DE102016118202A1 - Method for detecting a fluid outlet - Google Patents

Abstract

The invention relates to a method for detecting an undesirable leakage of a fluid from a fluid system, in particular an outlet of an anode operating medium (3) and / or an anode exhaust gas (4) from a fuel cell assembly, wherein a comparison of an opening degree setpoint with an opening degree Actual value of a first actuating means (24), in particular a pressure regulating valve (24), is carried out, and it is concluded in dependence of the comparison on whether a gas, in particular the anode operating medium (3), starts, a second actuating means (130) to flow through, it is concluded whether a / the second actuating means (130, 230) is functional, or it is concluded whether there is a leak in the fluid system. In one operation of the fluid system, the second actuating means (130) can be opened by a control device at one time, a liquid initially flowing through the second actuating means (130), and by comparing the opening degree setpoint with the opening degree actual value first actuating means (24) an incipient passage of the gas through the second actuating means (130) is detected. In one operation of the fluid system, the second actuating means (130, 230) can be opened by the control unit at one time, whereby the functionality of the second actuating means (130, 130) can be checked by comparing the opening degree setpoint with the opening degree actual value of the first actuating means (24). 230) is checked.

Description

The invention relates to a method for detecting a leakage of a fluid from a fluid system, in particular an outlet of an anode operating medium from a fuel cell assembly. Furthermore, the invention relates to a control unit, in particular an engine control unit, a fuel cell system and / or a fuel cell vehicle, wherein a detection method according to the invention can be carried out or carried out by the control unit and / or the fuel cell vehicle.

A fuel cell of a fuel cell assembly of a fuel cell system uses an electrochemical reaction of a hydrogen-containing (H, H ₂ ) fuel with oxygen (O, O ₂ ) to form water for generating electrical energy. For this purpose, the fuel cell contains as a core component at least one so-called membrane electrode assembly (MEA, Membrane Electrode Assembly), which is a structure of an ion-conducting or proton-conducting membrane and electrodes arranged on both sides of the membrane, an anode electrode and a cathode electrode. In addition, gas diffusion layers (GDL) can be arranged on both sides of the membrane-electrode assembly on the sides of the electrodes facing away from the membrane.

In general, the fuel cell is formed by means of a plurality of arranged in a stack (English stack) membrane electrode assemblies, wherein add their electrical power in an operation of the fuel cell. Bipolar plates, also called flux field plates or separator plates, are usually arranged between the individual membrane electrode units, which supply and usually also supply the membrane electrode units, ie a supply of the individual cells of the fuel cell, with the operating media, the so-called reactants serve a cooling of the fuel cell. In addition, the bipolar plates provide for a respective electrically conductive connection to the respective adjacent membrane-electrode units.

In an operation of the individual cells (single cell: membrane electrode unit and an associated anode space bounded by a bipolar plate and an associated cathode space bounded by a second bipolar plate) of the fuel cell, the fuel, a so-called anode operating medium, via an anode side open flow field of the bipolar plates supplied to the anode electrodes, where an electrochemical oxidation of H ₂ to 2H ^{+ occurs} with a release of electrons (2e ^- ) (H ₂ => 2H ⁺ + 2e ^- ). Through the membranes or electrolytes of the membrane-electrode units, which gas-tightly separate and electrically isolate the respective reaction spaces (anode space-cathode space pairs of the individual cells), a water-bound or anhydrous transport of the protons (H ⁺ ) formed by the anode electrodes ( (composite) anode of the fuel cell) in the anode spaces of the single cells to the cathode electrodes ((composite) cathode of the fuel cell) in the cathode spaces of the single cells.

The electrons provided at the anode are fed via electrical lines and an electrical load (electric traction motor, compressor, air conditioning et cetera) of the cathode. An oxygen-containing cathode operating medium is supplied to the cathode electrodes of the cathode via a cathode field open flow field of the bipolar plates, wherein an electrochemical reduction of O ₂ to 2O ^2- takes place under a recording of electrons (½O ₂ + 2e ^- => O ^2- ). At the same time, the oxygen anions (O ^2- ) formed on the cathode electrodes react with the protons transported through the membranes or electrolytes to form water (O ^2- + 2H ⁺ => H ₂ O).

A fuel cell vehicle describes a vehicle, which is operated or operated to a large extent by an electrical energy of a fuel cell or a fuel cell stack of a fuel cell assembly of the vehicle. Optionally, an energy store, in particular a rechargeable battery, may assist the fuel cell assembly to provide an electrical (traction) motor of the vehicle which generates torque for propulsion of the vehicle and, optionally, an electrical consumer with electrical energy. Further, it is possible for the fuel cell to assist the battery in driving the fuel cell vehicle.

In one operation of the fuel cell unit, liquid water is produced which can be trapped on / in an anode supply of the fuel cell assembly by means of a water separator, preferably a water separation module in a water collector, preferably of the water separation module (see also FIG 2 ). The water collector must be emptied by opening a separation valve, preferably the Wasserabscheidemoduls. If the opening time is too long, after the liquid water has completely separated or drained off, the anode operating medium can escape via the valve, which of course is undesirable. Determining an exact opening duration of the separation valve is dependent on various parameters and therefore can not be predetermined for all operating cases of the fuel cell assembly.

