Patent Description:
As disclosed in Patent Literature <NUM> (<CIT>), there is known a rotor that is used in an outer rotor type motor and is molded by injecting resin into a mold into which a magnet or the like is inserted.

Further examples of known rotors are disclosed by patent documents <CIT>, <CIT> and <CIT>.

When the resin is injected, gas may remain in a resin thin portion inside the magnet, and a swelling portion due to residual gas may be formed on an inner circumferential surface of the rotor after molding. Since the swelling portion comes into contact with a stator and causes abnormal noise, a step of removing the swelling portion is required.

Aim of the present invention is to provide a motor, a fan and an air conditioner which improve the state of the art indicated above. This aim is achieved by the motor, the fan and the air conditioner according to the corresponding appended claims.

A motor according to a first aspect includes a rotor molded by resin casting, and a stator disposed inside the rotor. The rotor has a cylindrical portion in which a plurality of magnets are arranged side by side in a circumferential direction. The magnets are exposed on a side of an open end as one end of the cylindrical portion in an axial direction of the cylindrical portion. The cylindrical portion includes an inner resin as a resin located inside each of the magnets in a radial direction of the cylindrical portion. The inner resin has a first resin portion and a second resin portion closer to the open end than the first resin portion in the axial direction. A sectional area of the second resin portion perpendicular to the axial direction is smaller than a sectional area of the first resin portion perpendicular to the axial direction.

The motor according to the first aspect suppresses formation of a swelling portion due to residual gas on an inner circumferential surface of the rotor molded by resin casting.

A motor according to a second aspect is the motor according to the first aspect, in which the sectional area of the second resin portion perpendicular to the axial direction gradually decreases toward the open end along the axial direction.

The motor according to the second aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to a third aspect is the motor according to the first aspect, in which the sectional area of the second resin portion perpendicular to the axial direction continuously decreases toward the open end along the axial direction.

The motor according to the third aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to a fourth aspect is the motor according to the first aspect, in which a dimension of the second resin portion in the radial direction is constant along the axial direction.

The motor according to the fourth aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to a fifth aspect is the motor according to any one of the first to fourth aspects, in which at least a part of each of the magnets is exposed inside in the radial direction in a range at which the second resin portion is located in the axial direction.

The motor according to the fifth aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to a sixth aspect is the motor according to any one of the first to fifth aspects, in which the second resin portion is in contact with the first resin portion in the axial direction and includes the open end.

The motor according to the sixth aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to a seventh aspect is the motor according to any one of the first to sixth aspects, in which a dimension of the first resin portion in the axial direction is <NUM>% to <NUM>% of a dimension of the cylindrical portion in the axial direction.

The motor according to the seventh aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to an eighth aspect is the motor according to any one of the first to seventh aspects, in which the second resin portion has a dimension of <NUM> or less in the radial direction.

The motor according to the eighth aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to a ninth aspect is the motor according to any one of the first to eighth aspects, in which the first resin portion has a dimension of <NUM> to <NUM> in the radial direction.

The motor according to the ninth aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to a tenth aspect is the motor according to any one of the first to ninth aspects, in which an interval between the rotor and the stator is larger than <NUM> and <NUM> or less.

The motor according to the tenth aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A motor according to an eleventh aspect is the motor according to any one of the first to tenth aspects, in which the rotor is molded by injecting resin from an injection port into an inside of a mold into which at least the magnets are inserted. The injection port is located at an end of the mold opposite to the open end.

The motor according to the eleventh aspect suppresses formation of the swelling portion due to the residual gas on the inner circumferential surface of the rotor molded by resin casting.

A fan according to a twelfth aspect includes the motor according to any one of the first to eleventh aspects and a blade driven by the motor.

The fan according to the twelfth aspect can suppress generation of abnormal noise caused by contact between the rotor and the stator of the motor.

An air conditioner according to a thirteenth aspect includes a casing and the fan according to the twelfth aspect. The fan is accommodated inside the casing.

The air conditioner according to the thirteenth aspect can suppress generation of abnormal noise caused by contact between the rotor and the stator of the motor of the fan.

