DE102017221831A1 - Measures for water passage with a fuel cell powered motor vehicle - Google Patents

Abstract

The technology disclosed herein relates to a motor vehicle having at least one energy converter 300. The motor vehicle comprises i) at least one exhaust path 416; and ii) at least one means 600 for closing off the exhaust path 416. The means 600 comprises a float 610, wherein the float 610 is arranged to cause the closure of the exhaust path 416 if a limit liquid level is reached.

Description

The disclosed technology relates to a fuel cell powered automobile. Such motor vehicles are known from the prior art. Depending on the vehicle architecture, in the case of a water passage of a fuel cell-powered motor vehicle, the case may occur that water from the vehicle surroundings invades the exhaust gas path in the opposite direction to the flow direction of the exhaust gas. This may be particularly relevant if components of a fuel cell system are installed below the maximum permissible water level line or maximum permissible wading depth (also referred to as wait line). These components must be protected from the environment surrounding the vehicle by the exhaust gas path.

It is a preferred object of the technology disclosed herein to reduce or eliminate at least one disadvantage of a previously known solution or to suggest an alternative solution. In particular, it is a preferred object of the technology disclosed herein to protect components directly or indirectly fluidly connected to the exhaust path from water intruding from the vehicle environment during a wade, or at least to reduce its effects. Other preferred objects may result from the beneficial effects of the technology disclosed herein. The object (s) is / are solved by the subject matter of the independent claims. The dependent claims are preferred embodiments.

The technology disclosed herein relates to a motor vehicle having at least one energy converter. The at least one energy converter is set up to convert the chemical energy of the fuel into other forms of energy, for example electrical energy and / or kinetic energy. The energy converter can be, for example, an internal combustion engine or a fuel cell system / fuel cell stack with at least one fuel cell. The energy converter is fluidly connected to at least one exhaust path. Through the exhaust path, the exhaust gas is discharged from the energy converter into the vehicle environment.

The technology disclosed herein preferably relates to a fuel cell system having at least one fuel cell as energy converter. The fuel cell system is intended, for example, for mobile applications such as motor vehicles (for example passenger cars, motorcycles, commercial vehicles), in particular for providing the energy for at least one drive machine for locomotion of the motor vehicle. In its simplest form, a fuel cell is an electrochemical energy converter that converts fuel (e.g., hydrogen) and oxidants (e.g., air, oxygen, and peroxides) into reaction products, thereby producing electricity and heat. A fuel cell system comprises, in addition to the at least one fuel cell, peripheral system components (BOP components) which can be used during operation of the at least one fuel cell. As a rule, several fuel cells are combined to form a fuel cell stack or stack.

The fuel cell system includes i.d.R. an anode subsystem, which is formed by the fuel-carrying components of the fuel cell system. The main task of the Anodensubsystems is the introduction and distribution of fuel to the electrochemically active surfaces of the anode compartment and the removal of anode exhaust gas.

The fuel cell system includes a cathode subsystem. The cathode subsystem is formed from the oxidant-carrying components. A cathode subsystem may comprise at least one turbomachine for conveying the oxidant (i.d.R., air), at least one cathode inlet path leading to the cathode inlet, at least one cathode exhaust path leading away from the cathode outlet, a cathode compartment in the fuel cell stack, and further elements. The main task of the cathode subsystem is the introduction and distribution of oxidant to the electrochemically active surfaces of the cathode compartment and the removal of unconsumed oxidant.

The turbomachine is in particular designed to convey air to an energy converter, in particular to at least one fuel cell. The turbomachine may in particular be an air-bearing turbocompressor, turbocompressor or centrifugal compressor. Preferably, the compressor has a working speed range from about 15,000 rpm to about 170,000 rpm, and more preferably from about 20,000 rpm to about 130,000 rpm. The turbomachine is in particular configured to supply air to at least one energy converter of a motor vehicle via an energy converter inflow path. The turbomachine preferably comprises a compressor unit with at least one compressor wheel and / or a turbine unit with at least one turbine wheel.

