Method of manufacturing rotor, rotor, and motor

A method of manufacturing a rotor includes forming plates each including a scrap portion that has a center hole and core plate portions that are disposed continuously with the scrap portion on an inner side of the center hole and that each defines a portion of a corresponding one of the outer cores forming a multilayer body including the outer cores by stacking the plates, setting at least a portion of the multilayer body and a portion of the inner core in a mold with a gap therebetween in the radial direction, forming a molded body by pouring a molten filling material into a gap in the mold and forming the filling section, at least a portion of the filling section being positioned between the outer cores, and separating the scrap portion and the core plate portions from each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a method of manufacturing a rotor, the rotor, and a motor.

2. Description of the Related Art

Hitherto, a motor including a spoke-type rotor has been known.

Among motors such as that described above, there are those in which a plurality of fit-in-type small teeth are fixed by being integrally molded by using a resin. However, in this case, it is necessary to pour the resin into a mold while holding the fit-in-type small teeth by, for example, the mold or a jig. Therefore, workability is poor and it may become more troublesome to manufacture the rotor.

SUMMARY OF THE INVENTION

An exemplary method of manufacturing a rotor of the present disclosure is a method of manufacturing a rotor including a cylindrical inner core that is disposed along a center axis, a plurality of outer cores that are disposed side by side in a peripheral direction on an outer side of the inner core in a radial direction, and a filling section that covers at least a portion of the inner core and at least a portion of each of the plurality of outer cores. The method includes forming plates each including a scrap portion that has a center hole extending therethrough in an axial direction and core plate portions that are disposed continuously with the scrap portion on an inner side of the center hole and that each defines a portion of a corresponding one of the outer cores; forming a multilayer body including the outer cores by stacking the plates; setting at least a portion of the multilayer body and a portion of the inner core in a mold with a gap therebetween in the radial direction; forming a molded body by pouring a molten filling material into a gap in the mold and forming the filling section, at least a portion of the filling section being positioned between the outer cores; and separating the scrap portion and the core plate portions from each other.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Motors according to exemplary embodiments of the present disclosure are described below with reference to the drawings. Note that the scope of the present disclosure is not limited to the embodiments below and can be optionally changed within the scope of the technical idea of the present disclosure. In the drawings below, in order to simplify each structure, for example, the scale of each structure and the number of structures may differ from the scale of each actual structure and the number of actual structures.

In the drawings, an XYZ coordinate system is shown as a three-dimensional orthogonal coordinate system as appropriate. In the XYZ coordinate system, a Z-axis direction is a direction parallel to an axial direction of a center axis C1shown inFIG. 1. A Y-axis direction is a direction that is orthogonal to the Z-axis direction. An X-axis direction is a direction orthogonal to both the Y-axis direction and the Z-axis direction.

In the state shown inFIG. 1, in the Z axis, an upper side is a positive side (+Z side) and a lower side is a negative side (−Z side). In addition, the positive side (+Z side) in the Z-axis direction is called a “first side”, and the negative side (−Z side) in the Z-axis direction is called a “second side”. Note that “first side” and “second side” are names merely used for explanation and do not limit the actual positional relationships and directions. Unless otherwise particularly indicated, the direction (Z-axis direction) parallel to the center axis C1is simply called the “axial direction”, a radial direction around the center axis C1as the center is simply called a “radial direction”, and a direction along an arc around the center axis C1as the center, that is, a peripheral direction around the center axis C1is simply called a “peripheral direction”.

A general structure of a motor according to an exemplary first embodiment of the present disclosure is described.FIG. 1is a sectional view of the motor.

As shown inFIG. 1, a motor A includes a rotor1, a stator2, a housing3, a first bearing41, and a second bearing42. The motor A also includes a sensor unit5that detects a rotational position of the rotor1.

The housing3has a cylindrical shape extending in the axial direction. The stator2is fixed to an inner peripheral surface of the housing3. By fixing the stator2inward of the housing, the center axis of the stator2matches the center axis of the housing3(the center axis C1).

The stator2surrounds an outer side of the rotor1in the radial direction. The center axis of the stator2and the center axis of the rotor1match (the center axis C1). The stator2includes a stator core21and coils22. The stator2includes the plurality of the coils22facing the rotor1.

The coils22are formed by winding conducting wires around an outer periphery of an insulator (not shown) that covers an outer surface of the stator core21. An end portion of each conducting wire extends from each coil22, and the end portion of each conducting wire extends from an end portion of the stator2on the first side in the axial direction towards the first side in the axial direction. By supplying electric power to the coils22via the conducting wires, the stator2is excited. For example, the coils22of the motor A are divided into three phases (U, V, W). In addition, for the phases, electric currents having sinusoidal waveforms that are out of phase are supplied. Therefore, the number of conducting wires that allow electric currents to be supplied for the three phases is provided. In the embodiment, there are two sets of three phases.

A shaft11(described later) of the rotor1is rotatably supported by the first bearing41, and the second side of the shaft11is rotatably supported by the second bearing42. That is, the rotor1is rotatably supported by the first bearing41and the second bearing42.

Here, the first bearing41and the second bearing42are ball bearings. The shaft11is rotatably supported by the housing3with the first bearing41and the second bearing42interposed therebetween. Here, the center axis of the shaft11matches the center axis C1of the housing3.

