Bearing assembly for the shaft of a turbo compressor

Abstract

The present invention relates to a bearing assembly for a shaft of a turbine compressor, comprising at least one water-hydraulic bearing configured to rotatably support the shaft of the turbine compressor, wherein the water-hydraulic bearing surrounds the shaft circumference to form a bearing clearance between the water-hydraulic bearing and the shaft; and wherein the water-hydraulic bearing is configured to allow water to flow through the bearing clearance to hydraulically support the shaft; and two seals configured to seal the bearing clearance relative to the shaft; and wherein the two seals are loaded with gas from the turbine compressor outside the bearing clearance for sealing the bearing.

Description

Technical Field

[0001] The present invention relates to a bearing assembly for a shaft of a turbine compressor, which may be a component of the cathode circuit of a fuel cell stack. Background Technology

[0002] Hydrogen-based fuel cells are seen as the foundation of future mobility solutions because they emit only water and can be refilled quickly. For example, a PEM fuel cell (proton-exchange-membrane) can operate by supplying oxygen-rich air as an oxidant at the cathode and hydrogen as fuel at the anode, in order to provide electricity with high efficiency.

[0003] These fuel cells are typically stacked and operate as a fuel cell stack in a fuel cell system. Air supplied to the cathode of the fuel cell stack is compressed using a turbocompressor.

[0004] The drive shaft of this turbo compressor is supported either by rolling bearings, which have the disadvantages of high friction and correspondingly short service life, or by hydrodynamic air bearings, which are laboriously manufactured due to the high precision required. Both variations also have the disadvantage of difficulty in dissipating the heat generated in the bearings and / or motor. Summary of the Invention

[0005] According to one aspect, a bearing assembly for a shaft of a turbo compressor, the use of the bearing assembly, a cathode circuit for a turbo compressor and a fuel cell stack are provided, based on the features of the independent claim, which at least partially solve the described tasks. The advantageous configuration is the subject of the dependent claims and the following description.

[0006] According to one aspect, a bearing assembly for a turbine compressor shaft is provided, comprising at least one water-hydraulic bearing configured to rotatably support the turbine compressor shaft, wherein the water-hydraulic bearing surrounds the shaft circumference to form a bearing clearance therebetween. Here, the water-hydraulic bearing is configured to allow water flow through the bearing clearance so as to hydraulically support the shaft. The bearing assembly has two seals configured to seal the bearing clearance relative to the shaft, and these two seals are loaded with turbine compressor gas outside the bearing clearance for sealing the bearing.

[0007] Such a turbo compressor typically has two turbines that are mechanically fixed to a common shaft and may have two such bearing assemblies.

[0008] Due to the higher viscosity of water relative to air, the bearing precision of this hydrohydraulic bearing in this bearing assembly is significantly reduced, and the load-bearing capacity of the bearing is significantly increased for similar dimensions.

[0009] As a result of this structure, the heat generated in the bearing can be dissipated by water, and the water can also be used to dissipate heat from the motor. Particularly advantageously, the turbocompressor arranged in the fuel cell stack system can readily provide the water required for the hydrohydraulic bearing, for example, through condensation of the airflow exiting the fuel cell stack.

[0010] Greater sealing performance of the bearing assembly can be achieved by externally loading gas from a turbine compressor onto each seal. Advantageously, this gas is automatically available in such a system.

[0011] According to one aspect, each seal has two sealing elements that form a cavity with the bearing and the shaft; and wherein the bearing has an opening between the two sealing elements to allow fluid connection of the cavity to the water tank.

[0012] This allows water from the bearing clearance through the sealing element adjacent to the bearing clearance to be discharged through the opening with the assistance of gas from the turbo compressor, thus achieving a higher level of bearing sealing. This is further aided by the gas from the turbo compressor, which acts on the sealing element located more externally relative to the bearing clearance. In other words, the compressed air from the turbo compressor is present on the outside of the correspondingly external sealing element, causing air to flow as a blocking medium through the external sealing element into the cavity between the seals. This cavity is connected to a chamber at a significantly lower pressure level. This ensures that no water enters the working air gap area of ​​the drive motor.

