JP7308411B2 - Electric tool motors and electric tools - Google Patents

Description

TECHNICAL FIELD The present disclosure relates generally to power tool motors and power tools, and more particularly to power tool motors and power tools with fans.

2. Description of the Related Art Conventionally, an electric power tool having a motor is known (see Patent Literature 1).

The power tool of Patent Document 1 includes a motor composed of a rotor and a stator, a cooling fan provided on the rotating shaft of the motor, a motor and a carbon brush portion cooled by the cooling fan, and a housing accommodating the carbon brush portion and the motor. and a cooling air inlet and outlet provided in the housing. The carbon brush part is arranged with a cylindrical side wall between the suction port and the commutator of the motor. is provided, and a metallic radiator plate that engages with the carbon brush portion is provided between the carbon brush portion and the coil end.

The power tool disclosed in Patent Document 1 can reliably cool the motor and the carbon brush portion by providing the cooling air inlet and outlet.

JP-A-2002-254337

In the power tool of Patent Document 1, the motor and the like can be reliably cooled, but there is a possibility that dust such as iron powder may enter the cooling air passage formed between the cooling air inlet and the cooling air outlet. be. As a result, dust can enter the interior of the power tool, for example, the air gap between the rotor and stator.

The present disclosure has been made in view of the above problems, and an object thereof is to provide a power tool motor and a power tool that suppress dust from entering the motor while cooling the motor.

A power tool motor according to one aspect of the present disclosure includes a stator, a rotor, and a fan. The stator has a coil portion. The rotor has a permanent magnet, and is rotated by a magnetic field generated by the permanent magnet and a magnetic field generated by current flowing through the coil portion. The fan has a wall and a plurality of ribs. The wall is provided inside the outer circumference of the fan along the outer circumference of the fan centered on the axis of rotation of the fan, and protrudes from the fan toward the rotor along the axis of rotation. The plurality of ribs are positioned inside the wall. In a cross-sectional view, the plurality of ribs rotate around the rotation axis of the fan in a space surrounded by the wall and a fixed wall formed by a portion of the insulator. When the fan rotates, the power tool motor generates swirling turbulence between a gap formed by the rotor and the stator and an exhaust passage through which the airflow generated by the fan passes.

A power tool motor according to one aspect of the present disclosure includes a stator, a rotor, and a fan. The stator has a coil portion. The rotor has a permanent magnet, and is rotated by a magnetic field generated by the permanent magnet and a magnetic field generated by current flowing through the coil portion. The fan rotates when the rotor rotates. The power tool motor has a buffer chamber between a gap formed by the rotor and the stator and an exhaust path through which the airflow generated by the fan passes. The fan has a plurality of ribs and a plurality of blades. The plurality of ribs are arranged in the buffer chamber. The plurality of vanes are arranged in the exhaust passage. The number of the plurality of ribs is less than the number of the plurality of wings. The power tool motor generates an air pressure difference between the buffer chamber and the exhaust passage when the fan rotates so that the air pressure in the buffer chamber is higher than the air pressure in the exhaust passage.

A power tool motor according to one aspect of the present disclosure includes a stator, a rotor, a rotor housing, and a fan. The stator has a coil portion. The rotor has a permanent magnet, and is rotated by a magnetic field generated by the permanent magnet and a magnetic field generated by current flowing through the coil portion. The rotor housing covers the rotor and an air gap between the rotor and the stator. The fan rotates when the rotor rotates. The fan has a wall and a plurality of ribs. The wall is provided inside the outer circumference of the fan along the outer circumference of the fan centered on the same axis as the rotation axis of the fan, and protrudes from the fan toward the rotor along the rotation axis. The plurality of ribs are positioned inside the wall. The plurality of ribs impede the flow of air from an exhaust passage through which the airflow generated by the fan passes to the rotor housing.

A power tool according to an aspect of the present disclosure includes the power tool motor and a tool body.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a power tool motor and a power tool that suppress dust from entering the motor while cooling the motor.

FIG. 1 is a schematic diagram of a power tool having a motor according to one embodiment. FIG. 2 is an external view of the same motor. FIG. 3 is an exploded perspective view of the same motor. FIG. 4 is a sectional view of the same motor. FIG. 5 is a perspective view of a rotor core of the same motor. FIG. 6 is a bottom view of a fan of the same motor. FIG. 7 is a sectional view of a fan of the same motor. FIG. 8 is a cross-sectional view of the vicinity of the rib during rotation of the same motor. FIG. 9 is a diagram showing a simulation result of the air volume near the rib when the motor is rotating.

Each embodiment and modifications described below are merely examples of the present disclosure, and the present disclosure is not limited to each embodiment and modification. Other than these embodiments and modifications, various modifications can be made according to the design and the like within the scope of the technical idea of the present disclosure. Each drawing described in the following embodiments is a schematic drawing, and the ratio of the size and thickness of each component in the drawing does not necessarily reflect the actual dimensional ratio. .

In the following description, the direction perpendicular to (perpendicular to) the horizontal plane when the motor 1 is installed as shown in FIG. 1 is referred to as the "vertical direction." The arrows indicating the "vertical direction" in the drawings are only shown for the sake of explanation and are not substantial. These directions are not meant to limit the installation state of the motor 1 .

(embodiment)
A power tool and a motor for a power tool according to the present embodiment will be described below with reference to FIGS. 1 to 9. FIG.

(1) Power Tool As shown in FIG. 1 , the power tool 10 includes a motor 1 . 1, the power tool 10 further includes a power source 101, a drive transmission section 102, an output section 103, a chuck 104, a tip tool 105, a trigger volume 106, and a control circuit 107. Prepare. The power tool 10 is a tool that drives a tip tool 105 with the driving force of the motor 1 .

A motor 1 is a drive source that drives the tip tool 105 . Motor 1 is, for example, a brushless motor. A power supply 101 is a DC power supply that supplies a current for driving the motor 1 . Power source 101 includes, for example, one or more secondary batteries. The drive transmission unit 102 adjusts the output (driving force) of the motor 1 and outputs it to the output unit 103 . The output portion 103 is a portion that is driven (for example, rotated) by the driving force output from the drive transmission portion 102 . The chuck 104 is fixed to the output portion 103 and is a portion to which the tip tool 105 is detachably attached. The tip tool 105 (also referred to as a bit) is, for example, a driver, socket, drill, or the like. Among various types of tip tools 105, the tip tool 105 corresponding to the application is attached to the chuck 104 and used.

