Water separator for a fuel cell and method for operating a water separator

Abstract

The invention relates to a water separator (10) for a fuel cell in a vehicle. 1. The water separator comprises a housing having an inlet (15) for supplying exhaust gas from an outlet of a stack of the fuel cell (1) and an outlet (16) for conducting hydrogen gas back to the fuel cell (1). A drain valve (12) is provided for draining liquid water and a gas vent valve (13) is provided for venting gas. A liquid level sensor (30) is arranged in the housing for capacitive liquid level measurement of the liquid water in the water separator (10). The liquid level sensor (30) outputs a measurement signal proportional to the liquid level. Furthermore, the liquid level sensor (30) comprises a sloshing damping and splash protection device (31) as a protection against sloshing waves and water splashes.

Description

Technical Field

[0001] The present invention relates to a water separator for a fuel cell in a vehicle and a method for operating the water separator. Background Technology

[0002] As internal combustion engines are increasingly replaced in vehicle technology, particularly in commercial vehicles, fuel cells are becoming increasingly important because battery-powered drives can result in high vehicle weight and relatively short driving range.

[0003] A fuel cell comprises an anode path (H2 path) and a cathode path (O2 path). In the anode path, hydrogen (H2) carried in a high-pressure container within the vehicle is reduced to intermediate pressure by a pressure reducer and supplied to the fuel cell stack at the desired pressure and quantity via a proportional valve, so as to generate current there for the electric motor used to operate the vehicle. The well-known reactions that occur for this purpose in the fuel cell stack will not be discussed in more detail here.

[0004] Unused or excess hydrogen, along with undesirable harmful gases such as nitrogen (N2) and water droplets or vapor, is supplied to the water separator via the fuel cell outlet. The water separator has the following function: to separate liquid water from the mixture of hydrogen, nitrogen, water vapor, and water droplets, and to temporarily store the mixture in a storage tank at the bottom of the water separator.

[0005] When a predetermined liquid volume is reached, the drain valve is opened at regular intervals to remove liquid water from the water separator and thereby prevent water overflow or backflow into the fuel cell stack. Additionally, the vent valve for removing harmful N2 gas can be opened at regular intervals to remove the harmful gas from the water separator, thus allowing only the lighter hydrogen gas to be supplied to the fuel cell stack in the driest and purest possible state via the recirculator.

[0006] A predetermined liquid volume can be detected by a level sensor, which then triggers the opening of the drain valve. Typically, such a level sensor is positioned on the side wall of the water separator to act as a switch in a so-called horizontal single-point triggering mechanism, detecting the upper limit of the liquid level required to open the drain valve.

[0007] For example, DE 10 2016 115 012 A1 discloses a water separator for a fuel cell system. The water separator has a housing with an input line from an anode exhaust gas line and an output line leading to the anode exhaust gas line. A first output line and a second output line are arranged in the bottom region of the water separator. The first output line has a throttle, and the second output line has an overflow pipe and a valve extending upward into the water separator. The water separator may have a level sensor for determining or detecting the water level in the water separator.

[0008] A liquid container with an anti-sloshing device is known from EP 3 097 978 A1. The anti-sloshing device consists of a tube arranged perpendicularly to the bottom of the liquid container inside the container, the tube having the same base shape as the liquid container. Openings are provided in the tube wall at the upper and lower ends of the tube.

[0009] The known arrangement of level sensors in water separators can have the following drawbacks: they typically only detect the upper limit of the level and therefore can only trigger the opening of the drain valve. The lower limit of the level used to close the drain valve would require an additional sensor in the case of normal level measurement, thus incurring additional costs and occupying additional structural space.

[0010] Tilting and / or orientation of the water separator, for example, due to fluctuations caused by vehicle movement, may cause the water surface to move relative to the level sensor within the water separator, making level measurements inaccurate, or potentially causing a significant deviation from the desired level limit or fill volume of an untilted or unmoved water separator, thereby potentially causing frequent and possibly undesirable switching.

