Compressor wheel assembly, side channel compressor and method for assembling compressor wheel assembly, fuel cell system

Abstract

The invention relates to a compressor wheel assembly for a side channel compressor of a fuel cell system for conveying and / or compressing a gaseous medium, in particular hydrogen, the compressor wheel assembly being rotatably mounted about an axis of rotation and / or being driven by means of a drive, the invention relates to a compressor wheel assembly comprising a compressor wheel, by means of which a gas flow, in particular in a compressor chamber, can be generated, a hub having a first shoulder, a magnetic guide ring, and at least one bearing, the compressor wheel having an annular projection. According to the invention, the compressor wheel assembly has a pressing element, by means of which the hub and the compressor wheel are fixed to one another, in particular pressed against one another, and wherein a clearance fit is formed between the hub and the compressor wheel orthogonally to the axis of rotation, the pressing element resting with a first end face against a second end face of the compressor wheel, a pressing force acting at least parallel to the axis of rotation is transmitted to the compressor wheel.

Description

Technical Field

[0001] The invention relates to a compressor wheel assembly for a side channel compressor of a fuel cell system, a side channel compressor and a method for assembling a compressor wheel assembly for a side channel compressor of a fuel cell system. In addition, the invention also relates to a fuel cell system. Background Art

[0002] In addition to liquid fuels, gaseous fuels will also play an increasingly important role in the automotive field in the future. In particular, in vehicles with fuel cell drives, the hydrogen flow must be controlled. Here, the gas flow is no longer controlled discontinuously as when injecting liquid fuel, but the gaseous medium is extracted from at least one high-pressure tank and delivered to the injection unit through the inflow pipeline of the medium-pressure pipeline system. The injection unit guides the gaseous medium to the fuel cell through the connecting pipeline of the low-pressure pipeline system. After the gaseous medium flows through the fuel cell, it is guided back to the injection unit through the return pipeline. Here, a side channel compressor can be connected in the middle, which assists the gas return in terms of fluid technology and efficiency technology. In addition, the side channel compressor can also be used to assist the fluid establishment in the fuel cell drive, especially when the vehicle is (cold) started after a certain period of rest. These side channel compressors are usually driven by an electric motor, which is powered by the vehicle battery when running in the vehicle.

[0003] DE 10 2022 212 235, which has not yet been published, discloses a side channel compressor for a fuel cell system, in which a gaseous medium, in particular hydrogen, is conveyed and / or compressed. The side channel compressor has a housing and a drive, wherein the housing has a housing upper part and a housing lower part; a compressor chamber extending around a rotation axis in the housing, the compressor chamber having at least one circumferential side channel; and a compressor wheel located in the housing, which is arranged rotatably around the rotation axis and driven by the drive. In this case, the compressor wheel has blades arranged in the region of the compressor chamber on its circumference and has a gas inlet and a gas outlet respectively formed on the housing, which are fluidically connected to each other via the compressor chamber, in particular at least one side channel, wherein the side channel compressor has at least one bearing. In addition, DE 10 2022 212 235 also shows that a rotor assembly, which can be embodied as a permanent magnet, is located on a drive flange corresponding to the hub.

[0004] The side channel compressor known from DE 10 2022 212 235 may have certain disadvantages. The compressor wheel can be connected to the hub by means of a clearance fit. The clearance fit is produced here orthogonally to the axis of rotation between the inner diameter of the compressor wheel and the outer diameter of the hub, in particular the smaller outer diameter in the first shoulder area of ​​the hub, between the surfaces extending orthogonally to the axis of rotation. In an exemplary embodiment, the compressor wheel can be connected to the hub by means of a plurality of threaded connection elements, wherein the connection of the compressor wheel and the hub is formed parallel to the axis of rotation between two end faces of the hub and the compressor wheel extending orthogonally to the axis of rotation. The torque applied to the hub by the drive for driving the side channel compressor and from the hub to the compressor wheel is transmitted here only via the connection of the end faces. When using a plurality of threaded connection elements, the preload force applied to press the compressor wheel to the hub may not be large enough, especially due to the surface pressure of the two end faces, so that the compressor wheel moves on the hub. This may result in a corresponding axial gap between the compressor wheel and the first and / or second housing part in the compressor chamber area becoming smaller or larger, so that the compressor wheel collides with the housing parts, or the sealing of the side channels is no longer ensured and the delivery effect of the side channel compressor is thus reduced.

