein the sound conductor contains metal and/or a crystalline substance.

9. The system for measuring a filling level according to claim 1, wherein the sound transmitter is configured to subject the sound conductor to compression waves, and/or torsion waves, and/or surface waves.

10. The system for measuring a filling level according to claim 1, wherein the system for measuring a filling level contains numerous sound conductors, sound transmitters and sound receivers, in particular three sound conductors, sound transmitters, and sound receivers in each case, which are configured to measure a filling level of a container at numerous, in particular three, measuring points.

11. The system for measuring a filling level according to claim 1, wherein the sound conductor has at least one branching.

12. The system for measuring a filling level according to claim 1, wherein the sound conductor is curved.

13. The system for measuring a filling level according to claim 1, which has an attachment means for attaching the sound conductor to a container at least one attachment point, wherein the attachment point is configured in particular with regard to a coupling of interference waves outside the sound conductor, and/or with regard to a decoupling of the sound to which the sound conductor is subjected.

14. The system for measuring a filling level according to claim 1, wherein the sound conductor has at least one longitudinal reference marker, which has an effect on the natural frequency of the sound conductor, wherein the longitudinal reference marker is formed in particular as a change in the cross section of the sound conductor, specifically as a tapering and/or widening of the sound conductor.

15. The system for measuring a filling level according to claim 1, wherein the sound conductor has a means for manipulating a sound coupling between the sound conductor and the liquid, wherein the means results in an enlargement of the surface of the sound conductor, and is formed in particular as ribs, fins, holes, and/or a surface wrinkling.

16. A container with the system for measuring a filling level according to claim 1, which is designed in particular as the oil tank for a vehicle.

17. A method for measuring a filling level of a liquid in a container that comprises the following steps: generating of a sound signal by a sound transmitter and subjecting a sound conductor to the sound signal; receiving the sound signal by a sound receiver, which is transported from the sound conductor to the sound receiver; determining a distance between the sound transmitter and a boundary surface of the liquid on the basis of the generated sound signal and the receive sound signal; evaluating the distance with regard to the filling level of the container by the evaluation unit; determining a natural frequency of the sound conductor with a vibration sensor; evaluating the natural frequency with regard to a density of the liquid by the evaluation unit.

Description

CONTENTS OF THE DRAWINGS

[0059] The present invention shall be explained in greater detail below based on the exemplary embodiments shown in the schematic figures, Therein:

[0060] FIG. 1 shows a schematic diagram of an embodiment of the invention;

[0061] FIG. 2 shows a schematic pulse diagram for an embodiment of the invention;

[0062] FIG. 3 shows a schematic diagram of an embodiment of the invention;

[0063] FIG. 4 shows a schematic pulse diagram for an embodiment of the invention;

[0064] FIGS. 5A, B each show a schematic diagram of an embodiment of the invention;

[0065] FIGS. 6A, B each show a schematic diagram of an embodiment of the invention;

[0066] FIG. 7 shows a schematic diagram of an embodiment of the invention;

[0067] FIGS. 8A-D each show a schematic diagram of an embodiment of the invention;

[0068] FIG. 9 shows a schematic diagram of an embodiment of the invention;

[0069] FIG. 10 shows a schematic diagram of an embodiment of the invention;

[0070] FIG. 11 shows a schematic diagram of an embodiment of the invention;

[0071] FIG. 12 shows a schematic block diagram of an embodiment of the invention;

[0072] The various drawings are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and are used in conjunction with the description to explain principles and concepts of the invention, Other embodiments and many of the specified advantages can be derived in reference to the drawings. The elements of the drawings are not necessarily drawn to scale.

[0073] Identical elements, features and components having the same functions and acting in the same manner are provided with the same reference symbols, as long as not otherwise stated.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0074] The functioning of the system 10 for measuring a filling level based on runtime measurements shall be described in reference to the drawings. It is understood that the alternatives, spectroscopy and interferometry, are the same as runtime measurement, as explained above.