FIG. 2is a perspective view of the rotor.FIG. 3is a sectional view of the rotor shown inFIG. 2cut by a plane orthogonal to the center axis.FIG. 4is a plan view of an outer core as seen in the axial direction. As shown inFIG. 2, the rotor1is a so-called spoke-type rotor. The rotor1includes the shaft11and a rotor core12. The rotor1is rotatable relative to the center axis C1as the center with respect to the stator2.

The shaft11has a columnar or substantially columnar shape extending in the axial direction (the Z-axis direction). The shaft11is rotatably supported by the housing3with the first bearing41and the second bearing42interposed therebetween. This allows the rotor1to be rotatable with respect to the stator2around the center axis C1as the center. The shaft11is fixed to the rotor core12by press-fitting. Note that the fixing of the shaft11and the rotor core12to each other is not limited to press-fitting. Methods that allow the shaft11and the rotor core12to be fixed to each other can be widely used.

As shown inFIG. 2, the rotor core12includes an inner core13, a plurality of outer cores14, a filling section15, and a plurality of permanent magnets16. In the explanation below, the “inner core” and the “outer cores” refer to the “inner core of the rotor core” and the “outer cores of the rotor core”. The rotor core12is formed by, for example, a molding operation in which the inner core13and the plurality of outer cores14are disposed in a mold and a resin or a nonmagnetic material is poured into the mold.

The inner core13has a cylindrical or substantially cylindrical shape placed along the center axis C1. The shaft11is press-fitted to the inside of the inner core13. Therefore, the inner core13is made of a material that allows the shaft11to be press-fitted. The inner core13may be made of the same material as the outer cores14. The inner core13has a grooved portion131in an outer peripheral surface thereof so as to be recessed inward in the radial direction (FIG. 1). The grooved portion131extends in the axial direction. One grooved portion131or a plurality of grooved portions131may be disposed in the peripheral direction. The grooved portion131is formed by, for example, a staking operation.

The plurality of outer cores14are disposed side by side in the peripheral direction on an outer side of the inner core13in the radial direction. The filling section15covers at least a part of the inner core13and at least a part of each outer core14.

As shown inFIG. 3, the plurality of outer cores14are disposed apart from each other in the peripheral direction on an outer side of the shaft11in the radial direction. The plurality of permanent magnets16are each disposed between adjacent outer cores14. The outer cores14are excited by the permanent magnets16. That is, the rotor core12includes the plurality of permanent magnets16that excite at least the outer cores14.

The magnetic poles of the plurality of outer cores14excited by the permanent magnets16differ from those of outer cores14adjacent thereto. For example, an outer core14that is adjacent to an outer core14that is excited to be an N pole is excited to be an S pole. That is, in the rotor core12, the outer cores14that are excited to be the N pole and the outer cores14that are excited to be the S pole are alternately disposed.

As shown inFIG. 3, each outer core14has in cross section a fan or substantially fan shape whose size in the peripheral direction increases from an inner side in the radial direction to an outer side in the radial direction. Corners of each outer core14on the outer side in the radial direction are such that, for example, both sides in the peripheral direction are chamfered. The chamfering of the corners of the outer cores14may be corner chamfering or round chamfering. In the example shown inFIG. 3, the corners of the outer cores14on the outer side in the radial direction are corner-chamfered.

As shown inFIG. 1, each outer core14includes a plurality of core plate portions17that are stacked upon each other in the axial direction. The core plate portions17are electromagnetic steel plates, which are a type of magnetic material.

As shown inFIG. 4, each core plate portion17includes a connecting recessed portion171, which is a recessed portion recessed inward in the radial direction. Therefore, it is easy to use the method of manufacturing the rotor1described below. By stacking the core plate portions17, the connecting recessed portion171of each core plate portion17is stacked. Consequently, as shown inFIGS. 3 and 4, each core recessed groove141extending in the axial direction is disposed in an outer end of its corresponding outer core14in the radial direction.

As shown inFIG. 4, each core plate portion17includes a core-plate-portion through hole172extending through the core plate portion17in the axial direction. The shape of each core-plate-portion through hole172in plan view is circular. Note that the shape of each core-plate-portion through hole172in plan view is not particularly limited and may be elliptical or substantially elliptical, or polygonal or substantially polygonal.

As shown inFIG. 1, the outer cores14include an outer-core through hole142extending through the outer cores14in the axial direction. The outer-core through hole142is formed by connecting the plurality of core-plate-portion through holes172in the axial direction. A part of the filling section15is disposed at the outer-core through hole142. That is, the core plate portions17are fixed to each other by the filling section15disposed inside the outer-core through hole142.

As shown inFIG. 3, the filling section15is disposed on the outer side of the inner core13in the radial direction. In the embodiment, the filling section15is fixed to an outer peripheral surface of the inner core13. More specifically, the filling section15is fixed to a portion of the outer peripheral surface of the inner core13where the grooved portion131is provided. In other words, the grooved portion131is positioned where it contacts the filling section15.

At least a part of the filling section15is positioned between the plurality of outer cores14. The filling section15covers at least a part of each of the plurality of outer cores14. In the embodiment, the filling section15is made of a resin. Note that the material of the filling section15is not limited to resin, so that, for example, a nonmagnetic material may be used. Examples of the nonmagnetic material include aluminum and stainless steel. In the embodiment, the filling section15holds the plurality of outer cores14.

