Electric motor, electrical equipment equipped with an electric motor, and method for manufacturing an electric motor.

Abstract

This disclosure aims to suppress the occurrence of electrolytic corrosion in bearings of electric motors. [Solution] The electric motor according to the present disclosure is provided with a first resin ring in contact with a first bearing and located on the rotor side of the first bearing in the longitudinal direction of the shaft, a first locking member in contact with the first resin ring and located on the rotor side of the first resin ring, a second resin ring in contact with a second bearing and located on the rotor side of the second bearing in the longitudinal direction of the shaft, and a second locking member in contact with the second resin ring and located on the rotor side of the second resin ring.

Description

Technical Field

[0001] The present disclosure relates to an electric motor improved to suppress the occurrence of electric corrosion of a bearing, an electric device including the electric motor, and a method for manufacturing the electric motor.

Background Art

[0002] In recent years, brushless motors often adopt a method of being driven by an inverter of a Pulse Width Modulation (hereinafter, appropriately referred to as PWM method) method. In the case of driving by such a PWM method inverter, the neutral point potential of the stator winding fluctuates due to the switching of the power element. This fluctuation of the neutral point potential is divided between the outer ring side of the bearing and the inner ring side of the bearing according to the capacitance distribution of the electric motor.

[0003] Since the capacitance distribution on the stator side on the outer ring side of the bearing including the stator winding is different from the capacitance distribution on the rotor side of the capacitance on the inner ring side of the bearing including the stator winding, a potential difference (hereinafter, referred to as shaft voltage) occurs between the outer ring of the bearing and the inner ring of the bearing. The shaft voltage includes a high-frequency component due to switching. When this shaft voltage reaches the breakdown voltage of the grease oil film inside the bearing, a minute current flows inside the bearing due to the breakdown of the grease oil film, causing roughness on the metal surface inside the bearing and resulting in electric corrosion (see, for example, Patent Document 1 and Non-Patent Document 1). In addition, when the electric corrosion progresses, a wavy wear phenomenon may occur on the inner ring of the bearing, the outer ring of the bearing, or the ball of the bearing, leading to abnormal noise, which is one of the main causes of problems in electric motors.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005] [Non-Patent Document 1] "Shaft Voltage Suppression Based on Ungrounded Common-Mode Equivalent Circuit of Inverter-Driven Brushless DC Motor," Transactions of the Institute of Electrical Engineers of Japan, 2012, Vol.132, No.6, pp.666-672. [Overview of the project] [Problems that the invention aims to solve]

[0006] This disclosure provides an electric motor improved to suppress the occurrence of galvanic corrosion of bearings, an electrical device equipped with the electric motor, and a method for manufacturing the electric motor. [Means for solving the problem]

[0007] An electric motor relating to one aspect of this disclosure is A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, In the longitudinal direction of the shaft, a first resin ring is in contact with the first bearing and is located on the rotor side of the first bearing, A first locking member that contacts the first resin ring and is located on the rotor side of the first resin ring, In the longitudinal direction of the shaft, a second resin ring is in contact with the second bearing and is located on the rotor side of the second bearing, A second locking member is provided, which contacts the second resin ring and is located on the rotor side of the second resin ring.

[0008] An electric motor relating to another aspect of this disclosure is: A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, A first insulator is provided between the shaft and the first bearing, in contact with the first bearing, and a first groove having a vector component in the longitudinal direction of the shaft is provided on the inside of the first insulator. A third insulator is provided between the shaft and the second bearing, in contact with the second bearing, and a second groove having a vector component in the longitudinal direction of the shaft is provided on the inside of the third insulator.

[0009] An electric motor relating to yet another aspect of this disclosure is: A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, Between the shaft and the first bearing, a first insulator that contacts the first bearing and a third insulator are provided inside the first insulator. Between the shaft and the second bearing, a second insulator is provided that contacts the second bearing, and a fourth insulator is provided inside the second insulator. In the longitudinal direction of the shaft, the length of the first insulator is longer than that of the first bearing, and the length of the third insulator is shorter than that of the first insulator. In the longitudinal direction of the shaft, the length of the second insulator is longer than that of the second bearing, and the length of the fourth insulator is shorter than that of the second insulator.

[0010] A method for manufacturing an electric motor according to one aspect of this disclosure is: A method for manufacturing an electric motor, The aforementioned electric motor is, A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, It comprises a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, A first insulator is provided between the shaft and the first bearing, which contacts the first bearing and has a width wider than the width of the first bearing. A second insulator is provided between the shaft and the second bearing, which contacts the second bearing and has a width wider than the width of the second bearing. (i) Prepare an upper mold having a first gate and a second gate, and a lower mold positioned opposite the upper mold, (ii) The upper mold and the lower mold sandwich the shaft, (iii) A first resin for forming the first insulator is poured through the first gate, and a second resin for forming the second insulator is poured through the second gate, (iv) The first resin and the second resin are fired to form the first insulator and the second insulator. [Effects of the Invention]

