AT526141A1 - Fuel cell system, vehicle with a fuel cell system and method for draining product water from a fuel cell stack of the fuel cell system - Google Patents

Abstract

The present invention relates to a fuel cell system (50), wherein the fuel cell system (50) comprises at least one fuel cell stack (10), which has inlet openings (12), outlet openings (14) and flow sections (12) that fluidly connect the inlet openings (12) to the outlet openings (14). 16), wherein the fuel cell system (50) comprises at least one drain system (30), wherein the drain system (30) has a drain channel (32) and at least one drain valve (34) arranged in the drain channel (32) for draining product water (1) from which has at least one fuel cell stack (10), wherein the at least one drain channel (32) leads from at least one drain channel flow section (17) of the flow sections (16) to the outside of the fuel cell stack (10), and wherein the fuel cell system (50) further has a Control device (40) for opening the at least one drain valve (34).

Description

Fuel cell system, vehicle with a fuel cell system and method for draining product water from a fuel cell stack of the

fuel cell system

The present invention relates to a fuel cell system, a vehicle with a fuel cell system and a method for discharging product water

from a fuel cell stack of a fuel cell system.

Fuel cell systems are known from the prior art in which the anode system (supplied with fuel, in particular hydrogen) is a closed circuit in which excess fuel is recirculated. In this closed circuit, liquid product water is separated in a water separator outside the fuel cell stack and periodically removed. The cathode system (supplied with oxidant, especially air) is normally open. Air from the environment is supplied to the stack, and the exhaust air with it

The product water (gaseous and liquid) is released into the environment.

In particular, polymer electrolyte membrane (PEM) fuel cell stacks and fuel cell systems containing them are now mostly used in motor vehicles or stationary applications where high inclination angles (in particular

>> 8 °) are not part of normal operation and only occur for a short time.

In other applications, such as off-road vehicles, construction machinery, tractors, airplanes, ships, snow groomers, snowmobiles, etc., high inclinations up to e.g. B. 30 ° (57.7%) to normal operation and can occur over a longer period of time (several minutes to hours). Here, product water can accumulate in the fuel cell stack because liquid water is only up to a certain inclination from the media gas streams against gravity or gravitational force

can be transported away.

Typically, a PEM fuel cell stack can only operate at a specific tilt angle for a specific time. The maximum slope and the possible time at that slope depend on the type of slope. The most critical finding was a slope where the inlet/exhaust openings

directed upwards (against the force of gravity). This can lead to one

insufficient removal of the product water (generated in the fuel cell stack)

sers, especially in the cell collectors, followed by an oxidant

/Fuel shortage. Oxidant deficiency can lead to a loss of performance

lead and render the fuel cell stack inoperable. Lack of fuel

can also lead to damage to the fuel cell stack.

It is the object of the present invention to at least partially eliminate the disadvantages described above. In particular, it is the object of the present invention to ensure stable, reliable and safe operation of fuel cell stacks of fuel cell systems even with large inclinations during their use

To enable operation for a long and, if possible, unlimited time.

The above object is achieved by a fuel cell system with the features of claim 1, a vehicle with the features of claim 15 and a method with the features of claim 16. Further features and details of the invention emerge from the subclaims, the description and the drawings . Features and details that are described in connection with the fuel cell system according to the invention naturally also apply in connection with the vehicle according to the invention and the method according to the invention and vice versa, so that reference is or will always be made to each other with regard to the disclosure of the individual aspects of the invention

can.

According to the invention, a fuel cell system is provided, wherein the fuel cell system comprises at least one fuel cell stack, which has inlet openings, outlet openings and flow sections that fluidly connect the inlet openings to the outlet openings, in particular flow channels in the individual fuel cells of the fuel cell stack. The fuel cell system further comprises at least one drain system, wherein the drain system has a drain channel and at least one drain valve arranged in the drain channel for draining product water from the at least one fuel cell stack, wherein the drain channel flows from at least one drain channel flow section of the flow sections to outside the fuel cell stack.

pels leads, and the fuel cell system also has a control device for

In contrast to the prior art, according to the invention a solution is provided which enables accumulated product water to be drained away directly from the fuel cell stack of the fuel cell system, in particular a vehicle. Compared to known fuel cell systems, in which an additional drainage of the product water directly from the stack itself in the anode system is not provided and an additional drainage system in the cathode system is not required, as follows from the introduction above, the fuel cell system according to the invention provides stable, reliable and safe operation of the fuel cell stack is achieved for an unlimited period of time, even at large inclinations. The drain channel leads from the drain channel flow section to the outside of the fuel cell stack, i.e. out of the fuel cell stack. Product water that accumulates in the drain channel flow section channel over a long period of operation at high inclinations, which cannot be transported away solely by the media gas streams against gravity, in particular to a water separator outside the fuel cell stack, can now be removed in a simple manner by opening the drain valve using the Control device must be drained

the.

