DE102014003369A1 - Vehicle with a fuel cell system - Google Patents

Abstract

The invention relates to a vehicle (1) having a fuel cell system (2), with at least one fuel cell (3) and an exhaust air line (8) through which an exhaust gas stream with exhaust gases and water, at least from a cathode region (5) of the fuel cell (3). , flows, and enters the environment through an open end (12). The vehicle according to the invention is characterized in that the open end (12) of the exhaust duct (8) terminates in an interior or exterior region of the vehicle (1), the surface of which flows around a laminar flow of air, the open end (12) of Exhaust line (8) is arranged perpendicular to the flow direction of the laminar air flow spaced from the surface.

Description

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

Generic vehicles are for example from the EP 1 658 190 B1 known. The fuel cell vehicle described herein has a fuel cell and an exhaust duct through which an exhaust gas flow with exhaust gases and water, at least from the cathode region of the fuel cell, flows and its open end terminates in the environment. In order to prevent the liquid water enters the environment and freezes there at temperatures below freezing, for example in the area of the vehicle and / or the road surface or the road surface, the EP patent describes the relatively complex release of air and water, in the these are separated first and then released into the environment. In one embodiment variant in the EP patent, the structure is realized in such a way that the exhaust gas freed from liquid water itself shields the discharged water from the ambient air so as to obtain the most uniform possible distribution over a long range of the air flow into the ambient air , This should reduce ice formation. In the second described idea, an additional airflow is trapped via a type of air trap and passed through a pipe element at least a little way through the vehicle. In the second variant, this specifically supplied air takes on the task which, in the first variant, the dried exhaust air stream held, namely the shielding of the separated liquid water from the ambient air.

The construction described here is very complex because it requires at least one water separator and in the second variant additionally a specifically provided air flow, which must be passed through the vehicle exclusively for this purpose. This creates the need for additional components to be used, which on the one hand is expensive due to the components and on the other hand is very space-consuming in the vehicle. The additional airflow provided in the second idea also increases the air resistance of the vehicle and thus adversely affects its energy requirements.

In addition, a generic vehicle from the DE 10 2012 006 132 A1 known. In this structure, it is such that an exhaust duct for discharging an exhaust gas with exhaust air and product water from the fuel cell in the flow direction before or after a vehicle radiator in an ambient air flow, which flows through the vehicle radiator ends. This has proven to be not entirely uncritical, since with a supply of the exhaust gas flow in front of the radiator, in particular at high ambient temperatures and high loads of the fuel cell system, the cooling capacity of the radiator is reduced. In these situations, there is typically no liquid water left because the fuel cell exhaust gas is already at a high temperature level. In practice, therefore, no heat can be removed by evaporation. As long as the surface of the radiator is the cooling capacity limiting factor, this is therefore a significant disadvantage in certain operating situations. In a very cold environment, it is the case that the exhaust gas flow generally always carries liquid water with it. Although this can then improve the cooling performance in which it evaporates, but it can also lead to icing of the radiator, so that it can not be completely flowed through, which in turn leads to a significant reduction in cooling capacity. The same applies to the supply of exhaust air to the radiator in very cold environment, since in these situations, despite the heated air through the radiator still icing of the components in the flow direction after the radiator can occur, which is also a disadvantage.

The object of the present invention is now to develop a generic vehicle with a fuel cell system so that in a very simple and compact design, without additional components, the above problems are reliably avoided.

According to the invention this object is achieved by a vehicle having the features in the characterizing part of claim 1. Advantageous embodiments and further developments of the vehicle according to the invention will become apparent from the dependent claims.