[0011] An electric motor and an electrical device equipped with an electric motor according to one aspect of the present disclosure can suppress the occurrence of electrolytic corrosion in the bearings of the electric motor. Furthermore, a method for manufacturing an electric motor according to one aspect of this disclosure can provide an electric motor that can suppress the occurrence of electrolytic corrosion in the bearings of the electric motor. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is an external view of the electric motor in Embodiment 1. [Figure 2] Figure 2 is a schematic cross-sectional view of the electric motor in Embodiment 1. [Figure 3] Figure 3 is a schematic perspective view of the rotor in Embodiment 1. [Figure 4] Figure 4 is a schematic exploded perspective view of the rotor in Embodiment 1. [Figure 5] Figure 5 is a schematic cross-sectional view of the area around the shaft of Embodiment 1. [Figure 6A] Figure 6A is a schematic diagram of the area around the shaft in Embodiment 2. [Figure 6B] Figure 6B is a schematic diagram of the area around another shaft in Embodiment 2. [Figure 7] Figure 7 is a schematic cross-sectional view of the area around the shaft of Embodiment 3. [Figure 8] Figure 8 is a schematic cross-sectional view of the periphery of another shaft in Embodiment 3. [Figure 9A] Figure 9A is a schematic diagram illustrating the method for manufacturing the first insulator and the second insulator according to Embodiment 2. [Figure 9B] Figure 9B is a schematic diagram illustrating another method for manufacturing the first and second insulators of Embodiment 2. [Figure 10] Figure 10 is a schematic cross-sectional view of the electric motor of Embodiment 1. [Figure 11] Figure 11 is a diagram of the capacitance distribution model of the electric motor in Embodiment 1. [Figure 12] Figure 12 is a schematic cross-sectional view of the electric motor of Embodiment 4. [Figure 13] Figure 13 is a diagram of the capacitance distribution model of the motor in Embodiment 4. [Figure 14] Figure 14 is a schematic diagram of the electrical equipment according to Embodiment 5. [Figure 15] Figure 15 is a schematic diagram of the cross-sectional configuration of a conventional electric motor. [Figure 16] Figure 16 is a diagram of a conventional model of the capacitance distribution of an electric motor. [Modes for carrying out the invention]

[0013] (Knowledge that forms the basis of this disclosure) Before describing embodiments of this disclosure, we will explain the knowledge that forms the basis of this disclosure. Conventionally, the following documents describe measures to suppress galvanic corrosion of bearings by reducing the shaft voltage, thereby keeping the grease film inside the bearing below its dielectric breakdown voltage and preventing dielectric breakdown of the grease film. Furthermore, Patent Document 1 describes measures to reduce the discharge energy caused by dielectric breakdown of the grease film inside the bearing by reducing the shaft voltage, thereby reducing damage to the metal surface inside the bearing.

[0014] The following provides a detailed explanation of Patent Document 1. Figure 15 is a schematic cross-sectional view of the inner rotor type brushless radial type electric motor 50 described in Patent Document 1. Patent Document 1 and Non-Patent Document 1 have the same configuration. As shown in Figure 15, the electric motor 50 includes a first metal bracket 1 and a second metal bracket 2 positioned at both ends of the electric motor 50, a pair of bearings (first bearing 5a and second bearing 5b), a shaft 4, a rotor 10, and a stator 18. The rotating body 9 has a rotor core 8 and a permanent magnet 11. The rotor 10 has a rotating body 9 and a shaft 4. The stator 18 has a stator core 6 and stator windings 3.

[0015] As shown in Figure 15, the outer ring of the first bearing 5a is connected to the first metal bracket 1, and the outer ring of the second bearing 5b is connected to the second metal bracket 2. The inner rings of the first bearing 5a and the second bearing 5b are connected by a shaft 4 and are electrically conductive. The conductive member 13 electrically short-circuits the first metal bracket 1 and the second metal bracket 2.

[0016] Patent Document 1 electrically short-circuits the first metal bracket 1 and the second metal bracket 2 with a conductive member 13, thereby matching the capacitances of the first metal bracket 1 and the second metal bracket 2. Furthermore, Patent Document 1 describes a method of reducing the shaft voltage by providing a dielectric layer 20 on the rotating body 9 and changing the capacitance of the rotating body 9.

[0017] Figure 16 is a model diagram of the capacitance distribution of the electric motor 50 described in Patent Document 1. In the electric motor 50 of Patent Document 1, when considering the capacitance distribution with respect to the stator core 6, the voltage distribution of the electric motor 50 is predominantly influenced by capacitive reactance, which is the reciprocal of the impedance. Therefore, as shown in Figure 5 of Non-Patent Document 1, the capacitance distribution model is used for explanation. Capacitance C between the stator winding 3 and the first metal bracket 1 sb1 This is because the charge in the first bearing 5a is accumulated, and the first shaft voltage V sh1 This schematically represents the increase in the first axis voltage V. sh1 When the voltage rises and reaches the dielectric breakdown voltage of the grease film inside the bearing, dielectric breakdown occurs. Capacitance C between the stator winding 3 and the second metal bracket 2 sb2 Capacitance C sb1 Similarly, charge accumulates in the second bearing 5b, and the second shaft voltage V sh2 This schematically represents the increase in the second axis voltage V. sh2 When the voltage rises, dielectric breakdown occurs.

[0018] The voltage generated between the outer ring side of the first bearing 5a (location 1 in Figure 16) and the zero potential reference N(12) of the drive circuit is the voltage V generated between the zero reference potential N(12) of the drive circuit and the neutral point potential S of the stator winding 3. comIt becomes a value divided by the capacitance distribution on the stator side. Also, the voltage generated between the outer ring side of the second bearing 5b (at position 2 in FIG. 16) and the zero potential reference N (12) of the drive circuit is the voltage V generated between the zero reference potential N (12) of the drive circuit and the neutral point potential S of the stator winding 3. com It becomes a value divided by the capacitance distribution on the stator side. The voltage generated between the inner ring side of the first bearing 5a and the inner ring side of the second bearing 5b (at position 4 in FIG. 16) and the zero potential reference N (12) of the drive circuit is the voltage V generated between the zero potential reference N (12) of the drive circuit and the neutral point potential S of the stator winding 3. com It becomes a value divided by the capacitance distribution on the rotor side.

[0019] By considering the capacitance distribution in FIG. 16, the present inventors found the following findings. The first shaft voltage V sh1 and the second shaft voltage V sh2 are the difference between the voltages generated on the outer ring side and the inner ring side of the first bearing 5a and the second bearing 5b. Therefore, it was found that in order to reduce the first shaft voltage V sh1 and the second shaft voltage V sh2 , it is necessary to make the capacitance distribution on the stator side and the capacitance distribution on the rotor side coincide or approximate.

