DE102016009931A1 - Method for operating a vehicle - Google Patents

Abstract

The invention relates to a method for operating a vehicle (1) whose electric drive power comes from a fuel cell (7) and an electrical energy storage device (6), wherein the vehicle (1) has a navigation system (18) and a control unit which is dependent the state of charge of the electrical energy storage device (6) and the air pollution the fuel cell (7) operates in a stop mode or a deactivated mode, characterized in that the degree of air pollution on the basis of the navigation system (18) known position of the vehicle (1) and is determined from average pollution levels stored for that position.

Description

The invention relates to a method for operating a vehicle whose drive power originates from a fuel cell and an electrical energy store, according to the preamble of claim 1.

Such vehicles are colloquially referred to as fuel cell vehicles. Typically, the fuel cell provides most of the necessary electrical drive power. In addition, an electrical energy storage device, such as a battery, a high power capacitor, or a combination thereof is provided in the vehicle to latch energy recuperated during deceleration. As a result, power peaks can be absorbed, since the fuel cell typically can not react as dynamically as an electrical energy storage device. Depending on the size of the electrical energy storage device and depending on whether it is loaded exclusively in the vehicle or via a charging station from outside the vehicle (plug-in technology), even larger routes can be driven purely electrically with stored energy, especially if low speeds are sufficient, for example in city traffic.

In practice, the fuel cell is typically operated with ambient air of the vehicle. This air provides the oxygen necessary for the fuel cell. Now it is so that the air can have pollutants, for example sulfur compounds, nitrogen compounds such as nitrogen oxides, ammonia or volatile organic compounds, the so-called VOCs. In practice, such pollutants in the air reduce the performance of the fuel cell. Sulfur compounds, for example, react irreversibly with the catalysts in the cathode region of the fuel cell and cause a considerable degradation of the fuel cell. Nitrogen compounds also react strongly, but for the most part are reversibly removable again via a suitable process sequence. The volatile organic compounds are predominantly still under investigation, although previous findings, also due to the comprehensive designation of this pollutant group, indicate both strong and slight as well as reversible to irreversible degradation.

With regard to the load conditions of the fuel cell, according to current investigations, it is most likely to depend on the amount of pollutant in the amount of air required by the fuel cell. Accordingly, at full load operation of the fuel cell and a correspondingly higher amount of air required higher impairments due to the higher amount of pollutants supplied are to be expected. The electric potential itself seems to have a rather negligible influence on the degradation.

The problem described above has been described, for example, in US Pat EP 1 233 879 B1 recognized and thematized. There it is proposed that the air pollution or the toxic substances in the air are detected by a sensor, wherein when the state of charge of the battery allows it, the fuel cell changes to a stop mode and the operation of the vehicle temporarily exclusively from the battery or the electrical energy storage device takes place. The disadvantage here is that by the described method only short distances can be covered in pure battery operation, in particular a driving distance, which is proportional to the state of charge of the battery at the beginning of the shutdown of the fuel cell. In addition, the measurement via a sensor is relatively complex, since various compounds are present in air pollutants, which all have more or less much influence on the degradation of the fuel cell. Measuring all of these would be costly. To pick out a single pollutant as a lead substance for air pollution is difficult because air pollution can vary significantly depending on local conditions. Easily measured pollutants, such as carbon monoxide - as mentioned in the above EP 1 233 879 B1 - are generally not suitable as a conductive substance to reliably detect air pollution in general.

Furthermore, it is known from the general state of the art that in order to control the state of charge of a battery in a hybrid vehicle control system, it automatically learns routes and optimizes the state of charge in accordance with this route. Purely by way of example is in this context on the DE 10 2011 018 182 A1 directed. In addition, it is known via a satellite-based navigation system, z. B. via GPS to capture planned routes and so for example to empty the battery in a hill climb, as with a subsequent downhill and the ability to recharge the battery via recuperation, is expected.

The object of the present invention is now to improve the method described in the generic state of the art in order to further improve this and to further minimize contamination of the fuel cell with pollutants.