Note that, in the description, “at least a part of the filling section is positioned between the plurality of outer cores14” implies that “at least a part of the filling section is positioned on a line connecting any two outer cores of the plurality of outer cores”. The any two outer cores of the plurality of outer cores are not particularly limited and may be two outer cores adjacent to each other in the peripheral direction or two outer cores14facing each other in the radial direction with the inner core13interposed therebetween. InFIG. 3, a part of the filling section15is positioned between outer cores14that are adjacent to each other in the peripheral direction.

As shown inFIG. 2, the filling section15includes cover portions151, one covering the first side and the other covering the second side of each outer core14in the axial direction. The shape of each cover portion151in plan view is a disc or substantially disc shape through whose center the center axis C1passes. The cover portion151that covers the first side of the filling section15in the axial direction has a plurality of magnet insertion holes152in which the permanent magnets16are inserted. The plurality of magnet insertion holes152are disposed between the plurality of outer cores14in the peripheral direction.

As shown inFIG. 3, the permanent magnets16excite the outer cores14. Each permanent magnet16has a rectangular parallelepiped or substantially rectangular parallelepiped shape extending in the radial direction. Each permanent magnet16includes two magnetic poles that are disposed in the peripheral direction. The same poles of the permanent magnets16that are adjacent to each other in the peripheral direction face each other in the peripheral direction. Therefore, the outer cores14disposed between permanent magnets16whose north poles face each other are excited to be N poles. In contrast, the outer cores14disposed between permanent magnets16whose S poles face each other are excited to be S poles.

As shown inFIG. 1, the sensor unit5includes a sensor yoke51, a sensor magnet52, a sensor cover53, and rotation sensors54. The sensor yoke51is a substantially cylindrical member. The sensor yoke51is made of a magnetic material. The sensor yoke51includes a cylindrical inner wall portion511, a cylindrical outer wall portion512, and a top plate portion513. In the embodiment, the inner wall portion511and the outer wall portion512each have a cylindrical or substantially cylindrical shape. The sensor yoke51is such that an inner surface of the inner wall portion511is fixed to an outer peripheral surface of the shaft11. This causes the sensor yoke51to be fixed to the shaft11.

As shown inFIG. 1, the outer wall portion512is positioned on an outer side of the inner wall portion511in the radial direction and surrounds the inner wall portion511in the peripheral direction. That is, the sensor yoke51has a double cylindrical or substantially cylindrical shape. The top plate portion513has a ring or substantially ring shape that connects an upper end portion of the inner wall portion511and an upper end portion of the outer wall portion512.

The sensor magnet52has a ring or substantially ring shape. The sensor magnet52is held by the sensor yoke51. For example, the sensor magnet52is fitted to the outer wall portion512from an outer side in the radial direction. Therefore, the sensor magnet52is indirectly fixed to the shaft11with the sensor yoke51interposed therebetween. Note that the sensor magnet52may be directly fixed to the shaft11.

Each rotation sensor54faces the sensor magnet52in the radial direction with a gap therebetween. Each rotation sensor54is, for example, a Hall IC, and the plurality of the rotation sensors54are provided. The rotation sensors54detect changes in magnetic flux of the sensor magnet52. On the basis of the detected changes in the magnetic flux, the rotational position of the rotor1is calculated in, for example, a control device (not shown) that controls the motor A. Note that the rotation sensors54may face the sensor magnet52in the axial direction with a gap therebetween. Note that, in the embodiment, although sensors using Hall ICs may be used, the rotation sensors54are not limited thereto. For example, sensors that are capable of detecting rotation of the rotor, such as resolvers, may be widely used.

The method of manufacturing the rotor described above is described with reference to the drawings.FIG. 5is a flowchart showing the method of manufacturing the rotor of the exemplary first embodiment of the present disclosure.FIG. 6is a plan view of a plate member.FIGS. 7 to 17each show a part of a corresponding step in the method of manufacturing the rotor shown inFIG. 5.

As shown inFIG. 5, the method of manufacturing the rotor of the embodiment includes a plate member forming step S10, a stacking step S20, a mold setting step S30, a molded body forming step S40, a separating step S50, a magnet mounting step S51, and a shaft mounting step S60. Note that, in the method of manufacturing the rotor of the embodiment, the steps from the plate member forming step S10to the magnet mounting step S51are manufacturing steps of the rotor core12.

The plate member forming step S10is a step of forming a plate member6shown inFIG. 6. The plate member6is a member having a plate-like or substantially plate-like shape. The shape of the plate member6in plan view is a square or substantially square shape. In plan view, the four corners of the plate member6are chamfered. The plate member6includes a scrap portion61and a plurality of core plate portions17. The scrap portion61has a ring or substantially ring shape having a center hole60extending therethrough in the axial direction.

Note that, in the description, “a certain member has a ring or substantially ring shape” implies a case in which “a certain member has a shape that is continuous along one entire circuit therearound”. That is, examples of the ring or substantially ring shape include a circular ring or substantially ring shape, an elliptical ring or substantially elliptical ring shape, a square ring or substantially square ring shape, and a rectangular ring or substantially rectangular ring shape. “A certain member has a ring or substantially ring shape” implies a case in which a certain member has a shape that is continuous along one entire circuit therearound, or a case in which a certain member has a shape that is discontinuous in a portion of one circuit therearound.

