JP2012060772A - Rotor of motor, motor, air handling unit, and manufacturing method of rotor of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor of a motor where electric corrosion of a bearing is suppressed by a cheap method.SOLUTION: In a rotor of a motor according to this invention, a magnet and shaft of the rotor are integrated by a resin part, and roller bearings are arranged on both edge-faces in an axis direction of the resin part formed in an outer circumference of the shaft. The roller bearing comprises: an inner ring which is pressed and fitted into the shaft; an outer ring which is supported by a bearing support part of a stator; and a rolling element which rolls between the inner ring and the outer ring. Either of the roller bearings is a ceramic bearing where at least one of the inner ring, the outer ring, and the rolling element is constituted by an insulating material of ceramics or the like.

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, an air conditioner equipped with the electric motor, and a method for manufacturing the rotor of the electric motor.

  Conventionally, when an electric motor is driven by an inverter, the carrier frequency of the inverter is set to be high for the purpose of reducing the noise of the electric motor 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 that roll 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, the electric motor disclosed in Patent Document 1 has a concave portion provided on the side of the bearing bracket that contacts the insulating material, and the convex portion of the insulating material provided with a convex portion corresponding to the concave portion of the bearing bracket is fitted into the concave portion of the bearing bracket. However, since it is configured to be fixed, it is easy to assemble with a simple configuration, but on the other hand, there is a problem that it is easily detached from the insulating material from the bearing bracket.

  Further, the electric corrosion prevention type rolling bearing of Patent Document 2 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, and provides an inexpensive electric motor rotor, electric motor, air conditioner, and electric motor rotor manufacturing method in which electric corrosion of a bearing is suppressed. .

The rotor of the electric motor according to the present invention is a rotor of an electric motor in which a magnet and a shaft of the rotor are integrated by a resin portion, and rolling bearings are disposed on both axial end surfaces of the resin portion formed on the outer periphery of the shaft. There,
The rolling bearing includes an inner ring press-fitted into the shaft, an outer ring supported by the bearing support portion of the stator, and a rolling element that rolls between the inner ring and the outer ring.
One of the rolling bearings is a ceramic bearing in which at least one of an inner ring, an outer ring, and a rolling element is made of an insulating material such as ceramic.

  In the rotor of the electric motor according to the present invention, any one of the rolling bearings is a ceramic bearing in which at least one of the inner ring, the outer ring, and the rolling element is made of an insulating material such as ceramic. An electric motor rotor that is suppressed and inexpensive can be obtained.

FIG. 3 shows the first embodiment and is a cross-sectional view of the electric motor 100. FIG. 3 shows the first embodiment and is a cross-sectional view of the mold stator 10. FIG. 3 shows the first embodiment, and is a cross-sectional view showing a state where a rotor 20 is inserted into a mold stator 10. FIG. 5 shows the first embodiment, and is a cross-sectional view of the bracket 30. 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 a cross-sectional view of the rotor resin assembly 20-1 with the load side rolling bearing 21a and the anti-load side rolling bearing 21b removed. FIG. 5 shows the first embodiment, and is a side view of the rotor resin assembly 20-1 viewed from the load side. FIG. 5 shows the first embodiment, and is an enlarged cross-sectional view of an end portion on the side opposite to the load of the rotor resin assembly 20-1. FIG. 5 shows the first embodiment, and is an enlarged cross-sectional view of an end portion on the counterload side of the rotor 20. 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 CC cross-sectional view of (a), and (c) is a right side view). FIG. 5 is a diagram illustrating the first embodiment and is a diagram illustrating a position detection resin magnet 25 ((a) is a left side view, (b) is a front view, and (c) is an enlarged view of a portion D in (b)). FIG. 3 shows the first embodiment, and is a circuit diagram of an electric motor built-in drive circuit 1 incorporated in 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.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 shows the first embodiment and is a cross-sectional view of an electric motor 100. An electric motor 100 shown in FIG. 1 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. The electric motor 100 is, for example, a brushless DC motor having a permanent magnet in the rotor 20 and driven by an inverter. In FIG. 1, the elements constituting the mold stator 10 and the rotor 20 are denoted by reference numerals, but are not described here. Those codes will be described later.

