JP2009225601A - Mold motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold motor capable of attaining long life and high reliability by preventing electric corrosion of bearings with a simple structure. <P>SOLUTION: The mold motor 100 includes a mold stator 20 in which a stator portion 10 with an attachment winding 2 wound around an insulation member 8 and a mold resin portion 3 are integrally formed at a stator core 1 and which has an opening portion at either edge portion in an axial direction, a substrate 5 fixed at an edge portion on the opening portion side of the mold stator 20 and having an inverter part, a rotor assembly 30 which is inserted into the mold stator 20 from the opening portion and has a rotor 4, a shaft 11 engaged with a shaft hole of the rotor 4, and two bearings 7a, 7b fixed at the shaft 11 and positioned outside both edge portions in the axial direction of the rotor 4 , a bracket 6 which retains the bearing 7a and is fixed at the edge portion in the axial direction on an opening portion side of the mold stator 20, and a dielectric plate 15 provided between the substrate 5 and the bracket 6 and having a predetermined dielectric constant and a predetermined thickness. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a molded electric motor used for an air conditioner or a water heater. More specifically, the present invention relates to a structure that suppresses the occurrence of electrolytic corrosion in a bearing of a molded electric motor.

  A fan motor that drives a blower used in an air conditioner is required to be highly efficient with energy saving of the air conditioner body. Therefore, a high-efficiency brushless DC motor (an example of a molded motor) is often used instead of the induction motor. As a method for driving the brushless DC motor, a PWM method (Pulse Width Modulation) is often used.

  When the PWM method is used, a high frequency switching voltage is applied to the mold motor, so that a potential difference is generated between the inner and outer rings of the bearing and discharge occurs. This discharge may cause wavy wear on the rolling surface of the bearing.

  The electric current flows from the periphery of the bearing into the bearing and sparks are generated on the rolling contact surface, and the damage caused on the bearing rolling surface is called electrolytic corrosion. This spark creates round spots on the surface at an early stage. These round spots are white layers, altered layers, tempered layers, etc. due to the heat effect of sparks, and they have different metal structures and hardness from the surrounding normal parts, and may develop into peeling afterwards. . Further, when the electrolytic corrosion further progresses, a corrugated horizontal striped pattern is generated, causing abnormal noise and vibration, and cannot function as a bearing. Due to this phenomenon, an abnormal noise is generated from the mold motor, and there is a problem that the product becomes defective.

In order to solve such problems, a stator winding in which a winding is wound around a stator iron core insulated with resin, and the stator winding is molded integrally with insulating resin to hold the bearing. In a finished molded product having a housing, a brushless motor or stator winding having one bearing of a rotatable rotor having a pair of bearings inside the housing portion and the other bearing fixed by a bracket. Brushless wire is molded and molded with insulating resin without providing a housing to hold the bearing, and both bearings of a rotatable rotor with a pair of bearings are inserted and fixed in a bracket press-fitted into the finished mold In a DC motor, a brushless DC motor has been proposed in which the stator iron core has a structure in which the bracket is short-circuited via the iron core connection terminal and the bracket connection terminal (for example, Patent reference 1).
JP 2007-159302 A

  However, the brushless DC motor described in Patent Document 1 requires an iron core connection terminal and a bracket connection terminal in order to short-circuit the stator iron core and the bracket. It was.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a molded motor having a long life and high reliability by preventing the electrolytic corrosion of the bearing with a simple structure.

In the molded motor according to the present invention, a stator portion in which an insulating member is attached to a stator core formed by laminating electromagnetic steel plates and a winding is applied, and a mold resin are integrally formed, and one end in the axial direction is formed. A mold stator having an opening in the part;
A substrate that is fixed to an end of the mold stator on the opening side and has an inverter;
The rotor is inserted into the mold stator through the opening, the rotating shaft is fitted into the shaft hole of the rotor, and the two bearings are fixed to the rotating shaft and are located outside the both axial ends of the rotor. A rotor assembly having;
A bracket that holds one of the bearings and is fixed to an axial end on the opening side of the mold stator;
A dielectric plate having a predetermined dielectric constant and a predetermined thickness is provided between the substrate and the bracket.

  In the molded motor according to the present invention, by providing a dielectric plate having a predetermined dielectric constant and a predetermined thickness between the substrate and the bracket, the stray capacitance between the inverter unit and the bracket can be reduced. There is an effect of preventing the occurrence of electric corrosion and suppressing the generation of noise, and providing a long-life and highly reliable mold motor.