The scrap portion61includes extending portions62, connecting protruding portions63, and fixing portions64. The scrap portion61is a ring-shaped or substantially ring-shaped portion that defines the center hole60. Each extending portion62extends inward in the radial direction from an inner edge of the center hole60. Each extending portion62includes the connecting protruding portion63on an end portion on an inner side thereof in the axial direction. Each extending portion62is connected to the scrap portion61and extends in the radial direction.

InFIG. 6, each connecting protruding portion63is a protruding portion that protrudes inward in the radial direction. More specifically, each connecting protruding portion63is a protruding portion that protrudes inward in the radial direction from an end of each extending portion62on an inner side in the radial direction. The shape of each connecting protruding portion63in plan view is a rectangular or substantially rectangular shape. The shape of each connecting protruding portion63is a shape in accordance with the shape of the connecting recessed portion171of its corresponding core plate portion17.

In the plate member6, the core plate portions17are disposed continuously with the scrap portion61on an inner side of the scrap portion61in the radial direction. By fitting the connecting recessed portions171of the core plate portions17to the connecting protruding portions63, the core plate portions17are connected to the scrap portion61. As described above, each connecting recessed portion171may have a portion whose peripheral-direction size is larger than that of a radial-direction outer end of each connecting recessed portion171, on an inner side of the radial-direction outer end in the radial direction. Such a shape allows radial-direction movement of the connecting recessed portions171fitted to the connecting protruding portions63to be suppressed. Therefore, it is possible to suppress movement and removal in the radial direction of the core plate portions17with respect to the scrap portion61. When the core plate portions17move in the axial direction with the connecting portions as fulcra, an inner end surface of each connecting protruding portion63in the radial direction and an outer end surface of each connecting recessed portion171in the radial direction interfere with each other to suppress movement of the core plate portions17in the axial direction. Therefore, it is possible to suppress movement of the core plate portions17in the axial direction and removal of the core plate portions17from the scrap portion61.

As described above, an inner side surface of each connecting recessed portion171is inclined in the peripheral direction such that the size of each connecting recessed portion171in the peripheral direction is increased towards the inner side in the radial direction from the outer side in the radial direction. Therefore, when the core plate portions17move in the axial direction with the connecting portions as fulcra, a side surface of each connecting protruding portion63and the inner side surface of each connecting recessed portion171interfere with each other to suppress movement of the core plate portions17in the axial direction. Therefore, it is possible to suppress movement of the core plate portions17in the axial direction and removal of the core plate portions17from the scrap portion61.

The scrap portion61includes the plurality of the fixing portions64(eight fixing portions64inFIG. 6). It is desirable that each fixing portion64be point-symmetrically disposed around the center axis C1as the center. The shape of each fixing portion64in plan view is, for example, a rectangular or substantially rectangular shape. Each fixing portion64has a pushed-out shape pushed out towards the second side in the axial direction. When the fixing portion64are superimposed upon a scrap portion61, the fixing portions64overlap the scrap portion61in the axial direction. When a portion pushed out from each fixing portion64on the first side in the axial direction is fitted to a corresponding fixing portion64, the scrap portions61are fixed in the axial direction. That is, the scrap portions61superimposed upon each other in the axial direction are fixed by a crimping operation by making use of the fixing portions64.

As shown inFIG. 6, pin holes65are provided in two of the four corners of the scrap portion61, the two corners facing each other and symmetrically formed with respect to the center axis C1. In the embodiment, the number of pin holes65is two. The pin holes65extend through the plate member6in the axial direction.

In the plate member forming step S10, the plate member6where the core plate portions17have been fitted to the scrap portion61is formed. In the plate member forming step S10, first, a belt-shaped or substantially belt-shaped electromagnetic steel plate7is punched to form a disc portion71(FIG. 8) and a through hole72(FIG. 7). The shape of the disc portion71shown inFIG. 8in plan view is a circular or substantially circular shape. The disc portion71includes a plurality of connecting recessed portions171at its outer edge. The plurality of connecting recessed portions171are disposed at equal intervals in the peripheral direction at the outer edge of the disc portion71.

The through hole72shown inFIG. 7is formed by punching out the disc portion71from the electromagnetic steel plate7. The through hole72includes a plurality of connecting protruding portions63extending inward in the radial direction from an inner edge. The plurality of connecting protruding portions63are disposed at equal intervals in the peripheral direction at the inner edge of the through hole72. The connecting protruding portions63are formed along the connecting recessed portions171by punching the electromagnetic steel plate7.

Next, the disc portion71is fitted to the through hole72. As described above, the plurality of connecting protruding portions63are formed along the connecting recessed portions171corresponding thereto. Therefore, by fitting the disc portion71and the through hole72to each other, it is possible to fit the plurality of connecting protruding portions63and the plurality of connecting recessed portions171all together.

By punching a part of the electromagnetic steel plate7with the disc portion71fitted to the through hole72, an external shape of each core plate portion17(FIG. 9) and an external shape of each extending portion62(FIG. 10) are formed. Specifically, a portion of the disc portion71other than the portion that becomes the external shapes of the plurality of core plate portions17is punched out and separated. By the punching operation, the core plate portions17, the extending portions62, and the center hole60are formed. The core plate portions17are formed in a connected state with the extending portions62. That is, in the plate member forming step S10, by fitting the connecting protruding portions63to the connecting recessed portions171, the core plate portions17are connected to the extending portions62.

