Chainsaw

Abstract

To provide a technique for a chain saw capable of preventing an outer shell part from being high temperature due to heat transmission from a guide bar.SOLUTION: The specification discloses a chain saw. The chain saw may be provided with: a saw chain; a guide bar on which the saw chain is attached; a sprocket making the saw chain travel along the circumference of the guide bar; a motor provided with an output shaft connected with the sprocket; a cooling fan connected on the output shaft; and a base member holding the guide bar. The base member may be made from heat conductive material with a heat conductivity equal to 10 W / m K or more when the temperature is at 300K. The base member may be provided with a plate part placed opposite to the motor in a direction along the output shaft and a lib part projecting from the plate part to the motor side.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The technology disclosed in this specification relates to a chainsaw.

Background Art

[0002] Patent Document 1 discloses a chainsaw. The chainsaw includes a saw chain, a guide bar to which the saw chain is attached, a sprocket that runs the saw chain along the periphery of the guide bar, a motor having an output shaft connected to the sprocket, a cooling fan connected to the output shaft, and a base member that holds the guide bar. The base member includes a plate portion disposed opposite to the motor in a direction along the output shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When cutting an object to be cut using a chainsaw, the temperature of the guide bar rises due to the frictional heat between the saw chain and the guide bar. If the guide bar becomes excessively hot, there is a risk that the outer shell portion exposed to the outside in the base member and its neighboring members becomes hot due to heat transfer from the guide bar, and there is a risk that a user may accidentally touch the hot outer shell portion. In this specification, a technology capable of suppressing the outer shell portion from becoming hot due to heat transfer from the guide bar in a chainsaw is provided.

Means for Solving the Problems

[0005] This specification discloses a chainsaw. The chainsaw includes a saw chain, a guide bar to which the saw chain is attached, a sprocket that runs the saw chain along the periphery of the guide bar, a motor having an output shaft connected to the sprocket, a cooling fan connected to the output shaft, and a base member that holds the guide bar. The base member may be made of a heat conductive material having a thermal conductivity of 10 W / m·K or more at a temperature of 300 K. The base member may include a plate portion disposed opposite to the motor in a direction along the output shaft, and a rib portion protruding from the plate portion toward the motor side.

[0006] In the above configuration, since the thermal conductivity of the base member is high, when the temperature of the guide bar rises, heat is transferred from the guide bar to the base member. And in the above configuration, when the motor is driven, the cooling air by the cooling fan cools the plate portion and the rib portion of the base member, so that heat can be efficiently dissipated from the base member. For this reason, according to the above configuration, it is possible to suppress the outer shell portion of the base member and the members in its vicinity from becoming high temperature due to heat transfer from the guide bar.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

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Figure 8

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Embodiments for Carrying Out the Invention

[0008] Hereinafter, representative and non-limiting specific examples of the present invention will be described in detail with reference to the drawings. This detailed description is merely intended to show those skilled in the art the details for implementing preferred examples of the present invention, and is not intended to limit the scope of the present invention. Further, the additional features and inventions disclosed below can be used separately or together with other features and inventions in order to provide an improved chainsaw, its manufacturing method, and its usage method.

[0009] Also, the combinations of features and steps disclosed in the following detailed description are not essential for implementing the present invention in the broadest sense, and are described only for the purpose of explaining representative specific examples of the present invention in particular. Further, the various features of the above and below representative specific examples, as well as the various features described in the independent and dependent claims, do not have to be combined as described in the specific examples here or in the order listed when providing additional and useful embodiments of the present invention.

[0010] All features described in this specification and / or the claims are intended to be disclosed separately and independently of each other, as limitations on the initial disclosure and the claimed specific matters, apart from the configurations of the features described in the examples and / or the claims. Further, all descriptions regarding numerical ranges and groups or populations are made with the intention of disclosing intermediate configurations as limitations on the initial disclosure and the claimed specific matters.

[0011] In one or more embodiments, the chainsaw may include a saw chain, a guide bar to which the saw chain is attached, a sprocket that runs the saw chain along the periphery of the guide bar, a motor having an output shaft connected to the sprocket, a cooling fan connected to the output shaft, and a base member that holds the guide bar. The base member may be made of a heat-conductive material having a thermal conductivity of 10 W / m·K or more at a temperature of 300 K. The base member may include a plate portion disposed opposite the motor in a direction along the output shaft, and a rib portion protruding from the plate portion toward the motor side.

[0012] In the above configuration, since the thermal conductivity of the base member is high, when the temperature of the guide bar rises, heat is transferred from the guide bar to the base member. And in the above configuration, when the motor is driven, the cooling air from the cooling fan cools the plate portion and the rib portion of the base member, so that heat can be efficiently dissipated from the base member. Therefore, according to the above configuration, it is possible to suppress the outer shell portion of the base member and the members in its vicinity from becoming high temperature due to heat transfer from the guide bar.

[0013] In one or more embodiments, the cooling fan may be a centrifugal fan. The cooling fan may be disposed between the motor and the plate portion. The rib portion may be disposed so as to surround the radially outer side of the cooling fan.

[0014] According to the above configuration, the cooling efficiency of the base member by the cooling fan can be further enhanced.

[0015] In one or more embodiments, the heat-conductive material may be a magnesium alloy.

[0016] According to the above configuration, it is possible to realize a lightweight base member with high thermal conductivity while ensuring the required rigidity and strength of the base member.

