Media transport device

Abstract

The invention relates to a transport device for a medium in a fuel cell system (1) with a prime mover (21), which drives at least one coolant pump (17), at least one transport mechanism for air (8) and at least one transport mechanism for anode exhaust gas recirculation (14). The transport device according to the invention is characterized in that the prime mover (21) has a rotor shaft (22) to which the coolant pump (17) is directly coupled, the coolant pump (17) or the prime mover (21) is magnetically coupled to one of the transport mechanisms (8, 14), and the prime mover (21) or the transport mechanism (8, 14) is magnetically coupled to the other transport mechanism (14, 8).

Description

[Technical field]

[0001] The present invention relates to a transport device for a medium in a fuel cell system of the kind as defined in detail in the preamble of claim 1. Furthermore, the present invention relates to a fuel cell system equipped with such a transport device and to a vehicle equipped with such a fuel cell system. [Background technology]

[0002] Fuel cell systems for use in providing electric drive power, for example in at least partially electrically driven vehicles, are largely known from the prior art. In the case of fuel cell systems, on the one hand, air as an oxygen source must be transported, and on the other hand, a cooling system is required, in which a coolant, typically in liquid form, circulates to remove the waste heat. In addition, a so-called anode circuit is present in many fuel cells. To compensate for pressure losses, a recirculation blower is often provided, either alone or as an auxiliary to the gas jet pump. In practice, it is common for both the coolant pump, the conveying mechanism for the air, e.g. a flow compressor, and the conveying mechanism for the recirculation, e.g. a recirculation blower, to each have their own drive, typically an electric motor drive. This requires a large construction space on the one hand and a large number of power supply lines to the individual components on the other hand.

[0003] Therefore, the document describes a fuel cell system with a medium-conveying unit in which there is a common drive for several units, whereby the required speed and conveying power are adjusted by means of corresponding speed converters and / or reduction devices, i.e. transmissions, and where appropriate the individual units are connected and disconnected from the drive by means of this drive unit. [Patent Document 1] DE102004037141A1

[0004] In fact, this structure should be rated as relatively dangerous since the need for a gearbox often results in oil getting into the area of ​​the conveyed air and / or the circulated anode exhaust gas, just as with the direct coupling to the drive motor according to the general prior art described above. These oils are detrimental to the fuel cell and can accelerate the degradation of electrochemically active components in the fuel cell, thus becoming a drawback to the predictable life of the fuel cell.

[0005] As further prior art, one may also point to US Pat. No. 5,399,633, which describes a common drive for two conveying mechanisms for air to the fuel cell on the one hand and for the recirculation of the anode exhaust gas on the other hand. In order to prevent mixing of these substances, these conveying mechanisms are hermetically sealed and coupled to a common drive motor, the construction of which is realised in each case in the form of a so-called canned motor. [Patent Document 2] DE102004044068A1

[0006] As further prior art, reference can be made to US Pat. No. 5,399,433, which shows two refrigerant pumps with a common electric motor drive, and also to US Pat. No. 5,499,444, which shows several electric motor drives grouped together in a motor housing, each of which is magnetically coupled to the conveying unit that it drives. [Patent Document 3] DE102012008494A1 [Patent Document 4] WO2010 / 082913A1 Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the invention is to provide an improved transport device for media in a fuel cell system. [Means for solving the problem]

[0008] This object is achieved according to the invention by a transport device having the features of claim 1. Furthermore, a fuel cell system comprising such a transport device achieves this object. A vehicle comprising a fuel cell system and such a transport device also achieves this object.

[0009] In addition, further advantageous configurations of the conveying device are evident from the dependent claims to the main claim.

[0010] The conveying device according to the invention, like the prior art mentioned at the beginning, utilizes a common prime mover for the coolant pump, the conveying mechanism for the air and the conveying mechanism for the anode exhaust gas. This prime mover is directly connected to the coolant pump by the rotor shaft of the prime mover. Possible lubricants and the like, which are required in the area of ​​the prime mover, typically an electric prime mover, are relatively free of risk here, so that a direct connection by a common shaft is advantageous here. In addition to this direct connection, the coolant pump or the prime mover is magnetically connected to one of the conveying mechanisms, and the prime mover or the connected conveying mechanism is also connected to another conveying mechanism by a further magnetic connection in this case.

