Rotary motor

Abstract

It comprises: a rotor (10) having a rotating shaft (12) and a rotor core (11); a stator (30) having a stator core (31) and a stator winding (32); a bearing (20); a frame (40) fixed to the stator core (31) and connected to the bearing (20) to house the rotor (10) and the stator (30); and an electrostatic shield (51) connected to the frame (40), the electrostatic shield (51) having a plurality of openings (51a) that allow the space where the stator (30) is disposed to communicate with the space where the rotor (10) is disposed.

Description

Technical Field

[0001] This invention relates to a rotating electric motor driven by a power conversion circuit including an inverter. Background Technology

[0002] In rotating electric machines driven by power conversion circuits including inverters, galvanic corrosion of the bearings occurs due to the switching action of the semiconductor elements contained in the inverter. This galvanic corrosion causes wear and damage to the bearings, reducing the reliability of the rotating electric machine.

[0003] Therefore, in existing rotating electric machines, electrostatic shielding is used to adjust the parasitic capacitance distribution inside the machine to reduce electro-corrosion, thereby reducing shaft voltage generated on the bearings. For example, in Patent Document 1, shaft voltage is reduced by configuring an electrostatic shielding material that is a non-magnetic, metallic conductor to block the openings of the stator slots.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-270507 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in Patent Document 1, the rotor and stator are spatially separated by an electrostatic shielding material. This results in heat generated in the rotor and stator being trapped in the narrow space. Consequently, for example, on the rotor side, demagnetization of the permanent magnets embedded in the rotor occurs, reducing the performance of the rotating machine. Furthermore, on the stator side, the insulation coating deteriorates due to the increased temperature of the stator windings, resulting in reduced insulation performance.

[0009] The present invention was made in view of the above circumstances, and its object is to provide a rotary motor that can reduce shaft voltage and ensure cooling performance.

[0010] Methods for solving problems

[0011] To solve the aforementioned problems and achieve the objective, the rotary electric motor of the present invention comprises: a rotor having a rotating shaft and a rotor core, wherein a plurality of magnets are embedded in the rotor core and the rotating shaft is fixed thereon; a stator having a stator core disposed opposite to the rotor core and a stator winding wound around the stator core; a pair of first bearings and second bearings supporting the rotating shaft; a frame fixed to the stator core and connected to the first and second bearings, for housing the rotor and the stator; and an electrostatic shielding member connected to the frame. The electrostatic shielding member has a plurality of openings that allow communication between the space where the stator is disposed and the space where the rotor is disposed.

[0012] The effects of the invention

[0013] The rotary motor according to the present invention has the effect of reducing shaft voltage and ensuring cooling performance. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of the rotary motor of Embodiment 1, parallel to the rotation axis.

[0015] Figure 2 This is a cross-sectional view of the rotary motor of Embodiment 1, perpendicular to the rotation axis.

[0016] Figure 3 This is a diagram showing the structure of the peripheral circuit of the rotary electric motor according to Embodiment 1.

[0017] Figure 4 This is an equivalent circuit diagram illustrating the principle of shaft voltage generation in the rotary motor of Embodiment 1.

[0018] Figure 5 This is a graph showing the time waveform of the shaft voltage in the rotary motor of Embodiment 1.

[0019] Figure 6 This is a diagram showing a comparative example of a rotary electric machine.

[0020] Figure 7 This is an enlarged cross-sectional view showing an example of the circumferential arrangement of the electrostatic shielding member in the rotary electric machine according to Embodiment 1.

[0021] Figure 8 This is an enlarged cross-sectional view showing another example of the circumferential configuration of the electrostatic shielding member in the rotary electric machine of Embodiment 1.

[0022] Figure 9 This is an enlarged cross-sectional view showing an example of the axial arrangement of the electrostatic shielding member in the rotary electric machine according to Embodiment 1.

[0023] Figure 10 This is a cross-sectional view of the rotary motor of Embodiment 2, parallel to the rotation axis.

[0024] Figure 11 This is a cross-sectional view of the rotary motor of Embodiment 2, perpendicular to the rotation axis.

[0025] Figure 12 This is a cross-sectional view of the rotary motor of Embodiment 3, parallel to the rotation axis.

[0026] Figure 13 This is a cross-sectional view of the rotary motor of embodiment 4, parallel to the rotation axis. Detailed Implementation

[0027] Hereinafter, a rotary motor according to an embodiment will be described in detail based on the accompanying drawings.