A trigger volume 106 is an operation unit that receives an operation for controlling rotation of the motor 1 . By pulling the trigger volume 106, the motor 1 can be turned on and off. Further, the rotation speed of the output unit 103, that is, the rotation speed of the motor 1 can be adjusted by the amount of operation for pulling the trigger volume 106. FIG. The control circuit 107 rotates or stops the motor 1 and controls the rotation speed of the motor 1 according to the operation input to the trigger volume 106 . In this power tool 10 , the tip tool 105 is attached to the chuck 104 . By controlling the rotation speed of the motor 1 by operating the trigger volume 106, the rotation speed of the tip tool 105 is controlled.

The power tool 10 of the embodiment includes the chuck 104 so that the tip tool 105 can be replaced depending on the application, but the tip tool 105 need not be replaceable. For example, the power tool 10 may be a power tool that can use only a specific tip tool 105 .

(motor)
(2-1) Overview An overview of the motor 1 will be described with reference to FIG. The motor 1 is, for example, a 3-phase brushless motor with 6 poles and 9 slots. The motor 1 includes an output shaft 20, a housing 11, a plurality of exhaust holes 12, and a plurality of intake holes 13, as shown in FIG. The output shaft 20 transmits the output torque of the motor 1 to the outside. The housing 11 is a case that fixes the stator 3, which will be described later. Also, the lines of magnetic force pass through the housing 11 and the housing 11 forms a magnetic circuit together with the permanent magnet 21 . A plurality of exhaust holes 12 (in FIG. 2, 2 sets of 6 exhaust holes, totaling 12 holes) discharge heat generated inside the housing 11 of the motor 1 together with the air. The exhaust hole 12 is a rectangular hole opened in the housing 11, as shown in FIG. A plurality of intake holes 13 (in FIG. 2, 4 sets of 12 exhaust holes, totaling 48 holes) are holes for sucking air to air-cool the motor 1 . The intake hole 13 is a rectangular hole opened in the housing 11, as shown in FIG.

Next, each element of the motor 1 will be explained using FIG. As shown in FIG. 3 , the motor 1 comprises a first bearing 14 , a fan 15 , a rotor 2 , a stator 3 , a Hall measurement substrate 4 , an insulator 5 , a second bearing 16 and a substrate 6 .

The first bearing 14 and the second bearing 16 are so-called bearings, and are formed of ball bearings or the like. The first bearing 14 and the second bearing 16 hold the output shaft 20 of the rotating rotor 2 . The first bearing 14 and the second bearing 16 face each other along the output shaft 20 with the fan 15, the rotor 2 and the Hall measurement substrate 4 interposed therebetween. The first bearing 14 and the second bearing 16 are fitted into a recess 53 on the upper surface of the fan 15 and a fitting portion 52 of the second insulator 51, respectively. The first bearing 14 and the second bearing 16 have inner rings fixed to the output shaft 20 and outer rings fixed to the motor 1 body. While the inner rings of the first bearing 14 and the second bearing 16 rotate together with the output shaft 20 as the rotor 2 rotates, the balls held by the retainers of the first bearing 14 and the second bearing 16 and the lubricating oil is sealed, the outer rings of the first bearing 14 and the second bearing 16 can hold the output shaft 20 while rotating smoothly. Main materials of the first bearing 14 and the second bearing 16 are, for example, high carbon chromium steel, medium carbon steel, silicon nitride ceramics.

The fan 15 creates an air flow to cool the stator 3 and drive board 61 of the motor 1 with the air. The fan 15 rotates to suck air through the plurality of air intake holes 13 and exhaust the sucked air through the plurality of air discharge holes 12 . At this time, the sucked air passes around the driving substrate 61 and the outside of the stator 3 and is exhausted from the plurality of exhaust holes 12 . The sucked air passes around the drive board 61 and outside the stator 3 to cool the drive board 61 and the stator 3 . In other words, the fan 15 creates an air flow in which the air sucked from the plurality of air intake holes 13 passes around the drive board 61 and the outside of the stator 3, and is exhausted and exhausted from the plurality of exhaust holes 12. to cool the motor 1. A detailed structure of the fan 15 will be described later.

The rotor 2 has an output shaft 20 , a plurality of permanent magnets 21 and a rotor core 22 . The output shaft 20 is held inside the rotor core 22 and transmits the output torque to the outside as described above. Output shaft 20 is supported by first bearing 14 and second bearing 16 .

The permanent magnet 21 is composed of a plurality (six in FIG. 3) of permanent magnets M1 to M6. The permanent magnets 21 are rectangular parallelepipeds and are fitted into holes 23 formed in the rotor core 22 . As shown in FIG. 3, the permanent magnets 21 are arranged adjacent to each other in order from the permanent magnet M1 to the permanent magnet M6 so as to form each side of the regular hexagon along the circumferential direction of the regular hexagon. there is The permanent magnet M1 and the permanent magnet M6 are adjacent to each other. The six permanent magnets 21 are magnetized in the radial direction of the rotor 2 . The three permanent magnets M1, M3 and M5 are magnetized so that the inner circumference has an N pole and the outer circumference has an S pole. The remaining three permanent magnets M2, M4, and M6 are magnetized so that the inner circumference has an S pole and the outer circumference has an N pole. N poles and S poles are alternately arranged on the inner circumference of the six permanent magnets M1 to M6. Similarly, N poles and S poles are alternately arranged on the outer peripheries of the six permanent magnets M1 to M6. The material of the permanent magnet 21 is, for example, iron, cobalt, nickel, etc. In addition, it is an alloy or oxide with neodymium or the like.

