U.S. patent application number 16/611521 was filed with the patent office on 2020-04-16 for electric tool.
This patent application is currently assigned to MAKITA CORPORATION. The applicant listed for this patent is MAKITA CORPORATION. Invention is credited to Junya INUZUKA.
Application Number | 20200119600 16/611521 |
Document ID | / |
Family ID | 64660887 |
Filed Date | 2020-04-16 |
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United States Patent
Application |
20200119600 |
Kind Code |
A1 |
INUZUKA; Junya |
April 16, 2020 |
ELECTRIC TOOL
Abstract
In the brushless motor disposed in a hammer drill, while a
stator core of a stator is formed by joining a plurality of divided
cores divided in a circumferential direction, varnishes are applied
over a coil and joining portions between the divided cores.
Inventors: |
INUZUKA; Junya; (Anjo-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAKITA CORPORATION |
Anjo-shi, Aichi |
|
JP |
|
|
Assignee: |
MAKITA CORPORATION
Anjo-shi, Aichi
JP
|
Family ID: |
64660887 |
Appl. No.: |
16/611521 |
Filed: |
June 4, 2018 |
PCT Filed: |
June 4, 2018 |
PCT NO: |
PCT/JP2018/021409 |
371 Date: |
November 7, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K 1/148 20130101;
H02K 3/34 20130101; B25D 11/00 20130101; H02K 1/18 20130101; H02K
3/522 20130101; B25F 5/00 20130101; H02K 1/185 20130101; H02K 9/06
20130101; H02K 11/33 20160101; H02K 1/16 20130101; H02K 3/46
20130101; H02K 7/145 20130101; H02K 2201/06 20130101; H02K 1/20
20130101 |
International
Class: |
H02K 1/16 20060101
H02K001/16; B25F 5/00 20060101 B25F005/00; H02K 1/18 20060101
H02K001/18; H02K 11/33 20060101 H02K011/33; H02K 3/34 20060101
H02K003/34; H02K 3/46 20060101 H02K003/46 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2017 |
JP |
2017-117093 |
Jun 14, 2017 |
JP |
2017-117094 |
Jun 14, 2017 |
JP |
2017-117095 |
Jun 14, 2017 |
JP |
2017-117096 |
Claims
1. An electric tool comprising a brushless motor including a
stator, a rotor, and a plurality of coils, the stator including a
stator core formed by laminating electromagnetic steel plates, the
rotor including a rotation shaft, the plurality of coils being
wound around the stator core via an insulating member, wherein
while the stator core is formed by joining a plurality of divided
cores divided in a circumferential direction, a varnish or an
adhesive is applied over the coils and joining portions between the
divided cores.
2. The electric tool according to claim 1, wherein the adhesive has
a high thermal conductivity.
3. (canceled)
4. The electric tool according to claim 1, wherein the coils are
wound around the respective divided cores.
5-6. (canceled)
7. The electric tool according to claim 1, wherein the stator
includes a sensor circuit board including a rotation detecting
element of the rotor, the sensor circuit board being fixed via a
plurality of fixing pins directly fixed to the stator core.
8. The electric tool according to claim 7, wherein the fixing pin
are fixed across the two adjacent divided cores.
9. The electric tool according to claim 7, wherein the fixing pins
are press-fitted to a disk made of metal disposed on an end surface
of the stator core.
10. The electric tool according to claim 1, wherein each of the
divided cores has a shape fixed with an integrally molded
resin.
11. The electric tool according to claim 1, wherein each of the
divided cores has a shape fixed with a dust core coating an outer
surface thereof.
12. The electric tool according to claim 1, wherein the respective
divided cores are fixed with a tubular fixing member made of metal
manufactured by shrinkage fitting or cold fitting.
13. The electric tool according to claim 1, wherein the respective
divided cores have joining portions inclined with respect to an
axial direction of the stator core.
14. The electric tool according to claim 1, wherein the
electromagnetic steel plates have a plate thickness of 0.25 mm or
less.
15-38. (canceled)
Description
BACKGROUND OF INVENTION
[0001] This application claims the benefits of International
Application No. PCT/JP2018/021409, filed on Jun. 4, 2018 and
Japanese Patent Application Number No. 2017-117093 filed on Jun.
14, 2017, Japanese Patent Application Number No. 2017-117094 filed
on Jun. 14, 2017, Japanese Patent Application Number No.
2017-117095 filed on Jun. 14, 2017, and Japanese Patent Application
Number No. 2017-117096 filed on Jun. 14, 2017, the entirety of
which is incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to an electric tool, such as a
hammer drill, using a brushless motor as a driving source.
BACKGROUND ART
[0003] A brushless motor (see Japanese Laid Open Patent Publication
No. 2017-35784) that is compact and excellent in durability is used
as a driving source of an electric tool. Recently, with an advance
of a performance of a battery cell serving as a power supply,
electric power input to the brushless motor has been increasing
while the brushless motor has been also required to have an
increased output.
[0004] To increase the output, thinning of electromagnetic steel
plates is considered against a high space factor of a winding wire,
an increase in size of the winding wire, and an increase in iron
loss (heat loss) in a stator core. However, as in Japanese Laid
Open Patent Publication No. 2017-35784, in the case of an
integrated stator core, a coil is forced to be formed in a narrow
space inside the stator core, making the high space factor
difficult. Additionally, a thin steel plate costs high and leads to
a cost increase without improvement of the yield.
[0005] Therefore, manufacturing a stator core by dividing the
stator core and coupling a plurality of components is considered.
Such a divided structure allows a large-sized stator core, achieves
a high space factor, and further a yield in punching of an
electromagnetic steel plate decreases and therefore a cost
reduction can be expected.
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0006] However, with an electric tool, there is a situation where a
working environment is severe, such as vibrations, dust, and an
impact due to falling. Therefore, configuring a stator core of a
brushless motor used in such a situation to be a divided structure
has possibly resulted in deterioration of durability and a
dust-proof performance.
[0007] In order to achieve downsizing and a weight reduction of the
motor, since a surface area of the motor decreases, a cooling
performance possibly gets worse. Especially, although the use of
the above-described divided cores allows downsizing of the motor
while efficiency and an output remain equivalent, the cooling
performance is difficult to be improved.
