Patent Description:
<CIT> discloses a motor according to the preamble of claim <NUM>.

<CIT> discloses a motor with a core. Holding grooves of the core are formed axially on an outer periphery of a rotational shaft in the shape that openings are narrower than at an inside such as in a dovetail shape.

Motors are devices which obtain torque by converting electrical energy into mechanical energy and are generally used in a vehicle, a home appliance, industrial equipment, and the like.

A motor may include a housing, a shaft, a stator disposed inside the housing, and a rotor installed on an outer circumferential surface of the shaft, and the like. Here, the stator of the motor causes an electrical interaction with the rotor and induces rotation of the rotor. Further, the shaft also rotates according to the rotation of the rotor.

Particularly, the motor may be used in a device for guaranteeing stability in steering of a vehicle. For example, the motor may be used in a motor for a vehicle such as an electronic power steering system (EPS) and the like.

A plurality of magnets are installed on the rotor. Here, depending on a method of installing the magnets, rotors are classified into an interior permanent magnet (IPM) type rotor in which magnets are inserted into and coupled to the rotor core and a surface permanent magnet (SPM) type rotor in which magnets are attached to a surface of a rotor core.

In the case of a motor including an SPM type rotor, since magnets are coupled to a rotor core only through bonding, when a bonding force becomes decreased, magnets are separated from the rotor core.

Meanwhile, magnets may be attached to an outer circumferential surface of the rotor core. Also, protrusions may be disposed on the outer circumferential surface of the rotor core. Here, a plurality of such protrusions may be arranged along the outer circumferential surface of the rotor core. Here, the plurality of magnets may each be disposed between the protrusions.

A position of each of the magnets has an effect on cogging torque of the motor. Due to a tolerance in a circumferential width of each of magnets and a tolerance in a distance between the protrusions, an error may occur in the position of each of magnets. When an error occurs in the position of each of magnets, the cogging torque increases.

Embodiments provide a rotor configured to protect magnets using a can and to prevent magnets attached to a rotor core from detaching using protrusions formed on the can at the same time and a motor including the rotor.

Embodiments are directed to providing a motor which reduces cogging torque.

Aspects of embodiments are not limited to the above-stated aspect and other unstated aspects thereof will be understood by those skilled in the art from a following description.

One aspect of the present invention provides a motor including a shaft, a rotor coupled to the shaft, and a stator disposed outside the rotor. Here, the rotor includes a first can, a rotor core at least partially disposed in the first can, a plurality of magnets coupled to the rotor core, and a second can in which another part of the rotor core is disposed. The plurality of magnets are arranged to be spaced apart in a circumferential direction due to a plurality of separation spaces. The first can includes a first plate portion, a first protruding portion formed by bending an edge of the first plate portion, and a plurality of first protrusions disposed in at least two different separation spaces of the plurality of separation spaces and spaced apart. The second can includes a second plate portion, a second protruding portion formed by bending an edge of the second plate portion, and a plurality of second protrusions disposed in at least two different separation spaces of the plurality of separation spaces and spaced apart. The first protrusions and the second protrusions are arranged to be diagonal to one another.

The first protrusions and the second protrusions may be arranged at different heights on the basis of bottom surfaces of the magnets.

The first protrusions may be formed on an end of the first protruding portion, and the second protrusions may be formed on an end of the second protruding portion.

The end of the first protruding portion may come into contact with the end of the second protruding portion.

The first protrusions may be formed to protrude from an inner circumferential surface of the first protruding portion, and grooves may be formed on an outer circumferential surface of the first protruding portion at positions corresponding to the first protrusions.

Distances between the first protrusions and the second protrusions may be uniform.

According to the invention the separation space is formed to extend from a top surface to a bottom surface of the rotor core, and the first protrusion and the second protrusion are arranged in a region more adjacent to a center than both ends of the separation space.

The rotor core may include a plurality of accommodation portions which accommodate the plurality of magnets, and at least one of the plurality of accommodation portions may include a surface in which a groove is formed. Here, the rotor core may include a plurality of guides formed to extend outward from an outer circumferential surface thereof. Each of the plurality of guides may be disposed in each of the plurality of separation spaces, and the accommodation portion may be defined as a region between the plurality of guides. The groove of the accommodation portion may be formed to extend from a top surface of the rotor core to a bottom surface of the rotor core and be disposed to be adjacent to the guide.

Another aspect of the present invention provides a rotor including a rotor portion including a rotor core and a plurality of magnets arranged to be spaced apart on an outer circumferential surface of the rotor core, a first can configured to cover an upper part of the rotor portion, and a second can configured to cover a lower part of the rotor portion. Here, the first can includes first protrusions arranged in separation spaces each formed between the magnets, and the second can includes second protrusions arranged in the separation spaces each formed between the magnets.

Here, the first protrusions and the second protrusions may be alternately arranged along a circumferential direction of the rotor core.

One side of the magnet may come into contact with the first protrusion, and the other side of the magnet may come into contact with the second protrusion.

The first can may include a ring-shaped first plate portion disposed above the rotor portion and a first protruding portion protruding from an outer circumferential surface of the first plate portion in an axial direction. The second can may include a ring-shaped second plate portion disposed below the rotor portion and a second protruding portion protruding from an outer circumferential surface of the second plate portion in the axial direction. The first protrusions may be formed on the first protruding portion, and the second protrusions may be formed on the second protruding portion.

The first protrusions formed on the first protruding portion may be arranged to be spaced at a certain distance from the first plate portion, and the second protrusions formed on the second protruding portion may be arranged to be spaced at a certain distance from the second plate portion.

The first protrusion may be formed by pressurizing one region of an outer circumferential surface of the first protruding portion, and the second protrusion may be formed by pressurizing one region of an outer circumferential surface of the second protruding portion.

