MOTOR

Description

[Technical Field]

[0001] Embodiments relate to a motor.[Background Art]

[0002] As a motor of a vehicle evolves to have a specification such as a higher torque and a higher speed, a robust design has been required for a rotor structure applied to the motor.

[0003] A rotor used in a general motor has a structure in that a stacked rotor core, which is formed by stacking a plurality of disc-shaped rotor core members, is provided and a magnet is attached to an outer side surface of the rotor core.

[0004] The motor using such a permanent magnet exhibits a cogging torque. The cogging torque refers to a non-uniform torque of a stator inevitably occurring in a motor using the permanent magnet and means a torque in a radial direction intended to move to a position where magnetic energy of the motor is at a minimum, that is, to an equilibrium state.

[0005] The cogging torque is caused by a sudden change in magnetic flux near a boundary between an N pole and an S pole of the magnet. It is important to reduce the cogging torque because the cogging torque causes noise and vibration and deteriorates performance of the motor. Particularly, it is more important to reduce the cogging torque in a motor used in an actuator for precise position control.

[0006] However, when a skew angle is applied in a state where each puck is attached to a rotor to which a plurality of magnets are attached, or three-stage magnets are simultaneously magnetized, neighboring pucks exert influences on each other during the magnetization, and the cogging torque and a back electromotive force harmonic wave are deteriorated due to influences from vertically opposite polarities even after the magnetization.

[0007] In addition, a plurality of magnets are installed in the rotor. According to an installation type of the magnets, the rotor is classified into an inner permanent magnet (IPM) rotor in which the magnets are inserted into and coupled to the inside of a rotor core and a surface permanent magnet (SPM) rotor in which the magnets are attached to a surface of the rotor core.

[0008] In the case of an IPM motor, a coupling hole is provided in the rotor core, and the magnet is inserted into the coupling hole. An adhesive is used to fix the magnet to the coupling hole. When the adhesive is applied to the coupling hole, a process of injecting and curing the adhesive between the magnet and the coupling hole is complicated and a process time increases. In addition, there is a problem that the process time increases because an additional process is required to confirm whether the adhesive is cured.

[0009] JP 2013-99038 A discloses a brushless motor whose rotor is designed with a view of enabling easy positioning of magnets while forming a flux barrier and a motor using the rotor for an electric motor. US2015 / 0357892A1 discloses a motor with a rotor with a plurality of rotor core members and a plurality of magnets mounted on the outer rotor surface in a skewed manner.[Technical Problem]

[0010] An embodiment is directed to providing a motor having magnets attached to a rotor core and spaced apart from each other.

[0011] In addition, an embodiment not part of the claimed invention is directed to providing a motor in which the magnet is fixed to a coupling hole of the rotor core without an adhesive.

[0012] The problems to be solved by the present invention are not limited to the above-mentioned problems and those skilled in the art may apparently understand other problems not mentioned herein based on the following descriptions.[Technical Solution]

[0013] The invention is a motor as defined in the independent claim 1. Further embodiments of the invention are defined in dependent claims 2-5.

[0014] In the present description and drawings, any examples and technical descriptions of apparatuses, products and / or methods which are not covered by the claims should be taken as background art or examples useful for understanding the invention.[Advantageous Effects]

[0015] According to an embodiment, magnets are spaced apart from each other so that the cogging torque and back electromotive force harmonic wave can be improved.

[0016] According to other embodiments not part of the claimed invention the magnets are fixed to a rotor core without an adhesive so that a manufacturing process can be simplified and a manufacturing time can be reduced.

[0017] The coupling between the magnet and the rotor core can be improved.

[0018] A bearing is supported through a second holder so that the structure can be simplified.