[0013] According to one aspect, a gas sealing device with an intermediate space between each of the two seals is arranged outside the seals, the gas sealing device being configured to seal the bearing clearance relative to the shaft, and the hydrohydraulic bearing being configured to apply gas from a turbine compressor to each seal outside the sealed bearing clearance via the intermediate space.

[0014] With the help of this gas sealing device with the bearing clearance arranged outside the seal, the gas of the turbine compressor can be loaded onto each seal particularly effectively and gas pressure can be established when necessary.

[0015] According to one perspective, the bearing clearance is configured for fluid connection with a water tank in order to supply water to the bearing clearance.

[0016] The water in the bearing gaps allows the bearing assembly with the water-hydraulic bearing to be rotatably supported.

[0017] According to one perspective, the water tank has a pump to pump water from the tank into the bearing clearance.

[0018] If the water-hydraulic bearing is implemented as a hydrostatic bearing, then this pump establishes the necessary pressure in the bearing clearance. Such a pump can be used for hydrodynamic bearings, for example, for low-wear startup of turbine compressors, because it can provide initial pressure.

[0019] According to one perspective, a water-hydraulic bearing is a hydrodynamic bearing and is configured to draw water into the bearing clearance itself.

[0020] Advantageously, hydrodynamic bearings do not require any externally applied water pressure because they can autonomously draw water from the tank. In the case of hydrodynamic bearings, the bearing geometry is adapted specifically with respect to eccentricity.

[0021] According to one approach, water flowing from the bearing assembly is used to humidify air, which is then supplied to the cathode of the fuel cell system via a turbo compressor. Thus, after flowing through the hydrodynamic bearings of the bearing assembly and / or, if necessary, through the cooling water circuit of the turbo compressor, the water can be supplied back to the fuel cell system.

[0022] One perspective suggests that water flowing from the bearing assembly is used to cool components of the fuel cell system.

[0023] Water can also be used for this purpose because heat from other components of the fuel cell system, such as electronic components, must also be dissipated in addition to the turbo compressor.

[0024] According to one proposal, the water used for the hydrodynamic bearings includes condensate from the fuel cell system. This advantageously means that the water does not need to be carried over, but is generated during the operation of the fuel cell so that it can be used, for example, for cooling purposes. For this purpose, such a fuel cell system can be equipped with a water separator, particularly at the output end on the cathode side of the fuel cell stack, wherein the water separated by the water separator can then be supplied to a water tank.

[0025] A bearing assembly from the aforementioned bearing assembly is proposed for supporting the shaft of a turbo compressor, which is a component of a fuel cell system. Because water is generated during operation in such a fuel cell system as described above, the turbo compressor supported in this manner is particularly advantageous here.

[0026] A turbo compressor having the aforementioned bearing assembly is proposed, wherein the turbo compressor has a liquid cooling circuit, and water flowing in and / or out of the bearing clearance is guided through the liquid cooling circuit to dissipate heat from the turbo compressor motor.

[0027] The water required for the hydraulic bearings can be guided along its path to the bearing location through the high-heat-load components of the motor and cool these components. The drive motor is located between the bearing locations, and its components must be cooled. The water required for the hydraulic bearings can be guided along its path to the bearing location through the high-heat-load components of the motor and cool these components.

[0028] A cathode circuit for a fuel cell stack with the aforementioned turbo compressor and a humidifier for humidifying the cathode air is proposed, wherein the cathode circuit is configured to supply water flowing from the bearing assembly to the humidifier. The mass flow of air delivered by the compressor of the turbo compressor must be humidified and cooled. Water flowing from the water-hydraulic bearing can also perform this task.

[0029] The cathode gas supplied to the cathode side of the fuel cell stack has an oxidant for the electrocatalytic reaction of the fuel cell in the fuel cell stack, wherein the oxidant may in particular be oxygen or air.

[0030] A water separator can be configured not only to separate droplets of water from the cathode gas, but also to condense gaseous water. In particular, a water separator can also be implemented as a condenser or a combination of a water separator and a condenser. Therefore, the term "water separator" includes not only the term "water separator" itself, but also the term "condenser".

