Media gap motor, fuel cell system and use

Abstract

The present application also relates to a media gap motor (10) and to a fuel cell system (1) including the media gap motor (10). The present application additionally relates to the use of the media gap motor (10) and the fuel cell system (1). The proposed media gap motor (10), for example for the fuel cell system (1), comprises a shaft (15) in which a rotor magnet (22) is housed. The media gap motor (10) additionally comprises a stator with a stator winding (23) for electrically driving the rotation of the shaft (15). The media gap motor (10) further comprises a housing (26) defining a flow space (12) formed between the shaft (15) and the stator. The media gap motor (10) further comprises an impeller (13) disposed in the flow space (12) and on the shaft.

Description

[Technical field]

[0001] The present application relates in particular to a media gap motor for a fuel cell system and to a fuel cell system including a media gap motor. The present application additionally relates to the use of the media gap motor and the fuel cell system. [Background technology]

[0002] Vehicles are known that have a fuel cell system that provides electric driving force. Typically, a hydrogen-oxygen fuel cell with a proton exchange membrane is used here. The fuel here is hydrogen, which is supplied to the anode side of the fuel cell via an anode circuit. The oxidant here is oxygen, which is supplied to the cathode of the fuel cell via a cathode circuit, where it reacts with the fuel to produce energy. For example, publication DE 10 2016 015 266 A1 describes a related type of prior art, in which an air supply device with a turbine wheel and an impeller is arranged in the cathode circuit. Here, an air bearing performs the role of both radial and axial bearings. Summary of the Invention

[0003] In contrast, it is an object of the present application to propose an improved media gap motor and an improved fuel cell system and their uses. In particular, it is an object of the present application to propose a media gap motor that ensures high efficiency with a particularly compact and durable construction and at the same time is relatively easy to manufacture. Furthermore, it is an object of the present application to propose a correspondingly advantageous fuel cell system and a correspondingly advantageous use.

[0004] These objects are achieved by a media gap motor having the features of claim 1 and by a fuel cell system and a use having the features of the further claims. Advantageous developments can be found in the features of the dependent claims and exemplary embodiments.

[0005] A proposed media gap motor, e.g. for a fuel cell system, has a shaft in which a rotor magnet is housed. The media gap motor additionally has a stator having a stator winding for electrically driving the rotation of the shaft. The stator winding and the rotor magnet may cooperate for this purpose. The media gap motor further has a housing defining a flow space formed between the shaft and the stator. The media gap motor further has an impeller arranged in the flow space and on the shaft.

[0006] In an advantageous embodiment, the media gap motor may have a retaining rib extending in the flow space for radial support of the shaft between the housing and the shaft. The retaining rib therefore generally forms a radial bearing for the shaft or a part of a radial bearing for the shaft. By providing a retaining rib extending in the flow space, it is possible to ensure that the media gap motor is particularly robust and durable. Typically, the retaining rib is located completely in the flow space. Generally, the retaining rib has an axial end located upstream and an axial end located downstream, where both ends are located in the flow space, for example the medium to be transmitted flows around them. In some embodiments, a second radial bearing for the shaft may be provided, and in some embodiments the shaft may be located in the housing of the media gap motor. Generally the medium to be transmitted does not flow around the second radial bearing for the shaft. By providing a retaining rib in the flow space, the second radial bearing may be formed with a relatively small space and low complexity. The retaining rib therefore also has the advantage that the media gap motor is particularly robust, small, space-saving and of a relatively simple structure.

[0007] In some embodiments, the retaining rib is arranged upstream of the impeller. This allows a particularly robust construction to be achieved. The retaining rib may radially support the shaft, for example in the region of the axial end of the shaft, in particular upstream. For example, it may be provided such that the impeller is accommodated in a radially widened portion of the flow space. In some embodiments, the retaining rib may be arranged in a portion of the flow space that is relatively narrow.

[0008] Some embodiments of the media gap motor have a turbine wheel. The turbine wheel may be arranged on the shaft. Typically, the housing defines a further flow space. The turbine wheel may be arranged in the further flow space. An additional retaining rib may also be provided. The additional retaining rib may extend in the further flow space between the housing and the shaft in order to radially support the shaft. The additional retaining rib therefore generally forms an additional radial bearing for the shaft or a part of an additional radial bearing for the shaft. The embodiment with the retaining rib and the additional retaining rib is particularly advantageous here, since it results in a particularly compact and stable construction. The provision of the retaining rib and the additional retaining rib results in a stable radial support of the shaft in the flow space and in the further flow space, so that an additional radial bearing in the housing or outside the flow space is generally not required, whereby a small overall size may be achieved. The flow space and the further flow space are generally fluidly separated from each other. For this purpose, a fluid seal may be provided around the shaft in the region between the impeller and the turbine wheel. A radial bearing between the impeller and the turbine wheel can be provided, but in contrast to the prior art DE 10 2016 015 266 A1, in most embodiments this is not necessary at all, since for example the radial support is usually sufficiently provided by the retaining ribs and further retaining ribs in the respective flow spaces, which means that no additional installation space is required for complex bearing technology.

