JP2021062444A - Power tool - Google Patents

Abstract

To provide a power tool covering a space between a stator coil and a motor housing by thermosetting resin with high heat dissipation.SOLUTION: In a cylindrical portion 31 of a motor housing, a stator core 21 around which a coil 25 is wound is positioned. An axis of the cylindrical portion 31 is turned vertical, and a convex mold 161 is inserted in that from the lower side to be temporally fixed. Then, a fluidized thermosetting resin 27 is flown from the upper side to a periphery of the coil 25, is filled until an upper end of the coil 25 is hidden, and then is cured. If removing the mold 161 after curing, the stator 20 is solidified by resin in a cylindrical shape. If using one with high thermal conductivity as the thermosetting resin 27, the thermal conductivity of the coil 25 and the cylindrical portion 31 is improved, and heat is finely discharged to atmosphere by the motor housing.SELECTED DRAWING: Figure 12

Description

The present invention relates to a power tool.

Power tools are now driven by battery packs that use secondary batteries, and are becoming more cordless. The battery pack is detachably attached to the power tool body, and when the voltage drops due to discharge, the battery pack is removed and charged using an external charging device. For example, Patent Document 1 discloses a power tool in which a motor housing is provided behind a gear case that supports a spindle and an operation switch is arranged around a motor to be accommodated. In this power tool, the operator performs the work while grasping the periphery of the motor so that the operation switch can be operated.

FIG. 25 is a top view showing a conventional disc grinder 301. The disc grinder 301 has a motor housing 302 that houses a motor 310 that is a drive source. Behind the motor housing 302 is a diameter-expanded portion 302c that extends in the radial direction with respect to the central axis C1, and the battery pack 200 is mounted. Further, the diameter-expanded portion 302c is provided with a control unit 350 for driving the motor 310. A switch mechanism having a trigger lever 335 is provided between the motor 310 and the control unit 350. The switch mechanism switches ON or OFF of the motor 310, and includes a switch 332 and a swing-type trigger lever 335 for operating the switch 332. The trigger lever 335 is provided with an off-lock lever 336.

A gear case 303 is provided in front of the motor housing 302. The gear case 303 accommodates a drive transmission means that converts the power transmission direction of the rotation shaft of the motor 310 by about 90 degrees. A spindle 316 is rotatably supported on the gear case 303, and the upper end of the spindle 316 and the rotating shaft of the motor 310 are connected by two bevel gears 306 and 307. A grindstone 60 is fixed to the lower end of the spindle 316 by a wheel washer 346 and a wheel nut 347. The periphery of the rear side of the grindstone 60 is covered with a metal foil guard 345. A cooling fan 325 is provided between the motor 310 and the gear case 303. An outside air suction port (not shown) is provided on the side surface of the enlarged diameter portion 302c of the motor housing 302, and air is sucked into the motor housing 302 from the suction port by the rotation of the motor 310, and the air is sucked into the motor housing 302 from the rear side to the front side of the motor housing 302. It flows to the side, passes around and inside the motor 310, flows from the vicinity of the fan 325 to the gear case 303 side, and is discharged to the air from the exhaust port provided in the gear case 303.

JP-A-2018-140447

In the conventional disc grinder 1 as shown in FIG. 25, the motor is cooled by providing an intake port and an exhaust port in the housing and generating cooling air. On the other hand, the outside air may contain dust, and especially in the case of a tool for metal processing such as a grinder, a large amount of metal powder is generated by the work. If such dust enters the inside of the housing, it may adversely affect electronic parts such as a motor. On the other hand, if the motor is configured to be isolated from the outside air, the adverse effect of dust can be suppressed, but cooling by the fan cannot be performed, which causes a problem on the cooling surface of the motor.

The present invention has been made in view of the above background, and an object of the present invention is to provide a power tool having improved dust resistance by housing a motor in a metal sealed case.
Another object of the present invention is to efficiently transfer heat from the stator to the motor housing and dissipate heat from the motor housing by covering the space between the stator coil and the motor housing with a thermosetting resin having good heat conduction characteristics. The purpose is to provide such power tools.
Still another object of the present invention is to provide a power tool having improved insulation and durability by covering the stator coil with a thermosetting resin and hardening the stator coil.

The typical features of the invention disclosed in the present application will be described as follows.
According to one feature of the present invention, a rotor using a permanent magnet, a stator in which a coil is wound around a stator core, a brushless motor having a rotating shaft for holding the rotor, a switch for turning on / off the brushless motor, and the like. In a power tool having a housing that holds a brushless motor and a switch, the housing has a motor housing that is isolated from the outside air and houses the brushless motor. The stator core holds the coil, and the coil and the inner surface of the motor housing are connected by the curable resin by filling the outer part in the radial direction from the portion where the coil is located with a curable resin having high thermal conductivity. I did it. The motor housing is made of metal, and the heat conductivity of the curable resin is 1.0 W / m · k or more, particularly preferably 2.0 W / m · k or more. A curable resin having a thermal conductivity of 4.0 W / m · k or more may be used as long as it has sufficient fluidity and curability as the resin in a liquid state. The curable resin is preferably a thermosetting resin which is heated to make it flow, then filled in the space where the coil of the stator core is accommodated, and then cooled and cured.

According to another feature of the present invention, the motor housing has a tubular portion having at least one end open and a lid portion (bottom cover) attached to one end of the tubular portion, and the coil has one end in the rotation axis direction. The area from the side to the other end is continuously covered with a thermosetting resin. The portion to be hardened by the thermosetting resin is from the cylindrical surface connecting the innermost peripheral positions of the teeth of the stator core in the radial direction to the outer portion in the radial direction and the inner wall surface of the tubular portion. Further, the outer peripheral surface of the stator core and the inner wall surface of the tubular portion are in contact with each other so as to have a gap, and the gap portion is filled with a curable resin.

According to still another feature of the present invention, the stator core in the state where the coil is wound is positioned inside the tubular portion, and the axial direction of the rotation axis of the tubular portion is positioned so as to be vertically oriented. Temporarily fix by inserting a convex jig that closes the lower side in the axial direction and the inner peripheral side of the part. After that, the curable resin in a fluid state is poured from above around the coil, and the space between the jig and the tubular portion is filled with the curable resin until the upper end of the coil is hidden, and then the curable resin is cured. Finally, the stator is fixed to the tubular portion by removing the convex jig. The leader wire from the coil should be taken out from the liquid level of the curable resin downward in the axial direction.

According to still another feature of the present invention, the tubular portion has both ends open in the axial direction, and the lid portion (bottom cover) that closes one opening has a through hole through which the rotation shaft penetrates. Is closed by a rotating shaft and a bearing member that pivotally supports the rotating shaft. Further, the lid portion (top cover) that closes the other opening holds a bearing member that pivotally supports the rotation shaft at the inner portion. In this way, the opening of the tubular portion is closed by the first lid portion (bottom cover) and the second lid portion (top cover) so that a closed motor housing is formed.

According to still another feature of the present invention, it has a handle that is connected to the motor housing, the handle houses the switch, and the lead wire from the coil passes through a wiring hole provided on the side of the motor housing. It is wired to the inside of the handle. The wiring hole through which the leader wire from the coil is passed may be closed with the same resin as the curable resin or another resin. In addition, a circular tip tool is attached to the rotating shaft, the tip tool is partially covered with a metal protective cover, and the motor housing supports the motor housing and the protective cover extending from the motor housing. It was configured to have an extension.

According to the present invention, the heat generated by the coil can be effectively transferred to the motor housing by the heat-dissipating resin. Since the motor housing is made of metal, this allows the motor to be suitably cooled. Further, in the motor housing, since the tubular portion having the opening is closed by the lid portion, a hermetically sealed structure can be easily realized. Further, since the resin can be filled and cured with the lid removed, the assembly workability is improved. Since a curable resin having high thermal conductivity is used, the metal motor housing and the protective cover attached to the motor housing can function as a heat sink for diffusing heat.

It is a vertical sectional view of the disc grinder 1 which concerns on embodiment of this invention. It is a left side view of the disc grinder 1 which concerns on embodiment of this invention. It is a top view of the disc grinder 1 which concerns on embodiment of this invention. It is a partially enlarged view around the spindle 17 of FIG. It is a developed view around the spindle 17 of FIG. 5 is a view of the fan 50 alone, FIG. 5A is a bottom view, and FIG. 5B is a top view. 5 is a perspective view of the fan 50 alone, FIG. 5A is a perspective view seen from below, and FIGS. 5B and 5C are perspective views viewed from above. It is sectional drawing of the part AA of FIG. It is sectional drawing of the BB part of FIG. Of the vertical cross-sectional views of the disc grinder 1 of FIG. 1, the rotor 11 is shown in a side view. It is a figure explaining the method of fixing the stator 20 to the motor housing 30 of FIG. 1 (the 1). It is a figure explaining the method of fixing the stator 20 to the motor housing 30 of FIG. 1 (the 2). It is the same figure as FIG. 10, and is the figure for demonstrating the heat transfer path. It is a perspective view of the foil guard 65 alone of FIG. It is a modification of this Example, and is the cross-sectional view corresponding to the CC part of FIG. It is a figure for demonstrating the assembling method of the rotating shaft 15 and the permanent magnet 13 of FIG. It is a figure which shows the permanent magnet 13A different from FIG. It is a cross-sectional view of the DD part, the EE part, and the FF part of FIG. 17, and is the figure which showed the direction of the magnetic fluxes thereof. It is sectional drawing which showed the direction of the magnetic flux of the permanent magnet 230 of the conventional example. It is a partially enlarged view around the coil 25 and the leader lines 26b, 26e of FIG. It is a top view of the tubular part 31 alone of FIG. It is a top view of the state where the stator 20 is attached to the tubular portion 31 alone of FIG. 21. It is a circuit diagram of the disk grinder 1 of this embodiment. It is a side view of the motor housing 30 which shows the pull-out state of the coil lead-out line 26a-26f and the signal line 80a-80e from the tubular part 31 of FIG. It is a vertical sectional view of the disc grinding machine 301 which concerns on a prior art. It is a front side view of the circular saw 101 (cutting machine) which is a modification of this invention.

Hereinafter, examples of the present invention will be described with reference to the drawings. In the following figures, the same parts are designated by the same reference numerals, and the repeated description will be omitted. Further, in the present specification, the front-back, left-right, and up-down directions are described as the directions shown in the drawings. In this embodiment, as an example of a power tool, a disc grinder 1 for driving a motor using a battery pack as a power source and rotating a disk-shaped grindstone will be described.

FIG. 1 is a vertical sectional view of a disc grinder 1 according to an embodiment of the present invention. The disc grinder 1 is a power tool that uses the electric power of the battery pack 200 to rotate a disk-shaped grindstone 60 by a motor 10. The disc grinder 1 of this embodiment is characterized by the arrangement of the motor 10. The motor 10 is arranged coaxially with the spindle 17 to which the grindstone 60 is fixed, and the spindle 17 is directly mounted on the rotating shaft 15 of the motor 10. Adopted a direct drive system to drive. That is, no reduction mechanism using gears is provided between the spindle 17 and the rotating shaft 15 of the motor 10. The motor 10 is housed inside a metal motor housing 30. The main housing (rear housing) 2 is fixed to the motor housing 30 in the direction orthogonal to the rotation axis B1 toward the rear side. A grip portion (handle portion) 2b that the operator grips with one hand is formed near the center of the main housing 2. A diameter-expanded portion 2c having a rail mechanism 86 is formed on the rear side of the main housing 2, and the battery pack 200 is detachably provided by using the rail mechanism 86. In the disc grinder 1, the rotation axis B1 of the motor 10 is in the vertical direction in the state shown in FIG. 1, and the central axis A1 of the main housing 2 is in the horizontal direction. In the power tool (including the disc grinder 1) of this embodiment, the power supply is arbitrary, and an AC power supply may be used instead of the battery pack 200. When using an AC power supply, the power cord may be connected to the position where the battery pack 200 is attached, and a rectifier circuit for rectifying the input AC power supply may be provided to supply the output of the rectifier circuit to the inverter circuit described later. ..

The motor 10 housed in the motor housing 30 is a brushless DC motor. Here, the rotor 11 is provided on the rotating shaft 15, and the stator 20 is provided on the outer peripheral side. A rotor 11 having a cylindrical permanent magnet 13 on the outside of the rotor core 12 is used, and a stator 20 having a coil 25 wound around the stator core 21 arranged on the outer peripheral side is provided. That is, the motor 10 is an inner rotor type brushless DC motor. The stator core 21 is composed of laminated iron cores and is fixed inside the cylindrical motor housing 30. The motor housing 30 is a closed type, and is an air-cooled type in which the metal motor housing 30 is cooled by the outside air. Here, the closed type means a structure that is isolated from the outside so that air exchange with the outside is completely or almost never performed, and here, the opening on the side surface of the motor housing 30 is from the motor 10. There is only a minimum number of passages (wiring holes) through which necessary wiring is passed, and a cooling fan is not provided inside the motor housing 30.

