The present invention discloses a motor comprising: a stator part; and a rotor assembly rotatably disposed with respect to the stator part, wherein the rotor assembly comprises: a ring magnet including an insertion hole with a shaft disposed therein and a plurality of first grooves formed at one side thereof along a first imaginary circle; and a core member including a body portion disposed between the shaft and the insertion hole, and an extension portion covering the plurality of first grooves, wherein the extension portion comprises a plurality of second grooves deviated from a plurality of first imaginary straight lines which pass from a center of the first imaginary circle respectively through the plurality of first grooves.
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1. A rotor comprising:
a shaft that extends in an axial direction from a lower end to an upper end;
a ring magnet including a first hole into which the shaft is inserted, the ring magnet having an upper surface; and
a core member disposed between the shaft and the ring magnetand including a resin material, and a part of the core member is on the upper surface of the ring magnet,
wherein the ring magnet includes a plurality of first recesses disposed on are formed in the ring magnet and open to the upper surface of the ring magnet,
wherein an upper surface of the core member is disposed on the upper surface of the ring magnet such that the upper surface of the core member is spaced apart in the axial direction from the upper surface of the ring magnet in a direction parallel to the axial direction,
wherein the core member includes a plurality of second recesses disposed on are formed in the core member and open to the upper surface of the core member, the second recesses and the first recesses being disposed to be misaligned in a radial direction,
wherein the plurality of first recesses are located along specific radial directions extending outward from the shaft, the plurality of second recesses are located along specific radial directions extending outward from the shaft, and the specific radial directions along which the second recesses are located differ from the specific radial directions along which the first recesses are located, and
wherein a shortest distance between the shaft and one each of the second recesses in respective radial directions extending outward from the shaft is less than a shortest distance between the shaft and one each of the first recesses in the respective radial direction directions extending outward from the shaft, and
wherein a shortest distance in a radial direction between the shaft and an outer end circumferential edge of the upper surface of the core member is greater than the shortest distance in a radial direction between the shaft and the one each of the first recesses on the upper surface of the ring magnet in the respective radial directions extending outward from the shaft, and
wherein all of the plurality of second recesses are disposed on a same circumference about the shaft, and an outer boundary of each of the second recesses is substantially cylindrical,
wherein all of the plurality of second recesses disposed on the same circumference are misaligned with respect to the ring magnet in any direction parallel to the axial direction such that no overlap exists, in any direction parallel to the axial direction, between any of the second recesses and the ring magnet.
15. A motor comprising:
a rotor; and
a stator,
wherein the rotor comprises;:
a shaft that extends in an axial direction from a lower end to an upper end;
a ring magnet including a first hole into which the shaft is inserted, the ring magnet having an upper surface; and
a core member disposed between the shaft and the ring magnetand including a resin material, and a part of the core member is on the upper surface of the ring magnet,
wherein the ring magnet includes a plurality of first recesses disposed on an are formed in the ring magnet and open to the upper surface of the ring magnet,
wherein an upper surface of the core member is disposed on the upper surface of the ring magnet such that the upper surface of the core member is spaced apart in the axial direction from the upper surface of the ring magnet in a direction parallel to the axial direction,
wherein the core member includes a plurality of second recesses disposed on are formed in the core member and open to the upper surface of the core member, the second recesses and the first recesses being disposed to be misaligned in a radial direction,
wherein the plurality of first recesses are located along specific radial directions extending outward from the shaft, the plurality of second recesses are located along specific radial directions extending outward from the shaft, and the specific radial directions along which the second recesses are located differ from the specific radial directions along which the first recesses are located, and
wherein a shortest distance between the shaft and one each of the second recesses in respective radial directions extending outward from the shaft is less than a radially shortest distance between the shaft and one each of the first recesses in the respective radial direction directions extending outward from the shaft, and
wherein a shortest distance in a radial direction between the shaft and an outer end circumferential edge of the upper surface of the core member is greater than the shortest distance in a radial direction between the shaft and the one each of the first recesses on the upper surface of the ring magnet in the respective radial directions extending outward from the shaft, and
wherein all of the plurality of second recesses are disposed on a same circumference about the shaft, and an outer boundary of each of the second recesses is substantially cylindrical, and
wherein all of the plurality of second recesses disposed on the same circumference are misaligned with respect to the ring magnet in any direction parallel to the axial direction such that no overlap exists, in any direction parallel to the axial direction, between any of the second recesses and the ring magnet.
2. The rotor of
the core member includes a plurality of third recesses disposed on are formed in the core member and open to the upper surface of the core member, and
wherein a shortest distance between the shaft and one of the third recesses is less than the shortest distance between the shaft and the one of the first recesses in the radial direction; and
wherein the third recesses at least partially overlap with the first recesses in an axial direction.
3. The rotor of
4. The rotor of
5. The rotor of
the plurality of second recesses are disposed on a same circumference about the shaft; and
the plurality of third recesses are disposed on a same circumference about the shaft.
0. 6. The rotor of
7. The rotor of
8. The rotor of
9. The rotor of
0. 11. The rotor of
0. 12. The rotor of
13. The rotor of
14. The rotor of
16. The motor of
the core member includes a plurality of third recesses disposed on are formed in the core member and open to the upper surface of the core member, and
wherein a shortest distance between the shaft and one of the third recesses is less than the radially shortest distance between the shaft and the one of the first recesses in the radial direction; and
wherein the third recesses at least partially overlap with the first recesses in an axial direction.
