Brushless motors and power tools

Abstract

A brushless motor and an electric tool capable of improving coil cooling efficiency are provided. The brushless motor (1) is an inner rotor type brushless motor having a plurality of multi-phase phase coils (U1-U3, V1-V3, W1-W3) arranged around a rotation axis (C1). The brushless motor (1) has a plurality of terminals (8), and the phase coils (U1-U3, V1-V3, W1-W3) are connected to a switching circuit (600) via the plurality of terminals (8). The plurality of terminals (8) are arranged inside a circumscribed circle (C2) of the phase coils (U1-U3, V1-V3, W1-W3).

Description

Technical Field

[0001] The present disclosure relates to a brushless motor and a power tool, and more particularly to a brushless motor and a power tool including a cooling mechanism. Background Art

[0002] A cooling mechanism for a motor is known (see Patent Document 1).

[0003] According to the disclosure of Patent Document 1, a rotor and a stator are arranged in a motor housing, and a motor cooling air path is formed in the motor housing to allow cooling wind to flow to at least one of the rotor and the stator. In addition, a retaining member provided with a drive circuit is mounted on the motor housing on one side in the direction of the rotor rotation axis. The circuit cooling air path is formed to allow cooling wind to flow to the drive circuit of the retaining member. The circuit cooling air path and the motor cooling air path are formed to be connected to each other. A fan is arranged in a connecting path connecting the cooling air path. The fan is configured to rotate together with the rotation of the rotor to generate cooling wind flowing through the cooling air path.

[0004] According to the cooling mechanism for the motor of Patent Document 1, the motor and the circuit are assembled together. Therefore, it is possible to provide a motor capable of effectively cooling the motor itself and cooling the drive circuit with fewer parts without increasing the overall size.

[0005] However, the cooling wind only passes through the gap between the rotor and the stator, and cannot directly cool the coils that are heated by the current flowing therethrough. Therefore, the cooling effect is not sufficient.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2007-318885 Summary of the invention

[0009] The present disclosure has been achieved in view of the above problems, and an object of the present disclosure is to provide a brushless motor and an electric power tool having improved coil cooling efficiency.

[0010] A brushless motor according to one aspect of the present disclosure is an inner rotor type brushless motor. The brushless motor includes a plurality of multi-phase phase coils arranged around a rotation axis and a plurality of terminals configured to connect the plurality of multi-phase phase coils to a switching circuit. The plurality of terminals are located inside the circumscribed circle of the plurality of multi-phase phase coils.

[0011] An electric power tool according to one aspect of the present disclosure includes the aforementioned brushless motor and a housing accommodating the aforementioned brushless motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 11 is a schematic diagram showing an electric power tool according to an embodiment.

[0013] Figure 2 1 is a schematic diagram showing a brushless motor and a housing according to this embodiment.

[0014] Figure 3 : is a schematic diagram showing the brushless motor of this embodiment.

[0015] Figure 4 Schematic diagram showing the internal mechanism of the brushless motor according to this embodiment.

[0016] Figure 5 It is an exploded perspective view of the brushless motor according to this embodiment.

[0017] Figure 6 It is a top view of the brushless motor of this embodiment.

[0018] Figure 7 is a cross-sectional view taken along line AA of the brushless motor of this embodiment. DETAILED DESCRIPTION

[0019] The embodiments and modifications described below are merely examples of the present disclosure. The present disclosure is not limited to the embodiments and modifications described below. As long as the purpose of the present disclosure is achieved, various modifications may be made to the following embodiments and modifications according to design, etc.

[0020] (First Embodiment)

[0021] Reference Figures 1 to 7 A brushless motor 1 and an electric power tool 10 according to the present embodiment will be described.

[0022] (1) Overview

[0023] like Figure 1 and Figure 2 As shown, the electric tool 10 includes a brushless motor 1 and a housing 11 for accommodating the brushless motor 1. Figure 1 As shown, the power tool 10 further includes a power source 101, a driving force transmission unit 102, an output unit 103, a chuck 104, an end tool 105, a trigger 106, and a control circuit 107. The power tool 10 is a tool configured to drive the end tool 105 using the driving force of the brushless motor 1.

[0024] The brushless motor 1 is a driving source for driving the end tool 105. The power supply 101 includes a DC power supply for supplying current to drive the brushless motor 1. The power supply 101 includes, for example, one or more secondary batteries. The driving force transmission unit 102 is configured to adjust the output (driving force) of the brushless motor 1 and supply the adjusted driving force to the output unit 103. The output unit 103 is configured to be driven (e.g., rotated) by the driving force supplied from the driving force transmission unit 102. The chuck 104 is fixed to the output unit 103. The end tool 105 is removably mounted to the chuck 104. Examples of the end tool 105 (drill) include a screwdriver, a socket, and a drill bit. One of these various types of end tools 105 is selected according to the intended use and is mounted to the chuck 104 for use. Therefore, the end tool 105 of the power tool 10 is rotatable.

[0025] The trigger 106 is configured to receive an operation to control the rotation of the brushless motor 1. The brushless motor 1 switches ON or OFF according to the operation given to the trigger 106. When the trigger 106 receives a pulling operation in the OFF state of the brushless motor 1, the brushless motor 1 switches from the OFF state to the ON state. When the pulling operation given to the trigger 106 is released in the ON state of the brushless motor 1, the brushless motor 1 switches from the ON state to the OFF state. In addition, the rotation speed of the brushless motor 1 is adjusted according to the pulling amount of the trigger, thereby adjusting the rotation speed of the output unit 103. According to the operation given to the trigger 106, the control circuit 107 starts or stops rotating the brushless motor 1, and also controls the rotation speed of the brushless motor 1. In this electric tool 10, the end tool 105 is mounted to the chuck 104. The rotation speed of the brushless motor 1 is controlled according to the operation given to the trigger 106, thereby controlling the rotation speed of the end tool 105.

