JP2016116267A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool with a motor, capable of achieving more stable operation by preventing deformation, dislocation and scattering of a rotor.SOLUTION: A circular saw 1 includes a brushless motor 5 with a stator 26 and a rotor 27 disposed on its inner periphery side. The circular saw 1 has a saw blade 4 driven by the rotation of the brushless motor 5. The rotor 27 of the brushless motor 5 has a plurality of permanent magnets 33, 33.., a rotor shaft 31 and a shaft hole 33c for penetrating the rotor shaft 31, and a rotor core 32 for retaining the permanent magnets 33, 33... On the outer periphery of the rotor core 32, a tubular member 33b is disposed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power tool such as a marnoco.

In an electric tool such as Marunoko, a motor such as a brushless motor is used as a drive source (see Non-Patent Document 1).
In a power tool, when a brushless motor is employed as a drive source, a brushless motor according to a type in which a permanent magnet is disposed in the rotor of the motor (Interior Permanent Magnet motor, IPM) may be selected.

Makita General Catalog 2013-4, [Search November 4, 2014], Internet <https://www.makita.co.jp/product/ecatalog/sougou/index_f.html>

In an IPM type motor, the rotor (permanent magnet) collapses and scatters due to the occurrence of stress concentration during high-speed rotation of the rotor, and the rotor (permanent magnet) shifts and deforms, resulting in effective magnetic flux. (Magnetic torque) may be reduced.
SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide an electric tool including a motor that can prevent a rotor from being deformed, displaced, and scattered, and can operate more stably.

In order to achieve the above object, a first aspect of the present invention is a brushless motor having a stator and a rotor disposed on the inner peripheral side of the stator, and driven by the rotation of the brushless motor to hold a tip tool. An electric power tool comprising a possible tip tool holding portion, wherein the rotor has a permanent magnet, a rotor shaft, and a hole for penetrating the rotor shaft, and holds the permanent magnet. A rotor core, and a tubular member is disposed on the outer periphery of the rotor core.
The invention according to claim 2 is the above invention, wherein the tubular member is a metal.
According to a third aspect of the present invention, in the above invention, the tubular member is a resin.
The invention according to claim 4 is the above invention, wherein the rotor core has a flux barrier.
The invention according to claim 5 is the above invention, wherein the rotor core is non-cylindrical.
The invention according to claim 6 is a brushless motor having a stator and a rotor disposed on the inner peripheral side of the stator, a tip tool holding portion that is driven by rotation of the brushless motor and can hold a tip tool, The rotor includes a rotor shaft, a rotor core fixed to the rotor shaft, and a tubular permanent magnet disposed on an outer peripheral side of the rotor core, and the permanent A tubular member is arranged on the outer periphery of the magnet.

  According to the present invention, there is an effect that it is possible to provide an electric tool including a motor that can prevent the rotor from being deformed, displaced, and scattered, and can operate more stably.

It is a side view of a marunoco concerning the 1st form of the present invention. It is a top view in FIG. It is AA sectional drawing of FIG. FIG. 4A is a cross-sectional view similar to FIG. 3 and FIG. FIG. 4 is a view corresponding to FIG. 3 of a marnoco according to a second embodiment of the present invention. 6A is a cross-sectional view similar to FIG. 5 and FIG. 6B is a cross-sectional view taken along the line CC in FIG.

  Hereinafter, embodiments of the present invention and modifications thereof will be described with reference to the drawings as appropriate. In addition, this invention is not limited to the said form or the said modification.

[First form]
FIG. 1 is a side view of a marnoco 1 as an example of a cutting machine (hand-held type) in an electric power tool according to the first embodiment of the present invention, and FIG. 2 is a plan view of the marnoco 1. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1.
The marunoco 1 includes a flat base 2 and a main body housing 3 disposed above the base 2.
The main body housing 3 supports a saw blade 4 as a tip tool and houses a brushless motor 5 that rotationally drives the saw blade 4. The main body housing 3 includes a motor housing 6 that holds the brushless motor 5, a gear housing 7 that is connected to the right side of the motor housing 6, and a blade case 8 that is connected to the right side of the gear housing 7 and covers the upper portion of the saw blade 4. Formed from.
A loop-shaped grip housing 9 is provided above the gear housing 7.

