Method for determining an aggregate state of aqueous operating liquid in an operating liquid container for a motor vehicle, and operating liquid container for carrying out the method

Patent metadata

Field	Value
Publication number	US-11774386-B2
Application number	US-201816958569-A
Country	US
Kind code	B2
Filing date	Dec 13, 2018
Priority date	Dec 28, 2017
Publication date	Oct 3, 2023
Grant date	Oct 3, 2023

Abstract

A method for determining an aggregate state of an operating liquid in an operating liquid container for a motor vehicle, which operating liquid container has at least one capacitor fastened to a container wall of the operating liquid container and has a first electrode and a second electrode opposite said first electrode. A first method determines the aggregate state of the operating liquid by means of a frequency-dependent phase profile of the impedance of the at least one capacitor. Another method determines the aggregate state of the operating liquid by means of a frequency-dependent capacitance profile of the at least one capacitor. Further, an operating liquid container is designed for carrying out the methods.

First claim

The invention claimed is:

1. A method for determining an aggregate state of an aqueous operating liquid in an operating liquid container for a motor vehicle, wherein the operating liquid container has at least one capacitor which is fastened to a container wall of the operating liquid container and has a first electrode and a second electrode opposite said first electrode, the method comprising:
applying at least a first alternating voltage to the capacitor, wherein a first frequency of the first alternating voltage corresponds to a lower frequency limit (fmin);
determining and storing a first impedance of the capacitor for the first frequency;
determining a first phase angle (φ 1 ) from the first impedance;
determining that the operating liquid located in the operating liquid container is in a solid aggregate state when the first phase angle (φ 1 ) is greater than a first critical angle (δ 1 );
applying a second alternating voltage to the capacitor, wherein a second frequency of the second alternating voltage corresponds to an upper frequency limit (fmax);
determining and storing a second impedance of the capacitor for the second frequency;
determining a second phase angle (φ 2 ) from the second impedance; and
determining that the operating liquid located in the operating liquid container is partially in a solid and partially in a liquid aggregate state when the first phase angle (φ 1 ) is smaller than the first critical angle (δ 1 ) and a difference between the second phase angle (φ 2 ) and the first phase angle (φ 1 ) is greater than a second critical angle (δ 2 ).

2. The method according to claim 1 , further comprising:
determining that the operating liquid located in the operating liquid container is in a liquid aggregate state when the first phase angle (φ 1 ) is smaller than the first critical angle (δ 1 ) and a difference between the second phase angle (φ 2 ) and the first phase angle (φ 1 ) is smaller than the second critical angle (δ 2 ).

3. The method according to claim 2 , further comprising:
determining a first capacitance (C 1 ) of the capacitor from the first impedance;
determining a second capacitance (C 2 ) of the capacitor from the second impedance;
determining a relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ); and
determining that the operating liquid located in the operating liquid container is in a solid aggregate state when the relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ) is greater than a first capacitance deviation (ΔC 1 ).

4. The method according to claim 3 , further comprising:
determining that the operating liquid located in the operating liquid container is partially in a solid and partially in a liquid aggregate state when the relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ) is smaller than the first capacitance deviation (ΔC 1 ) and greater than a second capacitance deviation (ΔC 2 ).

5. The method according to claim 4 , further comprising:
determining that the operating liquid located in the operating liquid container is in a liquid aggregate state when the relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ) is smaller than a second capacitance deviation (ΔC 2 ).

6. A method for determining an aggregate state of an aqueous operating liquid in an operating liquid container for a motor vehicle, wherein the operating liquid container has at least one capacitor which is fastened to a container wall of the operating liquid container and has a first electrode and a second electrode opposite said first electrode, the method comprising:
applying at least two different alternating voltages to the capacitor, wherein a first frequency of a first alternating voltage corresponds to a lower frequency limit (fmin) and a second frequency of a second alternating voltage corresponds to an upper frequency limit (fmax);
determining and storing a first capacitance (C 1 ) of the capacitor for the first frequency and a second capacitance (C 2 ) of the capacitor for the second frequency;
determining a relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ); and
determining that the operating liquid located in the operating liquid container is in a solid aggregate state when the relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ) is greater than a first capacitance deviation (ΔC 1 ).

7. The method according to claim 6 , further comprising:
determining that the operating liquid located in the operating liquid container is partially in a solid and partially in a liquid aggregate state when the relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ) is smaller than the first capacitance deviation (ΔC 1 ) and greater than a second capacitance deviation (ΔC 2 ).

8. The method according to claim 7 , further comprising:
determining that the operating liquid located in the operating liquid container is in a liquid aggregate state when the relative deviation of the second capacitance (C 2 ) from the first capacitance (C 1 ) is smaller than a second capacitance deviation (ΔC 2 ).

9. An operating liquid container comprising:
an interior delimited by a ceiling wall, a bottom wall, and a sidewall which connects the bottom wall to the ceiling wall;
at least one capacitor fastened to a container wall, the at least one capacitor including a first electrode and a second electrode;
an electronic evaluator which is electrically connected to the first electrode and to the second electrode,
wherein the evaluator is configured to perform a method comprising:
applying at least a first alternating voltage to the capacitor, wherein a first frequency of the first alternating voltage corresponds to a lower frequency limit (fmin);
determining and storing a first impedance of the capacitor for the first frequency;
determining a first phase angle (φ 1 ) from the first impedance;
determining that the operating liquid located in the operating liquid container is in a solid aggregate state when the first phase angle (φ 1 ) is greater than a first critical angle (δ 1 );

applying a second alternating voltage to the capacitor, wherein a second frequency of the second alternating voltage corresponds to an upper frequency limit (fmax);
determining and storing a second impedance of the capacitor for the second frequency;
determining a second phase angle (φ 2 ) from the second impedance; and
determining that the operating liquid located in the operating liquid container is partially in a solid and partially in a liquid aggregate state when the first phase angle (φ 1 ) is smaller than the first critical angle (δ 1 ) and a difference between the second phase angle (φ 2 ) and the first phase angle (φ 1 ) is greater than a second critical angle (δ 2 ).

10. The operating liquid container according to claim 9 , wherein the capacitor is embedded in the container wall.

11. The operating liquid container according to claim 10 , wherein:
the bottom wall has an elevation extending into the interior of the operating liquid container; and
the first electrode and the second electrode of the capacitor are embedded in the elevation.

12. The operating liquid container according to claim 11 , wherein:
the container wall comprises an outer layer, an inner layer facing the interior of the operating liquid container, and a bonding layer arranged in between; and
the first electrode and the second electrode of the at least one capacitor are arranged between the outer layer and the bonding layer.

13. The operating liquid c

Assignees

• Kautex Textron Gmbh & Co Kg

Inventors

• Krieger Karl-Ludwig
• Happel Jakob
• Wolf Hartmut

Classifications

• G01N27/026 Primary

  Dielectric impedance spectroscopy (electrochemical impedance spectroscopy for measuring corrosion G01N17/02) · CPC title

• G01N27/228

  Circuits therefor (measuring capacitance per se G01R27/26) · CPC title

• G01N27/22

  by investigating capacitance · CPC title