Rotors for synchronous drive motors

Abstract

The invention relates to a rotor of a synchronous drive motor for an electric vehicle, comprising a plurality of rotor poles, wherein each rotor pole comprises at least three radially consecutive magnetic layers (16, 17, 18) with holes (10-34), wherein the outermost magnetic layer (18) comprises at least one hole (22) filled with a permanent magnetic material, and each other magnetic layer (17, 18) comprises at least two holes (26, 30) filled with a permanent magnetic material, and each magnetic layer (16, 17, 18) has a local extension range of an ellipse (36, 38, 40), and the centers of all ellipses (36, 38, 40) are located at In the smallest ellipse (36) of the outer magnetic layer (16), each hole belonging to one of the at least three magnetic layers defines a cross section (48+49) in a radial plane, each of the cross sections (48, 49) of one magnetic layer (16, 17, 18) being divided into two partial cross sections (48, 49) by the corresponding ellipse (16, 17, 18), and in the second and each other magnetic layer (17, 18), between the holes, connecting edges (56, 46) are formed by the rotor material, the width of the connecting edges (56, 46) being at least twice as wide as the respective outer connecting edges (50, 52) of the same magnetic layer (17, 18) at the narrowest point.

Description

Technical Field

[0001] The present invention relates to a rotor of a synchronous drive motor for an electric vehicle, which has a plurality of rotor poles, wherein each rotor pole has at least three U-shaped magnetic layers arranged one after the other, and each magnetic layer comprises a row of at least three holes, wherein at least the inner holes are filled with a permanent magnetic material, and the two outer holes are respectively closed with rotor gaps formed by outer connecting edges facing the stator. The present invention also relates to a synchronous drive motor equipped with the rotor and a vehicle equipped with such a drive motor. Background Art

[0002] Synchronous drive motors are often used as motors for electric vehicles because they have high torque and therefore high power density over the entire speed range and ensure high driving dynamics of the driven vehicle at low weight. In particular, such motors have a high Essonne efficiency and can therefore achieve a high cost-effectiveness ratio.

[0003] In a hybrid synchronous machine (HSM), the torque consists of two components, namely the reluctance torque and the synchronizing torque, and it is desirable to increase the reluctance torque share of the total torque as high as possible, ideally to at least 50%.

[0004] The rotor of the synchronous drive motor has a plurality of poles, each of which is provided with an embedded magnetic layer, which is basically U-shaped, symmetrically arranged around the pole center axis (i.e., the d-axis) and consists of a row of holes, in which permanent magnets are arranged. In most cases, the radially outermost holes remain empty and act as flux resistances, which guide the magnetic flux from the rotor into the stator as far as possible on each pole in the radial direction and minimize leakage. This can reduce the flux density fluctuations at the center of the air gap between the rotor and the spindle. In particular, leakage losses that reduce efficiency are generated along the radially outer rotor edge through the connecting edge between the outer peripheral surface and the respective radially outermost holes. Therefore, it is desirable to design the outer connecting edge as narrow as possible, but the large centrifugal force acting on the magnets located in the holes will cause deformation of the rotor if the outer connecting edge is too narrow, which in turn requires a wider connecting edge. Summary of the invention

[0005] The object of the present invention is to maximize both the synchronous torque and the reluctance torque in a rotor for a synchronous drive motor of this type while at the same time minimizing the flux harmonics and the leakage flux.

[0006] The invention is characterized by the features of the independent claims. Advantageous developments and embodiments are the subject matter of the dependent claims. Further features, possible applications and advantages of the invention are apparent from the following description and from the description of the exemplary embodiments of the invention shown in the figures.