[0020] The voltage generated between the outer ring side of the first bearing 5a and the outer ring side of the second bearing 5b and the zero potential reference N (12) of the drive circuit is the capacitance C between the zero reference potential N (12) of the drive circuit and the first metal bracket 1 nb1 and the capacitance C between the stator winding 3 and the first metal bracket 1 sb1 and the capacitance C between the stator winding 3 and the second metal bracket 2 sb2 and the voltage division ratio A2 (C nb1 / combined capacitance A2) of the combined capacitance A2. Also, the voltage generated between the inner ring side of the first bearing 5a and the inner ring side of the second bearing 5b and the zero potential reference N (12) of the drive circuit is the capacitance C between the zero reference potential N (12) of the drive circuit and the shaft 4 ns and the capacitance C between the stator winding 3 and the stator core 6i , capacitance C between the stator core 6 and the magnet 11 g , capacitance C between the stator winding 3 and the magnet 11 sm and the capacitance C of magnet 11 mg The voltage division ratio B2(C) of the equivalent capacitance B2 ns The equivalent capacitance will be B2.

[0021] As a result of diligent consideration, the inventors of the present invention have determined that the first axis voltage V sh1 and the second axis voltage V sh2 To reduce this pressure division ratio A2(C nb1 / Equivalent capacitance A2) and voltage division ratio B2(C ns We found that the equivalent capacitance B2 and the voltage division ratio A2 can be made to match or approximate each other. This matching or approximation of the voltage division ratio A2 and the voltage division ratio B2 will be referred to simply as "matching" below. In Patent Document 1, capacitance C nb1 , C sb2 , C ns Since it is smaller than the equivalent capacitance B2, it was found that the method used to match the capacitances is to reduce the capacitance of the equivalent capacitance B2.

[0022] As shown in Figure 15, Patent Document 1 provides a dielectric layer 20 on the rotating body 9, and capacitance C d It forms the capacitance C of this dielectric. d In the capacitance distribution model diagram of Figure 16, the capacitance C of the magnet is shown. mg A capacitance C is connected in series with it. d This means that the capacitor has been inserted, and by reducing the equivalent capacitance B2, the capacitance distribution on the stator side is matched, and the first axis voltage V sh1 and the second axis voltage V sh2 It was found to be a way to reduce [the problem].

[0023] Capacitance C of dielectric layer 20 d The capacitance C is inversely proportional to the width (the distance in the shorter direction of the dielectric layer 20 in Figure 15), which is the distance in the thickness direction of the dielectric layer 20, and proportional to the length (the distance in the longer direction of the dielectric layer 20 in Figure 15). Therefore, the capacitance C dTo lower the value, the width of the dielectric layer 20 needs to be increased.

[0024] However, as shown in Figure 15, Patent Document 1 states that the dielectric layer 20 is subjected to stress as rotational torque, and therefore the width of the dielectric layer 20 may be restricted in order to ensure its strength. In that case, it was considered that the required capacitance could not be obtained and the shaft voltage could not be reduced. Furthermore, Patent Document 1 states that in an electric motor 50 using a rotating body 9 that holds multiple permanent magnets 11 in a spoke-like manner from the center in the radial direction, widening the width of the dielectric layer 20 necessitates shortening the length of the permanent magnets 11, which leads to a problem of deterioration in the performance of the electric motor 50.

[0025] The inventors of this invention identified the above-mentioned problems and diligently conducted research to solve them, leading to the following disclosure. Figure 2 is a schematic cross-sectional view of the electric motor 50 of this disclosure. As shown in Figure 2, the electric motor 50 has a first metal bracket 1 and a second metal bracket 2 positioned at both ends, a first bearing 5a and a second bearing 5b, a shaft 4, a rotor 10, and a stator 18. The rotating body 9 has a rotor core 8 and a magnet 11 which is a permanent magnet. The rotor 10 has a rotating body 9 and a shaft 4. The electric motor 50 has a resin housing 35 which holds a first metal bracket 1 and a second metal bracket 2. The stator 18 has a stator core 6 and stator windings 3.

[0026] In the electric motor 50, a first conductive member 31 is arranged inside the housing 35, the first conductive member 31 is electrically connected to the first metal bracket 1, and the first conductive member 31 is electrically connected to the second metal bracket 2. In other words, the first metal bracket 1 and the second metal bracket 2 are short-circuited, and the first metal bracket 1 and the second metal bracket 2 are at the same potential.

[0027] The electric motor 50 has a first resin ring 45a that contacts the first bearing 5a in the longitudinal direction of the shaft 4 and is located on the rotor 10 side of the first bearing 5a, and a first locking member 46a (here, an E-ring) that contacts the first resin ring 45a and is located on the rotor 10 side of the first resin ring 45a.

[0028] The electric motor 50 has a second resin ring 45b that contacts the second bearing 5b in the longitudinal direction of the shaft 4 and is located on the rotor 10 side of the second bearing 5b, and a second locking member 46b (here, an E-ring) that contacts the second resin ring 45b and is located on the rotor 10 side of the second resin ring 45b.

[0029] According to the above embodiment, the first resin ring 45a insulates the outer ring of the first bearing 5a from the shaft 4 without short-circuiting, and the second resin ring 45b insulates the outer ring of the second bearing 5b from the shaft 4 without short-circuiting.

[0030] More specific embodiments of the present disclosure are described below. However, some unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of already well-known matters or redundant descriptions of substantially identical components may be omitted. This is to avoid the following description becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The inventors provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and not to limit the subject matter described in the claims. In the following description, identical or similar components are denoted by the same reference numerals.

[0031] (Embodiment 1) Hereinafter, an electric motor 50 representing one aspect of this disclosure will be described with reference to the drawings. After describing the overall structure of the electric motor 50, each component will be explained. Here, we define the side of shaft 4 closer to the axis of rotation 90 as the inside, and the side further away from the axis of rotation as the outside.

