JP2014187754A - Rotor of motor, motor, air conditioner, and method of manufacturing rotor of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the rotor of a motor which allows for suppression of electrolytic erosion, while preventing generation of abnormal sound, by preventing an axial current flowing through a rolling bearing, without increasing the cost of the motor and without degrading the performance and quality, and to obtain a motor, an air conditioner, and a method of manufacturing the rotor of a motor.SOLUTION: In the rotor 20 of a motor 100 where the magnet (resin magnet 22) and the shaft 23 of the rotor are integrated by a resin portion 24, and rolling bearings 21a, 21b are attached to the shaft 23, an insulating sleeve 26 and a cavity 28 are interposed between the anti-load side rolling bearing 21b supported by a metal bracket 30 and the shaft 23.

Description

  The present invention relates to an electric motor rotor, an electric motor, an air conditioner, and a method for manufacturing the electric motor rotor.

  In the conventional electric motor, the carrier frequency of the inverter is set to a high value in order to reduce the noise of the electric motor generated with the switching of the transistor in the power circuit. However, as the carrier frequency increases, the shaft voltage generated by high frequency induction to the shaft of the motor increases, and the potential difference between the inner ring and the outer ring of the rolling bearing supporting the shaft increases, and current flows to the rolling bearing. Becomes easier to flow. The current flowing through the rolling bearings causes corrosion called electrolytic corrosion on the rolling surfaces of 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.

  In a conventional electric motor, in order to prevent the occurrence of electrolytic corrosion of the bearing, a stator around which a coil is wound, a frame for fixing the stator, and the stator are opposed to each other through a slight gap. In a rotating electrical machine having a rotating rotor, a rotating shaft to which the rotor is fixed, a rolling bearing that rotatably supports the rotating shaft via an O-ring, and a bearing bracket that supports the rolling bearing, A recess for inserting the O-ring is provided on a side of the rotating shaft that supports the rolling bearing or on an inner peripheral surface of the inner ring of the rolling bearing, and between a side surface of the inner ring of the rolling bearing and a step portion of the rotating shaft. Some have an insulating washer (see, for example, Patent Document 1).

  In addition, in the rotor of the electric motor in which the magnet and the shaft of the rotor are integrated by the resin portion and the rolling bearings are arranged on both axial end surfaces of the resin portion formed on the outer periphery of the shaft, at least one of the rolling bearings And an insulating sleeve that is integrated between the resin portion and the end surface on the side embedded in the resin portion of the insulating sleeve, and is formed at substantially equal intervals in the circumferential direction, with apexes near the end surface. An electric motor having a plurality of convex portions has been proposed (see, for example, Patent Document 2).

JP 2000-156952 A JP 2011-239508 A

  However, when electric corrosion is prevented by using an O-ring like the rotor of the electric motor shown in Patent Document 1, the O-ring, which is generally an elastic body such as rubber, is deformed during assembly. The O-ring is deformed when the rolling bearing is press-fitted and fixed to the rotating shaft via the pin, the gap between the rolling bearing and the rotating shaft is likely to vary, and these may come into contact with each other, ensuring the effect of preventing electrolytic corrosion. There is a problem that it is difficult to obtain. Further, the O-ring is deformed by external force during motor operation or vibration due to motor operation, and the gap between the stator and the rotor becomes non-uniform, which may reduce the efficiency of the motor.

  In the rotor of the electric motor shown in the above-mentioned Patent Document 2, there is a problem that the cost is increased in order to increase the effect on the shaft voltage and electric corrosion which increase as the efficiency and the noise of the electric motor increase. There is. For example, in order to increase the effect of preventing electric corrosion, increasing the thickness of the insulating sleeve can be mentioned, but increasing the thickness not only increases the material cost, but also reduces the strength because the shaft becomes thinner. There is also concern about the decline. In addition, the use of an insulating sleeve made of a material having a lower dielectric constant, that is, a material having a low dielectric constant, can also enhance the effect of preventing electrolytic corrosion, but there are few materials that can be selected from the dimensional accuracy and strength properties required for the insulating sleeve, and the cost is reduced. There is concern about the increase.

  The present invention has been made in view of the above, and prevents the shaft current flowing through the rolling bearing without increasing the cost of the motor and without reducing the performance and quality, and suppresses electrolytic corrosion. An object of the present invention is to obtain an electric motor rotor, an electric motor, an air conditioner, and a method for manufacturing the electric motor rotor capable of preventing the occurrence of abnormal noise.

  In order to solve the above-described problems and achieve the object, a rotor of an electric motor according to the present invention includes an electric motor in which a magnet and a shaft of a rotor are integrated by a resin portion, and a pair of rolling bearings is attached to the shaft. An insulating sleeve and a cavity are provided between at least one of the pair of rolling bearings and the shaft.

  According to the present invention, since the insulating sleeve and the cavity are provided between the shaft and the rolling bearing, the shaft current flowing through the rolling bearing is prevented without increasing the cost of the electric motor and without reducing the performance and quality. In addition, it is possible to suppress electric corrosion and to prevent the generation of abnormal noise.

FIG. 1 is a side sectional view of an electric motor according to an embodiment of the present invention. FIG. 2 is a side sectional view of the mold stator. FIG. 3 is a side sectional view showing a state in which the rotor is inserted into the mold stator. FIG. 4 is a side sectional view of the bracket. FIG. 5 is a perspective view of the stator. FIG. 6 is a side sectional view of the rotor. FIG. 7 is a cross-sectional view of the rotor from which the load side rolling bearing and the anti-load side rolling bearing have been removed. FIG. 8 is a side view of the rotor as viewed from the load side. FIG. 9 is a side view of the shaft assembly. FIG. 10 is an enlarged cross-sectional view of the end portion on the non-load side of the rotor. FIG. 11 is a view showing a resin magnet of the rotor. FIG. 12 is a diagram illustrating a resin magnet for position detection. FIG. 13 is a perspective view of the insulating sleeve of the first modification. FIG. 14 is a perspective view of the insulating sleeve of the second modification. FIG. 15 is a perspective view of an insulating sleeve of Modification 3. FIG. FIG. 16 is a perspective view of an insulating sleeve of Modification 4. FIG. 17 is a cross-sectional view of the rotor of the fifth modification. FIG. 18 is a cross-sectional view of a rotor according to the sixth modification. FIG. 19 is a circuit diagram of a drive circuit for driving the electric motor. FIG. 20 is a diagram illustrating a manufacturing process of the rotor. FIG. 21 is a configuration diagram of an air conditioner.

  Embodiments of a motor rotor, an electric motor, an air conditioner, and a method for manufacturing a motor rotor according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a side sectional view of an electric motor 100 according to an embodiment of the present invention. An electric motor 100 shown in FIG. 1 includes a mold stator 10, a rotor 20 (rotor of the electric motor) that is rotatably arranged inside an inner peripheral portion 10a of the mold stator 10, and an axial direction of the mold stator 10. A metal bracket 30 attached to one end is provided. Here, the mold stator 10 includes a stator 40 and a mold resin 50 that covers the stator 40, and the axial direction of the mold stator 10 coincides with the axial direction of the shaft 23 of the rotor 20. The electric motor 100 is, for example, a brushless DC motor having a permanent magnet in the rotor 20 and driven by an inverter.