[0011] The sloshing motion of water caused by changes in vehicle movement, and the resulting splashing water, such as during acceleration, braking, and cornering, can create large wave amplitudes and splashes on the walls where sensors are located. This can lead to significant inaccuracies and even overflow of the water separator in the direction of the fuel cell stack. Furthermore, the sensors may be exposed to sloshing motion and splashing water without protection, potentially causing erroneous measurements. Summary of the Invention

[0012] This invention integrates the self-protection function of a capacitive level sensor into a water separator, preventing or reducing sloshing waves and / or splashes onto the signal electrodes of the level sensor. This improves both the measurement accuracy and reliability of the level sensor, establishes a more accurate relationship between the measured level and the volume of water that can be extracted from the water separator, and thus ensures the safe operation of the fuel cell.

[0013] Therefore, according to the present invention, a water separator for a fuel cell in a vehicle having the features of claim 1 and a method for operating the water separator having the features of claim 13 are provided.

[0014] The water separator includes a housing with an inlet and an outlet. The inlet supplies exhaust gas from the fuel cell stack, and the outlet guides hydrogen gas back to the fuel cell. As mentioned earlier, the exhaust gas may contain hydrogen, water vapor, water droplets, and nitrogen. In the water separator, liquid water and harmful gases such as nitrogen are separated from the remaining hydrogen, allowing clean, dry hydrogen to be returned to the fuel cell.

[0015] The water separator includes a discharge valve for discharging liquid water and an vent valve for discharging gas. The discharge valve and vent valve can be electrically or electronically operated or regulated by a control device, for example.

[0016] A level sensor is arranged within the housing to measure the liquid level of the water in the water separator. The level sensor is configured to output a measurement signal proportional to the liquid level. Therefore, the actual liquid level present in the water separator can be measured at any time. In particular, the upper and lower limit values ​​can be measured or detected, enabling control of the discharge valve based on two or more limit values.

[0017] According to the present invention, the liquid level sensor has an inherent, sensor-integrated sloshing damping and splash protection device that protects the measuring electrodes of the liquid level sensor from extremely undulating sloshing waves on the water surface and / or from water splashes. This avoids erroneous measurements. Furthermore, the sloshing damping and splash protection device reduces wave motion on the water surface in the water separator, enabling higher accuracy in liquid level measurement.

[0018] Due to the proportional or continuous measurement signal, intelligent adjustment strategies can be implemented within the measurement range to, for example, dampen swaying motion and thus avoid the continuous opening and closing of the discharge valve in short intervals due to wave amplitude.

[0019] A method for operating a water separator for a fuel cell in a vehicle includes the step of measuring the level of liquid water in the water separator along a vertical measuring axis. In a further step, a measurement signal proportional to the liquid level is generated. The method further includes the steps of opening a drain valve for discharging liquid water when the measurement signal is equal to or greater than a first limit value, and closing the drain valve when the measurement signal is equal to or less than a second limit value, wherein the first limit value is greater than the second limit value.

[0020] Advantageous configurations and extensions are derived from the other dependent claims and from the description with reference to the accompanying drawings.

[0021] Preferably, the measuring axis of the level sensor can be arranged vertically. Vertical arrangement means that, in the installed state of the water separator, the measuring axis extends substantially parallel to the direction of gravity. If the vehicle moves, a slight tilt or orientation deviation of the measuring axis may occur accordingly.

[0022] Preferably, the level sensor may have a capacitive cylindrical capacitor or a capacitive polygonal capacitor. Measurement schemes using cylindrical or polygonal capacitors are advantageous in terms of insensitivity to electrical interference due to the external arrangement of the shielding electrodes. Furthermore, the external, preferably tubular, shielding electrodes also serve as a sloshing damper and splash protection for the measuring electrodes arranged inside the shielding electrodes.