[0028] Implementation Method 1

[0029] use Figure 1 and Figure 2 The structure of the motor 100, which is a rotary electric motor according to Embodiment 1, will be described. Figure 1 This is a cross-sectional view of the motor 100 of Embodiment 1 taken along a plane parallel to the axis of rotation. Figure 2 This is a cross-sectional view of the motor 100 of Embodiment 1 taken along a plane perpendicular to the axis of rotation.

[0030] exist Figure 1 and Figure 2 In this motor, motor 100 employs a so-called brushless motor structure. Motor 100 includes a rotor 10, bearings 20, a stator 30, a frame 40, and an electrostatic shield 51. The electrostatic shield 51 has multiple openings 51a. The electrostatic shield 51 will be described in detail later.

[0031] The rotor 10 has a rotor core 11, a rotating shaft 12, and a plurality of permanent magnets 13. A hole for inserting the rotating shaft 12 is formed in the center of the rotor core 11, and the rotating shaft 12 is fixed concentrically with the hole. The rotor core 11 and the rotating shaft 12 are electrically connected. The load-connected side and the load-unconnected side of the rotating shaft 12 are respectively held by a pair of bearings 20, and the rotating shaft 12 is rotatable relative to the housing 41. The pair of bearings 20 correspond to a first bearing and a second bearing. Each bearing 20 has an inner ring 21a, a plurality of rigid balls 21b, and an outer ring 21c. The outer ring 21c is fixed to the housing 41, and the inner ring 21a is fixed to the rotating shaft 12. A plurality of permanent magnets 13 are embedded inside the rotor core 11. The rotor core 11 is, for example, formed by stacking and integrally forming thin sheets of electromagnetic steel in the direction of rotation.

[0032] The stator 30 is composed of a stator core 31 and a stator winding 32. The stator core 31 has an annular core back 33, teeth 34 extending radially from the inner circumference of the core back 33, and a flange 35 protruding circumferentially from the front end of the teeth 34. Radial refers to the direction that radiates outward from the rotation axis 12 with the rotation axis 12 as the origin, and circumferential refers to the direction on the circumference of a concentric circle with the rotation axis 12 as the origin. The stator core 31 is obtained, for example, by stacking and integrating thin sheets of electromagnetic steel in the direction of the rotation axis. The stator winding 32 is wound around the teeth 34 and housed in the slot 36. The part of the stator winding 32 that protrudes from the outermost layer of the stator core 31 is called the coil end. As for the winding method of the stator winding 32, there is a winding method called concentrated winding, in which the stator winding 32 is wound around each tooth 34, and a winding method called distributed winding, in which the winding is carried out across multiple teeth 34. Regardless of the winding method, the effects of the implementation method described later can be obtained in the same way.

[0033] The frame 40 is composed of a housing 41 and brackets 42a and 42b. Brackets 42a and 42b correspond to the first bracket and the second bracket. The housing 41 has a cylindrical shape and is integrally fixed to each other with the inner circumferential surface of the housing 41 facing the outer circumferential surface of the back surface 33 of the stator core 31. The housing 41 and the back surface 33 of the stator core 31 are electrically connected. At each end of the housing 41, i.e., at the openings on the load connection side and the load non-connection side, brackets 42a and 42b are fastened with bolts or the like. In addition, brackets 42a and 42b are fixed to the outer ring 21c of the bearing 20. These integrated housings 41 and brackets 42a and 42b serve as the frame 40 of the motor 100, and house the rotor 10, the bearing 20, and the stator 30 inside.

[0034] Next, use Figure 3 This section explains the structure of the peripheral circuit of the motor 100 in the driving implementation method 1. Figure 3 This is a diagram showing the structure of the peripheral circuitry of the motor 100. The peripheral circuitry includes an inverter section 80, a power supply section 90, and wiring connecting them.

[0035] The power supply unit 90 is a DC power source that supplies the power required by the drive motor 100. For example, lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries can be used as DC power sources.

[0036] The inverter section 80 has a structure in which a first noise filter section 82, a first power conversion circuit section 83, a second noise filter section 84, and a second power conversion circuit section 85 are connected in series.

[0037] The first power conversion circuit section 83 includes a semiconductor switching element. For the voltage supplied from the power supply section 90 via the first noise filter section 82, the first power conversion circuit section 83 adjusts the ratio of the on-time to the off-time of the semiconductor switching element to boost or buck the DC voltage supplied from the power supply section 90 into a DC voltage of other voltages. The first power conversion circuit section 83 functions as a so-called converter circuit.