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

In the method according to the invention, it is provided that the degree of air pollution is determined from the position of the vehicle known from the navigation system and from the mean contamination stored for this position. The vehicle thus has a navigation system in addition to the components in the generic vehicle. The navigation system makes polluting much easier than using an appropriate sensor. It is sufficient if there are cards with medium pollution. These can be stored, for example, in the vehicle, or can be stored in a database and forwarded via telecommunications means to the vehicle. In addition to empirically recorded data, the measured values from current measuring stations can also be processed there, so that, for example, the current soiling situation for relevant points, for example in the area of heavily used motorway junctions, city highways or the like, always exists in a database. This makes it very easy and efficient to determine the degree of contamination from the position of the vehicle and this stored or stored data. Comparable as in the prior art, it can then be decided whether the fuel cell is operated in the stop mode or a deactivated mode, depending on the state of charge and the air pollution.

According to an advantageous development of the idea, it may further be provided that the vehicle, when approaching a zone with increased air pollution according to the navigation system, is operated with a corresponding excess power of the fuel cell in order to prevent the electrical energy store from reaching the zone with increased air pollution charge as much as possible. When entering the zone of increased air pollution, the fuel cell then switches to the stop mode and the drive power is operated from the previously fully pre-charged battery, which is ideally pre-charged for entry into such zone of increased air pollution.

The stop mode for the fuel cell is a mode in which it remains in a standby mode and can be restarted very quickly. Such a behavior is known to those skilled in the field of start / stop systems in fuel cell vehicles. For this purpose, the European patent EP 2 462 467 B1 referred to the applicant. In the context of this European patent, among other things, a so-called refresh is described, namely in the cited patent specification, in particular in section [0028]. In certain circumstances, such a refresh may make sense in order to prevent voltages in the area of the fuel cell from forming during the stop mode, which permanently damage the fuel cell. In the case of operation of the fuel cell vehicle in a zone of increased air pollution, however, it may now be disadvantageous to perform such a refresh, because then the polluted air would get into the fuel cell. According to an advantageous development of the method according to the invention, it is therefore provided that a refresh of the fuel cell is suppressed as long as the vehicle is in the zone of increased air pollution.

According to a further very favorable embodiment of this idea, it can also be provided that, if there is a risk that unfavorable voltages occur in the fuel cell without refresh for the service life, a refresh is carried out, preferably in a region which is less heavily polluted by the air pollution the zone with increased air pollution, if it is not possible to cross the charged zone from the battery alone. However, if it is possible to cross the zone from the battery alone, then the fuel cell is moved from the stop mode to a parked mode, so turned it off completely. Although this has the disadvantage of a certain necessary restart time after leaving the zone of increased air pollution, but protects the fuel cell in terms of degradation by air pollutants.

In order to make optimum use of the electrical energy in the electrical energy store, it is provided that the fuel cell is started from a predetermined minimum state of charge of the electrical energy store, specifically only if no charging station is available at the destination according to the navigation system. Before the vehicle stops, so the fuel cell is started and it is accepted that it is polluted by the air pollution. The operation of the fuel cell in the zone of increased air pollution takes place only to the extent necessary to charge the electrical energy storage to the extent that the zone can be traversed. The fuel cell is thus charged as little as possible with the pollutants. If, on the other hand, it is known that a charging station is available at the destination in accordance with the navigation system, and if the vehicle is designed so that it can be recharged externally, ie if it is a plug-in vehicle, then the electrical energy store is limited to one Charge state of nearly zero empty driven, since there is to be expected a charge. Such a charging station, for example, at a public parking, but especially at a parking lot at the user of the vehicle at home, or at his workplace be available, which is stored in the navigation system.

Whenever the power from the electrical energy store is insufficient to operate the vehicle or when the driver requests a higher power, for example by manually inputting this or by depressing a kickdown switch on the accelerator pedal, the fuel cell is started the desired power supply for the driver of the vehicle takes precedence over a protection of the fuel cell.

However, in the method, it is possible to largely keep the pollutants away from the fuel cell, so that the deterioration of the fuel cell performance due to the air pollutants may be delayed, so that the fuel cell has a longer life before its performance deteriorates due to the absorbed air pollutants.

Further advantageous embodiments of the method will become apparent from the embodiment, which is described below with reference to the figures.