The fuel cell system can be used in particular in a vehicle. Such a vehicle can be any land, water and/or aircraft. For many land vehicles, i.e. on-road vehicle applications, it can be assumed that high inclinations only occur for a limited time (e.g. only a few minutes), followed by a neutral position or even a downward inclination in the direction of gravity directional outlet openings. Therefore, product water in such vehicles may not accumulate to the extent that it becomes critical to vehicle operation. This assumption does not apply to other applications, so that these embodiments of vehicles are particularly advantageous. These can in particular be off-road vehicles, construction machinery, tractors, airplanes, ships, snow groomers and/or snowmobiles. Alternatively, it is also possible to use the fuel cell system according to the invention in devices other than a vehicle, with the embodiments made here corresponding to a vehicle also being applicable

other devices may apply, as far as technically feasible.

be technically connected.

The drain channel flow section is the at least one flow section in which the drain channel runs or from which the drain channel extends outside the fuel cell stack, that is to say towards an environment outside the fuel cell stack. The drain channel can extend into an environment within the fuel cell system or the vehicle outside the fuel cell stack or completely outside the vehicle. In the first variant, the product water can be collected and recirculated or used for other purposes. In the second variant, it can be removed from the vehicle. Of course, it is possible for the drain channel to run in or from more than one flow section, so that there are several drain channel flow sections. It is also possible for several drain channels to be provided in different flow sections, which can be merged or not, so that separate drain valves can also be provided for each of these drain channels.

channels can be provided.

A control device already provided in the fuel cell system can be used as a control device for opening the at least one drain valve,

which also takes on other control tasks there in order to reduce the costs

to keep the fuel cell system low. The control device can accordingly

be connected to the at least one drain valve in terms of control technology, so

that this can be controlled to open and also close. Possible

but is also a control system explicitly provided for the at least one drain valve

device to be provided.

Advantageously, the drain channel can be designed to passively drain product water by means of gravitational force acting on the product water. For this purpose, an installation position and/or at least partial extension direction of the drain channel relative to the vehicle, in particular relative to a normal position intended for operation, can be provided, which ensures that the product water is inclined when the vehicle is inclined, in particular relative to the normal position, and therefore at least one fuel cell stack is inclined can flow away through the gravitational force through the drain channel when the drain valve is open. The inlet and outlet openings can be directed counter to the direction of gravity. In particular, it can be provided that the product water can flow away exclusively by means of gravitational force when the drain valve is open. This means that no active influence on the operation of the fuel cell system (with the exception of opening the drain valve) is necessary, such as active flushing or active pressure control, i.e. a change in the media flow within the fuel cell stack in order to prevent the product water from flowing away

to enable.

It is also advantageous if the fuel cell system also has a water separator outside of the at least one fuel cell stack. This water separator is provided in addition to the drain system of the fuel cell system and in particular is operated separately from it. This water separator is typically provided in fuel cell systems for separating product water from the fuel cell stack, although the product water must be removed from the fuel cell stack by means of the media gas streams. The water separator can in turn have one or more valves. As explained at the beginning, this is not always entirely possible at large angles of inclination, so that the additional drainage system ensures that the water is reliably drained away from the fuel cell stack independently of the water separator.

such situations. The drain channel of the drain system can

in turn lead to the water separator or separated from it by fluid technology.

be separate. It is also possible to use the drain valve or another valve between the

The drain channel and the water separator must be provided for optional product water

to be fed from the drain channel to the water separator or discharged in another way.

ren.

It is also advantageous if the drain channel runs through an insulator plate of the at least one fuel cell stack. Insulator plates in fuel cell stacks are electrically non-conductive and isolate hardware components of the fuel cell stack from live parts of the fuel cell stack. The individual fuel cells of the fuel cell stack can be braced against one another by means of the load plates. They can also represent the mechanical connection of the fuel cell stack to the fuel cell system or the vehicle. The integration of the drain channel into an insulator plate enables an optimized integration of the drain channel in terms of installation space, so that previous designs of fuel cell stacks do not have to be laboriously modified and the fuel cell stack does not have to be dimensioned larger than before. It was found that the insulator plate and the load plate are not, or at best only insignificantly, affected by the additional drain channel in terms of functionality and structure. The drain channel can be, for example, as

a hole must be made in the insulator plate.