The idea with the vehicle according to the invention is that the open end of the exhaust air line ends in an inner or outer region of the vehicle, the surface of which flows around a laminar air flow. In particular, to optimize the aerodynamics of vehicles is increasingly taken to ensure that the surfaces of the vehicle are flowed around during the journey predominantly of a laminar flow without turbulence, since this is the reduction of air resistance beneficial. For this reason, there are often on the vehicle surface and increasingly in the underbody area of the vehicle constructive measures to realize a laminar air flow as possible along the surface of the vehicle. This laminar flow of air, which in any case is present in any case, or optionally also a laminar air flow which is constructively brought about in the vehicle according to the invention, is now realized in such a way that it discharges the air area of the vehicle flows around. The open end of the exhaust duct is also located in this area of the vehicle, which is surrounded by the laminar flow of air. In this case, the open end is arranged perpendicular to the flow direction of the laminar air flow from the surface at a distance. For this purpose, distances of the order of a few centimeters may be sufficient. The advantage that is thereby achieved lies in the fact that the laminar air flow protects the area of the vehicle from wetting with liquid water. The laminar air flow thus lies between the vehicle and the exhaust gas flow, which always contains water and water vapor. The advantage is that no additional measures are necessary due to the protective laminar airflow, as this protects even the corresponding areas of the vehicle from the water and thus reliably and reliably prevents freezing of these areas even at very low ambient temperatures.

Another advantage is that the exhaust flow and the air flow do not mix as much as with conventional structures. Ideally, there is only a slight diffusion in the boundary layer. If the ambient air is colder than the exhaust gas flow, this causes the exhaust gas flow to cool much more slowly than with conventional structures. As a result, the amount of liquid water which accumulates in the region of the surface of the vehicle is correspondingly reduced or the condensation is shifted to a flow region downstream of the moving vehicle, so that contamination of the vehicle can be largely prevented. As a result, the effect can be increased even further.

According to a very advantageous development of the vehicle according to the invention, it may further be provided that the flow-through cross-section of the open end is aligned in the flow direction of the air flow. Such an orientation of the open end of the exhaust air duct in the flow direction of the air flow ensures that the exhaust gas flow exits the exhaust air line parallel to the air flow and thus the risk of mixing between the exhaust gas flow and the laminar air flow along the area or its surface over a long Flow path can be reliably prevented.

Another very advantageous embodiment of the vehicle according to the invention provides that the laminar air flow is an ambient air flow flowing around the vehicle. Such is present anyway during movement of the vehicle and can thus be used ideally without any additional effort to safely and reliably shield the critical components and components of the vehicle from the exhaust gas flow.

In a further very favorable embodiment, it can also be provided that the laminar air flow consists wholly or partly of ambient air, which has previously flowed through a vehicle radiator. This ambient air will typically be heated by the heat intake in the vehicle radiator, at least in regular operating situations. This ensures that in the area of contact between the ambient air and the exhaust gas may possibly evaporate or evaporate in liquid form present water, so that an additional area arises in which the liquid water in the interior of the exhaust stream to the environment through the laminar air flow and between her and the heated part of the exhaust stream forming intermediate layer is shielded.

In a very favorable embodiment of the vehicle according to the invention, it can also be provided that the area in which the exhaust air line terminates is arranged on the outer skin of the vehicle. Such an area on the outer skin of the vehicle, in particular if, for aerodynamic reasons, it has already been constructed in such a way that the ambient air flows laminarly along its surface, is ideally suited for delivering the exhaust gas flow from the fuel cell system to the environment.

In a further very favorable embodiment thereof, it may be provided that the area is located on an underbody paneling. In particular, such a lying in the underbody panel area is ideally suited to deliver the exhaust gas flow from the fuel cell to the environment. The structure may be ajar, in particular in body shapes, as they are common in conventional vehicles with internal combustion engines. Instead of the previous exhaust system then the exhaust pipe can occur without major structural changes would be necessary here.

In an advantageous development of this idea, it can also be provided that the distance of the end of the exhaust air line to the region is selected so that a laminar flow is located both between the underbody lining and the exhaust gas flow and between a road surface and the exhaust gas flow. In this particularly favorable embodiment of the vehicle according to the invention, therefore, the exhaust gas stream can ideally be introduced between two laminar flows, once along the roadway surface and once along the underbody of the vehicle. This is not just a glaciation of the subsoil of the Vehicle at ambient temperatures below freezing safely and reliably prevented, but also icing of the road or the road surface can be prevented or at least minimized.