  Although details will be described in sequence, in FIG. 1, as the constituent elements of the stator 40, a stator core 41, a coil 42 wound around the stator core 41, an insulating portion 43 provided on the stator core 41, A neutral point terminal 44b provided in the insulating portion 43, a substrate 45 attached to the insulating portion 43, a lead wire lead-out component 46 assembled to the substrate 45, a lead wire 47 lead out from the lead wire lead-out component 46, and a substrate 45 An IC (Integrated Circuit) 49a mounted above, a Hall IC 49b mounted on the surface of the substrate 45 on the rotor 20 side, and the like are shown. The rotor 20 is attached to the shaft assembly 27, the resin portion 24 that integrates the rotor main body and the shaft assembly 27, and the shaft 23, and is also supported by the bearing support portion 11 of the mold stator 10. 21a and an anti-load-side rolling bearing 21b attached to the shaft 23 and supported by the bracket 30. The shaft assembly 27 includes an insulating sleeve 26 including, for example, a pair of insulating sleeves 26-1 and 26-2, and the insulating sleeve 26 and the cavity 28 are disposed between the anti-load side rolling bearing 21 b and the shaft 23.

  FIG. 2 is a side sectional view of the mold stator 10. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals. The mold stator 10 is formed with an opening 10b at one end in the axial direction (right side in FIG. 2), and the rotor 20 is inserted into the opening 10b. A hole 11a slightly larger than the diameter of the shaft assembly 27 (FIG. 1) of the rotor 20 is formed in the other axial end portion (left side in FIG. 2) of the mold stator 10. Other configurations of the mold stator 10 will be described later.

  FIG. 3 is a side sectional view showing a state in which the rotor 20 is inserted into the mold stator 10. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals. In the rotor 20 inserted from the opening 10b (see FIG. 2) of the mold stator 10, the load side (left side in FIG. 3) of the shaft assembly 27 passes through the hole 11a (see FIG. 2) to the outside (FIG. 3). It is arranged to be pulled out to the left). At this time, the load-side rolling bearing 21 a attached to the shaft 23 is pushed in until it abuts on the bearing support portion 11 of the mold stator 10 and is supported by the bearing support portion 11. Here, the bearing support portion 11 is provided on the end portion in the axial direction of the mold stator 10 and on the side opposite to the opening. Further, an anti-load-side rolling bearing 21b is attached to the anti-load side (right side in FIG. 3) of the shaft assembly 27 (generally by press-fitting). Although details will be described later, an insulating sleeve 26 attached to the shaft 23 and a cavity 28 between the insulating sleeves 26-1 and 26-2 are provided between the anti-load side rolling bearing 21b and the shaft 23.

  FIG. 4 is a side sectional view of the bracket 30. The bracket 30 closes the opening 10 b of the mold stator 10 and supports the anti-load side rolling bearing 21 b and is press-fitted into the mold stator 10. The bracket 30 includes a bearing support portion 30a and a press-fit portion 30b formed integrally with the bearing support portion 30a. The bearing support portion 30a supports the anti-load side rolling bearing 21b. The press-fit of the bracket 30 to the mold stator 10 is performed by press-fitting a press-fit portion 30b having a ring shape and a substantially U-shaped cross section into the opening 10b side of the inner peripheral portion 10a of the mold stator 10. . The outer diameter of the press-fit portion 30b is larger than the inner diameter of the inner peripheral portion 10a by the press-fit allowance. The bracket 30 is made of metal (has conductivity) and is formed of, for example, a galvanized steel plate. However, it is not limited to this, The bracket 30 can also be formed from materials other than a galvanized steel plate.

  Hereinafter, the configuration of the mold stator 10 will be described. The 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. Since the stator 40 is attached with a substrate 45 and the like which will be described later and has a weak strength structure, low pressure molding is desirable. Therefore, a thermosetting resin such as an unsaturated polyester resin is used for the mold resin 50.

FIG. 5 is a perspective view of the stator 40. The stator 40 shown in FIG. 5 is configured as follows.
(1) A strip-shaped stator core 41 is manufactured by punching a magnetic steel sheet having a thickness of, for example, about 0.1 to 0.7 mm into a strip shape, and laminating by caulking, welding, adhesion, or the like. The stator core 41 includes a plurality of teeth (not shown). The teeth are provided inside the stator core 41.
(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) For example, a concentrated winding coil 42 is wound around the teeth provided with the 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, 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. Further, the substrate 45 to which the lead wire lead-out component 46 that leads out the lead wire 47 is attached is assembled to the insulating portion 43 to form the stator 40. The chamfered prism 48 with the chamfered insulating portion 43 is inserted into a prismatic insertion hole (not shown) provided in the substrate 45, thereby positioning in the rotation direction and the substrate mounting surface (not shown) of the insulating portion 43. ) Is positioned in the axial direction. Further, the prism 45 protruding from the substrate 45 is thermally welded to fix the substrate 45 and the insulating portion 43, and further, the portion protruding from the substrate 45 of the terminal 44 is soldered to be electrically connected. The Electronic components such as an IC 49 a (drive element) that drives the electric motor 100 (for example, a brushless DC motor) and a Hall IC 49 b (position detection element) that detects the position of the rotor 20 are mounted on the substrate 45.

  Next, the configuration of the rotor 20 will be described. 6 is a side sectional view of the rotor 20, FIG. 7 is a sectional view of the rotor 20-1 from which the load side rolling bearing 21a and the anti-load side rolling bearing 21b are removed, and FIG. 8 is a view of the rotor 20- viewed from the load side. 9 is a side view of the shaft assembly 27, and FIG. 10 is an enlarged cross-sectional view of the end portion on the side opposite to the load of the rotor 20.

  As shown in FIGS. 6 and 7, the rotor 20 (or the rotor 20-1) includes a shaft assembly 27 (see FIG. 9) provided with a knurling 23 a-1 and a rotor constituting a rotor body. Resin magnet 22 (rotor magnet), a position detection resin magnet 25 (position detection magnet) that also constitutes the rotor body, and a resin portion 24 that integrally molds these. The resin magnet 22 of the rotor and the resin magnet 25 for position detection are each ring-shaped around the shaft 23. The resin portion 24 is formed on the outer periphery centering on the knurling 23 a-1 in the base portion 23 e (FIG. 9) of the shaft assembly 27. The resin portion 24 includes a mold inner diameter pressing portion 24a for holding the inner diameter of the position detection resin magnet 25, and a taper portion 24b for easily setting the position detection resin magnet 25 in the mold (lower mold). , And a resin injection portion 24c at the time of resin molding.

  The resin magnet 22 of the rotor, the shaft assembly 27, and the position detection resin magnet 25 are integrated by a resin portion 24 injected by a vertical molding machine. At this time, as shown in FIG. 8, the resin portion 24 includes a central cylinder portion 24g (formed inside the rotor resin magnet 22) formed on the outer periphery of the shaft assembly 27, and a rotor resin magnet. 22 has a plurality of ribs 24j that are radially formed around the shaft assembly 27 and extend in the axial direction. A cavity 24k penetrating in the axial direction is formed between the ribs 24j. The resin used for the resin portion 24 is, for example, a thermoplastic resin such as PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide). 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 anti-load side (right side in FIG. 6) of the shaft assembly 27 (generally by press-fitting). A load-side rolling bearing 21a is attached to the load side (left side in FIG. 6) of the shaft assembly 27 to which a fan or the like is attached. The load-side rolling bearing 21a includes an inner ring 21a-1 that is press-fitted into the shaft assembly 27, 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. Rolling elements 21a-3 that roll between the two. 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 through an insulating sleeve 26 of the shaft assembly 27, an outer ring 21b-2 that is supported by a bearing support portion 30a of the bracket 30, and an inner ring 21b-1 and an outer ring. The rolling element 21b-3 which rolls between 21b-2 is provided. A ball or a roller is used for the rolling element 21b-3.