[0075] The embodiments in the drawings each have a sound transmitter/receiver, thus a device that both transmits and receives sound.

[0076] It should be understood that a sound transmitter can also be separate from a sound receiver.

[0077] FIG. 1 shows a schematic diagram of a system 10 for measuring a filling level, the sound receiver 14 and vibration sensor 16 of which are placed in a liquid 18 in a container. The system 10 for measuring a filling level comprises a sound conductor 12, a vibration sensor 16 and an evaluation unit 17. A foam 22 is formed on the boundary surface of the liquid 18. The filling level of the liquid 18 is indicated by 11 in FIG. 1. The overall height of the container 50, or the overall length of the sound conductor 12 is indicated by 12 in FIG. 1.

[0078] It is illustrated in FIG. 1 that sound from the sound transmitter/receiver 14 is coupled into the sound conductor 12, and the sound is partially reflected at the boundary surface of the liquid 18, and partially conducted through the sound conductor 12. The sound that is not reflected at the boundary surface of the liquid 18 is reflected back to the sound transmitter/receiver 14 at the end of the sound conductor 12.

[0079] FIG. 2 shows a pulse diagram relating to FIG. 1. The amplitude A is plotted in the pulse diagram on the y-axis over time t on the x-axis. The pulse 101 is the transmission pulse, as it is emitted by the sound transmitter/receiver 14. The pulse 105 is the pulse as it is reflected at the boundary surface of the liquid 18, at the filling level 11. The pulse 103 is the pulse as it is reflected at the end of the sound conductor 12.

[0080] The system 10 for measuring a filling level according to FIG. 3 differs from the system 10 for measuring a filling level according to FIG. 1 in that the sound transmitter/receiver 14 and the vibration sensor 16 are not located in the liquid 18, but instead in the gas 20. The sound conductor 12 according to FIG. 3 is also S-shaped, while the sound conductor 12 according to FIG. 1 is straight. Accordingly, the sound conductor 12 according to FIG. 3 penetrates the liquid three times. The distance between the sound transmitter/receiver 14 and the first time it penetrates the liquid is indicated with 11. The distance between the sound receiver/transmitter 14 and the second time it penetrates the liquid is indicated with 12 in FIG. 3. The distance between the sound transmitter/receiver 14 and the third time it penetrates the liquid is indicated with 13 in FIG. 3. The distance between the sound transmitter/receiver 14 and the end of the sound conductor 12 is indicated with 14 in FIG. 3.

[0081] The pulse diagram according to FIG. 4 relating to FIG. 3 corresponds to the pulse diagram in FIG. 2. Accordingly, five pulses can be seen in the pulse diagram according to FIG. 4 for FIG. 3. Pulse 101 is the transmission pulse, as it is emitted from the sound transmitter. Pulse 105 is the pulse as it is reflected at the first time it penetrates the liquid. Pulse 107 is the pulse as it is reflected at the second time it penetrates the liquid. Pulse 109 is the pulse as it is reflected at the third time in penetrates the liquid. The pulse 103 is the pulse as it is reflected at the end of the sound conductor 12.

[0082] Figures SA, B each show attachment possibilities for a sound conductor 12 in a container 50. The attachment means according to FIGS. 5A and 5B each have an attachment means 24 that prevents leakage of the measurement sound field. It is possible to take into account the relationship between the sound impedance of the materials with different sound speeds c, thus the density and compressibility. If the sound conductor is hard and heavy, for example, the coupling element should be significantly lighter and softer, and vice versa. For a sound conductor made of metal, attachment means made of plastic or rubber are ideal. For a sound conductor filled with air, heavy metals are more appropriate for the attachment means. If the operating frequency remains constant, interference effects that have different sound speeds or different sound impedances can also be exploited by means of sound conductors with coated materials. 1 is also possible to make use of damping effects (e.g., via internal friction or scattering), in order to reduce the acoustic coupling in a targeted manner. An attachment means also serves as a mechanical attachment, in particular when subjected to sloshing oil, currents or vibrations.

