Patent Description:
The linear motor has a structure that generates thrust between a mover and a stator facing in a linear shape. The linear motor of a permanent magnet type places a permanent magnet on one of the mover and stator and applies alternating multi-phase power to the other, so that electromagnetic force acts between them to generate thrust in a certain direction.

Most conventional linear motors have a structure in which a magnetic flux from a protruding pole of an armature core passing through a permanent magnet and a magnetic core forms a magnetic closed loop and generates attractive force and repulsive force to generate thrust. So, the permanent magnet is most often placed between the protruding pole and the magnetic core and attached to the magnetic core.

<FIG> shows an open-type linear motor described in application numbers <CIT> and <CIT> filed by the inventor of the present application.

In <FIG>, the cores of the armature modules of U/V/W phases are the shape of a straight line, and accordingly, the protruding poles protrude at a right angle from the core and are arranged side by side with adjacent protruding poles. And, the permanent magnets of secondary members also protrude between two side-by-side protruding poles toward the straight core. A plurality of permanent magnets arranged in a traveling direction may be fixed to a permanent magnet module, and between the protruding poles two or more permanent magnet modules are arranged side by side with each other. So, the base for supporting serves as a connecting member for connecting a plurality of the permanent magnet modules, and a plurality of the permanent magnet modules may be fixed to the base.

The linear motor in <FIG> constitutes a magnetic closed loop without the intervention of a magnetic core. That is, there is no magnetic core on a magnetic path, and a permanent magnet is directly placed on the magnetic path to connect the magnetic flux to form a magnetic closed loop.

Since the permanent magnet directly connects the magnetic closed loop in the linear motor of <FIG>, a permanent magnet module may be assembled by inserting the permanent magnets into a plurality of openings formed according to the shape of the permanent magnets in a frame. Since a magnetic flux does not flow through the magnet module frame, the frame may be manufactured in an injection method using a non-magnetic material.

When a plurality of the permanent magnets are fixed to the openings formed in the frame, the magnetization direction of the permanent magnet is checked individually, an opening for fixing the permanent magnet whose magnetization direction is confirmed is determined, adhesive is applied to the inside of the opening or the rim of the permanent magnet, and the permanent magnet is fit through and bonded to the opening.

However, since the magnetic force of the permanent magnet is very strong, two magnets may stick together and it is very difficult to separate the two stuck magnets, the process of checking the magnetization direction is quite cumbersome. The adhesive applied to the inside of the opening or the rim of the permanent magnet will come out, so the assembled magnetic module will not have a smooth appearance. Thus, there are many work processes involved in assembling the magnet module, which is cumbersome and reduces work efficiency.

Further examples of background art can be found in <CIT>, <CIT>, <CIT>.

The present disclosure has been made in view of the above circumstances. It is an object of the present disclosure to a magnet module which can be easily manufactured and which is composed of a plurality of magnets arranged in a traveling direction of a linear motor and having no magnetic core.

The magnet module according to claim <NUM> comprises: a plurality of permanent magnets arranged in a straight line along a first direction, magnet polarity directions of the plurality of permanent magnets which are parallel to a second direction being alternatively arranged in the first direction; an injection molded frame to fix the plurality of permanent magnets; and an injection molded base in which a plurality of base holes are formed.

In an embodiment, the magnet module may further comprise a metal plate inserted into the base.

In an embodiment, the metal plate may have a shape that is longest in the first direction and a next longest in the second direction, and have holes formed at positions corresponding to the plurality of base holes.

In an embodiment, the base hole may be disposed at a position corresponding to a position between two adjacent permanent magnets in the frame, based on the first direction.

In an embodiment, the permanent magnet may be exposed to the outside, and the frame may protrude from a surface of the permanent magnet having a shape of a hexahedron in a direction away from the permanent magnet along the second direction at positions corresponding to edges of the permanent magnet, and protrude from the positions corresponding to the edges toward a center of the permanent magnet along the first direction and a third direction perpendicular to the first and second directions.

Therefore, the manufacturing process of the magnet module is simplified to increase manufacturing efficiency. Also, the structure is possible in which the magnets in the magnet module are not exposed to the outside, so the surfaces of the magnets can be prevented from being damaged.