It is also advantageous if a reservoir for collecting product water is arranged in the drain channel. This reservoir is formed outside the drain channel flow section and is characterized by the fact that it can store a predefined amount of product water before the product water can drain out when the drain valve is opened. As a result, a certain amount of product water can be removed from the drain channel flow section before the drain valve is opened in order to prevent impairment and possible damage to the fuel cell stack. In addition, backflow of the product water can be prevented or reduced if a different inclination occurs, especially in the opposite direction (for example if after a long period of time).

Driving uphill with the vehicle is followed by a downhill journey).

71729

through the reservoir.

Advantageously, the at least one drain valve is arranged outside the fuel cell stack. Nevertheless, it is advantageously located close to the fuel cell stack. In this way, the costs of the drain system can be kept low, since an alternative possible integration of the drain valve into the fuel cell stack, for example the insulator plate, is very costly and requires a lot of installation space.

would be difficult to accomplish.

Preferably, the at least one fuel cell stack is also arranged horizontally oriented in a vehicle. Such a horizontal fuel cell stack orientation can e.g. B. may be necessary due to space restrictions. For example, it may happen that a fuel cell stack in a vertical orientation or in a so-called "pancake" orientation (fuel cells are stacked in the stack in the manner of a pancake from bottom to top in a vertical direction) with appropriate power cannot be placed in an engine compartment of a passenger car as a possible embodiment of the vehicle. Here, the accumulation of product water when the vehicle is tilted is a particularly common problem that is therefore eliminated or at least reduced in a vehicle according to the invention

can be.

It is also advantageous if the control device is set up to receive a measured value from a measuring device which is indicative of an inclination of the vehicle and/or the fuel cell stack relative to a horizontal, to compare the measured value with a predefined comparison measured value and to use the at least one drain valve depending on a result of the comparison. This has the advantage that the drain valve only opens as far as is necessary

If product water accumulates to a sufficient extent, it is opened, which is caused by the

Sera accumulation has been found to exist.

It is particularly advantageous if the fuel cell system and/or the vehicle has an inclination measuring device for measuring an inclination angle of the vehicle and/or the at least one fuel cell stack relative to a horizontal and the control device is set up to open the at least one drain valve when the measured inclination angle exceeds a predefined angle of inclination. This type of measuring device allows a direct measurement of the inclination of the vehicle and thus of the fuel cell stack. Included

The inclination angles of the vehicle and fuel cell stack nominally do not have to

agree with each other, since the fuel cell stack itself with its installation

Position in the vehicle can be inclined relative to the vehicle. The installation position

However, it is known and fixed, so that a measured angle of inclination from the vehicle

can be transferred to the angle of inclination of the fuel cell stack.

Advantageously, it is provided that the at least one control device is set up to open the at least one drain valve when the measured angle of inclination exceeds the predefined minimum value for a predefined minimum duration. Thus, by suitable predefinition of a minimum duration, in particular at least in the range of minutes or hours, it can be prevented that the drain valve is opened for every short period of time in which no or only little product water has accumulated in the drain channel flow section, whereby only media gas streams would be drained. The minimum time required determines how long the predefined angle of inclination must be exceeded in order to open the drain valve so that (sufficient) product water has actually accumulated and can be drained off.

it can and must.

It is also particularly advantageous, additionally or alternatively, if the fuel cell system has a cell voltage measuring device for measuring a cell voltage of the at least one fuel cell stack and the control device is set up to open the at least one drain valve when the measured cell voltage falls below a predefined cell voltage. Using the cell voltage measurement, a malfunction in the operation of the fuel cell can be detected if the cell voltage is correspondingly low. This can be considered indicative of an accumulation of product water, so that the drain valve is then activated to drain the accumulated in the drain channel flow section

Product water can be opened.

