MEDIA GAP MOTOR FOR A TURBOCHARGER

Abstract

The present disclosure relates to a media gap motor for a turbocharger. The proposed media gap motor contains a rotor and a stator, wherein the stator comprises multiple fins which extend from an inner portion radially towards the rotor in a flow chamber formed between the stator and the rotor. The fins do not extend by means of their inner portions as far as the rotor, and therefore a gap is formed between an inner end of the fins and the rotor, wherein in internal diameter of the fins is at least 1.2 times and at most 3 times an external diameter of the rotor.

Claims

1. A media gap motor for a turbocharger, the media gap motor comprising: a rotor; and a stator, the stator comprising: multiple fins which extend from an inner portion radially towards the rotor in a flow chamber formed between the stator and the rotor, wherein the multiple fins do not extend as far as the rotor, and therefore a gap is formed between an inner end of the multiple fins and the rotor, wherein an internal diameter of the multiple fins is at least 1.2 times and at most 3 times an external diameter of the rotor.

2. The media gap motor according to claim 1, wherein the internal diameter of the multiple fins is at least 1.4 times and at most 2 times the external diameter of the rotor.

3. The media gap motor according to claim 1, multiple stator slots are formed in the flow chamber between the multiple fins such that at least part of a medium flows through the multiple stator slots.

4. The media gap motor according to claim 3, wherein an extent of the multiple stator slots through which the medium flows in a radial direction is at least a quarter of the external diameter of the rotor.

5. The media gap motor according to claim 1, wherein the flow chamber is delimited in an inner region by the rotor.

6. The media gap motor according to claim 1, wherein the flow chamber is at least partially formed by a hollow-cylindrical gap between the inner ends of the fins and the rotor and by a stator slot between a first fin of the multiple fins and a second fin of the multiple fins, wherein the second fin is adjacent to the first fin.

7. The media gap motor according to claim 1, wherein a maximum diameter of the flow chamber is at least twice the external diameter of the rotor.

8. The media gap motor according to claim 1, wherein each fin of the multiple fins comprise an outer portion extending radially outside the flow chamber, and wherein the stator comprises multiple coils surrounding the outer portions of the multiple fins.

9. The media gap motor according to claim 8, wherein the multiple coils and the outer portions of the multiple fins are arranged beyond a radial seal of the flow chamber.

10. The media gap motor according to claim 8, wherein the outer portions of the multiple fins and the inner portions of the multiple fins form an active part of a magnetic circuit.

11. The media gap motor according to claim 8, wherein each coil of the multiple coils are located on a corresponding coil carrier, wherein each coil of the multiple coils and each corresponding coil carrier are located on the outer portion of a particular fin of the multiple fins.

12. The media gap motor according to claim 8, wherein the outer portions of the multiple fins are formed in one piece with the inner portions.

13. The media gap motor according to claim 8, further comprising: a yoke ring to which the outer portions of the multiple fins are attached.

14. The media gap motor according to claim 13, wherein the outer portions of the multiple fins are connected to the yoke ring via a plug connection.

15. The media gap motor according to claim 13, wherein the outer portions of the multiple fins are connected to the yoke ring via a dovetail connection.

16. The media gap motor according to claim 13, wherein a first segment of the yoke ring is connected to a second segment of the yoke ring via an articulated joint, and wherein the first segment of the yoke ring is connected to a particular fin of the multiple fins and the second segment of the yoke ring is connected to a different particular fin of the multiple fins.

17. The media gap motor according to claim 8, further comprising: a cover plate arranged between the outer portion and inner portion of a first fin and a second fin adjacent to the first fin, wherein the cover plate delimits a region of the flow chamber, and wherein the cover plate is located between the multiple coils of the stator and the flow chamber.

18. The media gap motor according to claim 17, wherein the first fin and the second fin comprise one or more axially extending grooves into which the cover plate inserted.

19. The media gap motor according to claim 17, wherein the cover plate is formed in a single piece with the multiple fins such that the cover plate and the multiple fins form a one-piece fin ring.