  FIG. 2 is a diagram showing the first embodiment, and is a cross-sectional view of the mold stator 10. The mold stator 10 is open at one axial end (the right side in FIG. 2), and an opening 10b is formed here. The rotor 20 is inserted from the opening 10b (see the arrow in FIG. 2). A hole 11a that is slightly larger than the diameter of the shaft 23 of the rotor 20 is formed in the other axial end portion of the mold stator 10 (left side in FIG. 2). Other configurations of the mold stator 10 will be described later.

  FIG. 3 shows the first embodiment, and is a cross-sectional view showing a state where the rotor 20 is inserted into the mold stator 10. In the rotor 20 inserted from the opening 10b (see FIG. 2) at one axial end of the mold stator 10, the load side of the shaft 23 is a hole 11a at the other axial end of the mold stator 10 (see FIG. 2). To the outside (left side of Fig. 3). 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 the anti-load side (right side in FIG. 1) of the shaft 23 (generally by press-fitting).

  FIG. 4 shows the first embodiment, and is a cross-sectional view of the bracket 30. The opening 10b of the mold stator 10 is closed, and the bracket 30 that 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 bracket 30 is press-fitted into the mold stator 10 by using a press-fit portion 30b having a substantially ring shape of the bracket 30 and a U-shaped cross section as an opening 10b in the inner peripheral portion 10a (mold resin portion) of the mold stator 10. This is done by press-fitting to the side. The outer diameter of the press-fit portion 30b of the bracket 30 is larger than the inner diameter of the inner peripheral portion 10a of the mold stator 10 by the press-fit allowance. 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.

  A mold stator 10 shown in FIG. 2 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. The stator 40 is attached to a substrate and the like which will be described later, and has a weak structure. Therefore, thermosetting resins such as unsaturated polyester resins are used.

FIG. 5 is a perspective view of the stator 40 showing the first embodiment. The stator 40 shown in FIG. 5 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, for example, a three-phase single Y-connection winding. However, distributed winding may be used.
(4) Since it is a three-phase single-Y connection (star connection), a terminal 44 (power supply is connected) to each phase (U-phase, V-phase, W-phase) coil 42 is connected to the connection side of the insulating portion 43. The supplied power supply 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. A chamfered prism 48 (not shown in FIG. 5 but the main body is a prism) of the insulating part 43 formed in the stator core 41 is inserted into a prism insertion hole (not shown) provided in the substrate 45. Thus, positioning in the rotational direction is performed, and the position in the axial direction is determined by installing the substrate 45 on the substrate installation surface (not shown) of the insulating portion 43. Further, by thermally welding the prisms 48 protruding from the substrate 45, the substrate 45 and the insulating portion 43 are fixed, and the portions protruding from the substrate 45 of the terminals 44 of the stator 40 are 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: see FIG. 3) 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 structure of the rotor 20 which is the characteristic part of this Embodiment is demonstrated. 6 to 8 show the first embodiment. FIG. 6 is a cross-sectional view of the rotor 20. FIG. 7 is a rotor resin assembly 20-1 with the load side rolling bearing 21a and the anti-load side rolling bearing 21b removed. FIG. 8 is a side view of the rotor resin assembly 20-1 viewed from the load side.

  As shown in FIG. 6, the rotor 20 includes a rotor resin assembly 20-1, a load-side rolling bearing 21a, and an anti-load-side rolling bearing 21b.

  As shown in FIG. 7, the rotor resin assembly 20-1 includes a shaft 23 provided with a knurl 23 a, a ring-shaped rotor resin magnet 22 (an example of a rotor magnet), and a ring-shaped position detection device. A resin magnet 25 (an example of a position detection magnet) and a resin portion 24 that integrally molds the resin magnet 25 are included.