[0026] The power tool 10 of this embodiment includes a chuck 104 that allows the end tool 105 to be replaced according to the intended use, but is not limited thereto. The end tool 105 does not have to be replaceable. Alternatively, the power tool 10 can be designed to allow the user to use only a specific type of end tool 105.

[0027] (2) Structure

[0028] Will refer to Figures 2 to 7The structure of the brushless motor 1 is described. The brushless motor 1 can be, for example, a six-pole, nine-slot three-phase brushless motor. "Pole" refers to the number of magnetic poles of the permanent magnet 21 of the rotor 2. The N pole and the S pole are paired with each other. When the number of magnetic poles is counted, one permanent magnet used as an N pole is counted as "one" pole, and one permanent magnet used as an S pole is also counted as "one" pole. In the present embodiment, the brushless motor is a six-pole motor and therefore includes three permanent magnets using its N pole and three permanent magnets using its S pole. "Slot" refers to the number of coils 32. "Three-phase motor" refers to a motor including three coils whose phases are offset by 120 degrees from each other.

[0029] The brushless motor 1 is an inner rotor type brushless DC motor. Figure 5 As shown, the brushless motor 1 includes a rotor 2, a stator 3, a sensor substrate 4, an insulator 5 (coil frame) and a substrate 6. The brushless motor 1 also includes a first bearing 14, a second bearing 16, a fan 15, a plurality of multi-phase (for example, three-phase in the present embodiment) phase coils U1 to U3, V1 to V3 and W1 to W3, a plurality of terminals 8 and a plurality of retaining members 507.

[0030] (2-1) Shell

[0031] like Figure 2 As shown, the housing 11 is an outer cylinder for accommodating the brushless motor 1. The housing 11 has a cylindrical shape centered on the rotation axis C1. The housing 11 includes a first frame body 114 and a second frame body 115. The housing 11 has an exhaust port 12 and an air inlet 13. Through the air inlet 13, external air is introduced according to the operation of the fan 15 of the brushless motor 1 to cool the coil 32 of the brushless motor 1. Through the exhaust port 12, the intake air is discharged together with the heat. The air flows from the second substrate side to the fan 15 side.

[0032] (2-2) Rotor

[0033] The rotor 2 includes a cylindrical rotor core 22, a plurality of (for example, Figure 5 The output shaft 20 is coaxially held inside the rotor core 22 with the rotation axis C1 as a common axis with the rotor core 22. The plurality of permanent magnets 21 are respectively fitted into a plurality of holes 23 formed in the rotor core 22. The plurality of permanent magnets 21 are arranged in a polygonal shape (e.g., Figure 5 On the corresponding sides of the hexagon in the example shown).

[0034] The rotor core 22 has a circular shape when viewed along the rotation axis C1 of the rotor core 22. The "center of the rotor core 22" corresponds to the center of the circle.

[0035] The rotor core 22 includes a plurality of steel plates. The rotor core 22 is formed by stacking a plurality of steel plates one on top of another in a thickness direction. Each steel plate is made of a magnetic material (for example, may be a silicon steel plate).

[0036] The output shaft 20 is held inside the rotor core 22. Figure 5 As shown, the rotor core 22 has an axial hole 221 for the output shaft 20 to pass through. The rotor core 22 can rotate relative to the stator 3 together with the output shaft 20. The rotor core 22 is configured to rotate according to the magnetic field generated by the current flowing through the plurality of coils 32 of the stator 3. That is, the rotor core 22 has permanent magnets 21, is configured to rotate according to the magnetic field of the permanent magnets 21 and the magnetic field generated by the current flowing through the coils 32 of the stator 3, and transmits the generated torque to the output shaft 20. The material of the rotor core 22 may be iron, for example. The core of the rotor core 22 may be made of silicon steel containing silicon, permalloy, ferrite, etc., for example. The rotor core 22 may be made of an alloy containing iron, nickel, copper, carbon, etc. to have high strength so as to transmit the generated torque to the output shaft 20.

[0037] For example, each permanent magnet 21 may be a neodymium magnet. Both magnetic poles of each permanent magnet 21 are positioned along the circumference of the rotor core 22. Each permanent magnet 21 is magnetized in the radial direction. Two permanent magnets 21 adjacent to each other along the circumference of the rotor core 22 are configured in such a way that their magnetic poles are different from each other. In other words, the plurality of permanent magnets 21 are configured so that the N poles and the S poles appear alternately along the periphery of the plurality of permanent magnets 21.

[0038] (2-3) Stator

[0039] The stator 3 includes a plurality of (for example, 9 in the illustrated example) coils 32, a stator core 34, and an insulator 5. The stator 3 includes a coil unit 9, which includes a plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3, and a plurality of coil terminals 801. The plurality of coil terminals 801 correspond one-to-one to the plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3, and allow current to flow through the plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3. The plurality of coils 32 correspond one-to-one to the phase coils U1 to U3, V1 to V3, and W1 to W3. In the present embodiment, when starting from the phase coil W1, the phase coils are arranged counterclockwise in the order of W1, V1, U1, W2, V2, U2, W3, V3, and U3.

