TWI678053B - Slotless motor and electric blower or vacuum cleaner using the same - Google Patents

Abstract

[Problem] Provide a small and high-speed motor that improves the efficiency of the motor, and an electric blower or an electric vacuum cleaner using the same. [Solution] It has a hollow cylindrical core, a stator formed by winding a conductor coil around the core, and a permanent magnet rotor facing the inner coil of the stator and arranged to be rotatable. A frame body that holds the stator and is hollow inside is disposed outside the stator.

Description

Slotless motor and electric blower or vacuum cleaner using the same

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

In recent years, there has been a rapid increase in demand for wireless vacuum cleaners. In order to obtain sufficient output even with low-voltage battery driving, an electric blower using a brushless motor is mounted.

In order to meet the demand for miniaturization of electric vacuum cleaners, miniaturization of electric blowers has been sought. Regarding the miniaturization of the electric blower, it is possible to increase the speed of the electric blower to reduce the size of the fan. Therefore, there are many examples in which the number of rotations of the brushless motor is set to approximately 80,000 or more. As a structure of a brushless motor for a vacuum cleaner, a motor like the one disclosed in Patent Document 1 is mentioned. In the motor of Patent Document 1, a stator is constituted by winding a coil around a tooth portion protruding inward in the circumferential direction of a stator core. As a structure suitable for miniaturization and high speed of a brushless motor for a vacuum cleaner, there is a slotless structure having a tooth core on the stator side as disclosed in Patent Document 2 or Patent Document 3. The structure of Patent Literature 2 or Patent Literature 3 does not have a tooth core, so it is easy to shorten the diameter and reduce the iron loss. In addition, in Patent Document 2, an inner rotor is disposed inside the stator core and an outer rotor is disposed outside, thereby forming a dual-rotor structure, thereby increasing torque output. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2014-219006 [Patent Document 2] Japanese Patent Application Publication No. 5-116290 [Patent Literature 3] WO15 / 104795

[Problems to be Solved by the Invention]

However, due to the increase in speed of the motor, iron loss increases, which causes a decrease in the efficiency of the motor. In addition, by miniaturizing the motor, the heat generation in the vicinity of the volume increases and the heat dissipation area decreases, thereby increasing the temperature of the motor. Therefore, the copper loss increases due to the decrease in the residual magnetic flux density of the magnet or the increase in the coil resistance. Causes of reduced motor efficiency. In order to reduce the size of the electric motor of Patent Document 1, it is considered to shorten the teeth. To this end, it is necessary to reduce the number of turns of the coil or reduce the wire diameter of the coil, which may cause a reduction in the efficiency of the motor. However, the structures of Patent Documents 2 and 3 do not take into consideration the air-cooling of the motor. When the diameter is shortened, the motor cannot be sufficiently cooled, which may cause a reduction in the efficiency of the motor.

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

In order to solve the above-mentioned problems, the present invention is characterized by having a hollow cylindrical core, a stator including a coil of a conductor wound around the core, and a permanent magnet rotor including the inner coil of the stator. Opposingly, it is arranged to be rotatable, and a frame that holds the stator and is hollow inside is disposed outside the stator. [Effect of the invention]

According to the present invention, the motor is shortened in a slotless structure without a toothed core, and the coils wound around the stator core are moved by the inner coil to drive the motor, and the outer coil is used as a heat sink for heat radiation. By functioning, it is possible to obtain a small and high-speed motor with improved motor efficiency and an electric blower or electric vacuum cleaner using the same.

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

The motor shown in FIG. 1 is a so-called slotless motor. The structure of the slotless motor 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 includes a slotless stator 51, a rotor 50 disposed inside the slotless stator 51, and a frame 52 disposed outside the slotless stator 51. The rotor 50 includes a rotor permanent magnet 1 and a shaft 2. As a material of the rotor permanent magnet 1, a gadolinium-iron-nitrogen magnet, a neodymium magnet, a ferrite magnet, or the like can be considered. In addition, in order to prevent the magnet from being broken during high-speed rotation, the cover 3 may be used for protection. As a material of the shield 3, SUS, CFRP, or the like can be considered. FIG. 2 is a part of the slotless stator 51 during assembly. The slotless stator 51 includes a divided slotless stator core 4, a stator coil 5, and a stator coil core bar 6. The slotless stator 51 is obtained by winding a conductive stator coil 5 around the stator coil core bar 6 and inserting it into a plurality of divided slotless stator cores 4 to assemble the stator coil 5. In the divided slotless stator core 4 shown in FIG. 2, the cylindrical core is divided into two pieces, but the number of divisions may be several. In addition, after assembly, it may be considered to be fixed by resin molding. The frame body 52 is constituted by the inner frame body 7 and the outer frame body 8, and a hollow is formed between the inner frame body 7 and the outer frame body 8 and serves as a flow path of air. By having a slotless structure, a compact and high-speed structure suitable for a brushless motor for a vacuum cleaner can be achieved.