[0038] The second power conversion circuit section 85 is connected to the first power conversion circuit section 83 via a second noise filter section 84. The second power conversion circuit section 85 includes semiconductor switching elements. Taking the DC voltage output from the first power conversion circuit section 83 as input, the second power conversion circuit section 85 outputs the three-phase AC current required to drive the motor 100 by adjusting the ratio of the on-time and off-time of the switching elements. The second power conversion circuit section 85 functions as a so-called inverter circuit.

[0039] The switching elements included in the first power conversion circuit section 83 and the second power conversion circuit section 85 can be, for example, IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

[0040] The first noise filter section 82 is disposed between the power supply section 90 and the first power conversion circuit section 83 to prevent high-frequency noise generated by the switching operation of the semiconductor switching element of the first power conversion circuit section 83 from leaking to the power supply section 90. The second noise filter section 84 is disposed between the first power conversion circuit section 83 and the second power conversion circuit section 85 to prevent high-frequency noise generated by the switching operation of the semiconductor switching element of the second power conversion circuit section 85 from leaking to the power supply section 90.

[0041] The first noise filter section 82 and the second noise filter section 84 include an inductor and a capacitor. The inductor is connected in series to the positive side of the power supply section 90 in the DC power line. As an inductor, for example, a coil made of wire wound on a magnetic core such as ferrite can be used. The capacitor has a so-called X capacitor that is connected in parallel to the positive and negative sides of the DC power line, and a so-called Y capacitor that is connected in parallel between the positive power line and ground GND, and between the negative power line and ground GND. The ground GND of the first noise filter section 82 and the second noise filter section 84 refers to the frame of the inverter section 80.

[0042] The first noise filter section 82, the first power conversion circuit section 83, the second noise filter section 84, and the second power conversion circuit section 85 can be mounted on the same electronic substrate, or they can be mounted on separate electronic substrates.

[0043] The frame of the inverter section 80 is made of a conductive metal and also functions as an electromagnetic noise shield, preventing the intrusion of electromagnetic waves from the outside and preventing electromagnetic waves generated from the first power conversion circuit section 83 and the second power conversion circuit section 85 from leaking to the outside. The frame of the inverter section 80 is made of a conductive metal such as aluminum.

[0044] The negative side of the power supply unit 90, the frame of the inverter unit 80, and the housing 41 of the motor 100 are grounded to the same reference conductor.

[0045] Furthermore, this embodiment shows a structure where the power supply unit 90 uses a DC power supply, but the power supply unit 90 does not need to be a DC power supply; an AC power supply can also be used. In this case, the first power conversion circuit unit 83 can be replaced by a circuit that takes an AC voltage as input and converts it into a DC voltage of a different voltage.

[0046] Next, use Figure 1 , Figure 2 The structure of the electrostatic shielding component 51 is described below. The electrostatic shielding component 51 has a cylindrical shape concentric with the rotation axis 12. As the material of the electrostatic shielding component 51, a non-magnetic metal with high electrical conductivity is preferred, such as aluminum alloy or copper.

[0047] An electrostatic shielding element 51 is disposed in the gap formed between the outer peripheral surface of the rotor core 11 and the inner peripheral surface of the stator core 31. One end of the electrostatic shielding element 51 is electrically connected to the bracket 42a on the load connection side, and the other end is also electrically connected to the bracket 42b on the load non-connection side. The electrostatic shielding element 51 can be fastened to the brackets 42a and 42b by screws or the like, or it can be integrally formed with the brackets 42a and 42b, thus omitting the positioning step relative to the brackets 42a and 42b. In this case, the electrostatic shielding element 51 is made of the same material as the brackets 42a and 42b. In addition, since the brackets 42a and 42b are electrically connected to the housing 41, the connection destination of one end of the electrostatic shielding element 51 can also be the housing 41. The electrostatic shield 51 can be in contact with a part of the stator core 31 or spaced apart from the stator core 31 as long as it is disposed in the gap between the outer peripheral surface of the rotor core 11 and the inner peripheral surface of the stator core 31.

[0048] The electrostatic shield 51 has multiple openings 51a that pass through the rotor 10 side and the stator 30 side, creating a structure that allows the refrigerant to flow freely between the rotor 10 side and the stator 30 side. In other words, the multiple openings 51a connect the space where the stator 30 is disposed with the space where the rotor 10 is disposed.

[0049] use Figure 2 , Figure 7 An example of the circumferential configuration of the opening 51a will be described. Figure 7 This is an enlarged cross-sectional view showing an example of the circumferential arrangement of the electrostatic shielding component 51. For example... Figure 2 , Figure 7 As shown, the opening 51a is configured to face the teeth 34 of the stator core 31. Regarding the number of openings 51a, they can be configured to be the same as the number of teeth 34, or they can be configured to face a specific portion of the teeth 34.