[0019] The various and useful advantages and effects of the present invention are not limited to the above descriptions and may be more easily understood in the course of describing specific embodiments of the present invention.[Description of Drawings]

[0020] FIG. 1 is a view showing a basic structure of a motor according to an embodiment of the present invention. FIG. 2 is a view showing a first embodiment of a rotor. FIG. 3 is a view showing a second embodiment of the rotor. FIG. 4 is a view showing a third embodiment of the rotor. FIG. 5 is a view showing a shape of a spacer which is an element of FIG. 4. FIG. 6 is an enlarged view of an internal structure of FIG. 1. FIG. 7 is a view showing a change amount of a cogging torque according to the gap ratio of a magnet. FIGS.8 to 20 are views showing embodiments which are not part of the claimed invention. FIG. 8 is a view illustrating a motor according to still another embodiment. FIG. 9 is a view illustrating a rotor viewed from above according to still another embodiment. FIG. 10 is a view illustrating a rotor according to still another embodiment. FIGS. 11 and 12 are exploded perspective views of the rotor shown in FIG. 10. FIG. 13 is a perspective view illustrating a first holder viewed from above according to still another embodiment of FIG. 8. FIG. 14 is a perspective view illustrating a second holder viewed from below according to still another embodiment of FIG. 8. FIG. 15 is a plan view illustrating the first holder according to still another embodiment of FIG. 8. FIG. 16 is a view illustrating a first protrusion inserted into a coupling hole of a rotor core according to still another embodiment of FIG. 8. FIG. 17 is a view illustrating a shape of the first protrusion according to still another embodiment of FIG. 8. FIG. 18 is a perspective view illustrating the second holder viewed from above according to still another embodiment of FIG. 8. FIG. 19 is a perspective view illustrating the second holder viewed from below according to still another embodiment of FIG. 8. FIG. 20 is a plan view illustrating the second holder according to still another embodiment of FIG. 8. [Modes of the Invention]

[0021] The present invention is illustrated in the example of Fig. 6 and the related description. While the other embodiments discussed below are not all specifically claimed, the related description is useful as background information and to provide a better understanding of the invention and its context. The terms including ordinal numbers such as first and second may be used to describe various elements, but the elements are not limited by the terms. The terms are used only for the purpose of distinguishing one element from another element. The term "and / or" includes any one of a plurality of relevant listed items or a combination thereof.

[0022] The terms used herein are merely for the purpose of illustrating a particular embodiment and are not intended to limit the embodiments of the present invention.

[0023] In the description of an embodiment, when an element is described as being formed "on or under" another element, the expression "on or under" includes at least one of that two elements come into direct contact with each other or that the other element is disposed between the two elements. In addition, the expression "on or under" may include not only the upward direction but also the downward direction with respect to one element.

[0024] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. The same reference numerals in different drawings may indicate the same or corresponding elements, and a duplicate description thereof will be omitted.

[0025] Referring to FIG. 1, a motor 1 according to an embodiment of the present invention may include a rotating shaft 1100, a rotor 1200, a stator 1300, and a housing 1400.

[0026] The rotating shaft 1100 may be coupled to the rotor 1200. When an electromagnetic interaction occurs between the rotor 1200 and the stator 1300 through a current supply, the rotor 1200 rotates and the rotating shaft 1100 rotates in conjunction with the rotor 1200. The rotating shaft 1100 may be supported by a bearing.

[0027] The rotor 1200 is disposed inside the stator 1300. The rotor 1200 may include a rotor core and a magnet coupled to the rotor core. The rotor 1200 may be classified into the following forms according to the coupling type between the rotor core and the magnet.

[0028] The rotor 1200 may be implemented as a type in which the magnet is coupled to an outer circumferential surface of the rotor core. According to the rotor 1200 of the above type, an additional can member may be coupled to the rotor core to prevent separation of the magnet and increase a coupling force. Alternatively, the magnet and the rotor may be integrally formed by double injection molding.

[0029] The rotor 1200 may be implemented as a type in which the magnet is coupled to an inside of the rotor core. For the rotor 1200 of the above type, a pocket into which the magnet is inserted may be provided in the rotor core.

[0030] Meanwhile, the rotor core may be classified into two types.

[0031] First, the rotor core may be formed by stacking a plurality of plates in the form of a thin steel plate. Here, the rotor core may be formed as a single piece that does not form a skew angle or may be formed of a plurality of unit cores (pucks), which form a skew angle, to be coupled to each other.

[0032] Second, the rotor core may be formed as a single cylinder. Here, the rotor core may be formed as a single piece that does not form a skew angle or may be formed of a plurality of unit cores (pucks), which form a skew angle, to be coupled to each other.