[0011] This has the decisive advantage that in principle only one prime mover, preferably an electric prime mover, is required, which may, however, be assisted by a turbine, as in the case of so-called electric turbochargers, which are generally known and customary in fuel cell systems. This means that the prime mover can be directly connected to the coolant pump by its driven shaft, for example the rotor shaft of an electric drive motor, and can directly drive the coolant pump. The conveying mechanisms for both air and anode exhaust gas are then connected via a magnetic clutch. These conveying mechanisms can, for example, be connected in tandem, i.e. one of the conveying mechanisms, for example the conveying mechanism for air or its compressor wheel, is connected to the pump via a magnetic clutch, and the blower wheel of the conveying mechanism for recirculation is connected to the conveying mechanism for air, also by a magnetic clutch. This has the decisive advantage that no undesirable substances can get into either the air or the recirculated anode exhaust gas from the area of ​​the electric machine. An equivalent construction is of course also possible where one or both of the conveying mechanisms are magnetically coupled to the prime mover and, on the other side, the coolant pump alone or the coolant pump and one of the conveying mechanisms are correspondingly coupled.

[0012] In this respect, the magnetic coupling of the conveying mechanism for the air on the one hand and the conveying mechanism for the anode exhaust gas recirculation on the other hand has the decisive advantage that the structures with the corresponding media can be sealed very simply and efficiently, which is a decisive advantage especially in the case of hydrogen-containing anode exhaust gas in order to efficiently prevent the escape of hydrogen to the environment, which is absolutely necessary for safety reasons.

[0013] According to an advantageous embodiment of the conveying mechanism, a transmission is provided for at least one of the conveying mechanisms in the region of the coolant pump and / or in the region of one of the conveying mechanisms for speed adjustment. It is preferred in this respect that the transmission is arranged on the motor side or in the region of the coolant pump, in which case the already converted speed is transferred to the compressor wheel and / or blower wheel of the respective conveying mechanism via a magnetic clutch. This design minimizes contamination, for example with the corresponding lubricant used in the region of the transmission. However, depending on the design of the corresponding conveying mechanism, it is also possible to use simple lubricant-free transmission elements, for example in the region of the recirculation blower, so that a transmission can also be arranged between the magnetic clutch and the recirculation blower itself.

[0014] As already mentioned, such a conveying device is particularly suitable for use in fuel cell systems with at least one coolant pump, at least one conveying mechanism for air and at least one conveying mechanism for anode exhaust gas recirculation, where it can be advantageously used, where this applies in principle both to stationary fuel cell systems and to vehicles that are provided with at least part of their electric drive power by at least one of these fuel cell systems.

[0015] Further advantageous configurations of the transport device, the fuel cell system and the vehicle according to the invention are apparent from the exemplary embodiments which are described in more detail below with reference to the drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 shows a schematic diagram of a suggested fuel cell system for utilizing a transport device according to the present invention. [Diagram 2] 1 is a schematic diagram of a first possible embodiment of a conveying device according to the invention; [Diagram 3] 4 is a schematic diagram of a further alternative embodiment of a conveying device according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In the representation of FIG. 1, a fuel cell system 1 can be seen which is used to provide at least a part of the electric drive power in a vehicle 2, which is indicated very diagrammatically. Depending on the vehicle 2, a number of such fuel cell systems 1 are provided in this respect, or one or more fuel cell stacks 3 are provided in the fuel cell system 1 shown here. A fuel cell stack 3, which is indicated diagrammatically here, comprises in its interior a cathode chamber 4, an anode chamber 5 and a cooling heat exchanger 6, which is indicated by way of example. In this respect, the cathode chamber 4 is separated from the anode chamber 5 by a proton-conducting membrane 7. In reality, this structure is realized as a stack of single cells. In the figure, a common cathode chamber 4 and a common anode chamber 5 as well as a common cooling heat exchanger 6 are indicated diagrammatically and purely by way of example.

[0018] To provide an electrical output by the fuel cell stack 3, air is delivered to the fuel cell stack 3 via an air supply pipe 9 by a conveying mechanism 8. The exhaust air passes through an exhaust pipe 29 and leaves the fuel cell system 1 and the vehicle 2 with reduced oxygen. This area could be provided with an exhaust turbine in a manner known per se in order to recover pressure energy and thermal energy from the exhaust air. Exhaust turbines are to a large extent known from the prior art and could be present here as well. They are not shown in order to simplify FIG. 1 .

[0019] Hydrogen is fed to the cathode chamber 4 from a compressed gas reservoir 10 via a pressure regulating and metering valve 11. Unconsumed hydrogen is returned in the so-called anode circuit 12 through a recirculation pipe 13. A conveying mechanism 14 for the anode exhaust gas recirculation compensates for pressure losses. A water separator 15 separates the product water occurring in the region of the anode chamber 5. This product water is drawn off together with the inert gas accumulated in the anode circuit 12 via a valve 16, for example from time to time or depending on the hydrogen concentration in the anode circuit 12.

[0020] The cooling heat exchanger 6 of the fuel cell stack 3 is part of a cooling circuit 28 in which a liquid coolant is circulated by a coolant pump 17. Waste heat is rejected by the cooling heat exchanger (also called a cooler in colloquial terms) to the surroundings of the vehicle 2. The very simplified illustrated cooling circuit 28 further comprises a bypass pipe 19 to bypass the cooling heat exchanger 18, so that the cooling output can be controlled by a valve 20 controlling this bypass pipe and the speed of the coolant pump 17.

