JP4879249B2 - Electric motor and air conditioner - Google Patents

Description

  The present invention relates to an electric motor rotor using a rolling bearing, and more particularly to an electric motor rotor suitable for an electric motor driven by an inverter. The present invention also relates to an electric motor using the rotor of the electric motor, a method for manufacturing the rotor of the electric motor, and an air conditioner equipped with the electric motor.

  Conventionally, when an electric motor is operated using an inverter, the carrier frequency of the inverter is set high for the purpose of reducing the noise of the electric motor that is generated due to switching of the transistors in the power circuit. As the carrier frequency is set higher, the shaft voltage generated on the shaft of the motor based on the high frequency induction increases, and the potential difference existing between the inner ring and the outer ring of the rolling bearing supporting the shaft increases. This makes it easier for current to flow through the rolling bearing. The current flowing through the rolling bearings causes corrosion called electro-corrosion on the rolling surfaces of both the inner and outer ring raceways and the rolling elements (balls and rollers rolling between the inner and outer rings), thereby deteriorating the durability of the rolling bearings. There was a problem.

  Therefore, in order to obtain an electric motor that is easy to assemble with a simple configuration that can prevent electric current from flowing through the rolling bearing provided between the shaft and the motor case and prevent electric corrosion from occurring in the rolling bearing. A stator around which a coil is wound, a frame for fixing the stator, a rotor facing the stator with a slight gap, and the rotor are fixed, and can be freely rotated via a rolling bearing. In an electric motor having a shaft to be supported and a bearing bracket that supports a rolling bearing via an insulating material, a concave portion is provided on a side of the bearing bracket that contacts the insulating material, and a convex portion corresponding to the concave portion of the bearing bracket is provided. There has been proposed an electric motor in which a convex portion of an insulating material is fitted and fixed to a concave portion of a bearing bracket (for example, see Patent Document 1).

In the case of an electric corrosion prevention type rolling bearing in which an insulating coating is formed on the inner ring fitting surface or the outer ring fitting surface of the rolling bearing, or both the inner ring fitting surface and the outer ring fitting surface, the peripheral surface of the inner ring fitting surface or the outer ring fitting surface. An anti-corrosion-type rolling bearing has been proposed in which the boundary surface between the peripheral surface and the chamfered portion exhibits a loosely tapered surface or an arc surface with a large curvature radius, and at least one fitting surface has an insulating coating of an inorganic compound by thermal spraying. (For example, refer to Patent Document 2).
JP 2000-156952 A JP 59-103023 A

  However, since the motor of Patent Document 1 has a configuration in which the bearing bracket supports the rolling bearing via an insulating material, it is necessary to provide a separate insulating material, which increases the number of components and increases the cost. There was a problem.

  Further, the electric corrosion prevention type rolling bearing of Patent Document 2 also has a loosely tapered surface or an arc surface having a large curvature radius at the peripheral surface of the inner ring fitting surface or the boundary surface between the peripheral surface of the outer ring fitting surface and the chamfered portion, and at least On the other hand, since an insulating coating of an inorganic compound is formed by thermal spraying on the fitting surface, there is a problem that the cost increases.

  The present invention has been made to solve the above-described problems. Productivity is improved by arranging a resin portion that integrally forms a rotor magnet, a shaft, and the like so as to extend between the shaft and the rolling bearing. An object of the present invention is to provide an electric motor rotor, an electric motor, a method for manufacturing the electric motor rotor, and an air conditioner that can suppress electric corrosion of rolling bearings without impairing quality.

In the rotor of the electric motor according to the present invention, the rotor magnet and shaft are integrally formed with the resin portion, and the rolling bearing is disposed on the shaft.
The resin portion is integrated so that the resin portion is interposed between the shaft and the rolling bearing.

  In the rotor of the electric motor according to the present invention, since the resin portion is formed between the shaft and the rolling bearing, there is an effect of preventing current flowing through the rolling bearing, suppressing electric corrosion, and preventing the generation of abnormal noise. . Moreover, since the insulation between the shaft and the rolling bearing is performed by the resin portion that integrates the magnet of the rotor and the shaft, the configuration is simple and the cost can be reduced.

Embodiment 1 FIG.
FIGS. 1 to 13 are diagrams showing the first embodiment. FIG. 1 is a sectional view of the electric motor 100, FIG. 2 is a perspective view of the stator 40, FIG. 3 is a sectional view of the rotor 20, and FIG. FIG. 5 is a view showing the resin magnet 22 of the rotor (FIG. 5A is a left side view, FIG. 5B is a cross-sectional view taken along line AA of FIG. 5A, and FIG. 5C is a right side view). 6 is a diagram showing the position detecting resin magnet 25 ((a) is a left side view, (b) is a front view, (c) is an enlarged view of part A in (b)), and FIG. 7 is a modification. 8 is a cross-sectional view of the rotor 20 of the second modification, FIG. 9 is a cross-sectional view of the rotor 20 of the third modification, and FIG. 10 is a cross-section of the rotor 20 of the fourth modification. 11 is a cross-sectional view of a rotor 20 according to a fifth modification, FIG. 12 is a configuration diagram of a drive circuit 200 for driving the electric motor 100, and FIG.

