DE102015008937A1 - Method for operating a fuel cell system - Google Patents

Abstract

The invention relates to a method for operating a fuel cell system (1) in a vehicle (2) which, in operating phases in which the vehicle (2) is turned off, remains unexpectedly activated for a user or is temporarily reactivated unexpectedly by a predetermined state of the fuel cell system (1). The method according to the invention is characterized in that, during the unexpected activation of the fuel cell system, phase-shifted sound is generated and radiated to the resulting noise.

Description

The invention relates to a method for operating a fuel cell system in a vehicle according to the closer defined in the preamble of claim 1.

Fuel cell systems for use in vehicles are known from the general state of the art. Typically, fuel cell systems are designed for vehicle use in the form of so-called PEM fuel cell systems. It is the case that the membranes within the fuel cell, which serve as electrolyte, must have a certain humidity in order to ensure reliable and reliable functionality of the fuel cell. At ambient temperatures below freezing, and this is typically not fully avoided on vehicles, it may therefore happen that the fuel cell itself freezes. Depending on the amount of moisture and water in the fuel cell system, this can significantly delay the restart of the fuel cell system.

It is therefore known from the general state of the art that a fuel cell system in a vehicle, in particular when switching off the fuel cell system, can be brought into a state which favors a quick and reliable restart of the fuel cell system, even in adverse environmental conditions. Now it is such that such a shutdown procedure lasts comparatively long and often runs when the vehicle has long been turned off and the driver of the vehicle is no longer in the range of the vehicle, or at least expected no action from this vehicle. Such an unexpected activation of the fuel cell system and the accompanying noises are extremely disturbing in this case.

Another way to prepare a fuel cell system for a restart in ambient conditions with temperatures below freezing is to "wake up" the fuel cell system, for example, time-controlled or temperature-controlled only for a short time whenever the temperature drops and critical conditions for the restart are to be feared. In this case, after waking up, a conditioning routine may be started, which also ensures that the fuel cell system is in good condition for eventual restart, even at temperatures below freezing. Typically, such a conditioning routine is similar to a shutdown procedure. Typically, a fan or air conveyor is operated to dry the fuel cell system to some degree and to discharge moisture that could eventually freeze out of the fuel cell system. For this purpose, a control of valves within the fuel cell system is typically required in addition to the air conveyor or a blower. Such activation of the fuel cell system is accompanied by corresponding noise emissions, which are not expected by the user or passers-by in a parked vehicle, and which therefore can be perceived as particularly disturbing.

From the further general state of the art, it is now also known that sound waves can be reduced by active damping systems wholly or at least significantly in their intensity by producing phase-shifted sound and delivered in addition to the resulting noise. This "anti-noise" then ensures that the actual sound is reduced accordingly, so as to minimize the overall noise or suppress noise emissions altogether. In addition to an application for example in active headphone systems and applications in the field of automotive technology are known, for example from the DE 697 23 945 D1 or the EP 2 071 213 A1 , of the DE 195 15 769 A1 Here are just a few examples.

It is common to all these systems for generating anti-sounding that they must record the sounds that are to be reduced or suppressed via a measuring microphone in order then to generate the desired phase-shifted sound. This is extremely complex and complex, since the signal chain between the detection of the noise with the measuring microphone on the one hand and the generation of phase-shifted sound through one or more speakers on the other hand must be extremely fast. This makes the structure and the components required for this consuming and expensive.

The object of the present invention is now to provide an improved method for operating a fuel cell system in a vehicle according to the preamble of claim 1, which in particular allows a reduction of noise emissions in unattended operation.

According to the invention this object is achieved by a method having the features in claim 1. Advantageous embodiments and further developments emerge from the subclaims dependent thereon.

In the method according to the invention for operating a fuel cell system, it is provided that in situations in which a Preconditioning of the fuel cell system takes place for a later restart, and which are typically outside the actual operation of the fuel cell system, a sound phase-shifted to the resulting noise is generated. The vehicle is already parked or is already parked for a long period of time and the fuel cell system is working to prepare the vehicle for a later fast and swift re-start. Such operation is also referred to as freeze-start conditioning mode.