In addition, it is possible to prevent the magnetic module having a long length in a traveling direction from being bending in a direction in which a magnet flux advances. By minimizing the gap between the magnet and armatures, it is possible to minimize leakage of the magnetic flux to the outside.

Also, it is possible to prevent the magnet from separating from the frame of the magnet module even if the magnet is injected while exposed to the outside.

Hereinafter, a method of manufacturing a magnet module according to the present disclosure will be described in detail with reference to the accompanying drawings.

In the present disclosure, the magnet module including a plurality of magnets that are not magnetized are injection molded and the magnets mounted on the magnet module may be magnetized with a magnetizer, so the magnet module applied to a linear motor having a structure similar to <FIG> may be manufactured.

<FIG> shows a magnet module manufactured by an injection molding method according to an embodiment of the present disclosure, and <FIG> shows a frame to which permanent magnets are fixed in the magnet module of <FIG>. Two or more magnet modules may be continuously arranged in a traveling direction of a mover.

The magnet module <NUM> may comprise a frame <NUM> on which a plurality of permanent magnets <NUM> are mounted and a base <NUM> on which holes <NUM> for engaging the based to a stator. The frame <NUM> and the base <NUM> may be formed in one body by injection molding. For example, a plurality of permanent magnets 130N and <NUM> are disposed in the frame <NUM> which is made of an injection material such as plastic, while their magnetic poles being alternated along a traverse direction (X direction), that is, the moving direction of a mover. And, the magnet module <NUM> may be manufactured such that the permanent magnets in the magnet module <NUM> are not exposed to the outside.

The plurality of cuboid permanent magnets are arranged in a slightly inclined state, in which the sides of the cuboid are not aligned parallel to the transverse direction (X direction) to reduce velocity ripple. The magnetization direction of the permanent magnets <NUM> is perpendicular to a traveling direction of a mover, and is a direction protruding or entering an XY plane, that is, a direction perpendicular to the XY plane.

<FIG> shows an operation flow chart for the process of manufacturing the magnet module according to an embodiment of the present disclosure.

First, magnetless magnets are mounted on a mold frame for injection molding. The magnetless or non-magnetic magnet means a magnet without magnetic force, and means a state in which a material required for a magnet is compounded to the magnet but no magnetic force is injected to the material. Since magnets are magnetless, magnetless magnets of a same size may be arbitrarily mounted on the mold frame without needing to consider their magnetization directions.

<FIG> illustrate a method of fixing magnetless magnets to a mold frame to manufacture the magnet module by injection molding.

A mold frame may be composed of at least two parts, that is a first mold frame and a second mold frame the inside of which are molded to fit the external shape of the magnet module <NUM>. Fixing pins <NUM>, <NUM> and <NUM> are formed inside the mold frame in a state protruding from the inner surface. The fixing pins are for fixing the magnetless magnets <NUM> in their proper places when high temperature liquid resin such as plastic is injected at a high pressure into the space between the first mold frame <NUM> and the second mold frame <NUM> during an injection molding process.

In <FIG>, first fixing pins <NUM> protrude vertically from an inner surface of the first mold frame <NUM> to support a magnet <NUM> in -Z direction, second fixing pins <NUM> protrude vertically from an inner surface of the second mold frame <NUM> to support the magnet <NUM> in +Z direction, and third fixing pins <NUM> protrude vertically from at least one of the first and second mold frames <NUM> and <NUM> to supports the magnet <NUM> in X direction, Y direction or a combination direction of a predetermined ratio of the X direction component and the Y direction component.

The magnetless magnet <NUM> is in the form of a cuboid, and is mounted on the inside of the frame <NUM> in a state in which first/second surfaces having the largest area (the first and second surfaces face each other or are parallel with each other) are parallel to the XY plane. Since a magnetic flux flows in the Z direction when the magnet module <NUM> is mounted on the linear motor of the structure of <FIG>, it is necessary for the first surface of the magnet <NUM> to remain parallel to the XY plane or perpendicular to the Z direction.

