Patent ID: 12244182

MODES OF THE INVENTION

A direction parallel to a longitudinal direction (vertical direction) of a shaft is an axial direction, a direction perpendicular to the axial direction about the shaft is a radial direction, and a direction along a circumference of a circle having a radius in the radial direction about the shaft is a circumferential direction.

FIG.1is a view illustrating a motor according to an embodiment.

Referring toFIG.1, the motor according to the embodiment may include a shaft100, a rotor200, a stator300, a guide400, and a housing500. Hereinafter, the term “inward” refers to a direction from the housing500toward the shaft100, and the term “outward” refers to a direction from the shaft100toward the housing500, which is a direction opposite to “inward.”

The shaft100may be coupled to the rotor200. When an electromagnetic interaction occurs between the rotor200and the stator300due to the supply of a current, the rotor200rotates, and the shaft100rotates in conjunction with the rotor200. The shaft100may be connected to a vehicle's steering shaft and may transmit power to the vehicle's steering shaft.

The rotor200rotates through an electrical interaction with the stator300. The rotor200may be disposed inside the stator300.

The stator300is disposed outside the rotor200. The stator300may include a stator core300A, coils300B, and an insulator300C installed on the stator core300A. The coils300B may be wound around the insulator300C. The insulator300C is disposed between the coils300B and the stator core300A to electrically insulate the stator core300A from the coils300B. The coils300B induce an electrical interaction with magnets220(seeFIG.2) of the rotor200.

The housing500may be disposed outside the rotor200and the stator300.

FIG.2is an exploded view illustrating a rotor.

Referring toFIG.2, the rotor200may include a rotor core210, the magnets220, and the guide400. The magnets220are disposed outside the rotor core210. The guide400may be formed of a plastic resin. The magnets220may be a plurality of combined unit magnets.

The rotor core210may include a first rotor core210A and a second rotor core210B. The first rotor core210A and the second rotor core210B are arranged in an axial direction. The first rotor core210A and the second rotor core210B may be disposed to form a skew angle. The magnets220may be divided into first magnets220A and second magnets220B. The first magnets220A are disposed on an outer surface of the first rotor core210A. The second magnets220B are disposed on an outer surface of the second rotor core210B.

The guide400may be disposed between the first rotor core210A and the second rotor core210B in the axial direction. The guide400is a member for fixing the magnets220to the rotor core210and a member which assists with coupling of the first rotor core210A and the second rotor core210B.

FIG.3is a perspective view illustrating the rotor200, andFIG.4is a perspective view illustrating the first rotor core210A.

Referring toFIGS.3and4, the first rotor core210A and the second rotor core210B are stacked with the guide400interposed therebetween in the axial direction. The first rotor core210A and the second rotor core210B are disposed to be misaligned with each other by a predetermined skew angle. Accordingly, the first magnets220A and the second magnets220are also disposed to be misaligned with each other by a predetermined skew angle. The rotor core210may include a plurality of protrusions211A and211B. The protrusions211A and211B are in contact with side surfaces of the magnets220. Hereinafter, among the protrusions211A and211B, the protrusions211A or211B disposed on the first rotor core210A are referred to as first protrusions211A, and the protrusions211A or211B disposed on the second rotor core210B are referred to as second protrusions211B.

The first rotor core210A may include the plurality of first protrusions211A. The first protrusions211A are for guiding and fixing the first magnets220A to the first rotor core210A. The first protrusions211A protrude from the outer surface of the first rotor core210A. In addition, the first protrusions211A may be disposed to extend in the axial direction. The plurality of first protrusions211A may be disposed at predetermined intervals in a circumferential direction of the first rotor core210A. The first magnets220A are disposed between the first protrusions211A are adjacent to each other.

A length L1of the first protrusion211A in the axial direction is shorter than a length L2of the first rotor core210A in the axial direction. When one side end of the first protrusion211A matches one side end of the first rotor core210A, as inFIG.4, a space S1without having the first protrusion211A is provided. The space S1is a space S1though which second members420and430of the guide400enter.

