ROTOR ASSEMBLY AND SYNCHRONOUS MACHINE INCLUDING ROTOR ASSEMBLY

Abstract

The present invention relates to a rotor assembly (2) for an inductively electrically excited synchronous machine (1). The rotor assembly (2) comprises a hollow shaft (3) rotatable about a rotation axis (RA), a rotor (4) and a secondary circuit (5) of an energy transfer device (6). The secondary circuit (5) comprises a rectifier (7) having a printed circuit board (10) and at least one electrical component (11) and a secondary coil (8). The rectifier (7) according to the invention is aligned transversely to the rotation axis (RA) and is mounted in a cavity (9) of the hollow shaft (3). The present invention also relates to a synchronous machine (1) comprising the rotor assembly (2).

Description

[Technical field]

[0001] The present invention relates to a rotor assembly for an inductively electrically excited synchronous machine according to the preamble of claim 1, and to an inductively electrically excited synchronous machine comprising such a rotor assembly. [Background technology]

[0002] An inductively electrically excited synchronous machine is known, for example from EP 2 869 316 B1, and comprises a stator and a rotor rotatably arranged in the stator. The stator and the rotor are supplied with energy and interact electromagnetically with each other. To transmit energy to the rotating rotor, an inductive energy transfer device is provided, which comprises a primary coil on the stator side or a stationary primary coil and a secondary coil on the rotor side or a rotating secondary coil, respectively. A rotor-side rectifier or a rotating rectifier, respectively, is further provided. The rectifier is formed by a printed circuit board comprising a number of electrical components connected to each other. The printed circuit board is usually fixed to the rotor or to the shaft of the synchronous machine, and the electrical components are arranged diametrically around the shaft.

[0003] During operation of the synchronous machine, the rectifier is rotated together with the shaft and the electrical components are subjected to large centrifugal forces and vibrations. This can lead to damage to the electrical components and / or solder connections and thus to failure of the synchronous machine. Disadvantages: the minimum radius of the printed circuit board is limited at the bottom, and therefore the electrical components and their connections to the printed circuit board have to meet certain strength requirements. The choice of electrical components for the rectifier of the synchronous machine is therefore limited and the cost of the rectifier is accordingly high. Furthermore, the rotor and the shaft heat up significantly during operation of the synchronous machine. Due to the fact that the rectifier is arranged close to the shaft and close to the rotor, the upper temperature limit of the shaft and rotor is limited by the upper temperature limit of the electrical components of the rectifier. Cooling of the shaft and rotor therefore represents a further challenge. Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore an object of the present invention to identify an improved or at least alternative embodiment of a synchronous machine and rotor assembly to conventional synchronous machines, in which the aforementioned drawbacks are overcome. [Means for solving the problem]

[0005] The above object is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0006] The rotor assembly is provided in an inductively electrically excited synchronous machine, which may be provided in a motor vehicle. The rotor assembly comprises a hollow shaft rotatable about a rotation axis and a rotor connected to the hollow shaft so as not to rotate relative to the hollow shaft. The rotor assembly further comprises a secondary circuit of an energy transfer device, the secondary circuit being arranged so as not to rotate relative to the rotor assembly. The secondary circuit comprises a rectifier comprising a printed circuit board and at least one electrical component fixed to the printed circuit board, and a secondary coil. According to the invention, the rectifier is aligned transversely to the rotation axis and arranged so as not to rotate relative to the cavity of the hollow shaft.

[0007] In the present invention, the terms "radial" and "axial" always refer to the axis of rotation. The term "orbital" is with respect to the axis of rotation of the hollow shaft unless otherwise defined.

[0008] The cavity is formed in the hollow shaft and the flow straightener is arranged in the cavity of the hollow shaft or in the hollow shaft. The cavity is externally bounded by the walls forming the hollow shaft and the flow straightener can be rigidly connected to the hollow shaft or to the walls of the hollow shaft directly or indirectly. The flow straightener can be rigidly connected to the hollow shaft or to the walls of the hollow shaft in a force-fit and / or form-fit manner.

