Patent ID: 12186929

DETAILED DESCRIPTION

Representative, non-limiting examples of the present disclosure will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing aspects of the present teachings and is not intended to limit the scope of the present disclosure. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved chainsaws, as well as methods for using and manufacturing the same.

Moreover, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the present disclosure in the broadest sense, and are instead taught merely to particularly describe representative examples of the present disclosure. Furthermore, various features of the above-described and below-described representative examples, as well as the various independent and dependent claims, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

In one or more embodiments, a chainsaw may comprise: a saw chain; a guide bar equipped with the saw chain; a sprocket for running the saw chain along a periphery of the guide bar; a prime mover configured to rotate the sprocket about a rotation axis; a housing for housing the prime mover; a sprocket cover for covering the sprocket; and a guide member. The guide bar, the housing and the sprocket cover may define a chain passage, the saw chain passing through the chain passage. The guide member may include: a first facing surface arranged such that the first facing surface faces the saw chain in the chain passage, the first facing surface having an arc shape centered on the rotation axis when viewed in a direction along the rotation axis; and a second facing surface arranged such that the second facing surface faces the saw chain in the chain passage, the second facing surface having an arc shape centered on a position offset from the rotation axis when viewed in the direction along the rotation axis. When the chainsaw is placed on a horizontal mounting surface and viewed in the direction along the rotation axis, an angle between (i) a straight line connecting the rotation axis and a position where the first facing surface and the second facing surface are connected and (ii) a horizontal plane may be in a range of −10 degrees to 25 degrees. The “angle between the straight line and the horizontal plane” referred herein is a positive angle when the position where the first facing surface and the second facing surface are connected is below the horizontal plane, and is a negative angle when the position is above the horizontal plane.

According to the above configuration, since the passage area of the chain passage is reduced at the position where the first facing surface and the second facing surface of the guide member are connected, the cutting chips can be suppressed from advancing deep into the chain passage. Further, according to the above configuration, the cutting chips that were prohibited from advancing deep into the chain passage is discharged along the second facing surface having the arc shape, thus the cutting chips can be suppressed from being accumulated in the chain passage. Further, according to the above configuration, since the angle between (i) the straight line connecting the rotation axis and the position where the first facing surface and the second facing surface are connected and (ii) the horizontal plane is in the range of −10 degrees to 25 degrees when the chainsaw is placed on the horizontal mounting surface and viewed in the direction along the rotation axis, the cutting chips that were prohibited from advancing deep into the chain passage can easily be discharged downward by a gravitational force.

In one or more embodiments, the guide member may include a first guide member having the first facing surface and constituted of a rubber material. The first guide member may be detachably attached to the housing or the sprocket cover.

According to the above configuration, even when the saw chain collides with the first facing surface, the first guide member absorbs an impact thereof, thus the housing and the sprocket cover can be suppressed from being damaged. Further, according to the above configuration, even when the first guide member is damaged, it can easily be replaced with a new first guide member.

In one or more embodiments, when the chainsaw is placed on the horizontal mounting surface and viewed in the direction along the rotation axis, the first facing surface may reach vertically above the rotation axis.

According to the above configuration, since a large area of the chain passage can be covered by the first facing surface, the housing and the sprocket cover can further be ensured to be protected from damages caused by collision with the saw chain.

In one or more embodiments, the guide member may further include a second guide member having the second facing surface and constituted of a rubber material. The second guide member may be detachably attached to the housing or the sprocket cover.

According to the above configuration, even when the saw chain collides with the second facing surface, the second guide member absorbs an impact thereof, thus the housing and the sprocket cover can be suppressed from being damaged. Further, according to the above configuration, even when the second guide member is damaged, it can easily be replaced with a new second guide member.

In one or more embodiments, the first guide member and the second guide member may be formed seamlessly and integrally.

According to the above configuration, the number of components of the chainsaw can be reduced.

In one or more embodiments, a radius of curvature of the second facing surface may be equal to or less than half a radius of curvature of the first facing surface.

When the radius of curvature of the second facing surface becomes larger, a size of the chainsaw in a longitudinal direction of the guide bar must be increased accordingly. According to the above configuration, the size of the chainsaw in a longitudinal direction of the guide bar can be made compact.