A plurality of first holes212A are disposed in the first rotor core210A. The first holes212A are disposed to pass through from one side surface to the other side surface of the first rotor core210A. The first holes212A are holes into which third protrusions440of the guide400are inserted.

FIG.5is a perspective view illustrating the second rotor core210B.

Referring toFIGS.3and5, the second rotor core210B may include the plurality of second protrusions211B. The second protrusions211B are for guiding and fixing the second magnets220B to the second rotor core210B. The second protrusions211B protrude from an outer surface of the second rotor core210B. In addition, the second protrusions211B may be disposed to extend in the axial direction. The plurality of second protrusions211B may be provided at predetermined intervals in the circumferential direction of the second rotor core210B. The second magnets220B are disposed between the second protrusions211B which are adjacent to each other.

A length L3of the second protrusion211B in the axial direction is smaller than a length L4of the second rotor core210B in the axial direction. When one side end of the second protrusion211B matches one side end of the second rotor core210B, as inFIG.5, a space S2without having the second protrusions211B are formed. The space S2is a space S2through which the second members420and430of the guide400enter.

A plurality of second holes212B are disposed in the second rotor core210B. The second holes212B are disposed to pass through from one side surface to the other side surface of the second rotor core210B. The second holes212B are holes into which fourth protrusions450of the guide400are inserted.

FIG.6is a perspective view illustrating the guide400from above.

FIG.7is a perspective view illustrating the guide400from below.

Referring toFIGS.6and7, the guide400may include a first member410and the second members420and430.

The first member410is disposed between the first rotor core210A and the second rotor core210B in the axial direction and is in contact with one side surface of the first rotor core210A and the other side surface of the second rotor core210B. The first member410may be a flat plate member having an annular shape having a hole through which the shaft passes and which is formed in a central portion of the flat plate member. The first member410may include the third protrusions440and the fourth protrusions450. The third protrusions440protrude from one side surface of the first member410in the axial direction. In addition, the fourth protrusions450protrude from the other side surface of the first member410in the axial direction. The third protrusions440are inserted into the first holes212A of the first rotor core210A, and the fourth protrusions450are inserted into the second holes212B of the second rotor core210B. The plurality of third protrusions440and the plurality of fourth protrusions450may be disposed. The third protrusions440and the fourth protrusions450may have cylindrical shapes.

The second members420and430are members extending from the first member410in the axial direction and are in contact with the side surface of the magnets220. The plurality of second members420and430are disposed. The plurality of second members420and430may be disposed at predetermined intervals along an edge of the first member410. The magnets220are positioned between the second members420and430which are adjacent to each other.

The second members420and430may be divided into2-1members420and2-2members430. The2-1members420extend from one side surface of the first member410in the axial direction. The2-2members430extend from the other side surface of the first member410in the axial direction. Accordingly, the2-1members420may be disposed at one side of the first member410, and the2-2members430may be disposed at the other side of the first member410in the axial direction.

In order to form a skew angle, one side end portions and the other side end portions of the second members420and430are disposed to be different from each other in the circumferential direction of the guide400. The one side end portions of the second members420and430may correspond to one side end portions421of the2-1members420, and the other side end portions of the second members420and430may correspond to one side end portions431of the2-2members430. The2-1members420and the2-2members430are members connected to each other in the axial direction but are disposed to be misaligned with each other in the circumferential direction of the guide400.

Since the2-1members420and the2-2members430are disposed to be misaligned with each other in the circumferential direction of the guide400, stepped surfaces T1and T2are formed on two side surfaces of the second members420and430. For example, in the second members420and430, the first stepped surfaces T1may be provided to be coplanar with one side surface of the first member410like first stepped surfaces T1inFIG.6, and the second stepped surfaces T2may be provided to be coplanar with the other side surface of the first member410like second stepped surfaces T2inFIG.7. The first stepped surfaces T1are surfaces in contact with one side surface of the first magnet220A, and the second stepped surfaces T2are surfaces in contact with one side surface of the second magnet220B. The first stepped surfaces T1and the second stepped surfaces T2serve to support the magnets220in the axial direction.