[0032] Figure 1 is an external view of an inner rotor type brushless radial type electric motor 50, which shows one aspect of the present disclosure. The electric motor 50 includes a cover member 21, a housing 35, and a shaft 4. The cover member 21 includes a first metal bracket 1, and the housing 35 includes a second metal bracket 2. Figure 2 is a schematic cross-sectional view of an inner rotor type brushless radial type electric motor 50, which represents one aspect of the present disclosure.

[0033] As shown in Figure 2, a first conductive metal bracket 1 and a second conductive metal bracket 2 are positioned at both ends of the electric motor 50. The outer diameter of the first metal bracket 1 is the same as or larger than the outer diameter of the second metal bracket 2. This ensures that the bearing is stably supported and the shaft 4 can rotate. A first bearing 5a, fixed to the first metal bracket 1, is positioned in the center of the first metal bracket 1, and a second bearing 5b, fixed to the second metal bracket 2, is positioned in the center of the second metal bracket 2. The shaft 4 is supported and rotated by the first bearing 5a and the second bearing 5b. The shaft 4 protrudes from the first metal bracket 1.

[0034] The stator 18 generates a rotating magnetic field, which rotates the rotor 10. The rotor 10 is inserted inside the stator 18 with an air gap between it and the stator 18. The stator 18 has a stator core 6 and a stator winding 3, which is a winding. The stator winding 3 is wound around the stator core 6 with a resin 7 interposed to insulate the stator core 6. The first metal bracket 1 and the second metal bracket 2 may also be insulated from the stator core 6 by a space.

[0035] The rotor 10 rotates in the electric motor 50 and has a shaft 4 and a rotating body 9. The rotating body 9 has a rotor core 8 and permanent magnets 11 which are ferrite magnets. The rotor 10 holds a plurality of magnets 11 on the outer circumference of the rotor core 8 and has a shaft 4 that passes through the center of the rotor core 8. Alternatively, the rotor 10 may hold a plurality of magnets 11 in a spoke-like manner from the center, facing the stator 18.

[0036] The shaft 4 is fitted with a first bearing 5a and a second bearing 5b that support the shaft 4. The first bearing 5a and the second bearing 5b are cylindrical bearings having multiple iron balls, and the inner rings of the first bearing 5a and the second bearing 5b are fixed to the shaft 4. As a result, the inner rings of the first bearing 5a and the second bearing 5b are electrically connected to the shaft 4.

[0037] In the first bearing 5a and the second bearing 5b, the outer ring side of the first bearing 5a and the outer ring side of the second bearing 5b are fixed by a first metal bracket 1 and a second metal bracket 2, respectively, which are electrically conductive. In Figure 2, the first bearing 5a is fixed to the first metal bracket 1, and the second bearing 5b is fixed to the second metal bracket 2, so that the shaft 4 is supported by the two bearings and the rotor 10 rotates freely.

[0038] Furthermore, a printed circuit board 12, which has a drive circuit for generating a rotating magnetic field mounted inside the electric motor 50, is positioned between the rotor 10 and the first metal bracket 1. For example, the drive circuit includes an inverter circuit and the like to apply voltage to the stator winding 3.

[0039] With the electric motor 50 configured as described above, applying voltage from the drive circuit to the stator winding 3 causes current to flow through the stator winding 3, generating a magnetic field from the stator core 6. Then, the rotating magnetic field from the stator core 6 and the magnetic field from the magnet 11 generate attractive and repulsive forces depending on the polarity of these magnetic fields, and these forces cause the rotor 10 to rotate around the shaft 4.

[0040] Next, we will explain each component. Figure 3 is a schematic perspective view of the rotor 10 in Embodiment 1, Figure 4 is a schematic exploded perspective view of the rotor 10 in Embodiment 1, and Figure 5 is a schematic cross-sectional view of the area around the shaft 4 in Embodiment 1.

[0041] As shown in Figure 3-5, the shaft 4 is provided with the following components in this order: a first bearing 5a, a first resin ring 45a, a first locking member 46a (here, an E-ring), a rotating body 9, a second locking member 46b (here, an E-ring), a second resin ring 45b, and a second bearing 5b. (First insulator and second insulator) As shown in Figure 5, the shaft 4 is provided with a first insulator 41a and a second insulator 41b. The first insulator 41a and the second insulator 41b electrically insulate the shaft 4 from the inner ring of the first bearing 5a, and the shaft 4 from the inner ring of the second bearing 5b. The first insulator 41a and the second insulator 41b are preferably made of resin formed by molding.

[0042] The shaft 4 is provided with a first groove 36a for the first insulator 41a and a second groove 36b for the second insulator 41b. As will be explained in more detail later, the first insulator 41a is embedded in the first groove 36a, and the second insulator 41b is embedded in the second groove 36b.

[0043] The outer surface of the first insulator 41a is in contact with the inner ring of the first bearing 5a. In the longitudinal direction of the shaft 4, the length of the first insulator 41a is longer than the length of the first bearing 5a. The outer surface of the second insulator 41b is in contact with the inner ring of the second bearing 5b. In the longitudinal direction of the shaft 4, the length of the second insulator 41b is longer than the length of the second bearing 5b.

[0044] (Resin ring) The electric motor 50 has a first resin ring 45a that contacts the first bearing 5a in the longitudinal direction of the shaft 4 and is located on the rotor 10 side (right side of the paper) of the first bearing 5a. The electric motor 50 has a second resin ring 45b that contacts the second bearing 5b in the longitudinal direction of the shaft 4 and is located on the rotor 10 side (left side of the paper) of the second bearing 5b. The first resin ring 45a and the second resin ring 45b are insulators.