To ensure that substantially all of the liquid water exits the water collector, therefore, the separation valve must be open rather longer than shorter. For a good efficiency of the fuel cell system or low losses of the anode operating medium, however, it is important to leave as possible only liquid water and no anode operating medium from the water collector. Furthermore, the anode supply has a purge valve on / in the anode supply for discharging a purge gas (exhaust gas, exhaust gas) (see again 2 ).

In the prior art, this is done, for example, such that a sensor-triggered control of the separation valve by means of a water level sensor on / in the water collector takes place, a driving by means of the water level sensor is error-prone and also an extra sensor is necessary. Furthermore, an emptying of the water collector by a timed control of the Abscheideventils and an optionally map-based calculation of an accumulating amount of water done, with a precise amount of liquid water is difficult to predict. Furthermore, a complete emptying of the water collector via the separation valve by observing a pressure drop or an increased dosage of the anode operating medium from a time of exit of the anode operating medium take place, but at a high dynamics, in which a pressure of the anode operating medium changes quickly, is difficult to realize.

It is an object of the invention to specify a method for detecting a fluid outlet, in particular an outlet of an anode operating medium from a fuel cell assembly. The method should work reliably, if possible to dispense with an additional sensor to save costs and sources of error. Furthermore, a corresponding control unit, in particular an engine control unit, a corresponding fuel cell system and / or a corresponding fuel cell vehicle should be specified.

The object of the invention is a method for detecting a preferably unwanted leakage of a fluid from a fluid system, in particular an outlet of an anode operating medium from a fuel cell assembly; and by means of a control unit, in particular an engine control unit, a fuel cell system and / or a fuel cell vehicle; solved according to the independent claims. Advantageous developments, additional features and / or advantages of the invention will become apparent from the dependent claims and the following description.

In the method according to the invention, a comparison of an opening degree setpoint with an opening degree actual value of a first actuating means, in particular a pressure regulating valve, is made, it being concluded in a dependence of the comparison on whether a gas, in particular the anode operating medium starts, a second Adjusting means, in particular a separation valve, to flow, it is concluded whether a / the second actuating means, in particular a purge valve, is functional, and / or it is concluded whether there is a leak in the fluid system. By fluid system is meant a set of elements that are so interrelated and / or interconnected and capable of interacting in a manner that they can be considered as a task-bound, sense-bound and / or dedicated entity. An analog to a system is for example a device, a device, a device, an aggregate, a plant et cetera.

The degree of opening of the first actuating means, in particular of the pressure regulating valve, is a measure of which mass flow of fluid can flow or flow through the first actuating means and optionally the second actuating means, in particular the separating valve or the purge valve. The degree of opening depends essentially on an opening time or opening frequency and an effective flow cross-section of the first actuating means, wherein, for example, an opening operation and closing operation of the first actuating means can be disregarded (digitally setting, first actuating means, which is either open or closed).

Under the (known) opening degree setpoint that opening degree of the first actuating means, in particular the pressure control valve to understand, which has the first actuating means due to a (not exactly known) Istansteuerung (actual control signal) by a control unit, which in turn to a (known and desired) Sollansteuerung (reference control signal) goes back through the control unit. That is, the opening degree set value is a measure of that opening degree of the first actuating means, which it should assume on the basis of the Istansteuerung and is assumed by the fact that the first actuating means has this opening degree, but it does not have exactly.

Under the (not exactly known) opening degree actual value is that exact opening degree of the first actuating means, in particular the pressure control valve to understand, which actually has the first actuating means due to the (known and desired) target control (command control signal) by the control unit during operation. This Opening degree actual value is, however, only approximately known or even unknown, for example due to hysteresis (on the target control by the control unit variably delayed behavior of the opening degree actual value of the first actuating means), an effect of the fluid on a valve member of the first actuating means et cetera.

The actual control correlates with the value calculated on the basis of a system operation (for example in a fluid system of a fuel cell assembly: a pre-pressure before a pressure regulator, a power of a fuel cell or a fuel cell stack, a back pressure, the component geometries involved, the status of other valves (open / partially open / closed). The setpoint control correlates with the value which a controller sends to the valve in order to set its manipulated variable (again, for example, in the fuel cell assembly fluid system: a pressure in an anode supply).

In one embodiment of the detection method, in an operation of the fluid system, in particular of the fuel cell assembly, by a control device, in particular an engine control unit, the second actuating means, in particular the separation valve, opened at a time, wherein by the second actuating means initially substantially a liquid, in particular liquid Water, flows through it, and by the comparison of the opening degree setpoint with the opening degree of actual value of the first actuating means an incipient passage of the gas, in particular of the anode operating medium, is detected by the second actuating means.

