TW201926856A - Slotless electric motor, and electric blower or electric vacuum cleaner using same including a hollow cylindrical core, a stator, a permanent magnet rotor and a frame body - Google Patents

Abstract

To provide a miniaturized high-speed electric motor that improves electric motor efficiency and an electric blower or electric vacuum cleaner using the same. The solution comprises: a hollow cylindrical core; a stator that is formed by a coil made by winding a conductor onto the core; a permanent magnet rotor that is opposite to an inner coil of the stator and configured to be rotatable, and a frame body that is disposed outside the stator, holds the stator and has a hollow inside.

Description

Slotless motor, and electric blower or electric vacuum cleaner using the same

The present invention relates to a slotless motor and an electric blower or electric vacuum cleaner using the same.

In a wireless vacuum cleaner that has been rapidly increasing in demand in recent years, an electric blower using a brushless motor is mounted in order to obtain a sufficient output even in a low-voltage battery drive.

In order to achieve the demand for miniaturization of the electric vacuum cleaner, the size of the electric blower has been reduced. With regard to miniaturization of the electric blower, the electric blower can be speeded up to reduce the outer shape of the fan. Therefore, there are many examples in which the number of rotations of the brushless motor is set to be about 80,000 rpm or more. As a structure of the brushless motor for a vacuum cleaner, the motor of the patent document 1 is mentioned. In the motor of Patent Document 1, the coil is wound around the tooth portion projecting inward in the circumferential direction of the stator core, thereby constituting the stator. As a structure suitable for a small-sized and high-speed brushless motor for a vacuum cleaner, there is a grooveless structure having no tooth core on the stator side as in Patent Document 2 or Patent Document 3. Since the structure of the patent document 2 or the patent document 3 does not have a tooth core, it is a structure which can shorten a diameter, and can reduce iron loss. Further, in Patent Document 2, an inner rotor is disposed inside the stator core, and an outer rotor is disposed outside, and a double rotor structure is provided, thereby increasing torque output. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP-A-5-161290 (Patent Document 3) WO15/104795

[Problems to be solved by the invention]

However, the electric motor is increased in speed, and the iron loss is increased, which causes a decrease in the efficiency of the motor. In addition, by miniaturizing the motor, the amount of heat generated near the volume increases and the area of the heat dissipation decreases, and the temperature of the motor rises. Therefore, the loss of the residual magnetic flux of the magnet or the increase in the coil resistance increases the copper loss. The reason for the decrease in motor efficiency. In order to reduce the size of the motor of the patent document 1, it is conceivable to shorten the tooth portion. Therefore, it is necessary to reduce the number of turns of the coil or to reduce the wire diameter of the coil, which may cause a decrease in motor efficiency. However, in the structures of Patent Document 2 and Patent Document 3, air cooling of the motor is not considered, and when the diameter is reduced, the motor cannot be sufficiently cooled, and the efficiency of the motor is lowered.

The present invention has been made to solve the above problems, and provides a small-sized high-speed motor that improves motor efficiency and an electric blower or electric vacuum cleaner using the same. [Means to solve the problem]

In order to solve the above problems, the present invention is characterized in that it has a hollow cylindrical core, a stator formed by a coil wound around the core, and a permanent magnet rotor which is an inner coil of the stator. The housing is rotatably disposed, and a housing that holds the stator and has a hollow inside is disposed outside the stator. [Effects of the Invention]

According to the present invention, the motor is shortened in a grooveless structure having no tooth core, and the inner coil is moved to the motor by the coil wound around the stator core, and the outer coil is used as a radiator for heat dissipation. By functioning, a small high-speed motor that improves motor efficiency and an electric blower or electric vacuum cleaner using the same can be obtained.

Fig. 1 is a perspective view showing a stator and a rotor of an electric motor according to an embodiment of the present invention.

