Media Support Device

Description

[0001] The invention relates to a conveying device for media in a fuel cell system according to the type defined in more detail in the preamble of claim 1. Furthermore, the invention relates to a fuel cell system with such a conveying device and to a vehicle with such a fuel cell system.

[0002] Fuel cell systems, for example, for use in providing electric drive power in at least partially electrically powered vehicles, are known from the state of the art. Fuel cell systems require, on the one hand, air to supply oxygen, and, on the other hand, a cooling system in which a typically liquid cooling medium is circulated to dissipate waste heat. Furthermore, many fuel cells contain a so-called anode circuit. A recirculation fan is often provided to compensate for pressure losses, either alone or in support of a gas jet pump.In practice, the coolant pump, an air conveying device, such as a flow compressor, and a recirculation conveying device, such as a recirculation fan, are typically each equipped with their own drive, typically an electric motor. This requires a large amount of installation space and necessitates numerous electrical supply lines to the individual components.

[0003] DE 10 2004 037 141 A1 therefore describes a fuel cell system with media delivery units, in which a common drive is provided for several units. Appropriate speed increase and / or reduction devices, i.e., gears, are used to adjust the required speeds and delivery rates, and if necessary, the individual units can be switched on and off for drive by the single drive unit.

[0004] In practice, this design is relatively critical, as the required gearboxes, similar to the direct connection to the drive motors according to the aforementioned general state of the art, often introduce oils into the area of ​​the conveyed air and / or the recirculated anode exhaust gas. These are detrimental to the fuel cell and promote degradation of the electrochemically active components in the fuel cell, which can lead to disadvantages regarding the expected service life of the fuel cell.

[0005] For further information on the state of the art, reference can also be made to DE 10 2004 044 068 A1. This document describes a common drive for two conveying systems, one for supplying air to a fuel cell and the other for recirculating anode exhaust gas. To prevent mixing of these materials, they are hermetically sealed to the common drive motor, with the design being implemented in the form of so-called canned motors.

[0006] Further prior art includes DE 10 2012 008 494 A1, which shows two cooling medium pumps with a shared electric motor drive. WO 2010 / 082913 A1 also applies. This document shows several electric motor drives combined in a motor housing, which are magnetically coupled to the respective driven delivery units. Furthermore, WO 00 / 54353 A1 discloses a method for reducing the auxiliary energy consumption required to operate a fuel cell system and thus increasing the electrical energy usable outside the fuel cell system. In this method, an air compressor and a water pump of the fuel cell system are driven by a shared, speed-controlled drive motor. Furthermore, CN 205 985 199 U discloses a fuel cell system with an integrated drive structure.

[0007] The object of the present invention is to provide an improved conveying device for media in a fuel cell system.

[0008] According to the invention, this object is achieved by a conveying device having the features of claim 1. Furthermore, a fuel cell system with such a conveying device achieves the object. A vehicle with a fuel cell system and such a conveying device can also achieve the object.

[0009] Further advantageous embodiments of the conveying device also result from the subclaims dependent on the main claim.

[0010] The conveying device according to the invention uses, similarly to the prior art mentioned at the beginning, a common drive machine for a cooling medium pump, a

[0011] A conveying device for air and a conveying device for anode exhaust gas. The drive motor is directly connected to the cooling medium pump via a rotor shaft of the drive motor. Any lubricants and the like required in the area of ​​the drive motor, typically an electric drive motor, are relatively uncritical here, so a direct connection via a common shaft is advantageous. In addition to this direct coupling, either the cooling medium pump or the drive motor is magnetically coupled to one of the conveying devices, and the drive motor or the coupled conveying device is then coupled to the other conveying device via another magnetic coupling.

[0012] In principle, this has the decisive advantage that only a single drive machine is required, preferably an electric drive machine, which can, if necessary, however, be supported by a turbine, as is the case with the so-called electric turbocharger, which is generally known and common in fuel cell systems. This drive machine can in turn be coupled directly to the cooling medium pump with its driven shaft, for example the rotor shaft of the electric drive motor, and drive this directly. The two conveyor devices for the air and the anode exhaust gas are then coupled via magnetic couplings. These can, for example, be coupled one behind the other, so that one of the conveyor devices, for example the air conveyor device or the anode exhaust gas, is connected to the cooling medium pump.Its compressor wheel is coupled to the pump via a magnetic coupling, and a fan wheel of the recirculation conveying device is in turn coupled to the air conveying device via a magnetic coupling. This has the crucial advantage that no undesirable substances from the area of ​​the electric machine are introduced into either the air or the recirculated anode exhaust gas. A comparable setup is of course also possible if one or both of the conveying devices are magnetically coupled to the drive motor, and on the other side, the cooling medium pump alone, or the cooling medium pump and one of the conveying devices are coupled accordingly.

