Side channel compressor for a fuel cell system for conveying and / or compressing a gaseous medium, fuel cell system, method for assembling the side channel compressor

Abstract

The invention relates to a side-channel compressor (1) for a fuel cell system (2) for compressing a fluid, comprising a housing with a housing upper part (7) and a housing lower part (8), wherein the housing upper part (7) has a bearing journal (12) extending along an axis of rotation (4) with 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) with a compressor wheel (2) is rotatably arranged inside the housing (3) on a bearing outer ring (22a, b) about the axis of rotation (4), wherein the side-channel compressor (1) has a journal clamping section (48), wherein the journal main section (50) is arranged between the journal root section (52) and the journal clamping section (48), wherein the housing upper part (7) is at least indirectly clamped to the bearings (27, 47) via a central screw (25).

Description

[0001] The present 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 intended in particular for use in vehicles with a fuel cell drive. Furthermore, the invention relates to a fuel cell system with a side channel compressor according to the invention. Furthermore, the invention relates to a method for assembling the side channel compressor.

[0002] In the automotive sector, gaseous fuels will play an increasingly important role alongside liquid fuels in the future. Hydrogen gas flows must be controlled, particularly in fuel cell-powered vehicles. The gas flows are no longer controlled discontinuously, as is the case with liquid fuel injection; instead, the gaseous medium is taken from at least one high-pressure tank and fed to an ejector unit via an inlet line of a medium-pressure line system. This ejector unit feeds the gaseous medium to a fuel cell via a connecting line of a low-pressure line system. After the gaseous medium has flowed through the fuel cell, it is fed back to the ejector unit via a return line. A side channel compressor can be interposed to assist the gas recirculation in terms of flow and efficiency.Side channel compressors are also used to support the flow build-up in fuel cell propulsion, especially during a (cold) start of the vehicle after a certain period of inactivity. These side channel compressors are typically powered by electric motors, which are supplied with power from the vehicle battery during operation.

[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 comprises a housing with an upper housing part and a lower housing part, wherein the upper housing part has a bearing journal extending along a rotational axis and having a journal root section and a journal main section. A first bearing and a second bearing are arranged on the journal main section, wherein a compressor wheel assembly with a compressor wheel is arranged within the housing on an outer bearing ring so as to be rotatable about the rotational axis. In addition, the side channel compressor comprises a journal clamping section, wherein the journal main section is arranged between the journal root section and the journal clamping section, wherein the upper housing part is clamped at least indirectly to the bearings via a central screw.A bearing stop washer is arranged between a screw head and the respective bearing.

[0004] The side channel blower known from DE 10 2018 222 102 A1 can have certain disadvantages. When using the central screw, in which the central screw has a smaller diameter in the area of ​​its screw shaft than in a threaded area, the bearing stop disk is not guided radially to the rotation axis of the central screw in the area of ​​its inner diameter by a shaft area with a reduced diameter, especially during assembly. The inner diameter of the bearing stop disk must be much larger than the outer diameter of the shaft area, as otherwise it would not be possible to slide it over the threaded area. The centered assembly of at least the bearing stop disk and any other disks used is not guaranteed, because the central screw could clamp the bearing stop disk on one side and possibly even deform it. The shaft area of ​​the central screw has a smaller diameter than the threaded area.This makes centering the discs impossible. To achieve optimal force application during assembly, the bearing stop discs should be centered. However, a one-sided application of a bearing preload force via the central screw due to the tightening torque can lead to deformation of the bearing journal. This can increase the likelihood of bearing failure and thus the entire side channel blower. Disclosure of the inventionAdvantages of the invention

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

[0006] The present invention relates to a side channel compressor for a fuel cell system for compressing a fluid, having the features of independent claim 1, a method for assembling a side channel compressor, having the features of independent claim 8, and a fuel cell system with a side channel compressor, having the features of independent claim 9. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the side channel compressor according to the invention naturally also apply in connection with the fuel cell system according to the invention, and vice versa, so that reciprocal reference is or can always be made to the individual aspects of the invention with regard to the disclosure.