It is advantageous if the at least one control device is set up to open the at least one drain valve when the measured cell voltage falls below the predefined cell voltage for a predefined minimum duration. Thus, by appropriately pre-defining a minimum duration, in particular at least in the minute or hour range, it can be prevented that, for every short period of time,

in which there is still little or no product water in the drain channel

flow section has accumulated, the drain valve has already opened,

whereby only media gas streams would be vented. So it's about the emergency

A flexible minimum duration is specified for how long the predefined cell voltage is maintained.

must be taken to open the drain valve so that it actually (or

sufficient) product water has accumulated, which can be drained and

MUST.

Finally, alternatively or additionally, it can advantageously be provided that the control device is set up to open and close the at least one drain valve at predefined time intervals. This is a particularly simple way of indicatively determining product water accumulation in the drain channel flow section, although this can be less precise than the inclination angle measurement or the cell voltage measurement, which are, however, somewhat more complex. The time intervals can be predefined, for example, depending on the typical operation and/or empirical values. The time intervals can advantageously be measured by a time interval measuring device. When the time intervals then expire, the drain valve can be activated by the control

device must be opened.

Finally, it can advantageously be provided that the control device is set up to close the drain valve as a function of a media pressure in the at least one drain channel flow gas section. In particular, the media pressure in the at least one outlet channel flow gas section can be monitored, in particular by a corresponding monitoring device, in particular a pressure measuring device, and, in particular by the control device, continuously compared with a setpoint or a setpoint range. If the measured or monitored media pressure falls below the setpoint or is outside the setpoint range, it can be concluded that the medium in the outlet channel flow gas section is being drained from the outlet channel due to a media pressure drop. At this point in time, the product water has already been drained and the drain valve should be closed as quickly as possible to prevent more medium from being drained, which is required for the reaction in the fuel cell stack. Closing can therefore take place precisely in time due to the dependency on the media pressure. Furthermore, not only can

the setpoint of the media pressure can be monitored, but also by a

Monitoring the pressure gradient can determine a drop in pressure.

This also makes it possible to conclude that the product water already

drained and the drain valve can be closed.

Also the subject of the present invention is a vehicle with an inventive

proper fuel cell system.

A vehicle according to the invention thus brings with it the same advantages as explained in detail with reference to the fuel cell system according to the invention

have been.

The present invention also relates to a method for draining product water from at least one fuel cell stack of a fuel cell system of a vehicle according to the invention, the method having the following

has the steps:

— Measuring a measurement value that is indicative of an inclination of the vehicle

and/or the fuel cell stack is relative to a horizontal,

— comparing the measured value with a predefined comparison measured value,

and

— Opening the at least one drain valve to drain the product water

depending on a result of the comparison.

A method according to the invention therefore brings with it the same advantages as have been explained in detail with reference to the fuel cell system according to the invention. The fuel cell system, in particular the vehicle, can

be set up in particular to carry out the method according to the invention.

As explained above, the method can include, in particular in the measuring step, measuring an angle of inclination of the vehicle and/or the at least one fuel cell stack relative to the horizontal, measuring a cell voltage of the at least one fuel cell stack and/or measuring a time interval. Finally, the method can be used in particular in the public

step include opening the at least one drain valve

to understand the predefined cell voltage and/or the predefined time interval.

Further advantages, features and details of the invention emerge from the following description, in which reference is made to the drawings.

Examples of leadership are described in detail. It shows schematically:

1 is a frontal view of a fuel cell stack,

2 is a side view of the fuel cell stack from FIG. 1,

3 is a top view of the fuel cell stack from FIGS. 1 and 2,

4 shows a cross-sectional view through a vehicle according to an embodiment.

Example of the invention with the fuel cell stack from one of FIGS. 7 to 12,

Fig. 5 side views of the fuel cell stack of Fig. 4 at different

inclinations relative to a horizontal,

Fig. 6 top views of the fuel cell stack of Fig. 4 at different

chen inclinations relative to a horizontal,

7 shows a side view of a fuel cell stack according to an embodiment.

exemplary embodiment of the invention, FIG. 8 is a top view of the fuel cell stack from FIG. 7,

Fig. 9 is a detailed and cross-sectional view of the fuel cell stack

7 and 8 according to a first exemplary embodiment of the invention,

Fig. 10 is a detailed and cross-sectional view of the fuel cell stack

7 and 8 according to a second embodiment of the invention,

7 and 8 according to a third exemplary embodiment of the invention,

Fig. 12 is a detailed and cross-sectional view of the fuel cell stack

7 and 8 according to a fourth exemplary embodiment of the invention,

13 shows a schematic view of a fuel cell stack in a horizontal

zontal alignment,

14 shows a schematic view of a fuel cell stack in a vertical

cal orientation,

15 shows a schematic view of a fuel cell stack in a wider

ren vertical orientation, and

16 shows a schematic view of a method according to an embodiment.

approximate example of the invention.