[0040] The rotor 2 is arranged inside the stator core 31 to be spaced apart from the plurality of teeth portions 35. The rotor 2 is configured to rotate about a central axis of the yoke 30 as a rotation axis C1.

[0041] The stator core 34 includes a stator core 31 and a yoke 30. The yoke 30 is mounted on the stator core 31. Figure 5 As shown, the stator core 31 includes a cylindrical coupling portion 33 and a plurality of (eg, Figure 6 9) teeth 35 of the example shown. The rotor 2 is arranged in the space 36 inside the coupling portion 33. Each of the plurality of teeth 35 includes a body portion 351 and two end pieces 352. The body portion 351 protrudes outward from the coupling portion 33 in the radial direction of the coupling portion 33. Each of the two end pieces 352 extends from the end portion of the body portion 351 in a direction intersecting with the protruding direction of the body portion 351.

[0042] The coupling portion 33 couples at least some of the plurality of teeth 35 arranged in parallel.

[0043] The plurality of teeth portions 35 protrude from the inner peripheral surface of the yoke portion 30. The plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3 are provided to the plurality of teeth portions 35 one to one.

[0044] The plurality of coils 32 are respectively provided to the plurality of teeth 35 via the insulator 5. The coil 32 is wound around the body portion 351 via the insulator 5. The coupling portion 33 is located closer to the rotor 2 than the coil 32. In other words, the coupling portion 33 is located between the coil 32 and the rotor 2.

[0045] The plurality of teeth 35 may be separable. The separable teeth 35 allow each coil 32 to be wound around the corresponding tooth 35 with the teeth 35 separated, after which the stator core 31 may be formed. This may increase the space factor of the winding, reduce copper loss, and improve the efficiency of the brushless motor 1. The "space factor" means the ratio of the area occupied by the copper wiring to the area of ​​the space in which the copper wiring is wound.

[0046] The two end pieces 352 are provided as stoppers to prevent the coil 32 from being separated from the body portion 351. The coil 32 moving toward the end portion of the body portion 351 will be caught on the two end pieces 352. The end pieces 352 can thus prevent the coil 32 from being separated.

[0047] The stator core 31 of the stator iron core 34 of the stator 3 includes a plurality of steel members. The stator core 31 is formed by stacking a plurality of steel plates one on top of another in the thickness direction. Each steel plate is made of a magnetic material and may be, for example, a silicon steel plate.

[0048] like Figure 5 As shown, the connecting portion 33 is cylindrical. The axis of the connecting portion 33 is consistent with the thickness of the plurality of steel plates. The connecting portion 33 is continuous along its circumference. In other words, the connecting portion 33 is continuous along its circumference without being disconnected.

[0049] like Figure 5 As shown, the body portion 351 of each tooth portion in the plurality of tooth portions 35 is a rectangular parallelepiped. The coupling portion 33 and the tooth portion 35 are formed integrally. The body portion 351 protrudes outward from the coupling portion 33 along the radial direction of the coupling portion 33. The body portions 351 of the plurality of tooth portions 35 are arranged at equal intervals along the circumferential direction of the coupling portion 33.

[0050] Each of the two end pieces 352 extends from the end portion of the body portion 351 in a direction intersecting with the direction in which the body portion 351 protrudes. Specifically, the two end pieces 352 are provided at both sides along the circumferential direction of the coupling portion 33 at the end portion of the body portion 351. The two end pieces 352 extend along the circumferential direction of the coupling portion 33.

[0051] The yoke 30 includes a plurality of steel plates. The yoke 30 is formed by stacking a plurality of steel plates one on top of another in the thickness direction. Each steel plate is made of a magnetic material and may be, for example, a silicon steel plate. The yoke 30 is cylindrical. The yoke 30 is mounted on and surrounds a plurality of teeth 35.

[0052] like Figure 5 As shown, the yoke 30 has a plurality of (for example, 9) engaging portions 301 on the inner periphery of the yoke 30. The number of the engaging portions 301 of the yoke 30 is the same as the number of the tooth portions 35. Each of the plurality of engaging portions 301 includes a recessed portion provided in the inner peripheral surface of the yoke 30. The plurality of engaging portions 301 corresponds to the plurality of tooth portions 35 one-to-one. By moving at least one of the engaging portions 301 and the tooth portions 35 along the radial direction of the coupling portion 33, each of the engaging portions 301 and one of the tooth portions 35 corresponding to the engaging portion 301 in question engage with each other. This enables the yoke 30 to be mounted on the plurality of tooth portions 35.

[0053] The portion of the associated tooth portion 35 including the two end pieces 352 is fitted to each fitting portion 301. Therefore, the length of each fitting portion 301 measured along the circumferential direction of the yoke portion 30 is equal to the length measured from the protruding end of one of the two end pieces 352 protruding from the body portion 351 to the protruding end of the other of the two end pieces 352. As used herein, if one value is "equal to" another value, the two values ​​do not have to be strictly equal to each other, but may also be different from each other within a tolerance range. The tolerance range may be defined, for example, by an error within 3%, within 5%, or within 10%.