The technology disclosed herein includes at least one device for closing the exhaust path. The device is set up to close the exhaust path of the motor vehicle in such a way that water entering the exhaust path from the vehicle surroundings can not penetrate further into the exhaust path upstream of the exhaust gas flow direction. The device is expediently arranged downstream (relative to the exhaust gas flow direction) of the components to be protected. The device can be arranged in particular in the exhaust path, in particular also spaced from the outlet of the exhaust path.

The device may in particular comprise at least one float. The float can cause the closure of the exhaust path to protect against penetrating from the vehicle environment in the exhaust path liquid, if a Grenzflüssigkeitspegel, in particular in the exhaust path, is reached. Floats and their operating principle as such are known.

The liquid level or the water level or the liquid level or the liquid level (the terms are understood in the context of the technology disclosed here as synonyms) indicates the height of the liquid surface (eg the water to be traversed) relative to the road, the roadway also includes the floor of a Abstellortes with. The limit liquid level is a limit value for the liquid level. The limit liquid level is chosen in particular so that damage to components to be protected can be reliably ruled out by penetrating water before reaching the limit liquid level.

Preferably, the float may be coupled via a mechanical coupling with a closure of the device. The shutter may be configured to close off the exhaust path if a limit fluid level is reached. In other words, the float is thus set up to actuate the closure of the device mechanically, without requiring electrical actuation for this purpose. For example, the mechanical coupling may be a control linkage or a kinematics. An advantage of such a passive solution is that it is particularly fail-safe. The kinematic design of the mechanical coupling, by means of which the closure is closed by the float due to the change in position caused by the change of the liquid level, is known to the person skilled in the art.

Particularly preferably, the inlet from an inflow path for oxidant / air to the at least one energy converter in the installed position in the motor vehicle is further from the roadway than the outlet from the exhaust path. It is thus advantageously ensured that no liquid is sucked in during a wading movement.

Alternatively or additionally, the technology disclosed herein relates to a motor vehicle having the energy converter disclosed herein and having at least one exhaust path, wherein at least a portion of the at least one exhaust path in the installed position is spaced further from the roadway than a vehicle component fluidly coupled to the exhaust path, and which is to be protected from penetrating into the exhaust path water. In the case of a fuel cell system, the components to be protected are i.d.R. Components of the cathode subsystem, in particular the turbine of the turbomachine, the fuel cell stack, the humidifier and / or the heat exchanger. In particular, the at least one subregion of the type is formed and arranged in the motor vehicle such that the at least one subregion is arranged in the installed position above the wading line. In a preferred embodiment, this at least one sub-area is designed similar to an inverted siphon. If the motor vehicle now travels through a body of water which does not exceed the permissible wading depth, then due to the at least one subarea above the wading line no water flowing backwards into the cathode subsystem through the outlet of the exhaust path can cross this subarea and the components disposed upstream of the subarea are present Protected penetrating dirty water.

In a preferred embodiment, a drainage line is designed as a bypass line to the partial area, in particular such that product water condensed through the drainage line can be discharged from the exhaust gas path. For this purpose, the drainage line expediently branches off the exhaust gas path upstream of the at least one subarea and opens downstream of the at least one subarea. The drainage line is in particular configured to discharge product water accumulated upstream of the at least one partial area into a region downstream of the at least one partial area.

Particularly preferably, the drainage line is fluidly connected in fluid communication with a product water collecting area formed in the exhaust gas path. Advantageously, furthermore, the drainage line can open into a jet pump which is set up to draw in liquid from the drainage line. Jet pumps or suction jet pump as such are known. They are designed as venturi nozzle. A jet pump generally comprises a pipe section with a cross-sectional constriction, for example by two oppositely directed cones, which are united at the point of their smallest diameter. At this narrowed point or adjacent thereto ends a delivery channel, here the drainage line. The end of the conveying channel is flowed around by the medium flowing through the pipe section (here the exhaust gas), which acts as a propellant. Such a jet pump advantageously makes it possible to utilize the flow energy contained in the blowing agent for conveying the conveying medium out of the conveying channel. Such a jet pump is comparatively cheap, failsafe and requires comparatively little space. Alternatively or additionally, the delivery channel of the jet pump be fluidly connected to a product water collecting area of a noise damper of the exhaust path, so the product water can be discharged through the passively operating jet pump.

