FILLING LEVEL SENSOR AND ASSOCIATED OPERATING METHOD AND MANUFACTURING PROCESS AND CORRESPONDING USAGE

Abstract

The invention relates to a filling level sensor with several thermoelements for measuring a level of a liquid, especially for detecting the level of a fuel in a fuel tank of a motor vehicle, wherein a separate heating device for heating the thermoelements can be eliminated. Furthermore, the invention also relates to an associated operating method and manufacturing process.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

Other advantageous further developments of the invention are characterized in the dependent claims or are explained in detail in the following together with a description of the preferred exemplary embodiments of the invention with reference made to the figures.

FIG. 1 shows a schematic view of a filling level sensor in accordance with the invention with a single thermal column,

FIG. 2 shows an alternative exemplary embodiment of a filling level sensor in accordance with the invention with two thermal columns,

FIG. 3 shows a schematic view of a fuel tank of a motor vehicle with a filling level sensor in accordance with FIG. 1 arranged in it,

FIG. 4 shows a schematic view of a single thermoelement of the filling level sensor in accordance with the invention according to FIGS. 1 to 3,

FIG. 5 shows a schematic cross-sectional view of a filling level sensor in accordance with the invention in which the different conductor materials of the thermoelement are arranged on the same side of a carrier material,

FIG. 6 shows a simplified cross-sectional view of an alternative exemplary embodiment of a filling level sensor in accordance with the invention in which the different conductor materials of the thermoelements are arranged on opposite sides of the carrier material,

FIG. 7 shows a schematic view of a section of a thermocolumn with conductor materials applied on it successively in time,

FIG. 8 shows a section of an alternative exemplary embodiment of a thermocolumn consisting of uniform base material with a second, low-ohmic, thermoelectrically different layer,

FIG. 9 shows a schematic view of a section of a thermocolumn in which the different conductor materials of the thermoelements are applied on opposite sides of a carrier layer,

FIG. 10 shows a cross-sectional view through the thermocolumn of FIG. 9 along sectional line A-A,

FIG. 11 shows a simplified block diagram of a level measuring apparatus in accordance with the invention,

FIG. 12 shows an extremely simplified block diagram of a level measuring apparatus in accordance with the invention with a microcontroller for controlling and evaluating the filling level sensor, and

FIGS. 13A-D show different courses of current and voltage on the filling level sensor in accordance with the invention.

Claims

1. A filling level sensor for measuring a filling level of a fluid, comprising a plurality of thermoelements, wherein no separate heating is provided for heating the thermoelements.

2. The filling level sensor according to claim 1, wherein the thermoelements are connected in series behind each other.

3. The filling level sensor according to claim 1, wherein the thermoelements form an elongated thermocolumn.

4. The filling level sensor according to claim 3, wherein the individual thermoelements are aligned substantially at a right angle to a longitudinal axis of the thermocolumn.

5. The filling level sensor according to claim 1, wherein the thermoelements form several elongated thermocolumns that are connected in series behind each other and are arranged substantially in parallel and adjacent to each other.

6. The filling level sensor according to claim 4, wherein the thermoelements have hot contact points and cold contact points, the hot contact points are arranged in a first line, the cold contact points are arranged in a second line, and the first line and the second line are on opposite sides of the thermocolumn.

7. The filling level sensor according to claim 6, wherein in the adjacent thermocolumns the hot contact points face each other.

8. The filling level sensor according to claim 6, wherein in the adjacent thermocolumns the cold contact points face each other.

9. The filling level sensor according to claim 1, wherein each of the thermoelements comprises a first conductor material and a second conductor material that are connected to each other at a contact point.

10. The filling level sensor according to claim 9, wherein the first and second conductor materials are arranged on a same side of a carrier material.

11. The filling level sensor according to claim 9, wherein the first and second conductor materials are arranged on opposite sides of a carrier material and are connected to one another at the contact point by a plated-through hole.

12. The filling level sensor according to claim 9, wherein the first conductor material is a copper-nickel alloy.

13. The filling level sensor according to claim 9, wherein the second conductor material is selected from the group consisting of copper, a copper-manganese-nickel alloy and a nickel-chromium alloy.