[0009] In some embodiments, the turbine wheel is arranged between the further retaining rib and the impeller, which generates a robust and at the same time space-saving configuration. In some embodiments, it is provided that the impeller and the turbine wheel are arranged between the retaining rib and the further retaining rib, which allows a particularly robust support and high stiffness to be achieved through the retaining rib and the further retaining rib. The retaining rib and the further retaining rib may each act on one of two parts of the shaft arranged at opposite ends of the shaft.

[0010] By providing a turbine wheel, part of the energy of the medium flowing out through the further flow space can be used to drive the impeller. The drive of the impeller can be implemented or assisted by the stator winding and rotor magnet of the media gap motor. In particular, it can be advantageous for the media gap motor to start the impeller electrically, in order to increase the efficiency of the media gap motor. In an embodiment with a turbine wheel, the flow space can form part of the intake system and the further flow space part of the outlet system. By driving the turbine wheel in the outlet system, the medium pressure in the intake system can be increased so that the media gap motor supplies more medium and the efficiency can be increased. In the case of application of the media gap motor for a fuel cell system, for example the hydrogen pressure in the hydrogen supply line for the fuel cell can be efficiently increased in this way.

[0011] The rotor magnet is typically accommodated in a portion of the shaft that is arranged in the flow space. An additional rotor magnet may also be provided that is accommodated in another portion of the shaft, for example in a portion of the shaft that is arranged in the additional flow space. However, in some embodiments, it may be provided that the rotor magnet is accommodated in the additional flow space or in a portion of the shaft that is arranged outside the flow space. In embodiments with an additional rotor magnet accommodated in a portion of the shaft that is arranged in the additional flow space, an additional stator winding may be provided that is configured to cooperate with the additional rotor magnet to electrically drive the rotation of the shaft. This embodiment is particularly well balanced and allows for a robust arrangement in which the resulting rotation of the shaft is driven by the intended current flow in the first and second stator windings and thus by the action on different axial portions of the shaft. It may be provided that the additional retaining ribs are arranged in the additional flow space such that they have an axial overlap with the additional rotor magnet and / or the additional stator winding. This allows for a particularly robust arrangement to be achieved.

[0012] In some embodiments, the retaining ribs are configured to generate vortices in the medium transmitted in the flow space. In this way, the retaining ribs can for example form a leading grid upstream of the impeller and / or a trailing grid downstream of the impeller to generate vortices in the medium transmitted. For this purpose, it can be provided that the retaining ribs or at least a part of the retaining ribs are angled to generate vortices. For example, the retaining ribs extend at an angle to the axial direction such that vortices are generated in the medium transmitted as a result of said medium flowing against the retaining ribs. In this way, the flow characteristics can be optimized by the retaining ribs. In this case, the impeller blades are exposed to a different flow compared to a non-angled retaining rib, which means that a higher efficiency of the media gap motor can be achieved. It can therefore be particularly advantageous if the retaining ribs are arranged upstream of the impeller. The retaining ribs therefore also have the function of generating vortices in the medium. In particular, in conjunction with the droplet separator described below, the generation of vortices in the medium can be particularly advantageous as explained below.

[0013] The retaining ribs are generally accommodated in a flow space such that the medium flows through the retaining ribs from the upstream end of the retaining rib to the downstream end of the retaining rib. The flow space may be at least partially or completely formed by a gap between the shaft and the housing, in particular a substantially hollow cylindrical gap. The retaining ribs may be arranged evenly or regularly along the circumference. In a typical embodiment, the media gap motor has at least two or at least three and / or up to 24 retaining ribs in a flow space along the circumference. A space is generally formed between adjacent retaining ribs through which the entire medium to be transmitted or at least a part of the medium to be transmitted flows. In a typical embodiment, the retaining ribs are axially long and extend axially. In addition, in a typical embodiment, the retaining ribs extend substantially radially between the shaft and the housing. As a rule, the coils or windings of the stator, and in particular solid objects, are not arranged in the gap through which the medium flows. The gap is typically limited on both sides in the circumferential direction by the retaining ribs. In the radially outer region, the gap is usually limited by the inner wall of the housing. The size of the gap through which the medium flows is generally at least a quarter, in particular at least half and / or at most eight times, in particular at most four times, the outer diameter of the shaft in the axial region where the retaining ribs are arranged. It can be provided that the stator windings are arranged beyond the radial seal of the flow space, whereby both the magnetic flux and the flow characteristics can be optimized.

[0014] For example, it may be provided that the retaining ribs and / or the bearing parts connected to the retaining ribs form a radial air bearing for the shaft. However, it is also possible that the retaining ribs and / or the connected bearing parts form a radial bearing in contact with the shaft. The bearing parts may connect two or more retaining ribs. The bearing parts are typically retained by the retaining ribs. The bearing parts may be a sleeve, for example a cylindrical sleeve in particular. The sleeve may in particular entirely surround the shaft. It is possible that the sleeve is connected to a radially inner part of the retaining ribs. In some embodiments, it may also be provided that the gap is defined in the radially inner region by the sleeve.

