POWER TOOL

A power tool has highly airtight electrical connection between a controller and a switch to effectively prevent a short circuit. A grinder includes a housing, a motor accommodated in the housing, a controller accommodated in the housing and including a circuit board and a controller terminal located on a first facing surface and electrically connected to the circuit board, a switch accommodated in the housing and including a switch terminal located on a second facing surface facing the controller, being in direct contact with the controller terminal, and electrically connected to the controller terminal, and a seal located between the first facing surface and the second facing surface and sealing a periphery of the controller terminal and a periphery of the switch terminal with the controller terminal being in direct contact with the switch terminal. The first facing surface is a surface of the controller facing the switch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2021-164259, filed on Oct. 5, 2021, the entire contents of which are hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a power tool such as a grinder.

2. Description of the Background

In power tools such as grinders, as described in Japanese Patent No. 5468459 (hereafter, Patent Literature 1), a controller and a switch that turns on or off a motor are accommodated in a housing, and the controller and the switch are electrically connected to each other. One known grinder described in Patent Literature 1 includes a switch block including a switch attached to a housing. A male terminal protrudes from the controller, and a female terminal is accommodated in the switch block to form a connecting portion including an inlet for the male terminal. When the switch block is attached to the controller, the male terminal is placed into and connected to the female terminal. A sealing portion above the male terminal covers the surface of the connecting portion with the inlet, with the male terminal being placed and connected. The connecting portion thus achieves dust resistance.

BRIEF SUMMARY

A known power tool has a sealing portion formed from a resin. The surface with the inlet for the male terminal covered with such a sealing portion cannot have high airtightness and may cause entry of iron powder or other matter that can cause a short circuit.

One or more aspects of the present disclosure are directed to a power tool that has highly airtight electrical connection between a controller and a switch to effectively prevent a short circuit.

An aspect of the present disclosure provides a power tool, including:

a housing;

a motor accommodated in the housing;

a controller accommodated in the housing, the controller includinga circuit board, anda controller terminal located on a first facing surface and electrically connected to the circuit board;

a switch accommodated in the housing, the switch including a switch terminal located on a second facing surface facing the controller, the switch terminal being in direct contact with the controller terminal and electrically connected to the controller terminal; and

a seal between the first facing surface and the second facing surface, the seal sealing a periphery of the controller terminal and a periphery of the switch terminal with the controller terminal being in direct contact with the switch terminal,

wherein the first facing surface is a surface of the controller facing the switch.

The power tool according to the above aspect of the present disclosure has highly airtight electrical connection between the controller and the switch to effectively prevent a short circuit.

DETAILED DESCRIPTION

Embodiments of the present disclosure will now be described with reference to the drawings.

FIG.1is a side view of a grinder as an example of a power tool.FIG.2is a longitudinal central sectional view of the grinder.FIG.3is an enlarged view of the rear ofFIG.2.

A grinder1includes a housing including a gear housing2, a motor housing3, and a rear cover4in this order from the front. The gear housing2is formed from a metal. The motor housing3and the rear cover4are formed from a resin. A spindle5protrudes downward from the gear housing2.

The motor housing3is cylindrical and extends in the front-rear direction. The motor housing3accommodates a motor6. The motor housing3holds, on its left side surface, a switch knob7in a slidable manner. The rear cover4is cylindrical and extends in the front-rear direction. The rear cover4accommodates a switch8and a controller9. The rear cover4is connected to a power cable10on its rear.

The motor6is a commutator motor including a stator11, a rotor12, and a commutator13. An output shaft14included in the rotor12extends frontward and has its distal end protruding into the gear housing2. The output shaft14receives a bevel gear15at the distal end. The output shaft14receives a fan16in a front portion of the motor housing3.

A partition17is located between the gear housing2and the motor housing3. An output shaft14extends through the partition17. The partition17receives a bearing18that supports the output shaft14.

A bevel gear19is mounted on an upper portion of the spindle5inside the gear housing2. The bevel gear19meshes with the bevel gear15on the output shaft14. The gear housing2has multiple outlets20in the front surface.