[0023] According to a preferred configuration, the conductive shielding electrode of the level sensor is integrated into a sloshing damping and splash protection device. The sloshing damping and splash protection device can, for example, be constructed as a so-called sensordom. More particularly, the sloshing damping and splash protection device can be constructed as a substantially cylindrical tube made of plastic, in which the shielding electrode is embedded. The shielding electrode can simultaneously serve as a grounding electrode for capacitive level measurement and for shielding against external capacitive interference.

[0024] According to an alternative embodiment, the shielding electrode can also be arranged as a conductive foil on the surface of the sloshing damping and splash-proof device. To protect the foil from water in the level sensor, the conductive foil can be covered with an insulating and sealed protective layer.

[0025] A conductive, insulated, and sealed measuring electrode, serving as a signal electrode, is arranged within the sensor housing (sloshing damping and splash protection device) or within the shielding electrode. Particularly preferably, the shielding electrode can be constructed as a tube with a circular or polygonal cross-section. As a capacitive sensor, the level sensor measures the capacitance between the shielding electrode and the measuring electrode. Therefore, continuous level measurement can be achieved over the widest possible measurement range.

[0026] The shielding electrode and the sloshing damping and splash guard preferably have an opening at or below the lower end of the measuring range to establish a flow connection between the volume inside the shielding electrode (or sloshing damping and splash guard) and the volume outside the shielding electrode (or sloshing damping and splash guard). Preferably, the opening can extend radially through the shielding electrode or sloshing damping and splash guard. This allows for a connected pipe configuration necessary for measuring the liquid level, enabling liquid exchange between corresponding water volumes inside and outside the shielding electrode or sloshing damping and splash guard. In other words, water from the water separator intrudes below through the opening into the sensor housing, sloshing damping and splash guard, or shielding electrode, resulting in a liquid level in the level sensor that can be measured along with the signal electrode due to the measurement scheme.

[0027] Particularly preferably, the measuring axis of the level sensor extends vertically through the center of gravity of the liquid, extractable water in the water separator. This minimizes the interference of the water separator's tilt and / or tilt orientation on the level measurement. Furthermore, it minimizes the amplitude of waves on the water surface during sloshing motion and improves the accuracy of level measurement. Therefore, it allows for reliable and high-precision detection of the liquid level limits, preventing excessively high levels and overflow of the water separator towards the fuel cell stack. On the other hand, at low levels, accidental hydrogen escape through the outlet is prevented because the lower limit is also reliably identified. Thus, a minimum liquid level can be guaranteed.

[0028] A preferred configuration of the casing includes a carrier and a cover, which are connected to each other via an airtight interface. Here, airtight means that the escape of hydrogen is continuously suppressed until no safety-related defects occur.

[0029] The carrier essentially forms a bottom element that surrounds a volume in which a reservoir for temporarily holding liquid water is constructed. The carrier may, for example, have a generally rectangular cross-section, wherein the reservoir constructed therein may have a circular cross-section. Preferably, valves and additional components or parts of a water separator and / or fuel cell may be arranged on the carrier. The carrier can therefore also serve as a mechanical platform for securing additional components and for securing the water separator to the structural space of the vehicle. The carrier may be essentially an upwardly opening housing half having sidewalls and a bottom.

[0030] Corresponding to the carrier, the cover can be a downward-opening housing half. By fastening the cover to the carrier, an outwardly airtight internal space is created, in which the level sensor is arranged. Other components of the water separator can also be arranged on the cover. Preferably, the inlet and / or outlet are constructed on the cover.

[0031] According to a preferred embodiment, the carrier and the cap are each constructed as a single, integrally injection-molded plastic part. Therefore, these components can be manufactured cost-effectively in large quantities. Preferably, the required sealing interface between the carrier and the cap is located in a horizontal plane. This horizontal interface between the carrier and the cap can be constructed such that it does not conflict with the structural space of a similarly horizontal interface of a level sensor disposed deeper at the bottom of the carrier, and is therefore suitable for implementing the level sensor even when the available structural space is small.