  The configuration of the electric motor 100 will be described. As shown in FIG. 1, the electric motor 100 includes a mold stator 10, a rotor 20 (defined as a rotor of the electric motor), and a metal bracket 30 attached to one axial end of the mold stator 10. Prepare. The electric motor 100 is, for example, a brushless DC motor having a permanent magnet in the rotor 20 and driven by an inverter.

  The mold stator 10 is open at one axial end (right side in FIG. 1). The rotor 20 is inserted from this opening. A hole (not shown) slightly larger than the diameter of the shaft 23 of the rotor 20 is formed in the other axial end portion (left side in FIG. 1) of the mold stator 10. In the rotor 20 inserted from one end of the mold stator 10 in the axial direction, the load-side shaft 23 exits outside (on the left side in FIG. 1) from the hole in the other end of the mold stator 10 in the axial direction. Then, the load-side rolling bearing 21 a (an example of a rolling bearing) of the rotor 20 is pushed in until it comes into contact with the bearing support portion 11 at the axial end portion on the side opposite to the opening of the mold stator 10. At this time, the load-side rolling bearing 21 a is supported by the bearing support portion 11 formed at the axial end of the mold stator 10 on the side opposite to the opening.

  The rotor 20 has an anti-load-side rolling bearing 21b (an example of a rolling bearing) attached to an anti-load-side shaft 23 (right side in FIG. 1) (generally by press-fitting). While closing the opening part of the mold stator 10, the bracket 30 which supports the anti-load side rolling bearing 21b is press-fitted into the mold stator 10. The bracket 30 supports the anti-load-side rolling bearing 21b with a bearing support portion 30a. The press fitting of the bracket 30 into the mold stator 10 is performed by using the press fitting portion 30b having a substantially ring shape of the bracket 30 and a U-shaped cross section on the opening side of the inner peripheral portion 10a (mold resin portion) of the mold stator 10. It is done by press-fitting into. The outer diameter of the press-fit portion 30 b of the bracket 30 is larger than the inner diameter of the inner peripheral portion 10 a of the mold stator 10. The material of the bracket 30 is made of metal, for example, a galvanized steel plate. However, it is not limited to galvanized steel sheet.

  Since the present embodiment is characterized by the structure of the rotor 20, the mold stator 10 will be briefly described.

  The mold stator 10 includes a stator 40 and a mold resin 50 for molding. For the mold resin 50, for example, a thermosetting resin such as an unsaturated polyester resin is used. Since the stator 40 is attached with a substrate and the like which will be described later and has a weak structure, low pressure molding is desirable. Therefore, thermosetting resins such as unsaturated polyester resins are used.

The stator 40 has the following configuration.
(1) An electromagnetic steel sheet having a thickness of about 0.1 to 0.7 mm is punched into a strip shape, and a strip-shaped stator core 41 is manufactured by laminating by caulking, welding, bonding, or the like. The strip-shaped stator core 41 includes a plurality of teeth (not shown). The inside of which concentrated coil 42 described later is applied is a tooth.
(2) The insulating portion 43 is applied to the teeth. The insulating portion 43 is formed integrally with or separately from the stator core 41 using, for example, a thermoplastic resin such as PBT (polybutylene terephthalate).
(3) Concentrated winding coil 42 is wound around the teeth provided with insulating portion 43. A plurality of concentrated winding coils 42 are connected to form a three-phase single Y-connection winding. However, distributed winding may be used.
(4) Since it is a three-phase single Y connection, a terminal 44 (power supply to which power is supplied) is connected to the connection side of the insulating portion 43 to the coil 42 of each phase (U phase, V phase, W phase). Terminal 44a and neutral point terminal 44b) are assembled. There are three power terminals 44a and three neutral point terminals 44b.
(5) The board | substrate 45 is attached to the insulation part 43 (side in which the terminal 44 is assembled | attached) on the connection side. A substrate 45 on which a lead wire lead-out component 46 that leads out the lead wire 47 is assembled is assembled to the insulating portion 43 to form the stator 40. The chamfered square column 48 of the insulating part 43 formed in the stator core 41 is inserted into a rectangular column insertion hole (not shown) provided in the substrate 45, thereby positioning in the rotational direction and the insulating unit 43. The position in the axial direction is determined by installing the substrate 45 on the substrate installation surface. Further, by thermally welding the prisms 48 protruding from the substrate 45, the substrate 45 and the insulating portion 43 are fixed, and the portion protruding from the substrate 45 of the terminal 44 provided in the stator 40 is electrically soldered. Are also joined. On the substrate 45, an IC 49a (drive element) for driving the electric motor 100 (for example, a brushless DC motor), a Hall IC 49b (position detection element) for detecting the position of the rotor 20, and the like are mounted. IC 49a, Hall IC 49b, etc. are defined as electronic components.

  Next, the configuration of the rotor 20 will be described. As shown in FIG. 3, the rotor 20 includes a shaft 23 provided with a knurled portion 23a, a ring-shaped rotor resin magnet 22 (an example of a rotor magnet), and a ring-shaped position detection resin magnet 25 (position). An example of a detection magnet), and a resin portion 24 that integrally molds them.

  A resin magnet 22 of a ring-shaped rotor, a shaft 23, and a resin magnet 25 for position detection are integrated by a resin portion 24. At this time, the resin portion 24 is connected to the central cylinder portion 24g and a central cylinder portion 24g (a portion corresponding to the resin magnet 22 of the rotor), which will be described later, formed on the outer periphery of the shaft 23. And a plurality of axial ribs (not shown) radially formed about the shaft 23 in the radial direction. A cavity penetrating in the axial direction is formed between the ribs.