A further alternative embodiment of the vehicle according to the invention can also provide that the region in which the exhaust air line ends is located in the interior of the vehicle, and that the laminar air flow only flows outward in the direction of flow after the region. Such a construction can also be used to achieve ideal conditions, in particular to already achieve an air flow, which completely envelopes the exhaust gas flow from the fuel cells before it enters the environment, where such targeted orientation of the flow, for example by transversely or counter Wind effects that occur in the direction of travel and the like are often not quite as reliable as in a protected area in the interior of the vehicle. In addition, in this variant, in particular in combination with a use of ambient air, which has previously flowed through the vehicle radiator, a comparatively high temperature of the ambient air can be achieved in the area in which the exhaust duct ends so that in addition to the reliable sheath of the exhaust stream with laminar flowing Ambient air at the same time an additional heat input into the exhaust stream and thus evaporation or evaporation of possibly still liquid present water can be achieved.

In a very favorable development of the vehicle according to the invention, it can now further be provided that the laminar air flow does not flow into a turbulence zone of the air flowing around the vehicle after the region in which the exhaust air line ends. In many vehicles turbulence zones are unavoidable, especially in the rear of the vehicle. In such zones of turbulence, the laminar flows around the surface of the vehicle are disturbed, and the material around the vehicle, particles and the like can accumulate in these areas. Thus, especially in the field of the vast majority of vehicles increased pollution of the rear end is known by such turbulence after the vehicle and often seen in traffic. In this particularly advantageous embodiment of the vehicle according to the invention, it is now provided that the exhaust flow surrounded by the laminar air flow does not reach such an area, so that the jacket of the exhaust gas flow with ambient air is not broken and the exhaust gas flow with the moisture contained in it does not break can begin in the corresponding area of the vehicle. This can be achieved, for example, by maintaining a sufficient distance of the end of the exhaust duct to the corresponding area, or by selecting an area of the surface of the vehicle in which the passing air just does not reach the area of such a turbulence zone.

Of course, it is also conceivable to design the vehicle so that there are no turbulence zones, which is also a decisive advantage in terms of aerodynamics. An example of such a vehicle is the so-called "Bionic Car", a test vehicle of the Applicant, which is very similar in shape to the shape of a boxfish. In such a vehicle, no turbulence zones arise, in particular not behind the vehicle, so that the injection with such a construction could take place at any desired location of the surface with a corresponding distance to it.

In a further advantageous embodiment of the vehicle according to the invention, it may also be provided that the end of the exhaust duct is formed as a streamlined shaped body, which is aligned parallel to the surface of the region in which the exhaust duct ends, wherein at least one outlet opening for the exhaust gas flow in the direction of travel the rear of the vehicle is arranged. Such a streamlined body, which according to an advantageous development of this idea can extend over a certain width of the vehicle transversely to the direction of travel, is ideal for being introduced into a laminar flow along the region without permanently disturbing it. Due to the streamlined alignment, a stall and the formation of turbulence is safely and reliably prevented. At the same time by one or more outlet openings in the direction of travel of the vehicle behind, ie in the tapered region of the streamlined body in its cross section, the exhaust stream as a separate laminar flow or more parallel flows or flow threads when using multiple outlet openings very evenly between the layers of laminar flow of ambient air in the region of the area in which the exhaust duct ends, are introduced.

As already mentioned, an area around which a laminar flow of air flows around the vehicle can be created especially in order to deliver the exhaust gas flow from the fuel cell system to the environment in this area. In particular, however, an area can be used which is already present due to the aerodynamic optimization of the vehicle, so that the exhaust gas flow can be discharged to the environment very easily and efficiently without additional design effort without the risk that The vehicle thereby iced up at very low ambient temperatures.

Further advantageous embodiments of the inventive idea also result from the exemplary embodiment, which is described in more detail below with reference to the figures.

Showing:

1 a principle indicated vehicle with a fuel cell system; and

2 a schematic diagram of a vehicle in a possible embodiment according to the invention.

