Patent ID: 12251810

DETAILED DESCRIPTION OF THE EMBODIMENTS

In one non-limiting embodiment according to the present disclosure, the grip part may include a second operation member. The second operation member may be configured to be normally held in an OFF position and to be moved to an ON position to drive the motor when manually depressed by the user. The first operation member may be arranged in a position facing the second operation member.

According to this embodiment, the user can operate the first operation member and the second operation member with the same hand. Thus, the maneuverability of the power tool can be improved.

In addition or in the alternative to the preceding embodiments, the first operation member may be configured to be slidable within a predetermined range in a direction crossing the driving axis. The first operation member may be configured to change the action mode of the driving mechanism to the first mode when moved to a first position within the predetermined range, and to change the action mode to the second mode when moved to a second position different from the first position within the predetermined range.

According to this embodiment, the action mode of the driving mechanism can be changed to the first mode or to the second mode in response to the operation of the first operation member.

In addition or in the alternative to the preceding embodiments, the power tool may further have a tool holder and a clutch member. The tool holder may be configured to removably hold the tool accessory and to be rotationally driven around the driving axis by torque transmitted from the motor. The clutch member may be on the tool holder. The clutch member may be configured to be movable along the driving axis in response to the operation of the first operation member. The clutch member may be configured to transmit the torque when the he clutch member is in a third position in a direction along the driving axis and to interrupt the torque transmission when the clutch member is in a fourth position different from the third position in the direction along the driving axis. The driving mechanism may be configured to operate in the first mode when the clutch member is in the third position, and to operate in the second mode when the clutch member is in the fourth position.

According to this embodiment, the action mode of the driving mechanism can be changed to the first mode or to the second mode in response to movement of the clutch member the third position or the fourth position in the direction along the driving axis.

In addition or in the alternative to the preceding embodiments, the power tool may further have a transmitting mechanism. The transmitting mechanism may be configured to transmit sliding movement of the first operation member within the predetermined range to the clutch member and move the clutch member along the driving axis.

According to this embodiment, the sliding movement of the first operation member can be transmitted to the clutch member that is provided on the tool holder configured to be rotationally driven around the driving axis.

In addition or in the alternative to the preceding embodiments, the transmitting mechanism may include a converting mechanism. The converting mechanism may be configured to convert linear sliding movement of the first operation member within the predetermined range into rotating motion and further convert the rotating motion into linear motion along the driving axis.

According to this embodiment, the transmitting mechanism can move the clutch member along the driving axis by converting the linear sliding movement of the first operation member into rotating motion and converting the rotating motion into linear motion along (parallel to) the driving axis. Further, the degree of freedom in arrangement of the transmitting mechanism is enhanced as compared with a structure not having the converting mechanism.

In addition or in the alternative to the preceding embodiments, the converting mechanism may include a first rack gear, a first pinion gear, a second pinion gear and a second rack gear. The first rack gear may be configured to slide in response to the linear sliding movement of the first operation member within the predetermined range. The first pinion gear may be configured to be engaged with the first rack gear. The second pinion gear may be configured to rotate in response to rotation of the first pinion gear. The second rack gear may be configured to be engaged with the second pinion gear and convert the rotating motion of the first pinion gear and the second pinion gear into the linear motion along the driving axis.

According to this embodiment, the linear sliding movement of the first operation member can be converted into linear motion and then transmitted to the clutch member by using the first rack gear and the first pinion gear, and the second pinion gear and the second rack gear.

In addition or in the alternative to the preceding embodiments, the power tool may have a biasing member that is configured to bias the first operation member. The first operation member may be configured to be held in the first position or the second position by biasing force of the biasing member.

According to this embodiment, the power tool can be provided that facilitates sliding the first operation member within the predetermined range and positioning it in the first position or the second position.

In addition or in the alternative to the preceding embodiments, the grip part may include a second operation member that is configured to be normally held in an OFF position and to be moved to an ON position to drive the motor when manually depressed by the user. The power tool may further have a locking member and a lock controlling member. The locking member may be configured to be moved to a lock position to lock the second operation member in the ON position or to a non-lock position not to lock the second operation member in the ON position, in response to the user's manual operation of the locking member. The lock controlling member may be configured to be movable along the driving axis. The lock controlling member may be configured to, when the first mode is selected in response to the user's operation of the first operation member, the lock control member is in a position to interfere with the locking member, thereby holding the locking member in the non-lock position. Further, the lock controlling member may be configured to, when the second mode is selected in response to the user's operation of the first operation member, the lock control member is in a position not to interfere with the locking member, thereby allowing the locking member to move to the lock position.

According to this embodiment, the user need not continue manually depressing the second operation member during operation of continuously performing hammering only motion for a relatively long time. Thus, the burden on the user during the operation can be reduced. Further, the lock controlling member is configured to hold the locking member in the non-lock position, in the first mode in which the tool accessory performs (produces, provides) rotating motion. Thus, the user can stop driving of the motor simply by releasing the second operation member, for example, even if the tool accessory is jammed on the workpiece. Therefore, the power tool is provided with high safety.

In addition or in the alternative to the preceding embodiments, the power tool may further have a mode detecting part, a rotation detecting part and a controlling part. The mode detecting part may be configured to at least detect that the action mode of the driving mechanism is the first mode. The rotation detecting part may be configured to detect the state of rotation of the tool body around the driving axis. The controlling part may be configured to control driving of the motor. The controlling part may be configured to stop driving of the motor when detecting that the action mode is the first mode and detecting excessive rotation of the tool body around the driving axis, based on detection results of the mode detecting part and the rotation detecting part.

According to this embodiment, in the first mode in which the tool accessory performs rotating motion, the controlling part stops driving of the motor based on the detection results of the rotation detecting part, for example, even if the tool accessory is jammed (locked) on the workpiece and the tool body excessively rotates around the driving axis (this phenomenon is also referred to as kickback). Therefore, the safety of the power tool can be further enhanced.