FIG.8is a view illustrating the skew angle with respect to the second members420and430from one side, andFIG.9is a view illustrating the skew angle with respect to the second members420and439from the other side.

Referring toFIGS.8and9, the2-1member420and the2-2member430are disposed to be misaligned with each other in the circumferential direction of the guide400. Accordingly, about a center of the guide400, an angle R1formed by a center P1of one side end portion421of the2-1member420and a center P2of one side end portion431of the2-2member430corresponds to the skew angle of the motor. Accordingly, the magnet220installed along the2-1member420and the2-2member430may be precisely guided to a position at which the corresponding angle is formed.

FIG.10is a view illustrating the skew angle with respect to the third protrusion and the fourth protrusion.

Referring toFIG.10, the third protrusion440and the fourth protrusion450are disposed to be misaligned with each other in the circumferential direction of the guide400. Accordingly, an angle R2formed between a center of the third protrusion440and a center of the fourth protrusion450about the center of the guide400corresponds to the skew angle of the motor. In a process in which the guide400is installed in the rotor core210, since the third protrusion440is inserted into the first hole212A of the first rotor core210A, and the fourth protrusion450is inserted into the second hole212B of the second rotor core210B, a position of the2-1member420and a position of the2-2member430may be precisely arranged in the circumferential direction of the guide400. When the position of the2-1member420and the position of the2-2member430are precisely set, the magnet220installed along the2-1member420and the2-2member430may be precisely guided at a position at which the corresponding skew angle is formed.

FIG.11is a view illustrating a process in which the guide400is installed in the rotor core, andFIG.12is a view illustrating a process in which the magnets220are fixed to the rotor core210using the guide400.

Referring toFIGS.11and12, the first rotor core210A may be installed on the guide400from one side of the guide400, and the second rotor core210B may be installed on the guide400from the other side of the guide400in the axial direction so that the guide400is disposed therebetween. In a state in which the2-1members420and the first protrusions211A are aligned with each other in the circumferential direction of the guide400, the first rotor core210A is installed on the guide400. In addition, the2-2members430and the second protrusions211B are aligned with each other in the circumferential direction of the guide400, the second rotor core210B is installed on the guide400.

In this case, the2-1members420and the first protrusions211A face each other, become closer to each other, and finally come in contact with each other. In addition, the2-2members430and the second protrusions211B also face each other, become closer to each other, and finally come in contact with each other.

Then, the magnets220are inserted between the second members420and430in the axial direction.

FIG.13is a side cross-sectional view illustrating the rotor200along line A-A ofFIG.3, andFIG.14is a side cross-sectional view illustrating the rotor200along line B-B ofFIG.3.

Referring toFIG.13, when the magnets220are assembled to the rotor core210using the guide400, one side surfaces211Aa of the first protrusions211A are in contact with one side end portions421of the2-1members420. In this case, one side ends of the second magnets220B are in contact with the second stepped surfaces T2of the second members420and430. The second magnets220B are supported by the second stepped surfaces T2in the axial direction.

Referring toFIG.14, when the magnets220are assembled to the rotor core210using the guide400, one side surfaces211Ba of the second protrusions211B are in contact with one side end portions431of the2-2members430. In this case, one side ends of the first magnets220A are in contact with the first stepped surfaces T1of the second members420and430. The first magnets220A are supported by the first stepped surfaces T1in the axial direction.

FIG.15is a view illustrating the first magnets220A supported by the first protrusions211A, andFIG.16is a view illustrating the magnets220further supported by the second members420and430.