In one embodiment of the detection method, in the case of a significant deviation of the opening degree setpoint from the opening degree actual value of the first actuating means, in particular the pressure regulating valve, it is assumed that the gas, in particular the anode operating medium, flows through the second actuating means, in particular the separating valve. wherein then the second actuating means is closed. With a tolerable deviation of the opening degree desired value from the opening degree actual value of the first actuating means, it is assumed that only substantially the liquid, in particular liquid water, flows through the second actuating means, or the deviation is due to a valve hysteresis.

That this is possible is due to the fact that the second actuating means, in particular the separation valve, is actuated correspondingly in the conditions currently prevailing in the fluid system or fuel cell unit, it being assumed that only substantially the liquid or liquid water flows through the second actuating means. If the liquid, the gas or the liquid water, the anode operating medium admixed (usually hydrogen or a hydrogen-containing, gaseous fuel), or only essentially the gas or the anode operating medium (optionally with portions of liquid water) to flow through the second actuating means , this has a significant effect on an opening degree actual value of the first actuating means, in particular of the pressure control valve, since the first actuating means is controlled with a desired control (opening degree setpoint), which correlates to a control, which assumes that substantially only the liquid or liquid water flows through the second adjusting means.

In one embodiment of the detection method, in an operation of the fluid system, in particular of the fuel cell assembly, the second actuating means, in particular the purge valve, is opened by a control device, in particular an engine control unit, whereby the comparison of the opening degree setpoint with the opening degree -Istwert the first actuating means, in particular the pressure control valve, a functionality of the second actuating means is checked. In the case of an intact second actuating means, a fluid, in particular the liquid, the gas, a mixture thereof or an anode waste gas, of the fluid system or fuel cell aggregate flows through the second actuating means. It is possible to transfer this checking method to another second adjusting means, in particular the separating valve, wherein the method can be carried out both exclusively with liquid water and exclusively with the anode operating medium.

In one embodiment of the detection method, a significant deviation of the opening degree setpoint from the opening degree actual value of the first actuating means, in particular the pressure regulating valve, assumes that the second actuating means, in particular the purge valve, has not switched. With a tolerable deviation of the opening degree actual value from the opening degree set value of the first actuating means, it is assumed that the second actuating means has switched correctly. In the former case, it is preferable to make an error entry in a corresponding register and to repeat the process. If the result that the second actuating means, in particular the purge valve does not switch, is preferably repeated, a message or an alarm occurs in that the second actuating means or a circuit connected thereto is faulty or defective.

In one embodiment of the detection method, if the deviation of the opening degree desired value from the opening degree actual value of the first actuating means, in particular the pressure regulating valve, is significant, permanent and preferably substantially constant (assuming a load case), it is assumed that the leakage in the fluid system, especially in the fuel cell unit, is present. In one embodiment of the detection method, the opening degree setpoint is compared with the opening degree actual value of the first adjusting means continuously or quasi-continuously (digitally in small time steps). The comparison can be made permanently in one operation of the fluid system, in particular of the fuel cell assembly, or temporarily, when the second actuating means, in particular the separation valve or the purge valve is to be opened, is opened, closed and / or closed.

In one embodiment of the detection method, the opening degree actual value of the first actuating means, in particular of the pressure regulating valve, becomes: from a load case or operating state of the fluid system, in particular of the fuel cell assembly; from an electric current produced by the fuel cell assembly; from a mass flow of a fluid in an anode supply of the fuel cell assembly; from a sensor signal of the first actuating means itself, in particular the pressure control valve; and / or based on information about at least one other actuator in the fluid system, in particular the fuel cell aggregate calculated. The opening degree set value of the first actuating means, in particular of the pressure regulating valve, is known, as already explained above, so that the comparison can be carried out, for example, by forming a difference with the opening degree actual value.

In one embodiment of the detection method: the first actuating means is designed as a pressure regulating valve; if the detection method is carried out only in predetermined load cases or operating states of the fluid system, in particular of the fuel cell assembly; the comparison of the opening degree setpoint with the opening degree actual value of the first actuating means, in particular of the pressure regulating valve, is based on a subtraction; and / or a hysteresis of the actuating means, in particular the pressure control valve, is taken into account when comparing the opening degree setpoint with the opening degree actual value of the first actuating means. In embodiments of the detection method, an enumeration point, an arbitrary plurality of enumeration points or all enumeration points can be realized by an enumeration.

According to the invention, a calculation of the opening degree actual value of the first actuating means, which is preferably designed as a pressure regulating valve, takes place. In one embodiment, a determination of a deviation of the opening degree actual value from the opening degree setpoint of the first actuating means for checking whether via the separation valve (a second adjusting means) liquid water or anode operating medium is deposited. Further, in one embodiment, determining a deviation of the opening degree actual value from the opening degree set value of the first actuating means when switching the purge valve (another second actuating means) in order to check the function of the purge valve. In addition, a leakage of the fluid system or the fuel cell assembly can be detected. This can be transferred to any adjusting means of any fluid system.

In the case of an NO-actuating agent (NO: English normally open), which automatically opens or is open without an active control, it should always be checked whether there is a correspondingly large deviation between a nominal value and an actual value of a pressure regulator. In the case of an NC actuating means (NC: English normally closed), which is closed or closed without an active control, a check of the control signal of a pressure regulator should only be necessary if the NC actuating means is actively activated.

