Work tool

A work tool includes: a motor; a housing including a gripping part; an electronic switch; a controller controlling the motor based on a signal from the switch; an operating part provided at the gripping part; and an intervening part movably intervened between the operating part and the switch. The switch is provided at the housing at a first position in an axial direction of the gripping part, and is switchable between an ON position for driving the motor and an OFF position for stopping the motor. A direction connecting the ON position and the OFF position to each other is a crossing direction crossing the axial direction. The operating part is movable in the crossing direction to drive and stop the motor. The intervening part transmits movement to the switch by a moving amount smaller than movement in the crossing direction of the operating part passing through the first position.

TECHNICAL FIELD

The present invention relates to a work tool.

BACKGROUND ART

Conventionally, electric work tools capable of driving or stopping a motor in response to an operator's operations on a lever provided on a housing have been widely known. Patent Literature 1 discloses, as an example of such a work tool, an electric grinder having a switch lever and a switch.

With the electric grinder of Patent Literature 1, the operator presses the switch lever into a housing. At this time, a push bar provided on the switch lever presses a protruding part on the switch upward, whereby electric power from a commercial power supply is supplied to a motor.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

With a configuration in Patent Literature 1, the switch lever needs to be pivotally moved by a large amount relative to the housing so that the operator can feel that the switch lever is pressed inward. However, the switch lever is allowed to be moved by only a small amount when turning on the switch (when the switch lever contacts the protruding part and presses the protruding part upward in a case of Patent Literature 1). Therefore, the switch must be disposed at the downstream end on a pivot path of the switch lever, which reduces freedom in arranging the switch inside the housing.

In view of the foregoing, it is an object of the present invention to provide a work tool that can facilitate the arrangement of a switch in a housing when a lever-type operating part for driving a motor is provided.

Solution to Problem

In order to attain the above and other objects, the present invention provides a work tool including: a motor; a housing accommodating therein the motor, the housing including a gripping part that can be gripped by an operator; an electronic switch, the switch being provided at the housing at a first position in an axial direction of the gripping part, the switch being switchable between an ON position for driving the motor and an OFF position for stopping the motor, a direction connecting the ON position and the OFF position to each other being a direction crossing the axial direction; a controller controlling the motor on a basis of a signal from the switch; an operating part provided at the gripping part, the operating part being movable in the crossing direction in order to drive and stop the motor; and an intervening part movably intervened between the operating part and the switch, the intervening part transmitting movement to the switch by a moving amount smaller than movement in the crossing direction of the operating part passing through the first position.

According to the work tool with the above configuration, since the intervening part is intervened between the switch and the operating part, movement of the operating part at the first position can be converted to small movement of the intervening part and transmitted to the switch. Accordingly, the switch need not be provided at the downstream end of a pivot path of the operating part even when the operating part is configured to be pivotally moved relative to the housing by a large amount such that an operator can feel that a switch lever is pressed inward, thereby securing freedom in arrangement of the switch inside the housing.

In the above configuration, it is preferable that: the intervening part includes: a lever; and a pivot shaft supported by the housing and supporting the lever such that the lever is pivotally movable relative to the housing; movement of the operating part is transmitted to the lever by contact of the operating part with the lever at a second position in the axial direction; and the first position is positioned between the second position and the pivot shaft.

This can suitably attain a configuration in which movement of the operating part at the first position can be converted to small movement of the intervening part and transmitted to the switch.

Further, it is preferable that: the operating part includes a support shaft rotatably supported by the housing, the operating part being configured to be pivotally movable about the support shaft; and the second position is positioned between the first position and the support shaft in the axial direction.

This can also suitably attain a configuration in which movement of the operating part at the first position can be converted to small movement of the intervening part and transmitted to the switch.

Further, it is preferable that the intervening part is configured to be movable between a pressed position where the intervening part presses the switch such that the switch is at the ON position and a release position where the intervening part is positioned away from the switch, the intervening part being configured to be moved from the pressed position to the release position upon transmission of movement in the crossing direction of the operating part to the intervening part.

With this configuration, the motor can be suitably stopped since the intervening part is configured to be moved from the pressed position to the release position in response to the operator releasing operation on the operating part.

Further, it is preferable that: the intervening part and the operating part are configured to be engageable with each other; and operation in a direction for driving the motor and operation in a direction for stopping the motor in the crossing direction of the operating part are configured to be transmitted to the intervening part.

With this configuration, the motor can be suitably driven or stopped in response to the operator's operations on the operating part in a configuration in which the switch is turned on and off via the intervening part.

Further, it is preferable that an urging member is provided between the operating part and the housing to urge the operating part such that the intervening part is moved from the pressed position to the release position.

With this configuration, the intervening part can be moved from the pressed position to the release position through a simple configuration.

Further, it is preferable that: the work tool further includes: a first urging member provided between the intervening part and the switch to urge the intervening part to be moved from the pressed position to the release position; and a second urging member provided between the operating part and the housing to urge the operating part; and the intervening part is configured to be moved to the release position in accordance with movement of the operating part caused by application of an urging force by the second urging member.

With this configuration, the intervening part can be moved from the pressed position to the release position through a simple configuration. Further, if the first urging member is deteriorated, the urging force of the second urging member urging the operating part can move the intervening part to the release position.

Further, it is preferable that: the housing includes: a motor housing accommodating therein the motor; and a rear housing accommodating therein the switch; and the operating part is supported by the rear housing, and the intervening part is supported by the motor housing.

With this configuration, the intervening part is supported by the motor housing accommodating the motor therein. Therefore, a mechanism for supporting the intervening part need not be provided in the rear housing. As a consequence, a space for accommodating the switch can be easily secured in the rear housing when providing the switch in the rear housing.

Further, it is preferable that: the motor housing is formed through integral molding to have a cylindrical shape; the intervening part includes: a lever; a pivot shaft supported by the housing and supporting the lever such that the lever is pivotally movable relative to the housing; and a support part supporting the lever and the pivot shaft; and the intervening part is supported by the motor housing by attachment of the support part to the motor housing.

With this configuration, since the support part is attached to the motor housing to allow the intervening part to be supported by the motor housing, there is no need to provide a threaded boss for fastening the intervening part to the motor housing formed into a cylindrical shape, thereby avoiding an increase in an external size of the motor housing.

Further, it is preferable that: the motor includes a rotation axis; a holding part is provided at the motor housing, the holding part being positioned inside the motor housing and holding a bearing supporting the rotation axis; and the support part is held by the holding part.

With this configuration, the intervening part can be supported by the motor housing through a simple configuration.

Further, it is preferable that: an intake port through which air for cooling the controller is introduced is formed in the rear housing; and the switch and the intervening part are disposed at positions close to an inner surface of the rear housing.

With this configuration, since the intervening part is provided at a position close to the inner surface of the rear housing, the intervening part can be restrained from blocking cooling air introduced through intake port formed in the rear housing, thereby improving cooling efficiency.

Further, it is preferable that: the controller includes an inverter circuit including a plurality of switching elements for controlling the motor; and the intervening part and the inverter circuit are positioned at positions the same as each other in the axial direction.

With this configuration, the intervening part is not positioned upstream of the inverter circuit along a path of cooling air when the path extends in the axial direction of the gripping part. Therefore, the intervening part does not block cooling air on the upstream side of the inverter circuit, thereby improving cooling efficiency for the inverter circuit.

The present invention also provides a work tool including: a motor; a housing accommodating therein the motor; a switch switchable between an ON position for driving the motor and an OFF position for stopping the motor; an operating part including a support shaft supported by the housing, the operating part being pivotally movable relative to the housing about the support shaft in a first direction; and an intervening part intervened between the operating part and the switch, the intervening part including a pivot shaft supported by the housing, the intervening part being pivotally movable relative to the housing about the pivot shaft in a second direction opposite the first direction, the intervening part being capable of pressing the switch by pivotal movement of the intervening part relative to the housing in the second direction, and a contact part is provided at the operating part, the contact part being positioned closer to the support shaft than the switch is to the support shaft and capable of contacting the intervening part, the intervening part causing the switch to be moved to the ON position by the contact part pressing the intervening part in accordance with pivotal movement of the operating part.

According to the work tool with the above configuration, since movement of the operating part at the first position can be converted to small movement of the intervening part and transmitted to the switch, the switch need not be provided at the downstream end of a pivot path of the operating part even when the operating part is configured to be pivotally moved relative to the housing by a large amount such that an operator can feel that a switch lever is pressed inward, whereby freedom in arrangement of the switch inside the housing can be secured.