EMBODIMENT

As shown inFIGS.1and2, a chainsaw2of the present embodiment comprises a body4, a guide bar6, and a saw chain8. The guide bar6is an elongated plate-shaped member attached to the body4such that it protrudes forward from the body4. The guide bar6is constituted of a metal material such as iron. The saw chain8includes a plurality of cutters connected to each other, and is arranged along a periphery of the guide bar6. A battery pack B is attached to the body4. The chainsaw2is configured to cut objects such as wood materials by rotating the saw chain8along the periphery of the guide bar6using electric power supplied from the battery pack B. Various types of guide bars may be attached as the guide bar6in accordance with contents of cutting work. In the example shown inFIGS.1and2, a curvature radius of the end of the guide bar6is 10 mm, for example. The chainsaw2of the present embodiment is configured to drive and rotate the saw chain8along the periphery of the guide bar6at a speed of 25.5 m/s, for example. In the following description, with respect to the chainsaw2placed on a horizontal mounting surface S such as the ground as shown inFIG.3, a direction that orthogonally intersects the mounting surface S will be termed an up-down direction of the chainsaw2, a direction defined by projecting a longitudinal direction of the guide bar6on the mounting surface S will be termed a front-rear direction of the chainsaw2, and a direction orthogonally intersecting the up-down direction and front-rear direction of the chainsaw2will be termed a left-right direction of the chainsaw2. In drawings other thanFIGS.1to3, depiction of the saw chain8is omitted for clearer indication of the drawings.

As shown inFIGS.1and2, the body4comprises a left housing10, a right housing12, a base member14, a front handle16, a front hand guard18, a brake cover20, and a sprocket cover22. The left housing10, the right housing12, the front hand guard18, the brake cover20, and the sprocket cover22are constituted of a resin material such as polyamide resin. The base member14is constituted of a metal material such as magnesium alloy. A thermal conductivity of the base member14may for example be 10 W/mK or more, 30 W/mK or more, or 50 W/mK or more when its temperature is 300 K. The front handle16is constituted of a metal material such as aluminum alloy.

The body4includes a body housing24, a rear handle26, and a rear hand guard28. The body housing24is constitute of a left housing10, a right housing12, a base member14, and a brake cover20. The rear handle26and the rear hand guard28are constituted of the left housing10and the right housing12. The base member14is arranged to the right of a front portion of the right housing12. The brake cover20is arranged to the right of the base member14. The sprocket cover22is arranged to the right of the brake cover20.

The body housing24has a substantially rectangular box shape with its longitudinal direction along the front-rear direction of the body4. As shown inFIG.4, a battery pack receptacle24athat opens upward is defined in a rear portion of the body housing24. A right inner surface of the battery pack receptacle24aincludes a battery pack attachment portion24bto which the battery pack B can be detachably attached by sliding the battery pack B in the up-down direction. A recess24cis defined at the upper end of the right inner surface of the battery pack receptacle24ato allow a user to easily grip the battery pack B upon attaching or detaching the battery pack B.

The rear handle26extends rearward and downward from an upper portion of a rear surface of the body housing24, and is bent downward. The rear handle26has a substantially circular cross-sectional shape. The rear hand guard28extends rearward from a lower portion of the rear surface of the body housing24, and connects to the lower end of the rear handle26. The rear hand guard28has a substantially rectangular box shape of which dimension in the left-right direction is smaller than its dimension in the front-rear direction and of which dimension in the up-down direction is smaller than its dimension in the left-right direction. As shown inFIG.5, the rear hand guard28has a shape that covers an entirety of the rear handle26from below. The rear hand guard28includes a first guard part28aarranged directly below the rear handle26and a second guard part28bextending rightward from the first guard part28a. A hand of the user holding the rear handle26can be protected by the rear hand guard28.

A power button30for the user to switch on/off of power of the chainsaw2is arranged on an upper surface of the rear handle26in the vicinity of its front end. As shown inFIG.6, a power switch32configured to detect an operation performed on the power button30by the user is arranged inside the rear handle26. The power switch32is electrically connected to a control unit34to be described later.

A trigger lever36for the user to control rotation of the saw chain8is arranged on a lower surface of the rear handle26in the vicinity of its front end. The trigger lever36is supported by the rear handle26such that it is rotatable about a rotation shaft36aextending in the left-right direction. A trigger switch38configured to detect an operation by the user to pull up the trigger lever36is arranged inside the body housing24in the vicinity of its rear end. The trigger switch38is electrically connected to the control unit34.

A lock lever40configured to switch between a state allowing the operation by the user on the trigger lever36and a state prohibiting such operation is arranged on the upper surface of the rear handle26. The lock lever40is supported by the rear handle26such that it is rotatable about a rotation shaft40aextending in the left-right direction. With the lock lever40rotated upward, upward rotation of the trigger lever36is prohibited due to the lock lever40interfering with the trigger lever36. With the lock lever40rotated downward, the lock lever40does not interfere with the trigger lever36, thus the upward rotation of the trigger lever36is thereby allowed. A grip detection switch42configured to detect an operation by the user to press down the lock lever40is arranged inside the rear handle26in the vicinity of its front end. The grip detection switch42is electrically connected to the control unit34.

The trigger lever36and the lock lever40are connected to each other by a torsion spring44. The torsion spring44biases the trigger lever36in a direction of rotating downward, and biases the lock lever40in a direction rotating upward. Due to this, when the user is not touching the trigger lever36, the trigger lever36is in a state rotated downward by a biasing force of the torsion spring44. Further, when the user is not touching the lock lever40, the lock lever40is in a state rotated upward by the biasing force of the torsion spring44.

