Side channel compressor, fuel cell system and method of assembling side channel compressor

Abstract

The invention relates to a side-channel compressor for a fuel cell system for compressing a fluid, comprising a housing having a housing upper part and a housing lower part, the housing upper part having a bearing journal extending along a rotational axis, the bearing journal having a housing lower part, and the housing lower part having a bearing journal extending along a rotational axis. The bearing journal has a journal root section and a journal main section, a first bearing and a second bearing are arranged on the journal main section, a compressor wheel assembly having a compressor wheel is arranged in the housing on the bearing outer ring in a rotatable manner about the axis of rotation, and the compressor wheel assembly is arranged in the housing on the bearing outer ring in a rotatable manner about the axis of rotation. According to the invention, the side channel compressor has a journal tensioning section, the journal main section being arranged between the journal root section and the journal tensioning section, and the housing upper part being at least indirectly tensioned with the bearing via a central screw.

Description

Technical Field

[0001] The invention relates to a side channel compressor for a fuel cell system for conveying and / or compressing a gaseous medium, in particular hydrogen, which is in particular provided for use in a vehicle with a fuel cell drive. In addition, the invention relates to a fuel cell system having a side channel compressor according to the invention. In addition, the invention relates to a method for assembling a side channel compressor. Background Art

[0002] In the field of vehicles, in addition to liquid fuels, gaseous fuels will also play an increasingly important role in the future. Especially in vehicles with fuel cell drives, it is necessary to control the hydrogen gas flow. Here, the airflow is no longer discontinuously controlled as when injecting liquid fuel, but the gaseous medium is taken out from at least one high-pressure tank and guided to the delivery device via the inflow pipeline of the medium-pressure pipeline system. The injector unit guides the gaseous medium to the fuel cell via the connecting pipeline of the low-pressure pipeline system. After the gaseous medium flows through the fuel cell, the gaseous medium is guided back to the injector unit via the recirculation pipeline. Here, a side channel compressor can be connected in the middle, which assists gas recirculation in terms of flow technology and efficiency technology. In addition, the side channel compressor is used to assist the flow construction in the fuel cell drive, especially in the case of (cold) starting of the vehicle after a certain parking time. The side channel compressor is usually driven by an electric motor, which is powered by the vehicle battery when running in the vehicle.

[0003] DE 10 2018 222 102 A1 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 having an upper housing part and a lower housing part, wherein the upper housing part has a bearing journal extending along the axis of rotation, the bearing journal having a journal root section and a journal main section. Here, a first bearing and a second bearing are arranged on the journal main section, wherein a compressor wheel assembly having a compressor wheel is arranged in the housing on a bearing outer ring in a manner that can rotate around the axis of rotation. In addition, the side channel compressor has a journal tensioning section, wherein the journal main section is arranged between the journal root section and the journal tensioning section, wherein the upper housing part is at least indirectly tensioned with the bearing via a central screw. Here, a bearing stop disk is arranged between the screw head and the corresponding bearing.

[0004] The side channel compressor known from DE 10 2018 222 102 A1 may have certain disadvantages. When using a central screw (the diameter of the central screw in the area of ​​its screw shaft is smaller than the diameter in the threaded area), in particular during assembly, the bearing stop disk is not guided radially from the shaft area with a reduced diameter in the area of ​​its inner diameter with respect to the rotation axis of the central screw. Here, the inner diameter of the bearing stop disk must be much larger than the outer diameter of the shaft area, because otherwise, the bearing stop disk cannot be put on via the threaded area. At least the centered assembly of the bearing stop disk and possibly other used disks is not guaranteed, because the central screw may clamp the bearing stop disk on one side and may also deform the bearing stop disk. The diameter of the shaft area of ​​the central screw is smaller than the diameter of the threaded area. Therefore, the centering of the disk cannot be achieved. In order to achieve the best force introduction during the assembly process, the bearing stop disk should be centered. Here, the one-sided force introduction of the bearing pre-tensioning force via the central screw by means of the tightening torque can cause the deformation of the bearing journal. This can lead to an increased probability of failure of the bearing and thus of the entire side channel compressor. Summary of the invention

[0005] According to the invention, a side channel compressor for conveying and / or compressing a gaseous medium, in particular hydrogen, is provided for a fuel cell system.

[0006] The invention relates to a side channel compressor for compressing a fluid for a fuel cell system, a method for assembling a side channel compressor, and a fuel cell system having a side channel compressor. Further features and details of the invention are apparent from the description and the drawings. Features and details described in the context of the side channel compressor according to the invention are of course also applicable in the context of the fuel cell system according to the invention, and vice versa, so that reference is always made to one another or can be made to one another with regard to the disclosure of the individual inventive aspects.

