Rotor for motor

Abstract

The present invention relates to a rotor (1) for an electric motor (2), the rotor having a rotor shaft (3) designed as a hollow shaft having an inner surface (5). To enable internal rotor cooling, the invention provides: - a hollow inner shaft (6) disposed within the rotor shaft (3) and having at least one opening (7) at its center for spraying a cooling medium (8) onto the inner surface (5) of the rotor shaft (3) and cooling the cooling medium; - two end plates (9, 10) provided that define an internal space (11) of the rotor shaft (3) in the axial direction (12), wherein each end plate (9, 10) has a central through-hole (13, 14) through which the inner shaft (6) is guided; - at least one outlet opening (15) for discharging the cooling medium (8) is provided in each end plate (9, 10) and / or on the side of the rotor shaft (3).

Description

Technical Field

[0001] This invention relates to a rotor for an electric motor, the rotor having a rotor shaft and a rotor core, wherein, according to the preamble of claim 1, the rotor shaft is designed as a hollow shaft having an inner surface. The invention also relates to an electric motor having such a rotor. Background Technology

[0002] DE102018221569A1 discloses a universal rotor for an electric motor, comprising a rotor shaft having a rotor core, wherein the rotor shaft is designed at least segmentally as a hollow shaft with an inner wall, and wherein a fluid spray gun for internal rotor cooling is introduced into the hollow shaft. The inner wall of the hollow shaft is equipped with impact bulges to improve the distribution of cooling fluid.

[0003] Modern electric motors, or modern electric motors, due to their high speed or high power, typically require targeted and cost-effective cooling, for which internal rotor cooling is known. However, such internal rotor cooling is relatively complex and therefore expensive.

[0004] Therefore, the present invention relates to the problem of specifying and improving or at least replacing embodiments for general types of rotors, which in particular overcomes the disadvantages known in the prior art.

[0005] According to the invention, this problem is solved by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims. Summary of the Invention

[0006] The present invention is based on the following general concept: providing internal rotor cooling for the rotor of an electric motor, particularly a motor, wherein an inner shaft is provided for this purpose, which is rotatably fixed to the rotor shaft and has at least one corresponding opening. The rotor according to the invention has a rotor shaft having a rotor core (e.g., a laminated core), wherein the rotor shaft is designed in this case as a hollow shaft with an inner surface. According to the invention, the hollow inner shaft is then provided in the hollow shaft and has at least one opening at least at its axial center for spraying cooling medium onto the inner surface of the rotor shaft, and wherein two end plates defining the internal space of the rotor shaft in the axial direction are provided, wherein each end plate has a central through-hole through which the inner shaft is guided and held. Of course, multiple openings can also be provided. At least one outlet opening for discharging cooling medium is provided in each end plate and / or on the side of the rotor shaft. By coupling the inner shaft, which guides the cooling medium, to the rotor shaft via end plates, internal rotor cooling can be established by relatively easily introducing the cooling medium into the rotor shaft. Since the inner shaft is fixed to the two end plates provided according to the invention, this also offers significant advantages in terms of sealing, for example, compared to a fixed fluid spray gun extending into the internal space of the rotor shaft. Therefore, the rotor shaft can also theoretically be designed as a prefabricated assembly along with the two end plates and the inner shaft, enabling rapid installation of the rotor shaft, for example, in an electric motor.

[0007] A distribution element for distributing the cooling medium in the axial direction is suitably disposed on the inner surface radially outward of at least one opening. When the rotor rotates rapidly and the cooling medium is discharged through at least one opening of the hollow inner shaft, the cooling medium is splashed onto the inner surface of the rotor shaft due to centrifugal force, where it is distributed axially by the distribution element. Thus, uniform cooling of the inner surface and therefore uniform cooling of the internal rotor is possible. Furthermore, the cooling medium flows in the direction of the end plate and can exit the rotor shaft again there through at least one corresponding outlet opening.

[0008] Valve elements are suitably designed as rings, particularly as retaining rings. This allows for relatively simple installation of the dispensing element in the rotor shaft via such rings, especially retaining rings. Furthermore, in the case of retaining rings, for example, an inwardly opening annular groove can be formed on the inner surface of the rotor shaft, wherein the dispensing element is at least partially engaged in and held within this annular groove. In this case, the dispensing element designed as a retaining ring can be compressed, inserted into the rotor shaft, and released in the region of the inwardly opening annular groove, whereby the retaining ring engages in the annular groove and is reliably secured there. Therefore, no further installation or securing steps are required.