[0054] With the insulator 5 mounted on the stator core 31 and the coil 32 wound around the stator core, the yoke 30 can be mounted on the plurality of teeth 35, for example, by shrink-fitting. Specifically, the yoke 30 is heated and radially expanded, and then the stator core 31 is placed inside the yoke 30. This causes the inner surface of the yoke 30 to face the corresponding ends of the plurality of teeth 35 along the radial direction of the coupling portion 33 with a narrow gap between the inner surface of the yoke 30 and the plurality of teeth 35. Thereafter, as the temperature of the yoke 30 drops to shrink the yoke 30, the inner surface of the yoke 30 contacts the corresponding ends of the plurality of teeth 35. That is, when the plurality of engaging portions 301 move radially inwardly of the yoke 30 as the yoke 30 shrinks, the plurality of engaging portions 301 and the plurality of teeth 35 engage with each other. The yoke 30 applies a contact pressure generated radially inwardly of the yoke 30 to the plurality of teeth 35.

[0055] The insulator 5 is a member having electrical insulating properties. For example, the insulator 5 may be made of a resin such as nylon 66, and may include 30% by weight of a filler such as glass fiber.

[0056] The insulator 5 is fixed to the end surface in the direction of the rotation axis (rotation axis direction X) of the stator core 31. The sensor substrate 4 is fixed to the stator 3 using the insulator 5. This can electrically insulate the stator 3 and the sensor substrate 4 from each other.

[0057] like Figure 5 As shown, the insulator 5 includes a first insulator 51 and a second insulator 52. The first insulator 51 and the second insulator 52 can be formed integrally with the stator core 34 of the stator 3 by insert molding, for example. The first insulator 51 and the second insulator 52 are arranged along the rotation axis direction X.

[0058] The first insulator 51 covers the first end of the stator core 34 in the rotation axis direction X. Specifically, the first insulator 51 includes a circular ring portion 505 and a plurality of (for example, 9 in the present embodiment, which is the same as the number of the tooth portions 35) covering portions 506. The outer diameter of the circular ring portion 505 is substantially the same as the outer diameter of the cylindrical connecting portion 33 of the stator core 34. The circular ring portion 505 covers the first side of the connecting portion 33 and the tooth portion 35 in the rotation axis direction X (for example, the upper half in the rotation axis direction X). The covering portions 506 are arranged on the inner circumferential surface of the circular ring portion 505 at equal intervals along the circumference of the circular ring portion 505.

[0059] With the teeth 35 covered by the covering portions 506, 511, the windings of the coils 32 are wound around the corresponding teeth 35. That is, the coils 32 wound around the insulator 5 have winding axes intersecting with the rotation axis direction X of the output shaft 20.

[0060] The second insulator 52 covers the second end of the stator core 34 in the rotation axis direction X. Specifically, the second insulator 52 includes an annular portion 510 and a plurality of (for example, 9 in the present embodiment, which is the same as the number of the teeth 35) covering portions 511. The outer diameter of the annular portion 510 is substantially the same as the outer diameter of the cylindrical coupling portion 33 of the stator core 34. The annular portion 510 covers the second side of the coupling portion 33 and the teeth 35 in the rotation axis direction X. The covering portions 511 are arranged on the inner circumferential surface of the annular portion 510 at equal intervals along the circumference of the annular portion 510.

[0061] Nine coils 32 are provided one by one for the nine teeth 35. The nine coils 32 are electrically connected to each other. The coils 32 have a winding axis that intersects with the rotation axis direction X of the output shaft 20. The winding of each coil 32 may be, for example, an enameled wire. The winding includes a linear conductor and an insulating coating covering the conductor.

[0062] The coil 32 is located outside the coupling portion 33. In other words, the coupling portion 33 is located inside the coil 32 (closer to the rotor 2 than the coil 32).

[0063] Nine coils 32 are arranged around the rotation axis C1 and include multiple multi-phase phase coils. The brushless motor 1 of the present embodiment is used as a three-phase brushless motor. Therefore, the multiple multi-phase phase coils include three-phase phase coils. Specifically, the three phases include U phase, V phase and W phase. The nine coils 32 are used as phase coils U1 to U3, V1 to V3 and W1 to W3. Phase coil U1 is adjacent to phase coil V1. Phase coil V1 is adjacent to phase coil W1. Phase coil W1 is adjacent to phase coil U2. Phase coil U2 is adjacent to phase coil V2. Phase coil V2 is adjacent to phase coil W2. Phase coil W2 is adjacent to phase coil U3. Phase coil U3 is adjacent to phase coil V3. Phase coil V3 is adjacent to phase coil W3. Phase coil W3 is adjacent to phase coil U1. Multiple multi-phase phase coils are arranged around the rotation axis C1 in a prescribed order.

[0064] The phase coils U1 to U3 are connected to each other to form a U-phase coil. The phase coils V1 to V3 are connected to each other to form a V-phase coil. The phase coils W1 to W3 are connected to each other to form a W-phase coil.

[0065] The brushless motor 1 includes a plurality of (e.g., 3 in the illustrated example) terminals 8 configured to be connected to a switching circuit 600. The plurality of terminals 8 are located inside (close to the center axis) of a circumscribed circle C2 of a plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3. As used herein, a "circumscribed circle" refers to a virtual circle that circumscribes a polygon drawn by connecting the corresponding outer sides of the coil 32 seen along the rotation axis C1, wherein the coil 32 is configured around the rotation axis C1 and serves as a plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3. The plurality of terminals 8 may be located inside (close to the center) of an inscribed circle C3 of a plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3. As used herein, an "inscribed circle" refers to a virtual circle inscribed in a polygon drawn by connecting the corresponding inner sides of the coil 32 seen along the rotation axis C1, wherein the coil 32 is configured around the rotation axis C1 and serves as a plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3. In the present embodiment, the coil 32 includes three-phase phase coils, and the phase coils are connected to each other. As described above, respectively, the phase coils U1 to U3 are connected to each other, the phase coils V1 to V3 are connected to each other, and the phase coils W1 to W3 are connected to each other. Figure 6 As shown, the three-phase phase coil includes a total of six coil terminals 801, and the six coil terminals 801 are respectively connected to the phase coil U1, the phase coil V1, the phase coil W1, the phase coil U2, the phase coil V2 and the phase coil W2. As used herein, "coil terminal 801" means the end of the wound winding of the coil 32. The phase coil U1 and the phase coil V1 are electrically connected to each other, the phase coil W1 and the phase coil U2 are electrically connected to each other, and the phase coil V2 and the phase coil W2 are electrically connected to each other. Thus, a plurality of (for example, Figure 6 "3" in the example shown) terminals 8.