Referring toFIG.15, the first protrusions211A are in contact with side surfaces of the first magnets220A to guide assembly of the first magnets220A and support the first magnets220A so that the first magnets220A do not move in the circumferential direction of the rotor200. In addition, the first protrusions211A are formed so that widths of inner sides are greater than widths of outer sides, and fix the first magnets220A so that the first magnets220A are not separated in the radial direction of the rotor200. Although not illustrated in the drawings, the second protrusions211B also similarly support the second magnets220B.

Referring toFIG.16, the2-1members420may include bodies422and extension portions423extending from the bodies422. The bodies422are disposed between the adjacent first magnets220A and are in contact with side surfaces of the first magnets220A. The bodies422are in contact with the side surfaces of the first magnets220A to guide assembly of the first magnets220A and support the first magnets220A so that the first magnets220A do not move in the circumferential direction of the rotor200.

The extension portions423are in contact with outer surfaces of the first magnets220A. The extension portions423are in contact with the outer surfaces of the first magnets220A to firmly fix the first magnets220A so that, along with the first protrusions211A, the first magnets220A are not separated in the radial direction of the rotor200. Although not illustrated in the drawings, similarly, the2-2members430also include such bodies and extension portions and support the second magnets220B

FIG.17is a cross-sectional view illustrating a motor according to another embodiment.

Referring toFIG.17, the motor according to the embodiment may include a housing1100having one side at which an opening is formed, a cover1200disposed on the housing1100, a stator1300disposed in the housing1100, a rotor1400disposed inside the stator1300, a shaft1500which is coupled to the rotor1400and rotates, a busbar1600disposed on the stator1300, and a sensor part1700configured to detect rotation of the shaft1500.

The housing1100and the cover1200may form an exterior of the motor. The housing1100and the cover1200are coupled to form an accommodation space. In this case, the stator1300, the rotor1400, the shaft1500, and the like may be disposed in the accommodation space. In this case, the shaft1500is rotatably disposed in the accommodation space. In addition, a motor1may further include bearings10disposed on upper and lower portions of the shaft1500.

A shape or material of the housing1100may be variously changed. For example, the housing1100may be formed of a metal material which firmly withstands even high temperatures.

The cover1200is disposed on the housing1100and covers the opening of the housing1100.

The stator1300may be disposed inside the housing1100. In this case, the stator1300may be coupled to the housing1100in a hot press-fit manner. In addition, the stator1300may be supported by an inner circumferential surface of the housing1100.

The stator1300is disposed outside the rotor1400. The stator1300may include a stator core1310, coils1320, and an insulator1330. The insulator1330is installed on the stator core1310. In this case, the coils1320are wound around the insulator1330. In this case, the insulator1330is disposed between the stator core1310and the coils1320to insulate the coils1320.

The coils1320which generate a rotational magnetic field may be wound around the stator core1310.

The stator core1310may be formed in a form in which a plurality of thin steel plates are stacked but is not limited thereto. For example, the stator core1310may also be formed as a single part. In addition, the stator core1310may be formed by arranging a plurality of unit stator cores in a circumferential direction. The rotor1400may be disposed inside the stator1300. In addition, the shaft1500may be coupled to a center portion of the rotor1400.

The shaft1500may be disposed in the housing1100to be rotatable due to the bearings10. In addition, the shaft1500may rotate with the rotor1400in conjunction with rotation of the rotor1400.

FIG.18is a view illustrating the rotor according to another embodiment.

Referring toFIG.18, the rotor1400may include a rotor core1410and magnets1420. The rotor core1410is rotationally disposed in a cylindrical space portion formed in a central portion of the stator1300.

The plurality of magnets1420may be disposed on an outer circumferential surface of the rotor core1410. In addition, facing surfaces of the rotor core1410and the magnets1420may be bonded. In this case, space portions1410G may be formed between the rotor core1410and the magnets1420. An adhesive may be disposed in the space portions1410G. In addition, one or more partitions1410W disposed in each of the space portions1410G may be included. In this case, the partitions1410W overlap the space portions1410G in an axial direction. That is, one or more partitions1410W may serve to support the adhesive disposed in each of the space portions1410G in the axial direction.

