JP2007159302A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a high-frequency electrolytic corrosion (a wavy abrasion phenomenon) occurs to a bearing in an air conditioner fan brushless motor for adopting a PWM drive system so as to improve the efficiency. <P>SOLUTION: In a stator of the brushless motor molded by an insulative resin, a capacitance between a shaft and a bracket can be reduced, and the high-frequency electrolytic corrosion (the wavy abrasion phenomenon) is prevented from occurring to the bearing since a stator iron core is short-circuited to the bracket through an iron core connecting terminal and a bracket connecting terminal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor that is mounted on an electric device such as an air conditioner and drives a blower fan.

For example, a fan motor mounted on an air conditioner for driving a blower fan has recently been demanded to be highly efficient with energy saving of the air conditioner body. As the fan motor, a high-efficiency brushless motor is often used instead of the induction motor. As a driving method of the brushless motor, pulse width modulation (Pulse)
In many cases, driving is performed by an inverter of a Width Modulation (hereinafter referred to as PWM).

  In adopting such PWM drive, when high-frequency electrolytic corrosion (hereinafter simply referred to as electrolytic corrosion) of a bearing for supporting a motor shaft proceeds, a wavy wear phenomenon may occur and lead to abnormal noise.

  A conventional brushless motor of this type includes a motor structure described in Japanese Patent Application Laid-Open No. 2004-242413, for example. A conventional brushless motor of this type will be described with reference to FIGS. FIG. 3 is a structural cross-sectional view of a conventional brushless motor, and FIG. 4 is a model diagram of the approximate distribution of stray capacitance of the brushless motor shown in FIG.

  In FIG. 3, a stator is formed by molding a stator core 11 around which a stator winding 12 is wound with an insulating resin 13. A rotor 14 is inserted inside the stator through a gap. Two bearings 15 are attached to the shaft 16 of the rotor 14. The two bearings 15 are respectively supported by a stator insulating resin 13 and a bracket 17. The rotor 14 can rotate with a shaft 16 supported by two bearings 15.

Further, the brushless motor has a built-in printed wiring board 18 on which a drive circuit is mounted, and a brushless motor is formed by press-fitting the bracket 17 into the stator.
JP 2004-242413 A

  However, in the conventional structure of this type of motor, stray capacitances C1 to C7 and the like exist between the constituent members as shown in FIG. When the stator winding 12 of such a conventional motor is driven by a PWM inverter, a through current flows through the stray capacitances C1 to C7. As a result, a potential difference occurs between the constituent members, and electrolytic corrosion may occur under certain conditions.

  As a condition where electric corrosion is particularly likely to occur, it may occur when the motor is operated for a long time in a region where the applied voltage is high (for example, a commercial power supply 240V region) at a relatively low temperature and with a small number of revolutions. Are known. An example of the mechanism by which electrolytic corrosion occurs is as follows.

When the stator winding 12 is driven by a PWM inverter, the stator core 11 to the stator winding 12, the printed wiring board 18, the bracket 17, the bearing 15, the shaft through the stray capacitances C1 to C7 between the constituent members. 16, a loop-shaped high-frequency circulating current that returns to the rotor 14 and the stator core 11 is generated.

  At that time, when the oil film of the grease as the lubricant is cut inside the bearing 15 or the oil film thickness becomes thin, a discharge phenomenon due to local dielectric breakdown occurs accordingly, and a minute discharge is generated on the transfer surface of the bearing 15. Scars are formed, which can lead to electrical corrosion when continued for a long time. The presence or absence of this discharge phenomenon is closely related to C3 or C6 when the voltage is divided by the stray capacitances C1 to C7, that is, the magnitude of the voltage applied to each bearing 15. Here, Vdc in the figure is a voltage applied to the printed wiring board 18.

  By repeating this galvanic phenomenon, the transfer surface of the bearing 15 becomes rough, and if it becomes wavy, it will eventually lead to abnormal noise of the motor. As an example of a method for surely preventing this, there is a method using a bearing using a ceramic ball which is a nonconductive material between the inner ring and the outer ring of the bearing.

  However, this ceramic ball bearing is very expensive and has not yet been used in mass production.