[0009] In a further advantageous embodiment of the rotor according to the invention, the dispensing element is applied to the inner surface of the rotor shaft by injection molding. In this case, the dispensing element can also be manufactured relatively easily by simply inserting an injection molding gun into the rotor shaft and then injection molding the dispensing element onto the inner surface of the rotor shaft. Alternatively, it is of course conceivable to retain the dispensing element, designed as a metal or plastic ring, in the rotor shaft by press fitting, so that such a dispensing element only needs to be pressed into the rotor shaft by a corresponding mounting aid.

[0010] Alternatively, it can be provided that the rotor shaft is formed of two parts connected to each other at their ends via friction welding, wherein weld beads formed during the friction welding process form distribution elements. These weld beads are removed from the outer surface, while the weld beads form distribution elements on the inner surface. In this case, separate installation of the distribution elements is not required.

[0011] Alternatively, the dispensing elements can be manufactured by means of imprinting or tapering. For this purpose, for example, imprinting rollers can be guided to extend along the outer surface of the rotor shaft, wherein these imprinting rollers deform axially inward of the rotor due to radial pressure, thereby creating protrusions on the inner surface of the rotor shaft to form subsequent dispensing elements.

[0012] Alternatively, the distribution element can also be designed to guide pins, particularly heavy-duty roller pins, through the rotor shaft. Such pins can, for example, have a square cross-section, and typically at least two, and in particular even four, such pins are provided to prevent imbalance of the rotor shaft.

[0013] The distribution element suitably has a triangular, circular, or angular cross-sectional shape with an inwardly pointing tip. In particular, the triangular cross-sectional shape with an inwardly pointing tip, which deflects the flow of the cooling medium impacting the distribution element in the axial direction, provides a significant advantage for uniform internal rotor cooling.

[0014] The at least one opening is suitably introduced into the inner shaft by means of drilling, punching, or embossing. Even this incomplete list shows various possibilities for creating the at least one opening in the inner shaft, among which, in pure theory, it is even possible to make subsequent adjustments by introducing other openings in the hollow inner shaft.

[0015] In a further advantageous embodiment of the rotor according to the invention, the inner shaft is closed at the end plate by means of a plug. In this case, the cooling medium is supplied to the hollow inner shaft only from one side, while the other side is closed by means of a plug. This provides a significant advantage that the cooling power can be controlled or regulated by establishing a controllable or regulated pressure of the cooling medium in the inner shaft, thereby controlling or regulating the discharge rate.

[0016] The present invention is also based on the general concept of equipping the motor with a rotor corresponding to the foregoing paragraphs. This allows for the creation of a motor that can be optimally cooled via internal rotor cooling, thereby providing higher power.

[0017] Other important features and advantages of the invention can be derived from the dependent claims, the drawings, and the related description of the drawings.

[0018] It should be understood that, without departing from the scope of the invention, the features mentioned above and described below can be used not only in their respective specified combinations, but also in other combinations or individually.

[0019] Preferred exemplary embodiments of the present invention are shown in the accompanying drawings and will be described in more detail in the following description, wherein the same reference numerals denote the same or similar or functionally identical parts. Attached Figure Description

[0020] In their respective diagrams,

[0021] Figure 1 A cross-sectional view of the rotor according to the invention for use in an electric motor according to the invention is shown.

[0022] Figure 2 A cross-sectional view of one possible embodiment of the rotor shaft is shown.

[0023] Figure 3 It shows the relationship with Figure 2 The same representation, but with a distribution element formed by friction solder beads.

[0024] Figure 4 Another cross-sectional view of a rotor shaft with multiple distribution elements according to the present invention is shown.

[0025] Figure 5 It shows the relationship with Figure 4 Same cross-sectional view, but with different assigned elements.