In addition or in the alternative to the preceding embodiments, the power tool may further have an elastic member. The elastic member may connect the handle to the tool body so as to be movable along the driving axis relative to the tool body. The rotation detecting part may be housed within the handle.

According to this embodiment, transmission of vibration from the tool body to the rotation detecting part is reduced. Thus, the life of the rotation detecting part can be prolonged.

A power tool having a rotary hammer mechanism according to one embodiment of the present disclosure is now described with reference toFIGS.1to15. In this embodiment, a rotary hammer100is described as a representative example of the power tool. The rotary hammer100is configured to rotationally drive a tool accessory101coupled to a tool holder30around a prescribed driving axis A1(such motion is hereinafter referred to as rotating motion) and to linearly drive the tool accessory101in parallel to the driving axis A1(such motion is hereinafter referred to as hammering motion).

First, the structure of the rotary hammer (also called a hammer drill)100as a whole is described in brief with reference toFIG.1. The rotary hammer100includes a tool body10and a handle17connected to the tool body10.

The tool body10includes a gear housing12extending along the driving axis A1(the driving axis A1direction), and a motor housing13connected to one end portion in a longitudinal direction of the gear housing12and extending in a direction crossing the driving axis A1. In this embodiment, the motor housing13extends in a direction substantially orthogonal to the driving axis A1. Thus, the tool body10is generally L-shaped as a whole.

A tool holder30is provided within the other end portion of the gear housing12in the longitudinal direction and configured to removably hold the tool accessory101. A driving mechanism3is housed within the gear housing12. The driving mechanism3is configured to operate in an action mode that is selected from a plurality of action modes including a mode of performing rotating motion and hammering motion (such mode is hereinafter referred to as rotary hammer mode (hammering with rotation mode)) and a mode of performing hammering only motion (such mode is hereinafter referred to as hammer mode), which will be described in detail below. A motor2is housed within the motor housing13. The motor2is arranged such that a rotational axis A2of a motor shaft25crosses (more specifically, extend orthogonally to) the driving axis A1. The gear housing12and the motor housing13are connected together so as to be immovable relative to each other.

The handle17includes a grip part170extending in a direction crossing (more specifically, orthogonal to) the driving axis A1(driving axis A1direction), and connection parts173,174protruding from both end portions in a longitudinal direction of the grip part170in a direction crossing (more specifically, orthogonal to) the grip part170. The handle17is generally C-shaped as a whole. The handle17is connected to an end portion of the tool body10on the side opposite from the tool holder30in the longitudinal direction of the tool body10. More specifically, the connection part173is connected to the gear housing12, and the connection part174is connected to the motor housing13.

The structure of the rotary hammer100is now described in detail. In the following description, for convenience sake, the extending direction of the driving axis A1of the rotary hammer100(the longitudinal direction of the gear housing12) is defined as a front-rear direction of the rotary hammer100. In the front-rear direction, the side of one end portion of the rotary hammer100in which the tool holder30is provided is defined as the front of the rotary hammer100, and the opposite side is defined as the rear of the rotary hammer100. The extending direction of the grip part170is defined as an up-down direction of the rotary hammer100. In the up-down direction, the side of the rotary hammer100where the connection part173is connected to the gear housing12is defined as an upper side, and the opposite side is defined as a lower side. A direction orthogonal to the front-rear direction and the up-down direction is defined as a left-right direction.

First, the handle17is described. As described above, the handle17includes the grip part170extending in the up-down direction, the connection part173protruding forward from an upper end of the grip part170, and the connection part174protruding forward from a lower end of the grip part170. As shown inFIG.1, elastic members175and176are respectively arranged between the connection part173and a rear upper end portion of the gear housing12and between the connection part174and a rear lower end portion of the motor housing13. In this embodiment, compression coil springs are adopted as the elastic members175,176. The handle17is connected to be movable in the front-rear direction relative to the tool body10via the elastic members175,176. This structure reduces transmission of vibration (particularly, vibration caused in the front-rear direction by the hammering motion) from the tool body10to the handle17.

A switch lever171is provided in the grip part170. The switch lever171is arranged extending upward from a substantially intermediate portion of the grip part170in the up-down direction on the front side of the grip part170. The switch lever171is configured to be manually depressed by a user. InFIG.2, OFF and ON positions of the switch lever171are shown by a solid line and a two-dot chain line, respectively. The switch lever171is normally held in the OFF position by being biased forward by a plunger of a main switch172disposed behind the switch lever171, and when manually depressed by the user, the switch lever171is retracted rearward to the ON position within the grip part170. When the switch lever171is moved to the ON position, the main switch172housed within the handle17is turned on, and the motor2is driven by control of a controller9described below.

A locking mechanism8is provided in the vicinity of the connection part173of the handle17. The locking mechanism8is configured to lock the switch lever171in the ON position when the action mode is the hammer mode and not to lock the switch lever171in the ON position when the action mode is the rotary hammer mode. The locking mechanism8will be described below in further detail.

An acceleration sensor95is housed within the handle17. In this embodiment, the acceleration sensor95is housed within a lower end portion of the grip part170and arranged relatively apart from the driving axis A1. The acceleration sensor95is configured to output signals indicating detected acceleration to the controller9described below. In this embodiment, the acceleration detected by the acceleration sensor95is used as an index that indicates the state of rotation of the tool body10around the driving axis A1.

The structures of elements disposed within the motor housing13are now described. The motor housing13mainly houses the motor2and the controller9.

As shown inFIG.1, the motor2has a motor body20including a stator21and a rotor23, and a motor shaft25extending from the rotor23. The rotational axis A2of the motor2(the motor shaft25) extends in the up-down direction. In this embodiment, an AC motor is adopted as the motor2and is driven by power supply from an external power source via a power cord19. The motor shaft25is rotatably supported at its upper and lower end portions by bearings. The upper end portion of the motor shaft25protrudes into the gear housing12and has a driving gear29.