[0005] Furthermore, the position of the compressor wheel may change due to vibrations, wherein the compressor wheel assembly loses its balancing qualities. Large imbalances can also reduce the service life of the bearings and increase the probability of failure of the drive and thus the entire side channel compressor. These effects are intensified by the lack of support and / or guidance between the hub and the compressor wheel orthogonal to the axis of rotation. Summary of the invention

[0006] According to the invention, a compressor wheel assembly for a side channel compressor of a fuel cell system is provided, having the features of the independent patent claim, for conveying and / or compressing a gaseous medium, in particular hydrogen. In this case, the compressor wheel assembly is supported rotatably about an axis of rotation and / or can be driven by means of a drive, wherein the compressor wheel assembly has a compressor wheel, a hub, a magnetic guide ring, and at least one bearing, by means of which a gas flow can be generated in particular in a compressor chamber. The hub has a first shoulder and the compressor wheel has an annular shoulder.

[0007] With reference to claim 1, the compressor wheel assembly comprises a clamping element, wherein the hub and the compressor wheel are fixed to each other, in particular clamped, by means of the clamping element, and wherein a clearance fit is formed between the hub and the compressor wheel orthogonally to the axis of rotation, wherein the clamping element bears with a first end face against a second end face of the compressor wheel and transmits a clamping force acting at least parallel to the axis of rotation to the compressor wheel, wherein the end face extends annularly around the axis of rotation. In this way, the following advantages can be achieved: by using the clamping element, the preload force to be achieved, in particular the clamping force, can be increased, whereby the first end face is strongly pressed against the second end face by means of the preload force acting in the direction of the axis of rotation which is applied to the component hub and the compressor wheel by the clamping element, so that a reliable force-locking connection is formed between the hub and the compressor wheel.

[0008] Thus, due to the configuration of the compressor wheel assembly with the clamping element according to the invention, the effects of tilting or shifting of the compressor wheel on the hub can be prevented, so that the compressor wheel does not shift on the hub. Thus, with the configuration of the compressor wheel assembly according to the invention, it is possible to prevent the corresponding axial gap between the compressor wheel and the first and / or second housing part in the compressor chamber region from becoming smaller or larger, so that the compressor wheel collides with the housing parts or the sealing of the side channels is no longer ensured. Thus, due to the use of the compressor wheel assembly according to the invention and the use of the clamping element according to the invention, the conveying effect of the side channel compressor can be achieved.

[0009] Furthermore, by increasing the preload between hub and compressor wheel by using the clamping element according to the invention, it is possible to prevent the position of the compressor wheel on the hub from changing due to vibrations, wherein the compressor wheel assembly loses its balancing qualities. Large imbalances also reduce the service life of the bearings and increase the probability of failure of the drive and thus of the entire side channel compressor. This offers the advantage that the probability of failure of the compressor wheel assembly and / or the side channel compressor can be reduced, wherein the service life and efficiency of the side channel compressor can be increased. Furthermore, the assembly costs can be reduced, since the assembly complex consisting of compressor wheel and hub can no longer be realized by means of a plurality of screws and washers, but rather by means of a central clamping element. As a result, the number of required components and the number of assembly steps can be reduced, which leads to reduced assembly costs.

[0010] The measures listed in the dependent claims enable developments of the compressor wheel assembly and / or of the side channel compressor specified in claim 1. The dependent claims relate to preferred developments of the invention.