  A resin magnet 22 of a ring-shaped rotor, a shaft 23, and a position detection resin magnet 25 are integrated by a resin portion 24 injected by a vertical molding machine. At this time, the resin part 24 is formed on the outer periphery of the shaft 23, and a central cylinder part 24g (formed inside the rotor resin magnet 22), which will be described later, and the rotor resin magnet 22 are arranged in the central cylinder part 24g. And a plurality of axial ribs 24j (see FIG. 8) radially formed in the radial direction with the shaft 23 as a center. A cavity 24k (see FIG. 8) penetrating in the axial direction is formed between the ribs 24j.

  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 (right side in FIG. 6) of the shaft 23 (generally by press-fitting). A load-side rolling bearing 21a is attached to the load side (left side in FIG. 6) of the shaft 23 to which a fan or the like is attached.

  The load-side rolling bearing 21a and the anti-load-side rolling bearing 21b are well-known rolling bearings and will not be described in detail, but the inner ring 21a-1 press-fitted into the shaft 23 and the bearing support portion 11 of the mold stator 10 are omitted. An outer ring 21a-2 to be supported, and a rolling element 21a-3 that rolls between the inner ring 21a-1 and the outer ring 21a-2 are provided. A ball or a roller is used for the rolling element 21a-3.

  Since the inner ring 21a-1, the outer ring 21a-2, and the rolling element 21a-3 of the load side rolling bearing 21a are made of rolling bearing steel and are conductive, the inner ring 21a-1, the outer ring 21a-2, and the rolling element 21a-3 are not insulated. (Conducts).

  The inner ring 21b-1 and the outer ring 21b-2 of the anti-load-side rolling bearing 21b are made of rolling bearing steel and are conductive like the load-side rolling bearing 21a.

  The rolling element 21b-3 of the anti-load side rolling bearing 21b is made of ceramic and has an insulating property. The anti-load-side rolling bearing 21b in which the rolling element 21b-3 is made of ceramic is hereinafter referred to as “ceramic rolling element bearing” (in a broad sense, “ceramic bearing”). The inner ring 21b-1 and the outer ring 21b-2 are made of ceramic and insulated by a rolling element 21b-3 having insulating properties.

  In the present embodiment, the resin magnet 22 and the shaft 23 of the ring-shaped rotor are integrated by the resin portion 24 to insulate the rotor from the resin magnet 22 and the shaft 23, and metal (conductive) The anti-load-side rolling bearing 21b supported by the bracket 30 is “ceramic rolling element bearing”, and the inner ring 21b-1 and the outer ring 21b-2 are insulated to suppress the shaft current, thereby reducing the load side. It is characterized in that the occurrence of electrolytic corrosion of the rolling bearing 21a and the anti-load side rolling bearing 21b is suppressed.

  The shaft current flowing through the load-side rolling bearing 21a is the shaft current flowing through the anti-load-side rolling bearing 21b with the inner ring 21b-1 and the outer ring 21b-2 insulated from each other with the anti-load-side rolling bearing 21b as a "ceramic rolling element bearing". Therefore, the load-side rolling bearing is a ceramic rolling conductor bearing, and the inner ring 21a-1 and the outer ring 21a-2 do not have to be insulated.

  Although the rolling element 21b-3 of the anti-load side rolling bearing 21b is made of an insulating ceramic, at least one of the inner ring 21b-1, the outer ring 21b-2, and the rolling element 21b-3 is made of an insulating material such as ceramic. By doing so, the same effect can be obtained.

  The same effect can be obtained not only with ceramics but also with other insulating materials. Furthermore, although the example which makes the anti-load side rolling bearing 21b "ceramic bearing" was shown, it is the same when the load side rolling bearing 21a is made "ceramic bearing". That is, the same effect can be obtained by setting one of the load side rolling bearing 21a and the anti-load side rolling bearing 21b to “ceramic bearing”. The present embodiment also includes a rotor 20 that does not have the ring-shaped position detecting resin magnet 25.

  FIGS. 9 to 10 are diagrams showing the first embodiment. FIG. 9 is an enlarged cross-sectional view of the end portion on the anti-load side of the rotor resin assembly 20-1, and FIG. It is sectional drawing.