The plurality of partitions1410W may be provided. The partitions1410W may divide each of the space portions1410G into one or two sections. The divided sections may be disposed in the axial direction. The partition1410W may divide the space portion1410G into an upper portion and a lower portion. In this case, the adhesive may be applied on the upper portion and the lower portion of the space portion1410G. In addition, the partition1410W may be disposed in a lower end of the space portion1410G. In this case, at least a part of a lower side of the space portion1410G may be closed by the partition1410W.

Outer side ends of the partitions1410W may be in contact with the magnets1420. In this case, a width of a cross section of each of the partitions1410W cut in a direction perpendicular to the axial direction is equal to a width of a cross section of each of the space portions1410G cut in the direction perpendicular to the axial direction. Accordingly, the partition1410W may divide the space portion1410G into a plurality of closed sections. In addition, the lower side of the space portion1410G may be closed.

Outer side ends of the partitions1410W may also be spaced apart from the magnets1420. In this case, a width of a cross section of each of the partitions1410W cut in the direction perpendicular to the axial direction may be smaller than a width of a cross section of each of the space portions1410G cut in the direction perpendicular to the axial direction. Accordingly, the partitions1410W may divide each of the space portions1410G into the plurality of sections so that parts of the sections may be connected. In addition, only a part of a lower side of each of the space portion1410G may be closed.

Grooves extending in the axial direction may be formed in a surface of the rotor core1410in contact with the magnets1420. In this case, the grooves may form the space portions1410G between the rotor core1410and the magnets1420. In addition, the partitions1410W may extend on the rotor core1410.

The rotor core1410may include a plurality of first surfaces1410-1, a plurality of second surfaces1410-2, a plurality of third surfaces1410-3, and fourth surfaces1410-4on an outer circumferential surface thereof.

The plurality of first surfaces1410-1are provided. The plurality of first surfaces1410-1may be disposed between the plurality of magnets1420. The plurality of first surfaces1410-1are spaced apart from each other in the circumferential direction. The first surfaces1410-1are not in contact with the magnets1420.

The second surfaces1410-2may be disposed between the plurality of first surfaces1410-1. The plurality of second surfaces1410-2are provided. The plurality of second surfaces1410-2are spaced apart from each other. In this case, a distance from a center of the rotor to each of the first surfaces1410-1may be greater than a distance from the center of the rotor to each of the second surfaces1410-2. That is, the second surfaces1410-2are formed to be recessed closer to the shaft1500than the first surfaces1410-1. In this case, the second surfaces1410-2are in contact with inner side surfaces of the magnets1420.

The third surfaces1410-3connect the plurality of first surfaces1410-1and the plurality of second surfaces1410-2. In this case, the third surfaces1410-3are in contact with two side surfaces of each of the magnets1420.

The fourth surfaces1410-4are disposed between the plurality of second surfaces1410-2. In this case, a distance from the center of the rotor to each of the second surfaces1410-2may be greater than a distance from the center of the rotor to each of the fourth surfaces1410-4. That is, the fourth surfaces1410-4are formed to be recessed closer to the shaft1500than the second surfaces1410-2. In this case, the space portions1410G may be formed between the fourth surfaces1410-4and the magnets1420.

Although not illustrated in the drawings, grooves may be formed in inner side surfaces of the magnets. In this case, space portions may be formed by the grooves between the magnets and the rotor core. In addition, partitions may extend in the inner side surfaces of the magnets. In addition, although not illustrated in the drawings, a groove may also be formed in one selected from each of the magnets and the rotor core. In this case, a space portion may be formed by the groove between each of the magnets and the rotor core. In addition, a partition may also extend from the other of each of the magnets and the rotor core.

FIGS.19and20are views illustrating a rotor according to still another embodiment, andFIG.21is a view illustrating a state in which an adhesive is applied on a cross section CC′ ofFIG.19.