As shown in <FIG>, an air conditioner <NUM> mainly includes an indoor unit <NUM> attached to an indoor wall surface or the like, and an outdoor unit <NUM> installed outdoors. The indoor unit <NUM> and the outdoor unit <NUM> are connected to each other via a refrigerant pipe <NUM> to constitute a refrigerant circuit of the air conditioner <NUM>. The air conditioner <NUM> performs cooling operation, heating operation, and the like in a space in which the indoor unit <NUM> is installed.

A motor <NUM> according to the embodiment is used for a fan <NUM>. The outdoor unit <NUM> of the air conditioner <NUM> includes the fan <NUM>. As shown in <FIG>, the outdoor unit <NUM> mainly includes the fan <NUM>, a casing <NUM>, a heat exchanger <NUM>, a compressor <NUM>, an internal pipe, and a control unit. The casing <NUM> accommodates the fan <NUM>, a partition plate <NUM>, the heat exchanger <NUM>, a bell mouth <NUM>, the compressor <NUM>, and the like. The internal pipe is a part of the refrigerant circuit of the air conditioner <NUM>, and is a pipe through which a refrigerant circulating in the refrigerant circuit flows. The control unit is a microcomputer including a CPU, a memory, and the like. The control unit controls the motor <NUM> and the like of the fan <NUM>.

The partition plate <NUM> partitions a space inside the casing <NUM> into a fan chamber 102a and a machine chamber 102b. The fan <NUM>, the heat exchanger <NUM>, and the bell mouth <NUM> are disposed in the fan chamber 102a. The compressor <NUM> and the control unit are disposed in the machine chamber 102b.

The compressor <NUM> compresses the refrigerant circulating in the refrigerant circuit of the air conditioner <NUM>. The refrigerant compressed by the compressor <NUM> is sent to the heat exchanger <NUM> of the outdoor unit <NUM> during the cooling operation, and is sent to the heat exchanger of the indoor unit <NUM> during the heating operation.

The heat exchanger <NUM> causes heat exchange between the refrigerant and air. The heat exchanger <NUM> includes, for example, a heat transfer tube folded back a plurality of times at both ends in a longitudinal direction of the heat exchanger <NUM> and a fin attached to the heat transfer tube. The heat transfer tube is a part of the refrigerant circuit of the air conditioner <NUM>, and is a pipe through which the refrigerant circulating in the refrigerant circuit flows. The heat exchanger <NUM> causes heat exchange between the refrigerant flowing inside the heat transfer tube and air passing through the fin. The heat exchanger <NUM> functions as a condenser (radiator) during the cooling operation, and functions as an evaporator (heat absorber) during the heating operation.

The fan <NUM> mainly includes the motor <NUM> and a blade <NUM>. The blade <NUM> is a propeller fan that is driven by the motor <NUM> and sends air in a predetermined direction. The blade <NUM> forms an air flow that promotes heat exchange by the heat exchanger <NUM>. The air flow formed by a rotation of the blade <NUM> sucks air outside the casing <NUM> into the fan chamber 102a inside the casing <NUM>. In this process, the air passes through the heat exchanger <NUM> to exchange heat with the refrigerant, and then passes through the bell mouth <NUM> to be discharged to the outside of the casing <NUM>.

As shown in <FIG>, the motor <NUM> mainly includes the rotor <NUM>, a stator <NUM>, a motor cover <NUM>, a connection plate <NUM>, and a shaft <NUM>. The motor <NUM> is an outer rotor type motor. In other words, the stator <NUM> is disposed inside the rotor <NUM>. <FIG> schematically shows the blade <NUM>.

The stator <NUM> mainly includes a stator core <NUM>, a coil <NUM>, and an insulator <NUM>. The stator core <NUM> is formed by laminating steel plates that are conductive soft magnetic materials. The stator core <NUM> includes a plurality of teeth 31a. The coil <NUM> is formed by winding a copper wire coated with an insulating material such as enamel resin around the teeth 31a of the stator core <NUM>. The insulator <NUM> is formed by an insulating resin material. The insulator <NUM> is provided between the stator core <NUM> and the coil <NUM>. The insulator <NUM> insulates the stator core <NUM> from the coil <NUM> so that a current flowing through the coil <NUM> is not transmitted to the stator core <NUM>. The stator core <NUM> has a through hole through which the shaft <NUM> penetrates along the axial direction.