As shown inFIGS.1and2, the front handle16includes a right fixing part16aextending frontward and upward, an upper holding part16bextending leftward and frontward from the upper end of the right fixing part16a, a left holding part16cextending downward from the left end of the upper holding part16b, and a lower fixing part16dextending rightward from the lower end of the left holding part16c. The upper holding part16band the left holding part16chave substantially circular cross-sectional shapes. As shown inFIG.1, the right fixing part16ais fixed to the body housing24(specifically, the right housing12) by a fastener with the right fixing part16ainserted in a right handle attaching groove24ddefined in a right surface of the body housing24(specifically, a right surface of the right housing12). As shown inFIG.2, the lower fixing part16dis fixed to the body housing24(specifically, the left housing10) by a fastener with the lower fixing part16dinserted in a lower handle attaching groove24edefined in a lower surface of the body housing24(specifically, a lower surface of the left housing10).

When the user uses the chainsaw2, he/she holds the chainsaw2by holding the rear handle26with the right hand and holding the front handle16(specifically, the upper holding part16bor the left holding part16c) by the left hand. From this state, when the user presses down the lock lever40of the rear handle26, the operation on the trigger lever36by the user is allowed, and the saw chain8rotates when the user pulls up the trigger lever36with the index finger of the right hand with the lock lever40pressed down.

As shown inFIG.6, the control unit34, a motor46, an oil tank48, and an oil pump50are arranged in a front portion of the inside of the body housing24. The control unit34, the motor46, the oil tank48, and the oil pump50are arranged frontward from the battery pack B. The oil tank48is arranged frontward from the motor46and the oil pump50. The control unit34is arranged above the motor46, the oil tank48, and the oil pump50and along the front-rear direction and the left-right direction.

As shown inFIG.7, the motor46is an inner rotor DC brushless motor. The motor46has a stator54on which a coil52is wound, a rotor58arranged inside the stator54and including a permanent magnet56, an output shaft60arranged to penetrate the center of the stator54and the rotor58and fitted in the rotor58, a cooling fan62fitted on the output shaft60, and a sensor substrate64configured to detect rotation of the rotor58.

The base member14includes a base plate14aextending in the front-rear direction and the up-down direction and a substantially cylindrical supporting rib14bprotruding leftward from the base plate14a. The base plate14aand the supporting rib14bare seamlessly integrated. As shown inFIG.8, a motor casing66is fixed via a fastener to the left end of the supporting rib14b. The motor casing66is constituted of a resin material such as polyamide resin. As shown inFIG.7, the sensor substrate64is arranged facing the left end surface of the stator54. The motor casing66has a shape covering the stator54from radially outward and covering the left end surface of the stator54and the sensor substrate64. The stator54and the sensor substrate64are fixed to the motor casing66via a fastener. The coil52wound on the stator54and the sensor substrate64are each electrically connected to the control unit34(seeFIG.6). Although not shown, the control unit34includes a circuit board on which an inverter circuit having switching elements and a control circuit configured to control operations of the respective switching elements, and a substantially rectangular box-shaped casing that houses the circuit board. The control unit34is configured to control operations of the motor46by controlling a voltage to be applied to the coil52based on detection signals of the sensor substrate64.

As shown inFIG.7, the output shaft60is arranged along the left-right direction of the chainsaw2. The right end of the output shaft60penetrates through the right housing12, the base plate14a, and the brake cover20and protrudes rightward beyond the brake cover20. The left end of the output shaft60penetrates through a left surface of the motor casing66and protrudes leftward beyond the left surface of the motor casing66. The output shaft60is rotatably supported by the base plate14avia a bearing68and is rotatably supported by the motor casing66via a bearing70. The rotor58is arranged to the right of the bearing70, the cooling fan62is arranged to the right of the rotor58, and the bearing68is arranged to the right of the cooling fan62.

The cooling fan62may be a centrifugal fan, and may be a plate fan including a disk-shaped plate62aand a plurality of blades62bprotruding out from the plate62a. As shown inFIG.8, an air intake opening66ais defined in the left surface of the motor casing66. An air exhaust opening14cis defined in the supporting rib14bof the base member14. Further, as shown inFIG.2, an air inlet24fis defined in a left surface of the body housing24(specifically, a left surface of the left housing10), and an air outlet24gis defined in a lower surface of the body housing24(specifically, a lower surface of the right housing12). As shown inFIG.9, the air outlet24gis arranged facing the air exhaust opening14c.

When the cooling fan62rotates, air outside the body housing24flows into the body housing24through the air inlet24fshown inFIG.2. The air that flowed into the body housing24flows into the motor casing66through the air intake opening66ashown inFIG.7. The air that flowed into the motor casing66flows past the sensor substrate64and flows in a gap between the stator54and the rotor58, cools the stator54and the rotor58, and thereafter reaches the cooling fan62. As shown inFIG.9, the air that reached the cooling fan62flows radially outward along the blades62b, and thereafter flows in a circumferential direction along an inner surface of the supporting rib14band cools the base member14, and thereafter flows out from the body housing24through the air exhaust opening14cand the air outlet24g.