The motor shown in Fig. 1 is a so-called slotless motor. In the slotless motor, the structure is characterized in that the core (core) of the stator has no teeth, and the surface of the gap surface coil facing the rotor is exposed. In FIG. 1, the motor 100 is composed of a slotless stator 51, a rotor 50 disposed inside the slotless stator 51, and a frame 52 disposed on the outer side of the slotless stator 51. The rotor 50 has a rotor permanent magnet 1 and a shaft 2. As a material of the rotor permanent magnet 1, a neodymium iron nitrogen magnet, a neodymium magnet, a ferrite magnet, or the like can be considered. Further, in order to prevent breakage of the magnet at the time of high-speed rotation, it may be protected by the shield 3. As a material of the shield 3, SUS, CFRP, etc. can be considered. Figure 2 is a portion of the slotless stator 51 in the middle of assembly. The slotless stator 51 has a split slotless stator core 4, a stator coil 5, and a stator coil core strip 6. The slotless stator 51 is obtained by winding the stator coil 5 of the conductor around the stator coil core strip 6, and inserting the plurality of stator coils 5 into the split slotless stator core 4 to assemble them. In the divided slotless stator core 4 of Fig. 2, the cylindrical core is divided into two, but the number of divisions may be several. Further, after assembly, it is considered to be fixed by resin molding. The frame body 52 is composed of the inner frame body 7 and the outer frame body 8, and a space between the inner frame body 7 and the outer frame body 8 is a void and serves as a flow path for air. By having a grooveless structure, it is possible to have a small and high-speed structure suitable for a brushless motor for a vacuum cleaner.

Figure 2 is a cross-sectional view of Figure 1 (b). In one embodiment of the present invention, as shown in FIG. 1(b) and FIG. 2, when a current flows through the stator coil 5, a cylindrical stator core 11 in which the slotless stator core 4 is divided is assembled. The stator coil 5 is configured by flowing a direction in which a magnetic flux flows in the circumferential direction. Further, the stator coil 5 has a U-phase coil, a V-phase coil, and a W-phase coil, and flows a current of three phases, which are three-phase alternating currents whose phases are different from each other by 120 degrees. The rotor permanent magnet 1 illustrated in Fig. 3 is a four-pole magnet arrangement in which the rotor permanent magnet N pole 1a and the rotor permanent magnet S pole 1b are disposed adjacent to each other. The stator coil 5 illustrated in FIG. 3 is composed of twelve inner coils 9 facing the rotor permanent magnet 1 and twelve outer coils 10 supported by the inner casing 7 when viewed in cross section. When the cross section of the U-phase coil is located at the position of the inner coil Ua13, the inner coil Ub14 which is shifted by 90 degrees clockwise and the inner coil Ud16 which is shifted by 270 degrees are used to make the current in the same phase in the axial direction. Flow in the opposite direction. Further, the inner coil Uc15 is connected at a position shifted by 180 degrees from the inner coil Ua so that currents of the same phase flow in the same direction in the axial direction. The V-phase coil and the W-phase coil are also connected in the same manner at positions shifted by 120 degrees. The UVW illustrated in Fig. 3 indicates that currents flowing in the same phase are present, and +- indicates that the flow direction of the current is opposite in the axial direction. Coils of the same phase can also be connected in series or in parallel. With this arrangement, the current flowing through the inner coil 9 generates a rotating magnetic field, and the rotor 50 is rotated to generate torque.

The twelve inner coils 9 each have a pair of outer coils 10, and as shown in Fig. 1(a), the pair of inner coils 9 and outer coils 10 are connected at the coil end portion 17, and the pair of inner coils are connected. 9 and the outer coil 10 are such that the current in the same phase flows in the opposite direction in the axial direction. The coil end portion 17 is present above the drawing surface and below the drawing surface (not shown). The outer coil 10 does not contribute to the generation of torque, but is held by the inner casing 7, and the inner casing 7 and the outer casing 8 are hollow, and become a flow path of air. The inner frame 7 is cooled by the flowing air, thereby cooling the outer coil 10. Since the outer coil 10 is connected to the inner coil 9 at the coil end portion 17, the inner coil 9 is cooled by cooling the outer coil 10, and the slotless motor 100 can be cooled from the inside. The outer coil 10 does not contribute to the generation of torque, but can be said to function as a heat sink. By lowering the temperature of the motor, the magnetic flux density of the magnet is increased and the coil resistance is reduced, whereby the copper loss is reduced, and the motor efficiency is improved.