[0033] Meanwhile, each of the unit cores may include a magnet outside or inside the unit core.

[0034] The stator 1300 causes an electrical interaction with the rotor 1200 to induce rotation of the rotor 1200. A coil may be wound on the stator 1300 to cause the interaction with the rotor 1200. The specific configuration of the stator 1300 to wind the coil is as follows.

[0035] The stator 1300 may include a stator 1300 core including a plurality of teeth. The stator 1300 core may be provided with an annular yoke and teeth which protrude from an inner circumferential surface of the yoke toward a center of the stator 1300 core, may be provided. The teeth may be provided at regular gaps along a circumference of the yoke. Meanwhile, the stator 1300 core may be formed by stacking a plurality of plates in the form of a thin steel plate. In addition, the stator 1300 core may be formed by coupling or connecting a plurality of split cores to each other.

[0036] The housing 1400 is formed in a cylindrical shape so that a stator 1300 assembly may be coupled to an inner wall thereof. An upper portion of the housing 1400 may be implemented to be open, and a lower portion of the housing 1400 may be implemented to be closed. A bearing mounting space configured to accommodate a bearing for supporting a lower portion of the rotating shaft 1100 may be provided at the lower portion of the housing 1400. A cover may be coupled to the upper portion of the opened housing 1400.

[0037] FIG. 2 is a view showing a first embodiment of the rotor which is an element of the present invention.

[0038] Referring to FIG. 2, the rotor 1200 as an element of the present invention may include a rotor core 1210 surrounding the rotating shaft 1100 and a plurality of magnets 1230 coupled to the rotor core 1210, the magnets 1230 may be disposed to be spaced apart from the magnets 1230 adjacent in the axial direction of the rotating shaft 1100 by a predetermined gap, and the sum of the spaced gaps of the magnets 1230 may be set to have a ratio of 0.04 to 0.07 times an axial length of the stator 1300.

[0039] According to the present invention, the magnets 1230 disposed in the rotor core 1210 are spaced apart from each other in the direction of the rotating shaft 1100 to reduce the cogging torque.

[0040] When the rotor core 1210 is integrally formed, the magnets 1230 provided in a curved shape may be disposed on an outer surface of the rotor core 1210 to have a layered structure. In this case, the magnets 1230 may be disposed to be spaced apart from the magnets 1230 adjacent in the axial direction of the rotating shaft 1100 by a predetermined gap. Here, the sum of the gaps of the magnets 1230 formed of a multi-layered structure may be disposed to have a ratio of 0.04 to 0.07 times the axial length of the stator 1300.

[0041] Here, the gaps formed between the magnets 1230 having the layered structure and the adjacent magnets 1230 having the layered structure may be equal to each other.

[0042] In addition, when the rotor core 1210 is provided with a plurality of rotor cores, a height of each rotor core 1210 is set to be higher than a height of the magnet 1230 so that the magnets 1230 adjacent to each other in the axial direction of the rotating shaft 1100 may be disposed to be spaced apart from each other by a predetermined gap even when the rotor cores 1210 are tightly coupled to each other.

[0043] FIG. 3 is a view showing a second embodiment of the rotor 1200 which is an element of the present invention.

[0044] Referring to FIG. 3, the rotor core 1210 may be provided with a plurality of rotor cores and disposed to be spaced apart from the rotor cores 1210 adjacent in the axial direction of the rotating shaft 1100 by a predetermined gap. In this case, the gap of the rotor core 1210 may be adjusted by press-fitting equipment.

[0045] The rotor core 1210 and the magnet 1230 may have the same height. When the rotor cores 1210 are disposed to be spaced apart from each other, the sum of the gaps between the rotor cores 1210 may be the same as the sum of the gaps of the magnets 1230.

[0046] In addition, the sum of the gaps between the rotor cores 1210 is calculated as the sum of a first gap and a second gap formed by the rotor cores 1210, in which the first gap and the second gap may be formed at the same gap.

[0047] The sum of the gaps between the rotor cores 1210, in other words, the sum of the first gap and the second gap may be disposed to have a ratio of 0.04 to 0.07 times the axial length of the stator 1300.

