Electric motors and electric fans

Abstract

This electric motor (2) is provided with: a rotor (10) having a shaft (13) and a commutator (14) attached to the shaft (13); a brush (60) having a first end making contact with the commutator (14) and a second end positioned on the opposite side to the first end; a brush holder (70) for holding the brush (60); and a constant load spring (80) for pressing the brush (60) against the commutator (14). The constant load spring (80) has a coil portion (81) making contact with the second end of the brush (60) and an outside end (82) fixed to the brush holder (70).

Description

[Technical Field]

[0001] The present disclosure relates to electric motors and electric blowers. [Background technology]

[0002] The electric motors used in household vacuum cleaners include commutator motors with brushes (commutator motors) and brushless motors without brushes. Of these, brushless motors require electronic components and drive circuits, making the entire motor expensive. Therefore, studies are being conducted to improve the performance of vacuum cleaners by using commutator motors with brushes, which are less expensive than brushless motors.

[0003] In commutator motors, brush springs are used to press the brushes against the commutator. The brush springs apply pressure to the brushes by utilizing their spring elasticity. Conventionally, coil springs or torsion springs have been used as brush springs in commutator motors.

[0004] However, with coil springs or torsion springs, there is a large difference between the pressure (initial pressure) before the brush wears and the pressure (final pressure) after the brush wears, so the initial pressure must be set high to ensure a certain level of final pressure. As a result, in the initial stage, friction between the brush and the commutator increases when the rotor rotates, resulting in increased brush sliding loss. This results in reduced motor efficiency and a shorter brush life.

[0005] Therefore, a technique has been proposed in the past in which a constant-load spring is used as a brush spring in order to reduce the difference between the initial pressure and the final pressure and apply a uniform pressure (load) to the brush (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] CD-ROM of Japanese Utility Model Application No. 03-077375 (Japanese Utility Model Application Laid-Open No. 05-029268) Summary of the Invention [Problem to be solved by the invention]

[0007] However, the brush spring disclosed in Patent Document 1 requires two fixing points for fixing the brush spring, which poses a problem in that the brush spring cannot be fixed simply.

[0008] The present disclosure has been made to solve such problems, and aims to provide an electric motor, electric blower, etc. that can simply fix a constant force spring even when a constant force spring is used as a brush spring. [Means for solving the problem]

[0009] In order to achieve the above object, one aspect of the electric motor according to the present disclosure comprises a rotor having a shaft extending in an axial direction and a commutator attached to the shaft, a brush including a first end contacting the commutator and a second end located opposite the first end in a radial direction intersecting the axial direction, a brush holder that holds the brush so that the brush moves in the radial direction, and a constant force spring that presses the brush against the commutator, the constant force spring including a coil portion that contacts the second end included in the brush and an outer end fixed to the brush holder.

[0010] An aspect of an electric blower according to the present disclosure includes the electric motor described above and a rotary fan attached to the shaft of the electric motor. [Effects of the Invention]

[0011] Even when a constant force spring is used as the brush spring, the constant force spring can be fixed simply. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is a perspective view of an electric blower according to an embodiment, as viewed from above. [Figure 2] FIG. 2 is a perspective view of the electric blower according to the embodiment as viewed from below. [Figure 3] FIG. 3 is an exploded perspective view of the electric blower according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the electric blower according to the embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the electric blower according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view of the electric blower according to the embodiment taken along a plane that passes through the pair of brushes and is perpendicular to the axis of the shaft. [Figure 7] FIG. 7 is a perspective view of the brush holder in which the brushes, constant force springs, and conductive wires are housed, as viewed from the front. [Figure 8] FIG. 8 is a perspective view of the brush holder with the brushes, constant force springs, and conductive wires housed therein, as seen from the rear. [Figure 9] FIG. 9 is an exploded perspective view of the brush, the brush holder, the constant force spring, the conductive wires, and the electrode terminals. [Figure 10A] FIG. 10A is an enlarged perspective view of the front portion of the brush holder with the brushes and constant force springs housed therein. [Figure 10B] FIG. 10B is a cross-sectional perspective view of the front portion of the brush holder with the brushes and constant force springs housed therein. [Figure 11] FIG. 11 is a cross-sectional perspective view of the brushes and their surroundings in the electric blower according to the embodiment, taken along a plane that passes through the pair of brushes and is perpendicular to the axis of the shaft. [Figure 12] FIG. 12 is a diagram for explaining how the constant force spring is housed in the brush holder. [Figure 13] FIG. 13 is a diagram for explaining how the brushes wear in the electric blower according to the embodiment. [Figure 14]FIG. 14 is a diagram illustrating the length of the conductive wire connected to the brush in the electric blower according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, component placement positions, connection forms, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not recited in independent claims will be described as optional components.

[0014] In this specification and drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. The X-axis and Y-axis are perpendicular to each other and are also perpendicular to the Z-axis.

[0015] Note that each figure is a schematic diagram and is not necessarily a precise illustration. In each figure, substantially the same configuration is given the same reference numeral, and duplicated explanations are omitted or simplified. In this embodiment, the Z-axis direction is the direction of the axis C of the shaft 13.