[0050] The operation of the motor 100 in Embodiment 1 will now be explained. First, the principle of the rotation of the rotor 10 of the motor 100 will be explained.

[0051] The DC voltage supplied from the power supply unit 90 is converted in the inverter unit 80 to a specified voltage by stepping up or stepping down, converting DC to three-phase AC with a specific frequency. The inverter unit 80 supplies three-phase AC current to the stator winding 32 of the motor 100 via the three-phase power lines. The magnetic flux induced in each tooth 34 by the three-phase AC current flowing through the stator winding 32 forms a magnetic loop via the core back 33, generating a rotating magnetic field. When the rotating magnetic field is generated according to the above principle by the three-phase AC current flowing through the stator winding 32, the permanent magnet 13 mounted on the rotor core 11 is subjected to electromagnetic force by the electromagnetic force induced by the rotating magnetic field, causing the rotor core 11 to rotate. The rotor core 11 is rotatably disposed in the space surrounded by the flanges 35 on the inner circumference of the stator core 31, and the rotor core 11 and the rotating shaft 12 are fixed to each other. Therefore, by connecting the load to the rotating shaft 12, the driving force generated by the rotation of the rotor core 11 can be extracted to the outside of the motor 100. At this time, a gear for changing the rotation ratio can also be clamped between the rotating shaft 12 and the load.

[0052] Next, use Figure 4 This explains the principle of generating shaft voltage in the motor 100 driven by the inverter section 80. Figure 4 This is an equivalent circuit diagram illustrating the generation principle of the shaft voltage in the motor 100. Here, the shaft voltage is defined as the potential of the rotating shaft 12, measured with reference to the potential of the housing 40. Figure 4In this diagram, point G represents the potential of the frame 40, point N represents the neutral point potential of the stator winding 32, and point S represents the potential of the rotating shaft 12. Here, the potential difference V1 between points N and G represents the neutral point voltage of the motor 100, and the potential difference V2 between points S and G represents the shaft voltage of the motor 100. Additionally, C1 represents the parasitic capacitance between the stator winding 32 and the rotor 10, and C2 represents the parasitic capacitance between the rotor 10 and the frame 40.

[0053] To drive the motor 100, the semiconductor switching element group included in the second power conversion circuit section 85 performs switching operations at a carrier frequency fc based on PWM control. At this time, the magnitude of the neutral point voltage V1 also varies in a stepwise manner according to the period of the carrier frequency fc.

[0054] The variation of the neutral point voltage V1 generated between the frame 40 and the stator winding 32 is divided by the parasitic capacitances C1 and C2 distributed inside the motor 100, thereby inducing a limited potential difference, i.e., shaft voltage, on the rotating shaft 12 relative to the frame 40.

[0055] The impedance Z at frequency f of the parasitic capacitance C is shown in equation (1).

[0056] Z(C)=1 / (2πfC)…(1)

[0057] Therefore, the shaft voltage V2 is represented by the following equation (2).

[0058] V2={Z(C2) / (Z(C1)+Z(C2))}×V1

[0059] ={C1 / (C1+C2)}×V1…(2)

[0060] The effect of electrostatic shielding between the stator winding 32 and the rotor 10 will be explained below. Without electrostatic shielding, a shaft voltage V2 is applied between the inner ring 21a and the outer ring 21c of the bearing 20. If the shaft voltage V2 exceeds the insulation breakdown voltage of the lubricating oil coated on the rigid ball 21b, an impulse current flows between the inner ring 21a and the outer ring 21c, resulting in bearing wear and damage known as electro-corrosion. This significantly reduces the reliability of the motor, and bearing replacement is necessary in cases of significant damage due to electro-corrosion. To reduce the generation of such shaft voltage, according to equation (2), it is sufficient to adjust the capacitance ratio of C1 to C2, particularly by making C1 sufficiently small relative to C2, which can suppress the generation of shaft voltage V2.

[0061] Since C1 is the parasitic capacitance between the stator winding 32 and the rotor 10, in order to reduce the size of C1, electrostatic shielding can be performed between the stator winding 32 and the rotor 10.