[0007] According to a first aspect of the invention, a side channel compressor for a fuel cell system for compressing a gaseous fuel is provided. The side channel compressor has a housing with an upper housing part and a lower housing part, wherein the upper housing part has a bearing journal extending along a rotational axis and 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 with a compressor wheel is arranged within the housing on an outer bearing ring so as to be rotatable about the rotational axis, wherein the side channel compressor has a journal clamping section, wherein the journal main section is arranged between the journal root section and the journal clamping section, wherein the upper housing part is clamped at least indirectly to the bearings via a central screw.

[0008] The housing is formed by the upper housing part and the lower housing part. According to the invention, it can be provided, but is not absolutely necessary, 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, housing wall, or the like. Preferably, the upper housing part defines a pre-assembled subassembly of the side channel compressor, which has a bearing device and the compressor wheel subassembly. A working space for the compressor wheel subassembly is formed by the housing, preferably through the interaction of the upper housing part with the lower housing part.

[0009] The working chamber is preferably fluid-tight, except for a gas inlet opening and a gas outlet opening. Within the scope of the invention, fluid-tight also means that the seal is maintained at a working pressure of the silk-channel compressor that is higher than the ambient pressure. To ensure the seal, sealing devices, such as sealing rings, in particular made of silicone or rubber, or the like, are preferably provided between the upper housing part and the lower housing part. The upper housing part is preferably formed substantially or predominantly from aluminum. The lower housing part is preferably formed substantially or predominantly from aluminum.

[0010] The bearing journal is formed as a portion of the upper housing part and extends from an inner wall of the upper housing part. According to the invention, the bearing journal is formed monolithically with the upper housing part. Alternatively, the bearing journal can also be arranged on the upper housing part in a materially bonded manner, for example by welding, or in a force-fitting manner, for example by screwing or pressing. The bearing journal extends from the inner wall of the upper housing part, from the journal root section, through the main journal section, to the journal end section.

[0011] The side channel compressor comprises the bearing inner ring and the bearing outer ring. Preferably, several rolling elements, such as balls, rollers, barrels, or the like, are arranged between the bearing inner ring and the bearing outer ring to support the bearing outer ring on the bearing inner ring with as little play as possible and to ensure relative rotation between the bearing inner ring and the bearing outer ring.

[0012] The bearing inner ring of the bearing device is arranged on the main journal section, preferably with a loose fit. Multiple bearing inner rings can also be arranged on the main journal section, preferably each with a loose fit. The loose fit is preferably designed in such a way that, when the clamping is released, easy movement of the bearing device on the bearing journal, for example, by hand, is ensured, and tilting of the bearing inner ring on the bearing journal is prevented.

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

[0014] With reference to claim 1, the side channel compressor is designed such that the central screw has a screw head, a screw shaft, and a threaded portion, wherein the screw shaft has a centering portion with an enlarged diameter D1 and a shaft portion with a reduced diameter D2, wherein the centering portion is arranged adjacent to the screw head, and wherein, in the direction of the axis of rotation, a bearing stop disk is located between the head of the central screw and an inner ring of the respective bearing and / or bears against them in the direction of the axis of rotation. The bearing stop disk has an inner diameter d4, and wherein the outer diameter D1 at least almost corresponds to the inner diameter d4, in particular in the journal clamping section.This provides the advantage that the centering area with the enlarged diameter D1 allows the bearing stop disc to be centered on the screw shaft of the central screw during assembly, as the bearing stop disc, with its inner diameter d4 running radially around the axis of rotation, is in contact with the outer diameter of the central screw and is thus guided. This ensures the centered assembly of the bearing stop disc on the central screw with the bearing journal and the respective bearing, so that the central screw does not clamp the bearing stop disc on one side and thus does not deform it.Furthermore, the advantage of the inventive design of the side channel blower and / or the central screw and / or the bearing stop plate can be achieved in that optimal force introduction during the assembly process is achieved by centering the bearing stop plate on the screw shaft, in particular the centering area, thus preventing the bearing stop plate from becoming canted. Secondly, a uniform force introduction of a bearing preload force via the central screw can be ensured by means of the tightening torque over a circumferential contact area, in particular 360° circumferentially around the axis of rotation, of the bearing stop plate with the head of the central screw and / or the end face of the respective bearing inner ring. The bearing preload force on the respective bearing is applied axially to the axis of rotation from the bearing stop plate to the bearing. Furthermore, this can lead to deformation of the bearing journal.This can lead to an increased probability of failure of the bearings and thus of the entire side channel compressor, whereby faster and safer assembly can be ensured and thus the assembly costs can be reduced and / or the probability of failure of the bearings and thus of the entire side channel compressor can be reduced.