  The shaft assembly 27 according to the present embodiment is configured such that an insulating sleeve 26 is interposed between the anti-load-side rolling bearing 21b supported by the bracket 30 and the shaft 23, and a cavity 28 is provided. With this configuration, the anti-load-side rolling bearing 21 b and the shaft 23 are insulated from each other by the insulating sleeve 26 and the cavity 28. Since the insulation between the shaft 23 and the anti-load side rolling bearing 21b is based on the parallel connection of the capacitor by the insulating sleeve 26 and the cavity 28, the capacitor capacity can be reduced as compared with the conventional insulation by the insulating sleeve alone. That is, since the insulation resistance is large and the insulation performance is improved, the effect of suppressing the axial current between the anti-load side rolling bearing 21b and the shaft 23 is improved. Therefore, the occurrence of electrolytic corrosion of the load side rolling bearing 21a and the anti-load side rolling bearing 21b is further suppressed.

  In FIG. 9, the shaft assembly 27 includes a shaft 23 and an insulating sleeve 26. The insulating sleeve 26 is made of an insulating resin material and is fitted on the opposite side of the shaft 23. The insulating sleeve 26 includes, for example, an insulating sleeve 26-1 (first insulating sleeve) and an insulating sleeve 26-2 (second insulating sleeve), and there is a gap between the insulating sleeves 26-1 and 26-2. Is provided. In the rotor 20 according to the present embodiment, the shaft assembly 27 configured as described above, the rotor resin magnet 22, and the position detection resin magnet 25 are integrally formed by a resin portion 24 that is a thermoplastic resin. It consists of Further, on the outer periphery of the shaft 23, a knurl 23a-1 that functions as a rotation stopper and a stopper for the shaft 23 and the resin portion 24 is provided near the center of the base portion 23e.

  In FIG. 10, the outer periphery of the end portion 23d of the shaft 23 opposite to the load 23 is cut by the thickness of the insulating sleeve 26 (that is, the difference between the outer diameter d1 of the base 23e of the shaft 23 and the inner diameter of the insulating sleeve 26). . Specifically, the anti-load side end portion 23d is narrowed down into two steps by, for example, steps 23c-1 and 23c-2, and has a small diameter portion 23d- having an outer diameter d2-1 smaller than the outer diameter d1 of the base portion 23e. 1 (first small-diameter portion) and a small-diameter portion 23d-, which is provided on the opposite side of the small-diameter portion 23d-2 and has an outer diameter d2-2 smaller than the outer diameter d2-1 of the small-diameter portion 23d-2. 2 (second small diameter portion), the insulating sleeve 26-1 is assembled to the small diameter portion 23d-1, and the insulating sleeve 26-2 is assembled to the small diameter portion 23d-2. That is, the outer diameter d2-1 of the small diameter portion 23d-1 to which the insulating sleeve 26-1 is assembled is narrower than the outer diameter d1 of the base portion 23e of the shaft 23. Therefore, there is a gap between the base portion 23e and the small diameter portion 23d-1. A step 23c-1 is formed. Further, the outer diameter d2-2 of the small diameter portion 23d-2 to which the insulating sleeve 26-2 is assembled is thinner than the outer diameter d2-1. Therefore, between the small diameter portion 23d-1 and the small diameter portion 23d-2, A step 23c-2 is formed. As will be described later, the steps 23c-1 and 23c-2 are used for positioning to ensure a certain distance between the insulating sleeves 26-1 and 26-2. Further, the outer periphery of the anti-load side end portion 23d, specifically, for example, a part of the outer periphery of the small-diameter portion 23d-1 and the outer periphery of the small-diameter portion 23d-2, the anti-load-side end portion 23d and the insulating sleeve 26 are provided. A knurl 23a-2 is provided which functions as a detent and retainer. In addition, in the example of FIG. 10, the non-load side end surface 23f of the shaft 23 is exposed.

  The insulating sleeve 26 is formed of a resin having insulating properties, is formed with a predetermined thickness t1 and an axial length, and is formed in a ring shape having an outer diameter d3. The wall thickness t1 (shown only in the insulating sleeve 26-1 in FIG. 10, but the same applies to the insulating sleeve 26-2) is, for example, 1 to 2 mm, but is not limited to this range. . As for the axial length, the sum of the axial length L1 of the portion of the insulating sleeve 26-1 exposed from the resin portion 24 and the axial length L2 of the insulating sleeve 26-2 is the anti-load-side rolling bearing 21b. What is necessary is just to become a dimension shorter than the thickness (axial direction length). The outer diameter d3 is substantially the same as the outer diameter d1 of the base 23e of the shaft 23. The inner diameter of the insulating sleeve 26-1 is substantially the same as the outer diameter d2-1 of the small diameter portion 23d-1, and the inner diameter of the insulating sleeve 26-2 is substantially the same as the outer diameter d2-2 of the small diameter portion 23d-2. The insulating sleeve 26-1 is inserted and assembled into the small diameter portion 23d-1 until it contacts the step 23c-1, and the insulating sleeve 26-2 is inserted into the small diameter portion 23d-2 until it contacts the step 23c-2. As a result, the shaft assembly 27 is assembled. Since the insulating sleeves 26-1 and 26-2 are positioned by the steps 23c-1 and 23c-2 and are provided at a certain distance in the axial direction, the anti-load in which the insulating sleeves 26-1 and 26-2 are assembled is provided. By assembling the anti-load side rolling bearing 21b to the side end 23d, a cavity 28 is provided together with the insulating sleeve 26 between the shaft 23 and the anti-load side rolling bearing 21b (FIG. 6).

  The outer peripheral surface 26a of the insulating sleeve 26-1 is provided with a resin injection port extending in the axial direction with a width t2 and having a height h in the vicinity of the step 23c-1 of the shaft 23. This resin injection port is cut after molding and remains on the outer peripheral surface 26 a as a protruding gate cutting portion 26 b from the axial center of the shaft 23 toward the resin portion 24. However, the gate cutting portion 26b is embedded in the resin portion 24, and the anti-load-side rolling bearing 21b is inserted into a portion of the outer peripheral surface 26a of the insulating sleeve 26-1 exposed from the resin portion 24 to the anti-load side.

  In addition, when the gate cutting part 26b remains in the part exposed from the resin part 24 among the outer peripheral surfaces 26a of the insulating sleeve 26-1, the inner diameter part of the anti-load side rolling bearing 21b and the gate are inserted when the anti-load side rolling bearing 21b is inserted. An unexpected stress is generated due to contact with the cut portion 26b, and a reduction in quality is expected due to the gate cut portion 26b being cut and attached as dust. However, such a problem can be solved by providing the resin injection port in a portion embedded in the resin portion 24. Further, even when the gate cutting portion 26b is provided in a protruding shape from the axial center of the shaft 23 toward the resin portion 24 (or a protruding shape from the resin portion 24 toward the axial center of the shaft 23), the resin is injected. As a result, the gate cutting portion 26b functions as a detent for the insulating sleeve 26, so that the quality can be improved.

  The resin inlet of the insulating sleeve 26-2 is provided in the chamfered portion on the anti-load side (not shown). Providing the chamfered portion prevents protrusion to the outer peripheral side after the gate is cut, so that when the reversing rolling bearing 21b is inserted, the inner diameter portion of the anti-load side rolling bearing 21b and the gate cutting portion do not come into contact with each other, thereby preventing deterioration in quality. Is done.

As the material of the insulating sleeve 26, a resin material having substantially the same linear expansion coefficient as that of the shaft 23 is preferably used. The shaft 23 is made of, for example, iron. As such a resin material, for example, a BMC (bulk molding compound) resin of a thermosetting resin can be given. The BMC resin is a block clay-like thermosetting resin obtained by adding various additives to an unsaturated polyester resin. The BMC resin has the following characteristics.
(1) Productivity is good because the curing time is shorter than that of epoxy resin.
(2) Good balance between material cost and characteristics.
(3) Molding at low pressure is possible.
(4) High dimensional stability.
(5) The surface hardness is high and scratches are difficult to be scratched.
(6) Lighter than metal, excellent in moldability of complex shapes, and excellent in vibration absorption.