The motor 10 is cooled indirectly by cooling the motor housing 30 with cooling air. The motor housing 30 can be cooled only by contact with the outside air, for example, by forming cooling fins extending in the normal direction on the outer surface of the motor housing 30 to improve heat dissipation. However, in this embodiment, instead of providing the fins, a cooling fan 50 is provided between the motor accommodating portion of the motor housing 30 and the grindstone 60 when viewed in the direction of the axis B1. That is, the fan 50 is arranged in the outer portion of the motor accommodating portion constituting the closed space. The fan 50 is arranged between the motor housing 30 and the grindstone 60 which is a tip tool when viewed in the direction of the rotation axis B1. In this embodiment, a part of the blade portion of the fan 50 (described later in FIGS. 6 and 7). Is provided inside the extension portion extending below the motor housing 30. The fan 50 rotates in synchronization with the rotation of the motor 10 by being fixed to the spindle 17 formed integrally with the rotating shaft 15.

A paddle type switch mechanism 91 is provided on the grip portion 2b of the main housing 2. The switch mechanism 91 includes a switch 92 and a paddle lever 95 for pressing the plunger 93 of the switch 92 (see FIG. 2 described later). The paddle lever 95 operates about a small rotation angle around the swing shaft 94, and is an operation unit for turning on or off the switch 92. The state of FIG. 1 is an unoperated state (a state in which the rotation of the motor 10 is stopped) in which the operator does not pull the paddle lever 95 during work. What is characteristic here is that, in the state where the paddle lever 95 is operated, the tip portion 95a of the paddle lever 95 extends forward to a position close to the motor housing 30. At this time, since the distance between the tip portion 95a of the paddle lever 95 and the upper surface of the wheel guard 65 is sufficiently secured, the operator can grip the portion sufficiently close to the motor housing 30. Further, even if the grip portion 2b is gripped sufficiently close to the motor housing 30, a space for the operator's finger to enter is sufficiently secured between the grip portion 2b and the wheel guard 65 when viewed in the direction of the rotation axis B1. is there.

The diameter-expanded portion 2c of the main housing 2 is formed so as to expand radially outward from the central axis A1 as compared with the grip portion 2b, and the control unit 70 is housed inside the diameter-expanded portion 2c. The control unit 70 has the control circuit board 72 mounted in the storage case 71. The storage case 71 has a tray shape with an opening surface facing forward, and a control circuit board 72 is housed therein. The control circuit board 72 includes an inverter circuit for driving a brushless DC motor 10 and a microcomputer. A calculation unit or the like having the above is installed. The inverter circuit is composed of six FETs (Field Effect Transistors) that cannot be seen in the figure, and the FETs are provided with cooling fins 74 for heat dissipation. The cooling fins 74 are made of an aluminum alloy having a predetermined wall thickness and a sufficient size, and the cooling fins 74 are arranged so that their surface directions are along the central axis A1.

A rail mechanism 86 for connecting to the battery pack 200 is provided on the rear side of the storage case 71 and facing the battery pack 200, and a plurality of connection terminals 87 are provided inside the rail mechanism 86. In this embodiment, the rail mechanism 86 serves as the attachment / detachment portion of the battery pack 200, and its structure is composed of two parallel groove portions and a latch mechanism. However, the structure of the battery pack attachment / detachment portion is arbitrary, and may have a shape that does not use a rail or a rail groove. A connection terminal (not shown) on the battery pack 200 side is located at a position opposite to the connection terminal 87. The battery pack 200 is widely used in power tools and the like, and contains a plurality of secondary battery cells inside a synthetic resin upper case 201 and a lower case 202. Here, lithium ions are used. A battery cell is used. The upper case 201 is provided with a rail mechanism (not shown) and a connection terminal (not shown). The battery pack 200 is attached to the main housing 2 by relatively moving from the bottom to the top. When removing the battery pack 200, the battery pack 200 is moved downward while pressing the latch button 203. The battery pack support member 2d is formed so as to project rearward from the main housing 2 portion in the upper center of the battery pack 200.

The spindle 17 and the rotating shaft 15 are arranged side by side in the rotation axis B1 direction. The motor 10 is arranged so that the rotation axis 15 intersects the central axis A1 of the grip portion 2b of the main housing 2, where the rotation axis B1 of the motor is orthogonal to the central axis A1. The end of the rotating shaft 15 of the motor 10 is fixed to the motor housing 30 by two ball-type bearings 38 and 48. The motor housing 30 has a tubular portion 31 having upper and lower opening surfaces along the rotation axis B1, a top cover (upper lid portion) 35 that closes the upper opening of the tubular portion 31, and a lower opening of the tubular portion 31. It is formed by a bottom cover (lower lid portion) 40 that closes the door, and is a closed type (fully closed type). Both of these are formed of non-magnetic metals such as aluminum alloys. The upper bearing 38 is held by the top cover 35, and the lower bearing 48 is held by the bottom cover 40. Since the bearings 38 and 48 are held by the metal motor housing 30 in this way, it is advantageous not only in terms of strength but also in terms of heat dissipation.

The coil 25 is wound around the stator core 21 in a predetermined winding manner, and the entire stator 20 including the portions protruding from the upper side and the lower side of the stator core 21 is molded with the thermosetting resin 27. That is, the stator 20 has a structure in which the stator 20 is infiltrated with resin and then cured. The thermosetting resin 27 firmly holds the coil 25 so that it does not move due to vibration or the like, and also adheres the coil 25 to the inner wall surface of the tubular portion 31 on the outer peripheral side thereof, so that the stator core 21 is stable on the tubular portion 31. Can be held. Further, by using a thermosetting resin 27 having good thermal conductivity characteristics, heat from the stator core 21 and the coil 25 can be efficiently transferred to the tubular portion 31, so that the heat dissipation of the motor 10 can be improved. ..

An annular sensor substrate 28 is arranged between the top cover 35 and the coil 25. The sensor board 28 is for mounting three hole ICs 29 (only one can be seen in the figure), and is composed of an FPC board having a hole penetrating the rotation shaft 15 in the center. The sensor substrate 28 is arranged so as to be orthogonal to the rotation axis B1, and the hall IC 29 is arranged on the bottom surface side at a predetermined interval in the rotation direction so as to face the upper end surface of the permanent magnet 13. A signal line for transmitting the output of the Hall IC is drawn out from the bottom surface side of the sensor board 28 and wired to the main housing 2 side. Details will be described later with reference to FIG. 10 and the like.

The bottom cover 40 functions as a fixing member of the bearing 48 that pivotally supports the spindle 17. Further, a cylindrical foil guard mounting portion 46 is formed on the outer surface side of the bottom cover 40, and the foil guard 65 is mounted using the outer peripheral surface of the foil guard mounting portion 46. A through hole 42 is formed in the center of the bottom cover 40, and the spindle 17 extends through the through hole 42. A wheel washer 62 is provided on the spindle 17, and the grindstone 60 is fixed to the spindle 17 so as to be sandwiched between the wheel washer 62 and the wheel nut 64. Since the rotational force is transmitted from the rotating shaft 15 to the spindle 17 without going through the reduction gear, no operating noise is generated due to the meshing of the gears when the motor 10 rotates. In particular, in this embodiment, since the rotating shaft 15 and the spindle 17 are integrally formed, it is advantageous for noise reduction. Further, since there is no gear meshing, a plurality of merits such as a longer life of the power tool can be obtained.

The grindstone 60 is, for example, a resinoid flexible toys, flexible toys, resinoid toys, sanding discs, etc. having a diameter of 100 mm, and can be used for surface polishing and curved surface polishing of metals, synthetic resins, marble, concrete, etc. by selecting the type of abrasive grains to be used. is there. The rear upper surface, rear side surface, and lower surface of the grindstone 60 are covered with a metal foil guard 65. The foil guard 65 is a protective cover that protects the operator from scattering of ground members and damaged abrasive grains.

The grip portion 2b and the foil guard 65 partially overlap in the direction of the central axis A1 of the grip portion. Here, when the paddle lever 95 is pulled (swinged upward) during work, a sufficient space for the operator's fingers is secured between the extension of the upper surface of the wheel guard 65 and the grip portion 2b, so that the operator can enter the space. Can perform the work while gripping the vicinity of the rotation axis B1 on the front side of the grip portion 2b. That is, since the operator can grip the portion closer to the rotation axis B1 of the spindle 17 than the conventional disc grinder 301 (see FIG. 25), the gripped portion of the operator is the pressing portion of the grindstone 60 during work (the tip of the grindstone 60). It is close to 60a), and the work can be performed with a light pressing force.

The left and right portions of the main housing 2 are fixed by four screws (not shown), so that the main housing 2 on the right side is provided with screw bosses 9e to 9h. The switch 92 has a plunger 93 extending in the vertical direction, and the plunger 93 is urged downward by a spring (not shown). A pressing portion 95b is formed on the upper surface of the paddle lever 95, and the pressing portion 95b comes into contact with the lower end portion of the plunger 93. The paddle lever 95 has a counterclockwise swing angle limited in the drawing by a stopper (not shown). An off-lock lever 96 is provided near the front end of the paddle lever 95. In order for the operator to turn on the switch mechanism, the lower end of the off-lock lever 96 is swung forward to move the upper end position of the paddle lever 95 to the rear. As a result, when the operator grasps the grip portion 2b and the paddle lever 95 together and moves them upward, the upper end of the off-lock lever 96 enters the hole portion 2e formed in the bottom surface of the grip portion 2b, so that the paddle lever 95 Can be rotated upward. Since the off-lock lever 96 is urged counterclockwise in the drawing by the torsion coil spring 97, when the operator releases the operation of the paddle lever 95, the upper end of the off-lock lever 96 is on the front side of the hole 2e. By moving to, the paddle lever 95 cannot be operated upward without operating the off-lock lever 96, and the locked state is maintained.

In the present embodiment, drives the grinding wheel 60 at a direct-drive system, since the grip portion 2b installed between the motor 10 and the battery pack 200, the thickness T _H of the grip portion 2b is thinner, the product overall length L is conventional The total length of the disc grinder 301 (see FIG. 25) L ₀ can be shortened, and a compact disc grinder 1 can be realized. Moreover, it was possible to the thickness T _H of the grip portion 2b is smaller than the diameter D _m of the motor 10 ₍₌ inner diameter of the motor housing portion of the motor housing 30). In this embodiment, the outer shape of the grip portion 2b may have a perfect circular cross-sectional shape, an elliptical shape, or a substantially polygonal shape.

To efficiently generate a large torque in the motor 10 is better to reduce the length L _S of the stator by increasing the outer diameter D _m of the stator core 21 is advantageous in terms of reducing the volume of the motor, a cordless disk for grinder, a longer lamination thickness L _S of the stator 20 to reduce the diameter D _m of the motor 10, it is advantageous that the motor 10 of a so-called portrait. _{By setting the relationship of L S} > D _m / 2 in this way, the grip portion 2b (handle portion) between the motor 10 and the battery pack 200 can be installed at a higher position than before. , The operator can grasp the vicinity of the rotation axis B1 and the workability is improved. Further, in this embodiment, since the direct drive system having no deceleration mechanism is used to drive the grindstone 60, the diameter of the motor housing 30 can be reduced and the cutting depth can be increased.

Since the central axis A1 of the grip portion 2b connecting the motor 10 and the battery pack 200 is installed at a position sufficiently higher than the mounting surface, workability is improved. Specifically, the central axis A1 of the grip portion 2b is located above the vertical center position of the battery pack 200. If the center position of the grip portion 2b is lower than the center position of the battery pack 200, the arm of the operator who grips the grip portion 2b from above may interfere with the battery pack 200 or the battery pack support member 2d, which may hinder the work. However, such a problem is unlikely to occur in the structure of this embodiment. Further, when the grip portion 2b is in a high position, a large space below the grip portion 2b can be taken, so that the grip portion 2b can be easily gripped and the operator's fingers are prevented from coming into contact with the ground or the like when gripping the grip portion 2b. it can. Further, on the upper surface extension surface of the foil guard 65, the lower height 2f (height from the PL surface) of the grip portion 2b is higher than the lower end portion height of the coil 25 from the PL surface. Since the area around the lower coil end can be easily cooled by the outside air, the motor cooling performance is improved.