In the presentation of the 1 is very heavily schematized a vehicle 1 to recognize which by means of electrical power, which by a fuel cell system 2 is provided to be driven. The core of the fuel cell system 2 forms a fuel cell 3 which typically can be constructed as a stack of single cells, for example in PEM technology. This PEM fuel cell stack 3 includes an anode region 4 and a cathode region 5 , The anode area 4 is hydrogen from a here indicated pressure gas storage 6 fed, the cathode area 5 Air as an oxygen supplier. This air can, for example, via the indicated air conveyor 7 be encouraged. Via an exhaust air line 8th or a hydrogen derivative 8th' then the unconsumed substances return from the fuel cell 3 out. This will be discussed later.

The fuel cell 3 provides electrical power, which via a power electronics 9 an indicated traction motor 10 is provided over which the vehicle 1 is driven.

The fuel cell system in the vehicle 1 in the presentation of the 1 is shown very strongly schematized. However, a person skilled in such a fuel cell system is familiar. In addition to the components shown here, of course, other components such as a battery, additional conveyors, an exhaust turbine or the like may be present. All this is clear to the person skilled in the art, so that it is not shown here for the sake of simplicity.

The hydrogen discharge 8th' and the exhaust duct 8th lead in the very simplified embodiment shown here, the exhaust gases from the fuel cell 3 , Instead of this simple discharge could be especially around the anode area 4 a so-called Anodenloop be present over which unused hydrogen is recycled. Exhaust gases would then only be drained from time to time and, for example, in the exhaust air duct 8th brought in. The exhaust duct 8th leads in the embodiment shown here in the area of a 11 designated subfloor of the vehicle 1 and releases the exhaust air, which typically contains most of the fuel cell 3 product water is charged in liquid and vapor form, to the environment from. As already mentioned, exhaust gases and water can also escape from the anode area 4 via the hydrogen discharge 8th' and the exhaust duct are also discharged to the environment.

To prevent liquid water and condensing water vapor from the exhaust duct 8th in the area of the vehicle 1 remains freezing at temperatures below freezing, this is a special design for the open end 12 the exhaust duct 8th , which in the representation of the 2 is indicated in principle to recognize. In the presentation of this 2 is the vehicle 1 shown again. From the fuel cell system 2 is only the exhaust pipe 8th to recognize which is behind a front wheel in the direction of travel F. 13 of the vehicle 1 in the area of an underbody paneling 11 out of the vehicle 1 protrudes. Now it is that in this area of underbody paneling 11 , in particular the aerodynamics of the vehicle 1 to optimize the underbody paneling 11 should be designed so that a largely laminar flow of ambient air when the vehicle 1 drives, along the underbody paneling 11 occurs. This also applies to the area of underbody paneling 11 in which the exhaust duct 8th exit. This air flow around the vehicle 1 is in the representation of 2 roughly indicated by solid lines. The flow is at least between the underbody paneling 11 and a suggested road surface 14 in the front in the direction of travel F area of the vehicle 1 laminar. In this area, the exhaust duct ends 8th , by a certain distance x spaced from the surface of the underbody paneling 11 , From the direction of flow around the vehicle 1 flowing air open end 12 the exhaust duct 8th now occurs the exhaust stream from the fuel cell system 2 consisting of gaseous components as well as liquid and vaporous water. This is in the representation of 2 shown with dotted line. This exhaust gas flow is determined by the distance x of the exhaust air line 8th from the surface of the underbody panel 11 so between two indicated layers of laminar flow between the underbody cladding 11 and the road surface 14 introduced that both between the vehicle 1 and the exhaust flow as well as between the road surface 14 and the exhaust stream still each air flows. In addition, that's the end 12 the exhaust duct 8th with a formed streamlined profile, wherein the openings or outlets for the exhaust gas flow on the side facing away in the direction of travel, ie in the flow direction of the air around the vehicle 1 Rear are arranged, as it has already been mentioned. Due to the streamlined profile of the end 12 the exhaust duct 8th it is possible the exhaust flow so in the laminar flow below the vehicle 1 to bring in that their laminar alignment is not disturbed.

