阅读说明：本技术 测定汽车用工作液容器中的水性工作液的聚集态的方法以及用于实施该方法的工作液容器 (Method for determining the state of aggregation of an aqueous working fluid in a working fluid container for a motor vehicle and working fluid container for carrying out the method ) 是由 卡尔·路德维希·克里格 雅各布·哈珀尔 哈特穆特·沃夫 于 2018-12-13 设计创作，主要内容包括：本发明公开一种测定汽车用工作液容器(1)中的工作液的聚集态的方法,其中所述工作液容器(1)具有至少一个固定在所述工作液容器(1)的容器壁(10、20、30)上的电容器(60、70),所述电容器具有第一电极(61、71)和与所述第一电极相对设置的第二电极(62、72)。本发明的第一种方法是借助所述至少一个电容器(60、70)的阻抗的与频率相关的相位特性曲线来测定所述工作液的聚集态。本发明的另一种方法是借助所述至少一个电容器(60、70)的与频率相关的电容特性曲线来测定所述工作液的聚集态。此外,本发明还公开一种被构建为用于实施本发明方法的工作液容器(1)。(The invention relates to a method for determining the aggregation state of a working fluid in a working fluid container (1) for a motor vehicle, wherein the working fluid container (1) has at least one capacitor (60, 70) which is fastened to a container wall (10, 20, 30) of the working fluid container (1) and which has a first electrode (61, 71) and a second electrode (62, 72) which is arranged opposite the first electrode. The first method of the invention is to determine the state of aggregation of the operating fluid by means of a frequency-dependent phase characteristic of the impedance of the at least one capacitor (60, 70). Another method according to the invention is to determine the state of aggregation of the working fluid by means of a frequency-dependent capacitance characteristic of the at least one capacitor (60, 70). Furthermore, the invention also discloses a working fluid container (1) which is designed to carry out the method according to the invention.)

1. A method for determining the aggregation state of an aqueous working fluid in a working fluid container (1) for a motor vehicle, wherein the working fluid container (1) has at least one capacitor (60, 70) which is fastened to a container wall (10, 20, 30) of the working fluid container (1) and which has a first electrode (61, 71) and a second electrode (62, 72) arranged opposite the first electrode, wherein the method is characterized by the following method steps:

-applying (a) at least one first alternating voltage to the capacitor (60, 70), wherein a first frequency of the first alternating voltage corresponds to a lower limit frequency (fmin);

-determining and storing (B) a first impedance of the capacitor (60, 70) for the first frequency;

-determining (C) a first phase angle from said first impedance

-when the first phase angleIf the difference is greater than the first limiting angle (1), it is determined (D) that the operating fluid (50) located in the operating fluid container (1) has a solid state of aggregation.

2. The method according to claim 1, characterized by the following features:

-applying (E) a second alternating voltage to the capacitor (60, 70), wherein a second frequency of the second alternating voltage corresponds to an upper limit frequency (fmax);

-determining and storing (F) a second impedance of the capacitor (60, 70) for the second frequency;

-determining (G) a second phase angle from the second impedanceAnd is

-when the first phase angle

3. Method according to claim 2, characterized by the following method steps:

-when the first phase angleLess than the first limit angle (1) and the second phase angleTo the first phase angleWhen the difference is smaller than the second limit angle (2), it is determined (I) that the working fluid (50) in the working fluid container (1) has a liquid state of aggregation.

4. Method according to any of claims 2 or 3, characterized by the following method steps:

-determining (C') a first capacitance (C1) of the capacitor (60, 70) from the first impedance;

-determining (G') a second capacitance (C2) of the capacitor (60, 70) from the second impedance

-determining (L) a relative deviation of the second capacitance (C2) from the first capacitance (C1); and is

-determining (D) that the operating fluid (50) located in the operating fluid container (1) has a solid state of aggregation when the relative deviation of the second capacitance (C2) from the first capacitance (C1) is larger than a first capacitance deviation (ac 1).

5. Method according to claim 4, characterized by the following method steps:

determining (H) that the operating fluid (50) located in the operating fluid container (1) has partly a solid state of aggregation and partly a liquid state of aggregation when the relative deviation of the second capacitance (C2) from the first capacitance (C1) is smaller than the first capacitance deviation (Δ C1) and larger than a second capacitance deviation (Δ C2).

6. Method according to any of claims 4 to 5, characterized by the following method steps:

-determining (I) that the operating fluid (50) located in the operating fluid container (1) has an aggregate state in the liquid state when the relative deviation of the second capacitance (C2) from the first capacitance (C1) is smaller than a second capacitance deviation (ac 2).

7. A method for determining the aggregation state of an aqueous working fluid in a working fluid container (1) for a motor vehicle, wherein the working fluid container (1) has at least one capacitor (60, 70) which is fastened to a container wall (10, 20, 30) of the working fluid container (1) and which has a first electrode (61, 71) and a second electrode (62, 72) arranged opposite the first electrode, wherein the method is characterized by the following method steps:

-applying (J) at least two different alternating voltages to said capacitor (60, 70), wherein a first frequency of a first alternating voltage corresponds to a lower limit frequency (fmin) and a second frequency of a second alternating voltage corresponds to an upper limit frequency (fmax);

-determining and storing (K) a first capacitance (C1) of the capacitor (60, 70) for the first frequency and a second capacitance (C2) of the capacitor (60, 70) for the second frequency;

-determining (L) a relative deviation of the second capacitance (C2) from the first capacitance (C1); and is

-determining (M) that the operating fluid (50) located in the operating fluid container (1) has a solid state of aggregation when the relative deviation of the second capacitance (C2) from the first capacitance (C1) is larger than a first capacitance deviation (ac 1).

8. Method according to claim 7, characterized by the following method steps:

-determining (N) that the operating fluid (50) located in the operating fluid container (1) has partly a solid state of aggregation and partly a liquid state of aggregation when the relative deviation of the second capacitance (C2) from the first capacitance (C1) is smaller than the first capacitance deviation (ac 1) and larger than a second capacitance deviation (ac 2).

9. Method according to any of claims 7 to 8, characterized by the following method steps:

-determining (O) that the operating fluid (50) located in the operating fluid container (1) has an aggregate state in the liquid state when the relative deviation of the second capacitance (C2) from the first capacitance (C1) is smaller than a second capacitance deviation (ac 2).

10. A working fluid container (1) having the following features:

-the working fluid container inner chamber (2) is delimited by a top wall (30), a bottom wall (10) and a side wall (20) connecting said bottom wall (10) with said top wall (30);

-the operating fluid container (1) has at least one capacitor (60, 70) which is fastened to a container wall (10, 20, 30) of the operating fluid container (1) and which has a first electrode (61, 71) and a second electrode (62, 72);

-the working fluid container (1) has an electronic analysis device (80) electrically connecting the first electrode (61, 71) and the second electrode (62, 72),

-wherein the working fluid container (1) is characterized in that: the analysis device (80) is designed to carry out a method according to at least one of claims 1 to 9.

11. Operating fluid container (1) according to claim 10, characterized in that the capacitor (60, 70) is embedded in the container wall (10, 20, 30).