The controller9is mounted to a rear wall132of the motor body20. In this embodiment, the controller9is formed by a microcomputer including a CPU and memories and configured such that the CPU controls operation of the rotary hammer100.

The controller9is electrically connected to the main switch172, the acceleration sensor95and a mode detecting part90described below via electric wires (not shown). In this embodiment, when the main switch172is turned on, the controller9drives the motor2according to the rotation speed set via an adjusting dial (not shown). Further, the controller9is configured to stop driving of the motor2when detecting excessive rotation of the tool body10around the driving axis A1based on the detection results of the acceleration sensor95and the mode detecting part90, which will be described in detail below.

The structures of elements disposed within the gear housing12are now described. The gear housing12mainly houses the tool holder30, the driving mechanism3and a transmitting mechanism4.

The gear housing12has a generally cylindrical front portion extending parallel to the driving axis A1. The tool holder30is housed in this cylindrical portion (also referred to as a barrel part). Although not shown, an auxiliary handle for assisting in holding the rotary hammer100can be attached to the barrel part.

The driving mechanism3includes a motion converting mechanism31, a striking mechanism33and a rotation transmitting mechanism35. Most of the motion converting mechanism31and the rotation transmitting mechanism35are housed in a rear portion of the gear housing12.

The motion converting mechanism31is configured to convert rotation of the motor2into linear motion and transmit it to the striking mechanism33. In this embodiment, a known crank mechanism is adopted as the motion converting mechanism31. As shown inFIG.2, the motion converting mechanism31includes a crank shaft311, a connecting rod313and a piston315. The crank shaft311is arranged in parallel to the motor shaft25in a rear end portion of the gear housing12. The crank shaft311has a driven gear312engaged with a driving gear29. One end portion of the connecting rod313is connected to an eccentric pin, and the other end portion of the connecting rod313is connected to the piston315via a connection pin. The piston315is slidably disposed within a tubular cylinder317. When the motor2is driven, the piston315is reciprocated along (parallel to) the driving axis A1(in the front-rear direction) within the cylinder317.

The striking mechanism33includes a striker331and an impact bolt333(seeFIG.1). The striker331is disposed in front of the piston315so as to be slidable in the front-rear direction within the cylinder317. An air chamber335is formed between the striker331and the piston315and serves to linearly move the striker331via air pressure fluctuations caused by reciprocating movement of the piston315. The impact bolt333is configured to transmit kinetic energy of the striker331to the tool accessory101. As shown inFIG.1, the impact bolt333is arranged to be slidable in the front-rear direction within the tool holder30that is coaxially arranged with the cylinder317.

When the motor2is driven and the piston315is moved forward, air in the air chamber335is compressed and its internal pressure increases. The striker331is pushed forward at high speed by action of the air spring and collides with the impact bolt333, thereby transmitting its kinetic energy to the tool accessory101. As a result, the tool accessory101is linearly driven in parallel to the driving axis A1and strikes a workpiece. On the other hand, when the piston315is moved rearward, air of the air chamber335expands so that the internal pressure decreases and the striker331is retracted rearward. The rotary hammer100produces (provides) hammering motion by causing the motion converting mechanism31and the striking mechanism33to repeat these operations.

The rotation transmitting mechanism35is configured to transmit torque of the motor shaft25to the tool holder30. In this embodiment, as shown inFIG.2, the rotation transmitting mechanism35includes the driving gear29formed on the motor shaft25, an intermediate shaft36and a clutch mechanism54. The rotation transmitting mechanism35is configured as a reduction gear mechanism, and the rotation speeds of the motor shaft25, the intermediate shaft36and the tool holder30are reduced in this order.

The intermediate shaft36is arranged in front of and above the motor2in parallel to the motor shaft25. A driven gear362is provided on a lower portion of the intermediate shaft36and engaged with the driving gear29. A small bevel gear361is provided on an upper end portion of the intermediate shaft36.

The clutch mechanism54is on the tool holder30. The clutch mechanism54is configured to transmit torque from the motor shaft25to the tool holder30or to interrupt the torque transmission. In this embodiment, the clutch mechanism54includes a gear sleeve56having a large bevel gear561, and a driving sleeve55. The gear sleeve56is supported around a rear end portion of the tool holder30so as to be rotatable around the driving axis A1. The large bevel gear561is engaged with the small bevel gear361provided on the upper end portion of the intermediate shaft36.

The driving sleeve55has a tubular shape and is spline-connected to an outer periphery of the tool holder30in front of the gear sleeve56. Thus, the driving sleeve55is engaged with the tool holder30so as to be restrained from moving in a circumferential direction relative to the tool holder30while being movable in the front-rear direction.

A rearmost position (hereinafter referred to as a position Pd) and a foremost position (hereinafter referred to as a position Ph) within a moving range of the driving sleeve55are shown inFIGS.2,8and11. The driving sleeve55is engaged with a front end portion of the gear sleeve56when moved to the position Pd (seeFIG.8). In this state, torque of the motor2can be transmitted to the tool holder30via the rotation transmitting mechanism35. When the motor2is driven, the motion converting mechanism31is also driven as described above. Therefore, when the motor2is driven while the driving sleeve55is in the position Pd, rotating motion and hammering motion are simultaneously performed in the rotary hammer100. Thus, when the driving sleeve55is moved to the position Pd, the action mode of the rotary hammer100is changed (set) to the rotary hammer mode.

The driving sleeve55is disengaged from the gear sleeve56when moved forward from the position Pd (seeFIG.11). Thus, torque of the motor2cannot be transmitted to the tool holder30via the rotation transmitting mechanism35. When moved to the position Ph, as shown inFIG.2, the driving sleeve55is engaged with a lock ring301fixed to the gear housing12, so that the tool holder30cannot rotate around the driving axis A1. In this state, when the motor2is driven, the motion converting mechanism31is driven, and hammering only motion is performed in the rotary hammer100. Thus, when the driving sleeve55is moved to the position Ph, the action mode of the rotary hammer100is changed (set) to the hammer mode. In this manner, in the rotary hammer100, the action mode is changed by the driving sleeve55being moved in parallel to the driving axis A1(in the front-rear direction).