The rotor core 22 is circular and includes holes 23 that house a plurality of (six in FIG. 3) permanent magnets 21 . The rotor core 22 is rotatable together with the output shaft 20, and is rotated by a magnetic field generated by current flowing through a coil portion 32 of the stator 3, which will be described later. When an AC voltage is applied to the coil portion 32 of the stator 3 , a rotating magnetic field is generated inside the stator 3 . The rotor 2 also rotates synchronously at the same speed so that the permanent magnet 21 is attracted to the movement of the rotating magnetic field. That is, the rotor core 22 has a permanent magnet 21 , is rotated by the magnetic field generated by the permanent magnet 21 and the magnetic field generated by the current flowing through the coil portion 32 of the stator 3 , and transmits the generated torque to the output shaft 20 . The material of the rotor core 22 is iron, for example. The iron core of the rotor core 22 is made of, for example, silicon-mixed silicon steel, permalloy, or ferrite. In addition, since the rotor core 22 is required to have high strength in order to transmit the generated torque to the output shaft 20, an alloy of iron, nickel, copper, carbon, or the like is sometimes used.

The stator 3 has a stator core 30 , a coil portion 32 and an insulator 5 . Stator core 30 has an outer shell 33 and a plurality of (here, nine) teeth 301 to 309, as shown in FIG. The outer shell 33 is cylindrical and its center coincides with the rotation axis C of the output shaft 20 . A plurality of teeth 301 to 309 have iron cores 31 and connecting members 34 having arcuate surfaces. The coupling member 34 is provided at one end of both ends of the iron core 31 . The plurality of teeth 301-309 are annularly arranged so that the coupling member 34 of each of the plurality of teeth 301-309 is coupled. The inner shell 202 is formed by connecting the plurality of connecting members 34 . Each iron core 31 protrudes from the outer peripheral surface of inner shell 202 formed by annularly arranging teeth 301 to 309 so that coupling members 34 of teeth 301 to 309 are coupled. Each iron core 31 is arranged at equal angular intervals (for example, 40°). The tip of each iron core 31 protruding from the inner shell 202 abuts the inner peripheral surface of the outer shell 33 . That is, the inner shell 202 and the outer shell 33 are connected via each iron core 31 . At this time, the center of the inner shell 202 and the center of the outer shell 33 match. Here, the inner diameter of the inner shell 202 is larger than the diameter of the rotor 2 . The length (radius) from the center of the circle formed by the inner shell 202 to the inner peripheral surface of the inner shell 202 is the radius of the rotor 2 plus the gap 71 formed by the rotor 2 and the stator 3 . Here, the material of the stator core 30 is a material with low loss and high saturation magnetic flux density, such as silicon steel, electromagnetic pure iron, and permalloy.

The insulator 5 has a first insulator 50 and a second insulator 51 . The first insulator 50 and the second insulator 51 are made of an insulator material, for example, a polymer compound such as rubber or enamel, resin, glass fiber, or the like. The second insulator 51 accommodates the second bearing 16 in the fitting portion 52, and further accommodates the hole measurement substrate 4, which will be described later. The first insulator 50 and the second insulator 51 have a structure covering the iron core 31 of the stator core 30 . The first insulator 50 and the second insulator 51 are coupled in the rotating shaft direction of the motor 1 and cover part of the iron core 31 of the stator core 30 . That is, the insulator 5 electrically insulates the iron core 31 from the coil portion 32 described later.

The coil section 32 has nine coils U1 to U3, coils V1 to V3, and coils W1 to W3 in FIG. Coils U1-U3, coils V1-V3, and coils W1-W3 are formed of windings wound inside the motor 1. FIG. The winding material is, for example, copper. A part of the winding material may be aluminum or the like. Windings are wound on each of iron cores 31 whose surfaces are covered with insulators 5 to form coils U1 to U3, coils V1 to V3, and coils W1 to W3. Magnetic fields are generated by sequentially passing currents through the nine coils U1 to U3, the coils V1 to V3, and the coils W1 to W3 of the coil portion 32, and the rotor 2 having the permanent magnets 21 rotates. The coil portion 32 has different properties of the motor 1 depending on the number of turns, the winding method, the coil connection method, and the like. For example, in relation to the number of turns of the motor 1 and the coil portion 32, the greater the number of turns, the slower the maximum rotational speed under no load. Also, the larger the number of turns, the smaller the current required to obtain the same torque. That is, the torque constant is large. The winding method of the coil portion 32 includes, for example, distributed winding and concentrated winding, and the concentrated winding is adopted in this embodiment. Coil connection methods include star connection and triangular connection, for example. In this embodiment, the coil connection method is star connection.

The Hall measurement substrate 4 has a Hall substrate 40 and a Hall IC (Integrated Circuit) 41 . Hall measurement board 4 detects the rotational position of motor 1 . The Hall IC 41 is arranged on the lower surface of the Hall substrate 40 when viewed from the rotation axis. The Hall IC 41 has a magnetic sensor using the Hall effect and an IC that digitizes the output. The Hall IC 41 amplifies the Hall voltage output from the magnetic sensor, and outputs a signal corresponding to the magnitude of the magnetic flux density by performing signal processing with a circuit inside the IC, such as a comparator. The Hall measurement substrate 4 is housed in the second insulator 51 in which the second bearing 16 is housed in the load direction with the rotational axis C of the output shaft 20 of the motor 1 as the center. Further, it is separated from the rotor 2 by a position detection gap 70 which is a slight gap.

The substrate 6 has a potting 60 , a drive substrate 61 , a drive circuit 62 and a heat sink 63 .

The drive circuit 62 is composed of various circuits for driving the motor. Various circuits include at least a switch circuit, a PWM (Pulse Width Modulation) control circuit, and an arithmetic processing circuit. The switch circuit is connected to each of the coils U1 to U3, V1 to V3, and W1 to W3 of the coil unit 32, and switches the direction of current flow and on/off of the current in each of the coils U1 to U3, the coils V1 to V3, and the coils W1 to W3. Control. Each switch element of such a switch circuit can be configured using, for example, a power MOSFET (Metal-Oxide-Semiconductor field-effect transistor). The PWM control circuit repeats the on/off operation of each switch element of the switch circuit at a PWM-controlled pulse repetition frequency. The arithmetic processing circuit transmits a signal including the energization switching timing and the rotational speed command to the PWM control circuit. The drive circuit 62 is configured on the drive substrate 61 .