[0016] (Embodiment) First, the overall configuration of an electric blower 1 according to an embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a perspective view of the electric blower 1 according to the embodiment as seen from above, and FIG. 2 is a perspective view of the electric blower 1 as seen from below. FIG. 3 is an exploded perspective view of the electric blower 1. FIGS. 4 and 5 are cross-sectional views of the electric blower 1 taken along a plane passing through the axis C of the shaft 13. FIG. 4 is a cross-sectional view (XZ cross-section) taken along a plane passing through a pair of brushes 60, and FIG. 5 is a cross-sectional view (YZ cross-section) taken along a plane passing through a pair of magnets 21 of the stator 20. Note that only cross-sections are shown in FIGS. 4 and 5. Airflow is indicated by arrows in FIGS. 4 and 5.

[0017] 1 to 5, electric blower 1 includes electric motor 2 having rotor 10 and stator 20, rotary fan 3 attached to shaft 13 of electric motor 2, air guide 4 into which air discharged from rotary fan 3 flows, and fan case 5 that houses rotary fan 3. Electric blower 1 can be used in, for example, an electric vacuum cleaner.

[0018] The electric motor 2 is a fan motor that rotates the rotary fan 3. As an example, the electric motor 2 is a DC motor that receives a DC power supply as input. In this embodiment, the electric motor 2 is a commutator motor with brushes.

[0019] Specifically, as shown in Figures 3 to 5, the electric motor 2 includes a rotor 10, a stator 20, a yoke 30, a frame 40, a bracket 50, brushes 60, a brush holder 70, and a constant force spring 80. The rotor 10, the stator 20, and the yoke 30 are arranged within the frame 40. The detailed configuration of each member of the electric motor 2 will be described later.

[0020] The rotary fan 3 draws air into an outer shell (housing) formed by the frame 40 and the fan case 5. As an example, the rotary fan 3 is a centrifugal fan that can generate high suction pressure. When the rotary fan 3 rotates, wind pressure is generated, and air is drawn in through the air intake 5c of the fan case 5 and discharged from the rotary fan 3. The air discharged from the rotary fan 3 flows into the air guide 4. The rotary fan 3 is made of, for example, a resin material or a metal material such as aluminum.

[0021] As an example, the rotary fan 3 has a first side plate with an intake port, a second side plate facing the first side plate across a predetermined gap, and a plurality of fan blades sandwiched between the first and second side plates. Each of the fan blades is a plate-like blade curved in an arc and arranged radially.

[0022] The air guide 4 has a function of forming an airflow path. For example, the air guide 4 straightens and discharges air drawn in through the air intake 5c of the fan case 5 by the rotation of the rotary fan 3. The air discharged from the air guide 4 flows into the interior of the frame 40 via the bracket 50. In this embodiment, the air discharged from the air guide 4 is not only discharged into the interior of the frame 40, but also discharged to the outside of the frame 40 via the bracket 50.

[0023] The air guide 4 has a main body 4a, a circular ring-shaped portion 4b that surrounds the main body 4a with a gap therebetween, and a plurality of connecting plates 4c that connect the main body 4a and the ring-shaped portion 4b. The gap between the main body 4a and the ring-shaped portion 4b serves as an air passage.

[0024] The main body 4a is a disk having a through hole for fixing to the center 51 of the bracket 50. The annular portion 4b functions as a support that supports the end of the side wall 5b of the fan case 5 in the direction of the axis C (thrust direction) of the shaft 13. Each of the multiple connecting plates 4c functions as a guide plate for forming an airflow path. Specifically, the multiple connecting plates 4c each have a plate shape that is curved in an arc and are arranged radially from the through hole of the main body 4a in a spiral outward. The air guide 4 is made of, for example, a resin material, but may also be made of a metal material.

[0025] The fan case 5 is a housing that houses the rotary fan 3. In this embodiment, the fan case 5 is a cover that covers the rotary fan 3 and the air guide 4. As an example, the fan case 5 is a metal cover made of a metal material, but it may also be a resin cover made of a resin material.

[0026] The fan case 5 has a lid 5a that covers the upper portions of the rotary fan 3 and the air guide 4, and sidewalls 5b that cover the sides of the rotary fan 3 and the air guide 4. The fan case 5 also has an air intake 5c (suction port) for drawing in outside air. In this embodiment, the air intake 5c is a circular through-hole provided in the center of the lid 5a.

[0027] Fan case 5 is fixed to bracket 50. In this embodiment, fan case 5 is fixed to bracket 50 via air guide 4. Note that a fan case spacer having an opening corresponding to intake port 5c may be attached to intake port 5c of fan case 5.

[0028] In electric blower 1 configured as described above, when rotor 10 of electric motor 2 rotates, rotary fan 3 rotates and air is drawn into fan case 5 through intake port 5c of fan case 5. This causes air to flow into rotary fan 3, and the air drawn into rotary fan 3 is compressed to a high pressure by fan blades of rotary fan 3 and discharged radially outward from the outer circumferential side of rotary fan 3. The air discharged from rotary fan 3 flows into air guide 4 along side wall 5b of fan case 5 and reaches bracket 50 through the ventilation passage of air guide 4.