The present invention also provides a work tool including: a motor; a housing accommodating therein the motor, the housing including a gripping part that can be gripped by an operator and extending in a prescribed direction; a switch switchable between an ON position for driving the motor and an OFF position for stopping the motor, a direction connecting the ON position and the OFF position to each other being a direction crossing the prescribed direction; an operating part provided at the gripping part, the operating part being movable in the crossing direction in order to drive and stop the motor; and an intervening part movably intervened between the operating part and the switch, and the intervening part is configured to be movable between a pressed position where the intervening part presses the switch such that the switch is at the ON position and a release position where the intervening part is positioned away from the switch, the intervening part being configured to be moved from the pressed position to the release position upon transmission of movement in the crossing direction of the operating part to the intervening part.

According to the work tool with the above configuration, since the intervening part is configured to be moved from the pressed position to the release position in response to the operator releasing the operation to the operating part, the motor can be suitably stopped.

The present invention also provides a work tool including: a motor; a housing accommodating the motor, the housing including a gripping part that can be gripped by an operator; an operating part provided at the gripping part, the operating part being movable in a prescribed direction crossing an axial direction of the gripping part relative to the housing in order to drive and stop the motor; an intervening part movable between a motor drive position and a motor stop position relative to the housing in accordance with movement of the operating part; and a switch including a detection part positioned at a prescribed position in the axial direction of the gripping part to detect a position of the intervening part relative to the housing, the switch controlling the motor to be driven when the detection part detects that the intervening part is at the motor drive position, the switch controlling the motor to be stopped when the detection part detects that the intervening part is at the motor stop position, and the intervening part is movable from the motor stop position to the motor drive position in the prescribed direction passing through the prescribed position by a moving amount smaller than movement of the operating part.

According to the work tool with the above configuration, since movement of the operating part at the first position can be converted to small movement of the intervening part and transmitted to the switch, the switch need not be provided at the downstream end of a pivot path of the operating part even when the operating part is configured to be pivotally moved relative to the housing by a large amount such that an operator can feel that a switch lever is pressed inward. Accordingly, freedom in arrangement of the switch inside the housing can be secured.

Advantageous Effects of Invention

According to the work tool of the present invention, the arrangement of the switch in the housing can be facilitated even when the lever-type operating part for driving the motor is provided.

DESCRIPTION OF EMBODIMENTS

A disc grinder1as an example of a work tool according to a first embodiment of the present invention will be described while referring toFIGS.1to14. The disc grinder1is an electric work tool used to grind, cut, and the like workpieces using a disc-shaped end bit tool (such as a grinding wheel).

In the following description, “front”, “rear”, “up”, and “down” appearing in the drawings are used to define a frontward direction, a rearward direction, an upward direction, and a downward direction, respectively. Additionally, “right” and “left” when viewing the disc grinder1from the rear side thereof define a rightward direction and a leftward direction, respectively. When dimensions, numerals, and the like are referenced in this specification, the values are intended to include not only dimensions and numerals that correspond exactly to these dimensions, numerals, and the like, but also dimensions, numerals, and the like that approximately correspond (values within a range of manufacturing error, for example). Similarly, terms such as “identical”, “orthogonal”, “parallel”, “correspond”, “flush”, and the like are intended to include the meanings “approximately identical”, “approximately orthogonal”, “approximately parallel”, “approximately correspond”, “approximately flush”, and the like, respectively.

As illustrated inFIGS.1,2, and14, the disc grinder1includes a housing2, a filter part3, a lever part4, a motor5, a circuit board part6, a power transmission part7, an output part8, a power supply circuit9(seeFIG.14), a controller10(seeFIG.14), and an electronic switch11(seeFIG.14). A grinding wheel P as an example of the end bit tool is attachable to and detachable from the output part8. The electronic switch11includes a switch plunger11A.

As illustrated inFIG.1, the housing2mainly includes a motor housing21, a tail cover22, and a gear housing23. In the present embodiment, the housing2is constituted by three components arranged in a front-rear direction, but the housing2is not limited to this configuration. For example, the motor housing21and the tail cover22may be configured single piece structure, or may have another divided configuration. As illustrated inFIG.2, the housing2includes fixing screws2B,2C,2D, and2E. The housing2is an example of the “housing” of the present invention.

The motor housing21illustrated inFIGS.1and2is made of resin or metal, and accommodates the motor5therein. The motor housing21is configured as a cylindrical housing elongated in the front-rear direction and cannot be divided in a radial direction thereof. A bearing holding part211is provided at a rear portion inside the motor housing21. The motor housing21is an example of the “motor housing” of the present invention.

A female threaded hole211ais formed in an upper portion of the bearing holding part211to penetrate the bearing holding part211in the front-rear direction. A female threaded hole211bis formed in a lower portion of the bearing holding part211to penetrate the bearing holding part211in the front-rear direction. A through-hole penetrating the bearing holding part211in the front-rear direction is also formed in an approximate center portion in a radial direction of the bearing holding part211, and a ball bearing21A is provided at an inner surface of the through-hole. A configuration of the motor housing21will be described later in greater detail.

The tail cover22is made of resin or metal, and accommodates therein the circuit board part6. The tail cover22is configured as a cylindrical housing elongated in the front-rear direction and cannot be divided in a radial direction thereof. The tail cover22includes a rear wall formed with a through-hole22apenetrating the rear wall in the front-rear direction. As illustrated inFIG.2, a protruding part221, a support part22B, a power cord2A, and a base part60are provided at the tail cover22. The protruding part221is provided at a rear portion of the tail cover22, and protrudes downward from an outer circumferential surface of the tail cover22. The support part22B is provided at a lower portion of the tail cover22and extends in the front-rear direction. As illustrated inFIG.1, the support part22B has symmetrically configured wall portions on left and right sides. A through-hole22bis formed in each of the wall portions to penetrate the wall portions in a left-right direction. The tail cover22is an example of the “rear housing” of the present invention.

The power cord2A extends rearward from a rear end portion of the tail cover22. The power cord2A is configured to be connected to an AC power supply (e.g., a commercial AC power supply Q illustrated inFIG.14). A cylindrical part222is provided at a front portion of the power cord2A. The cylindrical part222has a general cylindrical shape that is elongated in an up-down direction. A protrusion222A is provided at the cylindrical part222. The protrusion222A protrudes inward from an inner surface of the cylindrical part222in a radial direction of the cylindrical part222.

The base part60is provided to fix the circuit board part6inside the tail cover22, and to fix the motor housing21and the tail cover22to each other. A front portion of the base part60has an upper portion formed with a through-hole60apenetrating the front portion of the base part60in the front-rear direction, and has a lower portion formed with a through-hole60bpenetrating the front portion of the base part60in the front-rear direction. The through-holes60aand60bare arranged at the same positions in the up-down and left-right directions as the female threaded holes211aand211bformed in the bearing holding part211of the motor housing21, respectively. In other words, the through-holes60aand60bare in communication with the female threaded holes211aand211bin the front-rear direction, respectively. A female threaded hole60cextending in the front-rear direction is formed in an upper portion of a rear portion of the base part60. The female threaded hole60cis arranged at the same position as the through-hole22aformed in the rear wall of the tail cover22in the up-down and left-right directions. In other words, the female threaded hole60cis in communication with the through-hole22ain the front-rear direction. The base part60also includes an extended part60A. The extended part60A forms a substantial columnar shape that is elongated in the up-down direction at a rear end portion of the base part60. An outer circumferential surface of the extended part60A has a shape identical to the inner surface of the cylindrical part222. A female threaded hole60dextending in the up-down direction is formed in the extended part60A.

In the present embodiment, the motor housing21and the tail cover22are connected to each other through the base part60. Specifically, the fixing screw2B is screwed into the female threaded hole211aformed in the bearing holding part211of the motor housing21through the through-hole60aof the base part60, and the fixing screw2C is screwed into the female threaded hole211bformed in the bearing holding part211through the through-hole60bof the base part60in order to fix the base part60and the motor housing21to each other. In the meantime, the fixing screw2D is screwed into the female threaded hole60cof the base part60through the through-hole22aformed in the rear wall of the tail cover22to fix the base part60and the tail cover22to each other. In the present embodiment, detachment of the power cord2A from the housing2is restrained by fitting the extended part60A of the base part60into the cylindrical part222of the power cord2A and screwing the fixing screw2E into the female threaded hole60dthrough the protrusion222A.