The first can may include a first groove formed by pressurizing one region of the outer circumferential surface of the first protruding portion, and a lower side of the first groove may communicate with the separation space.

The second can may include a second groove formed by pressurizing one region of the outer circumferential surface of the second protruding portion, and an upper side of the second groove may communicate with the separation space.

As the first protrusion and the second protrusion are formed, a side surface of each of the first protrusion and the second protrusion may be pressed against a side surface of the magnet.

The first plate portion of the first can and the second plate portion of the second can may be fixed to the rotor core through welding.

The rotor core of the rotor portion may further include guides protruding outward from an outer circumferential surface thereof, and the magnet may be disposed between the guides.

An inner surface of each of the first protrusion and the second protrusion may be disposed to be spaced apart from an outer surface of the guide.

The first protrusions and the second protrusions may be formed to be rotationally symmetrical to each other on the basis of a center of the rotor core.

Still another aspect of the present invention provides a motor including a shaft, a rotor on which the shaft is disposed at a center, and a stator disposed outside the rotor. The rotor includes a rotor portion including a rotor core and a plurality of magnets arranged to be spaced apart on an outer circumferential surface of the rotor core, a first can configured to cover an upper part of the rotor portion, and a second can configured to cover a lower part of the rotor portion. Here, the first can includes first protrusions arranged in separation spaces each formed between the magnets, and the second can includes second protrusions arranged in the separation spaces each formed between the magnets.

Yet another embodiment of the present invention provides a motor including a stator, a rotor disposed inside the stator and including a rotor core and magnets disposed on an outer circumferential surface of the rotor core, and a shaft coupled to the rotor. Here, the rotor core includes a cylindrical body and a plurality of guides protruding from an outer circumferential surface of the body in a radial direction. The body includes a surface disposed between the guides and on which the magnets are arranged and grooves formed to be recessed from the surface toward a center of the rotor. The guides include a first guide and a second guide disposed to be adjacent to the first guide. The grooves are asymmetrically arranged on the surface on the basis of a virtual line which connects a center of the body to a circumferential center between the first guide and the second guide.

The grooves may be consecutively arranged from a top surface to a bottom surface of the rotor core in an axial direction.

The grooves may be arranged on one side on the basis of the virtual line. The surface may include a first surface with the grooves and a second surface without the grooves. The magnet may be disposed to be spaced apart from the first guide and come into contact with the second guide.

The grooves may include a first groove and a second groove. The surfaces may include a first surface in which the first groove is disposed and a second surface in which the second groove is disposed on the basis of the virtual line. The first guide may be disposed to be adjacent to the first surface, and the second guide may be disposed to be adjacent to the second surface. A size of the first groove may be greater than a size of the second groove. The magnet may be disposed to be spaced apart from the first guide and come into contact with the second guide.

A plurality of such first grooves and a plurality of such second grooves may be formed. A sum of the sizes of the plurality of first grooves may be greater than a sum of the sizes of the plurality of second grooves.

A further embodiment of the present invention provides a motor including a stator, a rotor disposed inside the stator and including a rotor core and magnets arranged on an outer circumferential surface of the rotor core, and a shaft coupled to the rotor. The rotor core includes a cylindrical body and a plurality of guides protruding from an outer circumferential surface of the body in a radial direction. The guides include a first guide and a second guide disposed to be adjacent to the first guide. The body includes a first part and a second part distinguished on the basis of a virtual line which connects a center of the body to a circumferential center between the first guide and the second guide. A volume of the first part and a volume of the second part differ from each other.

The first guide may be disposed to be adjacent to the first part, and the second guide may be disposed to be adjacent to the second part. The volume of the second part may be greater than the volume of the first part. The magnet may be disposed to be spaced apart from the first guide and come into contact with the second guide.

The first part may include a groove formed to be recessed from an outer circumferential surface of the first part, and the second part may not include a groove formed to be recessed from an outer circumferential surface of the second part.

A first groove may be disposed in the outer circumferential surface of the first part, a second groove may be disposed in the outer circumferential surface of the second part, and a size of the first groove may be greater than a size of the second groove.

A sum of sizes of a plurality of such first grooves may be greater than a sum of sizes of a plurality of such second grooves.

A rotor according to embodiments which includes the above components and a motor including the rotor can prevent magnets from being separated by disposing a protrusion formed on a can between the magnets.

Also, the number of such protrusions can be minimized by forming the protrusion on a first can disposed above a rotor portion and a second can disposed therebelow and alternately arranging the protrusions formed on the first can and the second can along a circumferential direction.

Since the protrusions can be formed by pressurizing one regions of the first can and the second can while the first can and the second can are disposed on the rotor portion, minimization of the number of the protrusions may minimize a load applied to the magnets. Accordingly, damages to the magnets can be minimized.

Also, since the protrusions may be formed by pressurizing one regions of the first can and the second can, the rotor and the motor including the rotor may be pressed against the magnets to a degree and have a vibration-suppressing property.

Also, the first can and the second can are implemented to have the same shape so as to reduce manufacturing costs of the cans.

According to the embodiments, an effect of a motor configured to reduce cogging torque by stably mounting magnets in precise positions is provided.

A variety of advantageous effects of the embodiments are not limited thereto and will be easily understood throughout the detailed description of the embodiments.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

However, the technical concept of the present invention is not limited to some embodiments disclosed below but can be implemented in a variety of different forms. One or more of components of the embodiments may be selectively combined or substituted with one another without departing from the scope of the technical concept of the present invention.

Also, unless defined otherwise, the terms (including technical and scientific terms) used herein may be used as meanings capable of being commonly understood by one of ordinary skill in the art. Also, terms defined in generally used dictionaries may be construed in consideration of the contextual meanings of the related art.

Also, the terms used herein are intended to describe the embodiments but not intended to restrict the present invention.