  In FIG. 9, the resin portion 24 has a bearing abutment surface 24 d for positioning in the axial direction when the anti-load-side rolling bearing 21 b is inserted into the anti-load-side end 23 d of the shaft 23. It is formed at the opposite end portion of the central cylindrical portion 24g (resin portion) of the resin portion 24 formed on the outer periphery with the center.

  The central cylindrical portion 24g of the resin portion 24 formed on the outer periphery with the knurled portion of the shaft 23 as the center in the axial direction has a stepped portion 24e between the outer peripheral portion of the central cylindrical portion 24g and the bearing contact surface 24d. Is provided.

  It is essential that the diameter d3 of the stepped portion 24e is smaller than the inner diameter d4 of the outer ring 21b-2 of the anti-load side rolling bearing 21b. In the rotor 20 shown in FIG. 10, the diameter d3 of the stepped portion 24e is substantially the same as or slightly smaller than the outer diameter d5 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.

  Accordingly, even if the diameter d3 of the stepped portion 24e is larger than the outer diameter d5 of the inner ring 21b-1 of the anti-load side rolling bearing 21b, the portion larger than the outer diameter d5 of the inner ring 21b-1 is anti-load side rolling. It does not contact the bearing 21b. Therefore, it is practical that the diameter d3 of the stepped portion 24e is substantially the same as or slightly smaller than the outer diameter d5 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 of resin, the bearing contact surface 24d of the central cylindrical portion 24g of the resin portion 24 is erected. In the case of forming, the step portion 24e is formed by the above-mentioned eroko. Therefore, since the mating surface of the mold is the anti-load side end surface 24h of the central cylinder portion 24g, the anti-load side rolling bearing 21b is the anti-load that becomes the mating surface of the mold even if burrs occur on the mating surface of the mold. Since the stepped portion 24e is separated from the side end surface 24h, the burr does not come into contact with the anti-load side rolling bearing 21b. Therefore, there is little possibility of adversely affecting the anti-load side rolling bearing 21b.

  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, the radial dimension of the step portion 24e is constant, and the diameter of the central cylindrical portion 24g between the step portions 24e (the load side and the anti-load side) at both ends. The thickness of the direction can be increased to cope with it.

  Since the diameter d3 of the stepped portion 24e is smaller than the inner diameter d4 of the outer rings 21a-2 and 21b-2 of the load side rolling bearing 21a and the anti-load side rolling bearing 21b, the central cylindrical portion 24g between the stepped portions 24e It is also possible to make the diameter d6 larger than the inner diameter of the outer rings 21a-2 and 21b-2.

  FIG. 11 is a view showing the resin magnet 22 of the rotor, FIG. 11 (a) is a left side view, FIG. 11 (b) is a sectional view taken along the line CC of FIG. 11 (a), and FIG. is there. The structure 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. 11B) to ensure that the shaft 23 and the rotor resin magnet 22 are coaxial with each other during mold clamping during resin molding. The notch 22a is formed. In the example of FIG. 11, the notches 22a are formed at eight locations at substantially equal intervals in the circumferential direction (FIG. 11 (c)).

  In addition, on the resin magnet 22 of the rotor, pedestals 22b for placing 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. 11B). 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 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. .

  FIGS. 12A and 12B are diagrams showing the first embodiment, and are diagrams showing the position detection resin magnet 25 ((a) is a left side view, (b) is a front view, and (c) is an enlarged view of a portion D in (b)). It is. The configuration of the ring-shaped position detection resin magnet 25 will be described with reference to 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. 12, the step provided with the step 25 b at both ends is shown, but the step 25 b may be provided at either one of the end portions, and it may be positioned on the axial end portion side of the rotor 20. However, when both ends are provided with a step 25b, the position detection resin magnet 25 is set without worrying about the front and back when the resin magnet 24 for position detection is set on the mold (lower mold) when the resin portion 24 of the rotor 20 is integrally formed. Excellent workability because it can.