The exhaust gas flow from the exhaust air line 8th Then, as already mentioned, enters the environment in such a way that it is in each case surrounded by a layer of ambient air. Ideally, the exhaust gas flow mixes with the ambient air at least in the area of the vehicle 1 not overly strong. Ideally, only a small amount of diffusion occurs in the area of the boundary layer. In particular, liquid water is thereby from the vehicle floor as well as the road surface 14 kept away and can not freeze.

The outlet of the exhaust duct 8th does not necessarily take place below the vehicle, but could just as well be inside, for example in the engine compartment or a shielded area of the underbody of the vehicle or laterally and above in the front, rear or the like. In particular, care should be taken that the typically at the rear of the vehicle 1 occurring and also in 2 indicated turbulences are not included in the flow path of the exhaust stream, or at best as in the illustration of 2 can be seen in the way that the turbulence of the exhaust flow occurs a certain distance behind the vehicle, so that contamination of the rear side of the vehicle 1 with water and the risk of freezing is minimized.

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 1658190 B1 [0002]
• DE 102012006132 A1 [0004]

Claims (12)

Vehicle ( 1 ) with a fuel cell system ( 2 ), with at least one fuel cell ( 3 ) and an exhaust duct ( 8th ), through which an exhaust gas stream with exhaust gases and water, at least from a cathode region ( 5 ) of the fuel cell ( 3 ), and through an open end ( 12 ) enters the environment, characterized in that the open end ( 12 ) of the exhaust duct ( 8th ) in an interior or exterior area of the vehicle ( 1 ), whose surface is surrounded by a laminar flow of air, wherein the open end ( 12 ) of the exhaust duct ( 8th ) is arranged perpendicular to the flow direction of the laminar air flow spaced from the surface. Vehicle ( 1 ) according to claim 1, characterized in that the flow-through cross section of the open end ( 12 ) is aligned in the flow direction of the laminar air flow. Vehicle ( 1 ) according to claim 1 or 2, characterized in that the laminar air flow a the vehicle ( 1 ) is ambient air flow around. Vehicle ( 1 ) according to claim 1, 2 or 3, characterized in that the laminar air flow consists wholly or partly of ambient air, which has previously flowed through a vehicle radiator. Vehicle ( 1 ) according to one of claims 1 to 4, characterized in that the area in which the exhaust air duct ( 8th ) ends, on the outer skin of the vehicle ( 1 ) is arranged. Vehicle ( 1 ) according to one of claims 1 to 5, characterized in that the area in which the exhaust duct ( 8th ), on an underbody paneling ( 11 ) of the vehicle ( 1 ) is arranged. Vehicle ( 1 ) according to claim 6, characterized in that a distance (x) of the end ( 12 ) of the exhaust duct ( 8th ) is selected to the surface of the area so that a laminar air flow both between the underbody cladding ( 11 ) and the exhaust gas flow as well as between a road surface ( 14 ) and the exhaust stream is located. Vehicle ( 1 ) according to one of claims 1 to 7, characterized in that the area in which the exhaust duct ( 8th ), is located inside the vehicle, and the laminar air flow flows in the flow direction after the area to the outside. Vehicle ( 1 ) according to one of claims 1 to 8, characterized in that the laminar flow to the region in which the exhaust duct ( 8th ), does not flow into a turbulence zone of the air flowing around the vehicle. Vehicle ( 1 ) according to one of claims 1 to 9, characterized in that the open end ( 12 ) of the exhaust duct ( 8th ) as a streamlined shaped body ( 15 ) is formed, which parallel to the surface of the area in which the exhaust duct ( 8th ), wherein at least one outlet opening for the exhaust gas flow in the direction of travel (F) of the vehicle ( 1 ) is arranged behind. Vehicle ( 1 ) according to claim 10, characterized in that the shaped body ( 15 ) transversely to the direction of travel (F) of the vehicle ( 1 ) over part of the width of the vehicle ( 1 ), and has a plurality of outlet openings for the exhaust gas flow. Vehicle ( 1 ) according to any one of claims 1 to 11, characterized in that the area in which the exhaust duct ( 8th ) ends, is an area which is surrounded by the laminar air anyway due to the aerodynamic optimization.

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