The invention is explained in more detail below with reference to exemplary embodiments with reference to the attached schematic and not to scale drawing. Sections, elements, components, units, schemes and / or components that have identical, univocal or analogous training and / or function are in the description of the figures (see below), the list of reference numerals, the patent claims and in the figures of the drawing with the same Reference number marked. A possible, not described in the description (description of the invention (see above), figure description (see below)), not shown in the drawing and / or not final alternative, a static and / or kinematic inversion, a combination et cetera to the embodiments of the Invention or a component, a scheme, a unit, a component, an element or a portion thereof, can also be taken from the list of reference numerals.

In the invention, a feature (section, element, component, unit, component, function, size, et cetera) may be positively, that is, present, or negative, that is, absent, with a negative feature not explicitly explained as a feature. if it is not important that it is absent. A feature of this Specification (description, list of references, claims, drawing) may be applied not only in a specified manner and / or manner but also in a different manner and / or manner (isolation, summary, substitution, addition, isolation, et cetera). In particular, it is possible to replace, add or omit a feature in the claims and / or the description based on a reference numeral and a feature assigned thereto, or vice versa, in the description, the list of reference numerals, the patent claims and / or the drawing. In addition, a feature in a claim can be interpreted and / or specified in more detail.

The features of this specification are also interpretable as optional features (given the (mostly unknown) state of the art); that is, each feature can be considered as an optional, arbitrary, or preferred, that is, as a non-binding, feature. Thus, a detachment of a feature, possibly including its periphery, from an embodiment possible, this feature is then transferable to a generalized inventive concept. The absence of a feature (negative feature) in one embodiment demonstrates that the feature is optional with respect to the invention. Furthermore, in the case of a type term for a feature, a generic term for the feature is also readable (possibly further hierarchical structure into subgenus, section et cetera), whereby, for example, taking into account equality and / or equivalence, a generalization of one or this feature is possible. - In the merely exemplary figures show:

1 a simplified block diagram of an embodiment of a fuel cell assembly of a fuel cell system according to the invention;

2 a simplified block diagram of an embodiment of an anode supply of the fuel cell assembly with a Wasserabscheidemodul and a purge valve;

3 a flow diagram of a first embodiment of a method according to the invention for detecting an exit of an anode operating medium from a separation valve of the fuel cell assembly; and

4 a flowchart of a second embodiment of the method according to the invention for detecting a functionality of a purge valve of the fuel cell assembly.

The invention is based on embodiments of methods for detecting an exit of an anode operating medium 3 from a fuel cell aggregate 1 a fuel cell system of a fuel cell vehicle (passenger car, passenger transport vehicle, bus, ATV (English All Terrain Vehicle), motorcycle, commercial vehicle, (heavy) truck, construction vehicle, construction machine, special vehicle, rail vehicle) explained in more detail. The invention is further applicable to a method for detecting leakage of a fluid from a fluid system, wherein the anode operating medium is mixed with any fluid (gas and / or liquid) and the fuel cell aggregate 1 can be identified with any fluid system.

In the drawing, only those portions of the fuel cell assembly 1 of the fuel cell vehicle, which are necessary for an understanding of the invention. In particular, attention is drawn to a representation of a periphery of the fuel cell assembly 1 , Sensors, electronic, electrical and power electrical devices and / or facilities et cetera been largely waived. Although the invention has been described and illustrated in detail by preferred embodiments, the invention is not limited by the disclosed embodiments. Other variations can be deduced therefrom without departing from the scope of the invention.

The 1 shows a fuel cell aggregate 1 a fuel cell system according to a preferred embodiment of the invention. The fuel cell aggregate 1 is preferably part of the vehicle, not shown in detail, in particular a motor vehicle or an electric vehicle (fuel cell vehicle), which preferably has an electric traction motor, which or by a fuel cell 10 of the fuel cell aggregate 1 can be supplied with electrical energy. The fuel cell system differs from the fuel cell aggregate 1 In particular by not shown power electrical, electrical and electronic devices and / or devices (converter, battery, inverter et cetera), an engine control unit (English ECU, Engine Control Unit) et cetera, which the fuel cell assembly 1 not included.

The fuel cell aggregate 1 includes as a core component the fuel cell 10 or a fuel cell stack 17 , Which or which preferably a plurality of stacked individual fuel cells 11 , below as single cells 11 designated, wherein the fuel cell stack 17 in a preferably fluid-tight stack housing 16 is housed (fuel cell 10 ). Every single cell 11 includes an anode compartment 12 and a cathode compartment 13 , wherein the anode compartment 12 and the cathode compartment 13 from a membrane (part of a membrane-electrode assembly 14 , see below), preferably an ion-conductive polymer electrolyte membrane, spatially and electrically separated from each other (see detail).

The anode rooms 12 and the cathode rooms 13 the fuel cell 10 each have a catalytic electrode (part of the respective membrane-electrode unit 14 , see below), that is, an anode electrode and a cathode electrode, each of which catalyzes a partial reaction (see above) of a fuel cell reaction. The anode electrode and the cathode electrode each comprise a catalytic material, for example platinum, which is preferably supported on an electrically conductive carrier material with a comparatively large specific surface, for example a carbon-based material.