The gear housing2receives a bearing box21attached to its lower portion. The spindle5is supported by a bearing22and two bearings23. The bearing22is held in the gear housing2. The two bearings23are held in the bearing box21. The spindle5protrudes from the bearing box21. The spindle5has a lower end to receive a tip tool24, such as a grinding disc.

An inner housing25is integral with the rear end of the motor housing3. The inner housing25extends rearward in the rear cover4. The inner housing25includes a front bearing holder26, a pair of brush holders27, and a mount plate28, as also shown inFIGS.4to6. The pair of brush holders27are located above and below the bearing holder26.

The bearing holder26is cylindrical and has its axis in the front-rear direction. The bearing holder26holds a bearing29that supports the rear end of the output shaft14. The brush holder27is a rectangular frame as viewed in plan with openings at the top and the bottom. The brush holder27holds brushes30in contact with the commutator13.

The mount plate28extends rearward from the bearing holder26and the brush holder27. The mount plate28is parallel to the plane defined by the front-rear and lateral directions. The mount plate28includes a switch holder31and a controller holder32. The switch holder31is located above the mount plate28and holds the switch8. The controller holder32is located below the mount plate28and holds the controller9. A cable receiver33is located behind the switch holder31and on the upper surface of the mount plate28. The cable receiver33clamps the power cable10.

The switch holder31includes an upper retainer wall35, an upper attachment seat36, and an upper screw boss37.

As also shown inFIG.7, the upper retainer wall35is a rectangular wall as viewed in plan and extends vertically on the upper surface of the mount plate28and is open toward the top. The upper retainer wall35includes an upper front wall38, left and right upper side walls39A and39B, and an upper rear wall40. The left upper side wall39A is located on the front alone. The upper side wall39A has a cutout41at its rear to open the left side of the upper retainer wall35. A front rib42extending in the vertical direction is located at the middle of the upper front wall38in the lateral direction. The front rib42extends vertically between the upper surface of the bearing holder26and the rear surface of the upper brush holder27. Vents43extends in the front-rear direction through lower portions of the joints between the upper front wall38and the left side wall39A and between the upper front wall38and the right upper side wall39B.

The front portions of the left and right upper side walls39A and39B are higher than the upper front wall38and the upper rear wall40. The upper side walls39A and39B have a pair of rectangular grooves44on their opposing inner surfaces. Each rectangular groove44extends vertically. A locking tab45extends in the front-rear direction on the outer surface of the left upper side wall39A. A pair of left and right partition ribs46extends vertically on the rear surface of the upper rear wall40. The mount plate28has a pair of holes47on the left and right of the partition ribs46.

The mount plate28has a through-hole48between the left upper side wall39A and the right upper side wall39B. The through-hole48is rectangular and elongated laterally as viewed in plan.

The upper attachment seat36is located at the rear of the through-hole48between the left upper side wall39A and the right upper side wall39B. The upper attachment seat36is located lower than the rear upper surface of the mount plate28and extends laterally. A bottom rib49extends in the front-rear direction at the middle of the upper attachment seat36in the lateral direction.

The upper screw boss37is located behind and rightward from the upper attachment seat36and extends upward on the mount plate28.

The controller holder32includes a lower retainer wall50and a lower attachment seat51, as also shown inFIG.8. The lower retainer wall50extends downward from a front portion of the mount plate28. The lower retainer wall50extends downward from the left and right side surfaces of the mount plate28and surrounds the lower front surface of the mount plate28.

The lower retainer wall50includes a lower front wall52and left and right lower side walls53A and53B. The lower front wall52is integral with the lower brush holder27. The left and right lower side walls53A and53B include front portions continuous with the lower front wall52and extending downward farther than rear portions. The left and right lower side walls53A and53B receive a pair of lower screw bosses54on their outer front surfaces. Each lower screw boss54extends rearward.