[0009] At least one electric component may be fixed to the printed circuit board and electrically connected or in electrical contact with the printed circuit board. Advantageously, the rectifier has a number of electric components fixed to the printed circuit board. The electric components may be electrically connected or in electrical contact with one another via the printed circuit board. For example, the electric components may be diodes and / or electrical resistors and / or further elements. It goes without saying that the electric components are connected on the printed circuit board to form a rectifier circuit. Advantageously, the rectifier or the rectifier circuit is in electrical contact with the rotor winding of the rotor outside the hollow shaft, for example via the hollow shaft.

[0010] In the rotor assembly according to the present invention, the commutator is disposed in the cavity of the hollow shaft, and the electrical components can be disposed in the center or on a smaller diameter on the printed circuit board. Therefore, the centrifugal force acting on the electrical components when the rotor assembly rotates at a constant speed is reduced. Therefore, the rotor assembly can operate at a high rotation speed without damaging the electrical components or the solder connections of the electrical components, and thus the commutator. Therefore, the rotor assembly can be stable at a high rotation speed.

[0011] In the hollow shaft the rectifier can be protected from mechanical damage due to environmental influences, e.g. cooling medium, contamination by conductive particles, etc. The hollow shaft also provides a shield against coupling of interferences, e.g. electromagnetic compatibility (EMC), so no additional housing for the rectifier is needed. The rectifier can be balanced with the rotor assembly or rotor in a common balancing process, which can maximize the balancing quality or minimize the tolerable residual unbalance.

[0012] It is advantageous if the at least one electrical component of the rectifier is mechanically supported on the hollow shaft, so that the at least one electrical component can be particularly effectively protected against mechanical damage.

[0013] The hollow shaft may be formed with a shaft end and a shaft cover which axially closes the shaft end. The shaft end and the shaft cover may be rigidly connected during assembly of the hollow shaft by material-to-material bonding and / or in the manner of a press fit and / or in the manner of a form fit and may limit the cavity of the hollow shaft to the outside. The flow straightener may be rigidly connected to the shaft end of the hollow shaft or to the shaft cover. In particular, the flow straightener may be rigidly connected to the shaft end or to the shaft cover by material-to-material bonding and / or in the manner of a press fit and / or in the manner of a form fit. The assembly of the flow straightener may be performed during assembly of the hollow shaft.

[0014] In an advantageous embodiment of the rotor assembly, the rectifier may have a cooling body. The cooling body is located opposite the at least one electrical component and is attached in a heat-transferring manner to the printed circuit board of the rectifier. The cooling body is thus connected in a heat-transferring manner to the printed circuit board and can dissipate heat generated by the at least one electrical component to the outside, for example to the medium surrounding the cooling body. Thus, the printed circuit board and the at least one electrical component can be effectively cooled. Preferably, the cooling body can be made of a thermally conductive material.

[0015] Furthermore, the at least one electrical component of the rectifier can be encapsulated with a thermally conductive molding compound. The thermal conduction of the rectifier and thus the cooling of the at least one electrical component can be improved by the molding compound. Furthermore, damage to the at least one electrical component due to vibrations and shocks can be avoided by the molding compound. Alternatively or additionally, the at least one electrical component of the rectifier can be connected to a printed circuit board and / or the at least one printed circuit board can be connected to a heat sink, in each case via a thermally conductive pad for heat transfer. Thus, the thermal conduction of the rectifier and thus the cooling of the at least one electrical component and / or the cooling of the printed circuit board can be improved.

[0016] To improve the cooling of the rectifier, the heat sink may have a cooling structure located on the side opposite the printed circuit board. The cooling structure may be realized, for example, by at least one cooling rib and / or a number of cooling pins. The surface of the heat sink adjacent to the surrounding medium may be enlarged by the cooling structure, enhancing the heat dissipation to the medium. Thus, overall, the cooling of the rectifier may be improved.

[0017] It is advantageous if the heat sink is electrically insulated from the hollow shaft by a dielectric covering. Alternatively or additionally, the heat sink can be made of a dielectric material, preferably a composite material. Damage to the rectifier or to the at least one electrical component by ring currents generated in the rotor can be prevented.