[0017] (Example) As shown in FIGS. 1 and 2, the chainsaw 2 of this embodiment includes a main body 4, a guide bar 6, and a saw chain 8. The guide bar 6 is an elongated plate-shaped member attached to the main body 4 so as to protrude forward from the main body 4. The guide bar 6 is made of a metal material such as iron, for example. The saw chain 8 includes a plurality of cutters connected to each other and is attached along the peripheral edge of the guide bar 6. A battery pack B is attached to the main body 4. The chainsaw 2 cuts a workpiece such as wood by rotationally driving the saw chain 8 along the peripheral edge of the guide bar 6 by the power supplied from the battery pack B. Various guide bars 6 can be attached according to the content of the cutting work. In the example shown in FIGS. 1 and 2, the radius of curvature of the tip of the guide bar 6 is, for example, 10 mm. The chainsaw 2 of this embodiment rotationally drives the saw chain 8 along the peripheral edge of the guide bar 6 at a speed of, for example, 25.5 m / s. In the following description, as shown in FIG. 3, when the chainsaw 2 is placed on a horizontal placement surface S such as the ground, the direction perpendicular to the placement surface S is referred to as the vertical direction of the chainsaw 2, the direction in which the longitudinal direction of the guide bar 6 is projected onto the placement surface S is referred to as the front-rear direction of the chainsaw 2, and the direction perpendicular to the vertical direction and the front-rear direction of the chainsaw 2 is referred to as the left-right direction of the chainsaw 2. In the drawings other than FIGS. 1-3, the illustration of the saw chain 8 is omitted for clarity of illustration.

[0018] As shown in FIGS. 1 and 2, the main body 4 includes a left housing 10, a right housing 12, a base member 14, a front handle 16, a front hand guard 18, a brake cover 20, and a sprocket cover 22. The left housing 10, the right housing 12, the front hand guard 18, the brake cover 20, and the sprocket cover 22 are made of a resin material such as polyamide resin, for example. The base member 14 is made of a metal material such as a magnesium alloy, for example. The thermal conductivity of the base member 14 is, for example, 10 W / m·K or more, for example 30 W / m·K or more, for example about 50 W / m·K when the temperature is 300 K. The front handle 16 is made of a metal material such as an aluminum alloy, for example.

[0019] The main body 4 is formed with a main body housing 24, a rear handle 26, and a rear hand guard 28. The main body housing 24 is composed of a left housing 10, a right housing 12, a base member 14, and a brake cover 20. The rear handle 26 and the rear hand guard 28 are composed of the left housing 10 and the right housing 12. The base member 14 is attached to the right side of the front portion of the right housing 12. The brake cover 20 is attached to the right side of the base member 14. The sprocket cover 22 is attached to the right side of the brake cover 20.

[0020] The main body housing 24 has a substantially rectangular parallelepiped shape with a longitudinal direction in the front-rear direction of the main body 4. As shown in FIG. 4, a battery pack accommodation portion 24a that opens upward is formed at the rear portion of the main body housing 24. A battery pack attachment portion 24b for detachably attaching the battery pack B by sliding the battery pack B in the vertical direction is provided on the right inner surface of the battery pack accommodation portion 24a. A recess 24c is formed at the upper end of the right inner surface of the battery pack accommodation portion 24a so that the user can easily grip the battery pack B when attaching and detaching the battery pack B.

[0021] The rear handle 26 extends from the upper part of the rear surface of the main body housing 24 downward and rearward, and bends downward. The rear handle 26 has a substantially circular cross-sectional shape. The rear hand guard 28 extends rearward from the lower part of the rear surface of the main body housing 24 and is connected to the lower end of the rear handle 26. The rear hand guard 28 has a substantially rectangular parallelepiped shape with a smaller dimension in the left-right direction than in the front-rear direction and a smaller dimension in the vertical direction than in the left-right direction. As shown in FIG. 5, the rear hand guard 28 has a shape that covers the entire rear handle 26 from below. The rear hand guard 28 includes a first guard portion 28a disposed directly below the rear handle 26 and a second guard portion 28b extending rightward from the first guard portion 28a. The rear hand guard 28 can protect the hand of the user who grips the rear handle 26.

[0022] On the upper surface near the front end of the rear handle 26, a power button 30 is arranged for the user to switch the power of the chainsaw 2 on and off. As shown in FIG. 6, inside the rear handle 26, a power switch 32 for detecting an operation by the user on the power button 30 is provided. The power switch 32 is electrically connected to a control unit 34 described later.

[0023] On the lower surface near the front end of the rear handle 26, a trigger lever 36 for the user to operate the rotational drive of the saw chain 8 is arranged. The trigger lever 36 is supported by the rear handle 26 so as to be rotatable around a rotation axis 36a extending in the left - right direction. Inside the rear end vicinity of the main body housing 24, a trigger switch 38 for detecting a pulling - up operation of the trigger lever 36 by the user is provided. The trigger switch 38 is electrically connected to the control unit 34.

[0024] On the upper surface of the rear handle 26, a lock lever 40 is arranged which switches between a state of permitting and a state of prohibiting the operation of the trigger lever 36 by the user. The lock lever 40 is supported by the rear handle 26 so as to be rotatable around a rotation axis 40a extending in the left - right direction. In a state where the lock lever 40 rotates upward, the lock lever 40 interferes with the trigger lever 36, thereby prohibiting the upward rotation of the trigger lever 36. In a state where the lock lever 40 rotates downward, the lock lever 40 no longer interferes with the trigger lever 36, and the upward rotation of the trigger lever 36 is permitted. Inside the rear handle 26 near the front end, a grip detection switch 42 for detecting a pressing - down operation of the lock lever 40 by the user is arranged. The grip detection switch 42 is electrically connected to the control unit 34.

[0025] The trigger lever 36 and the lock lever 40 are connected to each other by a torsion spring 44. The torsion spring 44 biases the trigger lever 36 in a direction to rotate downward and biases the lock lever 40 in a direction to rotate upward. Therefore, when the user releases the trigger lever 36, the trigger lever 36 is in a state of rotating downward by the biasing force of the torsion spring 44. Also, when the user releases the lock lever 40, the lock lever 40 is in a state of rotating upward by the biasing force of the torsion spring 44.