  A thermoplastic resin such as PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide) is used for the resin used for the resin portion 24. Those in which a glass filler is blended with these resins are also suitable.

  An anti-load-side rolling bearing 21b is attached to the non-load-side shaft 23 (right side in FIG. 3) (generally by press-fitting). A load-side rolling bearing 21a is attached to a load-side shaft 23 (left side in FIG. 3) to which a fan or the like is attached.

  The load-side rolling bearing 21a and the anti-load-side rolling bearing 21b are known rolling bearings.

  The load-side rolling bearing 21a includes an inner ring 21a-1 that is press-fitted into the shaft 23, an outer ring 21a-2 that is supported by the bearing support portion 11 of the mold stator 10, and an inner ring 21a-1 and an outer ring 21a-2. And rolling elements 21a-3 that roll. A ball or a roller is used for the rolling element 21a-3.

  The anti-load-side rolling bearing 21b includes an inner ring 21b-1 that is press-fitted into the shaft 23, an outer ring 21b-2 that is supported by the bearing support portion 30a of the bracket 30, and an inner ring 21b-1 and an outer ring 21b-2. A rolling element 21b-3 that rolls. A ball or a roller is used for the rolling element 21b-3.

  In the present embodiment, a shaft 23, a ring-shaped rotor resin magnet 22, and a ring shape are provided between a shaft 23 and an anti-load side rolling bearing 21 b supported by a metal (conductive) bracket 30. The position detecting resin magnet 25 is integrally formed with a resin portion 24, and the resin portion 24 becomes insulating and suppresses the shaft current, thereby suppressing the occurrence of electrolytic corrosion of the anti-load-side rolling bearing 21b. . However, the present invention can also be applied when the ring-shaped position detecting resin magnet 25 is not provided.

  When the rotor 20 is integrally formed, the resin portion 24 is formed so as to extend to the end portion of the shaft 23 on the anti-load side.

  Since the outer ring 21a-2 is supported by the bearing support part 11 (made of the mold resin 50) of the mold stator 10, the load-side rolling bearing 21a has a very small floating capacity because the bearing support part is an insulating material. Even if 23 is not insulated, the shaft current flowing through the bearing is extremely small.

  FIG. 4 is an enlarged cross-sectional view of the end portion on the non-load side of the shaft 23. In FIG. 4, the diameter d <b> 2 of the anti-load side end portion 23 d of the shaft 23 where the anti-load side rolling bearing 21 b is held via the resin portion 24 is that the resin magnet 22 of the rotor is held via the resin portion 24. A step 23c is provided to be smaller than the diameter d1 of the central portion 23e.

  The dimension between the anti-load side end face 23f (an example of an axial end face) of the shaft 23 and the step 23c is longer than the thickness (axial length) of the anti-load side rolling bearing 21b. The non-load-side end surface 23f of the shaft 23 is exposed in the example of FIG.

  The resin portion 24 has a bearing abutment surface 24d which is positioned in the axial direction when the anti-load-side rolling bearing 21b is inserted into the anti-load-side end portion 23d of the shaft 23 on the bearing fitting portion 24f of the resin portion 24. On the other hand, it is formed in a shape bent in a substantially perpendicular direction.

  A stepped portion 24e is provided between the central cylindrical portion 24g of the resin portion 24 formed on the outer periphery of the central portion 23e of the shaft 23 (a portion corresponding to the resin magnet 22 of the rotor) and the bearing contact surface 24d. It is done. It is essential that the diameter of the stepped portion 24e is smaller than the inner diameter of the outer ring 21b-2 of the anti-load side rolling bearing 21b. In the rotor 20 shown in FIG. 3, the stepped portion 24e has a diameter that is substantially the same as or slightly smaller than the outer diameter of the inner ring 21b-1 of the anti-load side rolling bearing 21b.

  Generally, a rolling bearing is provided with a cover between an outer ring and an inner ring so that grease does not leak out from the inside of the rolling bearing or dust does not enter from the outside. This cover is located inside the both end faces of the rolling bearing.

  Therefore, even if the diameter of the stepped portion 24e is made larger than the outer diameter of the inner ring 21b-1 of the anti-load side rolling bearing 21b, the portion larger than the outer diameter of the inner ring 21b-1 becomes the anti-load side rolling bearing 21b. Do not touch. Accordingly, the diameter of the stepped portion 24e is practically the same as or slightly smaller than the outer diameter of the inner ring 21b-1 of the anti-load side rolling bearing 21b.

  By providing the stepped portion 24e, when the shaft 23, the resin magnet 22 of the rotor and the resin magnet 25 for position detection are integrally formed with resin, the center cylindrical portion anti-load side bearing contact surface of the resin portion is formed with an irico. In this case, even if burrs occur on the mating surfaces of the molds by forming the stepped portion with the above-mentioned erection, the burrs do not come into contact with the anti-load side rolling bearing 21b, and thus adversely affect the anti-load side rolling bearing 21b. There is little fear.