FIG. 2 is a left side view of the disc grinder 1 according to the present embodiment. In the state of FIG. 2, the switch 92 (see FIG. 1) is off. The main housing 2 is configured to be divided into two in the left-right direction on the extending surface passing through the central axis A1 (see FIG. 1), and the right side part and the left side part of the main housing 2 are fixed by a plurality of screws 5e to 5g or the like. Will be done. Further, the mounting portion 2a of the main housing 2 fixes the motor housing 30 with four screws 5a to 5d (5a and 5b are not visible in FIG. 2). Two side handle mounting holes 7c and 7d are formed on the side surface portion of the tubular portion 31 of the motor housing 30 at a predetermined distance in the vertical direction. Side handle mounting holes 7a and 7b (not visible in FIG. 7) are similarly formed at the same positions on the right side surface of the tubular portion 31. The mounting portion 2a of the main housing 2 mainly forms a portion for holding the two screws 5c and 5d, but here, a cooling air shielding wall 3 extending further downward is formed. The cooling air shielding wall 3 is a portion extending downward from the vicinity of the lower end of the grip portion 2b, and the cooling air shielding wall 3 is provided on the rear side surface of the motor housing 30 by the operator's finger during work. This is to avoid touching it. The cooling air shielding wall 3 and the motor housing 30 are configured so that a gap 4 is formed in a non-contact state except for a portion fixed by screws 5c and 5d, and is configured to allow air flow in the gap. To. A plurality of slits 3a (openings) arranged in the vertical direction were formed on the diagonally rear side of the gap 4 through which the air flows. In FIG. 3, only the slit group 3a formed on the left side surface of the main housing 2 can be seen, but the slit group is also formed on the right side surface of the main housing 2. Since air is discharged from the gap 4 side to the rear of the cooling air shielding wall 3 through the slit 3a, the flow of outside air flowing on the outer peripheral surface of the motor housing 30 is good. Further, since air also flows near the coil end on the upper side of the motor housing 30 (near the upper end of the stator core 21), the cooling efficiency of the motor 10 is improved.

Wind windows 88 for communicating the inside and the outside are formed on both side surfaces of the enlarged diameter portion 2c of the main housing 2. The wind window 88 is formed to cool the heat generating element of the internal control circuit board 72 (see FIG. 1), and here, a filter 89 having a removable mesh structure is formed so as to cover the outer portion including the wind window 88. To install. The filter 89 is a member obtained by molding a metal or synthetic resin mesh with a synthetic resin frame portion, and enables air to communicate at the mesh portion.

FIG. 3 is a top view of the disc grinder 1 according to the present embodiment. The motor housing 30 is made of metal, the main housing 2 holding the motor housing 30 is made of synthetic resin, and the housing of the disc grinder 1 is formed by these two. A diameter-expanded portion 2c is formed on the rear side of the main housing 2 and away from the connection point with the motor housing 30 (on the anti-motor side) of the main housing 2, and the battery pack 200 is held. The main housing 2 is composed of three main parts, a mounting part 2a, a gripping part 2b, and a diameter-expanding part 2c, which are manufactured by molding a synthetic resin divided into two left and right parts. The left side part and the right side part of the main housing 2 are separated by a vertical plane passing through the central axis A1 and are fixed by fixing means, for example, a plurality of screws or hooking means. The mounting portion 2a is fixed to the motor housing 30 by four screws (only 5a and 5c can be seen in the figure) of a plurality of screws 5a to 5d having horizontal axes. A speed adjusting dial 79 for adjusting the rotation speed of the motor 10 is provided on the upper side of the enlarged diameter portion 2c. When an operator performs grinding or cutting work using the disc grinder 1, the gripping portion 2b is gripped with one hand (for example, the dominant hand). Therefore, the grip portion 2b is designed to have an optimum thickness so that it can be easily gripped.

The outer peripheral surface of the motor housing 30 is covered with a synthetic resin main housing 2 only on a part of the rear side surface, but in consideration of heat dissipation, the motor housing 30 is exposed directly to the outside air except for the portion where the main housing 2 is located. Be placed. The top cover 35 of the motor housing 30 has a flat upper surface, and is screwed to the tubular portion 31 (see FIG. 1) by four screws 37a to 37d along the outer peripheral edge. The wheel guard 65 has a radius larger than that of the grindstone 60 having a diameter of 100 mm, and covers the entire upper side and the outer peripheral side on the rear side of the rotation axis of the grindstone 60. There is a necessary space between the outer peripheral edge of the grindstone 60 and the inner wall surface on the outer peripheral side of the foil guard 65, and the space is configured so as to be boring with dust or the like. The wheel guard 65 is attached to the wheel guard mounting portion 46 with screws 69a and 69b (described later in FIG. 14) for fixing. The wheel guard 65 can be fixed at an arbitrary position by swinging around the rotation axis B1 (see FIG. 1), and can also be removed.

FIG. 4 is a partially enlarged view of the vicinity of the spindle 17 of FIG. 1, and FIG. 5 is an exploded view of a portion of the motor housing 30 below the motor accommodating portion 30a from the state of FIG. Since the motor housing 30 of the disc grinder 1 is hermetically sealed, the lower opening 31b of the tubular portion 31 is closed by the bottom cover 40. The bottom cover 40 is formed with a through hole 42 for passing the spindle 17 in the vicinity of the rotation axis B1, and a bearing 48 for axially supporting the rotation shaft 15 is provided on the upper portion of the through hole 42. A bearing holding cylinder 43 is formed in the center of the upper side (inside) of the bottom cover 40, and the bearing holding cylinder 43 holds the lower surfaces of the outer ring and the inner ring of the bearing 48 and the outer peripheral surface of the outer ring. Two screw holes 44a and 44b are formed on the inner peripheral side of the bottom cover 40, and the lower surface of the head of the bearing holding screws 49e and 49f screwed into the screw holes 44a and 44b is in contact with the outer ring of the bearing 48. By contacting the bearing 48, the axial movement of the bearing 48 is suppressed, and the axial movement of the rotor 11 is restricted. The bottom cover 40 has a sufficient thickness in the direction of the rotation axis B1 in order to hold the bearing 48 and to screw the bearing restraint screws 49e and 49f.

The bottom cover 40 also functions as a holding member for holding the foil guard 65. Therefore, on the lower side of the bottom cover 40, an extending portion extending downward in the central axis B1 direction, that is, a foil guard mounting portion 46 is formed. The foil guard mounting portion 46 is a portion on which a cylindrical surface is formed on the outer peripheral side. Only the spindle 17 was located inside the mounting portion of the conventional foil guard 65, but in this embodiment, the fan 50 is arranged by using the inner portion of the foil guard mounting portion 46. Here, the fan 50 is located inside (upper side) of the opening surface 46a of the foil guard mounting portion 46. The space on the anti-motor housing side of the fan 50 is covered by a foil guard 65 having an annular plate portion. Since the fan 50 is completely housed in the wheel guard mounting portion 46 in this way, the grindstone 60 is completely unintentionally intended by the operator to be outside the motor housing portion 30a of the motor housing 30. Grinding work can be performed using. The fan 50 is screwed to the spindle 17. A male screw 17a is formed on the outer peripheral surface of the spindle 17, and a female screw is formed on the inner peripheral side of the fan 50. Further, the upper end portion of the fan 50 comes into contact with the lower surface of the inner ring of the bearing 48, so that the fan 50 functions as a holding member for holding the lower side of the bearing 48.

A wheel washer 62 is interposed below the fan 50, and the wheel nut 64 is screwed (screwed) to the spindle 17 so as to sandwich the grindstone 60 under the wheel washer 62. A through hole 62a for penetrating the spindle 17 is formed inside the wheel washer 62, but a female screw is not formed in the through hole 62a. However, a detent mechanism is formed so that the fan 50 and the wheel washer 62 do not rotate relative to each other. As the wheel nut 64, the same parts as the wheel nut 347 used in the conventional disc grinder 301 can be used. A female screw is formed in the through hole 64a of the wheel nut 64, and small diameter holes 64b and 64c for engaging a dedicated tightening tool are formed on the outer side thereof.

A hexagonal hole 17c is formed at the lower end of the spindle 17. Since the disc grinder 1 of this embodiment does not have a spindle lock mechanism for loosening the wheel nut 64 (see FIG. 1) when the grindstone 60 is attached, a hexagon wrench is inserted into the hexagonal hole 17c at the tip of the spindle 17. By fixing the spindle 17 so that it does not rotate, the wheel nut 64 is tightened or loosened with another special tool. The lower opening surface 65d of the wheel guard 65 is located below the grindstone 60. The grindstone 60 is the same as that used in the conventional disc grinder 301, and a disc-shaped mounting surface 61 is provided in the center, but the mounting surface 61 is in the direction of the rotation axis B1 rather than the position of the outer edge portion of the grindstone 60. Since it is offset to one side, the lower surface of the wheel nut 64 is located above the lower end position of the grindstone 60 after the wheel nut 64 is tightened.

FIG. 5 is a developed view of the vicinity of the spindle 17 of FIG. FIG. 5 shows a state in which the wheel nut 64 is removed and the grindstone 60 and the wheel washer 62 are removed from the state shown in FIG. In the replacement work of the grindstone 60 by the operator, the wheel nut 64 can be loosened and removed, and the grindstone 60 and the wheel washer 62 can be removed by moving the grindstone 60 and the wheel washer 62 downward in the rotation axis B1 direction. The wheel washer 62 is formed on the upper side with the width across flats 63a and 63b that engage with the width across flats 58a and 58b (see FIG. 6 described later) formed on the fan 50. At this time, the fan 50 remains fixed to the spindle 17. The state of FIG. 5 shows a state in which the fan 50 is removed from the spindle 17. The removal work of the fan 50 is performed by loosening the screw tightening of the fan 50 with respect to the spindle 17 using a special tool. Since the removal work of the fan 50 can be performed without disassembling the motor housing 30, maintenance work such as replacement of the fan 50 and cleaning by removing the fan 50 becomes easy.

The extending portion 30b of the motor housing 30 is a portion for fixing the wheel guard 65, and the foil guard mounting portion 46 is formed. The wheel guard mounting portion 46 has a cylindrical shape and is integrally formed with the bottom cover 40. An opening surface 46a having a circular cross-sectional shape orthogonal to the rotation axis B1 is formed on the lower side of the wheel guard mounting portion 46. The outer edge portion of the opening surface 46a is formed with an inclined surface 46b chamfered so that air can flow smoothly toward the fan 50 from the lower direction to the upper direction of the rotation axis B1. By providing the inclined surface 46b, the distance between the outer edge portion of the opening surface 46a and the outer edge position of the wheel washer 62 can be separated, so that the inflow resistance of air to the fan 50 can be reduced. Further, the wheel guard mounting portion 46 has a small upper diameter and a lower diameter so that the mounting ring 66 and the holding ring 68 of the foil guard 65 fixed to the wheel guard mounting portion 46 do not shift downward. Is formed in an enlarged diameter so that Four air holes 47a to 47d (47d cannot be seen in the drawing) are formed at four locations in the circumferential direction of the wheel guard mounting portion 46 so as to penetrate from the inner peripheral side in the radial direction to the outer peripheral side. Here, by the rotation of the fan 50, air is sucked upward from the lower side of the spindle 17, flows from the inner side to the outer side in the radial direction along the bottom surface of the bottom cover 40, and the foil passes through the four air holes 47a to 47d. It is discharged to the outside of the guard mounting portion 46. In order to form such an air flow, a centrifugal fan that blows air outward in the radial direction is used for the fan 50.

Here, the detailed shape of the fan 50 will be described with reference to FIGS. 6 and 7. FIG. 6 is a perspective view of the fan 50 alone of FIG. 5, and FIG. 6A is a perspective view seen from below. The fan 50 is formed with a plurality of blade portions (fins) 54 extending radially outward from the inner cylinder portion 51 at the center. The fin 54 has a shape connected to the end portion on the bottom surface side in the radial direction by an annular plate portion 55. That is, the space (penetration portion) 59 between the inner cylinder portion 51 and the plate portion 55 when viewed in the radial direction and between the adjacent fins 54 when viewed in the circumferential direction becomes the air passage for the sucked wind. The lower end surface of the inner cylinder portion 51 becomes an annular mounting surface 51a, and the foil washer 62 is mounted so as to abut against the annular mounting surface 51a. The two-sided width portions 58a and 58b having parallel chamfers are formed so that the foil washer 62 does not idle with respect to the fan 50, and the corresponding parallel two-sided width portions 63a and 63b of the wheel washer 62 (FIG. 5). See).

6 (B) and 6 (C) are perspective views of the fan 50 as viewed from above. The inner cylinder portion 51 is arranged so as to extend to the upper side in the rotation axis B1 direction, but a concentric middle cylinder portion 53 is formed so as to separate a predetermined space from the inner cylinder portion 51 to the outside in the radial direction. A labyrinth groove 57 is formed between the middle cylinder portion 53 and the inner cylinder portion 51, and a cylindrical portion (labyrinth cylinder 45 shown in FIG. 5) formed around the through hole 42 of the bottom cover 40 is housed in the labyrinth groove 57. .. The bottom surface portion of the labyrinth groove 57 is an annular connecting portion 52 in which the middle cylinder portion 53 and the inner cylinder portion 51 are connected in the radial direction. An inclined portion 56 is formed in the lower portion of the connecting portion 52. The inclined portion 56 is an inclined surface formed to guide the direction of air sucked from the lower side to the upper side in parallel with the rotation axis B1 so as to be smoothly directed outward in the radial direction by the rotational force and the suction force of the fan 50. Is. Further, the upper portion of the plate portion 55 is formed with an inclined portion 55a so as to be an inclined surface that moves upward as it goes outward in the radial direction, not a plane orthogonal to the rotation axis B1. That is, the inclined portion 55a and the inclined portion 56 are formed so as to be substantially parallel conical surfaces along the flow of the sucked air, as is clear from the cross-sectional view of the fan 50 of FIG. In this way, between the blade portions 54 that are adjacent to each other when viewed in the circumferential direction of the fan 50, the inclined portions 55a and 56 that are inclined outward in the radial direction from the axial direction are formed so as to face each other on the inner peripheral side and the outer peripheral side. Therefore, it is possible to smoothly guide the direction of the air sucked from the lower side to the upper side in the direction of the rotation axis B1 toward the outer side in the radial direction.