[0083] The attachment means 26 ensures that the sound conductor is sufficiently supported on the container 50.

[0084] FIGS. 6A, 6B each show differently shaped sound conductors 12 in a container 50 filled with liquid 18 and gas 20.

[0085] The sound conductor is basically U-shaped in FIG. 6A, wherein the sound transmitter/receiver 14 is formed in the middle of the sound conductor, between two vibration sensors 16. Accordingly, sound from the sound transmitter/receiver 14 is coupled into both arms 115, 117 of the sound conductor 12. Accordingly, it is possible to determine which arm of the sound conductor 12 reflects a pulse.

[0086] The sound conductor 12 is annular in FIG. 6B, wherein the sound transmitter/receiver is formed between two vibration sensors 16.

[0087] FIG. 7 shows another embodiment of a sound conductor 12, which is curved. The sound conductor 12 is placed in a particularly space-saving manner between two drives 111 and 113 due to its curvature.

[0088] FIGS. 8A-D each show different means 28 used to manipulate the sound coupling. In FIG. 8A, these means 28 for manipulating the sound coupling are in the form of fins. In FIG. 8B, the means 28 for manipulating the sound coupling are in the form of ribs. In FIG. 8C, the means 28 for manipulating the sound coupling are in the form of spokes. In FIG. 8D, the means for manipulating the sound coupling are in the form of holes.

[0089] FIG. 9 shows another embodiment of a system 10 for measuring a filling level. The sound conductor 12 according to FIG. 9 is basically in the shape of a W and is connected at both ends to a vibration sensor 16 and a sound transmitter/receiver 14. In FIG. 9, the sound conductor 12 penetrates the liquid 18 in the container 50 four times.

[0090] FIG. 10 shows another embodiment of a system 10 for measuring a filling level. The sound conductor 12 according to FIG. 10 has two branches 32.

[0091] FIG. 11 shows a system 10 for measuring a filling level that is similar to that in FIG. 3, wherein the system 10 according to FIG. 11 has a first sound transmitter/receiver 14 and a first vibration sensor 16, which are located in the liquid 18. In the further course of the sound conductor 12, it has another sound transmitter/receiver 14, which is located between two vibration sensors 16 in the liquid 18. The sound conductor 12 according to FIG. 11 also has a longitudinal reference marker 30 in the form of a tapering.

[0092] FIG. 12 shows a schematic block diagram of a method for determining a filling level, comprising the steps S1 to S6. In step S1, a sound signal is generated by a sound transmitter, and a sound conductor is subjected to the sound signal. In step S2, the sound signal is received by a sound receiver, which is transported from the sound conductor to the sound receiver. In step S3, a distance between the sound transmitter and a boundary surface of the liquid is determined on the basis of the generated sound signal and the received sound signal. In step S4, the distance is evaluated with respect to the filling level of the container by an evaluation unit. In step S5, a natural frequency of the sound conductor is determined by a vibration sensor. In step S6, the natural frequency is evaluated with respect to a density of the liquid by the evaluation unit.

REFERENCE SYMBOLS

[0093] 10 system for measuring a filling level [0094] 12 sound conductor [0095] 14 sound transmitter/receiver [0096] 16 vibration sensor [0097] 17 evaluation unit [0098] 18 liquid [0099] 20 gas [0100] 22 foam [0101] 24 attachment means [0102] 26 attachment means [0103] 28 means for manipulating the sound coupling [0104] 30 longitudinal reference marker [0105] 32 branching [0106] 50 container [0107] 101 transmitted pulse [0108] 103 reflected pulse [0109] 105 reflected pulse [0110] 107 reflected pulse [0111] 109 reflected pulse [0112] 111 gearing [0113] 113 gearing [0114] 115 arm [0115] 117 arm [0116] 11 distance [0117] 12 distance [0118] 13 distance [0119] 14 distance