A heat sink 63 , a drive circuit 62 and a drive substrate 61 are connected by potting 60 . The potting 60 is used to protect the substrate from vibration, and to protect the substrate from contamination such as humidity and dust. The material of the potting 60 is, for example, urethane resin. The heat dissipation base 63 is responsible for heat dissipation from the potting 60 including the drive substrate 61 . The drive circuit 62 turns on and off a large current flowing through each of the coils U1 to U3, V1 to V3, and W1 to W3 of the coil section 32, and thus tends to generate heat. For this reason, the heat dissipation base 63 uses a heat dissipation material substrate such as aluminum nitride ceramics, alumina ceramics, or magnesia ceramics.

(2-2) Configuration The configuration of the motor 1 will be described. First, the structure of the fan 15 will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 is a bottom view of the fan 15 of the motor 1 viewed from below. 6 is a cross-sectional view of a plane passing through the rotation axis C and parallel to the rotation axis C. FIG.

Fan 15 has main plate 150 , output shaft hole 151 , hub 152 , groove 153 , second wall 154 , multiple ribs 155 , wall 156 and multiple blades 157 . Fan 15 is a centrifugal fan.

With reference to FIG. 6, the structure of the fan 15 will be described in order outward from the rotation axis C of the fan 15. As shown in FIG. The fan 15 has a circular shape centered on the rotation axis C, and has an output shaft hole 151 through which the output shaft 20 is passed.

The fan 15 has a hub 152 that is circular with the output shaft hole 151 as its center, that is, is concentric with the fan 15 with the rotation axis C as its center. The hub 152 is coplanar from the output shaft hole 151 to the outer circumference of the hub 152 . The fan 15 has a groove 153 concentric with the fan 15 from the end of the hub 152 . Via the groove 153 , the fan 15 has a second wall 154 that is concentric with the fan 15 and protrudes from the fan 15 toward the rotor 2 when viewed from the direction of the output shaft 20 . Here, the direction from the fan 15 to the rotor 2 when viewed from the output shaft 20 is the direction opposite to the direction of connecting the load, that is, the direction opposite to the load when viewed from the motor 1 .

A rib portion 158 , which is an area composed of the main plate 150 and a plurality of ribs 155 , exists along the circumferential direction of the second wall 154 on the outside of the second wall 154 of the fan 15 as viewed from the rotation axis C. Main plates 150 and ribs 155 alternately appear in the rib portion 158 along the circumferential direction of the second wall 154 . The rib 155 protrudes in the anti-load direction when viewed from the main plate 150 . The height of rib 155 is lower than second wall 154 and lower than wall 156, as shown in FIG. The rib 155 extends from the second wall 154 to a wall 156 which will be described later. The rib 155 perpendicularly intersects the circumferential tangent line of the second wall 154 , and extension lines of the respective perpendiculars from the plurality of ribs 155 to the second wall 154 intersect at the center (rotational axis C) of the fan 15 . That is, each of the plurality of ribs 155 is radially arranged when viewed from the center of the fan 15 . In addition, the ribs 155 are arranged radially with equal angular intervals when viewed from the rotation axis C. As shown in FIG. Rib 155 extends from second wall 154 to wall 156 . The rib 155 also perpendicularly intersects the tangent line in the circumferential direction of the fan 15 with the wall 156 . Ribs 155 are introduced to reinforce the strength of fan 15 .

The wall 156 protrudes concentrically along the outer circumference of the fan 15 and the second wall 154 in the anti-load direction when viewed from the main plate 150 . The height of the wall 156 is the same height as the wing 157, which will be described later, when viewed from the main plate 150 in the anti-load direction. Also, it is higher than the rib 155 and lower than the second wall 154 . The wall 156 prevents dust and the like from entering a gap 71 formed between the rotor 2 and the stator 3, which will be described later. In addition, it forms a labyrinth structure together with a fixed wall 501, which will be described later. Here, the labyrinth structure is a structure in which a constriction is provided so that the gas flow path becomes long, and the gas flow path becomes a labyrinth.

Outside the wall 156 of the fan 15 , there is a vane portion 159 , which is an area composed of the main plate 150 and a plurality of vanes 157 , along the circumferential direction of the wall 156 . The fan 15 thus further comprises a plurality of blades 157 arranged outside the wall 156 . The vane portion 159 is a region from the outer circumference of the wall 156 to the outer circumference of the fan 15 . At the point where the wing 157 and the wall 156 intersect, the tangent line in the circumferential direction of the wall 156 and the wing 157 intersect perpendicularly. That is, the rotation axis C is on the extension line of the wing 157, and the wing 157 spreads radially when viewed from the rotation axis C. As shown in FIG. Further, the wings 157 are arranged radially with even angular intervals as viewed from the rotation axis C. As shown in FIG. The height of the wings 157 protrudes from the main plate 150 in the anti-load direction of the output shaft 20 . Also, the height of the wing 157 is the same as the wall 156, as shown in FIG. The blades 157 discharge air to the outside when the fan 15 rotates, as viewed from the rotation axis C of the fan 15 .

Here, the relationship between ribs 155 and blades 157 of fan 15 will be described. As shown in FIG. 7 , the cross-sectional area of the rib 155 is smaller than the cross-sectional area of the blade 157 in a cross-sectional view along a plane parallel to the output shaft 20 passing through the rotation axis C of the fan 15 . Also, in the fan 15 , the number of ribs 155 is less than the number of blades 157 .

Next, the rotor 2 and the stator 3, which are main parts of the structure of the motor 1, will be described with reference to the cross-sectional view of FIG.

The rotor core 22 and the stator core 30 are separated from each other by a slight air gap 71 with the rotational axis C of the output shaft 20 of the motor 1 as the center. If dust such as iron powder enters the air gap 71, the motor may be locked and the motor 1 may fail. Therefore, it is necessary to prevent iron powder or the like from entering the gap 71 while air-cooling.