20. The media gap motor according to claim 8, wherein the outer portions of the multiple fins have a greater width than the inner portions of the multiple fins.

21. The media gap motor according to claim 8, wherein the multiple coils are formed by a winding curved along a circular line.

22. The media gap motor according to claim 1, wherein the rotor comprises a rotor magnet, and wherein the multiple fins comprise an axial overhang with the rotor magnet.

23. The media gap motor according to claim 1, wherein the rotor comprises a rotor magnet, wherein a length of the rotor magnet exceeds a total length of the multiple fins in an axial direction.

24. The media gap motor according to claim 1, further comprising: a flow cap arranged in front of the rotor, wherein the flow cap comprises at least one of an inflow dome covering the rotor or one or more inflow edges arranged in front of the multiple fins.

25. The media gap motor according to claim 24, wherein the flow cap is continued in an axial direction in order to at least partially enclose the multiple fins, and wherein the flow cap at least partially encloses at least one of: one or more side surfaces of the multiple fins or a radially inner end of the multiple fins.

26. The media gap motor according to claim 24, further comprising: a second flow cap arranged behind the multiple fins with respect to a flow direction, wherein the second flow cap comprises one or more outflow edges, wherein the one or more outflow edges are at least one of: arranged behind the multiple fins or at least partially cover the multiple fins.

27. The media gap motor according to claim 26, wherein the one or more outflow edges are angled and configured to generate a pre-swirl in an intake medium.

28. A turbocharger for an internal combustion engine, comprising: a compressor arrangement for compressing fresh air; a compressor wheel; and a media gap motor, the media gap motor comprising: a rotor; and a stator, the stator comprising: multiple fins which extend from an inner portion radially towards the rotor in a flow chamber formed between the stator and the rotor, wherein the multiple fins do not extend as far as the rotor, and therefore a gap is formed between an inner end of the multiple fins and the rotor, wherein an internal diameter of the multiple fins is at least 1.2 times and at most 3 times an external diameter of the rotor, and wherein the rotor is coupled to the compressor wheel.

Description

[0038] Embodiments are described below with reference to the illustrations. Shown are

[0039] FIG. 1 a view of a turbocharger,

[0040] FIGS. 2(a) and (b) schematic views of a stator of the turbocharger,

[0041] FIG. 3 a perspective view of a coil and a bobbin,

[0042] FIGS. 4(a) to (c) schematic views of the stator of the turbocharger according to a further embodiment,

[0043] FIGS. 5(a) to (c) schematic views of the stator of the turbocharger according to a further embodiment,

[0044] FIG. 6 a schematic view of the stator of the turbocharger according to a further embodiment,

[0045] FIGS. 7(a) and (b) schematic views of flow caps,

[0046] FIGS. 8(a) and (b) perspective views of the stator with flow caps,

[0047] FIG. 9 a schematic view of the stator according to FIG. 8(a),

[0048] FIGS. 10(a) and (b) cross-sectional views of media gap motors,

[0049] FIGS. 11(a) and (b) perspective views of an inflow cap,

[0050] FIGS. 12(a) and (b) perspective views of an outflow cap,

[0051] FIGS. 13(a) and (b) sectional views of the inflow and outflow cap and

[0052] FIG. 14 stator laminations with cranked fins.

[0053] In a partially exploded view, FIG. 1 shows an electrically modified mechanical turbocharger 1 which can be coupled to an internal combustion engine with a turbine housing 2. In general, however, the invention described can also relate to other media gap motors, for example, with spiral conveyors. After combustion, the exhaust gas is collected by the exhaust manifold shown in the illustration and used to drive a turbine wheel 3. The turbine wheel 3 is surrounded by the turbine housing 2 and is essentially taken from a conventional mechanical turbocharger. A bearing housing 4 and then a compressor housing 5 adjoin the turbine housing 2. A compressor wheel 6 is arranged in said compressor housing 5 and compresses air supplied through an inlet opening. The air is then routed to the combustion chamber of the internal combustion engine. In the example shown, the compressor wheel 6 has an extension on the left side, on which extension a rotor 7 of an electric motor is arranged. The rotor 7 in this case is freely cantilevered, that is, the rotor 7 is not mounted separately. When the turbocharger 1 is fully assembled, the rotor 7 is mounted centrally in the inlet air opening. The air inlet flow direction is marked with an arrow with reference number 8 in the illustration.