In other words, the technology disclosed herein proposes measures to protect the components of a fuel cell system from ingress of water.

According to the technology disclosed herein, the water level can be detected by a float. In one embodiment, the float itself is a mechanical actuator that closes the exhaust path directly or indirectly. Alternatively or additionally, the float can be equipped with a sensor or form a sensor, wherein the sensor can generate a signal which is indicative of the water level. Alternatively or additionally, a fill level sensor or water level sensor can be provided which detects the water level. Such level sensors are known in the art.

The float or the water level sensor can be arranged, for example, i) in the exhaust path itself, in particular in the silencer from the exhaust path or in a vertical pipe section downstream of a component to be protected; and / or ii) in a liquid-permeable housing on the vehicle underbody.

The measure for protecting the components from water ingress can be a passive measure in particular. For example, a reverse siphon geometry may be provided in the exhaust path for this purpose. Alternatively or additionally, at least one backflow valve may be provided in the exhaust gas path, which allows outflow of exhaust gas in an outflow direction, and which prevents ingress of water from the vehicle environment against the outflow direction of the exhaust gas. The return flow valve may preferably have hydrophobically coated valve bearing surfaces. Such backflow valves are less likely to fail in winter due to frost. Alternatively or additionally, a float-operated flap may be provided, which is purely mechanically actuated by penetrating liquid from the vehicle environment. Furthermore, alternatively or additionally, it can be provided that the outlet from the exhaust gas path into the environment is arranged substantially in the direction of the vehicle vertical axis, that is to say perpendicular to the roadway. If the exhaust path exhaust pipe is formed, the dirty water can not penetrate or worse in the exhaust path.

• - dass die Drehzahl der Strömungsmaschine erhöht wird;
• - dass eine Energiewandler-Bypassleitung, die stromauf vom Energiewandler abgezweigt und stromab vom Energiewandler mündet, geöffnet bzw. weiter geöffnet wird;
• - das Energiewandler-Absperrventile geschlossen, falls das Eindringen von Wasser in den Energiewandler ansonsten unmittelbar bevorstehen würde;
• - dass das kathodenseitige Stapel-Absperrventil stromab vom Brennstoffzellenstapel zur Reduzierung der Wassereintrittswahrscheinlichkeit stärker verschlossen wird als vor Erreichen des Grenzflüssigkeitspegels; und/oder
• - dass das stöchiometrische Verhältnis λ des Oxidationsmittels erhöht wird.

Alternatively or additionally, the motor vehicle disclosed here may include active measures that prevent or at least reduce the ingress of water from the environment. According to the technology disclosed herein, a motor vehicle or a method may be provided, according to which the mass flow rate of gas, in particular exhaust gas, through the exhaust path is increased if the limit fluid level has been reached. For example, when the limit liquid level is reached, it can be provided:

• - That the speed of the turbomachine is increased;
• - That an energy converter bypass line, which branches off upstream of the energy converter and opens downstream of the energy converter opens or is opened further;
• - the energy converter shut-off valves are closed, if the penetration of water into the energy converter would otherwise be imminent;
• - That the cathode-side stack shut-off valve downstream of the fuel cell stack to reduce the probability of water ingress is more closed than before reaching the Grenzflüssigkeitspegels; and or
• - That the stoichiometric ratio λ of the oxidizing agent is increased.

The stoichiometric ratio λ of the oxidizing agent indicates by what factor more oxidizing agent is provided than is actually necessary for the reaction at the cathode. If air is used as the oxidizing agent, this can also be referred to as the air ratio λ or as the air ratio λ. The air ratio λ sets the actual air mass mL-tats available for the electrochemical reaction in the at least one fuel cell in relation to the at least necessary stoichiometric air mass mL-st, which is required for a complete electrochemical reaction in the at least one fuel cell. It therefore applies: $$\mathrm{\lambda \; =}\frac{\text{mL}-\text{tats}}{\text{mL}-\text{st}}$$

At the same time, a combination of active measures and passive measures is conceivable. More preferably, the technology disclosed herein may include a method whereby a means for closing the exhaust path partially occludes the exhaust path while increasing the mass flow rate of gas through the exhaust path. In the semi-closed cross-section of the device thus sets at a lower mass flow rate, a higher gas velocity, which reduces the penetration probability of dirty water.