As shown inFIG.7, a sprocket72and a brake base74are fixed to the vicinity of the right end of the output shaft60. The sprocket72and the brake base74are arranged to the right of the bearing68. A brake drum76is fitted to the brake base74.

As shown inFIG.10, the sprocket72is exposed outside of the brake cover20. The saw chain8is strapped over the sprocket72from the guide bar6(seeFIGS.1to3). When the motor46(seeFIG.7) is driven, the sprocket72rotates with the output shaft60, and the saw chain8thereby rotates around the sprocket72and the guide bar6.

A long hole6aextending along the longitudinal direction of the guide bar6is defined in the guide bar6. The guide bar6is supported by the base member14via bolts78,80penetrating the long hole6a. As shown inFIG.7, the bolts78,80are fixed to the base plate14a. Nuts82,84are fastened onto the bolts78,80from outside the sprocket cover22. The user can change a distance between the guide bar6and the sprocket72by sliding the guide bar6along the long hole6awith the nuts82,84loosened and thereby adjust tension on the saw chain8.

As shown inFIG.10, an engaging hole88configured to engage with an engaging pin86is defined in the guide bar6. As shown inFIG.11, the engaging pin86is connected to an adjustment screw92via a rotation-linear motion converting mechanism90. The rotation-linear motion converting mechanism90is configured to convert rotary motion of the adjustment screw92into linear motion of the engaging pin86along a direction of the long hole6a. As shown inFIG.10, the adjustment screw92is arranged between the bolt78and the bolt80, and penetrates the long hole6awithout contacting an inner circumferential surface of the long hole6a. When the user rotates the adjustment screw92, the engaging pin86moves in the direction along the long hole6aof the guide bar6and the guide bar6thereby slides in the direction along the long hole6a.

As shown inFIG.7, the sprocket72is covered by the sprocket cover22. As shown inFIG.1, an outer cover94is arranged on a right surface of the sprocket cover22in the vicinity of its front end. The outer cover94includes a recess94athat is recessed leftward. The recess94aincludes fastening openings94b,94cfor accessing the nuts82,84fastened onto the bolts78,80from outside and an adjusting opening94dfor accessing the adjustment screw92from outside. The user can tighten or loosen the nuts82,84with the sprocket cover22attached. Further, the user can adjust the tension on the saw chain8by rotating the adjustment screw92through the adjusting opening94dwith the sprocket cover22attached.

As shown inFIG.7, a sleeve96is arranged on the sprocket cover22. The sleeve96is constituted of a metal material such as aluminum, and is configured integrally with the sprocket cover22by injection molding. The sleeve96includes bolt openings96a,96bthrough which the bolts78,80penetrate and an adjustment screw opening96cthrough which the adjustment screw92is inserted. When the nuts82,84are fastened onto the bolts78,80, the guide bar6and the sleeve96are held and fixed between the nuts82,84and the base plate14a. Since a load applied to the sprocket cover22upon fastening the nuts82,84is received by the sleeve96, the sprocket cover22can be prevented from being damaged even when the nuts82,84are firmly tightened.

As shown inFIG.12, chain guides98,100are arranged on the right surface of the base plate14a. As shown inFIG.11, the chain guide98is arranged above the bolts78,80and the adjustment screw92. The chain guide100is arranged below the bolt78and the adjustment screw92. The chain guides98,100are constituted of a resin material such as polyacetal resin. As shown inFIG.13, a chain passage99through which the saw chain8(seeFIGS.1to3) passes is defined between the body housing24and the sprocket cover22. By having the chain guide98, the saw chain8(seeFIGS.1to3) passing through the chain passage99above the guide bar6can be suppressed from being tilted leftward and detached from the guide bar6. Further, during the cutting work using the chainsaw2, cutting chips may enter into the chain passage99as the saw chain8rotates, however, the presence of the chain guide98decreases a passage area of the chain passage99above the guide bar6, by which the cutting chips can be suppressed from entering deep into the chain passage99. Further, the presence of the chain guide100can suppress the saw chain8(seeFIGS.1to3) passing through the chain passage99below the guide bar6from being tilted leftward and detached from the guide bar6.

As shown inFIG.12, the chain guide98includes a substantially flat plate-shaped guiding part98aand engaging parts98bprotruding leftward from the guiding part98a. The chain guide100includes a substantially flat plate-shaped guiding part100aand engaging parts100bprotruding leftward from the guiding part100a. A guide attaching part102to which the chain guide98is detachably attached and a guide attaching part104to which the chain guide100is detachably attached are arranged on a right surface of the base plate14a. The guide attaching part102includes an attaching groove102aconfigured to receive the guiding part98aand engagement receiving parts102bto which the engaging parts98bare to be engaged. The guide attaching part104includes an attaching groove104aconfigured to receive the guiding part100aand engagement receiving parts104bto which the engaging parts100bare to be engaged. By configuring as such, even when the chain guides98,100are damaged due to contact with the saw chain8, work to replace them with new chain guides98,100can easily be performed.

