Rotor plate for an electric motor rotor, rotor for an electric motor and electric motor

Description

[0001] The invention relates to a rotor for an electric motor of the type defined in more detail in the preamble of claim 1. Furthermore, the invention relates to an electric motor comprising a stator and a rotor.

[0002] A rotor of the generic type for an electric motor is known from EP 0 299 100 A1.

[0003] US 2016 / 0352165 A1 describes a rotor package for an electric motor.

[0004] Another rotor for an electric motor, which has a rotor pack formed from several rotor laminations and a rotor shaft mounted in a bore of the rotor pack, is described in DE 10 2012 012 624 A1.

[0005] A permanent magnet motor with a rotor rotatable about an axis of rotation and with several permanent magnets arranged in receptacles of a laminated core composed of axially stacked laminations is described in DE 10 2007 000 213 A1.

[0006] From DE 295 00 984 U1 an electromechanical adjustment drive for a gearbox is known, in which a positive-locking connection of a rotor lamination stack to an injected rotor shaft is achieved by means of positive-locking projections.

[0007] In DE 10 2017 212 870 A1 a rotor for an electric motor is described with a rotor carrier and a rotor package, which are connected to each other by means of keys.

[0008] WO 2015 / 048955 A2 describes a rotor for an electric motor in which a bore of a main body has several projections extending into the bore.

[0009] WO 2006 / 064860 A1 describes an electric motor with a stator and a rotor. The rotor has a rotor shaft which has knurling in the area where a plastic insulating body is connected to it.

[0010] US patent 2019 / 181727 A1 discloses an electric motor with a rotor shaft that has a thread for attaching a fan.

[0011] The JP H09 93878 A describes a rotor for an electric motor which has raised and recessed areas running obliquely to the longitudinal axis.

[0012] However, all known connections between the rotor shaft and the rotor lamination stack can only transmit a limited amount of torque. Often, especially in AC-powered electric motors, a crimping compound is applied between the rotor shaft and the rotor lamination stack to provide electrical insulation. However, this compound can shrink as it hardens, further reducing the torque that can be transmitted from the rotor lamination stack to the rotor shaft.

[0013] It is therefore an object of the present invention to create a rotor for a permanent magnet electric motor operated with alternating current, which has the best possible connection between the rotor lamination and the motor in order to be able to transmit the highest possible torques.

[0014] According to the invention, this problem is solved by the features mentioned in claim 1.

[0015] This rotor allows for the transmission of very high torques and achieves very good values ​​in terms of its durability.

[0016] The recesses according to the invention, which extend from the bore serving to receive the rotor shaft into the rotor lamination, enable a very good connection of the rotor lamination stack with the rotor shaft to be achieved, so that very high torques can be transmitted to a rotor shaft which is connected to a rotor lamination stack formed from several rotor laminations according to the invention.

[0017] The different slopes with which the radius provided at the point of the recess furthest from the center of the bore is connected to the circumference of the bore result in an equally high transmission of torque in both possible directions of rotation of the rotor shaft.

[0018] Furthermore, the design of the recesses according to the invention reliably prevents damage to the rotor sheet that could result from the transmission of torque to the rotor shaft.

[0019] In order to further improve the properties of the rotor sheet according to the invention for use in different directions of rotation, it is also provided that some of the recesses, viewed clockwise, have a greater slope on the left side than on the right side, and that some of the recesses, viewed clockwise, have a greater slope on the right side than on the left side.

[0020] Furthermore, the fact that the bore has an even number of recesses allows for even better adaptation of the rotor sheet to different directions of rotation.

[0021] Furthermore, it is provided that the recesses, which, viewed clockwise, have a steeper slope on the left side than on the right side, and the recesses, which, viewed clockwise, have a steeper slope on the right side than on the left side, are arranged alternately. This represents a particularly advantageous embodiment with regard to reversing the direction of rotation of the electric motor equipped with several rotor lamination stacks connected to form a rotor lamination stack and fitted with a rotor shaft.

[0022] A particularly good connection between the rotor shaft and the rotor lamination stack is achieved by the fact that the rotor shaft has helical-like projections running around its circumference.

[0023] Furthermore, an insulating material is arranged between the rotor shaft and the rotor lamination stack. This reduces any vibrations and ensures the electrical operational reliability of such a rotor.

[0024] Claim 2 defines a permanent magnet excited, alternating current operated electric motor with a stator and with a rotor according to the invention.

[0025] Such an electric motor is capable of transmitting significantly higher torques than is the case with known electric motors.

[0026] It should also be noted that terms such as "comprehensive," "exhibit," or "with" do not exclude other characteristics or steps. Furthermore, terms like "a" or "that," which indicate a singular set of steps or characteristics, do not exclude a plurality of characteristics or steps, and vice versa.