[0021] All this is to a large extent known to those skilled in the art and therefore need not be discussed further.

[0022] The coolant pump 17 and both conveying mechanisms 8, 14 should here be driven by a common prime mover 21. In the representation of FIG. 2, this common prime mover 21 is suggested. This prime mover 21 can be, for example, an electric prime mover. In order to achieve the most energy-efficient drive possible, the prime mover 21 can furthermore be mechanically or electrically connected to an appropriate exhaust gas turbine, as already mentioned above. The prime mover 21 is directly connected via a shaft 22 to the coolant pump 17. The coolant pump 17 itself or its pump impeller is then connected via a magnetic clutch 23 with a drive side 24 and a driven side 25 to the conveying mechanism 8 for the air. An optional gearbox 26, shown cross-hatched, can furthermore be provided between the driven side 25 of the magnetic clutch 23 and the conveying mechanism 8. The conveying mechanism 8 for the air is also connected via another magnetic clutch 23 with a drive side 24 and a driven side 25 to the conveying mechanism 14 for the anode exhaust gas recirculation. Here too, a further transmission 27 can be provided between the driven side 25 of the second magnetic clutch 23 and the conveying mechanism 14 or its blower wheel.

[0023] The main ingress of lubricant occurs in the area where the shaft 22 directly connects the prime mover 21 and the coolant pump 17. This ingress is typically harmless to the coolant. In contrast, ingress of lubricant into the air and especially into the recirculated exhaust gases is dangerous, since this may reach the anode chamber 5 or the cathode chamber 4 and there adversely affect the electrochemical properties of the fuel cell stack 3. For this reason, a relatively good and easily sealable decoupling of these conveying mechanisms 8, 14 from the prime mover 21 can be achieved by both magnetic clutches 23. An optional transmission 26, 27 could certainly make this situation difficult as well, but since lubricated-free or only slightly lubricated transmissions are often required in this area, this remains relatively risk-free.

[0024] The representation of Fig. 3 shows an alternative embodiment. The electric motor 21 is again connected directly via its shaft 22 to the coolant pump 17, which is then connected accordingly by one of the magnetic clutches 23 to the conveying mechanism 8 for the air via an optional transmission 26, this time arranged on the side of the coolant pump 17. The magnetic clutch 23 provides a very good sealable magnetic connection between the transmission and the compressor wheel of the conveying mechanism 8, so that any possible contamination of the lubricant in the transmission 26 can be kept away from the air compressed by the conveying mechanism 8.

[0025] Here, the further conveying mechanism 14 is not arranged adjacent to the compressor wheel of the conveying mechanism 8, but on the other side of the drive motor 21. Here too, the optional gearbox 27 is arranged on the motor side, only then comes the magnetic clutch 23, so that here too, the ingress of any possible contamination from the electric motor 21 and any gearbox into the area of ​​the blower wheel of the conveying mechanism 14 can be prevented.

[0026] This construction, with the sequence of the optional transmissions 26, 27 and the magnetic clutch 23 rotated with respect to the representation in Fig. 2, would of course also be conceivable in the representation in Fig. 2. It would also be conceivable to use the sequence shown in Fig. 2 in the case of a construction according to Fig. 3. Moreover, it would of course be conceivable to interchange both conveying mechanisms 8, 14, or to mount both on one side of the electric motor 21 and the coolant pump 17 on the other side of the motor 21.

Claims

1. A transport device for a medium in a fuel cell system (1) with a prime mover (21), the prime mover driving at least one coolant pump (17), at least one transport mechanism for air (8) and at least one transport mechanism for anode exhaust gas recirculation (14), the transport device comprising: the prime mover (21) has a rotor shaft (22), the refrigerant pump (17) is directly connected to the rotor shaft (22), the refrigerant pump (17) or the prime mover (21) is magnetically connected to one of the conveying mechanisms (8, 14), and the prime mover (21) or the conveying mechanism (8, 14) is magnetically connected to another of the conveying mechanisms (14, 8); In at least one region of the conveying mechanism (8, 14), a transmission (26, 27) is provided for speed adjustment, The conveying device, wherein the transmissions (26, 27) are provided on the sides of the magnetic clutches (23) facing the respective conveying mechanisms (8, 14).

2. 2. The conveying device according to claim 1, characterized in that the conveying mechanism (8) for air is formed as a flow compressor.

3. 3. The conveying device according to claim 1 or 2, characterized in that the conveying mechanism (14) for anode exhaust gas recirculation is formed as a recirculation blower.

4. A fuel cell system (1) comprising a transport device according to any one of claims 1 to 3.

5. A vehicle (2) equipped with at least one fuel cell system (1) according to claim 4.

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