[0015] The measures listed in the subclaims enable advantageous developments of the conveying device specified in claim 1. The subclaims relate to preferred developments of the invention.

[0016] According to an advantageous embodiment of the side channel compressor, a spacer sleeve is located in the direction of the axis of rotation between the bearing stop disk and an end face of the bearing journal, in particular within an inner diameter of the bearing inner ring, and / or bears against these in the direction of the axis of rotation. The spacer sleeve has an inner diameter d5 and the outer diameter D1 at least almost corresponds to the inner diameter d5, in particular in the journal clamping section. In this way, the advantage can be achieved that, by means of the centering area with the enlarged diameter D1, the spacer sleeve can be centered on the screw shaft of the central screw during assembly, since the spacer sleeve, with its inner diameter d5 running radially around the axis of rotation, bears against the outer diameter of the central screw and is thus guided.The centered assembly of the spacer sleeve on the central screw with the bearing journal and the respective bearing can thus be ensured, so that the central screw does not clamp the spacer sleeve on one side and thus does not deform it. Furthermore, the advantage of the inventive design of the side channel blower and / or the central screw and / or the spacer sleeve can be achieved by optimal force introduction during the assembly process, as the spacer sleeve is centered on the screw shaft, in particular the centering area, thus preventing the spacer sleeve from jamming.Secondly, a uniform introduction of the bearing preload force via the central screw and the bearing stop disk onto the spacer sleeve can be ensured by means of the tightening torque over a circumferential contact area, in particular 360° around the axis of rotation, of the spacer sleeve with the bearing stop disk and / or the end face of the bearing journal. This prevents deformation of the bearing journal. This can increase the probability of failure of the bearings and thus of the entire side channel blower. Furthermore, by centering the spacer sleeve on the centering area of ​​the central screw, the security against self-loosening of the central screw can be increased. By arranging the spacer sleeve within the bearing inner ring, a compact design of the side channel blower can be achieved.

[0017] According to an advantageous development of the side channel compressor, the central screw has a conical guide area between the centering area and the shaft area. This has the advantage that, for example, during pre-assembly of the central screw with the bearing stop plate and the spacer sleeve, the bearing stop plate and the spacer sleeve can be pushed onto the centering area more easily. The guide area extends conically at an angle α to the axis of rotation. This increases safety during pre-assembly, ensuring faster and safer pre-assembly of the central screw with the bearing stop plate and the spacer sleeve, thus reducing assembly costs and / or reducing the probability of failure of the bearings and thus of the entire side channel compressor.

[0018] According to an advantageous development of the side channel blower, the central screw has an undercut in the transition area between the screw head and the centering area. This has the advantage of improving the contact between the bearing stop plate and the screw head. The undercut prevents the bearing stop plate from jamming and / or contacting one side due to the transition radius between the screw shaft and the screw head of the central screw. This ensures even contact between the end face of the screw head and the bearing stop plate. This reduces the probability of failure of the side channel blower, as increased security against self-loosening of the central screw is achieved due to the better contact between the bearing stop plate and the screw head thanks to the undercut.This can increase the service life of the bearings and the side channel compressor.