Fig. 2 is a sectional view of Fig. 1 (b). In an embodiment of the present invention, as shown in FIGS. 1 (b) and 2, when a current is passed to the stator coil 5, a cylindrical stator core 11 formed by dividing the slotless stator core 4 is assembled. The direction of the magnetic flux flowing in the circumferential direction of the magnetic field constitutes the stator coil 5. In addition, the stator coil 5 includes a U-phase coil, a V-phase coil, and a W-phase coil. Each of the currents flowing therethrough is a three-phase AC current whose phases are different from each other by 120 degrees. The rotor permanent magnet 1 shown in FIG. 3 is a 4-pole magnet arrangement, and the rotor permanent magnet N pole 1 a and the rotor permanent magnet S pole 1 b are arranged 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 an inner frame 7 when viewed in cross section. When the 1-section of the U-phase coil is located at the position of the inner coil Ua13, the inner coil Ub14 shifted by 90 degrees clockwise and the inner coil Ud16 shifted by 270 degrees, so that the currents in the same phase in the axial direction Flow in the opposite direction. And it is connected so that the inner coil Uc15 which is shifted 180 degrees from the inner coil Ua will cause currents of the same phase to 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 each shifted by 120 degrees. The UVW shown in FIG. 3 indicates that currents of the same phase flow, and +-indicates that the current flow direction is opposite in the axial direction. Coils of the same phase can also be connected in series or in parallel. With this arrangement, a rotating magnetic field is generated by the current flowing through the inner coil 9, and the rotor 50 is rotated to generate a 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 the outer coil 10 are connected at a coil terminal 17 and are connected to the pair of inner coils 9 and the outer coil 10 cause the same-phase current to flow in the axial direction in the opposite direction. The coil termination part 17 exists above the figure shown in the figure and below the figure not shown. The outer coil 10 does not contribute to the generation of torque, but is held by the inner frame 7, and a hollow is formed between the inner frame 7 and the outer frame 8 to serve as a flow path for air. The inner frame body 7 is cooled by the flowing air, thereby cooling the outer coil 10. The outer coil 10 is connected to the inner coil 9 at the coil terminal 17. Therefore, by cooling the outer coil 10, the inner coil 9 is also cooled, and the slotless motor 100 can be cooled from the inside. Although the outer coil 10 does not contribute to the generation of torque, it can be said to function as a heat sink. By reducing the temperature of the motor, the residual magnetic flux density of the magnet is increased and the coil resistance is reduced, thereby reducing the copper loss and improving the efficiency of the motor.

The slotless stator 51 is fixed to the inner housing 7 with, for example, resin bonding. The stator coil 5 has a high cooling effect when it comes into contact with the inner frame 7, but a resin or the like may be provided between the stator coil 5 and the inner frame 7. As a material of the inner frame body 7 and the outer frame body 8, a metal, a resin, or both of them can be considered, but the cooling effect is high when a metal is used.

As a material of the stator coil, copper or aluminum can be considered. In addition, as a material of the stator core, an electromagnetic steel plate whose main component is iron can be considered. As shown in FIG. 4, if instead of the slotless stator 51 of the embodiment, a stator 61 having a structure in which the number of coils 5 is wound around the teeth 19 of the stator core 18 having the teeth 19 is used, the inner frame The body 7 has a structure that holds 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 structure of this embodiment.