The lower attachment seat51is located on the full lower surface of the mount plate28, including the area surrounded by the lower retainer wall50. A protrusion55extends downward in a front portion of and at the middle of the lower attachment seat51in the lateral direction. The protrusion55is located frontward from the through-hole48. A recess56is recessed upward on the lower surface of the mount plate28between the protrusion55and the hole47. The through-hole48is located in the recess56.

The switch8is a push switch that is turned on in response to a pressing operation on a button61protruding from the housing60. The housing60has a rectangular shape fitting between the left and right upper side walls39A and39B of the switch holder31. The button61is located on the rear surface of the housing60facing rearward. As also shown inFIGS.9A to9E, the housing60includes a pair of positive and negative output terminals62on the left and right of its upper front surface. Each output terminal62is a plate extending frontward. A pair of left and right protection plates63is located on the upper plate of the housing60. Each protection plate63covers the output terminal62from above, excluding the distal end of the corresponding output terminal62. Each protection plate63protrudes frontward.

A pair of left and right ridges64is located between the left and right protection plates63. Each ridge64extends across the upper surface and the front surface of the housing60. The pair of left and right ridges64are apart from each other laterally at a predetermined interval. A sealing member (a sponge in this example)65is bonded to the front surface of the housing60between the ridges64. The sealing member65is a strip plate extending vertically. The sealing member65is aligned with the front rib42on the upper front wall38of the upper retainer wall35. A pair of side ribs66extending vertically is located on the left and right side surfaces of the housing60. The side ribs66are aligned with the rectangular grooves44on the left and right upper side walls39A and39B of the upper retainer wall35.

A pair of positive and negative switch terminals67is located on the left and right of the front portion of the housing60. Each switch terminal67is a plate extending downward. On a lower surface8aof the switch8A, a rectangular cylinder68extends downward in the front portion of the housing60. The rectangular cylinder68surrounds the area including the switch terminal67in the lateral and front-rear directions. The rectangular cylinder68has a flat lower surface. A divider69is located between the left and the right switch terminals67in the rectangular cylinder68. The divider69extends downward and divides the inside of the rectangular cylinder68into left and right parts. The divider69has a lower end flush with the lower surface of the rectangular cylinder68.

The front plate of the housing60includes a lower part corresponding to a front part of the rectangular cylinder68as a separate closing plate70. The closing plate70is fixed to the front plate by vibration welding or another method after the switch terminal67is attached inside the housing60. Retrofitting the closing plate70in this manner allows the front surface of the housing60to be open when the switch terminal67is attached. The switch terminal67can thus be attached easily.

At the rear of the rectangular cylinder68, the rear lower surface of the housing60is stepped and raised from the lower end of the rectangular cylinder68. A lower groove71extends in the front-rear direction at the middle of the rear lower surface of the housing60in the lateral direction. The lower groove71is aligned with the bottom rib49on the upper attachment seat36.

A positioning plate75is located above the switch8. The positioning plate75is rectangular in a plan view having a slightly larger length than the lateral width of the housing60. A fitting recess76is located on the lower surface of the positioning plate75. The fitting recess76extends in the front-rear direction and is fitted to the ridge64on the upper surface of the housing60. A fitting rib77extends in the front-rear direction inside the fitting recess76. The fitting rib77fits between the pair of ridges64.

A screw tab78extends rearward from the rear right end of the positioning plate75. The screw tab78has a through-hole79. The through-hole79is aligned with the upper screw boss37. The through-hole79can receive a screw80for thread engagement.

A rear abutting tab81extends downward from the rear end of the positioning plate75on the left of the screw tab78. The lower end of the rear abutting tab81can come in contact with the rear surface of the housing60. A side abutting tab82extends downward from the left edge of the positioning plate75. The side abutting tab82can come in contact with the outer surface of the left upper side wall39A of the upper retainer wall35. The side abutting tab82has an engagement hole83. The engagement hole83is engageable with the locking tab45on the upper side wall39A.

The controller9includes a case85, a circuit board86, a terminal board87, and a heat sink88, as also shown inFIG.3.