[0019] According to a particularly advantageous embodiment of the side channel compressor, a spring element is arranged in the region of the journal root section axially to the axis of rotation between the respective bearing inner ring and an end face of the housing upper part, which spring element can be clamped to the bearings in particular via the central screw. In this way, the advantage can be achieved that a constant bearing preload and / or bearing preload force can be applied to the at least one bearing and / or the bearing inner ring by means of the spring element. In the exemplary use of two bearings, in which the two bearing inner rings are designed as loose bearings, the bearing inner ring of a first bearing can be subjected to a force at least indirectly axially to the axis of rotation by means of the central screw, and the bearing inner ring of a second bearing can be in contact with the spring element axially to the axis of rotation and be subjected to a spring force by the latter.This ensures at least a nearly constant bearing preload, regardless of deviations in component tolerances and / or temperature changes, which can lead to different component widths axially relative to the rotation axis. This has the advantage of reducing the probability of failure of the bearings and the side channel compressor, thereby increasing the service life of the side channel compressor.

[0020] According to a particularly advantageous design of the side channel compressor, the width b1 of the spacer sleeve is adjustable. This has the advantage that by varying the width b1 of the spacer sleeve, the screw-in depth of the central screw into the internal thread of the bearing journal can be changed, thereby increasing or reducing the bearing preload. The smaller the width b1 of the spacer sleeve, the higher the bearing preload on the bearings by means of the central screw and a respective preload force. The larger the width b1 of the spacer sleeve, the lower the bearing preload on the bearings by means of the central screw and the respective preload force. In this way, existing tolerance fluctuations in the components rolling bearing and / or spring element and / or housing can be compensated.This also has the advantage that preload can be easily adjusted or limited in a targeted manner using simple and cost-effective means by selecting a suitable spacer sleeve. This allows manufacturing tolerances to be compensated for and excessive preload to be avoided. This also offers the advantage of achieving optimal bearing preload through appropriate pairing of the groove and retaining ring components. This can increase the service life of the bearings and the entire side channel compressor.

[0021] According to a particularly advantageous development of the side channel compressor, a spacer disk is located between the outer bearing ring of the first bearing and the outer bearing ring of the second bearing. This has the advantage that pivoting of the compressor wheel assembly relative to the rotational axis R can be better prevented using simple and cost-effective means. Wear on the bearing device can thus be reduced and its service life can be increased. Furthermore, the smooth running of the side channel compressor can be improved in this way.

[0022] According to an advantageous embodiment, a method for assembling the side channel compressor is proposed. The central screw is provided with the screw shaft, which has the centering area. The bearing stop disc is then pushed onto the centering area of ​​the central screw, in particular via the optional conical guide area, and the spacer sleeve is pushed onto the centering area of ​​the central screw via the conical guide area to form a central screw assembly. The compressor wheel assembly is then pushed onto the bearing journal of the upper housing section. In a final step, the pre-assembled assembly comprising the central screw, the bearing stop disc, and the spacer sleeve is screwed to the bearing journal of the upper housing section and thus to the compressor wheel assembly.

[0023] The fuel cell system according to the invention provides all the advantages already described for the side channel compressor according to the first aspect of the invention. Accordingly, the fuel cell system according to the invention has the advantage over conventional fuel cell systems that an improved arrangement of the bearing device on the bearing journal of the side channel compressor is ensured using simple means and in a cost-effective manner.By using the 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 by ensuring that, for example, co-rotation of the spring element with the bearing inner ring is prevented by defrosting and eliminating ice bridges using a heatable heating disk. Furthermore, the fuel cell system according to the invention features particularly simple assembly and disassembly of the side channel compressor and is therefore cost-effective to assemble and very easy to maintain. Furthermore, the fuel cell system according to the invention features particularly low operating noise.

[0024] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of one skilled in the art. Short description of the drawing

[0025] The invention is described in more detail below with reference to the drawing.

[0026] It shows: Fig. 1 a schematic sectional view of a side channel compressor according to the invention, Fig. 2 in a sectional view a Fig. 1 Section of the side channel compressor marked II with a compressor wheel assembly, a central screw and a bearing journal Fig. 3 in a sectional view an enlarged view of the central screw according to the prior art Fig. 4 in a sectional view an enlarged view of the central screw according to the invention Fig. 5 in a sectional view a Fig. 2 Section of the side channel compressor marked III with the central screw, the bearing journal, a respective bearing, a bearing stop disc and a spacer sleeve Fig. 6 a simplified representation of a flow chart to illustrate the claimed method, Description of the embodiment

[0027] According to the illustration Fig. 1 shows a schematic sectional view of a side channel compressor 1 according to the invention.