Such an unexpected activation of the fuel cell system causes sounds that are generally perceived by the user as extremely disturbing, especially since they occur quite unexpectedly. He has just parked the vehicle with the fuel cell system or the vehicle has been standing for some time and suddenly turns on to achieve a predetermined state of the fuel cell system. In order to act against these unwanted noises, so according to the invention, a phase-offset sound is generated to the resulting noise. This phase-shifted sound is added to the sound waves of the noise and ideally eliminates them completely or can at least significantly reduce their intensity so that only a very low noise level of the fuel cell vehicle occurs. By such a reduction of the noise during an unexpected activation of the fuel cell system for the user, therefore, a reduced disturbance of the user is achieved, which is ultimately a decisive advantage for the ease of use of the vehicle with the fuel cell system.

According to an extraordinarily advantageous embodiment of the method according to the invention, it is the case that the unexpected activation takes place in accordance with a predetermined sequence, wherein the phase-shifted sound suitable for this sequence is called up from a memory. In this particularly favorable and advantageous development of the method according to the invention, the fact is exploited that the unexpected activation of the fuel cell system typically takes place according to one or more less predefined sequences. The processes themselves are known and can be analyzed according to the resulting noise emissions. Typically, a fan or the air conveyor of the fuel cell system will run for a certain predetermined time. In addition, certain valves are actuated, each resulting in the same noise emission, which can be recorded once and stored. The method according to the invention can then be operated in such a way that the out-of-phase sound matched to the respective predetermined unexpected activation is retrieved from a memory. The effort to use a measuring microphone and to calculate the required anti-sound virtually in real time, is therefore unnecessary. With minimal effort to produce the phase-shifted sound, so it is easily possible to hold this prefabricated in a storage system ready for the activation required in each case in order to then retrieve it easily and efficiently.

According to a further advantageous embodiment of the idea, it is possible that the expiration of the unexpected activation is selected according to environmental conditions from a plurality of predetermined sequences. The process does not always have to be the same. It can be selected, for example, depending on predetermined environmental conditions, in particular temperatures. Nevertheless, the total number of available processes will remain relatively small, so that even in this variant of the method according to the invention in a particularly advantageous manner in a memory of the phase-shifted sound can be kept to the respective selected sequence.

The phase-shifted sound is radiated according to an advantageous development of the method according to the invention via one or preferably a plurality of arranged in the interior and / or exterior of the vehicle speakers. In particular, these can be positioned in such a way that a particularly efficient mixing of the phase-shifted sound with the noise emissions occurring during the unexpected activation results, so that the resulting noise can be completely avoided or at least greatly attenuated in intensity.

As already mentioned, it is possible to dispense with a measurement of the noise resulting from the unexpected activation in the advantageous variants described, which makes possible a considerable advantage with regard to the hardware on the one hand and the control of the method on the other hand.

Further advantageous embodiments of the method according to the invention will become apparent from the remaining dependent subclaims and will be described with reference to an embodiment, which will be explained in more detail below with reference to the figure.

The sole attached figure shows a vehicle indicated in principle with a fuel cell system for carrying out the method according to the invention.

The sole attached figure shows a fuel cell system indicated in principle 1 in a vehicle 2 , The core of the fuel cell system 1 forms a fuel cell 3 , which should be constructed as a stack of single cells, as a so-called fuel cell stack, preferably in PEM technology. The fuel cell 3 has an anode compartment 4 and a cathode compartment 5 on. In the illustrated embodiment, one example of each of the anode spaces 4 and one of the cathode rooms 5 , separated by a proton-conducting membrane 6 , indicated. In regular operation of the fuel cell system 1 becomes the cathode compartment 5 Air via an air conveyor 7 fed. In the very simplified embodiment shown here, the exhaust air passes through an exhaust duct 8th in the nearby areas. It is clear to the person skilled in the art that here as well an exhaust air turbine, a water separator and / or a humidifier in the exhaust air line 8th could be arranged with. On the anode side, the fuel cell 3 from a compressed gas storage 9 via a pressure regulating and metering device 10 supplied with hydrogen. This hydrogen flows into the anode compartment 4 and is partially consumed herein. Anode exhaust consisting of unconsumed hydrogen, product water and inert gases which were either present in the stored hydrogen or through the proton conducting membrane 6 from the cathode compartment 5 in the anode compartment 4 are diffused, flow through a recirculation line 11 a so-called Anodenkreislaufs 12 back and together with fresh hydrogen to the anode compartment 4 fed again. To compensate for the pressure losses thereby serves a recirculation conveyor 13 , which is exemplified here as a blower. Equally well, a gas jet pump or a combination of gas jet pump and blower could be used here. In the anode cycle 12 is also a water separator 14 provided, which via a valve device 15 and a blow-off line 16 suitable for this is water which has accumulated in it and inert gases which accumulate in the anode space cycle 12 accumulate with time, drain. This is known to the person skilled in the art, so that it need not be discussed further here.