As illustrated inFIG.1, a gripping part20, which is a portion that an operator grips during operations, is provided to span across a rear portion of the motor housing21and a front portion of the tail cover22. A configuration of the tail cover22will be described later in greater detail.

The gear housing23illustrated inFIGS.1and2is manufactured through the integral molding of aluminum or other metals, for example. The gear housing23accommodates the power transmission part7therein and rotatably supports the output part8. Ball bearings23A and23B, and a needle bearing23C are provided in the gear housing23. A wheel guard24is also provided at a rear portion of a lower end portion of the gear housing23. The wheel guard24is formed so as to cover a rear portion of the grinding wheel P attached to the output part8. Further, as illustrated inFIG.1, an exhaust port part2ais provided at an upper portion of the gear housing23. The exhaust port part2ahas exhaust ports formed in a front portion of the gear housing23that penetrate the front portion of the gear housing23in the front-rear direction. In the present embodiment, the gear housing23and the motor housing21are fixed to each other by screws or another prescribed configuration.

The motor5illustrated inFIG.2is an AC brushless motor, and includes a rotation shaft51, a rotor52, a stator53, and three magnetic sensors54(seeFIG.14). The motor5is an example of the “motor” of the present invention.

The rotation shaft51extends in the front-rear direction. The rotation shaft51has a rear end portion supported by the ball bearing23A and a front portion supported by the ball bearing23A. With this configuration, the rotation shaft51is supported by the motor housing21and the gear housing23so as to be rotatable about an axis extending in the front-rear direction. A cooling fan51A is provided on the front portion of the rotation shaft51. The rotation shaft51is an example of the “rotation shaft” of the present invention.

The cooling fan51A is provided on the rotation shaft51so as to be rotatable together with the rotation shaft51. The cooling fan51A is configured such that the cooling fan51A can generate an airflow in the housing2between an intake port part22A and the exhaust port part2afor cooling the motor5by rotation upon receipt of a driving force of the motor5.

The rotor52is a rotor having permanent magnets (seeFIG.14) and is fixed to the rotation shaft51so as to be rotatable coaxially and together with the rotation shaft51. The stator53has a substantial hollow cylindrical shape elongated in the front-rear direction, and includes three star-connected stator coils U, V, and W (seeFIG.14). The three magnetic sensors54are Hall elements arranged on a circuit board (not illustrated), which is provided rearward of the stator53. The three magnetic sensors54are provided on the circuit board at intervals of approximately 60° in a circumferential direction of the rotation shaft51. Each of the magnetic sensors54is connected to the controller10via a signal line.

The power transmission part7illustrated inFIG.2is interposed between the motor5and the output part8inside the housing2. The power transmission part7decelerates the rotation of the rotation shaft51of the motor5and transmits the decelerated rotation to the output part8. The power transmission part7includes a pinion gear71and a bevel gear72those are meshingly engaged with each other.

The pinion gear71has a substantial hollow cylindrical shape elongated in the front-rear direction, and is fixed to a front end portion of the rotation shaft51so as to be rotatable coaxially and together with the rotation shaft51. An outer shape of the pinion gear71is formed to taper toward the front. A plurality of gear teeth is provided on an outer circumferential surface of the pinion gear71.

The bevel gear72has a general annular shape in a plan view and is configured to be rotatable about an axis extending in a direction orthogonal to the rotational axes of the rotation shaft51and the pinion gear71(i.e., in the up-down direction). A plurality of gear teeth those are meshingly engaged with the plurality of gear teeth on the pinion gear71is provided on the bevel gear72.

The output part8illustrated inFIG.2includes an output shaft81, and a washer82and a nut83that retain the grinding wheel P so as to be detachably attachable.

The output shaft81has a general columnar shape elongated in the up-down direction. The output shaft81is rotatably supported by the gear housing23via the needle bearing23C and the ball bearing23B. The output shaft81includes a male threaded part81A. The male threaded part81A constitutes a lower portion of the output shaft81and, has an outer circumferential surface into which threads are cut.

The washer82is provided at the lower portion of the output shaft81. The washer82includes a cylindrical part82A. The cylindrical part82A has an inner diameter identical to an outer diameter of the male threaded part81A, and the male threaded part81A is inserted into the cylindrical part82A.

The nut83is provided a lower end portion of the output shaft81. The nut83is configured to be screwed onto the male threaded part81A. The grinding wheel P is fixed to the output shaft81by inserting the cylindrical part82A of the washer82into a through-hole formed in a center of the grinding wheel P in a plan view, and, while an upper surface of the grinding wheel P contacts a lower surface of the washer82, screwing the nut83onto the male threaded part81A. Similarly, the grinding wheel P is detached from the output shaft81by unscrewing the nut83from the male threaded part81A.

For example, the grinding wheel P may be a resinoid flexible grinding wheel, a flexible grinding wheel, a resinoid grinding wheel, a sanding disc, or the like having a substantial circular shape in a plan view and a diameter of 100 mm. Depending on the types of material and abrasive grains selected for use, the grinding wheel P can perform flat and curved surface grinding of metal, synthetic resin, marble, concrete, and the like. While the grinding wheel P is fixed to the output shaft81, the rear portion of the grinding wheel P is covered with the wheel guard24provided on the rear portion of the lower end portion of the gear housing23. Note that, although the grinding wheel P is attached to the output part8in the present embodiment, other end bit tools, such as a bevel wire brush, a nonwoven brush, or a diamond wheel, are also attachable to the output shaft81.

As illustrated inFIG.2, the circuit board part6is accommodated in the tail cover22, and includes a circuit board61, and connectors62(seeFIG.10). The circuit board61is fixed to the base part60. Various circuit elements such as switching elements Q1-Q6 that configure an inverter circuit96, the controller10, and the like are mounted on the circuit board61. The connectors62are provided for connecting various signal lines. The circuit board part6is an example of the “controller” of the present invention.

Next, an electrical configuration of the disc grinder1will be described with reference toFIG.14. As illustrated inFIG.14, the disc grinder1includes the power supply circuit9and the controller10. The power supply circuit9and the controller10are mounted on the circuit board61.

The power supply circuit9is configured such that the power supply circuit9can supply power from the commercial AC power supply Q to the motor5. The power supply circuit9includes a noise filter circuit91, a rectifier circuit92, a positive line93, a negative line94, a smoothing circuit95, the inverter circuit96, and a constant voltage power supply circuit97.

The noise filter circuit91is a circuit provided for noise reduction. As illustrated inFIG.14, the noise filter circuit91includes a first terminal91A, a second terminal91B, a choke coil91C, and a capacitor91D. A voltage of the commercial AC power supply Q is applied across the first terminal91A and the second terminal91B while the power cord2A is connected to the commercial AC power supply Q. The choke coil91C and the capacitor91D are filtering elements for reducing noise propagated from the commercial AC power supply Q to the power supply circuit9. The choke coil91C is connected in series between the rectifier circuit92and the commercial AC power supply Q. The capacitor91D is connected in parallel with the commercial AC power supply Q.

As illustrated inFIG.14, the rectifier circuit92is a diode bridge circuit having four diodes92A (four rectifying elements). The rectifier circuit92rectifies an AC voltage outputted from the commercial AC power supply Q through the noise filter circuit91and outputs the rectified voltage to the smoothing circuit95. In other words, the rectifier circuit92converts the AC voltage from the commercial AC power supply Q to a DC voltage and outputs this DC voltage to the smoothing circuit95.

As illustrated inFIG.14, the positive line93and the negative line94connect the rectifier circuit92and the inverter circuit96to each other. The negative line94is also connected to ground (GND; not illustrated).

The smoothing circuit95is connected between the rectifier circuit92and the inverter circuit96. The smoothing circuit95smooths the DC voltage outputted from the rectifier circuit92and outputs the smoothed voltage to the inverter circuit96. The smoothing circuit95includes a first capacitor95A, a second capacitor95B, and a resistor95C.

The first capacitor95A is a polarized electrolytic capacitor and is connected between the positive line93and the negative line94. In the present embodiment, the first capacitor95A has a capacitance of approximately 180 μF, but small capacitors with a capacitance between 40 and 200 μF may be employed, as well. The second capacitor95B is a non-polarized film capacitor and is connected between the positive line93and the negative line94. In the present embodiment, the second capacitor95B has a capacitance of approximately 4.7 μF. The resistor95C is a discharge resistor. The resistor95C is connected between the positive line93and the negative line94in parallel with the second capacitor95B.