As shown in <FIG> and <FIG>, the rotor <NUM> mainly includes a resin cylindrical portion <NUM>, a plurality of magnets <NUM>, a back yoke <NUM>, and a boss core <NUM>. In the following description, an "axial direction" refers to a direction of a center axis of the cylindrical portion <NUM>, a "radial direction" refers to a radial direction centered on the center axis of the cylindrical portion <NUM>, and a "circumferential direction" refers to a circumferential direction centered on the center axis of the cylindrical portion <NUM>.

The rotor <NUM> is molded by resin casting. In the resin casting, a resin is poured into a cavity formed by the mold in a state where the plurality of magnets <NUM>, the back yoke <NUM>, and the boss core <NUM> are accommodated in the cavity as shown in <FIG>. Thereafter, the rotor <NUM> is molded by curing the resin by heating or cooling. The magnets <NUM>, the back yoke <NUM>, and the boss core <NUM> are integrated by resin casting.

The rotor <NUM> is disposed outside of the stator <NUM> in the radial direction so as to be rotatable about an axis <NUM> of the shaft <NUM>. A gap <NUM> is formed between an inner circumferential surface of the cylindrical portion <NUM> of the rotor <NUM> and an outer circumferential surface of the stator core <NUM> of the stator <NUM>. A dimension of the gap <NUM> in the radial direction between the rotor <NUM> and the stator <NUM> is larger than <NUM> and <NUM> or less.

In the cylindrical portion <NUM>, the plurality of magnets <NUM> are arranged side by side in the circumferential direction. An inner surface of the magnet <NUM> in the radial direction is a flat surface that is not curved. The magnets <NUM> are exposed on a side of an open end 21a as one end in the axial direction of the cylindrical portion <NUM>. The back yoke <NUM> is located outside of the magnet <NUM> in the radial direction. The boss core <NUM> is engaged with the shaft <NUM> to couple the rotor <NUM> and the shaft <NUM>. As a result, the rotor <NUM> rotates around the stator <NUM> integrally with the shaft <NUM>. When the cylindrical portion <NUM> is viewed along the axial direction, the boss core <NUM> is located at the center of the cylindrical portion <NUM>. The cylindrical portion <NUM> is connected to the boss core <NUM> via a plurality of resin coupling portions <NUM>. The coupling portions <NUM> are formed integrally with the cylindrical portion <NUM> by resin casting.

As shown in <FIG>, the boss core <NUM> is located on the opposite side of the open end 21a in the axial direction. On the opposite side of the open end 21a, an end of each magnet <NUM> is coupled to the boss core <NUM> via one coupling portion <NUM>.

As shown in <FIG>, the cylindrical portion <NUM> includes an inner resin <NUM> as a resin located inside the magnet <NUM> in the radial direction. The inner resin <NUM> includes a first resin portion 23a and a second resin portion 23b. The second resin portion 23b is a portion closer to the open end 21a than the first resin portion 23a in the axial direction. The second resin portion 23b is in contact with the first resin portion 23a in the axial direction and includes the open end 21a. The coupling portion <NUM> is in contact with the first resin portion 23a.

A dimension of the first resin portion 23a in the axial direction and a dimension of the second resin portion 23b in the axial direction are constant in the circumferential direction. In the axial direction, a dimension of the cylindrical portion <NUM> is equal to a sum of a dimension L1 of the first resin portion 23a and the dimension L2 of the second resin portion 23b. In the axial direction, the dimension L1 of the first resin portion 23a is <NUM>% to <NUM>% of a dimension L0 of the cylindrical portion <NUM> (see <FIG>).

As shown in <FIG> and <FIG>, a sectional area of the second resin portion 23b perpendicular to the axial direction is smaller than a sectional area of the first resin portion 23a perpendicular to the axial direction. A dimension of the second resin portion 23b in the radial direction is constant along the axial direction. The dimension of the second resin portion 23b in the radial direction is <NUM> or less. Specifically, as shown in <FIG>, in the second resin portion 23b, a resin layer having a constant thickness is formed on an inner plane of the magnet <NUM> in the radial direction. In this case, a thickness T1 of the second resin portion 23b is, for example, <NUM> or less.