12. Operating fluid container (1) according to any one of claims 10 to 11, characterized by the following features:

-said bottom wall (10) has a projection (11) extending into the working fluid container inner cavity (2); and is

-the first electrode (71) and the second electrode (72) of the capacitor (70) are embedded in the bump (11).

13. Operating fluid container (1) according to any one of claims 10 to 12, characterized by the following features:

-the container wall (10, 20, 30) has an outer layer (41), an inner layer (45) facing the working fluid container interior (2), and an adhesive layer (44) arranged between the outer layer and the inner layer;

-the first electrode (61, 71) and the second electrode (62, 72) of the at least one capacitor (60) are arranged between the outer layer (41) and the adhesive layer (44).

14. Operating fluid container (1) according to any one of claims 10 to 13, characterized by the following features:

-the container wall (10, 20, 30) has a shielding layer (42) and an insulating layer (43);

-the shielding layer (42) is arranged between the outer layer (41) and the first and second electrodes (61, 62; 71, 72); and is

-the insulating layer (43) is arranged between the shielding layer (42) and the first and second electrodes (61, 62; 71, 72).

15. Operating fluid container (1) according to claim 14, characterized in that the insulating layer (43) has the same dielectric constant as the inner layer (45) and/or the outer layer (41).

Technical Field

The invention relates to a method for determining the aggregation state of an aqueous working fluid in a working fluid container for a motor vehicle. The invention also relates to a working fluid container for carrying out the method.

Background

In the following, reference is also made to a working fluid container for a motor vehicle, which is designed as a water container. The working fluid container according to the invention is in particular a water container for a motor vehicle for storing water to be injected into the intake pipe of an internal combustion engine, for example, a urea container, a washing water container, an auxiliary fluid container for a motor vehicle

Or additive containers, but not limited thereto. Containers of the above type are typically made in an extrusion blow molding process, with HDPE (High Density Polyethylene) being particularly suitable for making extrusion blow molded containers. In addition, the respective operating fluid container can also be produced by means of an injection molding process.

Water injection is one method used to increase the power of an internal combustion engine. In order not to exceed the maximum temperature at maximum power, distilled water is injected into the intake pipe of the internal combustion engine. The liquid has a cooling effect when evaporating and the compression work can be reduced. In practice, injection is also performed during the combustion phase to generate steam power and reduce exhaust temperature, thereby reducing exhaust backpressure. The injection of water contributes to the reduction of harmful emissions, in particular nitrogen oxides, of the internal combustion engine. The water injected into the intake pipe causes an effective charge air cooling by the heat of evaporation to be applied, whereby an internal cooling of the internal combustion engine is also achieved. As the combustion air becomes cooler, its density increases, thereby achieving the effect of increasing power.

The water can be filled on the premise that the water stored in the working fluid container has a liquid state of aggregation, so that the water can be conveyed by a pump. For example, the same is true for the urea solution stored in the working fluid container. At temperatures around the freezing point, the water in the working fluid container may have a partly solid and partly liquid state of aggregation, and may therefore be pumped. At temperatures well below freezing, the working fluid freezes mostly or completely, which makes it impossible to deliver the aqueous working fluid. As soon as the operating fluid has a partially solid state of aggregation, i.e. as soon as ice is present in the operating fluid container, the delivery of the operating fluid can no longer be ensured, so that countermeasures have to be taken. On the one hand, the vehicle can be prevented from operating during periods in which the operating fluid cannot be delivered. Further, a heating device for heating the working fluid in the working fluid container is activated.

Disclosure of Invention

The invention aims to provide a method for measuring the aggregation state of an aqueous working fluid in a working fluid container for an automobile.

The object of the invention is achieved by a method having the features of claim 1. Advantageous embodiments of the method are described in the dependent claims of claim 1.

More specifically, the solution to achieve the object of the invention is a method for determining the aggregation state of a working fluid in a working fluid container for a motor vehicle, wherein the working fluid container has at least one capacitor which is fastened to a container wall of the working fluid container and has a first electrode and a second electrode arranged opposite the first electrode. The method of the invention is characterized by the following method steps A, B, C and D:

A) applying at least one first alternating voltage to the capacitor, wherein a first frequency of the first alternating voltage corresponds to a lower limit frequency;

B) determining and storing a first impedance of the capacitor for the first frequency;

C) determining a first phase angle from the first impedance; and is

D) When the first phase angle is larger than a first limit angle, determining that the working fluid in the working fluid container has a solid aggregation state.

The advantage of the method according to the invention is that the measuring device (here the capacitor) can reliably determine or ascertain whether the operating fluid stored in the operating fluid container has a solid state of aggregation and is therefore present as ice, without the operating fluid having to be brought into direct contact with it. The impedance of the at least one capacitor and the phase angle derived from the impedance are related to the state of aggregation of the working fluid stored in the working fluid container. The state of aggregation of the working fluid in the interior of the working fluid container can thus be inferred by determining the impedance and/or the phase angle derived from this impedance.

The frequency-dependent impedance of the capacitor and the phase angle derived from this impedance are related to the relaxation frequency (relax frequency) of the material penetrated by the alternating electric field between the first and second electrodes. In this way, the frequency-dependent impedance of the capacitor and the phase angle derived from this impedance are dependent on the material of the container wall and the working fluid located in the interior of the working fluid container. The frequency-dependent impedance of the capacitor and the phase angle derived from this impedance are therefore dependent on the relaxation frequency of the oriented polarization of the water molecules of the operating fluid. The relaxation frequency of water in the liquid state of aggregation lies in the range of several GHz, while the relaxation frequency of water in the solid state of aggregation (i.e. ice) lies in the range of several kHz.

The applicant has found that, on the basis of the frequency-dependent variable and the frequency-dependent characteristic of the phase angle derived from the capacitor impedance, it is possible to unambiguously infer the state of aggregation of the operating fluid stored in the operating fluid reservoir. The applicant therefore concluded that: when the working fluid in the working fluid container has a solid state of aggregation, the phase angle derived from the capacitor impedance is greater than a predetermined first limit angle for an alternating voltage frequency corresponding to the lower limit frequency. Wherein the lower frequency of the alternating voltage applied to the capacitor is related to the geometry of the capacitor, the size of the electrodes of the capacitor and the distance between the electrodes of the capacitor.

Preferably, the first limit angle is-85 °. The lower frequency is preferably 10 kHz. In this way, when the working fluid in the working fluid container has a solid state of aggregation, that is, when the aqueous working fluid is frozen and exists as ice, the phase angle derived from the capacitor impedance is at least-85 ° in the case where the alternating voltage applied to the capacitor has a frequency of 10 kHz.

The operating fluid container is preferably an operating fluid container for a motor vehicle. Further preferably, the operating fluid container is designed as a water container for a motor vehicle for receiving water to be injected into a motor vehicle internal combustion engine. Further preferably, the operating fluid container is designed as a urea container for accommodating an aqueous urea solution to be injected into the exhaust line of the internal combustion engine.