[0029] Some of the air that reaches bracket 50 flows into frame 40 through bracket 50, passes through the inside of frame 40, and is discharged to the outside from exhaust port 40b of frame 40. In other words, the air that has flowed into frame 40 is discharged to the outside of electric blower 1 while cooling heat-generating components (windings, etc.) of electric motor 2.

[0030] Meanwhile, another portion of the air that reaches bracket 50 is discharged directly to the outside of electric blower 1 via bracket 50 without passing through the inside of frame 40. This allows the airflow to be discharged to the outside of electric blower 1 without incurring losses due to passing through the inside of frame 40.

[0031] Next, the detailed configuration of each member included in the electric motor 2 will be described with reference to FIGS.

[0032] 4 and 5, the rotor 10 is disposed inside the stator 20 with a small air gap between them. The rotor 10 rotates around the axis C of the shaft 13. The rotor 10 rotates at a high speed of, for example, 50,000 rpm.

[0033] The rotor 10 in this embodiment is an inner rotor, and is disposed inside the stator 20. Specifically, the rotor 10 is surrounded by the stator 20 with a minute air gap between them.

[0034] As an example, rotor 10 is an armature and includes rotor core 11 and winding coils 12 wound around rotor core 11 via insulators. Rotor 10 also includes shaft 13 and commutator 14. Note that in Figs. 3 to 5, winding coils 12 are shown schematically.

[0035] The rotor core 11 is a laminated body in which a plurality of electromagnetic steel sheets are stacked in the direction in which the axis C of the shaft 13 extends (the direction of the rotation axis). The rotor core 11 has a plurality of teeth. When a current flows through the winding coil 12, the rotor core 11 (rotor 10) generates a magnetic force that acts on the stator 20.

[0036] Shaft 13 is the axis of rotation when rotor 10 rotates, and extends in the longitudinal direction, which is the direction of axis C. Shaft 13 is fixed to the center of rotor 10. Shaft 13 is, for example, a metal rod, and is fixed to rotor core 11 in a state where it passes through rotor core 11. For example, shaft 13 is fixed to rotor core 11 by being press-fitted or shrink-fitted into the center hole of rotor core 11.

[0037] A first portion 13a of the shaft 13 protruding from the rotor core 11 to one side is supported by a first bearing portion 15. Meanwhile, a second portion 13b of the shaft 13 protruding from the rotor core 11 to the other side is supported by a second bearing portion 16. As an example, the first bearing portion 15 and the second bearing portion 16 are bearings that support the shaft 13. In this way, the shaft 13 is held by the first bearing portion 15 and the second bearing portion 16 in a freely rotatable state. The first bearing portion 15 is fixed to a bracket 50, and the second bearing portion 16 is fixed to the bottom of the frame 40. In other words, the bracket 50 is a first bracket, and the frame 40 is a second bracket.

[0038] In this embodiment, first portion 13a of shaft 13 protrudes from first bearing portion 15. Rotary fan 3 is attached to the tip of first portion 13a of shaft 13 protruding from first bearing portion 15.

[0039] The commutator 14 is attached to the shaft 13. Therefore, the commutator 14 rotates together with the shaft 13. In this embodiment, the commutator 14 is attached to the second portion 13b of the shaft 13. In other words, the commutator 14 is disposed on the side of the shaft 13 opposite to the rotary fan 3 side. Specifically, the commutator 14 is disposed between the rotor core 11 and the second bearing portion 16 on the shaft 13.

[0040] The commutator 14 is composed of a plurality of commutator segments 14a arranged in an annular shape so as to surround the shaft 13. The plurality of commutator segments 14a are insulated and separated from one another in the rotational direction of the shaft 13. Each of the plurality of commutator segments 14a is electrically connected to the winding coil 12.

[0041] Rotor 10 configured in this manner rotates due to the interaction between the magnetic flux generated in rotor core 11 (rotor 10) and the magnetic flux generated in stator 20.

[0042] As shown in Fig. 5, the stator 20 faces the rotor 10. Specifically, the stator 20 faces the rotor core 11 and is disposed on the radially outer periphery of the rotor core 11. In this embodiment, the stator 20 has a plurality of magnets 21 disposed at intervals around the circumferential direction of the rotor 10. The magnets 21 are field magnets that create magnetic flux for generating torque, and are, for example, permanent magnets having an S pole and an N pole. Each of the plurality of magnets 21 has an arc shape with a substantially uniform thickness when viewed from above.

[0043] In this embodiment, the stator 20 is composed of two magnets 21 that face each other across the rotor 10. A small air gap exists between the inner surface of each magnet 21 and the outer circumferential surface of the rotor 10 (rotor core 11). The magnets 21 are fixed to a yoke 30.

[0044] As shown in FIG. 5, the yoke 30 surrounds the magnet 21. The yoke 30 forms a magnetic circuit (field) together with the magnet 21. Therefore, the yoke 30 may be considered as part of the stator 20. The yoke 30 is cylindrical with a constant thickness and surrounds the rotor 10 and the stator 20 (magnet 21) entirely. The yoke 30 is made of a magnetic material such as iron. Specifically, the yoke 30 is made of an iron plate.