[0028] In this case, Fig. 1 shows that the side channel compressor 1 for a fuel cell system 31 for conveying and / or compressing a gaseous medium, in particular hydrogen, with a housing 3 and a drive 6, wherein the housing 3 has an upper housing part 7 and a lower housing part 8.In addition, the housing 3 has a compressor chamber 30 which runs circumferentially around an axis of rotation 4 and which has at least one circumferential side channel 19, 21, with a compressor wheel 2 located in the housing 3, which is arranged so as to be rotatable about the axis of rotation 4 and is driven by the drive 6, wherein the compressor wheel 2 has blades 5 arranged on its circumference in the region of the compressor chamber 30 and each having a gas inlet opening 14 and a gas outlet opening 16 formed on the housing 3, which are fluidically connected to one another via the compressor chamber 30, in particular the at least one side channel 19, 21, wherein the side channel compressor 1 has at least one bearing 27, 47. The respective side channel 19, 21 can also be fluidically interrupted by means of an interrupter region 15, wherein the interrupter region 15 is located, for example, between the gas inlet opening 14 and the gas outlet opening 16.

[0029] In addition, Fig. 1 shows that the drive 6 is designed as an axial-field electric motor 6, which has a stator 11 and a rotor 17, wherein the stator 11 and the rotor 17 are formed in a disk-like manner, circulating around the rotational axis 4, and wherein the stator 11 is arranged in the direction of the rotational axis 4 next to the rotor 17. The rotor 17 can be located at least indirectly on a hub disk 23 of the compressor wheel 2. In addition, Fig. 1 shows that the side channel compressor 1 has a stator chamber 42 and a rotor chamber 44, wherein components of the drive 6 are at least partially arranged in these chambers 42, 44. The upper housing part 7 has a continuous wall 29 which is located between the stator chamber 42 and the rotor chamber 44 and effects a fluidic separation between them. The stator chamber 42 is also at least partially surrounded and / or encapsulated by a stator housing 39. The lower housing part 8 has a cylindrical bearing journal 12, wherein the bearing journal 12 has a jacket surface on its side facing away from the axis of rotation 4. The bearing journal 12 extends in the direction of the rotation axis 4 in such a way that its outer surface extends circumferentially around the rotation axis 4 and wherein a first bearing 27 and / or a second bearing 47 are in contact with the outer surface of the bearing journal 12 radially to the rotation axis 4.In addition, the compressor wheel 2 can be connected to the respective bearing 27, 47 via the hub disc 23 and a hub 9. The hub 9 has an inner bore 24. Furthermore, the invention claims the fuel cell system 31 with the side channel compressor 1 according to the invention.

[0030] Fig. 2 shows a sectional view of a Fig. 1 shows a section of the side channel compressor 1, designated II, with a compressor wheel assembly 13, a central screw 25 and the bearing journal 12. It is shown that the at least one bearing 27, 47 is fixed at least indirectly, in particular positively, to the bearing journal 12 by means of the central screw 25. Furthermore, it is shown that the side channel compressor 1 has the housing 3 (shown in Fig. 1) with the housing upper part 7 and the housing lower part 8, wherein the housing upper part 7 has the bearing journal 12 extending along the axis of rotation 4 with a journal root section 52 and a journal main section 50, wherein the first bearing 27 and the second bearing 47 are arranged on the journal main section 50. The compressor wheel assembly 13 with the compressor wheel 2 is arranged within the housing 3 on the bearing journal 12 so as to be rotatable about the axis of rotation 4, wherein the side channel compressor 1 has a journal bracing section 48, wherein the journal main section 50 is arranged between the journal root section 52 and the journal bracing section 48. The compressor wheel assembly 13 can comprise the components compressor wheel 2, hub 9, screw 35, spring washer 40, first bearing 27, second bearing 47, spacer washer 37 and optionally segment magnets and return ring.In addition, the upper housing part 7 is clamped at least indirectly to the bearings 27, 47 via a central screw 25. The central screw 25 can be inserted and / or screwed into a bore 43 of the bearing journal 12 at least partially over its length in the direction of the axis of rotation 4, wherein the bearing journal 12 has an internal thread in the region of its bore 43, into which the screw element 25 is screwed. In this case, a bearing stop disk 26 and / or a spacer sleeve 33 can be in at least indirect contact with the central screw 25, in particular a screw head 38.