Throughout the specification, unless particularly stated otherwise, singular forms include plural forms. When the present invention is stated to include at least one (or one or more) of A, B, and C, one or more of all combinations of A, B, and C may be included.

Also, in describing components of the embodiments of the present invention, the terms such as first, second, A, B, (a), (b), and the like may be used.

These terms are merely for distinguishing one element from another, and the essential, order, sequence, and the like of corresponding elements are not limited by the terms.

Also, when it is stated that one element is "connected," or "coupled" to another, the element may not only be directly connected or coupled to the other element but may also be connected or coupled to the other element with another intervening element.

Also, when it is stated that an element is formed or disposed "above (on) or below (under)" another element, not only may the two elements come into direct contact with each other but also still another element may be formed or disposed between the two elements. Also, being "above (on) or below (under)" may include not only being in an upward direction but also being in a downward direction on the basis of one element.

Hereinafter, the embodiments will be described below in detail with reference to that attached drawings. However, equal or corresponding components will be referred to as the same reference numerals regardless of drawing signs, and a repetitive description thereof will be omitted.

<FIG> is a view illustrating a motor according to embodiments.

Referring to <FIG>, a motor <NUM> according to embodiments may include a housing <NUM> with an opening formed in one side, a cover <NUM> disposed above the housing <NUM>, a stator <NUM> disposed inside the housing <NUM>, a rotor <NUM> disposed inside the stator <NUM>, a shaft <NUM> configured to rotate with the rotor <NUM>, a busbar <NUM> disposed above the stator <NUM>, and a sensor portion <NUM> configured to sense rotation of the rotor <NUM>. Here, the motor <NUM> according to embodiments may be a motor according to a first embodiment.

The motor <NUM> may be a motor used in an electronic power steering system (EPS). The EPS allows a driver to perform safe driving by securing turning stability and providing a quick restoring force by aiding in a steering force using a driving force of a motor.

The housing <NUM> and the cover <NUM> may form an exterior of the motor <NUM>. Also, an accommodation space may be formed by coupling between the housing <NUM> and the cover <NUM>. Accordingly, in the accommodation space, as shown in <FIG>, the rotor <NUM>, the stator <NUM>, the shaft <NUM>, the busbar <NUM>, the sensor portion <NUM>, and the like may be arranged. Here, the shaft <NUM> is rotatably disposed in the accommodation space. Hence, the motor <NUM> may further include bearings <NUM> disposed above and below the shaft <NUM>.

The housing <NUM> may be formed to have a cylindrical shape. Also, the housing <NUM> may accommodate the stator <NUM>, the rotor <NUM>, and the like therein. Here, a shape or a material of the housing <NUM> may be variously modified. For example, the housing <NUM> may be formed of a metal material capable of withstanding high temperatures well.

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

The rotor <NUM> may be disposed inside the stator <NUM>, and the shaft <NUM> may be coupled to a central part of the rotor <NUM>. Here, the rotor <NUM> may be rotatably disposed inside the stator <NUM>. Here, the inside may mean a direction toward a center C, and the outside may mean a direction opposite the inside.

<FIG> is a perspective view illustrating the rotor of the motor according to embodiments, <FIG> is an exploded perspective view illustrating the rotor of the motor according to embodiments, <FIG> is a plan view illustrating the rotor of the motor according to embodiments, <FIG> is a side view illustrating the rotor of the motor according to embodiments, and <FIG> is a cross-sectional view illustrating the rotor of the motor according to embodiments. Here, <FIG> is a cross-sectional view taken along line A-A of <FIG>.

Referring to <FIG>, the rotor <NUM> includes a rotor portion <NUM>, a first can <NUM> disposed above the rotor portion <NUM>, and a second can <NUM> disposed below the rotor portion <NUM>. Here, a part of a rotor core <NUM> may be disposed in the first can <NUM>, and another part of the rotor core <NUM> may be disposed in the second can <NUM>.

Here, the first can <NUM> and the second can <NUM> may be formed to have the same shape. Accordingly, since the first can <NUM> and the second can <NUM> may be used in common, manufacturing costs may be minimized.

However, when the first can <NUM> and the second can <NUM> are disposed on the rotor portion <NUM>, since arrangement positions of protrusions formed on the first can <NUM> and the second can <NUM> are different, the first can <NUM> and the second can <NUM> have a difference therebetween.

<FIG> is a plan view illustrating the rotor portion disposed in the rotor of the motor according to embodiments.

Referring to <FIG>, the rotor portion <NUM> includes the rotor core <NUM> and a plurality of magnets <NUM> arranged to be spaced at preset intervals on an outer circumferential surface of the rotor core <NUM>. That is, the plurality of magnets <NUM> may be arranged to be spaced apart in a circumferential direction due to a plurality of separation spaces S. Here, the magnets <NUM> may be referred to as rotor magnets or drive magnets.

As shown in <FIG>, the separation space S may be formed between the magnets <NUM>.

The rotor core <NUM> may be implemented as a shape in which a plurality of plates having a circular thin steel plate shape are stacked or as a one cylinder shape. A hole to which the shaft <NUM> is coupled may be formed at a center C of the rotor core <NUM>.

The rotor core <NUM> may be formed to have a cylindrical shape.

The rotor core <NUM> may further include guides <NUM> which extend and protrude outward from an outer circumferential surface 311a. The guides <NUM> may be integrally formed with the rotor core <NUM>. Here, the guides <NUM> may be referred to as protrusions and correspond to guides <NUM> shown in <FIG>.

The guides <NUM> guide arrangement of the magnets <NUM>. Accordingly, each of the magnets <NUM> may be disposed between the guides <NUM>. Here, on the basis of the outer circumferential surface 311a of the rotor core <NUM>, a protruding length L of the guides <NUM> is smaller than a thickness T of the magnets <NUM>. Accordingly, the separation space S may be formed between the magnets <NUM> and be disposed outside the guide <NUM>.