For this, as shown in <FIG>, it is advantageous to dispose the first and second fixing pins <NUM> and <NUM> such that three or more ends of respective first and second fixing pins <NUM> and <NUM> contact the first and second surfaces of the magnet <NUM> with respect to the Z direction, the center of gravity of the plurality of first fixing pins <NUM> and the center of gravity of the plurality of second fixing pins <NUM> are respectively disposed in the center of the first or second surface of the magnet <NUM> with respect to the XY plane, and the first and second fixing pins <NUM> and <NUM> are evenly disposed on the first or second surface.

Also, as shown in <FIG>, the first and second fixing pins <NUM> and <NUM> may be arranged such that the first positions of the first fixing pins <NUM> and the second positions of the second fixing pins <NUM> are not identical to each other with respect to the XY plane, and the first positions and the second positions are point-symmetrical relative to the center of the first or second surface or symmetrical based on a straight line passing through the center of the first or second surface.

As shown in <FIG>, when the magnet <NUM> is a rectangle having a longer side with respect to the XY plane, three first fixing pins <NUM> and three second fixing pins <NUM> are disposed for each magnet <NUM> such that the first fixing pins or the second fixing pins are respectively arranged in the shape of an isosceles triangle with a hypotenuse being longer than a base and the first isosceles triangle formed by the first fixing pins <NUM> and the second isosceles triangle formed by the second fixing pins <NUM> are alternately arranged each other.

As shown in <FIG>, the plurality of third fixing pins <NUM> are arranged to contact each side of a rectangle formed by the first or second surface of each magnet <NUM> with respect to the XY plane or disposed to contact one or more surfaces other than the first and second surfaces.

The magnet <NUM> may not be a cuboid and may be a hexahedron in which the first/second surfaces of the XY plane are parallelograms. The embodiments related to the fixing pins of <FIG> may be applied to this case without modification. And, the planar shape of the magnet <NUM> is not limited to a rectangular shape or a parallelogram shape, and may be a rhombus, a circular shape, an ellipse, and the like.

After attaching the magnetless magnet <NUM> to one of the first and second mold frames <NUM> and <NUM>, the two mold frames <NUM> and <NUM> are combined. An inlet (not shown) for injecting a resin in a liquid state constituting the frame <NUM> and the base <NUM> is provided on one of the first and second mold frames <NUM> and <NUM> or a combined cross-section of the two mold frames. Also, an air hole (not shown) through which the air inside of the two mold frames is to be escaped is provided so that the resin penetrates into every corner of the inside of the two mold frames.

After combining the first and second mold frames <NUM> and <NUM> in a state in which the magnetless magnets <NUM> are fixed, the frame <NUM> and the base <NUM> of the magnet module <NUM> are molded by injecting a resin material in a high temperature liquid state through the inlet provided on the two mold frames.

When the resin material cools and becomes a solid state, the mold frames <NUM> and <NUM> are separated to obtain the magnet module <NUM> having a plurality of magnetless magnets <NUM> mounted therein. The unnecessary portion of the magnet module <NUM> is removed and trimmed to a final appearance.

Thereafter, the magnetless magnets <NUM> embedded in the frame <NUM> are magnetized using a magnetizer.

<FIG> shows an example of a method for magnetizing magnetless magnets included in the frame of the magnet module.

Magnetization is a process of applying an induced magnetic field to a magnetic material which has no magnet force to make a magnetic change to the magnetic material. The direction and intensity of the magnetic polarity of the product to be obtained is determined and a magnetic flux is applied as much as desired to obtain the magnetized magnet called as a permanent magnet. The magnetization operation works with the magnetizer comprising a control unit, which is a current supply device, and a yoke unit that induces a magnetic field.

In <FIG>, since each magnet <NUM> included in the frame <NUM> must be magnetized so that a magnetic polarity occurs in the Z direction, the magnetic core <NUM> the end of which has a shape corresponding to the magnet <NUM> included in the frame <NUM> is disposed to face one side of each magnet <NUM>, and a ferromagnetic body <NUM> electrically connected to a corresponding magnetic body core <NUM> and having the end the shape of which corresponds to the magnet <NUM> is disposed on the opposite side of each magnet <NUM>. Ae coil <NUM> is wound around the magnetic core <NUM> and a current is applied to the coil <NUM> to expose the magnet <NUM> to the magnetic field.