[0045] 3, in this embodiment, yoke 30 is a cylinder whose outer and inner peripheral shapes in a top view are generally oval (racetrack shaped), and has arc portions 31 and straight portions 32. By providing straight portions 32 in yoke 30 and making the cross-sectional shape of yoke 30 generally oval, the magnetic path can be made shorter than in a yoke with a circular cross-sectional shape (i.e., a cylindrical yoke), and loss in yoke 30 (magnetic path) can be reduced.

[0046] A pair of magnets 21 are arranged inside the arc portion 31 of the yoke 30. Specifically, each of the pair of magnets 21 has a shape that follows the inner peripheral surface of the arc portion 31, and is arranged so that the outer peripheral surface of the magnet 21 and the inner peripheral surface of the arc portion 31 are in close contact with each other.

[0047] As shown in FIGS. 1 to 3, the frame 40 is a housing (case) that houses components that constitute the electric motor 2, such as the rotor 10 and the stator 20. In this embodiment, the frame 40 is an outer shell (outer shell) of the electric blower 1 and the electric motor 2. The frame 40 is a cylindrical body with a bottom and an opening 40a. The yoke 30 housed in the frame 40 and the frame 40 are separate members. This allows the frame 40 and the yoke 30 to be made of different materials. Specifically, the yoke 30 is made of a magnetic material, while the frame 40 can be made of a non-magnetic material. This allows the frame 40 to be made of a lightweight and strong metal material. In this embodiment, the frame 40 is made of aluminum.

[0048] 1 to 5, a plurality of exhaust ports 40b are formed in each of the side wall and bottom of the frame 40 to discharge air sucked in by the rotation of the rotary fan 3. For example, a pair of opposing exhaust ports 40b is formed in the side wall of the frame 40, and a pair of opposing exhaust ports 40b is formed in the bottom of the frame 40.

[0049] 4 and 5, a gap G serving as a ventilation path in the direction of the axis C of the shaft 13 (the direction of the rotation axis) is formed between the outer surface of the yoke 30 and the inner surface of the frame 40. In this embodiment, a plurality of gaps G are formed.

[0050] As shown in FIGS. 1 to 3 , the frame 40 has a bulging portion 41, which is a portion of a side wall of the frame 40 that bulges outward in the radial direction (i.e., radially outward from the axis C). A gap G is a spatial region between the bulging portion 41 and the yoke 30. The bulging portion 41 extends in the direction in which the axis C of the shaft 13 extends (the direction of the rotation axis). Therefore, the gap G also extends in the direction in which the axis C of the shaft 13 extends. The bulging portion 41 also extends along the rotation direction of the shaft 13 (the rotation axis). Specifically, the bulging portion 41 extends in an arc shape along the rotation direction of the shaft 13. As an example, the bulging portion 41 is a rib formed in a protruding shape, and can be formed by, for example, pressing the side wall of the frame 40.

[0051] 4 and 5 , the bracket 50 covers the opening 40a of the frame 40. In the present embodiment, the bracket 50 does not completely block the opening 40a of the frame 40, but only partially covers the opening 40a of the frame 40. In other words, when the bracket 50 is attached to the frame 40, the air rectified by the air guide 4 flows into the frame 40.

[0052] Specifically, the bracket 50 is provided with a plurality of through holes as openings through which the air rectified by the air guide 4 passes. As shown in Figures 3 to 5, in this embodiment, the bracket 50 is provided with inner through holes 50a which are first through holes located radially inward, and outer through holes 50b which are second through holes located radially outward of the inner through holes 50a.

[0053] The bracket 50 also has a central portion 51 which is a portion including the center of the bracket 50, an inner annular portion 52 which is a first annular portion located radially outward from the central portion 51 and surrounding the central portion 51, and an outer annular portion 53 which is a second annular portion located radially outward from the inner annular portion 52 and surrounding the inner annular portion 52.

[0054] Furthermore, the bracket 50 has an inner bridge portion 54 (first bridge portion) that is a first bridge portion located radially inward, and an outer bridge portion 55 that is a second bridge portion located radially outward of the inner bridge portion 54. The inner bridge portion 54 separates two inner through holes 50a that are adjacent in the rotational direction of the shaft 13, and is bridged between the center portion 51 and the inner annular portion 52. In other words, the inner bridge portion 54 connects the center portion 51 and the inner annular portion 52 in a bridging manner. The outer bridge portion 55 separates two outer through holes 50b that are adjacent in the rotational direction of the shaft 13, and is bridged between the inner annular portion 52 and the outer annular portion 53. In other words, the outer bridge portion 55 connects the inner annular portion 52 and the outer annular portion 53 in a bridging manner.

[0055] The bracket 50 configured in this manner is fixed to the frame 40. For example, the bracket 50 and the frame 40 are fixed by joining the bracket 50 to a portion (recess) between two adjacent bulging portions 41 of the side wall portion of the frame 40. As an example, the bracket 50 and the frame 40 can be fixed by crimping them together.