The front part of the blade case 8 is connected to a U-shaped connecting plate 10 in plan view through a screw 11 passing through the connecting plate 10 in a state in which the blade case 8 can be rotated in the vertical direction. . The connecting plate 10 is rotatably connected to a left and right guide plate 12 having an arcuate guide groove standing at the front portion of the base 2 by pins in the front and rear direction. The connecting plate 10 can be fixed at any position along the guide groove of the guide plate 12 by a knob screw 13.
Further, a roller 17 projecting sideways is provided on the rear side surface of the blade case 8. The roller 17 passes through a depth guide 15 that curves in a circular arc toward the front side of the blade case 8. The depth guide 15 is rotatably connected to a left and right guide plate 14 erected at the rear portion of the base 2 by a front and rear direction pin. The guide plate 14 has an arcuate guide groove, and the depth guide 15 is connected by a knob screw 16 so as to be fixed at an arbitrary position along the guide groove. A lever 18 is provided on the extended shaft of the roller 17, and the roller 17 can be arbitrarily operated to clamp the depth guide 15 by the lever 18.
The main body housing 3 is rotated around the screw 11 by changing the clamp position of the blade case 8 along the depth guide 15, and the saw blade 4 protruding downward through the square hole 19 provided in the base 2. The amount of protrusion (cut amount) can be adjusted. Further, by changing the fixing position of the connecting plate 10 and the depth guide 15 in the front and rear guide plates 12, 14, the body housing 3 is tilted to the right side from the right angle position where the saw blade 4 is orthogonal to the base 2. The saw blade 4 can be fixed at an arbitrary inclination angle up to the maximum inclination position where the saw blade 4 is inclined at an angle of 45 ° with the base 2. In addition, the front end of the base 2 is formed with cuts 20 and 20 whose side edges are positioned on the extension line of the saw blade 4 at a right angle position (0 °) and a maximum inclination position (45 °) of the saw blade 4. By aligning the side edge of the notch 20 with the black line indicated on the upper surface of the material to be cut, cutting along the black line can be easily performed.

On the other hand, the grip housing 9 is arranged so as to be continuous with the motor housing 6, and is formed by assembling the left half housing 9a and the right half housing 9b with a plurality of screws (not shown). . The rear part of the grip housing 9 is a grip part 22.
A switch 23 in which a trigger 24 protrudes downward is accommodated on the front side of the grip part 22, and a power cord 25 is connected to the rear side of the grip part 22. Although an AC power supply (commercial power supply) is assumed here as a power supply, a battery mounting portion or a battery can be provided instead of the power supply cord 25 or together with the power supply cord 25. The battery can be a direct current power source (eg, DC 100V or more).

The brushless motor 5 in the motor housing 6 includes a stator 26 and a rotor 27 disposed on the inner peripheral side of the stator 26 (inner rotor).
The stator 26 includes a stator core 28 in which a plurality of steel plates 28a, 28a,... Are stacked, a first insulating member 29 and a second insulating member 30 that are in contact with the stator core 28 (on the right side or the left side), and a first insulating member. 29 and four coils (not shown) wound around the stator core 28 via the second insulating member 30. An insulator (not shown) is disposed between each coil and the stator core 28.

As shown in FIG. 4, the rotor 27 is disposed inside the rotor core 32, the left-right rotor shaft 31 disposed in the axial center, the cylindrical rotor core 32 disposed around the rotor shaft 31, and the rotor core 32. A plurality of (four) permanent magnets 33, 33,... And a plurality (four) permanent magnets 33a, 33a,... (See FIG. 4B). The rotor core 32 is a rotor core.
Therefore, the brushless motor 5 is an IPM type in which a plurality of magnets (permanent magnets 33, 33...) Are embedded in the rotor 27.
A tubular member 33 b that covers the rotor core 32 is provided around the rotor core 32 of the rotor 27. The tubular member 33b covers the outside (outer periphery) of the curved surface of the cylindrical rotor core 32 and the outside of the right side plane of the rotor core 32, and the left side plane of the rotor core 32 is not closed but is open to the left. The tubular member 33b is made of a non-magnetic and non-conductive resin, and is a thin tube having a thickness of about 0.35 mm (millimeter), for example.
The rotor core 32 has a hole (shaft hole 33c) for allowing the rotor shaft 31 to pass therethrough at its axis. The rotor core 32 has permanent magnet holes 33d, 33d, which are provided for each permanent magnet 33 and have substantially the same size as the permanent magnet 33, and hold the permanent magnets 33, 33,. ing. Flux barriers 33e and 33e as elongated cavities are provided on both sides of each permanent magnet hole 33d. Each flux barrier 33e is disposed at a corner portion of one of the permanent magnets 33, and prevents the magnetic lines of force of the permanent magnets 33 and 33 adjacent in the circumferential direction from being short-circuited.
Further, adjacent to the second insulating member 30 (left side), a sensor circuit board 34 mounted with two rotation detection elements for detecting the positions of the sensor permanent magnets 33a, 33a,... And outputting a rotation detection signal is fixed. Has been.