  Further, the position detecting resin magnet 25 includes eight ribs 25a (substantially triangular in cross section) that are circumferentially detented when embedded in the resin portion 24 in the step 25b at substantially equal intervals in the circumferential direction. However, the number, shape, and arrangement interval of the ribs 25a may be arbitrary.

  As shown in FIG. 6, in the resin portion 24, a mold inner diameter holding portion 24a for holding the inner diameter of the position detecting resin magnet 25 and the position detecting resin magnet 25 are set in a 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. 11, 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. As a result, the thickness of the position detecting resin magnet 25 can be minimized and disposed at an arbitrary position, and the cost can be reduced by filling a cheaper thermoplastic resin than the resin magnet 22 of the rotor. It becomes.

  As shown in FIG. 12, the position detecting resin magnet 25 has steps 25b on both sides in the thickness direction, and ribs 25a that prevent rotation when embedded in resin. Further, the coaxiality between the inner diameter of the position detecting resin magnet 25 and the outer diameter of the position detecting 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.

  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.

  The rotor 20 shown in FIG. 6 uses a rotor resin magnet 22 formed by mixing a permanent magnet with a thermoplastic resin and a magnetic material, but other permanent magnets (rare earth magnets (neodymium, samarium) are used. Iron), sintered ferrite, etc.) may be used.

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

  As already mentioned, when the electric motor is operated using an inverter, the carrier frequency of the inverter should be set high for the purpose of reducing the noise of the electric motor generated due to the switching of the transistors 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 by an inverter.

  FIG. 13 is a diagram showing the first embodiment, and is a circuit diagram of the motor built-in drive circuit 1 of the motor 100. The motor built-in drive circuit 1 will be described with reference to FIG. As shown in FIG. 13, AC power is supplied to a drive circuit 1 with a built-in motor from a commercial AC power supply 2 provided outside the motor 100. The AC voltage supplied from the commercial AC power supply 2 is converted into a DC voltage by the rectifier circuit 3. The DC voltage converted by the rectifier circuit 3 is converted to an AC voltage having a variable frequency by the inverter main circuit 4 and applied to the electric motor 100. The electric motor 100 is driven by variable frequency AC power supplied from the inverter main circuit 4. The rectifier circuit 3 includes a chopper circuit that boosts the voltage applied from the commercial AC power supply 2 and a smoothing capacitor that smoothes the rectified DC voltage.

  The inverter main circuit 4 is a three-phase bridge inverter circuit, and the switching section of the inverter main circuit 4 has six IGBTs 6a to 6f (insulated gate bipolar transistors, simply defined as transistors) and six flywheel diodes serving as inverter main elements. SiC-SBDs 7a-7f (Schottky barrier diodes, simply defined as diodes) using silicon carbide (SiC) as (FRD) are provided. The SiC-SBDs 7a to 7f, which are FRDs, are reverse current prevention means for suppressing the counter electromotive force generated when the IGBTs 6a to 6f turn the current from ON to OFF.

  In the first embodiment, the IGBTs 6a to 6f and the SiC-SBDs 7a to 7f are IC modules in which each chip is mounted on the same lead frame and molded with epoxy resin and packaged. The IGBTs 6a to 6f may be IGBTs using SiC or GaN instead of IGBTs using silicon (Si-IGBT), and MOSFETs (Metal-Oxide-Semiconductor Field-) using Si, SiC, or GaN instead of IGBTs. Other switching elements such as Effect Transistor may be used.

  Two voltage-dividing resistors 8a and 8b connected in series are provided between the rectifier circuit 3 and the inverter main circuit 4, and the high-voltage DC voltage is reduced by the voltage-dividing circuit using the voltage-dividing resistors 8a and 8b. A DC voltage detector 8 is provided for sampling and holding the electrical signal.

  In addition, the electric motor 100 includes a rotor 20 (FIG. 6) and a mold stator 10 (FIG. 1), and the rotor 20 is rotated by AC power supplied from the inverter main circuit 4. A Hall IC 49b for detecting the position detecting resin magnet 25 is provided in the vicinity of the rotor 20 of the mold stator 10, and an electric signal from the Hall IC 49b is processed and converted into position information of the rotor 20. A rotor position detection unit 110 is provided.

