Patent Description:
Motors are apparatuses configured to convert electrical energy to mechanical energy to obtain rotational forces and are widely used for vehicles, home appliances, industrial machines, and the like.

Particularly, as more electric devices are used in a vehicle, demands for a motor applied to a steering system, a braking system, a machinery system, and the like are significantly increasing.

A motor may include a housing, a shaft, a stator disposed on an inner circumferential surface of the housing, a rotor disposed on an outer circumferential surface of the shaft, and the like. In this case, an electrical interaction is induced between the stator and the rotor so that the rotor rotates.

The rotor may include a rotor core and a plurality of magnets disposed on the rotor core. In the case of such a multi-pole motor, there is a problem in that loud noise and a great deal of vibration occur.

Although the stator may be over-molded to reduce the noise and vibration, there is a problem in that a production cost increases.

Accordingly, there is a need for a motor with a structure allowing production efficiency of the motor to be increased and the noise and vibration to also be reduced. <CIT>, <CIT> and <CIT> are examples of rotors.

The present invention is directed to providing a motor to which a robust design using an adhesive member such as glue is applied when sheets are stacked to form a stator core, thereby reducing noise and vibration.

Objectives to be solved by the present invention are not limited to the above-described objectives, and other objectives which are not described above will be clearly understood by those skilled in the art from the following specification.

The present invention claims a motor according to claim <NUM>.

Advantageous embodiments of the motor of the present invention are claimed in claims from <NUM> to <NUM>.

The motor includes a shaft, a rotor coupled to the shaft, and a stator disposed outside the rotor, wherein the stator includes a stator core formed by arranging a plurality of unit stator cores in a circumferential direction and a coil wound around the stator core, the unit stator core formed by stacking a plurality of sheets includes a yoke including a plurality of holes, a tooth protruding from the yoke in a radial direction, and an adhesive member disposed in the plurality of holes, and each of the plurality of holes is disposed on a virtual line (L) extending along one of both side surfaces of the tooth in the radial direction.

The line (L) may be parallel to a virtual line (L1) connecting a center (C) of the rotor and a center (C1) of the tooth.

The holes may be symmetrically disposed on the basis of the line (L1), and when viewed from above, a distance from the line (L1) to a center (C2) of the hole may be the same as a distance from the line (L1) to the side surface of the tooth.

Some amount of the adhesive member disposed in the plurality of holes may be disposed between the plurality of sheets. For example, when the adhesive member fills the holes, the adhesive member may penetrate between the sheets.

A diameter of each of the plurality of holes is greater than two times and less than three times a thickness of each of the plurality of sheets. When the thickness of the sheet in the shaft direction is <NUM>, a diameter of the hole may be greater than two times and less than three times the thickness.

A center (C2) of the hole may be disposed on the line (L).

The adhesive member may have an anaerobic property. In this case, a viscosity of the adhesive member may be greater than or equal to <NUM> mPa. s and less than <NUM> mPa.

The plurality of sheets forming at least one unit stator core among the plurality of unit stator cores may be formed by stacking a plurality of first sheets including the plurality of holes and a second sheet in which the hole is not formed.

The second sheet may be disposed on a lower surface of the first sheet disposed as a lowermost layer among the plurality of first sheets and may block the holes of the plurality of first sheets.

The holes may be symmetrically disposed on the basis of the virtual line (L1) connecting the center (C) of the rotor and the center (C1) of the tooth.

When viewed in the radial direction, the hole may be disposed to overlap the side surface of the tooth.

In addition, twelve teeth may be provided, and ten magnets of the rotor may be provided.

According to embodiments, a motor to which a robust design is applied can be formed to reduce noise and vibration, wherein the robust design can be implemented by stacking sheets to form a stator core and filling holes formed in the stator core with an adhesive member. Particularly, in the case of a multi-pole motor having ten poles and twelve slots, since louder noise and more vibration occur when compared to other motors, the noise and vibration of the motor can be reduced by filling the holes formed in the stator core with the adhesive member.