Here, the separation space S is formed by at least two magnets <NUM> and one surface of the guide <NUM> as an example but is not limited thereto. For example, when the guides <NUM> are eliminated, the separation space S may be formed by at least two magnets <NUM> and the outer circumferential surface 311a of the rotor core <NUM>.

When the guides <NUM> are formed on the rotor core <NUM>, since a region to which an adhesive member is applicable increases, a fixing force of the magnets <NUM> may be increased.

However, when the guides <NUM> are formed on the rotor core <NUM>, a magnetic flux leakage may occur due to the guides <NUM>. Accordingly, performance of the motor <NUM> is degraded. Therefore, the motor <NUM> may use the rotor portion <NUM> from which the guides <NUM> are eliminated.

The magnets <NUM> may be arranged on the outer circumferential surface of the rotor core <NUM> to be spaced at preset intervals. Here, the magnets <NUM> may be attached to the outer circumferential surface of the rotor core <NUM> using the adhesive member such as glue. Here, ten magnets <NUM> are provided as an example but the number thereof is not limited thereto.

The first can <NUM> and the second can <NUM> may be formed to have a cup shape with a hole at a center and are disposed to cover an upper part and a lower part of the rotor portion <NUM>, respectively. Here, the term "can" may be designated as "cap. " Accordingly, the first can <NUM> may be referred to as a first cap and the second can <NUM> may be referred to as a second cap.

The first can <NUM> and the second can <NUM> may protect the rotor portion <NUM> from an external shock or physical and chemical stimuli and prevent foreign substances from soiling the rotor portion <NUM>.

Here, the first can <NUM> may include first protrusions <NUM> arranged in the separation spaces S each formed between the magnets <NUM>. Here, the second can <NUM> may include second protrusions <NUM> arranged in the separation spaces S each formed between the magnets <NUM>. Accordingly, the first protrusions <NUM> and the second protrusions <NUM> support the magnets <NUM> with the guides <NUM> to prevent the magnets <NUM> from moving in a rotational direction. Here, the first can <NUM> with the first protrusions <NUM> formed thereon and the second can <NUM> with the second protrusions <NUM> formed thereon may be fixed to the rotor core <NUM> using a fixing method such as welding.

The first protrusions <NUM> and the second protrusions <NUM> may be arranged to be rotationally symmetrical to each other on the basis of a center of the rotor <NUM>.

Also, as shown in <FIG>, according to the invention the separation spaces S are formed to extend from a top surface to a bottom surface of the rotor core <NUM>. Also, the first protrusions <NUM> and the second protrusions <NUM> are arranged in regions more adjacent to centers of the separation spaces S in an axial direction than both ends thereof.

Referring to <FIG>, <FIG>, and <FIG>, when viewed in the axial direction, the first protrusions <NUM> and the second protrusions <NUM> may be alternately arranged in the separation spaces S between the magnets <NUM> along the circumferential direction of the rotor core <NUM>. That is, the first protrusions <NUM> and the second protrusions <NUM> may be arranged diagonally along the circumferential direction. Accordingly, the numbers of the first protrusions <NUM> and the second protrusions <NUM> may be minimized. Here, the axial direction is a longitudinal direction of the shaft <NUM>. Here, the first protrusions <NUM> and the second protrusions <NUM> may be arranged at different heights on the basis of bottom surfaces of the magnets <NUM>. Also, distances between the first protrusions <NUM> and the second protrusions <NUM> may be mutually uniform.

As shown in <FIG>, one side of the magnet <NUM> may come into contact with the first protrusion <NUM> and the other side of the magnet <NUM> may come into contact with the second protrusion <NUM>. Accordingly, the first protrusion <NUM> and the second protrusion <NUM> may support the one side and the other side of the magnet <NUM>, respectively.

That is, the magnet <NUM> may be disposed between the first protrusion <NUM> and the second protrusion <NUM> such that movement of the magnet <NUM> in the rotational direction may be restricted.

<FIG> is a perspective view illustrating the first can disposed in the rotor of the motor according to embodiments, and <FIG> is a cross-sectional view illustrating the first can disposed in the rotor of the motor according to embodiments. Here, <FIG> is a cross-sectional view taken along line B-B' of <FIG>.

Although <FIG> illustrate the first can <NUM>, since the second can <NUM> has the same shape as that of the first can <NUM>, the second can <NUM> may be described with reference to <FIG>.

Referring to <FIG>, the first can <NUM> may include a ring-shaped first plate portion <NUM> disposed above the rotor portion <NUM>, a first protruding portion <NUM> protruding from an outer circumferential surface of the first plate portion <NUM> in the axial direction, and the first protrusions <NUM> formed on the first protruding portion <NUM>. Here, the first protrusions <NUM> may be disposed in at least two of the plurality of separation spaces S and arranged to be spaced apart.

The first plate portion <NUM> may be formed to have a ring shape in a plane view.

As shown in <FIG>, the first plate portion <NUM> may be disposed to cover a part of the rotor core <NUM>. For example, on the basis of the center C of the rotor <NUM>, a distance from an inner circumferential surface of the first plate portion <NUM> is smaller than a distance from the outer circumferential surface of the rotor core <NUM>.

Also, the first plate portion <NUM> may be fixed to the rotor core through spot welding at preset positions P. Accordingly, the first plate portion <NUM> prevents the magnets <NUM> from moving upward.

The first protruding portion <NUM> may be formed to protrude downward from the outer circumferential surface of the first plate portion. Here, the first protruding portion <NUM> may be integrally formed with the first plate portion <NUM>. For example, the first protruding portion <NUM> may be formed by bending an edge of the first plate portion <NUM>.