[0007] This task is especially accomplished by

[0008] - the outermost magnetic layer comprises at least one cavity filled with a permanent magnetic material, and each of the other magnetic layers comprises at least two cavities filled with a permanent magnetic material,

[0009] - each magnetic layer has a local extension of an ellipse always having a major axis or main axis and a minor axis or minor axis, the minor axis substantially coinciding with the radial polar axis, ie the d-axis,

[0010] - where the centres of all ellipses are within the smallest ellipse of the outer magnetic layer,

[0011] - where the ratio of the two axes for all magnetic layers applies: 1.2 <X i <4, where X i =a i / b i ,

[0012] - where the ratio of the maximum X value to the minimum X value is not greater than 1.5,

[0013] wherein each hole belonging to one of the magnetic layers defines a cross section in a radial plane, and each of the cross sections of a magnetic layer is divided into two partial cross sections by the associated ellipse, wherein the area ratio of the partial cross sections of a cross section is between 1 / 3 and 3,

[0014] wherein in the second magnetic layer and in each further magnetic layer, between the holes a web is formed from the rotor material, the width of the web being at least twice as wide at the narrowest point as the respective outer web of the same magnetic layer.

[0015] The increase in the number of holes is important for each additional magnetic layer, because the magnets placed therein must also exert a force on the respective upper magnetic layer. As a result, the magnetic surface is firstly increased, which results in more eddy current losses. By dividing into multiple and thus smaller holes / magnets, the losses are reduced and the efficiency is increased.

[0016] The elliptical design of the poles, which are elongated in the circumferential direction (the ratio of the two axes of all magnetic layers is between 1.2 and 4), is extremely advantageous, because the weight is thus lower than if the poles were thicker. This results in a higher speed stability, whereby the webs between adjacent holes can be kept small. The so-called ratio is preferably between 1.5 and 3.

[0017] The ellipses, each with a major axis and a minor axis, are substantially coincident with the radial polar axis, i.e. the angle between the polar axis and the minor axis is less than 10°. In this case, the ellipses should have similar length ratios, i.e. the ratio of the maximum X value to the minimum X value should be no greater than 1.5, preferably no greater than 1.2. As a result, the thickness of the q flux path also becomes uniform, which helps to reduce saturation, thereby improving the efficiency of the motor and the frequency converter connected thereto. The centers of all ellipses must lie within the smallest ellipse of the outer magnetic layer, i.e. they should be arranged, for example, concentrically, since the regularity of the flux resistance has a positive influence on the torque ripple.

[0018] It is particularly advantageous if the holes with and without magnets lie uniformly against the ellipse, thereby also resulting in a regularity of the flux resistance and the flux path.

[0019] For the magnetic field, the shortest and simplest path is also the path along which the flux is directed. If the flux must have a simple possible way (for example, through a ferromagnetic material such as iron instead of air), like an excessively large outer bridge or connecting edge on the rotor circumference, the flux will take this shortcut as leakage flux, and no torque will be generated at this time. That is, with a thin outer bridge, the flux is forced to continue on the prescribed q flux path.

[0020] According to an advantageous development of the invention, the rotor is made of a plurality of metal sheets, the width of the outer connecting edge being at most twice the thickness of the metal sheet at the narrowest point. It is particularly advantageous in terms of magnetic properties to design the outer connecting edge to be as thin as possible. In terms of manufacturing technology, it is usually not possible to stamp out a connecting edge that is thinner than the thickness of the metal sheet. For acoustics and to prevent mechanical vibrations, the magnetic flux resistance should be closed all the way to the air gap. Therefore, a good ratio is not more than twice the thickness of the metal sheet, preferably 1-2 times the thickness of the metal sheet. The thickness of the metal sheet is generally in the range of 0.2-0.5 mm.

[0021] According to an advantageous development of the invention, the length of the outer web is at least four times the thickness of the metal sheet. Long and thin outer webs increase the so-called Salienz, i.e. the magnetoresistance-induction ratio Lq / Ld. In particular, the outer webs are responsible for a significant reduction in the Salienz. The Salienz losses are reduced with internal webs of the same size.

[0022] According to an advantageous improvement of the present invention, the connecting edge extends at an angle of 70°-110° relative to the associated ellipse. From a mechanical point of view, the connecting edge should be oriented along the force direction, so it is extremely advantageous that the connecting edge is arranged perpendicular to the tangent of the ellipse.