[0056] Next, the brush 60, the brush holder 70, and the constant force spring 80 will be described with reference to FIGS. 3 and 4 and with reference to FIGS. 6 to 9. FIG. 6 is a cross-sectional view (XY cross-sectional view) of the electric blower 1 taken along a plane that passes through the pair of brushes 60 and is perpendicular to the axis C of the shaft 13. FIGS. 7 and 8 are perspective views of the brush holder 70 in which the brush 60, the constant force spring 80, and the conductive wire 91 are housed. FIG. 7 is a perspective view as seen from the front, and FIG. 8 is a perspective view as seen from the rear. FIG. 9 is an exploded perspective view of the brush 60, the brush holder 70, the constant force spring 80, the conductive wire 91, and the electrode terminal 92.

[0057] 4, the brush 60 is in contact with the commutator 14 in a radial direction intersecting the direction of the axis C. The brush 60 is pressed against the commutator 14 by receiving a pressing force from the constant force spring 80. Specifically, the brush 60 is provided so as to be movable in the radial direction about the shaft 13 as the center of rotation by the pressing force from the constant force spring 80 and to be able to slide against the commutator 14.

[0058] As shown in Fig. 6, a pair of brushes 60 are provided. The pair of brushes 60 are arranged opposite each other so as to sandwich the commutator 14. In other words, the pair of brushes 60 are arranged opposite each other with the commutator 14 between them. In this embodiment, the pair of brushes 60 are line-symmetrical with respect to the axis C of the shaft 13. Each of the pair of brushes 60 is an elongated member, and is arranged so that its longitudinal direction is the radial direction of rotation of the shaft 13. As an example, the brush 60 is an elongated, approximately rectangular parallelepiped.

[0059] The brushes 60 are power supply brushes that supply power to the rotor 10 by coming into contact with the commutator 14. Specifically, when the brushes 60 come into contact with the commutator segments 14a of the commutator 14, the armature current supplied to the brushes 60 flows through the commutator segments 14a to the winding coils 12 of the rotor 10. The brushes 60 are made of a conductive material. As an example, the brushes 60 are conductive carbon brushes made of carbon.

[0060] As shown in FIGS. 4 and 6, the brush 60 has a front end 61 which is a first end that contacts the commutator 14, and a rear end 62 which is a second end located opposite the front end 61.

[0061] The front end portion 61 of the brush 60 is one end portion in the longitudinal direction of the brush 60, and is the tip portion on the shaft 13 side (inner side) of the brush 60. The front end portion 61 has a front end surface 61a which is the contact surface that comes into contact with the commutator segments 14a of the commutator 14.

[0062] On the other hand, the rear end 62 of the brush 60 is the other end in the longitudinal direction of the brush 60, and is the tip end on the opposite side (outside) of the brush 60 from the shaft 13 side. The rear end 62 has a rear end surface 62a which is the contact surface that comes into contact with the constant force spring 80.

[0063] As shown in FIG. 4 , the brushes 60 are held by the brush holder 70 so as to move in a radial direction intersecting the direction of the axis C. In other words, the brush holder 70 is a holder that holds the brushes 60. The brush holder 70 is fixed to the frame 40. Specifically, the brush holder 70 is inserted into an opening provided in the frame 40 and fixed to the frame 40 by a screw 100. The brush holders 70 are arranged in accordance with the number of brushes 60. In this embodiment, two brushes 60 are arranged, and therefore two brush holders 70 are also arranged.

[0064] As shown in Figures 7 and 8, the brush holder 70 houses the brushes 60. Specifically, the brush holder 70 has through holes 71, and the brushes 60 are inserted into the through holes 71. The brush holder 70 is made of, for example, an insulating resin material. In this embodiment, the brush holder 70 is a resin-molded product formed by integral molding using a resin material.

[0065] The brush holder 70 also has a storage section 72 that stores the conductive wires 91. The storage section 72 is a recess (space) provided in the brush holder 70. The conductive wires 91 stored in the storage section 72 are covered by the insulating brush holder 70. This makes it possible to prevent poor insulation between the conductive wires 91 and peripheral components.

[0066] The conductive wire 91 is, for example, a pigtail wire, and as shown in FIGS. 8 and 9 , one end is connected to the brush 60 and the other end is connected to an electrode terminal 92. The conductive wire 91 is arranged so as not to be on the path of movement of the brush 60. Specifically, one end of the conductive wire 91 is connected to the side of the brush 60, and the conductive wire 91 is routed so as not to interfere with the brush 60 even if the brush 60 becomes worn due to sliding. This prevents the conductive wire 91 from interfering with the sliding of the brush 60. In this embodiment, the connection position between the conductive wire 91 and the brush 60 is always located forward of the contact position between the brush 60 and the constant force spring 80 and rearward of the fixed position between the brush holder 70 and the constant force spring 80, even if the brush 60 moves due to wear.

[0067] The length of the conductive wire 91 is set to be relatively long in consideration of movement of the brush 60 due to wear, but the storage section 72 has a structure for storing the conductive wire 91 so that the conductive wire 91 does not protrude from the brush holder 70 even before the brush 60 is worn. In other words, even if the brush 60 moves due to wear, the conductive wire 91 remains stored in the storage section 72 without protruding from the storage section 72. This makes it possible to prevent poor insulation between the conductive wire 91 and surrounding components even when the conductive wire 91 is slack in the early stages before the brush 60 is worn.