A chain catcher106is fixed by a fastener below the guide attaching part104of the base plate14a. The chain catcher106is constituted of a metal material such as an aluminum alloy. Due to the presence of the chain catcher106, even if by chance the saw chain8is detached from the guide bar6while it is rotating, the saw chain8can be suppressed from flying off toward the user.

A spike108is fixed by fasteners to the front end of the base plate14a. The spike108is constituted of a metal material such as iron. As shown inFIGS.1and2, the spike108protrudes forward from the front surface of the body housing24. When an object such as wood is to be cut using the chainsaw2, the user can stab the object to be cut with the spike108and use it as a fulcrum to perform the cutting work with stability.

As shown inFIG.14, chain guides110,112are arranged on the left surface of the sprocket cover22. The chain guide110is arranged above the sleeve96. The chain guide112is arranged below sleeve96. The chain guides110,112are constituted of a resin material such as polyacetal resin. As shown inFIG.13, by having the chain guide110, the saw chain8passing through the chain passage99above the guide bar6can be suppressed from being tilted rightward and detached from the guide bar6. Further, the presence of the chain guide110decreases the passage area of the chain passage99above the guide bar6, by which the cutting chips can be suppressed from entering deep into the chain passage99. Further, the presence of the chain guide112can suppress the saw chain8passing through the chain passage99below the guide bar6from being tilted rightward and detached from the guide bar6.

As shown inFIG.15, the chain guide110includes a substantially flat plate-shaped guiding part110aand engaging parts110bprotruding rightward from the guiding part110a. The chain guide112includes a substantially flat plate-shaped guiding part112aand engaging parts112bprotruding rightward from the guiding part112a. As shown inFIG.16, a guide attaching part114to which the chain guide110is detachably attached and a guide attaching part116to which the chain guide112is detachably attached are arranged on a left surface of the sprocket cover22. The guide attaching part114includes an attaching groove114aconfigured to receive the guiding part110aand engagement receiving parts114bto which the engaging part110bsare to be engaged. The guide attaching part116includes an attaching groove116aconfigured to receive the guiding part112aand engagement receiving parts116bto which the engaging parts112bare to be engaged. By configuring as such, even when the chain guides110,112are damaged due to contact with the saw chain8, work to replace them with new chain guides110,112can easily be performed.

As shown inFIG.14, a chip guide118is further arranged on a left surface of the sprocket cover22. The chip guide118is constituted of a rubber material such as nitrile rubber. As shown inFIG.15, the chip guide118includes a first guiding part120, a second guiding part122, a third guiding part124, and a supporting part126. The first guiding part120, the second guiding part122, the third guiding part124, and the supporting part126are seamlessly integrated. The first guiding part120includes a guiding surface120ahaving a substantially columnar surface shape. A curvature radius of the guiding surface120ais within a range of 24 mm to 36 mm, and may for example be 30 mm. The second guiding part122includes a guiding surface122ahaving a substantially columnar surface shape and a guiding surface122bhaving a substantially flat surface shape. A curvature radius of the guiding surface122ais within a range of 4 mm to 10 mm, and may for example be 6 mm A longitudinal length of the guiding surface122bis within a range of 30 mm to 40 mm, and may for example be 34 mm. The guiding surface122ais connected to the guiding surface120aat its one end and is connected to the guiding surface122bat its other end. The third guiding part124includes a guiding surface124ahaving a substantially columnar shape and a guiding surface124bhaving a substantially flat surface shape. A curvature radius of the guiding surface124ais within a range of 3 mm to 7 mm, and may for example be 5 mm A longitudinal length of the guiding surface124bis within a range of 14 mm to 25 mm, and may for example be 18 mm. The guiding surface124ais connected to the guiding surface122bat its one end and is connected to the guiding surface124bat its other end. The supporting part126includes engaging holes126a,126b,126c. As shown inFIG.16, a guide attaching part128to which the chip guide118is to be detachably attached is arranged on the left surface of the sprocket cover22. The guide attaching part128includes engaging pins128a,128b,128cconfigured to engage with the engaging holes126a,126b,126c. By configuring as such, even when the chip guide118is damaged due to contact with the saw chain8, work to replace it with a new chip guide118can easily be performed. As shown inFIG.14, a substantially flat plate-shaped guide rib22aprotruding leftward is arranged on the left surface of the sprocket cover22. When the chip guide118is attached to the sprocket cover22, a lower surface of the guide rib22aand the guiding surface120aare arranged substantially flush with substantially no gap in between.