[0008] Furthermore, vibrations cause disconnection of a coil in the
electric tool in some cases, and there may be case where an extra
terminal process is required.
[0009] In addition, the electric tool is sometimes used in the
severe situation, such as dust and falling, in addition to
vibrations, a concern remains about durability and a dust-proof
performance in the divided structure where the stator core is
divided in a circumferential direction.
[0010] Therefore, an object of the present invention is to provide
an electric tool that achieves a high space factor and a low cost
by configuring a stator core of a brushless motor as a divided
structure and also allows ensuring durability and a dust-proof
performance.
[0011] Further, an object of the present invention is to provide
the electric tool that achieves the high space factor and the low
cost by configuring the stator core of the brushless motor as the
divided structure and also allows improving a cooling
performance.
[0012] Furthermore, an object of the present invention is to
provide the electric tool that can preferably reduce disconnection
of a coil.
[0013] In addition, an object of the present invention is to
provide the electric tool excellent in the durability and the
dust-proof performance even when the stator core is divided.
Solutions to the Problems
[0014] In order to achieve the above-described object, there is
provided an electric tool according to the present invention. The
electric tool includes a brushless motor including a stator, a
rotor, and a plurality of coils. The stator includes a stator core
formed by laminating electromagnetic steel plates. The rotor
includes a rotation shaft. The plurality of coils are wound around
the stator core via an insulating member. While the stator core is
formed by joining a plurality of divided cores divided in a
circumferential direction, a varnish or an adhesive is applied over
the coils and joining portions between the divided cores.
[0015] In the present invention according to another aspect, the
adhesive has a high thermal conductivity.
[0016] In the present invention according to another aspect, the
coils are wound around the respective divided cores.
[0017] In the present invention according to another aspect, the
stator includes a sensor circuit board including a rotation
detecting element of the rotor. The sensor circuit board is fixed
via a plurality of fixing pins directly fixed to the stator
core.
[0018] In the present invention according to another aspect, the
fixing pin are fixed across the two adjacent divided cores.
[0019] In the present invention according to another aspect, the
fixing pins are press-fitted to a disk made of metal disposed on an
end surface of the stator core.
[0020] In the present invention according to another aspect, each
of the divided cores has a shape fixed with an integrally molded
resin.
[0021] In the present invention according to another aspect, each
of the divided cores has a shape fixed with a dust core coating an
outer surface thereof.
[0022] In the present invention according to another aspect, the
respective divided cores are fixed with a tubular fixing member
made of metal manufactured by shrinkage fitting or cold
fitting.
[0023] In the present invention according to another aspect, which
is in the configuration of any one of claims 1 to 12, the
respective divided cores have joining portions inclined with
respect to an axial direction of the stator core.
[0024] In the present invention according to another aspect, which
is in the configuration of any one of claims 1 to 13, the
electromagnetic steel plates have a plate thickness of 0.25 mm or
less.
Effects of the Invention
[0025] According to the present invention, the varnish or the
adhesive is applied over the coils and the joining portions of the
divided cores (claim 1), or the joining portions of the divided
cores have two different kinds of the shapes so as to alternately
mesh with one another (claim 3), or the abutting portions between
the insulating members in the insulating members have
convexo-concave shapes alternately meshing with one another (claim
5). These configurations achieve a high space factor and a low cost
by configuring the stator core as the divided structure and also
ensure durability and a dust-proof performance.
[0026] Additionally, according to the present invention, the
plurality of protrusion portions are disposed on the outer surface
on the divided core (claim 15) or the plurality of protrusion
portions are disposed on the outer periphery of the fixing member
to fix the divided cores (claim 18). These configurations achieve a
high space factor and a low cost by configuring the stator core of
the brushless motor as the divided structure and also allow
improving a cooling performance.
[0027] Furthermore, according to the present invention,
disconnection of the coil can be preferably reduced (claim 21 and
the like).
[0028] In addition, according to the present invention, even when
the stator core is divided, preferred durability and dust-proof
performance can be maintained (claim 29 and the like).
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a vertical cross-sectional view of a hammer
drill.
[0030] FIG. 2 is a perspective view of a stator from a lower
side.
[0031] FIG. 3 is a perspective view of a divided core.
[0032] FIG. 4A is a perspective view of the divided core in which a
resin molded portion is formed, and FIG. 4B is a perspective view
of a divided body.
[0033] FIG. 5 is a perspective view of the stator from the lower
side before coated with varnish.
[0034] FIG. 6 is a perspective view of the stator from the lower
side to which a sensor circuit board is mounted.
[0035] FIG. 7 is a perspective view of the stator from the lower
side to which a terminal unit is mounted.
[0036] FIGS. 8A to 8F are explanatory views of connection
patterns.
[0037] FIG. 9 is a vertical cross-sectional view of a stator
illustrating a modification example of the terminal unit.
[0038] FIG. 10A is a perspective view illustrating a modification
example of the divided core, and FIG. 10B is a perspective view of
a divided body.
[0039] FIGS. 11A and 11B are explanatory views illustrating
modification examples of upper and lower insulating portions.
[0040] FIG. 12A is a perspective view illustrating a modification
example of the divided core, and FIG. 12B is a perspective view
illustrating a coupled state with a fixing pin.
[0041] FIG. 13 is a perspective view of the stator from a lower
side in which the fixing pins double as mounting of the sensor
circuit board and joining of the divided cores.
[0042] FIG. 14 is a perspective view of the stator from the lower
side coated with a dust core.
[0043] FIG. 15 is a perspective view of the stator from the lower
side using a fixing member having ridges.
[0044] FIG. 16 is a perspective view of the stator from a lower
side using the fixing member with the ridges inclined.
[0045] FIG. 17 is a perspective view of the stator from the lower
side using divided cores with end edges of arc portions
inclined.
[0046] FIG. 18 is a perspective view of the stator from the lower
side using divided cores including protrusion portions on outer
peripheral surfaces of the arc portions.
[0047] FIG. 19 is a perspective view of an outer peripheral
portion.
[0048] FIG. 20 is a perspective view of a tooth.
[0049] FIG. 21A is a perspective view of the tooth in which the
resin molded portion is formed, and FIG. 21B is a perspective view
of a divided body.