As shown in <FIG>, a sectional shape of the first resin portion 23a perpendicular to the axial direction is different from a sectional shape of the second resin portion 23b perpendicular to the axial direction. Specifically, the first resin portion 23a has a thin portion 23a1 located at a center in the circumferential direction and thick portions 23a2 located on both sides of the thin portion 23a1 in the circumferential direction. A dimension T2 of the thin portion 23a1 in the radial direction is equal to the thickness T1 of the second resin portion 23b, or slightly larger than the thickness T1 of the second resin portion 23b.

The dimension of the first resin portion 23a in the radial direction is from <NUM> to <NUM>. For example, the dimension T2 of the thin portion 23a1 in the radial direction is <NUM>, and a maximum value of a dimension T3 of each of the thick portions 23a2 in the radial direction is <NUM>. The dimension of the first resin portion 23a may gradually increase from the center in the circumferential direction toward both ends in the circumferential direction. In this case, the maximum value of the dimension T3 of the thick portion 23a2 in the radial direction is equal to the dimension of the first resin portion 23a at both ends in the circumferential direction (see <FIG>).

The motor cover <NUM> covers the stator <NUM> and the connection plate <NUM>. The motor cover <NUM> mainly includes a first cover <NUM>, a second cover <NUM>, and a third cover <NUM>. The first cover <NUM> covers the stator <NUM> while facing inside of the rotor <NUM> in the radial direction. The second cover <NUM> surrounds the rotor <NUM> from outside of the rotor <NUM> in the radial direction. The third cover <NUM> covers an end of the rotor <NUM> in the axial direction closer to the boss core <NUM>. The motor cover <NUM>, for example, is formed by bulk molding compound (BMC) which is a thermosetting resin material. BMC is a resin material containing an unsaturated polyester resin as a main component to which a flame retardant such as aluminum hydroxide is added. The stator <NUM> is fixed to the motor cover <NUM>. A bearing <NUM> for supporting the shaft <NUM> is attached to the motor cover <NUM>. The bearing <NUM> is, for example, a metal ball bearing.

The motor cover <NUM> is fixed to the casing <NUM> of the outdoor unit <NUM> via a vibration-proof member. The vibration-proof member is molded by rubber or the like, and has a function of absorbing vibration of the motor <NUM>.

The connection plate <NUM> is disposed inside the motor cover <NUM> and at one end of the stator <NUM> in the axial direction. The connection plate <NUM> is connected to a winding start wire and a winding end wire of the coil <NUM> of the stator <NUM>. The connection plate <NUM> is connected to an external power source or the like via a lead wire.

The shaft <NUM> is a metal cylindrical member. As shown in <FIG>, the shaft <NUM> is coupled to the blade <NUM> at one end in the axial direction, and is coupled to the boss core <NUM> of the rotor <NUM> at the other end in the axial direction. The shaft <NUM> is rotatably supported with respect to the motor cover <NUM> by the bearing <NUM> fixed to the motor cover <NUM>.

The stator <NUM> generates a magnetic field for rotating the rotor <NUM> by power supplied from the outside to the coil <NUM> via the connection plate <NUM>. The rotor <NUM> is rotated by the magnetic field generated from the stator <NUM>. The shaft <NUM> coupled to the rotor <NUM> rotates about the axis <NUM> along the axial direction. The motor <NUM> transmits the rotational force to the blade <NUM> via the shaft <NUM> while supporting the shaft <NUM>. As a result, the motor <NUM> rotates the blade <NUM> about the axis <NUM> of the shaft <NUM>.

The rotor <NUM> of the motor <NUM> according to the embodiment includes the inner resin <NUM> (the first resin portion 23a and the second resin portion 23b). The rotor <NUM> is molded by resin casting. The mold used for resin casting of the rotor <NUM> has the resin filling space <NUM> and the injection port <NUM> inside the mold. The resin filling space <NUM> is a space that is filled with resin to mold the rotor <NUM>. The injection port <NUM> communicates with the resin filling space <NUM>. The injection port <NUM> is a space for filling the resin filling space <NUM> with resin by injecting the resin from outside.