[0032] Preferably, the level sensor is arranged on the bottom of the horizontal structure of the carrier. This allows for a level sensor for continuously measuring the liquid level in a water separator in a space-saving manner.

[0033] A level sensor, positioned below the bottom of the carrier and having a vertical measuring axis, for example along the sensor housing of the level sensor, is suitable for generating a continuous measurement signal of the water level over a large measurement range. Thus, the water separator can be used across a variety of different vehicles on various platforms.

[0034] The level sensor is positioned at the bottom of the water separator carrier, both at the lower part and internally, using a robust, material-locking welding method to seal the interface between the carrier and the level sensor. This allows for optimal utilization of the available structural space within the water separator to maximize the volume of water that can be extracted. The flattened construction of the level sensor housing below the measurement path defined by the sensor cover also allows for the detection of low levels as a shut-off threshold for the discharge valve.

[0035] By centrally arranging the level sensor on the bottom and inside of the water separator, which has a measuring axis pointing vertically upward within the sensor housing, it is possible to make the best use of the available structural space in the horizontal direction and maximize the usable volume inside the water separator.

[0036] Preferably, the opening in the sloshing damping and splash guard is located at the bottom. Therefore, even at low liquid levels, the corresponding liquid level inside the level sensor can be maintained, allowing for the maximum possible measurement range. For example, one, two, three, four, or more circular or rectangular openings can be constructed in the wall of the sloshing damping and splash guard near the bottom. Furthermore, another opening can be constructed above the opening near the bottom in the sloshing damping and splash guard.

[0037] The sloshing motion of water and the resulting splashing can occur, for example, during acceleration, braking, or cornering. These sloshing motions or splashes can be damped or prevented by sloshing damping and splash-proof devices. In particular, the centrally positioned measuring electrode can be protected from splashes. Therefore, the measurement accuracy and reliability of the level sensor can be improved.

[0038] Preferably, the level sensor is connected to the carrier via a surrounding welded interface. By preferably welding the level sensor internally into the carrier of the water separator, there is no direct external interface between the level sensor and the surrounding environment. This results in a significant reduction in the requirements for hydrogen sealing at the welded interface. Therefore, no safety-related features are involved, thereby enabling reduced inspection workload and lower process costs.

[0039] According to a preferred configuration, the water separator includes an electrical interface, particularly an external plug interface, for electrically connecting a level sensor to an external device. This interface comprises a metallic, injection-molded, stamped mesh integrated into a carrier. Particularly preferably, the electrical interface may have a space-saving impact contact. This configuration allows for additional freedom, such as arranging the electrical interface to the vehicle's wiring harness in a space-efficient and / or remote location from the sensor. Additionally, further electrical interfaces, such as those for the heating element to prevent water from freezing in the water separator or valve, can be integrated into a common stamped mesh and a common electrical interface. This results in further cost and space savings. For example, a common 5-pin plug for the heating element and level sensor requires less installation space than a 3-pin plug for the level sensor and a separate 2-pin plug for the heating element. In particular, the measurement signal can be read from the level sensor via the electrical interface. In addition, the voltage or potential required for measuring and operating the level sensor can be applied to the measuring electrode and / or shielding electrode via an electrical interface.

[0040] According to a preferred embodiment, the water separator is configured to open a discharge valve when a level sensor detects a first liquid level (first limit value), and close the discharge valve when the level sensor detects a second liquid level (second limit value). Here, the first liquid level is higher than the second liquid level. The first limit value corresponds to the maximum liquid level that should not be exceeded. The limit values ​​can be selected or set according to requirements and applications to cause the discharge valve to open and close. The entire measurement range of the level sensor can also be used for other regulation strategies without incurring additional costs or multiple different variations, and without requiring multiple sensors to detect different limits. Preferably, the control signals for opening or closing the discharge valve and / or vent valve can be generated and output by the water separator's internal electronics or via an external control device. Attached Figure Description

[0041] The invention will now be described in more detail with reference to embodiments illustrated in the schematic drawings. Herein lies: Figure 1 A schematic diagram of the anode path of a fuel cell is shown; Figure 2 A perspective view of a water separator according to one embodiment is shown; Figure 3 Show Figure 2 A cross-sectional view of the carrier of the water separator, which is equipped with a liquid level sensor; Figure 4 Show Figure 3 A top view of the carrier in the image.