The rotor shaft 31 is rotatably supported by a bearing 35 held at the rear portion of the motor housing 6 and a bearing 36 held by the gear housing 7. A first gear 37 is formed at the tip (right part) of the rotor shaft 31, and the right part of the rotor shaft 31 is disposed in the gear housing 7.
A centrifugal fan 38 for cooling the motor is arranged on the left side of the bearing 36. The centrifugal fan 38 is fixed to the rotor shaft 31. A plurality of air inlets 39.39,... Are formed on the left surface of the motor housing 6. On the other hand, a dish-like baffle plate 40 surrounding the periphery of the centrifugal fan 38 is provided on the right side of the stator 26. The baffle plate 40 has a hole through which the rotor shaft 31 passes.

An intermediate shaft 41 parallel to the rotor shaft 31 is provided on the right side of the rotor shaft 31. The left end portion of the intermediate shaft 41 is supported by a bearing 42 held by the gear housing 7, and the right end portion of the intermediate shaft 41 is supported by a bearing 44 held by a bearing retainer 43 assembled to the blade case 8. A second gear 45 is fixed to the left portion of the intermediate shaft 41. The second gear 45 meshes with the first gear 37 of the rotor shaft 31.
A ring 46 held by the bearing retainer 43 is provided on the right side of the bearing 44. The ring 46 receives the thrust load of the bearing 44.
A third gear 47 is formed on the right portion of the intermediate shaft 41. The third gear 47 has a smaller diameter than the second gear 45, and the number of teeth of the third gear 47 is smaller than the number of teeth of the second gear 45.

Further, an output shaft 48 parallel to the intermediate shaft 41 is provided on the right side of the intermediate shaft 41. The left end portion of the output shaft 48 is supported by a bearing 49 held by the blade case 8, and the center portion of the intermediate shaft 41 is supported by a bearing 50 held by the bearing retainer 43.
A fourth gear 51 that meshes with the third gear 47 of the intermediate shaft 41 is provided at the left portion of the output shaft 48.
The right portion of the output shaft 48 passes through the bearing retainer 43 and reaches the blade case 8. The saw blade 4 is fixed to the right end portion of the output shaft 48 by screwing a bolt 54 from the right into the shaft center of the output shaft 48 in a state of being sandwiched between the outer flange 52 and the inner flange 53. The output shaft 48, the outer flange 52, the inner flange 53, and the bolt 54 constitute a tip tool holding portion.
A safety cover 55 that covers the lower side of the saw blade 4 in a normal state is disposed in the blade case 8. The safety cover 55 is rotatably attached to the bearing retainer 43. The safety cover 55 is urged to rotate toward the normal position.

On the other hand, an overhang housing 56 is provided behind the motor housing 6 so as to be connected. A controller 57 is accommodated in the overhang housing 56. The controller 57 has a control circuit board (not shown). The control circuit board has a rectifier circuit and an inverter circuit by mounting a microcomputer, a diode, a smoothing capacitor (electrolytic capacitor), a switching element, and the like.
The inside of the overhang housing 56 communicates with the motor housing 6, and an intake port 58 is formed on the left side surface of the overhang housing 56. On the surface of the controller 57, fins 59, 59,.
An exhaust port 60 (see FIG. 1) is formed on the right side surface of the blade case 8, and a duct 61 (see FIG. 2) is formed on the left side surface of the blade case 8.

An example of the operation of the marnoco 1 will be described.
When the safety cover 55 is rotated from the normal position to the position accommodated in the blade case 8, the power cord 25 is connected to the power source and the trigger 24 is pulled upward, the switch 23 is turned on, and the DC power source rectified by the controller 57 is turned on. The brushless motor 5 is driven. That is, the microcomputer of the controller 57 obtains the rotation detection signal indicating the position of the sensor permanent magnet 33 a of the rotor 27 output from the rotation detection element of the sensor circuit board 34, thereby acquiring the rotation state of the rotor 27. The rotor 27 is rotated by controlling the ON / OFF of each switching element in accordance with the rotated state and causing current to flow sequentially to each coil of the stator 26.
Due to the rotation of the rotor 27, the rotor shaft 31 rotates, the intermediate shaft 41 rotates from the first gear 37 through the second gear 45, and the output shaft 48 rotates from the third gear 47 through the fourth gear 51. And since the saw blade 4 rotates, a workpiece | work can be cut | disconnected.