  Further, when the rotor 20 receives a thermal shock, the central cylindrical portion 24g of the resin portion 24 may break. Even in such a case, the step portion 24e is provided in the central cylindrical portion 24g, and the radial thickness between the step portions can be increased.

  FIG. 5 is a view showing the resin magnet 22 of the rotor, FIG. 5 (a) is a left side view, FIG. 5 (b) is a sectional view taken on line AA of FIG. 5 (a), and FIG. is there. The configuration of the resin magnet 22 of the ring-shaped rotor will be described with reference to FIG. The rotor resin magnet 22 has an axial end of the inner diameter (on the right side in FIG. 5B) to ensure the coaxiality of the shaft 23 and the rotor resin magnet 22 during mold clamping during resin molding. The notch 22a is formed. In the example of FIG. 5, the notches 22a are formed at eight locations at substantially equal intervals in the circumferential direction (FIG. 5 (c)).

  In addition, on the resin magnet 22 of the rotor, pedestals 22b for mounting the position detection resin magnet 25 are formed at substantially equal intervals in the circumferential direction on the end surface of the other axial end portion (left side in FIG. 5B). ing. The pedestal 22b is formed from the vicinity of the inner diameter of the resin magnet 22 of the rotor toward the outer diameter, and the positioning projection 22c is radially directed from the tip of the pedestal 22b toward the outer periphery of the resin magnet 22 of the rotor. It extends to. The positioning projection 22c is used for positioning the rotor resin magnet 22 in the circumferential direction (rotation direction) when the rotor magnet, the position detection magnet, and the shaft are integrally formed of resin.

  The configuration of the ring-shaped position detecting resin magnet 25 will be described with reference to FIG. 6A is a left side view of the position detection resin magnet 25, FIG. 6B is a front view of the position detection resin magnet 25, and FIG. 6C is an enlarged view of a portion A in FIG.

  The position detecting resin magnet 25 includes steps 25b at both axial end portions on the inner diameter side. The step 25b is necessary to prevent the position detecting resin magnet 25 from coming off in the axial direction by filling the step 25b on the axial end portion side of the rotor 20 with a part of the resin portion 24. In FIG. 6, the one provided with the step 25 b at both ends is shown, but the step 25 b may be provided at either one of the ends, and it should be positioned on the axial end of the rotor 20. However, the one provided with the step 25b at both ends can be set without worrying about the front and back when setting the resin magnet 25 for position detection on the mold when the resin portion 24 of the rotor 20 is integrally formed. Excellent.

  Further, the position detecting resin magnet 25 includes eight ribs 25a which are circumferentially detented when embedded in the resin portion 24 in the step 25b at substantially equal intervals in the circumferential direction.

  As shown in FIG. 3, in the resin portion 24, the inner diameter pressing portion 24a of the mold for holding the inner diameter of the position detection resin magnet 25 and the position detection resin magnet 25 are set in the mold (lower mold). A taper part 24b for facilitating and a resin injection part 24c at the time of resin molding are formed after resin molding.

  The rotor resin magnet 22 is formed by mixing a thermoplastic material with a magnetic material. As shown in FIG. 5, the inner diameter is provided with a notch 22a tapered from one end surface in the axial direction. A pedestal 22b on which the position detecting resin magnet 25 is placed is provided on the other axial end surface opposite to one axial end surface.

  The pedestal 22b of the rotor resin magnet 22 formed integrally with the shaft 23 enables the position detection resin magnet 25 to be separated from the end surface of the rotor resin magnet 22, and the thickness of the position detection resin magnet 25 is increased. Can be disposed at an arbitrary position, and the cost can be reduced by filling a thermoplastic resin cheaper than the resin magnet 22 of the rotor.

  As shown in FIG. 6, the position detecting resin magnet 25 has steps 25 b on both sides in the thickness direction, and ribs 25 a that prevent rotation when embedded in the resin. The coaxiality of the inner diameter of the position detection resin magnet 25 and the outer diameter of the position detection resin magnet 25 is made with high accuracy.

  When molded integrally with the shaft 23, the outer periphery of the position detection resin magnet 25 is filled with a taper-shaped resin (resin portion 24). Correspondingly, the resin to be filled is blocked by the axial end face (outer side) on one side of the position detection resin magnet 25 and the axial end faces of the rotor resin magnet 22, so that the outer diameter of the rotor resin magnet 22 is variable. It is possible to suppress the occurrence of the problem, and the quality is improved.

  Further, by arranging the gate port at the time of integral molding with the shaft 23 further inside than the inner diameter of the resin magnet 22 of the rotor and arranging the resin injection portion 24c in a convex shape, the concentration of pressure is alleviated, and the resin Can be easily filled, and the convex portion of the resin injection portion 24c can be used for positioning.

  FIG. 7 is a cross-sectional view of the rotor 20 of the first modification. The difference from the rotor 20 shown in FIG. 3 is that a center hole 23 b is formed at the end of the shaft 23 on the side opposite to the load.

  When the shaft 23, the rotor resin magnet 22, and the position detection resin magnet 25 are integrally formed with the resin portion 24, the center hole 23 b of the shaft 23 is set in a mold (upper mold), thereby the rotor resin. The coaxiality between the magnet 22 and the shaft 23 is improved.

  The center hole 23b may be formed at both ends of the shaft 23.