Embodiment 1 FIG.
1 to 4 are diagrams showing the first embodiment. FIG. 1 is a partial cross-sectional view of the mold motor 100. FIG. 2 is a perspective view of the stator unit 10 before the board 5 is attached. FIG. 4 is a schematic diagram of an electric circuit of the molded electric motor 100 represented simply.

  As shown in FIG. 1, the mold motor 100 includes a mold stator 20, a rotor assembly 30, and a bracket 6.

  The mold stator 20 is integrally formed by applying the mold resin 3 to the stator portion 10.

  As shown in FIGS. 1 to 3, the stator portion 10 is formed by laminating electromagnetic steel plates, and an insulating member 8 is attached to a stator core 1 having a plurality of slots (not shown). Line 2 is applied. Furthermore, a substrate 5 on which electronic components (such as switching elements constituting an inverter) for driving the molded motor 100 are mounted is attached to one axial end surface of the insulating member 8. The thing of this state is called the stator part 10. FIG.

  The substrate 5 is fixed to a protrusion 18 of the insulating member 8 that extends outward in the axial direction from one axial end of the insulating member 8. The shape of the board | substrate 5 is a substantially disc shape which has an opening part in the center part.

  The rotor assembly 30 includes a rotor 4 having permanent magnets (not shown), a shaft 11 (rotary shaft) that fits in a shaft hole formed in a substantially central portion of the rotor 4, and the shaft 11. Two bearings 7a and 7b which are fixed and are located outside both axial ends of the rotor 4 are provided. The bearing 7 a is held by the bracket 6. The bearing 7b is held by the mold resin 3. The rotor 4 is a permanent magnet type rotor using a permanent magnet, for example. The bearing 7 a includes an outer ring 7 a-1 fitted to the bracket 6 and an inner ring 7 a-2 fitted to the shaft 11. The same applies to the bearing 7b.

  For example, ball bearings are used as the bearings 7a and 7b. Ball bearings are bearings in which rolling elements use balls, and there are radial ball bearings and thrust ball bearings depending mainly on the direction of the load received. Bearings 7a and 7b shown in FIG. 1 are radial ball bearings. Radial ball bearings include deep groove ball bearings, angular contact ball bearings, 4-point contact ball bearings, self-aligning ball bearings, and other bearings.

  The axial end of the mold stator 20 on the substrate 5 side is closed with the mold resin 3 (however, a hole through which the shaft 11 is passed is opened). Since the other axial end of the mold stator 20 is open, the rotor assembly 30 is inserted into the mold stator 20 from this opening side. Further, the metal bracket 6 is attached to the opening side of the mold stator 20. The bracket 6 is attached so that the rotor assembly 30 is sandwiched between the bracket 6 and the mold resin 3, and the mold electric motor 100 is completed.

  FIG. 4 is a simplified model diagram of an electric circuit of the molded motor 100. The example shown in FIG. 4 is a model corresponding to the bearing 7 a on the opening side of the mold stator 20. Note that the bearing 7b opposite to the opening side of the mold stator 20 is a similar model.

  Each component of the mold motor 100 has a stray capacitance (capacitance) and is electrically connected to each other. By applying the output voltage of the inverter unit 5a from the substrate 5 on which the drive element of the inverter unit 5a is mounted to the winding 2 of the stator unit 10, the stray capacitance is combined between the inner and outer rings of the bearings 7a and 7b. Voltage is generated.

The stray capacitance between the components of the molded motor 100 includes the following.
(1) stray capacitance 22: stray capacitance between inverter unit 5a and stator core 1 (2) stray capacitance 23: stray capacitance between stator core 1 and rotor 4 (3) stray capacitance 25: stator core 1 Floating capacitance between brackets (4) Floating capacitance 26: Floating capacitance between inverter 5a and bracket 6 (5) Floating capacitance 27: Floating capacitance between outer ring 7a-1 and inner ring 7a-2 of bearing 7a (6) Floating capacitance Capacitance 21: Other stray capacitance

  For example, when the potential difference between the outer ring 7a-1 and the inner ring 7a-2 of the bearing 7a exceeds a certain value, the grease is discharged due to dielectric breakdown of the grease of the bearing 7a (the same applies to the bearing 7b). Due to the energy of this discharge, the rolling surface of the bearing 7a is scratched, resulting in a phenomenon of electrolytic corrosion. By repeating this discharge, abnormal noise is generated in the mold motor 100.