[0011] According to an advantageous configuration of the compressor wheel assembly, the clamping element has a sleeve-shaped forming part extending sleeve-shaped around the rotation axis and an annular forming part extending annularly around the rotation axis, so that the clamping element has, in particular, an L-shaped cross-sectional geometry. In this way, the following advantages can be achieved: a compact and space-saving implementation of the clamping element and the compressor wheel assembly with the clamping element can be achieved. Therefore, the entire side channel compressor can also be implemented more compactly and more space-savingly, especially compared to the prior art. In addition, the following advantages can be achieved: the maximum possible preload can be achieved with the clamping element, in that the clamping element can be fixed to the hub with the sleeve-shaped forming part, and the maximum possible preload can be transmitted from the clamping element to the compressor wheel with the aid of the annular forming part with a relatively large diameter, while the mechanical stresses of the components in the force flow can be kept as small as possible.

[0012] According to an advantageous extension of the compressor wheel assembly, the annular molded part extends with its first end face at a right angle, in particular 90°, to the axis of rotation. In addition, the annular molded part extends with its third end face at an angle α to the axis of rotation. In this way, the preload force to be achieved can be increased in that the annular molded part only rests against the second end face of the compressor wheel in the area of ​​its first end face, wherein the area of ​​the first end face has a larger diameter than the area of ​​the third end face. Thus, a compact structural form of the compressor wheel assembly can be achieved, thereby reducing the structural dimensions of the entire side channel compressor. This in turn can reduce the installation space required for the side channel compressor in the entire vehicle. In addition, an improved balancing quality of the compressor wheel can be ensured, thereby reducing the probability of failure of the side channel compressor.

[0013] According to a particularly advantageous configuration of the compressor wheel assembly, the clamping element is implemented as a clamping nut, which has an internal thread at least partially on its inner diameter, while the hub of the compressor wheel assembly has an external thread, in particular in the area of ​​the second shoulder, wherein the components are screwed to each other by means of the thread. In this way, an improved balancing quality of the compressor wheel assembly can be achieved, thereby reducing the probability of failure of the compressor wheel assembly and / or the bearings and / or the entire side channel compressor. By reducing the imbalance of the compressor wheel assembly, in particular the bearings are less loaded when operating at high speeds, thereby improving the service life of the bearings and thus the entire side channel compressor. In this way, the assembly costs and / or maintenance costs can be reduced, thereby reducing the manufacturing costs and / or operating costs of the compressor wheel assembly and thus the side channel compressor. In addition, a compact structural form of the compressor wheel assembly can also be achieved.

[0014] According to an advantageous configuration of the compressor wheel assembly, the clamping element has an elastic material, in particular spring steel, in the region of the annular forming part. In this way, the following advantages can be achieved: when tightening the clamping element and therefore when pressing the component hub and the compressor wheel, an increased preload can be achieved with the aid of the clamping element, because the clamping element is elastically deformable in the region of the annular forming part and can therefore load the clamping element with a greater tightening torque. Here, the preload acts in particular on the fourth and fifth end faces parallel to the axis of rotation and ensures that a form-locking component connection is reliably and stably formed. This provides a lower probability of failure of the compressor wheel assembly and therefore the entire side channel compressor and / or the entire fuel cell system. In addition, a reduction in the original imbalance is achieved, whereby the service life of the entire side channel compressor can be increased.

[0015] According to an advantageous development of the compressor wheel assembly, the clamping element has an external hexagon in the region of the outer diameter of the sleeve-shaped profiling. In this way, the following advantages can be achieved: by reliably loading the centering element with a tightening torque using standard tools, an improved assembly of the centering element can be achieved. The clamping element can thus be mounted quickly and cost-effectively on the hub, thereby enabling complete assembly of the compressor wheel assembly, thereby reducing assembly costs. In addition, large tightening torques can be reliably transmitted using the external hexagon without damaging the clamping element.

[0016] Furthermore, the centering element can be better positioned during assembly onto the outer diameter of the hub. Assembly errors are thus avoided, whereby the probability of failure of the compressor wheel assembly and thus of the entire side channel compressor can be reduced. Furthermore, a reduction in the initial imbalance is achieved, whereby the service life of the entire side channel compressor can be increased.