The inverter circuit96has the six switching elements Q1-Q6 connected in a three-phase bridge formation. In the present embodiment, the switching elements Q1-Q6 are MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), but may be other types of switching elements, such as IGBTs (Insulated Gate Bipolar Transistors).

Gates of the switching elements Q1-Q6 are connected to the controller10and perform switching operations based on control signals inputted from the controller10. Further, drain or source of each of the switching elements Q1-Q6 is connected to one of the stator coils U, V, and W. As illustrated inFIG.10, the switching elements Q1-Q6 are arranged in an approximate center in the left-right direction of the tail cover22so as to form two rows juxtaposed in the left-right direction of three switching elements aligned in the front-rear direction.

The constant voltage power supply circuit97illustrated inFIG.14is connected between the positive line93and the negative line94. The constant voltage power supply circuit97includes a diode97A, a capacitor97B, an IPD circuit97C, a capacitor97D, and a regulator97E. The constant voltage power supply circuit97converts the DC voltage outputted from the rectifier circuit92to generate a stabilized reference voltage and supplies this reference voltage to the controller10and the like.

The controller10has an arithmetic unit, a ROM, a RAM, and the like those are not illustrated in the drawings. The controller10is configured to control the inverter circuit96based on signals from the electronic switch11to drive the motor5. The controller10detects a rotated position of the rotor52based on signals outputted from each of the three magnetic sensors54and forms control signals for switching the switching elements Q1-Q6 on and off based on the detection results. The controller10outputs these control signals to the switching elements Q1-Q6 for sequentially switching winding among the stator coils U, V, and W that conducts electricity in order to drive the rotor52to rotate in a prescribed rotating direction.

Next, configurations of the tail cover22and the filter part3will be described in detail with reference toFIGS.3and4.

As illustrated inFIG.3, the tail cover22includes the intake port part22A that introduces cooling air for cooling the circuit elements, the controller10, and the like mounted on the circuit board61. The intake port part22A has intake port groups22c,22d,22e,22f,22g,22h, and22i, each of which is configured of a plurality of intake ports. The intake port groups22c,22d,22e,22f, and22gare all formed symmetrically on the left and right walls of the tail cover22at the rear portion of the tail cover22. In other words, the intake port part22A has intake port groups formed in a left side surface of the tail cover22, and intake port groups formed in a right side surface of the tail cover22. Thus, when referencing the intake port groups22c,22d,22e,22f, and22gin the following description, the references will be based on the intake port groups formed in the left side surface of the tail cover22.

The intake port group22cpenetrates the left side wall of the tail cover22in the left-right direction at an approximate center in the front-rear direction of the tail cover22. In the present embodiment, the intake port group22cis formed of six intake ports arranged successively in the up-down direction.

The intake port groups22d,22e, and22fare formed at positions rearward of the intake port group22cin the order of the intake port groups22d,22e, and22f. The intake port groups22d,22e, and22fpenetrate the left side wall of the tail cover22in the left-right direction. In the present embodiment, each of the intake port groups22d,22e, and22fis formed of six intake ports arranged successively in the up-down direction.

The intake port group22gis positioned rearward of the intake port group22fand penetrates the left side wall of the tail cover22in the left-right direction. In the present embodiment, the intake port group22ghas seven intake ports arranged successively in the up-down direction. The seven intake ports forming the intake port group22gare elongated in the front-rear direction.

The intake port groups22hand22iare provided at the rear end portion in the front-rear direction of the tail cover22and penetrate the rear wall of the tail cover22in the front-rear direction. The intake port group22his formed at a right portion of the rear wall constituting the tail cover22, and has three intake ports elongated in the up-down direction and arranged in the left-right direction. The intake port group22iis formed at an approximate center portion of the rear wall of the tail cover22and has four intake ports elongated in the up-down direction. The four intake ports are arranged in two rows juxtaposed in the up-down direction.

The filter part3illustrated inFIGS.3and4is configured to be detachably attached to a rear half portion of the tail cover22so as to cover the intake port part22A of the tail cover22in order to restrain dust from entering the tail cover22through the intake port part22A during operations. Although the filter part3is configured to cover substantially the entire intake port part22A in the present embodiment, the filter part3may be configured to cover only a portion of the intake port part22A. The filter part3includes a left filter31, a right filter32, and a rear filter33. In other words, the filter part3can be divided into the left filter31, the right filter32, and the rear filter33. The left filter31, the right filter32, and the rear filter33are made of resin. The left filter31is configured to cover the intake port groups in the intake port part22A formed in the left side surface of the tail cover22. On the other hand, the right filter32is configured to cover the intake port groups in the intake port part22A formed in the right side surface of the tail cover22. The left filter31and the right filter32are configured with left-right symmetry. Accordingly, corresponding components in the left filter31and the right filter32are designated with the same reference numerals in the drawings. Further, the components of the left filter31and the right filter32will be described based on the components in one of the left filter31and the right filter32, while descriptions of components in the other are omitted as appropriate.

As illustrated inFIG.3, each of the left filter31and the right filter32includes an upper wall part311, a side wall part312, and a lower wall part313. The upper wall part311, the side wall part312, and the lower wall part313are formed single piece structure. The upper wall part311extends in the front-rear direction and is formed so as to cover an upper surface on the left side of the tail cover22when the left filter31is attached to the tail cover22. An upper engaging part31A is provided at the upper wall part311.

The upper engaging part31A has a substantial plate shape that protrudes rearward from a right end portion of the upper wall part311. The upper engaging part31A is elastically deformable relative to the upper wall part311. The upper engaging part31A includes a hooking part31B. The hooking part31B is positioned at a rear end portion of the upper engaging part31A and protrudes upward like a pawl in order that the upper engaging part31A can be engaged with the rear filter33through elastic deformation.

The side wall part312of the right filter32is shaped so as to extend downward from a right end of the upper wall part311. The side wall part312is formed to cover the side surface of the tail cover22when the right filter32is attached to the tail cover22. Three openings312aare formed in the side wall part312to be arranged in the front-rear direction. Although not illustrated in the drawings, a fine metal mesh is provided in each of the openings312a. Pawls312A, protrusions312B, and a protrusion312C are provided on the side wall part312. Note that the side wall part312of the left filter31has an identical configuration to that described above.

The pawls312A form general L-shapes that protrude from an inner surface of the side wall part312. In the present embodiment, four pawls312A are provided to be arranged in the up-down direction. The four pawls312A are positioned to correspond to four intake ports of the intake port group22cprovided in the intake port part22A of the tail cover22. The four pawls312A are configured to be engaged with walls forming the corresponding intake ports of the intake port group22c. Each of the four pawls312A includes a first part312D, and a second part312E.

The first part312D extends inward from the inner surface of the side wall part312in a radial direction of the filter part3. The second part312E extends frontward from a distal end of the first part312D.

The protrusions312B protrude inward from the inner surface of the side wall part312in the radial direction of the filter part3. In the present embodiment, two protrusions312B are provided on an upper portion of the side wall part312. The two protrusions312B are arranged to correspond to the upper two intake ports within the intake port group22fprovided in the intake port part22A of the tail cover22. In a side view, each of the two protrusions312B has a smaller area than an area of the corresponding intake port. Each of the two protrusions312B is configured to enter the corresponding intake port when the filter part3is attached to the tail cover22.

The protrusion312C protrudes inward from the inner surface of the side wall part312in the radial direction of the filter part3. In the present embodiment, one protrusion312C is provided on a lower portion of the side wall part312. The protrusion312C is configured to correspond to one lower intake port in the intake port group22fof the intake port part22A. In a side view, the protrusion312C has a smaller area than an area of the corresponding intake port. The protrusion312C is configured to enter the corresponding intake port when the filter part3is attached to the tail cover22.

The lower wall part313is shaped to extend downward from a lower end of a rear end portion of the side wall part312. A lower engagement part313A is provided at the lower wall part313. The lower engagement part313A is formed to be recessed inward from an outer surface of the lower wall part313in the radial direction of the filter part3. The lower engagement part313A includes an engagement protrusion313B. The engagement protrusion313B protrudes outward within an interior space of the lower engagement part313A in the radial direction of the filter part3.