  Each stray capacity varies depending on the structure of the molded motor 100. In the model of the bearing 7a in FIG. 4, the total stray capacity between the outer ring 7a-1 and the inner ring 7a-2 of the bearing 7a is the outer ring 7a-1 of the bearing 7a. And the stray capacitance 27 between the inner ring 7a-2 and the stray capacitance of the system in contact with the outer ring 7a-1 and the inner ring 7a-2 of the bearing 7a. When the structure of the molded electric motor 100 is different, the floating capacity of each system of the outer ring 7a-1 and the inner ring 7a-2 of the bearing 7a changes. It is possible to suppress electrolytic corrosion by reducing these stray capacitances.

  In the first embodiment, the stray capacitance 26 (stray capacitance between the inverter unit 5a and the bracket 6) is reduced in the stray capacitance of each system. In the molded electric motor 100 of FIG. 1, the positions of the bracket 6 in the stator portion 10 and the substrate 5 including the inverter portion 5 a are arranged on the opposite sides with respect to the axial direction of the shaft 11. The distance between the bracket 6 and the substrate 5 provided with the inverter unit 5a is larger than when the bracket 6 is in the vicinity of the substrate 5.

  By adopting such a structure, by increasing the distance between the substrate 5 (which includes the inverter unit 5a) which is a high-frequency generation source and the metal bracket 6 which serves to promote the discharge of the bearing 7a. The stray capacitance 26 (stray capacitance between the inverter unit 5a and the bracket 6) becomes small.

The capacitance C of the parallel plate conductor is expressed by the following equation.
C = εS / d (1)
Here, ε is the dielectric constant of the dielectric, S [m ² ] is the area of the parallel plate conductor, and d [m] is the interval between the parallel plate conductors.

  By disposing the bracket 6 in the stator portion 10 and the substrate 5 having the inverter portion 5a on opposite sides with respect to the axial direction of the shaft 11, d in the formula (1) can be sufficiently large and static. The electric capacity C becomes small and the electric corrosion is suppressed. Thereby, the long-term reliability of the mold motor 100 is improved, and the long-life mold motor 100 can be provided.

Embodiment 2. FIG.
FIG. 5 shows the second embodiment, and is a partial cross-sectional view of the molded electric motor 100. The mold motor 100 shown in FIG. 5 is different from the mold motor 100 shown in FIG. 1 in that the position of the bearing 7b is separated from the substrate 5 in the axial direction and is arranged on the end side in the axial direction of the mold resin 3. . Other configurations are the same as those of the molded electric motor 100 of the first embodiment.

  The substrate 5 and the bearing 7b are separated by a dimension G (predetermined dimension) in the axial direction. Thereby, the stray capacitance between the inverter unit 5a and the bearing 7b is reduced, and the occurrence of electrolytic corrosion can be suppressed.

  In the molded electric motor 100 of the second embodiment, the positions of the bracket 6 and the substrate 5 including the inverter unit 5a in the stator unit 10 are arranged on opposite sides with respect to the axial direction of the shaft 11 as in the first embodiment. Has been. The substrate 5 and the bearing 7b are separated from each other by a dimension G (predetermined dimension) in the axial direction. Thereby, the long-term reliability of the mold motor 100 is further improved, and the long-life mold motor 100 can be provided.

Embodiment 3 FIG.
FIG. 6 shows the third embodiment, and is a partial cross-sectional view of the molded electric motor 100. The mold motor 100 shown in FIG. 6 is different from the mold motor 100 shown in FIG. 5 in that a bracket 16 (second bracket) different from the bracket 6 (first bracket) is provided on the substrate 5 side. Different.

  Since the mold motor 100 shown in FIG. 6 includes the bracket 16 integrally formed with the mold resin 3 as compared with the mold motor 100 shown in FIG. 5, the coaxiality of the shaft 11 is improved.

  As shown in FIG. 6, when the bracket 16 is disposed in the vicinity of the substrate 5, if the bracket 16 is made of metal, high-frequency leakage current easily flows from the inverter portion 5 a of the substrate 5 through the stray capacitance. Therefore, stray capacitance can be reduced by making the bracket 16 a non-conductive (for example, resin) material, and the occurrence of electrolytic corrosion can be suppressed.

  By making the bracket 16 a non-conductive (for example, resin) material, the area S of the equation (1) is reduced and the stray capacitance is reduced.