Referring toFIGS.19and20, a rotor core1410A may be formed by stacking a plurality of core plates. The plurality of core plates are stacked in an axial direction. A plurality of magnets1420are disposed on an outer circumferential surface of the rotor core1410A. In this case, a plurality of magnet grooves allowing the plurality of magnets1420to be disposed may be formed in the rotor core1410A. The plurality of magnets grooves may be disposed apart from each other in a circumferential direction. In this case, depths of the magnet grooves may be smaller than thicknesses of the magnets1420.

The rotor core1410A may be formed using two or more types of core plates. The rotor core1410A may include a plurality of first plates1411and one or more second plates1412.

Grooves are formed in surfaces of the first plates1411in contact with the magnets1420. In addition, grooves are not formed in surfaces of the second plates1412in contact with the magnets1420. Referring toFIG.21, an adhesive G is disposed in the grooves of the first plates1411. In this case, outer side ends of the second plates1412block the grooves of the first plates1411in the axial direction. Accordingly, the adhesive G disposed in the grooves of the first plates1411may be inhibited from flowing down by the outer side ends of the second plates1412.

FIG.22is a set of plan views illustrating the first plate and the second plate.

Each of the first plates1411may include a plurality of1-1surfaces1411-1, a plurality of1-2surfaces1411-2,1-3surfaces1411-3, and1-4surfaces1411-4on an outer circumferential surface thereof.

The plurality of1-1surfaces1411-1are provided. The plurality of1-1surfaces1411-1may be disposed between the plurality of magnets1420. The plurality of1-1surfaces1411-1are spaced apart from each other in the circumferential direction. The1-1surfaces1411-1are not in contact with the magnets1420.

The1-2surfaces1411-2may be disposed between the plurality of1-1surfaces1411-1. The plurality of1-2surfaces1411-2may be provided. The plurality of1-2surfaces1411-2are spaced apart from each other. In this case, a distance from a center of a rotor to each of the1-1surfaces1411-1may be greater than a distance from the center of the rotor to each of the1-2surfaces1411-2. That is, the1-2surfaces1411-2are formed to be recessed closer to a shaft1500than the1-1surfaces1411-1. The1-2surfaces1411-2are in contact with inner side surfaces of the magnets1420. In this case, first grooves1411G may be formed in the1-2surfaces1411-2.

The1-3surfaces1411-3connect the plurality of1-1surfaces1411-1and the plurality of1-2surfaces1411-2. In this case, the1-3surfaces1411-3are in contact with two side surfaces of each of the magnets1420.

The1-4surfaces1411-4are disposed between the plurality of1-2surfaces1411-2. In this case, a distance from the center of the rotor to each of the1-2surfaces1411-2may be greater than the center of the rotor each of the1-4surfaces1411-4. That is, the1-4surfaces1411-4are formed to be recessed closer to the shaft1500than the1-2surfaces1411-2. In this case, the first grooves1411G may be formed between the1-4surfaces1411-4and the magnets1420. The first grooves1411G of the first plates1411are connected in the axial direction. Accordingly, when the plurality of first plates1411are stacked, a groove extending in the axial direction may be formed. In addition, the adhesive G is disposed in the first grooves1411G.

Each of the second plates1412may include a plurality of2-1surfaces1412-1,2-2surfaces1412-2, a plurality of2-3surfaces1412-3on an outer circumferential surface thereof.

The plurality of2-1surfaces1412-1are provided. The plurality of2-1surfaces1412-1may be disposed between the plurality of magnets1420. The plurality of2-1surfaces1412-1are spaced apart from each other in the circumferential direction. The2-1surfaces1412-1are not in contact with the magnets1420.