  FIG. 8 is a cross-sectional view of the rotor 20 of the second modification. 3 differs from the rotor 20 shown in FIG. 3 in that the end surface of the end portion on the side opposite to the load of the shaft 23 is covered with the resin portion 24, and the center hole 23b is formed on the end surface on the end portion on the side opposite to the load of the shaft 23. It is.

  The end surface of the shaft 23 on the side opposite to the load is exposed at the center hole 23 b and the other part is covered with the resin part 24.

  When the end face of the end portion on the side opposite to the load side of the shaft 23 is covered with the resin portion 24 except for the center hole 23b portion, the resin portion 24 is used when the anti-load side rolling bearing 21b is press-fitted into the end portion on the opposite side of the shaft 23. Can prevent peeling and turning.

  7, when the shaft 23, the rotor resin magnet 22, and the position detection resin magnet 25 are integrally formed of resin, a mold is inserted into the center hole 23 b of the shaft 23. By fitting a projection that fits into the center hole in which the coaxial with the shaft insertion portion provided in the (upper mold) is secured, the shaft can be held in a state where the coaxial is secured, and the resin magnet 22 of the rotor The coaxiality between the shaft 23 and the shaft 23 is improved.

  FIG. 9 is a cross-sectional view of the rotor 20 of the third modification. The difference from the rotor 20 shown in FIG. 3 is that a part of the anti-load side end face 23 f of the shaft 23 (the outer peripheral side of the anti-load side end 23 d) is covered with the resin part 24.

  Similar to the rotor 20 shown in FIG. 8, the anti-load side rolling bearing 21 b is covered with the resin portion 24 except for the central portion of the anti-load side end surface 23 f so that the anti-load side rolling bearing 21 b is covered with the anti-load side end portion of the shaft 23. When press-fitting into the resin portion, it is possible to suppress peeling and turning of the resin portion 24.

  Further, when the shaft 23, the rotor resin magnet 22 and the position detection resin magnet 25 are integrally formed with the resin portion 24, a center hole 23b is formed in the shaft 23 by pressing the anti-load side end face 23f with a mold. Although not as much as the examples of FIGS. 7 and 8, the coaxiality between the resin magnet 22 of the rotor and the shaft 23 is also ensured.

  FIG. 10 is a cross-sectional view of the rotor 20 of the fourth modification. The difference from the rotor 20 shown in FIG. 3 is that the entire anti-load side end portion 23 d of the shaft 23 is covered with the resin portion 24.

  By covering the entire anti-load side end portion 23d of the shaft 23 with the resin portion 24, when the anti-load side rolling bearing 21b is press-fitted into the anti-load side end portion of the shaft 23, the resin portion 24 is more easily peeled off and turned up. It can be further suppressed.

  FIG. 11 is a cross-sectional view of the rotor 20 of the fifth modification. The difference from the rotor 20 shown in FIG. 3 is that a resin portion 24 is interposed between the load-side rolling bearing 21a and the shaft 23 to insulate them.

  By configuring as shown in FIG. 11, the shaft current in the load-side rolling bearing 21a can be further reduced. Furthermore, the shaft current of the motor other than the mold stator 10, for example, using a steel plate frame for the outer shell and using a metal bracket on the load side and the non-load side can be reduced.

  The rotor 20 shown in FIG. 11 has the same configuration as that of FIG. 3 in the configuration of the anti-load side end 23d of the shaft 23, but may have other configurations shown in FIGS.

  In addition, although the electric motor 100 shown in FIG. 1 showed what the mold stator 10 side becomes a load side and the bracket 30 side becomes an anti-load side, the reverse may be sufficient.

  Further, the rotor 20 shown in FIGS. 3 and 7 to 11 uses a rotor resin magnet 22 formed by mixing a magnetic material with a thermoplastic resin in a permanent magnet, but other permanent magnets ( Rare earth magnets (neodymium, samarium cobalt), ferrite, etc.) may be used.

  Similarly, other permanent magnets (rare earth magnets (neodymium, samarium cobalt), ferrite, etc.) may be used for the position detecting resin magnet 25.

  As described above, when an electric motor is operated using an inverter, the carrier frequency of the inverter is set high for the purpose of reducing the noise of the electric motor generated due to the switching of the transistor in the power circuit. Yes. As the carrier frequency is set higher, the shaft voltage generated on the shaft of the motor based on the high frequency induction increases, and the potential difference existing between the inner ring and the outer ring of the rolling bearing supporting the shaft increases. This makes it easier for current to flow through the rolling bearing. The current flowing through the rolling bearings causes corrosion called electro-corrosion on the rolling surfaces of both the inner and outer ring raceways and the rolling elements (balls and rollers rolling between the inner and outer rings), thereby deteriorating the durability of the rolling bearings. .

  Therefore, the rotor 20 of the present embodiment is particularly effective for reducing the shaft current when the electric motor 100 is operated using an inverter.

  FIG. 12 is a configuration diagram of a drive circuit 200 that drives the electric motor 100. As shown in FIG. 12, the inverter type drive circuit 200 includes a position detection circuit 110, a waveform generation circuit 120, a pre-driver circuit 130, and a power circuit 140.

  The position detection circuit 110 detects the magnetic pole of the position detection resin magnet 25 of the rotor 20 using the Hall IC 49b.