The rotor 2 is covered by a rotor housing 200 . Rotor housing 200 is slightly larger than rotor 2 . Rotor housing 200 is formed of a plurality of members. The rotor housing 200 forms the rotor 2 and the air gap 7 . Here, the gap 7 is formed by a position detection gap 70 , a gap 71 formed by the rotor 2 and the stator 3 , and a vent hole 72 .

The surface 201 of the rotor housing facing the lower surface of the rotor 2 in the vertical direction is, as shown in FIG. 51. As shown in FIG. 4, a surface 202 of the rotor housing 200 facing the circumferential direction when viewed from the rotation axis C of the rotor 2 is connected to the coupling member 34 of the stator core 30 via a gap 71 formed by the rotor core 22 and the stator core 30. formed by Since the coupling member 34 is connected and forms the surface 202 of the rotor housing 200, the gap 71 formed by the rotor 2 and the stator 3 can be airtightly covered. Therefore, dust can be prevented from entering from the side surface. A surface 203 of the rotor housing 200 facing the upper surface of the rotor 2 in the vertical direction is covered with the fan 15 as shown in FIG. A ventilation hole 72 formed by the fan 15 and the fixed wall 501 is connected to the outside of the fan 15 via the exhaust path 9 . That is, the rotor housing 200 has a surface 203 that faces the rotor 2 in the direction of the rotation axis C, and at least a portion of the surface 203 is made up of a portion of the fan 15 .

(3) Operation (3-1) Outline Operation of the motor 1 and the fan 15 will be described. The motor 1 is composed of three phases of U phase, V phase and W phase, the permanent magnet 21 is six poles composed of six permanent magnets M1 to M6, and the coil section 32 is composed of nine coils U1 to U3, coils V1 to It is a 9-slot motor consisting of V3 and coils W1 to W3. That is, it is a 3-phase brushless motor with 6 poles and 9 slots. A three-phase brushless motor has a coil portion 32 arranged around a rotor 2 made up of permanent magnets 21 . A switch circuit is connected to the coil portion 32 to turn on and off the current. The switch circuit switches the energization of the coils U1 to U3, the coils V1 to V3, and the coils W1 to W3 according to the rotation of the rotor 2. FIG. Based on the position detection signal generated by the hall measurement board 4, the switch circuit switches the switching timing of the energization of the nine coils U1 to U3, the coils V1 to V3, and the coils W1 to W3. Hall measurement board 4 generates position information corresponding to the rotational position of rotor 2 using a position sensor.

(3-2) Operation As shown in FIG. 3, the coil section 32 includes nine coils: coils U1 to U3, coils V1 to V3, and coils W1 to W3. Coils U1 to U3 are connected to each other to form a U-phase coil. Coils V1 to V3 are connected to form a V-phase coil. Similarly, coils W1 to W3 are connected to form a W-phase coil. A magnetic field is generated in each of the coils U1 to U3, V1 to V3, and W1 to W3 when a current flows through them. The switch circuit of the drive circuit 62 can change the direction and magnitude of the generated magnetic field by switching the direction of current flow and switching on/off of current flow. The drive circuit 62 also supplies a drive current according to the rotational position of the rotor 2 . As a result, the rotor 2 can obtain a driving force corresponding to the rotational position.

The coils U1 to U3, V1 to V3, and W1 to W3 are arranged on the same circumference around the rotation axis C at equal angular intervals. In this embodiment, the coil section 32 is composed of nine coils U1 to U3, V1 to V3, and W1 to W3, so the angular interval is 40°. Coils U 1 to U 3 are wound around teeth 301 , 304 and 307 of stator core 30 . The coils U1-U3 are each arranged at an angular distance of 120° from each other. Coils V1 to V3 are wound around teeth 302 , 305 , 308 of stator core 30 . The coils V1 to V3 are each arranged at an angular distance of 120° from each other. Coils W1 to W3 are wound around teeth 303 , 306 , 309 of stator core 30 . The coils W1 to W3 are arranged at angular intervals of 120° from each other.

Since the motor 1 has 9 slots, the angular interval is 40° as described above. Rotation of the rotor 2 is maintained by switching the energization every time the is rotated by 20°.

Each time the rotor 2 rotates, the output shaft 20 rotates and the fan 15 also rotates. When the fan 15 rotates, the motor 1 sucks air through the plurality of air intake holes 13 of the housing 11 . The sucked air is moved by the fan 15 and cools the drive board 61 , the rotor 2 and the stator 3 . Finally, the airflow generated by the fan 15 is exhausted to the outside of the motor 1 through the exhaust holes 12 of the housing 11 through the plurality of exhaust passages 9 . The coil portion 32 of the stator 3 generates heat due to energization. For this reason, it is necessary to air-cool the outside of the stator 3 in the radial direction when viewed from the rotation axis C of the stator 3 and also cool the inside of the stator 3 .

However, if the inside of the stator 3 in the radial direction as viewed from the rotation axis C is air-cooled, there is a possibility that dust will enter. However, since the anti-load direction of the output shaft 20 of the rotor 2 is covered with the second insulator 51, there is a low possibility that dust or the like will enter. Furthermore, in the radial direction when viewed from the rotation axis C of the rotor 2, the connecting member 34 of the stator 3 is connected to form a part of the rotor housing 200, and the gap 71 between the rotor 2 and the stator 3 is defined by It can be covered with good airtightness and can prevent dust from entering. On the other hand, there is a possibility that dust will enter the air exhaust portion (vent hole 73) because it is ventilated.

For this reason, the fixed wall 501 forming part of the first insulator 50 is provided as a dust intrusion prevention wall. In addition, the fixed wall 501 forms a labyrinth structure together with the wall 156 of the fan 15 to prevent dust from entering from the outside. In the X1-X1 cross-sectional view of the fan 15 shown in FIG. Rotate around axis C. Also, the fixed wall 501 is nested with the wall 156 and faces the plurality of ribs 155 .

Next, the operation during rotation of the rotor 2 will be described. 8 and 9 show cross-sectional views passing through the rotation axis C and parallel to the output shaft 20. FIG. FIG. 8 is a diagram omitting the airflow flow, and FIG. 9 is a diagram showing the airflow flow of the fan 15 at a certain time.