[0017] Since preferred areas of application of the compressor wheel assembly according to the invention are side channel compressors and / or fuel cell systems, a side channel compressor and / or a fuel cell system having a compressor wheel assembly according to the invention is also proposed.

[0018] According to an advantageous configuration, a method for assembling a side channel compressor is proposed. In this case, in a first method step, a hub having an external thread in the region of the second shoulder and a clamping element having an internal thread on its inner diameter are provided. Then, in a second method step, the clamping element is mounted on the hub. In a third method step, the clamping element is tightened to the hub so that the components are tightened to each other by means of the thread. In a fourth method step, the clamping element is loaded with a predetermined and / or maximum tightening torque so that the compressor wheel is loaded with a preload by the clamping element and pressed against the hub, forming a form-locking connection between the second end face of the compressor wheel and the third end face of the hub. In a fifth method step, the corresponding components of the compressor wheel assembly are magnetized.

[0019] According to a second aspect of the present invention, a fuel cell system is provided. The fuel cell system has a fuel cell having an oxygen inlet, a hydrogen inlet, an exhaust gas outlet, an anode, a cathode and an electrolyte. According to the present invention, the fuel cell system has a side channel compressor according to the present invention coupled to the exhaust gas outlet in fluid communication.

[0020] According to the present invention, the fuel cell can also be configured as a fuel cell stack consisting of a plurality of fuel cells. Preferably, the fuel cell stack has an exhaust gas outlet, and the side channel compressor according to the present invention is coupled to the exhaust gas outlet in fluid communication. The working chamber inlet of the side channel compressor is coupled to the exhaust gas outlet in fluid communication, so that the exhaust gas from the exhaust gas outlet can be supplied to the working chamber of the side channel compressor. Preferably, the fuel cell system has a water separator, which is preferably arranged upstream of the side channel compressor. The working chamber of the side channel compressor is preferably coupled to the hydrogen inlet in fluid communication, so that the hydrogen from the side channel compressor can be supplied to the fuel cell or the fuel cells of the fuel cell stack.

[0021] In the fuel cell system according to the invention, all the advantages described according to the first aspect of the invention with respect to the compressor wheel assembly and / or the side channel compressor are obtained. Therefore, compared with conventional fuel cell systems, the fuel cell system according to the invention has the following advantages: an improved compressor wheel assembly with a lower probability of failure can be manufactured by simple means and in a cost-effective manner. In addition, the fuel cell system according to the invention has particularly simple assemblability and disassembly of the compressor wheel assembly and / or the side channel compressor, and can therefore be assembled at low cost and very easy to maintain. In addition, the fuel cell system according to the invention has particularly low operating noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The invention is not limited to the embodiments described herein and the aspects emphasized herein. Rather, numerous modifications are possible within the scope given by the claims, which are within the capabilities of a person skilled in the art.

[0023] The present invention will be described in detail below with reference to the accompanying drawings.

[0024] The accompanying drawings show:

[0025] FIG1 : a schematic cross-sectional view of a side channel compressor according to the invention,

[0026] FIG2 : A schematic cross-sectional view of a compressor wheel assembly with a compressor wheel, a hub and a bearing according to the prior art,

[0027] Figure 3 : A schematic sectional view of a compressor wheel assembly according to the invention with a compressor wheel, a hub, a bearing and a pressing element,

[0028] Figure 4 : A compressor wheel assembly according to the invention having a hub, a compressor wheel and a pressing element Figure 3 A schematic cross-sectional view of the part indicated by II in FIG.

[0029] Figure 5 : A simplified diagram of a flow chart for visually illustrating the claimed method.