When the driving sleeve55is moved to a position between the position Ph and the position Pd as shown inFIG.11, torque of the motor2cannot be transmitted to the tool holder30as described above. Further, the driving sleeve55is not engaged with the lock ring301, so that the tool holder30is not fixed to the gear housing12. Therefore, in this state, a user can hold and turn the tool accessory101around the driving axis A1with fingers together with the tool holder30. Thus, the action mode of the rotary hammer100is changed (set) to a mode in which a user is allowed to position the tool accessory101on a workpiece. This action mode is also referred to as a “neutral mode”.

A structure for changing the action mode of the rotary hammer100is now described. The rotary hammer100has a mode changing operation part6to be manually operated (manipulated) by a user and the transmitting mechanism4configured to transmit the user's manual operation (manipulation) of the mode changing operation part6to the driving sleeve55, and is configured to change the action mode via these parts.

As shown inFIGS.1,2,8and11, the mode changing operation part6is on the tool body and faces the grip part170. The mode changing operation part6faces the switch lever171provided on the front side of the grip part170. In this embodiment, the mode changing operation part6is supported by the gear housing12so as to be linearly movable in the left-right direction while being partly exposed through an opening122formed in an upper portion of a rear wall121of the gear housing12. The mode changing operation part6is also referred to as a mode change lever.

The mode changing operation part6has a main operation part61to be manually operated by a user, and a base62connected to the main operation part61. As shown inFIG.3, the main operation part61has a rectangular plate part611having a long axis in the left-right direction, and a lever612protruding rearward from the plate part611. The lever612is formed on a central part of the plate part611in the left-right direction and extends in the up-down direction. The mode changing operation part6is movable between a position P1and a position P2that are respectively located to the left and right of a position Pn where the lever612is located at the center of the opening122in the left-right direction. InFIG.3, the mode changing operation part6located in the position P2is shown in solid lines, and the mode changing operation part6located in the position Pn or P1is shown in two-dot chain lines. A user manually operates the lever612to move the mode changing operation part6to the position P2in order to change the action mode into the hammer mode, or to the position P1in order to change the action mode into the rotary hammer mode, or to the position Pn in order to change the action mode into the neutral mode, which will be described in detail below.

The base62of the mode changing operation part6is held by the gear housing12so as to be movable in the left-right direction. As shown inFIG.4, leaf springs125are arranged on upper and lower sides of the base62and held by the gear housing12. Each of the leaf springs125extends in the left-right direction in sectional view. The leaf spring125has a projection126protruding toward the base62at a position corresponding to the center of the opening122in the left-right direction. The base62has an upper end having recesses62p2,62pn,62p1recessed downward and a lower end having recesses62p2,62pn,62p1recessed upward. The recesses62p2,62pn,62p1are arranged in this order from left to right and configured to be engaged with the projection126of the leaf spring125. InFIG.4, the projection126is engaged with the recess62p2. The recesses62p2,62pn,62p1are spaced apart from each other in the left-right direction so as to position the mode changing operation part6in the positions P2, Pn, P1, respectively, when engaged with the projection126. In this manner, the mode changing operation part6is held in the position P2, Pn or P1by biasing force of the leaf springs125.

The transmitting mechanism4is now described. The transmitting mechanism4is configured to transmit the user's manual operation of the mode changing operation part6to the driving sleeve55. In this embodiment, as shown inFIG.2, the transmitting mechanism4has a first converting mechanism40, and a connecting member70that connects the first converting mechanism40and the driving sleeve55. The first converting mechanism40is configured to convert linear sliding movement of the mode changing operation part6(the main operation part61) in the left-right direction into linear motion in a direction parallel to the driving axis A1(the front-rear direction). The connecting member70is arranged to be movable in parallel to the driving axis A1and configured to connect the first converting mechanism40and the driving sleeve55.

The first converting mechanism40is described now. The first converting mechanism40is configured as a rack and pinion mechanism. As shown inFIGS.2,8and11, the first converting mechanism40includes a first rack gear621, a first pinion gear41, a first shaft43, a second pinion gear42and a second rack gear712. In this embodiment, these components of the first converting mechanism40are configured to move the connecting member70to a rearmost position within a moving range of the connecting member70when the mode changing operation part6is moved to the position P1and to move the connecting member70to a foremost position within the moving range when the mode changing operation part6is moved to the position P2. These components are now described below.

The first rack gear621is a part of the mode changing operation part6. As shown inFIG.5, the first rack gear621is on a front portion of the base62. The first rack gear621linearly moves in the left-right direction along with linear movement of the mode changing operation part6(the main operation part61) in the left-right direction.

The first pinion gear41is engaged with the first rack gear621on the front side of the first rack gear621. As shown inFIGS.2,8and11, the first shaft43extends in the up-down direction and is rotatably supported by the gear housing12. The first pinion gear41is fixed to a lower portion of the first shaft43. The second pinion gear42is fixed to an upper portion of the first shaft43. A central axis of the first shaft43is coincident with a rotational axis of the first and second pinion gears41,42(hereinafter referred to as a rotational axis A3). When the first rack gear621moves in the left-right direction, the first pinion gear41rotates around the rotational axis A3and rotates the first shaft43. Thus, the second pinion gear42held on the upper portion of the first shaft43rotates around the rotational axis A3.

The second rack gear712is engaged with the second pinion gear42on the upper portion of the first shaft43. As shown inFIGS.2and6, the second rack gear712is provided on a first member71that extends in the front-rear direction in an upper portion of the first converting mechanism40. The first member71having the second rack gear712is moved in parallel to the driving axis A1(in the front-rear direction) by rotation of the second pinion gear42around the rotational axis A3. In this manner, the first converting mechanism40converts movement of the mode changing operation part6in the left-right direction into linear motion parallel to the driving axis A1.