17. The motor of
18. The motor of
19. The motor of
20. The motor of
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Herein, D1 is the diameter of the first imaginary circle, D2 is the diameter of the second imaginary circle, D3 is the diameter of the extension portion, and D4 is the diameter of the ring magnet.
An axial length of the core member may be greater than a length of the ring magnet.
The extension portion may include a plurality of third grooves formed on one surface thereof.
The number of the third grooves may be the same as the number of the first grooves.
Third imaginary straight lines respectively passing from the center of the first imaginary circle through the third grooves may overlap with the first imaginary straight lines.
The third imaginary straight lines respectively passing from the center of the first imaginary circle through the third grooves may respectively have a predetermined angle with the first imaginary straight lines.
The second grooves are respectively disposed not to be on the third imaginary straight lines respectively passing from the center of the first imaginary circle through the third grooves.
An angle between each of the third imaginary straight lines respectively passing from the center of the first imaginary circle through the third grooves and each of the first straight lines may be less than an angle between each of second imaginary straight lines respectively passing from the center of the first imaginary circle through the second grooves and each of the first imaginary straight lines.
The angle between each of the third imaginary straight lines and each of the first imaginary straight lines is less than or equal to 10°.
The extension portion may include a first extension portion extending toward the one surface of the ring magnet and a second extension portion extending toward the other surface of the ring magnet, and the first extension portion and the second extension portion may be formed in a disk shape and have practically the same diameter.
The second grooves may have protrusion portions protruding from a bottom surface thereof.
Ends of the protrusion portions may be formed to be lower than a flat surface of the extension portion.
Another aspect of the present invention provides a motor including a stator part and a rotor assembly disposed to be rotatable with the stator part. The rotor assembly may include a ring magnet including an insertion hole in which a shaft is disposed, and a core member disposed between the shaft and the insertion hole and extending toward one surface and the other surface of the ring magnet. An extension portion may include a plurality of second and third grooves. The extension portion may include a plurality of second grooves which are not on a plurality of third imaginary straight lines respectively passing from a center of the insertion hole through the plurality of third grooves.
A rotor assembly according to an exemplary embodiment of the present invention reduces generation of a crack by minimizing a pressure applied to a ring magnet when the rotor assembly is manufactured.
Also, the rotor assembly can use an injected resin instead of a metal core to reduce a weight of the rotor and mitigate an impact caused by vibration.
The rotor assembly, a motor and a dual-clutch transmission (DCT) including the same reduce an exposed area of the ring magnet and reduce generation of a crack.
The rotor assembly increases performance of the motor by preventing a cracked material from being discharged to the outside even when a crack is generated on the ring magnet.
The various effects and advantages of the present invention are not limited to the above description and may be more easily understood through a process of describing a detailed description of the exemplary embodiment of the present invention.
The second grooves recesses 224 may be disposed not to be on the first imaginary straight line L1 passing through the center of the first imaginary circle C1 and two of the plurality of first grooves 215. When the second grooves recesses 224 are disposed on the first imaginary straight line L1, an injection pressure is directly applied to the the first grooves 215 when the core member 220 is injection-molded, and thus there is a problem in which excessive stress is concentrated on the first grooves 215.
Also, a temperature of the injected resin is greater than or equal to about 300° C. so that a momentary temperature difference is generated and a thermal impact may cause cracks around the first grooves 215.
Therefore, the second grooves recesses 224 are disposed not to be on the first imaginary straight lines L1, and thus a stress applied to the first grooves 215 may be relatively mitigated when the rotor is manufactured.
Each of the first grooves 215 and/or the third grooves recesses 225 may be disposed between a plurality of second grooves recesses 224a, 224b and 224c, and the first grooves 215 and the second grooves recesses 224 may be disposed at an angle of about 25° to 55°. In this case, an angle θ11 between the second groove recess 224b and one of the third groove recesses 225 may be the same as or different from an angle θ12 between the second groove recess 224c and one of the third groove recesses 225.
Referring to
Therefore, the first imaginary straight line L1 and each of a third imaginary straight line L3 passing through the center of the first imaginary circle C1 and the third grooves recesses 225 are disposed not to correspond to each other so that a predetermined angle θ3 exists between them. For example, the third imaginary straight line L3 and the first imaginary straight line L1 may have an angle of less than or equal to 10°.
In this case, the second grooves recesses 224 may be disposed at positions which also do not correspond to the third imaginary straight lines L3. That is, the angle θ3 between the third imaginary straight line L3 and the first imaginary straight line L1 may be less than an angle θ2 between the second imaginary straight line L2 and the first imaginary straight line L1. That is, the third grooves recesses 225 may be disposed closer to the first grooves 215 than the second grooves recesses 224.
The third grooves recesses 225 may mark the magnetization direction of the ring magnet, and thus it is advantageous to dispose the third grooves recesses 225 close to the first grooves 215. The second grooves recesses 224 are disposed as far away from the first grooves 215 as possible to mitigate stress applied to the first grooves 215.
In
Referring to
Referring to
A method of forming a coating layer includes sanding and preheating a surface of the ring magnet 210, coating the sanded surface, post-heating the coating layer, and manufacturing the coating layer. However, the coating method is only an exemplary example and is not limited thereto. Various coating methods may be applied depending on kinds of coating materials.
A Teflon coating layer may be formed at a thickness of 10 to 30 μm. However, the coating material is not necessarily limited thereto, and various coating materials that prevent a crack generated in the ring magnet 210 or corrosion of the magnet may be selected.
The vertical axis in
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