Further, the cooling air sucked into the motor housing 6 from the intake port 39 by the rotation of the centrifugal fan 38 accompanying the rotation of the rotor shaft 31 passes through the brushless motor 5 as shown by an arrow a in FIG. After the brushless motor 5 is cooled, it is sent to the gear housing 7 side by the baffle plate 40.
On the other hand, the cooling air sucked from the intake port 58 of the overhanging housing 56 passes through the controller 57 and cools the controller 57 as shown by an arrow b, and then moves into the motor housing 6 to similarly baffle plates. 40 is sent to the gear housing 7 side.
Most of the cooling air sent to the gear housing 7 side is blown into the blade case 8 and merged with the air flow generated by the rotation of the saw blade 4 to form the exhaust formed on the right side surface of the blade case 8. It is discharged from the mouth 60. The remaining part of the cooling air is sent to the front end of the blade case 8 through the duct 61 provided on the left side surface of the blade case 8 and blown to the front end of the base 2. Therefore, it is prevented that the black line is hidden by the chips.

And, in the brushless motor 5, since the IPM type in which the permanent magnets 33, 33,... Are embedded in the rotor core 32 and the tubular member 33b covering the outer periphery of the rotor core 32 is provided, even if the rotor 27 rotates at high speed, The permanent magnets 33, 33,... Are pulled by centrifugal force, causing stress concentration, and the permanent magnets 33, 33,... And the rotor core 32 are scattered, or the permanent magnets 33, 33,. Thus, it is possible to prevent the magnet torque from being reduced.
This point will be further described in detail. The centrifugal force applied to the permanent magnets 33, 33,... And the rotor core 32 increases as the rotation speed increases. In the case of a conventional SPM (Surface Permanent Magnet) type rotor, since the permanent magnet is provided on the surface of the rotor core, the permanent magnet is supported only on one side, and cracks are relatively likely to occur. When the permanent magnet collapses, the permanent magnet is scattered in the motor.
On the other hand, in the IPM type brushless motor (without the tubular member 33b), the permanent magnet is embedded in the rotor core, so that the permanent magnet is supported on a plurality of surfaces and fixed more firmly, and the permanent magnet and the rotor core are relatively collapsed. It is hard to occur, and even if the permanent magnet collapses, it is relatively difficult to scatter in the motor. In the conventional IPM type brushless motor, since the permanent magnet is embedded in the rotor core, an extra cover (tubular member 33b) is not put on the rotor core.
However, even in such an IPM type brushless motor (without the tubular member 33b), there is a possibility that the rotor core and the permanent magnet may collapse during high speed rotation. If the rotor core has a non-uniformly shaped portion as a rotating body, stress concentration occurs in the portion, which may cause the rotor core and thus the permanent magnet to collapse or scatter. In addition, a flux barrier is mentioned as an example of a nonuniform part as a rotary body.
Therefore, in the IPM type brushless motor 5 (with the tubular member 33b) of the present invention, the permanent magnets 33, 33,... Are embedded in the rotor core 32 and the tubular member 33b is further covered. Therefore, even if the permanent magnet 33 is firmly held and non-uniform portions such as flux barriers 33e and 33e are provided, the rotor core 32 is supported by the tubular member 33b, and the rotor core 32 and the permanent magnets 33, 33,. Can be prevented from collapsing, and even if at least one of them collapses, the tubular member 33b can prevent the scattering thereof. The tubular member 33b has a cylindrical shape through which the rotor shaft 31 passes through the axial center thereof. The tubular member 33b is sufficiently uniform as a rotating body, and the possibility of collapse due to concentration of stress is extremely small. Further, since the strength of the rotor 27 can be sufficiently secured by installing the tubular member 33b, the flux barriers 33e, 33e,... Can be made relatively large, and the effective magnetic flux is improved correspondingly, and the performance of the brushless motor 5 is improved. Can be improved.
Therefore, in the brushless motor 5, the rotor 27 (particularly the axial length) can be reduced in size while having sufficient strength, and can be rotated at a higher speed. The Marunoco 1 using the brushless motor 5 is It is compact and highly durable (especially in the axial length) while maintaining high output (or maintaining output).