The case85has a lateral width fittable between the left and right lower side walls53A and53B of the controller holder32. The case85is rectangular in a plan view and extends in the front-rear direction, as also shown inFIGS.7and8. The case85is dish-shaped, with a surrounding wall89standing downward. Positioning tabs90are located on the left and right outer surfaces of the surrounding wall89. Each positioning tab90has a through-hole91. Each through-hole91is aligned with a lower screw boss54on the lower side walls53A and53B. The case85has, on its upper surface, a recess92at its front middle. The recess92is fitted to the protrusion55on the mount plate28.

The circuit board86has a lateral width fittable to the case85. The circuit board86is rectangular in a plan view extending in the front-rear direction. A control unit such as a capacitor and a triac is mounted on the lower surface of the circuit board86. A variable speed dial93for the motor6is placed on the lower surface of the rear end of the circuit board86.

The terminal board87is formed from a resin and located above the circuit board86. A pair of power input terminals94is mounted on the rear upper surface of the terminal board87. The power input terminals94are connected to the power cable10. The power input terminals94are held in protective rectangular cylinders95and protrude upward. The protective rectangular cylinders95are integral with the terminal board87and protrude upward. The protective rectangular cylinders95can extend through the holes47on the rear of the mount plate28. The power input terminals94are electrically connected to the circuit board86. Screws96connecting the power cable10are screwed into the upper end of the power input terminals94.

Controller terminals97are located in front of the power input terminals94on the terminal board87. The controller terminals97are connected to the switch8. The controller terminals97are insert-molded into front rectangular cylinders98formed from a resin. The upper ends of the controller terminals97are connected to the switch8. The upper end of each controller terminal97is a female terminal with a pair of front and rear terminal boards. The switch terminal67in the switch8is placed between the terminal boards of the controller terminals97to be in contact with each other. The lower ends of the controller terminals97are electrically connected to the circuit board86. The front rectangular cylinders98have a size fittable into the left and right of the rectangular cylinder68of the switch8from below.

The heat sink88is a metal plate covering the circuit board86from below, excluding the variable speed dial93. The heat sink88is connected to a triac with screws to be in thermal contact.

The controller9is molded with the circuit board86receiving the terminal board87on the upper surface and the heat sink88on the lower surface in the case85with a resin99filling above the heat sink88in the case85. The power input terminals94and the controller terminals97protrude upward from an upper surface9aof the controller9.

The controller9has, on its upper surface9a,an elastic sheet100formed from a sponge. The elastic sheet100is rectangular in a plan view covering the upper surface of the case85between the power input terminals94and the recess92. The front rectangular cylinders98of the controller terminals97protrude upward through relief holes101. The relief hole101is elongated laterally and formed in the elastic sheet100. The relief hole101is slightly smaller than the opening of the rectangular cylinder68.

The elastic sheet100is elongated rearward to cover the periphery of the controller terminals97. This allows the elastic sheet100to be located in the reverse direction when the switch8is attached in the reverse direction, the switch terminal67is shifted to the rear, and the controller terminal97is also placed on the rear. The large area of the elastic sheet100also enhances the sealing with the mount plate28.

The assembly of the switch8and the controller9will now be described.

The recess92on the case85of the controller9is fitted to the protrusion55on the mount plate28from below, with the heat sink88facing downward and the variable speed dial93at the rear. The power input terminals94are placed from below through the holes47in the mount plate28. The controller terminals97are placed from below through the through-hole48. In an actual assembly, the mount plate28is turned upside down, and the controller9is attached to the mount plate28from above.

The controller9is then placed on the lower attachment seat51on the mount plate28with the left and right positioning tabs90in contact with the rear of the lower screw bosses54. In this state, screws102extending through the through-holes91in the positioning tabs90from the rear are screwed into the lower screw bosses54. As shown inFIGS.3,6, and11, the controller9is then fastened to the lower attachment seat51on the mount plate28. As shown inFIG.10, the power input terminals94protrude through the holes47in the mount plate28to the left and right of the partition ribs46. The controller terminals97protrude through the through-hole48in the mount plate28to above the mount plate28.