  Other methods include making the bearing grease conductive, grounding the stator core, and lowering the PWM drive carrier frequency.

  However, none of these methods are necessarily satisfactory in terms of reliability, cost, quality, and usability, and the fact is that they have not been adopted. As described above, countermeasures against electric corrosion are accompanied by an increase in bearing costs, an increase in material costs for motors, and a decrease in usability.

  In order to solve the above-described conventional problems, the present invention provides a stator winding in which a winding is wound around a stator core insulated with resin in a fan motor that is mounted on an air conditioner and drives a blower fan, for example. And a molded finished product provided with a housing for holding the bearing by integrally molding the stator winding described above with an insulating resin, and one of the rotatable rotors having a pair of bearings inside the housing portion The brushless motor having the other bearing and the other bearing fixed by the bracket, or the stator winding described above is molded integrally with an insulating resin without providing a housing for holding the bearing, and a pair of In a brushless motor in which both bearings of a rotatable rotor having bearings are inserted and fixed in brackets press-fitted into the finished molded product described above, the stator described above Heart is obtained by a structure for short-circuiting the bracket over the core connection terminal and the bracket connecting terminal.

  With this structure, the stator iron core and the bracket in FIG. 4 are short-circuited to have the same potential, so that the voltage applied to the bearing can be greatly reduced and the occurrence of electrolytic corrosion can be suppressed.

As described above, according to the brushless motor of the electric motor of the present invention, the stator winding in which the winding is wound around the stator iron core insulated with resin, and the stator winding described above with the insulating resin In a finished mold product in which a housing for holding a bearing is formed by integrally molding the mold, one housing of a rotatable rotor having a pair of bearings is held inside the housing portion, and the other bearing is a bracket. The fixed brushless motor or the stator winding described above is molded integrally with an insulating resin without providing a housing for holding the bearing, and both bearings of a rotatable rotor having a pair of bearings are In the brushless motor inserted and fixed in the bracket press-fitted into the finished mold product described above, the stator iron core described above has a bracket connected to the iron core connection terminal and the bracket connection terminal. It is possible to suppress the occurrence of the electrolytic corrosion by a structure in which circuited.

  For this reason, it is possible to provide a relatively simple and inexpensive measure without taking measures such as using a ceramic ball bearing, and it is possible to provide a brushless motor with a low-cost electric corrosion countermeasure. This method is most effective when the bracket on the printed circuit board side and the stator core are short-circuited.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a structural cross-sectional view of a motor according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged structural cross-sectional view of the periphery of an iron core connection terminal and a bracket connection terminal shown in FIG.

  A motor 80 shown in FIG. 1 is a fan motor for an air conditioner indoor unit (hereinafter referred to as an indoor unit motor). In FIG. 1, a motor 80 of the present embodiment includes a stator 70 formed by integrally molding a stator core 11 and a stator winding 12 wound around the stator core 11 with an insulating resin 13. The rotor 14 having the shaft 16, the first bearing 151 and the second bearing 152 for supporting the shaft 16, and the stator 70 are coupled to the first bearing 151 or the second bearing 152. The bracket 17 that holds at least one of the above, the iron core conduction terminal 19 that short-circuits the stator core 11 and the bracket 17, and the bracket conduction terminal 20 are included.

  Further, the configuration of the motor 80 will be described in detail with reference to FIGS. 1 and 2. An insulator 21 is inserted into the stator core 11, and then a stator winding 12 is wound. Further, the core connection terminal 19 is fixed to the insulator 21 and then contacted or welded to the outer peripheral portion of the stator core 11.

  The contact or welding between the stator iron core 11 and the iron core connection terminal 19 has no problem even before the stator winding is applied. Through this process, the stator iron core 11 and the iron core connection terminal 19 can be electrically connected to each other, and the stator 70 is formed by molding with the insulating resin 13 to form the stator 70. The fitting portion with the connection terminal 20 is exposed.

  Furthermore, the groove | channel which can support the bracket connection terminal 20 is provided in at least 1 place of the stator 70, the bracket connection terminal 20 is inserted in the positioned iron core connection terminal 19, and it fixes by soldering or welding, and a stator core is obtained. 11 and the bracket connection terminal 20 can be conducted.