Showing:

1 a schematically indicated vehicle in a possible embodiment according to the invention;

2 a graph indicating the relative contribution of fuel cell activity, battery state of charge, and degree of soiling over a fictitious path; and

3 a flowchart for a possible embodiment of a method according to the invention.

In the presentation of the 1 is one with 1 designated vehicle indicated in principle. The vehicle 1 is powered by an electric drive motor 2 which is driven by a common axis 4 connected and driven wheels 3 in the highly schematic embodiment shown here drives. The electrical power for the electric drive motor 2 is about a power electronics 5 provided and prepared. In conjunction with the power electronics 5 there is an electrical energy storage 6 For example, a battery or a combination of battery and high performance capacitor. Equally well would be a bank of high-performance capacitors alone conceivable, in practice, in particular a combination of the two components has proven to save on the high-performance capacitors briefly high power and provide and store them on the battery long term. In addition to the electrical energy storage device 6 delivers one with 7 designated fuel cell electrical drive power for the vehicle 1 , The electrical energy storage device 6 can in case of slowing down the vehicle 1 by recuperation, ie by the generator operation of the electric drive motor 2 , to be charged. Otherwise, that of the fuel cell 7 generated to drive the traction motor 2 unnecessary part of the electrical power in the electrical energy storage device 6 be stored. The fuel cell 7 - For example, a PEM fuel cell - is known from the general state of the art. It has a cathode compartment 8th and an anode room 9 on. The cathode compartment 8th Air is transferred via an air conveyor 10 provided, which is designed for example as a flow compressor, and which of an electric drive motor 11 via the power electronics 5 is driven. Via a suction opening 12 , in the area of which an air filter, not shown here, is located, the intake air flows through an air supply line 13 in the area of the fuel cell. Unused exhaust air leaves the vehicle via the exhaust air line 14 , On the anode side, the fuel cell 7 from a compressed gas storage 15 via a pressure regulating and dosing unit 16 supplied with hydrogen. Unnecessary hydrogen passes through an exhaust pipe 17 from the system. Here further structures, such as a recirculation of hydrogen and the like would be conceivable. This is familiar to the person skilled in the art for fuel cell systems, so that a detailed illustration can be dispensed with. The same applies to the cathode side for elements such as an exhaust air turbine, a humidifier, a charge air cooler and the like.

In the embodiment of the vehicle shown in FIG 1 it should be a plug-in vehicle 1 act. It also has a charger 21 , which has an indicated cable 22 with a charging station 23 can be connected. Such a charging station 23 For example, in a garage of the user of the vehicle 1 he is the vehicle 1 for example, in the parked state each can reload. In addition, the use of other charging stations, as can be found, for example, in public parking areas, in parking lots for company employees, etc., conceivable.

The vehicle 1 also has a known navigation system 18 , which, for example, via an indicated satellite receiver 19 via GPS or similar technologies can determine the location of the vehicle. The navigation system 18 also has one with 20 designated telecommunication device, so as to obtain data, for example from a current database, about certain occurrences and events in the area of the position of the vehicle 1 to be able to call. The source can here, for example, an Internet connection or a data connection to appropriate databases, for example, the manufacturer of the vehicle 1 , be.

In practice, it is now so that the air passing through the suction port 12 and the air conveyor 10 into the fuel cell 7 or their cathode compartment 8th passes, is typically contaminated with pollutants. The pollutants in the air are usually due to external factors, for example in areas with frequent traffic jams, tunnels in which the pollutants can not deduct so well, multi-storey car parks, nearby farms, which for an increased proportion of volatile organic compounds in to take care of the air, or the like. Many of these pollutants react reversibly or irreversibly with the catalysts in the cathode region 8th of the fuel cell system and thus affect the performance of the fuel cell 7 , The goal is therefore a burden on the fuel cell 7 with such pollutants to reduce accordingly by the fuel cell 7 In areas with particularly polluted air is not or not so often operated.