When the first phase angle is larger than the first limit angle, the stop signal is preferably output. By outputting the stop signal, the vehicle can be prevented from running.

In method step a, the lower limit frequency is dependent on the geometry and size of the capacitor and can thus vary. In particular, the lower limit frequency is 10 kHz.

The phase angle is the angle between the voltage applied across the capacitor and the current flowing in the capacitor.

The phase angle between the voltage and the current is therefore determined in method step C.

The loss angle is the difference between-90 ° and the impedance phase angle.

Thus, method step C can also be expressed as: a first loss angle of the capacitor is determined for a first frequency. In this case, method step D can be expressed as: when the first loss angle is larger than the first limit loss angle, the working fluid in the working fluid container is determined to have a solid aggregation state.

Preferably, the first limiting loss angle is 5 °. The lower frequency is preferably 10 kHz. As such, when the working fluid in the working fluid container has a solid state of aggregation, that is, when the aqueous working fluid is frozen and exists as ice, the phase angle derived from the capacitor impedance is at least 5 ° in the case where the alternating voltage applied to the capacitor has a frequency of 10 kHz.

The method preferably has the following method steps:

E) applying a second alternating voltage to the capacitor, wherein a second frequency of the second alternating voltage corresponds to an upper limit frequency;

F) determining and storing a second impedance of the capacitor for the second frequency;

G) determining a second phase angle from the second impedance; and is

H) When the first phase angle is smaller than the first limit angle and the difference between the second phase angle and the first phase angle is larger than a second limit angle, determining that the working fluid in the working fluid container has an aggregation state of a solid part and an aggregation state of a liquid part.

The method according to the invention has the advantage that the capacitor can reliably determine or determine whether the operating fluid stored in the operating fluid container has a partially solid state of aggregation and a partially liquid state of aggregation without the capacitor having to be in direct contact with the operating fluid. The working fluid stored in the working fluid container is present partly in liquid form and partly in frozen form, which is formed in particular at a temperature in the range of the freezing point of the working fluid.

Preferably, an alarm signal is output in or after method step H. Therefore, the alarm signal is output when the working fluid stored in the working fluid container is partially in a solid state of aggregation and partially in a liquid state of aggregation.

By outputting an alarm signal, it is possible to indicate to a user of the vehicle in which the operating fluid container is installed that the operating fluid located in the interior of the operating fluid container has at least partially frozen. By outputting the warning signal, in particular a heating device for heating the operating fluid stored in the operating fluid container can be activated.

Both the lower and upper limit frequencies are related to the geometry and size of the capacitor and may thus vary. Specifically, the lower limit frequency is 10kHz and the upper limit frequency is 100 kHz.

Preferably, the second limiting angle is 7 °. When the aqueous working fluid stored in the working fluid container has a partially solid state of aggregation and a partially liquid state of aggregation, the difference between the phase angle at the upper limit frequency (which may be, for example, 100kHz) and the phase angle at the lower limit frequency (which may be, for example, 10kHz) exceeds 7 °.

Preferably, more than two alternating voltages are applied to at least one capacitor. Several alternating voltages to be applied to the at least one capacitor each have a different frequency in a frequency range between a lower and an upper frequency.

The frequency spacing of adjacent alternating voltages is preferably variable and is related to the geometry and dimensions of the capacitor and the measurement resolution desired. In particular, the frequency interval between the frequencies of the different alternating voltages is 1 kHz.

The method preferably has the following method steps:

I) determining that the working fluid in the working fluid container has a liquid state of aggregation when the first phase angle is smaller than the first limit angle and the difference between the second phase angle and the first phase angle is smaller than the second limit angle.

Preferably, the enable signal (freigabessignal) is output in or after method step I. Therefore, the enable signal is output when the working fluid stored in the working fluid container is in a liquid state of aggregation.

By outputting the enable signal, the control device of the motor vehicle can be informed in particular: the working fluid in the inner cavity of the working fluid container is in a liquid state of aggregation, so that the automobile can run.

The method preferably has the following method steps:

c') determining a first capacitance of said capacitor based on said first impedance;

g') determining a second capacitance of the capacitor based on the second impedance

L) determining the relative deviation of the second capacitance from the first capacitance; and is

D) Determining that the working fluid in the working fluid container has a solid state of aggregation when the relative deviation of the second capacitance from the first capacitance is greater than a first capacitance deviation.

With a correspondingly designed method, a further increased accuracy is achieved and thus icing of the working fluid stored in the working fluid container can be reliably detected. In this way, a vehicle equipped with a working fluid container for carrying out the corresponding method will have a higher operating safety.

The applicant has found that the capacitance of the capacitor drops more between the lower and upper limit frequencies when the aqueous working fluid is in the solid state of aggregation than when the aqueous working fluid is in the liquid state of aggregation. The lower and upper frequencies of the alternating voltage applied to the capacitor are dependent on the geometry of the capacitor, the size of the electrodes of the capacitor, the distance between the electrodes of the capacitor and the desired measurement resolution.

The applicant has found that for an aqueous working fluid in a working fluid container, when the aqueous working fluid has a solid state of aggregation, the frequency dependent capacitance of the capacitor decreases by at least 20% over a frequency range between 10kHz and 100 kHz. Therefore, the first capacitance deviation is 20%.

However, this frequency range may vary as a function of the size and geometry of the capacitor.

The method preferably has the following method steps:

H) when the relative deviation of the second capacitance and the first capacitance is smaller than the first capacitance deviation and larger than a second capacitance deviation, determining that the working fluid in the working fluid container has a solid aggregation state in part and a liquid aggregation state in part.

With a correspondingly designed method, a further increased accuracy is achieved and thus icing of the working fluid stored in the working fluid container can be reliably detected. In this way, a vehicle equipped with a working fluid container for carrying out the corresponding method will have a higher operating safety.

The applicant has found that for an aqueous working fluid in a working fluid container, when the aqueous working fluid has a partially solid state of aggregation and a partially liquid state of aggregation, the frequency dependent capacitance of the capacitor decreases with an amplitude below 20% and above 5% in a frequency range between 10kHz and 100 kHz. Therefore, the first capacitance deviation is 20% and the second capacitance deviation is 5%.

The method preferably has the following method steps:

I) determining that the working fluid in the working fluid container has a liquid state of aggregation when the relative deviation of the second capacitance from the first capacitance is smaller than a second capacitance deviation.

With a correspondingly designed method, the accuracy is further increased and the liquid state of aggregation of the operating fluid stored in the operating fluid container can thus be determined reliably. In this way, a vehicle equipped with a working fluid container for carrying out the corresponding method will have a higher operating safety.

The object of the invention is also achieved by a method according to the invention as claimed in claim 7. Advantageous embodiments of the method are described in the dependent claims of claim 7.

