Patent Application
20140334951
The present invention relates to outdoor fan motors and air-conditioning apparatuses including such outdoor fan motors, and in particular to an outdoor fan motor in which water entry into the motor is suppressed and an air-conditioning apparatus including the outdoor fan motor.
Various motors have been hitherto proposed in each of which a stator includes a plurality of tooth portions provided with respective windings and arranged annularly (see Patent Literature 1 to 5, for example). Such Patent Literature is intended to realize a reduction in the number of components, a reduction in the number of manufacturing steps, or an increase in the reliability of the motor by improving the method of connecting the windings on the tooth portions and the method of connecting an end of each winding and a lead wire. There is another motor in which a stator is covered with a mold (see Patent Literature 6, for example). Since aluminum is lower in cost than copper, which is currently in common use for motors, there is yet another motor in which aluminum wires are employed as windings for the purpose of cost reduction.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2000-134844
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2000-324762
Patent Literature 3: Japanese Unexamined Patent Application Publication No. 2001-268843
Patent Literature 4: Japanese Patent No. 2603907
Patent Literature 5: Japanese Unexamined Patent Application Publication No. 7-46782
Patent Literature 6: Japanese Unexamined Patent Application Publication No. 11-275813
Supposing that the motor disclosed by any of Patent Literature 1 to 6 is applied to an outdoor fan motor of an outdoor unit included in an air-conditioning apparatus, it is necessary to consider the influence of water that may enter the motor. For example, even if the stator is covered with a mold as in the motor disclosed by Patent Literature 6, the probability of water entry cannot be eliminated completely. This is because it is necessary to extract lead wires to the outside of the mold so that electric power is supplied to the stator, and holes are accordingly provided in the mold. The lead wires may also be covered with the mold, and a portion of a terminal block may be embedded in the mold. Even in such a configuration, the probability of water entry cannot be eliminated completely.
If aluminum wires are employed as windings of a motor, the following problems should be considered as well.
(1) Since aluminum wires have low resistance to corrosion, if water or the like adheres to peripheral elements, the aluminum wires may corrode and eventually cause wire connection failure.
(2) The aluminum wires are each coated with enamel. The enamel coating over a portion of the aluminum wire is mechanically stripped, and the portion of the aluminum wire is twisted and dipped into solder. However, it is unclear whether or not the stripped portion is assuredly coated with the solder.
(3) Since the wires are each laid along a groove provided in the outer circumference of an insulator (also called spool), the wire is protected by a varnished tube or the like so that the occurrence of any damage to the enamel coating is prevented. However, since there is a gap between the varnished tube and the wire, water may enter the gap and may corrode the aluminum wire.
The present invention is to solve at least one of the above problems and to provide an outdoor fan motor in which water entry into the motor is suppressed and an air-conditioning apparatus including the outdoor fan motor.
An outdoor fan motor according to the present invention includes a stator including a plurality of cores in which aluminum wires are used as windings, a rotor rotatably provided on an inner circumferential side of the stator, a body outer shell as a resin mold that secures the stator, a terminal block provided to a bottom portion of the body outer shell and including terminals with which the stator and an external power source are connected to each other, and lead wires made of copper wires and connecting the terminals of the terminal block to the aluminum wires forming the windings. A varnished tube is provided on a side of each of the lead wires that is nearer to the terminal block. The water entry preventing member that closes a gap between the varnished tube and the lead wire is provided between the terminal block and the varnished tube.
An air-conditioning apparatus according to the present invention includes a fan provided in a casing and configured to take in air from an air inlet and to blow the air that has passed through a heat exchanger from an air outlet, the above outdoor fan motor that drives the fan, and a supporting member to which the outdoor fan motor is secured with a securing member.
In the present invention, since the water entry preventing member that closes the gap between the varnished tube and the lead wire is provided between the terminal block and the varnished tube, the probability of adhesion of water to the aluminum wires forming the windings in the resin mold is significantly reduced. Hence, according to the present invention, the life of the outdoor fan motor is extended.
According to the present invention, since the above outdoor fan motor is included, the reliability increases with the extension of the life of the outdoor fan motor.
Embodiment of the present invention will now be described with reference to the drawings.