As the rotor 2 rotates, the fan 15 also rotates. When the fan 15 rotates, an air flow is generated that takes in air through the intake hole 13 and exhausts it from the exhaust hole 12 . In the rib portion 158 through which the plurality of ribs 155 of the fan 15 pass, that is, in the buffer chamber 8 surrounded by the second wall 154, the wall 156, the fixed wall 501, and the main plate 150, the passage of the ribs 155 causes disturbance. flow occurs. A plurality of ribs 155 existing inside the wall 156 serve as fins to scrape out the air, and when the air is to be scraped out, the air collides with the wall 156 and the fixed wall 501 to cause turbulence. That is, when the fan rotates, the motor 1 generates turbulence between the air gap 71 formed by the rotor 2 and the stator 3 and the exhaust path 9 through which the airflow generated by the fan 15 passes. The arrows in FIG. 9 indicate the direction of the wind, and the arrows become denser as the wind flow increases. Referring to FIGS. 8 and 9, in the space (exhaust passage 9) in which the blades 157 are arranged, the arrows are dense, that is, the air flow is large. On the other hand, referring to FIGS. 8 and 9, in the space (buffer chamber 8) where the ribs 155 are arranged, the arrows are more sparse than the wing portions 159, that is, the air flow is small. Furthermore, a swirling turbulent flow is generated in the space where the rib 155 is arranged. In other words, turbulence is generated in the buffer chamber 8 between the exhaust passage 9 and the gap 71 . For this reason, the air entering through the plurality of exhaust holes 12 from the outside is less likely to flow into the gap 71 formed by the rotor 2 and the stator 3 via the buffer chamber 8 . As a result, it is possible to prevent dust from entering the gap 71 formed by the rotor 2 and the stator 3 .

The ribs 155 of the fan 15 have a cross-sectional area smaller than that of the blades 157 in a cross-sectional view in a plane parallel to the output shaft 20 and passing through the rotation axis C shown in FIG. Also, in the fan 15 , the number of ribs 155 is less than the number of blades 157 . Therefore, when the fan 15 rotates, the amount of work of the blades 157 to rake the air is greater than the amount of work of the ribs 155 to rake the air. That is, the air pressure of the rib portion 158 having a small cross-sectional area and a small number of rib portions is higher than the air pressure of the vane portion 159 having a large cross-sectional area and a large number of rib portions. Therefore, as shown in FIG. 4, when the fan 15 rotates, the pressure difference between the buffer chamber 8 and the exhaust passage 9 depends on the difference in the amount of work between the ribs 155 and the blades 157 of the fan 15. The atmospheric pressure of 8 is higher than the atmospheric pressure of the exhaust passage 9 . Therefore, when the fan 15 rotates, the motor 1 creates an air pressure difference between the buffer chamber 8 and the exhaust passage 9 so that the air pressure in the buffer chamber 8 is higher than the air pressure in the exhaust passage 9 . Since the difference in pressure causes an airflow to flow from a higher pressure side to a lower pressure side, the airflow is directed from the buffer chamber 8 to the exhaust passage 9 . As a result, dust can be prevented from entering the gap 71 formed by the rotor 2 and the stator 3 . Also, ribs 155 cause pressure fluctuations inside wall 156, and without ribs 155, the pressure is atmospheric because there is nothing inside wall 156 to scoop out air. From this, it can be said that the plurality of ribs 155 obstruct the flow of air from the exhaust path 9 through which the airflow generated by the fan 15 passes to the rotor housing 200 .

From the above, the existence of the plurality of ribs 155 inside the wall 156, the existence of the pressure difference between the buffer chamber 8 and the exhaust passage 9, and the occurrence of turbulent flow inside the buffer chamber 8 cause the buffer An air current flows from the chamber 8 to the exhaust path 9 to suppress dust from entering the gap 71 formed by the rotor 2 and the stator 3 .

(4) Advantages The power tool motor 1 of this embodiment includes a stator 3 , a rotor 2 and a fan 15 . The stator 3 has a coil portion 32 . The rotor 2 has a permanent magnet 21 and is rotated by a magnetic field generated by the permanent magnet 21 and a magnetic field generated by current flowing through the coil portion 32 . The fan 15 rotates when the rotor 2 rotates. When the fan rotates, turbulence is generated between the air gap 71 formed by the rotor 2 and the stator 3 and the exhaust path 9 through which the airflow generated by the fan 15 passes. As a result, it is possible to prevent dust from entering the motor while cooling the motor.

The power tool motor 1 of the present embodiment includes a stator 3, a rotor 2, and a fan 15. A gap 71 formed by the rotor 2 and the stator 3 and an exhaust passage 9 through which the airflow generated by the fan 15 passes. , has a buffer chamber 8 between them. The power tool motor 1 creates an air pressure difference between the buffer chamber 8 and the exhaust passage 9 when the fan 15 rotates so that the air pressure in the buffer chamber 8 is higher than the air pressure in the exhaust passage 9 . Due to the air pressure difference, an air flow is directed from the buffer chamber 8 to the exhaust passage 9, and dust can be suppressed from entering the motor while cooling the motor.

The power tool motor 1 of this embodiment includes a stator 3 , a rotor 2 , a rotor housing 200 and a fan 15 . The stator 3 has a coil portion 32 . The rotor 2 has a permanent magnet 21 and is rotated by a magnetic field generated by the permanent magnet 21 and a magnetic field generated by current flowing through the coil portion 32 . Rotor housing 200 covers rotor 2 and air gap 71 between rotor 2 and stator 3 . The fan 15 rotates when the rotor 2 rotates. Fan 15 has walls 156 and ribs 155 . The wall 156 is provided inside the outer periphery of the fan 15 along the rotation axis C of the fan 15 , and protrudes from the fan 15 along the rotation axis C toward the rotor 2 . A plurality of ribs 155 are positioned inside wall 156 . The plurality of ribs 155 block the flow of air from the exhaust path 9 through which the airflow generated by the fan 15 passes to the rotor housing 200 . As a result, the flow of air from the exhaust passage 9 to the rotor housing 200 is blocked, and dust can be prevented from entering the gap 71 formed between the rotor 2 and the stator 3 .