[0018] In the case of an advantageous embodiment of the rotor assembly, the cooling body can divide the cavity of the hollow shaft in a liquid-tight manner into a cooling chamber and a transmission chamber. The cooling chamber is arranged to be located opposite the printed circuit board, through which a liquid or gaseous cooling fluid can flow. The transmission chamber accommodates the printed circuit board. In other words, the rectifier is arranged to face the transmission chamber with the printed circuit board and to face the cooling chamber with the cooling body. For sealing the cooling chamber against the transmission chamber, the cooling body can have at least one sealing element. The sealing element can be, for example, an annular seal. The cooling body can be embodied as a separate component and can be securely fixed to the shaft end or to the shaft cover.

[0019] The cooling fluid flows over and / or around the cooling body in the cooling chamber to dissipate heat from the cooling body. Thus, the printed circuit board and at least one electrical component can be effectively cooled and maintained below an upper temperature limit during operation of the rotor assembly. Thus, the continuous and peak performance of the rotor assembly can be increased without using high temperature components. Thus, the cost of the rotor assembly can be reduced for higher performance density.

[0020] Furthermore, the hollow shaft may have an axial end that is open to the outside and communicates with the cooling chamber, and the cooling fluid can enter the cooling chamber of the hollow shaft through the open axial end. The hollow shaft then also has at least one opening that communicates radially outward from the cooling chamber, and the cooling fluid can exit the cooling chamber of the hollow shaft through the at least one opening. Direct cooling of the hollow shaft and the rotor with the cooling fluid results in a lower temperature around the rectifier compared to conventional solutions.

[0021] It is advantageous if the secondary coil of the secondary circuit is arranged in the cavity of the hollow shaft or outside the cavity of the hollow shaft so that it can inductively interact with the primary circuit of the energy transfer device. If the secondary coil is arranged in the cavity of the hollow shaft, it can be fixed to the wall of the hollow shaft within the cavity so that it rotates around the axis of rotation. If the cavity is divided into a cooling chamber and a transfer chamber, the secondary coil can be arranged in the transfer chamber. It goes without saying that the secondary coil and at least one electrical component of the rectifier are electrically connected or in electrical contact with each other.

[0022] The invention also relates to an inductively electrically excited synchronous machine comprising a rotor assembly as described above. The synchronous machine comprises a stator assembly comprising a stator, the rotor assembly being accommodated in the stator so as to be rotatable about a rotation axis. The rotor of the rotor assembly and the stator of the stator assembly are arranged radially spaced from each other so as to be able to electromagnetically interact with each other. The stator assembly comprises a primary circuit of an inductive energy transfer device comprising an inverter and a primary coil. The primary circuit is arranged so as not to rotate relative to the stator assembly. As described above, the rotor assembly comprises a secondary circuit of an energy transfer device comprising a secondary coil and a rectifier. The primary coil and the secondary coil are arranged so as to be able to inductively interact with each other. Advantageously, the synchronous machine is provided in a motor vehicle. To avoid repetition, reference is made here to the previous description.

[0023] Further important features and advantages of the invention emerge from the dependent claims, the drawings and the corresponding figure description based on the drawings.

[0024] It goes without saying that the features mentioned above and those to be described below can be used not only in each specific combination but also in other combinations or alone, without departing from the scope of the invention.

[0025] Preferred exemplary embodiments of the present invention are illustrated in the drawings and will be explained in more detail in the following description, where like reference numbers indicate identical, similar or functionally identical features. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a cross-sectional view of a synchronous machine according to the present invention, which includes a rotor assembly according to the present invention in a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a synchronous machine according to the present invention, including a rotor assembly according to the present invention in a second embodiment. [Diagram 3] FIG. 3 is a circuit diagram of an energy transmission device in a synchronous machine according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Fig. 1 shows a cross-sectional view of an inductively electrically excited synchronous machine 1 according to the invention, comprising a rotor assembly 2 according to the invention in a first embodiment. The rotor assembly 2 comprises a hollow shaft 3 and a rotor 4, the hollow shaft 3 being rotatable about a rotation axis RA, the rotor 4 being connected to the hollow shaft 3 in a non-rotatable manner. The rotor assembly 2 further comprises a secondary circuit 5 of an energy transfer device 6. The secondary circuit 5 is connected to the rotor assembly 2 or to the hollow shaft 3 in a non-rotatable manner and comprises a rectifier 7 and a secondary coil 8, as also shown in Fig. 3. The hollow shaft 3 further comprises a cavity 9, in which the secondary circuit 5, i.e. here the rectifier 7 and the secondary coil 8, are arranged.