The connecting member70is described now. As shown inFIGS.2and6, the connecting member70includes the first member71having the second rack gear712, a second member72, a third member73, and an engagement arm74that is engaged with the driving sleeve55. These members are connected in series in this order from rear to front and arranged within the gear housing12so as to be integrally movable in the front-rear direction. The connecting member70is moved in the front-rear direction via the second rack gear712by rotation of the second pinion gear42. The connecting member70is configured to move the driving sleeve55to the position Ph by moving to the foremost position within the moving range and to move the driving sleeve55to the position Pd by moving to the rearmost position within the moving range. Further, the connecting member70has such a length in the front-rear direction as to move to the foremost position when the mode changing operation part6is moved to the position P2and to move to the rearmost position when the mode changing operation part6is moved to the position P1.

The connecting member70is described in further detail. When the second pinion gear42rotates around the rotational axis A3, the second rack gear712is moved in the front-rear direction and thus the first member71is moved in the front-rear direction. In this embodiment, the first member71has a plate-like part711extending in the front-rear direction, and an upper projection717(seeFIG.2) formed at a front end of the plate-like part711and protruding upward from the plate-like part711. The second rack gear712is provided on the plate-like part711. As shown inFIG.6, the first member71further has a right projection713protruding to the right from the front end portion of the plate-like part711, and a left projection714protruding to the left from the front end portion of the plate-like part711.

The second member72is a rod-like member extending in the front-rear direction. A rear end portion of the second member72is inserted into the upper projection717of the first member71and connected to the first member71. InFIG.6, a connection between the first member71and the second member72is shown by showing the inside of the upper projection717. The third member73is a rectangular member and a front end portion of the second member72is connected to a rear end portion of the third member73. The engagement arm74is an elongate plate-like member extending in the front-rear direction. As shown inFIG.2, a rear end portion of the engagement arm74is connected to a front end portion of the third member73. A bifurcated front end portion of the engagement arm74is bent downward like a hook and engaged with an annular groove551formed in an outer periphery of the driving sleeve55. In this embodiment, a through hole is formed in the rear end portion of the engagement arm74, and a connection pin76is inserted through the through hole. Further, a torsion spring77is held on a left front end portion of the third member73, and a lower end portion of the connection pin76is pinched between two arms of the torsion spring77by biasing force of the torsion spring77. One of the two arms that is arranged on the rear side of the connection pin76is engaged to the third member73.

With the above-described structure, when the mode changing operation part6is moved rightward to the position P2(seeFIG.5), the first converting mechanism40converts the rightward movement of the mode changing operation part6into forward linear motion of the connecting member70. Thus, the connecting member70moves to the foremost position within the moving range (seeFIGS.1,2and6), and the driving sleeve55is moved to the position Ph (seeFIG.2). As a result, the action mode of the rotary hammer100is changed (set) to the hammer mode.

When the mode changing operation part6is moved leftward to the position P1as shown inFIG.7, the first converting mechanism40converts the leftward movement of the mode changing operation part6into rearward linear motion of the connecting member70. Thus, as shown inFIGS.8and9, the connecting member70moves to the rearmost position within the moving range, and the driving sleeve55is moved to the position Pd. As a result, the action mode of the rotary hammer100is changed (set) to the rotary hammer mode.

When the mode changing operation part6is moved rightward or leftward to the position Pn as shown inFIG.10, the first converting mechanism40converts the rightward or leftward movement of the mode changing operation part6into forward or rearward linear motion of the connecting member70along the driving axis A1. Thus, as shown inFIGS.11and12, the connecting member70moves to a position between the foremost position and the rearmost position within the moving range, and the driving sleeve55is moved to a position between the position Ph and the position Pd. As a result, the action mode of the rotary hammer100is changed to the neutral mode.

The locking mechanism8is now described with reference toFIGS.13to15. In this embodiment, the locking mechanism8includes a lock lever180and the first member71.

The lock lever180is provided directly above the switch lever171in the upper end portion (in the vicinity of the connection part173) of the handle17, and supported to be movable in the left-right direction relative to the handle17. In this embodiment, the lock lever180has a rod-like body181extending in the left-right direction, and two locking pieces182protruding downward from a lower end of the body181. As shown inFIG.13, opposite end portions of the body181in the left-right direction are exposed through openings177formed in left and right walls of the connection part173. A user can manually operate (manipulate) the lock lever180by pushing the body181to the left or right into the handle17.

The switch lever171of this embodiment has two locking projections178protruding upward. As shown in solid lines inFIG.13, the two locking pieces182of the lock lever180are spaced apart from each other in the left-right direction such that one of the locking projections178of the switch lever171can pass between the locking pieces182. As shown in two-dot chain lines inFIG.13, the distance between the two locking pieces182of the lock lever180is equal to the distance between the two locking projections178of the switch lever171.

The lock lever180can be moved to a lock position, in which the lock lever180can lock the switch lever171in the ON position, and to a non-lock position, in which the lock lever180cannot lock the switch lever171in the ON position. More specifically, the lock position is a position of the lock lever180where the locking pieces182of the lock lever180are respectively on moving paths of the locking projections178of the switch lever171as shown in two-dot chain lines inFIG.13. In the lock position, rear ends of the locking pieces182of the lock lever180can abut on front ends of the locking projections178of the switch lever171in the ON position, so that the switch lever171can be held in the ON position. The non-lock position is a position of the lock lever180where the locking pieces182of the lock lever180are respectively out of the moving paths of the locking projections178of the switch lever171as shown in solid lines inFIG.13. In the non-lock position, the locking pieces182do not interfere with movement of the locking projections178in the front-rear direction, so that the switch lever171can be moved between the ON position and the OFF position. The lock lever180is normally placed in the non-lock position (shown in solid lines inFIG.13) by a user so as to allow operation of the switch lever170, and is moved to the lock position by the user only when locking the switch lever170in the ON position. Although not shown, in this embodiment, the lock lever180is held in the non-lock position or in the lock position by biasing force of a biasing member.