For this purpose, it is now provided that these areas with more or less heavily polluted air, for example, according to a classification into several pollution categories, in a database for the navigation system 18 available, or directly in the navigation system 18 in which maps are stored. Is now from the programming of the navigation system 18 clear that the vehicle 1 Such a zone of increased air pollution, which is also referred to below as the loaded zone approaches, then the state of charge of the electrical energy storage 6 tested and operation of the fuel cell 7 with appropriate excess power is initiated to the electrical energy storage 6 Fully charged as far as possible until entry into the loaded zone, so that it is possible to travel as far as possible from the electrical energy storage device in the loaded zone with electrical power. The state of charge of the electrical energy storage 6 Thus, by prediction of a loaded zone, such as a city highway, a tunnel, a currently occurring traffic jam, a parking garage or the like, adapted in a forward-looking manner. Ideally, until the entry into the loaded zone of the electrical energy storage 6 fully charged or charged so far that the loaded zone can be passed through completely electrically if possible. With the entry into the loaded zone or ideally just before the vehicle 1 enters the loaded zone, then the fuel cell 7 ideally brought into a standby mode, for example a so-called stop mode, comparable to the stop mode in a start / stop system.

In the presentation of the 2 is such an operation exemplified. On the Y-axis the respective relative proportion is shown, on the X-axis the distance. With I designated curve shows the degree of pollution of the air with II designated curve the state of charge of the electrical energy storage 6 and those with III designated curve the activity of the fuel cell 7 , In the first section A, which indicates the normal operation, the state of charge of the electrical energy storage varies 6 and the activity of the fuel cell approximately evenly. Air pollution I is correspondingly low. About the navigation system 18 It is now known that the route leads in the direction of a loaded zone C, which is shown in the right-most section of the route axis. This drive towards the polluted zone C is in 2 labeled B. The fuel cell 7 is thus operated or available opportunities for recuperation are used so that the state of charge II of the electrical energy storage 6 increases, ideally to a maximum state of charge at the transition from the passage B in the loaded zone C. In this point then becomes the activity III the fuel cell 7 reduces and decreases to zero, so that in the loaded zone C, the operation exclusively with electrical energy from the electric energy storage 6 he follows. At the same time, in the area of the polluted zone C, the air pollution or the degree increases I corresponding to the air pollution. At the end of the route C the state of charge has dropped significantly. If this is followed by a normal operation or an operation in a route B, then the state of charge can be increased, the fuel cell activity increases and the whole process can start anew.

To load the fuel cell 7 completely eliminating pollutants, it starts changing the fuel cell 7 in the stop mode and the operation with electrical energy from the electrical energy storage 6 ideally by a small distance b before in the loaded zone C begins, as from the representation of 2 can be seen.

In such a stop-mode, as he for example from his own EP Patent 2 462 647 B1 is known, typically after a certain time or when the voltages in the fuel cell 7 for the lifetime of the fuel cell 7 develop unfavorably, a so-called refresh performed. This is in detail for example in section [0028] of EP patents described. In such a case, air would re-enter the fuel cell 7 which is not desired due to the expected pollution and contamination of the air in the loaded zone. The refresh is thus suppressed in the loaded zone to the pollutant load of the fuel cell 7 to minimize. It is to be expected that due to the suppressed refresh voltages occur, which for the life of the fuel cell 7 According to the section of the EP patent described above, then the fuel cell becomes 7 completely switched off, if it can be assumed that the state of charge of the electrical energy storage 6 sufficient to pass the loaded zone. If this is not the case, then, with the energy from the electrical energy store, it is possible, if possible, to travel primarily in a section of the loaded zone in which it has the highest load. In a less heavily loaded section of the loaded zone, operation of the fuel cell can then be carried out if the refresh is unavoidable. The highest pollution levels are typically expected for tunnels. Due to the length, it can be assumed that these are fully charged electrical energy storage 6 Normally passable without the fuel cell 7 the fuel cell system is needed.

A corresponding flow chart, which shows the complex possible procedure, can be found in 3 , Here is also considered that the vehicle 1 via the optional plug-in function, ie the charger 21 to allow a charging connection with a charging station 23 features. If so, then if at the destination of the navigation system 18 programmed way a charging station 23 is expected, the fuel cell 7 switch to stop mode or switch it off completely, if it can be seen that the remaining charge state in the electrical energy storage 6 is sufficient to find the way to the charging station 23 to cover.