[0028] The rectifier 7 comprises a printed circuit board 10 with a number of electrical components 11 and a cooling body 12. The cooling body 12 is adjacent to the printed circuit board 10 on the opposite side to the electrical components 11 and is connected to the printed circuit board 10 in a heat-transferring manner. Alternatively, the cooling body 12 may be directly adjacent to the electrical components 11 in a heat-transferring manner. Thus, heat from the electrical components 11 can be dissipated directly to the cooling body 12, shortening the heat conduction path. Thus, heat generated in the electrical components 11 can be dissipated to the cooling body 12 via the printed circuit board 10. The rectifier 7 is aligned in the cavity 9 in a direction transverse to the rotation axis RA and divides the cavity 9 into a cooling chamber 9a and a transfer chamber 9b. The cooling body 12 of the rectifier 7 seals the cooling chamber 9a and the transfer chamber 9b from each other in a liquid-tight manner. For this purpose, an annular sealing element 13 circumferentially rotating around the rotation axis is arranged between the cooling body 12 and the hollow shaft 3. The rectifier 7 is arranged facing the cooling chamber 9a with the cooling body 12 and facing the transfer chamber 9b with the printed circuit board 10. The secondary coil 8 is fixed to the inner wall of the hollow shaft 3 in the transfer chamber 9b.

[0029] A cooling fluid in gaseous or liquid form flows through the cooling chamber 9a. The cooling fluid enters the cooling chamber 9a at the axial end 3a of the hollow shaft 3, which opens outward, and leaves the cooling chamber 9a through a number of openings 14 that communicate radially outward. The axial end 3a is arranged so as to be located axially opposite to the axial end 3b of the hollow shaft 3 on the A side. The cooling fluid flows around the cooling body 12, and heat is dissipated by the cooling body 12 to the cooling fluid. On the cooling chamber 9a side, the cooling body 12 further comprises a cooling structure 15 comprising a number of cooling ribs 16 or alternatively a number of cooling pins that further increase the dissipation of heat to the cooling fluid.

[0030] The synchronous machine 1 further comprises a primary circuit 17 of the energy transfer device 6 with a primary coil 18, see also figure 3. The primary coil 18 projects into the transfer chamber 9b and into the annular secondary coil 8. An annular gap circumferential around the axis of rotation is formed between the secondary coil 8 and the primary coil 18, through which the secondary coil 8 and the primary coil 18 can interact electromagnetically, or in an energy-transmitting or inductive manner.

[0031] For ease of assembly, the hollow shaft 3 is formed in two parts, and has a shaft end 19 and a shaft cover 20. The shaft end 19 surrounds the transmission chamber 9b of the hollow shaft 3 and is located at the axial end 3b on the A side of the hollow shaft 3. The shaft end 19 and the shaft cover 20 together form a bottle shape, with the cavity 9 widening from the axial end 3a towards the center and narrowing from the center towards the axial end 3b on the A side. In the first embodiment, the rectifier 7 is located at the shaft end 19, and the secondary coil 8 is located in the narrower area of ​​the cavity 9 or the transmission chamber 9b.

[0032] It goes without saying that the synchronous machine 1 also comprises a stator and a housing arranged so that the rotor assembly 2 rotates around an axis of rotation, however the stator and the housing are not explicitly shown here.

[0033] Figure 2 shows a cross-sectional view of an inductively electrically excited synchronous machine 1 according to the invention, comprising a rotor assembly 2 according to the invention in a second embodiment. The difference with respect to the first embodiment in Figure 1 is that the shaft end 19 has a larger axial length compared to the first embodiment in Figure 1. The secondary coil 8 is arranged in a larger area of ​​the cavity 9 or transmission chamber 9b, and is made more compact in the axial direction.

[0034] 3 shows a circuit diagram of an energy transfer device 6 in a synchronous machine 1 according to the invention. The energy transfer device 6 comprises a primary circuit 17 with a connection 21, an inverter 22 and a primary coil 18. The connection 21 may for example be provided for interconnecting the energy transfer device 6 to the on-board electronics of a motor vehicle. The energy transfer device 6 further comprises a secondary circuit 5 with a secondary coil 8, a rectifier 7 and a rotor winding 23 of the rotor.