The lock lever180has a lock hole184formed in a substantially central portion of the body181in the left-right direction and extending through the body181in the front-rear direction. The lock hole184has a height in the up-down direction and a width in the left-right direction to allow insertion of the plate-like member711of the first member71. The first member71forms part of the connecting member70as described above and moves in the front-rear direction in response to the user's operation of the mode changing operation part6.

The positional relation between the connecting member70and the lock hole184is shown inFIGS.6,9and12. The plate-like member711of the first member71extends in the front-rear direction. The plat-like member711is configured such that, when the mode changing operation part6is moved to the position P1(i.e. when the rotary hammer mode is selected), the plate-like member711is moved to the rearmost position within the moving range by the first converting mechanism40and engaged with the lock hole184. The plate-like member711is also configured such that, when the mode changing operation part6is moved to the position Pn or P2(i.e. when the neutral mode or the hammer mode is selected), the plate-like member711is moved forward from the rearmost position by the first converting mechanism40and disengaged from the lock hole184.

With the above-described structure, when the mode changing operation part6is moved to the position P1(i.e. when the rotary hammer mode is selected), the connecting member70is moved to the rearmost position within the moving range and the plate-like member711is engaged with the lock hole184(seeFIGS.9and15). Thus, the lock lever180is restrained from moving in the left-right direction by the first member71and locked in the non-lock position. When the mode changing operation part6is moved to the position P2(i.e. when the hammer mode is selected), the connecting member70is moved to the foremost position within the moving range and the plate-like member711is disengaged from the lock hole184(seeFIGS.6and14). Thus, the lock lever180can be moved in the left-right direction. In this state, when the lock lever180is moved to the lock position by a user, the switch lever171is held in the ON position. Thus, in the hammer mode, the user can keep the ON state of the switch lever171by pushing the lock lever180to the lock position, without continuing manually depressing the switch lever171.

Next, the mode detecting part90of the rotary hammer100, and control of the motor2by the controller9using the mode detecting part90and the acceleration sensor95are now described.

First, the mode detecting part90is described. The mode detecting part90is configured to detect the action mode (a current actual action mode (currently selected operation mode), or specifically, the position of the driving sleeve55). In this embodiment, the mode detecting part90includes a first switch91and a second switch92that are arranged in an upper part of the gear housing12. In this embodiment, the first and second switches91,92are push type micro switches. The first and second switches91,92are configured to output a signal (ON signal) to the controller9when pushed.

The first switch91is arranged behind the right projection713of the first member71to face the right projection713, and fixed to the gear housing12. The positional relation between the right projection713and the first switch91is adjusted such that a rear end surface of the right projection713abuts on the first switch91and pushes the first switch91rearward when the connecting member70is moved to the rearmost position (i.e. when the driving sleeve55is moved to the position Pd). The second switch92is arranged in front of the left projection714of the first member71to face the left projection714, and fixed to the gear housing12. The positional relation between the left projection714and the second switch92is adjusted such that a front end surface of the left projection714abuts on the second switch92and pushes the second switch92forward when the connecting member70is moved to the foremost position (i.e. when the driving sleeve55is moved to the position Ph).

With such a structure, the controller9can determine (detect) the action mode of the rotary hammer100from detection results of the first and second switches91,92(i.e. the position of the driving sleeve55). Specifically, the action mode of the rotary hammer100is determined as the rotary hammer mode if an ON signal is outputted from the first switch91to the controller9, and determined as the hammer mode if an ON signal is outputted from the second switch92to the controller9. If an ON signal is not outputted from the first and second switches91,92, the action mode is determined as the neutral mode.

Control of the motor2by the controller9based on detection results of the mode detecting part90and the acceleration sensor95is now described. In the rotary hammer mode, which involves rotating motion, if the tool accessory101is jammed on the workpiece and the tool holder30cannot rotate (is locked or blocked), excessive reaction torque may act on the tool body10and cause excessive rotation (kickback) of the tool body10around the driving axis A1.

In this embodiment, when the motor2is driven, the controller9obtains detection results of the acceleration sensor95and successively determines whether the detection results exceed a predetermined threshold. The threshold is a threshold of acceleration obtained in the state of excessive rotation of the tool body10around the driving axis A1, and is stored in advance in a memory of the controller9. The threshold can be obtained by experiment or simulation.

Further, the controller9determines whether the action mode is the rotary hammer mode, based on detection results of the mode detecting part90. In this embodiment, when receiving an ON signal from the first switch91, the controller9determines that the action mode is the rotary hammer mode.

When the acceleration exceeds the threshold and the action mode is the rotary hammer mode, the controller9stops driving of the motor2. This eliminates the state of excessive rotation of the rotary hammer100. When not receiving an ON signal from the first switch91(i.e. when the detection results of the mode detecting part90do not indicate the rotary hammer mode) even if the detection results of the acceleration sensor95exceed the threshold, the controller9continues driving of the motor2. This allows the user to continue operation in the hammer mode even if the detection results of the acceleration sensor95temporarily exceed the threshold, for example, due to impact of contact of the rotary hammer100with a wall or the like around the workpiece during operation in the hammer mode.

The above-described rotary hammer100according to this embodiment has the following effects.

In the rotary hammer100of this embodiment, the mode changing operation part6for changing the action mode is on the tool body10and faces the grip part170. Thus, this eliminates or reduces the possibility of collision of the mode changing operation6with the ground or a wall or the like, for example, even if the rotary hammer100is unintentionally dropped and collides therewith. Thus, the possibility of damage to the mode changing operation part6due to external impact on the rotary hammer100is reduced.