  The waveform generation circuit 120 generates a PWM (Pulse Width Modulation) signal for driving the inverter based on a speed command signal for instructing the rotation speed of the rotor 20 and a position detection signal from the position detection circuit 110, and a pre-driver Output to the circuit 130.

  The pre-driver circuit 130 outputs a transistor drive signal that drives the transistors 141 (six) of the power circuit 140.

  The power circuit 140 includes a DC power supply input unit and an inverter output unit, and includes an arm in which a transistor 141 and a diode 142 are connected in parallel and further connected in series.

  Since the electric motor 100 has three phases, a three-arm inverter output unit is connected to each coil 42. A 140V or 280V DC power source +, − obtained by rectifying AC 100V or 200V of commercial power is connected to the DC power source input unit.

  When the speed command signal is input to the drive circuit 200, the waveform generation circuit 120 sets the energization timing to each of the three-phase coils 42 according to the position detection signal and generates a PWM signal according to the input of the speed command signal. The pre-driver circuit 130 that outputs the PWM signal drives the transistor 141 in the power circuit 140.

  The inverter output unit drives the transistor 141 to apply a voltage to the coil 42, a current flows through the coil 42, torque is generated, and the rotor 20 rotates. It becomes the rotational speed of the electric motor 100 according to a speed command signal. The motor 100 is also stopped by a speed command signal.

FIG. 13 shows a manufacturing process of the rotor 20.
(1) Forming and demagnetizing the resin magnet 25 for position detection and the resin magnet 22 of the rotor. The shaft 23 is processed (step 1).
(2) The position detection resin magnet 25 is set in the lower mold with the end portion having the step 25b facing downward, and the inner diameter pressing portion provided in the lower mold holds the inner diameter of the position detection resin magnet 25 (step 2). ).
(3) The positioning projection 22c of the resin magnet 22 of the rotor is fitted into the positioning projection insertion portion provided in the lower mold and set in the lower mold (step 3).
(4) The shaft 23 is set in the lower mold, and the mold is clamped so that the notch 22a of the resin magnet 22 of the rotor is pressed by the notch pressing portion of the upper mold (step 4).
(5) Resin (resin portion 24) is molded (step 5). When the resin magnet 22 of the rotor, the resin magnet 25 for position detection, and the shaft 23 are integrally formed by the resin portion 24, the shaft 23 and at least one of the load side rolling bearing 21a or the anti-load side rolling bearing 21b are interposed between them. Then, integral molding is performed so that the resin portion 24 is interposed.
(6) The position detecting resin magnet 25 and the rotor resin magnet 22 are magnetized (step 6).
(7) The load-side rolling bearing 21a and the anti-load-side rolling bearing 21b are assembled to the shaft 23 (step 7).

  According to the manufacturing process described above, when the resin magnet 22 of the rotor, the shaft 23, and the position detection resin magnet 25 are integrated with the resin (resin portion 24), all the parts are set in the mold and the resin. Since the molding is performed, the cost of the rotor 20 can be reduced by reducing the work process.

  Further, the pedestal 22b of the rotor resin magnet 22 enables the position detection resin magnet 25 to be separated from the end surface of the rotor resin magnet 22, and the thickness of the position detection resin magnet 25 is minimized and arbitrary. The cost can be reduced by filling a thermoplastic resin that is cheaper than the resin magnet 22 of the rotor.

  Further, since the position detecting resin magnet 25 is symmetrical in the thickness direction, it can be set in the mold without matching the orientation.

  In addition, since the portion through which the outer diameter passes when setting the lower mold position detection resin magnet 25 is tapered (tapered portion 24b of the resin portion 24), the lower die position detecting resin magnet 25 is set without being caught by the lower die. Therefore, the cost can be reduced with the improvement of productivity by simplifying the work process.

  Further, when the position detecting resin magnet 25 is set in the lower mold, the inner diameter is held by the inner diameter pressing portion provided in the lower mold, thereby ensuring the accuracy of the coaxiality between the shaft 23 and the resin magnet 22 of the rotor. Is done.

  Further, the notch holding portion provided in the upper mold presses the notch 22a provided in the inner diameter of the resin magnet 22 of the rotor, so that the accuracy of the coaxiality between the shaft 23 and the resin magnet 22 of the rotor is ensured. .

  As described above, in the present embodiment, the resin of the shaft 23 and the ring-shaped rotor is provided between the shaft 23 and the anti-load-side rolling bearing 21b supported by the metal (conductive) bracket 30. The resin for integrally molding the magnet 22 is filled, the resin portion 24 is interposed, and insulation is suppressed by the resin portion 24, thereby suppressing the occurrence of electrolytic corrosion of the anti-load-side rolling bearing 21b. However, the same effect can be obtained by integrating the ring-shaped position detecting resin magnet 25 with the resin portion 24 together with the shaft 23 and the resin magnet 22 of the ring-shaped rotor.

  Further, by providing a step portion 24e between the central cylindrical portion 24g of the resin portion 24 formed on the outer periphery of the central portion 23e of the shaft 23 and the bearing contact surface 24d, the shaft 23 and the resin magnet 22 of the rotor are provided. When forming the central cylindrical part anti-load side bearing contact surface of the resin part with ileco when molding the resin integrally with the resin, burrs are generated on the mating surface of the mold by forming the step part with the ileco. However, since the burr does not come into contact with the anti-load side rolling bearing 21b, there is little possibility of adversely affecting the anti-load side rolling bearing 21b. However, the same effect can be obtained by integrating the ring-shaped position detecting resin magnet 25 with the resin portion 24 together with the shaft 23 and the resin magnet 22 of the ring-shaped rotor.