[0066] The brushless motor 1 further includes a plurality of terminals 8 (for example, Figure 6 The plurality of holding members 507 are held by an insulator 5 having electrical insulation properties. Figure 5 As shown, the insulator 5 and the plurality of retaining members 507 are integrally formed. Specifically, the plurality of retaining members 507 are integrally formed with at least a portion of the insulator 5 (for example, with the first insulator 51). The plurality of retaining members 507 correspond to the plurality of terminals 8 one-to-one. The corresponding terminals 8 are embedded in the corresponding retaining members 507. Figure 5As shown, the plurality of retaining members 507 are formed as recessed portions. The plurality of terminals 8 fitted into the plurality of retaining members 507 are arranged in an inner region surrounded by the plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3, and protrude from the insulator 5 toward the side opposite to the end of the output shaft. Figure 6 As shown, each of the plurality of terminals 8 is arranged in a region between two adjacent teeth 35 of the plurality of teeth 35. The reason is that the region between two adjacent teeth 35 can provide the maximum space for performing some operations. Therefore, the operation efficiency can be improved.

[0067] like Figure 6 and Figure 7 As shown, each of the plurality of terminals 8 includes two holding portions 805, a wiring connection portion 804, a protrusion 802, and an engagement portion 803. When the two holding portions 805 are engaged with the holding member 507 of the insulator 5, each of the plurality of terminals 8 is held by the insulator 5. Figure 6 As shown, the phase coil U1 and the phase coil V1 electrically connected to each other each have a coil terminal 801. In addition, the phase coil W1 and the phase coil U2 electrically connected to each other each have a coil terminal 801. The phase coil V2 and the phase coil W2 electrically connected to each other each have a coil terminal 801. The two coil terminals 801 to be connected to each other are clamped together with the joint 803 by the wiring connection part 804, so that the coils are electrically connected to each other. Specifically, the coil terminal 801 of the phase coil U1 and the coil terminal 801 of the phase coil V1 are clamped together with the joint 803 of the first terminal 8 among the three terminals 8 by the wiring connection part 804. The coil terminal 801 of the phase coil W1 and the coil terminal 801 of the phase coil U2 are clamped together with the joint 803 of the second terminal 8 among the three terminals 8 by the wiring connection part 804. The coil terminal 801 of the phase coil V2 and the coil terminal 801 of the phase coil W2 are clamped together with the joint 803 of the third terminal 8 of the three terminals 8 with the wiring connection portion 804. Various connection methods such as welding can be used to connect the coil terminal 801 to the terminal, and a preferred example is fusion. The connection method may be a combination of welding and fusion. Of course, the connection method may be welding. The protrusion 802 protrudes from the insulator 5 toward the side opposite to the end of the output shaft. As shown in FIG. Figure 7 As shown, the protrusion 802 is engaged to the engaging portion 803 , so that the coil terminal 801 is held by the wiring connecting portion 804 .

[0068] In the present embodiment, the plurality of holding members 507 are formed integrally with the insulator 5. Alternatively, the plurality of holding members 507 may be formed separately from the insulator 5.

[0069] The insulator 5 (second insulator 52) holds the second bearing (bearing) 16. The second insulator 52 has a bearing support portion 17. If the plurality of retaining members 507 and the insulator 5 are formed as separate bodies, the second insulator 52 can hold the second bearing 16. If the plurality of retaining members 507 and the insulator 5 are formed integrally, the plurality of retaining members 507 can hold the second bearing 16. In the present embodiment, since the plurality of retaining members 507 and the insulator 5 are formed integrally, the bearing 16 is held by the plurality of retaining members 507.

[0070] (2-4) Sensor substrate

[0071] The sensor substrate 4 is arranged between the rotor 2 and a plurality of holding members 507, and the plurality of holding members 507 are integrally formed with the insulator 5. The sensor substrate 4 faces the plurality of holding members 507 and is configured to detect the rotation angle of the rotor 2. The sensor substrate 4 is a circuit substrate for detecting the angular displacement of the rotor 2. The sensor substrate 4 is arranged closer to the second insulator 52 than the rotor 2 in the rotation axis direction X, and is parallel to the end surface of the rotor 2. On the sensor substrate 4, a sensor element (one or more) is mounted. Examples of the sensor element include a Hall element and an angle sensor (GMR). The sensor element is configured to detect the angular displacement of the rotor 2.

[0072] The plurality of holding members 507 , the sensor substrate 4 , and the rotor 2 are arranged along the rotation axis direction X. The sensor substrate 4 is disposed between the rotor 2 and the plurality of holding members 507 .