(5) Modifications Modifications are listed below. It should be noted that the modified examples described below can be applied in appropriate combination with the above-described embodiment.

The shape of the wall 156 of the fan 15 is not limited to a circular shape centered on the rotation axis C. For example, it may have a circular shape centered on the rotation axis C and include a notch. Even with the partial notch, the effect of the wall 156, the fixed wall 501, and the plurality of ribs 155 allows the air gap 71 formed by the rotor 2 and the stator 3 and the fan 15 to be separated when the fan 15 rotates. A turbulent flow is generated between the exhaust path 9 through which the generated airflow passes.

Further, the wall 156 of the fan 15 may have a polygonal shape with the rotation axis C as the center of gravity. Also in this case, due to the effect of the wall 156, the fixed wall 501, and the plurality of ribs 155, when the fan 15 rotates, the gap 71 formed by the rotor 2 and the stator 3 and the exhaust path through which the airflow generated by the fan 15 passes. A turbulent flow occurs between 9 and .

Although the ribs 155 of the fan 15 are radially arranged at even angular intervals when viewed from the rotation axis C, they do not necessarily have to be arranged evenly. A part of the ribs 155 arranged at even angles may be missing, or the ribs 155 may be arranged at uneven angles.

Although the plurality of ribs 155 are arranged on the fan 15, the plurality of ribs 155 may not necessarily be arranged. That is, the number of ribs 155 may be one. Even in this case, turbulence is generated each time the rib 155 passes through the buffer chamber 8 . In addition, since a pressure difference is generated between the buffer chamber 8 and the exhaust passage 9 so that the pressure in the buffer chamber 8 increases, the turbulent flow and the pressure difference prevent dust from entering the gap 71 formed by the rotor 2 and the stator 3 . can be suppressed.

Although the stator 3 has nine teeth 301 to 309 formed radially from the inner shell 202 toward the outer shell 33, the shape is not limited to this. For example, a structure in which the nine teeth 301 to 309 are separately formed and the outer shell 33 is attached after the coil portion 32 is formed may be used. In the divided core structure, the ratio of the area occupied by the coils U1 to U3, V1 to V3, and W1 to W3 in the slots can be increased, and the performance of the motor 1 having the permanent magnets 21 can be improved.

Alternatively, the structure may be such that the core 31 protrudes from the outer shell 33 toward the inner shell 202 . In this case as well, the rotation axis C exists on the radial extension of the nine teeth 301 to 309, as in the embodiment. That is, the teeth 301 to 309 are present radially at angular intervals of 40°.

(summary)
As described above, the electric tool motor (1) of the first aspect includes a stator (3), a rotor (2), and a fan (15). The stator (3) has a coil portion (32). The rotor (2) has a permanent magnet (21) and rotates with a magnetic field generated by the permanent magnet (21) and a magnetic field generated by current flowing through the coil (32). The fan (15) rotates when the rotor (2) rotates. When the fan (15) rotates, the electric tool motor (1) includes a gap (71) formed by the rotor (2) and the stator (3) and an exhaust passage ( 9) and generate a turbulent flow.

According to this configuration, it is possible to provide the power tool motor (1) and the power tool (10) that prevent dust from entering the motor (1) while cooling the motor (1). When turbulence occurs between the air gap (71) formed by the rotor (2) and stator (3) and the exhaust path (9) through which the airflow generated by the fan (15) passes, the airflow from the outside is generated. It becomes difficult to enter the gap (71) formed by the rotor (2) and the stator (3). Therefore, dust is suppressed from entering the gap (71) between the rotor (2) and the stator (3).

A power tool motor (1) of a second aspect comprises a stator (3), a rotor (2) and a fan (15). The stator (3) has a coil portion (32). The rotor (2) has a permanent magnet (21) and rotates with a magnetic field generated by the permanent magnet (21) and a magnetic field generated by current flowing through the coil (32). The fan (15) rotates when the rotor (2) rotates. A power tool motor (1) has a buffer chamber between a gap (71) formed by a rotor (2) and a stator (3) and an exhaust passage (9) through which an airflow generated by a fan (15) passes. (8). In the power tool motor (1), the air pressure in the buffer chamber (8) is higher than the air pressure in the exhaust passage (9) between the buffer chamber (8) and the exhaust passage (9) when the fan (15) rotates. Create an air pressure difference to make it higher.

According to this configuration, it is possible to provide the power tool motor (1) and the power tool (10) that prevent dust from entering the motor (1) while cooling the motor (1). When the pressure in the buffer chamber (8) becomes higher than the pressure in the exhaust passage (9), the flow path of air moves from the inside to the outside of the fan (15), making it difficult for the air to flow into the motor (1). . Therefore, dust is suppressed from entering the gap (71) between the rotor (2) and the stator (3).

A power tool motor (1) of a third aspect comprises a stator (3), a rotor (2), a rotor housing (200) and a fan (15). The stator (3) has a coil portion (32). The rotor (2) has a permanent magnet (21) and rotates with a magnetic field generated by the permanent magnet (21) and a magnetic field generated by current flowing through the coil (32). The rotor housing (200) covers the rotor (2) and the air gap (71) between the rotor (2) and the stator (3). The fan (15) rotates when the rotor (2) rotates. Fan (15) has a wall (156) and a plurality of ribs (155). The wall (156) is provided inside the outer circumference of the fan (15) along the outer circumference of the fan (15) centering on the same axis as the rotation axis (C) of the fan (15). protrudes from toward the rotor (2). A plurality of ribs (155) are positioned on the inside of wall (156). A plurality of ribs (155) impede the flow of air from the exhaust passage (9), through which the airflow generated by the fan (15) passes, to the rotor housing (200).

According to this configuration, the airflow generated by the plurality of ribs (155) collides with the wall (156) and the fixed wall (501) to generate turbulence. The turbulence prevents dust from entering the gap (71) between the rotor (2) and the stator (3).

In the electric tool motor (1) of the fourth aspect, in the third aspect, the plurality of ribs (155) are formed by the wall (156) and the insulator (5) of the motor (1) in a cross-sectional view. The fan (15) rotates around the rotational axis (C) of the fan (15) in the space surrounded by the fixed wall (501).