[0031] By employing a water separator implemented in this way, the product water of a fuel cell stack operating at different operating points can be separated. In particular, water can be separated when the outflowing cathode gas is not fully saturated with water, and when it additionally contains water droplets, such as mist or water that has already condensed elsewhere in the system. Here, such a water separator can have a cyclone separator and / or a condenser.

[0032] In other words, the water separator is configured to receive the gas flow from the electrode chambers of the fuel cell stack and to separate water from the gas flow as it is guided through the water separator, wherein the gas flow carries product water from the electrode chambers of the fuel cell stack.

[0033] Therefore, as mentioned above, the product water that accumulates in large quantities during the operation of the fuel cell stack can be used for other purposes.

[0034] According to one aspect, the mobile platform has a turbine compressor having a bearing assembly as described above.

[0035] A mobile platform can be a mobile system that is at least partially automated and / or a driver assistance system. An example could be a vehicle that is at least partially automated or has a driver assistance system. That is, in this context, a system that is at least partially automated includes a mobile platform in terms of its at least partially automated functionality, but the mobile platform also includes vehicles with driver assistance systems and other mobile machines. Each of these systems can be a fully or partially autonomous system. Attached Figure Description

[0036] According to the following Figure 1 and 2 Embodiments of the invention are described in more detail below. They are shown here:

[0037] Figure 1 Turbo compressor; and

[0038] Figure 2 Bearing assemblies for turbo compressors; Detailed Implementation

[0039] Figure 1 A system 100 is shown, comprising a turbo compressor including a water-hydraulic bearing 120, a cathode side of a fuel cell stack 140, and a water tank 130. The turbo compressor has a liquid cooling circuit 122 to which water flowing in and / or out of the bearing clearance can be supplied. This liquid cooling circuit is used to dissipate heat from the turbo compressor's motor.

[0040] At its input connection, the cathode side of the fuel cell stack 140 supplies air 142 through the compressor stage 112 of the turbo compressor, and at the output connection of the cathode side of the fuel cell stack 140, the air mass flow 144 can recover energy through the turbine 114 of the turbo compressor, since the two turbines are arranged on a common shaft 118.

[0041] The common shaft 118 of the turbo compressor is supported by two hydro-hydraulic bearings 120. The drive motor 110 is arranged between the bearings, and the components of the drive motor generate heat during operation, which must be dissipated.

[0042] Water from the water tank 130 can be supplied to the hydrohydraulic bearing 120 via a fluid-through connecting pipe 134 by means of a pump 132. In the case of a hydrohydraulic bearing 120 under static pressure, pressure is established in the bearing clearance around the shaft by means of the pump 132, so that the shaft 118 of the turbine compressor can be rotatably supported.

[0043] Water flowing into bearing 120 passes through the bearing and through liquid cooling circuit 122, which is provided for cooling the turbo compressor. This liquid cooling circuit 122 can also be used to supply air to the cathode side 140 of the fuel cell stack via supply section 124. Here, supply section 124 can supply water to a humidifier located within the air supply section for the cathode side 41 of the fuel cell stack. The passageway for the liquid cooling circuit of the turbo compressor can also be located on the pressure side of the bearing assembly. Water available from water tank 130 for the hydrohydraulic bearing can be condensate from the air mass flow 144 originating from the cathode side of the fuel cell stack 140. For this purpose, a condenser can be located within the air mass flow 144, and the condensate can be guided to water tank 130 via a fluid-through conduit 136.

[0044] Figure 2 Details of the bearing assembly 120 in system 200 are shown. In addition to the bearing assembly 120, system 200 also has a turbine compressor shaft 118 and a water tank 130.

[0045] Here, water from tank 130 is guided into bearing clearance 156 via fluid-permeable connecting pipe 134, so that the pressure required for the shaft 118 supporting the turbine compressor is established there, either by means of the rotating shaft 118 (in the case of a hydrodynamic bearing) or by means of a pump 132 arranged in connecting pipe 134. This water guided through bearing clearance 156 can be supplied via connecting pipe 122 as described above, either to cathode airflow 142 and / or to liquid cooling circuit 122 of the turbine compressor, the connecting pipe being connected to the bearing opening in the region of bearing clearance 156.