[0026] Figure 6 A cross-sectional view of a rotor shaft with a distribution element designed as a pin is shown. Detailed Implementation

[0027] according to Figure 1According to the invention, the rotor 1 for a motor 2 (e.g., an electric motor or generator) according to the invention has a rotor shaft 3 (see also, in particular, the rotor 1 for a motor 2 (not shown separately) has a rotor shaft 3 (see also, in particular, the rotor 1 for a motor 2 (e.g., an electric motor or generator) according to the invention has a rotor shaft 3 (see also, in particular, the rotor 1 for a motor 2 (not shown separately) has a rotor shaft Figures 2 to 6 A rotor core 4 (e.g., a laminated core) is provided on the outer surface of the rotor shaft. For example, from... Figures 1 to 6 It can be seen that the rotor shaft 3 is designed as a hollow shaft with an inner surface 5. According to the invention, a hollow inner shaft 6 is now disposed within the rotor shaft 3, having at least one opening 7 at its center (viewed in the axial direction 12) for spraying the cooling medium 8 onto the inner surface 5 of the rotor shaft 3. Two end plates 9 and 10 are also provided, defining an internal space 11 of the rotor shaft 3 in the axial direction 12, and each end plate 9, 10 has a central through-hole 13, 14 through which the inner shaft 6 is guided. Furthermore, at least one outlet opening 15 for discharging the cooling medium 8 is provided in each end plate 9, 10 and / or in the side surface of the rotor shaft 3. Therefore, discharging the cooling medium 8 via the rotor core 4 is generally also feasible.

[0028] The rotor 1 according to the invention enables internal rotor cooling and thus particularly uniform cooling of the rotor 1, thereby increasing the performance of the motor 2 equipped with the rotor 1.

[0029] At least one dispensing element 16 for dispensing the cooling medium 8 in the axial direction 12 is disposed on the inner surface 5 of the rotor shaft 3 on the radially outer side of the at least one opening 7. If the cooling medium 8 flows out of the inner shaft 6 into the inner space 11 through its at least one opening 7, the cooling medium is thus deflected in the axial direction 12 after impacting the dispensing element 16 so as to preferably be able to uniformly cool the entire inner surface 5 of the rotor shaft 2.

[0030] The dispensing element 16 can be designed as a ring (e.g., a retaining ring), wherein, it is also conceivable, an inwardly opening annular groove 17 is provided on the inner surface 5 of the rotor shaft 3, wherein the dispensing element 16 at least partially engages into and remains within the annular groove. This type of annular groove 17 can be very advantageous, especially when the dispensing element 16 is designed as a retaining ring, because in this case, in order to be installed in the rotor shaft 3, the dispensing element 16 only needs to be slightly compressed until it is pushed to the axial center of the rotor shaft 3, where it self-locks into the annular groove 17.

[0031] If observe Figure 1 It can be seen that the distribution element 16 has an angular, particularly rectangular, cross-sectional shape. In pure theory, it is also conceivable that the distribution element 16 has a triangular cross-sectional shape with an inwardly pointing tip, which serves as a distributor. A circular cross-sectional shape is also conceivable in pure theory.

[0032] Typically, the distribution element 16 can also be applied to the inner surface 5 of the rotor shaft 3 by injection molding. This offers the significant advantage of not only being able to manufacture a relatively simple annular distribution element 16, but also being able to manufacture, for example, inclined profiles (such as...). Figure 4 (As shown). This distribution element 16, formed by many individual components, also ensures the deflection of the flow of the cooling medium 8 in the axial direction 12. If observed... Figure 2 There you can see the rotor shaft 3, where the distribution element 16 is manufactured by means of embossing or tapering.

[0033] according to Figure 3 The rotor shaft 2 shown is made of two parts 18a and 18b, which are connected to each other via friction welding 19, wherein weld beads 20 form distribution elements 16 on the inner surface 5. Furthermore, the weld beads 20 may also be as... Figure 4 The distribution element 16 shown can cause the cooling medium 8 to form vortices, thereby also achieving improved cooling.

[0034] If observe Figure 5 It can be seen that the dispensing element 16 is designed as an inwardly extending thickened portion of material in this case, which also allows the dispensing element 16 to be manufactured in a relatively simple manner. If we consider according to... Figure 6 The distribution element 16 is designed to guide the pins 21, particularly heavy-duty roller pins, through the rotor shaft 3. These roller pins have a rectangular or rhomboid cross-section and, upon rotation, separate the cooling medium 8 ejected from at least one opening 7 in the axial direction 12. To avoid imbalance in the rotor shaft 3, at least two such pins 21 are arranged on opposite sides of the rotor shaft 3.

[0035] Obviously, in pure theory, at least two openings 7 offset in the axial direction 12 can also be provided on / in the inner shaft 6, wherein, in this case, even in pure theory, the distribution element 16 can be omitted on the inner side surface 5 of the rotor shaft 3, as long as enough such openings 7 are provided on the inner shaft 6 in the axial length.