With the button61on the rear and the side ribs66on the housing60fitting into the left and right grooves44on the upper retainer wall35, the switch8is pushed in from above between the left and right upper side walls39A and39B. The rear lower surface of the housing60is then placed on the upper attachment seat36, and the bottom rib49on the upper attachment seat36fits into the lower groove71on the lower surface of the housing60. The front rib42on the upper front wall38fits between the ridges64on the front surface of the housing60.

As shown inFIGS.10to12, the rectangular cylinder68in the housing60fits into the through-hole48in the mount plate28. The front rectangular cylinders98of the controller terminals97protruding through the through-hole48are then placed into the rectangular cylinder68from below. The switch terminals67are placed into and connected to the controller terminals97.

The assembling order of the switch8and the controller9may be reversed.

With the ridges64fitting in the fitting recess76and the fitting rib77fitting between the ridges64, the positioning plate75is placed to cover the upper surface of the housing60. This causes the locking tab45on the left upper side wall39A to be engaged in the engagement hole83in the side abutting tab82. The screw80is placed from above into the through-hole79in the screw tab78and screwed into the upper screw boss37. This causes the positioning plate75to press the housing60from above and thus allows the housing60to be fastened to the upper attachment seat36.

In this state, the lower end of the rectangular cylinder68presses the elastic sheet100, elastically deforming the elastic sheet100. This causes areas around the connections between the switch terminals67and the controller terminals97to be sealed by close contact between the rectangular cylinder68and the elastic sheet100.

At the same time, at the front surface of the housing60, the front rib42presses the sealing member65, elastically deforming the sealing member65. This causes the front surface of the housing60and the upper front wall38to be sealed between the left and right output terminals62by close contact between the front rib42and the sealing member65.

The output terminals62are connected to connectors106(FIG.12) of a lead wire105directed from the stator11in the motor6. Each connector106includes an insulating cover106a.The insulating cover106acovers the connection between the connector106and the output terminal62. Each output terminal62is partitioned by the front rib42and the sealing member65, and is covered with the protection plate63from above. This reduces the likelihood of a short circuit being formed by, for example, iron powder.

A pair of cables of the power cable10fixed to the cable receiver33is electrically connected to the power input terminals94with the screws96. Each power input terminal94is partitioned by the partition ribs46and the protective rectangular cylinders95. This reduces the likelihood of a short circuit being formed by, for example, iron powder.

The switch knob7is connected to a slide bar107. The slide bar107extends in the front-rear direction on the left of the upper retainer wall35in the motor housing3. The slide bar107includes a pressing portion108that bends to the right. The pressing portion108protrudes inside the upper retainer wall35through the cutout41in the upper retainer wall35and is located behind the button61on the switch8. As the slide bar107moves forward in response to a sliding operation on the switch knob7forward, the pressing portion108presses the button61. A coil spring109between the slide bar107and the inner housing25urges the slide bar107and the switch knob7toward a retracted position at which the pressing portion108does not press the button61.

The rear cover4is placed from the rear to cover the inner housing25with the switch8and the controller9assembled together. At the position at which the front end of the rear cover4overlaps the rear end of the motor housing3, a screw110extending through the rear surface of the rear cover4is screwed into a boss111on the rear surface of the mount plate28. This causes the rear cover4to be fastened to the inner housing25. The rear cover4has multiple inlets112in its rear, right and left side, and lower surfaces.

When the switch knob7is slid forward, the slide bar107moves forward and the pressing portion108pushes the button61on the switch8, thus causing the switch8to be turned on. Thus, the controller9drives the motor6to rotate the output shaft14. The spindle5rotates via the bevel gears15and19, thus allowing grinding or other operations using the tip tool24.

When the fan16rotates as the output shaft14rotates, outside air is sucked through each inlet112in the rear cover4. A part of the air sucked through the inlets112flows above the mount plate28and passes between the upper retainer wall35and the switch8, and becomes airflow passing through the vent43to the motor6. This cools the switch8and the motor6. The air sucked through the inlet112on the lower surface becomes airflow to the motor6after passing through the heat sink88. Thus, the airflow is intensively in contact with the heat sink88, which facilitates heat dissipation of the controller9(in particular, the triac).