[0046] The bearing clearance 156 is sealed by two seals, each having two sealing elements 152 and 154. The outermost sealing element 154 is loaded with gas from the turbine compressor to seal the bearing.

[0047] An opening is provided between two sealing elements 152 and 154, spaced apart to form a cavity with the shaft 118. This opening guides any water entering the cavity into the water tank 130 via a fluid-permeable connection 158. Because the outer sealing element 154 is loaded with gas from the turbine compressor, water passing through the inner sealing element 152 is guided into the water tank 130 through the opening in the cavity between the two sealing elements 152 and 154. This results in a particularly good seal for the bearing assembly, which is especially important to prevent water from entering the turbine of the hydrohydraulic bearing, thus avoiding droplet impact.

Claims

1. A bearing assembly (200) for a shaft (118) of a turbine compressor, comprising: At least one water-hydraulic bearing (120) is configured to rotatably support the shaft (118) of the turbine compressor, wherein, The water-hydraulic bearing (120) surrounds the shaft (118) on its circumference to form a bearing clearance (156) between the water-hydraulic bearing and the shaft; and wherein the water-hydraulic bearing (120) is configured to allow water to flow through the bearing clearance (156) so as to hydraulically support the shaft (118); and Two seals are provided for sealing the bearing clearance (156) relative to the shaft (118); and wherein the two seals are loaded with gas from the turbine compressor outside the bearing clearance (156) for sealing the bearing (120).

2. The bearing assembly (200) according to claim 1, wherein, Each seal has two sealing elements (152, 154) that form a cavity with the bearing (120) and the shaft (118); and wherein the bearing (120) has an opening between the two sealing elements (152, 154) to fluidly connect the cavity to the water tank (130).

3. The bearing assembly (200) according to claim 1 or 2, wherein, A corresponding gas sealing device with an intermediate space relative to each seal is arranged outside the two seals, the gas sealing device being configured to seal the bearing clearance (156) relative to the shaft (118), and the hydrohydraulic bearing (120) being configured to load the gas of the turbine compressor onto each seal outside the bearing clearance (156) by means of the intermediate space.

4. The bearing assembly (200) according to claim 1 or 2, wherein, The bearing gap (156) is configured for fluid connection with a water tank (130) to provide water to the bearing gap (156).

5. The bearing assembly (200) according to claim 4, wherein, The water tank (130) includes a pump (132) for pumping water from the water tank (130) into the bearing clearance (156).

6. The bearing assembly (200) according to claim 1 or 2, wherein, The water-hydraulic bearing (120) is a hydrodynamic bearing and is configured to draw in water for the bearing clearance (156).

7. The bearing assembly (200) according to claim 1 or 2, wherein, Water flowing out from the bearing assembly (200) is used to humidify the air supplied to the cathode of the fuel cell system via the turbo compressor.

8. The bearing assembly (200) according to claim 1 or 2, wherein, Water flowing from the bearing assembly (200) is used to cool components of the fuel cell system.

9. The bearing assembly (200) according to claim 6, wherein, The water used for the hydrodynamic bearing includes condensate from the fuel cell system.

10. An application of a bearing assembly (200) according to any one of the preceding claims, the bearing assembly being used to support the shaft (118) of a turbo compressor, the turbo compressor being a component of a fuel cell system.

11. A turbo compressor having a bearing assembly (200) according to any one of claims 1 to 9, wherein, The turbo compressor has a liquid cooling circuit (122), and water flowing in and / or out of the bearing clearance (156) is guided through the liquid cooling circuit (122) to dissipate heat from the motor of the turbo compressor.

12. A cathode circuit of a fuel cell stack, comprising a turbo compressor according to claim 11 and a humidifier for humidifying the cathode air, wherein, The cathode circuit is configured to supply water flowing from the bearing assembly (200) to the humidifier.

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