As shown in <FIG>, the first protruding portion <NUM> may be formed to have a cylindrical shape.

The first protruding portion <NUM> may be disposed outside the magnets <NUM>. Accordingly, the first protruding portion <NUM> prevents the magnets <NUM> from moving in the radial direction. That is, the first protruding portion <NUM> may support outer surfaces of the magnets <NUM> to correspond to a centrifugal force caused by rotation of the rotor <NUM>.

A plurality of such first protrusions <NUM> may be formed on the first protruding portion <NUM>. Also, the plurality of first protrusions <NUM> may be arranged to be spaced at certain intervals along a circumferential direction of the first protruding portion <NUM>.

Here, the first protrusions <NUM> may be arranged to be rotationally symmetrical on the basis of the center C. Also, the first protrusions <NUM> may be formed to protrude inward from an inner circumferential surface 322a of the first protruding portion <NUM>. As shown in <FIG>, the first protrusions <NUM> may be formed to have a staple shape.

Here, the first protrusions <NUM> may be formed on an end of the first protruding portion <NUM>. Here, the end of the first protruding portion <NUM> and an end of a second protruding portion <NUM> may come into contact with each other.

Referring to <FIG>, the first protrusion <NUM> may be disposed in the separation space S between the magnets <NUM>. Here, an inner surface 323a of the first protrusion <NUM> may be disposed to be spaced at a certain first distance d1 from an outer surface 312a of the guide <NUM>. When the guides <NUM> are eliminated from the rotor <NUM>, the inner surface 323a of the first protrusion <NUM> may be disposed to be spaced at the certain first distance d1 from the outer circumferential surface 311a of the rotor core <NUM>.

The first protrusions <NUM> may be formed to protrude inward from the inner circumferential surface 322a of the first protruding portion <NUM>. Accordingly, the first protrusion <NUM> may be disposed in the separation space S between the magnets <NUM>.

Referring to <FIG>, the first protrusion <NUM> may be arranged to be spaced at a certain second distance d2 from the first plate portion <NUM>.

Also, the first protrusion <NUM> may be formed by pressurizing one region of an outer circumferential surface 322b of the first protruding portion <NUM> from the outside. As shown in <FIG>, the one region of the outer circumferential surface 322b of the first protruding portion <NUM> may be bent inward. Accordingly, the first protrusion <NUM> may be referred to as a first bent portion.

When the outer circumferential surface 322b of the first protruding portion <NUM> is pressurized while the first protruding portion <NUM> is disposed outside the magnets <NUM>, the magnets <NUM> may be damaged. Accordingly, the first protrusion <NUM> may be formed by pressurizing only one region of the outer circumferential surface 322b of the first protruding portion <NUM> so as to minimize a load applied to the magnets <NUM>.

Also, the first protrusion <NUM> may be formed by pressurizing positions spaced at the certain second distance d2 from the first plate portion <NUM> so as to minimize the load applied to the magnets <NUM>.

Meanwhile, the first protrusion <NUM> is formed by pressurizing one region of the outer circumferential surface 322b of the first protruding portion <NUM> such that a groove G may be concavely formed in the outer circumferential surface 322b of the first protruding portion <NUM>. That is, the groove G may be formed in the outer circumferential surface 322b of the first protruding portion <NUM> at a position corresponding to the first protrusion <NUM>. Here, the groove G in the outer circumferential surface 322b of the first protruding portion <NUM> may be designated as a first groove G to be distinguished from a second groove G formed in an outer circumferential surface 332b of the second protruding portion <NUM>.

As shown in <FIG>, a lower side of the first groove G may communicate with the separation space S formed between the magnets <NUM>.

Also, the first protrusion <NUM> is formed by pressurizing one region of the outer circumferential surface 322b of the first protruding portion <NUM> such that a side surface 323b of the first protrusion <NUM> may be pressed against a side surface 313a of the magnet <NUM>. Here, a certain load may be applied to the magnet <NUM>.

Referring to <FIG>, the second can <NUM> may include a ring-shaped second plate portion <NUM> disposed below the rotor portion <NUM>, a second protruding portion <NUM> protruding from an outer circumferential surface of the second plate portion <NUM> in the axial direction, and the second protrusions <NUM> formed on the second protruding portion <NUM>. Here, the second protrusions <NUM> may be disposed in two other of the plurality of separation spaces S in which the first protrusions <NUM> are not disposed and may be disposed to be spaced apart.

The second plate portion <NUM> may be formed to have a ring shape in a plane view.

The second plate portion <NUM> may be disposed to cover a part of the rotor core <NUM>. For example, on the basis of the center C of the rotor <NUM>, a distance from an inner circumferential surface of the second plate portion <NUM> is smaller than a distance from the outer circumferential surface of the rotor core <NUM>.

Also, the second plate portion <NUM> may be fixed to the rotor core through spot welding at preset positions P. Accordingly, the second plate portion <NUM> prevents the magnets <NUM> from moving downward.

The second protruding portion <NUM> may be formed to protrude upward from the outer circumferential surface of the second plate portion <NUM>. Here, the second protruding portion <NUM> may be integrally formed with the second plate portion <NUM>. For example, the second protruding portion <NUM> may be formed by bending an edge of the second plate portion <NUM>.

Referring to <FIG>, the second protruding portion <NUM> may be formed to have a cylindrical shape.

The second protruding portion <NUM> may be disposed outside the magnets <NUM>. Accordingly, the second protruding portion <NUM> prevents the magnets <NUM> from moving in the radial direction. That is, the second protruding portion <NUM> may support outer surfaces of the magnets <NUM> to correspond to a centrifugal force caused by rotation of the rotor <NUM>.

A plurality of such second protrusions <NUM> may be formed on the second protruding portion <NUM>. Also, the plurality of second protrusions <NUM> may be arranged to be spaced at certain intervals along a circumferential direction of the second protruding portion <NUM>.