[0007] According to a first aspect of the present invention, a side channel compressor for a fuel cell system is provided, the side channel compressor being used for compressing a gaseous medium. The side channel compressor has a housing, the housing having an upper housing part and a lower housing part, wherein the upper housing part has a bearing journal extending along an axis of rotation, the bearing journal having a journal root section and a journal main section, wherein a first bearing and a second bearing are arranged on the journal main section, wherein a compressor wheel assembly having a compressor wheel is arranged in the housing on a bearing outer ring in a manner rotatable about the axis of rotation, wherein the side channel compressor has a journal tensioning section, wherein the journal main section is arranged between the journal root section and the journal tensioning section, wherein the upper housing part is at least indirectly tensioned to the bearing via a central screw.

[0008] The housing is formed by an upper housing part and a lower housing part. According to the invention, it can be provided, but not necessarily required, that the upper housing part and / or the lower housing part have further housing parts, which can be designed in particular as a housing cover, a housing wall or the like. Preferably, a preassembled assembly of the side channel compressor with a bearing device and a compressor wheel assembly is defined by the upper housing part and the body part. A working chamber for the compressor wheel assembly is formed by the housing, preferably by the mutual cooperation of the upper housing part and the lower housing part.

[0009] Preferably, the working chamber is designed to be fluid-tight, except for the gas inlet opening and the gas outlet opening. In the context of the invention, fluid-tight is also understood to mean that the tightness is maintained at an operating pressure of the side channel compressor that is higher than the ambient pressure. In order to ensure the tightness, preferably a sealing device, such as a sealing ring, in particular a sealing ring made of silicone or rubber or the like, is arranged between the housing upper part and the housing lower part. Preferably, the housing upper part is formed essentially or predominantly from aluminum. Preferably, the housing lower part is formed essentially or predominantly from aluminum.

[0010] The bearing journal is designed as a sub-region of the housing upper part and extends away from the inner wall of the housing upper part. According to the invention, the bearing journal is designed integrally with the housing upper part. Alternatively, the bearing journal can also be arranged on the housing upper part in a material-locked manner (for example, by welding) or in a force-locked manner (for example, by screwing or pressing). The bearing journal extends from the inner wall of the housing upper part from the journal root section via the journal main section to the journal end section.

[0011] The side channel compressor has an inner bearing ring and an outer bearing ring. Preferably, a plurality of rolling bodies, such as balls, rollers, cylinders or the like, are arranged between the inner bearing ring and the outer bearing ring in order to support the outer bearing ring on the inner bearing ring as free of play as possible and to ensure relative rotation between the inner bearing ring and the outer bearing ring.

[0012] The bearing inner ring of the bearing device is arranged on the main section of the journal, preferably with a loose fit. It is also possible to arrange a plurality of bearing inner rings on the main section of the journal, preferably each with a loose fit. The loose fit is preferably designed in such a way that when the tension is released, an easy movement of the bearing device on the bearing journal is ensured, for example manually, and a tilting of the bearing inner ring on the bearing journal is prevented.

[0013] The compressor wheel assembly is arranged on the bearing outer ring of the bearing device, preferably with a press fit. The press fit is preferably designed in such a way that a displacement of the compressor wheel assembly on the bearing device is prevented in a force-locking manner. Alternatively, the compressor wheel assembly can be arranged on the bearing outer ring with a loose fit and can be secured by a retaining device to prevent axial slipping from the bearing device.