Next, a second embodiment of the present invention will be described. FIG. 5 shows a modified example of the holding frame structure of the electric motor according to an embodiment of the present invention. Fig. 5 is a perspective view and a cross-sectional view showing the structure of the motor of this embodiment. A point different from the embodiment shown in FIGS. 1 to 3 is that the inner frame 7 and the outer frame 8 are connected by the beam 20. The inner frame 7 and the outer frame 8 are connected by the beam 20, so that the heat generated by the slotless motor 100 can be easily conducted to the outer frame 8. With this structure, the slotless motor 100 can be cooled by cooling the air flowing through the inner frame body 7 and the outer frame body 8 and the beam 20. The surface area to be cooled by the flowing air is wider than that of the embodiment shown in FIGS. 1 to 3, so the cooling effect is high. As a material of the beam 20, a metal, a resin, or the like can be considered, and the cooling effect of the metal is high. The beam 20 may be assembled as a component different from the inner frame body 7 or the outer frame body 8, or may be integrally formed on one or both of the inner frame body 7 and the outer frame body 8. FIG. 5 (a) shows a structure having a beam 20 as shown in FIG. 5 (b) in any cross section, but a part of the cross section may have a structure without a beam 20 as shown in FIG. It is also possible to have a structure in which the cross section with the beam 20 shown in FIG. 5 (a) and the cross section without the beam 20 shown in FIG. 3 alternately appear over multiple layers. The number of beams 20 may be several, but the more the heat is more easily conducted from the inner frame to the outer frame, the higher the cooling effect is.

Next, a third embodiment of the present invention will be described. FIG. 6 shows a modified example of a holding frame structure of a motor according to an embodiment of the present invention. Fig. 6 is a perspective view showing the structure of the motor of this embodiment. A point different from the embodiment shown in FIGS. 1 to 3 is that the end face of the motor has a terminal bracket 21 that connects the inner frame 7 and the outer frame 8 to each other. A gap 22 is provided in the terminal bracket 21 to allow air to flow between the inner frame body 7 and the outer frame body 8. The inner frame body 7 and the outer frame body 8 are connected by the terminal bracket 21, so that the heat generated by the slotless motor 100 can be easily conducted to the outer frame body 8. In this structure, the slotless motor 100 can be cooled by cooling with air flowing through the inner frame body 7, the outer frame body 8, and the terminal bracket 21. The surface area to be cooled by the flowing air is wider than that of the embodiment shown in FIGS. 1 to 3, so the cooling effect is high. As a material of the terminal bracket 21, a metal, a resin, or the like can be considered, and a metal cooling effect is high. The cross-sectional structure in FIG. 6 may have a structure without a beam 20 as shown in FIG. 3, and a structure with a beam 20 as shown in FIG. 5 (b) may be used. It is also possible to have a structure in which the cross section with the beam 20 shown in FIG. 5 (b) and the cross section without the beam 20 shown in FIG. 3 alternately appear over multiple layers. Although FIG. 6 only shows the structure which has the terminal bracket 21 on the one end surface, you may have the terminal bracket 21 on both end surfaces. In addition, the terminal bracket 21 has a structure that doubles as a bearing seat, thereby also having a cooling effect on the bearing portion.

Next, a fourth embodiment of the present invention will be described. FIG. 7 shows a modification of the holding frame structure of a motor according to an embodiment of the present invention. FIG. 7 is a perspective view and a partial cross-sectional view showing the structure of the motor of this embodiment. The point different from the embodiment shown in Figs. 1 to 3 is the cross section of the upper half of the drawing, without the inner frame 7 shown in Fig. 6 (b), and the cross section of the lower half of the drawing has Fig. 3 Or the structure of the inner frame body 7 shown in FIG.5 (b). With this structure, the slotless stator 51 can be held by the inner frame 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 divided into two sections based on the presence or absence of the inner frame 7. However, the section shown in FIG. 3, FIG. 5 (b), and FIG. 6 (b) may appear randomly across multiple layers. The construction.

Next, a fifth embodiment of the present invention will be described. FIG. 8 shows a modified example of a stator coil core bar structure and a holding frame structure of a motor according to an embodiment of the present invention. 8 (a) and 8 (b) are perspective views showing the structure of the motor of the present embodiment, FIG. 8 (a) is a motor before assembly, and FIG. 8 (b) is a motor after assembly. 8 (c) is a sectional view showing the structure of the motor of this embodiment. The point different from the embodiment shown in FIGS. 1 to 3 is that the stator coil core bar 6 becomes longer toward the outside in the radial direction, and has a stator coil core bar protruding portion 22 protruding from the outer diameter of the stator coil 5. And the fact that the inner frame body 7 has an inner frame body recessed portion 23 fitted into the stator coil core bar convex portion 22. With this structure, the slotless stator 51 and the inner frame body 7 can be positioned and fixed. In addition, the stator coil core bar convex portion 22 is provided with a concave portion in a mold used for resin-molding the slotless stator 51, and thus can be used for positioning and fixing during resin-molding.