[0031] Furthermore, in Fig. 2 shows that in the area of ​​the journal root section 52, a spring element 41 is arranged axially to the axis of rotation 4 between a respective bearing inner ring 22 and an end face of the housing upper part 7, which can be clamped to the bearings 27, 47, in particular via the central screw 25. The respective bearing 27, 47 each has a bearing outer ring 20 and / or the bearing inner ring 22. The spring element 41 is arranged axially to the axis of rotation 4 next to the respective bearing inner ring 22, in particular in a ring-shaped circumferential manner around the bearing journal 12, wherein the spring element 41 acts on the bearing inner ring 22 at least almost axially to the axis of rotation 4 and applies a spring force thereto. The spring force also acts at least almost parallel to the axis of rotation 4.In an exemplary embodiment, the spring element 41 is arranged on the side of the respective bearing 27, 47 facing away from the lower housing part 8, in particular between the respective bearing 27, 47 and the end face of the upper housing part 7. The at least one bearing 27, 47 with its respective bearing inner ring 22 is fixed at least indirectly via the bearing stop disk 26 by means of the central screw 25 to the bearing journal 12 axially to the axis of rotation 4. The spacer disk 37 can be arranged axially to the axis of rotation 4 between the bearing outer ring 20a of the first bearing 27 and the bearing outer ring 20b of the second bearing 47.

[0032] As in Fig. 2, in an exemplary embodiment of the side channel compressor 1, the spring element 41 can exert such a force acting axially to the rotational axis 4 on the compressor wheel assembly 13, in particular the bearing inner ring 22, and thereby presses the entire compressor wheel assembly 13 against the bearing stop plate 26. This requires a loose bearing, in particular a bearing play, for the bearing inner rings 22. In order to minimize tilting of the compressor wheel assembly 13, the play between the bearing inner ring 22 and the bearing journal 12 should be as small as possible. The respective bearing 27, 47 is located in a recess of the hub 9 and can be pressed into the recess of the hub 9. As in Fig. 2, the hub 9 is connected to the compressor wheel 2 by means of at least one spring washer 40 and at least one screw 35. In this exemplary embodiment of the side channel compressor 1 shown with the first bearing 27 and the second bearing 47, the spacer washer 37 can be located between the bearings 27, 47 in the direction of the rotation axis 4, wherein a distance between the bearings 27, 47 can be adjusted by means of the spacer washer 37.

[0033] Fig. Figure 3 shows a sectional view of an enlarged representation of the central screw according to the prior art. It shows that the central screw 25 has the enlarged screw head 38 and a screw shaft 49, with both elements 38, 49 extending rotationally symmetrically around the rotation axis 4. The central screw 25 has a threaded portion 51 in a portion of its screw shaft 49, particularly in the portion facing away from the screw head 38, and a smooth shaft portion 53 in another portion, particularly in the portion facing the screw head 38. The smooth shaft portion 53 has a diameter D2, and the threaded portion 51 has a diameter D3. The diameter D2 of the smooth shaft portion 53 is smaller than the diameter D3 of the threaded portion 51.

[0034] Fig. 4 shows a sectional view of an enlarged representation of the central screw 25 according to the invention. The central screw 25 has the screw head 38, the screw shaft 49, and the threaded portion 51, wherein the screw shaft 49 has a centering portion 10 with an enlarged diameter D1 and the shaft portion 53 with a reduced diameter D2, wherein the centering portion 10 is arranged adjacent to the screw head 38. The central screw 25 has the threaded portion 51 with the diameter D3 on the portion of the screw shaft 49 facing away from the screw head 38. In the direction of the rotation axis 4, the centering portion 10 is adjacent to the screw head 38, and the shaft portion 53 is located between the centering portion 10 and the threaded portion 51, in particular in the direction of the rotation axis 4.In an 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 shaft region 53 is smaller compared to the diameters D3 and D1.