Claims

1. A rotor assembly (2) for an inductively electrically excited synchronous machine, comprising: The rotor assembly (2) includes a hollow shaft (3) rotatable about a rotation axis (RA) and a rotor (4) connected to the hollow shaft (3) so as not to rotate relative to the hollow shaft (3); The rotor assembly (2) has a secondary circuit (5) of an energy transmission device (6), the secondary circuit (5) being arranged not to rotate relative to the rotor assembly (2); The secondary circuit (5) comprises: a rectifier (7) comprising a printed circuit board (10) and at least one electrical component (11) fixed to said printed circuit board (10); A secondary coil (8); having The flow straightener (7) is aligned transversely to the rotation axis (RA) and arranged to be non-rotatable relative to the cavity (9) of the hollow shaft (3); The rectifier (7) has a cooling body (12) made of a thermally conductive material, a cooling body (12) located opposite the at least one electrical component (11) and adjacent to the printed circuit board (10) of the rectifier (7) in a heat-transferring manner.

2. 2. The rotor assembly of claim 1, A rotor assembly, characterized in that at least one of said electrical components (11) of said rectifier (7) is mechanically supported on said hollow shaft (3).

3. 3. The rotor assembly according to claim 1, The hollow shaft (3) is formed by a shaft end (19) and a shaft cover (20) that axially closes the shaft end (19), A rotor assembly, characterized in that the flow straightener (7) is rigidly connected to the shaft end (19) of the hollow shaft (3) or to the shaft cover (20).

4. 3. The rotor assembly according to claim 1, At least one of the electrical components (11) of the rectifier (7) is encapsulated with a thermally conductive molding compound; and / or At least one of the electrical components (11) of the rectifier (7) is thermally connected to the printed circuit board (10) via a thermally conductive pad; and / or 11. A rotor assembly, comprising: at least one printed circuit board (10) of said rectifier (7) connected to said cooling body (12) via a thermally conductive pad in a thermally conductive manner.

5. 3. The rotor assembly according to claim 1, the cooling body (12) is electrically insulated from the hollow shaft (3) by a dielectric covering; and / or A rotor assembly, characterized in that the cooling body (12) is made of a dielectric material, preferably a composite material.

6. 3. The rotor assembly according to claim 1, The rotor assembly is characterized in that the cooling body (12) has a cooling structure (15) located on the opposite side to the printed circuit board (10), preferably at least one cooling rib (16) and / or at least two cooling pins.

7. 3. The rotor assembly according to claim 1, a cooling body (12) dividing the cavity (9) of the hollow shaft (3) in a fluid-tight manner into a cooling chamber (9a) located on the side opposite the printed circuit board (10) and through which a liquid or gaseous cooling fluid can pass, and a transmission chamber (9b) accommodating the printed circuit board (10).

8. 8. The rotor assembly of claim 7, The hollow shaft (3) has an axial end (3a) that opens to the outside and communicates with the cooling chamber (9a); the cooling fluid can enter the cooling chamber (9a) of the hollow shaft (3) through the open axial end (3a); The hollow shaft (3) has at least one opening (14) communicating radially outward from the cooling chamber (9a); A rotor assembly, characterized in that said cooling fluid can exit said cooling chamber (9a) of said hollow shaft (3) through at least one said opening (14).

9. 3. The rotor assembly according to claim 1, a secondary coil (8) of the secondary circuit (5) arranged within the cavity (9) of the hollow shaft (3) or outside the cavity (9) of the hollow shaft (3) so as to inductively interact with a primary circuit (17) of the energy transfer device (6).

10. A synchronous machine (1), The synchronous machine (1) comprises a rotor assembly (2) according to claim 1, The synchronous machine (1) has a stator assembly including a stator, The rotor assembly (2) is accommodated in the stator so as to be rotatable around the rotation axis (RA), The stator assembly includes a primary circuit (17) of the energy transfer device (6) of the inductive type; The primary circuit (17) is arranged not to rotate relative to the stator assembly; The primary circuit (17) includes an inverter (22) and a primary coil (18). A synchronous machine, characterized in that the primary coil (18) and the secondary coil (8) are arranged so as to be capable of inductively interacting with each other.

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