Identical or functionally identical elements are included in Figures 1 to 16

denoted by the same reference numeral.

Figure 1 shows a fuel cell stack 10 in a top view. The fuel cell stack 10 includes a plurality of inlet openings 12 on one side or edge of its top side, visible here, and a plurality of outlet openings 14 on the opposite side or edge of its top side. The inlet openings 12 and outlet openings 14 serve to transport the media used by the fuel cell stack 10 during its operation, which here are, for example, Fx for fuel, Ox for oxidant or air and Cx for coolant . Coolant) and are arranged in a purely exemplary arrangement.

shown, which can also be different.

Figure 2 shows the fuel cell stack 10 in a side view, to be precise the narrow side of the fuel cell stack 10 (viewed from the left of the inlet openings 12 in Figure 1). Within the fuel cell stack 10 there is, in a known manner, a row of fuel cells 15 or, in other words, a package of fuel cells arranged in series with one another. Run within this

Flow sections 16, in particular in the form of collecting channels, from the

Inlet openings 12 and outlet openings 14 through the individual cells. The A-

outlet collecting channels are connected to the outlet collecting channels via the flow channels

connected in the individual cells (i.e. Fx inlet opening to Fx outlet opening,

Ox inlet port to Ox outlet port and Cx inlet port to Cx outlet port

tion).

The fuel cell row 15 is held together on its end sides by load plates 20, in particular pressed together with a clamping system. There are also insulator plates between the load plates 20 and the fuel cell row 15.

th 18 arranged.

Figure 3 shows the fuel cell stack 10 in a side view of the wide side of the fuel cell stack 10 (viewed from below on the long side of the fuel cell stack 10 in Figure 1). Here it can be seen that the fuel cell stack 10 also has a bus plate 22. By means of the bus plate 22, an electrical connection (not shown) of the fuel cell stack 10 is made possible in a known manner in order to dissipate the current generated by the fuel cell stack 10, for example for supplying it to an electric motor of the vehicle 60 shown in FIG.

4 shows an exemplary embodiment according to the invention of a vehicle 60 with a fuel cell system 50 comprising a fuel cell stack 10, as shown in FIGS. 7 to 12 and will be explained in more detail below (which will be explained in more detail later

The explained process system 30 of the fuel cell stack 10 is shown in the overview in FIG.

For the sake of clarity, not shown, but included).

In addition to the fuel cell stack 10, the fuel cell system 50 can of course include other peripherals, such as corresponding pumps, valves, recirculation fans, etc., but these are not shown for the sake of clarity. However, what is shown is a control device 40 and several measuring devices 42, 44, 46 (which are only shown purely schematically here), which will be discussed in more detail later, and only one of the measuring devices 42, 44, 46 can be provided. In addition, the fuel cell system 50 has a water separator 52 (which is also only shown here purely schematically), which is connected to the

Fuel cell stack 10 is fluidly coupled.

water 1 in a lower region of one of the flow sections 16.

5 shows different inclinations of a fuel cell stack 10, the inclination angle position of the fuel cell stack 10 of FIG. 4 being indicated using a hand signal, which, unlike the inclination angle position indicated using an OK sign (with a hook), is critical. At the critical inclination angle position, the inlet openings 12 and outlet openings 14 are oriented upwards and against the direction of gravitational force g. This ensures that, as shown in FIG. 4, product water 1 can accumulate in one or more of the flow sections 16, which is not removed by the media gas streams within the flow section 16 or the flow sections 16

can.

In contrast, FIG. 6 shows other inclination angle positions of an orientation or installation position of the fuel cell stack 10, which are comparatively uncritical. Angles of inclination & of the fuel cell stack 10 are not shown here running along the fuel cell stack 10 along the flow sections 16, but instead, inclinations across the flow sections 16 are shown. The inlet openings 12 and outlet openings 14 are not all upwards here

aligned against the direction of gravitational force g.

Finally, Figure 7 shows a fuel cell stack 10 as it can be used in the exemplary embodiment of the vehicle 60 according to the invention. As can be seen, a drain system 30 is additionally provided here, which is shown in more detail and in possible embodiment variants in FIGS. 9 to 12 and with reference

is explained thereon.