[0048] FIG. 4 is a view showing a third embodiment of the rotor 1200 which is an element of the present invention. FIG. 5 is a view showing a shape of a spacer 1250 which is an element of FIG. 4.

[0049] Referring to FIGS. 4 and 5, a spacer 1250 may be provided between the rotor cores 1210 to define the gap between the rotor cores; When the rotor cores 1210 are disposed, the spacer 1250 may allow adjacent rotor cores 1210 to be spaced by a predetermined gap. The spacer 1250 may be disposed between the rotor cores 1210 to allow the rotor cores 1210 to be disposed at regular gaps. The spacer 1250 may be smaller than an outer diameter of the rotor core 1210 so that an interference of the spacer 1250 to the magnet 1230 may be minimized.

[0050] In one embodiment, the spacer 1250 may be provided in a circular ring shape and the rotating shaft 1100 may be inserted into the spacer 1250. The circular spacer 1250 having a constant thickness may stably support the gap formed by the spacer 1250 when the rotor 1200 rotates. The circular ring-shaped spacer 1250 is shown in FIG. 5, but the shape of the spacer 1250 is not limited and may be modified into various shapes.

[0051] In addition, the spacer 1250 disposed between the rotor cores 1210 allows the gap between the rotor cores 1210 to be maintained constantly, and the gap between the rotor cores 1210 may be an axial length of the spacer 1250. Here, the sum of axial lengths of a plurality of spacers 1250 may be disposed to have a ratio of 0.04 to 0.07 times an axial length of the stator 1300.

[0052] FIG. 6 is an enlarged view of an internal structure of the motor 1 according to an embodiment of the present invention.

[0053] Referring to FIG. 6, the stator 1300 is disposed adjacent to the outside of the rotor 1200.

[0054] In the structure where the plurality of rotor cores 1210 are coupled, the magnet 1230 attached to the rotor core 1210 protrudes from an upper surface and a lower surface of the stator 1300 in the axial direction of the rotating shaft 1100. In other words, when viewed from a side surface of the stator 1300, the magnet 1230 is disposed to protrude upward and downward from the stator 1300.

[0055] Here, the sum of a height h2 at which the magnet 1230 protrudes from the upper surface of the stator 1300 and a height h1 at which the magnet 1230 protrudes from the lower surface of the stator 1300 is equal to the sum of the gaps (D1+D2) between the magnets 1230. In other words, the sum of the height h of the stator 1300 is equal to the sum of the heights of the magnets 1230 having a multi-layered structure.

[0056] In addition, the height h2 at which the magnet 1230 protrudes from the upper surface of the stator 1300 may be equal to the height h1 at which the magnet 1230 protrudes from the lower surface of the stator 1300.

[0057] The arrangement of the magnets 1230 is intended to arrange the magnets 1230 at a center of the stator 1300 so that an influence of the gap of the magnet 1230 on the stator 1300 is minimized.

[0058] FIG. 7 is a view showing a change amount of a cogging torque according to the gap ratio of the magnet of the present invention.

[0059] Referring to FIG. 7, a graph shows changes in the cogging torque and the back electromotive force harmonic wave according to the change in the gap of the magnets 1230. [Table 1]Gap ratio (gap / stator stack)0.0%2.0%3.0%4.0%5.0%6.0%7.0%8.0%cogging torque15.815.014.612.610.29.712.3615.0

[0060] Table 1 shows quantitative values of the graph of FIG. 7.

[0061] It can be confirmed that the cogging torque decreases within a predetermined range as the ratio of the gaps formed by the magnets 1230 increase.

[0062] It can be confirmed that the cogging torque decreases gently when the gap ratio increases from 0% to 3%.

[0063] Thereafter, it can be confirmed that the cogging torque decreases sharply in the range of 3% to 6%, and the cogging torque increases again as the gap ratio increases from the vicinity of 6%.

[0064] Accordingly, it can be confirmed that the gap ratio according to the present invention is in the range of 4% to 7% to reduce the cogging torque, and it is more effective to reduce the cogging torque when the gap ratio is in the range of 5% to 6%.