The grooveless stator 51 is fixed to the inner casing 7 by, for example, resin bonding or the like. When the stator coil 5 is in contact with the inner casing 7, the cooling effect is high, but resin or the like may be provided between the stator coil 5 and the inner casing 7. As a material of the inner frame 7 and the outer frame 8, it is conceivable to use a metal, a resin, or both of them, but if a metal is used, the cooling effect is high.

As the material of the stator coil, copper or aluminum can be considered. Further, as the material of the stator core, an electromagnetic steel sheet whose main component is iron can be considered. As shown in FIG. 4, when the stator 61 having the structure in which the number of coils 5 is wound around the tooth portion 19 of the stator core 18 having the tooth portion 19 is used instead of the slotless stator 51 of the embodiment, the inner frame is used. The body 7 is configured to hold the stator core 18. At this time, the thermal conductivity of iron is lower than that of copper or aluminum, so the cooling effect is lower than that of the configuration of the present embodiment.

Next, a second embodiment of the present invention will be described. Fig. 5 shows a modification of the structure of the holding frame of the motor according to the embodiment of the present invention. Fig. 5 is a perspective view and a cross-sectional view showing the structure of the motor of the embodiment. The point different from the embodiment shown in FIGS. 1 to 3 is that the inner frame 7 and the outer frame 8 are contacted by the beam 20. The inner frame 7 and the outer frame 8 are contacted by the beam 20, whereby heat generated by the slotless motor 100 is easily transmitted to the outer frame 8. In this configuration, the air flowing through the inner frame 7 and the outer frame 8 and the beam 20 is cooled, whereby the slotless motor 100 can be cooled. The surface area cooled by the flowing air is wider than the embodiment of FIGS. 1 to 3, so the cooling effect is high. As the material of the beam 20, a metal or a resin can be considered, and the cooling effect of the metal is high. The beam 20 may be assembled as a different component from the inner frame 7 or the outer frame 8, or may be integrally formed on either or both of the inner frame 7 and the outer frame 8. Fig. 5(a) shows a structure in which the beam 20 is formed as shown in Fig. 5(b) regardless of the cross section. However, a part of the cross section may have a structure in which the beam 20 is not provided as shown in Fig. 3. Alternatively, the cross section having the beam 20 shown in Fig. 5(a) and the cross section having no beam 20 shown in Fig. 3 may be alternately formed in a plurality of layers. There are several types of beams 20, but the more heat, the easier it is to conduct from the inner frame to the outer frame, so the cooling effect is high.

Next, a third embodiment of the present invention will be described. Fig. 6 shows a modification of the structure of the holding frame of the electric motor according to the embodiment of the present invention. Fig. 6 is a perspective view showing the structure of the motor of the embodiment. The point different from the embodiment shown in FIGS. 1 to 3 is that the end bracket 21 that connects the inner casing 7 and the outer casing 8 is provided on the end surface of the motor. A gap 22 is provided in the terminal holder 21 to allow air to flow between the inner frame 7 and the outer frame 8. The inner frame 7 and the outer frame 8 are contacted by the terminal holder 21, whereby heat generated by the slotless motor 100 is easily transmitted to the outer frame 8. In this configuration, the air flowing through the inner frame 7 and the outer frame 8 and the end bracket 21 is cooled, whereby the slotless motor 100 can be cooled. The surface area cooled by the flowing air is wider than the embodiment of FIGS. 1 to 3, so the cooling effect is high. As the material of the terminal holder 21, a metal or a resin can be considered, and the metal cooling effect is high. The cross-sectional structure of Fig. 6 may have a structure in which the beam 20 is not provided as shown in Fig. 3, and the structure having the beam 20 as shown in Fig. 5(b) may be employed. Alternatively, the cross section having the beam 20 shown in FIG. 5(b) and the cross section having no beam 20 shown in FIG. 3 may be alternately formed in a plurality of layers. Although FIG. 6 shows only the structure in which the end bracket 21 is provided on one end surface, the terminal bracket 21 may be provided on both end surfaces. Further, the terminal holder 21 is configured to serve as a bearing housing, and the cooling effect of the bearing portion is also achieved.