  In the rotor of the electric motor, stress is generated when the thermal history of rising and falling heat is received and the shaft 23 and the resin have different linear expansion coefficients. For this reason, a creep phenomenon (a phenomenon in which the deformation of the material increases with time under a certain load) occurs in the resin, and the part where the bearing is inserted may not be able to maintain the initial dimensions. . In such a case, creep of the inner ring of the bearing (a phenomenon in which a minute gap is generated between the inner ring and the shaft and the contact position is shifted by a difference in circumference every rotation) may be caused, and there is a concern that the quality may deteriorate. On the other hand, the quality can be improved by using a thermosetting resin having high creep resistance and using a BMC resin having a linear expansion coefficient close to that of the shaft 23.

  As described above, in the rotor 20 of the present embodiment, the shafts 27 are configured by assembling the insulating sleeves 26-1 and 26-2 on the anti-load side end 23 d in a manner of being separated in the axial direction. Since the insulating sleeves 26-1 and 26-2 are disposed between the rolling bearing 21 b and the shaft 23, the cavity 28 is provided together with the insulating sleeve 26 between the anti-load side rolling bearing 21 b and the shaft 23. According to such a configuration, the anti-load side rolling bearing 21b and the shaft 23 are insulated from each other by the insulating sleeve 26 and the cavity 28, so that the insulation resistance is higher than that in the case where the insulating sleeve 26 is insulated alone. As a result, the effect of suppressing the shaft current is improved, and the occurrence of electrolytic corrosion of the load side rolling bearing 21a and the anti-load side rolling bearing 21b is further suppressed. In the present embodiment, the position detecting resin magnet 25 is used. However, the structure of the present embodiment is also applicable to the rotor 20 in which the position detecting resin magnet 25 is not used.

  Note that the number of gate cutting portions 26 b is not limited to one, and a plurality of gate cutting portions 26 b may be provided in a portion embedded in the resin portion 24 on the outer peripheral surface 26 a of the insulating sleeve 26. In addition, a plurality of protrusions different from the gate cutting part 26 b may be provided on the portion embedded in the resin part 24 in the outer peripheral surface 26 a of the insulating sleeve 26. As a result, it is possible to more reliably prevent rotation and retain, and improve the quality.

  Further, the provision of the insulating sleeve 26 reduces the axial current flowing through the anti-load side rolling bearing 21b, and accordingly, the axial current flowing through the load side rolling bearing 21a also decreases. Therefore, it is not necessary to insulate the shaft 23 on the load side rolling bearing 21a side.

  In FIG. 10, a bearing abutment surface 24 d is formed at the end of the central cylinder portion 24 g of the resin portion 24 on the side opposite to the load side that serves as an axial positioning when the antiload side rolling bearing 21 b is assembled to the shaft assembly 27. Has been. Further, a step portion 24e is provided between the outer peripheral surface of the central cylindrical portion 24g and the bearing contact surface 24d. The step portion 24e includes an outer peripheral surface 24f that is lowered to the inner diameter side by one step from the outer peripheral surface of the central cylinder portion 24g, and an anti-load side end surface 24h that is parallel to the bearing contact surface 24d. The diameter d4 of the outer peripheral surface 24f can be formed smaller than the inner diameter of the outer ring 21b-2 of the anti-load side rolling bearing 21b. For example, as shown in FIG. 6, the inner ring 21b− of the anti-load side rolling bearing 21b It is desirable that the outer diameter is substantially the same as or slightly smaller than the outer diameter of 1.

  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 surfaces of the rolling bearing. Therefore, even if the diameter d4 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 does not contact the anti-load side rolling bearing 21b. Therefore, it is practical that the diameter d4 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.

  Further, by providing the stepped portion 24e, when the shaft assembly 27, the rotor resin magnet 22 and the position detecting resin magnet 25 are integrally formed of resin, the bearing contact of the central cylindrical portion 24g of the resin portion 24 is achieved. In the case where the surface 24d is formed by erection (nesting), it is formed by the erection up to the step 24e. Therefore, the mating surface of the mold is located on the non-load side end surface 24h of the central cylindrical portion 24g. Then, even when burrs occur on the mating surface of the mold, the anti-load side rolling bearing 21b is separated from the anti-load side end surface 24h serving as the mating surface of the mold by the axial length of the step portion 24e. This burr does not contact the anti-load side rolling bearing 21b. Therefore, there is little possibility that this burr adversely affects 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 portions 24e are provided at both ends (the load side and the anti-load side) of the central tube portion 24g, the radial dimensions of the step portions 24e are fixed, and the center tube between the step portions 24e at both ends is provided. This can be dealt with by increasing the radial thickness of the portion 24g.

  Further, when the stepped portion 24e is provided at both ends (the load side and the anti-load side) of the central cylindrical portion 24g, the diameter d4 of the outer peripheral surface 24f constituting the stepped portion 24e is set to the outer ring 21a-2 of the load side rolling bearing 21a. It can be formed smaller than the inner diameter and smaller than the inner diameter of the outer ring 21b-2 of the anti-load side rolling bearing 21b. In this case, the thickness in the radial direction of the central cylindrical portion 24g between the stepped portions 24e can be made larger than the inner diameters of the outer rings 21a-2 and 21b-2.

  11A and 11B are views showing the resin magnet 22 of the rotor. FIG. 11A is a left side view, FIG. 11B is a cross-sectional view taken along the line CC in FIG. 11A, and FIG. It is. The configuration of the resin magnet 22 of the rotor will be described with reference to FIG. The rotor resin magnet 22 is coaxially secured at one end in the axial direction on the inner diameter side (right side in FIG. 11B) between the shaft assembly 27 and the rotor resin magnet 22 during mold clamping during resin molding. A notch 22a is formed for this purpose. In the example of FIG. 11C, the notches 22a are formed at, for example, eight locations at approximately equal intervals in the circumferential direction.

  Further, on the resin magnet 22 of the rotor, a pedestal 22b on which the position detection resin magnet 25 is placed is formed on the end surface of the other axial end portion (left side in FIG. 11B) at substantially equal intervals in the circumferential direction, for example. Has been. The base 22b is formed on the inner diameter side of the resin magnet 22 of the rotor, and the positioning protrusion 22c extends from the base 22b toward the outer diameter side of the resin magnet 22 of the rotor. The positioning protrusion 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 assembly 27 are integrally formed by the resin portion 24. The

  The configuration of the position detection resin magnet 25 will be described with reference to FIG. 12A and 12B are diagrams showing the position detecting resin magnet 25. FIG. 12A is a left side view, FIG. 12B is a front view, and FIG. 12C is an enlarged view of a portion D in FIG. is there. The position detecting resin magnet 25 includes steps 25b at both axial end portions on the inner diameter side. The step 25b on the end side in the axial direction of the rotor 20 is filled with a part of the resin portion 24, and this step 25b functions as a retaining member for the position detecting resin magnet 25 in the axial direction.

  FIG. 12 shows a position detecting resin magnet 25 having steps 25b at both ends in the axial direction as an example. However, a step 25b is provided at one of the end portions in the axial direction, which is the rotor 20. What is necessary is just to be located in the axial direction edge part side. However, in the case where the step 25b is provided at both ends in the axial direction, when the resin magnet 24 for position detection is set on the mold (lower mold) when the rotor 20 is integrally formed with the resin portion 24, the back and front are not bothered. Excellent workability.

  In addition, the position detecting resin magnet 25 includes eight ribs 25a (a cross section is substantially triangular) that are circumferentially detents when embedded in the resin portion 24 at substantially equal intervals in the circumferential direction. The rib 25a is disposed at a position where the step 25b is formed. However, the number, shape, and arrangement interval of the ribs 25a are not limited to the illustrated example, and may be arbitrary.