• 1 eine schematische Ansicht eines Brennstoffzellensystems;
• 2 eine schematische Ansicht einer typischen Einbausituation in einem Kraftfahrzeug;
• 3 eine weitere schematische Ansicht einer typischen Einbausituation in einem Kraftfahrzeug; und
• 4 einen schematischen Ausschnitt aus einem Abgaspfad 415.

Advantageously, the risk of damage from below the waiting line mounted and therefore to be protected components, in particular a fuel cell system, and particularly preferably a turbine of a turbomachine, can be reduced. The measures proposed here can be implemented without too great negative effects on production costs or space requirement. The technology disclosed herein will now be explained with reference to the figures. Show it:

• 1 a schematic view of a fuel cell system;
• 2 a schematic view of a typical installation situation in a motor vehicle;
• 3 a further schematic view of a typical installation situation in a motor vehicle; and
• 4 a schematic section of an exhaust path 415 ,

The 1 shows an energy converter 300 that's here as a fuel cell stack 300 is formed with a plurality of fuel cells. The fuel cell stack 300 is schematically divided into a cathode K and an anode A , The structure of such a fuel cell stack 300 is familiar to the expert. The anode subsystem includes a fuel source H2 that provides fuel, eg hydrogen. Through the pressure reducer 211 the pressure in the anode inflow path becomes 215 reduced before the fuel into the anode A from the fuel cell stack 300 arrives. After the electrochemical reaction in the fuel cell stack 300 the anode exhaust gas leaves the fuel cell stack 300 and at least partially via the recirculation conveyor 236 recirculated. In the water separator 232 Water is separated from the anode exhaust gas. Through the anode flush valve 238 Water and purge gas from the anode subsystem into the anode purge line 239 drained.

The turbomachine 500 sucks air O2 and compacts them. The compressed air is in the intercooler 420 cooled and possibly further downstream in the cathode inflow path 415 (= Energy converter inflow path) through a humidifier 430 moistened. Subsequently, the humidified air enters the cathode K of the fuel cell stack 300 where the electrochemical reaction with the fuel of the anode A takes place.

Also shown are cathode side stack shutoff valves 470 . 480 that can be provided as well as the bypass 460 , But this does not have to be this way. After the electrochemical reaction in the fuel cell stack 300 the cathode exhaust gas passes through the cathode exhaust path 416 in the nearby areas. The cathode exhaust gas can also be added to the anode exhaust gas. Within the scope of the technology disclosed here, the term exhaust gas should not be restricted further.

The turbomachine shown here 500 includes a compressor unit 510 indicating the cathode inflow path 415 with trains. Furthermore, the turbomachine shown here comprises 500 a turbine unit 520 passing the (cathodes) exhaust path 416 with trains. The compressor unit 510 , the turbine unit 520 and the electric drive 530 are here over a wave 540 rigidly connected.

In the 2 a typical installation situation of a propulsion system (eg, combustion engine, fuel cell system) is shown in which the technology disclosed herein may be used. Above the wading line AA here is the fuel cell stack 300 arranged. The air O2 is here via the inflow path 416 sucked, whose inlet above the wading line AA lies. Thus, no dirty water is sucked from the environment, provided that the liquid level is the wading line AA does not exceed. The turbomachine 500 is here below the wading line 500 arranged. The compressor 510 the turbomachine 500 here compresses the sucked air. In the energy converter 300 the electrochemical reaction takes place. Exhaust Ex leaves the energy converter 300 and flows over the exhaust path 416 in the area. The limit fluid level is typically less than the distance from the bottom of the exhaust path outlet to the roadway. Below the boundary liquid level so no dirty water can penetrate into the exhaust path. Now the motor vehicle passes through a body of water with a depth T , which is greater than the distance from the outlet of the exhaust path 416 to the road surface, so causes the liquid level W, the dirty water H2O in the outlet from the exhaust path 416 penetrates (shown as a dashed arrow). According to the technology disclosed herein, it may be provided that such a liquid level is detected by the motor vehicle, and that then a remedial action is initiated. For example, in the embodiment according to the 2 be provided that the speed of the turbomachine 500 is increased until a sufficiently high mass flow rate of gas in the exhaust path 416 is opposed to the penetrating water, so that the dirty water H2O can not or not penetrate deeper into the exhaust system. For this purpose, at least one section of the exhaust path is preferably formed substantially in the vertical direction (ie parallel to the vertical axis of the vehicle). If a sufficiently high mass flow rate of gas flows through such a vertical section, the penetration of dirty water H2O can be prevented particularly well. Alternatively or additionally, further measures disclosed herein can be used in the 2 be implemented. Any other components of the system, such as the intercooler 420 or the membrane humidifier 430 , have been omitted here for simplicity. According to the technology disclosed herein, these components could be above or below the wadding line AA be arranged.