[0065] FIGS.8 to 20 are views showing embodiments which are not part of the claimed invention.

[0066] FIG. 8 is a view showing a motor 1a.

[0067] Referring to FIG. 8, the motor 1a according to an embodiment may include a rotating shaft 2100, a rotor 2200, and a stator 2300.

[0068] The rotating shaft 2100 may be coupled to the rotor 2200. When an electromagnetic interaction occurs between the rotor 2200 and the stator 2300 by supplying a current, the rotor 2200 rotates and the rotating shaft 2100 rotates in conjunction with the rotor 2200. The rotating shaft 2100 may be connected to a steering shaft of the vehicle to transmit power to the steering shaft.

[0069] The rotor 2200 rotates through the electrical interaction with the stator 2300. The rotor 2200 may be disposed inside the stator 2300.

[0070] A coil may be wound on the stator 2300 to cause the electrical interaction with the rotor 2200. The specific configuration of the stator 2300 for winding the coil is as follows. The stator 2300 may include a stator core including a plurality of teeth. The stator core may be provided with an annular yoke portion, and the teeth may be provided around which the coil is wound from an inner circumferential surface of the yoke toward a center of the stator core. The teeth may be provided at regular gaps along an outer circumferential surface of the yoke portion. Meanwhile, the stator core may be formed by stacking a plurality of plates in the form of a thin steel plate. In addition, the stator core may be configured to have a plurality of split cores coupled or connected to each other.

[0071] The motor may include a bus bar 2400. The bus bar 2400 may be disposed on the stator 2300. The bus bar 2400 may include a terminal inside an annular mold member.

[0072] A housing 2500 of the motor may accommodate the rotor 2200 and the stator 2300 therein. The housing 2500 may include a body 2510 and a bracket 2520. The body 2510 has a cylindrical shape. The body 2510 may be formed of a metal material such as aluminum. In addition, the body 2510 is open at the top thereof. The bracket 2520 covers the open top of the body 2510. The stator 2300 may be disposed inside the body 2510, and the rotor 2200 may be disposed inside the stator 2300. A bearing 2530 may be disposed at a center of the bracket 2520. The bearing 2530 may be double injection-molded and integrated with the bracket 2520.

[0073] A sensing magnet 2600 is a device configured to be coupled to the rotating shaft 2100 to interlock with the rotor 2200 so as to detect a position of the rotor 2200.

[0074] A sensor configured to sense a magnetic force of the sensing magnet 2600 may be disposed on a printed circuit board 2700. Here, the sensor may be a Hall integrated circuit (IC). The sensor generates a sensing signal by sensing changes in N and S poles of the sensing magnet 2600.

[0075] FIG. 9 is a view showing coupling holes and magnets of the rotor.

[0076] Referring to FIG. 9, the rotor 2200 may include a rotor core 2210 and a magnet 2220. The rotor core 2210 may be implemented by stacking a plurality of plates in the form of a circular thin steel plate. A hole 2210a to which the rotating shaft 2100 is coupled may be disposed at a center of the rotor core 2210. The rotor core 2210 may include a plurality of coupling holes 2211. The coupling hole 2211 is formed through the rotor core 2210 in the height direction of the rotor core 2210. The height direction of the rotor core 2210 in the motor is a direction parallel to the axial direction of the rotating shaft 2100. The magnet 2220 is inserted into the coupling hole 2211. The number of the coupling holes 2211 is equal to the number of the magnets 2220. The coupling holes 2211 are disposed at regular gaps in a circumferential direction of the rotor core 2210. A plane shape of the coupling hole 2211 may be rectangular.

[0077] Gap portions G may be disposed on both sides of the coupling hole 2211. The gap portion G signifies a portion separated apart from the magnet 2220. The gap portion G is configured to prevent magnetic flux from leaking to an adjacent magnet 2220. Meanwhile, a bridge portion 2212 is disposed between adjacent coupling holes 2211. The bridge portion 2212 is disposed between the gap portions G of the adjacent coupling holes 2211.

[0078] FIG. 10 is a view showing the rotor. FIGS. 11 and 12 are exploded perspective views of the rotor shown in FIG. 10.