7A and 7B are views of the fan 50 alone of FIG. 5, FIG. 7A is a bottom view, and FIG. 7B is a top view. The fan 50 is a cast product of a metal such as an aluminum alloy. As is clear from the bottom view of (A), a plate portion 55 that partially covers the bottom surface side (anti-motor housing side) of the fan 50 is formed. The plate portion 55 is an annular shape that connects the outer peripheral sides of the blade portions 54 extending outward in the radial direction, and the inclined portion 55a is formed on the upper surface side. By providing the plate portion 55 on the outer peripheral side, the inertia of the fan 50 can be secured, and it is possible to prevent the air sent outward in the radial direction from returning to the lower side. Further, by providing the plate portion 55, it is possible to reduce the possibility that foreign matter such as metal powder generated in the cutting process using the grindstone 60 directly hits the bottom surface of the motor housing 30 or the blade portion 54. Further, by providing the plate portion 55, the rigidity can be significantly increased. Further, since the size of the axial depression and the penetrating portion 59 around the blade portion 54 becomes small, it becomes difficult for foreign matter to enter the inside of the fan 50 (between the blade portions 54), for example, cutting of a relatively large size. One piece is discharged to the outside in the radial direction by the fan 50, and defects such as damage to the processed material can be suppressed.

In FIG. 7B, the blade portion 54 is arranged so as to come into contact with the upper portion of the plate portion 55. As can be seen from the top view, the projected opening area of the penetrating portion 59 seen in the direction of the rotation axis B1 is small. The fan 50 is a groove (labyrinth groove 57) that is continuous in the circumferential direction so that the space between the inner cylinder portion 51 and the middle cylinder portion 53 is recessed downward in the axial direction. The bottom surface of the labyrinth groove 57 is closed by the connecting portion 52. A labyrinth cylinder 45 (see FIG. 5) formed on the bottom cover 40 is located inside the labyrinth groove 57, but the fan 50 rotates without contacting each other. Since the labyrinth mechanism (labyrinth portion) formed by the labyrinth cylinder 45 (see FIG. 5) and the labyrinth groove 57 is formed in this way, it is possible to significantly limit the entry of air and dust into the motor housing 30.

FIG. 8 is a cross-sectional view of a portion AA of FIG. The foil guard mounting portion 46, which is an extending portion, has a tubular shape having a mounting surface 46c on the outer peripheral side, and has an opening surface 46a that opens at one end (lower end). Air holes (vents) 47a to 47d are provided on the side surface of the wheel guard mounting portion 46. When the rotating shaft 15 of the motor 10 rotates and the fan 50 rotates, the suction of the fan 50 forms a flow of cooling air from the inside of the opening surface 46a to the air holes 47a to 47d. Here, the spindle 17, the foil guard mounting portion 46, and the wheel guard mounting portion 46 show a cross section, and the other bottom cover 40 shows a bottom surface. As can be seen from the figure, the bottom cover 40 is screwed to the tubular portion 31 (see FIG. 4) by four screws 49a to 49d oriented in the direction parallel to the rotation axis B1. The wheel guard mounting portion 46 has a small gap with the spindle 17 so that dust does not enter the bearing 48. The foil guard mounting portion 46 has a cylindrical shape, and a mounting ring 66 and a holding ring 68 (both described later in FIG. 14) formed on the upper side of the wheel guard 65 are fixed to the mounting surface 46c on the outer periphery thereof. The inner space of the wheel guard mounting portion 46 is hollow.

As described above, in the present embodiment, by configuring the motor housing 30 with metal, it has become possible to provide a hand-held disc grinder 1 with a good product balance while keeping the product compact. Further, since the heat dissipation of the motor 10 is improved, the motor 10 can be efficiently cooled while the product is downsized and the motor dustproof property is achieved, and as a result, the performance of the motor 10 can be improved. Furthermore, the mass balance of the product was improved, and noise reduction (-15 dB) was achieved by adopting the direct drive method.

FIG. 9 is a cross-sectional view of a portion BB of FIG. As shown in FIG. 9, the motor housing 30 is fixed so as to be in close contact with the contact surfaces 8a and 8b formed on the mounting portions 2a of the main housing 2 at the fixing portions 31e and 31f formed on the left and right side surfaces. .. The inner cross-sectional shape of the tubular portion 31 of the motor housing 30 is circular, and the stator core 21 is inserted into the inner peripheral surface. A slot liner 22 for electrically insulating the coil 25 and the stator core 21 is interposed around the teeth 21b adjacent to the stator core 21. _{Since fins for heat dissipation are not formed inside the motor housing 30, the diameter D m of the} stator core 21 (see FIG. 1 for reference numerals) is set so that the stator core 21 and the tubular portion 31 are in close contact with each other, and the tubular portion is formed from the stator core 21. The heat transferability to 31 is improved. The stator core 21 is composed of a laminated iron core, has six teeth 21b from the cylindrical portion 21a on the outer peripheral side toward the inside, a coil 25 is wound around each tooth 21b, and the circumference of the coil 25 is made of a thermosetting resin 27. And mold. At the tip of the teeth 21b, an inner magnetic core portion 21c that extends in the circumferential direction along the outer peripheral surface of the stator is formed. A rotor 11 having a permanent magnet 13 is attached to the rotating shaft 15. The rotor 11 is composed of a rotor core 12 and a cylindrical permanent magnet 13 provided on the outer peripheral surface of the rotor core 12. The permanent magnet 13 is a magnet in which the magnetic flux is reversed in the radial direction, and is convenient because the magnetic flux does not flow to the rotating shaft 15 serving as the rotor shaft and the rotating shaft 15 is less likely to be magnetized.

A gap 4 is provided between the rear side of the tubular portion 31 and the synthetic resin main housing 2 so as to be in a non-contact state. The gap 4 communicates in the direction of the rotation axis B1 (see FIG. 1), and air can flow upward in the main housing 2 in the gap 4. By forming the gap 4 in this way, the heat from the tubular portion 31 is less likely to be transferred to the hand of the operator who grips the grip portion 2b. Further, since the cooling air shielding wall 3 is made of synthetic resin and has a smaller thermal conductivity than metal, it serves as a heat protective wall transferred from the mounting portion 2a to the operator.

The left and right sides of the tubular portion 31 are formed to be thick in the radial direction, and recesses 32a and 32b as key grooves continuous in the rotation axis B1 direction are formed. Further, keys 21d continuous in the rotation axis B1 direction are formed at two locations on the outer circumference of the stator core 21. Here, a gap is formed between the recesses 32a and 32b of the cylindrical portion 31, but the stator core 21 is prevented from rotating in the circumferential direction by filling the cylindrical portion 31 with the thermosetting resin 27 as well. While holding it, the thermal conductivity from the stator core 21 to the cylindrical portion 31 is enhanced.

FIG. 10 is a side view showing only the rotor 11 in the vertical cross-sectional view of the disc grinder 1 of FIG. The foil guard mounting portion 46, which is the extending portion 30b of the motor housing 30, has a substantially cylindrical shape and is integrally with the closing surface (bottom cover 40) of the lower opening of the tubular portion 31 of the metal motor housing 30. It is formed. A foil guard 65 is attached to the foil guard attachment portion 46. Air holes 47a to 47d (47c and 47d cannot be seen in the figure) are formed in the vicinity of the connection portion between the wheel guard mounting portion 46 and the motor housing 30 to penetrate from the inside to the outside in the radial direction in order to exhaust the exhaust air. To. The extension portion 30b of the motor housing 30 is a portion in which the cylindrical center line extends coaxially with the rotation axis B1. This extending direction is a direction orthogonal to the central axis A1 (see FIG. 1) of the grip portion 2b. A fan 50 is arranged in the internal space of the extending portion 30b, and the rotation of the fan 50 sucks air upward from the periphery of the wheel washer 62 on the grindstone 60 as shown by an arrow. The sucked air that has reached the fan 50 is discharged outward in the radial direction by the rotation of the blade portion 54, and is separated from the rotation axis B1 from the four air holes 47a to 47d (47c and 47 are not visible in the figure). It is discharged in the direction. The air discharged from the air hole 47a existing on the front side is discharged to the front side along the bottom surface of the bottom cover 40. At this time, it contributes to cooling the motor housing 30 by flowing in contact with the bottom cover 40 and taking heat away. Although not visible in FIG. 10, the air discharged to the right side from the air hole 47c provided on the right side surface and the air discharged to the left side from the air hole 47d provided on the left side side surface are the air discharged from the air hole 47a. Similarly, it flows to the right or left side along the bottom surface of the bottom cover 40, takes heat from the bottom cover 40, and contributes to cooling the motor housing 30.

A cooling air shielding wall 3 is formed on the rear side of the extending portion 30b of the main housing 2. The cooling air shielding wall 3 is formed integrally with the main housing 2 and is made of synthetic resin. A gap 4 through which air flows is formed between the motor housing 30 and the cooling air shielding wall 3, and the gap 4 is hooked so as to communicate with the inside of the motor housing 30 from the cooling air shielding wall 3. As shown in FIG. 2, a plurality of slits 3a are formed in the cooling air shielding wall 3 to allow air flow from the gap 4 to the outside of the main housing 2. The air that flows into the fan 50 as shown by arrows 98a, flows as shown by arrows 98b and 98c, and is discharged from the air hole 47b existing on the rear side flows to the rear side along the bottom surface of the bottom cover 40. It hits the cooling air shielding wall 3. The air that hits the cooling air shielding wall 3 flows while diffusing upward, right side, left side, or downward. The air that divides the space between the motor housing 30 and the cooling air shielding wall 3 in the left-right direction and is discharged from the lowermost slit 3a (see FIG. 2) as shown by the arrow 99a and flows in the left-right and upward directions is the arrow 99b. As shown in ~ 99e, it flows upward along the outer peripheral surface of the motor housing 30, passes through the slit 3a (see FIG. 2) formed in the cooling air shielding wall 3, and is discharged to the outside of the main housing 2. Although only the five exhaust airs indicated by arrows 99a to 99e have been described here, eight slits 3a are provided on the left and right sides of the mounting portion 2a of the main housing 2 as shown in the side view of FIG. 3 (see FIG. 3). Is formed. In this way, the motor housing 30 is cooled by the air flowing upward along the outer peripheral surface of the tubular portion 31 of the motor housing 30, so that heat dissipation from the stator 20 provided inside is further promoted. In FIG. 2, the air discharged from the slit 3a is represented by an arrow backward, but since the slit 3a faces the left-right direction, the air from the slit 3a mainly spreads in the left-right direction. It is devised so that it is not easily hit by the operator located behind.

The wiring from the internal space of the motor housing 30 is drawn out through the notches 33a to 33c (only 33b can be seen in the drawing) formed on the side surface of the tubular portion 31. Wiring (80c, 26b, etc.) can be arranged only in the range 84 below the inner bottom surface of the top cover 35 and above the lower end position of the notch 33b. In this embodiment, in the lower portion of this range 84, that is, within the range 84a above the lower surface of the sensor substrate 28 and the lower end positions of the notches 33a to 33c (only 33b can be seen in the figure), the inside in the radial direction. The wiring (80b, 26b, etc.) was pulled out from the outside. The coil lead wire of the lead-out position of the wiring (26b, etc.) have to overlap the scope and partially or fully cured resin portion L _r of the stator 20. As a result, the distance S between the top cover 35 and the upper end position of the thermosetting resin 27 can be reduced, so that the length of the motor housing 30 in the rotation axis B1 direction can be reduced, and a compact disk can be used. Grinder 1 has been realized.

As described above, as described with reference to FIGS. 5 to 9, in this embodiment, the motor 10 is housed inside the motor housing 30 mounted so as to be orthogonal to the main housing 2, and the tip is outside the motor housing 30. A fan 50 is provided in a portion extending to the tool side, that is, in the wheel guard mounting portion 46. With this configuration, the motor housing 30 can be effectively cooled by the air flow generated by the fan 50. Further, heat from the heat generating portion of the motor 10, particularly the stator 20, can be dissipated through the motor housing 30. Further, since the wiring is pulled out from the inside of the main housing 2 so as to penetrate the cylindrical surface on the side surface of the motor housing 30, the size of the motor housing 30 in the rotation axis B1 direction can be reduced.