Although the robust design may be implemented by applying the adhesive member on the sheets and stacking the sheets, a cost and a time for a process increase. Accordingly, in the motor according to the embodiment, the adhesive member can penetrate between the sheets through the holes formed in the stator core to reduce the noise and vibration and also reduce a production cost.

In this case, the noise and vibration of the motor can be reduced further according to a viscosity of the adhesive member.

Various useful advantages and effects of the embodiments are not limited to the above-described contents and will be more easily understood from descriptions of the specific embodiments.

In addition, unless clearly and specifically defined otherwise by context, all terms (including technical and scientific terms) used herein can be interpreted as having customary meanings to those skilled in the art, and meanings of generally used terms, such as those defined in commonly used dictionaries, will be interpreted by considering contextual meanings of the related technology.

In the present specification, unless clearly indicated otherwise by the context, singular forms include the plural forms thereof, and in a case in which "at least one (or one or more) among A, B, and C" is described, this may include at least one combination among all possible combinations of A, B, and C.

In addition, in descriptions of components of the present invention, terms such as "first," "second," "A," "B," "(a)," and "(b)" can be used.

The terms are only to distinguish one element from another element, and an essence, order, and the like of the element are not limited by the terms.

In addition, it should be understood that, when an element is referred to as being "connected or coupled" to another element, such a description may include both of a case in which the element is directly connected or coupled to another element and a case in which the element is connected or coupled to another element with still another element disposed therebetween.

In addition, in a case in which any one element is described as being formed or disposed "on or under" another element, such a description includes both a case in which the two elements are formed or disposed in direct contact with each other and a case in which one or more other elements are interposed between the two elements. In addition, when one element is described as being disposed "on or under" another element, such a description may include a case in which the one element is disposed at an upper side or a lower side with respect to another element.

Hereinafter, example embodiments of the motor as disclosed will be described in detail with reference to the accompanying drawings. Components that are the same or correspond to each other will be denoted by the same reference numerals regardless of the figure numbers, and redundant descriptions will be omitted.

<FIG> is a view illustrating a motor according to an embodiment, <FIG> is a view illustrating a rotor and a stator of the motor according to the embodiment, and <FIG> is a view illustrating an arrangement relationship between the rotor and a stator core of the motor according to the embodiment. In <FIG>, an x direction may be referred to as a shaft direction and a y direction may be referred to as a radial direction. In addition, the shaft direction may be perpendicular to the radial direction. In this case, the stator core illustrated in <FIG> may be in a state before a hole is filled with an adhesive member.

Referring to <FIG> and <FIG>, a motor <NUM> according to the embodiment includes a housing <NUM> in which an opening is formed at one side, a cover <NUM> disposed on the housing <NUM>, a rotor <NUM> coupled to a shaft <NUM>, a stator <NUM> disposed in the housing <NUM>, the shaft <NUM> configured to rotate with the rotor <NUM>, a busbar <NUM> disposed on the stator <NUM>, and a sensor part <NUM> configured to detect rotation of the rotor <NUM>. In this case, the rotor <NUM> of the motor <NUM> may include ten magnets <NUM>, and the stator <NUM> may include twelve teeth <NUM>.

In this case, a stator core <NUM> of the stator <NUM> may be formed by stacking a plurality of sheets S in the shaft direction. In addition, an adhesive member B may penetrate between the sheets S by filling holes H formed in the stator core <NUM>. Accordingly, in the motor <NUM>, noise and vibration may be reduced due to the adhesive member B penetrating between the sheets S.

The motor <NUM> may be a motor used in an electronic power steering (EPS) system. The EPS system may assist a steering force using a driving force of the motor to secure turning stability and provide a rapid restoring force of a vehicle. Accordingly, a driver of the vehicle can travel safely.