[0045] (First locking member and second locking member) The electric motor 50 has a first locking member 46a (in this case, an E-ring) that is in contact with the first resin ring 45a and is located on the rotor 10 side (right side of the paper) of the first resin ring 45a. The first locking member 46a prevents the first bearing 5a and the first resin ring 45a from moving toward the rotor 10 (right side of the paper). Since the first locking member 46a is not in contact with the first bearing 5a, it is not electrically connected. Furthermore, the first locking member 46a is not limited to an E-ring, as long as it prevents the first bearing 5a and the first resin ring 45a from moving toward the rotor 10 side (right side of the paper).

[0046] The electric motor 50 has a second locking member 46b (in this case, an E-ring) that is in contact with the second resin ring 45b and is located on the rotor 10 side (left side of the paper) of the second resin ring 45b. The second locking member 46b prevents the second bearing 5b and the second resin ring 45b from moving toward the rotor 10 (left side of the paper). Since the second locking member 46b is not in contact with the second bearing 5b, it is not electrically connected. Furthermore, the second locking member 46b is not limited to an E-ring, as long as it prevents the second bearing 5b and the second resin ring 45b from moving toward the rotor 10 side (left side of the paper).

[0047] According to the above embodiment, the first resin ring 45a insulates the outer ring of the first bearing 5a from the shaft 4 without short-circuiting, and the second resin ring 45b insulates the outer ring of the second bearing 5b from the shaft 4 without short-circuiting.

[0048] Figure 10 is a schematic cross-sectional view of the motor 50 of Embodiment 1, and Figure 11 is a model diagram of the capacitance distribution of the motor 50 of Embodiment 1. As shown in Figures 10 and 11, the capacitance C between the stator winding 3 and the first metal bracket 1. sb1 And the capacitance C between the stator winding 3 and the second metal bracket 2. sb2 This forms a parallel circuit, resulting in a parallel equivalent capacitance A1 (hereinafter referred to as equivalent capacitance A1). Capacitance C between the stator winding 3 and the stator core 6 i And the capacitance C between the stator core 6 and the magnet 11 g And the capacitance C between the stator winding 3 and the magnet 11. sm And the capacitance C of magnet 11 mg This refers to a circuit configuration consisting of components in series and / or parallel, resulting in a combined series-parallel capacitance B1 (hereinafter referred to as combined capacitance B1).

[0049] Capacitance C between the stator winding 3 and the first metal bracket 1 sb1 Charge accumulates in the first bearing 5a, and the first shaft voltage V sh1 (Capacitance C between the outer and inner rings of the first bearing 5a) b1 This schematically represents the increase in the voltage of the first axis. sh1 When the voltage rises and reaches the dielectric breakdown voltage of the grease film inside the bearing, dielectric breakdown occurs. Furthermore, the capacitance C of the first insulator d1 However, capacitance C b1 It is connected in series with the other.

[0050] Capacitance C between the stator winding 3 and the second metal bracket 2 sb2 Capacitance C sb1 Similarly, charge accumulates in the second bearing 5b, and the second shaft voltage V sh2(Capacitance C between the outer and inner rings of the second bearing 5b) b2 This schematically represents the increase in the voltage of the second axis. sh2 When the voltage rises, dielectric breakdown occurs. Furthermore, the capacitance C of the second insulator d2 However, capacitance C b2 It is connected in series with the other.

[0051] In order to approximate the capacitance distribution on the stator 18 side with the capacitance distribution on the rotor 10 side, the inner and outer rings of the first bearing 5a and the second bearing 5b are used as references, and the capacitance C between the zero reference potential N(12) of the drive circuit and the first metal bracket 1 is used. nb1 The ratio of the equivalent capacitance A1 (C nb1 (Equivalent capacitance A1) and capacitance C between the zero reference potential N(12) of the drive circuit and shaft 4. ns The ratio of the equivalent capacitance B1 (C ns The capacitance C of the first insulator is approximated to the equivalent capacitance B1). d1 and the capacitance C of the second insulator d2 We are making adjustments.

[0052] Thus, without using the dielectric layer 20 of Patent Document 1, the ratio of the equivalent capacitance A1 (C nb1 The ratio of the equivalent capacitance A1 to the equivalent capacitance B1 (C ns The equivalent capacitance (B1) can be approximated. Approximation means that the above ratio is in the range of 0.7 to 1.3, preferably in the range of 0.8 to 1.2.

[0053] In Embodiment 1, the first insulator 41a and the second insulator 41b are provided on the shaft 4, but the first insulator 41a and the second insulator 41b may not be provided on the shaft 4.

[0054] (Embodiment 2) Embodiment 2 is a configuration in which a first groove 36a and a second groove 36b are arranged on the shaft 4. Figure 6A is a schematic diagram of the area around the shaft 4 of Embodiment 2. The upper part of Figure 6A is a schematic cross-sectional view of the area around the shaft 4, and the lower part of Figure 6A is a perspective view of the area around the first groove 36a and the second groove 36b.

[0055] As shown in Figure 6A, the first groove 36a is placed inside the first insulator 41a, and the second groove 36b is placed inside the second insulator 41b. The first groove 36a and the second groove 36b are grooves (recesses) parallel to the direction of rotation of the shaft 4.

[0056] In Figure 6A, the vectors 61 of the first groove 36a and the second groove 36b are represented by thick lines. Here, the longitudinal direction of shaft 4 is defined as the X vector, and the direction perpendicular to the longitudinal direction of shaft 4 (the vertical direction of the paper) in any cross-section including the axis of rotation 90 is defined as the Y vector.

[0057] (The central figure in Figure 6B) Since the vectors 61 of the first groove 36a and the second groove 36b are parallel to the axis of rotation 90, they consist only of the X vector and there is no Y vector. Therefore, the vectors 61 of the first groove 36a and the second groove 36b have an X-vector component in the longitudinal direction of the shaft 4.