More specifically, the solution to achieve the object of the invention is a method for determining the aggregation state of a working fluid in a working fluid container for a motor vehicle, wherein the working fluid container has at least one capacitor which is fastened to a container wall of the working fluid container and has a first electrode and a second electrode arranged opposite the first electrode. The method of the invention is characterized by the following method steps J, K, L and M:

J) applying at least two different alternating voltages to the capacitor, wherein a first frequency of the first alternating voltage corresponds to a lower limit frequency and a second frequency of the second alternating voltage corresponds to an upper limit frequency;

K) determining and storing a first capacitance of the capacitor for the first frequency and a second capacitance of the capacitor for the second frequency;

l) determining the relative deviation of the second capacitance from the first capacitance; and is

M) determining that the working fluid in the working fluid container has a solid state of aggregation when the relative deviation of the second capacitance from the first capacitance is greater than a first capacitance deviation.

The advantage of the method according to the invention is that the measuring device (here the capacitor) can reliably determine or ascertain whether the operating fluid stored in the operating fluid container has a solid state of aggregation and is therefore present as ice, without the operating fluid having to be brought into direct contact with it. The capacitance of the at least one capacitor is related to the state of aggregation of the working fluid stored in the working fluid reservoir. The state of aggregation of the working fluid in the interior of the working fluid container can thus be inferred by measuring the frequency-dependent capacitance of the capacitor.

The state of aggregation of the working fluid stored in the working fluid reservoir is related to the capacitance of the capacitor, which in turn is related to the medium penetrated by the alternating electric field between the first and second electrodes of the capacitor. This allows the state of aggregation of the working fluid to be inferred by measuring the frequency dependent capacitance of the capacitor.

The frequency dependent capacitance of the capacitor is related to the conductivity of the medium penetrated by the alternating electric field between the first and second electrodes of the capacitor. The frequency-dependent capacitance of the capacitor is therefore dependent on the material of the container wall and the state of aggregation of the operating fluid located in the interior of the operating fluid container.

The applicant has found that the state of aggregation of the operating fluid can be unambiguously deduced from the capacitance characteristic of the capacitor as a function of the frequency of the applied alternating voltage. The applicant therefore concluded that: when the working fluid has a solid state of aggregation, the capacitance characteristic curve of the capacitor must have a certain deviation, for example a certain drop, between the lower limit frequency and the upper limit frequency. Wherein the lower and upper frequencies of the alternating voltage applied to the capacitor are related to the geometry of the capacitor, the size of the electrodes of the capacitor and the distance between the electrodes of the capacitor.

Applicants have found that for an aqueous working fluid stored in a working fluid container having a conductivity of about 130 mus/cm, there is at least a 20% deviation in the capacitance of the capacitor over the frequency range of 10kHz to 100 kHz. Thus, the difference between the capacitance of the capacitor at a frequency of 100kHz and the capacitance of the capacitor at a frequency of 10kHz is at least 20%. However, this frequency range may vary as a function of the size and geometry of the capacitor.

The operating fluid container is preferably an operating fluid container for a motor vehicle. Further preferably, the operating fluid container is designed as a water container for a motor vehicle for receiving water to be injected into a motor vehicle internal combustion engine. Further preferably, the operating fluid container is designed as a urea container for accommodating an aqueous urea solution to be injected into the exhaust line of the internal combustion engine.

In carrying out method step L for determining the relative deviation of the second capacitance from the first capacitance, the following calculation is carried out:

delta＝|Cfmin–Cfmax|/Cfmin

wherein:

-fmin is the lower limit frequency

-fmax is the upper frequency limit

-Cfmin is the first capacitance of the capacitor at which the alternating voltage has a lower limit frequency fmin

-Cfmax is the second capacitance of the capacitor at which the alternating voltage has an upper limit frequency fmax

Delta is the relative deviation of the second capacitance Cfmax from the first capacitance Cfmin

The first minimum deviation is preferably greater than 0.2.

For example, in the case of tap water, and in the case of a lower limit frequency of 10kHz and an upper limit frequency of 100kHz, if the length of the electrodes of the capacitor extends to 100mm, the width extends to 50mm, and the distance from the first electrode to the second electrode is 10mm, the minimum deviation is, for example, about 0.2.

When the relative deviation of the second capacitor from the first capacitor is larger than the deviation of the first capacitor, the stop signal is preferably output. By outputting the stop signal, the vehicle can be prevented from running.

The method preferably has the following method steps:

n) when the relative deviation of the second capacitor and the first capacitor is smaller than the first capacitor deviation and larger than a second capacitor deviation, determining that the working fluid in the working fluid container has a solid aggregation state in part and a liquid aggregation state in part.

The method adopting the corresponding design has the following advantages: the capacitor can reliably determine or determine whether the working fluid stored in the working fluid container has a partially solid state of aggregation and a partially liquid state of aggregation without direct contact with the working fluid. The aqueous working fluid stored in the working fluid container is present partly in liquid form and partly in frozen form, which is formed in particular at a temperature in the range of the freezing point of the working fluid.

Preferably, an alarm signal is output in or after method step N. Therefore, the alarm signal is output when the working fluid stored in the working fluid container is partially in a solid state of aggregation and partially in a liquid state of aggregation.

By outputting an alarm signal, it can be indicated to a user of the vehicle in which the operating fluid container is installed that the operating fluid located in the interior of the operating fluid container has at least partially frozen and is partially present as ice. By outputting the warning signal, in particular a heating device for heating the operating fluid stored in the operating fluid container can be activated.

The method preferably has the following method steps:

o) determining that the working fluid in the working fluid container has a liquid state of aggregation when the relative deviation of the second capacitance from the first capacitance is smaller than a second capacitance deviation.

Preferably, the enable signal is output in or after method step O. Therefore, the enable signal is output when the working fluid stored in the working fluid container is in a liquid state of aggregation.

By outputting the enable signal, the control device of the motor vehicle can be informed in particular: the working fluid in the inner cavity of the working fluid container is in a liquid state of aggregation, so that the automobile can run.

It is also an object of the invention to provide a working fluid container which is designed for determining the state of aggregation of a working fluid located in the working fluid container.

This object is achieved by a working fluid container having the features of claim 10. Advantageous embodiments of the working fluid container are described in the dependent claims of claim 10.

More precisely, the solution to achieve the object of the invention is a working fluid container whose working fluid container interior is delimited by a top wall, a bottom wall and a side wall connecting the bottom wall and the top wall. The operating fluid container has at least one capacitor which is attached to a container wall of the operating fluid container and has a first electrode and a second electrode. The working solution container is also provided with an electronic analysis device which is electrically connected with the first electrode and the second electrode. The working fluid container of the present invention is characterized in that: the analysis device is constructed for carrying out at least one of the methods described above.

The at least one capacitor is preferably mounted on or in a side wall of the operating fluid container. It is further preferred that the at least one capacitor is arranged on or in the side wall in such a way that the first and second electrodes, each having a longitudinal extension, a width extension and a depth extension, each extend parallel to the side wall, so that the longitudinal extension of the first and second electrodes runs in the direction from the bottom wall to the top wall.

According to a further embodiment of the operating fluid container, the at least one capacitor is arranged on or in the bottom wall such that the first and second electrodes each extend parallel to the bottom wall.

At least one capacitor may be arranged outside and connected to the container wall. Furthermore, at least one capacitor can also be integrated or embedded in the container wall. Wherein the first and second electrodes of the capacitor are surrounded by the container wall.