A structure of a membrane and the associated electrodes is also called a membrane-electrode unit 14 designated. Between two such membrane-electrode units 14 (in the 1 is only a single membrane electrode assembly 14 indicated) is further a bipolar plate 15 arranged (in the 1 again merely indicated), which supply of operating media 3 . 5 into a relevant anode compartment 12 a first single cell 11 and a respective cathode compartment 13 a directly adjacent second single cell 11 serves and which, moreover, an electrically conductive connection between the two directly adjacent individual cells 11 realized.

Between a bipolar plate 15 and a directly adjacent anode electrode of a membrane-electrode assembly 14 is an anode room 12 and between a cathode electrode of the same membrane-electrode assembly 14 and a second bipolar plate directly adjacent thereto 15 is a cathode compartment 13 a single cell 11 (Anode space-cathode space pair 12 / 13 ) educated. Optionally, gas diffusion layers between the membrane-electrode assemblies 14 and the bipolar plates 15 be arranged. In the fuel cell 10 or in the fuel cell stack 17 So are membrane electrode units 14 and bipolar plates 15 alternately arranged or stacked (fuel cell stack 17 ).

To supply the fuel cell 10 or the fuel cell stack 17 with the operating media 3 . 5 has the fuel cell aggregate 1 or the fuel cell system on the one hand an anode supply 20 and on the other hand, a cathode supply 30 on.

The anode supply 20 includes an anode supply path 21 , which is a supply of an anode operating medium 3 , a fuel 3 , for example hydrogen 3 or a hydrogen-containing gas mixture 3 , in the anode rooms 12 the fuel cell 10 serves. For this purpose, the anode supply path connects 21 a fuel storage 23 or fuel tank 23 via a jet pump 29 or a gas jet pump 29 with an anode input of the fuel cell 10 , The anode supply 20 further includes an anode exhaust path 22 , which is an anode exhaust 4 from the anode chambers 12 through an anode output of the fuel cell 10 through. An established anode operating pressure on an anode side of the fuel cell 10 is preferably by means of an actuating means 24 , also as first adjusting agent 24 referred to, in the anode supply path 21 adjustable.

In addition, the anode supply points 20 preferably a fuel recirculation line 25 on which the anode exhaust path 22 with the anode supply path 21 fluid mechanically connects. A recirculation of the anode operating medium 3 , that is, the actually preferred to be fueled fuel 3 , is often set up, the most over-stoichiometric anode operating medium 3 the fuel cell 10 to be returned and used. This is in / at the fuel recirculation line 25 a recirculation compressor 26 preferably arranged, by means of which a recirculation can be realized and / or a recirculation rate is adjustable. A drive of the recirculation compressor 26 is preferably done by means of an electric motor 27 or a drive 27 , which in particular with a corresponding power electronics 28 Is provided.

The cathode supply 30 includes a cathode supply path 31 which is the cathode spaces 13 the fuel cell 10 a cathode operating medium 5 for example, oxygen 5 or an oxygen-containing gas mixture 5 , preferably air 5 , feeds, which in particular from the environment 2 is sucked. The cathode supply 30 further includes a cathode exhaust path 32 , which is a cathode exhaust 6 , in particular an exhaust air 6 , from the cathode rooms 13 the fuel cell 10 through dissipates and this or this optionally supplied exhaust device or exhaust system supplies.

For a promotion and compression of the cathode operating medium 5 is at / in the cathode supply path 31 preferably at least one cathode compressor 33 arranged. In Embodiments is the cathode compressor 33 as a cathode compressor driven exclusively or also by an electric motor 33 designed, the drive (also) by means of an electric motor 34 or a drive 34 takes place, which preferably with a corresponding power electronics 35 Is provided.

The cathode compressor is preferred 33 as an at least electrically driven turbocharger 33 (English ETC, Electric Turbo Charger) trained. The cathode compressor 33 can also be characterized by a in the cathode exhaust path 32 arranged cathode turbine 36 optionally with variable turbine geometry, be supported by means of a common shaft or a transmission. The cathode turbine 36 represents an expander, which is an expansion of the cathode exhaust gas 6 and thus a lowering of the fluid pressure causes (increase efficiency fuel cell 10 ).

The cathode supply 30 may according to the illustrated embodiment, a wastegate 37 or a Waste Management 37 which or which the cathode supply path 31 or a cathode supply line with the cathode exhaust path 32 or a cathode exhaust pipe connects, so a cathode-side bypass for the fuel cell 10 represents. The wastegate 37 allows an increase in a volume flow of the cathode compressor 33 at substantially constant volume flow into the fuel cell stack of the fuel cell 10 into it. One in the wastegate 37 arranged adjusting means 38 allows adjustment of a volume flow of the fuel cell 10 optionally immediate cathode operating medium 5 ,

All adjusting means 24 . 38 , ( 130 . 230 ; see below) of the fuel cell unit 1 can be designed as controllable, controllable or non-controllable valves, flaps, throttles, apertures et cetera. For insulation of the fuel cell 10 from the surroundings 2 or another object may be at least one further corresponding actuating means in the anode supply 20 and / or the cathode supply 30 , for example on / in an anode path 21 . 22 or a line of the anode path 21 . 22 , and / or on / in a cathode path 31 . 32 or a line of the cathode path 31 . 32 be arranged.