[0026] As shown in FIGS. 1 and 2, the front handle 16 includes a right fixed portion 16a extending forward and upward, an upper grip portion 16b extending leftward and forward from the upper end of the right fixed portion 16a, a left grip portion 16c extending downward from the left end of the upper grip portion 16b, and a lower fixed portion 16d extending rightward from the lower end of the left grip portion 16c. The upper grip portion 16b and the left grip portion 16c have a substantially circular cross-sectional shape. As shown in FIG. 1, the right fixed portion 16a is fixed to the main body housing 24 (specifically, the right housing 12) by a fastener in a state of being inserted into a right handle mounting groove 24d formed in the right surface of the main body housing 24 (specifically, the right surface of the right housing 12). As shown in FIG. 2, the lower fixed portion 16d is fixed to the main body housing 24 (specifically, the left housing 10) by a fastener in a state of being inserted into a lower handle mounting groove 24e formed in the lower surface near the front end of the main body housing 24 (specifically, the lower surface of the left housing 10).

[0027] When using the chainsaw 2, the user holds the rear handle 26 with the right hand and holds the front handle 16 (specifically, the upper grip portion 16b or the left grip portion 16c) with the left hand to hold the chainsaw 2. From this state, when the user presses down the lock lever 40 of the rear handle 26 with the palm of the right hand, the operation of the trigger lever 36 by the user is permitted. In this state, when the user pulls up the trigger lever 36 with the index finger of the right hand, the saw chain 8 is rotationally driven.

[0028] As shown in FIG. 6, a control unit 34, a motor 46, an oil tank 48, and an oil pump 50 are arranged in the front of the interior of the main body housing 24. The control unit 34, the motor 46, the oil tank 48, and the oil pump 50 are arranged in front of the battery pack B. The oil tank 48 is arranged in front of the motor 46 and the oil pump 50. The control unit 34 is arranged above the motor 46, the oil tank 48, and the oil pump 50 and is arranged along the front-rear direction and the left-right direction.

[0029] As shown in FIG. 7, the motor 46 is an inner rotor type DC brushless motor. The motor 46 includes a stator 54 around which a coil 52 is wound, a rotor 58 arranged inside the stator 54 and having a permanent magnet 56, an output shaft 60 arranged so as to penetrate the centers of the stator 54 and the rotor 58 and fitted to the rotor 58, a cooling fan 62 fitted to the output shaft 60, and a sensor board 64 for detecting the rotation of the rotor 58.

[0030] The base member 14 includes a base plate 14a extending in the front-rear direction and the up-down direction, and a substantially cylindrical support rib 14b protruding leftward from the base plate 14a. The base plate 14a and the support rib 14b are integrally formed without a joint. As shown in FIG. 8, a motor case 66 is fixed to the left end of the support rib 14b via a fastener. The motor case 66 is made of a resin material such as polyamide resin, for example. As shown in FIG. 7, the sensor substrate 64 is disposed to face the left end face of the stator 54. The motor case 66 has a shape that covers the outer side in the radial direction of the stator 54, the left end face of the stator 54, and the sensor substrate 64. The stator 54 and the sensor substrate 64 are fixed to the motor case 66 via fasteners. The coil 52 wound around the stator 54 and the sensor substrate 64 are each electrically connected to a control unit 34 (see FIG. 6). Although not shown, the control unit 34 includes an inverter circuit including a switching element and a circuit board mounted with a control circuit for controlling the operation of each switching element, and a substantially rectangular parallelepiped casing for housing the circuit board. The control unit 34 controls the operation of the motor 46 by controlling the voltage applied to the coil 52 based on the detection signal of the sensor substrate 64.

[0031] As shown in FIG. 7, the output shaft 60 is disposed along the left-right direction of the chainsaw 2. The right end of the output shaft 60 penetrates the right housing 12, the base plate 14a, and the brake cover 20 and protrudes to the right side of the brake cover 20. The left end of the output shaft 60 penetrates the left surface of the motor case 66 and protrudes to the left side of the left surface of the motor case 66. The output shaft 60 is rotatably supported by the base plate 14a via a bearing 68 and is rotatably supported by the motor case 66 via a bearing 70. The rotor 58 is disposed on the right side of the bearing 70, the cooling fan 62 is disposed on the right side of the rotor 58, and the bearing 68 is disposed on the right side of the cooling fan 62.

[0032] The cooling fan 62 is, for example, a centrifugal fan, and is a plate fan including, for example, a disk-shaped plate 62a and a plurality of blades 62b protruding from the plate 62a. As shown in FIG. 8, an air supply opening 66a is formed in the left surface of the motor case 66. An exhaust opening 14c is formed in the support rib 14b of the base member 14. Further, as shown in FIG. 2, an air supply port 24f is formed in the left surface of the main body housing 24 (specifically, the left surface of the left housing 10), and an exhaust port 24g is formed in the lower surface of the main body housing 24 (specifically, the lower surface of the right housing 12). As shown in FIG. 9, the exhaust port 24g is disposed to face the exhaust opening 14c.

[0033] When the cooling fan 62 rotates, the air outside the main body housing 24 flows into the main body housing 24 through the air supply port 24f shown in FIG. 2. The air flowing into the main body housing 24 flows into the motor case 66 through the air supply opening 66a shown in FIG. 7. The air flowing into the motor case 66 passes through the sensor board 64, flows through the gap between the stator 54 and the rotor 58, cools the stator 54 and the rotor 58, and then reaches the cooling fan 62. As shown in FIG. 9, the air reaching the cooling fan 62 flows radially outward along the blade 62b, then flows circumferentially along the inner surface of the support rib 14b, cools the base member 14, and then flows out to the outside of the main body housing 24 through the exhaust opening 14c and the exhaust port 24g.