8 shows a top view of the fuel cell stack 10 of FIG. 7 and a section line AA along which the views of FIGS. 9 to 12 with respect to the diagram

running system 30 are shown.

designated.

In Fig. 9, the drain channel flow section 17 is the flow section 16 in which the fuel is transported. Alternatively, it can also be any other of the flow sections 16. Several flow sections 16 can also be provided as drain channel flow sections 17, so that several drain channels 32 can also be provided, by means of which product that accumulates in the flow sections 16 at a corresponding inclination.

water 1 can be drained.

The drain valve 34, which is shown here outside the fuel cell stack 10, is actuated by means of the previously mentioned control device 40, i.e. controlled for opening and closing. The control device 40 can receive a measured value from one or more of the measuring devices 42, 44, 46, which is indicative of an inclination of the fuel cell stack 10 relative to the horizontal H shown by way of example in FIG. Then the control device 40 can compare the measured value with a predefined comparison measured value and open the at least one drain valve 34 depending on a result of the comparison. It can be provided that the result of the comparison must exist for a predefined minimum period. The measuring devices 42, 44, 46 shown are, for example, an inclination angle measuring device 42

Cell voltage measuring device 44 and a time interval measuring device 46.

In the embodiment variant of FIG. 10, the drain channel 32, on the other hand, extends

only in the insulator plate 18. In addition, the drain channel 32 is different here than in

9 is not executed straight, but with a bend or change of direction.

The drain channel 32 thus has a direction transverse, in particular perpendicular, to the

Drain channel flow section 17.

In the embodiment variants of Figures 11 and 12, reservoirs 36 or, in other words, pockets are provided in the drain channel 32, which are formed here, for example, in the insulator plate 18. The reservoirs 36 enable product water 1 to be stored therein before the product water 1 is drained when the drain valve 34 is opened, as well as reduced backflow of product water 1 when the direction of inclination changes. In Fig. 11, the reservoir 36 is arranged between the drain channel 32. In Fig. 12, the reservoir 36 is shown directly adjoining the drain channel flow section 17, from which the drain channel extends

32 extends towards the surroundings of the fuel cell stack 10.

Figures 13 to 15 show different orientations of the fuel cell stack 10, as they can be used in the vehicle 60. The horizontal orientation shown in FIG. 13 is often used for reasons of installation space, particularly in passenger cars, which is particularly critical with regard to possible accumulations of product water. Here, problems with the drainage of the product water 1 can occur if the slope is steep. There is a risk of flooding, especially of the anode. A shortage of fuel and damage to the fuel cell stack are possible. Additional drainage of the product water 1 within the fuel cell stack 10, as proposed herein, can

prevent this.

14 (so-called pancake orientations) are less sensitive if the inlet and outlet openings 12, 14 are aligned downwards in accordance with the direction of gravitational force g, but the use of the drain system 30 can also be used here previously described, be useful. If the inlet and outlet openings 12, 14, as shown in Fig. 14, are directed downwards or in the direction of gravitational force g, this can happen in all directions at static inclinations of <30 ° compared to the horizontal H

However, product water 1 usually expires. If the inlet and

Exhaust openings 12, 14, as shown in Fig. 15, but upwards or opposite

the gravitational force direction g can occur in the fuel cell state

pel 10 product water 1 accumulate, so that the discharge of the product water 1 with-

by means of the drainage system 30, as proposed herein, very advantageous or for one

Operation is even absolutely necessary.

Finally, FIG. 16 shows the sequence of a method 100 according to an exemplary embodiment of the invention. In a first step 102 of the method 100, the aforementioned measured value is measured using one or more of the measuring devices 42, 44, 46, which is indicative of an inclination of the fuel cell stack 10 relative to the horizontal H. In a second step 104 of the method 104, the control device 40 compares a predefined comparison measured value with the measured measured value. And in a third step 106 of the method 100, the drain valve 34 is finally used to drain the product water 1

depending on the result of the comparison of step 104.

Furthermore, in a further step of the method 100, not shown, the drain valve 34 can be closed depending on a media pressure in the drain channel flow section 17 in order to prevent a medium in the drain channel flow section 17, such as fuel, from escaping the fuel -

cell stack 10 is drained.

The above explanations of the embodiments describe the present

present invention exclusively within the scope of examples.