[0058] According to the above embodiment, when the shaft 4 rotates, the first groove 36a and the second groove 36b have an X-vector component, so it is possible to prevent the first insulator 41a and the second insulator 41b from shifting position in the rotational direction of the shaft 4, or from peeling off the first insulator 41a and the second insulator 41b in the rotational direction of the shaft 4.

[0059] Figure 6B is a schematic diagram of the periphery of another shaft 4 in Embodiment 2, the upper part of Figure 6B is a schematic cross-sectional view of the periphery of shaft 4, and the lower part of Figure 6B is a perspective view of the periphery of the third groove 37a and the fourth groove 37b. The difference between Figure 6B and Figure 6A is that the third groove 37a and the fourth groove 37b of the shaft 4 are inclined with respect to the rotation axis 90 of the shaft 4 in any cross-section including the rotation axis 90 of the shaft 4.

[0060] In Figure 6B, the vectors 62 of the first groove 36a and the second groove 36b are shown as thick lines. Therefore, the vectors 62 of the third groove 37a and the fourth groove 37b have both X and Y vector components, and the vectors of the third groove 37a and the fourth groove 37b have an X vector component in the longitudinal direction of the shaft 4 (center diagram in Figure 6B).

[0061] According to the above embodiment, when the shaft 4 rotates, the third groove 37a and the fourth groove 37b have an X-vector component, which prevents the first insulator 41a and the second insulator 41b from shifting position in the rotational direction of the shaft 4, or from peeling off in the rotational direction of the shaft 4.

[0062] Furthermore, since the third groove 37a and the fourth groove 37b have a Y-vector component, it is possible to prevent the first insulator 41a and the second insulator 41b from shifting position in the rotational direction of the shaft 4, or from peeling off the first insulator 41a and the second insulator 41b in the rotational direction of the shaft 4.

[0063] (Manufacturing method) Figure 9A is a schematic diagram illustrating the method for manufacturing the first insulator 41a and the second insulator 41b according to Embodiment 2.

[0064] (S1) The shaft 4 is provided with a first groove 36a and a second groove 36b.

[0065] (S2) An upper mold 51 having a first gate 53 and a second gate 54, and a lower mold 52 positioned opposite the upper mold 51 are prepared. The first gate 53 is a groove that penetrates from the upper surface of the upper mold 51 to the lower surface of the upper mold 51. The second gate 54 is a groove that penetrates from the upper surface of the upper mold 51 to the lower surface of the upper mold 51.

[0066] The shaft 4 is sandwiched between the upper mold 51 and the lower mold 52.

[0067] The first resin 47a is poured through the first gate 53 to form the first insulator 41a. The second resin 47b is poured through the second gate 54 to form the second insulator 41b. Furthermore, at this time, assuming the position where the first insulator 41a will be attached to the shaft 4 after molding, it is preferable to pour the first resin 47a for molding the first insulator 41a from the first gate 53 which is located outside the width range of the first bearing 5a (see Figure 9B). It is preferable to pour the second resin 47b for molding the second insulator 41b from the second gate 54, which is located outside the width range of the second bearing 5b, assuming that the second insulator 41b will be attached to the shaft 4 after molding (see Figure 9B).

[0068] The first resin 47a and the second resin 47b are fired to form the first insulator 41a and the second insulator 41b.

[0069] Finally, the upper mold 51 and the lower mold 52 are separated from the shaft 4. In this way, the first insulator 41a and the second insulator 41b are formed on the shaft 4. Furthermore, the diameter of the first insulator 41a and the diameter of the shaft 4 outside the longitudinal range of the first groove 36a and the second groove 36b are the same length, or approximately the same length.

[0070] Figure 9B is a schematic diagram illustrating another method for manufacturing the first insulator 41a and the second insulator 41b of Embodiment 2.

[0071] (S1) The shaft 4 is provided with a first groove 36a and a second groove 36b. The first bearing 5a is positioned near the first groove 36a, and the second bearing 5b is positioned near the second groove 36b.

[0072] (S2) An upper mold 51 having a first gate 53 and a second gate 54, and a lower mold 52 positioned opposite the upper mold 51 are prepared. The first gate 53 is a groove that penetrates from the upper surface of the upper mold 51 to the lower surface of the upper mold 51. The second gate 54 is a groove that penetrates from the upper surface of the upper mold 51 to the lower surface of the upper mold 51.

[0073] The upper mold 51 is provided with a first bearing groove 55a and a second bearing groove 55b spaced apart from the first bearing groove 55a in the longitudinal direction of the shaft 4. The lower mold 52 is provided with a first bearing groove 55a and a second bearing groove 55b spaced apart from the first bearing groove 55a in the longitudinal direction of the shaft 4.

[0074] The shaft 4 is sandwiched between the upper mold 51 and the lower mold 52 such that the first bearing groove 55a fits into the first bearing groove 55a and the second bearing groove 55b fits into the second bearing groove 55b. At this time, the first bearing 5a is positioned within the width range of the first insulator 41a, and the second bearing 5b is positioned within the width range of the second insulator 41b.

[0075] A first resin 47a is poured in from a first gate 53 located outside the width range of the first bearing 5a to form the first insulator 41a. The second resin 47b is poured in from the second gate 54, which is positioned outside the width range of the second bearing 5b, to form the second insulator 41b.

[0076] The first resin 47a and the second resin 47b are fired to form the first insulator 41a and the second insulator 41b.

[0077] Finally, the upper mold 51 and the lower mold 52 are separated from the shaft 4. In this way, the first insulator 41a and the second insulator 41b are formed on the shaft 4. Furthermore, the diameter of the first insulator 41a and the diameter of the shaft 4 outside the longitudinal range of the first groove 36a and the second groove 36b are the same length, or approximately the same length.