The rear filter33is configured such that the rear filter33is attachable to the housing2and engageable with the left filter31and the right filter32. The rear filter33has a substantial disc shape in a rear side view. The rear filter33includes a pair of lower engaging parts33A, an upper engagement part33C, protrusions33D, and protrusions33E. Note that, although the rear filter33is configured to function as a filter in the present embodiment, the rear filter33may instead be provided simply to connect the left filter31and the right filter32together in the left-right direction.

The lower engaging parts33A are provided on a lower portion of the rear filter33and configured with left-right symmetry. Each of the two lower engaging parts33A are configured to be engaged with the corresponding lower engagement parts313A of the left filter31and the right filter32. Each of the two lower engaging parts33A is formed in a substantial plate shape that protrudes frontward from a front surface of the rear filter33. The lower engaging parts33A are elastically deformable relative to a body part of the rear filter33. Each of the lower engaging parts33A includes a hooking part33B. The hooking part33B is positioned at a front end portion of the lower engaging part33A. The hooking parts33B protrude like pawls inward in the radial direction of the filter part3and substantially downward in order that the lower engaging parts33A can be engaged with the corresponding lower engagement parts313A of the left filter31and the right filter32through elastic deformation.

The upper engagement part33C is provided at an upper portion of the rear filter33. The upper engagement part33C is configured to be engaged with the upper engaging parts31A of the left filter31and the right filter32. Although not illustrated in the drawings, a recess recessed upward is provided at the upper engagement part33C in order to receive the hooking parts31B of the upper engaging parts31A.

The protrusions33D protrude frontward from the front surface of the rear filter33. In the present embodiment, three protrusions33D are provided on a right portion of the rear filter33. The three protrusions33D are arranged to correspond to the three intake ports of the intake port group22hprovided in the intake port part22A of the tail cover22. In a front side view, each of the protrusions33D has a smaller area than an area of the corresponding intake port. Each of the three protrusions33D is configured to enter the corresponding intake port when the filter part3is attached to the tail cover22.

The protrusions33E protrude frontward from the front surface of the rear filter33. In the present embodiment, two protrusions33E are provided on the lower portion of the rear filter33. Each of the two protrusions33E is configured to correspond to one of two intake ports in the intake port group22iof the intake port part22A. In a front side view, each of the two protrusions33E has an area smaller than an area of the corresponding intake port. Each of the two protrusions33E is configured to enter the corresponding intake port when the filter part3is attached to the tail cover22.

An opening33a, an opening33b, and a notch33care also formed in the rear filter33. The opening33aextends from the right portion to a center portion of the rear filter33and penetrates the rear filter33in the front-rear direction. Although not illustrated in the drawings, a fine metal mesh is provided in the opening33a. The opening33bis formed in a left portion of the rear filter33. The opening33bhas a rectangular shape and penetrates the rear filter33in the front-rear direction. In the present embodiment, the disc grinder1is not provided with a dial for adjusting a rotational speed of the motor5. However, if such a dial for adjusting the rotational speed of the motor is provided on a rear portion of a tail cover configuring an electric work tool, the adjustment dial can be exposed to an outside through the opening33b. The notch33cis formed at the lower portion of the rear filter33. The notch33cis cut out upwardly to form a circular shape. The power cord2A can be exposed to an outside through the notch33cwhen the rear filter33is attached to the tail cover22.

Next, operations for attaching the filter part3to and detaching the filter part3from the tail cover22will be described with reference toFIGS.4through7.

As illustrated inFIGS.4and5, the operator first engages the pawls312A on the left filter31and the right filter32with the intake port part22A of the tail cover22. Specifically, the operator causes the second parts312E of the pawls312A on each of the left filter31and the right filter32to enter the tail cover22through the corresponding intake port groups22c. Next, the left filter31and the right filter32are attached to the tail cover22by pivotally moving the left filter31and the right filter32relative to the tail cover22about the pawls312A so that rear portions of the left filter31and the right filter32approach the tail cover22, as illustrated inFIG.6. In this state, side surfaces of the second parts312E inserted into the housing2opposes an inner surface of the housing2. In addition, movement in the front-rear direction of the left filter31and the right filter32relative to the housing2is restricted by front surfaces of the first parts312D constituting the pawls312A opposing front walls forming the intake port groups22cand rear surfaces of the first parts312D opposing rear walls forming the intake port groups22c. In other words, by pivotally moving the left filter31and the right filter32about the pawls312A to a position illustrated inFIG.6, the operator can retain the pawls312A relative to the tail cover22such that the pawls312A cannot separate away from the tail cover22. Hereinafter, the position illustrated inFIG.6will be referred to as a fixed position.

At the same time, the protrusions312B and312C provided on the side wall part312of each of the left filter31and the right filter32enter the corresponding intake port groups22gof the intake port part22A. In this state, the left filter31and the right filter32are restricted from moving in the front-rear direction relative to the housing2by front surfaces of the protrusions312B and312C opposing front walls forming the intake port groups22gand rear surfaces of the protrusions312B and312C opposing rear walls forming the intake port groups22g. In other words, the left filter31and the right filter32can be engaged with the tail cover22without any elastic deformation (non-active engagement). In this specification, engagement between members that requires elastic deformation of at least one of the members when moving into or out of the engaged state is referred to as active engagement, while conversely engagement that does not require such elastic deformation of members is referred to as non-active engagement.

In this state, the intake port groups22c,22d,22e,22f, and22gof the intake port part22A that are formed in the side surfaces of the tail cover22are covered from the sides by the metal mesh provided in the openings312aformed in the left filter31and the right filter32. This metal mesh prevents dust from entering the housing2through the intake port groups22c,22d,22e,22f, and22gduring operations.

Next, as illustrated inFIGS.5and6, the operator moves the rear filter33frontward relative to the left filter31and the right filter32so as to engage the upper engaging parts31A on the left filter31and the right filter32with the upper engagement part33C of the rear filter33. In other words, the operator moves the rear filter33in a direction crossing the left-right direction relative to the left filter31and the right filter32. As the hooking parts31B on the upper engaging parts31A contact and are pressed against the upper engagement part33C, the upper engaging parts31A are elastically deformed downward relative to the left filter31and the right filter32. Subsequently, the hooking parts31B enter the upwardly recessed area formed in the upper engagement part33C, pressure applied to the upper engaging parts31A is released and the upper engaging parts31A is elastically deformed upward to return to their state prior to being pressed by the upper engagement part33C.

As illustrated inFIGS.6and7, the operator then pivotally moves the rear filter33in a clockwise direction in the drawings relative to the left filter31and the right filter32in order to engage the lower engagement parts313A on the left filter31and the right filter32with the lower engaging parts33A on the rear filter33. In other words, the operator pivotally moves the rear filter33in a direction crossing the left-right direction relative to the left filter31and the right filter32. As the hooking parts33B of the lower engaging parts33A contact the engagement protrusions313B provided on the lower engagement parts313A and are pressed outward in the radial direction of the filter part3, the lower engaging parts33A are elastically deformed radially outward relative to the left filter31and the right filter32. When the hooking parts33B subsequently become engaged with the engagement protrusions313B, as illustrated inFIG.7, pressure on the lower engaging parts33A is released and the lower engaging parts33A are elastically deformed radially inward and return to their state prior to being pressed by the engagement protrusions313B. That is, through the engagement between the upper engaging parts31A and the upper engagement part33C and the engagement between the lower engaging parts33A and the lower engagement parts313A, the left filter31and the right filter32can be engaged with the rear filter33through elastic deformation (active engagement). Since the engagement between the upper engaging parts31A and the upper engagement part33C and the engagement between the lower engaging parts33A and the lower engagement parts313A require elastic deformation to be disengaged, a force of engagement is suitably strong enough to restrain detachment of the rear filter33from the left filter31and the right filter32.

In this state, the intake port groups22hand22iof the intake port part22A formed in the rear surface of the tail cover22are covered from the rear side by the metal mesh provided in the opening33a. This metal mesh restrains dust from entering the housing2through the intake port groups22hand22iduring operations.

Note that, in the above description, the lower engaging parts33A are engaged with the lower engagement parts313A after the engagement of the upper engaging parts31A with the upper engagement part33C, but the order of engagement is not limited to this order. Specifically, the lower engaging parts33A may be engaged with the lower engagement parts313A prior to engagement of the upper engaging parts31A with the upper engagement part33C, or both engagements may be performed simultaneously.