The body outer shell 1 has an annular shape surrounding an axial center. The stator 20 is fixed to the inner side of the body outer shell 1. The rotor 30 (not illustrated) that is rotatably supported by a bearing is provided on the inner circumferential side of the stator 20. The body outer shell 1 serves as an outer shell of a molded stator that is obtained by forming a resin mold over the stator 20. The kind of the resin that forms the mold is not specifically limited and may be, for example, unsaturated polyester, saturated polyester, foaming resin, or the like. While Embodiment 1 concerns an exemplary case of integral resin molding, the forming method is not limited to resin molding and may be aluminum die casting or metal machining.
A plurality of leg portions 101 are provided at an end of the body outer shell 1 that is on a side of the bottom portion 2. The leg portions 101 project outward from the periphery of the body outer shell 1. The leg portions 101 are formed of the resin that forms the body outer shell 1 and are formed integrally with the body outer shell 1. The leg portions 101 are provided for fastening the body outer shell 1 to a supporting member with securing members such as screws. The supporting member employed herein corresponds to a plate member, a rail, or the like that is provided in an outdoor unit. In plan view, the leg portions 101 are each provided at a position where the terminal block 50 is not provided. The number of leg portions 101 is not specifically limited. A number of leg portions 101 that are sufficient to secure the motor 100 to the supporting member only need to be provided.
The bottom portion 2 is provided at the end of the body outer shell 1 (the end opposite the end from which the shaft 40 projects) in such a manner as to cover the end of the body outer shell 1. The bottom portion 2 has an opening in its center. The bottom portion 2 is formed of the resin that forms the body outer shell 1 and is formed integrally with the body outer shell 1. The terminal block 50 is provided on an exposed surface of the bottom portion 2 (a surface spreading along the outer periphery of the motor 100) as described above. The bottom portion 2 is formed such that, for example, a step is provided at the end of the body outer shell 1 or the bottom portion 2 forms an end facet of the body outer shell 1. A portion of the terminal block 50 is exposed on the bottom portion 2. The terminal block 50 has terminals with which the stator 20 and an external power source are connected to each other.
The terminal block 50 is provided such that, for example, a base portion thereof is embedded in the bottom portion 2. In such a case, the base portion that is embedded is on end facets of some of split cores (split cores 21 illustrated in
In Embodiment 1, since the lead wires 120 that are connected to the base portion of the terminal block 50 are covered with the mold formed of the resin that forms the body outer shell 1, the ease of production in the formation of the body outer shell 1 from resin is improved. Furthermore, since the terminal block 50 is provided in the bottom portion 2, the waterproofness is improved. Furthermore, since the leg portions 101 are each provided at a position where the terminal block 50 is not provided in plan view, wires connected to the terminal block 50 and the leg portions 101 do not interfere with each other, improving the ease of installation work.
Alternatively, for example, the terminal block 50 may be provided to the bottom portion 2 such that the base portion thereof is not embedded in the bottom portion 2. In such a case, however, exit portions for the lead wires 120 need to be provided on the bottom portion 2 or a side face of the body outer shell 1. Accordingly, water entry from the exit portions is more easily assumed. Therefore, it is more effective to take any of countermeasures to be described below.
While Embodiment 1 concerns an exemplary case where the split cores 21 that are connected annularly to form the stator 20, the present invention is not limited to such a case. For example, the stator 20 may include cores only some of which are separable or all of which are originally connected to one another. In either case, the stator 20 only needs to include aluminum wires that are concentratedly wound around tooth portions.
Now, an air-conditioning apparatus (an outdoor unit 300) including the motor 100 according to Embodiment 1 and a state of securing of the motor 100 will be described.
As illustrated in
In such a top-flow air-conditioning apparatus, dewdrops on the heat exchanger and water accumulated at the bottom of the casing 310 may be swirled up by the wind and may adhere to the motor that drives the fan 312. That is, simply providing the terminal block 50 to the bottom portion 2 is not enough as a countermeasure to the water problem. Although the base portion of the terminal block 50 is embedded in the bottom portion as described above, the bottom portion 2 cannot be sealed completely because there is a connection between the embedded portion and the exposed portion. Hence, it is desired to improve the waterproofness at the joint between the bottom portion 2 and the terminal block 50.
In
The length of the shaft 40 is set such that a predetermined gap is provided between the lower end of each of blades of the fan 312 and the supporting member 320. In Embodiment 1, the motor 100 is secured on the supporting member 320. Therefore, a length L of the shaft 40 can be made shorter than in a case where a central portion of the motor 100 is supported. By reducing the length of the shaft 40, the occurrence of axial shift of the fan 312 is suppressed. In the motor 100 according to Embodiment 1, the diameter in plan view (the diameter of the body outer shell 1) is smaller than a diameter R of a boss 312a of the fan 312. With such a configuration, the resistance of the wind blowing from the lower side toward the upper side of the motor is reduced.