[0079] Referring to FIGS. 10 to 12, the rotor 2200 may be formed by stacking a plurality of rotor cores 2210. For example, the rotor 2200 may be formed by stacking three rotor cores 2210A, 2210B, and 2210C. Around a second rotor core 2210B disposed at a center of the rotor cores, a first rotor core 2210A may be disposed on the top of the second rotor core, and a third rotor core 2210C may be disposed on the bottom of the second rotor core. Each of the first, second and third rotor cores 2210A, 2210B and 2210C may be stacked to form a skew angle. In addition, the magnet (2220 of FIG. 9) is disposed inside each of the first, second and third rotor cores 2210A, 2210B, and 2210C.

[0080] Meanwhile, the rotor 2200 may include a first holder 2230 and a second holder 2240. The first holder 2230 and the second holder 2240 serve to fix the magnet 2220 to the coupling hole 2211 without an adhesive.

[0081] The first holder 2230 may be disposed between the first rotor core 2210A and the second rotor core 2210B or between the second rotor core 2210B and the third rotor core 2210C. For example, the first holder 2230 may be disposed between the second rotor core 2210B disposed at the center and the first rotor core 2210A disposed on the top of the second rotor core 2210B. In addition, the first holder 2230 may be disposed between the second rotor core 2210B disposed at the center and the third rotor core 2210C disposed on the bottom of the second rotor core 2210B. The second rotor core 2210B disposed at the center may be interposed between the two first holders 2230.

[0082] The second holder 2240 may be disposed on the top of the first rotor core 2210A disposed on the uppermost side. Alternatively, the second holder 2240 may be disposed on the bottom of the third rotor core 2210C disposed on the lowermost side. Two second holders 2240 may be disposed with the rotor core 2210 therebetween.

[0083] FIG. 13 is a perspective view showing the first holder viewed from above. FIG. 14 is a perspective view showing the second holder viewed from below. FIG. 15 is a plan view of the first holder.

[0084] The first holder 2230 may include a base plate 2231, first protrusions 2232, and second protrusions 2233.

[0085] The base plate 2231 may be formed in a disc shape. A through-hole 2231a is formed at a center of the base plate 2231. The rotating shaft 2100 passes through the through-hole 2231a.

[0086] The first protrusions 2232 may protrude from an upper surface of the base plate 2231. The second protrusions 2233 may protrude from a lower surface of the base plate 2231. The first protrusions 2232 and the second protrusions 2233 are disposed at regular gaps with respect to the circumferential direction of the first holder 2230. Positions of the first protrusions 2232 and positions of the second protrusions 2233 correspond to positions of the gap portion (G in FIG. 9) of the coupling hole 2211 of the rotor core 2210.

[0087] Referring to FIGS. 9, 10 and 13, the first protrusion 2232 may be forcibly fitted into the coupling hole 2211 of the first rotor core 2210A disposed on the upper side. Specifically, the plurality of first protrusions 2232 may be forcibly fitted into the gap portions (G in FIG. 9) of the coupling holes 2211 toward the low surface of the first rotor core 2210A disposed on the upper side, respectively. Alternatively, the plurality of second protrusions 2233 may be forcibly fitted into the gap portions (G in FIG. 9) of the coupling holes 2211 toward the upper surface of the second rotor core 2210B disposed at the center, respectively.

[0088] Alternatively, the second protrusion 2233 may be forcibly fitted into the coupling hole 2211 of the third rotor core 2210C disposed on the lower side. Specifically, the plurality of second projections 2233 may be forcibly fitted into the gap portions (G in FIG. 9) of the coupling holes 2211 toward the upper surface of the third rotor core 2210C disposed on the lower side, respectively. Alternatively, the plurality of first protrusions 2232 may be forcibly fitted into the gap portions (G in FIG. 9) of the coupling holes 2211 toward the lower surface of the second rotor core 2210B disposed at the center, respectively.

[0089] The first protrusions 2232 may be shifted from the second protrusions 2233 with respect to the circumferential direction of the first holder 2230. This is because the first rotor core 2210A and the second rotor core 2210B or the second rotor core 2210B and the third rotor core 2210C are disposed to be shifted from each other to form a skew angle.