[0034] As shown in FIG. 7, a sprocket 72 and a brake base 74 are fixed near the right end of the output shaft 60. The sprocket 72 and the brake base 74 are disposed on the right side of the bearing 68. A brake drum 76 is fitted to the brake base 74.

[0035] As shown in FIG. 10, the sprocket 72 is exposed outside the brake cover 20. The guide chain 8 (see FIGS. 1-3) is strung from the guide bar 6 over the sprocket 72. When the motor 46 (see FIG. 7) is driven, the sprocket 72 rotates together with the output shaft 60, and thereby the guide chain 8 rotates around the sprocket 72 and the guide bar 6.

[0036] A long hole 6a is formed in the guide bar 6 along the longitudinal direction of the guide bar 6. The guide bar 6 is supported by the base member 14 via bolts 78 and 80 passing through the long hole 6a. As shown in FIG. 7, the bolts 78 and 80 are fixed to the base plate 14a. Nuts 82 and 84 are fastened to the bolts 78 and 80 from the outside of the sprocket cover 22. The user can adjust the tension of the guide chain 8 by sliding the guide bar 6 along the long hole 6a with the nuts 82 and 84 loosened to change the distance between the guide bar 6 and the sprocket 72.

[0037] As shown in FIG. 10, an engagement hole 88 for engaging with the engagement pin 86 is formed in the guide bar 6. As shown in FIG. 11, the engagement pin 86 is connected to the adjustment screw 92 via a rotation-linear motion conversion mechanism 90. The rotation-linear motion conversion mechanism 90 converts the rotational motion of the adjustment screw 92 into a linear motion in the direction along the long hole 6a of the engagement pin 86. As shown in FIG. 10, the adjustment screw 92 is disposed between the bolt 78 and the bolt 80 and passes through the long hole 6a without contacting the inner peripheral surface of the long hole 6a. When the user rotates the adjustment screw 92, the engagement pin 86 moves in the direction along the long hole 6a of the guide bar 6, and the guide bar 6 slides in the direction along the long hole 6a.

[0038] As shown in FIG. 7, the sprocket 72 is covered by a sprocket cover 22. As shown in FIG. 1, an outer cover 94 is attached to the right surface near the front end of the sprocket cover 22. The outer cover 94 is provided with a recess 94a that is recessed toward the left. In the recess 94a, fastening openings 94b and 94c for externally accessing nuts 82 and 84 fastened to bolts 78 and 80, and an adjustment opening 94d for externally accessing the adjustment screw 92 are formed. The user can tighten or loosen the nuts 82 and 84 with the sprocket cover 22 attached. Also, the user can adjust the tension of the saw chain 8 by rotating the adjustment screw 92 through the adjustment opening 94d with the sprocket cover 22 attached.

[0039] As shown in FIG. 7, a sleeve 96 is provided on the sprocket cover 22. The sleeve 96 is made of a metal material such as aluminum, for example, and is integrally formed with the sprocket cover 22 by injection molding. The sleeve 96 is provided with bolt openings 96a and 96b through which the bolts 78 and 80 pass, and an adjustment screw opening 96c into which the adjustment screw 92 is inserted. When the nuts 82 and 84 are fastened to the bolts 78 and 80, the guide bar 6 and the sleeve 96 are sandwiched and fixed between the nuts 82 and 84 and the base plate 14a. Since the sleeve 96 receives the load applied to the sprocket cover 22 when the nuts 82 and 84 are fastened, it is possible to prevent the sprocket cover 22 from being damaged even when the nuts 82 and 84 are firmly fastened.

[0040] As shown in Fig. 12, chain guides 98 and 100 are attached to the right surface of the base plate 14a. As shown in Fig. 11, the chain guide 98 is disposed above bolts 78 and 80 and adjusting screw 92. The chain guide 100 is disposed below bolts 78 and adjusting screw 92. The chain guides 98 and 100 are made of a resin material such as polyacetal resin. As shown in Fig. 13, a chain passage 99 through which the saw chain 8 (see Figs. 1 - 3) passes is formed between the main body housing 24 and the sprocket cover 22. By providing the chain guide 98, it is possible to prevent the saw chain 8 (see Figs. 1 - 3) passing through the chain passage 99 above the guide bar 6 from tilting to the left and coming off the guide bar 6. Further, during the cutting operation using the chain saw 2, chips may enter the chain passage 99 as the saw chain 8 rotates. However, by providing the chain guide 98, the passage area of the chain passage 99 above the guide bar 6 can be narrowed, and it is possible to prevent the chips from entering deep into the chain passage 99. Furthermore, by providing the chain guide 100, it is possible to prevent the saw chain 8 (see Figs. 1 - 3) passing through the chain passage 99 below the guide bar 6 from tilting to the left and coming off the guide bar 6.

[0041] As shown in Fig. 12, the chain guide 98 includes a guide portion 98a having a substantially flat plate shape and an engaging portion 98b protruding leftward from the guide portion 98a. The chain guide 100 includes a guide portion 100a having a substantially flat plate shape and an engaging portion 100b protruding leftward from the guide portion 100a. On the right surface of the base plate 14a, a guide attachment portion 102 to which the chain guide 98 is detachably attached and a guide attachment portion 104 to which the chain guide 100 is detachably attached are formed. The guide attachment portion 102 includes an attachment groove 102a for receiving the guide portion 98a and an engaged portion 102b with which the engaging portion 98b engages. The guide attachment portion 104 includes an attachment groove 104a for receiving the guide portion 100a and an engaged portion 104b with which the engaging portion 100b engages. With such a configuration, even when the chain guides 98 and 100 are damaged by contact with the saw chain 8, the replacement work for the new chain guides 98 and 100 can be easily performed.