  As shown in FIG. 6, in the resin portion 24, a mold inner diameter pressing portion 24 a that holds the inner diameter of the position detection resin magnet 25 and the position detection resin magnet 25 are set in a mold (lower mold). The taper portion 24b for facilitating the process and the resin injection portion 24c for resin molding are formed after the resin molding.

  The rotor resin magnet 22 is formed by mixing a thermoplastic material with a magnetic material. As shown in FIG. 11, as shown in FIG. 11, the inner diameter side is provided with a notch 22 a tapered from one end surface in the axial direction. A pedestal 22b is provided on the other end surface in the axial direction opposite to the one end surface in the axial direction with the notch 22a. The base 22b of the rotor resin magnet 22 formed integrally with the shaft assembly 27 makes it possible to separate the position detection resin magnet 25 from the end surface of the rotor resin magnet 22. The thickness can be minimized and can be arranged 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. 12, the position detecting resin magnet 25 includes steps 25b on both sides in the thickness direction, and ribs 25a that prevent rotation when embedded in the resin on both steps 25b. 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 assembly 27, the outer periphery of the position detection resin magnet 25 is filled with a taper-shaped resin (resin portion 24) to cope with variations in the outer diameter of the position detection resin magnet 25. Since the resin to be filled is blocked by the axial end surface (outside) on one side of the resin magnet 25 for position detection and the axial end surfaces of the resin magnet 22 of the rotor, there is a burr on the outer diameter of the resin magnet 22 of the rotor. It is possible to suppress the occurrence, and the quality is improved.

  In addition, the gate port at the time of integral molding with the shaft assembly 27 is disposed further inside than the inner diameter of the resin magnet 22 of the rotor, and the resin injection portion 24c is disposed in a convex shape, thereby reducing pressure concentration, The resin can be easily filled, and the convex portion of the resin injection portion 24c can be used for positioning.

  FIG. 13 is a perspective view of an insulating sleeve of Modification 1 of the present embodiment. 13A shows a state before the insulating sleeves 26-1 and 26-2 are assembled to the shaft 23, and FIG. 13B shows a state after the insulating sleeves 26-1 and 26-2 are assembled to the shaft 23. Shows the state. 13 is different from the insulating sleeve 26 shown in FIG. 6 in that support portions 26-1a and 26-2a projecting in the axial direction are provided on end surfaces of the insulating sleeves 26-1 and 26-2 so as to support each other. By assembling, the insulating sleeves 26-1 and 26-2 are positioned at regular intervals. That is, the non-load side end surface of the insulating sleeve 26-1 is formed in an annular shape, and a support portion 26-1a extending in the axial direction is provided on the anti-load side end surface. Further, the load side end surface of the insulating sleeve 26-2 is formed in an annular shape, and a support portion 26-2a extending in the axial direction is provided on the load side end surface. The lengths of the insulating sleeves 26-1 and 26-2 in the axial direction are equal. The insulating sleeves 26-1 and 26-2 are arranged with a phase shifted in the circumferential direction so that the support portions 26-1a and 26-2a do not interfere with each other. In the illustrated example, the support portions 26-1a and 26-2a are arranged with a 180 ° phase shift in the circumferential direction, for example. The support portion 26-1a of the insulation sleeve 26-1 contacts the load side end surface of the insulation sleeve 26-2, and the support portion 26-2a of the insulation sleeve 26-2 contacts the non-load side end surface of the insulation sleeve 26-1. By contact, the insulating sleeves 26-1 and 26-2 are positioned, and the insulating sleeves 26-1 and 26-2 are assembled to the non-load side end 23 d of the shaft 23. On the outer peripheral surface on the load side of the insulating sleeve 26-1, a gate cutting portion 26b and a plurality of protrusions 26e are provided in the circumferential direction.

  Although the support portions 26-1a and 26-2a are provided on the insulating sleeves 26-1 and 26-2 one by one, a configuration in which one or more support portions 26-1a and 26-2a are provided on at least one side is also possible.

  As shown in FIG. 13, in the present modification, the inner diameters of the insulating sleeves 26-1 and 26-2 are the same. That is, since the insulating sleeves 26-1 and 26-2 are positioned by the support portions 26-1 a and 26-2 a, it is not necessary to provide the step 23 c-2 at the anti-load side end portion 23 d of the shaft 23. The outer diameter of the side end 23d is constant d2 (= d2-1 = d2-2), and the inner diameters of the insulating sleeves 26-1 and 26-2 can be the same. Therefore, shaft processing is simplified and cost reduction can be achieved.

  FIG. 14 is a perspective view of the insulating sleeve of the second modification. In FIG. 14, the difference from the insulating sleeve 26 shown in FIG. 6 is that the insulating sleeve 26 is not separated into two parts, but is integrated, and a slit 26c extending in the axial direction is formed on the side surface of the substantially cylindrical insulating sleeve 26. It is a point. The slit 26c is, for example, the same length as the axial direction length of the anti-load side rolling bearing 21b and has a constant width. Further, the slit 26c is provided with a certain length in the axial direction from the end face on the side opposite to the load of the insulating sleeve 26, for example.

  In the present modification, similarly to the first modification, the step 23c-2 does not need to be provided at the opposite end 23d of the shaft 23, and the shaft processing is simplified. Further, since the insulating sleeve 26 has an integral structure, the manufacturing cost of the insulating sleeve 26 can be reduced. Furthermore, since the insulating sleeve 26 has an integral structure and is integrally formed with the resin portion 24, the insulating sleeve 26 is prevented from being rotated and prevented from coming off by the gate cutting portion 26b and the protrusion 26e, and can be securely fixed by a simple method, thereby improving the quality. Further, the knurling 23a-2 at the opposite end 23d of the shaft 23 can be eliminated and the assembly can be simplified, so that the cost can be further reduced. In FIG. 14, one slit 26c is used, but a plurality of slits may be used. Thereby, insulation performance is improved more and the electrolytic corrosion inhibitory effect can be improved.

  FIG. 15 is a perspective view of an insulating sleeve of Modification 3. FIG. 15 differs from the insulating sleeve 26 shown in FIG. 6 in that the insulating sleeve 26 is integrated into one piece without being separated into two, and a plurality of slits 26c extending in the axial direction on the side surface of the substantially cylindrical insulating sleeve 26. And a plurality of slits 26c extending in the axial direction from the non-load side end surface of the insulating sleeve 26 and those extending in the axial direction from the load side end surface of the insulating sleeve 26 are alternately arranged in the circumferential direction. This is the point formed. In the illustrated example, four slits 26c-1 extending in the axial direction from the end surface on the anti-load side of the insulating sleeve 26 and four slits 26c-2 extending in the axial direction from the end surface on the load side of the insulating sleeve 26 are alternately formed in the circumferential direction. Has been. According to such a configuration, the number of slits 26c at each end of the insulating sleeve 26 can be reduced, and the accuracy of the outer diameter of the insulating sleeve 26 can be easily maintained. On the outer peripheral surface on the load side of the insulating sleeve 26, a gate cutting portion 26b and a plurality of protrusions 26e are provided in the circumferential direction.

  In the present modification, similarly to the first modification, the step 23c-2 does not need to be provided at the opposite end 23d of the shaft 23, and the shaft processing is simplified. Further, since the insulating sleeve 26 has an integral structure, the manufacturing cost of the insulating sleeve 26 can be reduced. Furthermore, since the insulating sleeve 26 has an integral structure and is integrally formed with the resin portion 24, the insulating sleeve 26 is prevented from being rotated and prevented from coming off by the gate cutting portion 26b and the protrusion 26e, and can be securely fixed by a simple method, thereby improving the quality. Further, the knurling 23a-2 at the opposite end 23d of the shaft 23 can be eliminated and the assembly can be simplified, so that the cost can be further reduced.