[0068] As shown in FIGS. 8 and 9 , electrode terminals 92 connected to conductive wires 91 are power supply terminals that receive power to be applied to the winding coils 12 of the rotor 10. In other words, the electrode terminals 92 provide power to the brushes 60. The power supplied to the electrode terminals 92 is supplied to the brushes 60 via the conductive wires 91 and then to the winding coils 12 of the rotor 10 via the commutator segments 14a. In this embodiment, the electrode terminals 92 are fixed to the brush holder 70. The electrode terminals 92 are also fixed to the brush holder 70 so as not to be on the path of movement of the brushes 60 along which they slide radially. This allows the brushes 60 to be longer than when the electrode terminals 92 are on the path of movement of the brushes 60, thereby extending the life of the electric motor 2.

[0069] 6, the brush holder 70 houses constant force springs 80. That is, the brush holder 70 holds not only the brushes 60 but also the constant force springs 80. In this embodiment, the constant force springs 80 are housed in the through holes 71. The constant force springs 80 are arranged in accordance with the number of brushes 60. In this embodiment, two brushes 60 are arranged, and therefore two constant force springs 80 are also arranged.

[0070] The constant force spring 80 is a brush spring for pressing the brush 60 against the commutator 14. Specifically, the constant force spring 80 applies pressure to the brush 60, thereby pressing the brush 60 against the commutator 14. The constant force spring 80 is a spring that applies a uniform pressure (load) to the brush 60. In this embodiment, the constant force spring 80 is a spiral spring having a portion where wire is wound in a spiral shape. The constant force spring 80 is, for example, a power spring made of a strip-shaped wire made of a metal material or the like.

[0071] As shown in Figures 6 and 9, the constant force spring 80 has a coil portion 81, which is a portion around which a strip-shaped wire is wound. Specifically, the coil portion 81 is a portion around which a long, strip-shaped metal plate is wound in only one direction. The constant force spring 80 also has an outer end portion 82, which is one end of the strip-shaped metal plate, and an inner end portion 83, which is the other end of the strip-shaped metal plate. The outer end portion 82 is the tip end on the outer periphery of the strip-shaped metal plate pulled out from the coil portion 81, and the inner end portion 83 is the tip end on the inner periphery of the strip-shaped metal plate located inside the coil portion 81.

[0072] The constant force spring 80 presses the brush 60 against the commutator 14 by the coil portion 81. Specifically, the coil portion 81 of the constant force spring 80 is in contact with the rear end portion 62 of the brush 60, and the spring elastic force (spring restoring force) of the coil portion 81 applies a pressing force (spring pressure) to the brush 60, thereby urging the brush 60 toward the commutator 14.

[0073] 6, the constant force spring 80 is housed in the brush holder 70. Specifically, the constant force spring 80 is disposed in the through-hole 71 of the brush holder 70 so that the coil portion 81 is located rearward of the rear end portion 62 of the brush 60. The outer end portion 82 of the constant force spring 80 is disposed in the through-hole 71 of the brush holder 70 so as to pass beside the brush 60 and be drawn out toward the commutator 14.

[0074] The constant force spring 80 is also fixed to the brush holder 70. Specifically, an outer end 82 of the constant force spring 80 is fixed to the brush holder 70. In this embodiment, the constant force spring 80 is fixed to the brush holder 70 by engaging the outer end 82 of the constant force spring 80 with the brush holder 70. Specifically, as shown in FIGS. 10A, 10B, and 11, the outer end 82 of the constant force spring 80 is provided with a notched recess 82a as a first engaging portion, and the brush holder 70 is provided with a protrusion 70a as a second engaging portion. With this configuration, the recess 82a formed in the constant force spring 80 and the protrusion 70a formed in the brush holder 70 are engaged with each other, thereby fixing the constant force spring 80 to the brush holder 70.

[0075] In this embodiment, the constant force spring 80 is fixed to the brush holder 70 only at the outer end 82, and the constant force spring 80 is not fixed anywhere other than the outer end 82. In other words, the constant force spring 80 is not supported and is free except at the outer end 82. In other words, the constant force spring 80 is supported at only one location, the outer end 82.

[0076] 7 and 9, the brush holder 70 is provided with an opening 73 through which the coil portion 81 of the constant force spring 80 can be inserted. The opening 73 is a through-hole provided in the side surface of the brush holder 70, and is connected to the through-hole 71 in which the brush 60 is disposed. The opening 73 has, for example, a rectangular shape, and extends along the longitudinal direction of the brush 60. By providing the opening 73 in the brush holder 70 in this way, the constant force spring 80 can be easily disposed within the brush holder 70.

[0077] Specifically, when the constant force spring 80 is installed inside the brush holder 70, as shown in Figure 12, the coil portion 81 of the constant force spring 80 is inserted into the brush holder 70 through the opening 73, and the recessed portion 82a of the constant force spring 80 is hooked onto the protruding portion 70a of the brush holder 70, thereby engaging the recessed portion 82a with the protruding portion 70a. This allows the constant force spring 80 to be placed inside the brush holder 70 with the outer end portion 82 fixed to the brush holder 70.