After forming the external shapes of the core plate portions17, when the connecting protruding portions63and the connecting recessed portions171are formed, the plurality of core plate portions17that have been stacked tend to come apart. As a result, it takes time and effort to fit the plurality of connecting protruding portions63and the plurality of connecting recessed portions171to each other. Therefore, in the embodiment, after assembling the disc portion71to the through hole72, the external shapes of the plurality of core plate portions17are formed. This manufacturing method is particularly useful for relatively small medium-sized motors or small-sized motors. Note that when manufacturing the rotor of large motors in which the core plate portions17do not easily come apart, the core plate portions17may be mounted on the extending portions62after forming the core plate portions17from the disc portion71.

Then, a part of the electromagnetic steel plate7is pushed out in the axial direction by a press operation to form the fixing portions64on an outer side of the center hole60of the electromagnetic steel plate7in the radial direction. A region where the fixing portions64are formed is a region that becomes the scrap portion61of the electromagnetic steel plate7. Therefore, the core plate portions17need not be provided with fixing portions64. Consequently, it is possible to suppress distortion of magnetic flux passing the outer cores14and to suppress deterioration in the magnetic characteristics of the motor A. Note that due to the “pushing out”, portions that protrude towards the second side in the axial direction are formed in the fixing portions64.

After the fixing portions64have been formed, the electromagnetic steel plate7is punched along the external shape of the plate member6shown inFIG. 6. This causes the plate member6to be formed. Note that the plate member forming step S10includes a step of forming the core-plate-portion through holes172and a step of forming the pin holes65. The step of forming the core-plate-portion through holes172and the step of forming the pin holes65may be performed, for example, before or after forming the external shapes of the core plate portions17after fitting the disc portion71to the through hole72.

That is, in the plate member molding step S10, the plate member6including the scrap portion61having the center hole extending therethrough in the axial direction and the core plate portions17that are disposed continuously with the scrap portion61on the inner side of the center hole60and that each constitutes a part of a corresponding one of the outer cores14is formed.

As shown inFIG. 11, the multilayer body forming step S20is a step of forming a multilayer body66by stacking plate members6. Each plate member6is successively stacked upon the first side of another plate member6in the axial direction. At this time, the pushed-out portions of the fixing portions64of a plate member6that is to be stacked are fitted to depressed portions of the fixing portions64of a plate member6that has already been stacked. This causes the plate members6that are superimposed upon each other in the axial direction to be fixed to each other.

In the embodiment, the plate members6formed by punching in the plate member forming step S10are successively stacked by dropping them as they are towards the second side in the axial direction. That is, the plate member forming step S10and the multilayer body forming step S20are performed concurrently. This makes it possible to efficiently form the multilayer body66. Note that the multilayer body forming step S20may be performed after forming all of the plate members6constituting the multilayer body66by performing the plate member forming step S10.

The multilayer body66is formed by stacking each plate member6upon the first side in the axial direction. Of the plate members6that constitute the multilayer body66, the fixing portions64of the plate member6disposed closest to the second side in the axial direction extend through the plate member6in the axial direction. In this way, by forming, as through holes, the fixing portions64of the plate member6that is closest to the second side in the axial direction, for example, when a plurality of multilayer bodies66are superimposed upon each other and formed, it is possible to prevent adjacent multilayer bodies66from being fixed to each other by the fixing portions64.

By stacking the plate members6upon each other, the core plate portions17are stacked upon each other. This causes the outer cores14to be formed. That is, the multilayer body66includes the outer cores14. That is, in the stacking step S20, the multilayer body66including the outer cores14is formed by stacking the plate members6upon each other.

As shown inFIG. 12, the mold setting step S30is a step of setting the multilayer body66and the inner core13in a mold. The order in which these are set in the mold is not particularly limited, so that the multilayer body66may be set first, the inner core13may be set first, or the multilayer body66and the inner core13may be set at the same time. A gap is formed between at least a part of the multilayer body66and a part of the inner core13. That is, in the mold setting step S30, the multilayer body66and the inner core13are set in a mold Md1and a mold Md2with a gap in the radial direction between at least a part of the multilayer body66and a part of the inner core13.

As an example, the mold includes the first mold Md1on the first side in the axial direction and the second mold Md2on the second side in the axial direction. First, the multilayer body66is set in the mold Md2. Here, as shown inFIG. 6, since each scrap portion61includes the extending portions62, a part of the second mold Md2or a jig can be disposed in a gap between extending portions62that are adjacent to each other in the peripheral direction. This makes it easier to stably hold the multilayer body66in the second mold Md2.

Next, the inner core13is inserted into a center hole of the multilayer body66that has been set in the second mold Md2and is positioned with respect to the second mold Md2. The second mold Md2has a hole Md21in which the inner core13is inserted. The center axis of the hole Md21in which the inner core13is inserted matches the center axis of the multilayer body66. By disposing the inner core13in the hole Md21, the inner core13is positioned with respect to the second mold Md2. Here, an end portion of the inner core13on the second side in the axial direction protrudes towards the second side in the axial direction from the second mold Md2. Note that a gap between the hole Md21of the second mold Md2in which the inner core13is inserted and the inner core13is made smaller, as a result of which a resin Rs that is ejected in the molded body forming step S40does not leak.