[0050] FIG. 22 is a perspective view from a lower side in a state
of arranging the divided bodies.
[0051] FIG. 23 is a perspective view from the lower side
illustrating a state in which the divided bodies are joined to the
outer peripheral portion.
[0052] FIG. 24 is a perspective view illustrating a modification
example of coupling the teeth together with joints.
[0053] FIG. 25 is a perspective view from a lower side in a state
where the divided bodies with the resin molded portions mutually
connected are arranged, and
[0054] FIG. 26 is a perspective view illustrating an example in
which an outer peripheral portion is longer than teeth.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0055] The following describes embodiments of the present invention
with reference to the drawings.
[Description of Hammer Drill]
[0056] FIG. 1 is a vertical cross-sectional view of the hammer
drill as one example of an electric tool. A hammer drill 1 includes
an output housing 4, which houses an output unit 5 and extends
forward, on an upper side of a motor housing 2 in an up-down
direction housing a brushless motor 3. A battery mounting portion 6
that houses a controller 7 and has a lower side to which two
battery packs 8, 8 are mountable is disposed on the lower side of
the motor housing 2. Reference numeral 9 denotes a handlebar
disposed to extend in the up-down direction from the rear of the
output housing 4 to the battery mounting portion 6.
[0057] The brushless motor 3 is an inner rotor type including a
stator 10 and a rotor 11 inside the stator 10 and is housed in the
motor housing 2 with a posture in which a rotation shaft 12 of the
rotor 11 facing above. The stator 10 includes a stator core 13, an
upper insulator 14 and a lower insulator 15, which are disposed on
the top and bottom of the stator core 13, and a plurality of coils
16, 16, and so on (FIG. 2 and the like) wound around the inside of
the stator core 13 via the upper and lower insulators 14, 15. The
stator core 13 has a divided structure constituted of a plurality
of components, and details of this divided structure will be
described later.
[0058] The rotor 11 includes the rotation shaft 12 positioned at
its axial center, a tubular rotor core 17 arranged around the
rotation shaft 12, and a plurality of permanent magnets 18, 18, and
so on arranged inside the rotor core 17. A sensor circuit board 19
and a terminal unit 20 to connect terminals of the coils 16 are
fixed to the lower end of the lower insulator 15. The sensor
circuit board 19 includes a rotation detecting element (not
illustrated) that detects positions of the permanent magnets 18 in
the rotor core 17 and outputs a rotation detection signal. The
rotation shaft 12 has a lower end supported to a bearing 21, which
is disposed on the bottom portion of the motor housing 2, and an
upper end supported to a bearing 22, which is disposed in the
output housing 4 and projects into the output housing 4. A pinion
23, which is formed on the upper end of the rotation shaft 12,
meshes with gear 26, 27, which are disposed on respective
intermediate shaft 24 and crankshaft 25 on the front and rear. A
centrifugal fan 28 is disposed on the lower side of the bearing 22
and on the rotation shaft 12, and a baffle plate 29 is disposed
below the centrifugal fan 28 and inside the motor housing 2.
[0059] The output unit 5 includes a rotatable, tubular tool holder
30 extending in a front-rear direction. A bevel gear 31, which is
externally mounted to a rear end of the tool holder 30, meshes with
a bevel gear 32 disposed on an upper end of the intermediate shaft
24. A cylinder 33 is inserted into and mounted to the inside of the
tool holder 30, and a piston 34 disposed inside the cylinder 33 is
coupled to a crank pin 36, which is disposed at an eccentric
position on the upper end of the crankshaft 25, via a connecting
rod 35.
[0060] A striker 38 is housed inside the cylinder 33 and ahead of
the piston 34 in an air chamber 37 to be movable back and forth,
and an impact bolt 39 is housed inside the tool holder 30 ahead of
the striker 38 to be movable back and forth. Here, when a tool bit,
such as a drill bit, is inserted from a distal end of the tool
holder 30, a rear end of the tool bit retreats the impact bolt 39
up to a position where the impact bolt 39 abuts on a receiving ring
40 ahead of the cylinder 33 to cause the rear end to project into
the cylinder 33. Reference numeral 41 denotes an operation sleeve
externally mounted to a front end of the tool holder 30 for
performing attachment and removal operations of the tool bit.
[0061] Meanwhile, inside the battery mounting portion 6, two
terminal blocks 42, 42 on which the battery packs 8, 8 are slidably
mounted from a right-left direction are arranged back and forth,
and the controller 7 is housed on the upper side. The controller 7
includes a control circuit board (not illustrated) including a
microcomputer and a switching element and is supported by U-shaped
ribs 43, 43, which are disposed upright on an inner surface of the
battery mounting portion 6, in the front-rear direction. A light 44
that irradiates the front side of the tool holder 30 with an LED is
disposed in front of the controller 7. Guard plates 45, 45 to cover
the front and rear of the mounted battery packs 8, 8 are formed to
project downward on the front and rear of the battery mounting
portion 6.
[0062] A switch 46 and a capacitor 47 electrically coupled to the
controller 7 are disposed in the handlebar 9, and a switch lever 48
is disposed on a plunger projecting forward from the switch 46.
[0063] Accordingly, with this hammer drill 1, pushing the switch
lever 48 by a hand gripping the handlebar 9 and performing an ON
operation on the switch 46 feeds the power from the battery pack 8
to the brushless motor 3 to rotate the rotation shaft 12. That is,
the microcomputer in the controller 7 obtains the rotation
detection signal indicative of the position of the permanent magnet
18 of the rotor 11 output from the rotation detecting element in
the sensor circuit board 19 to obtain the rotating state of the
rotor 11. According to the obtained rotating state, the
microcomputer controls ON/OFF of the respective switching elements
and flows a current in sequence to the respective coils 16 in the
stator 10 in order to rotate the rotor 11.
[0064] Thus rotating the rotation shaft 12 decelerates and rotates
the intermediate shaft 24 via the gear 26 and rotates the tool
holder 30 together with the tool bit via the bevel gears 32, 31.
Simultaneously, the crankshaft 25 decelerates and rotates via the
gear 27, the piston 34 reciprocates inside the cylinder 33 via the
connecting rod 35 to move the striker 38 back and forth via the air
chamber 37. Accordingly, the striker 38 hits the tool bit via the
impact bolt 39.