Next, a sixth embodiment of the present invention will be described. An impeller fixed to the shaft 2 is arranged at one end of the motor of any of the structures shown in Figs. 1 to 8 so that the outer frame body 8 has a structure functioning as a diffuser. On the other hand, a structure as an electric blower forcing air to flow between the inner frame 7 and the diffuser is forced. By forcing air to flow between the inner frame 7 and the diffuser, the cooling efficiency of the motor is improved. As described above, by using any of the electric blowers according to the first to sixth embodiments in the electric vacuum cleaner, the size and weight of the electric vacuum cleaner and the efficiency can be improved. Moreover, the electric motor blower has a short diameter, so it has a high degree of freedom in planning where to place it in the electric vacuum cleaner. For example, it can be formed into a slim electric vacuum cleaner by being housed inside a hard pipe section or a hose section. .

In addition, as any of the first to sixth embodiments, the description has been given in the case of a three-phase driving motor having four poles of magnets and twelve coils, but it may be considered that the number of poles of the magnets is 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 combination of the number of magnet poles is 2n and the number of coils is 6n. The number of magnet poles may be 2n, and the number of coils may be 12n. An example in which the number of poles of the magnet is 2 and the number of coils is 12 is shown in FIG. 9. When this structure is formed, as shown in FIG. 9, the adjacent coils may be made in pairs in phase. In addition, a single-phase drive motor having a number of poles of 2n and a number of coils of 2n may be used.

1: rotor permanent magnet 1a: rotor permanent magnet N pole 2b: rotor permanent magnet S pole 2: shaft 3: shroud 4: split slotless stator core 5: stator coil 6: stator coil core bar 7: inner frame body 8 : Outer frame 9: Inner coil 10: Outer coil 11: Stator core 12: Hollow 13: Inner coil Ua 14: Inner coil Ub 15: Inner coil Uc 16: Inner coil Ud 17: Coil terminal 18: Stator core 19: Tooth part 20: Beam 21: Terminal bracket 22: Stator coil core bar convex part 23: Inside frame recess 50: Rotor 51: Slotless stator 52: Frame 61: Stator 100: Slotless motor 101: Motor

1 (a) and 1 (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 a motor according to an embodiment of the present invention. 3 is a cross-sectional view of a motor according to an embodiment of the present invention. (4) (a), (b), and (c) of FIG. 4 are perspective views and cross-sectional views of a stator and a motor in another form for showing the superiority of one embodiment of the present invention. (A) and (b) of FIG. 5 are a perspective view and a sectional view of a motor according to an embodiment of the present invention. 6 is a perspective view of a motor according to an embodiment of the present invention. (A) and (b) of FIG. 7 are a perspective view and a sectional view of a motor according to an embodiment of the present invention. (A), (b) and (c) of FIG. 8 are a perspective view and a sectional view of a motor according to an embodiment of the present invention. 9 is a cross-sectional view of a motor according to an embodiment of the present invention.

Claims (7)

A slotless electric motor is characterized by having a hollow cylindrical core, a stator formed by winding a coil of a conductor around the core, and a permanent magnet rotor facing the inner coil of the stator, and It is rotatably arranged, and includes an inner frame that holds the stator, and an outer frame that is positioned outside the inner frame. The outer frame has a cavity between the inner frame and the outer frame. A part of the cross-sectional structure does not include the aforementioned inner frame. The slotless motor according to claim 1, further comprising a plurality of beams connecting the inner frame and the outer frame. The slotless motor according to claim 1 or claim 2, wherein a terminal support portion is provided on one side of an end portion of the slotless motor, and the terminal support portion has a connection to the inner frame and the The void space between the outer frames. The slotless motor according to claim 1 or claim 2, wherein a terminal support portion is provided on both sides of an end portion of the slotless motor, and the terminal support portion has a connection to the inner frame and the aforementioned The void space between the outer frames. The slotless motor according to claim 1 or claim 2, wherein the coil is wound around a coil core bar, the coil core bar has a convex portion on the outer side in the radial direction, and the inner frame body is on the inner side in the radial direction. It has a recessed part, and the said convex part and the said recessed part are fitted. An electric blower is a slotless motor according to any one of claim 1 to claim 5, characterized in that it has a unilateral impeller fixed to the end of the permanent magnet rotor, and the outer frame is Diffuser. A motor vacuum cleaner characterized by using the electric blower according to claim 6.