[0015] In some embodiments, the media gap motor has a portion for axial support of the shaft. The portion may be embodied as a part of the retaining rib or may be connected to the retaining rib. In particular, a portion in the radially inner region of the retaining rib may be embodied as a part of the retaining rib or may be connected to the retaining rib. The portion may be formed, for example, as a part of the sleeve described above. The portion may, for example, surround the shaft for axial support or have a protrusion that engages with the shaft for axial support. In particular, the portion may be provided to partially or completely surround the axial end of the shaft. In some embodiments, the portion for axial support of the shaft is provided to act on a surface of the shaft, for example having a surface perpendicular to the axial direction. The surface of the shaft may, for example, be an end surface of the shaft. In this embodiment, the surface may define the axial end of the shaft. The bearing portion may also be provided to act on a step of the shaft, for example having a surface perpendicular to the axial direction. The portion is usually connected to at least one of the retaining ribs. The retaining rib may therefore also have the function of contributing to the axial support of the shaft.

[0016] As mentioned, the rotor magnet is typically housed in a portion of the shaft that is arranged in the flow space. In a typical embodiment, the rotor magnet may be arranged upstream of the impeller, in particular in a narrower portion of the flow space. It may further be provided that the retaining ribs are arranged such that they have an axial overlap with the rotor magnet and / or the stator winding. In this way, a compact construction with a relatively short axial length may be achieved. In this way, the retaining ribs may also be used to achieve an efficient cooling of the stator via the medium flow, since the medium has a larger wall contact in the area of ​​the rotor magnet and / or the stator winding. In a particularly preferred embodiment, the retaining ribs optimize the magnetic flux and form an active part of the magnetic circuit formed by the rotor magnet and the stator winding. For example, it may be possible for the retaining ribs to continue the stator teeth in the flow space, i.e. thus improving the magnetic flux in a particularly advantageous manner. The magnetic field may now be induced from the stator winding, which may be arranged outside the flow space, via the retaining ribs, radially through the flow space to the rotor. The retaining ribs may have magnetically conductive properties for this purpose. For example, the retaining ribs may have the stator laminations. The stator may also have the stator laminations. It is possible that the retaining ribs continue the stator laminations into the flow spaces. The retaining ribs and the stator laminations may be formed as an integral stator lamination core with the individual laminations, i.e. as a continuous stator lamination core, especially with respect to the individual laminations. This means that the retaining ribs, in addition to their function of supporting the shaft, may also contribute to improving the magnetic flux. The retaining ribs may here be used to focus the magnetic flux lines from the stator to the rotor magnets and reduce leakage losses.

[0017] A suitable length of the retaining rib in the axial direction is generally at least 5 mm and / or at most 150 mm, in particular at most 100 mm. The radial extent of the retaining rib in the flow passage is generally at least 5 mm and / or at most 250 mm, in particular at most 150 mm. The width of the retaining rib in the circumferential direction may be at least 0.5 mm and / or at most 10 mm, in particular at most 5 mm. In addition to possible stator laminations, the retaining rib is generally made of a non-magnetic conductive material such as plastic or aluminum alloy. Fixing methods for the retaining rib may be insert sleeves, glued / welded connections, caulking integrated into the stator housing and / or injection molded components.

[0018] In some embodiments, a media gap motor is provided in which the shaft has an integral stiffener. The stiffener may have a first portion and a second portion. The rotor magnet may be housed inside the first portion of the stiffener. Furthermore, the impeller may be disposed on the second portion of the stiffener. The first and second portions of the stiffener may be directly adjacent to each other or may be axially spaced apart. The impeller may for example be pressed against the second portion of the stiffener. For a particularly robust and kink-resistant configuration, it may be provided that the stiffener extends through the impeller and the second portion spans a large area of ​​the axial length of the impeller. For example, it may be provided that the stiffener extends through the impeller and the second portion spans at least two-thirds, preferably the entire axial length of the impeller. Thus, in some embodiments, the second portion of the stiffener may be at least as long as the impeller in the axial direction. Advantageously, in some embodiments, the impeller may only be mounted on the stiffener and not on other components of the shaft. This simplifies production on the one hand and increases the stability of the shaft on the other hand. The stiffener is usually at least partially hollow on the inside to accommodate the rotor magnet. The shaft may also have a shaft rod housed in a cavity inside the stiffener. The rotor magnet may also be attached to the shaft rod. It may be provided that the shaft or the stiffener has a continuous cavity on its inside, i.e. in particular a cavity extending over the entire axial length of the shaft or the stiffener. Thus, in some embodiments, the shaft may be embodied as a hollow shaft. The rotor magnet and the shaft rod may be housed in a continuous cavity. In particular, it may be provided that a continuous cavity of the shaft or the stiffener, if provided, extends in at least one region from the impeller to the turbine wheel. The use of the described stiffener offers manufacturing advantages and results in a robust construction with particularly good bending behavior and low instability, which is particularly suitable for high-speed operation. The stiffener is usually made of a non-magnetic material.The integral embodiment of the reinforcement, i.e. in particular the component made of a continuous piece with certain material properties and / or the embodiment of the reinforcement as a non-bonded component, achieves particular advantages in terms of improved support of the impeller together with the rotor magnet. For example, the reinforcement can be made of steel, in particular chromium steel. If the reinforcement is made of a continuous steel part, this results in a torsion-resistant construction, in particular for the first and second parts housing the rotor magnet and the impeller. The impeller can be made of aluminum, for example.