[0065] Air inlets (not illustrated) are formed on right and left
side surfaces of the battery mounting portion 6, which serve as
both right and left sides of the controller 7. Exhaust outlets (not
illustrated) are formed on right and left side surfaces of the
motor housing 2, which serve as both right and left sides of the
centrifugal fan 28, and the controller 7 is arranged between the
air inlets and the brushless motor 3. Accordingly, by the rotation
of the centrifugal fan 28 in association with the rotation of the
rotation shaft 12, air suctioned from the air inlets first contacts
the controller 7 to cool the controller 7, and after that, the air
pass through the inside of the motor housing 2 to cool the
brushless motor 3. The air is then discharged from the exhaust
outlets via the baffle plate 29.
[Description of Structure of Stator]
[0066] Next, the following describes the structure of the stator 10
in detail. FIG. 2 is a perspective view of the stator 10 before the
sensor circuit board 19 and the terminal unit 20 are mounted, FIG.
2 is upside down of FIG. 1. The stator core 13 has a tubular body
including a plurality (here, 12 pieces) of teeth 52, 52, and so on
having a T shape in plan view and projecting toward the center on
an inner periphery of the stator core 13. Here, as illustrated in
FIG. 3, the stator core 13 is divided by 12 pieces of divided cores
50, 50, and so on formed of arc portions 51 as a part of the
tubular body and the teeth 52 projecting inward from inner surfaces
of arc portions 51, thus forming the stator core 13 by joining the
divided cores 50, 50 adjacent in the circumferential direction. On
both ends of the arc portions 51 serving as joining portions of the
divided cores 50, 50, protruding portions 53 projecting into a
triangular shape in plan view and depressed portions 54 depressed
into a V shape in plan view are each formed on one ends and the
other ends across the whole length in the up-down direction. The
protruding portion 53 and the depressed portion 54 have shapes
fittable to one another. A through-hole 55 penetrating up and down
is formed at the center in the circumferential direction of the arc
portion 51.
[0067] Electromagnetic steel plates (for example, a plate thickness
t=0.25 mm or less) punched into an identical shape are laminated
and integrally molded with resin, thus manufacturing the divided
cores 50. The use of the electromagnetic steel plates having the
thin plate thickness leads to a reduction in loss due to eddy
current.
[0068] As illustrated in FIG. 4A, an integrally molded resin molded
portion R having a predetermined thickness coats an outer periphery
of the divided core 50 excluding parts of the protruding portion 53
and the depressed portion 54 on both ends of the arc portion 51,
the projecting end of the tooth 52, and the through-hole 55.
However, insulation papers (not illustrated) are interposed inside
the resin molded portion R on both right and left surfaces of the
tooth 52 in the circumferential direction, thus double insulations
are provided.
[0069] In this resin molded portion R, a part positioned on the top
side of the arc portion 51 becomes an upper insulating portion 56
constituting the upper insulator 14 and a part positioned on the
bottom side of the arc portion 51 becomes a lower insulating
portion 57 constituting the lower insulator 15. That is, the upper
and lower insulators 14, 15 are divided into twelve pieces,
similarly to the stator core 13.
[0070] An upper outer rib 58 and a lower outer rib 59 to receive
the outer side of the coil 16 are disposed upright on inner edges
on the tooth 52 side of the upper and lower insulating portions 56,
57, respectively, and a pair of terminal plates 60, 60 are disposed
outside the lower outer rib 59. This terminal plates 60 have a
U-shape with both ends facing downward, and end portions 60a on
both ends sides of the arc portions 51 are formed longer so as to
extend downward with respect to end portions 60b inside the end
portions 60a. Furthermore, a slit 61 opening downward is formed at
the center of the lower outer rib 59, and an expansion portion 62
having a widening width is formed on the lower side of the slit 61.
An upper inner rib 63 and a lower inner rib 64 to receive the
inside of the coil 16 are each disposed upright on the top and
bottom of the projecting end of the tooth 52 in the resin molded
portion R.
[0071] In the divided core 50 thus integrally molded with resin, a
magnet wire is wound around to each tooth 52 to form the coil 16.
After both terminals 16a, 16a of the coil 16 are pulled out from
both sides of the lower insulating portions 57 and pressure shaping
is performed on the coil 16, both terminals 16a, 16a are coupled to
the right and left terminal plates 60, 60 by fusing, soldering, or
the like. Then, as illustrated in FIG. 4B, the coil 16 is wound
around the divided core 50 via the upper and lower insulating
portions 56, 57, and the divided body 65 in which the terminals
16a, 16a are fixed to the terminal plates 60, 60 are obtained.
[0072] Thus, the shape of each divided core 50 is fixed with the
resin molded portion R coating the outer surface of the divided
core 50. Therefore, the divided core 50 is insulated at the same
time together with the integration of the electromagnetic steel
plates. Since the coil 16 is formed on each divided core 50, the
magnet wire can be easily wound at identical timing.
[0073] Twelve pieces of the divided bodies 65 are circumferentially
arranged such that the arc portions 51 of the respective divided
cores 50 are circumferentially coupled, and the adjacent protruding
portions 53 and depressed portions 54 are fitted to one another and
joined by welding or the like. Then, as illustrated in FIG. 5, the
respective divided bodies 65, 65, and so on are circumferentially
coupled. In this state, applying varnishes 66, 67 over the outer
peripheral surfaces of the respective coils 16 and the joining
parts of the divided cores 50, 50 (both upper and lower ends of the
fitting parts between the protruding portions 53 and the depressed
portions 54) allows obtaining the stator 10 illustrated in FIG. 2.
The varnishes 66, 67 are to insulate and protect the coils 16 and
may be adhesives, and especially, applying the adhesives over the
joining parts of the divided cores 50, 50 allows expecting
improvement in strength. The use of an adhesive having a high
thermal conductivity (for example, a resin adhesive mainly
containing epoxy resin) facilitates releasing heat generated in the
coils 16 and improves heat resistance performance.