[0014] According to the invention, the side channel compressor is designed such that the central screw has a screw head, a screw shank and a threaded area, wherein the screw shank has a centering area with an increased diameter D1 and a shank area with a reduced diameter D2, wherein the centering area is arranged adjacent to the screw head, and wherein the bearing stop disk is located between the head of the central screw and the inner ring of the corresponding bearing in the direction of the rotation axis and / or abuts against the head and the inner ring in the direction of the rotation axis. The bearing stop disk has an inner diameter d4, and wherein, in particular in the journal tensioning section, the outer diameter D1 at least approximately corresponds to the inner diameter d4. In this way, the following advantage can be achieved: when the bearing stop disk is mounted, the centering area with the increased diameter D1 can be used to center the bearing stop disk on the screw shank of the central screw, because the bearing stop disk with its inner diameter d4 abuts against the outer diameter of the central screw in the radial direction around the rotation axis and is thus guided. Thus, it can be ensured that the bearing stop disk is mounted on the central screw together with the bearing journal and the corresponding bearing in a centered manner, so that the central screw does not unilaterally clamp the bearing stop disk and therefore does not deform the bearing stop disk. In addition, the advantages of optimal force introduction during the assembly process can be achieved by means of the configuration according to the invention of the side channel compressor and / or the central screw and / or the bearing stop disk, in that the bearing stop disk is centered on the screw shaft, especially in the centering area, and thus on the one hand, a tilting of the bearing stop disk is prevented. On the other hand, by means of the tightening torque, a uniform force introduction of the bearing preload via the central screw can be ensured via the surrounding contact area of ​​the bearing stop disk with the head of the central screw and / or with the end face of the corresponding bearing inner ring, especially 360° around the axis of rotation. Here, the bearing preload acting on the corresponding bearing acts from the bearing stop disk to the bearing in the axial direction with respect to the axis of rotation. Here, deformation of the bearing journal is prevented. This may ensure faster and safer assembly and thus may reduce assembly costs and / or may reduce the probability of failure of the bearing and thus of the entire side channel compressor.

[0015] According to an advantageous embodiment of the side channel compressor, the spacer sleeve is located between the bearing stop disk and the end face of the bearing journal in the direction of the rotation axis, in particular in the inner diameter of the bearing inner ring, and / or abuts against the bearing stop disk and the end face in the direction of the rotation axis. The spacer sleeve has an inner diameter d5, and wherein, in particular in the journal tensioning section, the outer diameter D1 at least approximately corresponds to the inner diameter d5. In this way, the following advantage can be achieved: when the bearing stop disk is mounted, the spacer sleeve can be centered on the screw shaft of the central screw by means of the centering region with the increased diameter D1, because the spacer sleeve with its inner diameter d5 abuts against the outer diameter of the central screw in the radial direction around the rotation axis and is thus guided. It can thus be ensured that the spacer sleeve is mounted on the central screw together with the bearing journal and the corresponding bearing in a centered manner, so that the central screw does not jam the spacer sleeve on one side and thus does not deform the spacer sleeve. In addition, the advantages of an optimal force introduction during assembly can be achieved by means of the configuration according to the invention of the side channel compressor and / or of the central screw and / or of the spacer sleeve, in that the spacer sleeve is centered on the screw shaft, in particular in the centering area, and thus on the one hand, a tilting of the spacer sleeve is prevented. On the other hand, by means of the tightening torque, a uniform force introduction of the bearing preload via the central screw and the bearing stop disk can be ensured via the surrounding contact area of ​​the spacer sleeve with the end face of the bearing stop disk and / or with the bearing journal, in particular 360° around the axis of rotation. In this way, deformation of the bearing journal is prevented. In addition, by means of the centering of the spacer sleeve in the centering area of ​​the central screw, the safety against self-loosening of the central screw can be increased. In addition, by arranging the spacer sleeve in the inner ring of the bearing, a compact structural shape of the side channel compressor can be achieved.

[0016] According to an advantageous development of the side channel compressor, the central screw has a conical guide region between the centering region and the shaft region. In this way, the following advantages can be achieved: for example, when preassembling the central screw together with the bearing stop disk and the spacer sleeve, it is possible to slide the bearing stop disk and the spacer sleeve onto the centering region in an improved manner. In this case, the guide region extends conically at an angle α to the axis of rotation. Thus, an increase in safety can be achieved during preassembly, wherein a faster and safer preassembly of the central screw with the bearing stop disk and the spacer sleeve can be ensured, and thus the assembly costs can be reduced and / or the probability of failure of the bearing and thus the entire side channel compressor can be reduced.

[0017] According to an advantageous development of the side channel compressor, the central screw has a recess in the transition area from the screw head to the centering area. In this way, the following advantages can be achieved: the bearing stop plate can be abutted against the screw head in an improved manner. Here, the recess can be used to prevent the bearing stop plate from being stuck and / or being put on on one side due to the transition radius between the screw shaft and the screw head of the central screw. Thus, a uniform abutment of the end face of the screw head with the bearing stop plate can be ensured. This leads to a reduction in the probability of failure of the side channel compressor, because the bearing stop plate abuts better against the screw head due to the recess, which can achieve increased safety against self-loosening of the central screw. Thus, the service life of the bearing can be increased and the service life of the side channel compressor can be increased.