[0042] The accompanying drawings are intended to provide a further understanding of embodiments of the invention. The drawings illustrate embodiments and serve to explain the schemes and concepts of the invention within the context of the description. Referring to the drawings, many other embodiments and advantages, among those mentioned, become apparent. Elements in the drawings are not necessarily shown to scale.

[0043] In the accompanying drawings, unless otherwise specified, identical, functional, and functional elements, features, and parts are given the same reference numerals. Detailed Implementation

[0044] Figure 1 A schematic diagram of the anode path of fuel cell 1 in a vehicle is shown. In the anode path, hydrogen gas carried in a high-pressure container in the vehicle is reduced to medium pressure via pressure reducer 3 and supplied to the fuel cell stack 2 at the desired pressure and amount via proportional valve 4, so as to generate current there for driving the vehicle. The anode path shown also includes a shut-off valve 5 for cutting off the hydrogen supply and sensors 6 for measuring pressure and temperature.

[0045] A filter 7 for trapping impurities is also arranged before the inlet of fuel cell stack 2. Exhaust gas is directed through the outlet of fuel cell stack 2 to a water separator 10 equipped with a level sensor 30. The water separator 10 further includes a discharge valve 12 and an exhaust valve 13, wherein a filter 11 is connected upstream of the discharge valve 12. Dry and pure hydrogen gas can be returned to the anode path through outlet 16. An additional pressure sensor may be arranged at outlet 16.

[0046] Figure 2 A perspective view of a water separator 10 according to one embodiment is shown. The water separator 10 includes a housing having an inlet 15 and an outlet 16, the inlet for supplying exhaust gas from the outlet of the fuel cell stack 2 of the fuel cell 1, and the outlet for guiding hydrogen gas back to the fuel cell 1.

[0047] Here, the housing includes a carrier 22 and a cover 20, the carrier being essentially an upward-opening half of the housing and the cover being essentially a downward-opening half. The carrier 22 and the cover 20 are connected to each other via an airtight interface 21. At the four corners, the cover 20 and the carrier 22 are screwed together, see also [reference needed]. Figure 3 .

[0048] The carrier 22 is externally provided with an electrically controllable discharge valve 12 for discharging liquid water and an electrically controllable exhaust valve 13 for discharging gas. In addition, the carrier includes an electrical interface 17 for establishing an electrical connection between a liquid level sensor 30 disposed in the housing and an external control device (not shown).

[0049] In addition, a heating device 18 is arranged on the carrier 22 to prevent valves 12 and 13 from freezing. The heating device 18 can be connected to an external control device or voltage source (not shown) via an electrical interface 19. An outlet 14 is arranged on the discharge valve 13, through which water can flow out of the water separator 10 when the discharge valve 13 is open.

[0050] The carrier 22 and the cover 20 are each constructed as a one-piece plastic injection molded part, which can be manufactured in large quantities at a cost-effective pace.

[0051] Figure 3 Show Figure 2 A cross-sectional view of the carrier 22 of the water separator 10, which includes a level sensor 30. Approximately centered on the bottom of the carrier 22, the level sensor 30 is arranged within a housing for capacitively measuring the level of liquid water in the water separator 10. The measuring axis 35 of the level sensor 30 is vertically arranged, and the level sensor 30 is configured to output a measurement signal proportional to the liquid level. The measurement signal may, for example, be a voltage signal between 0 and 5V or 0 and 24V. In particular, the measuring axis 35 of the level sensor 30 extends through, or at least very close to, the center of mass of the liquid, extractable water in the water separator 10.