Further, since the tubular member 33b is non-magnetic, the magnetic flux of the permanent magnets 33, 33,... Is not disturbed, the rotor 27 can be smoothly rotated, and the strength can be improved while maintaining the performance of the brushless motor 5. The Marunoco 1 is compact and has high output and high durability.
Furthermore, since the tubular member 33b is non-conductive, there is no generation of heat or heat generation due to electromagnetic induction, and there is almost no loss of magnetic flux of the permanent magnets 33, 33,... Due to the tubular member 33b. The rotor 27 can be efficiently rotated while being increased, and the Marnoco 1 is compact and has high output and high durability.
In addition, since the tubular member 33b is non-conductive, it can be insulated by the tubular member 33b, and when combined with the insulator between the coil and the stator core 28 in the stator 26, the stator 26 side and the rotor 27 are combined. It can be insulated (double insulation) from the side. The insulation by the tubular member 33b and the double insulation can improve the split torque of the rotor shaft 31, and the Marnoco 1 can have a higher output. Further, the insulation on the rotor 27 side has been conventionally performed by arranging a cylindrical insulator between the rotor shaft and the rotor core. However, in the brushless motor 5 of the Marunoco 1, it can be insulated by the tubular member 33b. Therefore, the degree of freedom in designing the conventional insulator portion is increased. For example, the size of the rotor shaft 31 can be reduced by omitting the conventional insulator portion, the rotor shaft 31 can be disposed on the conventional insulator portion, the rotor core 31 or the permanent magnets 33, 33.・ You can enlarge.
Still further, the balance of the rotor 27 can be adjusted by the tubular member 33b. For example, the rotation balance is appropriately observed only by the rotor 27, and the balance of the rotation is observed, and a part of the tubular member 33b is shaved based on the observation. If the tubular member 33b is a material that can be easily processed, such as resin, it is easier to adjust the balance. For balance adjustment, the tubular member 33b can be thickened by, for example, about 0.2 mm.

[Second form]
FIG. 5 is a diagram corresponding to FIG. 3 according to the second embodiment of the present invention, and FIG. 6 is a diagram corresponding to FIG.
Since the marunoco 71 according to the second embodiment is the same as the first embodiment except for the rotor 77 of the brushless motor 75, the same reference numerals as those in the first embodiment are appropriately attached and the description thereof is omitted.
The outer shape of the rotor core 82 extending left and right in the rotor 77 is a cylindrical shape in which the left and right planes (side surfaces) are non-circular, and has a non-cylindrical shape. It has a flower shape with a petal shape. One type of the petal shape is a trapezoidal shape that surrounds two adjacent flux barriers 33e and 33e (a total of four), and the other type connects the petal-shaped portions of the trapezoidal shape. It has an arc shape (total of 4). Therefore, the rotor core 82 has dents 88, 88,... That are recessed with respect to the virtual cylindrical surface on the outer peripheral surface (a total of eight).
The inner surface of the tubular member 83b disposed outside the outer peripheral surface and the right side surface of the rotor core 82 has the same shape as the outer peripheral surface and the right side surface of the rotor core 82, and the rotor core 82 is inserted into the tubular member 83b without a gap. It has been.

Since the rotor core 82 of the brushless motor 75 has a non-cylindrical shape, the marnoco 71 according to the second embodiment has dents 88, 88..., And the magnets for magnetizing the permanent magnets 33, 33. By positioning the magnets at 88, 88,..., The magnetizing magnet can be positioned more easily and closer, and the permanent magnets 33, 33,. It is possible to obtain a marnoco 71 incorporating a better brushless motor 75, and the marnoco 71 can be made more compact with higher output.
In addition, since the tubular member 83b is provided on the outer peripheral surface of the rotor core 82, the rotor core 82 and the permanent magnets 33, 33,... Can be prevented from collapsing and scattering, and even if the rotor core 82 has dents 88, 88,. The rotation of the rotor 77 with good balance can be ensured, and the marnoco 71 can be made more compact with higher output.

[Examples of changes]
In addition, this invention is not limited to the said form, For example, the following changes can be given suitably.
A tubular member can be provided in an SPM type rotor in which a circular permanent magnet having, for example, four poles is provided on the outer periphery of the rotor core. In this case, the permanent magnet itself can be prevented from being destroyed.