[0073] (2-5)Substrate

[0074] The substrate 6 includes a driving substrate 60, a head heat dissipation sheet 61, a packaging portion 62 and a heat dissipation member 63. Figure 3 and Figure 4 As shown, the driving substrate 60 includes a switching field effect transistor (FET) 600, a large-capacity Zener diode 601 and three holes 602. The switching FET 600 is connected to the coil 32 of each phase coil U1 to U3, V1 to V3 and W1 to W3. The switching FET 600 controls the direction and ON and OFF of the current flowing through the phase coils U1 to U3, V1 to V3 and W1 to W3. The switching element of the switching circuit can be a power metal oxide semiconductor field effect transistor (MOSFET). The PWM control circuit repeatedly turns on and off the various switching elements of the switching circuit at a pulse repetition frequency under PWM control. The processing circuit sends a signal containing a command indicating ON / OFF timing and speed to the PWM control circuit. The Zener diode 601 is constructed to absorb surge current. The three terminals 8 are embedded in the three holes 602. As shown Figure 4 As shown, three terminals 8 are arranged to pass through one or more holes 602 provided in the drive substrate 60 .

[0075] The head heat dissipation sheet 61 helps to dissipate heat from the switch FET substrate that generates heat. The heat sink 63 , the head heat dissipation sheet 61 and the drive substrate 60 are connected to the packaging portion 62 .

[0076] The packaging part 62 may be used to protect the driving substrate 60 from vibration, moisture, dust, etc. The material of the packaging part 62 may be, for example, polyurethane resin. The heat sink 63 helps to dissipate heat from the packaging part 62 and the driving substrate 60.

[0077] (2-6) Bearings

[0078] The brushless motor 1 includes two bearings for rotatably supporting the output shaft 20, namely, a first bearing 14 and a second bearing 16. The first bearing 14 is arranged in a recess formed in the fan 15. The second bearing 16 is arranged in the bearing support portion 17 of the second insulator 52 of the insulator 5. The first bearing 14 and the second bearing 16 have corresponding inner races fixed to the output shaft 20 and corresponding outer races fixed to the body of the brushless motor 1. The inner race of the first bearing 14 and the inner race of the second bearing 16 rotate with the output shaft 20 according to the rotation of the rotor 2. The first bearing 14 and the second bearing 16 include corresponding retainers that retain balls and lubricating oil in a sealed manner. Therefore, the outer race of the first bearing 14 and the outer race of the second bearing 16 can rotate smoothly in a state where the first bearing 14 and the second bearing 16 retain the output shaft 20. Examples of the main materials of the first bearing 14 and the second bearing 16 include high carbon chromium steel, medium carbon steel, and silicon nitride ceramics.

[0079] (2-7) Fan

[0080] The fan 15 is configured to generate air flow to cool the stator 3 and the drive substrate of the brushless motor 1 by air. The rotation of the fan 15 causes air to be introduced into the inside of the housing 11 and the introduced air is discharged through the exhaust port 12 together with heat.

[0081] The fan 15 has a recessed portion for accommodating the first bearing 14 in a central portion of the fan 15. The fan 15 includes blades 150 extending from the recessed portion in a radial direction of the fan 15.

[0082] (3) Operation

[0083] When each of the phase coils U1 to U3, V1 to V3, and W1 to W3 is energized, current flows therethrough to generate a magnetic field. The switching circuit adjusts the direction of the current and ON and OFF to adjust the direction and magnitude of the magnetic field. The switching circuit is configured to supply a driving current according to the angular displacement of the rotor 2. The rotor 2 can provide a driving force according to the angular displacement.

[0084] Phase coils U1 to U3, V1 to V3, and W1 to W3 are arranged at equal angles on the same circumference with the rotation axis C1 as the center. In the present embodiment, the coil 32 includes nine phase coils U1 to U3, V1 to V3, and W1 to W3. Therefore, the "equal angle interval" is 40 degrees. Phase coils U1 to U3 are arranged at equal angles of 120 degrees. Phase coils V1 to V3 are arranged at equal angles of 120 degrees. Phase coils W1 to W3 are arranged at equal angles of 120 degrees. Figure 5 As shown, the phase coil U1 and the phase coil V1 are arranged adjacent to each other, and the phase coil V1 and the phase coil W1 are arranged adjacent to each other.

[0085] The brushless motor 1 has nine slots, so the angular interval is 40 degrees as described above. In addition, the rotor 2 has six magnetic poles. Every time the rotor 2 rotates 20 degrees, the rotor 2 can be continuously rotated by switching the energization of the phase coils U1 to U3, V1 to V3, and W1 to W3. The switching FET circuit adjusts the magnitude and direction of the respective currents flowing through the phase coils U1 to U3, the phase coils V1 to V3, and the phase coils W1 to W3, whereby the rotor 2 rotates continuously.

[0086] The coil 32 generates heat when energized. However, the heated coil 32 is air-cooled by the fan 15 that rotates along with the rotation of the brushless motor 1. When the air introduced through the air inlet 13 is exhausted through the exhaust port 12, the heat is exhausted together with the air. Figure 6 As shown, in this embodiment, multiple (for example, Figure 6 The terminals 8 are arranged in a plurality of multi-phases (e.g., Figure 6 The inside of the inscribed circle of the phase coils U1 to U3, V1 to V3 and W1 to W3 of the three phases (in the example shown). The cooling wind generated by the fan 15 can reach and cool the coil 32 without being blocked by the three terminals 8. This can suppress the increase in the resistance of the coil 32 due to Joule heat, so the efficiency of the brushless motor 1 can be improved. Since the cooling wind generated by the fan 15 can cool the coil 32 without being blocked by the three terminals 8, the change in the local temperature of the stator core 31 caused by the presence of the three terminals 8 can be reduced.