The stator 20 basically includes a plurality of split cores 21 (split cores 21a to 21i) and windings 22 (windings 22a to 22c) that are concentratedly wound around the split cores 21. The split cores 21 each include a core back 23 having a substantially annular shape forming an outer circumferential portion thereof, and a tooth portion 25 projecting in the radial direction from the inner circumferential side of the core back 23. A slot 28 is provided between adjacent ones of the tooth portions 25.
The split cores 21 each have a substantially T shape. Portions of the respective split cores 21 that are connected annularly correspond to the core backs 23. The split cores 21 include the respective tooth portions 25 on inner circumferential portions thereof. The slot 28 is provided between adjacent ones of the tooth portions 25. The tooth portions 25 are provided with the windings 22 that are concentratedly wound therearound with non-illustrated insulators (also called spools) interposed therebetween. The stator 20 is connected to a three-phase (including U, V, and W phases) alternating-current power source (including an inverter) with the wires that are connected in, for example, the Y manner in advance. In the following description, the U phase corresponds to the winding 22a, the V phase corresponds to the winding 22b, and the W phase corresponds to the winding 22c.
The winding 22a for the U phase is wound around each of the split core 21a, the split core 21d, and the split core 21g. The windings 22a wound around the split core 21a, the split core 21d, and the split core 21g, respectively, are connected in series. A corresponding one of the lead wires 120 is connected to a leading end of the series of the windings 22a, whereby the series of the windings 22a is connected to the U phase via the lead wire 120. The lead wire 120 and the series of the windings 22a are connected to each other via a connected portion 121.
The winding 22b for the V phase is wound around each of the split core 21b, the split core 21e, and the split core 21h. The windings 22b wound around the split core 21b, the split core 21e, and the split core 21h, respectively, are connected in series. A corresponding one of the lead wires 120 is connected to a leading end of the series of the windings 22b, whereby the series of the windings 22b is connected to the V phase via the lead wire 120. The lead wire 120 and the series of the windings 22b are connected to each other via a connected portion 121.
The winding 22c for the W phase is wound around each of the split core 21c, the split core 21f, and the split core 21i. The windings 22c wound around the split core 21c, the split core 21f, and the split core 21i, respectively, are connected in series. A corresponding one of the lead wires 120 is connected to a leading end of the series of the windings 22c, whereby the series of the windings 22c is connected to the W phase via the lead wire 120. The lead wire 120 and the series of the windings 22c are connected to each other via a connected portion 121.
The ends of the lead wires 120 that are opposite the ends connected to the series of the windings 22a, the series of the windings 22b, and the series of the windings 22c are connected together and form respective neutral points. The lead wires 120, which are aluminum wires or copper wires, are laid along grooves provided in the outer circumferences of the non-illustrated insulators and are connected to the respective phases.
The motor 100 according to Embodiment 1 employs aluminum wires as the windings 22 and copper wires as the lead wires 120 that connect the windings 22 for the different phases to the terminal block 50. Since aluminum is lower in cost than copper, employing aluminum wires as the windings 22 leads to a cost reduction. However, aluminum wires have the following problem.
In the motor 100 in which the terminal block 50 is provided in the bottom portion 2 of the body outer shell 1, water that has been swirled up with the airflow that is produced by the fan 312 may adhere to the bottom portion 2. As described above, although the base portion of the terminal block 50 is embedded in the bottom portion 2, there is a gap between the embedded portion and the resin. Accordingly, water may enter the gap.
Copper is highly resistant to corrosion and does not corrode even if a small amount of water adheres thereto. However, since the motor 100 employs aluminum wires, such aluminum wires may corrode even with a small amount of water. If the corrosion of the aluminum wires progresses, wire connection failure may occur eventually. In addition, it should be noted that, although aluminum wires are each coated with enamel and portions of the respective aluminum wires from which the enamel coatings are mechanically stripped are twisted and dipped into solder, it should be borne in mind that whether or not the stripped portions are assuredly coated with the solder is uncertain, depending on the control accuracy.