The working fluid container is preferably designed as follows: the at least one capacitor is embedded in the container wall.

In the case of a capacitor with electrodes embedded in the container wall, the electrodes are surrounded by the container wall, so that only the electrical connections of the electrodes still project from the container wall.

The working fluid container with the corresponding design has the following advantages: since the at least one capacitor is embedded in the wall of the operating fluid container, the distance between the first and second electrodes of the at least one capacitor and the interior of the operating fluid container is reduced, and thus the distance between the first and second electrodes and the operating fluid located in the interior of the operating fluid container is also reduced. The electric field between the first and second electrodes of the capacitor therefore interacts less with the material of the container wall and more with the working fluid located in the interior of the working fluid container. In this way, the state of aggregation of the operating fluid in the interior of the operating fluid container can be determined with increased accuracy.

A further advantage achieved by embedding the at least one capacitor in the container wall is that the at least one capacitor is mechanically and chemically protected, so that the inventive operating fluid container has an increased long-term stability.

The operating fluid container is designed in particular for a motor vehicle.

The working fluid container is preferably designed as follows: the bottom wall has a protrusion extending into the working fluid container interior cavity, wherein the first and second electrodes of the capacitor are embedded in the protrusion.

With a correspondingly designed operating fluid container, the state of aggregation of the operating fluid can be determined with further increased accuracy, since the influence of deposits possibly present in the region of the base wall on the determination of the state of aggregation of the operating fluid in the interior of the operating fluid container can be reduced.

The projection of the bottom wall is preferably formed as a recess into the interior of the operating fluid container.

The protrusion preferably rises from 2mm to 5mm from the surrounding inner surface of the bottom wall.

The working fluid container is preferably designed as follows: the container wall has an outer layer, an inner layer facing the working fluid container interior cavity, and an adhesive layer disposed between the outer layer and the inner layer, wherein the first electrode and the second electrode of the at least one capacitor are disposed between the outer layer and the adhesive layer.

Thus, at least one capacitor is arranged between the outer layer and the adhesive layer. Thus, the inner layer may directly contact the working fluid.

The corresponding design of the operating fluid container contributes to a simplification of the construction of the capacitor and makes it easier to integrate the capacitor into the container wall of the operating fluid container.

The working fluid container is preferably designed as follows: the container wall has a shielding layer and an insulating layer, wherein the shielding layer is disposed between the outer layer and the first and second electrodes, and wherein the insulating layer is disposed between the shielding layer and the first and second electrodes.

The advantage of using a correspondingly designed operating fluid container is that it has a further increased accuracy in determining the state of aggregation of the operating fluid located in the interior of the operating fluid container. Because the shielding layer formed as a metal layer preferably shields the electrodes of the at least one capacitor from interfering fields.

The shielding layer is therefore arranged between the outer layer and the reference capacitor or capacitors.

The shield layer is preferably in contact with the outer layer.

Therefore, the insulating layer is arranged between the shielding layer and the capacitor in a sandwich shape.

The shielding layer has a metal, thereby protecting the at least one capacitor from disturbing electric fields.

The insulating layer is made of a dielectric material, preferably plastic, so that the first and second electrodes of the at least one capacitor are not in electrical contact with the shielding layer.

The working fluid container is preferably designed as follows: the insulating layer has the same dielectric constant as the inner layer and/or the outer layer.

The advantage of using a correspondingly designed operating fluid container is that it has a further increased accuracy in determining the state of aggregation of the operating fluid located in the interior of the operating fluid container.

The working fluid container is preferably designed as follows: the distance between the first electrode and the second electrode and the inner cavity of the working fluid container is between 1.5mm and 3.5 mm.

The advantage of using a correspondingly designed operating fluid container is that it has a further increased accuracy in determining the state of aggregation of the operating fluid located in the interior of the operating fluid container, since the distance of the respective electrode to the operating fluid located in the interior of the operating fluid container is reduced.

Therefore, the inner layer preferably has a thickness of 1.5mm to 3.5 mm.

The distance of the at least one capacitor from the interior of the working fluid container is therefore only 1.5mm to 3.5 mm.

The working fluid container is preferably designed as follows: at least one of the first and second electrodes of the capacitor has a non-uniform width extension along its longitudinal extension.

The wider the electrode, the greater the penetration depth of the electric field in the interior of the working fluid container and in the working fluid located in the interior of the working fluid container, so that the working fluid has a greater influence on the determination of the state of aggregation of the working fluid.

The working fluid container is preferably designed as follows: at least one of the first and second electrodes of the capacitor has a width extension along its longitudinal extension which becomes larger towards the bottom wall.

The advantage of using a correspondingly designed operating fluid container is that the measuring accuracy of the capacitor for the state of aggregation in the bottom region of the operating fluid container is increased.

Drawings

Further advantages, details and characteristics of the invention can be taken from the examples set forth below. Wherein, specifically:

FIG. 1 is a flow chart of a method of determining the state of aggregation of an aqueous working fluid according to a first embodiment of the present invention;

FIG. 2 is a frequency dependent phase characteristic of capacitor impedance for an aqueous working fluid having three different temperatures;

FIG. 3 is a flow chart of a method of determining the state of aggregation of an aqueous working fluid according to a second embodiment of the present invention;

FIG. 4 is a frequency dependent capacitance characteristic of a capacitor for an aqueous working fluid having three different temperatures;

FIG. 5 is a flow chart of a method of determining the state of aggregation of an aqueous working fluid according to a third embodiment of the present invention;

FIG. 6 is a simplified perspective view of the working fluid container of the present invention;

FIG. 7 is a very simplified view of the layer structure of the bottom wall and/or the side walls of a working fluid container according to a further embodiment of the invention; and

fig. 8A to 8C are separate side plan views of capacitor examples of the operating fluid container according to various embodiments of the present invention.

Detailed Description

In the following description, the same reference numerals are used for the same components or the same features, and thus, the description for one component with reference to one drawing is also applicable to other drawings to avoid the repetition of the description. Furthermore, individual features described in connection with one embodiment may also be applied to other embodiments separately.

Fig. 1 shows a flowchart of a method of determining an aggregation state of an aqueous working fluid in a working fluid container 1 according to a first embodiment of the present invention. The method according to the flow chart shown in fig. 1 is carried out by the operating fluid container 1 shown in fig. 6.

Fig. 6 shows a very schematic perspective view of a working fluid container 1 according to the invention. The working fluid container interior 2 is delimited by a top wall 30, a bottom wall 10 and a side wall 20 connecting the bottom wall 10 to the top wall 30. As shown in fig. 6, the sidewall 20 is circumferentially formed.

The working fluid container 1 shown in fig. 6 has a first capacitor 60 and a second capacitor 70. However, according to the invention, the operating fluid container 1 can also have only the first capacitor 60 or only the second capacitor 70. In addition, the operating fluid container 1 may also have other capacitors not shown in fig. 6.