At this time, movement of the rear filter33in the front-rear direction relative to the left filter31is restricted by the engagement between the upper engaging part31A of the left filter31and the upper engagement part33C and the engagement of the lower engaging part33A and the lower engagement part313A of the left filter31, and movement of the right filter32in the front-rear direction relative to the rear filter33is restricted by the engagement between the upper engaging part31A of the right filter32and the upper engagement part33C and the engagement between the lower engaging part33A and the lower engagement part313A of the right filter32. Hence, relative positions of the rear filter33, the left filter31, and the right filter32can be suitably set.

Further, since the hooking parts31B of the upper engaging parts31A protrude upward and the hooking parts33B of the lower engaging parts33A protrude substantially inward of the filter part3, movement of the rear filter33in the front-rear direction relative to the left filter31and the right filter32can be suitably restricted.

Additionally, the protrusions33D provided on the front surface of the rear filter33enter the intake port group22hof the intake port part22A and the protrusions33E enter the intake port group22i. Thus, the rear filter33becomes engaged with the tail cover22without elastic deformation (non-active engagement). In this state, right surfaces of the protrusions33D oppose right walls forming the intake ports in the intake port group22h, and left surfaces of the protrusions33D oppose left walls forming the intake ports in the intake port group22h. Similarly, right surfaces of the protrusions33E oppose right walls forming the intake ports in the intake port group22i, and left surfaces of the protrusions33E oppose left walls forming the intake ports in the intake port group22i. This configuration restricts the rear filter33from moving in the left-right direction relative to the tail cover22.

As described above, the pawls312A of the left filter31and the right filter32can be non-actively engaged with the tail cover22, i.e., without elastic deformation, while the upper engaging parts31A of the left filter31and the right filter32can be actively engaged with the rear filter33, i.e., with elastic deformation. In other words, since it is not necessary to fix the left filter31and the right filter32to the housing2by elastically deforming parts of the housing2, deterioration of the housing2can be suppressed. Further, by using simple holes in the housing2as engaging parts, such as intake ports described in the present embodiment, the filter part3can be attached to the housing2without requiring a special configuration on the housing2for active engagement. Hence, the filter of the present invention can be attached to or detached from a conventional work tool that only has intake ports or a work tool having a simple construction for suppressing manufacturing costs. Further, since the filter part3is ultimately fixed to the housing2through active engagement, a suitable fixing force for the filter part3can be secured.

Further, since engagement between the rear filter33and the housing2without elastic deformation restricts movement of the rear filter33in the left-right direction relative to the housing2, engagement of the left filter31and the right filter32with the rear filter33(active engagement) can suitably fix the left filter31and the right filter32to the housing2. Further, since the rear filter33and the housing2are engaged with each other without elastic deformation, this configuration can suppress deterioration of the housing2.

In order to detach the filter part3from the tail cover22, first the operator disengages the rear filter33from the left filter31and the right filter32. Specifically, as illustrated inFIGS.6and7, the operator pivotally moves the rear filter33in a counterclockwise direction in the drawings relative to the left filter31and the right filter32so as to disengage the lower engagement parts313A of the left filter31and the right filter32from the lower engaging parts33A of the rear filter33. In other words, the operator moves the rear filter33in a direction crossing the left-right direction relative to the left filter31and the right filter32. At this time, the hooking parts33B of the lower engaging parts33A contact to be pressed by the engagement protrusions313B provided on the lower engagement parts313A, thereby causing the lower engaging parts33A to be elastically deformed radially outward relative to the filter part3. When the lower engaging parts33A subsequently separate from the lower engagement parts313A, as illustrated inFIG.6, the lower engaging parts33A are elastically deformed to return to their state before the lower engaging parts33A are pressed by the engagement protrusions313B.

Next, as illustrated inFIGS.5and6, the operator moves the rear filter33rearward relative to the left filter31and the right filter32so that the upper engaging parts31A on the left filter31and the right filter32are disengaged from the upper engagement part33C of the rear filter33. In other words, the operator moves the rear filter33in a direction crossing the left-right direction relative to the left filter31and the right filter32. At this time, the hooking parts31B of the upper engaging parts31A contact and are pressed by the upper engagement part33C to cause the upper engaging parts31A to be elastically deformed downward relative to the left filter31and the right filter32. When the upper engaging parts31A subsequently separate from the upper engagement part33C, as illustrated inFIG.5, the upper engaging parts31A are elastically deformed to return to their state prior to being pressed by the upper engagement part33C.

Then, the operator pivotally moves the left filter31and the right filter32relative to the tail cover22about their respective pawls312A so that the rear portions of the left filter31and the right filter32separate from the tail cover22, and subsequently detaches the left filter31and the right filter32from the tail cover22. That is, by pivotally moving the left filter31and the right filter32about the pawls312A to a position illustrated inFIG.5, the operator can separate the pawls312A from the tail cover22. Hereinafter, the position illustrated inFIG.5will be referred to as an attachment-detachment position.

Thus, the disc grinder1according to the present embodiment is configured so that the left filter31and the right filter32can be easily detached from the tail cover22simply by moving the rear filter33in a direction crossing the left-right direction, thereby improving usability.

Further, the rear filter33can be engaged with the left filter31and the right filter32and the tail cover22when the left filter31and the right filter32are at the fixed position, and restricts the left filter31and the right filter32from moving from the fixed position to the attachment-detachment position while the rear filter33is engaged with the left filter31and the right filter32and the tail cover22. Therefore, there is no need to provide the housing2with a new configuration for engaging the left filter31and the right filter32with the tail cover22.

Further, the left filter31and the right filter32cannot be detached from the tail cover22, even when the rear filter33is detached from the tail cover22, unless the left filter31and the right filter32are moved from the fixed position to the attachment-detachment position. Accordingly, this configuration can suppress inadvertent detachment of the left filter31and the right filter32from the tail cover22.

Further, the left filter31and the right filter32are moved between the attachment-detachment position and the fixed position in accordance with pivotal movement of the left filter31and the right filter32relative to the tail cover22about points of engagement between the pawls312A and the intake port part22A. Accordingly, the left filter31and the right filter32is movable between the attachment-detachment position and the fixed position through a simple configuration.

Since the pawls312A are engaged with the intake port part22A without elastic deformation when the left filter31and the right filter32are moved from the attachment-detachment position to the fixed position, deterioration of the housing2can be restrained.

While the left filter31and the right filter32are configured as two filter halves having left-right symmetry, movement of the left filter31and the right filter32toward the attachment-detachment position can be suitably restricted by engaging both filter halves, i.e., the left filter31and the right filter32, with the rear filter33.

Next, detailed configurations of the motor housing21, the lever part4, and the electronic switch11, and arrangement of the lever part4in the housing2will be described with reference toFIGS.1,2, and8through12.

As illustrated inFIGS.1,2, and8, the lever part4is provided downward of the tail cover22, and includes a paddle lever41, and an intervening part42. The paddle lever41is arranged on the gripping part20that spans over the motor housing21and the tail cover22, and extends in the front-rear direction. A pressing part41A, a spring411, an off-lock mechanism412, and a pivot shaft413are provided at the paddle lever41. The paddle lever41is an example of the “operating part” of the present invention.

As illustrated inFIG.8, the pressing part41A has a substantial columnar shape protruding into the housing2from a rear portion of the paddle lever41. The pressing part41A includes a lever engaging part41B. The lever engaging part41B protrudes from a distal end of the pressing part41A in a direction orthogonal to a direction in which the pressing part41A extends.

As illustrated inFIG.1, the pivot shaft413is provided at the rear portion of the paddle lever41, and has a substantial columnar shape extending in the left-right direction. The pivot shaft413is inserted into the through-holes22bformed in the support part22B of the tail cover22. With this configuration, the paddle lever41is configured to be pivotally movable in a clockwise direction inFIG.11about the pivot shaft413relative to the tail cover22when the operator presses the paddle lever41into the housing2. In other words, the paddle lever41is movable in the up-down direction in order to drive and stop the motor5. The pivot shaft413is an example of the “support shaft” of the present invention.

As illustrated inFIG.2, the spring411is disposed between the paddle lever41and the outer circumferential surface of the tail cover22. The spring411urges the paddle lever41to separate away from the tail cover22. More specifically, the spring411urges the paddle lever41to be pivotally moved in a counterclockwise direction inFIG.2about the pivot shaft413.