[0013] The magnetic coupling of the air conveying system on the one hand and the conveying system for recirculating the anode exhaust gas on the other hand has the decisive advantage that the structure can be sealed very easily and efficiently with the appropriate media. This is particularly important for the anode exhaust gas, which contains hydrogen, in order to effectively prevent hydrogen from escaping into the environment. This is essential for safety reasons.

[0014] According to an advantageous embodiment of the conveying device, a gearbox for speed adjustment is provided in the area of ​​the cooling medium pump and / or one of the conveying devices for at least one of the conveying devices. Preferably, the gearbox is arranged on the motor side or in the area of ​​the cooling medium pump, and the already geared speed is then transmitted via the magnetic coupling to the compressor wheel and / or the fan wheel of the respective conveying device. This design minimizes contamination with corresponding lubricants, which are provided, for example, in the area of ​​the gearbox. Depending on the design of the respective conveying device, simple unlubricated gearbox elements can also be used, for example in the area of ​​the recirculation fan, so that the gearbox could also be arranged between the magnetic coupling and the recirculation fan itself.

[0015] As already mentioned, such a conveying device is particularly suitable for use in fuel cell systems that have at least one cooling medium pump, at least one conveying device for air, and at least one conveying device for recirculating anode exhaust gas. The conveying device can be used advantageously there. This applies in principle both to stationary fuel cell systems and to vehicles that are supplied with at least part of their electrical drive power by at least one of these fuel cell systems.

[0016] Further advantageous embodiments of the conveying device according to the invention, the fuel cell system and the vehicle also emerge from the exemplary embodiment which is illustrated in more detail below with reference to the figures.

[0017] Showing: Fig. 1 shows a schematically indicated fuel cell system for using the conveying device according to the invention; Fig. 2 shows a first possible embodiment of the conveying device according to the invention in a schematic representation; and Fig. 3 shows a further alternative embodiment of the conveying device according to the invention in a schematic representation.

[0018] In the presentation of the Figure 1, a fuel cell system 1 can be seen which is to be used in a very schematically indicated vehicle 2 to provide at least part of the electrical drive power. Depending on the vehicle 2, several such fuel cell systems 1 are provided, or one or more fuel cell stacks 3 are provided within the fuel cell system 1 shown here. The fuel cell stack 3 indicated schematically here comprises a cathode compartment 4, an anode compartment 5 and a cooling heat exchanger 6 indicated by way of example inside the fuel cell stack 3. The cathode compartment 4 is separated from the anode compartment 5 by a proton-conducting membrane 7. In reality, this structure is implemented as a stack of individual cells. In the illustration, a common cathode compartment 4 and a common anode compartment 5 as well as a common cooling heat exchanger 6 are indicated schematically purely as an example.

[0019] To provide electrical power through the fuel cell stack 3, air is supplied to it via a conveyor device 8 via an air supply line 9. Exhaust air, depleted of oxygen, is drawn from the fuel cell system 1 and the vehicle 2 via an exhaust line 29. In this area, an exhaust air turbine could be provided in a manner known per se to recover pressure energy and thermal energy from the exhaust air. This is known from the prior art and could also be present here. For the sake of simplicity, a diagram is omitted. Figure 1 been waived.

[0020] Hydrogen is supplied to the cathode chamber 4 from a compressed gas reservoir 10 via a pressure control and metering valve 11. Unused hydrogen is returned to a so-called anode circuit 12 via a recirculation line 13. Pressure losses are compensated for by a conveying device 14 for the recirculated anode exhaust gas. Product water generated in the area of ​​the anode chamber 5 is separated via a water separator 15. This water is discharged via a valve 16 together with inert gases accumulating in the anode circuit 12, for example, from time to time or depending on the hydrogen concentration in the anode circuit 12.

[0021] The cooling heat exchanger 6 of the fuel cell stack 3 is part of a cooling circuit 28, in which a liquid cooling medium is circulated via a cooling medium pump 17. The waste heat is dissipated into the environment of the vehicle 2 via a cooling heat exchanger, colloquially also referred to as a radiator. The cooling circuit 28, shown in a very simplified manner, also has a bypass line 19 for bypassing the cooling heat exchanger 18, so that the cooling performance can be controlled using a valve 20 controlling this bypass line and the speed of the cooling medium pump 17.