The first capacitor 60 has a first electrode 61 and a second electrode 62. The first electrode 61 and the second electrode 62 each have a longitudinal extension L, a width extension B and a depth extension (see fig. 8A to 8C), respectively. Wherein the first electrode 61 and the second electrode 62 are respectively arranged to extend parallel to the side wall 20 such that the longitudinal extension L of the first electrode 61 and the second electrode 62 runs from the bottom wall 10 towards the top wall 30. Wherein the first electrode 61 and the second electrode 62 extend in depth to be disposed opposite to each other.

The first capacitor 60 is embedded in the sidewall 20, which causes the first electrode 61 and the second electrode 62 of the first capacitor 60 to be embedded in the sidewall 20. Thus, the first capacitor 60 is surrounded by the sidewall 20. As a result, the first electrode 61 and the second electrode 62 of the first capacitor 60 do not directly contact the working fluid 50 (see fig. 7). In addition, the first electrode 61 and the second electrode 62 of the first capacitor 60 do not directly contact the ambient environment of the working fluid container 1. With regard to the embedding of the first capacitor 60 in the sidewall 20, reference is made to fig. 6, which will be described below.

However, the present invention is not limited to embedding the first capacitor 60 in the sidewall 20. In the working fluid container 1 of the present invention, the first capacitor 60 may be fixed to the outer surface of the side wall 20.

As shown in fig. 6, the first electrode 61 and the second electrode 62 of the first capacitor 60 each have two wings 63 extending parallel to the width extension B of the electrodes 61, 62. Wherein the wings 63 are formed at different heights of the first and second electrodes 61, 62, and thus the wings 63 are disposed at different heights of the operating fluid container 1. As such, the first and second electrodes 61, 62 of the first capacitor 60 have a non-uniform width extension B along their longitudinal extension L. However, the invention is not limited to a corresponding design of the first and second electrodes 61, 62 of the first capacitor 60. For example, the first and second electrodes 61, 62 of the first capacitor 60 may also have a uniform width extension B over their longitudinal extension L.

The second capacitor 70 has a first electrode 71 and a second electrode 72. The first electrode 71 and the second electrode 72 extend parallel to the bottom wall 10. Wherein the first electrode 71 and the second electrode 72 are arranged to extend parallel to the bottom wall 10 such that the longitudinal extension and the width extension of the first electrode 71 and the second electrode 72 are distributed in the plane of the bottom wall 10, which is such that the depth extensions of the first electrode 71 and the second electrode 72 are arranged opposite to each other.

As shown in fig. 6, the bottom wall 10 has a projection 11 which extends into the interior 2 of the operating fluid container. The second capacitor 70 is embedded in the bottom wall 10 such that the first electrode 71 and the second electrode 72 of the second capacitor 70 are embedded in the projection 11 of the bottom wall 10. As a result, the first electrode 71 and the second electrode 72 of the second capacitor 70 do not directly contact the working fluid 50. In addition, the first electrode 71 and the second electrode 72 of the second capacitor 70 do not directly contact the ambient environment of the working fluid container 1. By embedding the first electrode 71 and the second electrode 72 in the protrusion 11 of the bottom wall 10, the influence of the deposits possibly present on the bottom wall 10 on the determination of the aggregation state of the working fluid 50 in the inner chamber 2 of the working fluid container can be reduced.

With regard to the embedding of the second capacitor 70 in the bottom wall 10 or in the projection 11 of the bottom wall 10, reference is made to fig. 7, which will be explained below.

However, the present invention is not limited to embedding the second capacitor 70 in the bottom wall 10. In the working fluid container 1 of the present invention, the second capacitor 70 may be fixed to the outer surface of the bottom wall 10.

The working fluid container 1 further has an electronic analysis device 80 electrically connecting the first capacitor 60 and the second capacitor 70. The electrical connection of the analysis means 80 to the first capacitor 60 and the second capacitor 70 is realized by means of wires not shown in fig. 6.

The analysis device 80 is designed to carry out a method according to the flowchart shown in fig. 1, as will be explained below.

In method step a, at least one first alternating voltage is applied to first capacitor 60 and/or second capacitor 70. The first frequency of the first ac voltage corresponds to a lower limit frequency fmin, which in the illustrated embodiment is 10 kHz.

In method step B, a first impedance of the first capacitor 60 and/or the second capacitor 70 is determined and stored for a first frequency.

Subsequently, in method step C, a first phase angle is determined from the first impedance

Fig. 2 is three different frequency-dependent phase characteristic curves of the impedance of the first capacitor 60 and/or the second capacitor 70 for an aqueous working fluid 50 having three different temperatures. Wherein the characteristic curve 91 is a phase characteristic curve of impedance for an aqueous working fluid at a temperature of-15 ℃. Characteristic curve 92 is a frequency-dependent characteristic curve of the impedance phase angle for a working fluid at a temperature of-2 ℃. Characteristic curve 93 is a frequency-dependent characteristic curve of the impedance phase angle for a working fluid at a temperature of +3 ℃.

As can be seen from the characteristic curve 91 of the impedance phase angle of the capacitors 60, 70 shown in FIG. 2 when the temperature of the working fluid is-15 deg.C, the first phase angleGreater than a first limit angle 1 depicted in fig. 2 at a lower frequency fmin of 10kHz, wherein the first limit angle 1 is-85 deg. in the illustrated embodiment.

Returning to the method according to the flow chart shown in fig. 1, the first phase angle is checked after method step C

Is greater than the first limit angle 1. If this condition is met, it is determined in method step D that the operating fluid 50 located in the operating fluid container 1 has a solid aggregate state and is therefore present as ice. According to a characteristic curve 91 of impedance phase angles of the capacitors 60, 70 at a temperature of-15 deg.C of the working fluid shown in FIG. 2, a first phase angle

About-83. The first limit angle 1 is then-85. Thus for a working fluid having a temperature of-15 deg.C, the first phase angleThe condition of greater than the first limiting angle 1 is satisfied, so that in method step D it is determined that the operating fluid has a solid state of aggregation.

If the first phase angleNo greater than first limit angle 1, a second ac voltage is applied to first capacitor 60 and/or second capacitor 70 in method step E, the second frequency of the second ac voltage corresponding to upper limit frequency fmax. In the illustrated embodiment, the upper frequency is 100 kHz. In method step F, a second resistance of first capacitor 60 and/or second capacitor 70 is then determined and stored for a second frequencyAnd (3) resisting. In a method step G following method step F, a second phase angle is determined from the second impedance

Then checking the second phase angle

At a first phase angle

Whether the absolute value of the difference is greater than the second limit angle 2. If this condition is met, it is determined in method step H that the operating fluid 50 located in the operating fluid container 1 has partly a solid state of aggregation and partly a liquid state of aggregation. Therefore, only when the first phase angle

Less than a first limit angle 1 and a second phase angleAt a first phase angleOnly if the absolute value of the difference is greater than the second limiting angle 2 is method step H performed.