[0036] The at least one opening 7 on the inner shaft 6 can be introduced, for example, by drilling, punching, or embossing. The inner shaft 6 can be introduced at the end plates 9 and 10 by means of a plug 22, according to... Figure 1The end plate 9 is closed, thus, in this case of the inner shaft 6, the supply of cooling medium is from the right side. The inner shaft 6 can protrude beyond the rotor shaft 3 and rotor core 4 in the axial direction 12 and has a support point 23 for mounting the rotor 1. In this case, a corresponding bearing (e.g., a ball bearing) can also be provided on the inner shaft 6 or between it and the housing of the motor 2 (not shown). This provides the great advantage that the inner shaft 6 can be used not only for cooling the rotor shaft 3, but also for mounting the rotor 1.

[0037] The inner shaft 6 can be pressed into the through holes 13 and 14 of the end plates 9 and 10, thereby being securely anchored in the through holes. The end plates 9 and 10 are then securely pressed into or, for example, glued to their outer surfaces. The inner diameter of the distribution element 16 is typically smaller than the inner diameter of the rotor shaft 3.

[0038] In summary, by using the rotor 1 according to the invention, significantly improved rotor cooling (due to its more uniformity) can be achieved, thereby increasing the power of the motor 2.

Claims

1. A rotor (1) for an electric motor (2), said rotor having a rotor shaft (3) designed as a hollow shaft, said rotor shaft having an inner surface (5), Its features are, - A hollow inner shaft (6) is disposed in the rotor shaft (3) and has at least one opening (7) at at least one axial center for spraying cooling medium (8) onto the inner surface (5) of the rotor shaft (3) and cooling the cooling medium. - Two end plates (9, 10) are provided that define the internal space (11) of the rotor shaft (3) in the axial direction (12), wherein each end plate (9, 10) has a central through hole (13, 14) through which the inner shaft (6) is guided. - At least one outlet opening (15) for discharging cooling medium (8) is provided in each end plate (9, 10) and / or on the side of the rotor shaft (3); and - The inner shaft (6) protrudes beyond the rotor shaft (3) and rotor core (4) in the axial direction (12) and has a support point (23) for mounting the rotor (1).

2. The rotor according to claim 1, Its features are, A dispensing element (16) for dispensing cooling medium (8) in the axial direction (12) is disposed on the inner side (5) on the radially outer side of the at least one opening (7).

3. The rotor according to claim 2, Its features are, The distribution element (16) is designed as a ring.

4. The rotor according to claim 3, Its features are, An inwardly opening annular groove (17) is provided on the inner side (5) of the rotor shaft (3), and the dispensing element (16) is at least partially engaged in and held in the annular groove.

5. The rotor according to claim 2, Its features are, - The dispensing element (16) is applied to the inner surface (5) of the rotor shaft (3) by means of injection molding, or - The rotor shaft (3) is formed of two parts (18a, 18b), which are connected to each other by friction welding (19), wherein weld beads (20) form the distribution element (16). -The dispensing element (16) is manufactured by means of embossing or tapering, or - The distribution element (16) is designed to guide the pin (21) through the rotor shaft (3).

6. The rotor according to any one of claims 2 to 5, Its features are, The distributing element (16) has a triangular cross-sectional shape, a circular cross-sectional shape, or an angular cross-sectional shape with an inwardly pointing tip.

7. The rotor according to any one of claims 1 to 5, Its features are, At least two openings (7) offset in the axial direction (12) are provided on the inner shaft (6).

8. The rotor according to any one of claims 1 to 5, Its features are, The at least one opening (7) is introduced into the inner shaft (6) by means of drilling, punching or stamping.

9. The rotor according to any one of claims 1 to 5, Its features are, The inner shaft (6) is closed at the end plates (9, 10) by means of a plug (22).

10. The rotor according to any one of claims 1 to 5, Its features are, The inner shaft (6) is pressed into the through holes (13, 14) through the end plates (9, 10), thereby being firmly anchored in the through holes.

11. The rotor according to any one of claims 1 to 5, Its features are, The end plates (9, 10) are firmly pressed into the rotor shaft (3) on their outer surfaces.

12. The rotor according to claim 3, Its features are, The ring is a retaining ring.

13. The rotor according to claim 5, Its features are, The pin (21) is a heavy-duty rolling pin.

14. The rotor according to any one of claims 1 to 5, Its features are, The end plates (9, 10) are bonded to the rotor shaft (3) on their outer surfaces.

15. An electric motor (2) having a rotor (1) according to any one of claims 1 to 14.

Images