The housing <NUM> and the cover <NUM> may form an exterior of the motor <NUM>. In addition, the housing <NUM> may be coupled to the cover <NUM> to form an accommodation space. Accordingly, as illustrated in <FIG>, the rotor <NUM>, the stator <NUM>, the shaft <NUM>, the busbar <NUM>, the sensor part <NUM>, and the like may be disposed in the accommodation space. In this case, the shaft <NUM> is rotatably disposed in the accommodation space. Accordingly, the motor <NUM> may further include bearings <NUM> disposed on an upper portion and a lower portion of the shaft <NUM>.

The housing <NUM> may be formed in a cylindrical shape. In addition, the rotor <NUM>, the stator <NUM>, and the like may be accommodated in the housing <NUM>. In this case, the shape or material of the housing <NUM> may be variously changed. For example, the housing <NUM> may be formed of a metal material which firmly withstands even at high temperature.

The cover <NUM> may be disposed on an open surface of the housing <NUM>, that is, an upper portion of the housing <NUM>, to cover an opening of the housing <NUM>.

Referring to <FIG>, the rotor <NUM> may be disposed inside the stator <NUM>, and the shaft <NUM> may be coupled to a central portion of the rotor <NUM> through a press-fitting method. In this case, the term "inside" may be referred to as a direction toward a center C, and the term "outside" may be referred to as a direction opposite to the term "inside.

In addition, the rotor <NUM> may be rotatably disposed inside the stator <NUM>.

Referring to <FIG> and <FIG>, the rotor <NUM> may include a rotor core <NUM> and a plurality of magnets <NUM> disposed on an outer circumferential surface of the rotor core <NUM> in a circumferential direction.

As illustrated in <FIG>, ten magnets <NUM> may be disposed on the outer circumferential surface of the rotor core <NUM> to be spaced apart from each other at preset intervals. In this case, the magnets <NUM> may be referred to as rotor magnets or drive magnets. In this case, an example in which the plurality of magnets <NUM> are disposed on the outer circumferential surface of the rotor core <NUM> of the rotor <NUM> is illustrated. For example, the rotor <NUM> may also be formed as an interior permanent magnet (IPM) rotor in which magnets <NUM> are disposed in a rotor core <NUM>.

The rotor core <NUM> is formed in a form in which a plurality of circular thin steel plates are stacked on each other or a single cylindrical form. In addition, a hole coupled to the shaft <NUM> may be formed at a center C of the rotor core <NUM>.

The magnets <NUM> generate a rotating magnetic field with coils <NUM> wound around the stator core <NUM> of the stator <NUM>. The magnets <NUM> may be disposed so that an N-pole and an S-pole are alternately disposed around the shaft <NUM> in the circumferential direction.

Accordingly, due to an electrical interaction between the coils <NUM> and the magnets <NUM>, the rotor <NUM> is rotated, and the shaft <NUM> is rotated in conjunction with the rotation of the rotor <NUM> so that a driving force of the motor <NUM> is generated.

Meanwhile, the rotor <NUM> may further include a can (not shown) disposed to cover the rotor core <NUM> to which the magnets <NUM> are attached.

The can may protect the rotor core <NUM> and the magnets <NUM> from external shocks and physical and chemical stimuli while preventing foreign materials from being introduced to the rotor core <NUM> and magnets <NUM>.

In addition, the can prevents the magnets <NUM> from being separated from the rotor core <NUM>.

The stator <NUM> may be disposed inside the housing <NUM>. In this case, the stator <NUM> may be coupled to the housing <NUM> through a hot press fitting method. Accordingly, the stator <NUM> may be supported by an inner circumferential surface of the housing <NUM>. In addition, the stator <NUM> is disposed outside the rotor <NUM>. That is, the rotor <NUM> may be rotatably disposed inside the stator <NUM>.

Referring to <FIG> and <FIG>, the stator <NUM> may include the stator core <NUM>, insulators <NUM> disposed on the stator core <NUM>, and the coils <NUM> wound around the insulators <NUM>. In this case, the insulators <NUM> may be disposed between the stator core <NUM> and the coils <NUM> to insulate the coils <NUM>.

The coils <NUM> configured to generate a rotating magnetic field are wound around the stator core <NUM>.