[0023] According to an advantageous development of the invention, the permanent magnet is formed in the shape of a cuboid and its longitudinal axis is located in at least one place within its extension parallel to the ellipse to which it belongs. The production of cuboid magnets is much simpler and cheaper than that of curved magnets. In particular, it is easier to grind the magnets to exact tolerances than with more complex shapes. The orientation of the magnets along the ellipse is extremely advantageous on the one hand, since this results in regular flux paths and flux resistances. When the magnets are arranged along the ellipse, a common magnetic polarization of the magnets along the surface normal, i.e. which points in each case towards the highest magnet, is particularly advantageous.

[0024] According to an advantageous refinement of the invention, permanent magnets are used that match the shape of the respective holes at least in a portion of the holes filled with permanent magnetic material. In this refinement, preferably all holes except the two radially outermost holes are equipped with permanent magnets. The edge holes are preferably empty in order to act as flux barriers and force the magnetic flux to turn radially and avoid leakage as much as possible. The edge holes should not be equipped with permanent magnets in any case, because this would subject the outer connecting edges to excessively high centrifugal loads, so that the outer connecting edges must be wider, which in turn causes leakage through them.

[0025] According to an alternative advantageous development of the invention, at least in a portion of the cavities filled with the permanent magnetic material, at least a portion of the cavities filled with the permanent magnetic material is filled with an injected, solidified and / or hardened substance containing the permanent magnetic material. In this development, during an injection process (e.g. by injection molding), the substance is injected into the cavity under high pressure, where it subsequently solidifies and / or hardens, especially when synthetic resins are used. In this design, according to an advantageous development, all cavities, i.e. including the outer cavities, can be filled with magnetic material, since the density of the magnetic material in the filled outer cavities and thus the centrifugal force is lower than when the magnet parts are placed there.

[0026] The invention comprises a synchronous drive motor having a rotor according to one of the above-described designs.

[0027] The present invention also includes a vehicle having such a synchronous drive motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further advantages, features and details emerge from the following description of at least one exemplary embodiment, which is described in detail with reference to the drawings, if necessary. Identical, similar and / or functionally identical components are provided with the same reference numerals, wherein:

[0029] Figure 1 A partial cross-sectional view of a first embodiment of a rotor for a synchronous drive motor is shown;

[0030] Figure 2A partial cross-sectional view of a second embodiment of a rotor for a synchronous drive motor is shown;

[0031] Figure 3 A diagram of the field lines through a synchronous drive motor in a pole region is shown.

[0032] Reference numerals list

[0033] 10a, b rotor

[0034] 12a, b Polar axis

[0035] 14 Stator

[0036] 16a, b Magnetic layer

[0037] 17a, b Magnetic layer

[0038] 18a, b Magnetic layer

[0039] 20a, b holes

[0040] 22a, b holes

[0041] 24a, b holes

[0042] 26a, b holes

[0043] 28a, b holes

[0044] 30a, b holes

[0045] 32a, b holes

[0046] 34a, b holes

[0047] 36a, b Ellipse

[0048] 38a, b Ellipse

[0049] 40a, b Ellipse

[0050] 42a, b Main axis

[0051] 44a, b Countershaft

[0052] 46a, b edge connection

[0053] 48a, b External edge

[0054] 49 Partial cross section

[0055] 50a, b External edge

[0056] 51 Partial cross section

[0057] 52a, b External edge

[0058] 54a, b edge connection

[0059] 56a, b edge connection

[0060] 58 Coil

[0061] 60 Magnetic Field Lines DETAILED DESCRIPTION

[0062] Figure 1 and Figure 2 The two figures show two embodiments of rotors 10a, 10b around the pole axes 12a, 12b. Typically, a rotor 10a, 10b has 6 to 10 poles, which are evenly distributed around the circumference. Radially outside the rotor 10a, 10b, the rotor is Figure 3 The stator 14 shown partially in FIG.

[0063] Each pole of the rotor 10a, 10b has three magnetic layers 16a, 16b, 17a, 17b, 18a, 18b, each magnetic layer consisting of a row of holes. Figure 1 In the figure, the radially outermost magnetic layer 16a includes three holes 20a, 22a, 20a, the middle magnetic layer 17a includes four holes 24a, 26a, 26a, 26a, 24a, and the innermost magnetic layer 18a includes four holes 28a, 30a, 30a, 28a.