[0054] A stator 9 is provided around the rotor 7, the stator 9 being shown only schematically in the figure and essentially having a hollow-cylindrical shape. In the present case, the stator 9 is provided as an insert in a corresponding opening, so that it can be assembled very easily. A rotor gap formed between the rotor 7 and the stator 9 forms the inlet air opening for the compressor wheel 6. The rotor 7 of the electric motor comprises a rotor magnet surrounded by a reinforcement.

[0055] The compressor wheel 6 can (but does not have to) be made of a non-metallic material; in an embodiment made of an unreinforced plastic, for example, the influence on the electromagnetic field of the electric motor is minimized. The rotor magnet, in turn, is designed to be hollow in some regions so that it can be plugged onto a common shaft with the compressor wheel 6. In the present embodiment, a shaft 10 connecting the turbine wheel 3 to the compressor wheel 6 is designed such that the turbine wheel 3, the compressor wheel 6 and the rotor 7 are connected to one another in a torque-proof manner.

[0056] The target voltage of the electric motor is 12 V, for example, but other voltages (for example 48 V to 800 V for hybrid vehicles) are also possible. In the example shown, the rotor magnet of the rotor 7 is designed such that it is partially or completely integrated into the compressor wheel 6 or is connected thereto. A smallest internal diameter of the stator 9 can be 1.5 to 8 times larger than a largest external diameter of the rotor 7. The electric motor can be operated both in motor mode (to accelerate and avoid turbo lag) and in generator mode (to recover energy). If the charging pressure (in the turbine housing 2) reaches a specific target value, additional electrical energy is generated using a regenerative converter. The electric motor of the turbocharger 1 is connected to a store for electrical energy in order to draw electrical energy when the turbocharger 1 is operating as a motor and to feed in electrical energy when the turbocharger 1 is operating as a generator. For efficient control of the drive system or turbocharger 1, control electronics are provided for determining the speed of turbine wheel 3 or compressor wheel 6, actual values of pressure conditions on the turbine housing side and compressor housing side, and further torque-relevant values for the internal combustion engine.

[0057] FIG. 2(a) shows a schematic view of the stator 9 of the turbocharger to be produced, viewed in the direction transverse to the rotor axis. Recurring features are provided with the same reference symbols in this and the following figures. The stator 9 comprises a yoke ring 11 which, in the illustration shown, is designed as a pole chain having six portions. Two of the portions of the yoke ring 11 are identified by the reference numerals 12 and 12′ by way of example. All portions 12, 12′ of the yoke ring 11 are connected to one another via articulated joints, identified by way of example with reference numerals 13 and 13′.

[0058] The portions 12, 12′ of the yoke ring 11 are each formed in one piece with a fin 14, 14′, that is, monolithically, coherently. The fins 14, 14′ each comprise a thinner inner portion 15, 15′ and a widened outer portion 16, 16′. During production of the turbocharger 1, coils 17, 17′ of the stator 9, which are accommodated on coil carriers 18, 18′, are pushed or plugged onto the outer portions 16, 16′ of the fins 14, 14′.