[0030] In Figures 1 to Figure 5 In the drawings, elements having the same function and mode of action are respectively provided with the same reference numerals. DETAILED DESCRIPTION

[0031] FIG. 1 schematically shows a side channel compressor 1 according to the prior art in a sectional view. The side channel compressor 1 comprises a housing having a first housing part 3 and a second housing part 4. The first housing part 3 has a bearing journal 5 extending in the direction of the second housing part 4 and a bearing arrangement 9 arranged on the bearing journal 5 and having two rolling bearings 19, 20. Here, the first bearing 19 and the second bearing 20 of the bearing arrangement 9 are arranged next to each other in the direction of the rotation axis 46. In addition, a spacer 15 is located between the rolling bearings 19, 20, wherein in particular the bearing outer rings 11a, b are in axial contact with the spacer 15 relative to the rotation axis 46. The bearing inner ring 8 of each bearing 19, 20 is arranged on the bearing journal 5. The compressor wheel assembly 10 having a compressor wheel 34 is arranged on the bearing outer rings 11a, b of each bearing 19, 20. In addition, the side channel compressor 1 has a compressor chamber 36 extending around the rotation axis 46, which has at least one surrounding side channel 35. The compressor wheel 34 is driven by a drive 37.

[0032] As shown in FIG. 1 , the side channel compressor has a blind hole in the bearing journal 5, in which a fastening element 28, in particular a pressure bolt 28, is arranged. The bearings 19, 20 are at least indirectly pressed against the first housing part 3 via the pressure bolt 28 and the spring element 18, wherein the first housing part 3 is at least indirectly pressed against the bearing arrangement 9 via the fastening element 28. Here, by screwing in the pressure bolt 28, a bearing pressure force acting parallel to the axis of rotation 46 is applied to the bearing arrangement 9. It is also shown that four axial gaps 33a, b, c, d are located in the direction of the axis of rotation 46 in the region between the compressor wheel assembly 10, in particular the compressor wheel 34, and the respective housing part 3, 4, wherein the axial gaps 33a, b, c, d seal the compressor chamber 36.

[0033] 1 , the drive 37 is implemented as an axial magnetic field motor 37 having a stator 37 , wherein a magnetic field is formed by energizing the stator 37 , and the magnetic field acts on the segmented magnets 42 of the compressor wheel assembly 10 , so that the compressor wheel assembly is set in a rotational motion. In this case, in an exemplary embodiment, the hub 7 may have a groove 45 extending annularly around the rotation axis 46 , wherein the component magnetic guide ring 40 and at least two segmented magnets 42 , ideally four segmented magnets 42 are at least almost completely located in the groove 45 .

[0034] FIG. 2 shows a schematic sectional view of a compressor wheel assembly 10 according to the prior art, which has a compressor wheel 34, a hub 7 and at least one bearing 19, 20. The compressor wheel assembly 10 shown here is a component of a side channel compressor 1 for a fuel cell system 2, which is used to convey and / or compress a gaseous medium, in particular hydrogen. Here, the compressor wheel assembly 10 is supported rotatably around an axis of rotation 46 and can be driven by means of a drive 37. Here, the compressor wheel assembly 10 has a compressor wheel 34, by means of which a gas flow can be generated, in particular in a compressor chamber 36. In addition, the compressor wheel assembly 10 also has a hub 7, a magnetic guide ring 40 and at least one bearing 19, 20. Here, the compressor wheel assembly 10 is suitable for a side channel compressor 1. The side channel compressor 1 is suitable for a fuel cell system 2 for conveying and / or compressing a gaseous medium, in particular hydrogen. Here, the compressor wheel assembly 10 can be supported rotatably around a rotation axis 46 and / or can be driven by means of a drive 37, wherein the compressor wheel assembly 10 has a compressor wheel 34, a hub 7, a magnetic guide ring 40 and at least one bearing 19, 20, with the aid of which an air flow can be generated in particular in the compressor chamber 36, wherein the hub 7 has a first shoulder 16 and the compressor wheel 34 has an annular protrusion 44.

