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DE-202026101638-U1 - Electric motor rotor and permanent magnet motor

DE202026101638U1DE 202026101638 U1DE202026101638 U1DE 202026101638U1DE-202026101638-U1

Abstract

Electric motor rotor comprising a rotor core (110) and magnets (120) positioned on an outer circumference of the rotor core (110), wherein the outer circumference of the rotor core (110) is provided with circumferentially spaced positioning elements, wherein each of the magnets (120) is fixed in a tangential direction between associated positioning elements, characterized in that each of the positioning elements is formed by a first rib (111) and a second rib (112), wherein the first rib (111) and the second rib (112) are spaced apart from each other in the axial direction of the rotor core (110) and each rib (111, 112) is V-shaped.

Assignees

  • BROSE FAHRZEUGTEILE SE & CO KG WUERZBURG

Dates

Publication Date
20260513
Application Date
20260324
Priority Date
20260324

Claims (13)

  1. An electric motor rotor comprising a rotor core (110) and magnets (120) positioned on an outer circumference of the rotor core (110), wherein the outer circumference of the rotor core (110) is provided with circumferentially spaced positioning elements, wherein each of the magnets (120) is fixed in a tangential direction between associated positioning elements, characterized in that each of the positioning elements is formed by a first rib (111) and a second rib (112), wherein the first rib (111) and the second rib (112) are axially are spaced apart in the direction of the rotor core (110) and each rib (111, 112) is V-shaped.
  2. electric motor rotor after Claim 1 , characterized in that the first rib (111) and the second rib (112) are arranged at the outermost points on both axial end faces (110a, 110b) of the rotor core (110).
  3. electric motor rotor after Claim 1 , characterized in that the first rib (111) and the second rib (112) are arranged in the axial direction at a certain distance from the corresponding axial end faces (110a, 110b).
  4. electric motor rotor according to one of the Claims 1 until 3 , characterized in that the angle (A) enclosing between the two legs (111a) of the V-shape is 60-150°.
  5. electric motor rotor according to one of the Claims 1 until 3 , characterized in that both legs (111a) of the V-shape are formed as obtuse-angled triangles, wherein one acute corner of the two obtuse-angled triangles runs towards each other and one obtuse corner of the two obtuse-angled triangles is arranged away from each other and close to the corresponding magnets (120).
  6. electric motor rotor after Claim 5 , characterized in that the height (T) of a side opposite the converging pointed corner is greater than 0.35 mm.
  7. electric motor rotor according to one of the Claims 1 until 3 , characterized in that the ratio of the width (W) of a section in which the rib (111, 112) is connected to the rotor core (110) in the circumferential direction of the rotor core (110) to the width (W_m) of the magnet (120) in the circumferential direction is less than 0.25.
  8. electric motor rotor according to one of the Claims 1 until 3 , characterized in that the ratio of the height (H) of the rib (111, 112) in the radial direction of the rotor core (110) to the minimum height (T_m) of the magnet (120) in the radial direction of the rotor core (110) at its two side edges (120a, 120b) is less than 0.3.
  9. electric motor rotor according to one of the Claims 1 until 3 , characterized in that the first rib (111) and the second rib (112) have the same thickness (L1, L2) in the axial direction of the rotor core (110) and a ratio of the thickness (L1, L2) of each rib to the length (L_r) of the rotor core (110) in the axial direction is less than or equal to 0.1.
  10. electric motor rotor according to one of the Claims 1 until 3 , characterized in that the ribs (111, 112) and the associated magnets (120) are designed with clearance, wherein the maximum clearance tolerance (G) is less than 0.12 mm.
  11. electric motor rotor according to one of the Claims 1 until 3 , characterized in that the rotor core (110) and/or the ribs (111, 112) are designed as sheet metal and/or that the material of the ribs (111, 112) and the rotor core (110) is the same.
  12. electric motor rotor according to one of the Claims 1 until 3 , characterized in that the ribs (111, 112) are formed integrally with the rotor core (110).
  13. Permanent magnet motor, characterized by an electric motor rotor (100) according to one of the Claims 1 until 12 .