Embodiment 4 FIG.
7 and 8 are diagrams showing the fourth embodiment. FIG. 7 is a partial cross-sectional view of the mold motor 100. FIG. 8 is a partial cross-sectional view of the mold motor 100 according to a modification. In the molded motor 100 shown in FIG. 7, first, the insulating member 8 is attached to the stator core 1, and the stator portion 10 provided with the winding 2 is molded with the mold resin 3 and is formed at one end in the axial direction. Let it be a mold stator 20 having an opening. Next, the protrusion 18 of the insulating member 8 extending outward in the axial direction from one axial end portion (end portion on the opening side) of the insulating member 8 is protruded from the mold stator 20. The substrate 5 including the inverter unit 5a is fixed to the protrusion 18 of the insulating member 8.

  The rotor assembly 30 is inserted into the mold stator 20 from the opening side of the mold stator 20. And the bracket 6 is attached to the opening part side of the mold stator 20, and the mold electric motor 100 is completed.

  The mold motor 100 of FIG. 7 has the board | substrate 5 provided with the inverter part 5a, and the bracket 6 in the opening part side of the mold stator 20, and the arrangement | positioning which approached.

  Therefore, the stray capacitance 26 between the inverter unit 5a and the bracket 6 of the molded motor 100 of FIG. 7 is larger than that of the molded motor 100 shown in FIG.

  Therefore, as shown in FIG. 7, a dielectric plate 15 having a predetermined dielectric constant and a predetermined thickness is inserted between the substrate 5 and the bracket 6. The material of the dielectric plate 15 is, for example, resin, ceramic, mica, fiber, mineral, oil, or the like. The relative dielectric constant of these materials is, for example, 2 for Teflon (registered trademark), 1.3-2 for silk, 1.4-1.5 for asbestos, 2.4-4.1 for ABS resin, polyethylene pellets Is about 1.7 (vacuum relative permittivity is 1). When these are combined, the dielectric constant of the dielectric plate 15 is about 1.3 to 4.1.

  By inserting the dielectric plate 15 between the substrate 5 and the bracket 6, the stray capacitance 26 between the inverter unit 5a and the bracket 6 is reduced, and the occurrence of electrolytic corrosion can be prevented.

  FIG. 8 shows a modified mold motor 100. In the molded electric motor 100 of FIG. 8, the portion of the dielectric plate 15 of FIG. Other configurations are the same as those in FIG.

  The dielectric constant of the air layer 14 is smaller than that of the dielectric plate 15 and is substantially equal to the dielectric constant of vacuum. Therefore, S / d in the equation (1) can be increased accordingly.

Since the relative dielectric constant of the dielectric plate 15 is about 1.3 to 4.1 as described above, in order to make the stray capacitance of the air layer 14 equal to the stray capacitance of the dielectric plate 15, the equation (1) S [m ² ] / d [m] may be 1.3 to 4.1 times that of the dielectric plate 15. For example, if S is constant, d can be shortened to 1 / (1.3 to 4.1) times. Thereby, size reduction of the mold electric motor 100 can be achieved.

  By setting the air layer 14 that satisfies the above conditions between the substrate 5 and the bracket 6, the stray capacitance 26 between the inverter 5a and the bracket 6 can be reduced, and the occurrence of electrolytic corrosion can be prevented.

Embodiment 5 FIG.
FIG. 9 is a diagram showing the fifth embodiment, and is a configuration diagram of the air conditioner 200. The air conditioner 200 includes an indoor unit 52 and an outdoor unit 53 connected to the indoor unit 52. The outdoor unit 53 is provided with a blower 54. Although not shown, the indoor unit 52 also includes a blower.

  The molded motor 100 according to any one of the first to fourth embodiments is mounted on the blower 54 of the outdoor unit 53 and the blower of the indoor unit 52.

  Long-term reliability is improved by suppressing electrolytic corrosion, and reliability of the air conditioner 200 is improved by mounting the long-life molded motor 100.

Embodiment 6 FIG.
FIG. 10 is a diagram illustrating the sixth embodiment, and is a configuration diagram of the water heater 300. The water heater 300 includes an outdoor unit 55, a tank 56, and a bathtub 57.

  The outdoor unit 55 is equipped with a blower 58. Then, the mold motor 100 according to any one of the first to fourth embodiments is mounted on the blower 58.

  Long-term reliability is improved by suppressing electrolytic corrosion, and reliability of the water heater 300 is improved by mounting the long-life mold motor 100.