When the switch knob7is released from being slid forward, the slide bar107retracts under an urging force from the coil spring to release the pressure on the button61applied by the pressing portion108. Thus, the switch8is turned off to stop the motor6.

The grinder1according to the embodiment includes the motor6, the controller9including the circuit board86and the controller terminals97electrically connected to the circuit board86, and the switch8including the switch terminals67electrically connected to the controller terminals97accommodated in the rear cover4(housing). The controller terminals97are located on the upper surface9a(first facing surface facing the switch) of the controller9. The switch terminals67are located on the lower surface8a(a second facing surface facing the controller) of the switch8. The controller terminals97and the switch terminals67are in direct contact with each other and are electrically connected to each other. The elastic sheet100(seal) is located between the upper surface9aof the controller9and the lower surface8aof the switch8to seal the periphery of controller terminals97and the periphery of the switch terminals67with the controller terminals97being in direct contact with the switch terminals67.

This structure achieves the sealing between the upper surface9aof the controller9and the lower surface8aof the switch8using the elastic sheet100with a simple assembly operation. Thus, the electrical connection between the controller9and the switch8is sealed tightly to effectively prevent a short circuit.

The elastic sheet100is located on the upper surface9aof the controller9. The rectangular cylinder68(cylinder) formed from a resin is located on the lower surface8aof the switch8. The rectangular cylinder68is in contact with the elastic sheet100and seals the periphery of the controller terminals97and the periphery of the switch terminals67with the controller terminals97being in direct contact with the switch terminals67.

The rectangular cylinder68comes in surface contact with the elastic sheet100, thus enhancing sealing.

The front rectangular cylinders98(second cylinder) formed from a resin are located on the upper surface9aof the controller9. The front rectangular cylinders98cover the periphery of the controller terminals97and protrude toward the rectangular cylinder68. The front rectangular cylinders98are placed in the rectangular cylinder68with the controller terminals97being in direct contact with the switch terminals67.

The distance of a labyrinth to the contact between the terminals is increased, thus enhancing sealing.

The rectangular cylinder68and the front rectangular cylinders98are integral with the controller9or the switch8. This structure stabilizes the positions of the front rectangular cylinders98and the rectangular cylinder68, thus allowing the front rectangular cylinders98to be easily placed into the rectangular cylinder68.

The rectangular cylinder68and the front rectangular cylinders98cover the full portion of the periphery of the controller terminals97or the switch terminals67.

Thus, the controller terminals97and the switch terminals67are reliably protected.

The motor housing3(housing) includes an inner housing25between the switch8and the controller9. The switch holder31holding the switch8is located on the upper surface of the inner housing25. The controller holder32holding the controller9is located on the lower surface of the inner housing25. The rectangular cylinder68is placed in the front rectangular cylinders98through the through-hole48in the inner housing25.

This structure enhances the sealing of the electrical connection between the controller9and the switch8, and the through-hole48also allows the positioning of the rectangular cylinder68.

The upper screw boss37, the positioning plate75, and the screws80(switch positioner) are located to position the switch8in the inner housing25.

Thus, the switch8can be stably positioned without rattling.

The lower screw bosses54, the positioning tabs90, and the screws102(controller positioner) are located to position the controller9in the inner housing25.

Thus, the controller9can be stably positioned without rattling.

The switch8includes the housing60and the output terminals62connected to the motor6. The housing60includes the protection plate63(terminal protector) covering a part of the output terminals62in a contactless manner.

This structure thus prevents a short circuit from being formed between the output terminals62.

The controller9includes a pair of power input terminals94to receive power to the circuit board86. The protective rectangular cylinders95(protector) are located at least on the surfaces of the pair of power input terminals94facing each other to protect the power input terminals94.

This structure thus prevents a short circuit from being formed between the power input terminals94.

The seal is the elastic sheet100(sheet elastic member).

The elastic sheet can have a large area with enhanced sealing.

Modifications will now be described.