The method can be used in particular in inner cities, since usually only low speeds are necessary, which easily with the energy from the electrical energy storage device 6 can be achieved. Typically, the pollutant values are also correspondingly high there, so that the ideal synergies for the process according to the invention result here.

If the fuel cell still needs to be turned on, because the state of charge of the electrical energy storage device 6 insufficient or because the driver switching on the fuel cell 7 For example, requesting a kick-down or a manual start of the fuel cell, then this should ideally be operated with not too high voltage levels to keep the load low. If the measurement technology of an environment detection of the vehicle, for example sensors, cameras, radar or the like makes it possible, it can also be implemented that in the area of known pollutant emitting objects, for example on mountain driving trucks, in the area of gas stations or farms, the fuel cell 7 temporarily put into the stop mode, if this is possible without limiting the speed of the ride. This allows concentration peaks of pollutants, which in the fuel cell 7 can penetrate, ideally avoid. Because vehicles 1 In particular, if they increasingly drive with their own hands, have the sensors mentioned anyway, this can be done very easily without any additional effort by adapting the software.

Ultimately, the process leads to a longer life of the fuel cell 7 , Thus, the effects mentioned have a positive effect on the TCO (Total Cost of Ownership) for the owner of the vehicle. Maintenance intervals can be extended and the customer less often to the service or the vehicle 1 has less life. This is a significant advantage, both for the private user, as well as for use within a vehicle fleet.

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

• EP 1233879 B1 [0005, 0005]
• DE 102011018182 A1 [0006]
• EP 2462467 B1 [0011]
• EP 2462647 B1 [0028]

Claims (9)

Method for operating a vehicle ( 1 ) whose electrical drive power with a fuel cell ( 7 ) and an electrical energy storage device ( 6 ), where the vehicle ( 1 ) via a navigation system ( 18 ) and a control device which, depending on the state of charge of the electrical energy storage device ( 6 ) and air pollution the fuel cell ( 7 ) operates in a stop mode or a deactivated mode, characterized in that the degree of air pollution is determined on the basis of the navigation system ( 18 ) known position of the vehicle ( 1 ) and from average pollution levels stored for this position. Method according to claim 1, characterized in that the average pollution data per position of the vehicle ( 1 ) in the vehicle ( 1 ) are stored. A method according to claim 1 or 2, characterized in that the stored data of the average degree of contamination are stored in a database or updated via a database, wherein the data via a telecommunication device ( 20 ) to the vehicle ( 1 ). Method according to claim 1, 2 or 3, characterized in that when the vehicle ( 1 ) according to the navigation system ( 18 ) approaches a zone (C) with increased air pollution, the electrical energy storage device ( 6 ) is charged as far as possible, the fuel cell being (C) of increased air pollution entering the zone (C) ( 7 ) is brought into a stop mode or switched off, and the electric drive power from the electrical energy storage device ( 6 ) is delivered. A method according to claim 4, characterized in that a refresh of the fuel cell in the stop mode is suppressed as long as the vehicle is in the zone (C) of increased air pollution. A method according to claim 5, characterized in that if there is a risk that without refresh for the life of the fuel cell ( 7 ) unfavorable voltages in the fuel cell ( 7 ), a refresh is carried out, preferably in an area of the zone (C) of increased air pollution which is less heavily polluted by air pollution, whenever no crossing of the zone (C) of increased air pollution from the electrical energy store ( 6 ) alone, otherwise the fuel cell ( 7 ) is brought from the stop mode to the deactivated mode. Method according to one of the preceding claims, characterized in that starting the fuel cell ( 7 ) from a predetermined minimum state of charge of the electrical energy storage device ( 6 ), if at the destination according to the navigation system ( 18 ) no charging station ( 23 ) is available, provided that the vehicle ( 1 ) as a plug-in vehicle ( 1 ) is trained. Method according to one of the preceding claims, characterized in that an operation of the fuel cell ( 7 ) in the zone (C) increased air pollution only as far as necessary to the electrical energy storage ( 6 ) Reload to the extent that the zone (C) of increased air pollution can be traversed takes place. Method according to one of the preceding claims, characterized in that starting the fuel cell ( 7 ) at the request of the driver of the vehicle ( 1 ) can be enforced in any case.

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