As can be seen from the characteristic curve 92 of the impedance phase angle of the capacitors 60, 70 at a temperature of-2 deg.C of the working fluid shown in FIG. 2, the first phase angleAt a lower frequency fmin of 10kHz, about-87.5 DEG, and a second phase angleAt an upper frequency fmax of 100kHz, about-77.5. Thus, the second phase angleAt a first phase angleThe absolute value of the difference is 10 °. In the illustrated embodiment, the second limiting angle 2 is 7 °. Due to the first phase angleLess than a first limit angle 1 and a second phase angle

At a first phase angleThe absolute value of the difference is greater than 7 °, so that for the phase angle characteristic shown in fig. 2, it is determined in method step H that the operating fluid located in the operating fluid container 1 has a partially solid state of aggregation and a partially liquid state of aggregation, so that partial icing occurs.

Alternatively, method steps E, F and G can also be carried out directly after method step C.

If the second phase angle

At a first phase angleIf the absolute value of the difference is less than the limiting angle 2, it is determined in method step I that the operating fluid 50 located in the operating fluid container 1 has a liquid state of aggregation.

As can be seen from a characteristic curve 93 of the impedance phase angles of the capacitors 60, 70 at the temperature of +3 deg.c of the operating fluid shown in fig. 2, the first phase angle

At a lower frequency fmin of 10kHz, about-90 DEG, and a second phase angleAt an upper frequency fmax of 100kHz, about-85.5. Thus, the second phase angle

At a first phase angle

The absolute value of the difference is 4.5 °. In the illustrated embodiment, the second limiting angle 2 is 7 °. Due to the first phase angle

Less than a first limit angle 1 and a second phase angle

At a first phase angle

The absolute value of the difference is less than 7 °, so that, for the phase angle characteristic 93 shown in fig. 2, it is determined in method step I that the operating fluid located in the operating fluid container 1 has a liquid state of aggregation.

The analysis device 80 of the operating fluid container 1 shown in fig. 6 is further designed to carry out a method according to the flowchart shown in fig. 3, as will be explained below.

In method step J, at least two different alternating voltages having different frequencies are applied to first capacitor 60 and/or second capacitor 70. The first frequency of the first ac voltage corresponds to the lower limit frequency fmin. The second frequency of the second alternating voltage corresponds to the upper limit frequency fmax.

Next, in method step K, a first capacitance C1 of the first capacitor and/or of the second capacitor 70 is determined and stored for the first frequency. Furthermore, a second capacitance C2 of first capacitor 60 and/or second capacitor 70 is determined and stored for the second frequency in method step K.

Subsequently, the relative deviation of the second capacitance C2 from the first capacitance C1 is determined in method step L. Therefore, it is determined in method step L how much percent of the deviation of the second capacitance C2 from the first capacitance C1 is present.

Fig. 4 is three different frequency-dependent capacitance characteristics of the first capacitor 60 and/or the second capacitor 70 for an aqueous working fluid 50 having three different temperatures. Wherein the characteristic curve 101 is a frequency dependent capacitance characteristic curve of the first capacitor 60 and/or the second capacitor 70 for an aqueous working fluid at a temperature of-15 ℃. Characteristic curve 102 is a frequency-dependent capacitance characteristic of first capacitor 60 and/or second capacitor 70 for a working fluid having a temperature of-2 ℃. Characteristic 103 is a frequency-dependent capacitance characteristic of the first capacitor 60 and/or the second capacitor 70 for a working fluid at a temperature of +3 ℃.

As shown in fig. 4, the characteristic curve 101 of the frequency dependent capacitance of the capacitors 60, 70 decreases from the first capacitance C1 to the second capacitance C2 for an aqueous working fluid 50 at a temperature of-15 ℃. Wherein the capacitors 60, 70 have a first capacitance C1 of about 14pF at a lower limiting frequency fmin (10 kHz in the illustrated embodiment) and a second capacitance C2 of about 10pF at an upper limiting frequency fmax (100 kHz in the illustrated embodiment). Thus, the relative deviation of C1 from C2 was approximately 28% when the working fluid temperature was-15 ℃.

As further shown in fig. 4, the frequency dependent capacitance of the capacitors 60, 70 drops from a first capacitance C1 to a second capacitance C2 for an aqueous working fluid 50 at a temperature of-2 ℃. Wherein the capacitor 60, 70 has a first capacitance C1 of about 14.5pF at the lower limit frequency fmin and a second capacitance C2 of about 13pF at the upper limit frequency fmax. Thus, the relative deviation of C1 from C2 was about 10% when the temperature of the working fluid was-2 ℃.

As further shown in fig. 4, the frequency dependent capacitance of the capacitors 60, 70 drops from the first capacitance C1 to the second capacitance C2 for an aqueous working fluid 50 at a temperature of +3 ℃. Wherein the capacitor 60, 70 has a first capacitance C1 of about 15pF at the lower limit frequency fmin and a second capacitance C2 of about 14.6pF at the upper limit frequency fmax. Thus, the relative deviation of C1 from C2 was about 2.6% when the temperature of the working fluid was +3 ℃.

Returning to the method according to the flowchart shown in fig. 3, it is checked after method step L whether the relative deviation of the second capacitance C2 from the first capacitance C1 is greater than the first capacitance deviation Δ C1. More specifically, it is determined whether the following condition is satisfied:

if this condition is met, it is determined in method step M that the operating fluid located in the operating fluid container 1 has a solid aggregate state.

In the illustrated embodiment, the first capacitance deviation Δ C1 has a value of 0.2. With respect to the capacitance characteristic curve 101 shown in fig. 4, it is thereby determined that the operating fluid located in the operating fluid container 1 has a solid state of aggregation, since the relative deviation of the second capacitance C2 from the first capacitance C1 is 28%, i.e., 0.28.

Otherwise, if not satisfied

This condition, it is checked whether the following condition is satisfied:

where Δ C2 is the second capacitance deviation, which is 0.05 in this embodiment. If this condition is met, it is determined in method step N that the operating fluid located in the interior 2 of the operating fluid container has a partially solid state of aggregation and a partially liquid state of aggregation. Therefore, method step N is performed when the value of the relative deviation of the second capacitance C2 from the first capacitance C1 is between the first capacitance deviation Δ C1 and the second capacitance deviation Δ C2, wherein the second capacitance deviation Δ C2 is smaller than the first capacitance deviation Δ C1.

For the capacitance characteristic curve 102 shown in fig. 4, it is thereby determined in method step N that the operating fluid located in the operating fluid container 1 has a partially solid state of aggregation and a partially liquid state of aggregation, since the relative deviation of the second capacitance C2 from the first capacitance C1 is 0.1, so that the condition 0.20>0.10>0.05 is satisfied.

Otherwise, if not satisfied

This condition determines in method step O that the operating fluid present in the operating fluid container 1 has a liquid state of aggregation.

The analysis device 80 of the operating fluid container 1 shown in fig. 6 is further designed to carry out a method according to the flowchart shown in fig. 5, as will be explained below. Wherein the method according to the flowchart shown in fig. 5 is a combination of the method according to the flowchart shown in fig. 1 and the method according to the flowchart shown in fig. 3.