Description

The present invention relates to the field of electric motors, in particular a permanent magnet motor and an electric motor rotor. The rotor of a permanent magnet motor typically comprises a rotor core and magnets positioned around the outer circumference of the rotor core. The magnets can be surface-mounted to the rotor core, for example, using adhesive. However, the adhesive requires curing time and is susceptible to aging, meaning it may not maintain its bond strength permanently. To prevent the magnets from detaching, a plastic cover is currently being attached to the outside of the rotor core. Figure 1 shows a current electric motor rotor 100' comprising a rotor core 110' and a plastic cover 120'. The rotor core 110' includes a central bore 111' for mounting a motor shaft, weight reduction 112', and positioning holes 113'. The plastic cover 120' includes circumferentially and axially distributed positioning projections 121', as well as defined positioning grooves 122' between the positioning projections for positioning the magnets. Also known is an electric motor rotor comprising a rotor core and magnets positioned on the outer circumference of the rotor core. The outer circumference of the rotor core is provided with several axially extending slots spaced around its circumference. The electric motor rotor further comprises several axial support arms made of plastic, some of which are injection-molded into the corresponding slots. Magnet receptacles are formed between adjacent axial support arms, into which the magnets are pressed and thus fixed. The axial length of the axial support arms can be less than or equal to the axial length of the slots. The current problem is that, due to the design of the positioning projections and the axial retaining arms, as well as the insufficient strength of the plastic, neither the positioning projections nor the retaining arms of the two aforementioned designs can guarantee the positional accuracy of the magnets. In particular, the magnets tend to shift tangentially, which leads to tangential assembly errors and consequently to torque fluctuations and cogging torque problems in the electric motor. Based on this, the invention aims to at least mitigate the problems mentioned above. For this purpose, the invention provides an electric motor rotor comprising a rotor core and magnets positioned on an outer circumference of the rotor core, wherein the outer circumference of the rotor core is provided with uniformly spaced positioning elements, each magnet being fixed tangentially between associated positioning elements. According to the invention, each of the positioning elements is formed by a first rib and a second rib, wherein the first rib and the second rib are spaced apart from each other in the axial direction of the rotor core, and each rib is V-shaped. According to one embodiment, the first rib and the second rib are arranged at the outermost points on both axial end faces of the rotor core. According to one embodiment, the angle enclosing between the two legs of the V-shape is 60-150°, preferably 85-90°. According to one embodiment, both legs of the V-shape are each formed as obtuse triangles, with one acute corner of each obtuse triangle converging towards the other and one obtuse corner pointing away from the other and close to the corresponding magnets. For example, the height T of a side opposite the converging acute corner is greater than 0.35 mm. According to one embodiment, the ratio of the width W of a section where the rib is connected to the rotor core in the circumferential direction of the rotor core to the width W_m of the magnet in the circumferential direction is less than 0.25. According to one embodiment, the ratio of the height H of the rib in the radial direction of the rotor core (i.e., a perpendicular distance from the highest point of the rib to the magnet) to the minimum height T_m (i.e., a minimum thickness) of the magnet in the radial direction of the rotor core near the two side edges of the magnet is less than 0.3. According to one embodiment, the first rib and the second rib are of equal thickness in the axial direction of the rotor core. Preferably, the ratio of the rib thickness to the length of the rotor core in the axial direction is less than or equal to 0.1. According to one embodiment, the ribs and the associated magnets are designed with sufficient clearance, with the maximum clearance tolerance being less than 0.12 mm. According to one embodiment, the rotor core and/or the ribs are designed as sheet metal. According to one embodiment, the material of the ribs and the rotor core is the same, e.g., magnetic steel. According to one embodiment, the ribs are formed integrally with the rotor core, for example by stamping them together with the rotor core. The invention further provides a permanent magnet motor comprising an electric motor rotor as described above. The design according to the invention increases the strength of the