[0074] As illustrated in FIG. 6, the sensor circuit board 19 is
mounted on the lower insulator 15 of the stator 10. The sensor
circuit board 19 has an outer diameter such that the sensor circuit
board 19 can be housed in an inner space surrounded by the
respective lower outer ribs 59 on the lower insulator 15, has a
ring shape having a through-hole for the rotor 11 at the center,
and has an outer periphery on which three installation pieces 70,
70, and so on radially protrude at regular intervals in the
circumferential direction. This installation piece 70 engages the
expansion portions 62 of the slits 61 and projects outward with
respect to the lower outer rib 59 at the corresponding position,
and a fixing pin 72 is press-fitted between a through hole 71
disposed at the distal end and the through-hole 55 in the divided
core 50 positioned immediately below the through hole 71. Thus, the
sensor circuit board 19 is supported to the divided cores 50 via
the fixing pins 72, 72, and so on.
[Effects Brought by Fixing Structure of Sensor Circuit Board with
Fixing Pins]
[0075] Thus, the sensor circuit board 19 is fixed via the plurality
of fixing pins 72, 72, and so on directly fixed to the stator core
13. Accordingly, the sensor circuit board 19 can be positioned with
respect to the stator core 13 without via the lower insulator 15
made of resin having low accuracy. Accordingly, the rotation
position of the rotor 11 can be accurately detected,
controllability is improved, and a permanent magnet for detection
of the rotation becomes unnecessary.
[0076] As illustrated in FIG. 7, by insert-molding a plurality of
terminal metal fittings with resin, the terminal unit 20 has a
structure in which bifurcated end portions 76, 76, and so on of
terminal metal fittings 75, 75, and so on project so as to match
positions of the terminal plates 60, 60 of the respective divided
bodies 65 on an outer periphery of an insulating ring 74, which has
a diameter approximately identical to that of the sensor circuit
board 19 and has a through-hole for the rotor 11 at the center. The
longer end portions 60a of the corresponding terminal plates 60 are
inserted into the respective bifurcated end portions 76 and coupled
by soldering or the like, thus mounting to the stator 10 is
performed. Changing the shapes of the terminal metal fittings 75
and the disposed configuration in the insulating ring 74 makes the
connection pattern of the coils 16 selectable. Coupling that the
adjacent divided bodies 65, 65 are reversely wound also becomes
possible.
[0077] FIG. 8 illustrates examples of the connection patterns of 12
pieces of the coils 16, 16 . . . , and so on distinguished by
numbers (1) to (12) in FIG. 5, FIG. 8A illustrates a Star (Y)
connection of four series, FIG. 8B illustrates a Star (Y)
connection of four parallel, FIG. 8C illustrates a Star
(Y)-connection of two series and two parallel, FIG. 8D illustrates
a Delta (.DELTA.) connection of four series, FIG. 8E illustrates a
Delta (.DELTA.)-connection of two series and two parallel, and FIG.
8F illustrates a Delta (.DELTA.) connection of four parallel.
[0078] As illustrated in FIG. 9, the terminal unit 20 may
integrally include a bearing holder 77 that holds the bearing 21 of
the rotation shaft 12. Disposing the holding portion for the
bearing 21 in the motor housing 2 likely causes a cumulative
tolerance, and the use of the divided cores 50 likely causes a
difficulty of ensuring the coaxiality between the stator 10 and the
rotor 11. However, supporting the rotation shaft 12 with the
bearing holder 77 via the bearing 21 using the terminal unit 20
facilitates providing the coaxiality between the stator 10 and the
rotor 11.
[Effects Brought by Varnish or Adhesive]
[0079] With the stator 10, while the stator core 13 is formed by
joining the plurality of divided cores 50, 50, and so on, which are
divided in the circumferential direction, applying the varnish or
the adhesive over the respective coils 16 and the joining portions
between the divided cores 50, 50 increases integrity and
adhesiveness. Accordingly, while the stator core 13 is configured
as the divided structure to achieve a high space factor and a low
cost, durability and a dust-proof performance can be ensured.
[0080] Moreover, in the application of the adhesive, the use of an
adhesive having a high thermal conductivity facilitates releasing
the heat in the coils 16 to the stator 10, thus improving heat
resistance.
[0081] Meanwhile, the use of the divided cores 50 possibly
generates a chattering sound caused by an electromagnetic force
generated between the divided cores 50, 50 during switching of
excitation. However, applying the varnish or the adhesive over the
respective coils 16 and the joining portions between the divided
cores 50, 50 increases integrity and adhesiveness. Therefore, a
reduction effect of the chattering sound can be expected.
[Effects Brought by Two Terminals Disposed on Each Coil]
[0082] With the stator 10, since the two terminal plates 60, 60
coupled to the magnet wire forming the coil 16 are disposed on each
coil 16, the magnet wire can be coupled to the terminal plates 60,
60 with tension applied to the coil 16. Accordingly, there is no
possibility of causing a looseness and a deflection in the coil 16,
and a disconnection and a layer short are reduced.
[0083] Therefore, the present invention is also usable for a stator
in which a stator core is not divided.
[Effects Brought by Terminal Unit]
[0084] Here, the stator 10 includes the terminal unit 20 including
the plurality of terminal metal fittings 75, 75, and so on to
couple the predetermined terminal plates 60, 60 to one another, and
the coupling between the terminal metal fittings 75 on the terminal
unit 20 and the terminal plates 60 connects the respective coils
16. That is, after a plurality of the terminal units 20 having the
terminal metal fittings 75 different in the shapes and the disposed
configuration are prepared, the respective coils 16 are wound
around the stator cores 13, and the respective magnet wires are
coupled to the terminal plates 60, any of the terminal units 20 is
selected and fixed to the stator 10. Then, the terminal metal
fittings 75 on the terminal unit 20 and the terminal plates 60 are
coupled, and the respective coils 16 can be connected via the
terminal unit 20. Accordingly, the use of the terminal unit 20
according to the purpose allows easily selecting the series,
parallel, Y-connection, and the A connection as illustrated in FIG.
8. Thus, since only the change of the terminal unit 20 can change
the connection method, optimal winding wire specifications of a
manufacturing period (number of turnings) and manufacturability
(wire diameter) are selectable according to the respective
manufacturing specifications using the identical winding wire
facility.