As shown inFIG.17, when the sprocket cover22is arranged on the body housing24, the guide rib22ais arranged on the front upper side of the sprocket72, the first guiding part120is arranged on the rear upper side of the sprocket72, and the second guiding part122and the third guiding part124are arranged on the rear lower side of the sprocket72. When the chainsaw2is seen from the right, a center C1of a curvature circle of the guiding surface120aof the first guiding part120substantially coincides with a center C0of the output shaft60. When the chainsaw2is seen from the right, a center C2of a curvature circle of the guiding surface122aof the second guiding part122is offset to the rear lower side from the center C1of the curvature circle of the guiding surface120aof the first guiding part120. An amount of this rearward offset of the center C2of the curvature circle of the guiding surface122afrom the center C1of the curvature circle of the guiding surface120ais in a range of 24 mm to 38 mm, and may for example be 31 mm. When the chainsaw2is seen from the right, an angle θ1formed by a horizontal plane H and a line L1connecting a connection point P1of the guiding surface120aand the guiding surface122awith the center C0of the output shaft60is in a range of −10 degrees≤θ1≤25 degrees. Here, θ1is positive when P1is located below C0, and is negative when P1is located above C0. For example, in this embodiment, θ1is 6 degrees. When the chainsaw2is seen from the right, a center C3of a curvature circle of the guiding surface124aof the third guiding part124is offset to the rear lower side from the center C2of the curvature circle of the guiding surface122aof the second guiding part122. An amount of this rearward offset of the center C3of the curvature circle of the guiding surface124afrom the center C2of the curvature circle of the guiding surface122ais in a range of 10 mm to 30 mm, and may for example be 19 mm. When the chainsaw2is seen from the right, an angle θ2formed by the horizontal plane H and a line L2connecting a connection point P2of the guiding surface122aand the guiding surface124awith the center C0of the output shaft60is in a range of 32 degrees≤θ2≤50 degrees. Here, θ2is positive when P2is located below C0, and is negative when P2is located above C0. For example, in this embodiment, θ2is 41 degrees.

By having the guide rib22aarranged as above, the passage area of the chain passage99on the front upper side of the sprocket72can be decreased, by which the cutting chips can be suppressed from entering deep into the chain passage99. Further, by having the first guiding part120arranged as above, the passage area of the chain passage99on the rear upper side of the sprocket72can be decreased, by which the cutting chips can be suppressed from entering deep into the chain passage99. Moreover, by having the second guiding part122arranged as above, the cutting chips that entered into the chain passage99can easily be discarded toward the rear lower side. By having the third guiding part124arranged as above, the cutting chips that entered into the chain passage99can easily be discarded toward the rear lower side.

As shown inFIG.1, the front hand guard18includes a guard part18a, a left supporting part18b, and a right supporting part18c. As shown inFIG.5, the guard part18ais arranged in front of the upper holding part16bof the front handle16, and is configured to protect the hand of the user holding the upper holding part16b. As shown inFIG.2, the left supporting part18bextends rearward and downward from the left lower end of the guard part18a. The left supporting part18bis held at the vicinity of its lower end by the left housing10such that it is rotatable about a rotation shaft18d(seeFIG.8) extending in the left-right direction. As shown inFIG.11, the right supporting part18cextends downward from the right end of the guard part18a. The right supporting part18cis held at the vicinity of its lower end by the base plate14asuch that it is rotatable about a rotation shaft18eextending in the left-right direction. The rotation shaft18d(seeFIG.8) and the rotation shaft18eare arranged substantially colinear. Due to this, the front hand guard18is configured to rotate between a normal position at which it is pulled upward relative to the body housing24and a stop position at which it is pressed down forward. As shown inFIG.8, a stop detection switch129is arranged on the left surface of the base plate14a. The stop detection switch129is configured to detect whether the front hand guard18is in the stop position. The stop detection switch129is electrically connected to the control unit34(seeFIG.6).

As shown inFIG.11, the right surface of the base plate14aincludes a lock member130and a compression spring132. The lock member130includes a protrusion130athat enters into a recess18fdefined in the right supporting part18cof the front hand guard18. The compression spring132biases the lock member130with respect to the base plate14ain a direction along which the protrusion130aenters into the recess18f. Due to this, even if a force in a direction pressing down the front hand guard18forward is applied to the front hand guard18, a state in which the protrusion130ais within the recess18fis maintained by a biasing force of the compression spring132so long as the force is smaller than a predetermined value, as a result of which the front hand guard18is maintained in the normal position. On the other hand, if the force is greater than the predetermined value, the protrusion130aexits the recess18fagainst the biasing force of the compression spring132, and the front hand guard18thereby rotates from the normal position to the stop position.