[0019] In some embodiments, it is provided that the first part of the reinforcement has a larger outer diameter than the second part of the reinforcement. This means that the rotor magnet can be arranged in the part of the reinforcement with a larger diameter. This results in an improved stability with favorable flow efficiency and an improved magnetic efficiency. In particular, for this purpose, it can be provided that the rotor magnet and the impeller have a radial overlap, such that for example a part of the impeller and a part of the rotor magnet are arranged in the same radial position, but in different axial positions. In some embodiments, a region is formed between the first and second parts of the reinforcement, in which the outer diameter of the reinforcement for example decreases gradually, i.e. for example continuously. The outer diameter can for example increase continuously in a region in the direction of the first part, such that a maximum pitch angle of 70 degrees, in particular a maximum pitch angle of 50 degrees, is achieved. In this way, a robust and particularly hydraulically advantageous configuration can be achieved. In particular, edges at the transition between the first and second parts can be avoided. The region can be formed between the first part and the step mentioned below. In some embodiments, it may be provided that a region in which the outer diameter of the reinforcement is, for example, gradually or continuously reduced is formed between the first portion of the reinforcement and the step, for example there may be no step on the outside of the reinforcement, and in particular the shaft between the first portion of the reinforcement and the step.

[0020] In a particularly advantageous embodiment, the second part of the reinforcement ends in a step. The impeller may be in contact with the step. The step may limit the second part of the reinforcement, particularly in the direction of the first part. The step is usually formed in such a way that the outer diameter, which is smaller in the second part, increases beyond the step when viewed from the second part. Typically, the impeller is supported on the step. This allows forces resulting from a rocking movement of the shaft or the reinforcement to be absorbed in an advantageous manner. In this way, the stiffness of the shaft can be additionally increased. In a preferred embodiment, the reinforcement is embodied in such a way that a substantially flat, for example continuous, transition is created between the reinforcement and the impeller in the region of the step of the reinforcement. Thus, in general, the structure comprising the shaft and the impeller does not have a step on the radial outside of the structure in the region of the reinforcement step, resulting in a smooth transition in the outer shape. For this purpose, the height of the step of the reinforcement may correspond to the radial extent of the impeller bearing relative to the step. In this way, the flow characteristics can be improved on the one hand and the stability is further increased on the other hand.

[0021] The stiffener is particularly advantageous in combination with a retaining rib for radial support of the shaft, resulting in a particularly stable structure, especially when the retaining rib or an associated bearing part radially supports the shaft in the area of ​​the stiffener. However, the stiffener is advantageous in itself, even if no retaining rib is provided. For example, the present application may relate to a media gap motor, for example for a fuel cell system, comprising a shaft in which a rotor magnet is accommodated, a stator having a stator winding for electrically driving the rotation of the shaft, a housing defining a flow space formed between the shaft and the stator, an impeller arranged in the flow space and on the shaft, and an integral stiffener. The media gap motor may also have the advantageous features described above or below.

[0022] It may be provided that the media gap motor has a droplet separator. The droplet separator may be arranged in the flow space of the housing or in other embodiments in the further flow space. The droplet separator may be, for example, a water separator. The droplet separator may be used, for example, to separate liquid water from the medium flow. The droplet separator may be arranged on an inner wall of the housing that defines the flow space or the wider flow space or may be formed as part of the inner wall. In an advantageous embodiment, the droplet separator is arranged in a part of the flow space or the further flow space, in particular at the transition to the wider part of the flow space that accommodates the impeller or turbine wheel. The droplet separator is generally arranged axially between the retaining rib and the impeller, if provided, and / or between the rotor magnet and the impeller. The droplet separator may also be arranged axially between any further retaining ribs and the turbine wheel that are provided, and / or between the further rotor magnet and the turbine wheel. The droplet separator usually has an axial overlap with the shaft. In particular, by integrating the droplet separator into the media gap motor as described, a particularly compact configuration can be achieved, so that no further droplet separator is required. Here, for example, separation of liquid water from a channel of a fuel cell system for carrying fuel or oxidant, for example from a recirculation line, can be achieved in a particularly compact and efficient manner. For example, the droplet separator can be formed as a channel and / or an annular channel in which droplets are collected during operation. The droplet separator can be fluidly connected to a discharge line, so that the droplets can be discharged via the discharge line. In some embodiments, the droplet separator is arranged downstream of the retaining rib. In this way, a compact configuration can be achieved, which on the one hand provides a stable support for the shaft and on the other hand optimally uses the installation space in the flow path of the droplet separation. In principle, the droplet separator is arranged at least in part in an axial position located between the impeller and the rotor magnet and / or between the impeller and the retaining rib. This creates an optimized functionality in the flow space with a compact construction.