According to this configuration, the plurality of ribs (155) rotate around the rotation axis (C) of the fan (15) in the space surrounded by the wall (156) and the fixed wall (501), thereby causing turbulent flow. occurs. The generation of turbulent flow prevents dust from entering the gap (71) between the rotor (2) and the stator (3).

In the electric tool motor (1) of the fifth aspect, in the fourth aspect, the fixed wall (501) is nested with the wall (156) and faces the plurality of ribs (155).

According to this configuration, the fixed wall (501) and the wall (156) are nested so that the fixed wall (501) and the wall (156) form a labyrinth structure, which makes it difficult for dust to enter. Further, turbulence is generated by the fixed wall (501) facing the plurality of ribs (155). Therefore, dust is suppressed from entering the gap (71) between the rotor (2) and the stator (3).

In the electric tool motor (1) of the sixth aspect, in any one of the third to fifth aspects, the fan (15) further has a plurality of blades (157) arranged outside the wall (156). . The number of ribs (155) is less than the number of wings (157).

According to this configuration, the number of the plurality of ribs (155) is smaller than the number of the plurality of blades (157). The pressure in the section (159) will be lower than the pressure in the rib section (158) where there are a plurality of ribs (155). Due to the pressure difference, the air flow path is directed from the rib portion (158) to the vane portion (159), and the dust enters the gap (71) between the rotor (2) and the stator (3). Entry is restricted.

In the power tool motor (1) of the seventh aspect, in any one of the third to sixth aspects, the cross-sectional area of each of the plurality of ribs (155) is larger than the cross-sectional area of each of the plurality of wings (157). is also small.

According to this configuration, the number of the plurality of ribs (155) is smaller than the number of the plurality of blades (157). The pressure in the section (159) will be lower than the pressure in the rib section (158) where there are a plurality of ribs (155). Due to the pressure difference, the air flow path is directed from the rib portion (158) to the vane portion (159), and the dust enters the gap (71) between the rotor (2) and the stator (3). Entry is restricted.

In the electric tool motor (1) of the eighth aspect, in any of the third to seventh aspects, the rotor housing (200) has a surface (203) facing the rotor (2) in the direction of the rotation axis (C). ). At least part of the face (203) is made up of part of the fan (15).

According to this configuration, at least part of the rotor housing (200) is part of the fan (15), so that the length of the power tool (10) in the direction of the output shaft (20) can be shortened.

A power tool according to a ninth aspect comprises the power tool motor (1) according to any one of the first to eighth aspects, and a tool body.

According to this configuration, dust entering the gap (71) between the stator (3) and the rotor (2) prevents the motor (1) from locking and the power tool (10) from malfunctioning. .

1 Motor 2 Rotor 3 Stator 5 Insulator 200 Rotor Housing 8 Buffer Chamber 9 Exhaust Path 10 Electric Tool 15 Fan 21 Permanent Magnet 32 Coil Part 71 Air Gap Formed by Rotor and Stator 155 Rib 156 Wall 157 Blade 501 Fixed Wall C Rotating Axis

Claims (9)

a stator having a coil portion;
a rotor having a permanent magnet and rotated by a magnetic field generated by the permanent magnet and a magnetic field generated by the current flowing through the coil;
a fan that rotates when the rotor rotates,
The fan is
a wall provided inside the outer circumference of the fan along the outer circumference of the fan centered on the same axis as the rotation axis of the fan and protruding from the fan toward the rotor along the rotation axis;
a plurality of ribs positioned inside the wall;
The plurality of ribs rotate about the rotation axis of the fan in a space surrounded by the wall and a fixed wall formed by a part of the insulator in a cross-sectional view,
When the fan rotates, swirling turbulence is generated between a gap formed by the rotor and the stator and an exhaust passage through which the airflow generated by the fan passes;
Motors for power tools. a stator having a coil portion;
a rotor having a permanent magnet and rotated by a magnetic field generated by the permanent magnet and a magnetic field generated by the current flowing through the coil;
a fan that rotates when the rotor rotates,
A buffer chamber is provided between a gap formed by the rotor and the stator and an exhaust path through which the airflow generated by the fan passes;
The fan is
a plurality of ribs arranged in the buffer chamber;
a plurality of blades arranged in the exhaust passage,
the number of the plurality of ribs is less than the number of the plurality of wings,
When the fan rotates, an air pressure difference is generated between the buffer chamber and the exhaust passage so that the air pressure in the buffer chamber is higher than the air pressure in the exhaust passage.
Motors for power tools. a stator having a coil portion;
a rotor having a permanent magnet and rotated by a magnetic field generated by the permanent magnet and a magnetic field generated by the current flowing through the coil;
a rotor housing covering the rotor and a gap between the rotor and the stator;
a fan that rotates when the rotor rotates,
The fan is
a wall provided inside the outer circumference of the fan along the outer circumference of the fan centered on the same axis as the rotation axis of the fan and protruding from the fan toward the rotor along the rotation axis;
a plurality of ribs positioned inside the wall;
The plurality of ribs impede the flow of air from an exhaust passage through which the airflow generated by the fan passes to the rotor housing.
Motors for power tools. In a cross-sectional view, the plurality of ribs rotate about the rotation axis of the fan in a space surrounded by the wall and a fixed wall formed by a part of the insulator.
The electric tool motor according to claim 3. The fixed wall is
nested with said wall;
and facing the plurality of ribs,
The electric tool motor according to claim 4. the fan further comprising a plurality of blades positioned outside the wall;
the number of the plurality of ribs is less than the number of the plurality of wings,
The electric tool motor according to any one of claims 3 to 5. a cross-sectional area of each of the plurality of ribs is less than a cross-sectional area of each of the plurality of wings;
The electric tool motor according to claim 6 . The rotor housing has a surface facing the rotor in the direction of the rotation axis,
at least a portion of the surface is made up of a portion of the fan;
The electric tool motor according to any one of claims 3 to 7. The electric tool motor according to any one of claims 1 to 8;
a tool body;
Electric tool.

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