The resin filling space <NUM> has the same shape as a shape in which the cylindrical portion <NUM> having the first resin portion 23a and the second resin portion 23b and the plurality of coupling portions <NUM> are connected. At the time when the resin is poured into the resin filling space <NUM>, at least the plurality of magnets <NUM>, the back yoke <NUM>, and the boss core <NUM> are accommodated in the resin filling space <NUM>. As shown in <FIG>, the resin is injected into the resin filling space <NUM> from the injection port <NUM>. In <FIG>, a dotted arrow indicates a flow of the resin injected from the injection port <NUM> into the resin filling space <NUM>. An injection port <NUM> is located at an end in the axial direction of the resin filling space <NUM>, the end being opposite to the open end 21a of the rotor <NUM>. Specifically, the injection port <NUM> is connected to an outer side surface of the resin filling space <NUM> in the radial direction at an end on a side where the boss core <NUM> is accommodated.

A process of filling the resin filling space <NUM> with the resin will be described. The resin poured into the resin filling space <NUM> from the injection port <NUM> first passes through a space forming the coupling portion <NUM> to fill a space forming the first resin portion 23a, and then fills a space forming the second resin portion 23b. Since the rotor <NUM> has the open end 21a which is not covered with the resin, a gas in the cavity inside the mold escapes from the open end 21a in the process of filling the resin filling space <NUM> with the resin.

The first resin portion 23a has the thin portion 23a1 and the thick portions 23a2 located on both sides of the thin portion 23a1 in the circumferential direction. The dimension T3 of the thick portion 23a2 in the radial direction is larger than the dimension T2 of the thin portion 23a1 in the radial direction. Therefore, in the resin filling space <NUM>, a flow resistance of the space forming the thick portion 23a2 is smaller than a flow resistance of the space forming the thin portion 23a1.

The dimension T3 in the radial direction of the thick portion 23a2 of the first resin portion 23a is larger than the thickness T1 of the second resin portion 23b. The dimension T2 in the radial direction of the thin portion 23a1 of the first resin portion 23a is substantially equal to the thickness T1 of the second resin portion 23b. Therefore, in the resin filling space <NUM>, a flow resistance of the space forming the first resin portion 23a is smaller than a flow resistance of the space forming the second resin portion 23b.

In the process of filling the resin filling space <NUM> with the resin, the resin flows from a space having a small flow resistance toward a space having a large flow resistance. Therefore, as shown in <FIG>, the resin poured from the injection port <NUM> into the space forming the first resin portion 23a tends to flow from the space forming the first resin portion 23a having a small flow resistance toward the space forming the second resin portion 23b having a larger flow resistance. In other words, in the space forming the first resin portion 23a and the second resin portion 23b, the resin easily flows in the axial direction or in a direction substantially parallel to the axial direction from the side of the injection port <NUM> toward the side of the open end 21a. When the resin flows in the axial direction toward the open end 21a, a gas in the resin filling space <NUM> can escape from the open end 21a. Therefore, after the resin filling space <NUM> is filled with the resin, the gas hardly remains between the inner surface in the radial direction of the magnet <NUM> and the inner resin <NUM>.

<FIG> is an external view of a resin filling space <NUM> as a comparative example. In <FIG>, a dotted arrow indicates a flow of the resin injected from an injection port <NUM> into the resin filling space <NUM>. In <FIG>, a sectional shape of the inner resin of the rotor is constant in the axial direction and is the same as the sectional shape of the first resin portion 23a according to the embodiment. Therefore, the space forming the inner resin of the rotor includes a thin portion space <NUM> at a center of the magnet in the circumferential direction and thick portion spaces <NUM> at both ends of the magnet in the circumferential direction. The thin portion space <NUM> corresponds to a space forming the thin portion 23a1 according to the embodiment. The thick portion space <NUM> corresponds to a space forming the thick portion 23a2 according to the embodiment. The injection port <NUM> is at the same position as the injection port <NUM> according to the embodiment.