[0052] exist Figure 3 The exemplary water level is indicated by W. M represents the measurement range of the level sensor 30. S represents the current water level. The level sensor 30 therefore outputs a measurement signal corresponding to the water level S via interface 17.

[0053] exist Figure 3 The liquid level sensor 30 shown includes a capacitive cylindrical capacitor with a so-called sensor housing that serves as a sloshing damping and splash protection device 31. A conductive shielding electrode 33 is integrated into the substantially tubular sloshing damping and splash protection device 31. A conductive measuring electrode 32 is centrally and concentrically arranged within the sloshing damping and splash protection device 31. The shielding electrode 33 serves as a grounding electrode for capacitive measurements and also as a shield against external capacitive interference. Here, the liquid level sensor 30 is centrally positioned at the bottom of the horizontal structure of the carrier 22.

[0054] The sloshing damping and splash prevention device 31, arranged concentrically around the measuring electrode 32, reduces the surface area of ​​water in the level sensor 30. This significantly reduces the formation of waves and / or splashes on the water surface caused by the movement or acceleration of the water separator 10, and also significantly reduces bubble formation caused by air flowing into the water.

[0055] The shielding electrode 33 and the sloshing damping and splash prevention device 31, with the latter having a window 34, establish a flow connection between the volumes inside and outside the sloshing damping and splash prevention device 31 through an opening in the window. The window opening additionally serves for sloshing damping and stabilizing the liquid level within the sensor housing 31. This also involves reducing or shielding the formation of small bubbles in the water inside the sloshing damping and splash prevention device 31 compared to the outside. Small bubble formation in the water is caused by the volumetric flow of gas flowing into the water separator 10. The window or opening 34 establishes a flow connection between the volumes inside and outside the sloshing damping and splash prevention device 31. The opening 34 is constructed on the lower end of the sloshing damping and splash prevention device 31. Figure 3 The cross-sectional view shows two pairs of opposing openings 34 in the sway damping and splash guard 31, each opening being constructed on the lower end of the sway damping and splash guard 31. Here, the height of the openings 34 can extend to approximately one-third or approximately half the height of the sway damping and splash guard 31.

[0056] The level sensor 30 is connected to the carrier 22 via a surrounding welded interface 29. This allows a secure, airtight seal to be established between the level sensor 30 and the carrier 22.

[0057] The level sensor 30 includes an electrical interface 17 externally configured as a plug-in connection on the carrier 22 (see...). Figure 2 The electrical interface 17 is used to electrically connect the level sensor 30 to an external device (not shown), such as for reading measured values ​​and / or for controlling the water separator 10. The electrical interface 17 connects to a metal, injection-molded, stamped mesh 37 integrated into the carrier 22. The stamped mesh 37 serves as the wiring between the three electrical contacts 36 of the level sensor 30 and the external electrical interface 17 leading to the cable harness connector.

[0058] Figure 4 A top view of the opening of the carrier 22 is shown. The rectangular cross-section of the carrier 22 is visible here, wherein the volume for containing water has a substantially circular cross-section. At each of the four corners of the carrier 22, a screw joint 23 for tightening the carrier 22 to the cover 20 is visible. During tightening, a seal is used at the interface 21 between the carrier 22 and the cover 20 to seal the housing.

[0059] exist Figure 4 The top view shows three electrical contacts 36 of the liquid level sensor 30, which are connected to the electrical interface 17 via a stamped mesh 37.

[0060] An exhaust passage 25 is arranged on the upper edge of the carrier 22, through which unwanted gases, such as nitrogen, can be discharged from the water separator 10. An exhaust valve 13 is used for this purpose.

[0061] Reference numeral 24 indicates a discharge passage for discharging water from the water separator 10 via discharge valve 12. Discharge passage 24 is located near the bottom of the carrier 22. Filter 11 is connected upstream of discharge valve 12 to prevent contaminants from entering discharge valve 12.