[0023] The droplet separator is particularly advantageous in combination with retaining ribs for radial mounting of the shaft, especially when the retaining ribs are set up to generate vortices in the medium to be conveyed, since this allows an optimized flow pattern to be set for droplet separation. However, even if no retaining ribs are provided, the droplet separator is advantageous in itself. For example, the present application may relate to a media gap motor, for example for a fuel cell system, comprising a shaft in which a rotor magnet is accommodated, a stator having stator windings for electrically driving the rotation of the shaft, a housing defining a flow space formed between the shaft and the stator, an impeller arranged in the flow space and on the shaft, and a droplet separator arranged in the flow space of the housing. The media gap motor may also have the advantageous features described above or below.

[0024] The present application may further relate to a fuel cell system comprising a media gap motor as described above or below. The fuel cell system may also have a channel for transmitting fuel. The flow space may form part of the channel for transmitting fuel. A channel may be set up to recirculate fuel, for example hydrogen, to and from the fuel cell. An impeller may be arranged in the channel for transmitting fuel. In this way, the media gap motor may be used to supply fuel to the fuel cell. As a result, the fuel supply or recirculation circuit may be precisely load-dependently controlled via a particularly durable media gap motor, which means that lower hydrogen consumption may be achieved. The fuel cell system may have a fuel cell and a media gap motor as described above or below, and, if necessary, a channel for transmitting fuel. In some embodiments, the fuel cell system is formed as part of a motor vehicle. The present application further relates to the use of a media gap motor as described above or below, or a fuel cell system as described above or below, for providing an electric driving force in a vehicle.

[0025] While the media gap motor and fuel cell system in the embodiments having the retaining ribs described are particularly advantageous, the present application may also relate to a fuel cell system having a media gap motor with a shaft in which a rotor magnet is housed, a stator having stator windings for electrically driving rotation of the shaft, and a housing defining a flow space formed between the shaft and the stator, and an impeller disposed in the flow space and on the shaft, without necessarily having the retaining ribs described above or below. The fuel cell system may additionally have any of the advantageous features described above or below.

[0026] The fuel cell system may have a channel for transmitting an oxidant, in particular oxygen. The channel may have an oxidant supply line for supplying the oxidant to the fuel cell. The channel may also have a discharge line for discharging the oxidant and / or reaction products, in particular water, from the fuel cell. The flow space in which the impeller is arranged may form part of the channel for transmitting the oxidant. The impeller may be arranged in the channel for transmitting the oxidant. In particular, the flow space in which the impeller is arranged may form part of the oxidant supply line. A further flow space in which a turbine wheel is arranged may form part of the discharge line.

[0027] The present application relates in a particularly advantageous manner to a media gap motor for a fuel cell application or system, but may also generally relate to a media gap motor having the advantageous features described above or below. For example, the present application may relate to a media gap motor. The media gap motor may have a stator as described, a rotor as described, and an impeller as described. The media gap motor may also include other advantageous features as described above or below. For example, the media gap motor may be a media gap motor for a turbocharger.

[0028] Features mentioned above or below with respect to the media gap motor are correspondingly transferable to the recirculation fan and its use, and to the fuel cell system, and vice versa. [Brief description of the drawings]

[0029] Exemplary embodiments are described below on the basis of the drawings, in which:

[0030] [Figure 1] FIG. 1 shows a schematic diagram of a fuel cell system including a media gap motor. [Diagram 2] FIG. 2 shows a schematic diagram of a media gap motor. [Diagram 3] 13 shows a schematic diagram of a media gap motor according to a further embodiment. [Figure 4] FIG. 2 shows a schematic diagram of a media gap motor. [Diagram 5] 13 shows a schematic diagram of a media gap motor according to a further embodiment. [Figure 6] 13 shows a schematic diagram of a media gap motor according to a further embodiment. [Figure 7] FIG. 2 shows a cross-sectional view of the shaft of the media gap motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] FIG. 1 shows a schematic diagram of a fuel cell system 1. The fuel cell system 1 is installed in a vehicle and is used to provide the vehicle with electric driving power. The fuel cell system 1 comprises a fuel cell 2, for example a hydrogen-oxygen fuel cell, with a cathode side 3 and an anode side 4. A cathode circuit is connected to the cathode side 3, via which the fuel cell 2 is supplied with oxygen, for example as oxidant. For this purpose, the cathode circuit comprises an oxidant supply line 5, in particular an air supply line (via which the oxidant, for example as a component of air, is supplied to the fuel cell 2), and an exhaust line 6, in particular an exhaust line (via which exhaust air and, if necessary, reaction products such as water are exhausted).