The fuel cell aggregate 1 further preferably comprises a humidifier 39 on. The humidifier 39 On the one hand, this is on / in the cathode supply path 31 arranged it from the cathode operating medium 5 can be flowed through. On the other hand, the humidifier 39 such on / in the cathode exhaust path 32 arranged it from the cathode exhaust 6 can be flowed through. The humidifier 39 is in the cathode supply path 31 preferably downstream of the cathode compressor 33 and upstream of a cathode input of the fuel cell 10 , and in the cathode exhaust path 32 between a cathode output of the fuel cell 10 and the on / in the cathode exhaust path 32 provided cathode turbine 36 arranged. A moisture transmitter of the humidifier 39 preferably has a plurality of membranes, which are often formed either flat or in the form of hollow fibers, optionally as a hollow fiber body.

Various further details of the fuel cell system or of the fuel cell aggregate 1 or the fuel cell 10 / of the fuel cell stack 17 , the anode supply 20 and / or the cathode supply 30 are in the 1 not shown for reasons of clarity. So can the humidifier 39 from the cathode supply path 31 and / or the cathode exhaust path 32 be bypassed by means of a bypass (adjusting means). There may also be a turbine bypass on the cathode exhaust pathway 32 be provided, which is the cathode turbine 36 bypasses (adjusting means).

Furthermore, at / in the anode exhaust path 22 and / or cathode exhaust path 32 a water separator be installed, by means of which a from the relevant partial reaction of the fuel cell 10 resulting product water condensable and / or separable and optionally in a water collector for storing is derivable. Furthermore, the anode supply 20 alternatively or additionally to the cathode supply 30 analog humidifier 39 exhibit. Furthermore, the anode exhaust path 22 in the cathode exhaust path 32 or vice versa, the anode exhaust gas 4 and the cathode off-gas 6 optionally can be removed via the common exhaust device. Moreover, in embodiments, the cathode operating medium 5 a on / in the cathode supply path 31 flow through the provided intercooler.

The fuel cell aggregate 1 further comprises a in the 1 exemplified and greatly simplified cooling medium supply 40 , which is a cooling circuit 40 includes, in which the fuel cell 10 is integrated heat transfer. The cooling circuit 40 includes a cooling medium supply path 41 , which of the fuel cell 10 a comparatively cool cooling medium 7 supplies, and further a cooling medium discharge path 42 that of the fuel cell 10 a comparatively warm cooling medium 8th dissipates. A promotion of the in the cooling circuit 40 circulating cooling medium 7 / 8th is preferably carried out by means of at least one electric motor driven cooling medium pump in the cooling circuit 40 , The cooling medium 7 / 8th , especially water 7 / 8th , one Water-alcohol mixture 7 / 8th or a water-ethylene glycol mixture 7 / 8th is coolable by a radiator or main vehicle radiator in the cooling circuit, which usually has an air blower.

The 2 shows the anode supply 20 with a water separation module 100 for separating, collecting and draining liquid water. For this purpose, the Wasserabscheidemodul 100 preferably a water separator 110 , a water collector 120 and an adjusting agent 130 , in particular a separation valve 130 , also as a second actuating means 130 designated (see above), on. Here, the actuating means 130 separate from the water separation module 100 be provided. Furthermore, the anode supply 20 an actuating agent 230 , in particular a purge valve 230 , also as a second adjusting agent 230 designated (see above), on. Both the water separation module 100 as well as the purge valve 230 are downstream with the environment 2 in fluid communication. That is by means of the separation valve 130 and / or purge valves 230 is the anode supply 20 with the environment 2 be brought into fluid communication.

The invention includes a calculation of a necessary opening (opening degree) of the pressure regulating valve 24 the anode supply 20 for a respective dynamic load case of the fuel cell assembly 1 , For a specific load case, this results in a certain degree of opening of the pressure control valve 24 one. If over the separation valve 130 Only water is deposited, this has a negligible influence on the degree of opening of the pressure control valve 24 , Occurs, however, anode operating medium 3 When removing water, a deviation of calculated (opening degree actual value) and set by a control (opening degree setpoint) opening degree of the pressure regulating valve 24 one ( 3 ). In this case, a hysteresis of the pressure regulating valve is preferred 24 to be observed.

The boxes A to M in the 3 are as follows: A: Open the separation valve 130 by control (for example time-controlled), B: calculation of the opening-degree-actual value of the pressure regulating valve 24 , C: Comparison opening degree setpoint of the pressure control valve 24 with opening degree actual value, D: Deviation: Yes (continue with box E), E: Outlet operating medium outlet 3 via the separation valve 130 , F: Premature closing of the separation valve 130 (opposite to the control) to avoid losses, G: Deviation: No, H: Exiting of water via separation valve 130 , J: Control wants separation valve 130 close, K: No (continue with box B), L: Yes (continue with box M), M: Separator valve 130 will be closed.