  The position information of the rotor 20 detected by the rotor position detection unit 110 is output to the output voltage calculation unit 120. The output voltage calculation unit 120 is an optimum inverter main unit to be applied to the electric motor 100 based on the command of the target rotational speed N given from the outside of the electric motor built-in drive circuit 1 or information on the operating condition of the apparatus and the positional information of the rotor 20. The output voltage of the circuit 4 is calculated. The output voltage calculation unit 120 outputs the calculated output voltage to the PWM signal generation unit 130. PWM is an abbreviation for Pulse Width Modulation.

  The PWM signal generation unit 130 outputs a PWM signal that becomes the output voltage given from the output voltage calculation unit 120 to the main element drive circuit 4a that drives each of the IGBTs 6a to 6f of the inverter main circuit 4, and the inverter main circuit 4 Each of the IGBTs 6a to 6f is switched by the main element drive circuit 4a.

  In the first embodiment, the inverter main circuit 4 is a three-phase bridge, but another inverter circuit such as a single phase may be used.

  Here, the wide band gap semiconductor will be described. A wide band gap semiconductor is a generic term for semiconductors having a larger band gap than Si, and SiC used in the SiC-SBDs 7a to 7f is one of the wide band gap semiconductors, in addition to gallium nitride (GaN), There are diamonds. Furthermore, wide band gap semiconductors, particularly SiC, have higher heat resistance temperature, dielectric breakdown strength, and thermal conductivity than Si. In the first embodiment, SiC is used for the FRD of the inverter circuit, but other wide band gap semiconductors may be used instead of SiC.

FIG. 14 is a diagram illustrating the first embodiment, and is a diagram illustrating a manufacturing process of the rotor 20. The manufacturing process of the rotor 20 will be described with reference to FIG.
(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 inserted 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). 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.
(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). The anti-load side rolling bearing shall be a “ceramic rolling element bearing”.

  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 can be arbitrarily set. 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 this embodiment, the resin magnet 22 of the ring-shaped rotor and the shaft 23 are integrated by the resin portion 24 injected by the vertical molding machine, and the resin magnet 22 of the rotor and the shaft are integrated. 23 is insulated, and the anti-load-side rolling bearing 21b supported by the metal (conductive) bracket 30 is a "ceramic rolling element bearing", so that the inner ring 21b-1 The outer ring 21b-2 is insulated and the shaft current is suppressed. Thereby, generation | occurrence | production of the electrolytic corrosion of the load side rolling bearing 21a and the anti-load side rolling bearing 21b can be suppressed. 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 shaft 23 and the bearing contact surface 24d, the shaft 23, the resin magnet 22 of the rotor, and position detection are provided. When the resin magnet 25 is integrally formed of resin, when the bearing contact surface 24d of the central cylinder portion 24g of the resin portion 24 is formed of ileco, the step portion 24e is formed of the eleco. Therefore, since the mating surface of the mold is the anti-load side end surface 24h of the central cylinder portion 24g, the anti-load side rolling bearing 21b is the anti-load that becomes the mating surface of the mold even if burrs occur on the mating surface of the mold. Since the stepped portion 24e is separated from the side end face 24h, the burr does not contact the anti-load side rolling bearing 21b. Therefore, there is little possibility of adversely affecting the anti-load side rolling bearing 21b.

  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.

  In addition, when the motor is driven by an inverter, the carrier frequency of the inverter is set higher for the purpose of reducing the noise of the motor. However, as the carrier frequency is set higher, high frequency induction is applied to the shaft of the motor. The shaft voltage generated based on this increases, and the potential difference existing between the inner ring and the outer ring of the rolling bearing supporting 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. It goes without saying that the same effect can be obtained in a sensorless drive system in which a flowing current is detected by a current detector (not shown) and the motor is operated.

  Further, according to the manufacturing process shown in FIG. 14, 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 molded into the mold. Since it is set and molded with resin, 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 can be arbitrarily set. 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. .