The resin injected into the resin filling space <NUM> from the injection port <NUM> tends to flow from the thick portion space <NUM> having a small flow resistance toward the thin portion space <NUM> having a large flow resistance. Therefore, as shown in <FIG>, in a space on the inner side of the magnet in the radial direction, the resin easily flows from both ends of the magnet in the circumferential direction (the thick portion spaces <NUM>) toward the center of the magnet in the circumferential direction (the thin portion space <NUM>). In this case, since the resin is filled from both ends of the magnet in the circumferential direction (the thick portion spaces <NUM>), the center of the magnet in the circumferential direction (thin portion space <NUM>) is the last portion to be filled with the resin. As a result, the gas in the resin filling space <NUM> tends to remain at the center of the magnet in the circumferential direction (the thin portion space <NUM>). Furthermore, when the rotor does not have the open end 21a according to the embodiment, in other words, when the end of the magnets in the axial direction is covered with the resin, the gas in the resin filling space <NUM> does not escape from the end of the rotor in the axial direction, and thus the gas in the resin filling space <NUM> tends to remain.

If the gas remained between the inner surface of the magnet <NUM> in the radial direction and the inner resin <NUM>, a swelling portion due to a residual gas would be formed on an inner circumferential surface of the rotor <NUM> after molding. The swelling portion is a portion where the resin swells inward in the radial direction from the inner circumferential surface of the rotor <NUM>. In the comparative example of <FIG>, the swelling portion is easily formed in the thin portion space <NUM> where the gas in the resin filling space <NUM> tends to remain. If the dimension in the radial direction of the swelling portion is larger than the dimension in the radial direction of the gap <NUM> between the rotor <NUM> and the stator <NUM>, the swelling portion may come into contact with the stator <NUM> during rotation of the rotor <NUM>. As a result, abnormal noise may occur during driving of the motor <NUM>, or the motor <NUM> may fail, and thus a step of removing the swelling portion is required after molding of the rotor <NUM>. For example, a step of scraping the swelling portion to expose an inner circumferential surface of the magnet <NUM> in the radial direction is required.

However, in the embodiment, since the gas hardly remains between the inner surface of the magnet <NUM> in the radial direction and the inner resin <NUM> due to the above-described reason, a step of removing the swelling portion formed on the inner circumferential surface of the rotor <NUM> by the residual gas after molding the rotor <NUM> by resin casting becomes unnecessary. As a result, the abnormal noise caused by the swelling portion formed on the inner circumferential surface of the rotor <NUM> coming into contact with the stator <NUM> is suppressed, and therefore, a noise generated from the motor <NUM> and the failure of the motor <NUM> are suppressed.

As shown in <FIG> and <FIG>, the inner surface of the magnet <NUM> in the radial direction may be curved in a concave shape inward in the radial direction. For example, the inner surface of the magnet <NUM> in the radial direction when viewed along the axial direction may have an arc shape.

In this modification, as shown in <FIG>, the first resin portion 23a includes the thin portion 23a1 and the thick portions 23a2 located on both sides of the thin portion 23a1 in the circumferential direction. The dimension of the thin portion 23a1 in the radial direction is smaller than the dimension of each of the thick portions 23a2 in the radial direction. A dimension of the second resin portion 23b in the radial direction is constant in the circumferential direction. Specifically, as shown in <FIG>, in the second resin portion 23b, a resin layer having a constant thickness is formed on an inner curved surface of the magnet <NUM> in the radial direction. In this case, the inner surface of the second resin portion 23b in the radial direction has the same curvature as the inner surface of the magnet <NUM> in the radial direction.

In this modification, as in the embodiment, in the space forming the first resin portion 23a and the second resin portion 23b, the resin easily flows in the axial direction or in a direction substantially parallel to the axial direction from the side of the first resin portion 23a toward the side of the open end 21a. Therefore, after the rotor <NUM> is molded by resin casting, the step of removing the swelling portion on the inner circumferential surface of the rotor <NUM> by the residual gas becomes unnecessary.

As shown in <FIG>, the sectional area of the second resin portion 23b perpendicular to the axial direction may gradually decrease toward the open end 21a along the axial direction. In this case, in the process of filling the space forming the second resin portion 23b with the resin, the flow resistance of the space forming the second resin portion 23b gradually increases toward the open end 21a. As in the embodiment, the resin easily flows in the axial direction or in a direction substantially parallel to the axial direction from the side of the first resin portion 23a toward the side of the open end 21a.