[0027] Further features and advantages of the invention will become apparent from the following description of an exemplary embodiment of the invention. The figures show several features of the invention in combination with one another. Of course, a person skilled in the art can also consider these features separately and, if necessary, combine them into further meaningful sub-combinations without having to make any inventive contributions.

[0028] They show schematically: Figure 1 shows a section through an electric motor according to the invention with a stator and a rotor; Figure 2 shows a section along line II-II from Fig. 1 ; and Figure 3 shows a front view of a rotor sheet according to the invention.

[0029] Figure 1Figure 1 schematically depicts an electric motor 1, which, in a manner known per se, comprises a stator 2 and a rotor 3 arranged within the stator 2. The rotor 3 also comprises, in a manner known per se, a rotor shaft 4 and a rotor lamination stack 5. Preferably, the electric motor 1 is a permanent magnet excited, AC-driven electric motor 1 or a brushless motor. However, it can also be a DC-driven electric motor 1.

[0030] Figure 2 shows a cut along the line II-II out of Figure 1 The figure shows a stator lamination 6 and a rotor lamination 7. Several of the stator laminations 6, together with a winding (not shown), form the stator 2. InSimilarly, several of the rotor laminations 7 form the rotor lamination stack 5. Together with the rotor shaft 4, which is received in a central bore 8 of the rotor lamination 7, and the respective magnets 10, which are received in magnet pockets 9 of the rotor lamination 7, the rotor laminations 7 form the rotor 3.

[0031] In Figure 3One of the rotor laminations 7 is shown in detail. It can be seen that the rotor lamination 7 is symmetrical, at least with regard to the majority of its features, and has several axes of symmetry 11 running in the plane in which the rotor lamination 7 extends. Furthermore, it can be seen that the rotor lamination 7 has four magnet pockets 9 arranged at 90 degrees to each other. In principle, a different number of magnet pockets 9 could also be provided, i.e., it could be a different multipole arrangement; however, this number of magnet pockets 9 and the magnets 10 arranged therein has proven to be optimal with regard to maximum power output. The exact design of the number and arrangement of the magnet pockets 9 generally depends on the rotational speed requirement. For the sake of clarity, only one of the magnets 10 in one of the magnet pockets 9 is indicated by dashed lines.Naturally, in the electric motor 1 with a rotor lamination stack 5 formed from several rotor laminations 7, magnets 10 are housed in each of the magnet pockets 9. The magnets 10 are arranged alternately with their north pole and their south pole facing outwards in the magnet pockets 9.

[0032] Since, as described above, the rotor lamination 7 has several axes of symmetry 11, all of the magnet pockets 9 are identical in this case. Therefore, the specific design of the magnet pockets 9 will be described below only with reference to one of the magnet pockets 9. Again, for the sake of clarity, all features are designated by reference numerals only for one of the magnet pockets 9.

[0033] The magnet pocket 9 has a substantially rectangular base shape with a transverse extent x extending substantially perpendicular to one of the axes of symmetry 11 of the rotor lamination 7 and a vertical extent y extending in the direction of the same axis of symmetry 11. This rectangular base shape of the magnet pockets 9 corresponds to the rectangular base shape of the magnets 10. However, the magnet pocket 9 has recesses 12 on both sides that increase its transverse extent x, so that free areas are formed laterally in the magnet pockets 9 which are not occupied by the magnets 10. The recesses 12 form a flux barrier. In this case, the recesses 12 have a substantially triangular base, with the longest side edge of the triangle abutting the magnet 10.

[0034] Stop elements 13 project into the recesses 12 on both sides, serving to secure the magnet 10 on both sides. The stop elements 13 thus reduce the area of ​​the recesses 12 and consequently the area of ​​the magnet pocket 9. It can be seen that the stop elements 13 are each arranged on the sides of the recesses 12 facing the outer circumference of the rotor plate 7. In other words, the stop elements 13 extend inwards from the outer circumference of the rotor plate 7, thus projecting into the recesses 12.

[0035] The distance between the two stop elements 13 in the direction of the transverse dimension x of the magnetic pockets 9 is slightly larger, for example 0.1 - 0.5 mm, in particular 0.2 - 0.4 mm, than the extent of the magnets 10 in the direction of the transverse dimension x, i.e., than the width of the magnets 10. This ensures easy mounting of the magnets 10 in the magnetic pockets 9.

[0036] Furthermore, the magnet pocket 9 has recesses 14 on its side facing away from the outer circumference of the rotor plate 7, i.e., on the side facing the bore 8 for the rotor shaft 4. These recesses 14 are adjacent to the recesses 12 and increase the area of ​​the magnet pockets 9. It can be seen that the recesses 14, similar to the recesses 12, contribute to an additional deviation of the area of ​​the magnet pocket 9 from the generally rectangular base. The magnets 10 therefore do not extend into the recesses 14.