In the embodiment, an elastic sheet is used as a seal in the controller case, but a strip-shaped seal may surround the periphery of the controller terminals. The seal is not limited to a sponge but may be a rubber member or another member.

In the embodiment, the two switch terminals are covered with a single rectangular cylinder, but a rectangular cylinder may be used for each switch terminal. In this case, each rectangular cylinder may be placed in the corresponding front rectangular cylinder in the controller terminal.

In the embodiment, the cylinder (rectangular cylinder) is located in the housing of the switch and the seal (elastic sheet) is located in the case of the controller. Conversely, the cylinder may be located in the case of the controller and the seal may be located in the housing of the switch.

The shapes of the terminals are not limited to those in the embodiment. The switch terminals may be female, and the controller terminals may be male. The cylinder and the second cylinder are not limited to the rectangular cylinders as in the embodiment, but may be circular cylinders. The cylinder and the second cylinder are not limited to the cylinders covering the full portion of the periphery of the terminal, but may be shorter than the terminal.

The cylinder and the second cylinder may be eliminated. For example, the controller may include no case, the circuit board may be covered with an insulating material, or a plate may be partially attached to the controller. In this case, the controller terminals are located on the surface of the controller facing the switch (first facing surface). Similarly, the switch may include no housing. In this case, the switch terminals are located on the surface of the switch facing the controller (second facing surface). Thus, a seal covering the periphery of both the terminals is to be placed between the two facing surfaces.

In the embodiment, the switch is located upward and the controller is located downward. Conversely, the switch may be located downward, and the controller may be located upward, or the switch and the controller may be located laterally.

The switch may be located with the button facing frontward. An ON/OFF operation on the switch may be performed by the pressing portion of the slide bar independently of the orientation of the button, or may be performed by a link member that swings in coordination with the slide of the slide bar. The switch may be turned on or off by swinging of a lever, rather than by pressing of a button.

The housing may have any shape other than the shape described in the embodiment. For example, the closing plate may be eliminated, and an integral rectangular cylinder may be located in the housing.

The switch positioner is not limited to the positioning plate in the embodiment. The positions and the number of screws may be changed, or the housing may be screwed directly to the inner housing without the positioning plate. The positioning is not limited to the positioning using screws, but may be performed using a locking tab in the inner housing engaged with the housing.

The terminal protector for the output terminal is not limited to the protection plate covering the upper surface alone as in the embodiment. The terminal protector may be semi-cylindrical or cylindrical to cover multiple surfaces of the output terminal. The terminal protector may be eliminated.

Sealing between the output terminals may be performed with ribs on the housing and a sealing member on the inner housing, conversely to the structure in the embodiment. The shape of the ribs and the sealing members may be changed as appropriate. Sealing may not include a sealing member and may be performed through contact between ribs. The seal between the output terminals may be eliminated.

The controller positioner is not limited to the lower screw boss and the positioning tab in the embodiment. A screw boss may be located in the case and a positioning tab in the controller holder. The positioning is not limited to the positioning using screws, but may be performed using a locking tab in the inner housing engaged with the housing, similarly to the screw.

The protector for the power input terminal is not limited to the protective rectangular cylinder in the embodiment. A wall may cover the facing surface of the power input terminal alone, or the protector may be eliminated. The power cable may be electrically connected in a manner other than with screws.

The case and the circuit board may have any shape other than the shape described in the embodiment. The case and the circuit board may extend laterally, rather than in the front-rear direction. The case and the circuit board may be square or in other shapes as viewed in plan. The variable speed dial may have another shape or be at another position, or may be eliminated.

The shape and the position of the heat sink are not limited to the shape and the position described in the embodiment. The heat sink may be eliminated.

The structure of the grinder is not limited to the structure described in the embodiment. A brushless motor may be used as a motor. A brake for the output shaft may be located in the front portion of the motor housing.

The power tool may be a device other than a grinder. The present disclosure is also applicable to other power tools, such as a polisher, an angle screw driver and an angle impact driver.

The power tool may be a direct current (DC) machine powered by a battery.

REFERENCE SIGNS LIST