[0042] Below the guide attachment portion 104 of the base plate 14a, a chain catcher 106 is fixed by a fastener. The chain catcher 106 is made of a metal material such as an aluminum alloy, for example. By providing the chain catcher 106, even if the rotating saw chain 8 comes off the guide bar 6 by any chance, it is possible to prevent the saw chain 8 from flying toward the user.

[0043] At the front end of the base plate 14a, a spike 108 is fixed by a fastener. The spike 108 is made of a metal material such as iron, for example. As shown in Figs. 1 and 2, the spike 108 protrudes forward from the front surface of the main body housing 24. When the user cuts a workpiece such as wood using the chainsaw 2, the user can stab the spike 108 into the workpiece to use it as a fulcrum, thereby performing the cutting operation stably.

[0044] As shown in FIG. 14, chain guides 110 and 112 are attached to the left surface of the sprocket cover 22. The chain guide 110 is disposed above the sleeve 96. The chain guide 112 is disposed below the sleeve 96. The chain guides 110 and 112 are made of a resin material such as polyacetal resin. As shown in FIG. 13, by providing the chain guide 110, it is possible to prevent the source chain 8 passing through the chain passage 99 above the guide bar 6 from tilting to the right and coming off the guide bar 6. Further, by providing the chain guide 110, the passage area of the chain passage 99 above the guide bar 6 can be narrowed, and it is possible to prevent chips from entering deep into the chain passage 99. Furthermore, by providing the chain guide 112, it is possible to prevent the source chain 8 passing through the chain passage 99 below the guide bar 6 from tilting to the right and coming off the guide bar 6.

[0045] As shown in FIG. 15, the chain guide 110 includes a guide portion 110a having a substantially flat plate shape and an engaging portion 110b protruding rightward from the guide portion 110a. The chain guide 112 includes a guide portion 112a having a substantially flat plate shape and an engaging portion 112b protruding rightward from the guide portion 112a. As shown in FIG. 16, on the left surface of the sprocket cover 22, a guide attachment portion 114 to which the chain guide 110 is detachably attached and a guide attachment portion 116 to which the chain guide 112 is detachably attached are formed. The guide attachment portion 114 includes an attachment groove 114a for receiving the guide portion 110a and an engaged portion 114b with which the engaging portion 110b engages. The guide attachment portion 116 includes an attachment groove 116a for receiving the guide portion 112a and an engaged portion 116b with which the engaging portion 112b engages. With such a configuration, even when the chain guides 110 and 112 are damaged by contact with the source chain 8, the replacement work for the new chain guides 110 and 112 can be easily performed.

[0046] As shown in FIG. 14, a chip guide 118 is further attached to the left surface of the sprocket cover 22. The chip guide 118 is made of a rubber material such as nitrile rubber. As shown in FIG. 15, the chip guide 118 includes a first guide portion 120, a second guide portion 122, a third guide portion 124, and a support portion 126. The first guide portion 120, the second guide portion 122, the third guide portion 124, and the support portion 126 are integrally formed without joints. The first guide portion 120 includes a guide surface 120a formed in a substantially cylindrical surface shape. The radius of curvature of the guide surface 120a is within the range of 24 mm to 36 mm, for example, 30 mm. The second guide portion 122 includes a guide surface 122a formed in a substantially cylindrical surface shape and a guide surface 122b formed in a substantially flat shape. The radius of curvature of the guide surface 122a is within the range of 4 mm to 10 mm, for example, 6 mm. The longitudinal length of the guide surface 122b is within the range of 30 mm to 40 mm, for example, 34 mm. The guide surface 122a is connected to the guide surface 120a at one end and connected to the guide surface 122b at the other end. The third guide portion 124 includes a guide surface 124a formed in a substantially cylindrical shape and a guide surface 124b formed in a substantially flat shape. The radius of curvature of the guide surface 124a is within the range of 3 mm to 7 mm, for example, 5 mm. The longitudinal length of the guide surface 124b is within the range of 14 mm to 25 mm, for example, 18 mm. The guide surface 124a is connected to the guide surface 122b at one end and connected to the guide surface 124b at the other end. The support portion 126 includes engagement holes 126a, 126b, and 126c. As shown in FIG. 16, a guide attachment portion 128 to which the chip guide 118 is detachably attached is formed on the left surface of the sprocket cover 22. The guide attachment portion 128 includes engagement pins 128a, 128b, and 128c that engage with the engagement holes 126a, 126b, and 126c. With such a configuration, even when the chip guide 118 is damaged by contact with the so-called chain 8, the replacement work for the new chip guide 118 can be easily performed. As shown in FIG. 14, a guide rib 22a having a substantially flat plate shape protruding leftward is formed on the left surface of the sprocket cover 22.When the chip guide 118 is attached to the sprocket cover 22, the lower surface of the guide rib 22a and the guide surface 120a are arranged so that there is almost no step and almost no gap.