[0062] Furthermore, the performance degradation of the motor 100 is explained due to the temperature rise caused by heat generation inside the frame 40 of the motor 100. Achieving high output of the motor 100 or miniaturization of the frame 40 is important in industry, but these are accompanied by an increase in temperature inside the frame 40. As a result, the temperature of the permanent magnet 13 embedded in the rotor core 11 rises, the coercivity of the permanent magnet 13 decreases, and the performance of the motor 100 deteriorates significantly. Additionally, the insulation performance of the stator winding 32 deteriorates due to the temperature rise. In either case, the temperature rise reduces the reliability of the motor 100, greatly limiting its performance.

[0063] As mentioned above, in order to obtain a motor with high reliability, capable of handling high output and miniaturization, it is necessary to suppress the generation of electro-corrosion caused by shaft voltage while suppressing the temperature rise inside the housing.

[0064] The effect of the electrostatic shielding component 51 will be explained below. (Refer to...) Figure 4 As explained in equation (2), the shaft voltage V2 is the voltage generated by the neutral point voltage V1 generated by the stator winding 32 being divided and applied to the rotating shaft 12 according to the parasitic capacitance distribution inside the frame 40. The shaft voltage V2 can be suppressed by electrostatic shielding between the stator winding 32 and the rotor 10.

[0065] As described above, the electrostatic shielding component 51 has a cylindrical shape, such as... Figure 1 As shown, the gap between the rotor core 11 and the stator core 31 is provided. Furthermore, the two ends of the electrostatic shield 51 are electrically connected to the brackets 42a and 42b, respectively. The electrostatic shield 51 becomes a conductor at the same potential as the frame 40, thus providing electrostatic shielding against capacitive coupling between the stator winding 32 and the rotor 10. Consequently, the parasitic capacitance C1 generated between the stator winding 32 and the rotor 10 is relatively smaller than the parasitic capacitance C2, resulting in a reduction in the shaft voltage V2 supplied to the rotating shaft according to equation (2).

[0066] Figure 5 This is a graph showing the measured results of the time waveform of the axis voltage used to verify the shielding effect of the electrostatic shielding component 51. The line indicated by reference numeral S1 shows the state without the electrostatic shielding component, and the line indicated by reference numeral S2 shows the state with the electrostatic shielding component 51. Figure 5 In this context, the frame 40 is used as the reference potential, and the potential of the rotating shaft 12 is represented as the shaft voltage. Figure 5 It can be seen that by setting the electrostatic shield 51, the observed shaft voltage can be reduced.

[0067] The cooling effect produced by the electrostatic shield 51 having an opening 51a in Embodiment 1 will be explained below by comparing the structure with that of the comparative example. Figure 6 This is a diagram showing motor 200 as a comparative example. (See diagram below.) Figure 6 As shown, the comparative example motor 200 includes: a rotor 210 having a rotor core 211 and a rotating shaft 212; a stator 230 having a stator core 231 and a stator winding 232; and an electrostatic shield 253 without openings. In the electrostatic shield 253, a conductive member is used as a partition wall between the stator 230 and the rotor 210 to reduce shaft voltage. However, in this structure, the stator 230 and the rotor 210 are spatially separated. Therefore, the heat generated in the stator 230 and the rotor 210 is trapped in their respective spaces, and the temperature gradient is limited by the efficiency of heat exchange through the conductive walls. As a result, for example, on the rotor 210 side, the permanent magnet embedded in the rotor 210 may demagnetize due to temperature rise, impairing the performance of the motor 200. Furthermore, on the stator 230 side, the insulation of the stator winding 232 may deteriorate due to temperature rise, leading to a deterioration in insulation performance and consequently a reduction in the reliability of the motor 200.

[0068] On the other hand, the electrostatic shielding member 51 of the motor 100 in Embodiment 1 has an opening 51a in its cylindrical wall. This opening 51a penetrates both the inner and outer circumferential surfaces of the electrostatic shielding member 51, allowing refrigerant to flow freely between the rotor 10 side and the stator 30 side. Thus, in addition to heat exchange via the conductive wall, refrigerant-based heat exchange is also achieved, enabling efficient cooling of the rotor 10 and stator 30. As the refrigerant in the structure of the motor 100, air cooling using air can be employed.

[0069] Figure 7 This is an enlarged cross-sectional view showing an example of the circumferential arrangement of the electrostatic shielding member 51 in the motor 100. (Example) Figure 7 As shown, by configuring the opening 51a to face the teeth 34 of the stator 30 in the circumferential direction, the refrigerant can be selectively guided to the teeth 34. This allows for more direct cooling of the teeth 34 and the coil ends in the stator winding 32.