Such fuel cell systems 1 can now start badly under certain environmental conditions. Such environmental conditions may be present, for example, when the temperatures in the environment of the vehicle 2 fall below freezing and in the fuel cell 3 resulting product water freezes. In order to be able to start easily, efficiently and in particular sufficiently quickly even under such adverse environmental conditions, it is generally known and customary for the fuel cell system 1 via a suitable operation of the fuel cell system 1 in a predetermined state of the fuel cell system 1 is brought, in which a simple and efficient restart is possible. Typically, this is done via activation of the fuel cell system 1 for example, after the vehicle is parked 2 , or time and / or temperature controlled while the vehicle 2 is turned off. Such activation is for the user of the vehicle 2 typically unexpected because it occurs either after parking or, in particular, when the vehicle is parked 2 can be done without the user is necessarily present. This activation is also referred to as freeze-start conditioning mode. Within the scope of the present disclosure, it is intended to speak of an "unexpected activation".

In the context of such an unexpected activation, in particular the fuel cell system can now 1 be brought into a sufficiently dry state to allow a restart easily. This can be done in particular by the fact that air via a separate blower or in particular via the air conveyor 7 through the fuel cell system 2 is encouraged to dry this accordingly. Optionally, this can also be a connection line 17 with a valve device 18 be provided, which allows a supply of the conveyed air from the cathode side in the region of the anode side. In this case, then the valves 18 and the valve 15 opened accordingly to the moisture-laden air from the fuel cell system 1 dissipate.

Such an unexpected activation to transfer the fuel cell system 1 in a given state is typically always realized after one or a few predetermined processes. As a result, it is now possible in a particularly simple manner to react to the particular selected or predetermined sequence. In particular, the noise emissions of the process or the selected sequence are known, since at certain times, for example, the air conveyor 7 runs and the valves 15 . 18 be operated. It is now sufficient for each of the predetermined processes once to record the resulting noise and create a suitable anti-sound, ie a phase-shifted sound, which superimposes the resulting noise in the process to eliminate them completely or at least mitigate their intensity , This is in the vehicle 2 a data processing device 19 with a data store 20 intended. The data processing device 19 receives knowledge about the selected predefined sequence and its start time. It can then be removed from the database 20 select the appropriate phase-shifted sound and this via an indicated speaker 21 in the vehicle 2 or radiate its surroundings. In the Practice are certainly more about the vehicle 2 distributed speakers 21 more efficient, but purely exemplary here is only one of the speakers 21 exemplified. By this radiation of the phase-shifted sound through the speaker 21 become those of the fuel cell system 1 during the unexpected activation generated noise superimposed and thereby in the area outside the vehicle 2 canceled or at least reduced in their intensity. The unexpected activation of the fuel cell system 1 then leads due to the simultaneously radiated matching phase-shifted sound to no or only a very low noise emission. This represents a considerable gain in comfort for the user of the vehicle 2 represents.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 69723945 D1 [0005]
• EP 2071213 A1 [0005]
• DE 19515769 A1 [0005]

Claims (6)

Method for operating a fuel cell system ( 1 ) in a vehicle ( 2 ), which is used in operating phases in which the vehicle ( 2 ), remains unexpectedly activated for a user or is temporarily reactivated unexpectedly to maintain a predetermined state of the fuel cell system ( 1 ), characterized in that generated and emitted during the unexpected activation of the fuel cell system to the resulting noise phase-offset sound. A method according to claim 1, characterized in that the unexpected activation takes place according to a predetermined sequence, wherein the phase-shifted sound matching this sequence from a memory ( 20 ) is retrieved. A method according to claim 2, characterized in that the sequence is selected according to environmental conditions and / or operating conditions of the previous operation of a plurality of predetermined sequences. Method according to Claim 1, 2 or 3, characterized in that the phase-shifted sound is transmitted via one or preferably several inside and / or outside of the vehicle ( 2 ) arranged loudspeakers ( 21 ) is radiated. A method according to claim 2, 3 or 4, characterized in that a measurement of the noise is dispensed with. Method according to one of claims 1 to 5, characterized in that the unexpected activation in preparation for a later start of the fuel cell system ( 1 ) in the vehicle ( 2 ) and is triggered by temperature and / or time.

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