As illustrated inFIG.2, the off-lock mechanism412includes an off-lock member412A, and a spring412B. The off-lock member412A has a substantial plate shape extending in a direction orthogonal to an extending direction in which the paddle lever41extends when no external force is acting on the disc grinder1. The off-lock member412A has one end portion protruding downward from a lower surface of the paddle lever41. The spring412B is provided on the paddle lever41to pivotally move the off-lock member412A in the counterclockwise direction inFIG.2. Therefore, unless the operator pivotally moves the off-lock member412A in a clockwise direction against the urging force of the spring412B, another end portion of the off-lock member412A contacts an outer circumference of the tail cover22when the paddle lever41is pressed into the housing2, thereby preventing the paddle lever41from being further pressed into the housing2. This configuration suppresses the disc grinder1from being driven unexpectedly. Further, since the protruding part221is provided on the rear portion of the tail cover22in the present embodiment, the disc grinder1can be even more suitably suppressed from being driven unintentionally. If the disc grinder1is dropped on the ground, for example, the protruding part221contacts the ground before the paddle lever41does.

As illustrated inFIG.9, the intervening part42includes an attachment part421, a lever422, and a pin423. The attachment part421includes a base part421A, a first protrusion421B, a second protrusion421C, and a lever retaining part421E. The attachment part421is attached to the motor housing21, as will be described later. The intervening part42is an example of the “intervening part” of the present invention. The attachment part421is an example of the “support part” of the present invention.

The base part421A has a substantial plate shape extending in the up-down direction. Although not illustrated in the drawings, a through-hole is formed in a lower portion of the base part421A to penetrate the base part421A in the left-right direction. The first protrusion421B has a substantial block-like shape that protrudes leftward from an upper portion of the base part421A. The second protrusion421C is provided on a front portion of the base part421A. The second protrusion421C has a block-like shape that extends in the front-rear and left-right directions. The second protrusion421C has a right surface having a curved surface421D that is curved at a predetermined curvature.

The lever retaining part421E is positioned at a lower portion of the attachment part421, and has a substantial plate shape extending in the up-down and front-rear directions. A through-hole is formed in an approximate center portion in the front-rear direction of the lever retaining part421E to penetrate the lever retaining part421E in the left-right direction. The through-hole is positioned at the same position in the front-rear and up-down directions as the through-hole (not illustrated) formed in the lower portion of the base part421A.

The lever422includes a lever base part422A, a pressure-receiving part422B, a notched part422C, an engagement part422D, and a reinforcing part422E. The lever base part422A has a substantial plate shape extending in the front-rear direction. Although not illustrated in the drawings, a through-hole is formed in a front portion of the lever base part422A to penetrate the lever base part422A in the left-right direction. This through-hole is positioned at the same position in the up-down and front-rear directions as the through-hole (not illustrated) formed in the lower portion of the base part421A of the attachment part421and the through-hole formed in the lever retaining part421E. By fitting the pin423into the through-holes formed in the lever base part422A, the base part421A, and the lever retaining part421E in the present embodiment, the lever422is pivotally movable about the pin423relative to the attachment part421. The lever422is an example of the “lever” of the present invention, and the pin423is an example of the “pivot shaft” of the present invention.

The pressure-receiving part422B is positioned rearward of the lever base part422A and extends in the front-rear direction. The pressure-receiving part422B is formed to have a width in the left-right direction greater than that of the lever base part422A. The pressure-receiving part422B is configured so that the pressure-receiving part422B can contact the pressing part41A of the paddle lever41. The lever422is movable between a release position illustrated inFIG.11, and a pressed position illustrated inFIG.12in which the lever422is pressed by the paddle lever41. The notched part422C constitutes a rear end portion of the lever422, and is recessed leftward to form a notched shape. The pressed position is an example of the “motor drive position” of the present invention, and the release position is an example of the “motor stop position” of the present invention.

The engagement part422D is provided in an approximate center portion in the front-rear direction of the lever422and protrudes downward in an L-shape. The engagement part422D is configured such that the engagement part422D is engageable with the lever engaging part41B of the paddle lever41.

The reinforcing part422E is provided to connect a lower surface of the lever base part422A and a front surface of the engagement part422D to each other. By providing the reinforcing part422E, the engagement part422D can be strengthened against forces applied for tilting the engagement part422D frontward.

As illustrated inFIG.11, the electronic switch11is accommodated in the tail cover22and includes a switch plunger11A, and a leaf spring11B. The electronic switch11and the controller10are connected to each other through wiring for transmitting and receiving signals. The electronic switch11is a microswitch which is a small switch configured to detect slight movements using the switch plunger11A and to transmit signals.

As illustrated inFIG.11, the switch plunger11A is provided at a position B with respect to a direction of an axis A of the gripping part20, which spans over the motor housing21and the tail cover22. The switch plunger11A is configured to detect a position of the intervening part42relative to the housing2. The axis A is an axis passing through an approximate center of the gripping part20and extending in the front-rear direction. The switch plunger11A is configured to be capable of expanding and contracting when pressed upward relative to a body of the electronic switch11. Specifically, by moving in the up-down direction, the switch plunger11A is switchable between an OFF position (seeFIG.11) for driving the motor5, and an ON position (seeFIG.12) for stopping the motor5. In the present embodiment, a distance over which the switch plunger11A is moved between the ON position and the OFF position is much shorter than a distance over which the paddle lever41is moved in the up-down direction when the operator presses the paddle lever41into the housing2. That is, an amount by which the switch plunger11A is allowed to be manipulated upward relative to the switch plunger11A to turn on the switch plunger11A is small compared to an amount by which the operator operates the paddle lever41. In other words, an allowable amount of movement of the switch plunger11A is smaller than a required amount of movement of the paddle lever41. The switch plunger11A is an example of the “switch” and the “detection part” of the present invention. The position B is an example of the “first position” and the “prescribed position” of the present invention. The up-down direction is an example of the “direction connecting the ON position and the OFF position to each other” of the present invention.

In the present embodiment, the electronic switch11transmits an ON signal to the controller10for driving the motor5when the switch plunger11A detects that the intervening part42is at the pressed position and transmits an OFF signal to the controller10for stopping the motor5when the switch plunger11A detects that the intervening part42is at the release position. The switch plunger11A serves as an example of the detection part and may be configured of a magnetic sensor, a distance sensor, or the like that detects the position of the intervening part42and transmits signals to the controller10. The controller10may be configured to determine that the intervening part42is at the release position when an ON signal is no longer outputted from the electronic switch11, and vice versa. Thus, the controller10is configured to control the motor5based on signals from the electronic switch11.

The leaf spring11B is provided between a lower surface of the body of the electronic switch11and the lever base part422A. The leaf spring11B urges the lever422such that the switch plunger11A and the lever422are positioned away from each other. Specifically, the leaf spring11B urges the lever422to be pivotally moved in the clockwise direction inFIG.11about the pin423.

As illustrated inFIG.10, the intervening part42and the electronic switch11are arranged at positions in the housing2near a left side surface thereof. This arrangement prevents the intervening part42and the electronic switch11from blocking cooling air introduced through the intake port part22A of the tail cover22, thereby improving cooling efficiency for the motor5and the circuit elements and the like mounted on the circuit board part6. Further, by providing the notched part422C in the lever422, contact of the intervening part42with the switching element Q2 can be prevented when the lever422is pivotally moved in the up-down direction, even when the provided switching elements are relatively large.

The intervening part42and the inverter circuit96are arranged at the same position in the front-rear direction. With this arrangement, the intervening part42is not positioned upstream of the inverter circuit96along a path of cooling air when the path extends in the front-rear direction, as in the present embodiment. Therefore, the intervening part42does not block cooling air on the upstream side of the inverter circuit96, thereby improving cooling efficiency for the inverter circuit96.

As illustrated inFIG.8, an intervening unit holding part212for holding the attachment part421of the intervening part42is provided inside the motor housing21. The intervening unit holding part212includes a pair of upper and lower rail parts212A and212B, a pair of upper and lower wall parts212C and212D, and a cylindrical part212E.

The pair of upper and lower rail parts212A and212B protrude inward in the radial direction of the motor housing21and extend in the front-rear direction. A distance between a lower surface of the rail part212A and an upper surface of the rail part212B is configured to grow smaller toward the front. The rail parts212A and212B are shaped so that the first protrusion421B of the attachment part421in the intervening part42is slidingly movable therebetween.