Here, the second protrusions <NUM> may be arranged to be rotationally symmetrical on the basis of the center C. Also, the second protrusions <NUM> may be formed to protrude inward from an inner circumferential surface 332a of the second protruding portion <NUM>. As shown in <FIG>, the second protrusions <NUM> may be formed to have a staple shape.

Here, the second protrusions <NUM> may be formed on an edge of the second protruding portion <NUM>.

Referring to <FIG>, the second protrusion <NUM> may be disposed in the separation space S between the magnets <NUM>. Here, an inner surface 333a of the second protrusion <NUM> may be disposed to be spaced at a certain first distance d1 from the outer surface 312a of the guide <NUM>. When the guides <NUM> are eliminated from the rotor <NUM>, the inner surface 333a of the second protrusion <NUM> may be disposed to be spaced at the certain first distance d1 from the outer circumferential surface 311a of the rotor core <NUM>.

The second protrusions <NUM> may be formed to protrude inward from the inner circumferential surface 332a of the second protruding portion <NUM>. Accordingly, the second protrusion <NUM> may be disposed in the separation space S between the magnets <NUM>.

Referring to <FIG>, the second protrusion <NUM> may be arranged to be spaced at a certain second distance d2 from the second plate portion <NUM>.

Also, the second protrusion <NUM> may be formed by pressurizing one region of the outer circumferential surface 332b of the second protruding portion <NUM> from the outside. The one region of the outer circumferential surface 332b of the second protruding portion <NUM> may be bent inward. Accordingly, the second protrusion <NUM> may be referred to as a second bent portion.

When the outer circumferential surface 322b of the second protruding portion <NUM> is pressurized while the second protruding portion <NUM> is disposed outside the magnets <NUM>, the magnets <NUM> may be damaged. Accordingly, the second protrusion <NUM> may be formed by pressurizing one region of the outer circumferential surface 332b of the second protruding portion <NUM> so as to minimize a load applied to the magnets <NUM>.

Also, the second protrusion <NUM> may be formed by pressurizing positions spaced at the certain second distance d2 from the second plate portion <NUM> so as to minimize the load applied to the magnets <NUM>.

Meanwhile, the second protrusion <NUM> is formed by pressurizing one region of the outer circumferential surface 332b of the second protruding portion <NUM> such that a groove G may be concavely formed in the outer circumferential surface 332b of the second protruding portion <NUM>. Here, the groove G on the outer circumferential surface 332b of the second protruding portion <NUM> may be referred to as the second groove G.

An upper side of the second groove G may communicate with the separation space S formed between the magnets <NUM>.

Also, the second protrusion <NUM> is formed by pressurizing one region of the outer circumferential surface 332b of the second protruding portion <NUM> such that a side surface 333b of the second protrusion <NUM> may be pressed against the side surface 313a of the magnet <NUM>. Here, a certain load may be applied to the magnet <NUM>.

Referring to <FIG>, the end of the first protruding portion <NUM> of the first can <NUM> and an end of the second protruding portion <NUM> of the second can <NUM> may be disposed to come into contact with each other. Also, the ends of the first can <NUM> and the second can <NUM> which are in contact with each other may be fixed using an adhesive member or welding.

The stator <NUM> may be disposed inside the housing <NUM>. Here, the stator <NUM> may be supported by an inner circumferential surface of the housing <NUM>. Also, the stator <NUM> is disposed outside the rotor <NUM>. That is, the rotor <NUM> may be disposed inside the stator <NUM>.

Referring to <FIG>, the stator <NUM> may include a stator core <NUM>, an insulator <NUM> disposed on the stator core <NUM>, and a coil <NUM> wound on the insulator <NUM>.

The coil <NUM>, which forms a rotating magnetic field, may be wound on the stator core <NUM>. Here, the stator core <NUM> may be formed as one core or formed by coupling a plurality of divided cores.

The stator core <NUM> may include a plurality of plates which have a thin steel sheet shape and are stacked on one another but is not limited thereto. For example, the stator core <NUM> may be formed as a single component.

The stator core <NUM> may include a cylindrical yoke (not shown) and a plurality of teeth (not shown) protruding from the yoke in the radial direction. Also, the coil <NUM> may be wound on the teeth.

The insulator <NUM> insulates the stator core <NUM> from the coil <NUM>. Accordingly, the insulator <NUM> may be disposed between the stator core <NUM> and the coil <NUM>.

Accordingly, the coil <NUM> may be wound on the stator core <NUM> on which the insulator <NUM> is disposed.

The shaft <NUM> may be rotatably disposed inside the housing <NUM> by the bearings <NUM>. Also, the shaft <NUM> may rotate in conjunction with the rotation of the rotor <NUM>.

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

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

The busbar <NUM> may include a busbar body (not shown) and a plurality of terminals (not shown) arranged inside the busbar body. Here, the busbar body may be a molded material formed through injection molding. Also, each of the terminals may be electrically connected to the coil <NUM> of the stator <NUM>.

The sensor portion <NUM> may sense a magnetic force of a sensing magnet installed to be rotationally coupled to the rotor and recognize a current position of the rotor <NUM> so as to sense rotation of the shaft <NUM>.

The sensor portion <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 be coupled to the rotor <NUM> and detects a position of the rotor <NUM>. Here, the sensing magnet assembly <NUM> may include a sensing magnet and a sensing plate.

The sensing magnet may include main magnets arranged in a circumferential direction to be adjacent to a hole, which forms an inner circumferential surface, and sub magnets formed on an edge. The main magnets may be arranged like drive magnets inserted into the rotor <NUM> of the motor. The sub magnets are further subdivided than the main magnets and include many poles. Accordingly, the sub magnets are able to more precisely divide and measure rotation angles and may include smoother driving of the motor.