  Thereafter, a printed wiring board 18 on which a drive circuit for driving the motor 80 is mounted is added to form a finished mold, and the bracket 17 is finally press-fitted and fixed to the stator 70. The bracket connection terminal 20 protrudes from the end surface of the finished mold product, and is structured to be fixed to the bracket 17 by deforming the bracket connection terminal 20 at the same time as the bracket 17 is press-fitted. As a result, the stator core 11 has a structure in which the bracket 17 is short-circuited through the core connection terminal 19 and the bracket connection terminal 20.

  Note that a thermoplastic resin (PET, PBT or the like) is used for the resin member 21, and an unsaturated polyester resin that is a thermosetting resin is used for the insulating resin 13.

On the other hand, a shaft 16 is press-fitted and fixed to the rotor 14. Furthermore, the shaft 1
6, two bearings that rotatably support the shaft 16, that is, a first bearing 151 and a second bearing 152 are attached.

  The finished mold in which the printed wiring board 18 is added to the stator 70, that is, the rotor 14 in which the first bearing 151 and the second bearing 152 are held on the shaft 16 with respect to the stator 70, through the gap. In this way, the motor 80 is configured. The first bearing 151 is held by the housing 30 formed on the stator 70, and the second bearing 152 is held by the bracket 17.

With this configuration, the stator core 11 and the bracket 17 are short-circuited through the iron core connection terminal 19 and the bracket connection terminal 20 to have the same potential, so that the voltage applied to the two bearings 151 and 152 is greatly reduced. As a result, the occurrence of electrolytic corrosion can be suppressed. Therefore, it is not necessary to take measures such as using a ceramic ball bearing, and it is possible to provide a motor that is relatively simple and inexpensive and has anti-corrosion measures. In addition, in this structure, as shown in FIG. 2, when the bracket 17 arrange | positioned at the printed wiring board 18 side and the stator core 11 are short-circuited, an effect becomes large.
(Embodiment 2)
FIG. 5 is a side view of the iron core connection terminal 19 in Embodiment 2 of the present invention, and FIG. 6 is a side view of the bracket connection terminal 20. In FIG. 5, the iron core connection terminal 19 has a shape obtained by bending a distance of the dimension K. This is an example to ensure contact with the stator core 11 according to FIG. In FIG. 6, the bracket connection terminal 20 has a structure in which an iron core connection part insertion hole 23 is provided in consideration of a fixed connection with the iron core connection terminal 19.

  In addition, these parts are preferably made of a spring-made material (for example, phosphor bronze), welded, or soldered brass.

By providing these two connecting parts, the stator core 11 and the bracket 17 can be reliably positioned and short-circuited.
(Embodiment 3)
7 and 8 are side views of the stator before molding (enlarged view before the stator core and core connecting terminal welding) and side views of the stator before molding in the third embodiment of the present invention. It is an enlarged view after a stator iron core and iron core connection terminal welding.

By pressing and fixing the iron core connection terminal 19 shown in FIG. 5 to the insulator 22, the iron core connection terminal 19 can be positioned and contacted with the stator iron core 11. Further, as shown in FIG. 8, the welded portion 24 is provided by spot welding or the like between the stator core 11 and the core connection terminal 19.
Thus, a structure in which the stator core 11 and the core connection terminal 19 are reliably short-circuited is possible.
(Embodiment 4)
9 and 10 are an enlarged view of a structural sectional view before insertion of the bracket connection terminal 20 and an enlarged view of the structural sectional view before insertion of the bracket 17 in Embodiment 4 of the present invention.

In FIG. 9, at least one notch is provided in the outer peripheral portion of the finished mold product, and the bracket connection terminal 20 can be accommodated there. Further, after the bracket connection terminal 20 is inserted into a designated place and fixed with the solder 24, it is press-fitted and fixed on both the inner diameter side and the outer diameter side of the bracket 17. When the bracket 17 is press-fitted, the bracket connection terminal 20 is configured such that the distance of the dimension L protrudes from the end face of the finished mold product, and the distance of the dimension L is deformed when the bracket 17 is press-fitted to make sure that the bracket contact terminal 20 contacts the bottom of the bracket. It is said. Finally, the stator core 11 can be structured to reliably short-circuit the bracket 17 via two types of terminals (iron core connection terminal 19 and bracket connection terminal 20).