[0085] Accordingly, the present invention according to the terminal
unit is also usable for a stator in which a stator core is not
divided.
[0086] With the terminal unit 20, coupling a starting end of a
magnet wire of one coil 16 and a terminating end of a magnet wire
of another coil 16 adjacent to one another in the identical phase
allows producing the divided bodies 65 using the identical winding
wire facility even when a fractional slot is used.
[Modification Example of Divided Cores (Shapes of Joining Portions
Alternately Different)]
[0087] Like a divided core 50A illustrated in FIG. 10A, the divided
core may include the arc portion 51 having the protruding portions
53 and the depressed portions 54 on both ends in the
circumferential direction. The protruding portions 53 and the
depressed portions 54 may have convexo-concave shapes of two
different kinds of shapes appearing in alternation such that the
adjacent divided cores 50A, 50A alternately mesh with one
another.
[0088] The convexo-concave shapes can be formed by stacking
electromagnetic steel plates having different both end shapes in
which one end portion of the arc portion 51 is configured to be a
protruding shape and the other end portion is configured to be a
depressed shape while changing orientations by every predetermined
number of plates.
[0089] On this divided core 50A, the resin molded portion R
including the upper insulating portion 56 and the lower insulating
portion 57, the upper and lower outer ribs 58, 59, and the like is
formed with resin similarly, the coil 16 is wound around, and both
terminals 16a, 16a are electrically coupled to the terminal plates
60, 60. Then, as illustrated in FIG. 10B, a divided body 65A
including the arc portion 51 of the divided core 50A having both
ends in the circumferential direction exposed as the
convexo-concave shapes is obtained.
[0090] Twelve pieces of the divided bodies 65A, 65A, and so on are
arranged in the circumferential direction such that the arc
portions 51 of the respective divided cores 50A are coupled in the
circumferential direction, and the protruding portions 53 and the
depressed portions 54 are alternately fitted and are joined by
welding or the like. Then, similarly to FIG. 5, the respective
divided bodies 65A, 65A, and so on are in the state of being
coupled in the circumferential direction. In this state, applying
the varnishes 66, 67 over the outer peripheral surfaces of the
respective coils 16 and the joining parts between the divided cores
50A, 50A obtains the stator 10 similar to FIG. 2. It is only
necessary to similarly fix the sensor circuit board 19 and the
terminal unit 20.
[Effects Brought by Shapes of Joining Portions Alternately
Different]
[0091] Thus, the end portions of the joining portions between the
divided cores 50A, 50A in the respective divided cores 50A are
configured such that the protruding portions 53 and the depressed
portions 54 having the two different shapes appear in alternation.
Accordingly, the end portions mesh with one another with the
divided cores 50A, 50A in the joined state, thereby allowing
ensuring strength and adhesiveness in a thrust direction.
Accordingly, while the stator core 13 is configured as the divided
structure to achieve the high space factor and the low cost,
durability and a dust-proof performance can be ensured.
[0092] It should be noted that, not limited to the
triangular-shaped protruding portion 53 and the V-shaped depressed
portion 54, as long as meshing is possible with two different
shapes, the shapes of the end portions are appropriately
changeable, such as fitting of semicircular-shaped convex portion
and concave portion and a protruding portion and a depressed
portion literally. The same applies to the divided core 50
illustrated in FIG. 3, and the shapes are appropriately changeable
not limited to the protruding portion 53 and the depressed portion
54.
[Modification Example of Divided Cores (Shapes of Insulating
Portions Alternately Different)]
[0093] Such structures that are alternately different are
applicable to the upper and lower insulating portions 56, 57. For
example, as illustrated in FIG. 11A, the upper insulating portion
56 in one divided core 50 (50A) is configured as an uneven portion
78a having a lower side extending to the adjacent divided cores 50
(50A) side and an upper side retreating to a side of itself, and
the upper insulating portion 56 in another divided core 50 (50A) is
configured as a reversed uneven portion 78b having an upper side
extending to the adjacent divided core side and a lower side
retreating to the side of itself. In this case as well, the uneven
portions 78a, 78b alternately mesh with one another in the joined
state. The same applies to the lower insulating portion 57.
[Effects Brought by Shapes of Insulating Portions Alternately
Different]
[0094] Thus, when the respective upper and lower insulating
portions 56, 57 are divided similarly to the divided cores 50 (50A)
and arranged on the respective divided cores 50 (50A), and abutting
portions between the upper insulating portions 56, 56 and between
the lower insulating portions 57, 57 are configured to have
convexo-concave shapes alternately meshing with one another, an
insulation distance can be ensured long. While the stator core 13
is configured as the divided structure to achieve the high space
factor and the low cost, the integrated upper and lower insulating
portions 56, 57 allows enhancing the strength in the thrust
direction and ensuring durability and a dust-proof performance.
[0095] It should be noted that the convexo-concave shapes are not
limited to these shapes, the numbers of depressed portions and
protruding portions may be increased, and not limited to the
convexo-concave shapes, as illustrated in FIG. 11B, inclined
surfaces 79, 79 can abut on one another.
[Modification Example of Divided Cores (Fixing Pin is Doubled)]
[0096] Like a divided core 50B illustrated in FIG. 12A, tubular
hinge portions 80 and concave surface portions 81 to which the
hinge portions 80 are fitted are formed in alternation on both ends
of the arc portion 51 such that the hinge portions 80, 80 coaxially
overlap in alternation between end portions of the arc portions 51
on the adjacent divided cores 50B, 50B.
[0097] Similarly to the divided cores 50A, the hinge portions 80
and the concave surface portions 81 can be formed by stacking
electromagnetic steel plates having different both end shapes in
which one end portions are configured to be ring shapes as a part
of the hinge portions 80 and the other end portions are configured
to be concave shapes as a part of the concave surface portions 81
while changing orientations by every predetermined number of
plates.
[0098] As illustrated in FIG. 12B, penetrating the fixing pin 72
for the sensor circuit board 19 across the hinge portions 80, 80
coaxially positioned between the adjacent divided cores 50B, 50B
allows joining between the divided cores 50B, 50B.