If the lead wires 120 are also made of aluminum wires that are each coated with enamel, the following problem may also occur. As described above, the lead wires 120 are laid along the grooves provided in the outer circumferences of the insulators. Hence, to prevent the occurrence of damage to the enamel coatings, a varnished tube or the like is provided over each of the lead wires 120, whereby the enamel coating is protected. However, there is also a gap between the varnished tube and the lead wire 120, and water may enter the gap. Note that at least three grooves are provided in the outer circumference of each insulator so that the lead wires 120 connected to the respective phases can be laid therealong.
As can be seen from the state of wire connection of the known stator 20′ illustrated in
However, with the stator 20′, the probability that water having entered from the terminal block 50′ may reach the aluminum wires forming the windings 22′ is not completely eliminated. That is, since there is only a short distance between the terminal block 50′ and a connected portion 121′ that is formed between each of the aluminum wires forming the windings 22′ and a corresponding one of the lead wires 120′, water that has entered from the terminal block 50′ may run along the lead wires 120′ and reach the aluminum wires forming the windings 22′ via the connected portions 121′.
Typically, the position where the terminal block 50′ is to be provided is predetermined. This also applies to the terminal block 50 of the stator 20. In general, the connected portions 121′ are each obtained by winding the aluminum wire around the lead wire 120′. This also applies to the connected portions 121 of the stator 20, because aluminum wires are easier to process than copper wires.
Hence, in the motor 100, as illustrated in
Hence, in the motor 100, a cost reduction is realized with the aluminum wires employed as the windings 22. Furthermore, since the lead wires 120 made of copper wires and the windings 22 made of aluminum wires are connected to each other at positions far from the terminal block 50, the probability that water having entered from the terminal block 50 may reach the aluminum wires is minimized. Therefore, the life of the motor 100 is extended. While the above description concerns a countermeasure to water entry in the case of Y-connection, the above countermeasure to water entry is also applicable to a case of delta (Δ)-connection.
In each of the stators 20′ of the respective types illustrated in
Hence, in each of the motors 100 that are of the respective slot types, the connected portions 121 between the aluminum wires forming the windings 22 and the lead wires 120 are provided as far as possible from the terminal block 50 as described above. Furthermore, in the motor 100, the lead wires 120 that are made of copper wires have large lengths, whereby water that has entered from the terminal block 50 is prevented from reaching the aluminum wires forming the windings 22.
In the six-slot type illustrated in
In the nine-slot type illustrated in
In the twelve-slot type illustrated in
As described above, regardless of the slot type of the motor 100, the leading end of the aluminum wire forming the winding 22 for each of the phases resides on one of the split cores 21 that is not adjacent to the split core 21 on which the terminal block 50 is provided. Therefore, in the motor 100, the lead wires 120 that are made of copper wires have large lengths, whereby water that has entered from the terminal block 50 is prevented from reaching the aluminum wires forming the windings 22. Hence, in the motor 100, a cost reduction is realized with the aluminum wires employed as the windings 22. In addition, since each of the lead wires 120 made of copper wires and a corresponding one of the aluminum wires are connected to each other at a position far from the terminal block 50, the probability that water having entered from the terminal block 50 may reach the aluminum wires is minimized. Consequently, the life of the motor 100 is extended.
As described above, to provide the connected portions 121 at positions far from the terminal block 50, the leading end of the winding 22 for each of the phases is desired to be at a position opposite the terminal block 50, that is, a position at 180 degrees or more about the center of rotation. However, the leading end of the winding 22 for each of the phases only needs to reside on one of the split cores 21 that is not adjacent to the split core 21 on which the terminal block 50 is provided.
The description in [Countermeasure 1 to Water Entry] concerns an exemplary case where the connected portions 121 are provided far from the terminal block 50, whereby water that has entered from the terminal block 50 is prevented from reaching the aluminum wires forming the windings 22. In [Countermeasure 2 to Water Entry], the gap between the varnished tube and each of the lead wires 120 is closed, whereby water that has entered from the terminal block 50 is prevented from reaching the aluminum wires forming the windings 22.
As described above, to prevent the occurrence of damage to the enamel coating, a varnished tube or the like is provided over each of the lead wires, whereby the enamel coating is protected. However, there is also a gap between the varnished tube and the lead wire, and water may enter the gap. That is, in the known example illustrated in
Accordingly, in the motor 100 illustrated in
Typically, as illustrated in
The water entry preventing members 90 may each be molded from resin such as unsaturated polyester, saturated polyester, foaming resin, or the like. The water entry preventing member 90 may also serve as, for example, the adhesive or the like that is used to fix the varnished tube 70. That is, the water entry preventing member 90 may be made of a material that can close the gap 80.