[0018] According to a particularly advantageous embodiment of the side channel compressor, in the region of the journal root section, a spring element is arranged axially with respect to the rotation axis between the corresponding bearing inner ring and the end face of the housing upper part, which spring element can be tensioned with the bearing, in particular via a central screw. In this way, the following advantages can be achieved: by using the spring element, a constant bearing preload and / or bearing preload can be applied to at least one bearing and / or the bearing inner ring. In the case of the exemplary use of two bearings, wherein the two bearing inner rings are designed as floating bearings, the bearing inner ring of the first bearing can be loaded with a force at least indirectly in the axial direction with respect to the rotation axis by means of the central screw, and the bearing inner ring of the second bearing can be in contact with the spring element in the axial direction with respect to the rotation axis and loaded with a spring force by the spring element. In this case, an at least approximately constant bearing preload can be ensured, regardless of deviations in component tolerances and / or deviations due to temperature changes, which can lead to different component widths in the axial direction with respect to the rotation axis. The following advantages can thus be achieved: the probability of failure of the bearing and the side channel compressor can be reduced, thereby increasing the service life of the side channel compressor.

[0019] According to a particularly advantageous design of the side channel compressor, the width b1 of the spacer sleeve can be adjusted. In this way, the following advantages can be achieved: by changing the width b1 of the spacer sleeve, the screwing depth of the central screw into the internal thread of the bearing journal can be changed, thereby increasing or reducing the bearing pretensioning force. The smaller the width b1 of the spacer sleeve, the greater the bearing pretensioning force acting on the bearing by means of the central screw and the corresponding pretensioning force. The greater the width b1 of the spacer sleeve, the smaller the bearing pretensioning force acting on the bearing by means of the central screw and the corresponding pretensioning force. Thus, existing tolerance fluctuations of the component rolling bearing and / or the spring element and / or the housing can be compensated. In addition, this has the advantage that by simple means and in a cost-effective manner, the pretensioning force can be particularly simply and specifically set or limited by selecting a suitable spacer sleeve. Thus, production tolerances can be compensated and excessive pretensioning forces can be avoided. In addition, the following advantages can be achieved in this way: an optimal bearing pretensioning force can be achieved by corresponding pairing of the component groove and the clamping ring. Therefore, the service life of the bearing may be increased and the service life of the entire side channel compressor may be increased.

[0020] According to a particularly advantageous development of the side channel compressor, the spacer disk is located between the bearing outer ring of the first bearing and the bearing outer ring of the second bearing. This has the advantage that pivoting of the compressor wheel assembly about the axis of rotation R can be avoided more effectively by simple means and in a cost-effective manner. As a result, the wear of the bearing arrangement can be reduced and the service life of the bearing arrangement can be increased. In addition, the smooth running of the side channel compressor can be improved in this way.

[0021] According to an advantageous development, a method for assembling a side channel compressor is provided. In this case, a central screw having a screw shank with a centering region is provided. Then, a bearing stop disk is placed onto the centering region of the central screw, in particular via an optional conical guide region, and a spacer sleeve is placed onto the centering region of the central screw via a conical guide region to form a central screw assembly. Then, the compressor wheel assembly is placed onto the bearing journal of the housing upper part. In a last step, the preassembled assembly having the central screw, the bearing stop disk and the spacer sleeve is screwed to the bearing journal of the housing upper part and thus to the compressor wheel assembly.

[0022] In the fuel cell system according to the invention, all the advantages that have been described for the side channel compressor according to the first aspect of the invention are produced. Therefore, compared with conventional fuel cell systems, the fuel cell system according to the invention has the following advantages: an improved arrangement of the bearing device on the bearing journal of the side channel compressor is ensured by simple means and in a cost-effective manner. By using a heating element in the area of ​​the journal root section in the immediate vicinity of the spring element, an improved cold start capability of the side channel compressor and / or the fuel cell system can be achieved, in that it can be ensured, for example, that the spring element is prevented from rotating together with the inner ring of the bearing, in that ice bridges are thawed and eliminated by means of a heating disk that can be heated. In addition, the fuel cell system according to the invention has a particularly simple assembly and disassembly of the side channel compressor and can therefore be assembled cost-effectively and is very maintenance-friendly. In addition, the fuel cell system according to the invention has particularly low operating noise.