[0047] As shown in FIG. 17, when the sprocket cover 22 is attached to the main body housing 24, the guide rib 22a is disposed above the front of the sprocket 72, the first guide portion 120 is disposed above the rear of the sprocket 72, and the second guide portion 122 and the third guide portion 124 are disposed below the rear of the sprocket 72. When the chainsaw 2 is viewed from the right, the center C1 of the curvature circle of the guide surface 120a of the first guide portion 120 substantially coincides with the center C0 of the output shaft 60. When the chainsaw 2 is viewed from the right, the center C2 of the curvature circle of the guide surface 122a of the second guide portion 122 is offset downward and rearward from the center C1 of the curvature circle of the guide surface 120a of the first guide portion 120. The offset amount of the center C2 of the curvature circle of the guide surface 122a rearward from the center C1 of the curvature circle of the guide surface 120a is in the range of 24 mm to 38 mm, for example, 31 mm. When the chainsaw 2 is viewed from the right, when the angle formed by the straight line L1 connecting the connection point P1 of the guide surface 120a and the guide surface 122a and the center C0 of the output shaft 60 with the horizontal plane H is θ1, it is in the range of -10° ≦ θ1 ≦ 25°. Here, θ1 is positive when P1 is below C0 and negative when P1 is above C0. For example, in this embodiment, θ1 = 6°. When the chainsaw 2 is viewed from the right, the center C3 of the curvature circle of the guide surface 124a of the third guide portion 124 is offset downward and rearward from the center C2 of the curvature circle of the guide surface 122a of the second guide portion 122. The offset amount of the center C3 of the curvature circle of the guide surface 124a rearward from the center C2 of the curvature circle of the guide surface 122a is in the range of 10 mm to 30 mm, for example, 19 mm. When the chainsaw 2 is viewed from the right, when the angle formed by the straight line L2 connecting the connection point P2 of the guide surface 122a and the guide surface 124a and the center C0 of the output shaft 60 with the horizontal plane H is θ2, it is in the range of 32° ≦ θ2 ≦ 50°. Here, θ2 is positive when P2 is below C0 and negative when P2 is above C0. For example, in this embodiment, θ2 = 41°.

[0048] By arranging the guide rib 22a as described above, the passage area of the chain passage 99 above the front of the sprocket 72 can be narrowed, and it is possible to prevent chips from entering deep into the chain passage 99. Further, by arranging the first guide portion 120 as described above, the passage area of the chain passage 99 above the rear of the sprocket 72 can be narrowed, and it is possible to prevent chips from entering deep into the chain passage 99. Furthermore, by arranging the second guide portion 122 as described above, the chips that have entered the chain passage 99 can be easily discharged downward to the rear. By arranging the third guide portion 124 as described above, the chips that have entered the chain passage 99 can be more easily discharged downward to the rear.

[0049] As shown in FIG. 1, the front hand guard 18 includes a guard portion 18a, a left support portion 18b, and a right support portion 18c. As shown in FIG. 5, the guard portion 18a is disposed in front of the upper grip portion 16b of the front handle 16 and protects the hand of a user who grips the upper grip portion 16b. As shown in FIG. 2, the left support portion 18b extends rearward and downward from the lower left end of the guard portion 18a. The left support portion 18b is held by the left housing 10 so as to be rotatable around a rotation shaft 18d (see FIG. 8) extending in the left-right direction in the vicinity of the lower end. As shown in FIG. 11, the right support portion 18c extends downward from the right end of the guard portion 18a. The right support portion 18c is held by the base plate 14a so as to be rotatable around a rotation shaft 18e extending in the left-right direction in the vicinity of the lower end. The rotation shaft 18d (see FIG. 8) and the rotation shaft 18e are arranged substantially in a straight line. For this reason, the front hand guard 18 is rotatable between a normal position raised upward and a stop position pushed forward with respect to the main body housing 24. As shown in FIG. 8, a stop detection switch 129 is provided on the left surface of the base plate 14a. The stop detection switch 129 detects whether or not the front hand guard 18 is in the stop position. The stop detection switch 129 is electrically connected to the control unit 34 (see FIG. 6).

[0050] As shown in FIG. 11, a lock member 130 and a compression spring 132 are provided on the right surface of the base plate 14a. The lock member 130 includes a convex portion 130a that fits into a concave portion 18f formed in the right support portion 18c of the front hand guard 18. The compression spring 132 biases the lock member 130 with respect to the base plate 14a in a direction in which the convex portion 130a fits into the concave portion 18f. Therefore, even when a force in a direction of pushing the front hand guard 18 forward acts, if the force is smaller than a predetermined value, the convex portion 130a is maintained in a state of fitting into the concave portion 18f by the biasing force of the compression spring 132, and the front hand guard 18 is maintained in the normal position. On the other hand, if the force is larger than the predetermined value, the convex portion 130a comes out of the concave portion 18f against the biasing force of the compression spring 132, and the front hand guard 18 rotates from the normal position to the stop position.

[0051] On the right side of the base plate 14a, there are further provided an arm member 134, a link member 136, a brake member 138, a brake band 140, and a compression spring 142. One end of the arm member 134 is fixed to the right support portion 18c of the front hand guard 18. The other end of the arm member 134 is rotatably connected to one end of the link member 136. The other end of the link member 136 is rotatably connected to the brake member 138. The brake member 138 is slidably held by the base plate 14a between a normal position at the rear lower side and a stop position at the front upper side. The brake band 140 is arranged to surround the periphery of the brake drum 76. One end of the brake band 140 is held by the brake member 138. The other end of the brake band 140 is fixed to the base plate 14a. When the front hand guard 18 rotates from the normal position to the stop position, the arm member 134 also rotates together with the front hand guard 18, so that the arm member 134 and the link member 136 are in a bent state, and the brake member 138 moves from the normal position to the stop position. As a result, the brake band 140 contracts in diameter, and the inner peripheral surface of the brake band 140 abuts against the outer peripheral surface of the brake drum 76, and the rotation of the output shaft 60 is braked by the frictional force between the two. When the front hand guard 18 rotates from the stop position to the normal position, the arm member 134 also rotates together with the front hand guard 18, so that the arm member 134 and the link member 136 are arranged in a substantially straight line, and the brake member 138 moves from the stop position to the normal position. As a result, the brake band 140 expands in diameter, and the inner peripheral surface of the brake band 140 separates from the outer peripheral surface of the brake drum 76, and the braking of the rotation of the output shaft 60 is released.