  FIG. 16 is a perspective view of an insulating sleeve of Modification 4. In FIG. 16, the difference from the insulating sleeve 26 shown in FIG. 6 is that the insulating sleeves 26-1 and 26-2 constituting the insulating sleeve 26 are not separated and are integrated with the connecting portion 26 d. . That is, a part of the annular load-side end face of the insulating sleeve 26-1 and a part of the annular non-load-side end face of the insulating sleeve 26-2 are connected by the connecting portion 26d extending in the axial direction. In this modified example, the cavity 28 can be made larger compared to the modified examples 2 and 3 in which the insulating sleeve 26 has an integral structure. In FIG. 16, a gate cutting portion 26 b and a plurality of protrusions 26 e in the circumferential direction are provided on the outer peripheral surface on the load side of the insulating sleeve 26-1.

  Further, in this modification, similarly to the first modification, the step 23c-2 does not have to be provided at the anti-load side end 23d of the shaft 23, and the shaft processing is simplified. Further, since the insulating sleeve 26 has an integral structure, the manufacturing cost of the insulating sleeve 26 can be reduced. Furthermore, since the insulating sleeve 26 has an integral structure and is integrally formed with the resin portion 24, the insulating sleeve 26 is prevented from being rotated and prevented from coming off by the gate cutting portion 26b and the protrusion 26e, and can be securely fixed by a simple method, thereby improving the quality. Further, the knurling 23a-2 at the opposite end 23d of the shaft 23 can be eliminated and the assembly can be simplified, so that the cost can be further reduced.

  FIG. 17 is a cross-sectional view of the rotor 20a of the fifth modification. 17 is different from the rotor 20 shown in FIG. 6 in that a center hole 23 b is formed on the end surface on the side opposite to the load of the shaft assembly 27. The mold (upper mold) is provided with a protrusion (not shown) whose coaxiality with the center of the center hole 23b is provided. The shaft assembly 27, the resin magnet 22 of the rotor, and the position detection resin magnet 25 are provided. When the mold is closed when the resin portion 24 is integrated (molded), the projection of the mold is fitted into the center hole 23b of the shaft, so that the resin magnet 22 of the rotor and the shaft assembly 27 are connected. The coaxiality is improved. The center hole 23b may be formed at both ends of the shaft 23.

  FIG. 18 is a cross-sectional view of the rotor 20b of the sixth modification. 18 is different from the rotor 20 shown in FIG. 6 in that an insulating sleeve 26 is also provided between the load-side rolling bearing 21a and the shaft 23, and the cavity 28 is provided between the insulating sleeves 16-1 and 26-2. Is a point provided. Thus, by providing the insulating sleeve 26 also between the load side rolling bearing 21a and the shaft 23, the axial current in the load side rolling bearing 21a can be further reduced. Furthermore, even in the case of an electric motor in which a material other than a mold is used for the outer shell (for example, a steel plate frame for the outer shell) and a metal bracket is used on the load side and the non-load side, the axial current can be reduced. .

  FIG. 1 shows an electric motor 100 configured such that the mold stator 10 side is a load side and the bracket 30 side is an anti-load side. However, the electric motor 100 includes a load side and an anti-load side. Even when configured to be reversed, the same effect can be obtained. Accordingly, in general, the insulating sleeve 26 is provided between the load side rolling bearing 21a and the shaft 23, between the anti-load side rolling bearing 21b and the shaft 23, or both the load-side rolling bearing 21a and the anti-load side rolling bearing 21b. A structure provided between the shaft 23 and the shaft 23 is possible. Further, the rotors 20, 20a, and 20b shown in FIGS. 6, 17, and 18 use a rotor resin magnet 22 formed by mixing a magnetic material with a thermoplastic resin as a permanent magnet. Permanent magnets (rare earth magnets (neodymium, samarium 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 described above, when the motor is operated using the inverter, the carrier frequency of the inverter is set to a high value in order to reduce the noise of the motor generated due to the switching of the transistors in the power circuit. As the carrier frequency is set higher, the shaft voltage generated by high frequency induction to the shaft of the motor increases, and the potential difference existing between the inner ring and the outer ring of the rolling bearing supporting the shaft increases. It becomes easier for the current to flow through the rolling bearing. The current flowing through the rolling bearings causes corrosion called electrolytic corrosion on the rolling surfaces of 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. .

  In the rotor 20 of the present embodiment, the shaft 23 is insulated from at least one of the load-side rolling bearing 21a and the anti-load-side rolling bearing 21b by the insulating sleeve 26 and the cavity 28, and the axial current is suppressed. As described above, the rotor 20 of the present embodiment is particularly effective for reducing the shaft current generated when the electric motor 100 is operated using an inverter.

  FIG. 19 is a circuit diagram of the drive circuit 1 built in the electric motor 100. As shown in FIG. 19, AC power is supplied to the drive circuit 1 from a commercial AC power supply 2 provided outside the electric 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 is provided with 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 includes six IGBTs 6a to 6f (insulated gate bipolar transistors) serving as inverter main elements and six flywheel diodes (FRD). SiC-SBDs 7a to 7f (Schottky barrier diodes) using silicon carbide (SiC) 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 present embodiment, it is assumed that an IC module in which IGBTs 6a to 6f and SiC-SBDs 7a to 7f are mounted on the same lead frame and molded with an epoxy resin is used. The IGBTs 6a to 6f may be IGBTs using SiC or GaN instead of the IGBT using silicon (Si-IGBT). Further, instead of the IGBT, other switching elements such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) using Si, SiC, or GaN 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 lowered by the voltage-dividing circuit using the voltage-dividing resistors 8a and 8b. Is done. The drive circuit 1 is provided with a DC voltage detector 8 that samples and holds the reduced electric signal.

  Moreover, the rotor 20 (FIG. 6) and the mold stator 10 (FIG. 2) according to the present embodiment are used for the electric motor 100, and the stator 10 is rotated by AC power supplied from the inverter main circuit 4. The child 20 is rotated. The mold stator 10 includes a Hall IC 49b for detecting the position detection resin magnet 25 in the vicinity of the rotor 20, and a rotor position where electric signals from the Hall IC 49b are processed and converted into position information of the rotor 20. A 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 includes a command for the target rotational speed N (speed command signal for commanding the rotational speed of the rotor 20) or information on the operating conditions of the apparatus, and the position of the rotor 20 given from the outside of the drive circuit 1. Based on the information, an optimum output voltage of the inverter main circuit 4 to be applied to the electric motor 100 is calculated. The output voltage calculation unit 120 outputs this output voltage to a PWM (Pulse Width Modulation) signal generation unit 130. 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, so that the inverter main The IGBTs 6a to 6f of the circuit 4 are switched by the main element driving circuit 4a. In the present 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 this embodiment, SiC is used for the FRD of the inverter circuit. However, other wide band gap semiconductors may be used instead of SiC.