[0070] Figure 8 This is an enlarged cross-sectional view showing another example of the circumferential configuration of the electrostatic shield 51 in the motor 100. As another circumferential configuration, such as... Figure 8 As shown, by configuring the opening 51a to face the slot 36 of the stator 30, the refrigerant can be selectively guided to the slot 36. This allows for more direct cooling of the slot 36 and the portion of the stator winding 32 housed within the slot 36.

[0071] Figure 9This is an enlarged cross-sectional view showing an example of the axial configuration of the electrostatic shield 51 in the motor 100, and a diagram showing the positional relationship between the opening 51a of the electrostatic shield 51 and the axial direction of the stator 30. Multiple openings 51a of the electrostatic shield 51 are intermittently provided along the axial direction, but as... Figure 9 As shown, by configuring a portion of the opening 51a to face the coil end of the stator winding 32, the refrigerant can be selectively guided to the coil end. This allows for more direct cooling of the coil end.

[0072] The shape of the opening 51a shown above can be rectangular or elliptical. Furthermore, the opening area on the rotor 10 side of the opening 51a can be different from the opening area on the stator 30 side. That is, the radial cross-sectional shape of the opening 51a can be different, while the circumferential cross-sectional shape is the same.

[0073] As explained above, according to Embodiment 1, the electrostatic shield 51 has an opening 51a, thus enabling a motor 100 that can reduce shaft voltage while cooling the rotor 10 and stator 30.

[0074] Implementation Method 2

[0075] use Figure 10 and Figure 11 The structure of the motor 300 in Embodiment 2 will be described. Figure 10 This is a cross-sectional view of the motor 300 of Embodiment 2 taken along a plane parallel to the axis of rotation. Figure 11 This is a cross-sectional view of the motor 300 of Embodiment 2 taken along a plane perpendicular to the axis of rotation.

[0076] In embodiment 2, the electrostatic shield 52 does not isolate the space between the stator core 31 and the rotor 10. The electrostatic shield 52 is composed of a first electrostatic shield 52c and a second electrostatic shield 52d. The first electrostatic shield 52c is arranged to connect the outermost layer of the stator core 31 and the bracket 42a. The second electrostatic shield 52d is arranged to connect the outermost layer of the stator core 31 and the bracket 42b. The first electrostatic shield 52c and the second electrostatic shield 52d have a plurality of openings 52a communicating between the rotor 10 side and the stator 30 side. The circumferential arrangement of the openings 52a can also be... Figure 7 and Figure 8 Any of the positions shown. The axial configuration position for the opening 52a can also be adopted. Figure 9 The positions shown are such that, since the brackets 42a, 42b and the housing 41 are electrically connected, the connection destination of one end of the first electrostatic shield 52c and the second electrostatic shield 52d can also be the housing 41.

[0077] In this embodiment 2, the electrostatic shield 52 becomes a conductor at the same potential as the frame 40, thus shielding the capacitive coupling between the coil ends in the stator winding 32 and the rotor 10. As a result, the parasitic capacitance C1 generated between the stator winding 32 and the rotor 10 can be made relatively small compared to the parasitic capacitance C2, and consequently, the shaft voltage V2 divided according to equation (2) can be reduced.

[0078] Furthermore, in Embodiment 2, since the space between the stator core 31 and the rotor 10 is not isolated, it is an advantageous structure from the viewpoint of cooling.

[0079] For the parts of the outermost layer of the stator core 31 that are connected to the first electrostatic shield 52c and the second electrostatic shield 52d, by removing a portion of the insulation covering of the stator core 31, it can make electrical contact with the first electrostatic shield 52c and the second electrostatic shield 52d, thereby achieving a more effective electrostatic shielding effect.

[0080] Furthermore, the first electrostatic shield 52c and the second electrostatic shield 52d do not necessarily need to be fixed to the outermost layer of the stator core 31. They can also be fixed to the inner layer of the stator core 31 by providing a recess of the same degree as the opening hole 52a. Alternatively, a flexible member such as a conductive washer can be used to make the second electrostatic shield 52d contact the stator core 31. They have the effect of buffering the impact on the electrostatic shield 52 caused by the vibration of the motor 300. In addition, by absorbing manufacturing tolerances and assembly tolerances, the assemblability of the motor 300 is improved.

[0081] As explained above, according to Embodiment 2, the stator core 31 is not isolated from the space on the rotor 10 side, thus making it a more advantageous structure from a cooling point of view compared to Embodiment 1.

[0082] Implementation Method 3

[0083] use Figure 12 The structure of the motor 400 in Embodiment 3 will be described. Figure 12 This is a cross-sectional view of the motor 400 of Embodiment 3 taken along a plane parallel to the rotation axis.