11 and 12 are views for explaining the procedure for attaching the motor housing 30 of the stator 20 to the tubular portion 31. The upper side of FIG. 11A is a side view showing a state in which the stator 20 is assembled. First, the stator 20 is assembled by winding the coil 25 around the stator core 21. The method of forming the coil 25 is the same as that of the conventional brushless DC motor. Synthetic resin insulators 23 and 24 are attached to the upper and lower ends of the stator core 21, and the teeth 21b of the stator core 21 (see FIG. 11). ) Is surrounded by six wound portions (not shown) on the six teeth 21b. The insulators 23 and 24 are non-magnetic materials and non-conductors for electrically insulating the coil 25 and the stator core 21, and are made of, for example, a synthetic resin. A cylindrical portion having substantially the same shape as the stator core 21 is formed on the outer peripheral side of the insulators 23 and 24, and a plurality of winding portions are formed from the cylindrical portion inward in the radial direction. The projected shapes of the insulators 23 and 24 as viewed from the axial direction of the rotation axis B1 are substantially the same as the projected shapes of the stator 20. After the synthetic resin insulators 23 and 24 are provided in this way, a copper enamel wire is used as the electric wire to be wound, and the enamel wire is used from the winding portion of the upper insulator 23 to the winding portion of the lower insulator 24. By turning around the teeth part of the lower insulator 24, it folds back from the bottom to the top, and turns around the teeth part of the upper insulator 23 to form a single winding. By repeating 10 to several tens of times, multiple rolls of one tooth are formed. Here, in order to form a three-phase delta connection, the coil 25 for one phase is formed by continuously forming two teeth with one enamel wire. When the coil is formed using the six teeth in this way, the coil 25 for three phases is formed, and six coil leader wires (26b, 26e, etc.) are formed. The six leader lines (only 26b and 26e can be seen in the figure) are not connected, but are bundled and stretched in the radial direction (direction orthogonal to the rotation axis B1) from the vicinity of the upper end of the coil 25.

Next, the tubular portion 31 is positioned below the stator core 21 around which the coil 25 is wound, and the stator core 21 is inserted into the tubular portion 31. The size of the stator core 21 is adjusted so that it fits well on the inner wall surface of the tubular portion 31 except for the key 21d (see FIG. 9), thereby improving the accuracy of centering the tubular portion 31 and the stator core 21. Is good. Two keys 21d (see FIG. 9) are formed at positions facing 180 degrees on the outer peripheral surface of the stator core 21. On the other hand, since the tubular portion 31 is formed with a vertical recess 32a (see FIG. 9) for accommodating the key 21d, the key 21d is set to fit inside the recess 32a. In this way, the stator core 21 in which the coil 25 is wound is positioned inside the tubular portion 31, and the coil leader wires 26b, 26e, etc. are inserted from above to below the notch portions 33b, etc. from the inside. Penetrate outward. The notch 33b is formed so as to be continuous downward in the rotation axis B1 direction from the upper opening 31a of the tubular portion 31 together with the adjacent notches 33a and 33c (see FIGS. 22 and 24 described later). Is. FIG. 11B shows a state in which the stator 20 is inserted into the tubular portion 31 of the motor housing 30 in this way. In this state, the stator 20 is temporarily fixed to the tubular portion 31.

Next, the convex mold 160 is inserted from the lower side of the assembly in the state (B). The mold 160 is a molding mold, which is a jig used when a liquid thermosetting resin 27 is filled around the coil 25 and cured, and is mounted inside the stator 20 instead of the rotor 11. Will be done. Here, the central axis of the tubular portion 31 is positioned so that the rotation axis B1 direction faces vertically, and a mold 160 having a shaft portion and a convex portion upward from the lower side to the upper side of the tubular portion 31 is inserted. And temporarily fix it. The mold 160 has a disk-shaped large-diameter portion 161 that serves as a pedestal, a columnar medium-diameter portion 162 formed in a convex shape upward from the large-diameter portion 161, and an axial center position of the upper surface 162a of the medium-diameter portion 162. It is composed of a shaft-shaped small diameter portion 163 extending upward from the. The lower opening 31b of the tubular portion 31 is positioned on the upper surface 161a of the large diameter portion 161. The outer peripheral surface of the medium diameter portion 162 is in close contact with the inner wall of the tubular portion 31, and the upper surface 162a determines the downward position of the stator 20. A plurality of ribs 24a for positioning are formed on the lower insulator 24 in the circumferential direction, and the ribs 24a come into contact with the upper surface 162a so that the positions of the stator core 21 and the tubular portion 31 are accurately positioned. The mold 160 is a jig having a rotationally symmetric shape about the rotation axis B1, the small diameter portion 163 is used to fill the accommodation space of the rotor 11, and the medium diameter portion 162 is a liquid thermosetting resin 27. It is used as the bottom surface when flowing. The mold 160 is made of, for example, a steel material, and is removed after the thermosetting resin 27 is cured. If a chemical such as a mold release agent is applied to the outer peripheral surface of the small diameter portion 163 and the upper surface of the medium diameter portion 162 before setting the mold 160 as shown in FIG. 11C, after curing, The mold 160 can be smoothly taken out from the thermosetting resin 27 of the above.

Next, as shown in FIG. 12A, the liquid thermosetting resin 27 is poured into the tubular portion 31 from above. The thermosetting resin 27 is filled in the space in which the coil 25 of the stator core 21 is accommodated, and then cooled. The thermosetting resin 27 has adhesiveness and insulating properties after curing, and has sufficient strength. Further, since the thermosetting resin 27 is a non-magnetic material, it has almost no effect on the magnetic field generated by the motor 10. Here, by using a thermosetting resin 27 having particularly high thermal conductivity, the heat generated in the coil 25 and the stator core 21 can be transferred to the tubular portion 31 of the motor housing 30 via the thermosetting resin 27. did. That is, the coil 25 and the inner cylinder surface of the motor housing 30 are connected by the thermosetting resin 27, and here, a thermosetting resin having a thermal conductivity of 1.0 W / m · K or more is used. In this embodiment, an epoxy resin of about 2.0 to 4.0 W / m · K is used in particular. It should be noted that the higher the thermal conductivity, the higher the cooling effect, so that it is more preferable if it is 4.0 W / m · K or more, but the higher the thermal conductivity, the worse the fluidity, so the fluidity (assembly). It is important to select the thermosetting resin 27 in consideration of the property). The commercially available thermosetting resin 27 achieves a desired thermal conductivity by filling the matrix resin with an inorganic filler called a filler. For example, in an epoxy resin of 2.0 or 4.0 W / m · K, alumina (Al ₂ O ₃ ) having a thermal conductivity of 15 to 30 W / m · K is used as a filler.

The portion hardened by the thermosetting resin 27 is the entire space located on the outer side in the radial direction from the cylindrical virtual surface connecting the innermost peripheral positions of the teeth 21b (see FIG. 9) of the stator core 21 in the radial direction. The liquid of the thermosetting resin 27 also comes into contact with the exposed inner wall surface of the tubular portion 31. In this way, the thermosetting resin 27 is poured into the tubular portion 31 so that the upper liquid surface 27a completely buries the coil 25. At this time, it is preferable that the upper end position of the lead-out position of the coil leader lines 26a to 26f is within the liquid level. If the upper end position of the thermosetting resin 27 is fixed so as not to move substantially even if the coil 25 and the take-out portions of the coil leader wires 26a to 26c are not completely buried, FIG. The liquid level 27a may be slightly below the position (A). By using the thermosetting resin 27 as described above, the gap between the outer peripheral surface of the stator core 21 and the inner wall surface of the tubular portion 31 is completely filled and hardened by the thermosetting resin 27.

Next, in the state of FIG. 12A, the thermosetting resin 27 is cured by putting it in a furnace and maintaining it at about 100 degrees. This curing step takes, for example, about 5 hours. After the thermosetting resin 27 is cured, the mold 160 is pulled downward from the assembly of the tubular portion 31 and the stator 20 as shown in FIG. 12 (B). Since the thermosetting resin 27 has adhesiveness, the stator core 21, the insulators 23, and 24 including the coil 25 are strongly fixed to the tubular portion 31. In this way, the coil 25 is continuously covered with the thermosetting resin 27 from one end side (lower side) to the other end side (upper side) in the rotation axis B1 direction. The inner peripheral portion 27c hardened with the thermosetting resin 27 has a smooth cylindrical surface with no step in the circumferential direction. The lower surface 27b and the upper surface (liquid surface 27a) are planes orthogonal to the rotation axis B1. Since the hardened thermosetting resin 27 is sufficiently hard, has withstand voltage and heat resistance, the coil 25 and the cylindrical surface 31 can be communicated with each other by a resin for heat transfer, and the durability of the motor 10 is greatly improved. Can be enhanced.

The rotor 11 fixed to the sensor substrate 28 and the rotating shaft 15 was subsequently inserted into the assembly of the tubular portion 31 and the stator 20 in the upper state of FIG. 12B to fix the bearings 38 and 48. The top cover 35 and the bottom cover 40 are attached. The sensor substrate 28 (not shown in FIG. 12) is fixed by substrate holding ribs 23d and 23e (described later in FIG. 22) formed on the upper insulator 23. After that, the top cover 35 and the bottom cover 40 (not shown) are fixed to the tubular portion 31. The assembly of the motor housing 30 is manufactured by the above steps. In this assembly, the lead wires 26a to 26f of the coil and the signal lines 80a to 80e from the sensor substrate 28 are drawn out to the rear side of the tubular portion 31. The connection and wiring on the tip side of the coil leader lines 26a to 26f and the signal lines 80a to 80e are performed outside the motor housing 30 and in the inner space of the main housing 2 as described later in FIGS. 20 to 24. Therefore, the space of the motor housing 30 required for connection and wiring can be reduced, and the increase in size of the motor housing 30 can be suppressed.

FIG. 13 is the same diagram as FIG. 10, and is a diagram for explaining a heat transfer path. The arrows shown here indicate a state in which the heat generated from the stator core 21 and the coil 25 is transmitted to the metal portion and dissipated to the air flow. Heat transfer extends from the source to the lower temperature of the metal part. The coil 25 of this embodiment is connected and fixed to the tubular portion 31 of the motor housing 30 by the thermosetting resin 27. Further, since the thermosetting resin 27 is cured so as to completely include the coil 25 portion, the heat generated from the stator core 21 and the coil 25 is immediately transferred to the tubular portion 31. Since the tubular portion 31 is exposed to the outside air, the tubular portion 31 itself has a heat dissipation effect, but heat is transferred to the bottom cover 40 side, which has a low temperature. Here, since the lower end position of the thermosetting resin 27 is installed so as to face the bottom cover 40 and the bearing holding screws 49e and 49f provided on the bottom cover 40 in close proximity to each other, the cylindrical portion from the thermosetting resin 27 The heat dissipation to the bottom cover 40 is improved via the 31. A cylindrical foil guard mounting portion 46, which is a portion extending downward, is formed on the bottom cover 40, and the foil guard 65 is mounted therein.

Since the foil guard 65 is formed of a thin iron plate and has a large surface area, it has a high heat dissipation effect, and its temperature is closest to the outside air temperature as compared with the tubular portion 31 and the foil guard mounting portion 46. Therefore, the heat transferred to the bottom cover 40 is transferred to the foil guard 65. In this way, the heat generated by the motor 10 is transferred to the wheel guard 65, and the heat is effectively released in the process. Further, since the grindstone 60 rotates at high speed inside the wheel guard 65, the wind generated by the grindstone 60 during the work effectively cools the wheel guard 65. Further, since the fan 50, which is provided coaxially with the spindle 17 and rotates with the rotation of the motor 10, is provided, it is transmitted to the tubular portion 31 → the bottom cover 40 → the foil guard 65 by the flow of air generated by the fan 50. It is possible to effectively dissipate heat into the outside air in the middle of the heat transfer path. In FIG. 13, the heat downward from the tubular portion 31 is indicated by an arrow, but when the temperature on the top cover 35 side is lower than that on the tubular portion 31, the heat is transferred to the top cover 35 side and is transmitted from the top cover 35. The phenomenon of heat dissipation also occurs.

The coil leader line 26b and the like and the signal line 80c and the like are pulled out in the range between the lower surface of the sensor substrate 28 and the lower end position of the notch 33b, that is, the portion described as “wiring lead-out range” in the drawing. The notched portions 33a to 33c above the upper surface of the thermosetting resin 27 are in a state of leaving an opening portion with the top cover 35 covered. Therefore, the airtightness is ensured by filling the resin in the vicinity indicated by the dotted line 85. The resin of the dotted line 85 (second resin) does not have to be thermosetting, as long as good airtightness and durability can be ensured. Therefore, a resin different from the thermosetting resin 27 may be applied. Of course, the thermosetting resin 27 may be used to seal the seal. The lower end positions of the cutout portions 33a to 33c are located below the upper end positions of the thermosetting resin 27. Accordingly, the rotation axis direction B1 in the range of resin curing portion L _r of the wiring drawing range and the stator 20, a positional relationship partially overlap.