  Further, when the rotor 20 receives a thermal shock, the central cylindrical portion 24g of the resin portion 24 may break, but a stepped portion 24e is provided in the central cylindrical portion 24g, and the radial direction of the central cylindrical portion 24g between the stepped portions 24e. Can be dealt with by increasing the thickness.

  As in the rotor 20 of the first modification shown in FIG. 7, the shaft 23, the rotor resin magnet 22, and the position detection resin magnet 25 are formed by forming a center hole 23 b at the opposite end of the shaft 23. When integrally molded with resin, the shaft 23 is fitted into the center hole 23b of the shaft 23 by fitting a projection to be fitted into the center hole 23b in which the coaxial with the shaft insertion portion provided in the mold (upper mold) is secured. Can be held in a state where the coaxiality is secured, and the coaxiality between the resin magnet 22 of the rotor and the shaft 23 is improved.

  As in the rotor 20 of Modification 2 shown in FIG. 8, the end surface of the shaft 23 on the side opposite to the load side is covered with the resin portion 24, and the center hole 23 b is formed on the end surface of the shaft 23 on the side opposite to the load side. Thus, when the anti-load-side rolling bearing 21b is press-fitted into the anti-load-side end portion of the shaft 23, the resin portion 24 can be prevented from being peeled off and turned, and the shaft 23, the rotor resin magnet 22 and the position detection resin can be suppressed. When the magnet 25 is integrally formed of resin, a projection that fits into the center hole 23b of the shaft 23 secured in the center hole 23b of the mold (upper mold) is fitted into the center hole 23b of the shaft 23. The shaft 23 can be held in a state where the coaxiality is secured, and the coaxiality between the resin magnet 22 of the rotor and the shaft 23 is improved.

  Like the rotor 20 of the modification 3 shown in FIG. 9, by covering a part of the anti-load side end surface 23f of the shaft 23 (the outer peripheral side of the anti-load side end 23d) with the resin part 24, the anti-load side When the rolling bearing 21 b is press-fitted into the opposite end portion of the shaft 23, the resin portion 24 can be prevented from being peeled off or turned up. Further, when the shaft 23, the rotor resin magnet 22 and the position detection resin magnet 25 are integrally formed with the resin portion 24, the rotor resin magnet 22 and the shaft are pressed by pressing the anti-load side end face 23f with a mold. The degree of coaxiality with 23 is also secured.

  10, the entire anti-load side end 23d of the shaft 23 is covered with the resin portion 24 so that the anti-load-side rolling bearing 21b is covered with the anti-load side end of the shaft 23. In the case of press-fitting into the resin, peeling and turning of the resin portion 24 can be further suppressed.

  Like the rotor 20 of the modification 5 shown in FIG. 11, the resin part 24 is interposed also between the load side rolling bearing 21a and the shaft 23, and it insulates between them, The shaft in the load side rolling bearing 21a The current can be further reduced. Furthermore, the shaft current of the motor other than the mold stator 10, for example, using a steel plate frame for the outer shell and using a metal bracket on the load side and the non-load side can be reduced.

  When an electric motor is operated using an inverter, the carrier frequency of the inverter is set higher for the purpose of reducing the noise of the electric motor. However, as the carrier frequency is set higher, the motor shaft has a higher frequency. The shaft voltage generated based on the induction increases, and the potential difference existing between the inner ring and the outer ring of the rolling bearing that supports the shaft increases, so that the current flowing through the rolling bearing also increases. Therefore, the rotor 20 of the present embodiment is particularly effective for reducing the shaft current when the electric motor 100 is operated using an inverter. Here, the detection method is described using the Hall IC 49b which is a sensor for detecting the magnetic pole of the position detection resin magnet 25 of the rotor 20. However, the coil is not used without using the position detection resin magnet 25 and the Hall IC 49b. Needless to say, the sensorless driving method in which the flowing current is detected by a current detector (not shown) and the electric motor is driven by using a microcomputer or the like in the waveform generation circuit 120 has the same effect.

Embodiment 2. FIG.
FIG. 14 is a diagram illustrating the second embodiment, and is a configuration diagram of the air conditioner 300.

  The air conditioner 300 includes an indoor unit 310 and an outdoor unit 320 connected to the indoor unit 310. The indoor unit 310 is equipped with an indoor unit blower (not shown), and the outdoor unit 320 is equipped with an outdoor unit blower 330.

  The outdoor unit blower 330 and the indoor unit blower include the electric motor 100 of the first embodiment as a drive source.

  The durability of the air conditioner 300 is improved by mounting the electric motor 100 of the first embodiment on the outdoor unit blower 330 and the indoor unit blower that are main components of the air conditioner 300.

  As an application example of the electric motor 100 of the present invention, the electric motor 100 can be used by being mounted on a ventilation fan, a home appliance, a machine tool, or the like.