[0078] In the electric motor 2 configured as described above, the armature current supplied to the brushes 60 flows through the winding coils 12 of the rotor 10 via the commutator 14. This generates magnetic flux in the rotor 10, and the magnetic force generated by the interaction between the magnetic flux of the rotor 10 and the magnetic flux generated by the magnets 21 of the stator 20 becomes torque that rotates the rotor 10, causing the rotor 10 to rotate. The rotation of the rotor 10 then rotates the shaft 13, which in turn rotates the rotary fan 3 attached to the shaft 13.

[0079] As the rotor 10 rotates in this manner, the front ends 61 of the brushes 60 that come into contact with the commutator 14 wear. At this time, the brushes 60 are constantly pressed against the commutator 14 by a constant pressing force (load) from the constant force springs 80. As a result, as shown in FIG. 13 , as the front ends 61 of the brushes 60 wear due to friction with the commutator segments 14a, the brushes 60 slide toward the commutator 14 within the through holes 71 of the brush holder 70. At this time, the wire that makes up the constant force springs 80 is wound more as the brushes 60 become shorter due to wear. In other words, the coil portions 81 move closer to the outer ends 82.

[0080] 14, in this embodiment, the length of the conductive wire 91 is set so that the constant force spring 80 applies a pressing force to the brush 60 even when the brush 60 is at its maximum wear. Also, the length of the conductive wire 91 is set so that the brush 60 is positioned so that it receives the load of the constant force spring 80 from the initial position of the constant force spring 80 before the brush 60 is assembled.

[0081] This configuration ensures that the conductive wire 91 remains taut even when the brush 60 is completely worn. In other words, this configuration allows the brush 60 to slide as desired, and even if a gap exists between the brush 60 and the brush holder 70, vibration of the brush 60 can be suppressed. Therefore, the electric motor 2 according to this embodiment can suppress problems caused by vibration of the brush 60. Specifically, vibration of the brush 60 can cause the brush 60 to jump and temporarily separate from the commutator 14. When the brush 60 temporarily separates from the commutator 14, the current flowing from the brush 60 to the commutator 14 is interrupted, resulting in problems such as sparks. However, this configuration stabilizes the behavior of the brush 60. In other words, the conductive wire 91 according to this embodiment has both the function of supplying power to the brush 60 and the function of stably holding the brush 60.

[0082] Furthermore, by setting the length of the conductive wire 91 as described above, the constant force spring 80 can constantly apply pretension to the brush 60 by utilizing the spring properties of the constant force spring 80. Therefore, a reaction force from the brush 60 is applied to the constant force spring 80, which can prevent the constant force spring 80 from coming off the brush holder 70. This configuration not only prevents the constant force spring 80 from coming off when the electric motor 2 is running, but also prevents the constant force spring 80 from coming off when the electric motor 2 is assembled. In other words, the electric motor 2 according to this embodiment can prevent the constant force spring 80 from coming off from the time the electric motor 2 is assembled until the end of the life of the brush 60.

[0083] As described above, in the electric motor 2 and electric blower 1 according to this embodiment, the constant force spring 80 is used as the brush spring for pressing the brush 60 against the commutator 14. This allows a constant load to be applied to the brush 60, so the initial pressure of the brush spring can be set small. Therefore, it is possible to prevent the friction between the brush 60 and the commutator 14 from increasing in the initial stage, which would result in an increase in sliding loss of the brush 60. Therefore, by using the electric motor 2 according to this embodiment, it is possible to prevent a decrease in the efficiency and lifespan of the electric motor 2.

[0084] Moreover, in the electric motor 2 and electric blower 1 according to this embodiment, the constant force spring 80 used as a brush spring has a coil portion 81 that contacts the rear end portion 62 (second end portion) of the brush 60, and an outer end portion 82 that is fixed to the brush holder 70. This allows the constant force spring 80 to be supported at a single location, the outer end portion 82. Therefore, even when the constant force spring 80 is used as a brush spring, the constant force spring 80 can be simply fixed to the brush holder 70.

[0085] In this embodiment, the constant force spring 80 is fixed to the brush holder 70 by having the outer end 82 of the constant force spring 80 engage with the brush holder 70 .

[0086] This allows the constant force spring 80 to be simply secured to the brush holder 70 .

[0087] Specifically, a notched recess 82a is provided at the outer end 82 of the constant force spring 80, and a protrusion 70a is provided on the brush holder 70 to engage with the recess 82a.

[0088] As a result, the recessed portion 82a of the constant force spring 80 and the protruding portion 70a of the brush holder 70 are hooked and locked together, so that the constant force spring 80 can be fixed to the brush holder 70.

[0089] (Variation) The electric motor 2 and the electric blower 1 according to the present disclosure have been described above based on the embodiments, but the present disclosure is not limited to the above-described embodiments.

[0090] For example, in the above embodiment, as an example of a locking structure for locking and fixing the brush holder 70 and the constant force spring 80, a protrusion 70a is provided on the brush holder 70 and a notched recess 82a is provided on the outer end 82 of the constant force spring 80, but this is not limiting. For example, a recess may be provided on the brush holder 70 and a protrusion may be provided on the outer end 82 of the constant force spring 80, and the outer end 82 of the constant force spring 80 may be fixed to the brush holder 70 by locking these recesses and protrusions together.