The first mold Md1is disposed from the first side in the axial direction and covers the second mold Md2. Here, the first mold Md1has a hole Md11in which the inner core13is inserted. The center axis of the hole Md11in which the inner core13is inserted matches the center axis of the multilayer body66. By disposing the inner core13in the hole Md11, the inner core13is positioned with respect to the first mold Md1. That is, an intermediate portion of the inner core13is disposed in the first mold Md1and the second mold Md2. Note that a gap between the hole Md11of the first mold Md1in which the inner core13is inserted and the inner core13is made smaller, as a result of which the resin Rs that is ejected in the molded body forming step S40does not leak.

In the mold setting step S30, at least a portion of the inner core13that is covered by the filling section15is set in the mold Md1and the mold Md2, and a portion of the inner core13protruding from the filling section15is set outside the mold Md1and the mold Md2.

A space that is surrounded by the first mold Md1and the second mold Md2includes the grooved portion131of the inner core13. That is, the multilayer body66and the inner core13are held in the first mold Md1and the second mold Md2. Here, the center axis of the inner core13and the center axis of the multilayer body66match (seeFIG. 13). For example, a part of the first mold Md1or a jig is disposed between outer cores14from the first side in the axial direction. This causes a portion of the rotor core12where the permanent magnets are disposed to be formed.

Note that a step of forming the grooved portion131in the outer peripheral surface of the inner core13so as to be recessed inward in the radial direction is provided before the mold setting step S30. The first mold Md1and the second mold Md2sandwich and hold the scrap portions61of the plate members6that are disposed on two ends of the multilayer body66in the axial direction.

The molded body forming step S40is a step of forming a molded body8shown inFIG. 14by pouring a molten resin or a molten magnetic material, serving as a filling material, into the mold and forming the filling section15. That is, in the molded body forming step S40, the molded body8is formed by pouring the molten filling material into gaps in the mold Md1and the mold Md2, and forming the filling section15, at least a part of the filling section15being positioned between the outer cores14.

The molded body8is formed by connecting the multilayer body66and the inner core13by the filling section15. Note that, in the description below, a case in which the filling section15is made of a resin, and the molten resin Rs is poured into the space in the first mold Md1and the space in the second mold Md2is described.

As shown inFIG. 12, in the molded body forming step S40, the resin is poured from gates G of the first mold Md1into the first mold Md1and the second mold Md2where a part of the inner core13and the multilayer body66are set. The gates G face in the axial direction an end surface of each outer core14on the first side in the axial direction with a gap therebetween. Therefore, the resin that is poured in from the gates G collides with the end surface of each outer core14on the first side in the axial direction. This causes pressure from an upper side to be applied to each outer core14by the ejection pressure of the resin that is ejected from the gates G. Therefore, the core plate portions17that have been stacked are in close contact with each other. Consequently, it is possible to suppress entry of the resin to locations between the core plate portions17and to suppress widening of gaps between the core plate portions17in the axial direction. As a result, it is possible to increase the dimensional precision of each outer core14.

As shown inFIG. 12, in the radial direction, the gates G are disposed at locations that do not correspond with the position of the outer-core through hole142. Therefore, the resin Rs that is poured into the first mold Md1and the second mold Md2from the gates G applies a pressure to the end surface of each outer core14on the first side in the axial direction. InFIG. 12, the gates G are disposed inward of the outer-core through hole142in the radial direction.

As shown inFIG. 12, inside the first mold Md1and the second mold Md2, spaces are provided at two ends of the outer cores14in the axial direction. When the resin Rs in the spaces at the two end portions of the outer cores14in the axial direction are solidified, the cover portions151of the filling section15are formed.

The plurality of plate members6of the multilayer body66are fixed to each other by the fixing portions64. That is, the plate members6are fixed to each other at portions of the plate members6on the outer side in the radial direction. The plate members6are subjected to the ejection pressure of the resin Rs at portions of the plate members6on the inner side in the radial direction. Therefore, the plate members6are held down at both end sides in the radial direction. As a result, a force that causes the stacked plate members to move away from each other in an up-down direction is further suppressed.

In the molded body forming step S40, by pouring the resin Rs into the outer-core through hole142, it is possible to dispose a part of the filling section15inside the outer-core through hole142. This makes it possible to fix the core plate portions17to each other by the filling section15as described above.

The plurality of gates G are provided at the first mold Md1. The plurality of gates G are disposed at equal intervals in the peripheral direction. Therefore, the flow of the resin Rs in the first mold Md1and the second mold Md2can be made uniform or substantially uniform in the entire peripheral direction, and the dimensional precision of the filling section15can be increased.

In the mold setting step S30, the grooved portion131that is formed in the outer peripheral surface of the inner core13is disposed in the spaces inside the first mold Md1and the second mold Md2. That is, in the mold setting step S30, the grooved portion131is disposed so as to face the gaps in the mold Md1and the mold Md2into which the filling material Rs is poured.

Therefore, the resin Rs that is poured in from the gates G is poured into the grooved portion131. Therefore, a part of the filling section15is disposed in the grooved portion131. Consequently, the inner core13and the filling section15can be more firmly fixed to each other.