FIG. 14 is a perspective view of the foil guard 65 of FIG. 1 alone. The foil guard 65 is made of metal so as to have sufficient strength, and is manufactured here by pressing an iron plate. The purpose of the wheel guard 65 is to cover about half of the rotation range of the grindstone 60 that rotates around the spindle 17, and to serve as a cover that prevents the grindstone 60 from being touched from the outside. It plays a role of guarding the generated cutting powder from scattering to the operator side. The wheel guard 65 includes a diameter-expanded upper surface 65a extending horizontally from the mounting ring 66 for half a circumference, a semi-cylindrical outer cylinder surface 65b extending downward from the outer edge of the diameter-expanded upper surface 65a, and an outer cylinder. It has a folded-back portion 65c that is slightly folded back with the lower opening of the surface 65b facing inward. The mounting ring 66, the enlarged diameter upper surface 65a, the outer cylinder surface 65b, and the folded portion 65c can be formed by pressing a metal plate. Nuts 67a and 67b are welded to both ends of the mounting ring 66 in the circumferential direction. The holding ring 68 is a component corresponding to the mounting ring 66 for half a circumference, has bent portions and through holes at both ends in the circumferential direction, and screws 69a and 69b are passed through the through holes. By arranging the mounting ring 66 and the holding ring 68 on the outer peripheral side of the wheel guard mounting portion 46 and screwing the screws 69a and 69b into the nuts 67a and 67b, the foil guard 65 is attached to the foil guard mounting portion of the bottom cover 40. It is fixed to 46.

As described above, in the disc grinder 1 of the present embodiment, a circular tip tool (grinding stone 60) is attached to the spindle 17, and the grindstone 60 is partially covered with a protective cover (foil guard 65). The motor housing 30 has a support portion (foil guard mounting portion 46) for fixing the wheel guard 65, and the fan 50 has a base portion (inner cylinder portion 51, connecting portion 52) fixed to the spindle 17. The blade portion 54 extends radially from the base portion, and is arranged so that at least a part of the blade portion 54 is located inside the support portion. With this configuration, the motor 10 can be effectively cooled without flowing air for cooling inside the motor housing 30, so that a power tool having a sealed motor housing 30 can be realized. Further, since the stator core 21 and the coil 25 are firmly fixed by the thermosetting resin 27 having high thermal conductivity, good thermal conductivity to the tubular portion 31 can be realized, vibration resistance is strong, and reliability and life are greatly extended. It became possible to improve.

Next, a modified example of this embodiment will be described with reference to FIG. FIG. 15 is a horizontal cross-sectional view of a portion corresponding to the BB portion of FIG. Here, a metal spacer 127 extending in the axial direction is inserted in a space between adjacent teeth 21b of the stator core 21 and filled with the thermosetting resin 27. The spacer 127 is preferably made of a non-magnetic material so as not to affect the magnetic field generated by the stator core 21. Further, it is preferable to use a material having better heat conduction characteristics than the thermosetting resin 27 having good heat dissipation. Here, as the spacer 127, a plate-shaped block made of an aluminum alloy is used, and the spacer 127 is arranged between the teeth 21b before filling the thermosetting resin 27 shown in the step of FIG. 11C, or Before completing the filling of the thermosetting resin 27 shown in FIG. 12 (A), the spacer 127 is inserted into the thermosetting resin 27, and then the thermosetting resin 27 is filled to a specified position. .. By using the spacer 127 of this modification, the required filling amount of the thermosetting resin 27 can be saved. Further, by using the spacer 127 which is superior in thermal conductivity characteristics to the thermosetting resin 27, the thermal conductivity from the stator 20 to the tubular portion 31 can be further improved. The spacer 127 is not limited to the metal one. As long as it is a material having good heat conduction characteristics and is a non-magnetic material, it may be another member such as ceramic.

FIG. 16 is a diagram for explaining a method of assembling the rotating shaft 15 and the permanent magnet 13 of FIG. In this embodiment, a cylindrical permanent magnet 13 is used as the permanent magnet attached to the rotor 11. Further, a "polar anisotropic magnet" having a characteristic in the magnetizing direction of the permanent magnet 13 is used so that the rotating shaft 15 located inside the permanent magnet 13 is not easily magnetized. A spindle 17 serving as an output shaft is connected to the lower end of the rotating shaft 15 serving as a rotor shaft. The rotating shaft 15 and the spindle 17 may be separated from each other by using a connecting joint or being connected by a fitting portion, but in this embodiment, the rotating shaft 15 and the spindle 17 are manufactured as an integral metal product. did. In this embodiment, both the rotating shaft 15 and the spindle 17 are made of steel. Therefore, when a conventional permanent magnet is used, the magnetic flux generated by the permanent magnet reaches the inside of the rotating shaft 15, so that the rotating shaft 15 and the spindle are used. There is a risk that 17 will be magnetized. In the disc grinder 1, a grindstone 60 may be attached to the spindle 17 as a tip tool to grind iron, and when the spindle 17 is magnetized when iron powder or the like is scattered, the spindle is particularly good. Iron powder is adsorbed on the tip (bottom) of the wheel. The magnetic field that magnetizes the spindle 17 is due to the permanent magnet 13, and does not disappear even after the rotation of the motor 10 is stopped. Therefore, the iron powder adsorbed on the spindle 17 remains attached, which is not preferable in terms of operation. Therefore, in the rotor 11 of the present embodiment, the magnetic flux penetrates linearly in the radial direction instead of the permanent magnet 230 (described later in FIG. 19) in which the magnetic flux penetrates in the radial direction conventionally used as the permanent magnet 13. No polar anisotropy magnets 131 to 133 are used.

Each of the permanent magnets 13 (131 to 133) has a circular tube shape, and forms a magnetic path that does not use the rotor core (or sleeve 16) as a magnetic path. The magnetic path is magnetized so that it goes from the outer side in the radial direction to the inner side, reverses inward, and goes outward in the radial direction again. The permanent magnet 13 is composed of three parts. Ideally, it is preferable to use a polar anisotropic magnet that is sufficiently long in the axial direction as if the permanent magnets 131 to 133 were integrally formed. However, since the permanent magnets 131 to 133 are manufactured by baking the magnets using a mold, they cannot be sintered so as to have the same magnetic flux as the length of the cylindrical portion becomes long. Further, even if a magnet having an ideal magnetic flux can be manufactured, the manufacturing cost increases significantly when a polar anisotropic magnet long in the axial direction is manufactured. Therefore, in this embodiment, three small permanent magnets 131 to 133 are arranged side by side in the axial direction. For example, by using three permanent magnets 131 to 133 having an axial length of 17 mm, a permanent magnet 13 having an axial length of 51 mm could be realized.

The rotating shaft 15 of the motor 10 has two bearing holding portions 15c and 15d formed at both ends of a spindle portion 15a located inside the permanent magnet 13. The outer peripheral surface of the upper bearing holding portion 15d is fixed to the inner ring of the ball-type bearing 38 (see FIG. 1), and the upper end of the rotating shaft 15 is pivotally supported by the top cover 35 via the bearing 38. The lower bearing holding portion 15c is fixed to the inner ring of the ball-type bearing 48 (see FIG. 1), and the lower side of the rotating shaft 15 is pivotally supported by the bottom cover 40 via the bearing 48. A spindle 17 serving as an output shaft is formed on the lower side of the rotating shaft 15. In the disc grinder 1 of this embodiment, the spindle 17 for rotating the tip tool is directly connected to the rotating shaft 15 of the motor 10 without a reduction mechanism. Therefore, in this embodiment, the rotating shaft 15 and the spindle 17 can be manufactured as an integral metal product. The rotary shaft 15 is formed by cutting a metal casting to form a spindle portion 15a, a large diameter portion 15b, and bearing holding portions 15c and 15d. Due to the ease of cutting, circumferential grooves 15f and 15e are formed between the spindle portion 15a and the bearing holding portion 15d and between the large diameter portion 15b and the bearing holding portion 15c. However, the formation of these grooves is not essential.

On the outer peripheral surface of the spindle 17, there is a male screw portion 17a on which a male screw is formed. Here, a female screw is formed on the inner peripheral surface of the fan 50 (see FIG. 7), a female screw is formed on the inner peripheral surface of the through hole of the wheel nut 64 (see FIG. 5), and these female screw portions are screwed with the male screw portion 17a. To do. The wheel washer 62 (see FIG. 5) is configured to be slidable in the axial direction of the spindle 17 because no threaded portion is formed in the through hole. Circumferential grooves 17b continuous in the circumferential direction are formed at the connection portion between the spindle 17 and the bearing holding portion 15c, which are also formed for convenience of cutting and thread cutting.

A cylindrical sleeve 16 is provided on the main shaft portion 15a of the rotating shaft 15. The sleeve 16 is provided to fill the space between the spindle portion 15a and the permanent magnet 13, and is made of a non-magnetic metal such as an aluminum alloy, and is press-fitted into the spindle portion 15a or is press-fitted into the spindle portion 15a. / And fixed by adhesion. Three permanent magnets 131, 132, 133 are inserted into the outer peripheral surface of the sleeve 16 in the axial direction, and the outer peripheral surface of the sleeve 16 and the inner peripheral surfaces of the permanent magnets 131, 132, 133 are fixed with an adhesive. Reference lines 131a, 132a, 133a indicating magnetizing reference positions are printed at one location on the outer peripheral surfaces of the permanent magnets 131, 132, and 133 so that the positions of the magnetic poles in the circumferential direction coincide with each other. These reference lines are lines indicating one of the boundary positions of the S pole and the N pole existing in four sets of permanent magnets 131, 132, 133, and by aligning these lines so as to be aligned in the direction of the rotation axis, The magnetic pole positions of the three permanent magnets 131 to 133 match.

From the state on the left side of FIG. 16, the state in which the permanent magnets 131 to 133 are fixed to the sleeve 16 is shown in FIG. 16B on the right side. The bottom surface side of the bottommost permanent magnet 133, that is, the end surface on the side close to the spindle 17, is positioned by the balancer 14 formed in an annular shape. The balancer 14 is attached to the rotating shaft 15 in order to balance the rotation of the rotor 11 to which the sleeve 16 and 131 to 133 are fixed, and is a separate brass part. After fixing the sleeve 16 and the permanent magnets 131 to 133 to the rotating shaft 15, these assemblies are rotated so that any part of the circumferential groove 14a formed on the outer peripheral surface of the balancer 14 is formed on the tip of a drill (not shown). The rotation of the rotor 11 is balanced by forming a slight recess in the radial direction. The method of balancing the rotation is the same as the known method of adjusting the rotor, and the number, position, diameter, groove depth, etc. of the drill grooves are adjusted.

FIG. 17 is a diagram showing a modified example of the permanent magnet 13 of FIG. Here, it is the same as the permanent magnets 131 to 133 shown in FIG. 16 in that three permanent magnets 134 to 136 are attached and that the permanent magnets 134 to 136 are polar anisotropic magnets having eight poles in the circumferential direction. .. The only difference is that recesses 134a to 136a and recesses 134b to 136b for positioning are formed on the outer peripheral surface of the ends of the permanent magnets 134 to 136, respectively. As described above, the permanent magnets 134 to 136 may be easily aligned by changing the appearance of the permanent magnets 131 to 133, for example, changing the shape such as unevenness, and changing the color. The recesses 134a to 136a and the recesses 134b to 136b are both provided in the manufacturing process of the permanent magnets 134 to 136.

FIG. 18 is a cross-sectional view of the DD, EE, and FF portions of FIG. 17, and is a diagram showing the directions of their magnetic fluxes with arrows. The polar anisotropic magnet has a predetermined thickness in the domain wall portion in the radial direction, and the magnetization direction of the magnetic section is gradually reversed in the domain wall so that the direction is changed by about 180 degrees. Here, eight south poles in which the magnetic field lines are directed from the outside to the inside and eight north poles in which the magnetic field lines are directed from the inside to the outside are provided. That is, when viewed only on the outer peripheral surface, there are a total of eight S-curves and N poles in the circumferential direction. In the magnets 131 to 133, the direction of the magnetic flux is reversed from the outside to the outside inside the magnet before reaching the inner peripheral surface from the outer peripheral side of the magnet, so that the magnetic field does not act on the inner peripheral side of the permanent magnets 131 to 133. .. Further, since the magnetic flux does not pass through the rotor core 12 portion (see FIG. 16) and the rotating shaft 15 portion (see FIG. 16), the magnetic flux generated when the magnetic field passes through the magnetic material is not attenuated.