[0035] Furthermore, in Fig. 4 shows that the central screw 25 has a conical guide area 18 between the centering area 10 and the shaft area 53, wherein the conical guide area 18 is enlarged from the shaft area 53 to the centering area 10 and / or the conical guide area 18 extends at an angle α to the rotation axis 4. The conical guide area 18 can serve to improve the assembly and / or threading of the bearing stop disc 26 and the spacer sleeve 33 during possible pre-assembly. In addition, the central screw 25 has a relief cut 28 in the transition area of ​​the screw head 38 to the centering area 10. This relief cut 28 ensures optimal support of the screw head 38, for example, on the bearing stop disc 26 in the direction of the rotation axis 4.Without this undercut 28, the bearing stop disc 26 could become misaligned at the transition radius between an end face of the screw head 38 and the centering area 10, such that the bearing stop disc 26 is no longer flush and thus almost completely abuts the end face of the screw head 38. Furthermore, the undercut 28 reduces mechanical stresses in the component, particularly when the central screw 25 is screwed to the bearing journal 12 with a high torque.

[0036] Fig. 5 shows a sectional view of a Fig. 2 section of the side channel compressor 1 designated III with the central screw 25, the bearing journal 12, the bearings 27, 47, the bearing stop disk 26 and the spacer sleeve 33. It is shown that the bearing stop disk 26 is located in the direction of the axis of rotation 4 between the head 38 of the central screw 25 and an inner ring 22 of the respective bearing 27, 47 and / or is in contact with these in the direction of the axis of rotation 4. The bearing stop disk 26 has an inner diameter d4 and the centering region 10 of the central screw 25 has the outer diameter D1, wherein the outer diameter D1 corresponds at least almost to the inner diameter d4, in particular in the pin clamping section 48. The bearing stop disk 26 can be in contact with an outer surface 32 of the centering region 10 radially and / or circumferentially to the axis of rotation 4 with a first inner surface 34 facing the central screw 25.In addition, the spacer sleeve 33 with a second inner surface 36 facing the central screw 25 can be in contact with the outer surface 32 of the centering area 10 radially and / or circumferentially to the axis of rotation 4.

[0037] In Fig. 5 further shows that, in the direction of the rotation axis 4, the spacer sleeve 33 is located between the bearing stop disk 26 and an end face 45 of the bearing journal 12, in particular within an inner diameter of the bearing inner ring 22, and / or is in contact with these in the direction of the rotation axis 4. The spacer sleeve 33 has an inner diameter d5, wherein the outer diameter D1 of the centering region 10 of the central screw 25 at least almost corresponds to the inner diameter d5, in particular in the journal clamping section 48. The bearing stop disk 26 has such a large diameter that it covers the bearing inner ring 22, in particular orthogonal to the rotation axis 4, and can thus transmit a force axial to the rotation axis 4 to the bearing inner ring 22. Furthermore, the bearing stop disc 26 is in contact, at least indirectly via the spacer sleeve 33, with the end face 45 of the bearing journal 12 in the direction of the rotation axis 4.By machining the spacer sleeve 33 prior to assembly, a bearing preload of the respective bearing 27, 47 can be achieved, particularly by applying a bearing preload force. The width b1 of the spacer sleeve 33 is adjustable. The greater the width b1 of the spacer sleeve 33, the smaller the achievable bearing preload force on the respective bearings 27, 47.