[0087] (4) Advantages

[0088] Having the plurality of terminals 8 located inside the circumscribed circles of the plurality of multi-phase phase coils U1 to U3 , V1 to V3 , and W1 to W3 can provide the brushless motor 1 and the electric power tool 10 in which the cooling efficiency of the coil 32 is improved.

[0089] Improving the cooling efficiency of the coil 32 can suppress the generation of Joule heat to reduce the resistance of the coil 32 , thereby improving the efficiency of the brushless motor 1 .

[0090] (5) Modification

[0091] Some modified examples will be listed one by one. Note that the modified examples to be described below can be adopted in combination with the above-mentioned embodiment as appropriate.

[0092] According to the first embodiment, the base plate 6 includes the head heat radiation sheet 61 , but the present invention is not limited thereto. The base plate 6 may not include the head heat radiation sheet 61 .

[0093] According to the first embodiment, each of the plurality of terminals 8 is arranged in a region between two adjacent teeth 35 of the plurality of teeth 35, but is not limited thereto. Although preferably arranged in a region between adjacent teeth 35, it may be arranged in a region outside the region between adjacent teeth 35.

[0094] According to the first embodiment, the plurality of terminals 8 are located inside the inscribed circle of the plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3, but are not limited thereto. It is sufficient that the plurality of terminals 8 are located inside the circumscribed circle of the plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3. They may be located on or above the plurality of multi-phase phase coils U1 to U3, V1 to V3, and W1 to W3 in the direction of the rotation axis X.

[0095] (Summarize)

[0096] According to the above description, the brushless motor (1) of the first aspect is an inner rotor type brushless motor. The brushless motor (1) includes a plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3) arranged around a rotation axis (C1) and a plurality of terminals (8) configured to connect the plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3) to a switching circuit (600). The plurality of terminals (8) are located inside a circumscribed circle (C2) of the plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3).

[0097] Since the plurality of terminals (8) are located inside the circumscribed circle (C2) of the plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3), this aspect can provide a brushless motor (1) and an electric tool (10) that improve the cooling efficiency of the coil (32). Therefore, the heating of Joule heat can be suppressed, thereby improving the efficiency of the brushless motor (1).

[0098] The brushless motor (1) of the second aspect according to the first aspect further includes a plurality of holding members (507) corresponding one-to-one to the plurality of terminals (8). Each of the plurality of holding members (507) holds a corresponding one of the plurality of terminals (8).

[0099] According to this aspect, a plurality of terminals (8) can be stably held on the insulator (5) using a plurality of holding members (507).

[0100] The brushless motor (1) of the third aspect according to the second aspect further includes a yoke (30), a stator core (31), a stator (3) and an insulator (5). The stator core (31) includes a plurality of teeth (35) protruding from the inner peripheral surface of the yoke (30), and a plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3) are arranged one-to-one on the plurality of teeth (35). The stator (3) includes a coil unit (9), the coil unit (9) includes a plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3) and a plurality of coil terminals (801), the plurality of coil terminals (801) correspond one-to-one to the plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3) and are configured to allow current to flow through the plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3). The rotor (2) is arranged inside the stator core (31) and is spaced apart from the plurality of teeth (35). The rotor (2) is configured to rotate with the central axis of the yoke (30) as the rotation axis (C1). The insulator (5) is fixed to the end surface of the stator core (31) in the rotation axis direction (X). A plurality of retaining members (507) are retained on the insulator (5).

[0101] According to this aspect, the plurality of coil terminals (8) can be stably positioned by the plurality of holding members (507) held on the insulator (5).

[0102] In the brushless motor (1) of the fourth aspect according to the third aspect, the plurality of holding members (507) are provided integrally with the insulator (5).

[0103] This aspect can ensure the strength of the plurality of holding members (507) formed integrally with the insulator (5). In addition, this aspect can reduce the number of components, thereby reducing the defective rate of production.

[0104] In the brushless motor (1) of a fifth aspect according to the third or fourth aspect, the plurality of teeth portions (35) may be separated.

[0105] Since a plurality of teeth (35) can be separated, this aspect can increase the filling rate of the winding. Therefore, a high-efficiency motor can be produced.

[0106] In the brushless motor (1) of the sixth aspect according to any one of the second to fifth aspects, the plurality of holding members (507) also hold the bearings (16).

[0107] Since the plurality of retaining members (507) also retain the bearing (16), the bearing (16) can be supported inside the brushless motor (1) of this aspect.

[0108] In the brushless motor (1) of the seventh aspect according to any one of the third to fifth aspects, the sensor substrate (4) is arranged between the rotor (2) and the plurality of holding members (507) in the rotation axis direction (X). The sensor substrate (4) faces the plurality of holding members (507) and is configured to detect the rotation angle of the rotor (2).

[0109] According to this aspect, the sensor substrate (4) can be stably positioned.

[0110] In the brushless motor (1) of the eighth aspect according to any one of the first to seventh aspects, a plurality of terminals (8) are arranged in an inner area surrounded by a plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3) and protrude toward the side opposite to the end of the output shaft (20) of the brushless motor.

[0111] According to this aspect, since the plurality of terminals (8) are arranged in an inner area surrounded by a plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3) and protrude toward the side opposite to the end of the output shaft (20), the connection length between the plurality of terminals (8) and the switching circuit (600) can be reduced.