In the rotary hammer100, the distance (center height) from the driving axis A1to an outer surface around the driving axis A1in the rotary hammer100can be shortened, compared with a structure in which an operation part for changing the action mode is arranged on a surface (such as an upper surface or a side surface) of the rotary hammer100around the driving axis A1. This can improve the maneuverability of the rotary hammer100.

Further, in the rotary hammer100, the outer surface around the driving axis A1can be formed flat and smooth, compared with a structure in which the operation part for changing the action mode is arranged on a surface (such as the upper surface or the side surface) of the rotary hammer100around the driving axis A1. Therefore, according to this embodiment, the rotary hammer100is provided with improved designability.

The mode changing operation part6faces the switch lever171on the tool body10. This allows the user to operate the mode changing operation part6and the switch lever171with the same hand, and thus, for example, to change the operation mode and start the motor2without moving an arm of the user. Therefore, according to this embodiment, the rotary hammer100is provided with improved maneuverability.

The rotary hammer100has the transmitting mechanism4that is configured to transmit movement of the mode changing operation part6to the driving sleeve55and move the driving sleeve55in parallel to the driving axis A1. Thus, the transmitting mechanism4can transmit movement of the mode changing operation part6(provided in a position facing the grip part170) in the left-right direction to the driving sleeve55(provided onto the tool holder30configured to be rotationally driven around the driving axis A1).

Further, the transmitting mechanism4is configured to, when the mode changing operation part6is moved to the position P1, move the driving sleeve55to the position Pd and thereby transmit torque of the motor2to the tool holder30. The transmitting mechanism4is further configured to, when the mode changing operation part6is moved to the position P2, move the driving sleeve55to the position Ph and thereby interrupt the torque transmission. Therefore, in the rotary hammer100, by user's manual operation of the mode changing operation part6, the driving sleeve55is moved to switch the action mode between the rotary hammer mode and the hammer mode.

The transmitting mechanism4includes the first converting mechanism40configured to convert linear sliding movement of the mode changing operation part6in the left-right direction into rotating motion and further convert the rotating motion into linear motion along the driving axis A1. Therefore, in the rotary hammer100, compared with a structure not having the first converting mechanism40, the degrees of freedom in arrangement of the driving sleeve55and the mode changing operation part6and in configuration of the transmitting mechanism4are enhanced.

The leaf springs125are arranged on upper and lower sides of the base62of the mode changing operation part6and held by the gear housing12, and the mode changing operation part6is configured to be held in the position P1corresponding to the rotary hammer mode or the position P2corresponding to the hammer mode by the biasing force of the leaf springs125. Therefore, according to this embodiment, the rotary hammer100is provided that facilitates moving the mode changing operation part6in the left-right direction and positioning it in the position P1or P2.

The rotary hammer100of this embodiment has the locking mechanism8. The locking mechanism8is configured such that, in the hammer mode in which the tool accessory101produces (provides) hammering only motion, the first member71is not engaged with the lock lever180and thus allows the lock lever180to move to the lock position. Therefore, the user need not continue manually depressing the switching lever171during operation of continuously performing hammering only motion for a relatively long time. Thus, the burden on the user during the operation can be reduced. Further, the locking mechanism8is configured such that, in the rotary hammer mode in which the tool accessory101produces (provides) rotating motion, the first member71is engaged with the lock lever180and holds the lock lever180in the non-lock position. Thus, the user can stop driving of the motor2simply by releasing the switch lever171, for example, even if the tool accessory101is jammed on the workpiece. Therefore, the rotary hammer100can be provided with high safety.

The rotary hammer100has the mode detecting part90and the acceleration sensor95, and the controller9is configured to stop driving of the motor2when determining excessive rotation of the tool body10around the driving axis A1based on detection results of the acceleration sensor95and determining that the operation mode is the rotary hammer mode based on detection results of the mode detecting part90. Thus, the safety of the rotary hammer100can be enhanced. Further, in the hammer mode, the controller9is configured to continue driving of the motor2even if the detection results of the acceleration sensor95indicate occurrence of excessive rotation of the tool body10around the driving axis A1. Thus, the user can continue operation in the hammer mode even if the detection results of the acceleration sensor95temporarily indicate occurrence of excessive rotation of the tool body10, for example, due to impact of contact of the rotary hammer100with a wall or the like around the workpiece during operation in the hammer mode. Therefore, the possibility that the motor2is stopped during the hammer mode without user's intention is reduced. Thus, according to this embodiment, the rotary hammer100can be provided with improved safety and maneuverability.

In the rotary hammer100, the acceleration sensor95is housed within the handle17, and the tool holder10and the handle17are connected via the elastic members175,176. This structure can reduce transmission of vibration from the tool body10to the acceleration sensor95and thus prolongs the life of the acceleration sensor95.

Further, in this embodiment, the acceleration sensor95is housed within a lower part of the handle17. Therefore, the accuracy of detecting rotation of the tool body10around the driving axis A1can be enhanced, compared with a structure in which the acceleration sensor95is housed within an upper portion of the handle17or other positions close to the driving axis A1.

Correspondences

Correspondences between the features of the above-described embodiment and the features of the present disclosure are as follows. The features of the above-described embodiment are merely exemplary and do not limit the features of the present disclosure.

The rotary hammer100is an example of the “power tool having a rotary hammer mechanism”.

The motor2is an example of the “motor”.

The tool accessory101is an example of the “tool accessory”.

The driving axis A1is an example of the “driving axis”.

The rotary hammer mode is an example of the “first mode”.

The hammer mode is an example of the “second mode”.

The driving mechanism3is an example of the “driving mechanism”.

The tool body10is an example of the “tool body”.

The grip part170is an example of the “grip part”.

The handle17is an example of the “handle”.

The mode changing operation part6is an example of the “first operation member”.

The switch lever171is an example of the “second operation member”.

The positions P1and P2are examples of the “first position” and the “second position”, respectively.

The tool holder30is an example of the “tool holder”.

The driving sleeve55is an example of the “clutch member”.