Embodiment 2. FIG.
FIG. 15 is a diagram showing 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.

  DESCRIPTION OF SYMBOLS 1 Motor built-in drive circuit, 2 Commercial AC power supply, 3 Rectifier circuit, 4 Inverter main circuit, 4a Main element drive circuit, 6a-6f IGBT, 7a-7f SiC-SBD, 8 DC voltage detection part, 8a Voltage dividing resistor, 8b Voltage divider resistor, 10 Mold stator, 10a Inner peripheral part, 10b Opening part, 11 Bearing support part, 11a Hole, 20 Rotor, 20-1 Rotor resin assembly, 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 For positioning Projection, 23 Shaft, 23a Knurl, 24 Resin part, 24a Inner diameter pressing part, 24b Taper part, 24c Resin injection part 24d Contact surface, 24e Stepped portion, 24f Fitting portion, 24g Center tube portion, 24h Anti-load side end surface, 24j Rib, 24k Cavity, 25 Position detecting resin magnet, 25a Rib, 25b Stepped, 30 Bracket, 30a Bearing Support part, 30b Press-fit part, 40 Stator, 41 Stator core, 42 Coil, 43 Insulating part, 44 terminal, 44a Power supply terminal, 44b Neutral point terminal, 45 Substrate, 46 Lead wire lead-out part, 47 Lead wire, 48 Prism, 49a IC, 49b Hall IC, 50 mold resin, 100 motor, 110 rotor position detector, 120 output voltage calculator, 130 PWM signal generator, 300 air conditioner, 310 indoor unit, 320 outdoor unit, 330 outdoor Blower for machine.

Claims (6)

A rotor of an electric motor in which a magnet and a shaft of a rotor are integrated by a resin portion, and rolling bearings are disposed on both axial end surfaces of the resin portion formed on the outer periphery of the shaft,
The rolling bearing includes an inner ring press-fitted into the shaft, an outer ring supported by a bearing support portion of a stator, and a rolling element that rolls between the inner ring and the outer ring,
One of the said rolling bearings is a ceramic bearing in which at least one of the said inner ring | wheel, the said outer ring | wheel, and the said rolling element is comprised with insulating materials, such as a ceramic, The rotor of the motor characterized by the above-mentioned.   An electric motor using the rotor of the electric motor according to claim 1. The rotor of the electric motor includes a position detection magnet,
The electric motor according to claim 2, wherein the electric motor is driven by an electric motor built-in drive circuit including the following elements:
(1) An inverter main circuit composed of a transistor and a diode that drives the motor by supplying AC power of variable frequency to the motor;
(2) A rotor position detection unit that detects the position of the rotor by detecting the position detection magnet with a position detection element;
(3) Optimum to be applied to the motor based on the target rotational speed command or information on the operating condition of the device given from outside the motor built-in drive circuit and the rotor position information of the rotor position detector An output voltage calculation unit for calculating the output voltage of the inverter main circuit;
(4) A PWM signal generation unit that generates a PWM (Pulse Width Modulation) signal to be the output voltage given from the output voltage calculation unit;
(5) A main element driving circuit for driving the transistor of the inverter main circuit.   The electric motor according to claim 3, wherein a Schottky barrier diode using SiC (silicon carbide) is used as the diode.   An air conditioner using the electric motor according to any one of claims 2 to 4 as an electric motor for a blower. A method of manufacturing a rotor of an electric motor in which a magnet and a shaft of a rotor are integrated by a resin portion, and rolling bearings are disposed on both axial end surfaces of the resin portion formed on the outer periphery of the shaft,
The rolling bearing includes an inner ring press-fitted into the shaft, an outer ring supported by a bearing support portion of a stator, and a rolling element that rolls between the inner ring and the outer ring,
A method for manufacturing a rotor of an electric motor, wherein a ceramic bearing in which at least one of the inner ring, the outer ring, and the rolling element is made of an insulating material such as ceramic is assembled to one of the rolling bearings.

Images