[0078] (Embodiment 3) Embodiment 3 is a configuration in which the first insulator 41a and / or the second insulator 41b consists of two layers. Figure 7 is a schematic cross-sectional view of the area around the shaft 4 of Embodiment 3. As shown in Figure 7, a first insulator 41a that contacts the first bearing 5a and a third insulator 42a are provided between the shaft 4 and the first bearing 5a, with the second insulator 42a located inside the first insulator 41a. Between the shaft 4 and the second bearing 5b, a second insulator 41b is provided that contacts the second bearing 5b, and a fourth insulator 42b is provided inside the second insulator 41b.

[0079] In the longitudinal direction of the shaft 4, the length of the first insulator 41a is longer than that of the first bearing 5a, and the length of the third insulator 42a is shorter than that of the first insulator 41a. In the longitudinal direction of the shaft 4, the length of the second insulator 41b is longer than that of the second bearing 5b, and the length of the fourth insulator 42b is shorter than that of the second insulator 41b.

[0080] The third insulator 42a and the fourth insulator 42b are rectangular in shape. By changing the thickness of the third insulator 42a, the capacitance of the third insulator 42a can be changed. Furthermore, by changing the thickness of the fourth insulator 42b, the capacitance of the fourth insulator 42b can be changed.

[0081] In this way, the ratio of the equivalent capacitance A1 (C nb1 The ratio of the equivalent capacitance A1 to the equivalent capacitance B1 (C ns The equivalent capacitance (B1) can be approximated.

[0082] Furthermore, the first insulator 41a and / or the second insulator 41b are not limited to two layers, but may consist of three or more layers.

[0083] Figure 8 is a schematic cross-sectional view of the periphery of another shaft 4 in Embodiment 3. As shown in Figure 8, a first insulator 41a that contacts the first bearing 5a and a fifth insulator 43a are provided between the shaft 4 and the first bearing 5a. Between the shaft 4 and the second bearing 5b, there is a second insulator 41b that contacts the second bearing 5b, and a sixth insulator 43b located inside the second insulator 41b.

[0084] The fifth insulator 43a and the sixth insulator 43b are arc-shaped. By changing the thickness of the fifth insulator 43a, the capacitance of the fifth insulator 43a can be changed. Furthermore, by changing the thickness of the sixth insulator 43b, the capacitance of the sixth insulator 43b can be changed.

[0085] In this way, the ratio of the equivalent capacitance A1 (C nb1 The ratio of the equivalent capacitance A1 to the equivalent capacitance B1 (C ns The equivalent capacitance (B1) can be approximated.

[0086] (Embodiment 4) Embodiment 4 is a configuration in which a dielectric layer 20 is provided on the rotating body 9 of the electric motor 50 of Embodiment 1. Figure 12 is a schematic cross-sectional view of the electric motor 50 of Embodiment 4, and Figure 13 is a model diagram of the capacitance distribution of the electric motor 50 of Embodiment 4.

[0087] As shown in Figures 12 and 13, the capacitance Cd of the dielectric layer 20, the capacitance Cd1 of the first insulator 41a, and the capacitance Cd2 of the second insulator 41b are changed to obtain the ratio (C) of the combined capacitance A1. nb1 The ratio of the equivalent capacitance A1 to the equivalent capacitance B1 (C ns This approximates the equivalent capacitance (B1).

[0088] (Embodiment 5) As an example of the electrical equipment covered by this disclosure, the configuration of an indoor unit of an air conditioner will be described in detail as Embodiment 5. The electrical equipment covered by this disclosure is not necessarily limited to these examples.

[0089] In Figure 14, a brushless motor 101 is provided inside the housing 111 of the indoor unit 110 of the air conditioner. A cross-flow fan 112, which is a blower fan, is attached to the rotating shaft 90 of the brushless motor 101. The brushless motor 101 is driven by a motor drive unit 113. When power is supplied from the motor drive unit 113, the brushless motor 101 rotates, and the cross-flow fan 112 rotates in conjunction with it. The rotation of the cross-flow fan 112 allows air-conditioned air (not shown) to be blown into the room by the indoor unit's heat exchanger. Here, for example, the electric motor 50 of Embodiment 1 described above can be used as the brushless motor 101.

[0090] The electrical equipment of this disclosure comprises a brushless motor and a housing on which the brushless motor is mounted, and employs the electric motor 50 of the above embodiment as the brushless motor.

[0091] In Figure 2 of Embodiment 1, the printed circuit board 12 with the drive circuit is located inside the electric motor 50, but the printed circuit board 12 with the drive circuit may also be located outside the electric motor 50. In that case, the electric motor 50 can be made more compact.

[0092] Furthermore, the inventions according to Embodiments 1 to 5 can be substituted or combined, as long as no contradictions arise.

[0093] As described above, this disclosure includes electric motors and electrical equipment equipped with such electric motors as described in the following items.

[0094] [Item 1] A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, In the longitudinal direction of the shaft, a first resin ring is in contact with the first bearing and is located on the rotor side of the first bearing, A first locking member that contacts the first resin ring and is located on the rotor side of the first resin ring, In the longitudinal direction of the shaft, a second resin ring is in contact with the second bearing and is located on the rotor side of the second bearing, An electric motor provided with a second locking member that contacts the second resin ring and is located on the rotor side of the second resin ring.

[0095] [Item 2] A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, A first insulator is provided between the shaft and the first bearing, in contact with the first bearing, and a first groove having a vector component in the longitudinal direction of the shaft is provided on the inside of the first insulator. An electric motor in which a second insulator is provided between the shaft and the second bearing, in contact with the second bearing, and a second groove having a vector component in the longitudinal direction of the shaft is provided on the inside of the second insulator.

[0096] [Item 3] The electric motor according to item 2, wherein the first groove and the second groove are grooves parallel to the direction of rotation of the shaft.

[0097] [Item 4] The electric motor according to item 2, wherein the first groove and the second groove are inclined with respect to the rotation axis of the shaft.