The stator core <NUM> includes yokes <NUM> in which holes H are formed, teeth <NUM> protruding from the yokes <NUM> in the radial direction, and the adhesive member B disposed in the holes H.

<FIG> is a perspective view illustrating the stator core of the motor according to the embodiment.

Referring to <FIG>, the stator core <NUM> is formed in a form in which a plurality of thin steel sheets S are stacked on each other. Accordingly, when the adhesive member B fills the holes H, the adhesive member B may penetrate between the sheets S to reduce noise and vibration of the motor <NUM>. In this case, each of the plurality of sheets S may have a predetermined thickness T in the shaft direction. In this case, the thickness T may be <NUM>.

The yokes <NUM> may be formed in a cylindrical shape. In addition, the plurality of teeth <NUM> may be disposed to protrude from an inner circumferential surface of the yokes <NUM> in the radial direction. In this case, the teeth <NUM> may be disposed to be spaced apart from each other in the circumferential direction. Accordingly, slots may be formed between the teeth <NUM> for winding the coils <NUM>.

In addition, the coil <NUM> is wound around the tooth <NUM>. In this case, the insulator <NUM> may be disposed between the tooth <NUM> and the coil <NUM> to insulate the tooth <NUM> from the coil <NUM>.

The plurality of holes H are disposed in the yokes <NUM> to be spaced apart from each other in the circumferential direction. In this case, the holes H may be formed in the yokes <NUM> to pass through the yokes <NUM> in the shaft direction.

Referring to <FIG>, the holes H may be disposed on virtual lines L each extending along a corresponding side surface <NUM> of the teeth <NUM> in the radial direction. Accordingly, when viewed in the radial direction, the holes H may be disposed to overlap the side surfaces <NUM> of the teeth <NUM>.

As illustrated in <FIG>, since two side surfaces <NUM> of the tooth <NUM> are provided, two holes H may also be provided to correspond to the side surfaces <NUM> of the tooth <NUM>.

In this case, a center C2 of the hole H may be disposed on the line L but is not necessarily limited thereto. For example, the hole H may also be disposed in the yoke <NUM> in a range in which an outer diameter of the hole H does not deviate the line L.

In this case, the line L may be parallel to a virtual line L1 connecting a center C of the rotor <NUM> and a center C1 of the tooth <NUM>. Accordingly, the two holes H may be symmetrically disposed on the basis of the line L1, and a distance D1 from the line L1 to the center C2 of the hole may be the same as a distance from the line L1 to the side surface <NUM> of the tooth <NUM>.

Meanwhile, a diameter D of the hole H is greater than or equal to two times and less than three times the thickness T of the sheet S in the shaft direction. Accordingly, when the thickness T of the sheet S is <NUM>, the diameter D of the hole H may be in the range of φ1. <NUM>≤D<φ1.

In addition, since the holes H are filled with the adhesive member B, the adhesive member B may penetrate between the sheets S. For example, when the adhesive member B fills the holes H, the adhesive member B may penetrate between the sheets S stacked in the shaft direction due to the capillary phenomenon.

In this case, the adhesive member B filling the hole H may be glue having an anaerobic property. Accordingly, the adhesive member B may be cured without performing a curing process using thermal curing or ultraviolet curing. In addition, a viscosity of the adhesive member B may be <NUM> mPa. s or more and less than <NUM> mPa.

For example, in a case in which the viscosity of the adhesive member B is <NUM> mPa. s, the adhesive member B penetrates between the sheets S at high speed so that a section in which the adhesive member B is not applied is not present between the sheets S. That is, the adhesive member B may be applied between all the sheets S. However, in a case in which the viscosity of the adhesive member B is less than <NUM> mPa. s, the adhesive member B may be applied between the sheets S and leak to the outside.