[0038] Fig. Figure 6 shows a simplified representation of a flow chart illustrating the claimed method. The method serves to assemble the side channel compressor 1 and may include the following steps, in particular assembly steps: - Providing 101 the central screw 25 with the screw shaft 49, which has the centering area 10, - sliding 102 of the bearing stop disc 26, in particular over the optional conical guide area 18, onto the centering area 10 of the central screw 25 and sliding 102 of the spacer sleeve 33 over the conical guide area 18 onto the centering area 10 of the central screw 25 to form a central screw assembly, - Pushing 103 of the compressor wheel assembly 13 onto the bearing journal 12 of the upper housing part 7, - Screwing 104 of the pre-assembled assembly, comprising central screw 25, bearing stop washer 26 and spacer sleeve 33, to the bearing journal 12 of the upper housing part 7 and thus to the compressor wheel assembly 13. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 222 102 A1 [0003, 0004]

Claims

[1] Side channel compressor (1) for a fuel cell system (2) for compressing a fluid, comprising a housing with a housing upper part (7) and a housing lower part (8), wherein the housing upper part (7) has a bearing journal (12) extending along a rotation axis (4) with 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) with a compressor wheel (2) is arranged within the housing (3) on the bearing journal (12) so as to be rotatable about the rotation axis (4), wherein the side channel compressor (1) has a journal clamping section (48), wherein the journal main section (50) is arranged between the journal root section (52) and the journal clamping section (48), wherein the housing upper part (7) has a Central screw (25) is at least indirectly clamped to the bearings (27, 47), characterized byin that the central screw (25) has a screw head (38), a screw shaft (49) and a threaded region (51), wherein the screw shaft (49) has a centering region (10) with an enlarged diameter (D1) and a shaft region (53) with a reduced diameter (D2), wherein the centering region (10) is arranged adjacent to the screw head (38) and wherein, in the direction of the axis of rotation (4), a bearing stop disk (26) is located between the head (38) of the central screw (25) and an inner ring (22) of the respective bearing (27, 47) and / or is in contact with these in the direction of the axis of rotation (4), wherein the bearing stop disk (26) has an inner diameter (d4) and wherein the outer diameter (D1) corresponds at least almost to the inner diameter (d4), in particular in the pin clamping section (48). [2] Side channel compressor (1) according to claim 1, characterized byin that a spacer sleeve (33) is located in the direction of the rotation axis (4) between the bearing stop disk (26) and an end face (45) of the bearing journal (12), in particular within an inner diameter of the bearing inner ring (22), and / or is in contact with these in the direction of the rotation axis (4), wherein the spacer sleeve (33) has an inner diameter (d5) and wherein the outer diameter (D1) corresponds at least almost to the inner diameter (d5), in particular in the journal clamping section (48). [3] Side channel compressor (1) according to claim 1 or 2, characterized by , wherein the central screw (25) has a conical guide region (18) between the centering region (10) and the shaft region (53). [4] Side channel compressor (1) according to one of the preceding claims, characterized by that the central screw (25) has a relief groove (28) in the transition area of the screw head (38) to the centering area (10) [5] Side channel compressor (1) according to one of the preceding claims, characterized by that in the region of the journal root section (52) a spring element (41) is arranged axially to the axis of rotation (4) between the respective bearing inner ring (22) and an end face of the housing upper part (7), which can be clamped to the bearings (27, 47) in particular via the central screw (25). [6] Side channel compressor (1) according to claim 2, characterized by that the width b1 of the spacer sleeve (33) is adjustable. [7] Side channel compressor (1) according to one of the preceding claims, characterized by that a spacer disc (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] Method for assembling the side channel compressor (1) according to one of the preceding claims, comprising the following steps: - Providing (101) the central screw (25) with the screw shaft (49) having the centering area (10), - sliding (102) of the bearing stop disc (26), in particular via the optional conical guide area (18), onto the centering area (10) of the central screw (25) and sliding (120) of the spacer sleeve (33) over the conical guide area (18) onto the centering area (10) of the central screw (25) to form a central screw assembly - Slide (103) the compressor wheel assembly (13) onto the bearing journal (12) of the upper housing section (7) - Screwing (104) the pre-assembled assembly, comprising central screw (25), bearing stop disc (26) and spacer sleeve (33) to the bearing journal (12) of the upper housing part (7) and thus to the compressor wheel assembly (13). [9] Fuel cell system (31) with a side channel compressor (1) according to one of the preceding claims 1 to 8, wherein the side channel compressor (1) is arranged in an anode circuit of the fuel cell system (31).

Images