[0022] All of this is well known to the expert, so there is no need to go into it further.

[0023] The cooling medium pump 17 and the two conveying devices 8, 14 are now to be driven by a common drive motor 21. In the illustration of the Figure 2This common drive motor 21 is indicated. This drive motor 21 can, for example, be an electric drive motor. It can also be mechanically or electrically coupled to the optimal exhaust air turbine already mentioned above in order to realize the most energy-efficient drive possible. The drive motor 21 is coupled directly to the cooling medium pump 17 via a shaft 22. The cooling medium pump 17 itself or its pump impeller is then coupled to the conveying device 8 for the air via a magnetic coupling 23 with a drive side 24 and an output side 25. An optional gearbox 26, shown cross-hatched, can also be provided between the output side 25 of the magnetic coupling 23 and the conveying device 8.The air conveying device 8 is in turn coupled to the conveying device 14 for the recirculated anode exhaust gas via a further magnetic coupling 23, which has a drive side 24 and an output side 25. Here, too, a further gear 27 can be provided between the output side 25 of the second magnetic coupling 23 and the conveying device 14 or its fan impeller.

[0024] The primary entry of lubricants occurs in the area where the shaft 22 directly connects the drive motor 21 and the cooling medium pump 17. This entry is typically harmless to the cooling medium. In contrast, the entry of lubricants into the air and especially into the recirculated exhaust gas is critical, as this could enter the anode chamber 5 or the cathode chamber 4 and adversely affect the electrochemical properties of the fuel cell stack 3. For this reason, the two magnetic couplings 23 can provide a relatively good and easily sealed decoupling of these conveying devices 8, 14 from the drive motor 21. While the optional gearboxes 26, 27 can exacerbate the situation, gearboxes with no or only minimal lubrication are often necessary in this area, so this remains relatively uncritical.

[0025] In the presentation of the Figure 3An alternative design variant is shown. The electric drive motor 21 is again directly coupled to the cooling medium pump 17 via its shaft 22. This is then coupled to the air conveying device 8 via the optional gearbox 26, which this time is arranged on the side of the cooling medium pump 17, using one of the magnetic couplings 23. Any possible lubricant contamination within the gearbox 26 can thus be kept away from the air compressed by the conveying device 8, since the highly sealed magnetic coupling is established via the magnetic coupling 23 between the gearbox and the compressor wheel of the conveying device 8.

[0026] The additional conveying device 14 is now not connected to the compressor wheel of the conveying device 8, but is arranged on the other side of the drive motor 21. Here, too, the optional gearbox 27 is arranged on the motor side, followed by the magnetic coupling 23, so that the entry of any contamination from the electric drive motor 21 and the optional gearbox into the area of ​​the impeller of the conveying device 14 can be prevented.

[0027] This structure with a different representation than in Figure 2 rotated order of optional gear 26, 27 and magnetic clutch 23 would also be self-evident in the representation of the Figure 2 It would also be conceivable to use the structure according to Figure 3 which in Figure 2It would also be conceivable to interchange the two conveying devices 8, 14 or to mount both on one side of the electric drive motor 21 and the cooling medium pump 17 on the other side of the drive motor 21.

Claims

1. A conveying apparatus for media in a fuel cell system (1) having a drive machine (21), via which at least one conveying device (8) for air and at least one conveying device (14) for recirculated anode exhaust gas are driven via at least one cooling medium pump (17), characterized in that the drive machine (21) includes a rotor shaft (22) to which the cooling medium pump (17) is directly coupled, wherein the cooling medium pump (17) or the drive machine (21) is magnetically coupled to one of the conveying devices (8, 14) and the drive machine (21) or the conveying device (8, 14) is magnetically coupled to the other conveying device (14, 8).

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

3. The conveying apparatus according to claim 1 or 2, characterized in that the conveying device (14) for the recirculation of anode exhaust gas is designed as a recirculation fan.

4. The conveying apparatus according to claim 1, 2, or 3, characterized in that a gear (26, 27) for speed matching is provided in the area of at least one of the conveying devices (8, 14).

5. The conveying apparatus according to claim 4, characterized in that the gear (26, 27) is provided on the side of the magnetic clutch (23) facing away from the respective conveying device (8, 14).

6. A fuel cell system (1) having a conveying apparatus as claimed in any one of claims 1 to 5.

7. A vehicle (2) having at least one fuel cell system (1) as claimed in claim 6.