[0052] The compression spring 142 biases the brake member 138 toward the stop position from the normal position. When the front hand guard 18 is in the normal position and the arm member 134 and the link member 136 are aligned substantially linearly, even if the biasing force of the compression spring 142 acts on the brake member 138, the brake member 138 remains in the normal position. However, when an impact acts on the chainsaw 2 due to kickback during cutting work, the arm member 134 and the link member 136 bend slightly, and the biasing force of the compression spring 142 causes the brake member 138 to move from the normal position to the stop position. As a result, the front hand guard 18 rotates from the normal position to the stop position, and the rotation of the output shaft 60 is braked by the frictional force between the brake band 140 and the brake drum 76.

[0053] The oil tank 48 shown in FIG. 6 stores lubricating oil for lubricating the saw chain 8. The oil tank 48 is provided with a cap 144 that is detachable from a replenishing opening 48a (see FIG. 7) for replenishing the oil tank 48 with lubricating oil. As shown in FIG. 2, the cap 144 of the oil tank 48 is exposed outside the left housing 10 and is disposed on the left surface of the front portion of the main body housing 24.

[0054] The oil pump 50 shown in FIG. 6 sucks out the lubricating oil inside the oil tank 48 through the introduction pipe 146 in conjunction with the rotation of the motor 46, and sends out the lubricating oil toward the guide bar 6 through the discharge pipe 148. The lubricating oil sent to the discharge pipe 148 is supplied to the guide bar 6 and the saw chain 8 (see FIGS. 1 - 3) through an oil supply port 14d (see FIG. 11) formed in the base plate 14a. Near the left end of the output shaft 60 of the motor 46, a worm gear 150 for driving the oil pump 50 is fitted. As shown in FIG. 7, the worm gear 150 is disposed on the left side of the bearing 70. The discharge amount of the lubricating oil supplied from the oil tank 48 to the guide bar 6 by the oil pump 50 can be adjusted via an adjustment pin 152 (see FIG. 9).

[0055] As shown in FIG. 2, an adjustment opening 24h through which the adjustment pin 152 can be accessed from the outside is formed in the lower surface of the main body housing 24 (specifically, the lower surface of the left housing 10). The user can insert a tool through the adjustment opening 24h and rotate the adjustment pin 152 to adjust the discharge amount of the lubricating oil in the oil pump 50. In the left-right direction of the chainsaw 2, the adjustment opening 24h is disposed near the left end of the main body housing 24.

[0056] A drain hole 24i communicating with the battery pack housing portion 24a (see FIG. 4) is formed in the lower surface of the main body housing 24 (specifically, the lower surface of the left housing 10). Therefore, even when water enters the battery pack housing portion 24a, it can be drained through the drain hole 24i. Further, as shown in FIG. 18, a drain hole 24j communicating with the inside of the main body housing 24 is formed in the right handle mounting groove 24d of the main body housing 24. Therefore, even when water enters the inside of the main body housing 24, the water can be drained through the drain hole 24j by tilting the chainsaw 2 to the right. Further, since the drain hole 24j is disposed at a position where it is not conspicuous, the appearance of the chainsaw 2 is not impaired. Furthermore, since the drain hole 24j is disposed at a position away from the guide bar 6, it is possible to suppress chips from entering the inside of the main body housing 24 through the drain hole 24j.

[0057] In the chainsaw 2 of the present embodiment, the volume of the base member 14 is 400 cm 3 or more, for example, 500 cm 3 or more, for example, about 550 cm 3 or more. Further, the weight of the base member 14 accounts for 2% or more, for example, 3% or more, for example, about 4% of the total weight of the chainsaw 2 including the guide bar 6, the saw chain 8, and the battery pack B. By using such a large and heavy base member 14, the heat capacity of the base member 14 can be increased, and the temperature rise of the base member 14 can be suppressed.

[0058] In the chainsaw 2 of the present embodiment, the space in which the motor 46 is accommodated and the space through which the saw chain 8 passes are separated by the base member 14. By adopting such a configuration, it is possible to prevent chips from reaching the motor 46 and affecting the operation of the motor 46.

[0059] (Modification example) The chainsaw 2 may be supplied with power via a power cord without attaching the battery pack B.

[0060] The motor 46 may be an outer rotor type DC brushless motor. Alternatively, the motor 46 may be a brushed motor or another type of electric motor.

[0061] The chainsaw 2 may be provided with an engine having an internal combustion engine as a prime mover for rotating the sprocket 72 instead of the motor 46. In this case, it may be configured to rotate the output shaft 60 connected to the sprocket 72 by driving the engine.

[0062] The material of the base member 14 is not limited to a magnesium alloy, and any heat conductive material having a thermal conductivity of 10 W / m·K or more at a temperature of 300 K may be used. For example, a metal material such as austenitic stainless steel may be used, or a non-metallic material may be used.

[0063] The chip guide 118 may be detachably attached to the right surface of the main body housing 24 (specifically, the right surface of the brake cover 20) instead of the left surface of the sprocket cover 22. Further, the chip guide 118 may not be provided with the third guide portion 124. Furthermore, in the chip guide 118, the first guide portion 120, the second guide portion 122, and the third guide portion 124 may be formed as separate parts, and each may be detachably attached to the sprocket cover 22 or the main body housing 24.