[0091] Furthermore, instead of a locking structure in which a notched recess and a protrusion are engaged, a locking structure in which a through-hole and a protrusion are engaged may be used. For example, a protrusion may be provided on the side of the brush holder 70, and a through-hole may be provided in the outer end 82 of the constant force spring 80, and the protrusion of the brush holder 70 may be engaged in the through-hole of the constant force spring 80, thereby fixing the outer end 82 of the constant force spring 80 to the brush holder 70.

[0092] Furthermore, the method of fixing the constant force spring 80 and the brush holder 70 is not limited to an engagement structure, and the brush holder 70 and the outer end 82 of the constant force spring 80 may be fixed by a method other than an engagement structure.

[0093] In the above embodiment, the stator 20 is formed by the magnet 21, but this is not limiting. For example, the stator 20 may be formed by a stator core and a winding coil wound around the stator core. In this case, a yoke portion is formed on the stator core, and the yoke 30 functions as an auxiliary yoke.

[0094] In the above embodiment, the electric blower 1 is described as being used in an electric vacuum cleaner, but the invention is not limited to this. For example, the electric blower 1 may be used in an air towel or the like.

[0095] In the above embodiment, the electric motor 2 is used in the electric blower 1, but the present invention is not limited to this, and the electric motor 2 may be used in electrical equipment other than the electric blower 1. Furthermore, the electric motor 2 is not limited to being used in household equipment, and may be used in industrial equipment such as automotive equipment.

[0096] In addition, this disclosure also includes forms obtained by making various modifications to the above embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions in the embodiments within the scope of the present disclosure. [Industrial Applicability]

[0097] The electric motor and electric blower of the present disclosure can be used in a variety of electric appliances, including household electric appliances such as electric vacuum cleaners. [Explanation of symbols]

[0098] 1 electric blower 2 electric motor 3 Rotating Fan 4 Air Guide 4a Main body 4b Annular part 4c connecting plate 5 Fan case 5a Lid 5b Side wall part 5c Air intake 10 rotor 11 Rotor core 12 winding coil 13 Shaft 13a Part 1 13b 2nd part 14 Commutator 14a Commutator piece 15 First bearing part 16 Second bearing part 20 Stator 21 Magnet 30 York 31 Arc section 32 Straight section 40 frames 40a opening 40b Exhaust port 41 Bulge 50 bracket 50a inner through hole 50b Outer through hole 51 Center 52 Inner annular part 53 Outer annular part 54 Inner bridge section 55 Outer bridge section 60 brushes 61 Front end 61a Front end surface (first end) 62 Rear end 62a Rear end surface (second end) 70 Brush holder 70a convex part 71 Through hole 72 Storage area 73 Opening 80 constant force spring 81 Coil section 82 Outer edge 82a Recess 83 Inner end 91 Conductive wire 92 Electrode terminal 100 screws

Claims

1. a rotor having an axially extending shaft and a commutator attached to the shaft; a brush including a first end portion in contact with the commutator and a second end portion located on the opposite side of the first end portion in a radial direction intersecting the axial direction; a brush holder for holding the brush so that the brush moves in the radial direction; a constant force spring for pressing the brush against the commutator; an electrode terminal for providing power to the brush; the constant force spring includes a coil portion contacting the second end of the brush and an outer end fixed to the brush holder; the electrode terminal is fixed to the brush holder so as not to be on a path of movement of the brush in the radial direction; a clamping structure is provided on a side surface of the brush holder to clamp the tip of the outer end of the constant force spring in the thickness direction of the outer end, The constant force spring has an outer end portion provided with a notched recess, The brush holder has a side surface provided with a protrusion that engages with the recess, an opening through which the coil portion of the constant force spring can be inserted is provided on the side surface of the brush holder; Electric motor.

2. The electric motor further includes a conductive wire having one end connected to the brush and the other end connected to the electrode terminal, The length of the conductive wire is set so that the constant force spring applies a pressing force to the brush even when the brush is worn, and so that the brush is positioned at a position where it receives the load of the constant force spring from the initial position of the constant force spring before the brush is assembled.

2. The electric motor according to claim 1.

3. Further, the device has a conductive wire whose one end is connected to the brush and whose other end is connected to the electrode terminal, The conductive wire is connected to one of the four side surfaces of the brush that is perpendicular to the axial direction of the shaft.

2. The electric motor according to claim 1.

4. The constant force spring is fixed to the brush holder by engaging the outer end of the constant force spring with the brush holder.

2. The electric motor according to claim 1.

5. the brush holder has a housing portion for housing the conductive wire, The conductive wire is arranged so as not to be on a path of movement of the brush in the radial direction.

3. The electric motor according to claim 2.

6. The storage portion has a structure for storing the conductive wire so that the conductive wire does not protrude from the brush holder before the brush is worn.

6. The electric motor according to claim 5.

7. The constant force spring is a spiral spring having a portion around which a strip-shaped wire is wound as the coil portion. The electric motor according to any one of claims 1 to 6.

8. An electric motor according to any one of claims 1 to 7; a rotary fan attached to the shaft of the electric motor, Electric blower.

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