[0064] Figure 2 The situation in FIG. 1 is similar, the only difference is that the innermost magnetic layer 18 b includes six holes instead of four, namely 32 b, 34 b, 34 b, 34 b, 34 b, 32 b. However, other numbers of holes may also be provided, for example, five holes may be provided in the third magnetic layer 18 b.

[0065] Figure 1 The three holes 20a, 22a, 20a of the outermost magnetic layer 16a of the embodiment are located on a part or partial area of ​​an ellipse 36a, the four holes 24a, 26a, 26a, 26a, 24a of the middle magnetic layer 17a are located on a part of a larger ellipse 38a, and the four holes 28a, 30a, 30a, 28a of the innermost magnetic layer 18a are located on a part of a larger ellipse 40a. The centers of all ellipses 36, 38, 40 are located in the smallest ellipse. Here, the center of an ellipse refers to the midpoint between the two foci of an ellipse. In accordance with Figure 2 In an embodiment, the condition is simulated.

[0066] exist Figure 1 For the smallest ellipse 36a and Figure 2 4 and 5. In FIG. 4, major axes 42a, 42b and minor axes 44a, 44b are shown for the largest ellipse 40b, respectively.

[0067] The respective ratios between the major axes 42a, 42b and the minor axes 44a, 44b, ie Xa=major axis 42a / minor axis 44a and Xb=major axis 42b / minor axis 44b, are between 1.2 and 4 for all ellipses 36-40. Figure 1 The ellipse 36a shown, Xa is about 1.6, for Figure 2 For the ellipse 40b shown, Xb is approximately 1.9.

[0068] In one embodiment of the invention, the cavities 20a, 24a, 28a or 20b, 24b, 28b at the edges are empty air cavities and serve as flux resistances for the magnetic lines of force. In contrast, permanent magnets are placed in the cavities 22a, 26a, 30a or 22b, 26b, 30b located in between. These permanent magnets are preferably cuboid-shaped, which simplifies manufacturing and assembly. The cavities 22a, 26a, 30a or 22b, 26b, 30b have extensions at their respective longitudinal ends so as to form connecting edges 46a, 46b with a specified cross section between the cavities.

[0069] In another embodiment, all cavities are filled with magnetic material, which is injected in the form of a plastic mass (eg by injection molding) and subsequently solidifies and / or hardens in the cavities.

[0070] in accordance with Figure 1 The left hole 30a in FIG. 1 shows that each hole defines a cross section (also 30a) in a radial plane, and each of the cross sections of the magnetic layer 18a is divided into two partial cross sections 49, 51 by the corresponding ellipse 40a, wherein the area ratio of the partial cross sections 49, 51 of a cross section 30a (ratio of the partial cross section 49 to the partial cross section 51) is between 0.5 and 2. Figure 1 In the case shown, the area ratio is approximately 1.

[0071] The outer connecting edge 48a, 50a, 52a or 48b, 50b, 52b is Figure 1 The outermost holes 20a, 24a, 28a and Figure 2 The outermost holes 20b, 24b, 28b of the respective rotors 10a, 10b extend between the outer edges of the respective rotors 10a, 10b. Between the holes, there are other connecting edges 54a, 54b in the outer magnetic layers 16a, 16b, connecting edges 56a, 56b in the middle magnetic layers 18a, 18b, and connecting edges 46a, 46b in the inner magnetic layer 18a.

[0072] In the middle and inner magnetic layers 17a, 18a, 17b, 18b, the width of the connecting edges 46a, 46b, 56a, 56b at the narrowest point is at least twice as wide as the respective outer connecting edges 50a, 50b, 52a, 52b of the same magnetic layers 17a, 17b, 18a, 18b.

[0073] Figure 3 Shown according to Figure 2 The invention comprises a rotor 10b, a stator 14 and a pole arrangement of magnetic lines of force. The stator 14 comprises a row of coils through which current flows, and the outer holes are formed into a cavity-like shape by the holes on the rotor side, and permanent magnets are arranged in the remaining holes. Figure 3 As can be seen in FIG. 1 , most of the magnetic flux lines 60 can be bundled to radially leave the rotor 10 b and enter the stator 14 .