The separating step S50is a step of separating the scrap portions61and the core plate portions17of the molded body8from each other. In the separating step S50, the connecting protruding portions63and the connecting recessed portions171are separated from each other to separate the scrap portions61and the core plate portions17from each other. Therefore, it is easy to separate the scrap portions61and the core plate portions17from each other.

Specifically, the molded body8is removed from the first mold Md1and the second mold Md2and is set in a pressing machine. By using the pressing machine, the rotor core12including the inner core13, the filling section15, and the outer cores14are punched out from the molded body8along a boundary between the scrap portions61and the core plate portions17.

Note that, in the description, “separate the scrap portions and the core plate portions” means that the scrap portions and the core plate portions only need to be capable of being detached from each other, and the means therefore is not particularly limited. For example, a case in which a portion between the scrap portions and the core plate portions is cut and a case in which this portion between the scrap portions and the core plate portions is snap-cut are also included.

In the separating step50, a portion excluding the inner core13, the filling section15, and the outer cores14, that is, the scrap portions61are removed from the molded body8. As described above, in the embodiment, the fixing portions64that fix the plate members6to each other are provided in the scrap portions61. After the molded body forming step S40, the core plate portions17are fixed to each other by the filling section15. Therefore, even if the scrap portions61are removed, the core plate portions17are not separated from each other, and the shapes of the outer cores14are maintained.

As shown inFIG. 16, in the magnet mounting step S51, the permanent magnets16are inserted from the openings of the magnet insertion holes152provided in the cover portion151on the first side of the rotor core12in the axial direction.

As shown inFIG. 17, the shaft mounting step S60is a step of mounting the shaft11in the inner core13of the rotor core12where the permanent magnets16have been mounted. The shaft11is mounted in the inner core13by, for example, press-fitting the outer peripheral surface of the shaft11to an inner peripheral surface130of the inner core13. This causes the shaft11to be fixed to the inner core13, that is, the rotor core12. Note that the fixing of the shaft11and the inner core13to each other is not limited to press-fitting. For example, it is possible to insert the shaft11into the inner core13and bond the shaft11to the inner core13. That is, the shaft mounting step S60is provided after the molded body forming step S40to fix the shaft11in the inner core13.

The fixing may be performed by fixing portions that fix both ends of the inner core13in the axial direction. The fixing portions may be an external thread provided on the shaft11and a nut having an internal thread that is capable of being screwed onto the external thread and a washer holding down the inner core13. Other methods of fixing the shaft11to the inner core13can be widely used. In this way, the shaft11can be made removable from the inner core13by the fixing using fasteners. That is, the shaft11is removable from the inner core13and may further include a fixing portion that fixes the shaft11and the inner core13to each other.

In the embodiment, in the mold setting step S30, an end portion of the inner core13on the first side in the axial direction protrudes from the first mold Md1. The end portion of the inner core13on the second side in the axial direction protrudes from the second mold Md2. That is, an inner peripheral surface of the hole of the first mold Md1and an inner peripheral surface of the hole of the second mold Md2are made to contact the outer peripheral surface of the inner core13. Therefore, by using at least the inner core13whose portions that contact the first mold Md1and the second mold Md2have the same outside diameter, even if the first mold Md1and the second mold Md2are not changed, it is possible to manufacture rotor cores12having different shapes. For example, rotor cores12to be mounted on shafts11having different diameters may be manufactured. In this case, an inner core13having a common outside diameter and having inside diameters corresponding to the shafts11are used. This makes it possible to, by using the common first mold Md1and the common second mold Md2, to manufacture rotor cores12to be mounted on shafts11having different outside diameters.

Note that the mold according to the embodiment includes the first mold Md1that is disposed from the first side in the axial direction and the second mold Md2that is disposed from the second side in the axial direction. Therefore, in the molded body forming step S40, after forming the molded body8, it can be formed by moving the first mold Md1towards the first side in the axial direction and the second mold Md2towards the second side in the axial direction. This makes it possible to simplify the manufacturing step because the mold ejection direction is uniaxial. In addition, since the structure of the mold is also simplified, it is possible to reduce the costs required for manufacturing the mold. However, it is not limited thereto. For example, at least one mold that is disposed from the outer side in the radial direction may be provided. Note that “the costs required for manufacturing” here includes the time, labor, and material required for the manufacturing.

The sensor magnet52is mounted on the shaft11fixed to the rotor core12. Specifically, the sensor yoke51is press-fitted to the shaft11. The rotor1, the stator2, the first bearing41, and the second bearing42, which have been described above, are accommodated in the housing3. This causes the motor A including the above-described rotor1to be manufactured.

FIG. 18is a perspective view showing another example of an inner core of the rotor according to the embodiment. An inner core13B shown inFIG. 18includes an inner cylindrical body132B on the inner side in the radial direction and an outer cylindrical body133B on the outer side of the inner cylindrical body132B. That is, the inner core13B includes a plurality of cylindrical bodies that are adjacent to each other in the radial direction.

The outer cylindrical body133B is disposed in the first mold Md1and the second mold Md2to form the molded body8. That is, in the mold setting step S30, at least the outer cylindrical body133B of the inner core13B that is disposed on the outermost side in the radial direction is set in the molds Md1and Md2. When the shaft11having an outside diameter that is the same or substantially the same as the inside diameter of the outer cylindrical body133B is to be fixed, the shaft11is directly fixed to the outer cylindrical body133B. Note that, for the fixing of the outer cylindrical body133B and the shaft11, press-fitting may be mentioned; however, the fixing is not limited thereto.

