US-12626934-B2 - Air supply apparatus for fuel cell systems, and fuel cell system

US12626934B2US 12626934 B2US12626934 B2US 12626934B2US-12626934-B2

Abstract

The invention relates to an air supply device for fuel cell systems with a flow compressor and an electric drive motor for the flow compressor, wherein the flow compressor has two compressor wheels which are essentially symmetrical and which are arranged, together with the electric drive motor there between, on a common shaft. The air supply device according to the invention is characterized in that the two compressor wheels are connected on the pressure side to two systems which are pneumatically not permanently connected. A fuel cell system which uses such an air supply device is also claimed.

Inventors

Philipp Hausmann
Oliver Harr
Benjamin Pieck

Assignees

CELLCENTRIC GMBH & CO. KG

Dates

Publication Date: 20260512
Application Date: 20210512
Priority Date: 20200515

Claims (1)

1 . An air supply device for fuel cell systems having a flow compressor and an electric drive motor for the flow compressor, wherein the flow compressor has two compressor wheels which are essentially symmetrical and which are arranged, together with the electric drive motor arranged there between, on a common shaft, characterized in that the two compressor wheels are connected on the pressure side to two systems that are pneumatically not permanently connected, wherein the two systems that are pneumatically not permanently connected systems are two fuel cell systems, and the two compressor wheels are configured to supply air to the two fuel cell systems, wherein the pneumatically not permanently connected systems are controllably connected via a bypass line provided with a valve, and wherein a device for supplying liquid into compressed air flow from the flow compressor is provided, which in particular has at least one nozzle for atomizing the liquid in the compressed air flow.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a national stage application under 35 U.S.C. 371 and claims the benefit of PCT Application No. PCT/EP2021/062565 having an international filing date of 12 May 2021, which designated the United States, and which PCT application claimed the benefit of German Patent Application No. 10 2020 206 162.9 filed 15 May 2020, the contents of each of which are incorporated herein by reference in their entireties. The invention relates to an air supply device for fuel cell systems according to the preamble of claim 1 and a fuel cell system which is supplied via this device. Fuel cell systems are known from the prior art. For their air supply, flow compressors are often used, some of which are electrically driven. It is very often the case that a turbine is arranged on one side of an electric motor and a compressor is arranged on the other side. This design, which is also known as an electric turbocharger or motor-assisted turbocharger, is often used because it is able to recover residual energy from the exhaust gases. However, it has the disadvantage that the bearings are loaded unevenly, since the forces acting in the region of the compressor and the forces acting in the region of the turbine sometimes differ greatly. This leads to increased friction in the region of the axial bearing. This means that very complex and expensive axial bearings are required, in the region of which undesirably high performance losses can hardly be avoided. Other structures can also be designed as two-stage compressors with an electric motor and two compressor wheels on the same shaft. DE 10 2010 035 725 A1 can be referred to as an example in this context. Here, too, the load on the axial bearing is relatively high, since there are different pressure conditions and forces on the different sides. In the document mentioned, an attempt is made to compensate for this via the wheel back parts of the compressor wheels. The generic WO 2019/096890 A2 solves this force imbalance by arranging two symmetrical compressor wheels on a common shaft with the electric drive motor. This allows the axial forces to be significantly reduced. Smaller axial bearings and much less friction in the region of these axial bearings are thus possible. Regarding further prior art, reference can also be made to the applicant's DE 101 20 947 A1, which describes the combination of an electrically driven flow compressor with a so-called freewheel, i.e. a freewheeling turbocharger with a turbine on one side and a compressor on the other side. The object of the present invention is now to specify an improved air supply device for fuel cell systems according to the preamble of claim 1 and, moreover, an improved fuel cell system using this air supply device. According to the invention, this object is achieved by an air supply device for fuel cell systems having the features of the claims. Advantageous refinements and developments of the air supply device result from the dependent claims. Advantageous refinements and developments of the fuel cell system result from the dependent claims. The air supply device for fuel cell systems provides, in a comparable way to the generic prior art, for a flow compressor which is driven by an electric drive motor. In this case, the flow compressor has two compressor wheels which are of essentially symmetrical design and are arranged on a common shaft together with the electric drive motor arranged there between. According to the invention, the two compressor wheels are connected to two systems that are not permanently connected pneumatically. This use of an electrically driven flow compressor with two substantially symmetrical compressor wheels in the manner described in the generic prior art enables the axial bearings to be significantly relieved, which simplifies their construction and reduces friction. In case of fuel cell applications in the automotive sector and power levels usually involved, up to 2 kW of power loss can be saved. The use of the generated air currents, in which the compressor wheels are connected to two different systems on the pressure side, which are not or at least not permanently connected pneumatically, has the decisive advantage that only part of the heat is introduced into both systems, while in case of merged pressure-side air conduits, this heat is jointly present in the components, which can very quickly lead to a thermal overload of the components in fuel cell systems. The air supply according to the invention can now be used in particular to supply air via the one common air supply device to two fuel cell systems that are separate from one another, as provided according to a very advantageous development of the air supply device. The separate fuel cell systems can be, for example, two systems of the same type that are combined with one another within a modular structure, for example in order to provide the drive power required for a commercial vehicle