Further, in the configuration of FIG. 10, a structure in which the dimension N of the bracket connection terminal 20 is longer than the dimension M of the bracket 17 allows the bracket connection terminal 20 to be seen even after the bracket 17 is inserted (after the motor is assembled). Therefore, it is possible to confirm conduction (short circuit) between the bracket 17 and the bracket connection terminal 17 (finally the stator core 11).
The continuity can be confirmed by a continuity check device such as a tester, a multimeter, or a ground continuity test device.
(Embodiment 5)
FIG. 11 is a front view of the completed stator before insertion of the bracket connection terminal 20 shown in FIG. 9 in the fifth embodiment of the present invention (enlarged view of the iron core connection terminal portion 19), and FIG. 12 is before insertion of the bracket shown in FIG. It is a front view (enlarged view of the bracket connection terminal 20 insertion part) of a stator completion. In FIG. 11, a portion of the insulating resin 13 is provided with a notch, and the bracket connection terminal 20 is inserted at that location, and positioning with the iron core connection terminal portion 19 is performed.

  In FIG. 12, when the bracket connection terminal 20 is fixed by soldering or welding, and when the bracket 17 is further press-fitted, the side surface of the bracket connection terminal 20 and the bracket 17 are prevented from applying stress to the solder fixing or welding fixing part. Both sides (inside and outside of the bracket: hatched area) are not in contact with each other.

(Embodiment 6)
13 is a structural cross-sectional view of the brushless motor according to the sixth embodiment of the present invention, and FIG. 14 is an enlarged structural cross-sectional view of the periphery of the iron core connection terminal 19 and the bracket connection terminal 20 shown in FIG. The example in the fan motor (henceforth "the motor for outdoor use") used in is shown. The difference from the indoor motor is that the iron core connection terminal 19 and the bracket connection terminal 20 are located below (lead wire side) in the figure, and the bearing on the opposite side of the bracket 17 is held by the bracket A25. It is that you are.

  The outdoor motor may be exposed to wind and rain depending on the usage environment, and there is a concern that water may enter the motor from the gap around the conductive pin. As one of the countermeasures against this, by positioning the core connection terminal 19 and the bracket connection terminal 20 so that they are on the lower side when the motor is installed, it is not directly exposed to wind and rain, so that water can enter the motor. Can be prevented.

In addition, it is widely known that the electric corrosion is often generated in the bearing closer to the printed circuit board 18, but for the reason described above, the bracket 17 is not the bracket A25 but the bracket connection terminal 20, the iron core connection. Since the effect of reducing the voltage applied to the bearing is greater when short-circuited to the stator core 11 via the terminal 19, this is also implemented in the outdoor motor. (Embodiment 7)
As an example of the electric apparatus according to the present invention, first, the configuration of an air conditioner indoor unit will be described in detail as a seventh embodiment.

  In FIG. 15, a brushless motor 201 is mounted in the casing 211 of the air conditioner indoor unit 210. A cross flow fan 212 is attached to the rotating shaft of the brushless motor 201. The brushless motor 201 is driven by a motor driving device 213. The brushless motor 201 is rotated by energization from the motor driving device 213, and the cross flow fan 212 is rotated accordingly. By the rotation of the cross flow fan 212, air conditioned by an indoor unit heat exchanger (not shown) is blown into the room. Here, as the brushless motor 201, for example, the one of the first to sixth embodiments can be applied.

The electric device of the present invention includes a brushless motor and a casing on which the brushless motor is mounted, and employs the motor of the present invention having the above-described configuration as a brushless motor.
(Embodiment 8)
Next, as an example of the electrical apparatus according to the present invention, the configuration of an air conditioner outdoor unit will be described in detail as an eighth embodiment.

  In FIG. 16, the air conditioner outdoor unit 301 has a brushless motor 308 mounted inside a housing 311. The brushless motor 308 has a fan 312 attached to a rotating shaft and functions as a fan motor for blowing air.

