Patent Application
20230268529
The present invention relates to a detection system for detecting hydrogen in a cavity of a fuel cell vehicle, comprising a fuel cell system with a fuel cell housing and a purging air line for purging the fuel cell housing and a hydrogen sensor outside the fuel cell housing, wherein the purging air line has a purging air outlet for discharging purging air out of the fuel cell housing. The invention further relates to a fuel cell vehicle comprising such a detection system.
In polymer electrolyte membrane (PEM) fuel cell systems, hydrogen is converted into electrical energy using oxygen while generating waste heat and water. For this purpose, such a PEM fuel cell system generally has a plurality of stacked fuel cells, each with an anode that is in each case supplied with hydrogen, a cathode that is in each case supplied with air and polymer electrolyte membranes that are in each case placed between an anode and a cathode. By stacking the fuel cells, the electrical output voltage of the fuel cell system can be increased. Within such a stack, there are supply channels that supply the individual fuel cells with hydrogen and air, or remove depleted moist air and depleted anode exhaust gas from the fuel cell stack, or the fuel cell system. Structurally, a fuel cell stack has many meters of sealing points through which small amounts of hydrogen can leave the fuel cell stack in the form of leakage.
For the defined removal of the escaping hydrogen, the fuel cell stack in accordance with the prior art is enclosed by a fuel cell housing. The fuel cell housing is supplied with purging air in a defined manner from at least one point. At at least one further point, the purging air leaves the fuel cell housing again through a purging air line. The fuel cell housing is purged, as it were, with the purging air. With fuel cell systems of this type, a hydrogen sensor is installed in or on the purging air line in order to detect hydrogen in the fuel cell housing. In addition, according to statutory requirements, a further hydrogen sensor must be installed in closed or semi-closed cavities, such as in an engine compartment of the fuel cell vehicle. With known systems, both hydrogen sensors detect hydrogen, or a hydrogen concentration, and cause the fuel cell system to shut down when it is detected that a predefined limit is exceeded. However, hydrogen sensors are expensive and lead to a complex system structure in the fuel cell vehicle.
The present invention proposes a cost-effective and simply constructed system for the reliable detection of unwanted hydrogen in a fuel cell system and/or in a fuel cell vehicle. Features described in connection with the detection system also apply in connection with the fuel cell vehicle according to the invention and vice versa in each case so that reference is and/or can always be made mutually with respect to the disclosure concerning the individual aspects of the invention.
In accordance with a first aspect of the present invention, a detection system for detecting hydrogen in a cavity of a fuel cell vehicle is provided. The detection system has a fuel cell system with a fuel cell housing and a purging air line for purging the fuel cell housing, and a hydrogen sensor outside the fuel cell housing. The purging air line has a purging air outlet for discharging purging air out of the fuel cell housing. The purging air outlet is designed for applying the purging air from the purging air line to the hydrogen sensor.
The arrangement according to the invention of the purging air line, or purging air opening, and of the one hydrogen sensor means that the otherwise usual hydrogen sensor within the purging air line and/or within the fuel cell housing can be dispensed with. This can reduce costs and simplify the system design of the fuel cell system. Dispensing with the hydrogen sensor and the associated functional components also creates installation space for other functional components or allows a more compact design of the fuel cell system.
The purging air outlet is preferably designed for directly applying the purging air from the purging air line to the hydrogen sensor. That is to say, the purging air outlet and/or the purging air line are designed and/or arranged in such a way that purging air escaping from the purging air line through the purging air opening can reach the hydrogen sensor directly and/or at least without obstacles.
The hydrogen sensor can be understood as a sensor unit with a sensor housing and a sensor surface in the sensor housing. A functional unit described here and arranged on the hydrogen sensor therefore does not have to be arranged directly on the sensor surface but can also be arranged on the sensor housing. The hydrogen sensor is configured and arranged to detect hydrogen and/or a hydrogen concentration in the purging air and in the cavity.
The purging air outlet is configured to discharge purging air from the fuel cell housing to the surroundings of the fuel cell housing. Depending on the design variant, the purging air outlet can be understood as an end section of the purging air line or a functional component adjoining the purging air line and connecting the purging air line to the hydrogen sensor.
The cavity can be designed to be closed or semi-closed. The cavity can be understood as an installation space, e.g., the engine installation space, in the fuel cell vehicle. The purging air line does not have to be designed in the form of an ideal duct, but can in principle have any geometry as long as it is suitable for conducting the purging air out of the fuel cell housing in a targeted manner. The fuel cell system is not purged through the purging air line but is purged by using the purging air line. The purging air line can have a purging air inlet section through which purging air is conducted into the fuel cell housing, and a purging air outlet section using which the purging air or treated purging air can be conducted out of the fuel cell housing again.
The fuel cell system preferably has a plurality of fuel cell stacks enclosed or substantially enclosed by the fuel cell housing. The hydrogen sensor can be configured in the form of a hydrogen microsensor with temperature-compensating, pressure-compensating and humidity-compensating signal analysis.