[0032] The anode side 4 of the fuel cell 2 is connected to a channel having a fuel supply line 7 and a fuel exhaust line 8. The channel is connected to a fuel source 9, for example a compressed gas storage tank for fuel, in particular hydrogen. Fuel is supplied to the anode side 4 of the fuel cell 2 via the fuel supply line 7. Residual fuel not consumed in the fuel cell 2 may be exhausted from the fuel cell 2 via the fuel exhaust line 8. The unused fuel may then be supplied back to the fuel supply line 7 and the anode side 4 of the fuel cell 2, possibly mixed with further fuel from the fuel source 9.

[0033] The fuel cell system 1 comprises a media gap motor 10 with a flow space 11 and a further flow space 12 which are shown diagrammatically in the drawings and which form part of an oxidant supply line 5 and a discharge line 6, respectively. An impeller 13 is housed in the flow space 11 and a turbine wheel 14 is housed in the further flow space 12, as will be explained in more detail below. In order to increase the efficiency of the cathode circuit, the impeller 13 and the turbine wheel 14 are connected to each other via a common shaft 15.

[0034] The fuel cell system 1 also comprises a further media gap motor 10' in the anode circuit, i.e. in the channel for directing the fuel or, more precisely, in the fuel discharge line 8 as part of the recirculation fan. The further media gap motor 10' has an impeller, described in more detail below or above, for conveying the fuel, which is arranged in the flow space of the further media gap motor 10'. A discharge line 16 is also connected to the further media gap motor 10', via which the separated water in the recirculation circuit can be discharged. For this purpose, the discharge line 16 is connected to a droplet separator 32, described in more detail below, which can be arranged in the flow space of the further media gap motor 10'.

[0035] FIG. 2 shows a schematic diagram of the media gap motor 10. Recurring features are designated with the same reference numerals in this and subsequent figures. The media gap motor 10 has a flow space 11 and a further flow space 12, which are defined by a common housing 26. An impeller 13 is disposed in the flow space 11. The flow space 11 has an oxidant inlet 17, through which air enters the flow space 11. The air is then compressed by the impeller 13 before it leaves the flow space 11 through an oxidant outlet 19 and is supplied to the cathode side 3 of the fuel cell 2. Unused oxidant and any reaction products then enter the further flow space 12 via an exhaust inlet 20 where they may drive a turbine wheel 14 before re-exiting the further flow space 12 via an outlet 21 of the further flow space 12.

[0036] The impeller 13 and the turbine wheel 14 are mounted on a shaft 15 and are thus connected to each other for combined rotation. The shaft 15 is embodied as a hollow shaft and has at its end a rotor magnet 22 arranged in the flow space 11, which can be driven by generating a current flow in a stator winding 23 of a stator with stator laminations. Correspondingly, a further rotor magnet 24 is accommodated at the further end of the shaft 15 in the further flow space 12, which can be driven by generating a current flow in a further stator winding 25 of a stator with stator laminations. In this way, charging can be improved by a balanced electric drive of the rotation of the shaft 15, so that an efficient fuel supply to the fuel cell 2 is achieved.

[0037] The shaft 15 is radially mounted in both opposite end regions in the media gap. For this purpose, the media gap motor 10 has a retaining rib 27 extending between the housing 26 and the shaft 15 in the region of the flow space 11, which is located between the stator winding 23 and the rotor magnet 22. Correspondingly, the media gap motor 10 has a further retaining rib 28 extending between the housing 26 and the shaft 15 in the region of the further flow space 12, which is located between the further stator winding 25 and the further rotor magnet 24. In some embodiments, the retaining rib 27 and / or the further retaining rib 28 are connected at their radially inner ends to associated cylindrical sleeves 29, 30, whereby a contacting radial bearing or a radial air bearing of the shaft 15 is achieved in cooperation with the retaining rib 27 and / or the further retaining rib 28. Between the impeller 13 and the turbine wheel 14, the housing 26 forms a liquid-tight seal of the flow spaces 11, 12 around the shaft 15. A stable radial mounting of the shaft 15 is generally not necessary at this point due to the radial mounting by the retaining ribs 27, 28. The cylindrical sleeve 29 also has a portion 31 for axial mounting of the shaft 15, which portion surrounds the axial end of the shaft 15.

[0038] In some embodiments, the retaining ribs 27 and further retaining ribs 28 may have stator laminations forming part of the stator laminations of the associated stator, extending them into the associated flow spaces 11, 12, so that the magnetic field generated by the associated stator windings 23, 25 to drive the shaft 15 is brought closer to the associated rotor magnets 22, 24.