  The air conditioner outdoor unit 301 is partitioned into a compressor chamber 306 and a heat exchanger chamber 309 by a partition plate 304 erected on the bottom plate 302 of the housing 311. A compressor 305 is disposed in the compressor chamber 306. A heat exchanger 307 and the blower fan motor are disposed in the heat exchanger chamber 309. An electrical component box 310 is disposed above the partition plate 304.

  The blower fan 312 rotates with the rotation of the brushless motor 308 driven by the motor driving device 303 housed in the electrical component box 310, and the heat fan chamber 309 passes through the heat exchanger 307. To blow. Here, as the brushless motor 308, for example, the one of the first to sixth embodiments can be applied.

The electric device of the present invention includes a brushless motor and a housing on which the brushless motor is mounted, and employs the brushless motor of the present invention having the above-described configuration as a brushless motor.
(Embodiment 9)
Next, as an example of the electric apparatus according to the present invention, the configuration of the hot water heater will be described in detail as a ninth embodiment.

  In FIG. 17, a brushless motor 333 is mounted in a housing 331 of the water heater 330. A fan 332 is attached to the rotation shaft of the brushless motor 333.

  The brushless motor 333 is driven by a motor driving device 334. The brushless motor 333 is rotated by energization from the motor driving device 334, and the fan 332 is rotated accordingly. The rotation of the fan 332 blows air necessary for combustion to a fuel vaporization chamber (not shown). Here, as the brushless motor 333, for example, those of the first to sixth embodiments can be applied.

The electric device of the present invention includes a brushless motor and a casing on which the brushless motor is mounted, and employs the motor of the present invention having the above-described configuration as a brushless motor.
(Embodiment 10)
Next, as an example of the electrical apparatus according to the present invention, the configuration of the air cleaner will be described in detail as a tenth embodiment.

  In FIG. 18, a brushless motor 343 is mounted in the housing 341 of the air purifier 340. An air circulation fan 342 is attached to the rotation shaft of the brushless motor 343. The brushless motor 343 is driven by a motor driving device 344. The brushless motor 343 is rotated by energization from the motor driving device 344, and the fan 342 is rotated accordingly. Air is circulated by the rotation of the fan 342.

Here, as the brushless motor 343, for example, those of the first to sixth embodiments can be applied.

The electric device of the present invention includes a brushless motor and a casing on which the brushless motor is mounted, and employs the motor of the present invention having the above-described configuration as a brushless motor.
In the above description, the fan motor mounted on the air conditioner outdoor unit, the air conditioner indoor unit, the water heater, the air purifier, etc. is taken up as an example of the electric device according to the present invention. Needless to say, the present invention can also be applied to brushless motors mounted on various information devices and brushless motors used in industrial devices.

  The brushless motor according to the present invention has a structure in which the stator iron core and the bracket are short-circuited via the iron core connection terminal and the bracket connection terminal in the stator of the brushless motor molded with an insulating resin. It is possible to reduce, and the object is to prevent the electric corrosion and wavy wear phenomenon of the bearing.

  This is mainly a low-priced device that requires a long life and is effective for a brushless motor of an electric motor such as a fan motor mounted in an air conditioner indoor unit, an air conditioner outdoor unit, a water heater, an air purifier or the like.