In addition, in a case in which the viscosity of the adhesive member B is <NUM> mPa. s, although the adhesive member B penetrates between the sheets S, a section is formed in which the adhesive member B may not penetrate to an inner side of the tooth <NUM> through between the sheets S. In addition, the viscosity of the adhesive member B is <NUM> mPa. s, since it takes a considerable amount of time for the adhesive member B to penetrate between the sheets S, workability is degraded, curing proceeds, and thus a section may be formed in which the adhesive member B does not penetrate between the sheets S, wherein the section may be half of an area of the sheet S.

Accordingly, the adhesive member B, which has a viscosity greater than or equal to <NUM> mPa. s and less than <NUM> mPa. s, of the motor <NUM> may be selected in consideration of penetration speed and the capillary phenomenon.

<FIG> is a table comparing electrical performance variations according to the diameter of the hole formed in the stator core of the motor according to the embodiment, <FIG> are graphs showing a cogging torque of a comparative example and a cogging torque according to the diameter of the hole formed in the stator core of the motor according to the embodiment, and <FIG> and <FIG> are graphs showing electrical performance variations according to the diameter of the hole formed in the stator core of the motor according to the embodiment.

<FIG> is the graph showing the cogging torque of the comparative example, <FIG> is the graph showing the cogging torque in a case in which the diameter of the hole formed in the stator core is φ1. <NUM>, <FIG> is the graph showing the cogging torque in a case in which the diameter of the hole formed in the stator core is φ1. <NUM>, and <FIG> is the graph showing the cogging torque in a case in which the diameter of the hole formed in the stator core is φ2. In addition, <FIG> is a graph showing a torque according to the change in diameter of the hole, <FIG> is a graph showing a cogging torque according to the change in diameter, <FIG> is a graph showing a ripple according to the change in diameter of the hole, and <FIG> is a graph showing a counter electromotive force according to the change in diameter of the hole.

In this case, a motor provided as the comparative example is a motor in which a hole is not formed in a stator core. In this case, changes in electrical performance of experimented motors, each of which includes a rotor having ten magnets and a stator having twelve teeth, are compared, and the motor <NUM> is in a state in which the hole is not filled with the adhesive member.

Referring to <FIG> and <FIG>, in a case in which the diameter D of the hole H is in the range of φ1. <NUM>≤D<φ1. <NUM>, it may be seen that changes in torque, cogging torque, ripple, and counter electromotive force of the motor <NUM> are insignificant.

Referring to <FIG>, it may be seen that, when the diameter D of the hole H is in the range of φ1. <NUM>≤D<φ1. <NUM>, the torque is insignificantly decreased, but when the diameter D of the hole H is greater than φ1. <NUM>, a torque reduction rate increases.

Referring to <FIG>, it may be seen that, when the diameter D of the hole H is in the range of φ1. <NUM>≤D<φ1. <NUM>, the cogging torque increases insignificantly, but when the diameter D of the hole H is greater than φ1. <NUM>, the cogging torque decreases sharply. However, it may be seen that when the values are considered, since the cogging torque decreases from <NUM> mNm to <NUM> mNm, when the diameter D of hole H is greater than φ1. <NUM>, the cogging torque decreases slightly.

Referring to <FIG>, it may be seen that, when the diameter D of the hole H is in the range of φ1. <NUM>≤D<φ1. <NUM>, a ripple increases insignificantly, but when the diameter D of the hole H is greater than φ1. <NUM>, the ripple increases sharply.

Referring to <FIG>, it may be seen that when the diameter D of the hole H is in the range of φ1. <NUM>≤D<φ1. <NUM>, a counter electromotive force decreases insignificantly, but when the diameter D of the hole H is greater than φ1. <NUM>, the counter electromotive force decreases sharply.

<FIG> is a table showing a reduction in vibration before and after filling with an adhesive member of the motor according to the embodiment when a viscosity of the adhesive member is <NUM> mPa. <FIG> is a table showing a reduction in vibration before and after filling with an adhesive member of the motor according to the embodiment when the viscosity of the adhesive member is <NUM> mPa.

Referring to <FIG>, it may be seen that when the viscosity of the adhesive member B filling the hole H is <NUM> mPa. s, an amplitude in a section between <NUM> to <NUM> is decreased by about <NUM>%.