[0090] Two first protrusions 2232 may be disposed in one coupling hole 2211. The number of the first protrusions 2232 disposed in the first holder 2230 may be double the number of the magnets 2220. In addition, two second protrusions 2233 may be disposed in one coupling hole 2211. The number of the second protrusions 2233 disposed in the first holder 2230 may be double the number of the magnets 2220.

[0091] FIG. 16 is a view showing the first protrusion inserted into the coupling hole of the rotor core.

[0092] Referring to FIG. 16, the first protrusion 2232 is forcibly fitted into the gap portion G. The first protrusion 2232 disposed between the coupling hole 2211 and the magnet 2220 presses the magnet 2220 so that the magnet 2220 is fixed to the coupling hole 2211. The second protrusion 2233 is also forcibly fitted into the gap portion G in the same manner as the first protrusion 2232 so that the magnet 2220 is fixed to the coupling hole 2211.

[0093] FIG. 17 is a view showing a shape of the first protrusion.

[0094] Referring to FIGS. 16 and 17, a sectional shape of the first protrusion 2232 corresponds to a planar shape of the spacing space between the coupling hole 2211 and the magnet 2220. For example, the sectional shape of the first protrusion 2232 may include a first region 10 and a second region 20.

[0095] A sectional shape of the first region 10 may have a triangular shape as a whole. A first surface 11 of the first region 10 comes into contact with a side surface of the coupling hole 2211 of the rotor core 2210. A second surface 12 of the first region 10 comes into contact with an outer surface of the coupling hole 2211. A third surface 13 of the first region 10 comes into contact with a side surface of the magnet 2220.

[0096] The second region 20 may correspond to a shape recessed around a corner defining a boundary between a side surface and an inner surface of the coupling hole 2211. For example, a sectional shape of the second region 20 may be rectangular. The second region 20 may be connected to an inner end of the first region 10.

[0097] With reference to the bridge portion 2212, a first protrusion 2232a, which is coupled to the coupling hole 2211A disposed on one side, and a first protrusion 2232b, which is coupled to the coupling hole 2211B disposed on the other side, may be symmetrically disposed. A distance W2 between the first protrusion 2232a and the first protrusion 2232b facing each other may be greater than a width W1 of the bridge portion 2212.

[0098] Although not shown in the drawings, a function, shape, and size of the second protrusion 2233 may be the same as those of the above first protrusion 2232.

[0099] FIG. 18 is a perspective view showing the second holder viewed from above. FIG. 19 is a perspective view showing the second holder viewed from below. FIG. 20 is a plan view of the second holder.

[0100] Referring to FIGS. 18 to 20, the second holder 2240 may include a second base plate 2241, third protrusions 2242, and a support portion 2243.

[0101] The second base plate 2241 may be formed in a disc shape. A second through-hole 2241a is formed at a center of the second base plate 2241. The rotating shaft 2100 passes through the second through-hole 2241a.

[0102] The third protrusions 2242 may protrude from a lower surface of the second base plate 2241. Here, the lower surface of the second base plate 2241 refers to a surface that faces the upper surface or the lower surface of the rotor core 2210 when the second holder 2240 is mounted on the rotor core 2210. The third protrusions 2242 are disposed at regular gaps with respect to a circumferential direction of the second holder 2240. Positions of the third protrusions 2242 correspond to the positions of the gap portions (G in FIG. 9) of the coupling holes 2211 of the rotor core 2210.

[0103] The shape and size of the third protrusion 2242 may be the same as the shape and size of the first protrusion 2232 or the shape and size of the second protrusion 2233. In addition, positions of the third protrusions 2242 correspond to the positions of the first protrusions 2232 and the second protrusions 2233. For example, Referring to FIG. 12, the second holder 2240 is coupled to the upper surface of the first rotor core 2210A, and the first holder 2230 is coupled to the lower surface of the first rotor core 2210A, with respect to the first rotor core 2210A. Here, because the first protrusion 2232 and the third protrusion 2242 are coupled to the same coupling hole 2211, the position of the third protrusion 2242 of the second holder 2240 corresponds to the position of the first protrusion 2232 of the first holder 2230. Alternatively, with respect to the third rotor core 2210C, the second holder 2240 is coupled to the lower surface of the third rotor core 2210C, and the first holder 2230 is coupled to the upper surface of the third rotor core 2210C. Here, because the second protrusion 2233 and the third protrusion 2242 are coupled to the same coupling hole 2211, the position of the second protrusion 2242 of the second holder 2240 corresponds to the position of the second protrusion 2233 of the first holder 2230.