FIG. 19 is a cross-sectional view showing the direction of the magnetic flux of the permanent magnet 230 of the conventional example. In the conventional permanent magnet 230, the magnetic flux direction is magnetized so as to penetrate from the radial outer side to the inner side at the S pole, and the magnetic flux direction penetrates from the radial inner side to the outer side at the N pole. Therefore, it is necessary to form a rotating shaft or a sleeve located inside the magnet 230 with a magnetic material to form a magnetic path. Normally, when a magnetic field is transmitted to the rotor core portion, the core portion has a magnetic resistance, so that the magnetic flux decreases there. When the amount of magnetic flux decreases, it becomes necessary to use a large magnet in order to obtain the required motor output, which inevitably increases the size of the motor. On the other hand, if the amount of magnetic flux to be attenuated is small, it is not necessary to increase the size of the motor. There was a strong permanent magnet in the conventional magnet type, but there was a problem that the rotation axis was magnetized when the magnetic force was increased in the conventional type. In this embodiment, the sleeve 16 can be made of an aluminum alloy by using a polar anisotropic magnet in which the magnetic field lines from the outer peripheral surface to the inner side in the radial direction are magnetized so as to be inverted before reaching the inner peripheral surface. It was. Further, the magnetization of the rotating shaft 15 and the spindle 17 is greatly suppressed, iron powder is not adsorbed on the tip of the spindle 17 which is the output shaft, and a power tool with improved reliability can be realized.

Next, a method of wiring the leader wire from the coil 25 to the outside of the motor housing 30 will be described with reference to FIGS. 20 to 22. FIG. 20 is a partially enlarged view of the coil 25 of FIG. 1 in the vicinity of the leader lines 26b and 26e. In the disc grinder 1 of this embodiment, since the closed motor housing 30 is used, the wiring of the leader lines 26a to 26c from the coil 25 and the routing of the signal lines 80a to 80e from the sensor substrate 28 become problems. A hand-held power tool that rotates a substantially disk such as a grindstone without using a speed reducer has many merits such as a small size, a thin handle, easy to grip, low noise, and a long life. In this case, if a large torque is generated only by the output of the motor 10, it is necessary to increase the exciting current flowing through the coil 25, and the coil leader wires 26a to 26c connecting the coil 25 and the inverter circuit 73 correspond to a large current. Therefore, it must be thickened. When the thick coil leader wires 26a to 26c are used and the coil leader wires 26a to 26c of the coil 25 are connected inside the motor housing 30, in order to secure a space for the connection portion, particularly an installation space for the lead wire and the insulating tube. The motor housing 30 must be enlarged.

In this embodiment, the tubular portion 31 of the motor housing 30 is provided with notches 33a to 33c for fixing the coil leader wires 26a to 26c (only 33b can be seen in the figure), and the coil leader wires 26a to 26c (FIG. Then, only 26b and 26e can be seen), and then connected to the main housing 2 side, and connected to the wirings 83a to 83c (only 83b can be seen in the figure) from the inverter circuit 73. As a wiring procedure, the two coil leader wires of each phase of the coil 25 are bundled (connected) in the main housing 2. The two bundled coil leader wires (three phases) are connected (connected) to the three wires from the inverter circuit 73, respectively. In the case of delta connection, no connection is made to create a neutral point. As described above, in this embodiment, the coil 25 and the inverter circuit 73 are electrically connected inside the outer portion of the motor housing 30, that is, the inside of the main housing 2. Further, the wiring from the sensor board 28 is also wired to the control circuit board 72 side at the outer portion of the motor housing 30. According to the configuration of this embodiment, it is possible to suppress the increase in size of the motor housing 30 in the rotation axis B1 direction, and it is possible to obtain the effect that the total height of the disc grinder 1 can be reduced.

The leader lines 26a to 26f of the coil 25 (only 26b and 26e can be seen in FIG. 20) are places drawn out from the cutouts 33a to 33c of the motor housing 30 (only 33b can be seen in the figure). It is connected at a large portion of the excess space of the main housing 2. Here, the leader lines 26b and 26e are connected to the V-phase output line 83b by utilizing the space between the screw boss 9e and the upper wall surface of the grip portion 2b. In addition, as will be described later, the leader lines 26a, 26c to 26d, 26f are also connected to the output lines 83a, 83c in the same manner. These connections can be soldered or crimp terminals can be used, but if the physical connection between the connected wires and the conductive state can be maintained stably for a long period of time, the method of connection is It doesn't matter. In FIG. 20, in addition to the connection by soldering, the connection points are covered with heat-shrinkable tubes 82a to 82c (only 82b can be seen in the figure), but insulation is achieved by connecting members other than the heat-shrinkable tubes. Is also good.

Notches (slits) 33a to 33c through which leader lines 26a to 26f pass are provided on the side surface of the tubular portion 31 of the motor housing 30 (33a and 33c are not visible in the figure). The cutout portions 33a to 33c have an opening that contacts not only the radial inner and outer surfaces of the tubular portion 31 but also the upper opening portion 31a. The opening 31a is closed by the top cover 35. That is, when the top cover 35 is attached to the tubular portion 31, the cutout portions 33a to 33c have the same shape as the through hole because the upper portion is closed. The positions of the through holes through which the wiring is passed are as described with reference to FIG. That is, it is formed so that the lower end positions of the cutouts 33a to 33c are lower than the upper end positions of the coil 25 which is the upper end surface of the stator 20. With such a positional relationship, the leader lines 26a to 26f can be easily passed from the inside of the motor housing 30 to the main housing 2 side. Further, waterproofness and airtightness are improved by applying resin 85 (see FIG. 13) to the inner portion and / or the outer portion of the cutout portions 33a to 33c. By doing so, the flow of water and air through the notches 33a to 33c can be suppressed, so that the airtightness of the motor housing 30 can be ensured.

FIG. 21 is a top view of the tubular portion 31 of FIG. 20 alone. A recess 32a extending in parallel with the rotation axis B1 is formed inside the tubular portion 31 for inserting the key 21d of the stator core 21. Further, by forming a predetermined gap between the stator core 21 and the outer peripheral surface and filling it with the thermosetting resin 27, two recesses 32b are formed to enhance the adhesive force between the stator core 21 and the tubular portion 31. Will be done. The recess 32b has a semicircular cross-sectional shape and is continuous in parallel with the rotation axis B1. Screw holes 34a to 34d are formed at four locations in the circumferential direction of the tubular portion 31.

Three notches 33a to 33c extending downward from the upper opening 31a of the tubular portion 31 are formed. The cutout portions 33a to 33c are not formed as horizontal holes formed by a drill or the like, but are formed in a slit shape from the upper side to the lower side. Therefore, the coil leader lines 26a to 26f are arranged in the orthogonal direction on the upper side. Since it is only necessary to move the motor housing 30 so as to be fitted to the lower side, the assembleability of the motor housing 30 is extremely improved. Further, since a plurality of wiring grooves, that is, cutout portions 33a to 33c for positioning the coil leader wire are provided, the coil 25 is difficult to move when the liquid thermosetting resin 27 is filled in the tubular portion 31, and the assembly work is performed. Becomes easier. _{The width W 1} seen in the circumferential direction of the cutout portions 33a to 33c is the minimum necessary width W such that a slight gap for assembly is added to the diameters of the coil leader wires 26a to 26f. For example, if the diameters of the coil leader wires 26a to 26f are D ₁ , the range may be _{D 1} ≤ W ₁ <1.5 × W _1. A film obtained by baking enamel varnish or a film made of resin is formed on the coil leader wires 26a to 26f, but it is important to prevent the coil leader wires from easily moving in the notches 33a to 33c in order to prevent disconnection. Is. FIG. 22 shows a state in which the six coil leader lines 26a to 26f are pulled out in this way.

FIG. 22 is a top view of the state in which the stator 20 is attached to the tubular portion 31 of FIG. 21, and is also a top view of the state of FIG. 12 (B). Inside the tubular portion 31, a stator core 21 (not visible in the figure), a lower insulator 24 (not visible in the figure, see FIG. 12), and an upper insulator 23 are housed. Here, the detailed illustration of the coil main body portion around which the coil 25 is wound is omitted, and the leader lines 26a to 26f are illustrated. The shape of the upper insulator 23 in the radial direction is determined so as to have the same cross-sectional shape as that of the stator core 21. The insulator 23 is provided with two substrate holding ribs 23d and 23e for holding the sensor substrate 28 (see FIG. 20). The substrate holding ribs 23d and 23e are mounting bases for holding the sensor substrate 28 at a position separated from the permanent magnet 13 of the rotor 11 by a predetermined distance, and have screw holes for screwing.

Since the coil 25 is wound around the stator 20, a total of six coil lead wires 26a to 26f are drawn out from each tooth portion for three phases. Here, the U-phase coil leader wires 26a and 26d are arranged in the notch 33a, the V-phase coil leaders 26b and 26e are arranged in the notch 33b, and the W-phase coil leaders 26b and 26e are arranged in the notch 33c. Coil leader lines 26c and 26f are arranged. The coil leader lines 26a and 26d are connected to the V-phase output line 83a of the inverter circuit by soldering or the like. The connection points are insulated by covering with a heat shrinkable tube 82a. Similarly, the coil leader wires 26b and 26e are connected to the W phase output wire 83b of the inverter circuit and covered with the heat shrink tube 82b. The coil leader wires 26c and 26f are connected to the W phase output wire 83c of the inverter circuit and covered with the heat shrink tube 82c.

FIG. 23 is a circuit diagram of the drive control system of the motor 10 of the disc grinder 1 of this embodiment. The inverter circuit 73, the constant voltage power supply circuit 77, and the calculation unit 75 shown in this circuit diagram are mounted on the same control circuit board 72 (see FIG. 1). The output of the battery pack 200 is input to the inverter circuit 73. The inverter circuit 73 includes six switching elements Q1 to Q6, and the switching operation is controlled by gate signals H1 to H6 supplied from the control signal output circuit 76 according to an instruction from the calculation unit 75. The inverter circuit 73 includes six switching elements Q1 to Q6 connected in a three-phase bridge type. Here, the switching elements Q1 to Q6 are MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), but IGBTs (Insulated Gate Bipolar Transistors) may be used.

Each drain or each source of the six switching elements Q1 to Q6 of the inverter circuit 73 is connected to the U phase, V phase, and W phase of the delta-connected coil 25. The drain terminals of the switching elements Q1 to Q3 are commonly connected to the positive electrode side of the battery pack 200. On the other hand, the drain terminals of the switching elements Q4 to Q6 are connected to the V-phase, U-phase, and W-phase terminals of the motor, respectively. Here, the coil leader lines 26a and 26d are connected to the U-phase output line 83a at the connection point 81a, the coil leader lines 26b and 26e are connected to the V-phase output line 83b at the connection point 81b, and the coil leader lines 26c and 26e are connected. Is connected to the W phase output line 83c at the connection point 81c.

Inside the stator 20 of the motor 10, the rotor 11 having the permanent magnet 13 rotates. By detecting the position of the permanent magnet 13 of the rotor 11 with the three hole ICs 29 which are the rotation position detection elements, the calculation unit 75 can detect the rotation position of the motor 10.

The calculation unit 75 is a control means for controlling the on / off and rotation of the motor, and is configured by incorporating a microcomputer. The calculation unit 75 controls the rotation speed of the motor 10 based on the start signal input when the switch 92 for turning on / off the motor 10 is operated and the variable resistance signal set by the speed adjustment dial 79, and controls the coil. The energization time and drive voltage of U, V, and W are controlled. The calculation unit 75 outputs a signal for controlling the drive signals H1 to H6 output to each gate of the six switching elements Q1 to Q6 of the inverter circuit 73 to the control signal output circuit 76.

The switching elements Q1 to Q6 perform a switching operation based on the drive signals H1 to H6 input from the control signal output circuit 76, and apply the DC voltage supplied from the battery pack 200 to three phases (U phase, V phase, and W phase). ) The voltage Vu, Vv, Vw is supplied to the motor 10. The magnitude of the current supplied to the motor 10 is detected by the calculation unit 75 by detecting the voltage values across the shunt resistor 78 connected between the battery pack 200 and the inverter circuit 73. A predetermined current threshold value corresponding to the set rotation of the motor 10 is preset in the calculation unit 75, and when the detected current value exceeds the threshold value, the switching operation of the inverter circuit 73 is performed in order to stop the driving of the motor 10. To stop. As a result, the occurrence of burning or the like due to the overcurrent flowing through the motor 10 is prevented.

The constant voltage power supply circuit 77 is a power supply circuit that is directly connected to the output side of the battery pack 200 and supplies a stabilized reference voltage (low voltage) direct current to the arithmetic unit 75 composed of a microcomputer or the like. The constant voltage power supply circuit 77 includes a diode, an electrolytic capacitor for smoothing, an IPD circuit, a regulator, and the like.