FIG. 20 is a diagram illustrating a manufacturing process of the rotor 20. An example of the manufacturing process of the rotor 20 will be described with reference to FIG.
(1) The insulating sleeve 26 is molded with BMC resin. Further, after the position detecting resin magnet 25 and the rotor resin magnet 22 are molded, demagnetization is performed. Further, the shaft 23 is processed. A knurling 23a-2 is applied to the shaft 23 near the center of the base 23e and the end 23d on the side opposite to the load. Further, steps 23c-1 and 23c-2 are formed at the opposite end portion 23d (step 1).
(2) An insulating sleeve 26 is assembled to the shaft 23 to form a shaft assembly 27. Specifically, the insulating sleeves 26-1 and 26-2 are inserted into the opposite end 23d of the shaft 23 until they abut against the steps 23-1 and 23-2, respectively. 2 is assembled to the shaft 23 (step 2).
(3) The position detection resin magnet 25 is set on the lower mold with the end portion having the step 25b facing downward, and the inner diameter pressing portion 24a provided on the lower mold holds the inner diameter of the position detection resin magnet 25 ( Step 3).
(4) 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 4).
(5) The shaft assembly 27 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 holding portion of the upper mold (step 5).
(6) Resin (resin portion 24) is molded (step 6). When the resin magnet 22 of the rotor, the resin magnet 25 for position detection, and the shaft assembly 27 are integrally formed by the resin portion 24, the shaft assembly 27 and at least one of the load side rolling bearing 21a or the anti-load side rolling bearing 21b Between them, integral molding is performed so that the insulating sleeve 26 is interposed.
(7) The position detecting resin magnet 25 and the rotor resin magnet 22 are magnetized (step 7).
(8) The load side rolling bearing 21a and the anti-load side rolling bearing 21b are assembled to the shaft assembly 27 (step 8).

  According to the above manufacturing process, when the resin assembly 22 of the rotor and the shaft assembly 27 assembled with the insulating sleeve 26 and the resin magnet 25 for position detection are integrated with the resin (resin portion 24), Since the parts are set in a mold and resin-molded, the cost of the rotor 20 can be reduced by reducing the work process.

  Further, since the knurling 23a-2 is applied to the opposite end 23d of the shaft 23 and the insulating sleeve 26 is press-fitted into the shaft assembly 27, movement of the insulating sleeve 26 in the axial direction and the circumferential direction can be suppressed.

  Further, the position detection resin magnet 25 can be separated from the end surface of the rotor resin magnet 22 by the base 22b of the resin magnet 22 of the rotor, and the thickness of the resin magnet 25 for position detection can be minimized and arbitrarily set. It becomes possible to dispose the thermoplastic resin less expensive than the resin magnet 22 of the rotor, and the cost can be reduced.

  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.

  Also, when the lower mold position detecting resin magnet 25 is set, the portion through which the outer diameter passes is tapered so that the opening becomes wider (tapered portion 24b of the resin portion 24), so that the lower die 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 detection 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, so that the accuracy of the coaxiality with the shaft assembly 27 and the resin magnet 22 of the rotor is increased. Secured.

  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 assembly 27 and the resin magnet 22 of the rotor is ensured. The

  FIG. 21 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. An indoor unit blower (not shown) is mounted on the indoor unit 310, and an outdoor unit blower 330 is mounted on the outdoor unit 320. The outdoor unit blower 330 and the indoor unit blower use the electric motor 100 of the present embodiment as a drive source. The durability of the air conditioner 300 can be improved by using the electric motor 100 for the outdoor unit blower 330 and the indoor unit blower that are main components of the air conditioner 300.

  In addition, the electric motor 100 concerning this Embodiment can be mounted and utilized for electric equipments (for example, a ventilation fan, household appliances, a machine tool, etc.) other than the air conditioner 300. FIG.

  As described above, in the rotor 20 of the electric motor according to the present embodiment, the rotor magnet (resin magnet 22) and the shaft 23 are integrated by the resin portion 24, and the rolling bearings 21a and 21b are mounted on the shaft 23. An insulating sleeve 26 and a cavity 28 are interposed between a shaft 23 and an anti-load side rolling bearing 21b which is a rotor 20 of the attached electric motor 100 and supported by a metal (conductive) bracket 30. As a result, the anti-load side rolling bearing 21b and the shaft 23 are insulated from each other by the insulating sleeve 26 and the cavity 28, so that not only the effect of suppressing the axial current can be enhanced, but also an increase in cost can be suppressed, resulting in higher efficiency and lower noise. Electric corrosion of the motor can be prevented. As a result, it is possible to improve the quality and performance of the electric motor 100 and reduce the cost.

  Further, by providing the resin inlet of the insulating sleeve 26 in the portion embedded in the resin portion 24, the resin inlet is in a portion exposed from the resin portion 24 on the outer peripheral surface of the insulating sleeve 26, and the gate cutting portion 26 b Concerns about remaining as a protrusion (protrusion) are eliminated.

  Further, since the chamfered portion is provided with the resin injection port of the insulating sleeve 26, the protrusion to the outer peripheral side can be prevented after the gate is cut, so that the concern when the gate cut portion remains as the protruding portion is eliminated.

  In addition, by providing the plurality of protrusions 26e in the portion embedded in the resin portion 24 in the outer peripheral surface of the insulating sleeve 26, the axial movement and the circumferential movement of the insulating sleeve 26 can be further suppressed.

  When the insulating sleeve 26 is interposed between the load-side rolling bearing 21a and the anti-load-side rolling bearing 21b and the shaft 23, the shaft current in the load-side rolling bearing 21a and the anti-load-side rolling bearing 21b is further increased. Can be reduced. In the case of an electric motor in which a material other than a mold is used for the outer shell (for example, a steel plate frame for the outer shell) and a metal bracket 30 is used on the load side and the anti-load side, the axial current can be reduced.

  Further, since the insulating sleeve 26 is made of a resin material having substantially the same linear expansion coefficient as that of the shaft 23, the occurrence of creep between the bearing inner ring and the insulating sleeve 26 is suppressed, and the quality of the electric motor 100 is improved. Improvements can be made.

  Further, as the material of the insulating sleeve 26, for example, BMC (bulk molding compound) resin, which is a thermosetting resin, is used, the occurrence of creep between the bearing inner ring and the insulating sleeve 26 is suppressed, and the electric motor 100 The quality can be improved.

  Further, the rotor 20 of the electric motor according to the present embodiment has a stepped portion 24e between the central cylindrical portion 24g of the resin portion 24 formed on the outer peripheral surface of the base portion 23e of the shaft 23 and the bearing contact surface 24d. When the shaft 23, the rotor resin magnet 22 and the position detection resin magnet 25 are integrally formed of resin, the bearing contact surface 24d of the central cylindrical portion 24g of the resin portion 24 is formed in an irico manner. The step portion 24e is formed with the above-mentioned eroko. For this reason, the mating surface of the mold becomes the anti-load side end surface 24h of the central cylindrical portion 24g, so that even if burrs occur on the mating surface of the mold, the anti-load side rolling bearing 21b is the anti-load that becomes the mating surface of the mold. Since the axial length of 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 step portion 24e is provided at both ends of the central cylindrical portion 24g, and the central cylindrical portion 24g between the stepped portions 24e is provided. This can be dealt with by increasing the thickness in the radial direction.

  The insulating sleeve 26 is provided with support portions 26-1a and 26-2a projecting in the axial direction on the end surfaces of the insulating sleeves 26-1 and 26-2, and these support portions 26-1a and 26-2a support each other. As a result, the insulating sleeves 26-1 and 26-2 may be assembled at a predetermined interval. In this case, the inner diameters of the insulating sleeves 26-1 and 26-2 can be made the same, the step 23 c-2 of the shaft 23 does not have to be provided, the shaft processing is simplified, and the cost can be reduced. .

  Further, the insulating sleeve 26 may be integrally formed without being separated into two, and a slit 26c extending in the axial direction may be provided on the side surface of the substantially cylindrical shape. In this case, the step 23c-2 does not have to be provided at the opposite end 23d of the shaft 23, and the shaft processing is simplified. Further, since the insulating sleeve 26 is integrated, the manufacturing cost of the insulating sleeve 26 is reduced, the assembly is simplified, and the cost can be further reduced. A plurality of slits 26c may be provided. Thereby, insulation performance is improved more and the electrolytic corrosion inhibitory effect can be improved.