• - den Querschnitt zu verringern, falls der Grenzflüssigkeitspegel erreicht ist bzw. falls der Massendurchsatz an Gas im Abgaspfad erhöht wird, um Schmutzwasser am Eindringen zu hindern; und
• - den Querschnitt zu erweitern, falls der Flüssigkeitspegel unterhalb vom Grenzflüssigkeitspegel ist (oder keine Flüssigkeit detektiert wird).

Preferably, in the exhaust path 416 an exhaust gas accelerating device for accelerating the exhaust gas may be provided (not shown). The exhaust gas accelerating device is preferably downstream of the muffler 417 intended. Preference can thereby at lower power or at lower flow volume of the turbomachine 500 already the dirty water to be prevented from entering. In a preferred embodiment, the cross-sectional constriction of the exhaust gas accelerating device is compared to adjacent regions of the exhaust path 416 Max. 15% or max. 7% or max. 3%. In one embodiment, the exhaust gas accelerator is a venturi configured to extract water from the muffler 417 dissipate. Alternatively or additionally, it may be provided that the exhaust gas acceleration device has a variable cross section. For example, the exhaust gas accelerating device may be operable to

• reduce the cross-section if the limit liquid level is reached or if the mass flow rate of gas in the exhaust path is increased to prevent dirty water from entering; and
• - to expand the cross-section if the liquid level is below the limit liquid level (or no liquid is detected).

According to the technology disclosed herein, the exhaust path becomes 416 not completely closed, but it continues to emit exhaust gas.

In a further embodiment (not shown here) can be provided that the outlet from the exhaust path 416 above the wading line AA is arranged. Thus, it is thus ensured that the dirty water H2O is not in the outlet from the exhaust path 416 penetrates. In this case, the motor vehicle may further preferably comprise a drainage device, wherein the drainage device is set up, water or product water from the exhaust path 416 , in particular of areas of the exhaust path 416 below the wading line AA To remove and at the same time the drainage path from the outside in the exhaust path 416 penetrating water or dirty water is protected. For example, such a drainage device may be a correspondingly designed valve or a drainage pump. The drainage pump can drain the water, for example, to the outlet above the wading line AA pump. This solution is independent of the other solutions disclosed herein. Further advantageously, the dewatering pump can also be controlled in normal operation so that is drained only in suitable driving conditions.

The 3 shows a further embodiment of the technology disclosed here. Below, only the differences from the embodiment according to the 2 explained. The exhaust path 416 here includes a subarea 416 ' , which is above the wading line AA runs. The subarea 416 ' is further spaced from the road F arranged as the flow machine to be protected 500 , If the motor vehicle now passes through a body of water with the depth T, then the turbomachine emerges 500 into the waters.

The dirty water H2O penetrates through the outlet of the exhaust path 416 in the exhaust path 416 and floods the silencer 417 , However, the dirty water H2O can not become turbomachine 500 stream. The dirty water H2O is here through the sub-area 416 ' prevented from doing so. Only when the liquid level W here far over the wading line AA increases, the dirty water H2O could backflow. In the 3 is also a drainage line 419 located. The drainage line 419 branches of a water collection area 527 from the exhaust path 416 from. The drainage line 419 under water collection area 427 can be designed such that no or only insignificantly small amounts of dirty water H2O through the drainage line 419 can flow back.