[0064] As described above, in one or more embodiments, the chainsaw 2 includes a saw chain 8, a guide bar 6 to which the saw chain 8 is attached, a sprocket 72 that runs the saw chain 8 along the periphery of the guide bar 6, a motor 46 having an output shaft 60 connected to the sprocket 72, a cooling fan 62 connected to the output shaft 60, and a base member 14 that holds the guide bar 6. The base member 14 is made of a heat conductive material having a thermal conductivity of 10 W / m·K or more at a temperature of 300 K. The base member 14 includes a base plate 14a (an example of a plate portion) disposed opposite to the motor 46 in a direction along the output shaft 60 (for example, the left-right direction), and a support rib 14b (an example of a rib portion) protruding from the base plate 14a toward the motor 46 side.

[0065] In the above configuration, since the thermal conductivity of the base member 14 is high, when the temperature of the guide bar 6 rises, heat is transferred from the guide bar 6 to the base member 14. And in the above configuration, when the motor 46 is driven, the cooling air by the cooling fan 62 cools the base plate 14a and the support rib 14b of the base member 14, so that heat can be efficiently dissipated from the base member 14. For this reason, according to the above configuration, it is possible to suppress the outer shell portions of the base member 14 and the members in its vicinity (for example, bolts 78, 80, nuts 82, 84, chain catcher 106, spikes 108, etc.) from becoming high temperature due to heat transfer from the guide bar 6.

[0066] In one or more embodiments, the cooling fan 62 is a centrifugal fan. The cooling fan 62 is disposed between the motor 46 and the base plate 14a. The support rib 14b is disposed so as to surround the radially outer side of the cooling fan 62.

[0067] According to the above configuration, the cooling efficiency of the base member 14 by the cooling fan 62 can be further enhanced.

[0068] In one or more embodiments, the heat conductive material of the base member 14 is a magnesium alloy.

[0069] According to the above configuration, it is possible to realize the base member 14 that is lightweight and has a high thermal conductivity while ensuring the required rigidity and strength of the base member 14.

Explanation of Signs

[0070] 2: Chainsaw 4: Main body 6: Guide bar 6a: Long hole 8: Saw chain 10: Left housing 12: Right housing 14: Base member 14a: Base plate 14b: Support rib 14c: Exhaust opening 14d: Oil supply port 16: Front handle 16a: Right fixing part 16b: Upper gripping part 16c: Left gripping part 16d: Lower fixing part 18: Front hand guard 18a: Guard part 18b: Left support part 18c: Right support part 18d: Rotation shaft 18e: Rotation shaft 18f: Recess 20: Brake cover 22: Sprocket cover 22a: Guide rib 24: Main body housing 24a: Battery pack housing part 24b: Battery pack mounting part 24c: Recess 24d: Right handle mounting groove 24e: Lower handle mounting groove 24f: Air supply port 24g: Exhaust port 24h: Adjustment opening 24i: Drain hole 24j: Drain hole 26: Rear handle 28: Rear handle guard 28a: First guard part 28b: Second guard part 30: Power button 32: Power switch 34: Control unit 36: Trigger lever 36a: Rotation axis 38: Trigger switch 40: Lock lever 40a: Rotation axis 42: Grip detection switch 44: Torsion spring 46: Motor 48: Oil tank 48a: Refill opening 50: Oil pump 52: Coil 54: Stator 56: Permanent magnet 58: Rotor 60: Output shaft 62: Cooling fan 62a: Plate 62b: Blade 64: Sensor board 66: Motor case 66a: Air supply opening 68: Bearing 70: Bearing 72: Sprocket 74: Brake base 76: Brake drum 78: Bolt 80: Bolt 82: Nut 84: Nut 86: Engagement pin 88: Engagement hole 90: Rotary-linear motion conversion mechanism 92: Adjusting screw 94: Outer cover 94a: Recess 94b: Fastening opening 94c: Fastening opening 94d: Adjustment opening 96: Sleeve 96a: Bolt opening 96b: Bolt opening 96c: Adjusting screw opening 98: Chain guide 98a: Guide part 98b: Engaging part 99: Chain passage 100: Chain guide 100a: Guide part 100b: Engaging part 102: Guide mounting part 102a: Mounting groove 102b: Engaged part 104: Guide mounting part 104a: Mounting groove 104b: Engaged part 106: Chain catcher 108: Spike 110: Chain guide 110a: Guide part 110b: Engaging part 112: Chain guide 112a: Guide part 112b: Engaging part 114: Guide mounting part 114a: Mounting groove 114b: Engaged part 116: Guide mounting part 116a: Mounting groove 116b: Engaged part 118: Chip guide 120: First guide part 120a: Guide surface 122: Second guide part 122a: Guide surface 122b: Guide surface 124: Third guide part 124a: Guide surface 124b: Guide surface 126: Support part 126a: Engagement hole 126b: Engagement hole 126c: Engagement hole 128: Guide mounting part 128a: Engagement pin 128b: Engagement pin 128c: Engagement pin 129: Stop detection switch 130: Locking member 130a: Protrusion 132: Compression spring 134: Arm member 136: Link member 138: Brake member 140: Brake band 142: Compression spring 144: Cap 146: Introduction pipe 148: Outlet pipe 150: Worm gear 152: Adjustment pin

Claims

1. A chainsaw, a saw chain, a guide bar to which the saw chain is attached, a sprocket that runs the saw chain along the periphery of the guide bar, a motor having an output shaft connected to the sprocket, a cooling fan connected to the output shaft, and a base member that holds the guide bar, wherein the base member is made of a heat-conductive material having a thermal conductivity of 10 W / m·K or more at a temperature of 300 K, the base member has, a plate portion disposed opposite to the motor in a direction along the output shaft, and a rib portion protruding from the plate portion toward the motor side, the cooling fan is a centrifugal fan, the cooling fan is disposed between the motor and the plate portion, and the rib portion is disposed so as to surround the radially outer side of the cooling fan. A chainsaw.

2. The chainsaw according to claim 1, wherein the heat-conductive material is a magnesium alloy.

Images