A shaft11having an outside diameter that is smaller than the inside diameter of the outer cylindrical body133B may be fixed. After fixing the inner cylindrical body132B to the shaft11, the inner cylindrical body132B is fixed to the outer cylindrical body133B. Note that the inner cylindrical body132B is press-fitted to the outer cylindrical body133B. This causes the shaft11to be fixed to the rotor core12. An outer peripheral surface of the inner cylindrical body132B and an inner peripheral surface of the outer cylindrical body133B each have a shape and size that allow press-fitting. Note that, although, in the embodiment, the inner cylindrical body132B is previously fixed to the shaft11, the fixing is not limited thereto. For example, it is possible to, after inserting the shaft11into the outer cylindrical body133B, insert the inner cylindrical body132B between the shaft11and the outer cylindrical body133B to fix the shaft11and the rotor core12to each other. Although the inner core13B includes two cylindrical bodies, the inner cylindrical body132B and the outer cylindrical body133B, the inner core13B is not limited thereto. It may include three or more cylindrical bodies.

In this way, when the inner core13B includes a plurality of cylindrical bodies that are adjacent to each other in the peripheral direction, it is possible to fix shafts11having different outside diameters by using one type of rotor core12.

FIG. 19is a perspective view of another example of an inner core of the rotor according to the embodiment. An inner core13C shown inFIG. 19has a structure in which ring-shaped plate portions134are stacked in the axial direction. In the plate member molding step S10, the ring-shaped plate portions134are molded by punching into ring shapes a portion of the disc portion71remaining after forming the plurality of core plate portions17by punching. Then, the ring-shaped plate portions134formed by punching into the ring shapes are stacked and formed. That is, the inner core13C is a multilayer cylindrical body including the ring-shaped plate materials134that are stacked upon each other.

By forming the inner core13C into a multilayer body including the ring-shaped plate portions134, uneven portions are formed at an outer peripheral surface of the inner core13C. In the molded body forming step S40, an ejected resin Rs enters the uneven portions of the ring-shaped plate portions134. Therefore, even if the outer peripheral surface of the inner core13C is not provided with a grooved portion131, it is possible to more firmly fix the inner core13C and the filling section15to each other.

The ring-shaped plate portions134can be molded out of an unnecessary portion that is produced when manufacturing the multilayer body66, such as a portion of the disc portion71, shown, for example, inFIG. 9, remaining after molding the core plate portions17. Therefore, it is possible to cut manufacturing costs of the inner core13C. Note that the inner core13C may be molded out of a remaining portion of the scrap portion61. The step of forming the core plate portions17by punching included in the plate member molding step may be performed after the stacking step and, after forming the stacked core plate portions17by punching, stacked disc portions71may be punched into a cylindrical or substantially cylindrical shape.

That is, the ring-shaped plate material forming step of forming the ring-shaped plate materials134constituting a part of the inner core13C and the inner core forming step of forming the multilayer cylindrical body by stacking the ring-shaped plate materials134may be provided before the mold setting step S30. Note that, in the inner core13B, at least one of the plurality of cylindrical bodies is a multilayer cylindrical body including ring-shaped plate materials134that are stacked upon each other.

A method of manufacturing a rotor according to an exemplary second embodiment of the present disclosure is described with reference to the drawings. Note that the method of manufacturing a rotor according to the embodiment includes a shaft mounting step S601in place of the shaft mounting step S60. In addition, the method includes a molded body forming step S401in place of the molded body forming step S40.

FIG. 20is a perspective view of a state in which a shaft is mounted in an inner core.FIG. 21shows a state in which the inner core in which the shaft is mounted is set in the mold.FIG. 22is a perspective view showing a multilayer body, the inner core, and the shaft disposed in the mold.FIG. 23is a perspective view of a molded body before separation.

FIG. 20shows a part of the shaft mounting step S601. As shown inFIG. 20, a shaft11is fixed to a cylindrical inner core13. That is, the shaft mounting step S601is provided before the mold setting step S30. Note that the shaft mounting step S601may be provided before the plate material molding step S10or before the stacking step S20. The shaft mounting step S601may be performed concurrently with one or both of these steps.

As shown inFIGS. 21 and 22, in the mold setting step S30, the inner core13to which the shaft11is fixed is mounted in the first mold Md1and the second mold Md2. An outer peripheral surface of the inner core13contacts the hole of the first mold Md1. The outer peripheral surface of the inner core13also contacts the hole of the second mold Md2. Therefore, in the mold setting step S30, if the outside diameter of the inner core13is the same, the molded body forming step S40can be performed by using the same first mold Md1and second mold Md2regardless of whether there is a shaft11.

Then, in the molded body forming step S40, a molded body8is formed after pouring a resin Rs.

As described above, in the embodiment, the shaft11is fixed to the inner core13before forming the filling section15. Therefore, when the filling section15is included, it is possible to use a fixing method that cannot be used or that is difficult to use, such as shrink fitting or welding.

Although the embodiments of the present disclosure have been described above, the embodiments can be variously modified within the scope of the spirit of the present disclosure.