[0023] The invention is not limited to the embodiments described herein and the aspects emphasized therein. On the contrary, numerous modifications within the scope given by the description are possible which are within the capabilities of a person skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

[0025] The accompanying drawings show:

[0026] Figure 1 shows a schematic cross-sectional view of a side channel compressor according to the invention,

[0027] Figure 2 In the cross-sectional view, the side channel compressor Figure 1 The side channel compressor has a compressor wheel assembly, a central screw and a bearing journal,

[0028] Figure 3 In the sectional view an enlarged schematic diagram of a central screw according to the prior art is shown,

[0029] Figure 4 In the sectional view an enlarged schematic representation of the central screw according to the invention is shown,

[0030] Figure 5 In the cross-sectional view, the side channel compressor Figure 2 The side channel compressor has a central screw, a bearing journal, a corresponding bearing, a bearing stop disk and a spacer sleeve,

[0031] Figure 6 A simplified schematic diagram is shown for illustrating a process flow diagram of the claimed method. DETAILED DESCRIPTION

[0032] From the basis Figure 1 A schematic sectional view of a side channel compressor 1 according to the invention can be seen in the schematic diagram of FIG.

[0033] Here, in Figure 1 , a side channel compressor 1 for a fuel cell system 31 for conveying and / or compressing a gaseous medium, in particular hydrogen, is shown having a housing 3 and a drive 6, wherein the housing 3 has a housing upper part 7 and a housing lower part 8. The housing 3 also has a compressor chamber 30, which extends around an axis of rotation 4 and has at least one circumferential side channel 19, 21, the side channel compressor having a compressor wheel 2 located in the housing 3, which is arranged rotatably around the axis of rotation 4 and is driven by the drive 6, wherein the compressor wheel 2 has blades 5 on its circumference which are arranged in the region of the compressor chamber 30, and the side channel compressor has a gas inlet opening 14 and a gas outlet opening 16, which are formed on the housing 3 and are fluidically connected to one another via the compressor chamber 30, in particular via at least one side channel 19, 21, wherein the side channel compressor 1 has at least one bearing 27, 47. Furthermore, the respective side channel 19 , 21 can be interrupted fluidically by means of an interruption region 15 , wherein the interruption region 15 is situated, for example, between the gas inlet opening 14 and the gas outlet opening 16 .

[0034] In addition, Figure 1 , the drive 6 is designed as an axial field electric motor 6 having a stator 11 and a rotor 17, wherein the stator 11 and the rotor 17 are designed in a disk-shaped manner around the rotation axis 4 and wherein the stator 11 is arranged next to the rotor 17 in the direction of the rotation axis 4. In this case, the rotor 17 can be located at least indirectly on the hub 23 of the compressor wheel 2. In addition, in Figure 1, the side channel compressor 1 has a stator chamber 42 and a rotor chamber 44, wherein the components of the drive 6 are at least partially arranged in these chambers 42, 44. Here, the housing upper part 7 has a continuous wall 29, which is located between the stator chamber 42 and the rotor chamber 44 and realizes the fluid separation of these chambers. In addition, the stator chamber 42 is at least partially surrounded and / or encapsulated by the stator housing 39. Here, the housing lower part 8 has a cylindrical bearing journal 12, wherein the bearing journal 12 has an outer circumferential surface on the side of the bearing journal facing away from the rotation axis 4. Here, the bearing journal 12 extends in the direction of the rotation axis 4 so that the outer circumferential surface of the bearing journal extends around the rotation axis 4, and wherein the first bearing 27 and / or the second bearing 47 are in contact with the outer circumferential surface of the bearing journal 12 in the radial direction with respect to the rotation axis 4. In addition, the compressor wheel 2 can be connected to the corresponding bearings 27, 47 via the hub disk 23 and the hub 9. Here, the hub 9 has an inner bore 24. Furthermore, the invention claims a fuel cell system 31 having a side channel compressor 1 according to the invention.

[0035] Figure 2 The side channel compressor 1 is shown in a sectional view. Figure 1 The side channel compressor shown in the fragment marked with II in FIG. 1 has a compressor wheel assembly 13, a central screw 25 and a bearing journal 12. It is shown here that at least one bearing 27, 47 is fixed to the bearing journal 12 at least indirectly, in particular in a form-fitting manner, by means of the central screw 25. It is also shown that the side channel compressor 1 has a housing 3 (in Figure 1), which has a housing upper part 7 and a housing lower part 8, wherein the housing upper part 7 has a bearing journal 12 extending along the rotation axis 4, the bearing journal having a journal root section 52 and a journal main section 50, wherein a first bearing 27 and a second bearing 47 are arranged on the journal main section 50. In this case, a compressor wheel assembly 13 with a compressor wheel 2 is arranged in the housing 3 on the bearing journal 12 in a manner rotatable about the rotation axis 4, wherein the side channel compressor 1 has a journal tensioning section 48, wherein the journal main section 50 is arranged between the journal root section 52 and the journal tensioning section 48. In this case, the compressor wheel assembly 13 can have the components compressor wheel 2, hub 9, screw 35, spring disk 40, first bearing 27, second bearing 47, spacer disk 37 and optionally segmented magnets and a return ring. In addition, the housing upper part 7 is at least indirectly tensioned to the bearings 27, 47 via a central screw 25. Here, the central screw 25 can be introduced and / or screwed into the bore 43 of the bearing journal 12 at least partially over its length in the direction of the rotation axis 4, wherein the bearing journal 12 has an internal thread in the region of the bore 43 of the bearing journal, into which the tightening element 25 is screwed. Here, the bearing stop disk 26 and / or the spacer sleeve 33 can bear against the central screw 25, in particular the screw head 38, at least indirectly.