[0035] Here, the hub 7 has a first shoulder 16 and the compressor wheel 34 has an annular shoulder 44, wherein the hub 7 and the compressor wheel 34 are screwed to each other by means of screws 39, in particular grub screws 39. During assembly, the compressor wheel 34 is inserted onto the hub 7 in the direction of the rotation axis 46 until the compressor wheel 34 has its fourth end face 41 (such as the annular projection 44) with its fourth end face 41 (such as the annular projection 44) of the compressor wheel 34. Figure 3 ) and the fifth end face 43 (as shown) of the first boss 16 of the hub 7 Figure 3The two components are then screwed together and the compressor wheel assembly 10 is formed. The compressor wheel assembly 10 according to the prior art has a clearance fit 38, wherein the clearance fit 38 is located orthogonally to the axis of rotation 46 between the outer diameter 13 of the first shoulder 16 of the hub 7 and the inner diameter 17 of the annular projection 44 of the compressor wheel 34. This clearance fit 38 is necessary because the materials used for the compressor wheel 34 and the hub 7 are different, for example, the compressor wheel 34 has aluminum and the hub 7 has stainless steel. In this case, different thermal expansions occur during the operation of the side channel compressor 1 due to different thermal expansion coefficients. If the two components 7, 34 are in contact with their respective inner and outer diameters 13, 17 and no clearance fit 38 is formed, such movement of the components can occur when passing through a wide temperature range, for example from 0°C to 80°C, which movement ultimately leads to failure of the screw connection, thereby damaging and failing the compressor wheel assembly 10. FIG. 2 further shows that the hub 7 has a groove 45 extending annularly around the axis of rotation 46 , wherein the component flux guide ring 40 and at least two segment magnets 42 , ideally four segment magnets 42 , are located at least almost completely in the groove 45 .

[0036] 2 furthermore shows that the bearing stop 12 can be located between the fastening element 28, in particular the enlarged screw head, and the bearing journal 5 and / or the respective bearing inner ring 8 in the direction of the rotation axis 46. Furthermore, the bearing stop 12 abuts against the flat surface of the bearing journal 5 at least indirectly via the spacer sleeve 14 in the direction of the rotation axis 46. By machining the spacer sleeve 14 before assembly, a bearing preload of the respective bearing 19, 20 can now be achieved, in particular by means of a bearing contact force.

[0037] exist Figure 3 , a schematic sectional view of a compressor wheel assembly 10 according to the invention is shown, which has a compressor wheel 34, a hub 7, bearings 19, 20 and a pressing element 24. It is shown here that the compressor wheel assembly 10 has a pressing element 24, wherein the hub 7 and the compressor wheel 34 are fixed to each other, in particular pressed, by means of the pressing element 24. Here, a clearance fit 38 is formed between the hub 7 and the compressor wheel 34 orthogonally to the axis of rotation 46, wherein the pressing element 24 rests with a first end face 21 against a second end face 23 of the compressor wheel 34 and transmits a pressing force 31 acting at least parallel to the axis of rotation 46 to the compressor wheel 34, wherein the end faces 21, 23 extend annularly around the axis of rotation 46. The pressing element 24 here has a sleeve-shaped forming part 6 extending sleeve-shaped around the axis of rotation 46 and an annular forming part 22 extending annularly around the axis of rotation 46, so that the pressing element 24 has, in particular, an L-shaped cross-sectional geometry.

[0038] The clamping element 24 can be designed as a clamping nut 24, which has an internal thread 32 at least partially on its inner diameter, while the hub 7 of the compressor hub assembly 10 has an external thread 26, in particular in the region of the second shoulder 48. The hub 7 and the clamping element 24 are screwed to each other by means of the threads 26, 32. In addition, the clamping element 24 can have an elastic material, in particular spring steel, in the region of the annular molded part 22. In addition, the clamping element 24 can have an assembly outer diameter 29, in particular an outer hexagon 29, in the region of the outer diameter of the sleeve-shaped molded part 6, so that the clamping element 24 can be assembled on the hub 7 more quickly and at a lower cost and a greater torque, in particular a tightening torque, of the clamping element 24 is allowed. In the state where the clamping element 24 is assembled on the compressor hub assembly 10, the rotational symmetry axis of the clamping element 24 is almost coaxial with the rotation axis 46.