FIG. 3 shows the first embodiment and is a cross-sectional view of the electric motor 100. FIG. 5 shows the first embodiment, and is a perspective view of a stator 40. FIG. 3 shows the first embodiment and is a cross-sectional view of a rotor 20. FIG. 5 shows the first embodiment, and is an enlarged cross-sectional view of an end portion on the opposite side of the shaft 23; FIG. 3 is a diagram illustrating the first embodiment, and is a diagram illustrating a resin magnet 22 of a rotor ((a) is a left side view, (b) is a cross-sectional view taken along line AA of (a), and (c) is a right side view). FIG. 4 is a diagram illustrating the first embodiment and is a diagram illustrating a position detection magnet 25 ((a) is a left side view, (b) is a front view, and (c) is an enlarged view of a portion A in (b)). FIG. 5 shows the first embodiment and is a cross-sectional view of a rotor 20 of a first modification. FIG. 5 shows the first embodiment and is a cross-sectional view of a rotor 20 of a second modification. FIG. 5 shows the first embodiment and is a cross-sectional view of a rotor 20 of a third modification. FIG. 5 shows the first embodiment and is a cross-sectional view of a rotor 20 of a fourth modification. FIG. 5 shows the first embodiment and is a cross-sectional view of a rotor 20 of a fifth modification. FIG. 5 shows the first embodiment and is a configuration diagram of a drive circuit 200 that drives the electric motor 100; FIG. 5 shows the first embodiment, and shows a manufacturing process of the rotor 20. FIG. 5 shows the second embodiment and is a configuration diagram of an air conditioner 300.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Mold stator, 10a Inner peripheral part, 11 Bearing support part, 20 Rotor, 21a Load side rolling bearing, 21a-1 Inner ring, 21a-2 Outer ring, 21a-3 Rolling element, 21b Anti-load side rolling bearing, 21b- 1 Inner ring, 21b-2 Outer ring, 21b-3 Rolling element, 22 Rotor resin magnet, 22a Notch, 22b Pedestal, 22c Positioning protrusion, 23 Shaft, 23a Knurl, 23b Center hole, 23c Step, 23d Anti-load side End part, 23e center part, 23f anti-load side end face, 24 resin part, 24a inner diameter pressing part, 24b taper part, 24c resin injection part, 24d contact surface, 24e step part, 24f fitting part, 24g center tube part, 24h Anti-load side end face, 25 Position detection resin magnet, 25a Rib, 25b Step, 30 Bracket , 30a Bearing support portion, 30b Press-fit portion, 40 Stator, 41 Stator core, 42 Coil, 43 Insulating portion, 44 terminal, 44a Power supply terminal, 44b Neutral point terminal, 45 Substrate, 47 Lead wire, 48 Rectangular column, 49a IC, 49b Hall IC, 50 Mold resin, 100 Electric motor, 110 Position detection circuit, 120 Waveform generation circuit, 130 Pre-driver circuit, 140 Power circuit, 141 Transistor, 142 Diode, 200 Drive circuit, 300 Air conditioner, 310 Indoor unit 320 outdoor unit, 330 outdoor unit blower.

Claims (9)

The magnet and the shaft, is formed on the outer periphery of the shaft, a rotor and a resin portion for integrating the magnet and the shaft,
Two rolling bearings attached to the shaft;
A stator and a mold resin for molding the stator, an opening is provided at one end in the axial direction, and a bearing support portion for supporting one of the two rolling bearings is formed at the other end in the axial direction. A mold stator having a mold resin,
A metal bracket attached to the opening and supporting the other of the two rolling bearings;
With
Of only the two rolling bearings, the Ke rolling bearing which is supported by the metal bracket, between the shaft and the resin portion formed on an outer periphery of the shaft, characterized in the extension Mashimasu Turkey Electric motor. Said only two rolling bearings, the electric motor according to claim 1, wherein the load-side roller bearing, and is only non-load-side rolling bearing. The resin portion extending between the roller bearing and which is supported by the shaft and the metal bracket, and positioning in the axial direction during insertion into the rolling bearing the shaft of which is supported by the metal bracket the electric motor according to claim 1 or 2, characterized in that to form a bearing contact surface made. The inner diameter of the outer ring of the rolling bearing is located between the central cylindrical portion of the resin portion and the bearing abutting surface, which is located inside the magnet of the rotor and formed on the outer periphery of the substantially central portion of the shaft. The electric motor according to claim 3 , wherein a smaller step portion is provided . The resin portion formed between the rolling bearing and the shaft being supported by the metal bracket can be of any claims 1 to 4, characterized in that covers at least a portion of the axial end surface of said shaft The electric motor according to Crab . The electric motor according to any one of claims 1 to 5 , wherein the shaft includes a center hole in at least one of both axial end portions . The material of the resin portion, the electric motor according to any one of claims 1 to 6, characterized in that the thermoplastic resin is obtained by blending a glass filler. The electric motor further includes:
A position detection circuit for detecting the magnetic pole of the rotor using a position detection element;
A waveform generation circuit for generating a PWM (Pulse Width Modulation) signal for driving the inverter based on a speed command signal for instructing the rotation speed of the rotor and a position detection signal from the position detection circuit;
A pre-driver circuit that generates a drive signal from the output of the waveform generation circuit;
Connected in parallel with transistor and a diode, to one of the claims 1 to 7, characterized in that these and a power circuit with an arm connected in series comprises a <br/> the drive circuit of inverter type constituted The electric motor described. An air conditioner using the electric motor according to any one of claims 1 to 8 as an electric motor for a blower.

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