Each of the pair of upper and lower wall parts212C and212D has a general plate shape that extends rightward from the corresponding one of the rail parts212A and212B. A distance between a lower surface of the wall part212C and an upper surface of the wall part212D is set equivalent to a width in the up-down direction of the second protrusion421C in the attachment part421.

The cylindrical part212E is disposed radially inward in the motor housing21. The cylindrical part212E has a general hollow cylindrical shape elongated in the front-rear direction. As illustrated inFIG.2, the cylindrical part212E is a part into which the ball bearing21A is fitted. The cylindrical part212E has a left side surface having a curvature the same as that of the curved surface421D of the second protrusion421C.

As illustrated inFIG.8, the configuration of the present embodiment enables the intervening part42to be attached to the motor housing21by fitting the second protrusion421C between the lower surface of the wall part212C, the upper surface of the wall part212D, and the left side surface of the cylindrical part212E while slidingly moving the first protrusion421B relative to the pair of rail parts212A and212B.

Thus, in the present embodiment, there is no need to provide a configuration for supporting the intervening part42in the tail cover22since the intervening part42is supported by the motor housing21that accommodates the motor5therein. Therefore, when the electronic switch11is provided on the tail cover22, as in the present embodiment, a space sufficient for accommodating the electronic switch11can easily be allocated in the tail cover22.

Further, since the intervening part42is configured to be supported by the motor housing21by attaching the attachment part421to the motor housing21, there is no need to provide a threaded boss for fastening the intervening part42to the cylindrical motor housing21, thereby avoiding an increase in an external size of the motor housing21.

Further, the intervening part42can be supported by the motor housing21through a simple configuration in which the attachment part421is retained in the intervening unit holding part212.

Next, positional relationship among the paddle lever41, the intervening part42, and the electronic switch11will be described with reference toFIG.11.

As illustrated inFIGS.11and12, the switch plunger11A is positioned at a position (the position B) in the direction of the axis A between the pin423and a point of contact between the pressing part41A of the paddle lever41and the pressure-receiving part422B of the lever422of the intervening part42. Also, this point of contact is positioned between the position B and the pivot shaft413of the paddle lever41. In other words, the pressing part41A is positioned closer to the pivot shaft413than the switch plunger11A is to the pivot shaft413. As a result, the point of contact is positioned at a position separated from the switch plunger11A in the direction of the axis A, and the switch plunger11A is positioned between this point of contact and the pin423. With this positional relationship, the switch plunger11A can be pressed upward by a base end of the lever base part422A of the lever422, which is closer to the pin423and requires a smaller amount of movement (an amount of pivotal movement). The point of contact is an example of the “second position” of the present invention.

That is, the intervening part42can transmit movement to the switch plunger11A with a smaller amount than the movement of the paddle lever41in the up-down direction passing through the position B. Hence, even when the paddle lever41is configured to be pivotally moved significantly relative to the housing2to give the operator the sense of pressing the paddle lever41inward, the switch plunger11A need not be disposed on the farthest downstream end in a pivot path of the paddle lever41, thereby securing freedom in arrangement for the electronic switch11in the housing2.

Next, machining work performed on a workpiece using the disc grinder1according to the embodiment of the present invention, and operations of the disc grinder1during machining work will be described with reference toFIGS.11through13.

In a state where the power cord2A is connected to the commercial AC power supply Q, the operator first presses the paddle lever41into the housing2. Specifically, the operator pivotally moves the off-lock mechanism412in the clockwise direction against the urging force of the spring412B and presses the paddle lever41into the housing2. Consequently, the paddle lever41is pivotally moved in the clockwise direction inFIG.11about the pivot shaft413relative to the tail cover22.

In this state, as illustrated inFIG.12, the pressing part41A and the lever engaging part41B of the paddle lever41contact the pressure-receiving part422B of the lever422of the intervening part42and press the pressure-receiving part422B upward. As a consequence, the lever422is pivotally moved in the counterclockwise direction inFIG.11about the pin423. In this state, the base end on the lever base part422A of the lever422, which is closer to the pin423and requires a smaller amount of movement (an amount of pivotal movement), presses the switch plunger11A of the electronic switch11upward. That is, the lever422presses the switch plunger11A so that the switch plunger11A is at the ON position.

At this time, electric power is supplied to the motor5via the power supply circuit9, and the rotation shaft51begins rotating. As the rotation shaft51is rotated, the pinion gear71fixed to the rotation shaft51is also rotated coaxially. Since the gear teeth on the pinion gear71are meshingly engaged with the gear teeth on the bevel gear72in this state, the bevel gear72begins rotating in the clockwise direction in a plan view. While rotating, the bevel gear72reduces the rotational speed of the pinion gear71.

The output shaft81fixed to the bevel gear72also begins rotating together with the bevel gear72. Accordingly, grinding or other machining can be performed on a workpiece using the grinding wheel P attached to the output shaft81.

When work is completed, the operator releases pressure on the paddle lever41into the housing2, and the paddle lever41is pivotally moved in the counterclockwise direction in the drawings about the pivot shaft413by the urging force of the spring411. At the same time, the lever422of the intervening part42is pivotally moved in the clockwise direction in the drawings about the pin423by the urging force of the leaf spring11B in the electronic switch11. As the lever422separates from the switch plunger11A, pressure on the switch plunger11A is released to allow the switch plunger11A to be moved downward.

Note that, due to deterioration of the leaf spring11B, there is a possibility that the lever422is not returned to its original position and remains in a state illustrated inFIG.13. However, in the present embodiment, the lever422can be returned to the position illustrated inFIG.11through the engagement between the lever engaging part41B of the paddle lever41and the engagement part422D of the lever422. In other words, the urging force of the spring411disposed between the paddle lever41and the tail cover22can return the lever422to the position illustrated inFIG.11. Thus, by transmitting the movement in the up-down direction of the paddle lever41to the lever422, the lever422is movable from the pressed position illustrated inFIG.12to the release position illustrated inFIG.11, thereby reliably stopping the motor5.

In the embodiment described above, operation in a direction for driving the motor5and operation in a direction for stopping the motor5in the up-down direction of the paddle lever41are transmitted to the intervening part42. This configuration can properly drive and stop the motor in response to operations by the operator on the paddle lever41when the electronic switch11is configured to be turned on and off through the intervening part42, as in the present embodiment.

Further, the intervening part42is movable from the pressed position to the release position through a simple configuration in which the spring411is provided between the paddle lever41and the tail cover22. The spring411is an example of the “urging member” and the “second urging member” of the present invention, and the leaf spring11B is an example of the “first urging member” of the present invention.

Next, a disc grinder100as an example of a work tool according to a second embodiment of the present invention will be described while referring toFIG.15. The disc grinder100basically has a configuration identical to the disc grinder1according to the first embodiment and, thus, the configuration that differs therefrom will be mainly described. Configurations identical to those in the disc grinder1exhibit the same technical advantages described above.

The disc grinder100according to the second embodiment includes a housing120in place of the housing2, and a filter part130in place of the filter part3. The filter part130includes a left filter31and a right filter32configured similarly to the left filter31and the right filter32according to the first embodiment, and a rear filter133that differs from the rear filter33according to the first embodiment.

The housing120includes a tail cover122. The tail cover122has a hollow cylindrical shape whose width in the left-right direction is greater. In other words, the tail cover122has a substantial elliptical shape in a rear side view. Although not illustrated in the drawings, a plurality of intake ports are formed in a left side surface, a right side surface, and a rear surface of the tail cover122.

The rear filter133includes an upper engagement part133C. The upper engagement part133C is configured to be engageable with the upper engaging parts31A of the left filter31and the right filter32. Also, an opening133ais formed in the rear filter133. A fine metal mesh is provided in the opening133a. The metal mesh is configured to restrain dust from entering through the intake ports formed in the rear surface of the tail cover122when the rear filter133is attached to the tail cover122.

As described above, both the filter part3described in the first embodiment and the filter part130described in the second embodiment are configured of filters divided into three parts. Therefore, shapes of the left filter31and the right filter32need not be modified when the shape of the tail cover is changed, as in the second embodiment. The left filter31and the right filter32can be detachably attached to housings of various shapes simply by modifying a shape of the rear filter connecting the left filter31and the right filter32to each other. Accordingly, costs can be reduced by using common parts (the left filter31and the right filter32).

While the disc grinder1is described as an example of a work tool in the present embodiments, the present invention can also be applied to work tools that are driven by motors other than the disc grinders.

REFERENCE SIGNS LIST