[0039] As in Figure 3 As shown in , the compressor wheel 34 has a fourth end face 41 and the hub 7 has a fifth end face 43, wherein the end faces 41, 43 extend at least approximately orthogonally to the rotation axis 46 and abut against each other. By means of the tightening of the pressing element 24 to the hub 7, the compressor wheel 34 is pressed against the hub by means of the preload force 31. Here, the fourth end face 41 and the fifth end face 43 are pressed against each other at least approximately in the direction of the rotation axis 46, in particular by means of the preload force 31, so that a force-locking connection is formed between the compressor wheel 34 and the hub 7, and thus the compressor wheel 34 is prevented from moving on the hub 7, in particular orthogonally to the rotation axis. Here, the compressor wheel 34 is fixed and / or pressed with its annular projection 44 between the annular shaped part 22 of the pressing element 24 and the first shoulder 16 and / or the fifth end face 43 of the hub 7. The compressor wheel assembly 10, in particular the hub 7, the compressor wheel 34 and the pressing element 24, can be preassembled as an assembly complex and in an exemplary embodiment can also be preassembled with other components, such as at least part of the bearings 19, 20, so that simplified assembly of the individual components and subsequent magnetization of the assembly are achieved.

[0040] Figure 4 The compressor wheel assembly 10 according to the present invention is shown in FIG. Figure 3, the compressor wheel assembly has a hub 7, a compressor wheel 34 and a clamping element 24. It is shown here that the annular molded part 22 of the clamping element 24 has a first end face 21 and a third end face 27 on its side facing the compressor wheel 34 in the direction of the rotation axis 46. The first end face 21 is located in the outer area of ​​the annular molded part 22 facing the rotation axis 46, while the third end face 27 is located in the inner area of ​​the annular molded part 22 facing the rotation axis 46. Here, the first end face 21 extends at right angles, especially 90°, to the rotation axis 46 at least almost orthogonally. The third end face 27 extends at an angle α to the rotation axis 46, wherein the angle α can have a value of 90.01° to 110°. Here, the clamping element 24 is in contact with the second end face 23 of the compressor wheel 34 at least with a partial area of ​​its first end face 21 and thus transmits the preload force 31.

[0041] Furthermore, the compressor wheel 34 has a groove 47 in the region of the annular projection 44, wherein the groove 47 extends on the end side of the projection 44 facing the axis of rotation and is interrupted by a raised region on the side of the annular shaped part 22 facing away from the axis of rotation 46, which forms the second end face 23. Thus, the first end face 21 and the second end face 23 form a contact region extending annularly around the axis of rotation 46. The preload force 31 is transmitted from the pressure element 24 to the annular projection 44 of the compressor wheel 34 via this contact region. The preload force 31 is then transmitted from the fourth end face 41 of the annular shoulder 44 of the compressor wheel 34 to the fifth end face 43 of the hub 7, so that the two elements 7, 34 are connected to each other by a force-locking connection in the region of the end faces 41, 43.

[0042] Figure 5 A simplified diagram of a flow chart for intuitively illustrating the claimed method is shown. The method is used to assemble a compressor wheel assembly 10 for a side channel compressor 1 and / or a fuel cell system 2 and may include the following steps, in particular an assembly step:

[0043] - providing 101 a hub 7 having an external thread 26 in the region of the second shoulder 48 and a pressing element 24 having an internal thread 32 on its inner diameter;

[0044] - Mounting 102 the pressing element 24 on the hub 7;

[0045] - tightening 103 the pressing element 24 to the hub 7 so that the components 7 and 24 are tightened to each other by means of the threads 26 and 32;

[0046] The pressing element 24 is loaded with 104 a predetermined and / or maximum tightening torque, so that the compressor wheel 34 is loaded with a preload force 31 by the pressing element 24 and pressed against the hub 7 , thereby forming a positive connection between the fourth end face 41 of the compressor wheel 34 and the fifth end face 43 of the hub 7 .