[0059] The fins 14 comprise grooves 19, 19′ running axially on both sides between the outer portions 16 and the inner portions 15. During the production of the turbocharger, cover plates 20, 20′ are pushed into the grooves 19, 19′ of adjacent fins in the axial direction. The cover plates 20, 20′ then (together with the fins 14) seal off a flow chamber 29 of the turbocharger 1 in the radial direction, as illustrated in FIG. 2(b). In the configuration shown, the turbocharger 1 is assembled by folding the articulated joints 13, 13′ such that the portions 12, 12′ of the yoke ring 11 form a closed ring. After assembly, the inner portions 15, 15′ of the fins 14, 14′ extend in the radial direction inwards toward the rotor 7. The fins 14, 14′ are also arranged distributed evenly over the circumference. The flow chamber 29 comprises stator slots 22 for media delivery through the turbocharger 1, the stator slots 22 being delimited by intermediate spaces between the inner portions 15, 15′ of the fins 14, 14′, and a media gap 23 completely surrounding the rotor 7, the media gap 23 extending in a radial region between the rotor 7 and inner ends of the fins 14, 14′. An internal diameter of the fins 14, 14′, based on the largest possible circular diameter centered on the rotor axis, can be, for example, at most 50 mm, in particular at most 37.5 mm, and/or at least 15, for example, 26 mm. An external diameter of the rotor can be at the same axial position, based on the smallest possible circular diameter, for example, at most 25 mm and/or at least 10 mm, for example, 17 mm. The fins 14, 14′ also comprise widenings 24, 24′ at their inner ends to reduce the magnetic cogging torque.

[0060] FIG. 3 illustrates in an exemplary perspective view of how the coil 17 is accommodated on the bobbin 18. The coil 17 in this case is wound around the bobbin 18 and prefabricated together with the bobbin 18. In the example shown, the coil 17 is pushed onto the outer portion 16 of the fin 14 together with the bobbin 18 from the outside, the inner portion 15 of the fin 14 not being shown in this figure.

[0061] FIGS. 4(a) to (c) show a schematic view of the stator 9 of the turbocharger 1 according to a further embodiment. This embodiment corresponds to that described above, wherein, however, the cover plates 20, 21 are designed in one piece, that is, monolithically, with the fins 14, 14′ and thus with their inner and outer portions 15, 16. In this embodiment, the fins 14, 14′ together with the cover plates 20, 21 form a one-piece fin ring 25. When the turbocharger 1 is assembled, the coils 17 together with the coil carriers 18 are pushed onto the outer portions 16 of the fins 14 from the outside. The fin ring 25 is then inserted together with the coils 17 into a yoke ring 11 shown in FIG. 4(b) and connected thereto, therefore resulting in the configuration shown in FIG. 4(c).

[0062] FIGS. 5(a) to (c) show a stator 9 of the turbocharger 1 according to a further embodiment. This embodiment corresponds to that described above, wherein, however, the fins 14 can be attached to the yoke ring 11 via a dovetail connection. For this purpose, the fins 14 comprise dovetail-shaped pins 26, 26′ on their outer portions 16, dovetail-shaped pins 26, 26′ being able to be pushed into correspondingly shaped grooves 27, 27′ on an inner side of the yoke ring 11.

[0063] A further embodiment of the stator 9 is shown in FIG. 6. This embodiment can correspond in all features to the embodiments described above, wherein, however, the coils 17, 17′ and bobbins 18, 18′ are curved such that the inner sides 28, 28′ of the coils or bobbins correspond in shape to a segment of a circle. Said inner sides 28, 28′ follow the shape of the cover plates 20, 21 delimiting the flow chamber 29. The space available for generating the magnetic field can be optimally utilized In this way.

[0064] FIGS. 7(a) and 7(b) show flow caps 30, 30′ according to two different embodiments. FIGS. 8(a) and 8(b) show corresponding perspective views in which the stator 9 is equipped with one of the flow caps 30, 30′. FIG. 9 shows a plan view of the stator 9 according to FIG. 8(a). The flow caps 30, 30′ are arranged upstream in front of the fins 14 of the stator 9 and improve the flow behavior. The flow cap 30 of FIGS. 7(a), 8(a) and 9 comprises six struts 31, 31′ distributed over the circumference, each of which covers one of the fins 14 in the axial direction. Three of the struts 31, 31′ hold an inflow dome 32 which is arranged in an axially central position and which tapers in the upstream direction and which covers the rotor 7 of the turbocharger 1. The embodiment of the flow cap 30′ of FIGS. 7(b) and 8(b) also comprises struts 33, 33′ extending inward. Said struts 33, 33′ comprise pronounced inflow or outflow edges 34, 34′ at their upstream end.