Next, a fourth embodiment of the present invention will be described. Fig. 7 shows a modification of the structure of the holding frame of the electric motor according to the embodiment of the present invention. Fig. 7 is a perspective view and a partial cross-sectional view showing the structure of the motor of the embodiment. The point different from the embodiment shown in FIGS. 1 to 3 is a cross section of the upper half of the drawing, and does not have the inner frame 7 shown in FIG. 6(b), and the lower half of the drawing has a cross section of FIG. Or the structure of the inner frame 7 shown in Fig. 5 (b). With this configuration, the grooveless stator 51 can be held by the inner casing 7, and the outer coil 10 can be directly cooled by the flowing air, and the cooling effect is high. FIG. 6 shows a structure in which the inner frame 7 is divided into two stages, but the cross sections shown in FIG. 3, FIG. 5(b), and FIG. 6(b) may be randomly formed in multiple layers. Construction.

Next, a fifth embodiment of the present invention will be described. Fig. 8 shows a modification of the stator coil core strip structure and the holding frame structure of the motor according to the embodiment of the present invention. 8(a) and 8(b) are perspective views showing the structure of the motor of the present embodiment, wherein Fig. 8(a) shows the motor before assembly, and Fig. 8(b) shows the assembled motor. 8(c) is a cross-sectional view showing the structure of the motor of the embodiment. The point different from the embodiment shown in FIGS. 1 to 3 is that the stator coil core strip 6 is elongated outward in the radial direction and has the stator coil core strip convex portion 22 extending from the outer diameter of the stator coil 5. Further, the inner frame housing portion 7 has an inner frame recess portion 23 that is fitted to the stator coil core strip portion 22 inside. With this configuration, positioning and fixing of the slotless stator 51 and the inner casing 7 can be performed. Further, the stator coil core strip convex portion 22 is provided with a concave portion in a mold used for resin molding the grooveless stator 51, whereby it can be used for positioning and fixing at the time of resin mold molding.

Next, a sixth embodiment of the present invention will be described. In the end portion of the motor of any of the configurations shown in FIGS. 1 to 8, the impeller fixed to the shaft 2 is disposed, and the outer casing 8 has a function as a diffuser, whereby the impeller is provided. On the side, the air is forced to flow between the inner casing 7 and the diffuser as a structure of the electric blower. The cooling efficiency of the motor is improved by forcing air to flow between the inner frame 7 and the diffuser. As described above, the electric air blower of any of the first to sixth embodiments is used in an electric vacuum cleaner, whereby the electric vacuum cleaner can be reduced in size, weight, and efficiency. Moreover, since the motor blower has a short diameter, the degree of freedom in planning where the electric vacuum cleaner is disposed is high, for example, by being housed inside the hard pipe portion or the hose portion, a slim electric vacuum cleaner can be constructed. .

Further, as one of the first to sixth embodiments, a description has been given of a three-phase drive motor in which the number of poles of the magnet is four and the number of coils is twelve. However, the number of poles of the magnet may be considered to be two. The number of coils is 6, or the number of poles of the magnet is 6, the number of coils is 18, etc. For the natural number n, the number of poles of the magnet is 2n, and the number of coils is 6n. Further, the number of magnet poles is 2n, and the number of coils may be 12n or the like. An example in which the number of poles of the magnet is 2 and the number of coils is 12 is shown in FIG. In the case of this structure, as shown in Fig. 9, the adjacent coils may be in phase with each other. Further, it may be a single-phase drive motor in which the number of poles of the magnet is 2n and the number of coils is 2n.