In method step a, at least one first alternating voltage is applied to first capacitor 60 and/or second capacitor 70. The first frequency of the first ac voltage corresponds to a lower limit frequency fmin, which in the illustrated embodiment is 10 kHz.

In method step B, a first impedance of the first capacitor 60 and/or the second capacitor 70 is determined and stored for a first frequency.

Subsequently, in method step C, a first phase angle is determined from the first impedance

In method step C', a first capacitance C1 of the first capacitor 60 and/or the second capacitor 70 is determined and stored for the first frequency.

Subsequently, in method step E, a second alternating voltage is applied to first capacitor 60 and/or second capacitor 70, wherein a second frequency of the second alternating voltage corresponds to upper frequency fmax. In the illustrated embodiment, the upper frequency is 100 kHz. Next, in method step F, a second impedance of first capacitor 60 and/or second capacitor 70 is determined and stored for a second frequency. In a method step G following method step F, a second phase angle is determined from the second impedance

In a method step G', the first capacitor 60 and/or the second electricity is determined and stored for the second frequencyA second capacitance C2 of the container 70.

After method step G, the first phase angle is checked

Whether it is greater than the first limit angle 1 and whether the relative deviation of the second capacitance C2 from the first capacitance C1 is greater than the first capacitance deviation ac 1. If these conditions are met, it is determined in method step D that the operating fluid 50 located in the operating fluid container 1 has a solid aggregate state and is therefore present as ice.

Conversely, if these conditions are not met, the first phase angle is checked

Whether or not it is less than the first limit angle 1, the second phase angleAt a first phase angle

Whether the absolute value of the difference is greater than the second limit angle 2 and whether the relative deviation of the second capacitance C2 from the first capacitance C1 is less than the first capacitance deviation ac 1 and greater than the second capacitance deviation ac 2.

If these conditions are met, it is determined in method step H that the operating fluid 50 located in the operating fluid container 1 has partly a solid state of aggregation and partly a liquid state of aggregation. If these conditions are not met, the liquid in the operating fluid container 1 is determined in method step I to have a liquid state of aggregation.

Fig. 7 shows a very schematic view of the layer structure of the container walls 10, 20, 30 of the operating fluid container 1. The container wall may be the bottom wall 10 and/or the side wall 20 and/or the top wall 30. It can be seen that the container wall 10 has a multilayer structure.

The layer structure of the container walls 10, 20, 30 will be explained below with reference to the bottom wall 10 and the second capacitor 70. However, the side walls 20 and/or the top wall 30 may also have a corresponding layer structure. Furthermore, the first capacitor 60 can also be embedded in the container walls 10, 20, 30 in the same way.

It can be seen that the bottom wall 10 has an outer layer 41, an inner layer 45 facing the interior 2 of the operating fluid container, and an adhesive layer 44 arranged between the outer layer 41 and the inner layer 45. The first electrode 71 and the second electrode 72 of the second capacitor 70 are arranged between the outer layer 41 and the adhesive layer 44. The bottom wall 10 further has a shielding layer 42 and an insulating layer 43, wherein the shielding layer 42 is arranged between the outer layer 41 and the first electrode 71 and the second electrode 72 of the second capacitor 70. The insulating layer 43 is in turn arranged between the shielding layer 42 and the first and second electrodes 71, 72 of the second capacitor 70.

It can further be seen that the bottom wall 10 has an outer layer 41, an inner layer 45 facing the interior 2 of the operating fluid container, and an adhesive layer 44 arranged between the outer layer 41 and the inner layer 45. The first electrode 71 and the second electrode 72 of the second capacitor 70 are arranged between the outer layer 41 and the adhesive layer 44. The bottom wall 10 further has a shielding layer 42 and an insulating layer 43, wherein the shielding layer 42 is arranged between the outer layer 41 and the first and second electrodes 71, 72 of the second capacitor 70. The insulating layer 43 is in turn arranged between the shielding layer 42 and the first and second electrodes 71, 72 of the second capacitor 70.

Fig. 8A shows the first capacitor 60 in isolation in a side plan view. In the illustrated embodiment, it can be seen that the first electrode 61 of the first capacitor 60 has a uniform width extension B along its longitudinal extension L. The second electrode 62 of the first capacitor 60 then has a width extension B which varies along the longitudinal extension of the second electrode 62. It can be seen that the width of the second electrode 62 has a width extension B along its longitudinal extension L which becomes larger towards the bottom wall 10.

Fig. 8B shows another example of the first capacitor 60 according to another embodiment of the operating fluid container 1. It can be seen that the first electrode 61 and the second electrode 62 each have two wings 63 extending along the width extension B of the first and second electrodes 61, 62, respectively, at different heights (i.e. at different positions with reference to the longitudinal extension L of the first and second electrodes 61, 62). It can be seen that each wing 63 is rounded.

Fig. 8C shows the first capacitor 60 of the operating fluid container 1 according to a further embodiment. The first capacitor 60 shown in fig. 8C is also designed as follows: the first electrode 61 and the second electrode 62 each have two wings 63 extending over the width extension B of the associated electrode 61, 62, respectively. Wherein each wing 63 is arranged at a different height of the associated electrode 61, 62.

However, the present invention is not limited to the embodiments of the first capacitor 60 as shown in fig. 8A to 8C, as long as an electric field extending into the interior 2 of the operating fluid container can be generated by means of the first capacitor 60, so that the aggregation state of the aqueous operating fluid 50 can be determined by means of the analysis device 80.

Description of reference numerals

1 working fluid container

2 working fluid container inner cavity

10 (of the working-fluid container) bottom wall

11 (of the bottom wall) projection

20 (of the working fluid container)

30 top wall

41 (of the bottom wall/side wall) outer layer

42 (bottom/side wall) shielding layer

43 (bottom/side wall) insulating layer

44 (bottom/side) adhesive layer

45 (of the bottom wall/side wall) inner layer

50 working fluid

60 first capacitor

61 (of the first capacitor) first electrode

62 (of the first capacitor) second electrode

63 (of the first and/or second electrode)

70 second capacitor

71 first electrode (of a second capacitor)

72 (of the second capacitor) second electrode

80 analysis device

91 frequency-dependent phase response for an aqueous working fluid at a temperature of-15 DEG C

92 frequency-dependent phase response curve for an aqueous working fluid at a temperature of-2 DEG C

93 frequency-dependent phase response for an aqueous working fluid at a temperature of +3 DEG C

101 frequency-dependent capacitance characteristic curve for an aqueous working fluid at a temperature of-15 DEG C

102 frequency dependent capacitance characteristic curve for an aqueous working fluid at a temperature of-2 DEG C

103 frequency dependent capacitance characteristic curve for an aqueous working fluid at a temperature of +3 DEG C

L (of the electrodes of the measuring capacitor) longitudinal extension

B (of the electrodes of the measuring capacitor) width extension

First capacitance of C1 (of capacitor)

Second capacitance of C2 (of capacitor)

Lower limit frequency of fmin

fmax upper frequency limit

First phase angle

Second phase angle

1 first limit angle

2 second limiting angle

Δ C1 first capacitance deviation

Δ C2 second capacitance deviation