[0099] In this case, it is sufficient that the fixing pins 72, 72
are extended long downward, as illustrated in FIG. 13, the
respective installation pieces 70 on the sensor circuit board 19
are positioned between the divided cores 50B, 50B not the expansion
portions 62 of the slits 61 on the lower outer ribs 59, the
respective fixing pins 72 are inserted into the through holes 71 in
the respective installation pieces 70, and the sensor circuit board
19 is mounted.
[0100] It should be noted that, in FIG. 13, in a divided body 65B
configured by fixing each divided core 50B with the resin molded
portion R, one terminal plate 60 disposed on the lower insulating
portion 57 has an L shape not having the longer end portion 60a,
and the bifurcated end portion 76 of the terminal metal fitting 75
of the terminal unit 20 is electrically coupled to only the longer
end portion 60a of the other terminal plate 60. In a state of being
coupled with a crossover wire 16b, which meanders the outer side of
the fixing pin 72, the coils 16, 16 on the adjacent divided bodies
65B, 65B are electrically coupled and connected to the respective
U-shaped terminal plate 60 and L-shaped terminal plate 60, which
are adjacent to one another and between which the fixing pin 72 is
sandwiched.
[Effects Brought by Doubled Fixing Pin]
[0101] Thus fixing the fixing pin 72 across the adjacent two
divided cores 50B, 50B allows the fixing pin 72 to double as the
coupling between the divided cores 50B, 50B and the mounting of the
sensor circuit board 19.
[0102] Especially, as in FIG. 12B, in a case where an interval
between the divided cores 50B, 50B is expanded in a state of being
coupled with the fixing pin 72 and an interval between the teeth
52, 52 is expanded, the coils 16, 16 are easily wound around after
the resin molded portions R are formed and can be wound around
without cutting the magnet wires, thereby ensuring reducing the
number of terminal plates. In a connection structure in FIG. 13,
the fixing pins 72 are usable for positioning the crossover wires
16b between the coils 16, 16.
[0103] A disk-shaped coupling ring 82 made of metal is disposed
outside the upper outer ribs 58 on the end surface of the upper
insulator 14, and upper ends of the respective fixing pins 72 are
coupled to the coupling ring 82 by press-fitting or the like. In
this case, since the fixing pins 72 are integrated with the
coupling ring 82, the integrity of the divided cores 50B, 50B, and
so on is enhanced.
[0104] As in FIG. 12, with the use of the fixing pin 72 for
coupling of the divided cores 50B, 50B, in order to avoid the arc
portions 51, 51 to mutually turn excessively from positions where
the arc portions 51, 51 are continuous in the circumferential
direction, stopper surfaces 80a, 81a that abut on one another to
restrict the excessive turning are preferably disposed inside the
hinge portions 80 and the concave surface portion 81.
[Modification Example of Divided Cores (Fixation and Heat Release
Structure)]
[0105] The fixation of the divided cores 50 (50A, 50B) are not
limited to the integral molding with resin, and as illustrated in
FIG. 14, outer peripheries can be coated with a dust core (a mixed
material of a magnetic material, such as iron, and resin) 83, and
as illustrated in FIG. 15, the outer peripheries can be fixed with
a tubular fixing member 84 made of metal manufactured by shrinkage
fitting or cold fitting. The use of such dust core 83 and fixing
member 84 facilitates fixing the divided cores 50 (50A, 50B).
[0106] Especially, by disposing a plurality of ridges 85, 85, and
so on as protrusion portions extending up and down at regular
intervals in the circumferential direction on the outer periphery
of the fixing member 84, the heat generated in the coils 16 can be
effectively released via the fixing member 84. Additionally, the
varnish or the adhesive may be interposed between the outer
peripheries of the respective divided cores 50 (50A, 50B) and the
fixing member 84 to improve integrity. The fixing member is not
limited to have the cylindrical shape but may have a cornered
tubular shape, or a part of the outer peripheral surface may be
depressed.
[0107] As illustrated in FIG. 16, the ridges 85 can be inclined
with respect to an axial direction of the stator core. This
configuration increases a surface area (cooling area) of the fixing
member 84 including the ridges 85, leading to improvement in a heat
release effect. It should be noted that, instead of the ridges, a
plurality of protrusions may be formed.
[0108] In a case that the ridges 85 and the protrusions are
arranged such that the cooling air from the centrifugal fan 28 is
straightened, a noise caused by the cooling air can be reduced.
[0109] It should be noted that the bearing holder 77 to hold the
bearing 21 on the lower side can be disposed on the fixing member
84, not the terminal unit 20.
[0110] Further, as illustrated in FIG. 17, both ends of the arc
portions 51 of the divided cores 50 (50A, 50B) need not have a
structure being formed into a straight line along the axial
direction of the stator 10 but may have a structure of being
inclined with respect to the axial direction and inclined end edges
51a, 51a are mutually joined by mating fitting. By thus inclining
the joining portions, the integrity in the thrust direction is
enhanced.
[Modification Example of Divided Cores (Heat Release
Structure)]
[0111] As illustrated in FIG. 18, a plurality of protrusion
portions 86, 86, and so on can be disposed in the outer peripheral
surface of the arc portion 51 of each divided core 50 (50A, 50B).
The protrusion portions 86 are disposed such that rows arranged at
regular intervals in the up-down direction (the stacking direction
of the electromagnetic steel plates) are disposed plurally at
regular intervals in the circumferential direction. Between the
rows adjacent in the circumferential direction, the protrusion
portions 86, 86 are arranged such that the phases are displaced in
the up-down direction in alternation. It should be noted that, on
both ends of the arc portions 51, protrusion portions 86a, 86a, and
so on are formed so as to be continuously arranged in the up-down
direction, and rows of the protrusion portions 86a, 86a are
adjacent between the end portions of the respective arc portions
51. The adjacent rows of the protrusion portions 86a, 86a are
joined together by welding, with a separate sandwiching member, or
the like to ensure the joining between the divided cores 50 (50A,
50B).
[0112] The respective protrusion portions 86 may be formed into a
laminated state by forming a part of the protrusion portions 86,
86a on the respective electromagnetic steel plates forming the
divided cores 50 (50A, 50B), or the separate protrusion portions
86, 86a may be joined to the arc portions 51.