The sensing plate may be formed of a metal material having a disc shape. The sensing magnet may be coupled to a top surface of the sensing plate. Also, the sensing plate may be coupled to the shaft <NUM>. Here, a hole, through which the shaft <NUM> passes, is formed in the sensing plate.

A sensor, which senses a magnetic force of the sensing magnet, may be disposed on the PCB <NUM>. Here, the sensor may be provided as a hall integrated circuit (IC). Also, the sensor may sense a change N pole and S pole of the sensing magnet and generate a sensing signal.

Referring to <FIG>, the motor according to other embodiments may include a shaft <NUM>, a rotor <NUM>, a stator <NUM>, and a housing <NUM>. Here, the motor according to embodiments shown in <FIG> may be referred to as a motor according to a second embodiment.

The shaft <NUM> may be coupled to the rotor <NUM>. When the rotor <NUM> rotates, the shaft <NUM> rotates in conjunction therewith.

The rotor <NUM> is coupled to the shaft <NUM>. The rotor <NUM> is disposed inside the stator <NUM>.

The stator <NUM> is disposed outside the rotor <NUM>. The stator <NUM> may include a stator core <NUM>, an insulator <NUM>, and a coil <NUM>. The insulator <NUM> is mounted on the stator core <NUM>. The coil <NUM> is wound on the insulator <NUM>.

The rotor <NUM> and the stator <NUM> may be accommodated inside the housing <NUM>.

<FIG> is a plan view illustrating the rotor, <FIG> is a partially enlarged view of the rotor, and <FIG> is a view illustrating a first part and a second part of a rotor core.

Referring to <FIG> and <FIG>, the rotor <NUM> may include a rotor core <NUM> and magnets <NUM>.

The magnets <NUM> may be disposed on an outer circumferential surface of the rotor core <NUM>. A plurality of such magnets <NUM> may be present. The rotor core <NUM> may include a plurality of guides <NUM> formed to extend outward from the outer circumferential surface of the rotor core <NUM>. Here, the guides <NUM> may be referred to as protrusions and may each be arranged in each of the separation spaces S. The plurality of guides <NUM> may be arranged to be spaced along a circumferential direction on the basis of a center of the rotor core <NUM>. Accordingly, the magnet <NUM> may be accommodated in an accommodation portion defined as a region between the plurality of guides <NUM>.

The rotor core <NUM> may include a surface <NUM> in which the magnet <NUM> is disposed. The surface <NUM> is disposed between the guides <NUM> in the circumferential direction. An inner circumferential surface of the magnet <NUM> comes into contact with the surface <NUM>.

The rotor core <NUM> is a metal material. The magnet <NUM> is attached to the surface <NUM> of the rotor core <NUM> by a magnetic force. A circumferential width of the surface <NUM> is greater than a circumferential width of the magnet <NUM>. This is to secure an assembling property of the magnets <NUM>. On the basis of the circumferential direction, positions of the magnets <NUM> have an effect on cogging torque. Accordingly, arranging the positions of the magnets <NUM> in the circumferential direction is a significant factor for improving cogging torque. Since the circumferential width of the surface <NUM> is greater than the circumferential width of the magnet <NUM>, it is necessary to push and align all the magnets <NUM> in a clockwise or counterclockwise direction between the guides <NUM>.

The motor according to embodiments easily aligns all the magnets <NUM> in the clockwise or counterclockwise direction using asymmetry of magnetic force between the magnets <NUM> and the rotor core <NUM>.

Hereinafter, adjacent guides <NUM> are referred to as a first guide 1211A and a second guide 1211B.

The rotor core <NUM> may include a first part A and a second part B. The first part A and the second part B are divided on the basis of a center of the circumferential width between the first guide 1211A and the second guide 1211B. A volume of the first part A is smaller than a volume of the second part B. A difference between the volume of the first part A and the volume of the second part B causes asymmetry of magnetic force between the magnets <NUM>. The asymmetry of the magnetic force means a difference between a magnetic force of one side and a magnetic force of the other side on the basis of the center of the circumferential width between the first guide 1211A and the second guide 1211B. A magnetic force at the first part A is relatively greater than a magnetic force at the second part B.

The circumferential width between the first guide 1211A and the second guide 1211B means a circumferential width between a first reference line L1 and a second reference line L2. The first reference line L1 is a virtual straight line which connects a boundary point P1 between the first guide 1211A and the rotor core <NUM> to a center C of the rotor core <NUM>. The second reference line L2 is a virtual straight line which connects a boundary point P1 between the second guide 1211B and the rotor core <NUM> to the center C of the rotor core <NUM>. When a virtual straight line, which connects a circumferential center of the first reference line L1 and the second reference line L2 to the center C of the rotor core <NUM> in a circumferential direction is referred to as a third reference line L3, the first part A and the second part B are distinguished by the third reference line L3. Also, the surface <NUM> may include a first surface 1212A and a second surface 1212B. The first surface 1212A and the second surface 1212B are distinguished on the basis of the third reference line L3.

A groove <NUM> may be disposed in the first surface 1212A of the first part A. Here, the groove <NUM> may be formed in the first surface 1212A of at least one of the accommodation portions. Also, the groove <NUM> may be formed to extend from a top surface to a bottom surface of the rotor core <NUM> and be disposed to be adjacent to the guide <NUM>.

The groove <NUM> is formed to be recessed from the first surface 1212A. The groove <NUM> may be disposed lengthwise along a longitudinal direction of the rotor core <NUM>. The groove <NUM> may not be disposed in the second part B but may be disposed only in the first part A. Since the volume of the first part A and the volume of the second part B differ depending on whether the groove <NUM> is present, asymmetry in magnetic force on the basis of the third reference line L3 is caused. Here, the groove <NUM> of the motor according to the second embodiment may be formed in the rotor core <NUM> of the motor <NUM> according to the first embodiment.