Reference symbol list

1 product water

10 fuel cell stacks

12 inlet opening

14 outlet opening

15 fuel cell series

16 flow section

17 drain channel flow section 18 insulator plate

20 load plate

22 bus plate

30 drain system

32 drain channel

34 drain valve

36 Reservoir

40 control device

42 inclination angle measuring device 44 cell voltage measuring device 46 time interval measuring device

50 fuel cell system

52 water separators

60 vehicle

100 procedures

102 first step

104 second step

106 third step

H Horizontal g gravitational force direction & tilt angle

AVL List GmbH

Claims (1)

Patent claims 1. Fuel cell system (50), wherein the fuel cell system (50) comprises at least one fuel cell stack (10), which has inlet openings (12), outlet openings (14) and flow sections (16) which fluidly connect the inlet openings (12) to the outlet openings (14). , characterized in that the fuel cell system (50) comprises at least one drain system (30), wherein the drain system (30) has a drain channel (32) and at least one drain valve (34) arranged in the drain channel (32) for draining product water (1) from which has at least one fuel cell stack (10), wherein the at least one drain channel (32) leads from at least one drain channel flow section (17) of the flow sections (16) to the outside of the fuel cell stack (10), and wherein the fuel cell system (50) further has a Control device (40) for opening the at least one drain valve (34). 2. Fuel cell system (50) according to claim 1, characterized in that the drain channel (32) for passively draining product water (1) with is formed by means of gravitational force acting on the product water (1). 3. Fuel cell system (50) according to claim 1 or 2, characterized in that the fuel cell system (10) further comprises a water separator (52) outside the at least one fuel cell stack (10). 4. Fuel cell system (50) according to one of the preceding claims, characterized in that the drain channel (32) through an insulator plate (18) of the at least one fuel cell stack (10). 5. Fuel cell system (50) according to claim 4, characterized in that a reservoir (36) for collecting product water (1) is arranged in the drain channel (32), the reservoir (36) being in particular in the insulating gate plate (18) and / or the load plate (20) is formed. 6. Fuel cell system (50) according to one of the preceding claims, characterized in that the at least one drain valve (34) is outside half of the fuel cell stack (10) is arranged. (10) is arranged horizontally oriented in a vehicle (60). 8. Fuel cell system (50) according to one of the preceding claims, characterized in that the control device (40) is set up to receive a measured value from a measuring device (42, 44, 46), which is indicative of an inclination of the fuel cell stack (10 ) relative to a horizontal (H), the measured value is to be compared with a predefined comparison measured value and the at least one drain valve (34) depending on ability to open a result of the comparison. 9. Fuel cell system (50) according to one of the preceding claims, characterized in that the fuel cell system (50) has an inclination measuring device (42) for measuring an inclination angle (a) of the at least one fuel cell stack (10) relative to a horizontal (H) and the control device (40) is set up to open the at least one drain valve (34) when the measured angle of inclination (a) is exceeds a predefined inclination angle. 10. Fuel cell system (50) according to claim 9, characterized in that the at least one control device (40) is set up to open the at least one drain valve (34) when the measured inclination angle (@) the predefined minimum value for a predefined minimum duration exceeds. 11. Fuel cell system (50) according to one of the preceding claims, characterized in that the fuel cell system (50) has a cell voltage measuring device (44) for measuring a cell voltage of the at least one fuel cell stack (10) and the control device (40) is set up to do this at least to open a drain valve (34) when the measured cell voltage falls below a predefined cell voltage. strides. 12. Fuel cell system (50) according to claim 11, characterized in that the at least one control device (40) is set up to do this strides. 13. Fuel cell system (50) according to one of the preceding claims, characterized in that the control device (40) is set up to open the at least one drain valve (34) at predefined time intervals. to open and close. 14. Fuel cell system (50) according to one of the preceding claims, characterized in that the control device (40) for closing the drain valve (34) depending on a media pressure in the at least at least one outlet channel flow gas section (17) is set up. 15. Vehicle (60) with a fuel cell system (50) according to one of the preceding standing claims. 16. Method (100) for draining product water (1) from at least one fuel cell stack (10) of a fuel cell system (50), in particular a vehicle (60), according to one of the preceding claims, wherein the method (100) has the following steps: — Measuring a measured value that is indicative of an inclination of the Fuel cell stack (10) relative to a horizontal (H), — Comparing the measured value with a predefined comparison measurement worth, and — Opening the at least one drain valve (34) to drain the product duct water (1) depending on a result of the comparison.