The detection method may be implemented, for example, as follows ( 3 ). The separation valve 130 is opened by an electronic control (for example timed by the engine control unit) (box A). In the temporal sequence according to the invention, the opening degree-actual value of the pressure regulating valve 24 calculated (box B), which is compared with its opening degree setpoint (for example, difference, box C). If there is a significant deviation (yes path, D), it is concluded that the anode operating medium 3 via the separation valve 130 outlet (box E), wherein the separating valve 130 (versus the controller) to avoid losses of the anode operating medium 3 closed early (box F).

If there is no significant deviation (Nei-path, G, continue box H) it is concluded that water is via the separation valve 130 exit (box H), it is up to the controller how to proceed. Will the controller the separation valve 130 close (box J, yes path, L, continue at box M), then the Abscheideventil 130 closed (box M). If the controller continues to drain water (no-path, K, go to box B), the detection procedure in the box will calculate the opening degree feedback value of the pressure regulator 24 (Box B).

The designations A to H in the 4 are as follows: A: opening the purge valve 230 by control (for example timed), B: calculating the opening degree actual value of the pressure regulating valve 24 , C: Comparison opening degree setpoint of the pressure control valve 24 with opening degree actual value, D: Deviation: No, E: purge valve 230 has switched, F: deviation: Yes, G: purge valve 230 is not open despite control signal, H: error. This assumes that an influence of the purge valve 230 on a pressure regulator is taken into account in the calculation.

Further, on the deviation of the opening degree actual value from the opening degree set value of the pressure regulating valve 24 be recognized, whether a relevant valve, for example, the purge valve 230 actually turns. This is applicable to other actuating means. The detection method can be implemented, for example, as follows (see 4 ). The purge valve 230 is opened by the electronic control (eg timed by the engine control unit) (box A). In the temporal sequence according to the invention, the opening degree-actual value of the pressure regulating valve 24 calculated (box B), which with an opening degree setpoint of the pressure control valve 24 (for example, difference, box C). If there is no significant deviation (no path, D, continue with box E), then it is concluded that the purge valve 230 has switched, is open and works correctly (box E).

Results from the comparison of the opening degree actual value with the opening degree set value of the pressure regulating valve 24 (Box C) a significant deviation, it is concluded that the purge valve 230 despite control signal is not open by the controller (no path, F, continue at box G). An error is diagnosed (box H). Furthermore, if a significant deviation is permanent and preferably substantially constant, it is possible to conclude that there is a leak in the fuel cell assembly 1 occured. If this deviation has a size equal to that of a NO valve, one can assume that the NO valve is not activated.

LIST OF REFERENCE NUMBERS

1

 Fuel cell aggregate of the fuel cell system

2

 Environment, air

3

 Fluid, operating medium, reactant, in particular anode operating medium, actual fuel, preferably hydrogen or hydrogen-containing gas mixture, inflowing

4

 Fluid, exhaust possibly including liquid water, in particular anode exhaust, outflowing

5

 Fluid, operating medium, reactant, in particular cathode operating medium, preferably (ambient) air, flowing

6

 Fluid, exhaust gas optionally including liquid water, in particular cathode exhaust gas, preferably exhaust air, outflowing

7

 Fluid, cooling medium, cooling water (water, water-alcohol mixture, water-ethylene glycol mixture), inflowing

8th

 Fluid, cooling medium, cooling water, outflowing

10

Fuel cell of the fuel cell unit 1 or the fuel cell system

11

Single cell with an anode electrode of the anode of the fuel cell 10 and a cathode electrode of the cathode of the fuel cell 10 , Single fuel cell

12

Anode compartment of a single cell 11

13

Cathode space of a single cell 11

14

Membrane electrode unit with preferably a polymer electrolyte membrane and an anode electrode and a cathode electrode and optionally in each case a carrier therefor

15

Bipolar plate, flow field plate, separator plate

16

Stack housing of the fuel cell 10

17

Fuel cell stack of the fuel cell 10

20

Fuel cell supply, anode supply, anode circuit of the fuel cell

10

or the fuel cell stack 10

21

Path, supply path, flow path, anode supply path

22

Path, exhaust path, flow path, anode exhaust path

23

Fuel storage, fuel tank with anode operating medium 3

24

(first) adjusting means, (on) controllable, (controllable), not controllable, in particular valve, flap, throttle, aperture et cetera, pressure regulating valve

25

Fuel recirculation line

26

Fluid conveyor, (flow) compressor, recirculation compressor, compressor, pump with the motor 27 , Roots blower et cetera

27

(Electric) engine, drive with electric motor, if necessary including gearbox

28

Electronics, in particular power electronics for the motor 27

29

(Gas) jet pump, ejector

30

Fuel cell supply, cathode supply, cathode circuit of the fuel cell 10 or the fuel cell stack 10