The tubular member may cover at least the outside of the curved surface of the cylindrical rotor core, and may further cover the outside of the left plane of the rotor core, or may cover the left and right planes of the rotor core 32 to cover the rotor core. May be enclosed. Further, the tubular member may have one or two or more holes, or a part or all of them may be formed in a mesh shape.
The tubular member may be formed of other materials instead of resin.
For example, it can be formed as a thin-walled tube (for example, 0.2 mm thick) from a non-magnetic metal (stainless steel, etc.). In this case, after the tubular member is thermally expanded, the rotor core is tubularly cooled by inserting the rotor core. Can be inserted into the member (baked-in). The tubular member can be formed of a material that is nonmagnetic but conductive, such as a nonmagnetic metal, and in this case, although it generates a little heat and does not exhibit an insulating action, the strength of the tubular member itself, The fixing strength of the rotor core or the like by the tubular member can be made better.
Further, a non-magnetic sheet (for example, a fiber sheet, particularly a carbon fiber sheet in consideration of further securing strength) is appropriately coated with an adhesive and then wound around the outer peripheral surface of the rotor core 82 to form a tubular member. Also good. Alternatively, the tubular member may be formed by applying an uncured resin material to the outer peripheral surface or side surface of the rotor core and curing the resin material.
Furthermore, the tubular member can be formed of a plurality of materials or components such as a fiber sheet wound around the outer peripheral surface of a resin or metal cylinder.
In the case of resin, the thickness of the tubular member can be appropriately changed, for example, from 1.1 mm to 1.2 mm.

The flux barrier can be omitted. Further, the flux barrier may be filled with a filler such as a resin, and in this case, the strength of the rotor core and the permanent magnet is further increased. By installing the tubular member, sufficient strength can be ensured without filling the flux barrier, which is advantageous in terms of cost, and the degree of freedom in designing the flux barrier, and thus the rotor core and rotor, is increased.
Change the shape, number, and arrangement of flux barriers as appropriate, such as increasing the cross-sectional area, increasing or decreasing the cross-sectional area, and arranging multiple types of flux barriers with different cross-sectional area sizes and lengths. can do.
The shape, size, dent, etc. of the rotor core in the second form can also be appropriately changed. For example, the number, size and arrangement of the petal shapes in the flower shape on the side surface can be changed, or the shape other than the flower shape (non-circular shape other than the flower shape side surface) Non-cylindrical shape with side surfaces), arranging multiple types of dents with different sizes, increasing or decreasing the number of dents, or forming dents only in the center or end in the longitudinal direction (left-right direction) Can be provided.

The number of permanent magnets and coils (the number of poles of the rotor) in the brushless motor can be increased or decreased, for example, 6 poles. Also, the number of stator iron cores can be increased or decreased.
As for the deceleration from the motor output to the output shaft in the Marnoco, it can be replaced with another speed reduction mechanism such as a planetary gear speed reduction mechanism, or these can be used together.
Further, the present invention is applied to other hand-held cutting machines other than Marunoko, non-hand-held cutting machines, other power tools such as rechargeable impact drivers and driver drills, garden tools such as cleaners and garden trimmers, etc. Can be applied.

  1. Marunoko (hand-held cutting machine), 6. Main body (predetermined part relating to hand-held cutting machine), 22. Gear housing, 22a ... Projection, 44 ... Lever, 60 ... Torsion spring.

Claims (6)

A brushless motor having a stator and a rotor disposed on the inner peripheral side of the stator;
A tip tool holding portion driven by the rotation of the brushless motor and capable of holding a tip tool;
An electric tool comprising
The rotor is
With permanent magnets,
A rotor shaft;
A rotor core having a hole for penetrating the rotor shaft, and holding the permanent magnet;
With
A tubular member is disposed on the outer periphery of the rotor core. The power tool according to claim 1, wherein the tubular member is a metal. The electric tool according to claim 1, wherein the tubular member is a resin. The power tool according to any one of claims 1 to 3, wherein the rotor core has a flux barrier. The power tool according to any one of claims 1 to 4, wherein the rotor core has a non-cylindrical shape. A brushless motor having a stator and a rotor disposed on the inner peripheral side of the stator;
A tip tool holding portion driven by the rotation of the brushless motor and capable of holding a tip tool;
An electric tool comprising
The rotor is
A rotor shaft;
A rotor core fixed to the rotor shaft;
A cylindrical permanent magnet disposed on the outer peripheral side of the rotor core;
With
A tubular member is disposed on the outer periphery of the permanent magnet.

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