Referring to <FIG>, it may be seen that the viscosty of the adhesive member B filling the hole H is <NUM> mPa. s, the amplitude in the section between <NUM> to <NUM> is decreased by about <NUM>%.

Referring to <FIG>, a plurality of unit stator cores 410a may be disposed in the circumferential direction to form the stator core <NUM>. In this case, the unit stator core 410a including the holes H passing therethrough in the shaft direction may be referred to as a first unit stator core.

<FIG> is a perspective view illustrating the unit stator core of the motor according to the embodiment, <FIG> is a plan view illustrating the unit stator core of the motor according to the embodiment, <FIG> is a perspective view illustrating a sheet of the unit stator core of the motor according to the embodiment, and <FIG> is a view illustrating the adhesive member which permeates the unit stator core of the motor according to the embodiment.

Referring to <FIG>, the unit stator core 410a may be formed by stacking sheets Sa including yokes 411a having an arc shape and teeth 412a protruding from the yokes 411a in the radial direction and filling the holes with the adhesive member B. As illustrated in <FIG>, the holes H may be formed in the yoke 411a. In this case, the sheet Sa in which the holes H are formed to form the unit stator core 410a may be referred to as a first sheet.

Accordingly, as illustrated in <FIG>, the adhesive member B may fill the holes H formed in the unit stator core 410a to penetrate between the sheets Sa. Accordingly, noise and vibration of the motor <NUM> may be reduced.

<FIG> is a perspective view illustrating another example of the unit stator core of the motor according to the embodiment.

Referring to <FIG>, a plurality of unit stator cores 410b may be disposed in the circumferential direction to form the stator core <NUM>.

When the unit stator core 410b is compared to the first unit stator core which is the unit stator core 410a including the holes H passing therethrough in the shaft direction, there is a difference in that the unit stator core 410b, which is another example thereof, further includes a second sheet Sb which blocks the holes at a lower side of the unit stator core 410b. Accordingly, the unit stator core 410b which is another example thereof may be referred to as a second unit stator core.

Referring to <FIG>, the unit stator core 410b, which is another example thereof, may include the plurality of first sheets Sa in which the holes H are formed and one second sheet Sb disposed below the first sheets Sa. In this case, the holes H are not present in the second sheet Sb. Accordingly, the second sheet Sb may block the holes H of the plurality of first sheets Sa, which are disposed to be stacked, to prevent the adhesive member B from leaking to a lower side of the unit stator core 410b.

<FIG> is a view illustrating still another example of the stator core of the motor according to the embodiment.

In the examples, the unit stator cores 410a or 410b are disposed in the circumferential direction to form the above-described stator core <NUM>.

As illustrated in <FIG>, the stator core <NUM> may also be formed by stacking sheets Sc including a yoke 411b having a ring shape and a plurality of teeth 412b protruding from the yoke 411b in the radial direction. In this case, each of the plurality of sheets Sc may have a predetermined thickness T in the shaft direction. In this case, the thickness T may be <NUM>.

However, in the case in which the stator core <NUM> is formed using the unit stator cores 410a or 410b, since the adhesive member B may penetrate along contact surfaces between the unit stator cores 410a or 410b in the shaft direction according to the viscosity of adhesive member B, noise and vibration of the motor <NUM> may decrease further.

For example, when the adhesive member B fills the holes H in a state in which the plurality of unit stator cores 410a or 410b are disposed in the circumferential direction, and the plurality of unit stator cores 410a or 410b are temporarily assembled through a spot-welding method or the like, the adhesive member B may penetrate between the sheets Sa and permeate along contact surfaces between the unit stator cores 410a or 410b in the shaft direction.

Meanwhile, the tooth <NUM> may be disposed to face the magnet <NUM> of the rotor <NUM>. In addition, the coil <NUM> is wound around each of the teeth <NUM>.

The insulator <NUM> may be formed of a synthetic resin material to insulate the stator core <NUM> from the coil <NUM>.