[0112] In the brushless motor (1) of the ninth aspect according to any one of the first to eighth aspects, each of the plurality of terminals (8) is arranged in an area between corresponding two adjacent tooth portions (35) among the plurality of tooth portions (35).

[0113] In the case where a machine (manufacturing device) is used in the process of connecting the coil (32) to the switching circuit (600), this aspect can provide a space allowing the machine to be placed. Positioning the terminal in the maximum space between the areas where the winding is wound can improve work efficiency.

[0114] In the brushless motor (1) of the tenth aspect according to any one of the first to ninth aspects, the plurality of terminals (8) are located inside the inscribed circle (C3) of the plurality of multi-phase phase coils (U1 to U3, V1 to V3, W1 to W3).

[0115] Since the plurality of terminals (8) are located inside the inscribed circle (C3), the stator (3) does not include any object that obstructs the flow of cooling air at the outer periphery of the stator (3). Therefore, this aspect can improve the cooling efficiency of the coil (32). Improving the cooling efficiency of the coil (32) can suppress the generation of Joule heat, thereby improving the efficiency of the brushless motor (1).

[0116] In the brushless motor (1) of the eleventh aspect according to any one of the first to tenth aspects, the plurality of terminals (8) are arranged to pass through one or more holes (602) provided in the drive substrate (60).

[0117] This aspect can position the plurality of terminals (8) near the plurality of switch circuits (600) provided on the drive substrate (60), thereby reducing the wiring length.

[0118] An electric tool (10) according to a twelfth aspect comprises the brushless motor (1) according to any one of the first to eleventh aspects and a housing (11) accommodating the brushless motor (1).

[0119] Since the brushless motor (1) used can reduce the change in the local temperature of the stator core (31) caused by the presence of the three terminals (8), this aspect can provide an electric tool (10) including a high-efficiency motor.

[0120] Reference numerals list

[0121] 1 Brushless motor

[0122] 2 Rotors

[0123] 3 Stator

[0124] 5 Insulator

[0125] 507 Retaining member

[0126] 9 Coil Unit

[0127] 10. Power Tools

[0128] 11 Housing

[0129] 16 Second bearing (bearing)

[0130] 20 Output shaft

[0131] 30 yoke

[0132] 31 stator core

[0133] 32 Coil

[0134] 35 teeth

[0135] 60 drive substrate

[0136] 8 terminals

[0137] 600 switch circuit

[0138] 602 holes

[0139] C1 Rotation axis

[0140] C2 circumcircle

[0141] C3 Inscribed Circle

[0142] U1, U2, U3, V1, V2, V3, W1, W2, W phase coil

Claims

1. An inner rotor type brushless motor, comprising: A plurality of multi-phase phase coils arranged around a rotation axis; as well as a plurality of terminals configured to connect the plurality of multi-phase phase coils to a switching circuit, The plurality of terminals are located inside the inscribed circles of the plurality of multi-phase phase coils, The plurality of terminals include corresponding wiring connection portions, each of the wiring connection portions clamping two coil terminals of two phase coils among the plurality of phase coils so as to connect the two coil terminals to each other, The wiring connection parts of the plurality of terminals are located inside the inscribed circle of the plurality of multi-phase phase coils, The plurality of terminals are arranged to pass through one or more holes provided in a driving substrate on which a switching element of the switching circuit is mounted.

2. The brushless motor according to claim 1, characterized in that: The brushless motor further includes a plurality of holding members corresponding one-to-one to the plurality of terminals, Each of the plurality of holding members holds a corresponding one of the plurality of terminals.

3. The brushless motor according to claim 2, characterized in that: The brushless motor also includes: A stator comprising: A stator core comprising: yoke, and a plurality of teeth protruding from the inner peripheral surface of the yoke, and the plurality of multi-phase phase coils are provided one-to-one at the plurality of teeth, and A coil unit comprising: the plurality of multi-phase phase coils, and a plurality of coil terminals corresponding one-to-one to the phase coils of the plurality of phases, and is configured to allow current to flow through the plurality of multi-phase phase coils; a rotor arranged inside the stator core and spaced apart from the plurality of teeth, the rotor being configured to rotate with a central axis of the yoke as the rotation axis; and an insulator fixed to an end surface of the stator core in the rotation axis direction, Wherein, the plurality of holding members are held on the insulator.

4. The brushless motor according to claim 3, characterized in that: The plurality of holding members are provided integrally with the insulator.

5. The brushless motor according to claim 3 or 4, characterized in that: The plurality of teeth are separable.

6. The brushless motor according to any one of claims 2 to 4, characterized in that The plurality of retaining members also retain the bearing.

7. The brushless motor according to claim 3 or 4, characterized in that: A sensor substrate is arranged between the plurality of holding members and the rotor in the rotation axis direction, the sensor substrate faces the plurality of holding members and is configured to detect a rotation angle of the rotor.

8. The brushless motor according to any one of claims 1 to 4, characterized in that: The plurality of terminals are arranged in an inner region surrounded by the plurality of multi-phase phase coils, and protrude toward a side opposite to a distal end of an output shaft of the brushless motor.

9. The brushless motor according to claim 3 or 4, characterized in that: Each of the plurality of terminals is arranged in a region between corresponding two of the plurality of tooth portions adjacent to each other.

10. An electric tool comprising: The brushless motor according to any one of claims 1 to 9; as well as A housing houses the brushless motor.

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