[0036] In addition, Figure 2 , it is shown that in the region of the journal root section 52, a spring element 41 is arranged axially with respect to the rotation axis 4 between the corresponding bearing inner ring 22 and the end face of the housing upper part 7, which spring element can be tensioned with the bearing 27, 47, in particular via a central screw 25. Here, the corresponding bearing 27, 47 has a bearing outer ring 20 and / or a bearing inner ring 22. Here, the spring element 41 is arranged axially with respect to the rotation axis 4 next to the corresponding bearing inner ring 22, in particular annularly around the bearing journal 12, wherein the spring element 41 acts on the bearing inner ring 22 at least almost axially with respect to the rotation axis 4 and loads the bearing inner ring with a spring force. Here, the spring force also acts at least almost parallel to the rotation axis 4. In an exemplary embodiment, the spring element 41 is arranged on the side of the corresponding bearing 27, 47 facing away from the housing lower part 8, in particular between the corresponding bearing 27, 47 and the end face of the housing lower part 7. At least one bearing 27, 47 is fixed with its corresponding bearing inner ring 22 at least indirectly via a bearing stop disk 26 by means of a central screw 25 axially to the bearing journal 12 with respect to the rotation axis 4. Here, a spacer disk 37 can be arranged axially with respect to the rotation axis 4 between the bearing outer ring 20a of the first bearing 27 and the bearing outer ring 20b of the second bearing 47.

[0037] like Figure 2 As shown, in an exemplary embodiment of the side channel compressor 1, the spring element 41 can apply this type of force acting axially with respect to the rotation axis 4 to the compressor wheel structure group 13, in particular the bearing inner ring 22, and thereby press the entire compressor wheel structure group 13 against the bearing stop disk 26. This presupposes a floating bearing for the bearing inner ring 22, in particular a bearing gap. In order to minimize the tilting of the compressor wheel structure group 13, the gap between the bearing inner ring 22 and the bearing journal 12 should be as small as possible. Here, the corresponding bearings 27, 47 are located in a recess in the hub 9 and can be pressed into the recess in the hub 9. As shown Figure 2 As shown, the hub 9 is connected to the compressor wheel 2 by means of at least one spring disk 40 and at least one screw 35. In the illustrated exemplary embodiment of the side channel compressor 1 with a first bearing 27 and a second bearing 47, a spacer disk 37 can be located between the bearings 27, 47 in the direction of the axis of rotation 4, wherein the spacing between the bearings 27, 47 can be adjusted by means of the spacer disk 37.

[0038] Figure 3 In the sectional view, an enlarged schematic diagram of a central screw according to the prior art is shown. It is shown here that the central screw 25 has an enlarged screw head 38 and a screw shaft 49, wherein the two elements 38, 49 extend rotationally symmetrically about the axis of rotation 4. Here, the central screw 25 has a threaded area 51 in a sub-area of ​​the screw shaft 49 of the central screw, in particular in the area of ​​the central screw facing away from the screw head 38, and a smooth shaft area 53 in a further sub-area, in particular in the area of ​​the central screw facing the screw head 38. Here, the smooth shaft area 53 has a diameter D2, and the threaded area 51 has a diameter D3. Here, the diameter D2 of the smooth shaft area 53 is smaller than the diameter D3 of the threaded area 51.