[0047] - Magnetizing 105 the respective components 40, 42 of the compressor wheel assembly.

Claims

1. A compressor wheel assembly (10) for a side channel compressor (1) of a fuel cell system (2) for conveying and / or compressing a gaseous medium, in particular hydrogen, wherein: The compressor wheel assembly (10) is supported so as to be rotatable about an axis of rotation (46) and / or is drivable by means of a drive (37), wherein the compressor wheel assembly (10) comprises a compressor wheel (34), a hub (7), a magnetic guide ring (40) and at least one bearing (19, 20), by means of which a gas flow can be generated, in particular in a compressor chamber (36), wherein the hub (7) comprises a first shoulder (16) and the compressor wheel (34) comprises an annular projection (44), wherein the compressor wheel assembly (10) comprises a pressing element (24 ... The hub (7) and the compressor wheel (34) are fixed to each other, in particular pressed, by means of the pressing element (24), wherein a clearance fit (38) is formed between the hub (7) and the compressor wheel (34) orthogonally to the rotation axis (46), wherein the pressing element (24) abuts with a first end face (21) against a second end face (23) of the compressor wheel (34) and transmits a pressing force (31) acting at least parallel to the rotation axis (46) to the compressor wheel (34), wherein the end faces (21, 23) extend annularly around the rotation axis (46).

2. The compressor wheel assembly (10) according to claim 1, characterized in that The pressing element (24) has a sleeve-shaped forming part (6) extending sleeve-shaped around the rotation axis (46) and an annular forming part (22) extending annularly around the rotation axis (46), so that the pressing element (24) has an L-shaped cross-sectional geometry.

3. The compressor wheel assembly (10) according to claim 1 or 2, characterized in that: The annular molded part (22) extends with its first end face (21) at a right angle, in particular 90°, to the rotation axis (46) and with its third end face (27) at an angle (α) to the rotation axis (46).

4. The compressor wheel assembly (10) according to any one of the preceding claims, characterized in that The clamping element (24) is embodied as a clamping nut (24) which has an internal thread (32) at least partially on its inner diameter, while the hub (7) of the compressor wheel assembly (10) has an external thread (26), in particular in the region of a second shoulder (48), wherein the components (7, 24) are screwed to one another by means of the thread (26, 32).

5. The compressor wheel assembly (10) according to any one of the preceding claims, characterized in that The pressure element (24) comprises an elastic material, in particular spring steel, in the region of the annular molded part (22).

6. The compressor wheel assembly (10) according to any one of the preceding claims, characterized in that The pressing element (24) has an external hexagon in the region of the outer diameter of the sleeve-shaped profile (6).

7. A side channel compressor (1) having a compressor wheel assembly (10) according to any one of claims 1 to 6.

8. A fuel cell system (2) having a side channel compressor (1) according to claim 7, wherein: The side channel compressor (1) is arranged in the anode circuit of the fuel cell system (2).

9. A method for assembling a compressor wheel assembly (10) for a side channel compressor (1) or a fuel cell system (2) according to any one of the preceding claims, comprising the following steps: - providing (101) a hub (7) having an external thread (26) in the region of the second shoulder (48) and a pressing element (24) having an internal thread (32) on its inner diameter, - mounting (102) the pressing element (24) on the hub (7), - tightening (103) the pressing element (24) to the hub (7) so that the components (7, 24) are screwed to one another by means of the threads (26, 32), - loading (104) the pressing element (24) with a predetermined and / or maximum tightening torque, so that the compressor wheel (34) is loaded with a preload force (31) by the pressing element (24) and pressed against the hub (7), and thus a positive connection is formed between the fourth end face (41) of the compressor wheel (34) and the fifth end face (43) of the hub (7), - magnetizing (105) the respective components (40, 42) of the compressor wheel assembly.

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