  The insulating sleeve 26 is integrally formed without being separated into two, and a plurality of slits 26c extending in the axial direction are provided on the side surface of the substantially cylindrical insulating sleeve 26, and the plurality of slits 26c are insulated. Even if the slits 26c are alternately inserted in the axial direction by alternately arranging the one extending in the axial direction from the end surface on the non-load side of the sleeve 26 and the one extending in the axial direction from the end surface on the load side of the insulating sleeve 26. Good. Thereby, the number of the slits 26c can be reduced at each end of the insulating sleeve 26, and the accuracy of the outer diameter of the insulating sleeve 26 is easily maintained. Further, the step 23c-2 of the shaft 23 may not be provided, and the shaft processing is simplified. Further, since the insulating sleeve 26 is integrated, the manufacturing cost of the insulating sleeve 26 is reduced, the assembly is simplified, and the cost can be further reduced.

  Further, the insulating sleeve 26 may be integrally formed by connecting the insulating sleeves 26-1 and 26-2 constituting the insulating sleeve 26 with a connecting portion 26 d without being separated. In this case, since the cavity 28 can be enlarged, the electrolytic corrosion suppression effect is also enhanced. Further, it is not necessary to provide the step 23c-2 on the shaft 23, and the shaft processing is simplified. Further, since the insulating sleeve 26 is integrated, the manufacturing cost of the insulating sleeve 26 is reduced, the assembly is simplified, and the cost can be further reduced.

  Further, as in the rotor 20a shown in FIG. 17, a center hole 23b is formed on the end surface on the side opposite to the load of the shaft 23, so that the shaft assembly 27, the resin magnet 22 of the rotor, and the position detection resin magnet 25 are made of resin. When the molding is integrally performed, the shaft assembly 27 is held in a state where the coaxiality is secured by fitting the protrusions provided in the molds (upper mold and lower mold) into the center hole 23b of the shaft 23. Thus, the coaxiality between the resin magnet 22 of the rotor and the shaft assembly 27 is improved.

  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 to the shaft of the motor is performed. The shaft voltage generated by the above 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. Needless to say, the sensorless driving method in which the flowing current is detected by a current detector (not shown) and the motor is driven using a microcomputer or the like in the waveform generation circuit has the same effect.

  It should be noted that the motor rotor, the motor, the air conditioner, and the method for manufacturing the motor rotor according to the embodiment of the present invention show an example of the contents of the present invention, and are another known technique. Of course, it is possible to combine with the above, and it is possible to change and configure such as omitting a part without departing from the gist of the present invention.

  As described above, the present invention can be applied to a rotor of an electric motor, and is particularly useful as an invention that can suppress electric corrosion of a bearing without increasing the performance, quality, and cost of the electric motor. is there.

  DESCRIPTION OF SYMBOLS 1 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 division Resistance, 10 Mold stator, 10a Inner circumference, 10b Opening, 11 Bearing support, 11a Hole, 20, 20a, 20b, 20-1 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-1, 23a-2 knurled, 23b center hole, 23c-1, 23c-2 step, 23d counter load side end, 3d-1, 23d-2 Small diameter part, 23e base part, 23f Anti-load side end face, 24 resin part, 24a inner diameter pressing part, 24b taper part, 24c resin injection part, 24d bearing contact surface, 24e step part, 24f outer peripheral face 24g Central cylinder part, 24h End face on the opposite side of load, 24j rib, 24k cavity, 25 position detection resin magnet, 25a rib, 25b step, 26, 26-1, 26-2 Insulating sleeve, 26-1a, 26-2a Support part, 26a outer peripheral surface, 26b gate cutting part, 26c slit, 26d connecting part, 26e protrusion, 27 shaft assembly, 28 cavity, 30 bracket, 30a bearing support part, 30b press-fitting 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 part, 47 lead wire, 48 prism, 49a IC, 49b Hall IC, 50 mold resin, 100 electric motor, 110 rotor position detector, 120 output voltage calculator, 130 PWM signal generator, 300 air conditioner, 310 indoor unit, 320 outdoor unit, 330 blower for outdoor unit.

Claims (16)

A rotor of an electric motor in which a magnet and a shaft of a rotor are integrated by a resin portion, and a pair of rolling bearings is attached to the shaft,
An electric motor rotor, wherein an insulating sleeve and a cavity are provided between at least one of the pair of rolling bearings and the shaft.   The motor rotor according to claim 1, wherein a resin material having substantially the same linear expansion coefficient as that of the shaft is used as a material of the insulating sleeve.   The insulating sleeve includes first and second insulating sleeves arranged at a certain distance in the axial direction of the shaft, and the cavity is provided between the first insulating sleeve and the second insulating sleeve. The electric motor rotor according to claim 1, wherein the electric motor rotor is provided.   The first and second insulating sleeves are separated from each other, and one step in the axial direction of the shaft is provided with two steps separated in the axial direction, and the first step is provided at one step. The axial positioning of said 1st and 2nd insulation sleeve is carried out by abutting an insulation sleeve and abutting said 2nd insulation sleeve to the other level | step difference, The Claim 3 characterized by the above-mentioned. Electric motor rotor.   The first and second insulating sleeves are separated from each other, and end portions of the first and second insulating sleeves are provided with support portions of the same length extending in the axial direction, respectively, The supporting portion of the insulating sleeve is in contact with the end surface of the second insulating sleeve and the supporting portion of the second insulating sleeve is in contact with the end surface of the first insulating sleeve, whereby the first and second The rotor of the electric motor according to claim 3, wherein the insulating sleeve is axially positioned.   4. The electric motor rotor according to claim 3, wherein the first insulating sleeve and the second insulating sleeve are integrally connected by a connecting portion extending in the axial direction.   3. The electric motor rotor according to claim 1, wherein the insulating sleeve is provided with one or a plurality of slits extending in the axial direction as the cavity. 4.   The insulating sleeve has a substantially cylindrical shape, and a plurality of slits extending in the axial direction are provided on a side surface of the insulating sleeve, and the plurality of slits extend in an axial direction from one end surface of the insulating sleeve. The rotor for an electric motor according to claim 7, wherein the insulating sleeve and the one extending in the axial direction from the other end surface of the insulating sleeve are alternately arranged in the circumferential direction.   The rotor of an electric motor according to claim 1, wherein the insulating sleeve is formed integrally with the resin portion.   10. The electric motor rotor according to claim 1, wherein the insulating sleeve is made of BMC (bulk molding compound) resin, which is a thermosetting resin.   The rotor of an electric motor according to any one of claims 1 to 10, wherein the shaft is knurled on at least a part of a portion where the insulating sleeve is disposed.   The motor rotor according to claim 1, wherein a center hole is provided in at least one end surface of the shaft.   An electric motor using the rotor of the electric motor according to any one of claims 1 to 12. A stator in which a coil is formed by winding a plurality of teeth of a stator core provided with an insulating portion;
A board that is assembled to the stator, on which electronic components are mounted and lead wire lead-out components that lead out lead wires are attached;
A mold stator formed by molding the stator and the substrate with a thermosetting resin;
A bracket that is fitted into an opening of the mold stator and supports one of the rolling bearings;
The electric motor according to claim 13, comprising:   An air conditioner using the electric motor according to claim 13 or 14 as an electric motor for a blower. In the method of manufacturing a rotor of an electric motor, in which a magnet and a shaft of a rotor are integrally formed with a resin portion, and a pair of rolling bearings are attached to the shaft,
Forming the rotor magnet, processing the shaft, and forming an insulating sleeve;
Assembling the insulating sleeve to the shaft such that the insulating sleeve and the cavity are provided between at least one of the pair of rolling bearings and the shaft;
Producing a rotor by integrally molding the shaft on which at least the magnet of the rotor and the insulating sleeve are assembled with a thermoplastic resin; and
Assembling the pair of rolling bearings on the shaft;
The manufacturing method of the rotor of the electric motor characterized by the above-mentioned.

Images