[0039] Figure 4The sectional view shows an enlarged schematic view of a central screw 25 according to the invention. The central screw 25 has a screw head 38, a screw shank 49 and a threaded region 51, wherein the screw shank 49 has a centering region 10 with an increased diameter D1 and a shank region 53 with a reduced diameter D2, wherein the centering region 10 is arranged adjacent to the screw head 38. The central screw 25 has a threaded region 51 with a diameter D3 on a region of the screw shank 49 facing away from the screw head 38. The centering region 10 adjoins the screw head 38 in the direction of the rotation axis 4, and the shank region 53 is located between the centering region 10 and the threaded region 51, in particular between the centering region 10 and the threaded region 51 in the direction of the rotation axis 4. In the embodiment of the central screw 25 according to the invention, the diameter D1 of the centering region 10 is the largest diameter compared to D2 and D3, wherein the diameter D2 of the shank region 53 is smaller than the diameters D3 and D1.

[0040] In addition, Figure 4 4 shows that the central screw 25 has a conical guide region 18 between the centering region 10 and the shaft region 53, wherein the conical guide region 18 increases from the shaft region 53 to the centering region 10 and / or the conical guide region 18 extends at an angle α to the rotation axis 4. In this case, the conical guide region 18 can be used in a possible pre-assembly to improve the assembly and / or stringing of the bearing stop disk 26 and the spacer sleeve 33. In addition, the central screw 25 has a recess 28 in the transition region from the screw head 38 to the centering region 10. With the help of this recess 28, an optimal support of the screw head 38 in the direction of the rotation axis 4, for example, on the bearing stop disk 26, is produced. Without such a recess 28, the bearing stop disk 26 would be tilted at the transition radius between the end face of the screw head 38 and the centering region 10 in such a way that the bearing stop disk 26 no longer rests flatly and therefore almost completely on the end face of the screw head 38. Furthermore, the recess 28 reduces mechanical stresses in the component, in particular when the central screw 25 is screwed onto the bearing journal 12 with high torques.

[0041] Figure 5 The side channel compressor 1 is shown in a sectional view. Figure 2, which is a section marked with III in FIG. 4 , the side channel compressor has a central screw 25, a bearing journal 12, bearings 27, 47, a bearing stop disk 26 and a spacer sleeve 33. It is shown here that the bearing stop disk 26 is located between the head 38 of the central screw 25 and the inner ring 22 of the corresponding bearing 27, 47 in the direction of the rotation axis 4 and / or abuts against the head and the inner ring in the direction of the rotation axis 4. Here, the bearing stop disk 26 has an inner diameter d4 and the centering region 10 of the central screw 25 has an outer diameter D1, wherein, in particular in the journal tensioning section 48, the outer diameter D1 at least approximately corresponds to the inner diameter d4. Here, the bearing stop disk 26 can abut against the outer surface 32 of the centering region 10 radially and / or circumferentially with respect to the rotation axis 4 with a first inner surface 34 facing the central screw 25. Furthermore, the spacer sleeve 33 can abut against the outer surface 32 of the centering region 10 radially and / or circumferentially with respect to the rotation axis 4 with a second inner surface 36 facing the central screw 25.

[0042] In addition, Figure 5 , it is shown that the spacer sleeve 33 is located between the bearing stop disk 26 and the end face 45 of the bearing journal 12 in the direction of the rotation axis 4, in particular in the inner diameter of the bearing inner ring 22, and / or is in contact with the bearing stop disk and the end face in the direction of the rotation axis 4. The spacer sleeve 33 has an inner diameter d5, wherein, in particular in the journal tensioning section 48, the outer diameter D1 of the centering region 10 of the central screw 25 at least approximately corresponds to the inner diameter d5. The bearing stop disk 26 has such a large diameter that it covers the bearing inner ring 22, in particular orthogonally to the rotation axis 4, and can therefore transmit forces to the bearing inner ring 22 in the axial direction with respect to the rotation axis 4. In addition, the bearing stop disk 26 is in contact with the end face 45 of the bearing journal 12 in the direction of the rotation axis 4, at least indirectly via the spacer sleeve 33. Now, by machining the spacer sleeve 33 before assembly, a bearing prestressing force of the respective bearing 27, 47 can be achieved, in particular by means of a bearing prestressing force. In this case, the width b1 of the spacer sleeve 33 can be adjusted. The greater the width b1 of the spacer sleeve 33 is, the smaller the bearing prestressing force that can be achieved and acts on the respective bearing 27, 47.

[0043] Figure 6 A simplified schematic diagram is shown for explaining the process flow diagram of the claimed method. The method is used for assembling a side channel compressor 1 and may include the following steps, in particular an assembly step:

[0044] - providing 101 a central screw 25 having a screw shank 49 with a centering region 10,

[0045] - sliding the bearing stop disk 26 onto the centering region 10 of the central screw 25 102 , in particular via the optional conical guide region 18 , and sliding the spacer sleeve 33 onto the centering region 10 of the central screw 25 102 via the conical guide region 18 , in order to form a central screw assembly,

[0046] - Put the compressor wheel assembly 13 onto the bearing journal 12 of the upper housing part 7 103,

[0047] The preassembled assembly, which has the central screw 25 , the bearing stop disk 26 and the spacer sleeve 33 , is screwed 104 to the bearing journal 12 of the housing upper part 7 and thus to the compressor wheel assembly 13 .