[0039] Figure 3 shows a schematic diagram of a media gap motor 10 according to a further embodiment, which may be the further media gap motor 10' shown in figure 1. The media gap motor 10 substantially corresponds to the media gap motor 10 described above, but with a droplet separator 32 which may also be provided accordingly in the media gap motor 10 described above with reference to figure 2, in particular in the flow space 11 and / or the further flow space 12, but is preferably used in conjunction with an anode circuit as shown in figure 1 and a further media gap motor 10' arranged in its flow space 11. The droplet separator 32 comprises a circumferential channel formed in the inner wall of the housing 26 in the area axially located between the stator winding 23 and the impeller 13, in which any droplets present in the medium flow, in particular water droplets, are separated. The droplet separator 32 is thus arranged at the transition to the part 34 of the flow space 11 that accommodates the impeller 13, which is wider than the narrower part 33 of the flow space 11 that accommodates the retaining ribs 27. The droplets may flow along paths illustrated by arrows from the media flow to the inner wall of the housing 26, one of which is indicated by reference numeral 35. The droplet separator 32 is connected to the discharge line 16, so that the droplets may then be discharged from the flow space 11. In some embodiments, the retaining ribs 27 are angled (not shown in the illustrated schematic) so that they are curved in the flow direction. In this way, vortices may be generated in the media flow, thereby optimizing the angle of impact with the impeller 13 and the path of the droplets to the droplet separator 32.

[0040] 3, a cylindrical sleeve 29 at the radially inner end of the retaining rib 27 also serves to axially support the shaft 15 by acting on a step 36 of the shaft 15. In addition, a part of the housing 26 may form a further radial bearing 37 for the shaft 15.

[0041] A further schematic view of the media gap motor 10 is shown in FIG. 4, which illustrates the media gap motor 10, 10' described with reference to each of the figures described above, when viewed from the axial direction. The blades of the downstream impeller 13 are shown diagrammatically. A retaining rib 27 is arranged upstream of the impeller 13 and radially supports the shaft 15 together with a cylindrical sleeve 29. In the example shown, the retaining rib 27 is formed by three individual ribs 27', 27'', 27''', which are arranged equidistant from each other in the circumferential direction and extend between the housing 26 and the sleeve 29. Spaces 38, 38', 38'' are formed between adjacent ribs, through which, in the example shown, the entire medium to be transmitted flows.

[0042] 5 shows a schematic diagram of a media gap motor 10 according to a further embodiment. In this exemplary embodiment, the impeller 13 is arranged at the upstream end of the shaft 15. Adjacent to this downstream is a retaining rib 27 with a cylindrical sleeve 29 for radial support of the shaft 15. Downstream of this is arranged the rotor magnet 22, through which the shaft 15 can be driven in cooperation with the stator winding 23. This adjoins at its downstream end a further retaining rib 28 with a further cylindrical sleeve 30, which also radially supports the shaft 15. The sleeves 29, 30 also form an axial bearing for the shaft 15, in that the sleeves 29, 30 engage with parts of the shaft 15 on associated steps 36, 36', one of which is identified by reference number 31.

[0043] FIG. 6 shows a media gap motor according to a further embodiment. In this embodiment, a number of impellers 13, 13', 13'', 13''' are provided, which are arranged in the flow space 11 and fixed to the shaft 15 so as not to rotate. In addition to the retaining rib 27 and the further retaining rib 28 with associated sleeves 29, 30, further retaining ribs 28', 28'' with associated sleeves 30', 30'' are provided at different axial points for radial support of the shaft 15. The retaining ribs 27, 28, 28', 28'' are all arranged in the flow space 11. The shaft 15 can be driven via the rotor magnet 22 and the other rotor magnet 24 and the associated stator windings 23, 25.

[0044] FIG. 7 shows a cross-sectional view of the shaft 15 described in more detail above. The shaft 15 includes an integral stiffener 39 extending to an axial end 40 of the shaft. The stiffener 39 is made of chrome steel, for example, and has a first portion 41 and a second portion 42. The second portion 42 has a smaller outer diameter than the first portion 41, which ends in a step 43 that extends circumferentially around the shaft 15, which represents an upward step when looking from the second portion 42 to the first portion 41. In an exemplary embodiment, the second portion 42 is located downstream of the first portion 41. Between the first portion 41 and the second portion, and between the first portion 41 and the step 43, the outer diameter of the shaft 15 decreases in the direction of the second portion 42.

[0045] The stiffener 39 has a continuous cavity 44 having a first region 45 and a second region 46. In some embodiments, the cavity 44 extends through the entire shaft 15 and / or into the region of the turbine wheel 14 (if provided and described above) and / or further rotor magnets 24. The first region 45 of the cavity 44 is formed in a first portion 41 of the stiffener 39, while the second region 46 of the cavity 44 is formed in a second portion 42 of the stiffener 39. The rotor magnets 22 are housed in the first region 45 of the cavity 44. A shaft rod is housed in the second region 46 and may be connected to the rotor magnets 22.

[0046] The impeller 13, which may for example be made from aluminum, is arranged on the second part 42 of the stiffener 39, for example pressed against the stiffener 39, so that the impeller 13 rests particularly flat against a step 43 of the stiffener 39, in the example shown, against a surface of the step extending transversely to the axial direction, and is supported against the step 43. The inner diameter of the stiffener 39 in the first part 41, which accommodates the rotor magnet 22, is larger than the outer diameter of the stiffener 39 in the second part 42, in which the impeller 13 is arranged. In this way, the rotor magnet 22 can have an outer diameter larger than the inner diameter of the impeller 13, whereby a higher efficiency of the media gap motor can be achieved through advantageous magnetic and flow properties.