[0037] The cutouts 14 reduce the area of ​​the rotor lamination 7 in the region of a web 15 located between two adjacent magnets 10, thus ensuring the desired magnetic flux distribution. Furthermore, short-circuit currents between like poles of the magnets 10 are prevented. The flux barrier formed by the cutouts 12 is increased or reinforced by the cutouts 14.

[0038] In the present case, the recesses 14 have a substantially triangular base, with one apex of the triangular base of the recess 14, facing away from the outer circumference of the rotor plate 7, being rounded. Furthermore, it is evident that a straight outer edge of the recess 14 aligns with a straight outer edge of the corresponding recess 12, i.e., that the recess 14 continues the recess 12 in this area.

[0039] The stop elements 13 can extend so far into the recess 12 that the magnet 10 rests in the area where the straight outer edge of the recess 12 transitions into the straight outer edge of the recess 14.

[0040] The space within the magnet pocket 9 not occupied by the magnet 10, in particular the area of ​​the recesses 12 on both sides and the indentations 14 on both sides, can be filled with a potting material not shown, so that the magnets 10 are securely held in the rotor lamination stack 5 formed by the rotor laminations 7.

[0041] The size of the recesses 12 and the indentations 14 depends, among other things, on the size and geometric shape of the magnetic pocket 9 and on the desired effect of the flux barriers formed thereby.

[0042] In Figure 3It can also be seen that the bore 8 of the rotor lamination 7 has several recesses 16 around its circumference, which increase the area of ​​the bore 8 and serve to engage projections 17 of the rotor shaft 4. The shape of the projections 17 of the rotor shaft 4 is adapted to the shape of the recesses 16 of the bore 8, which is described in detail below. An insulating material 18 is arranged between the rotor shaft 4 and the rotor lamination stack 5.

[0043] The recesses 16 are shaped like hills and have a radius 19 at their point furthest from the center of the bore 8. The transitions from the radius 19 to the circumference of the bore 8 have different slopes on both sides of the recess 16. For example, at least one of the transitions from the radius 19 to the circumference of the bore 8 can be formed by a radius. Alternatively or additionally, at least one of the transitions from the radius 19 to the circumference of the bore 8 can be formed by a straight line. Of course, it is also possible that one of the transitions from the radius 19 to the circumference of the bore 8 is formed by a radius and the other transition by a straight line.

[0044] Viewed clockwise, some of the recesses 16 have a steeper slope on their left side than on their right side, while others have a steeper slope on their right side than on their left. The different recesses are mirror images of each other, meaning there are only two different shapes of recesses 16. It is particularly advantageous that the shape and arrangement of the recesses 16 are point-symmetrical about the center of the bore 8. In this context, the bore 8 has an even number of recesses 16.Furthermore, the recesses 16, which, viewed clockwise, have a steeper slope on the left side than on the right, and the recesses 16, which, viewed clockwise, have a steeper slope on the right side than on the left, are arranged alternately. The recesses 16 are equidistant from each other. Since there are a total of 12 recesses 16 in this case, they are each offset from one another by an angle of 30 degrees. Naturally, the individual recesses 16 are not symmetrical, but, as explained above, have different slopes on their two sides.

Claims

1. Rotor (3) for a permanently excited, alternating current-powered electric motor (1) having a rotor shaft (4) and a rotor laminated core (5), which has rotor laminations (7), the rotor laminations (7) having a bore (8) for receiving the rotor shaft (4), the bore (8) having several recesses (16) on its circumference, the recesses (16) being hill-like in shape and having a radius (18) at their point furthest from the centre of the bore (8), the transitions from the radius (18) to the circumference of the bore (8) having different inclinations on both sides of the recesses (16), some of the recesses (16) viewed clockwise having a greater inclination on the left side than on the right side, some of the recesses (16) viewed clockwise having a greater inclination on the right side than on the left side, the bore (8) having an even number of recesses (16), the recesses (16) which, viewed clockwise, have a greater inclination on the left side than on the right side, and the recesses (16) which, viewed clockwise, have a greater inclination on the right side than on the left side, being provided alternately, an insulating material (17) being arranged between the rotor shaft (4) and the rotor laminated core (5), wherein the rotor shaft (4) has screw-like elevations extending around its circumference for connection between it and the rotor laminated core (5), and wherein twelve recesses (16) are provided, each offset from the other by an angle of 30°.

2. Permanently magnet-excited, alternating current-powered electric motor (1) having a stator (2) and a rotor (3) according to claim 1.