[0062] The water separator 10 is configured to open the discharge valve 12 when the level sensor 30 detects a first liquid level as a first upper limit value, and to close the discharge valve 12 when the level sensor 30 detects a second liquid level as a second lower limit value. The first liquid level (first limit value) is higher than the second liquid level (second limit value). Therefore, water overflow from the water separator 10 into the fuel cell stack 2 can be reliably prevented. Furthermore, accidental leakage of hydrogen from the water separator at low liquid levels can be prevented.

[0063] The present invention, as described in the accompanying drawings, integrates a sloshing damping and splash prevention device 31 into the level sensor 30 of the water separator 10 of the fuel cell. The level sensor 30 is mounted in the water separator 10 as a capacitive cylindrical or polygonal capacitor. Therefore, the level sensor 30 has integrated self-protection against excessive sloshing waves, small bubble formation, or splashes onto the central measuring electrode 32 of the level sensor 30. The sloshing damping and splash prevention device 31 according to the invention fully utilizes the geometry of the capacitive level sensor 30, which is essentially a tube with a circular or polygonal base surface.

[0064] During sloshing events with different manifestations of wave amplitude, compensation is made for the liquid level between the liquid level height of the medium outside the liquid level sensor 30 (here, water) and the liquid level height of the medium inside the liquid level sensor 30, regardless of the medium filling height within the measurement range set in the liquid level sensor 30.

[0065] Furthermore, level compensation can be performed independently of the designed tilt orientation of the water separator or level sensor 30 relative to the horizontal plane. Typically, in the water separator of a fuel cell, a tilt requirement of ±18° is known.

[0066] The water separator 10 according to the invention ensures accurate liquid level measurement regardless of the orientation of the water separator or liquid level sensor relative to the horizontal plane, which is between 0° and 360°. Since the liquid level is measured within the liquid level sensor 30, the internal liquid level must correspond to the external liquid level outside the liquid level sensor 30 and the liquid level within the water separator 10. For this purpose, the liquid level sensor has multiple openings 34 in the sloshing damping and splash prevention device 31 and in the external shielding electrode 33.

[0067] Furthermore, complete evacuation of the level sensor 30 can be ensured when the connection between the media surface inside and outside the level sensor 30 is interrupted. In this embodiment, this is achieved by arranging four pairs of openings 34, each opposite to the other, on the lower end of the sloshing damping and splash guard 31. This also ensures the refillability of the level sensor 30, especially after evacuation in an inclined orientation, and in the case of a subsequent freeze-start with refilling when residual water that cannot be extracted freezes in the water separator 10 and frozen media (ice) still exists in the lower portion of the level sensor 30. In the case of multiple, especially four, openings 34 evenly distributed around the periphery of the sloshing damping and splash guard 31, at least one opening 34 advantageously remains ice-free at all times.

[0068] In the current configuration, the external shielding electrode 33 serves not only as a grounding electrode but also additionally as an electrical shield to prevent capacitive interference from the measuring electrode 32, thereby reducing susceptibility to interference and improving measurement accuracy. In the current configuration, the sway damping and splash protection device 31 can be implemented, for example, as a plastic injection-molded part with an embedded (integrated) metal shielding electrode 33.

[0069] The water separator 10 according to the invention can operate in different orientations between 0° and 360° in terms of tilt relative to the horizontal plane, thereby maximizing the spatial distance between the power supply of the level sensor and the power supply of other components of the water separator 10 (e.g., the heating unit 18, the discharge valve 12, and the exhaust valve 13) without accepting any other functional loss of the level sensor 30.

[0070] By optimizing the number, width, shape, and height of the cross-sections of the openings 34 in the lower region of the sloshing damping and splash prevention device 31, as well as the radius of the openings 34, the filling and emptying of the level sensor 30 can be optimized to maximize the usable measurement range of the level sensor 30, which possesses good accuracy and a linear sensor characteristic curve. Specifically, multiple openings 34 with widths of, for example, 4 mm and heights of, for example, 16.5 mm can be constructed in the lower region of the level sensor 30.