In accordance with a further design variant of the present invention, it is possible for the purging air outlet in a detection system to be directed toward the hydrogen sensor for direct application of the purging air from the purging air line to the hydrogen sensor. By orienting the purging air outlet and the purging air line directly toward the hydrogen sensor, the hydrogen concentration in the purging air can be determined particularly accurately. Mixing with other fluids can be easily prevented or at least reduced and/or adjusted to the desired amount. Orienting the purging air outlet toward the hydrogen sensor can be understood to mean that a normal vector of the purging air outlet is directed in the direction of the hydrogen sensor and/or toward the hydrogen sensor. Furthermore, a normal vector of the purging air outlet can be oriented orthogonally or at an obtuse angle to a normal vector of a sensor surface of the hydrogen sensor, wherein the normal vector of the sensor surface extends in the direction of gravity or substantially in the direction of gravity in a state installed in the fuel cell vehicle. This is a simple way of ensuring that the purging air reaches the hydrogen sensor as directly as possible.
In accordance with another design variant of the present invention, it is possible for a detection system to have a collection means for collecting hydrogen, which means is arranged at the hydrogen sensor for the purpose of conducting the collected hydrogen to the hydrogen sensor. By means of the collection means, hydrogen-containing fluid that would otherwise not be able to reach the hydrogen sensor can also be conducted to the hydrogen sensor, as a result of which the detection system can particularly effectively detect an unwanted hydrogen leakage.
With a detection system according to the invention, the collection means can be designed to be funnel-shaped. The funnel shape allows ambient air, and thus any hydrogen, to be collected and fed to the hydrogen sensor in a simple, cost-effective and yet effective manner. The funnel-shaped collection means tapers toward the hydrogen sensor. In particular, the funnel-shaped collection means tapers in the opposite direction to the direction of gravity in a state of the detection system installed in the fuel cell vehicle. The collection means is preferably designed and/or arranged coaxially and/or concentrically with the hydrogen sensor and/or the purging air outlet.
With a detection system in accordance with the present invention, the purging air outlet is preferably arranged at least partially in alignment with the hydrogen sensor. This allows the purging air flowing out of the purging air line to directly impinge on the hydrogen sensor. This allows particularly meaningful measurements to be carried out of the hydrogen content in the purging air. In this case, the purging air outlet is directed directly or substantially directly toward the hydrogen sensor. The purging air outlet being arranged at least partially in alignment with the hydrogen sensor can be understood to mean that an imaginary extension of the purging air line in the direction of a normal vector of the purging air outlet would at least partially impinge on the hydrogen sensor.
In addition, a detection system in accordance with the present invention can have a connection housing that is connected to the purging air line and the hydrogen sensor for the purpose of conducting the purging air to the hydrogen sensor. With the aid of the connection housing, the purging air and thus also the hydrogen in the purging air can be conducted directly to the hydrogen sensor without the purging air being diverted by obstacles, for example, and thus being undesirably mixed with other fluids. With the aid of the connection housing, the hydrogen sensor does not have to be arranged directly at the purging air outlet and a meaningful measurement of the hydrogen content in the purging air can still be carried out.
Furthermore, it can be advantageous if the connection housing with a detection system in accordance with the present invention is designed to be at least partially funnel-shaped. The funnel-shaped connection housing, which preferably tapers toward the purging air outlet and widens correspondingly toward the hydrogen sensor, can act as a diffuser through which the purging air flow from the purging air line can be slowed down and thus be detected more effectively at the hydrogen sensor.
Moreover, with a detection system in accordance with the present invention, it is possible for the connection housing to have at least one gas inlet opening for admitting hydrogen from the cavity into the connection housing. This is a simple and effective way of ensuring that hydrogen from the surroundings of the fuel cell housing or leakage hydrogen from the fuel cell housing can still be detected by the hydrogen sensor. The connection housing preferably has a plurality of gas inlet openings or holes for admitting hydrogen from the cavity or ambient air from the surroundings of the fuel cell housing into the connection housing. Alternatively, the connection housing can be designed to be half-shell-shaped, wherein the closed part of the connection housing connects the purging air line and the hydrogen sensor to one another and the open part of the connection housing can be understood as the at least one gas inlet opening.
Furthermore, it is possible that the purging air line of a detection system according to the invention has a nozzle and the connection housing comprises an ejector adjacent to the nozzle with a mixing chamber for providing a fluid mixture of the purging air and the hydrogen from the cavity, and with a diffuser, wherein the mixing chamber has the at least one gas inlet opening and the diffuser is connected to the hydrogen sensor for the purpose of supplying the fluid mixture to the hydrogen sensor. In this way, ambient air from the surroundings of the fuel cell housing or the leakage hydrogen contained therein can be effectively drawn into the mixing chamber and from there conducted toward or to the hydrogen sensor.
In accordance with a further aspect of the present invention, a fuel cell vehicle having a cavity and a detection system as described in detail above for detecting hydrogen in the cavity is provided. Thus, the fuel cell vehicle according to the invention offers the same advantages as have been described in detail with reference to the detection system according to the invention. The fuel cell vehicle is preferably provided in the form of a road vehicle, in particular in the form of a car or a truck.
Further measures improving the invention result from the following description of various exemplary embodiments of the invention, which are schematically illustrated in the figures. All features and/or advantages arising from the claims, the description or the figures, including structural details and spatial arrangements, can be essential to the invention both by themselves and in the various combinations.
The following are shown, in each case schematically:
Elements with the same function and mode of operation are each given the same reference signs in the figures.
In accordance with the embodiment shown in
In
In addition to the illustrated embodiments, further design principles of the invention are possible. That is to say, the invention is not to be limited to the exemplary embodiments explained with reference to the figures. Thus, the purging air line 17 need not extend beyond the fuel cell housing 16 but can also be flush with the fuel cell housing 16.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 209 494.2 | Jul 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/069805 | 7/15/2021 | WO |