In the 4 is an enlarged detail view of the silencer 417 shown. Other components of the motor vehicle have been omitted for simplicity. Hereinafter, only the differences from the previous embodiments will be explained. In the silencer 417 here is the decor 600 for closing the exhaust path 416 arranged. The device 600 includes a float 610 , this one over a sliding bar 612 is guided. The swimmer 610 is designed to change its vertical position in the installed position depending on the liquid level W. The swimmer 610 is here via a mechanical coupling 630 with the lock 620 connected. The mechanical coupling 630 is here by two control rods 634 . 635 and three camps 631 . 632 . 633 educated. In the embodiment shown here, for example, the bearing 631 a camp and the camps 632 . 633 are floating bearings. Particularly preferred may be the closure 620 be closed by a toggle (not shown). Such kinematics to form a mechanical coupling 630 can be designed differently and is familiar to the expert.

In the position shown here closes the shutter 620 the device 600 the section of the exhaust path 416 through which the Ex exhaust gas enters the silencer 417 flows. This is the case when the liquid level W is above the limit liquid level. Now, if the liquid level W below the limit liquid level, so is the float 610 arranged lower (shown in dashed lines in the figure). Consequently, the shutter is 620 then in an open position. During normal vehicle operation, therefore, the exhaust gas Ex unhindered in the silencer 417 flow. In the silencer 417 accumulating product water can via a fluid connection in a delivery line of the jet pump 470 be introduced. The delivery line of the jet pump 470 gets here from the drainage line 419 educated. But such a fluid connection does not have to be in the drainage line 419 but can also separate in the jet pump 470 lead.

As an alternative to the embodiment according to the 4 can be provided that the shutter 620 a flap comprising the float disclosed herein. The flap may, for example, be of the shape that the flap is open if the liquid level W is below the limit liquid level, ie if there is no critical wading. For example, the flap can be held in the open position via a return means (usually a spring means). The buoyant force acting on the float would then act against these return means before and during a wad and seal the closure. The flap is thus set up by that in the exhaust path 416 back-flowing water to be actuated. Advantageously, such a flap, for example, by the camp 632 be stored. The float may for example be attached to the flap or be formed by the flap material itself. In one embodiment, the flap may be coated hydrophobic.

For the sake of legibility, the term "at least one" has been omitted for simplicity. If a feature of the technology disclosed herein is singularly described (eg, the exhaust path, the inflow path, the shutter, the float, the device, the drainage line) Part area, the / a jet pump, the / a noise damper, etc.) so should also be at the same time with its majority disclosed (eg the at least one exhaust path, the at least one inflow, the at least one closure, the at least one float, the at least one device , the at least one drainage line, the at least one partial area, the at least one jet pump, the at least one noise damper, etc.).

The foregoing description of the present invention is for illustrative purposes only, and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

Claims (7)

Motor vehicle at least one energy converter (300), comprising; - At least one exhaust path (416); and - At least one means (600) for closing the exhaust path (416); wherein the device (600) comprises a float (610), the float (610) being arranged to effect closure from the exhaust path (416) if a limit liquid level is reached. Motor vehicle after Claim 1 wherein the float (610) is coupled to a closure (620) via a mechanical coupling (630), the closure (620) being arranged to close the exhaust path (416) if the limit liquid level is reached. Motor vehicle after Claim 1 wherein a movable shutter (620) comprises the float (610), and wherein the shutter (620) is arranged to close the exhaust path (416) if the boundary liquid level is reached. Motor vehicle according to one of the preceding claims, wherein an inlet of an inflow path (415) in the installed position is further from the roadway spaced as the outlet from the exhaust path (416). Motor vehicle, in particular according to one of the preceding claims, wherein at least a portion (416 ') of the at least one exhaust path (416) in the installed position further from the roadway (F) is spaced as a vehicle component (500) with the exhaust path (416) is fluid-connected, and to be protected from entering the exhaust path (416) water. Motor vehicle after Claim 4 , wherein a drainage line (419) as a bypass line to the partial area (416 ') is formed. Motor vehicle after Claim 5 wherein the drainage line (419) opens into a jet pump (470) adapted to draw liquid from the drainage line (419).

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