31

Path, supply path, flow path, cathode supply path

32

Path, exhaust path, flow path, cathode exhaust path

33

(second) fluid / air conveyor, compressor, cathode compressor, compressor, pump with the motor 34

34

Motor, electric motor, drive with electric motor, possibly including gearbox

35

Electronics, in particular power electronics for the motor 34

36

Turbine with optionally variable turbine geometry, cathode turbine, expander, possibly an exhaust gas turbocharger

37

Wastegate, Waste Management

38

Adjusting means, (on) controllable, (controllable), not controllable, in particular valve, flap, throttle, aperture et cetera

39

Humidifier, humidity transmitter with humidity transmitter

40

Fuel cell supply, cooling medium supply, cooling circuit of the fuel cell

10

or the fuel cell stack 10

41

Path, inlet path, flow path, cooling medium inlet path

42

Path, drain path, flow path, cooling medium drain path

43

Coolant pump

100

Wasserabscheidemodul

110

water

120

water collector

130

(second) actuating means, (on) controllable, (controllable), not controllable, in particular valve, flap, throttle, aperture et cetera, separating valve

230

(second) adjusting means, (on) controllable, (controllable), not controllable, in particular valve, flap, throttle, aperture et cetera, purge valve

Claims (10)

Method for detecting an undesired escape of a fluid from a fluid system, in particular an outlet of an anode operating medium ( 3 ) and / or an anode exhaust gas ( 4 ) from a fuel cell aggregate ( 1 ), characterized in that a comparison of an opening degree setpoint with an opening degree actual value of a first actuating means ( 24 ), in particular a pressure regulating valve ( 24 ), and it is concluded in dependence of the comparison on whether a gas, in particular the anode operating medium ( 3 ), a second actuating means ( 130 ), it is concluded whether a / the second actuating means ( 130 . 230 ) is functional, or it is concluded whether there is a leak in the fluid system. Detecting method according to claim 1, characterized in that in an operation of the fluid system by a control device at a time the second actuating means ( 130 ) is opened, wherein by the second actuating means ( 130 ) substantially first flows through a liquid, and by comparing the opening degree setpoint with the opening degree actual value of the first actuating means ( 24 ) an incipient passage of the gas through the second actuating means ( 130 ) is detected. Detection method according to claim 1 or 2, characterized in that, in the case of a significant deviation of the opening degree set value from the opening degree actual value of the first actuating means ( 24 ) is assumed that the gas through the second actuating means ( 130 ) and then the second actuating means ( 130 ) is closed; and / or at a tolerable deviation of the opening degree setpoint from the opening degree actual value of the first actuating means ( 24 ) is assumed that only substantially the liquid through the second actuating means ( 130 ) flows through. Detecting method according to claim 1, characterized in that in an operation of the fluid system by a control device at a time the second actuating means ( 130 . 230 ) is opened, wherein by comparing the opening degree setpoint with the opening degree actual value of the first actuating means ( 24 ) a functionality of the second actuating means ( 130 . 230 ) is checked. Detection method according to claim 1 or 4, characterized in that, in the case of a significant deviation of the opening degree set value from the opening degree actual value of the first actuating means ( 24 ) it is assumed that the second actuating means ( 130 . 230 ) has not switched; and / or at a tolerable deviation of the opening degree actual value from the opening degree set value of the first actuating means ( 24 ) it is assumed that the second actuating means ( 130 . 230 ) has switched correctly. Detection method according to one of claims 1 to 5, characterized in that in the case of a significant, permanent and preferably substantially constant deviation of the opening degree setpoint from the opening degree actual value of the first actuating means ( 24 ) it is assumed that the leakage is present in the fluid system. Detection method according to one of claims 1 to 6, characterized in that the comparison of the opening degree setpoint with the opening degree actual value of the first actuating means ( 24 ) takes place continuously or quasi-continuously; and / or the comparison is made permanently in an operation of the fluid system or temporarily when the second actuating means ( 130 . 230 ) is open. Detection method according to one of claims 1 to 7, characterized in that the opening degree actual value of the first actuating means ( 24 ): from a load case or operating condition of the fluid system; from one through the fuel cell aggregate ( 1 ) produced electricity; from a mass flow of a fluid ( 3 . 4 ) in an anode supply ( 20 ) of the fuel cell aggregate ( 1 ); from a sensor signal of the first actuating means ( 24 ) even; and / or based on information about at least one other actuator in the fluid system. Detection method according to one of claims 1 to 8, characterized in that: the first actuating means ( 24 ) as the pressure regulating valve ( 24 ) is trained; the detecting method is performed only in predetermined load cases or operating conditions of the fluid system; the comparison of the opening degree setpoint with the opening degree actual value of the first actuating means ( 24 ) is based on a difference; and / or when comparing the opening degree set value with the opening degree actual value of the first actuating means ( 24 ) a hysteresis of the first actuating means ( 24 ) is taken into account. Control unit, in particular engine control unit, fuel cell system and / or Fuel cell vehicle, characterized in that by the control unit, the fuel cell system and / or the fuel cell vehicle, a detection method according to any one of claims 1 to 9 is feasible or carried out.

Images