[0065] To illustrate possible fin geometries, FIGS. 10(a) and 10(b) show media gap motors having different fin lengths in cross-section. FIG. 10(a) shows a stator 9 having a minimum inner fin diameter of 20.5 mm and a rotor magnet diameter of 15 mm, a 2 mm thick reinforcement of the rotor 7 being provided. FIG. 10(b), on the other hand, shows a stator 9 having an inner fin diameter of 45 mm, the rotor magnet diameter again being 15 mm and the thickness of the reinforcement of the rotor 7 again being 2 mm. In FIGS. 10(a) and (b), the internal diameter of the fins 14, 14′ is indicated by the dashed line with reference numeral 35. The external diameter of the rotor 7, on the other hand, is indicated by a dashed line with reference number 36. In FIGS. 10(a) and 10(b), as in the previous illustrations, it can be seen that the flow chamber through which the medium usually flows during operation is typically formed in an outer region by the stator slots and in an inner region is delimited by the optionally rotating rotor. The radially outer flow region of the stator slots and the radially inner, annular flow region, which lies between the fins and the rotor, are directly connected to one another or merge directly into one another.

[0066] FIGS. 11(a) and (b) show an inflow cap 37 in a front view (viewed in the flow direction) and a rear view (viewed against the flow direction). The inflow cap 37 is prefabricated as a one-piece, magnetically inactive plastic part and can be pushed onto the stator laminations of the fins 14 and attached in the axial flow direction. The inflow cap 37 comprises a ring element 41 and the inflow edges 31, 31′ extending inward from the ring element and covering the fins 14. In addition, the inflow cap 37 comprises the inflow dome 32 covering the rotor 7. The inflow dome 32 is held by part of the inflow edges 31, 31′. The inflow cap 37 also comprises thin-walled, sleeve-like extensions 38, 38′ enclosing the stator laminations of the fins, which have a rectangular cross-section. Here, the extensions 38, 38′ enclose the two side surfaces and the radially inner ends of the fins 14.

[0067] FIGS. 12(a) and (b) show an outflow cap 39 in a front view (viewed in the flow direction) and a rear view (viewed against the flow direction). The outflow cap 39, like the inflow cap 37, is prefabricated as a one-piece, magnetically inactive plastic part and can be attached to other parts of the media gap motor. The discharge cap 39 comprises a ring element 42 and outflow edges 40, 40′ extending inwardly from the ring element 42 and covering the fins 14 on the downstream side. In preferred embodiments, the outflow edges can be designed such that they generate a pre-swirl through an inclined position, having an advantageous effect on the compressor characteristics. The outflow edges 40, 40′ are not hollow.

[0068] As FIGS. 13(a) and (b) illustrate, the inflow cap 37 and the outflow cap 39 can be pushed into the stator as prefabricated parts in the axial direction towards one another such that the extensions 38, 38′ surround the stator laminations of the fins 14 like a sleeve.

[0069] FIG. 14 shows the stator laminations of cranked fins 14 according to one embodiment. The stator laminations of the fins 14 are made from stamped individual laminations and are formed in one piece with the yoke ring 11 in the example shown. The individual laminations are stacked on top of one another in the axial direction. It can be seen that the outer portions 16 of the fins 14 and the inner portions 15 of the fins 14 have a rectangular cross-section. The outer portions 16 of the fins 14 have a constant cross-section in the radial direction. A cross-sectional area of the fins 14 decreases in a stepwise manner from the outer portion 16 to the inner portion 15. A cross-sectional area of the inner portions 15 of the fins 14 continuously decreases in the radially inward direction by providing tapered surfaces 43, 43′ on the upstream side of the inner portions 15 of the fins 14. On the other hand, upstream sides of the outer portions 16 of the fins are not tapered and run transversely to the axial direction.

[0070] Features of the various embodiments disclosed only in the exemplary embodiments can be combined with one another and claimed individually.