That is, one end of the magnetic core <NUM> faces the first surface of the magnet <NUM> in parallel and the ferromagnetic body <NUM> faces the second surface of the magnet <NUM> in parallel so that the magnetic core <NUM>, the ferromagnetic body <NUM>, and the magnet <NUM> form a magnetic closed circuit. A current flows through the coil <NUM> wound around the magnetic core <NUM> so that the flux flows through the magnetic closed circuit. A magnetic flux Flux exits from one end of the magnetic core <NUM> toward the magnet <NUM>, passes through the magnet <NUM> and enters the ferromagnetic body <NUM>, whereby the magnet <NUM> is magnetized.

The directions in which the coils <NUM> are wound in two adjacent magnetic cores <NUM> are reversed to each other. For example, the coil <NUM> is wound in a clockwise CW in a first magnetic core <NUM>, and the coil <NUM> is wound in a counterclockwise CCW in a neighboring second magnetic core <NUM>, so the directions of the magnetic poles of two neighboring magnets <NUM> may be reversed. in the frame <NUM>.

As many magnet cores <NUM> as the number of magnets <NUM> included in the frame <NUM> are provided in the magnetizer, so all the magnets <NUM> included in the frame <NUM> can be magnetized at one time.

Therefore, it is possible to reduce the effort of assembling the magnet module frame while checking the magnetic pole directions of the permanent magnets one by one. Also, when fixing the permanent magnet to the opening of the magnet module frame, it is possible to prevent the inconvenience caused by the adhesive operation and prevent the adhesive from smearing and being dirty. In addition, the surface of the magnet is prevented from being damaged because the magnet is not exposed to the outside. Of course, depending on the intended use, some or all of the magnet surface may be exposed.

<FIG> shows a magnet module manufactured by an injection molding method according to another embodiment of the present disclosure, and <FIG> shows a metal plate inserted into the base of the magnet module. The magnet module <NUM> of <FIG> is almost the same as the magnet module <NUM> of <FIG> except that the metal plate <NUM> is inserted into the base <NUM> and the magnets <NUM> are exposed to the outside.

Because the length of the magnet module <NUM> is long in the traveling direction of the linear motor (X direction in <FIG>) and the density of the resins constituting the frame <NUM> in the direction and the density of the magnets <NUM> fitted in the frame <NUM> are different from each other, there is a possibility that bending occurs in the Z direction after injection molding.

To solve this problem, in another embodiment of the present disclosure, the magnet module <NUM> is injection molded while the metal plate <NUM> is inserted into the base <NUM> fixed to a stator. A rectangular parallelepiped metal plate <NUM> that is the longest in the X direction, forms a rectangular plane in the X and Z directions, and has a thin thickness in the Y direction is fixed inside of the based <NUM>, so the magnet module <NUM> can be prevented from bending. The metal plate may have a hexahedral shape forming a parallelogram plane in the X and Y directions.

In the metal plate <NUM>, a plurality of metal plate holes <NUM> as many as the plurality of base holes <NUM> are formed in the same positions as the plurality of base holes <NUM> formed in the base <NUM>. The base hole <NUM> may be formed at a position in the base <NUM> corresponding to the position which is located between two adjacent magnets <NUM> in the frame <NUM> based on the X direction that is the traveling direction and at which the resin forming the frame <NUM> is formed long in the Y direction, This is because the position where the magnet <NUM> is disposed in the frame <NUM> has the weakest strength.

<FIG> shows an embodiment in which a magnetless magnet and a metal plate are fixed to a mold frame in order to manufacture a magnet module by injection molding. <FIG> is a cross-sectional view of the magnet module <NUM> and the mold frames cut out based on the YZ plane in <FIG>.

In at least two parts molded inside to fit the external shape of the magnet module <NUM>, that is in the mold frame constituted by the first mold frame <NUM> and the second mold frame <NUM>, the third fixing pins <NUM> are formed to protrude from the inner surface of the first frame <NUM> or the second frame <NUM>.

Since the magnets <NUM> of the magnet module <NUM> in <FIG> are exposed to the outside unlike the <FIG>, the first fixing pins <NUM> for fixing the magnet <NUM> in the Z direction or the second fixing pins <NUM> is not required. Instead, the first mold frame <NUM> and the second mold frame <NUM> are provided with cross sections corresponding to the first/second surfaces of the magnet <NUM> to fix the magnet <NUM> in the Z direction.