[0104] The support portion 2243 may protrude from the upper surface of the second base plate 2241. The support portion 2243 may include a third through-hole 2243a disposed at a center thereof. The third through-hole 2243a communicates with the second through-hole 2241a. An inner diameter of the third through-hole 2243a may be the same as an outer diameter of the rotating shaft 2100. The support portion 2243 may support the bearing 2530 (in FIG. 8).

[0105] Referring to FIG. 18, the second holder 2240 may include a concave portion 2244. The concave portion 2244 may be formed to be concave on the upper surface of the second holder 2240. The concave portion 2244 may be disposed at regular gaps along the circumferential direction of the second holder 2240. The concave portion 2244 may be a weight reducing shape generated during injection molding. Accordingly, a weight of the second holder 2240 may be minimized.

[0106] The above descriptions are merely illustrative of the technical idea of the present invention.

[0107] The scope of the present invention should be understood according to the following claims.[Description of Reference Numerals]

[0108] 1, 1a: motor 1100: rotating shaft 1200: rotor 1210: rotor core 1230: magnet 1250: spacer 1300: stator 1400: housing 2100: rotating shaft 2200: rotor 2210: rotor core 2210A: first rotor core 2210B: second rotor core 2210C: third rotor core 2211: coupling hole 2212: bridge portion 2220: magnet 2230: first holder 2231: base plate 2232: first protrusion 2233: second protrusion 2240: second holder 2241: second base plate 2242: third protrusion 2243: support portion 2244: concave portion 2300: stator

Claims

1. A motor comprising: a housing (1400); a rotating shaft (1100) extending along an axial direction; a stator (1300) disposed in the housing and having an axial length (h) in the axial direction between a first end surface and a second end surface; and a rotor (1200) coupled to the rotating shaft (1100) and disposed inside the stator, wherein the rotor (1200) includes a rotor core (1210) surrounding the rotating shaft (1100) and a plurality of magnets (1230) coupled to the rotor core on an outer surface thereof in a skewed manner, wherein the rotor core comprises a plurality of rotor core members (1210), charcterized in that the rotor core members (1210) are spaced apart from each other in the axial direction, with predetermined gaps between adjacent rotor core members in the axial direction, wherein the gaps between the rotor core members (1210) consist of a first gap and a second gap between rotor core members, and wherein the first gap is equal to the second gap wherein the magnets (1230) are spaced apart from each other in the axial direction, wherein gaps (D1) between adjacent magnets in the axial direction are equal to each other, wherein the sum of the gaps between the magnets (1230) ranges from 0.04 to 0.07 times the axial length of the stator (1300), wherein a first one of the magnets (1230) protrudes in the axial direction with respect to the first end surface of the stator (1300) by a first axial length (h1), while a second one of the magnets (1230) protrudes in the axial direction with respect to the second end surface of the stator (1300) by a second axial length (h2), and wherein the sum of the first and second axial lengths (h1, h2) is equal to the sum of the gaps between the magnets (1230).

2. The motor of claim 1, wherein the sum of the gaps between adjacent rotor core members (1210) is equal to the sum of the gaps between the magnets (1230).

3. The motor of claim 2, comprising spacers (1250) disposed between adjacent rotor core members (1210) to define the predetermined gaps between the adjacent rotor core members, wherein an outer diameter of the spacer (1250) is smaller than an outer diameter of the rotor core.

4. The motor of claim 1, wherein the second axial length (h2) is equal to the first axial length (h1).

5. The motor of claim 1, wherein the sum of the gaps between the magnets (1230) ranges from 0.05 to 0.06 times the axial length of the stator (1300).