[Effects Brought by Heat Release Structure of Protrusion
Portions]
[0113] By thus disposing the plurality of protrusion portions 86,
86a on the outer peripheral surfaces of the respective divided
cores 50 (50A, 50B), the heat generated in the coils 16 can be
effectively released.
[0114] Especially, here, since the protrusion portions 86, 86a are
arranged at the regular intervals along the stacking direction of
the electromagnetic steel plates, the heat release effect can be
equally obtained.
[0115] The protrusion portions 86a are disposed side by side into
the straight line on both ends where the divided cores 50 (50A,
50B) are mutually joined and the rows of the protrusion portions
86a between the adjacent divided cores 50 (50A, 50B) are mutually
welded or the like to join the divided cores 50 (50A, 50B).
Therefore, a rational structure in which the divided cores 50 (50A,
50B) can be joined by using the protrusion portions 86a for heat
release can be constructed.
[0116] It should be noted that when the protrusion portions 86 are
arranged such that the cooling air from the centrifugal fan 28 is
straightened, the noise caused by the cooling air can be
reduced.
[Modification Example of Divided Configuration]
[0117] While the divided cores 50 (50A, 50B) according to the
embodiments described above and modification examples have the
structure formed of the arc portions 51 and the teeth 52 dividing
the stator core 13 in the circumferential direction, the divided
configuration is not limited to this configuration. For example,
the stator core 13 can be divided into a cylindrical shaped outer
peripheral portion 90 illustrated in FIG. 19 and a plurality of
teeth 91, 91, and so on illustrated in FIG. 20. Here, dovetail
grooves 92, 92, and so on penetrating up and down are formed at a
positions where the teeth 91 are arranged in an inner surface of
the outer peripheral portion 90, a dovetail tenon 93 fitted to the
dovetail groove 92 is formed on an outer end of each tooth 91, and
the through-hole 55 for the fixing pin 72 is formed in the dovetail
tenon 93.
[0118] Meanwhile, as illustrated in FIG. 21A, the resin molded
portion R is integrally molded into a tubular shape as follows. The
resin molded portion R including the upper and lower insulating
portions 56, 57 has an opening R1 into which the tooth 91 is
inserted from the dovetail tenon 93 side to cover the tooth 91, and
only the lower insulating portion 57 projects outside from the
upper and lower outer ribs 58, 59. The coil 16 is wound around the
resin molded portion R, and both terminals 16a, 16a are formed in a
state being coupled to the terminal plates 60, 60.
[0119] Accordingly, as illustrated in FIG. 21B, when the tooth 91
is joined to the resin molded portion R from the inside such that
the dovetail tenon 93 is inserted first, divided bodies 94, 94, and
so on where the dovetail tenons 93 project outside are obtained as
illustrated in FIG. 22. When the dovetail tenons 93 of the
respective divided bodies 94 are fitted to the respective dovetail
grooves 92 in the outer peripheral portion 90 from the lower side,
the respective divided bodies 94 are joined to the outer peripheral
portion 90 as illustrated in FIG. 23, thus obtaining the stator 10
becoming the stator core 13.
[Effects Brought by Divided Configurations of Outer Peripheral
Portion and Teeth]
[0120] Thus, the stator core 13 is divided into the cylindrical
shaped outer peripheral portion 90 and the plurality of teeth 91,
which project from the inside of the outer peripheral portion 90
and around which the respective coils 16 are wound, and the stator
core 13 is formed by joining the outer peripheral portion 90 and
the teeth 91, thus ensuring maintaining the strength by the use of
the continuous outer peripheral portion 90.
[0121] Especially, here, the teeth 91 are inserted into the resin
molded portions R around which the coils 16 are preliminarily wound
and are joined to the outer peripheral portion 90. Therefore, the
assembly can be easily performed.
[0122] It should be noted that a relationship between the dovetail
groove and the dovetail tenon may be set reverse to the
configuration described above such that the dovetail tenons is
formed in the outer peripheral portion and the dovetail grooves is
formed in the teeth.
[0123] While the divided configuration forms each of the teeth 91
independently, between projecting ends 95, 95 of the adjacent teeth
91, 91, joints 96, 96, and so on joining both projecting ends may
be disposed, and all teeth 91, 91, and so on may be mutually fixed
with the projecting ends 95, 95 to be integrated as illustrated in
FIG. 24. In this case, it is sufficient to form the electromagnetic
steel plates so as to have a shape including the joints 96.
[0124] Further, as illustrated in FIG. 25, coupling portions 97, 97
to couple between the upper and lower inner ribs 63, 64 may be
integrally disposed between the projecting ends 95, 95 of the
adjacent teeth 91, 91 in the respective resin molded portions R to
ensure integrating all resin molded portions R via the coupling
portions 97 as integrally molded resin.
[0125] Thus integrating the teeth 91 or the resin molded portions R
facilitates the assembly to the outer peripheral portion 90 and
also facilitates management.
[0126] Meanwhile, with such a divided configuration, separately
forming the outer peripheral portion 90 and the teeth 91 can
differentiate their axial lengths. FIG. 26 illustrates an example
of forming the outer peripheral portion 90 longer than the teeth 91
to the one end side. Thus forming the outer peripheral portion 90
axially longer than the teeth 91 allows forming a three-dimensional
magnetic circuit and increasing a freedom of design, leading to
downsizing and a weight reduction.
[0127] The outer peripheral portions of these are not limited to
have the cylindrical shape, and the outer peripheral surface and
the inner peripheral surface may be a non-circular shape (a polygon
and a shape having a partial unevenness).
[0128] Besides, in each of the present inventions, to achieve heat
release, the switching element disposed in the controller may be
thermally bonded to the protrusion portion on the stator core and
the ridges on the fixing member via a thermal bonding member, and
the switching element may be disposed in the sensor circuit board
and similarly may be thermally bonded to the protrusion portion on
the stator core and the ridges on the fixing member via the thermal
bonding member.
[0129] As the magnet wire forming the coil, a flat wire may be
used.
[0130] Furthermore, the number of coils (slots) is not limited to
12 and may be any number other than 12. Obviously, not limited to a
hammer drill, as long as the brushless motor is used as a driving
source, each of the present inventions is applicable to another
electric tool, such as an impact driver and a circular saw.
* * * * *