Referring to <FIG>, a plurality of third fixing pins <NUM> may be disposed to contact one or more sides of the right-angled rectangle formed by the first or second surface of each magnet <NUM> with respect to the XY plane or other surfaces except the first and second surfaces, in order to fix the magnet <NUM> in the X and Y directions.

In the first mold frame <NUM> and the second mold frame <NUM>, resin accommodating portions <NUM> may be formed on at least one or both of them (in the center of the cross section) among the cross sections for fixing the magnet <NUM> in the Z direction. When the amount of the resin injected from the outside is more than necessary, it may be accommodated in the resin accommodating portions <NUM> so that there is no abnormality in the shape of the magnet module <NUM>. Since the resin that has entered the resin accommodating part <NUM> is separated from the part forming the frame <NUM> and is hardened in the center of the magnet <NUM>, the resin entering the resin accommodating part <NUM> does not form a part of the frame <NUM> and is separated from the magnet <NUM> when the first mold frame <NUM> and the second mold frame <NUM> are separated.

Since the magnet <NUM> is exposed to the outside in the magnet module <NUM> of <FIG>, there is a possibility that the magnet <NUM> is separated from the frame <NUM>. To prevent this, depressions <NUM> and <NUM> may be provided at positions corresponding to the corners or edges of the magnet <NUM> in the first mold frame <NUM> and the second mold frame <NUM>. Then, the injected frame <NUM> protrudes from the surface of the magnet <NUM> in a direction away from the magnet <NUM> (that is in the Z direction) at the edges of the magnet <NUM>, and protrudes from the edge off the magnet <NUM> in the XY direction toward the center of the magnet <NUM>, thereby preventing the magnet <NUM> from deviating from the frame <NUM>.

Meanwhile, since the metal plate <NUM> is built in the base <NUM> of the magnet module <NUM> of <FIG>, portions for fixing the position of the metal plate <NUM> and forming holes in the base <NUM> may be provided in the first mold frame <NUM> and the second mold frame <NUM>.

A plurality of protrusions <NUM> and <NUM> protruding toward each other in the Y direction are provided in the X direction in the first mold frame <NUM> and the second mold frame <NUM>, thereby forming a plurality of base holes <NUM> in the X direction in the base <NUM>. The ends of the protrusions <NUM> and <NUM> of the first mold frame <NUM> and the second mold frame <NUM> do not contact each other, and the ends of the protrusions <NUM> and <NUM> may determine a position of the metal plate <NUM> in the Y direction.

The metal plate <NUM> is also formed with a metal plate holes <NUM> in the positions corresponding to the protrusions <NUM> and <NUM>, so that the magnet module <NUM> may be fixed to a stator (or a mover) by passing bolts through the base holes <NUM> and the metal plate holes <NUM>.

In the second mold frame <NUM>, a plurality of metal plate support portions <NUM> may be formed spaced apart from each other in the X direction, thereby determining the position of the metal plate <NUM> in the Z direction inside the base <NUM>. Also, support portions may be formed on both sides in the X direction to determine the position of the metal plate <NUM> in the X direction.

In the first mold frame <NUM>, an injection unit <NUM> for injecting a resin forming the appearance of the magnet module <NUM> may be formed at a position corresponding to the base <NUM>.

In this way, by embedding the metal plate <NUM> in the base <NUM> of the magnet module <NUM>, it is possible to prevent the magnet module <NUM> having a long length in the X direction from bending in the Z direction. that is, in the direction in which the magnetic flux of the magnet <NUM> proceeds.

In addition, by exposing the magnet <NUM> to the outside of the frame <NUM>, it is possible to minimize the gap between the magnet <NUM> and the armature, thereby minimizing leakage of the magnetic flux to the outside.

Claim 1:
A magnet module (<NUM>), comprising:
a plurality of permanent magnets (<NUM>) arranged in a straight line along a first direction (X), magnet polarity directions of the plurality of permanent magnets (<NUM>) which are parallel to a second direction (Z) being alternatively arranged in the first direction (X);
an injection molded frame (<NUM>) to fix the plurality of permanent magnets;
a base (<NUM>) in which a plurality of base holes (<NUM>) are formed, characterized in that the base is an injection molded base.