An adhesive may be applied between the magnet <NUM> and the surface <NUM> of the rotor core <NUM>. The groove <NUM> may be utilized as an escape space for a residual adhesive. In a process of mounting the magnet <NUM> on the surface <NUM>, it is possible to reduce a downward flow of the residual adhesive toward an end of the rotor core <NUM>.

<FIG> is a view illustrating a modified example of the rotor core.

Referring to <FIG>, as a modified example of the rotor core <NUM>, a first groove 1213A may be disposed in the first surface 1212A of the first part A, and a second groove 1213B may be disposed in the second surface 1212B of the second part B. Here, a size of the first groove 1213A may be greater than that of the second groove 1213B. For example, under a condition in which a radial thickness of the first groove 1213A is equal to a radial thickness of a second groove 1213B, a circumferential width W1 of the first groove 1213A may be greater than a circumferential width W2 of the second groove 1213B. Since the size of the first groove 1213A is greater than the size of the second groove 1213B, asymmetry in magnetic force on the basis of the third reference line L3 is caused.

<FIG> is a view illustrating another modified example of the rotor core.

Referring to <FIG>, as another modified example of the rotor core <NUM>, a plurality of such first grooves 1213A may be disposed in the first surface 1212A of the first part A, and a smaller number of the second grooves 1213B than the number of the first grooves 1213A may be disposed in the second surface 1212B of the second part B. For example, two first grooves 1213A and one second groove 1213B may be present.

Here, a sum of the sizes of all the first grooves 1213A may be greater than a sum of the sizes of all the second grooves 1213B. For example, under a condition in which the radial thickness of the first groove 1213A is equal to the radial thickness of the second groove 1213B, a sum of circumferential widths W1a and W1b of all the first grooves 1213A may be greater than a sum of the circumferential width W2 of all the second grooves 1213B. Since the sum of the sizes of all the first grooves 1213A is greater than the sum of the sizes of all the second grooves 1213B, asymmetry in magnetic force on the basis of the third reference line L3 is caused.

<FIG> is a view illustrating movement of the magnets caused by asymmetry in magnetic force.

Referring to <FIG>, a magnetic force in the second part B is relatively greater than a magnetic force in the first part A. Accordingly, in a circumferential direction, the magnet <NUM> easily moves toward the second guide 1211B. When the magnet <NUM> moves, a gap G1 occurs between the first guide 1211A and one side surface of the magnet <NUM>, and the second guide 1211B comes into contact with the other side surface of the magnet <NUM>. The above process occurs in all the magnets <NUM> mounted on the rotor core <NUM>, and positions of all the magnets <NUM> are aligned in the circumferential direction.

When the positions of all the magnets <NUM> are aligned, an advantage of improving cogging torque is present.

<FIG> is a view illustrating cogging torques in a comparative example and an embodiment.

Referring to <FIG>, the comparative example is a motor without a groove in an outer circumferential surface of a rotor core to which magnets are attached in which magnetic forces are formed to be symmetrical on the basis of a center of a circumferential width of a surface of the rotor core to which magnets are attached. The embodiment is a motor in which the groove <NUM> is formed in the first part A and is not formed in the second part B.

In the case of the comparative example, average cogging torque is <NUM> mNm. In the case of the embodiment, average cogging torque is <NUM> mNm. The embodiment provides an effect of improving cogging torque <NUM>% more than the comparative example.

In the case of the comparative example, dispersion cogging torque is <NUM> mNm. In the case of the embodiment, dispersion cogging torque is <NUM> mNm. The embodiment provides an effect of improving cogging torque <NUM>% more than the comparative example.

Although the embodiments of the present invention have been described above, it may be understood by one of ordinary skill in the art that a variety of modifications and changes may be made without departing from the concept and scope of the present invention disclosed within the range of the following claims. Also, it should be noted that differences related to the modifications and changes are included within the scope of the present invention defined by the claims.

Claim 1:
A motor comprising:
a shaft (<NUM>, <NUM>);
a rotor (<NUM>, <NUM>) coupled to the shaft (<NUM>, <NUM>); and
a stator (<NUM>, <NUM>) disposed outside the rotor (<NUM>, <NUM>),
wherein the rotor (<NUM>, <NUM>) comprises a first can (<NUM>), a rotor core (<NUM>, <NUM>) at least partially disposed in the first can (<NUM>), a plurality of magnets (<NUM>, <NUM>) coupled to the rotor core (<NUM>, <NUM>), and a second can (<NUM>) in which another part of the rotor core (<NUM>, <NUM>) is disposed,
wherein the plurality of magnets (<NUM>, <NUM>) are arranged to be spaced apart in a circumferential direction due to a plurality of separation spaces (S),
wherein the first can (<NUM>) comprises a first plate portion (<NUM>), a first protruding portion (<NUM>) formed by bending an edge of the first plate portion (<NUM>), and a plurality of first protrusions (<NUM>) disposed in at least two different separation spaces (S) of the plurality of separation spaces (S) and spaced apart,
wherein the second can (<NUM>) comprises a second plate portion (<NUM>), a second protruding portion (<NUM>) formed by bending an edge of the second plate portion (<NUM>), and a plurality of second protrusions (<NUM>) disposed in at least two different separation spaces (S) of the plurality of separation spaces (S) and spaced apart, and
wherein the first protrusions (<NUM>) and the second protrusions (<NUM>) are arranged diagonally,
characterized in that
the separation space (S) is formed to extend from a top surface to a bottom surface of the rotor core (<NUM>), and
that the first protrusion (<NUM>) and the second protrusion (<NUM>) are arranged in a region more adjacent to a center of the separation space (S) in the axial direction than to both ends of the separation space (S).