Hence, in the motor 100, a cost reduction is realized with the aluminum wires employed as the windings 22. Moreover, since the water entry preventing member 90 is provided over each of the lead wires 120 that are connected to the terminal block 50, the probability that water having entered from the terminal block 50 may reach the aluminum wires is minimized. Therefore, the life of the motor 100 is extended.
The water entry preventing member 90 only needs to close the gap 80, and the size, shape, material, and other factors thereof are not specifically limited. The varnished tube 70 may be of a generally available type. Alternatively, a sheet of varnish may be rolled into a cylinder, which may be employed as the varnished tube 70. Furthermore, the varnished tube 70 may contain a heat-shrinkable material.
In [Countermeasure 3 to Water Entry], a dehumidifying agent or varnish is applied to the connected portions 121 and joined portions 122, whereby water having entered from the terminal block 50 is prevented from reaching the aluminum wires forming the windings 22.
The connected portions 121 are each formed by connecting the aluminum wire and the copper wire to each other by twisting the two together. To allow the aluminum wire and the copper wire to be electrically continuous with each other, enamel coatings provided over a portion of the aluminum wire and a portion of the copper wire that are to form the connected portion 121 are mechanically stripped. Subsequently, the aluminum wire and the copper wire are twisted together, whereby the connected portion 121 is formed. Then, the connected portion 121 is dipped into solder. If the connected portion 121 is assuredly coated with solder, since the solder corrodes before the aluminum wire corrodes in the event of water reaching the connected portion 121, the aluminum wire does not corrode as long as the solder is present. Instead of mechanically stripping the enamel coating of the copper wire, the enamel coating of the copper wire may be thermally stripped simultaneously with the solder dipping.
The joined portions 122 are each formed by connecting the aluminum wires forming the windings 22 for the same phase to each other by twisting the two together. To allow the aluminum wires to be electrically continuous with each other, enamel coatings provided over portions of the respective aluminum wires that are to form the joined portion 122 are mechanically stripped. Subsequently, the aluminum wires are twisted together, whereby the joined portion 122 is formed. Then, the joined portion 122 is dipped into solder. If the joined portion 122 is assuredly coated with solder, since the solder corrodes before the aluminum wires corrodes in the event of water reaching the joined portion 122, the aluminum wires do not corrode as long as the solder is present.
Depending on the control accuracy in solder dipping, however, it is unclear whether or not the connected portion 121 and the joined portion 122 are assuredly coated with the solder. For example, if any of the aluminum wires includes a portion of even 1 mm in length that is not coated with the solder and if water adheres to that portion, the corrosion of the aluminum wires forming the connected portion 121 and the joined portion 122 will progress.
Hence, in the motor 100, at least one of a dehumidifying agent and varnish is applied to the connected portion 121 and the joined portion 122 so that no portions of the aluminum wires are exposed. Thus, in the motor 100, portions of the aluminum wires that are to form the connected portion 121 and the joined portion 122 with their enamel coatings stripped are prevented from being exposed. Consequently, water having entered from the terminal block 50 is prevented from reaching the aluminum wires forming the windings 22.
Hence, in the motor 100, a cost reduction is realized with the aluminum wires employed as the windings 22. In addition, since the exposure of the aluminum wires in portions that are to form the connected portion 121 and the joined portion 122 is avoided, the probability that water having entered from the terminal block 50 may reach the aluminum wires is minimized. Consequently, the life of the motor 100 is extended.
While the dehumidifying agent may be a generally available, highly moisture-resistant, insulating coating whose chief component is acryl, polyurethane, or the like, it is preferred that the dehumidifying agent have an excellent quick-drying characteristic. While the varnish may be a generally available varnish, it is preferred that the varnish have an excellent quick-drying characteristic. Furthermore, at least one of the dehumidifying agent and the varnish only needs be applied. Alternatively, both of the two may be applied.
In Embodiment 1, the individual countermeasures to water entry from the terminal block 50, specifically, [Countermeasure 1 to Water Entry] to [Countermeasure 3 to Water Entry], have been described separately. The motor 100 may include any one of or any combination of those countermeasures.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/002733 | 4/20/2012 | WO | 00 | 6/27/2014 |