[0047] Only the features of the various embodiments disclosed in the exemplary embodiments can be combined with each other and claimed separately.

Claims

1. A shaft on which the rotor magnet is housed; a stator having stator windings for electrically driving rotation of said shaft; a housing defining a flow space formed between the shaft and the stator; and an impeller disposed in the flow space and on the shaft; Equipped with a retaining rib extending in the flow space between the housing and the shaft for radially supporting the shaft. Media gap motor.

2. 2. The media gap motor of claim 1, characterized by a turbine wheel disposed on the shaft, wherein the housing defines an additional flow space, the turbine wheel disposed in the additional flow space and including an additional retention rib extending into the additional flow space between the housing and the shaft for radially supporting the shaft.

3. The media gap motor of claim 2 , wherein the turbine wheel is disposed between the additional retention rib and the impeller.

4. The media gap motor of claim 2 , wherein the impeller and the turbine wheel are disposed between the retaining rib and the further retaining rib.

5. 3. The media gap motor of claim 2, further comprising: a further rotor magnet housed in a portion of the shaft disposed in the further flow space; and a further stator winding configured to cooperate with the further rotor magnet to electrically drive rotation of the shaft.

6. 6. The media gap motor of claim 5, wherein the further retention rib is disposed in the further flow space such that the further retention rib has an axial overlap with the further rotor magnet and / or the further stator winding.

7. 3. The media gap motor of claim 2, further comprising a portion for axially supporting the shaft, the portion being embodied as part of the retaining rib or connected to the retaining rib, the portion acting on a surface of the shaft to axially support the shaft.

8. The media gap motor of claim 1 characterized by a second radial bearing about the shaft, wherein the second radial bearing is disposed in the housing of the media gap motor.

9. 2. The media gap motor of claim 1, wherein the shaft has an integral stiffener with a first portion and a second portion, the rotor magnet is housed inside the first portion of the stiffener, and the impeller is disposed on the second portion of the stiffener.

10. 10. The media gap motor of claim 9, wherein the stiffener is embodied as a component made of a continuous piece with consistent material properties and as a non-bonded component, the stiffener being made of steel.

11. 10. The media gap motor of claim 9, wherein the stiffener extends through the impeller, the second portion spanning at least two-thirds of the axial length of the impeller.

12. The media gap motor of claim 9 , wherein the first portion of the stiffener has a larger outer diameter than the second portion of the stiffener.

13. The media gap motor according to claim 12 , wherein a region is formed between the first portion and the second portion of the reinforcement material where the outer diameter of the reinforcement material continuously decreases.

14. The media gap motor of claim 9 , wherein the second portion of the stiffener terminates in a step against which the impeller abuts.

15. 15. The media gap motor of claim 14, wherein the stiffener is embodied such that in the region of the step in the stiffener, a substantially flat transition between the stiffener and the impeller is provided.

16. The media gap motor of claim 1 , further comprising a droplet separator disposed in the flow space of the housing.

17. The media gap motor of claim 16 , wherein the droplet separator is disposed at a transition to a portion of the flow space that contains the impeller.

18. The media gap motor of claim 16 , wherein the droplet separator is disposed downstream of the retention rib.

19. The media gap motor of claim 1 , wherein the retaining ribs are configured to generate vortices in a medium conveyed in the flow space.

20. 20. The media gap motor of claim 19, wherein the retaining ribs extend at an angle relative to an axial direction such that vortices are generated in the transmitted media as a result of the media flowing against the retaining ribs.

21. The media gap motor of claim 19 , wherein the retention rib is located upstream of the impeller.

22. The media gap motor of claim 1 , comprising a portion for axially supporting the shaft, wherein the portion is embodied as part of the retaining rib or is connected to the retaining rib.

23. 23. The media gap motor of claim 22, wherein the portion acts on a surface of the shaft, e.g., having a surface perpendicular to the axial direction, to axially support the shaft.

24. The media gap motor of claim 1 , wherein the retention ribs are positioned such that they have axial overlap with the rotor magnet and / or the stator windings.

25. 25. The media gap motor of claim 24, wherein the retention ribs form an active portion of a magnetic circuit formed by the rotor magnet and the stator windings to optimize magnetic flux.

26. 26. The media gap motor of claim 25, wherein the retention rib has magnetic conductive properties.

27. A fuel cell system comprising the media gap motor according to any one of claims 1 to 26.

28. 28. The fuel cell system of claim 27, wherein the impeller is disposed in a channel for directing a fuel or in a channel for directing an oxidant.

29. 29. The fuel cell system of claim 28, wherein the media gap motor is a media gap motor as described in claim 2 and comprises an oxidant supply line for supplying an oxidant to the fuel cell and a discharge line for discharging oxidant and / or reaction products from the fuel cell, wherein the flow space in which the impeller is arranged forms part of the oxidant supply line and wherein the further flow space in which the turbine wheel is arranged forms part of the discharge line.

30. 28. Use of a media gap motor according to any one of claims 1 to 26 or a fuel cell system according to claim 27 to provide electric driving power in a vehicle.

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