1‧‧‧Rotor permanent magnet

1a‧‧‧Rotor permanent magnet N pole

2b‧‧‧Rotor permanent magnet S pole

2‧‧‧Axis

3‧‧‧Shield

4‧‧‧Segmented slotless stator core

5‧‧‧statar coil

6‧‧‧ Stator coil core strip

7‧‧‧ inside frame

8‧‧‧Outer frame

9‧‧‧Inside coil

10‧‧‧Outer coil

11‧‧‧Silker core

12‧‧‧ hollow

13‧‧‧Inside coil Ua

14‧‧‧Inside coil Ub

15‧‧‧Inside coil Uc

16‧‧‧Inside coil Ud

17‧‧‧ coil terminal

18‧‧‧Silker core

19‧‧‧ teeth

20‧‧ ‧ beams

21‧‧‧Terminal bracket

22‧‧‧ Stator coil core strip convex

23‧‧‧Inside frame recess

50‧‧‧Rotor

51‧‧‧Slotless stator

52‧‧‧ frame

61‧‧‧ Stator

100‧‧‧ slotless motor

101‧‧‧Electric motor

Fig. 1 (a) and (b) are perspective views of a motor according to an embodiment of the present invention. Fig. 2 is a part of a stator structure constituting an electric motor according to an embodiment of the present invention. Figure 3 is a cross-sectional view showing a motor according to an embodiment of the present invention. 4(a), 4(b) and 4(c) are a perspective view and a cross-sectional view showing a stator and an electric motor according to another aspect of the embodiment of the present invention. Fig. 5 (a) and (b) are a perspective view and a cross-sectional view showing a motor according to an embodiment of the present invention. Figure 6 is a perspective view of a motor according to an embodiment of the present invention. Fig. 7 (a) and (b) are a perspective view and a cross-sectional view showing a motor according to an embodiment of the present invention. Fig. 8 (a), (b) and (c) are a perspective view and a cross-sectional view showing a motor according to an embodiment of the present invention. Figure 9 is a cross-sectional view showing a motor according to an embodiment of the present invention.

Claims (9)

A slotless motor comprising: a hollow cylindrical core; a stator formed by a coil wound around the core; and a permanent magnet rotor facing the inner coil of the stator; The housing is rotatably disposed, and a frame that holds the stator and has a hollow inside is disposed outside the stator. A slotless motor comprising: a hollow cylindrical core; a stator formed by a coil wound around the core; and a permanent magnet rotor facing the inner coil of the stator; The outer side of the stator has an outer frame that holds the inner frame of the stator and is located outside the inner frame, and has a cavity between the inner frame and the outer frame. A slotless motor according to claim 2, comprising a plurality of beams that connect the inner frame to the outer frame. The slotless motor according to claim 2 or claim 3, wherein the end portion of the end portion of the slotless motor has a terminal bracket portion, and the terminal bracket portion is associated with the inner frame and the foregoing The void between the outer frames. The slotless motor of claim 2 or claim 3, wherein the end portion of the endless portion of the slotless motor has a terminal bracket portion, the terminal bracket portion having a connection with the inner frame and the foregoing The void between the outer frames. The slotless motor of claim 2 or claim 3, wherein the inner frame body is not included in a part of the cross-sectional structure. The slotless motor according to claim 2 or claim 3, wherein the coil is wound around a coil core strip, wherein the coil core strip has a convex portion on a radially outer side, and the inner frame body portion is in a radial direction The inner side has a concave portion, and the convex portion is fitted to the concave portion. An electric blower is a slotless motor according to any one of claims 2 to 7, characterized in that it has a single impeller fixed to the end of the permanent magnet rotor, and the outer frame portion is Diffuser. A motor cleaner is characterized in that the electric blower described in claim 8 is used.