[0098] [Item 5] A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, Between the shaft and the first bearing, a first insulator that contacts the first bearing and a third insulator are provided inside the first insulator. Between the shaft and the second bearing, a second insulator is provided that contacts the second bearing, and a fourth insulator is provided inside the second insulator. In the longitudinal direction of the shaft, the length of the first insulator is longer than that of the first bearing, and the length of the third insulator is shorter than that of the first insulator. An electric motor in which, in the longitudinal direction of the shaft, the length of the second insulator is longer than that of the second bearing, and the length of the fourth insulator is shorter than that of the second insulator.

[0099] [Item 6] An electrical device equipped with an electric motor described in any of items 1 to 5 and a blower fan driven by the electric motor.

[0100] [Item 7] A method for manufacturing an electric motor, The aforementioned electric motor is, A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, It comprises a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, A first insulator is provided between the shaft and the first bearing, which contacts the first bearing and has a width wider than the width of the first bearing. A second insulator is provided between the shaft and the second bearing, which contacts the second bearing and has a width wider than the width of the second bearing. (i) Prepare an upper mold having a first gate and a second gate, and a lower mold positioned opposite the upper mold, (ii) The upper mold and the lower mold sandwich the shaft, (iii) A first resin for forming the first insulator is poured through the first gate, and a second resin for forming the second insulator is poured through the second gate, (iv) The first resin and the second resin are fired to form the first insulator and the second insulator. Method for manufacturing an electric motor.

[0101] [Item 8] (v) Prepare an upper mold having a first gate and a second gate, and a lower mold positioned opposite the upper mold, (vi) The upper mold and the lower mold sandwich the shaft, (vii) A first resin for forming the first insulator is poured through the first gate located outside the width range of the first bearing, and a second resin for forming the second insulator is poured through the second gate located outside the width range of the second bearing, (viii) A step of firing the first resin and the second resin to form the first insulator and the second insulator, The method for manufacturing the electric motor described in item 7. [Explanation of Symbols]

[0102] 1. First metal bracket 2. Second metal bracket 3 Stator winding 4 shafts 5a First bearing 5b Second bearing 6 Stator core 8 Rotor core 9. Solids of revolution 10 rotors 11 Magnets 18 Stator 36a First groove 36b Second groove 37a Third groove 37b The fourth groove 41a First insulator 41b Second insulator 42a Third insulator 42b Fourth insulator 43a Fifth insulator 43b The sixth insulator 45a First resin ring 45b Second resin ring 46a First locking member 46b Second locking member 47a First resin 47b Second resin 50 Electric motor 51 Upper mold 52 Lower mold 53 The First Gate 54 The second gate

Claims

1. A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, In the longitudinal direction of the shaft, a first resin ring is in contact with the first bearing and is located on the rotor side of the first bearing, A first locking member that contacts the first resin ring and is located on the rotor side of the first resin ring, In the longitudinal direction of the shaft, a second resin ring is in contact with the second bearing and is located on the rotor side of the second bearing, An electric motor provided with a second locking member that contacts the second resin ring and is located on the rotor side of the second resin ring.

2. A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, A first insulator is provided between the shaft and the first bearing, and a first groove having a vector component in the longitudinal direction of the shaft is provided on the inside of the first insulator. An electric motor in which a second insulator is provided between the shaft and the second bearing, and a second groove having a vector component in the longitudinal direction of the shaft is provided on the inside of the second insulator.

3. The electric motor according to claim 2, wherein the first groove and the second groove are grooves parallel to the rotation direction of the shaft.

4. The electric motor according to claim 2, wherein the first groove and the second groove are inclined with respect to the rotation axis of the shaft.

5. A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, An electric motor comprising a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, Between the shaft and the first bearing, a first insulator that contacts the first bearing and a third insulator are provided inside the first insulator. Between the shaft and the second bearing, a second insulator is provided that contacts the second bearing, and a fourth insulator is provided inside the second insulator. In the longitudinal direction of the shaft, the length of the first insulator is longer than that of the first bearing, and the length of the third insulator is shorter than that of the first insulator. An electric motor in which, in the longitudinal direction of the shaft, the length of the second insulator is longer than that of the second bearing, and the length of the fourth insulator is shorter than that of the second insulator.

6. An electrical device comprising an electric motor according to any one of claims 1 to 5 and a blower fan driven by the electric motor.

7. A method for manufacturing an electric motor, The aforementioned electric motor is, A stator including a stator core around which stator windings are wound, A rotor including a rotating body that holds a plurality of magnets in the circumferential direction opposite to the stator, or a rotating body that holds a plurality of magnets in a spoke-like manner from the center, and a shaft that passes through the center of the rotating body, The first bearing and the second bearing supporting the rotating body, It comprises a first metal bracket for fixing the first bearing and a second metal bracket for fixing the second bearing, A first insulator is provided between the shaft and the first bearing, which contacts the first bearing and has a width wider than the width of the first bearing. A second insulator is provided between the shaft and the second bearing, which contacts the second bearing and has a width wider than the width of the second bearing. (i) Prepare an upper mold having a first gate and a second gate, and a lower mold positioned opposite the upper mold. (ii) The upper mold and the lower mold sandwich the shaft, (iii) A first resin for forming the first insulator is poured through the first gate, and a second resin for forming the second insulator is poured through the second gate, (iv) The first resin and the second resin are fired to form the first insulator and the second insulator. Method for manufacturing an electric motor.

8. (v) Prepare an upper mold having a first gate and a second gate, and a lower mold positioned opposite the upper mold, (vi) The upper mold and the lower mold sandwich the shaft, (vii) A first resin for forming the first insulator is poured from the first gate located outside the width range of the first bearing, and a second resin for forming the second insulator is poured from the second gate located outside the width range of the second bearing, (viiii) A step of firing the first resin and the second resin to form the first insulator and the second insulator, A method for manufacturing an electric motor according to claim 7.

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