As shown in <FIG>, the sectional area of the second resin portion 23b perpendicular to the axial direction may continuously decrease toward the open end 21a along the axial direction. In this case, in the process of filling the space forming the second resin portion 23b with the resin, the flow resistance of the space forming the second resin portion 23b gradually increases toward the open end 21a. As in the embodiment, the resin easily flows in the axial direction or in a direction substantially parallel to the axial direction from the side of the first resin portion 23a toward the side of the open end 21a.

At least a part of the inner surface of the magnet <NUM> in the radial direction may be exposed in a range at which the second resin portion 23b is located in the axial direction. In other words, at least a part of the second resin portion 23b may have a portion where no resin is present.

Alternatively, the second resin portion 23b does not need to be present. In other words, the sectional area of the second resin portion 23b perpendicular to the axial direction may be <NUM>.

In this modification, in the process of filling the space forming the inner resin <NUM> with the resin, the gas in the resin filling space <NUM> easily escapes from the portion where the magnet <NUM> is exposed. Therefore, the gas hardly remains between the inner surface in the radial direction of the magnet <NUM> and the inner resin <NUM>.

The air conditioner <NUM> may be a device that does not have a cooling function and a heating function but has an air cleaning function. In this case, the air conditioner <NUM> includes the fan <NUM> for sending clean air from which foreign matters and the like have been removed, and the motor <NUM> is used for the fan <NUM>.

The motor <NUM> may be used for equipment and devices other than the fan <NUM> and the air conditioner <NUM>.

The mold is used for resin casting of the rotor <NUM>. The mold has the resin filling space <NUM> and the injection port <NUM> inside the mold. The resin filling space <NUM> is a space that is filled with resin to mold the rotor <NUM>. The injection port <NUM> communicates with the resin filling space <NUM>. The injection port <NUM> is a space for filling the resin filling space <NUM> with resin by injecting the resin from outside. The rotor <NUM> has the cylindrical portion <NUM> in which the plurality of magnets <NUM> are arranged side by side in the circumferential direction. The magnets <NUM> are exposed on a side of an open end 21a as one end in the axial direction of the cylindrical portion <NUM>. The cylindrical portion <NUM> includes the inner resin <NUM> as a resin located inside the magnet <NUM> in the radial direction of the cylindrical portion <NUM>. The inner resin <NUM> has the first resin portion 23a and the second resin portion 23b closer to the open end than the first resin portion 23a in the axial direction. The sectional area of the second resin portion 23b perpendicular to the axial direction is smaller than the sectional area of the first resin portion 23a perpendicular to the axial direction. At least the magnet <NUM> is accommodated in the resin filling space <NUM> when the resin is filled. The injection port <NUM> is located at an end in the axial direction of the resin filling space <NUM>, the end being opposite to the open end 21a.

Although the embodiment of the present disclosure has been described above, it will be understood that various changes in form and details can be made without departing from the and scope of the present disclosure described in the apended claims.

Claim 1:
A motor (<NUM>) comprising:
a rotor (<NUM>) molded by resin casting; and
a stator (<NUM>) disposed inside the rotor, wherein
the rotor includes a cylindrical portion (<NUM>) in which a plurality of magnets (<NUM>) are arranged side by side in a circumferential direction, and a boss core (<NUM>),
the magnets are exposed on a side of an open end (21a) as one end of the cylindrical portion in an axial direction of the cylindrical portion,
the cylindrical portion includes an inner resin (<NUM>) as a resin located inside each of the magnets in a radial direction of the cylindrical portion,
the inner resin includes
a first resin portion (23a), and
a second resin portion (23b) closer to the open end than the first resin portion in the axial direction, and
a sectional area of the second resin portion perpendicular to the axial direction is smaller than a sectional area of the first resin portion perpendicular to the axial direction,.
characterized in that
the boss core is located on the opposite side of the open end in the axial direction,
wherein, on the opposite side of the open end, an end of each magnet is coupled to the boss core via one coupling portion (<NUM>),
the second resin portion is in contact with the first resin portion in the axial direction and includes the open end,
the coupling portion is in contact with the first resin portion.