The positions Pd and Ph are examples of the “third position” and the “fourth position”, respectively.

The transmitting mechanism4is an example of the “transmitting mechanism”.

The first converting mechanism40is an example of the “converting mechanism”.

The first pinion gear41and the second pinion gear42are examples of the “at least one pinion gear”.

The first rack gear621and the second rack gear712are examples of the “first rack gear” and the “second rack gear”, respectively.

The leaf spring125is an example of the “biasing member”.

The lock lever180is an example of the “locking member”.

The first member71is an example of the “lock controlling member”.

The first switch91and the mode detecting part90are examples of the “mode detecting part”.

The acceleration sensor95is an example of the “rotation detecting part”.

The controller9is an example of the “controlling part”.

The elastic members175,176are examples of the “elastic member”.

Other Embodiments

In the above-described embodiment, the rotary hammer100may be configured to be operated by power supplied not from an external AC power source but from a rechargeable battery. In this case, in place of the power cord19, a battery mounting part, which is configured to removably receive the battery, may be provided, for example, in a lower end portion of the handle17.

The mode changing operation part6may be provided, for example, on a rear wall of the motor housing13, as long as the mode changing operation part6faces the grip part170. This structure also reduces the possibility of damage to the mode changing operation part6due to drop of the rotary hammer100.

The mode changing operation part6may be configured to be linearly moved not only in the left-right direction but, for example, in the up-down direction. Further, the moving path of the mode changing operation part6may not be linear but, for example, arcuate.

It may be sufficient for the mode detecting part90to detect at least the rotary hammer mode and thus, for example, the mode detecting part90may not have the second switch92. In this case, the controller9may be configured to, when the detection results of the acceleration sensor95exceed the threshold, stop driving of the motor2if receiving a signal that the first switch91has been pushed, while continuing driving of the motor2if not receiving the signal that the first switch91has been pushed. Further, the mode detecting part90is not limited to the push type micro switch, but may include a detector(s) of a different type that is configured to detect the position (movement) of the driving sleeve55. Examples of the detector may include a contact type detector (e.g., a switch of other type), a non-contact type detector (e.g., a magnetic sensor and an optical sensor).

The rotary hammer100may have any other detecting device capable of detecting the state of rotation of the tool body10around the driving axis A1, in place of the acceleration sensor95. Examples of the detecting device may include a speed sensor, an angular speed sensor and an angular acceleration sensor.

In the above-described embodiment, the rotary hammer100is capable of operating in an operation mode, which is selected from the plurality of action modes including the rotary hammer mode and the hammer mode. The above-described embodiment may however be applied to a power tool having a rotary hammer mechanism that is configured to selectively operate in any of the rotary hammer mode, the hammer mode and a rotation mode. In this case, in the rotation mode, driving of the motor2may be controlled in the same manner as in the rotary hammer mode.

In the above-described embodiment, the first converting mechanism40has the first rack gear621, the first pinion gear41, the first shaft43, the second pinion gear42and the second rack gear712. Alternatively, a common pinion gear may be engaged with the first rack gear621and the second rack gear712. In other words, the first converting mechanism40may employ a single pinion gear. For example, the first converting mechanism40may be formed by the first rack gear621, a pinion gear engaged with the first rack gear621, and the second rack gear712engaged with the pinion gear. In this case, the pinion gear can convert sliding movement of the first rack gear621in the left-right direction into rotating motion and then convert the rotating motion into linear motion of the second rack gear712in parallel to the driving axis A1.

The structure of the transmitting mechanism4is not limited to the structure of the above-described embodiment, as long as the transmitting mechanism4is configured to move the driving sleeve55along the driving axis A1in response to the sliding movement of the mod changing operation part6within the predetermined range. In the case of the transmitting mechanism4having the connecting member70, it is sufficient for the connecting member70to connect the first converting mechanism40and the driving sleeve55, and the number and structures of parts (components, elements) of the connecting member70and connection between the parts are not limited to those of the above-described embodiment.

In the above-described embodiment, the drive control of the motor2is executed by a CPU, but other kinds of control circuits, including programmable logic devices such as an ASIC (application specific integrated circuit) and an FPGA (field programmable gate array), may be adopted in place of the CPU. The drive control of the motor2may be executed by a plurality of control circuits in a distributed manner.

DESCRIPTION OF THE REFERENCE NUMERALS

2: motor,3: driving mechanism,4: transmitting mechanism,6: mode changing operation part,8: locking mechanism,9: controller,10: tool body,12: gear housing,13: motor housing,17: handle,19: power cord,20: motor body,21: stator,22: rotor,25: motor shaft,29: driving gear,30: tool holder,31: motion converting mechanism,33: striking mechanism,35: rotation transmitting mechanism,36: intermediate shaft,40: first converting mechanism,41: first pinion gear,42: second pinion gear,43: first shaft,54: clutch mechanism,55: driving sleeve,56: gear sleeve,61: main operation part,62: base,62p1: recess,62p2: recess,62pn: recess,70: connecting member,71: first member,72: second member,73: third member,74: engagement arm,76: connection pin,77: torsion spring,90: mode detecting part,91: first switch,92: second switch,95: acceleration sensor,100: rotary hammer,101: tool accessory,121: rear wall,122: opening,125: leaf spring,126: projection,132: rear wall,170: grip part,171: switch lever,171: main switch,173: connection part,174: connection part,175: elastic member,177: opening,178: locking projection,180: lock lever,181: body,182: locking piece,184: lock hole,301: lock ring,311: crank shaft,312: driven gear,313: connecting rod,315: piston,317: cylinder,331: striker,333: impact bolt,335: air chamber,361: small bevel gear,362: driven gear,551: annular groove,561: large bevel gear,611: plate part,612: lever,621: first rack gear,711: plate part,712: second rack gear,713: right projection,714: left projection,717: upper projection, A1: driving axis, A2: rotational axis, A3: rotational axis