The right surface of the base plate14afurther includes an arm member134, a link member136, a brake member138, a brake band140, and a compression spring142. One end of the arm member134is fixed to the right supporting part18cof the front hand guard18. The other end of the arm member134is rotatably connected to one end of the link member136. The other end of the link member136is rotatably connected to the brake member138. The brake member138is held by the base plate14asuch that it is slidable between a normal position on the rear lower side and a stop position on the front upper side. The brake band140is arranged to surround a periphery of the brake drum76. One end of the brake band140is held by the brake member138. The other end of the brake band140is fixed to the base plate14a. When the front hand guard18rotates from the normal position to the stop position, the arm member134also rotates together with the front hand guard18, by which the arm member134and the link member136enter a state of being inclined relative to one another, and the brake member138moves from the normal position to the stop position. Due to this, the brake band140decreases its diameter, by which an inner circumferential surface of the brake band140comes into contact with an outer circumferential surface of the brake drum76, and the rotation of the output shaft60is braked by a frictional force between them. When the front hand guard18rotates from the stop position to the normal position, the arm member134also rotates with the front hand guard18, by which the arm member134and the link member136enter a state of being arranged substantially colinear, and the brake member138thereby moves from the stop position to the normal position. Due to this, the brake band140increases its diameter, by which the inner circumferential surface of the brake band140separates from the outer circumferential surface of the brake drum76, and the brake on the rotation of the output shaft60is thereby released.

The compression spring142biases the brake member138from the normal position toward the stop position. When the front hand guard18is in the normal position and the arm member134and the link member136are arranged substantially colinear, the brake member138is maintained in the normal position even if a biasing force of the compression spring142is applied to the brake member138. However, when an impact is applied to the chainsaw2by a kickback motion during the cutting work, the arm member134and the link member136are slightly inclined relative to one another, and the brake member138moves from the normal position to the stop position by the biasing force of the compression spring142. Due to this, the front hand guard18rotates from the normal position to the stop position, and also the rotation of the output shaft60is braked by the frictional force of the brake band140and the brake drum76.

The oil tank48shown inFIG.6stores lubricant oil for lubricating the saw chain8. The oil tank48has a cap144to be detachably attached to a refill opening48a(seeFIG.7) for refiling the lubricant oil in the oil tank48. As shown inFIG.2, the cap144of the oil tank48is exposed outside of the left housing10, and is arranged on the front left surface of the body housing24.

The oil pump50shown inFIG.6is configured to suction the lubricant oil in the oil tank48through an inlet tube146and feeds out the lubricant oil toward the guide bar6through an outlet tube148in conjunction with the rotation of the motor46. The lubricant oil fed to the outlet tube148is supplied to the guide bar6and the saw chain8(seeFIGS.1to3) via an oil supply port14d(seeFIG.11) defined in the base plate14a. A worm gear150for driving the oil pump50is fitted in in the vicinity of the left end of the output shaft60of the motor46. As shown inFIG.7, the worm gear150is arranged to the left of the bearing70. A discharge amount of the lubricant oil supplied from the oil tank48to the guide bar6by the oil pump50can be adjusted using an adjustment pin152(seeFIG.8).

As shown inFIG.2, an adjusting opening24hthrough which the adjustment pin152can be accessed from outside is defined in the lower surface of the body housing24(specifically, the lower surface of the left housing10). The user can rotate the adjustment pin152by inserting a tool through the adjusting opening24hto adjust the amount of the lubricant oil discharged from the oil pump50. In the left-right direction of the chainsaw2, the adjusting opening24his arranged in the vicinity of the left end of the body housing24.

A water draining hole24icommunicating with the battery pack receptacle24a(FIG.4) is defined in the lower surface of the body housing24(specifically, the lower surface of the left housing10). Due to this, even when water enters into the battery pack receptacle24a, it can be drained through the water draining hole24i. Further, as shown inFIG.18, a water draining hole24jcommunicating with inside of the body housing24is defined in the right handle attaching groove24dof the body housing24. Due to this, even when water enters into the body housing24, it can be drained through the water draining hole24jby tilting down the chainsaw2to the right. Further, since the water draining hole24jis arranged at a position that is not noticeable, thus will not deteriorate aesthetics of the chainsaw2. Further, since the water draining hole24jis arranged at a position remotely separated from the guide bar6, the cutting chips can be suppressed from entering into the body housing24through the water draining hole24j.

In the chainsaw2of the present embodiment, a volume of the base member14is 400 cm3or more, may for example be 500 cm3or more, and may for example be about 550 cm3. Further, a weight of the base member14is 2% or more of an entire weight of the chainsaw2including the guide bar6, the saw chain8, and the battery pack B, may for example be 3% or more, and may for example be about 4%. By using the base member14that is large-sized and heavy, a heat capacity of the base member14can be increased, and thus a temperature rise in the base member14can be suppressed.

In the chainsaw2of the present embodiment, a space in which the motor46is housed and a space through which the saw chain8passes are separated by the base member14. By configuring as such, the cutting chips can be suppressed from reaching the motor46and adversely affecting the operation of the motor46.

(Variants)

The chainsaw2may not be equipped with the battery pack B, and may be supplied with electric power through a power cable.

The motor46may be an outer rotor DC brushless motor. Alternatively, the motor46may be a brush motor or another type of electric motor.