FIG. 24 is a side view of the motor housing 30 showing the drawing conditions of the coil leader lines 26a to 26f and the signal lines 80a to 80e from the tubular portion 31 of FIG. 21. As described above, there are six leader wires (coil leader wires) from the coil 25, and two of them are arranged from the bottom surface side of the notch portions 33a to 33c, respectively. The signal lines from the Hall IC 29 are three signal lines 80a to 80c from the three Hall elements, and a common power supply signal line 80d and a ground signal line 80e not shown in the circuit diagram of FIG. 23. There will be a total of five. Here, one signal line 80b is arranged in the central notch 33b, and two signal lines 80a, 80c to 80e are arranged in the remaining notches 33a, 33c. After wiring to the notch portions 33a to 33c in this way, the remaining space where the leader line of the notch portions 33a to 33c is not located is sealed by filling the portion indicated by the dotted line 85 with resin from the inside of the cylindrical portion 31. To do. Finally, the upper end opening 31a of the tubular portion 31 is covered with the top cover 35 to close the upper end opening of the cutout portions 33a to 33c. Since the top cover 35 is provided with the insertion portion 36 as shown by the dotted line, the upper ends of the cutout portions 33a to 33c are surely closed. Further, the space where the coil leader lines and signal lines of the cutout portions 33a to 33c are not located is closed by the resin 85. The purpose of the resin 85 is to maintain airtightness, and the need for having thermal conductivity is low. Therefore, a resin having a low thermal conductivity (second resin), which is different from the thermosetting resin 27, may be used.

As described above, since the connection processing for the delta connection of the coil leader wires 26a to 26f and the connection to the inverter circuit 73 (see FIG. 23 described later) are performed outside the motor housing 30, the assembleability of the motor 10 is very difficult. Get better. Further, by making the connection inside the main housing 2, the space required for the connection inside the motor housing 30 can be saved. Further, since the main housing 2 is a left-right split type, the coil leader wires 26a to 26f are connected in the housing on one side, and other wiring, the inverter circuit 73, the switch 92, etc. are arranged, and then the other one is arranged. Since it is sufficient to cover the housing and fix it with screws 5e to 5g or the like, a special process is not required for wiring, and the power tool assembly efficiency is good. Further, since the electrical connection is made not inside the metal motor housing 30 but inside the resin main housing 2, there is no risk of electric leakage from the connection portion to the motor housing 30, and reliability is improved. To do.

The above method of arranging the coil leader wire from the motor housing 30 does not presuppose that it is a direct drive type power tool as in this embodiment. For example, regardless of whether the shape of the motor is a brushless DC motor or not, regardless of the type of the other motor, the lead wire of the coil and the power supply to the motor and the peripheral circuit of the motor are supplied to the outside of the sealed motor housing 30. A wire or a signal wire may be extended and wired in the main housing 2. With such a configuration, the same effect that the accommodation space inside the motor housing can be reduced can be obtained.

Although the present invention has been described above based on Examples, the present invention is not limited to the above-mentioned Examples, and various modifications can be made without departing from the spirit of the present invention. For example, in the above example, a disc grinder has been described as an example of a power tool, but the same can be applied not only to a disc grinder but also to a polisher or a cutting machine using a disk-shaped tip tool.

FIG. 27 is a front side view of a circular saw 101 (cutting machine) which is a modified example of the present invention. The circular saw 101 has a motor housing 130 and a handle housing 102 connected to the top of the motor housing 130. Similar to the disc grinder 1, the motor housing 130 has a tubular portion 131 having a metal tubular integrated structure, and a cover 135 and a cover 140 for closing the openings at both ends thereof. The motor housing 130 has a closed structure so that active air exchange with the outside is not performed. A motor 10 (brushless motor) having a rotor 11 and a stator 20 is housed inside the motor housing 130, and the rotor 11 is provided with a rotating shaft 115 that rotates integrally. The gap between the stator coil 20 and the motor housing 130 is filled with a thermosetting resin 27 having high heat dissipation, and the entire coil 25 is covered with the thermosetting resin 27. The cover 135 and the cover 140 are made of metal so as to efficiently absorb the heat of the tubular portion 131 that has absorbed the heat of the motor 10. A saw blade 150 is attached to the tip of the rotating shaft 115, and the saw blade 150 is sandwiched between a washer 152 and a flange 154 and fixed to the rotating shaft 115. The cover 140 extends upward so as to cover the left side surface of the saw blade 150. The saw blade 150 has a circular shape, and the cover 140 covers the entire left side surface of the portion located above the rotation shaft 115 of the saw blade 150. The cover 140 is provided with a saw cover 155 that partially covers the upper and right side surfaces of the saw blade 150. The saw cover 155 is made of metal and can efficiently absorb the heat of the cover 140. Inside the motor housing 130, a sensor substrate 128 capable of detecting the rotational position of the rotor 11 is provided. A base 139 is provided below the motor housing 130, and the circular saw 101 can cut the processed material by sliding the lower surface of the base 139 on the surface of the processed material such as wood.

The circular saw 101 also uses the same motor 10 as the disc grinding machine 1, but has a direct drive system in which the motor housing 130 has a sealed structure, and has the same effect as the disc grinding machine 1. The circular saw 101 does not have a fan, but since the saw blade 150 has a relatively larger diameter than the grindstone 60, an air flow is generated by the saw blade 150 rotating at high speed, and the air flow is generated. This is because the cover 140 and the saw cover 155 can be effectively cooled, so that the need for providing a fan is reduced. Since the size of the entire product, especially the left-right direction, can be made compact because there is no fan, a fan similar to the disc grinder 1 may be provided if the cooling of the motor 10 is prioritized.

1 Disc grinder 2 Main housing (rear housing)
2a Mounting part 2b Grip part (handle part) 2c Diameter expansion part 2d Battery pack support member 2e Hole part 3 Cooling air shielding wall 3a Slit 4 Gap 5a to 5g Screw 7a to 7d Side handle mounting hole 8a, 8b Contact surface 9e to 9h Screw Boss 10 Motor 11 Rotor 12 Rotor Core 13, 13A Permanent Magnet 14 Balancer 14a Circumferential Groove 15 Rotating Shaft 15a Main Shaft 15b Large Diameter 15c Bearing Holding 15d Bearing Holding 15f Circumferential Groove 16 Sleeve 17 Spindle (Output Shaft) 17a Male screw part 17b Circumferential groove 17c Hexagonal hole 20 Stator 21 Spator core 21a Cylindrical part 21b Teeth 21c Inner magnetic core part 21d Key 22 Slot liner 23 Insulator (upper side)
23d, 23e Board holding rib 24 Insulator (lower side)
24a Positioning rib 25 Coil 26a to 26c Coil leader wire 27 Thermosetting resin 27a Liquid level 27b Bottom surface 27c Inner circumference 28 Sensor board 29 Hall IC
30 Motor housing 30a Motor housing part 30b Extension part 31 Cylindrical part 31a Upper opening 31b Lower opening 31e Fixing part 32a, 32b Recessed part 33a to 33c Notch part 34a to 34d Screw hole 35 Top cover 36 Insertion part 37a ~ 37d Screw 38 Bearing 39 Slot liner 40 Bottom cover 42 Through hole 43 Bearing holding cylinder 44a, 44b Screw hole 45 Labyrinth cylinder 46 Wheel guard mounting part 46a Opening surface 46b Inclined surface 46c Mounting surface 47a to 47d Air hole 48 Bearing 49a to 49d Screw 49e, 49f Bearing holding screw 50 Fan 51 Inner cylinder 51a Mounting surface 52 Connecting part 53 Middle cylinder 54 Blade (fin) 55 Plate 55a Inclined 56 Inclined 57 Labyrinth groove 58a, 58b Width 59 Penetration part 60 Bearing 60a (Bearing stone) Tip 61 (Bearing stone) Mounting surface 62 Wheel washer 62a Through hole 63a, 63b Width across flats 64 Wheel nut 64a Through hole 64b, 64c Small diameter hole 65 Wheel guard 65a Expanded upper surface 65b Outside Cylinder surface 65c Folded part 65d Lower opening surface 66 Mounting ring 67a, 67b Nut 68 Holding ring 69a, 69b Screw 70 Control unit 71 Storage case 72 Control circuit board 73 Inverter circuit 74 Cooling fin 75 Calculation unit 76 Control signal output circuit 77 Voltage power supply circuit 78 Shunt resistance 79 Speed adjustment dial 80a to 80e Signal line 81a to 81c Connection point 82a to 82c Heat shrink tube 83a U-phase output line 83b V-phase output line 83c W-phase output line 85 Resin 86 Rail mechanism 87 Connection terminal 88 Wind window 89 Filter 91 Switch mechanism 92 Switch 93 Plunger 94 Swing shaft 95 Paddle lever 95a Tip 95b Pressing part 96 Off-lock lever 97 Twisting coil spring 101 Round saw 102 Handle housing 115 Rotating shaft 127 Spacer 128 Sensor board 131-136 Permanent magnet (Polar anisotropic magnet) 131a to 133a Reference line 133a to 136a Recessed 135 Cover 138 Bearing 139 Base 140 Cover 148 Bearing 148a Bearing holder 150 Saw blade 151 Large diameter part 151a Top surface 152 Washer 154 Flange 155 Saw cover 160 mold (jig)
161 Large diameter part 161a Top surface (of large diameter part)
162 Medium diameter part 162a (Medium diameter part) Top surface 163 Small diameter part 200 Battery pack 201 Upper case 202 Lower case 203 Latch button 230 Permanent magnet 301 Disc grinder 302 Motor housing 302c Diameter expansion part 303 Gear case 306, 307 Umbrella gear 310 Motor 316 Spindle 325 Fan 332 Switch 335 Trigger lever 336 Off-lock lever 345 Wheel guard 346 Wheel washer 347 Wheel nut 350 Control unit A1 Center axis B1 Rotation axis C1 Center axis D _m (of motor 10) Diameter L Product total length L _S Axial length S (upper end position of thermosetting resin 27 and top cover 35) spacing U coil W (notch 33a to 33c) width

Claims (13)

A rotor using a permanent magnet, a stator in which a coil is wound around a stator core, and a brushless motor having a rotating shaft for holding the rotor.
A switch for turning the brushless motor on and off,
A housing that holds the brushless motor and the switch,
The housing has a motor housing that is isolated from the outside air and houses the brushless motor.
The stator core holds the coil, and is a power tool characterized in that the coil and the inner surface of the motor housing are connected by a curable resin having high thermal conductivity. The power tool according to claim 1, wherein the motor housing is made of metal, and the thermosetting resin has a thermal conductivity of 1.0 W / m · k or more. The power according to claim 2, wherein the curable resin is filled in a space in which the coil of the stator core is accommodated after being made to flow by applying heat, and then cured by being cooled. tool. The motor housing has a tubular portion having at least one end open and a lid portion attached to one end of the tubular portion.
The power tool according to claim 3, wherein the coil is continuously covered with the curable resin from one end side to the other end side in the axial direction of the rotating shaft. The portion to be hardened by the curable resin is characterized from a cylindrical surface connecting the innermost peripheral positions of the teeth of the stator core in the radial direction to an outer portion in the radial direction to the inner wall surface of the tubular portion. The power tool according to claim 4. The power tool according to claim 5, wherein the outer peripheral surface of the stator core and the inner wall surface of the tubular portion are in contact with each other so as to have a gap, and the gap portion is filled with the curable resin. The stator core with the coil wound is positioned inside the tubular portion.
Positioning the tubular portion so that the axial direction faces vertically, a convex jig that closes the lower side and the inner peripheral side of the tubular portion in the axial direction is inserted and temporarily fixed.
After that, the curable resin in a fluid state is poured from above around the coil, and the space between the jig and the tubular portion is filled with the curable resin until the upper end of the coil is hidden, and then the curing is performed. Cure the sex resin,
The power tool according to claim 5 or 6, wherein the stator is fixed to the tubular portion by removing the convex jig. The power tool according to claim 7, wherein the leader wire from the coil is taken out laterally in the axial direction below the upper liquid surface of the curable resin. The power tool according to claim 8, wherein the curable resin is an epoxy resin mixed with alumina having a thermal conductivity of 2.0 w / m · k or more. The power tool according to claim 9, wherein the curable resin is filled in a space between the teeth adjacent to the stator core with a metal spacer extending in the axial direction inserted. Both ends in the axial direction of the tubular portion are open,
The first lid portion that closes one opening has a through hole through which the rotating shaft penetrates, and the through hole is closed by a bearing member that pivotally supports the rotating shaft and the rotating shaft, and the tubular portion is closed. The motor housing is formed by closing the opening of the motor housing with the first lid portion.
The second lid that closes the other opening holds the second bearing member that pivotally supports the rotating shaft at the inner portion.
The power according to any one of claims 4 to 10, wherein the motor housing is formed by closing the opening of the tubular portion with the first lid portion and the second lid portion. tool. It has a handle portion connected to the motor housing and has a handle portion.
The switch is housed in the handle portion.
The leader wire from the coil is routed into the handle portion through a wiring hole provided on the side surface of the motor housing.
The power according to any one of claims 1 to 4, wherein the wiring hole through which the leader wire from the coil is penetrated is closed by the same resin as the curable resin or another resin. tool. A circular tip tool is attached to the rotating shaft.
The tip tool is partially covered with a metal protective cover
The power tool according to any one of claims 1 to 12, wherein the motor housing has a motor accommodating portion and an extending portion extending from the motor accommodating portion to support the protective cover.

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