The2-2surfaces1412-2may be disposed between the plurality of2-1surfaces1412-1. One2-2surface1412-2is disposed between the spaced2-1surfaces1412-1. In this case, a distance from the center of the rotor to each of the2-1surfaces1412-1may be greater than a distance from the center of the rotor to each of the2-2surfaces1412-2. That is, the2-2surfaces1412-2are formed to be recessed closer to the shaft1500than the2-1surfaces1412-1. The2-2surfaces1412-2may be in contact with the inner side surfaces of the magnets1420. In this case, grooves are not formed in the2-2surfaces1412-2. In this case, parts of the2-2surfaces1412-2may overlap the first grooves1411G in the axial direction.

The2-3surfaces1412-3connect the plurality of2-1surfaces1412-1and the plurality of2-2surfaces1412-2. In this case, the2-3surfaces1412-3are in contact with two side surfaces of each of the magnets1420.

Two second plates1412may be provided. As inFIGS.19and20, one second plate1412may be stacked between the plurality of first plates1411, and the other second plate1412may be disposed at a lower side of the plurality of first plates1411. In this case, one second plate1412may support the adhesive flowing from the upper first grooves1411H, the other second plate1412may support the adhesive flowing downward from the lower first grooves1411G, and thus the downward flow of the adhesive can be more effectively inhibited.

A shape of the rotor core1410may be changed according to the number and a stack order of the first plates1411and the second plates1412.

FIG.23is a set of views illustrating variously modified examples in which the numbers and stack orders of the first and second plates are changed.

Referring toFIG.23A, one second plate1412may be provided. In addition, a plurality of first plates1411may be sequentially stacked. In this case, one second plate1412may be disposed at a lower side of the plurality of first plates1411. In this case, the second plate1412disposed at a lowermost end portion of a rotor core may block an adhesive flowing from first grooves of the first plates1411.

Referring toFIG.23B, three or more second plates1412may be provided. In this case, three or more second plates1412may be stacked between first plates1411. In this case, the second plates1412disposed between the first plates1411are disposed apart from each other in an axial direction. In addition, one second plate1412may be stacked at a lower side of the plurality of first plates1411.

As the number of the second plates1412increases, an effect of inhibiting adhesive from flowing down may be improved. However, as the number of the second plates1412increases, first grooves1411G are shielded, a magnetic effect decreases, and thus magnetic characteristics of a rotor1400may be degraded. Accordingly, four or fewer second plates1412may be provided. In addition, the sum of thicknesses of one or more second plates1412in the axial direction may be less than 0.3 times a length of the rotor core in the axial direction. For example, the sum of the thicknesses of the one or more second plates1412in the axial direction may be less than 0.2 times the length of the rotor core in the axial direction.

The thickness of the second plate1412in the axial direction may be changed according to the number of the second plates1412. Table 1 is a table showing a maximum thickness of each of the second plates according to the number of the second plates.

TABLE 1Height of rotor coreNumber of second platesin axial direction12420 mmLess than 4 mmLess than 2 mmLess than 1 mm30 mmLess than 6 mmLess than 3 mmLess than 1.3 mm

As in Table 1, when the number of the second plates increases, the thickness of each of the second plates in the axial direction also decreases. In this case, when a ratio of the sum T of the thicknesses of the second plates in the axial direction to the length of the rotor core in the axial direction is greater than 0.2, magnetic characteristics of the rotor are degraded.

According to another embodiment of the present invention, in order to improve the magnetic characteristics of the rotor core, the rotor core may be formed so that grooves may be formed not to be completely blocked in the axial direction.

FIG.24is a view illustrating a rotor according to yet another embodiment,FIG.25is a view illustrating a state in which an adhesive is applied on a cross section DD′ ofFIG.24, andFIG.26is a set of plan views illustrating a first plate and a third plate. In this case, since members of which reference numerals are identical to those ofFIGS.17to23are the same members having the same shapes and functions, repeated description thereof will be omitted.

Referring toFIGS.24and25, a rotor core1410B may include a plurality of first plates1411and one or more third plates1413. In this case, the plurality of first plates1411and one or more third plates1413may be stacked in an axial direction.