[0071] In this invention, multiple features are designated with the names "first" and "second". These names are used only to distinguish the features in terms of understanding. In particular, no spatial or functional arrangement or priority should be derived from them.

[0072] If the list of alternatives in this application is named "or", it should be understood that not only should the listed alternatives be understood individually, but also, if meaningful, combinations of multiple or all of the listed alternatives.

Claims

1. A water separator (10) for a fuel cell (1) in a vehicle, the water separator comprising: The housing has an inlet (15) and an outlet (16), the inlet being used to supply exhaust gas from the stack outlet of the fuel cell (1), and the outlet being used to return hydrogen gas to the fuel cell (1). Discharge valve (12), the discharge valve being used to discharge liquid water; Exhaust valve (13), the exhaust valve being used to discharge gas; and A liquid level sensor (30) is arranged in the housing for capacitive liquid level measurement of liquid water in the water separator (10), wherein the liquid level sensor (30) is configured to output a measurement signal proportional to the liquid level, and the liquid level sensor (30) has a sloshing damping and splash protection device (31).

2. The water separator (10) according to claim 1, wherein: The liquid level sensor (30) has a capacitive cylindrical capacitor or a capacitive polygonal capacitor.

3. The water separator (10) according to claim 2, wherein: The conductive shielding electrode (33) of the liquid level sensor (30) is integrated into the sloshing damping and splash prevention device (31), and the conductive measuring electrode (32) is arranged in the sloshing damping and splash prevention device (31).

4. The water separator (10) according to any one of the preceding claims, wherein: The sway damping and splash guard (31) has at least one opening (34) to establish a flow connection between the volume inside the sway damping and splash guard (31) and the volume outside the sway damping and splash guard (31).

5. The water separator (10) according to any one of the preceding claims, wherein: The housing includes a carrier (22) and a cover (20), which are connected to each other via an airtight interface (21).

6. The water separator (10) according to claim 4 or 5, wherein: The opening (34) is arranged in such a way that it is distributed around the periphery of the sway damping and splash guard (31).

7. The water separator (10) according to claim 6, wherein: The liquid level sensor (30) is connected to the carrier (22) via a surrounding welded interface (29).

8. The water separator (10) according to any one of claims 4 to 7, wherein: The opening (34) is constructed on the bottom of the liquid level sensor (30) and on the lower end of the sloshing damping and splash prevention device (31).

9. The water separator (10) according to any one of claims 5 to 8, wherein, The carrier (22) and the cover (21) are respectively constructed as one-piece plastic injection molded parts.

10. The water separator (10) according to any one of claims 5 to 9, wherein the water separator further comprises: Electrical interface (17), the electrical interface being used to electrically connect the liquid level sensor (30) to an external device, wherein, The electrical interface (17) is connected to a metal, injection-molded stamped mesh (37), which is integrated into the carrier (22).

11. The water separator (10) according to any one of the preceding claims, wherein, The water separator (10) is configured to: When the level sensor (30) detects the first liquid level, the discharge valve (12) is opened; and When the liquid level sensor (30) detects the second liquid level, the discharge valve (12) is closed, wherein, The first liquid level is higher than the second liquid level.

12. The water separator (10) according to any one of the preceding claims, wherein, The sway damping and splash protection device (31) is tubular.

13. A method for operating a water separator (10) for a fuel cell (1) in a vehicle, the method comprising: The liquid level of the water in the water separator (10) is measured along the measuring axis; Generate a measurement signal proportional to the liquid level; When the measured signal is equal to or greater than the first limit value, the discharge valve (12) for discharging liquid water is opened; and When the measured signal is equal to or less than the second limit value, the discharge valve (12) is closed, wherein the first limit value is greater than the second limit value.

14. The method for operating the water separator (10) according to claim 13, in, The measurement axis is vertical or inclined relative to a vertical line.

Images