[0084] In addition to the structure of the motor 100 in Embodiment 1, the motor 400 also includes refrigerant passages 71-77, a pump 61, and a heat exchanger 62.

[0085] The refrigerant passages, i.e., the paths through which the refrigerant passes for cooling the rotor 10 and stator 30, will be described. The rotor 10 has refrigerant passages 71, 72, 73, and 74. Refrigerant passage 71 is located on the load-free side of the rotating shaft 12 and is an elongated hole extending along the axial length of the rotating shaft 12, with the load-free side serving as an opening for refrigerant supply. Refrigerant passage 72 communicates with refrigerant passage 71 and is an elongated hole extending radially in the circumferential direction of the rotor core 11. Refrigerant passage 73 communicates with refrigerant passage 72 and is an elongated hole extending along the axial length of the rotor core 11. Refrigerant passage 74 communicates with refrigerant passage 73 and is an elongated hole extending radially in the circumferential direction of the rotor core 11, with an opening at the outer periphery of the rotor core 11. Refrigerant passages 74 are located at multiple axial locations within the rotor core 11. These refrigerant passages 71, 72, 73, and 74 are interconnected, forming a refrigerant passage from the opening on the load-free side of the rotating shaft 12 to the opening on the outer periphery of the rotor core 11.

[0086] The frame 40 has refrigerant passages 75 and 76. The refrigerant passage 75 is a hole provided in the housing 41, with openings near the coil end on the load connection side and the coil end on the load non-connection side, respectively. The refrigerant passage 76 is a hole serving as a refrigerant discharge port for the bracket 42b provided on the load non-connection side.

[0087] The motor 400 is externally equipped with piping 77a, 77b, 77c serving as a refrigerant passage 77, a pump 61, and a heat exchanger 62. Piping 77a is connected to the refrigerant passage 76 and to the heat exchanger 62. Piping 77b connects the heat exchanger 62 and the pump 61. Piping 77c is connected to the pump and to the refrigerant passage 71.

[0088] The operation of the motor 400 in Embodiment 3 will be explained. Refrigerant driven by pump 61 is supplied to refrigerant passage 71, which has a refrigerant supply port, via piping 77c. The refrigerant passes through interconnected refrigerant passages 71, 72, 73, and 74. In addition to the driving force of the pump from the opening in the rotor core 11 towards the stator 30, the refrigerant is also sprayed towards the electrostatic shield 51 by the centrifugal force generated by the rotation of the rotor 10. The refrigerant is guided to the stator core 31 and stator winding 32 through the opening 51a provided in the electrostatic shield 51. The refrigerant dripping from the stator 30 passes through the opening 51a again and is finally discharged to the outside of the frame 40 via refrigerant passage 75 from the refrigerant outlet provided in the refrigerant passage 76. The discharged refrigerant is sent to the heat exchanger 62 via piping 77a. In the heat exchanger 62, the heat of the refrigerant that has risen in temperature inside the housing 40 is reduced, so that the cooled refrigerant is supplied back to the pump 61 through the piping 77b.

[0089] The effects of the motor 400 in Embodiment 3 will now be explained. During the passage of refrigerant through refrigerant passages 71, 72, 73, and 74 provided in the rotor 10, the refrigerant exchanges heat with the rotor core 11 and the permanent magnet 13. Thus, by absorbing the heat present in the rotor core 11 and the permanent magnet 13, the temperature rise of the rotor core 11 and the permanent magnet 13 can be suppressed. In particular, the electrostatic shield 51 has an opening 51a, allowing refrigerant to flow towards the stator 30. Thus, the refrigerant exchanges heat with the stator winding 32, absorbing the heat from the stator winding 32, thereby suppressing the temperature rise of the stator winding 32. The heat absorbed by the refrigerant is discharged to the outside of the motor 400 in the heat exchanger 62. Therefore, in the motor 400 of this embodiment, the shaft voltage can be reduced while the temperature rise of the rotor 10 and the stator 30 can be efficiently suppressed using the refrigerant. For example, insulating oil or air can be used as the refrigerant.

[0090] As a circumferential configuration of the opening 51a, such as Figure 7 As shown, by providing an opening 51a facing the tooth 34, the refrigerant can be selectively guided to the tooth 34. This allows for more direct cooling of the tooth 34 and the coil ends in the stator winding 32.

[0091] In addition, other circumferential configurations of the opening 51a, such as Figure 8 As shown, by providing an opening 51a facing the slot 36, the refrigerant can be selectively guided to the slot 36. This allows for more direct cooling of the slot 36 and the portion of the stator winding 32 housed within the slot 36.