14. The filling level sensor according to claim 6, wherein the thermoelements are adapted to heat the hot contact points and cool the cold contact points as a function of an applied electrical current, and the thermoelements are adapted to produce a thermovoltage between the hot contact points and the cold contact points in a currentless state as a function of a temperature difference between the hot contact points and the cold contact points.

15. The filling level sensor according to claim 1, wherein the thermoelements are arranged on a foil as a carrier material.

16. The filling level sensor according to claim 1, wherein the thermoelements are arranged on a thin-walled tube as a carrier material.

17. A filling level measuring apparatus comprising a filling level sensor according to claim 1.

18. The filling level measuring apparatus according to claim 17, comprising: (a) a current source connected to the filling level sensor and adapted to supply a current to the filling level sensor; and(b) a voltage measuring apparatus connected to the filling level sensor and adapted to measure an electrical voltage produced by the filling level sensor in a currentless state.

19. The filling level measuring apparatus according to claim 18, wherein the current source comprises an impulse generator and is adapted to control the filling level sensor with current impulses.

20. The filling level measuring apparatus according to claim 18, comprising an integrator connected to the voltage measuring apparatus and adapted to perform a simple integration of the measured voltage.

21. The filling level measuring apparatus according to claim 18, comprising an integrator connected to the voltage measuring apparatus and adapted to perform a double integration of the measured voltage.

22. The filling level measuring apparatus according to claim 18, comprising a microcontroller connected to the filling level sensor and adapted for electrical controlling of the filling level sensor and for measuring the electrical voltage produced by the filling level sensor.

23. The filling level measuring apparatus according to claim 18, wherein the filling level sensor is arranged in a fuel tank of a motor vehicle and measures the filling level of a fuel in the fuel tank.

24. The filling level measuring apparatus according to claim 18, wherein the thermoelements form an elongated thermocolumn aligned at substantially a right angle to a fluid level to be measured.

25. The filling level measuring apparatus according to claim 18, wherein each thermoelement is aligned substantially parallel to a fluid level to be measured.

26. An operating process for a filling level sensor with several thermoelements, wherein the thermoelements are not heated by a separate heating.

27. The operating process according to claim 26, comprising the following steps: (a) supplying the thermoelements with a current for producing a temperature difference over the individual thermoelements,(b) measuring an electrical voltage produced by the filling level sensor, and(c) determining a filling level from the measured voltage.

28. The operating process according to claim 26, wherein the filling level sensor is supplied with current impulses.

29. The operating process according to claim 27, wherein the measuring of the voltage takes place in a currentless state after the filling level sensor has been supplied with current.

30. The operating process according to claim 27, comprising a simple integration of the measured voltage.

31. The operating process according to claim 27, comprising a double integration of the measured voltage.

32. The operating process according to claim 26, wherein the filling level sensor is controlled and measured by a microcontroller.

33. A manufacturing process for a filling level sensor comprising the following steps: (a) application of a plurality of thermoelements on a carrier material,(b) electrical connection of the thermoelements to a series connection of each of the thermoelements,wherein no separate heating device is applied on the carrier material.

34. The manufacturing process according to claim 33, wherein each thermoelement comprises a first conductor material and a second conductor material that are connected to one another at a contact point.

35. The manufacturing process according to claim 34, wherein the first and second conductor materials are applied on a same side of the carrier material.

36. The manufacturing process according to claim 34, wherein the first and second conductor materials are applied on opposite sides of the carrier material and a plated-through hole is produced in the carrier material at the contact point and extends through the carrier material.

37. The manufacturing process according to claim 34, wherein the first and second conductor materials are applied onto the carrier material by a method selected from the group consisting of sputtering, printing, a galvanic method and an etching method.

38. A method of measuring a filling level of a fluid, said method comprising: providing a plurality of thermoelements connected in series behind each other; andmeasuring the filling level of the fluid without a separate heating step.

39. The method according to claim 38, wherein the fluid is a fuel in a fuel tank of a motor vehicle.