FIG. 5 shows the first embodiment, and is a partial cross-sectional view of the molded electric motor 100. FIG. 5 shows the first embodiment, and is a perspective view before the substrate 5 of the stator portion 10 is attached. FIG. 5 shows the first embodiment, and is a perspective view after the substrate 5 of the stator portion 10 is attached. FIG. 3 is a diagram illustrating the first embodiment, and is a model diagram of an electric circuit of the molded electric motor 100 simply illustrated. FIG. 5 shows the second embodiment, and is a partial cross-sectional view of the molded electric motor 100. FIG. 5 shows the third embodiment and is a partial cross-sectional view of the molded electric motor 100. FIG. 5 is a diagram showing the fourth embodiment, and is a partial cross-sectional view of a molded electric motor 100. It is a figure which shows Embodiment 4, and is a fragmentary sectional view of the mold motor 100 of a modification. FIG. 9 shows the fifth embodiment and is a configuration diagram of an air conditioner 200. FIG. 10 shows the sixth embodiment and is a configuration diagram of a water heater 300.

Explanation of symbols

  1 Stator Iron Core, 2 Windings, 3 Mold Resin, 4 Rotor, 5 Substrate, 5a Inverter, 6 Bracket, 7a Bearing, 7a-1 Outer Ring, 7a-2 Inner Ring, 7b Bearing, 8 Insulating Member, 10 Stator Part, 11 shaft, 14 air layer, 15 dielectric plate, 16 bracket, 18 protrusion, 21 stray capacity, 22 stray capacity, 23 stray capacity, 25 stray capacity, 26 stray capacity, 27 stray capacity, 30 rotor assembly, 52 interior Machine, 53 outdoor unit, 54 blower, 55 outdoor unit, 56 tank, 57 bathtub, 58 blower, 100 mold electric motor, 200 air conditioner, 300 water heater.

Claims (6)

A stator fixing part in which an insulating member is attached to a stator iron core formed by laminating electromagnetic steel plates and a winding is applied, and a mold resin are integrally formed, and a mold fixing having an opening at one end in the axial direction With the child,
A substrate that is fixed to an end of the mold stator on the opening side and has an inverter;
The rotor is inserted into the mold stator from the opening, and the rotor is fitted into the shaft hole of the rotor. The rotor is fixed to the rotor shaft and is positioned outside both ends in the axial direction of the rotor. A rotor assembly having two bearings;
A bracket that holds one of the bearings and is fixed to an axial end of the mold stator on the opening side;
A molded electric motor comprising a dielectric plate having a predetermined dielectric constant and a predetermined thickness, which is provided between the substrate and the bracket. 2. The mold motor according to claim 1, wherein an air layer satisfying the following condition is provided between the substrate and the bracket in place of the dielectric plate.
(A) When the area of the substrate is S and the distance between the substrate and the bracket is d, S [m ² ] / d [m] is the case where the air layer is composed of the dielectric plate. Compared to 1.3 to 4.1 times. An insulating member is attached to a stator iron core formed by laminating electromagnetic steel sheets, winding is performed, and a stator portion on which a substrate having an inverter portion is fixed to the insulating member, and a mold resin are integrally formed, and a shaft A mold stator having an opening at one end in the direction;
The rotor is inserted into the mold stator from the opening, and the rotor is fitted into the shaft hole of the rotor. The rotor is fixed to the rotor shaft and is positioned outside both ends in the axial direction of the rotor. A rotor assembly having two bearings;
A bracket that holds the one bearing and is fixed to an axial end of the mold stator on the opening side, and the substrate and the other bearing are arranged apart from each other by a predetermined dimension in the axial direction. Molded electric motor characterized by An insulating member is attached to a stator iron core formed by laminating electromagnetic steel sheets, winding is performed, and a stator portion on which a substrate having an inverter portion is fixed to the insulating member, and a mold resin are integrally formed, and a shaft A mold stator having an opening at one end in the direction;
The rotor is inserted into the mold stator from the opening, and the rotor is fitted into the shaft hole of the rotor. The rotor is fixed to the rotor shaft and is positioned outside both ends in the axial direction of the rotor. A rotor assembly having two bearings;
A first bracket that holds the one bearing and is fixed to an axial end of the mold stator on the opening side;
A mold electric motor comprising: a non-conductive second bracket that is integrally formed with the mold resin, on the opposite side of the mold stator to the opening side, which holds the other bearing.   An air conditioner equipped with the molded electric motor according to any one of claims 1 to 4.   A water heater equipped with the molded electric motor according to any one of claims 1 to 4.

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