[0092] Furthermore, regarding the axial configuration of the opening 51a, such as Figure 9 As shown, by providing an opening facing the coil end, the refrigerant can be selectively guided to the coil end. This allows for more direct cooling of the coil end.

[0093] As explained above, according to Embodiment 3, the motor 400 has refrigerant passages 71 to 77 that allow refrigerant to circulate within it, and the opening 51a of the electrostatic shield 51 forms part of the refrigerant passages, thereby enabling the motor 400 to efficiently cool the rotor 10 and stator 30 while reducing shaft voltage.

[0094] Implementation Method 4

[0095] use Figure 13 The structure of the motor 500 in Embodiment 4 will be described. Figure 13This is a cross-sectional view of the motor 500 of Embodiment 4 taken along a plane parallel to the axis of rotation. In addition to the structure of the motor 300 of Embodiment 2, the motor 500 also includes refrigerant passages 71-77, a pump 61, and a heat exchanger 62.

[0096] By adopting this structure, the stator core 31 can be directly cooled using refrigerant. This results in more efficient cooling performance. Furthermore, since the coil ends are electrostatically shielded by the electrostatic shield 52, shaft voltage can also be reduced.

[0097] As explained above, according to embodiment 4, the motor 500 has refrigerant passages 71 to 77 that allow refrigerant to circulate within it, and the opening 52a of the electrostatic shield 52 forms part of the refrigerant passages, thereby enabling the motor 500 to efficiently cool the rotor 10 and stator 30 while reducing shaft voltage.

[0098] The structure shown in the above embodiments represents one example of the content of the present invention. It can also be combined with other known technologies, and a part of the structure can be omitted or modified without departing from the spirit of the present invention.

[0099] Explanation of reference numerals in the attached figures

[0100] 10 Rotor, 11 Rotor core, 12 Rotating shaft, 13 Permanent magnet, 20 Bearing, 30 Stator, 31 Stator core, 32 Stator winding, 33 Core back, 34 Tooth, 35 Flange, 36 Slot, 40 Frame, 41 Housing, 42a, 42b Brackets, 51, 52 Electrostatic shielding, 51a, 52a Openings, 61 Pump, 62 Heat exchanger, 71-77 Refrigerant passages, 80 Inverter section, 82 First noise filter section, 83 First power conversion circuit section, 84 Second noise filter section, 85 Second power conversion circuit section, 90 Power supply section, 100, 200, 300, 400, 500 Motors.

Claims

1. A rotary electric motor, characterized in that, have: A rotor has a rotating shaft and a rotor core, wherein a plurality of magnets are embedded in the rotor core and the rotating shaft is fixed thereon; The stator has a stator core disposed opposite to the rotor core and a stator winding wound on the stator core; A pair of first and second bearings support the rotating shaft; A frame, fixed to the stator core, connected to the first bearing and the second bearing, houses the rotor and stator; and An electrostatic shielding element, connected to the frame, is disposed in the gap formed between the outer peripheral surface of the rotor core and the inner peripheral surface of the stator core. The frame has a cylindrical outer shell fixed to the stator core, a first bracket connecting one end of the outer shell to the first bearing, and a second bracket connecting one end of the outer shell to the second bearing. The electrostatic shielding component includes a first electrostatic shielding component and a second electrostatic shielding component. One end of the first electrostatic shield is connected to the first bracket, and the other end of the first electrostatic shield is connected to the stator core. One end of the second electrostatic shield is connected to the second bracket, and the other end of the second electrostatic shield is connected to the stator core. The first electrostatic shield and the second electrostatic shield have a plurality of openings that allow the space where the stator is configured to communicate with the space where the rotor is configured.

2. The rotary motor according to claim 1, characterized in that, The plurality of openings are arranged circumferentially on the rotor facing the teeth of the stator.

3. The rotary motor according to claim 1, characterized in that, The plurality of openings are arranged circumferentially on the rotor facing the slots of the stator.

4. The rotary motor according to claim 1, characterized in that, The plurality of openings are arranged axially on the rotating shaft facing the coil ends of the stator winding of the stator.

5. The rotary electric motor according to any one of claims 1 to 4, characterized in that, The rotating shaft has a first refrigerant passage for refrigerant to flow through, and the rotor has a second refrigerant passage for the refrigerant to flow through. The refrigerant can flow toward the stator winding via the first refrigerant passage, the second refrigerant passage, and the opening.

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