The chainsaw2may include an engine with an internal combustion mechanism instead of the motor46as its prime mover for rotating the sprocket72. In this case, the output shaft60connected to the sprocket72may be rotated by actuation of the engine.

The material of the base member14is not limited to a magnesium alloy, and may be any heat conductive material with thermal conductivity of 10 W/mK or more when the temperature of the material is 300K, and may for example be a metal material such as austenite-based stainless steel or a nonmetal material.

The chip guide118may be arranged detachably on the right surface of the body housing24(specifically, the right surface of the brake cover20) instead of the left surface of the sprocket cover22. Further, the chip guide118may not include the third guiding part124. Further, in the chip guide118, the first guiding part120, the second guiding part122, and the third guiding part124may be configured as separate components, each of which may be configured to be detachably attached to the sprocket cover22or the body housing24independent from one another.

As above, in one or more embodiments, the chainsaw2comprises: the saw chain8; the guide bar6equipped with the saw chain8; the sprocket72for running the saw chain8along the periphery of the guide bar6; the motor46(example of prime mover) configured to rotate the sprocket72about the rotation axis C0; the body housing24(example of housing) for housing the motor46; the sprocket cover22for covering the sprocket72; and the chip guide118(example of guide member). The guide bar6, the body housing24, and the sprocket cover22define the chain passage99, the saw chain8passing through the chain passage99. The chip guide118includes: the guiding surface120a(example of first facing surface) arranged such that the guiding surface120afaces the saw chain8in the chain passage99, the guiding surface120ahaving the arc shape centered on the rotation axis C0when viewed in the direction along the rotation axis C0(such as the left-right direction); and the guiding surface122a(example of second facing surface) arranged such that the guiding surface122afaces the saw chain8in the chain passage99, the guiding surface122ahaving the arc shape centered on the position C2offset from the rotation axis C0when viewed in the direction along the rotation axis C0(such as the left-right direction). When the chainsaw2is placed on the horizontal mounting surface S and viewed in the direction along the rotation axis C0(such as the left-right direction), the angle between (i) the straight line L1connecting the rotation axis C0and the position P1where the guiding surface120aand the guiding surface122aare connected and (ii) the horizontal plane H is in the range of −10° to 25°.

According to the above configuration, since the passage area of the chain passage99is reduced at the position P1where the guiding surface120aand the guiding surface122aof the chip guide118are connected, the cutting chips can be suppressed from advancing deep into the chain passage99. Further, according to the above configuration, the cutting chips that were prohibited from advancing deep into the chain passage99is discharged along the guiding surface122ahaving the arc shape, thus the cutting chips can be suppressed from being accumulated in the chain passage99. Further, according to the above configuration, since the angle between (i) the straight line L1connecting the rotation axis C0and the position P1where the guiding surface120aand the guiding surface122aare connected and (ii) the horizontal plane H is in the range of −10° to 25° when the chainsaw2is placed on the horizontal mounting surface S and viewed in the direction along the rotation axis C0(such as the left-right direction), the cutting chips that were prohibited from advancing deep into the chain passage99can easily be discharged downward by a gravitational force.

In one or more embodiments, the chip guide118includes the first guiding part120(example of first guide member) having the guiding surface120aand constituted of the rubber material. The first guiding part120is detachably attached to the body housing24or the sprocket cover22.

According to the above configuration, even when the saw chain8collides with the guiding surface120a, the first guiding part120absorbs an impact thereof, thus the body housing24and the sprocket cover22can be suppressed from being damaged. Further, according to the above configuration, even when the first guiding part120is damaged, it can easily be replaced with a new first guiding part120.

In one or more embodiments, when the chainsaw2is placed on the mounting surface S and viewed in the direction along the rotation axis C0(such as the left-right direction), the guiding surface120areaches vertically above the rotation axis C0.

According to the above configuration, since a large area of the chain passage99can be covered by the guiding surface120a, the body housing24and the sprocket cover22can further be ensured to be protected from damages caused by collision with the saw chain8.

In one or more embodiments, the chip guide118further includes the second guiding part122(example of second guide member) having the guiding surface122aand constituted of the rubber material. The second guiding part122is detachably attached to the body housing24or the sprocket cover22.

According to the above configuration, even when the saw chain8collides with the guiding surface122a, the second guiding part122absorbs an impact thereof, thus the body housing24and the sprocket cover22can be suppressed from being damaged. Further, according to the above configuration, even when the second guiding part122is damaged, it can easily be replaced with a new second guiding part122.

In one or more embodiments, the first guiding part120and the second guiding part122are formed seamlessly and integrally.

According to the above configuration, the number of components of the chainsaw2can be reduced.

In one or more embodiments, the curvature radius of the guiding surface122ais equal to or less than half the curvature radius of the guiding surface120a.

When the curvature radius of the guiding surface122abecomes larger, the size of the chainsaw2in the longitudinal direction of the guide bar6must be increased accordingly. According to the above configuration, the size of the chainsaw2in the longitudinal direction of the guide bar6can be made compact.