In addition, the coil <NUM> may be wound around the stator core <NUM> on which the insulator <NUM> is disposed. In addition, the coil <NUM> may generate a rotating magnetic field when power is supplied thereto.

The insulators <NUM> may be coupled to an upper side and a lower side of the stator core <NUM>. In this case, the insulators <NUM> may also be formed as one single product to be coupled to the stator core <NUM>. Alternatively, a plurality of unit insulators may also be formed as the insulators <NUM> so that the insulators <NUM> are disposed on the stator core <NUM> in the circumferential direction.

As illustrated in <FIG>, the shaft <NUM> may be rotatably supported by the bearings <NUM> in the housing <NUM>. In addition, the shaft <NUM> may be rotated in conjunction with the rotation of the rotor <NUM>.

The busbar <NUM> may be disposed on the stator <NUM>.

In addition, the busbar <NUM> may be electrically connected to the coil <NUM> of the stator <NUM>.

The busbar <NUM> may include a busbar body and a plurality of terminals disposed in the busbar body. In this case, the busbar body may be a mold product formed through an injection molding process. In addition, each of the terminals may be electrically connected to the coil <NUM> of the stator <NUM>.

The sensor part <NUM> may detect a magnetic force of a sensing magnet installed to rotate in conjunction with the rotor <NUM> to check a present position of the rotor <NUM> so as to detect rotation of the shaft <NUM>.

The sensor part <NUM> may include a sensing magnet assembly <NUM> and a printed circuit board (PCB) <NUM>.

The sensing magnet assembly <NUM> is coupled to the shaft <NUM> to rotate in conjunction with the rotor <NUM> so as to detect a position of the rotor <NUM>. In this case, the sensing magnet assembly <NUM> may include sensing magnets and a sensing plate. The sensing magnets and the sensing plate may be coaxially coupled.

The sensing magnets may include main magnets disposed close to a hole forming an inner circumferential surface thereof in the circumferential direction and sub-magnets.

The main magnets may be arranged like the drive magnets inserted into the rotor <NUM> of the motor.

The sub-magnets may be divided further than the main magnets so that the sub-magnets may be formed to have poles of which the number is greater than the number of poles of the main magnets. Accordingly, a rotation angle may be divided and measured more precisely, and thus the motor may be driven more smoothly.

The sensing plate may be formed of a metal material having a disc shape. The sensing magnet may be coupled to an upper surface of the sensing plate. In addition, the sensing plate may be coupled to the shaft <NUM>. In this case, a hole through which the shaft <NUM> passes may be formed in the sensing plate.

A sensor configured to detect a magnetic force of the sensing magnets may be disposed on the PCB <NUM>. In this case, a Hall integrated circuit (IC) may be provided as the sensor. In addition, the sensor may detect changes in an N-pole and an S-pole of the sensing magnet to generate a sensing signal.

While the present invention has been described with reference to the exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.

Claim 1:
A motor comprising:
a shaft (<NUM>);
a rotor (<NUM>) coupled to the shaft (<NUM>); and
a stator (<NUM>) disposed outside the rotor (<NUM>),
wherein the stator (<NUM>) includes a stator core (<NUM>) formed by arranging a plurality of unit stator cores (410a) in a circumferential direction and a coil wound around the stator core (<NUM>),
wherein the unit stator core (410a), formed by stacking a plurality of sheets (S) in an axial direction, includes a yoke (<NUM>) including a plurality of holes (H) passing through the yoke in the shaft direction, a tooth (<NUM>) protruding from the yoke (<NUM>) in a radial direction, and an adhesive member (B) disposed in the plurality of holes (H) and between the sheets (S),
characterized in that
each of the two side surfaces (<NUM>) of the tooth (<NUM>) extends on a plane parallel to the radial direction, and the center of each of the plurality of holes (H) is on the plane on which the corresponding side surface (<NUM>) of the tooth extends, and wherein
a diameter of each of the plurality of holes (H) is greater than two times and less than three times a thickness of each of the plurality of sheets (S).