Claims

1. A side channel compressor (1) for a fuel cell system (2), the side channel compressor being used for compressing a fluid, the side channel compressor having a housing, the housing having an upper housing part (7) and a lower housing part (8), wherein: The housing upper part (7) has a bearing journal (12) extending along the rotation axis (4), the bearing journal having a journal root section (52) and a journal main section (50), wherein a first bearing (27) and a second bearing (47) are arranged on the journal main section (50), wherein a compressor wheel assembly (13) having a compressor wheel (2) is arranged in the housing (3) on the bearing journal (12) in a manner rotatable about the rotation axis (4), wherein the side channel compressor (1) has a journal tensioning section (48), wherein the journal main section (50) is arranged between the journal root section (52) and the journal tensioning section (48), wherein the housing upper part (7) is at least indirectly tensioned to the bearings (27, 47) via a central screw (25), characterized in that the central screw (25) It has a screw head (38), a screw shank (49) and a threaded area (51), wherein the screw shank (49) has a centering area (10) and a shank area (53), the centering area having an increased diameter (D1) and the shank area having a reduced diameter (D2), wherein the centering area (10) is arranged adjacent to the screw head (38), and wherein a bearing stop disk (26) is located between the head (38) of the central screw (25) and the inner ring (22) of the corresponding bearing (27, 47) in the direction of the rotation axis (4) and / or abuts against the head and the inner ring in the direction of the rotation axis (4), wherein the bearing stop disk (26) has an inner diameter (d4), and wherein, in particular in the journal tensioning section (48), the outer diameter (D1) at least approximately corresponds to the inner diameter (d4).

2. The side channel compressor (1) according to claim 1, characterized in that The spacer sleeve (33) is located between the bearing stop disk (26) and the end face (45) of the bearing journal (12) in the direction of the rotation axis (4), in particular within the inner diameter of the bearing inner ring (22), and / or abuts against the bearing stop disk and the end face in the direction of the rotation axis (4), wherein the spacer sleeve (33) has an inner diameter (d5) and wherein, in particular in the journal tensioning section (48), the outer diameter (D1) at least approximately corresponds to the inner diameter (d5).

3. The side channel compressor (1) according to claim 1 or 2, characterized in that: The central screw (25) has a conical guide region (18) between the centering region (10) and the shaft region (53).

4. A side channel compressor (1) according to any one of the preceding claims, characterised in that The central screw (25) has a recess (28) in the transition region from the screw head (38) to the centering region (10).

5. A side channel compressor (1) according to any one of the preceding claims, characterised in that In the region of the journal root section (52), a spring element (41) is arranged axially with respect to the rotation axis (4) between the corresponding bearing inner ring (22) and the end face of the housing upper part (7), the spring element being able to be tensioned with the bearing (27, 47), in particular via the central screw (25).

6. The side channel compressor (1) according to claim 2, characterized in that The width b1 of the spacer sleeve (33) can be adjusted.

7. A side channel compressor (1) according to any one of the preceding claims, characterised in that The spacer disk (37) is located between the bearing outer ring (20a) of the first bearing (27) and the bearing outer ring (20b) of the second bearing (47).

8. A method for assembling a side channel compressor (1) according to any one of the preceding claims, comprising the following steps: - providing (101) a central screw (25) having a screw shank (49) with a centering region (10), - sliding (102) the bearing stop disk (26) onto the centering region (10) of the central screw (25), in particular via an optional conical guide region (18), and sliding (102) the spacing sleeve (33) onto the centering region (10) of the central screw (25) via the conical guide region (18) to form a central screw assembly, - Slide the compressor wheel assembly (13) onto the bearing journal (12) of the housing upper part (7) (103), - Screwing (104) a preassembled assembly having a central screw (25), a bearing stop disk (26) and a spacer sleeve (33) to the bearing journal (12) of the housing upper part (7) and thus to the compressor wheel assembly (13).

9. A fuel cell system (31) having a side channel compressor (1) according to any one of claims 1 to 8, wherein: The side channel compressor (1) is arranged in the anode circuit of the fuel cell system (31).

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