Referring toFIG.26, first grooves1411G may be formed in surfaces of the first plates1411in contact with magnets1420, and second grooves1413G may be formed in surfaces of the third plates1413in contact with the magnets1420. Widths of the second grooves1413G may be smaller than widths of the first grooves1411G in a radial direction. In this case, the plurality of first plates1411and the third plates1413may be stacked in the axial direction so that the plurality of first grooves1411G and one or more second grooves1413G may be disposed collinear with each other in the axial direction. In this case, the plurality of first grooves1411G may extend in the axial direction. In addition, the second grooves1413G may be disposed between the extending plurality of first grooves1411G. Alternatively, the second groove1413G may be disposed at a lower side of the plurality of first grooves1411B.

Each of the third plates1413may include a plurality of3-1surfaces1413-1, a plurality of3-2surfaces1413-2, a plurality of3-3surfaces1413-3, and3-4surfaces1413-4.

The plurality of3-1surfaces1413-1are provided. The plurality of3-1surfaces1413-1may be disposed between the plurality of magnets1420. The plurality of3-1surfaces1413-1are spaced apart from each other in a circumferential direction. The3-1surfaces1413-1are not in contact with the magnets1420.

The3-2surfaces1413-2may be disposed between the plurality of3-1surfaces1413-1. The plurality of3-2surfaces1413-2are provided. The plurality of3-2surfaces1413-2are spaced apart from each other. In this case, a distance from a center of the rotor to each of the3-1surface1413-1may be greater than a distance from the center of the rotor to each of the3-2surfaces1413-2. That is, the3-2surfaces1413-2are formed to be recessed closer to a shaft1500than the3-1surfaces1413-1. The3-2surfaces1413-2are in contact with inner side surfaces of the magnets1420. In this case, second grooves1413G may be formed in the3-2surfaces1413-2.

The3-3surfaces1413-3connect the plurality of3-1surfaces1413-1and the plurality of3-2surfaces1413-2. In this case, the3-3surfaces1413-3are in contact with two side surfaces of each of the magnets1420.

The3-4surfaces1413-4are disposed between the plurality of3-2surfaces1413-2. In this case, a distance from the center of the rotor to each of the3-2surfaces1413-2may be greater than a distance from the center of the rotor to each of the3-4surfaces1413-4. That is, the3-4surfaces1413-4are formed to be recessed closer to the shaft1500than the3-2surfaces1413-2. In this case, the second grooves1413G may be formed between the3-4surfaces1413-4and the magnets1420. The first grooves1411G of the first plates1411are connected in the axial direction. Accordingly, when the plurality of first plates1411are stacked, a groove extending in the axial direction may be formed. An adhesive G is not applied on the second grooves1413G. However, a part of the adhesive G may also be disposed in the second grooves1413G while the adhesive in the first grooves1411G flows down.

According to yet another embodiment of the present invention, in a rotor core, all of the first plates, second plates, and third plates are applied. In this case, an entire lower end portion of a groove extending in an axial direction of the rotor core may be blocked, and only a part of an upper side portion thereof may be blocked.

FIG.27is a view illustrating a rotor according to yet another embodiment. In this case, since members of which reference numerals are identical to those ofFIGS.17to26are the same members having the same shapes and functions, repeated description thereof will be omitted.

Referring toFIG.27, a rotor core may be formed by stacking a plurality of first plates1411, one or more second plates1412, and one or more third plates1413.

In this case, the third plates1412may be stacked between the plurality of first plates1411. In addition, the second plates1412may be disposed under the stacked first plates1411and the third plates1413. In this case, a part of an adhesive disposed in first grooves is blocked while the adhesive passes through second grooves, and the adhesive may be completely blocked by the second plates1412.

An example of an inner rotor type motor has been described in the above-described embodiments but the present invention is not limited thereto. The present invention may also be applied to an outer rotor type motor. In addition, the present invention may be applied to various devices for vehicles or home appliances.