[0074] Although the present invention is specifically shown and described in detail by preferred embodiments, the present invention is not limited to the disclosed examples, and the technician can deduce other changes therefrom without departing from the scope of protection of the present invention. It is therefore obvious that there are many possible changes. It is also obvious that the exemplified embodiments are actually only examples, which should not be understood in any way as limiting, for example, the scope of protection, the possibility of application or the configuration of the invention. On the contrary, the previous description and the accompanying drawings enable the technician to specifically implement the exemplary embodiments, where the technician who understands the disclosed inventive concept can, for example, make various changes related to the function or arrangement of some parts mentioned in the exemplary embodiments, without departing from the scope of protection defined by the claims and their legal equivalents (such as further description in the specification).

Claims

1. A rotor for a synchronous drive motor of an electric vehicle, the rotor having a plurality of rotor poles, wherein: Each rotor pole has at least three U-shaped magnetic layers (16, 17, 18) arranged radially one behind the other, and each magnetic layer (16, 17, 18) comprises a row of at least three holes (10-34), at least the inner holes (22, 26, 30, 34) of which are filled with permanent magnetic material, and the two outer holes (20, 24, 28) are respectively closed by outer connecting edges (48, 50, 52) towards the rotor gap formed by the stator (14), characterized in that: - the outermost magnetic layer (16) comprises at least one cavity (22) filled with a permanent magnetic material, and each of the other magnetic layers (17, 18) comprises at least two cavities (26, 30) filled with a permanent magnetic material, - each magnetic layer (16, 17, 18) has a local extension of an ellipse (36, 38, 40) having a major axis (42) and a minor axis (44), the minor axis substantially coinciding with the radial polar axis (d), - wherein the centers of all ellipses (36, 38, 40) are located inside the smallest ellipse (36) of the outer magnetic layer (16), - wherein the ratio of the two axes for all magnetic layers (16, 17, 18) applies: 1.2 <X i <4, where X i =a i / b i , - where the ratio of the maximum X value to the minimum X value is not greater than 1.5, - wherein each hole belonging to one of at least three of said magnetic layers defines a cross section (49+51) in a radial plane, and each of said cross sections (49+51) of a magnetic layer (16, 17, 18) is divided into two partial cross sections (49, 51) by the associated ellipse (16, 17, 18), wherein the area ratio of the respective partial cross sections (49, 51) of a cross section (49+51) is between 1 / 3 and 3, - wherein in the second magnetic layer and each other magnetic layer (17, 18), a connecting edge (56, 46) is formed from the rotor material between the holes and the width of the connecting edge (56, 46) is at least twice as wide as the respective outer connecting edge (50, 52) of the same magnetic layer (17, 18) at the narrowest point.

2. The rotor according to claim 1, characterized in that: The rotor is made of sheet metal, and the width of the outer connecting edge (48, 50, 52) is at most twice the thickness of the sheet metal at the narrowest point.

3. The rotor according to claim 2, characterized in that: The length of the outer connecting edge (48, 50, 52) is at least four times the thickness of the metal sheet.

4. The rotor according to any of the preceding claims, characterized in that The connecting edges (46, 54, 56) extend at an angle of 70° to 110° relative to the corresponding ellipse (36, 38, 40).

5. The rotor according to any of the preceding claims, characterized in that The permanent magnetic material is composed of a rectangular parallelepiped magnet, wherein the magnet defines a substantially rectangular cross section (49+51) in a radial plane, and the major axis of the cross-sectional rectangle is located in its extension range parallel to the corresponding ellipse (36, 38, 40) at at least one position.

6. The rotor according to any of the preceding claims, characterized in that Permanent magnet pieces matching the shapes of the respective holes (20-34) are installed in at least a portion of the holes (20-34) filled with the permanent magnetic material.

7. The rotor according to any of the preceding claims, characterized in that At least a portion of the cavities (20-34) filled with permanent magnetic material is filled with an injected, solidified or hardened substance containing permanent magnetic material.

8. A synchronous drive motor comprising a rotor according to any one of the preceding claims.

9. A motor vehicle comprising a synchronous drive motor according to the preceding claim.

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