Cross-sectional view of the structure of the brushless motor according to the first embodiment of the present invention Structure cross-sectional enlarged view of the periphery of the iron core connection terminal and bracket connection terminal shown in FIG. Cross-sectional view of the structure of a conventional brushless motor Model diagram of approximate distribution of stray capacitance of brushless motor Iron core connection terminal side view in Embodiment 2 of the present invention Side view of bracket connection terminal in embodiment 2 of the present invention Side view of stator before molding in Embodiment 3 of the present invention (enlarged view before stator core and core connection terminal welding) Side view of stator before molding in Embodiment 3 of the present invention (enlarged view after welding of stator core and core connection terminal) Enlarged view of the structural cross-sectional view before insertion of the bracket connection terminal in Embodiment 4 of the present invention The enlarged view of the structure sectional view before bracket insertion in Embodiment 4 of the present invention Front view of completion of stator before insertion of bracket connection terminal shown in FIG. 9 in Embodiment 5 of the present invention (enlarged view of iron core connection terminal portion) Front view of completed stator before bracket insertion shown in FIG. 10 according to Embodiment 5 of the present invention (enlarged view of bracket connection terminal insertion portion) Cross-sectional view of the structure of the brushless motor according to the sixth embodiment of the present invention Structural cross-sectional enlarged view of the periphery of the iron core connection terminal and bracket connection terminal shown in FIG. Structural diagram of electrical apparatus (air conditioner indoor unit) according to Embodiment 7 of the present invention Structural diagram of electrical apparatus (air conditioner outdoor unit) according to Embodiment 8 of the present invention Structure diagram of electrical apparatus (hot water heater) in Embodiment 9 of the present invention Structure diagram of electrical apparatus (air purifier) in Embodiment 10 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Stator iron core 12 Stator coil | winding 13 Insulation resin 14 Rotor 15 Bearing 16 Shaft 17 Bracket 18 Printed circuit board 19 Iron core connection terminal 20 Bracket connection terminal 21 Insulator 22 Solder 23 Core connection component insertion hole 24 Welding part 25 Bracket A
30 Housing 70 Stator 80 Motor 151 First Bearing 152 Second Bearing 201 Brushless Motor 210 Air Conditioner Indoor Unit 211 Housing 212 Cross Flow Fan 213 Motor Drive Device 301 Air Conditioner Outdoor Unit 302 Bottom Plate 303 Motor Drive Device 304 Partition Plate 305 Compression Machine 306 Compressor room 307 Heat exchanger 308 Brushless motor 309 Heat exchanger room 310 Electrical component box 311 Housing 312 Fan 330 Water heater 331 Housing 332 Fan 333 Brushless motor 334 Motor driving device 340 Air cleaner 341 Housing 342 Fan 343 Brushless motor 344 Motor drive device

Claims (9)

Molded product having a stator winding in which a winding is wound around a stator iron core insulated with resin, and a housing for holding a bearing by integrally molding the stator winding described above with insulating resin In the brushless motor having one bearing of a rotatable rotor having a pair of bearings inside the housing portion described above and the other bearing fixed by a bracket, the stator core described above is A brushless motor that is short-circuited to the bracket via the iron core connection terminal and the bracket connection terminal. 2. A brushless motor according to claim 1, wherein the stator winding is molded integrally with an insulating resin without providing a housing for holding the bearing, and a rotatable rotor having a pair of bearings. Both of the bearings are inserted into and fixed to a bracket press-fitted into the finished molded product described above. 3. The finished mold product according to claim 1 or 2, wherein the outer peripheral portion of the stator core and the core connection terminal are contact-fixed or weld-fixed, and then molded integrally with the mold. Brushless motor. 4. The brushless motor according to claim 1, wherein the outer peripheral portion of the stator core and the core connection terminal are contact-fixed or weld-fixed, and then the mold is integrally formed in the molded product, and the core connection terminal exposed from the mold end surface; 4. The brushless motor according to claim 1, wherein the bracket connection terminal is fixed by soldering or welding. 5. The brushless motor according to claim 1, wherein when the bracket connection terminal is inserted into the finished mold product, at least one bracket connection terminal protrudes from the mold end surface, and the bracket is press-fitted and fixed. 5. The brushless motor according to claim 1, wherein the connection terminal is deformed and becomes conductive. 6. The brushless motor according to claim 1, wherein the bracket connecting terminal portion inserted into the finished molded product is exposed from the outer peripheral side length of the bracket to the outer portion of the motor so that the bracket and the bracket are described even after the motor is assembled. 6. The brushless motor according to claim 1, wherein continuity between connection terminals can be confirmed. 6. The brushless motor according to claim 1, wherein the bracket connection terminal and the bracket connection terminal inserted into the finished mold product are fixed by soldering or welding, and when the bracket is press-fitted, stress is applied to the solder fixing or welding fixing part. The brushless motor according to claim 1 or 6, wherein the brushless motor is not applied. The brushless motor according to any one of claims 1 to 7, wherein PWM (Pulse) is used.
A brushless motor that is driven by an inverter driving method (hereinafter referred to as “PWM driving method”). An electric apparatus comprising the brushless motor according to any one of claims 1 to 8.

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